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Molecular dynamics simulations of a small redox-active protein plastocyanin address two questions. (i) Do protein electrostatics equilibrate to the Gibbsian ensemble? (ii) Do the electrostatic potential and electric field inside proteins follow the Gaussian distribution? The statistics of electrostatic potential and electric field are probed by applying small charge and dipole perturbations to different sites within the protein. Nonergodic (non-Gibbsian) sampling is detectable through violations of exact statistical rules constraining the first and second statistical moments (fluctuation–dissipation relations) and the linear relation between free-energy surfaces of the collective coordinate representing the Hamiltonian electrostatic perturbation. We find weakly nonergodic statistics of the electrostatic potential (simulation time of 0.4–1.0 μs) and non-Gibbsian and non-Gaussian statistics of the electric field. A small dipolar perturbation of the protein results in structural instabilities of the protein–water interface and multi-modal distributions of the Hamiltonian energy gap. The variance of the electrostatic potential passes through a crossover at the glass transition temperature Ttr ≃ 170 K. The dipolar susceptibility, reflecting the variance of the electric field inside the protein, strongly increases, with lowering temperature, followed by a sharp drop at Ttr. The linear relation between free-energy surfaces can be directly tested by combining absorption and emission spectra of optical dyes. It was found that the statistics of the electrostatic potential perturbation are nearly Gibbsian/Gaussian, with little deviations from the prescribed statistical rules. On the contrary, the (nonergodic) statistics of dipolar perturbations are strongly non-Gibbsian/non-Gaussian due to structural instabilities of the protein hydration shell. [ABSTRACT FROM AUTHOR]

We extend the conventional transfer matrix method to include anisotropic features for electron transmission in two-dimensional materials, such as breaking reflection law in pseudo-spin phases and wave vectors, which are not usually considered appropriately in the literature. This method allows us to study transmission properties of anisotropic and stratified electrostatic potential media from a wide range of tunable parameters, which include strain tensor and gating. We apply the extended matrix method to obtain the electron transmission, conductance, and Fano factor for the interplay of a uniaxially strained graphene sheet with external one-dimensional aperiodic potentials. Our results suggest the possibility of visualizing this interplay from conductance measurements. [ABSTRACT FROM AUTHOR]

Magnetically shielded Hall effect thrusters suffer from pole erosion as their life-limiting mechanism. However, the dominant physical mechanism causing this erosion remains unclear, limiting the ability create designs that mitigate erosion and the predictive accuracy of simulations used to aid in design. This paper provides spatially resolved laser Thomson scattering measurements of electron temperature and density in the near field plume of a magnetically shielded Hall effect thruster, traversing the front pole region from the discharge channel centerline to the cathode centerline. The signals are inverted in a Bayesian framework, and the data are compared qualitatively and quantitatively to simulations of the same Hall effect thruster. Based on the electron momentum equation, electron pressure gradient is used as a proxy for the electron-predicted electrostatic potential gradient. To within the accuracy of this approximation, the electron pressure has a minimum immediately in front of the front pole. Hence, ions have an electrostatic potential avenue from the discharge region to the front pole, validating this mechanism of pole erosion. [ABSTRACT FROM AUTHOR]

We present a dynamic density functional theory for modeling the effects of applied electric fields on the local structure of polymers with added salt (polymer electrolytes). Time-dependent equations for the local electrostatic potential and volume fractions of polymer, cation, and anion of added salt are developed using the principles of linear irreversible thermodynamics. For such a development, a field theoretic description of the free energy of polymer melts doped with salts is used, which captures the effects of local variations in the dielectric function. Connections of the dynamic density functional theory with experiments are established by relating the three phenomenological Onsager's transport coefficients of the theory to the mutual diffusion of electrolyte, ionic conductivity, and transference number of one of the ions. The theory is connected with a statistical mechanical model developed by Bearman and Kirkwood [J. Chem. Phys. 28, 136 (1958)] after relating the three transport coefficients to friction coefficients. The steady-state limit of the dynamic density functional theory is used to understand the effects of dielectric inhomogeneity on the phase separation in polymer electrolytes. The theory developed here provides not only a way to connect with experiments but also to develop multi-scale models for studying connections between local structure and ion transport in polymer electrolytes. [ABSTRACT FROM AUTHOR]

The motion of ions in supercapacitor electrodes produces internal stresses that cause viscoelastic strains. In addition, stresses may be due to external forces applied to structural supercapacitors, which are multifunctional materials that simultaneously store energy and carry structural loads. There are currently no thermodynamics-based models for the coupled electro-chemo-viscoelastic response of electrodes. Here, the same thermodynamics model is used for both the viscoelastic response and the electrochemical response. This mathematical equivalence is a reference from which to study coupling between the viscoelastic and electrochemical responses. The model has two inputs (stress or strain and electric potential or specific charge) and two outputs (strain or stress and specific charge or electric potential). The coupling is studied by adding three constants in the free energy. The convexity of the free energy and the stability of the free response limit the magnitude of the coupling. The unit response matrix is derived, and results are given for the time and frequency domains. The effect of an applied potential on stress is shown to be much more significant than the converse effect. The model compares well to an experiment consisting of a cyclic electric current applied during stress relaxation. [ABSTRACT FROM AUTHOR]

In photoelectrochemical cells, promising devices for directly converting solar energy into storable chemical fuels, the spatial variation of the electrostatic potential across the semiconductor–electrolyte junction is the key parameter that determines the cell performance. In principle, electric field induced second harmonic generation (EFISH) provides a contactless in situ spectroscopic tool to measure the spatial variation of electrostatic potential. However, the total second harmonic generation (SHG) signal contains the contributions of the EFISH signals of semiconductor space charge layer and the electric double layer, in addition to the SHG signal of the electrode surface. The interference of these complex quantities hinders their analysis. In this work, to understand and deconvolute their contributions to the total SHG signals, bias-dependent SHG measurements are performed on the rutile TiO2(100)–electrolyte junction as a function of light polarization and crystal azimuthal angle (angle of the incident plane relative to the crystal [001] axis). A quadratic response between SHG intensity and the applied potential is observed in both the accumulation and depletion regions of TiO2. The relative phase difference and amplitude ratio are extracted at selected azimuthal angles and light polarizations. At 0° azimuthal angle and s-in–p-out polarization, the SHG intensity minimum has the best match with the TiO2 flatband potential due to the orthogonal relative phase difference between bias-dependent and bias-independent SHG terms. We further measure the pH-dependent flatband potential and probe the photovoltage under open circuit conditions using the EFISH technique, demonstrating the capability of this contactless method for measuring electrostatic potential at semiconductor–electrolyte junctions. [ABSTRACT FROM AUTHOR]

I present an exact solution of the Poisson–Boltzmann equation for two parallel plates and discuss the solution properties. I discuss in more detail plates with opposite charges: In this case, there are two critical separations, Lc,1 < Lc,2. For separations less than Lc,1, the force between plates is repulsive. It switches to attractive at Lc,1, but with the electric potential having the same sign on both plates. For L > Lc,2, the force remains attractive, and the potential at the plates has the same sign as the charge on each plate. I also describe charge regulation, determined by pKa, and provide formulas for both the critical distance where oppositely charged plates repel and their charging process. The implications of these results for the nanoparticle assembly, as driven by electrostatic interactions, are also discussed. [ABSTRACT FROM AUTHOR]

An analytical linearized mean-field theory is presented to describe the adsorption behavior of polyelectrolytes near charged colloidal surfaces with additional short-ranged non-electrostatic interactions. The coupling between the polyelectrolyte segment density and electrostatic potential is explicitly accounted for in a self-consistent manner. This coupling gives rise to highly non-linear behavior, such as oscillations of the electrostatic potential. We derive analytical expressions for the critical surface charge density σc, after which adsorption takes place, and recover the well-known σ c ∼ n s 3 / 2 scaling regime, where ns is the salt concentration. In addition, the theory yields a new n s 1 scaling regime if the surface is hard and a unified n s 1 scaling regime if the surface also possesses some short-ranged attraction with the polyelectrolyte. Furthermore, we derive an analytical expression to describe the critical polyelectrolyte concentration φc to achieve complete charge reversal, which is found to scale as φc ∼ σ2/(f2c2), where c is related to the magnitude of short-ranged interactions and f is the average charge per monomer of the polyelectrolyte. It is observed that within our theory, complete charge reversal can only take place if the short-ranged interactions are sufficiently strong to completely compensate for the entropy loss of adsorption. [ABSTRACT FROM AUTHOR]

This paper presents the first implementation of a coupling between advanced wavefunction theories and molecular density functional theory (MDFT). This method enables the modeling of solvent effect into quantum mechanical (QM) calculations by incorporating an electrostatic potential generated by solvent charges into the electronic Hamiltonian. Solvent charges are deduced from the spatially and angularly dependent solvent particle density. Such a density is obtained through the minimization of the functional associated with the molecular mechanics (MM) Hamiltonian describing the interaction between the fluid particles. The introduced QM/MDFT framework belongs to QM/MM family of methods, but its originality lies in the use of MDFT as the MM solver, offering two main advantages. First, its functional formulation makes it competitive with respect to sampling-based molecular mechanics. Second, it preserves a molecular-level description lost in macroscopic continuum approaches. The excited state properties of water and formaldehyde molecules solvated into water have been computed at the selected configuration interaction (SCI) level. The excitation energies and dipole moments have been compared with experimental data and previous theoretical work. A key finding is that using the Hartree–Fock method to describe the solute allows for predicting the solvent charge around the ground state with sufficient precision for the subsequent SCI calculations of excited states. This significantly reduces the computational cost of the described procedure, paving the way for the study of more complex molecules. [ABSTRACT FROM AUTHOR]

Surface-specific nonlinear optical techniques are ideally suited to investigate the complex structure of aqueous interfaces. For colloidal particles dispersed in aqueous solutions, interfacial properties can be retrieved with angle-resolved second harmonic scattering (AR-SHS). The mathematical framework of AR-SHS does not require a priori knowledge on the electrostatic distribution in the first few nanometers close to the interface, therefore allowing us to formulate a molecular-level description of the electrical double layer (EDL) based on the experimental data. However, farther away from the interface, an analytical form of the electrostatic potential decay is necessary to account for the distance dependence of the surface electrostatic field propagating into the solution. This requirement is especially important at low ionic strengths, where the electrostatic field is not efficiently screened by counterions. Here, we examine to what extent the analytical form of the electrostatic potential decay impacts the AR-SHS data analysis. We analyze the effect of different functions on the scattering form factors, on the integrated AR-SHS signal intensity, and on the surface parameters extracted from fitting the AR-SHS data. We find that the trends of the surface parameters remain similar regardless of the chosen function, demonstrating the robustness of our approach to establish a molecular-level picture of the EDL. At ionic strengths <10−4M for 100-nm diameter particles, a functional form that physically represents counterions packed more densely in the vicinity of the surface than in the case of the Poisson–Boltzmann distribution has the largest impact, resulting in an overestimation of the obtained surface potential. [ABSTRACT FROM AUTHOR]

The conventional electrostatic solutions for two-dimensional (2D) electrodes possess edge singularities for the surface charge density σ and the normal component of the electric field E n. These singularities are generally non-physical because they admit infinite gradients of the concentration of free charge carriers. In particular, they are unacceptable in the studies of the local field sensitive effects, such as the electric breakdown and the ferroelectric domain reversal. We claim that account for diffusion of free charge carriers leads to the disappearance of the edge singularities. This generalization occurs consistently within the same basic concept of conduction. Specifically, we consider the case of U -biased circular disc electrode of radius a. Account for diffusion leads here to a strongly nonlinear integral 2D equation for the electrostatic potential φ (r). Numerical solution of this equation shows that the law σ (a) ∝ U 2 / a takes place. Outside a close vicinity of the disc edge, we stay close to the conventional electrostatic solution for φ and σ. [ABSTRACT FROM AUTHOR]

The electronic structures of three highly mismatched alloys (HMAs)—GeC(Sn), Ga(In)NAs, and BGa(In)As—were studied using density functional theory with HSE06 hybrid functionals, with an emphasis on the local environment near the mismatched, highly electronegative atom (B, C, and N). These alloys are known for their counterintuitive reduction in the bandgap when adding the smaller atom, due to a band anticrossing (BAC) or splitting of the conduction band. Surprisingly, the existence of band splitting was found to be completely unrelated to the local displacement of the lattice ions near the mismatched atom. Furthermore, in BGaAs, the reduction in the bandgap due to BAC was weaker than the increase due to the lattice constant, which has not been observed among other HMAs but may explain differences among experimental reports. While local distortion in GeC and GaNAs was not the cause for BAC, it was found to enhance the bandgap reduction due to BAC. This work also found that mere contrast in electronegativity between neighboring atoms does not induce BAC. In fact, surrounding the electronegative atom with elements of even smaller electronegativity than the host (e.g., Sn or In) consistently decreased or even eliminated BAC. For a fixed composition, moving Sn toward C and In toward either N or B was always energetically favorable and increased the bandgap, consistent with experimental annealing results. Such rearrangement also delocalized the conduction band wavefunctions near the mismatched atom to resemble the original host states in unperturbed Ge or GaAs, causing the BAC to progressively weaken. These collective results were consistent whether the mismatched atom was a cation (N), anion (B), or fully covalent (C), varying only with the magnitude of its electronegativity, with B having the least effect. The effects can be explained by charge screening of the mismatched atom's deep electrostatic potential. Together, these results help explain differences in the bandgap and other properties reported for HMAs from different groups and provide insight into the creation of materials with designer properties. [ABSTRACT FROM AUTHOR]

We investigate the polarization of disk electrodes immersed in an electrolyte solution and subjected to a small external AC voltage over a wide range of frequencies. A mathematical model is developed based on the Debye–Falkenhagen approximation to the coupled Poisson–Nernst–Planck equations. Analytical techniques are used for predicting the spatial distribution of the electric potential and the complex impedance of the system. Scales for impedance and frequency are identified, which lead to a self-similar behavior for a range of frequencies. Experiments are conducted with gold electrodes of sizes in the range 100–350 μm immersed in a high-conductivity KCl solution over five orders of magnitude in frequency. A collapse of data on impedance magnitude and phase angle onto universal curves is observed with scalings motivated by the mathematical model. A direct comparison with the approximate analytical formula for impedance is made without any fitting parameters, and a good agreement is found for the range of frequencies where the analytical model is valid. [ABSTRACT FROM AUTHOR]

This paper presents a new conformal mapping method to solve 2D Laplace and Poisson equations in MOS devices. More specifically, it consists of an analytical solution of the 2D Laplace equation in a rectangular domain with Dirichlet boundary conditions, with arbitrary values on the boundaries. The advantages of the new method are that all four edges of the rectangle are taken into account and the solution consists of closed-form analytical expressions, which make it fast and suitable for compact modeling. The new model was validated against other similar methods. It was found that the new model is much faster, easier to implement, and avoids many numerical issues, especially near the boundaries, at the cost of a very small loss in accuracy. [ABSTRACT FROM AUTHOR]

Gallium oxide (G a 2 O 3 ) is a promising ultra-wide bandgap material offering a large bandgap (> --> 4.7 eV) and high critical electric fields. The increasing demand for electronic devices for high-power applications in electric automobiles, high-performance computing, green energy technologies, etc., requires higher voltages and currents with enhanced efficiency. Vertical transistors, such as fin-shaped field-effect transistors (FinFETs) have emerged to meet the growing need with improved current handling capabilities, reduced resistance, and enhanced thermal performance. However, to fully exploit the Ga 2 O 3 power transistors, precise and reliable physics-driven models are crucial. Therefore, a comprehensive surface potential model has been developed in this work for a vertical Ga 2 O 3 FinFET. The electric potential across the channel is explained by analyzing the two-dimensional (2D) Poisson equation employing parabolic approximation. Such a surface potential model is instrumental in determining the performance of the Ga 2 O 3 FinFET as it affects the threshold voltage, the drain current, and fringing capacitance. Exploiting the surface potentials, a fringing capacitance model is derived which is crucial in analyzing the speed of the device in compact integrated circuits. In addition, statistical analysis of the Ga 2 O 3 FinFET using the Monte Carlo simulation technique is performed to determine the leakage current fluctuation due to doping variations. The validation of the analytical model with experimental results confirms the effectiveness and prospects of the developed models in the rapid development and characterization of next-generation high-performance vertical Ga 2 O 3 power transistors. [ABSTRACT FROM AUTHOR]

Motivated by the booming development of spintronics based on chiral helical microstructures, we employed the standard nonequilibrium Green's function theory to study nonreciprocity and chirality of the heat generation and spin filtering in ferromagnetic helical chains. Our results demonstrate that magnetization, spin–orbit interaction, and nonstep electrostatic potential distribution by bias jointly determine nonreciprocity of the heat generation, and only spin–orbit interaction determines nonreciprocity of the spin-polarized current. Chirality of the heat generation and spin-polarized current is determined by both magnetization and spin–orbit interaction, and some quantitative relationships related to chirality were discovered. However, a transverse field can break these relations and suppress heat generation significantly and modulate nonreciprocity and chirality of the spin-polarized current effectively. By further simulating the critical electrostatic potential distribution, we found with the transverse field applied, compared to the case with zero temperature, that the finite temperature less than one characteristic phonon energy can suppress nonreciprocity of the heat generation while enhancing that of the spin filtering. In terms of chirality, compared to the left-handed helical structure, the right-handed one is more advantageous for designing spin filtering diodes. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is believed to be a rather promising cable insulating material for high‐capacity electric power system with low carbon emission due to its decent thermo‐resistance and recyclable nature. In this paper, a new dually chemical grafting modification strategy by methyl acrylate (MA) and acrylic acid (AA) is put forward to tailor the charge transportation behavior in PP, thus further enhancing the electrical properties. Experimental results indicate that the dually grafted PP with 2.3 weight percent (wt%) MA and 1.9 wt% AA shows enhanced volume resistivity and electrical breakdown strength than pure PP, and the space charge injection is significantly suppressed. This work further adopts thermally stimulated depolarization current (TSDC) test and computational analysis based on density functional theory (DFT) to reveal the mechanism of enhancement. The analysis shows that grafted chemical groups can introduce quantities of deep traps and electrostatic potential wells which are strongly correlated with the carbonyl group and would hinder the charge transportation thus improving the electrical insulating performances of PP. This work would provide a new route of PP‐based dually grafting modification for the development of high‐voltage cable insulation. [ABSTRACT FROM AUTHOR]

Theoretical studies indicate that electric potential saturation in a polar cap ionosphere is regulated by the limited reconnection rate at the magnetopause associated with field‐aligned currents (FACs), predicting the possible saturation of FACs under large interplanetary electric field (IEF). However, recent statistical studies have shown that observed FACs increase linearly with IEF. To reconcile this disparity, numerical experiments are conducted to explore the response of FACs under large IEF. Results show that FACs may exhibit either linear or saturated responses, depending on the Alfvén Mach number. The magnetospheric closure paths of region 1 currents differ significantly between the linear and saturated conditions. In the linear case, essential parts of the region 1 current extend toward dayside and connect to the magnetopause currents, whereas these parts of currents almost disappear in the saturation state. Saturation usually occurs under sub‐Alfvénic solar wind conditions, so the observed FACs generally grow linearly with IEF. Plain Language Summary: Field‐aligned currents (FACs) are highly responsive to fluctuations in the solar wind (SW) and play a crucial role in the coupling between the SW, magnetosphere, and ionosphere. Theoretical models propose that FACs may saturate under high interplanetary electric field (IEF). However, observations from satellites reveal a linear correlation between FACs and IEF. To address this disparity, we conducted comparative global simulations and scrutinized FAC magnitudes and configurations. Our findings unveil distinct structural disparities in FACs between linear and saturated conditions, and show that the FACs saturate when the magnetosheath magnetic pressure is much greater than the thermal pressure, usually under sub‐Alfvénic solar wind conditions. Key Points: Both saturation and linear variations of field‐aligned current may occur with increasing interplanetary electric field (IEF)Region 1 (R1) field‐aligned current structures are different for linear and saturation cases even under the same IEFR1 current saturates when the magnetosheath magnetic pressure is much larger than thermal pressure, possibly under sub‐Alfvénic solar wind [ABSTRACT FROM AUTHOR]

Tuning full‐color emission of polymers holds significant promise. However, preparing unconventional luminescence polymers with color‐tunability in dilute solution and understanding the relationship between non‐covalent interactions and luminescent behavior remains a great challenge. We report two emitters (P1 and P2) incorporating tetracoordinate boron. The P1 with non‐conjugated D‐π‐A structure, exhibited red delayed fluorescence at 645 nm with quantum yield of 9.15 % in aggregates. Notably, the emission wavelength of P1 can be tuned from 418 to 588 nm at different solvent. Similarly, the emission wavelength of P2 can also be adjusted by manipulating the interactions between the solvent and fluorophore. Experimental characterization and theoretical calculations indicate that the B←N bond and electronic interactions between solvent and fluorophore significantly regulate the equilibrium the electrostatic potential (ESP) and the intramolecular O⋅⋅⋅O interactions of P1, thereby modulating its emission wavelength. Additionally, these polymers showed excellent potential in fluoride ions detection. This work provides new insights into the complex effects of intermolecular interactions on luminescent properties. [ABSTRACT FROM AUTHOR]

Molecular stacking behavior exerts a significant influence on the blend film morphology of organic solar cells (OSCs), further affecting device performance and stability. Modulation of the molecular structure, such as central unit and end‐group, can profoundly impact this process. Herein, four quinoxaline (Qx)‐fused‐core‐based non‐fullerene acceptors (NFAs), Qx‐N4F and Qx‐o/m/p‐N4F are synthesized combining π‐extended end‐groups and optimized central units. The isomeric fluorinated central units lead to changes in the local dipole moments and electrostatic potential distribution, which influences the molecular stacking pattern and photoelectronic properties of NFAs. Consequently, binary and ternary devices based on PM6:Qx‐p‐N4F achieve superior power conversion efficiencies (PCE) of up to 18.75% and 19.48%, respectively. Grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) characterization reveals Qx‐p‐N4F's stronger crystallinity, aggregation, and donor–acceptor interactions, which can separately enhance short‐circuit current density (JSC) and fill factor (FF) through higher phase purity and tighter molecular stacking based on maintaining more donor–acceptor interfaces. Furthermore, PM6:Qx‐p‐N4F‐based devices demonstrate exceptional thermal stability, retaining 93.2% of the initial PCE value after 3000 h of heating due to the best morphological stability with the most stable stacking structure. These results underscore the significance of synergistic optimization of NFAs through conjugation expansion and halogenation substitution for obtaining efficient and stable OSCs. [ABSTRACT FROM AUTHOR]

Recently, there has been a surge in research focusing on triazolone-based energetic materials, propelled by their remarkable properties such as good detonation performance as well as acceptable thermal and physical stability. In this work, a novel combination of the triazolone framework with dinitropyrazoles has been attained using the N-methylene-C-linked approach. Different substituents (NH2, NO2, N3, OH) were utilized on the dinitropyrazole moiety to obtain neutral energetic compounds 3–5 and 8. Furthermore, the hydroxy derivative (compound 8) facilitates the formation of energetic salts 9–13 to fine-tune the overall properties further. All the novel compounds 3–13 were thoroughly characterized by IR, multinuclear NMR spectroscopy, high-resolution mass spectrometry (HRMS), and elemental analysis. Compounds 3, 4, 8, and 10 were further confirmed via15N NMR spectroscopy. The structure of compounds 3 and 8 was also confirmed through single-crystal X-ray diffraction studies. The majority of synthesized compounds showed good thermal stability as well as insensitivity toward external stimuli. Computational studies, including analyses such as Hirshfeld surface, non-covalent interaction, electrostatic potential surface, and HOMO–LUMO analysis, were conducted to examine the influence of substitution at the 4th position on the overall stability of compounds 3, 4, and 8. [ABSTRACT FROM AUTHOR]

Thin-walled plates are extensively used in the aerospace industry due to their lightweight properties. However, their low rigidity makes them susceptible to deformation and chatter during traditional machining processes, which increases machining complexity and reduces both quality and efficiency. Therefore, this paper proposes an electrochemical machining method involving the use of a rotating body with complex structured windows as the cathode, enabling pure rolling motion on the workpiece surface. Through the action of an electrolyte and an external power supply, the material is removed from the machined surface layer by layer in the form of ions, thus facilitating the manufacture of complex thin-walled plates. Based on the principles of this method, a kinematics model was established to determine the relative position relationship between the cathode and anode during machining. Additionally, an electric field model and a material dissolution model were established to analyze the electric potential distribution and simulate the process of material removal. The simulation results indicate that the trajectory of the cathode windows forms a "V" shape, with the taper angle being independent of the window angle, but decreasing as the cathode diameter increases. Furthermore, it was observed that the use of an insulation coating can effectively reduce stray corrosion on convex structures of the workpiece surface. Based on these simulation results, electrochemical machining experiments were conducted on nickel-based GH4169 plates measuring 600 × 96 mm with a thickness of 3 mm. The results demonstrate that the average thickness of machined workpieces is 1.1 mm, with a thickness error of 0.12 mm. Meanwhile, the surface roughness Ra is 0.778 μm, with a material removal rate reaching 1.01 cm3/min (8271.9 mg/min). Therefore, electrochemical machining proves to be an effective method for manufacturing thin-walled plates. [ABSTRACT FROM AUTHOR]

Functionalization of cellulose with nanomaterials and functional groups is essential for enhancing its properties for specific applications, such as flexible sensors and printed electronics. This study employs Hartree Fock (HF) and Density Functional Theory (DFT) calculations to investigate the vibrational spectra of cellulose, identifying DFT: B3LYP/3–21 g** as the optimal model aligning with experimental spectra. Using this model, we examined the impact of functionalizing cellulose with various groups (OH, NH2, COOH, CH3, CHO, CN, SH) and graphene oxide (GO) on its electronic properties. The results indicate that cellulose functionalized with GO (Cellulose-GO) has the lowest bandgap energy (0.1687 eV), and improvements in reactivity, stability, and electronic properties were confirmed through Molecular Electrostatic Potential (MESP) and Total Dipole Moment (TDM) analyses. The spectrum of Density of States (DOS) for the cellulose functionalized with different groups shows several peaks, indicating various energy levels where electronic states are concentrated. The Projected Density of States (PDOS) analysis reveals how different functional groups affect the electronic structure of cellulose. Moreover, the (Cellulose-GO) composite was characterized using an Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrometer, revealing interaction through the OH group of CH2OH, as indicated by a new band at 1710 cm−1, consistent with theoretical predictions. Overall, this study demonstrates that functionalization with GO enhances cellulose's responsiveness, degradation, and electrical properties, making it suitable for applications in flexible electronic devices and protective barriers against corrosion. [ABSTRACT FROM AUTHOR]

ABSTRACT Bioelectrochemical systems (BESs) offer a sustainable method for chemical production, including the enhanced production of succinic acid. By combining fermentation with BES, it could be possible to achieve sustainable succinic acid production and CO2 fixation using Actinobacillus succinogenes. In literature, the potential application of BES is commonly associated with increased succinate yields, as it is expected to enhance the availability of NADH, thereby influencing the intracellular nicotinamide adenine dinucleotide (NADH/NAD+) balance. However, it remains unclear whether BES can improve NADH regeneration and achieve higher NADH/NAD+ ratios across all growth phases of A. succinogenes. This study investigates the impact of an applied electrical potential on the intracellular NADH/NAD+ ratio during an electrochemical‐assisted fermentation process. Using an adapted high‐performance liquid chromatography method with a Supelcosil LC‐18‐T column, it was demonstrated that NADH availability in BES, particularly during the stationary growth phase, improved by up to 1.98‐fold compared to the control. This enhancement in reducing power led to a succinate yield of 0.747 ± 0.01 g g−1, representing a 15.65% increase compared to a fermentation without electrochemical assistance. These findings support the expectation that the use of BES could enhance the competitiveness of bio‐based succinate production. [ABSTRACT FROM AUTHOR]

The modulation of the electrostatic potential barrier at grain boundaries determines the performance of many ceramic-based electronics such as varistors. However, conventional protocols relying on complex doping and annealing processes inevitably increase the inhomogeneity of microstructure, which may jeopardize the performance stability and mechanical reliability in service. Instead of doping, herein we demonstrate an effective strategy to modulate the potential barrier in ZnO-based low-voltage varistors by exploiting internal stress-induced piezoelectric polarization. The local residual stress as large as ~1 GPa can be created in the ZnO matrix by incorporating ultra-stiff nanodiamond particles using a cold sintering process. As a result, the composite with only 2 wt% of nanodiamond exhibits a prominent nonlinear current-voltage response at a low switch voltage of 15.7 V/mm, which is ascribed to the depressed barrier height induced by the distinct effects of positively and negatively charged polarization on grain boundaries. More strikingly, the large internal stress can significantly enhance the strength of the composite by more than 230% compared with the monolith, owing to the highly strengthened grain boundaries and crack-tip bridging from prestressed nanodiamonds. These findings add internal stress as a new dimension to design mechanically robust ceramic electronics with high performance. The authors find that the large internal stress induced by prestressed stiff nanoparticles can be exploited as an effective tool to modulate the potential barrier while highly enhance the mechanical reliability of ceramics. [ABSTRACT FROM AUTHOR]

In this study, the density functional theory (DFT) method is used to theoretically investigate the nonlinear optical (NLO) properties of natural carbazoles. The selected carbazoles have significant NLO characteristics. Using the B3LYP/6‐311++G(d,p) and CAM‐B3LYP/6‐311++G(d,p) level theories, the linear optical absorption, HOMO‐LUMO energy gap, molecular electrostatic potential (MEP), and dipole moments were calculated. The first hyperpolarizability (β0), second hyperpolarizability (γ), and static and dynamic linear polarizability (α0) components were computed. Electron correlation was obtained, which was compared with NLO and docking studies showing good relation with both. All carbazole compounds demonstrate good optoelectronic qualities that promote their potential use in electronic devices, as demonstrated by the frequency‐dependent dynamic hyperpolarizabilities of the B3LYP/6‐311++G(d,p) and CAM‐B3LYP/6‐311++G(d,p) functionals at 532 and 1064 nm wavelengths. The results of the molecular docking study shows that CBZ molecules exhibit a strong affinity for both Malassezia globosa (SMG1) lipase targets. The docking data demonstrated a strong binding ability, with CBZ7 and CBZ3. This indicates that CBZ7 and CBZ3 outperform all other compounds and have a high binding capability to the target protein. [ABSTRACT FROM AUTHOR]

Quantitative molecular structure‐reactivity models are useful for generating predictions to guide synthesis design, and in formulating and testing mechanistic hypotheses. We report an expanded multivariate linear regression (MLR) model for the rate of (hetero)aryl (pseudo)halide oxidative addition to L2Pd(0), here exemplified by Pd(PCy3)2. This builds on a prior model from our group, with additional substrate classes (aryl chlorides and iodides) and reaction solvents (THF, toluene, THF/DMF mixture). Overall solvent effects across the entire substrate set are minimal under these conditions, enabling a unified MLR model without introduction of new molecular descriptors beyond the original five. Examining the mechanistic origin of the two molecular electrostatic potential (ESP) descriptors led to generation of a simpler, four descriptor model that is suitable for aryl halides, but not for 2‐halopyridines. Using this model we identified a mechanistic outlier, 2‐pyridyl triflate, which undergoes a nucleophilic displacement oxidative addition that does not involve the adjacent nitrogen atom. Finally, we discuss the relationship between C−X bond strength and oxidative addition rates, and compare the intrinsic bond strength index (IBSI) to bond dissociation enthalpy (BDE) as a bond strength descriptor. [ABSTRACT FROM AUTHOR]

In this paper, we prepared four donor (D)–acceptor (A)–donor (D) compounds utilizing thiophene as D and quinoxaline as A to investigate the efficacy of o-diphenyl side group in preventing aggregation caused quenching (ACQ). The phenyl rings were placed on the quinoxaline core (QT-Ph) and further modified at the para position with decyloxy (QT-Ph-OC10), decanoate (QT-Ph-EstC10), and benzoate (QT-Ph-EstPh) substituents. From UV-Vis spectroscopy, it was found that in solution the compounds exhibit similar absorption patterns with λmax around 440 nm with the exception of QT-Ph-OC10 which had a shorter λmax at 407 nm. In solution, all four compounds exhibited high fluorescence quantum yields at ca. 55% with emission maxima following the optical HOMO–LUMO gap trend. In the solid-state, all compounds experienced varying degrees of red-shift in their absorption and emission compared to solution. ACQ of 50–60% was observed for QT-Ph-OC10 and QT-Ph-EstPh in the solid-state. However, QT-Ph and QT-Ph-EstC10 showed significantly diminished ACQ and retained high quantum yields of 46% and 44%, respectively. The optimized geometries generated by theoretical calculations at the B3LYP/6-31G* level revealed that the dihedral angles between structural subunits may play a key role in the different degrees of ACQ. Notably, the dihedral angle between the quinoxaline and phenyl side group was found to be ca. 40°. The ester group in QT-Ph-EstC10 was orthogonally arranged to the phenyl ring which may have prevented any significant ACQ. Both QT-Ph and QT-Ph-EstC10 proved to be excellent organogelators in several polar and nonpolar solvents. Polarized optical microscopy and scanning electron microscopy on dried gels revealed the existence of one-dimensional fibers. Finally, their potential as fluorescent acid sensors was investigated. While all the title compounds showed fast emission quenching upon exposure to trifluoroacetic acid (TFA) vapor in the solid-state, only QT-Ph-EstC10 demonstrated fast emission recovery upon removal of TFA. The reversibility was discussed with electrostatic potential energy map. The current study demonstrates not only the utility of dangling o-diphenyl groups in reducing ACQ, but also feasibility of further modification that can tune photophysical and assembling properties. [ABSTRACT FROM AUTHOR]

The 2,2,5‐trimethyl‐1,3‐dioxane‐5‐carboxylic acid (TDCA) using both theoretical and experimental methods have been studied. The sample has been subjected to XRD, FTIR, FT‐Raman, (C13 and H1) NMR, and UV–vis spectrum analysis. Then, theoretical calculations have been performed at the DFT/B3LYP/6‐311++G(d,p) higher based scale. The theoretical and experimental geometrical parameters and frequencies have been compared well. Theoretical and experimental NMR chemical shifts have been determined. Absorption wavelengths of UV–Vis spectrum were experimentally measured and compared with TD‐DFT predictions. Detailed explanations have been given for frontier molecular orbitals, low density gradient, distribution of Mulliken charges, molecular electrostatic potential (MEP), RDG, localized orbital location, and electron localized activities. Based on the studied 2D image of the Hirschfield surfaces, H···H (65.6%) and O···H/H···O (33.6%) are found as the controlling interactions. A high binding affinity of −6.5 Kcal/mol has been calculated against 4OAR protein. These theoretical findings of the molecule may be used as an anticancer drug candidate, which helps to explain the structural stability, reactivity and anticancer potential of TDCA. High drug affinity for the TDCA has been detected by in silico ADMET prediction. [ABSTRACT FROM AUTHOR]

The spectral‐luminescence properties and photochemical conversions of phenol were analyzed for an isolated molecule as well as in water solvents in a continuum implicit model and explicit atomistic surroundings. This involved employing cut‐edge hybrid quantum‐classical methodologies to generate static optical spectra and the excited dissipative crossing potential energy curves. A combination of electronic excitations, gradient calculations, and embedding electrostatic potential fitting charges on quantum‐classical molecular dynamic propagation trajectories provided statistically averaged absorption spectra. The mixed‐reference spin‐flip multiconfigurational linear response method based on reference triplet preprocessed in the time‐dependent density‐functional theory was utilized to determine conical intersections between the lowest excited and ground states, as well as two‐stage transitions from the second excitation to the ground state. Non‐adiabatic quantum‐classical molecular dynamics defined photodissipative trajectories of excited states, their lifetimes, and crossing points through trajectory surface hopping together with the mixed‐reference spin‐flip and embedding electrostatic potential fitting approaches. Dyson orbitals of the extended Koopmans' theorem were applied to reveal the nature of molecular states at conical intersections and key points on photodynamic trajectories. Potential hydroxyl group cleavage predicted with conical intersections searching turns to "swift" OH deprotonation through |π→σOH*$$ {\upsigma}_{\mathrm{OH}}^{\ast } $$⟩ transition along photodynamic propagations in contrast with "long" processes leading to benzene ring deformation with stable OH bond. [ABSTRACT FROM AUTHOR]

Achieving excellent thermal and dielectric performance is crucial to prevent premature insulation failure of epoxy in high‐frequency transformers. However, interfaces introduced by embedding micro/nano fillers in epoxy have opposite effects on these properties. Here, the interfacial characteristics of micro‐BN/nano‐Al2O3 epoxy is tailored composites by modifying nano‐Al2O3 with functional amine groups, leading to simultaneous improvements in thermal conductivity and high‐frequency breakdown strength. After modification, thermal conductivity increased from 0.193 to 0.490 W m−1 K−1 at 25 °C, and breakdown strength improved from 85.4 to 94.8 kV mm−1 at 10 kHz. The findings revealed the coexistence of overlapping interfaces between micro‐BN and chemical interfaces between modified Al2O3‐NH2 and matrix in composites. Contrary to the overlapping interface, the chemical interface played a more pivotal role in macroscopic performance. Calculations based on a covalent bonding interfacial model demonstrated that this in‐situ tight interface facilitated phonon transport, thereby enhancing thermal conductivity. Besides the physical structure, an increase in electrostatic potential in the chemical interface also impeded charge migration, resulting in an improved breakdown strength. The synergistic effect of the chemical interface on thermal and dielectric properties presents a promising design strategy for developing high‐performance epoxy composites. [ABSTRACT FROM AUTHOR]

Aqueous Zn‐ion batteries (AZIBs) are promising energy storage systems due to their low cost, excellent safety, and environmental friendliness. However, challenges like uncontrollable dendrite growth and side reactions during battery operation limit their commercialization. Addressing these issues requires regulating ion deposition behavior at the anode/electrolyte interface. The electrostatic shielding effect, which leverages the interplay between electric potential and ionic motion, provides a unique mechanism to inhibit zinc dendrites and side reactions effectively. Despite significant progress in understanding electrostatic shielding in AZIBs, a comprehensive summary of its effects is still lacking. This paper first reviews the primary challenges in AZIBs and then describes how the electrostatic shielding effect can optimize their performance. Existing strategies for achieving electrostatic shielding through anode structure optimization and electrolyte optimization‐are classified and analyzed. Finally, the review summarizes current electrostatic shielding strategies for stabilizing zinc anodes, identifies existing challenges, and discusses the future potential, and for this approach in AZIBs. [ABSTRACT FROM AUTHOR]

The formation of barium sulfate scale is a persistent and formidable challenge across various industrial processes. In order to effectively mitigate this problem, this study proposed the development of an innovative azacrown ether-based macrocycle descaling agent. Using density functional theory, an in-depth analysis of the surface energy of different barium sulfate crystal facets was carried out, together with a detailed investigation into the adsorption properties of the functional groups on the (001) surface. A further comprehensive investigation was carried out to determine how changes in the nitrogen and oxygen atoms in the crown ether framework influence its adsorption affinity to barium ions. In addition, a detailed analysis was carried out to elucidate the molecular interactions between crown ethers with pyridine carboxylic acid side chains and barium sulfate. The newly developed decalcifying macrocycle descaling agent exhibited superior adsorption performance, achieving an adsorption energy for barium ions approximately −4.1512 ev higher than that of conventional DTPA decalcifiers. This remarkable improvement is mainly attributed to the pivotal role of electrostatic forces in the coordination process between the macrocycle descaling agent and barium ions, with an electrostatic potential value reaching −143.37 kcal/mol. This discovery not only introduces a novel approach to the removal of barium sulfate scale but also highlights the significant potential of macrocycle chemistry in industrial applications. [ABSTRACT FROM AUTHOR]

This work focused on analyzing the properties of N‐(5‐nitrothiazol‐2‐yl)furan‐2‐carboxamide (C8H5N3O4S, NTFC) as a possible inhibitor of the rheumatoid arthritis process. The synthesis of NTFC was carried out and good‐quality crystals were obtained and studied by NMR (1H and 13C), DEPT 135, UV–Vis, IR, MS and single‐crystal X‐ray diffraction. The structure of NTFC consists of two rings, thiazole and furan, and a central C—N—C(=O)—C segment, which appears to be planar. This central amide segment forms angles of 2.61 (10) and 7.97 (11)° with the planes of the thiazole and furan rings, respectively. The crystal structure of NTFC exhibits N—H...N, N—H...O and C—H...O hydrogen bonds, and C—H...π and π–π interactions that facilitate self‐assembly and the formation of hydrogen‐bonded dimers, which implies the appearance of R22(8) graph‐set motifs in this interaction. The stability of the dimeric unit is complemented by the formation of strong intramolecular C—S...O interactions of chalcogen character, with an S...O distance of 2.6040 (18) Å. Hirshfeld surface (HS) analysis revealed that O...H/H...O interactions were dominant, accounting for 36.8% of the total HS, and that N—H...N interactions were fundamental to the formation of the dimeric structure. The molecular electrostatic potential (MEP) map showed a maximum energy of 46.73 kcal mol−1 and a minimum of −36.06 kcal mol−1. The interaction energies of molecular pairs around NTFC are highest for those interactions linked by N—H hydrogen bonds. The properties of the NTFC ligand as a potential inhibitor of the DHODH (dihydroorotate dehydrogenase) enzyme were evaluated by molecular docking, showing coupling energies very close to those obtained with the control drug for rheumatoid arthritis, i.e. leflunomide. [ABSTRACT FROM AUTHOR]

This study utilises a combination of density functional theory (DFT) approach, 6-31G (d, p) basis set, and Monte Carlo (MC) simulations. The goal is to understand the relationship between the structure and properties of heterocyclic inhibitors and how they interact with Fe (110) surfaces. Furan, pyrrole, thiophene, pyridine, pyridazine, pyrimidine, indole, benzofuran, carbazole, quinolone, isoquinoline, and imidazole are the chemicals that were looked at in this study. The DFT calculations provide important insights into various properties of the inhibitors, such as molecular structure, dipole moments, electrostatic potential maps, Reduced Density Gradient (RDG), UV spectroscopy, and thermal characteristics. Carbazole has the smallest energy difference (4.789 eV) and the highest softness (0.209 eV−1), It also has the most chemical activity, Furthermore, the Monte Carlo models demonstrate that these derivatives have favourable adsorption energies on the Fe (110) surface. Among them, carbazole shows significant inhibitory potential. The study confirms that the carbazole compound with the biggest negative adsorption energy (−95.495) actually has the smallest energy difference and fits with the MC simulation for adsorption on Fe (110) when it is not charged. Carbazole has much stronger adsorption than oxazole, showing how the structure of a molecule affects how well an inhibitor works. [ABSTRACT FROM AUTHOR]

The conversion of CO2 into valuable chemicals remains a significant challenge for achieving environmental sustainability, primarily due to the stability of the CO2 molecule. This necessitates the development of efficient and ecofriendly catalysts. In recent years, frustrated Lewis pairs (FLPs) have shown promise for CO2 utilization. In this study, we introduce α‐aminodiboronic acid (DBA), a novel trifunctional aminoboronic acid, as an intramolecular FLP for converting CO2 into cyclic carbonate and formic acid. Using density functional theory (DFT) calculations, we explored the reaction mechanism and investigated DBA's electronic structure through molecular electrostatic potential surface (MESP) and natural bond orbital (NBO) analyses. Our results reveal that one −B (OH)2 group induces an unusual state of frustration in the molecule due to charge transfer from the nitrogen atom's lone pair to the π* orbitals, enhancing catalytic performance. The additional −B (OH)2 group serves as an anchoring site for reactive species. The epoxide activation energy is reduced by approximately 27 kcal/mol compared to the uncatalyzed reaction, and the reduction of CO2 occurs with a requirement of 26 kcal/mol. The additional −B (OH)2 plays a crucial role in the catalytic mechanism and minimizes the energies of various structures observed in the reaction path. The reaction energetics align with structural analysis observations, marking this study as the first report on single‐molecule trifunctional FLPs for transforming CO2 into valuable chemicals. [ABSTRACT FROM AUTHOR]

Previous studies on the dynamic problems of magneto-electro-elastic (MEE) beams mainly focused on the buckling and free vibration, no literature paid attention to the low-velocity impact response problem. More importantly, no one conducted the investigation on the nonlinear low-velocity impact of MEE beams with considering the effect of initial geometric imperfection. To fill this gap, this article aims to study the low-velocity impact problem of MEE beams with initial geometric imperfection. Firstly, the nonlinear Hertz contact law is used to describe the displacement and contact force of the MEE beam, and the initial conditions for the beam and impactor are given. Subsequently, considering the multiple coupling effect, the dynamic model is established through Hamilton's principle. Taking the simply-supported boundary condition into account, the Galerkin principle is utilized to reduce the dimensionality, resulting in a nonlinear equation regarding contact time, lateral central displacement and contact force. Meanwhile, two comparative analyses are conducted to confirm the rationality of the present work. Finally, the Runge–Kutta method is employed to solve the low-velocity impact response, in which the effects of electric potential, magnetic potential, initial geometric imperfection, temperature rise, prestress, damping coefficient, the radius and velocity of the impactor as well as the geometric dimension of the beam are discussed. [ABSTRACT FROM AUTHOR]

In this paper, the free and forced vibration behaviors of a piezoelectric semiconductor (PS) cylindrical shell are investigated based on the first order shear deformation theory. According to the constitutive equation as well as geometric relationship, the kinetic energy, strain energy and virtual work of the PS cylindrical shell are obtained. Furthermore, the vibration governing equations of the system are derived by means of Hamilton's principle, and the analytical solutions are acquired for the simply supported PS cylindrical shell. Through numerical examples, the effects of the initial electron concentration, circumferential wave number, geometric parameter and excitation frequency on the natural frequency, damping characteristic, vibration amplitude and induced electric potential of the PS cylindrical shell are discussed. The multi-field coupling characteristic among deformation, polarization and carrier is revealed. The main innovation of the manuscript is that the maximum radial displacement and induced electric potential of the PS cylindrical shell can be effectively controlled by doping different initial electron concentrations, and the damping characteristic of the system is obviously size-dependent. [ABSTRACT FROM AUTHOR]

This paper studies multi-physical fields in a piezoelectric semiconductor (PS) fiber with consideration of heat conduction, pyroelectric, and thermoelectric effects. Based on the three-dimensional (3D) framework of piezoelectricity, drift–diffusion theory, Seebeck effect, and Peltier effect, we develop a highly nonlinear one-dimensional (1D) model that incorporates axial deformation, axial variations of the electric field, the redistribution of carriers, and temperature deviation. Combining the 1D nonlinear governing equations and the corresponding boundary conditions, the influence of the thermoelectric coefficients and axial forces on electrostatic potential, carrier redistribution, and temperature variation are solved numerically. Due to the nonlinearity of the model, these solutions are observed without symmetry or asymmetry. Our research shows that the temperature will increase near the action point of the axial force. Therefore, the temperature deviation in the fiber can be controlled by applying axial force at different points. Finally, we examine how the axial forces applied in the fiber affect the current–voltage relation. The presented study provides a potential application for mechanical switches, sensors, or thermal control for PSs. [ABSTRACT FROM AUTHOR]

• Flexoelectricity and surface effect on piezoelectric nanolaminates were reported. • Analytical solution of bending deformation and vibration were obtained. • Effects of residual surface stress and the flexoelectric coefficient were examined. • Effects of aspect ratio and plate thickness on bending behavior were examined. In this paper, a model of double-layer rectangular piezoelectric nanolaminates with different upper and lower surface properties is established. The bending and vibration behavior of the piezoelectric nanolaminates are evaluated and analyzed, taking into consideration the flexoelectric and surface effects. Utilizing the surface piezoelectric model, flexoelectric theory, and Kirchhoff plate theory, this study provides analytical solutions for the bending deflection and natural frequency of rectangular piezoelectric nanolamination materials under various boundary conditions. The results indicate that the effects of flexoelectric and surface influences on piezoelectric nanolaminates are associated with residual surface stress and flexoelectric coefficients. These effects can enhance the bending stiffness and decrease the natural frequency of the piezoelectric nanolaminates. Furthermore, altering the residual stress on the upper and lower surfaces of the laminates separately will result in different trends in bending deflection, while causing a consistent trend in natural frequency change. When the electric potential direction of piezoelectric nanolaminates is different, the bending deflection of piezoelectric nanolaminates will change accordingly. The natural frequency of piezoelectric nanolaminates is determined by the absolute value of the flexoelectric coefficients, and is independent of their positive or negative values. Both the surface effect and the flexoelectric effect are influenced by size-dependent behaviors. When the thickness of the laminates is sufficiently large, both the surface effect and flexoelectric effect can be disregarded. This paper's research methods and results provide theoretical models and analytical methods for the microstructure design, multi-physical field characterization, and bending deformation behavior of intelligent components containing rectangular piezoelectric nanolaminates. [ABSTRACT FROM AUTHOR]

• A model for the bending of the ssDNA-microbeam with surface charge effect is established. • The electric potential distribution is calculated by using finite difference method and Newton's iteration method. • The surface charge density can modulate the bending of the ssDNA-microbeam. A unified energy model for mechanical deformation of the microbeam included by single stranded DNA (ssDNA) adsorption considering the surface charge density on substrate is investigated. First, a free energy model is established to quantify the deflection and axial displacement of the microbeam, the ion concentration in the solution, as well as the electric potential distribution inside and outside the ssDNA film with a uniform surface charge density. Then, the governing equations and corresponding boundary conditions are obtained by minimizing the free energy with three types of variational variables. And, the relationship of the electric potential difference between the two sides of the ssDNA film and the deformation of microcantilever and simply support beam are determined in different solutions (1: 1, 1: 2, 1: 3). Moreover, the numerical solutions of the electric potential distribution inside and outside the ssDNA film are investigated by using the finite difference method and Newton's iteration method. The results suggest that the nonlinear model for electric potential distribution should be used under higher surface charge density. By fitting and comparing the present predictions with Arroyo-Hernandez's experimental data, the effectiveness of the model is verified. The study shows that the surface charge density can modulate the magnitude and direction of ssDNA-microbeam deformation, which also indicates that there exists a critical surface charge density, causing the failure of ssDNA-microbeam detection. These conclusions are helpful for designing the efficient biosensors based on DNA-microbeam. [ABSTRACT FROM AUTHOR]

Revealing the interaction effect in the nonlinear bending of post‐buckled functionally graded (FG) piezoelectric beams promotes the intelligent development of structural design. The nonlinear bending behavior of post‐buckled piezoelectric beams is studied. Based on the displacement field constructed by the refined beam model, the post‐buckling configuration is considered. The nonlinear geometric relationship and the constitutive relationship in the multi‐physical field are modeled. In the framework of the principle of minimum potential energy, the nonlinear static models of post‐buckled FG piezoelectric beams are established. The post‐buckling configuration is obtained by the extended two‐step perturbation method. To obtain the approximate solution for the static problems of the post‐buckled FG piezoelectric beam, the perturbation scheme of electric potential and generalized displacement is proposed. The detailed parametric analysis indicates the interaction mechanism in the nonlinear bending of the post‐buckled FG piezoelectric beam. The snap‐through process and its sensitive interval are further captured. The back propagation neural network (BPNN) technique developed for the nonlinear bending problem of post‐buckled FG piezoelectric beams achieves accurate prediction. [ABSTRACT FROM AUTHOR]

As the proportion of renewable energy in energy use continues to increase, to solve the problem of line impedance mismatch leading to the difference in the state of charge (SOC) of each distributed energy storage unit (DESU) and the DC bus voltage drop, a distributed energy storage system control strategy considering the time-varying line impedance is proposed in this paper. By analyzing the fundamental frequency harmonic components of the pulse width modulation (PWM) signal carrier of the converter output voltage and output current, we can obtain the impedance information and, thus, compensate for the bus voltage drop. Then, a novel, droop-free cooperative controller is constructed to achieve SOC equalization, current sharing, and voltage regulation. Finally, the validity of the system is verified by a hardware-in-the-loop experimental platform. [ABSTRACT FROM AUTHOR]

In this paper, a novel 3300 V/40 A 4H-SiC junction barrier Schottky diode (JBS) with a multi-step separated trench (MST) structure is proposed and thoroughly investigated using TCAD simulations. The results show that the introduction of MST expands the Schottky contact area, resulting in a decrease in the forward voltage drop. Furthermore, the combination of the deep P+ shielded region and the central P+ region effectively reduces the leakage current, leading to a 43.7% increase in the blocking voltage compared to conventional 4H-SiC JBS. The effects of the step depth (ds) and the width of the central P+ region (wm) on the device performance are analyzed in depth. In addition, a multi-step trenched linearly graded field-limiting rings (MTLG-FLR) termination ensures a more uniform electric field distribution, and the terminal protection efficiency reaches up to 90%, which further enhances the reliability of the terminal structure. [ABSTRACT FROM AUTHOR]

As the large-scale development of wind farms (WFs) progresses, the connection of WFs to the regional power grid is evolving from the conventional receiving power grid to the sending power grid with a high proportion of wind power (WP). Due to the randomness of WP output, higher requirements are put forward for the voltage stability of each node of the regional power grid, and various reactive power compensation devices (RPCDs) need to be rationally configured to meet the stable operation requirements of the system. This paper proposes an optimal configuration method for multi-type RPCDs in regional power grids with a high proportion of WP. The RPCDs are located according to the proposed static voltage stability index (VSI) and dynamic VSI based on dynamic voltage drop area, and the optimal configuration model of RPCDs is constructed with the lowest construction cost as the objective function to determine the installed capacity of various RPCDs. Finally, the corresponding regional power grid model for intensive access to WFs is constructed on the simulation platform to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Cholesterol, an essential lipid of cell membranes, regulates G protein-gated inwardly rectifying potassium (GIRK) channel activity. Previous studies have shown that cholesterol activates GIRK2 homotetrameric channels, which are expressed in dopaminergic neurons of the brain. Deletion of GIRK2 channels affects both GIRK2 homo- and heterotetrames and can lead to abnormal neuronal excitability, including conditions such as epilepsy and addiction. A 3.5 Á cryo-EM structure of GIRK2 in complex with CHS (cholesteryl hemisuccinate) and PIP2 (phosphatidylinositol 4,5-bisphosphate) has been solved. This structure provides the opportunity to study GIRK2 channel gating dynamics regulated by cholesterol using gating molecular dynamics (GMD) simulations. In the present study, we conducted microsecond-long GMD simulations on the GIRK2 channel in its APO, PIP2, and PIP2/CHS bound states, followed by systematic analysis to gain molecular insights into how CHS modulates GIRK2 channel gating. We found that CHS binding facilitates GIRK2 channel opening, with 43 K+ ion permeation events observed, compared to 0 and 2 K+ ion permeation events for GIRK2-APO and GIRK2/PIP2, respectively. Binding of CHS to the GIRK2 channel enhances PIP2 and channel interactions, which is consistent with previous experimental results. The negatively charged PIP2 alters the internal electrostatic potential field in the channel and lowers the negative free energy barrier for K+ ion permeation. [ABSTRACT FROM AUTHOR]

Single crystals of (benzene-1,2-dicarboxylic acid-κO)(2-carboxybenzoato-κO) caesium(I), also known as caesium trihydrodiphthalate (CsADP), were successfully synthesized through a controlled hydrothermal reaction between caesium sulfate and phthalic acid in a 1:2 molar ratio. The resulting crystals, grown over 26–28 days, were analyzed using various techniques. FT-IR spectroscopy revealed characteristic vibrational bands, while powder XRD and single-crystal XRD confirmed phase purity and structural properties. CsADP crystallizes in the orthorhombic system with a centrosymmetric space group (Pbcn). The caesium ion is coordinated by ten oxygen atoms, with Cs···O bond lengths ranging from 3.085 to 3.610 Å, forming a distorted bicapped square antiprism geometry. Thermal analysis indicated stability up to 240 °C, while UV–Vis spectroscopy demonstrated transparency, with a bandgap of 4.17 eV. Nonlinear optical (NLO) properties were investigated using Z-scan techniques, revealing reverse saturation absorption and a strong third-order susceptibility, highlighting CsADP as a promising candidate for NLO applications. Hirshfeld surface analysis identified dominant O···H/H···O interactions, contributing to its NLO behaviour. Additionally, molecular electrostatic potential and Mulliken population analysis provided insights into the charge distribution within the structure. [ABSTRACT FROM AUTHOR]

The generalized Poisson–Boltzmann equation with the uniform ionic size is investigated. In mean-field theory, the ionic size effect is added by modifying the entropy effect of solvent molecules in the electrostatic free-energy functional of ion concentrations. Taking minimization of the mean-field electrostatic free-energy functional including the ionic size effect with respect to the ion concentrations, the minimum free-energy is obtained (see (4.6) in Li [(2009a) "Continuum electrostatics for ionic solutions with non-uniform ionic sizes," Nonlinearity 22(4), 811–833]. Maximizing the minimum free-energy with respect to the electrostatic potential determines the generalized Poisson–Boltzmann equation. By the definition of shape derivative, the first variation of this minimum free-energy with respect to variation of the dielectric boundary is derived. Thus, the dielectric boundary force of an ionic solution with multiple ionic species with the uniform ionic size is obtained. [ABSTRACT FROM AUTHOR]