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The effects of the long range electrostatic interaction in twisted bilayer graphene are described using the Hartree-Fock approximation. The results show a significant dependence of the band widths and shapes on electron filling, and the existence of broken symmetry phases at many densities, either valley/spin polarized, with broken sublattice symmetry, or both., Comment: Invited contribution to a special issue of Nano Materials Science. 12 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:2004.01577

Nematic liquid crystal (LC) droplets have been widely used for the detection of molecular species. We investigate the response of micrometer sized nematic LC droplets against the adsorption of nanoparticles from aqueous media. We synthesized ti 100 nm-in-diameter silica nanoparticles and modified their sur-faces to mediate either planar or homeotropic LC anchoring and a pH-dependent charge. We show sur -face functionality-and concentration-dependent configurations of the droplets consistent with the change in the surface anchoring and the formation of local heterogeneities upon adsorption of the nanoparticles to LC-aqueous interfaces. The adsorption of nanoparticles modified with dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP, homeotropic) exhibit a transition from bipolar to radial, whereas the adsorption of -COOH-terminated counterparts (planar) did not cause a configura-tion transition. By manipulating the electrostatic interactions, we controlled the adsorption of the nanoparticles to the LC-aqueous interfaces, providing access to the physicochemical properties of the nanoparticles. We demonstrate a temporal change in the droplet configurations caused by the adsorption of the nanoparticles functionalized with -COOH/DMOAP mixed monolayers. These results provide a basis for studies in applications for the detection of nano-sized species, for sensing applications that combine nanoparticles with LCs, and for the synthesis of anisotropic composite particles with complex structures. (c) 2021 Elsevier Inc. All rights reserved.

The effect of the surface conductivity on the electrical and mechanical characteristics of the surface dielectric barrier discharge actuator has been numerically investigated in this study. Two typical AC-surface dielectric barrier discharge actuators, wire-to-plate and plate-to-plate have been considered to control airflow alongside a flat dielectric plate. A sinusoidal high voltage of varied frequencies and amplitudes is supplied to the active electrode, and the passive electrode, which is grounded, is encapsulated inside a dielectric plate. Two-species ion transport model, involving generic positive and negative ions, coupled to the electrostatics model is assumed. The electrostatic field is affected by both the space and the surface charges. The surface charge is accumulated due to ion deposition, but its distribution varies due to the surface ohmic conduction. The Navier-Stokes equations for the flow simulation, which include the time-averaged electrohydrodynamic body force determined from the discharge model, are solved to analyze the flow field and the boundary layer morphology. The numerical algorithm has been implemented in the COMSOL commercial package. The significance of the dielectric surface conductivity on the discharge behavior and the flow field has been shown. The dielectric surface conductivity behaves non-monotonically and affects the flow field by altering the EHD force strength, direction and distribution.

Two-dimensional material membranes with fast transport channels and versatile chemical functionality are promising for molecular separation. Herein, for the first time, we reported design and engineering of two-dimensional Ti3C2Tx MXene (called transition metal carbides and nitrides) membranes supported on asymmetric polymeric hollow fiber substrate for water desalination. The membrane morphology, physicochemical properties and ions exclusion performance were systematically investigated. The results demonstrated that surface hydrophilicity and electrostatic repulsion and size sieving effect of interlayer channels synergistically endowed the MXene hollow fiber membrane with fast water permeation and efficient rejection of divalent ions during nanofiltration process.

The electrostatic interaction of RNA with its aqueous environment is most relevant for defining macromolecular structure and biological function. The attractive interaction of phosphate groups in the RNA backbone with ions in the water environment leads to the accumulation of positively charged ions in the first few hydration layers around RNA. Electrostatics of this ion atmosphere and the resulting ion concentration profiles have been described by solutions of the nonlinear Poisson-Boltzmann equation and atomistic molecular dynamics (MD) simulations. Much less is known on contact pairs of RNA phosphate groups with ions at the RNA surface, regarding their abundance, molecular geometry, and role in defining RNA structure. Here, we present a combined theoretical and experimental study of interactions of a short RNA duplex with magnesium (Mg2+) ions. MD simulations covering a microsecond time range give detailed hydration geometries as well as electrostatics and spatial arrangements of phosphate-Mg2+ pairs, including both pairs in direct contact and separated by a single water layer. The theoretical predictions are benchmarked by linear infrared absorption and nonlinear two-dimensional infrared (2D-IR) spectra of the asymmetric phosphate stretch vibration which probes both local interaction geometries and electric fields. Contact pairs of phosphate groups and Mg2+ ions are identified via their impact on the vibrational frequency position and line shape. A quantitative analysis of infrared spectra for a range of Mg2+ excess concentrations and comparison with fluorescence titration measurements shows that on average 20 to 30% of the Mg2+ ions interacting with the RNA duplex form contact pairs. The experimental and MD results are in good agreement. In contrast, calculations based on the nonlinear Poisson-Boltzmann equation fail in describing the ion arrangement, molecular electrostatic potential and local electric field strengths correctly. Our results underline the importance of local electric field mapping and molecular-level simulations to correctly account for the electrostatics at the RNA-water interface.

Particle-laden turbulent flow under saturated electrostatic field in 90-degree bend pipe at Reb = 58000 is investigated using one-way coupled Large Eddy Simulation (LES) with a Lagrangian particle tracking technique. Drag, lift, buoyancy, gravity, and electrostatic force are considered. Three particle sizes (dp = 5, 10, 50 μm, St = 5.47, 21.91, 547) are considered. The results show that particle concentration is higher in outer bend than that in inner bend and the concentration increases with particle size. At the stagnation point of Dean vortices near the inner arc of bend, particle concentration is significantly increased under the synergy effect of electrostatics and secondary flow. In addition, particles trapped in the viscous layer are difficult to resuspend under electrostatic effect. Particle concentration near the wall under the presence of electrostatics is larger than that under the absence of electrostatics. However, at the bend, particle concentration in the core region under the presence of electrostatics is lower than that in the absence of electrostatics. For particle behavior, drag force plays the most important role in the core region while electrostatic force dominates the near wall region and causes particles to accumulate there.

A user-friendly Python-based program has been developed to analyze diffuse scattering from single crystals with the reverse Monte Carlo method. The approach allows for refinement of correlated disorder from atomistic supercells with magnetic or structural (occupational and/or displacive) disorder., A user-friendly program has been developed to analyze diffuse scattering from single crystals with the reverse Monte Carlo method. The approach allows for refinement of correlated disorder from atomistic supercells with magnetic or structural (occupational and/or displacive) disorder. The program is written in Python and optimized for performance and efficiency. Refinements of two user cases obtained with legacy neutron-scattering data demonstrate the effectiveness of the approach and the developed program. It is shown with bixbyite, a naturally occurring magnetic mineral, that the calculated three-dimensional spin-pair correlations are resolved with finer real-space resolution compared with the pair distribution function calculated directly from the reciprocal-space pattern. With the triangular lattice Ba3Co2O6(CO3)0.7, refinements of occupational and displacive disorder are combined to extract the one-dimensional intra-chain correlations of carbonate molecules that move toward neighboring vacant sites to accommodate strain induced by electrostatic interactions. The program is packaged with a graphical user interface and extensible to serve the needs of single-crystal diffractometer instruments that collect diffuse-scattering data.

openaire: EC/H2020/788185/EU//E-DESIGN | openaire: EC/H2020/845060/EU//QMKPFM | openaire: EC/H2020/897828/EU//EIM While offering high resolution atomic and electronic structure, scanning probe microscopy techniques have found greater challenges in providing reliable electrostatic characterization on the same scale. In this work, we offer electrostatic discovery atomic force microscopy, a machine learning based method which provides immediate maps of the electrostatic potential directly from atomic force microscopy images with functionalized tips. We apply this to characterize the electrostatic properties of a variety of molecular systems and compare directly to reference simulations, demonstrating good agreement. This approach offers reliable atomic scale electrostatic maps on any system with minimal computational overhead.

The charge density in a flame contains important information about the combustion processes that is difficult to obtain due to fast, complex, and highly exothermic reactions. This paper presents a study of using electrostatic probes to measure the charge density in methane fired diffusion and premixed flames. The sensing principle, practical design, and performance assessment of the electrostatic probe are presented. Comparative experimental studies with a reference ion-current sensor carried out on a combustion test rig indicate that the fluctuation of the signal from the electrostatic probe arises from the variation in the charge density in a flame. A dimensionless index, combining the average of local peak values in the electrostatic signal with the flame oscillation frequency, is adopted as an indicator of the charge density. Experimental results demonstrate that the charge density in a methane diffusion flame has an increasing trend with the fuel flowrate varying from 0.80 L/min to 1.20 L/min. The charge density in a methane-air premixed flame yields a decreasing trend with the equivalence ratio ranging from 0.54 to 0.75, then increases and reaches a local peak at the equivalence ratio of 1.03, and continues to increase when the equivalence ratio varies from 1.03 to 3.50. The charge density in the inner cone is higher than that in the outer cone for diffusion and premixed flames. The results obtained suggest that the developed electrostatic probe and the index can be used to indicate the charge density in diffusion and premixed flames.

Currently, it is of great significance to develop new proton-conduction materials with high proton conductivity, high stability, and good conducting durability to meet the demands of fuel cell and sensors. Herein, we prepared two composites DETA-HPW@MIL-101-SO3H 1 and TETA-HPW@MIL-101-SO3H 2 (DETA = diethylenetriamine, HPW = H3PW12O40·xH2O, MIL = Material Institut Lavoisier, TETA = triethylenetetramine) by encapsulating polyoxometalate (POM) and organic amine into a sulfonated MIL-101 through a step-by-step dipping method. Delightedly, 1 and 2 have high proton conductivities of 6.4 × 10−2 and 2.9 × 10−2 S·cm−1 at 65 °C and 95% relative humidity (RH), respectively, which can be attributed to the fast proton transfer among acid–base pairs formed between HPW and organic amine as well between sulfonic acid and organic amine. Moreover, the time-dependent test in proton conductivity displays that their proton-conduction properties have good stability and durability, which benefit from that the electrostatic interactions among acid–base pairs and the limitation of opening size of MIL-101-SO3H make HPW and organic amine stably exist in the cages of MIL-101-SO3H. The remarkable proton-conduction properties (high proton conductivity and high stability) of the two composites make them become promising proton-conduction materials.

We present a physics-based circuit-compatible model for pH-sensitive field-effect transistors based on 2-D materials. The electrostatics along the electrolyte-gated 2-D-semiconductor stack is treated by solving the Poisson equation, including the site-binding model and the Gouy–Chapman–Stern approach, while the carrier transport is described by the drift-diffusion theory. The proposed model is provided in an analytical form and then implemented in Verilog-A, making it compatible with standard technology computer-aided design tools employed for circuit simulation. The model is benchmarked against two experimental transition-metal-dichalcogenide (MoS2 and ReS2)-based ion sensors, showing excellent agreement when predicting the drain current, threshold voltage shift, and current/voltage sensitivity measurements for different pH concentrations.

Elastomer materials are very important due to weak intermolecular forces and very low Young's modulus and have high failure strain. Due to these properties, they are used in a large number of applications especially in pharmaceutical industry and medical / surgical equipment etc. Electrostatic discharge on such material is a potential hazard for the operator who is dealing with elastomers. In the research presented here, a detailed analysis on the elasto-electric analysis of 03x elastomers is analyzed in detail by using Finite Element Method (FEM). A CAD model is generated in accordance with an early research on elasto-electric study of Silicon material. Subsequently FEM based analysis is carried out to study vital electrostatics properties like Surface deformation and surface potential distribution developed on the application of external forces on 03x types of elastomers i.e. Silicon Rubber, Nitrile (NBR) and Poly Vinyl Chloride (PVC). The whole study is carried out in COMSOL multi-physics software. Analysis showed that the electric field developed on the surface of the elastomer is dependent on the deformation on non-linear nature and depends upon the material properties. FEM based results show that Silicon Rubber develops maximum deformation and electric potential of three chosen materials up to 50mm and 3150V respectively. Based on the conducted analysis, Silicon Rubber is widely recommended for its utilization in Pharmaceutical applications requiring electrostatics.

With the advantages of high actuation strain and specific power and ability of self-healing after dielectric breakdown, the planar hydraulically amplified self-healing electrostatic (pHASEL) actuators are promising for extensive emerging applications of soft robots. However, the relationship between the output and the input of actuator should be quantified to provide precise driven behavior data for motion mechanism. Due to the interdependence of output length and force, we mainly investigate the voltage-length-force relationship of the pHASEL actuator in this paper. The output forces include electrostatic force, elastic force, and corrective elastic force, namely hydrostatic force. We deduce the electrostatic force model which is approximated to be an infinite parallel capacitor including three dielectric layers. The elastic force is produced by the main elastomer covered by electrode and the marginal elastomer, and they are predicted by Neo-Hookean model under biaxial condition. Since the aggregation of dielectric liquid used in pHASEL causes significant error in the electrostatic force prediction, we suggest calibrating the volume to reduce the error by nearly 50%. The influence by cambered shape elastomer is also deduced. To validate the proposed model, the output forces and the applied voltage under different sizes of pHASEL actuators are measured under different stretching lengths. The results demonstrate that the model can well describe the voltage-length-force relationship.

Nanoscale vacuum (airgap) channels have garnered attention as conduits for ballistic electron transport even under ambient atmospheric conditions. To date only single nanogap devices that cannot be integrated have been developed. This report presents a nanoscale space charge limited field emission (SCL-FE) triode based on a combination of one lateral and two vertical nanoscale airgaps in a Metal-oxide-semiconductor (MOS). Two identical MOS-shared p-Si substrates are separated by a $\sim 50$ -nm-wide etched trench to create a combined lateral bidirectional SCL-FE metal–air device and dual vertical nanoscale vacuum diodes. The lateral device provides bidirectional SCL-FE electron current, and the vertical devices provide rectifying behavior for carrier transport. The ballistic trajectories of electrons within the nanoscale airgap can be controlled by driving the two MOSs in different operational regimes. The triode operates at a low voltage of $\sim 2$ V and has an emission-capture efficiency of up to $\sim 95$ %, with a total emission current density of $\sim 2\times 10^{3}$ A/cm2.

In this work, a Diagonal Tunneling Dielectrically Modulated Tunnel Field Effect Transistor (DT-DMTFET) architecture is proposed for label-free bio-sensing application. The performance of this sensor architecture is comprehensively investigated with the help of extensive numerical device simulations. The architecture has been carefully engineered to exploits the diagonal band to band tunneling (BTBT) component in favor of bio-molecule detection. The essential physics of the transduction mechanism for lateral tunneling, vertical tunneling, and diagonal tunneling-based DMTFETs is extensively analyzed from device electrostatics and transport mechanisms. The transduction efficiency of the sensor devices is quantitatively assessed in terms of current sensitivity, where DT-DMTFET exhibits a sensitivity of 3590 compared to 2514 and 1550 observed in lateral tunneling (LT) and vertical tunneling (VT) dominated DMTFETs, respectively. The optimum sensitivity of DT-DMTFET is observed at 4V and 0.4 V gate and drain biases ranges of operation, where the same is observed at a gate bias of 5V and 7V for LT- and VT- DMTFET, respectively. Furthermore, the device design aspects are studied in detail to identify the relevant structural parameters and subsequently optimize the sensing performance of the DT-DMTFET. Finally, an extensive comparative performance study establishes that the DT-DMTFETs offer more than 50% and 100 % improvements in the current sensitivity compared to their lateral and vertical tunneling-based counterparts, respectively, over a range of bio-molecule sample specifications.

In this paper, a novel n + SiGe pocket layer gate stacked VTFET doping less charge plasma is proposed and analyzed using Silvaco TCAD simulation software. The proposed device will be worked as a transducer sensor which is based upon the principle of the electrostatic charge plasma. The inclusion of doping less charge plasma will ease the device in terms of cost production and form random dopant fluctuation (RDF). The inclusion of charge plasma with gate stacking will enhance the electrostatics control over the gate in order to gain the variation of drain current to boost the current sensitivity. The selection width of the High-K dielectric constant material with SiO2 will filter out using equivalent gate oxide thickness. The physics behind the change is work function of the gate material in the presence of the gas material is the dissociation and absorption of gas molecule via diffusion process to the catalytic gate metal of the device. In addition, n + SiGe pocket layer is introducing to suppress the tunneling barrier at source channel interface due to reduction in the band gap energy material from 1.1 to 0.7 eV. This paper analysis with oxygen and ammonia gases forms different introduced gate metal electrode such as Silver (m1 = 4.26–4.46 eV), Molybdenum (m2 = 4.40–4.60 eV), Ruthenium (m3 = 4.71–4.91 eV), and Cobalt (m4 = 5.0–5.20 eV). In this regard, the current sensitivity, electric filed, surface potential, energy band gap and other electrical characteristics with different drain and gate bias with suitable range is operated. The vertical distribution of the channel concentration will improve the device scalability. To test changes in device sensitivity of the catalytic material of the gate electrode will increases as a work function with the range of 50, 100, 150, 200, and 250 meV. The reported sensitivity (Idon/Idoff) is higher for lower work function i.e. for Silver, Cobalt, Molybdenum and Ruthenium the sensitivity is 4.18 × 102, 3.49 × 102, 1.02 × 103 and 2.79 × 101 respectively.

Core-shell micro-spheres (MS) with both negative and positive charges in the core and only negative charges in the shell were developed as adaptive plugging agents for in-depth conformance control for enhanced oil recovery. The MS were designed to propagate deeply into the reservoir due to the small particle size and electrostatic repulsion between the MS and the sandstone at the initial stage of injection and form aggregates by electrostatic attraction between the cores with mixed charges when the shells degraded at a given time during transportation, leading to an effective plugging of the highly permeable layers with low residual oil saturation. The self-assembling and plugging behaviors of the MS have been studied by Monte Carlo simulation. The results show that charge density (Dcharge), fraction of positive charge (Fp), MS concentration, temperature, and salinity are the key factors influencing the self-assembling behaviors. The electrostatic interaction would become stronger with the increase in Dcharge when it is larger than 0.5. The MS are more likely to form aggregates when Fp approaches 0.5. The higher the concentration of the MS, the stronger the electrostatic interaction between the MS. In addition, electrostatic interactions between the MS become stronger with the increase in temperature and decrease in salinity. Simulation results prove that the MS with mixed charges can effectively and adaptively plug highly permeable layers with low residual oil saturation through self-assembling by combination of electrostatic interactions along with physical bridging, leading to the improvement of oil recovery. Furthermore, block charge distribution will be helpful for the MS with mixed charges to form larger aggregates than that of the random mode to effectively plug the highly permeable layers.

Semiconductor doping is limited by such practical concerns as bandgap narrowing and solid solubility limits of dopants. Bound-charge engineering (BCE) bypasses these limits by doping with surface bound charge located on the interface between a semiconductor and an adjacent low-permittivity oxide; it can be used to reduce depletion lengths of junctions in field-effect transistors (FETs). BCE is established by basic electrostatics and is widely applicable to emerging materials and novel devices. In this work, an analytical surface potential model for gate-all-around BCE-assisted silicon nanowire FETs, with arbitrary and possibly distinct spacer and gate oxides, is derived. This model is based on scaling theory and verified against atomistic quantum transport simulations; it provides an intuitive formalism for developing and modeling devices with BCE.

The self-assembly and structure of nanoparticles containing curved polycyclic aromatic hydrocarbon molecules (cPAHs) are investigated using molecular modelling. These polar fullerene-like molecules are receiving increased attention recently due to the steric and electronic properties caused by the inclusion of five-membered ring(s) within their hexagonal lattice. In this work, the curPAHIP potential is extended to describe the interactions between large cPAHs. It is then used within molecular dynamics simulations to produce nanoparticles containing cPAHs. Structural and energetic metrics, including diameter, density, intermolecular spacing, coordination number, alignment angle, radial distance, and energy value, are used to analyse systems containing cPAHs of different sizes and ratios, and containing flat PAHs or ions. Homogeneous cPAH particles are more tightly packed than their flat PAH counterparts, with large cPAHs displaying stacked columnar configurations absent in nanoparticles containing small cPAHs. Mixing cPAHs of different sizes disrupts the ordered mesophase and forms a core-shell structure in which the larger molecules make up the core and the smaller molecules comprise the shell, although this partitioning is less distinct compared to flat PAHs. In addition, the presence of flat PAHs and ions within cPAH nanoparticles promotes distinct arrangements dominated by weak dispersive interactions and strong electrostatic interactions, respectively.

Electrostrictive polymers having a large strain are desirable for actuation, sensing, and energy harvesting in wearable electronics and soft robotics. However, a high electric field (>100 MV/m) is usually required for current electrostrictive polymers. To realize large electrostriction at reduced electric fields, the fundamental electrostriction mechanism needs to be better understood. In response to this need, the structure and electrostrictive properties of relaxor ferroelectric (RFE) poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] random terpolymers films with different thermal annealing histories were studied in this work. First, the semicrystalline structure of the P(VDF-TrFE-CTFE) terpolymer films was studied by combined small-angle X-ray scattering and wide-angle X-ray diffraction analyses. A three-phase model was employed, namely, crystals and oriented and isotropic amorphous fractions (OAF and IAF). The bulky CTFE units generated taut-tie molecules (TTM) in the crystalline lamella, dividing it into many nanosized crystals (∼1.3 nm thick). It is this unique crystalline structure with nanocrystals and mobile TTM/OAF that enabled the RFE behavior for the P(VDF-TrFE)-based terpolymers. Through electrostriction measurements and nonlinear dielectric analysis, an inverse correlation was observed between the ferroelectric nonlinearity and the electrostrictive coefficient under a high poling electric field (>100 MV/m). This suggested that higher electrostriction performance could be achieved by decreasing the ferroelectric nonlinearity of the RFE terpolymer. Indeed, above the Curie temperature, the paraelectric terpolymer films achieved a high electrostrictive performance with the transverse strain being ∼5% at 200 MV/m. This was attributed to the strong electrostatic repulsion among electric field-induced ferroelectric nanodomains. The finding from this work provides a viable way to design new electrostrictive polymers with higher performance at low driving fields.

In this paper, an improved Poisson-Nernst-Planck ion channel (PNPic) model is presented, along with its effective finite element solver and software package for an ion channel protein in a solution of multiple ionic species. Numerical studies are then done on the effects of boundary value conditions, membrane charges, and bulk concentrations on electrostatics and ionic concentrations for an ion channel protein, a gramicidin A (gA), and five different ionic solvents with up to four species. Numerical results indicate that the cation selectivity property of gA occurs within a central portion of ion channel pore, insensitively to any change of boundary value condition, membrane charge, or bulk concentration. Moreover, a numerical scheme for computing the electric currents induced by ion transports across membrane via an ion channel pore is presented and implemented as a part of the PNPic finite element package. It is then applied to the calculation of current-voltage curves, well validating the PNPic model and finite element package by electric current experimental data.

In this paper, a novel vertically stacked silicon Nanosheet Tunnel Field Effect Transistor (NS-TFET) device scaled to a gate length of 12 nm with Contact poly pitch (CPP) of 48 nm is simulated. NS-TFET device is investigated for its electrostatics characteristics using technology computer-aided design (TCAD) simulator. The inter-band tunneling mechanism with a P-I-N layout has been incorporated in the stacked nanosheet devices. The asymmetric design technique for doping has been used for optimum results. NS-TFET provides a low leakage current of order10−16 A, an excellent subthreshold swing (SW) of 23mv/decade, and negligible drain induced barrier lowering (DIBL) having a value of 10.5 mv/V. The notable ON to OFF current ratio of the order of 1011 has been achieved. The device exhibits a high transconductance of 3.022 × 10−5 S at the gate to source voltage of 1 V. The radiation effect of an alpha particle at different energies on NS-TFET is investigated. The injection causes drain current fluctuation for a short span and the result can serve as a guideline for designing of a robust circuit. NS-TFET shows tremendous improvement in short channel effects (SCE) and is a good option for advanced technologies.

Using amphiphilic molecular brushes to stabilize emulsions usually requires the synthesis of specific side chains, which can be a time-consuming and difficult challenge to meet. By taking advantage of the electrostatic interactions between water-soluble molecular brushes and oil-soluble oligomeric ligands, the in situ formation, assembly and jamming of molecular brush surfactants (MBSs) at the oil-water interface is described. With MBSs, stable emulsions including o/w, w/o and o/w/o can be easily prepared by varying the molar ratios of the molecular brushes to the ligands. Moreover, when jammed, the binding energy of MBSs at the interface is sufficiently strong to allow the stabilization of liquids in nonequilibrium shapes, i.e., structuring liquids, producing an elastic film at the interface with exceptional mechanical properties. These structured liquids have numerous potential applications, including chemical biphasic reactions, liquid electronics, and all-liquid biomimetic system.

While multiscale modeling significantly enhances the capability of molecular simulations of polymer systems, it is well realized that the systematically derived coarse-grained (CG) models generally underestimate the thermomechanical properties. In this work, a charge-based mapping scheme has been adopted to include explicit electrostatic interactions and benchmarked against two typical polymers, atactic poly(methyl methacrylate) (PMMA) and polystyrene (PS). The CG potentials are parameterized against the oligomer bulks of nine monomers per chain to match the essential structural features and the two basic pressure-volume-temperature (PVT) properties, which are obtained from the all-atomistic (AA) molecular dynamics (MD) simulations at a single elevated temperature. The so-parameterized CG potentials are extended with the MD method to simulate the two polymer bulks of one hundred monomers per chain over a wide temperature range. Without any scaling, all the simulated results, including mass densities and bulk moduli at room temperature, thermal expansion coefficients at rubbery and glassy states, and glass transition temperatures (Tg), compare well with the corresponding experimental data. The proposed scheme not only contributes to realistically simulating various thermomechanical properties of both apolar and polar polymers but also allows for directly simulating their electrical properties.

Structural ordering in the concentrated magnetic colloids containing 50 × 5 nm hard magnetic disc-like SrFe12O19 nanoparticles was investigated by cryogenic scanning electron microscopy, optical microscopy, magnetic measurements, and small-angle X-ray scattering. It was revealed that macroscopically homogeneous magnetic liquid consists of dynamic threads of stacked nanoparticles. The threads align into quasiperiodic arrays with the distances between individual threads of a few micrometers. They also can form pseudodomain structures with ~ 90° domain boundaries realized through T-type thread interconnects. The effects of magnetic attraction and electrostatic repulsion on the equilibrium interplatelet distance in the threads were studied. It was demonstrated that this distance can be tuned by the control of the particles charge and electric double layer screening from Stern layer thickness (~ 1 nm) to tens of nanometers. It was shown that the permanent magnetic field is not able to cause any structural changes in the ordered magnetic liquid phase, while alternating field draws particles apart by their vibrations. External variation of interparticle distance up to 6% was achieved using an alternating magnetic field of low intensity. Experimental data were complemented by the theoretical models of screened electrostatic interactions between spherical and platelike magnetic particles. The last model provides good predictive power and correlates with the experimental data. The stabilization energy of the condensed phase in the order of 1–10 kBT was derived from the model. An approach allows controlling of an equilibrium interparticle distance and interparticle distance distribution by adjusting the magnetization and surface charge of the particles as well as the ionic strength of the solvent.

The efficiency of the electrostatic separation of granular plastics wastes depends on the electric charge acquired by the particles in appropriate tribocharging devices. The objective of the present study was the development and functional optimization of new tribocharger design consisting of an assembly of six cylinders, made of polyvinyl chloride (PVC), acryl-methyl butadiene styrene (ABS), or polycarbonate (PC) that can rotate at variable speed and be inclined at a certain angle with respect to the horizontal plane. The performances of the triboelectric charger were evaluated by measuring the charge per mass ratio of the granules collected at the outlet of the device. A first set of experiments involved eight granular polymers, size 2 to 6 mm, originating from waste electric and electronic equipment. The polymers could be arranged in a triboelectric series with respect to the amount of charge acquired in contact to the PVC, ABS, and PC cylinders. A second set of experiments was carried out with polystyrene granules and enabled the choice of the limits of variation of the two factors that were expected to affect the tribocharging: the inclination of the six-PVC-cylinder assembly and its rotation speed. Finally, design of experiments methodology was used for modeling and optimization of the process. The best results were obtained for high rotation speeds and low inclination angles.

Summary Ionic Coulomb blockade is one of the ion transport phenomena revealing the quantized nature of ionic charges, which is of crucial importance to our understanding of the sub-continuum transport in nanofluidics and the mechanism of biological ion channels. Here, we report an experimental observation and plausible theoretical reasoning of ionic conduction oscillations. Our experiment is performed under confinement in sub-nanometer (sub-nm) MoS2 pores with optoelectronic control enabled for active tuning of pore surface charges. Under this charge control, we measure the ionic current at fixed voltages and observe multiple current peaks. Our analytical discussions and molecular dynamics simulations further reveal that the conductance oscillations may originate from the multi-ion interaction at the pore entry, particularly the electrostatic repulsion of ions external to the pore by ions bound inside the pore. Our work adds a further understanding of ionic Coulomb blockade effect and paves the way for developing advanced ionic machineries.

Polyelectrolyte (PE) solutions, which are charged polymers in polar solvents, are ubiquitous and essential to life. Due to the electrostatic interactions among the charged monomers and mobile ions, the dependence of the rheological properties on the polymer concentration of PE solutions differs significantly from that of solutions of uncharged macromolecules. In addition, salt in PE solutions, whether added intentionally or intrinsically present, can affect the properties of the solutions. Here, we analyze the ion distribution near a monomer using the nonlinear Poisson–Boltzmann equation for scenarios with nonoverlapping and overlapping electric double layers. Consequently, by incorporating the electrostatic interactions into the blob model and Zimm–Rouse dynamic model, we obtain different scaling laws for the electrostatic energy per monomer, correlation length, end-to-end distance, relaxation time and viscosity η of semidilute, unentangled PE solutions in consecutive regimes of polymer concentration n p, and salt concentration n s, which are summarized in tables. With our theory, we anticipate that the empirical Fuoss law η ∝ n p 1 / 2 is expected for solutions prepared with salt-contaminated PE samples, while η ∝ n p 0.68 might be found for those with purer PE samples. A new critical charge fraction φ c is defined, where we predict that the peak, which is present in the measurements of the reduced viscosity η / n p as a function of n p, is only expected for weakly charged PEs φ < φ c prepared with pure PE samples. Comparisons with the experimental data as well as the classical scaling theories are provided, and the range of applicability of the theory is discussed.

A novel multi-hydroxyl-containing gemini surfactant (G16) is first designed for modifying silica precursors (SiNPs), with the purpose of fabricating organic adsorbents targeted at methyl orange (MO). The purity of G16 and structural character of the resultant G16-SiNPs are unveiled through Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry-derivative thermogravimetry, scanning electron microscopy, and surface analysis (BET). Compared with SiNPs, G16-SiNPs exhibit enhanced hydrophobicity, enlarged interlayer spacing, and increased thermal weight losses with the modifier availability reaching as high as 100%. Enhanced MO adsorption is obtained from the higher adsorption capacity of G16-SiNPs (401.88 mg/g) than SiNPs (64.72 mg/g), which is more effective than most of the existing silica-based adsorbents. Pseudo-second-order and Langmuir models conform to all adsorption processes, indicating that the adsorption mainly relies on the availability of adsorption sites and characterized by a homogeneous adsorption form. By combining the experimental study and theoretical calculation methods, it can be demonstrated that the as-synthesized adsorbent G16-SiNPs own multi-active sites that contribute to multi-adsorption mechanisms. The partition process, electrostatic interactions, and OH−π interactions are all responsible for the adsorption performance of G16-SiNPs. This study throws light on the exploration of the superb MO adsorbent in aspects of not only the novel structured modifier and precursor but also theoretical analysis for gaining insights into the adsorption mechanism.

Two-dimensional molecular junctions (MJs) are mostly developed by sandwiching molecules between two metal electrodes. Charge transport in molecular junctions is not only determined by the difference between work function of electrodes and HOMO/LUMO of the molecule (≈ energy offset, $${\varepsilon }_{0}$$ ), but also on molecule–electrode electronic coupling strengths ( $${\Gamma }_{g}$$ ). Detailed knowledge of molecule–electrode coupling could reveal its effect on electron transport efficiency. We have examined the modulation of electronic conductance ( $$G$$ ) across bio-molecule/protein-based MJs, where electronic coupling strengths were altered via applied mechanical forces on molecules with conducting-AFM probe. We have utilized numerical tunneling transport models which are developed for MJs and calculated $$G$$ , $${\varepsilon }_{0}$$ , $${\Gamma }_{g}$$ from experimentally obtained current–voltage data. We conclude that the modulation in electronic transport in bio-MJs under applied forces originates from the alteration of $${\Gamma }_{g}$$ , which further incites the alteration of physical structure and variation of electrostatics environment around the chromophore of the protein.

Liquid marbles may be traditionally formed by rolling a droplet on a bed of non-wetting particles resulting in encapsulation and stabilisation. Particles used in this process may range from nanometre to millimetre if handled with sufficient care. This method, however, runs the risk of droplet coalescence and is limited to non-wetting particles. Currently there exist some alternative methods of formulation including using electrostatics to either deliver a particle bed to the droplet or pull the droplet to the particles. The former has shown some promise in potential batch processes but is hindered by interparticle forces. Additional production methods include a form of blender, but this has shown to be unable to produce marbles of a narrow size distribution. Once formed, liquid marbles have demonstrated value as potential blood typing devices, as micro-reaction vessels due to the inherent barrier between the internal phase and the substrate whilst maintaining gas permeability, and as contaminant sensors. Liquid marbles also demonstrate a remarkable level of elasticity under compressive force and reduced evaporation rates when compared to bare water droplets, a function of the size and composition of the stabilising particles. In addition to this, liquid marbles have been proposed as actuators. Locomotion may easily be induced in these structures, using electrostatics, sound, magnetism or light depending on the particle/liquid combinations used in formation, and the environment of deployment. This review seeks to present and summarise recent advances in the field of liquid marble manufacture and methods for actuation. We also aim to highlight potential future avenues of further study within this arena.