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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]

The chemical transformations of substituted chromones 1a–c were examined toward some nucleophiles namely dimedone (R1), 4-hydroxycoumarin (R2) and 4-hydroxy-1-methylquinolin-2(1H)-one (R3). DFT computation at the B3LYP/6-311 G(d,p) level of theory was used to perform the theoretical computations for the produced compounds. HOMO and LUMO analyses were performed to determine the electronic charge distribution and reactivity of the molecules. Molecular electrostatic potential (MEP) surface analysis was utilized to predict the molecule's reactive sites. Moreover, the studied compounds showed NLO characteristics, where they have first order hyperpolarizability greater than urea. In addition, the GIAO method was used to estimate the 1H-NMR and 13C-NMR chemical shifts; and the findings were compared with experimental values. Testing the generated compounds for antibacterial and anticancer activities revealed varied degrees of inhibitory effect. According to the Lipinski, Veber, and Egen rules, these compounds exhibit physicochemical properties. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of benzyl 4-([1,1'-biphenyl]-4-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate are described. Single crystal X-ray diffraction of title molecule was used to investigate the crystal structure. The most stable optimised structure was identified using the B3LYP/6-31 + G(d) method. IR, 1H-NMR and elemental analysis of the title compound were performed. Besides, frontier molecular orbitals, molecular electrostatic potential, and thermodynamic properties were investigated by theoretically. In order to explore the nonlinear optical properties were performed theoretically. Hirshfeld analysis was also performed to determine the interactions of the molecule. [ABSTRACT FROM AUTHOR]

Nowadays, there is an increasing focus on cancer as a major cause of death. Therefore, comprehending the chemical reactivity, geometric and electronic structures of inhibitors can aid in the development of better quality and more efficient drugs. In this study, we propose a hybrid compound of Podophyllotoxin (PPT) and vitamin C (VC) as an anti-cancer agent. The PPT and its derivatives are well-known for their anti-tubulin properties. The geometry optimisation and calculation of global chemical reactivity indices (µ = −3.836 eV, η = 2.402 eV, S = 0.416 eV, and ω = 3.061 eV) were performed using the M06/6-311++G (d, p) level of theory. The global reactivity descriptors predict that the PPT-VC compound has more nucleophilic properties compared to Etoposide and Teniposide compounds. Furthermore, the PPT-VC compound exhibits a lower HOMOPPT-VC–LUMOSWCNT gap and a higher adsorption energy (−37.4 kJ mol−1) in the encapsulation process than other derivatives into SWCNT, providing additional evidence of its nucleophilic nature as an effective anti-tubulin agent. Therefore, the PPT-VC@SWCNT compound can be considered a reliable drug delivery system (DDS). Molecular docking analysis reveals that the best cavity of tubulin has an interaction energy of −102.1 kJ mol−1, involving both bonding and non-bonding interactions. [ABSTRACT FROM AUTHOR]

This study investigates the electromechanical performance of piezoelectric sandwich plates both numerically and experimentally. The effect of different inner design parameters, namely the length-to-thickness, core-to-face thickness, boundary conditions and aspect ratio on both the eigenfrequency and electric potential attributes is assessed. Moreover, vibration amplitude-dependent effects are investigated. Polymer-based, sandwich plates are additively manufactured (AM) and commercially available PZT layers are surface-bonded and experimentally probed. AM smart plates are found to yield comparable eigenfrequency properties with the ones reported for fiber-reinforced smart sandwich composites. Low length-to-thickness, low core-to-face, and rectangular rather than square designs favor the electric potential performance. [ABSTRACT FROM AUTHOR]

Corrosion of mild steel has gained a lot of attention by many industries and academia. This study was aimed to find the corrosion inhibition properties of hydrazine and its 11 derived molecules for mild steel using computational method, namely, the density functional theory with Beck 3‐parameter Lee Yang and Parr functional along with the 6‐311++G (d, p) basis set using simple quantum chemical parameters. The main quantum chemical parameters were energies of highest occupied and lowest unoccupied molecular orbitals and their energy gap, dipole moment, hardness, softness, electrophilicity index, the fractions of electrons transmitted, the change energy back‐donation, electron‐donating power, electron‐accepting power, molecular electrostatic potential, and Fukui function as well as polarizability. The results indicated that hydrazine derivatives have good anticorrosion nature which is consistent with the experimental findings. Out of the 12 target inhibitor molecules, N′‐(3‐nitrobenzylidene) hydrazine carbodithioic acid (NBHCA) and N′‐(4‐dimethylaminobenzylidene) hydrazine carbodithioic acid (DABHCA) are the most effective inhibitors. According to the value of the quantum chemical parameters, EHOMO, ΔEgap, Χ, η, σ, ε, ΔN, α, and ΔEb-d DABHCA showed the top effective anticorrosion inhibitor, and by the value of the quantum chemical parameters, ELUMO, TE, ω−, and ω+ NBHCA showed an effective anticorrosion inhibitor. The quantum chemical parameter data showed that NBHCA and DABHCA are nearly equivalent in their values, which is consistent with experimental values. Furthermore, a multiple‐linear regression equation was proposed as a quantitative structural activity relationship model to relate the calculated molecular descriptors of hydrazine derivatives to their experimental inhibition efficiencies obtained from literature. As a result, this model showed an excellent accuracy with an R‐squared of 0.924 and this uses to predict inhibition efficiencies of another molecules. [ABSTRACT FROM AUTHOR]

In the last decade, with the development of the electric vehicle industry and their acceptance in human societies, the participation plan of electric vehicles in supplying the load of the network has been taken into consideration. One of the requirements of this plan is the optimal location of the stations for these vehicles in the network so that they play an effective role in the operation of the network. In this regard, along with the construction of charging and discharging stations for electric vehicles, the construction of renewable sources in the network can play a complementary role for these stations. In this paper, the effect of using renewable resources as a supplement for smart charging stations and the placement of these stations to achieve technical and economic goals have been investigated. In order to manage the demand on the side of consumers and even out the load curve, the time of use mechanism as one of the demand response programs has been considered in this study. In this research, the improved nondominant sorting genetic algorithm is proposed to solve the problem, and the results of the proposed method are also compared with the conventional genetic and particle swarm optimization algorithms. All the simulations have been done in the MATLAB software and on the IEEE 33‐bus network. Based on the obtained results, after the implementation of the proposed plan in the distribution network, the objective functions of the loss, voltage drop, and the total cost have been reduced by 13.6%, 58.7%, and 54.4%, respectively, compared to the base conditions of the network. [ABSTRACT FROM AUTHOR]

Piezoelectricity is a well-known effect in a vast number of technologically important insulators and semiconductors and exists in 20 out of the 32 three-dimensional crystal classes. The piezoelectric effect is the driving mechanism behind several classical sensors and transmitters, and also most recently, in many nanodevices. Zhong Lin Wang coined the fields piezotronics and piezo-phototronics where the piezoelectric effect plays a dominant role. Piezoelectricity couples in a linear fashion mechanical strain to electrical fields and vice versa. In solids, there is another linear coupling between strain and the electric potential, known as the deformation potential effect. While linear in its coupling nature, this effect does not require the solid to be non-centrosymmetric in contrast to the piezoelectric effect. Moreover, the deformation potential effect is quantitatively huge and leads to changes in the conduction and valence band edges of III–V and II–VI materials of, typically, 50–100 meV in the presence of 1 % strain. Therefore, the deformation potential effect is essential to determine the electronic and photonic properties of bulk and nanostructure semiconductors in the presence of strain. In this work, we compute the relative importance of piezoelectricity and the deformation potential effect in the presence of lattice mismatch and external strain. We choose p − n junctions of ZnO/GaN structures but anticipate that the general conclusions can be carried over to other material structures. The main result of the present work is that both the inclusion of the deformation potential effect and piezoelectricity is crucial to correctly compute the effect of strain on p − n junction current–voltage curves and photonic properties. In our analysis of wurtzite heterostructures, the spontaneous polarization effect is also included but this effect appears to play a minor role for electronic and photonic properties. [ABSTRACT FROM AUTHOR]

In X‐ray structures of the isomorphic mer‐[IrX3(THT)(CNXyl)2] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6‐Me2C6H3−) complexes, we revealed short intermolecular contacts between the C‐atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X‐ray data and analysis of appropriate DFT studies allowed the attribution of these contacts to CMe⋅⋅⋅X−IrIII (X=Cl, Br) tetrel bond. Specifically, through the application of DFT calculations and various theoretical models, the presence of tetrel bonding interactions was validated, and the contribution of the CMe⋅⋅⋅X−IrIII interaction was assessed. The reinforcement of the tetrel bond upon the isocyanide coordination to iridium(III) is substantiated by molecular electrostatic potential (MEP) surface calculations. To distinguish the tetrel bonding characteristics of CMe⋅⋅⋅X−IrIII (X=Cl, Br) interactions from conventional hydrogen bonding, we employed multiple computational methodologies, including Natural Bond Orbital (NBO) analysis and Electron Localization Function (ELF) analysis. Additionally, Energy Decomposition Analysis (EDA) was applied to selected model systems to explore the underlying physical nature of these interactions. [ABSTRACT FROM AUTHOR]

Low hydroxide conductivity and insufficient alkaline stability are the main problems currently facing anion exchange membranes (AEMs). Conventional quaternary ammonium groups have limited resistance to attack by hydroxide roots. In this paper, quaternary ammonium-type (Cn-PFCO (n = 2, 5)) perfluoroanion exchange polymers with carbonyl side chains were synthesized. The C5–PFCO exhibited an impressive conductivity of 113.4 mS cm−1 at 80 °C, and remarkably, it retained 86.87% of its initial conductivity even after 15 days of immersion in a 1 M KOH aqueous solution. This excellent alkali resistance is due to the generation of intermediate oxygen anions from OH− and carbonyl groups through a reversible reaction. These anions effectively reduce the likelihood of S N 2 attack by diminishing the electrostatic potential of the QA groups from Density Functional Theory (DFT) calculations. The electrostatic potential of C2–PFCO is 6.28 eV, while it decreases to 2.69 eV after the formation of intermediate anions. Furthermore, we also used the prepared AEM for pure water electrolysis to explore its performance. The electrochemical performance of AEMWE exhibited remarkable results when supplied with pure water, demonstrating an impressive current density of 262 mA cm−2 at 1.9 V. This study introduces a novel strategy for concurrently enhancing hydroxide conductivity and alkali resistance in AEMs by analyzing the potential for further improvement in AEMs' alkali resistance. [Display omitted] • The AEM with tetrafluoroethylene backbone maintains excellent physicochemical stability. • The presence of carbonyl groups enables sustainable mitigation of hydroxide attacks. • DFT calculations revealed that the ESP of the Cn-PFCO membrane was notably lower (2.69 eV). • The prepared AEM demonstrated excellent alkaline stability in long-term testing. [ABSTRACT FROM AUTHOR]

The electrostatic potential within porous materials critically influences applications like gas storage, catalysis, sensors and semiconductor technology. Precise control of this potential in covalent organic frameworks (COFs) is essential for optimizing these applications. We propose a straightforward method to achieve this by employing electric quadrupolar building blocks. Our comprehensive models accurately reproduce the electrostatic potential in 2D-COFs, requiring only a few parameters that depend solely on local electrostatic properties, independent of the COF's lattice structure and topology. This approach has been validated across various systems, including conjugated and non-conjugated building blocks with different symmetries. We explore single-layer, few-layer, and bulk systems, achieving changes in the potential which exceed one electronvolt. Stacking configurations such as eclipsed AA, serrated AA', and inclined stacking all exhibit the tuning effect with minor variations. Finally, we discuss the impact of these potential manipulations on applications like ion and gas uptake. [ABSTRACT FROM AUTHOR]

The doubly-fed induction generator (DFIG) is vulnerable to overcurrent at the stator winding and overvoltage at the DC link due to voltage drop after the grid fault. The large wind farm may have a capacity of several million MWs, whose tripping yields a notable power imbalance and frequency drop in the power systems, which may be avoided by the low-voltage ride-through (LVRT) strategies implemented with the hardware or software. The latter has the merits of low cost and easy to realize, thus studied in this paper. Considering the grid fault uncertainty and DFIG parameters' correlation, this paper newly introduces the sliding mode structure into the passive control to improve the performance of the inner current control loop of the rotor-side converter (RSC), thus proposing a passive sliding mode control (P-SMC) based RSC control strategy to improve the LVRT capability of the DFIG. The time domain analysis with different fault severities, i.e., voltage drops, at the point of public coupling (PCC) is performed. The simulation results with the P-SMC control or not are obtained and compared to verify the control effect and the robustness of the proposed LVRT strategy. This study is beneficial for maintaining power system security against fast-increasing wind power. [ABSTRACT FROM AUTHOR]

Induction motors are the most common type of motor in power systems, constituting approximately 70–90% of the dynamic loads, making them significant contributors to system dynamics. In transient voltage stability analysis, dynamic equivalent models are commonly used to simplify the representation of a group of induction motors. This paper presents a method for the grouping and aggregation of induction motors at a common bus. Firstly, grouping rules are provided for clustering induction motors into several subgroups based on the mechanical principles of rotor force and motion, and aggregation rules are provided for aggregating a motor subgroup into a single-unit model based on the relationship between voltage drop and power transmission in distribution networks. Secondly, guided by the grouping rules, high-speed remaining electromagnetic torque and low-speed remaining electromagnetic torque are defined as new clustering indicators, and an adaptive K-means clustering method using silhouette coefficient verification is introduced to obtain the optimal motor subgroups. Thirdly, guided by the aggregation rules, a dynamic equivalent method is further introduced to obtain the equivalent single-unit model from a motor subgroup. Lastly, a transient voltage stability simulation in a typical distribution network is presented to illustrate that the proposed clustering and equivalent methods are more reasonable, accurate, and effective than traditional methods, as the obtained model has better dynamic characteristics and can more accurately reproduce the process of voltage collapse. [ABSTRACT FROM AUTHOR]

Electric vehicles (EVs) are transforming the transportation sector, driven by the rapid expansion of charging infrastructure, including fast-charging stations (FCSs), significantly reducing charging time compared to standard charging stations. Despite the advantages of faster charging, the substantial power demand of EVs poses significant technical challenges for distribution networks. In particular, the existing literature has a research gap regarding how FCSs may impact or interact with step-voltage regulators' (SVRs) tap operations. In this study, we characterize and evaluate the effects of fast recharging at varying penetration levels (PLs) on SVRs' tap operations using probabilistic simulations and sensitivity analysis. To address these challenges, we propose a local and innovative application of the Volt/Var control on EV fast charging. The proposed application aims to inject reactive power into the network, depending on the FCS's nominal active power, when the bus voltage connected to the FCS exceeds a minimum value. Our research on an actual feeder in northern Brazil reveals that reducing the active power supplied to the vehicle or oversizing the charging station power converters is unnecessary. Furthermore, our strategy reduces the probability of undervoltage violations and minimizes SVR tap changes, mitigating EVs' impact on voltage quality. [ABSTRACT FROM AUTHOR]

Polyelectrolyte brushes (PEBs) are commonly used to modify surface that have attracted great research interest. The dielectric permittivity of the grafted surface is typically significantly different from that of solution, which results in surface polarization (SP) effect with a jump of electric field. It is thus important to study how SP alters the PEB's structure and properties. In this work, the SP effects on PEB structure was studied using a statistical thermodynamic theory. The free energy functional to describe SP effect was constructed by using the image-charge method. Meanwhile, the electrostatic potential was solved from a modified Poisson-Boltzmann equation taking the ion solvation effect into consideration. In the absence of SP, the thickness of PEB exhibited a continuous collapse transition when decreasing the solvent quality. In the presence of SP, the collapse became a jump-like transition. Free energy analysis showed that the long-range Coulombic interaction dominated the transition because of the enhanced counterion condensation in the presence of SP. The theory provides an effective tool to study SP effect on PEBs, and the results explain the underlying physics in PEB collapse transition. [ABSTRACT FROM AUTHOR]

In this study, we have investigated a strategy for designing some novel pyrazoline-thiazole hybrids containing azo moiety. The synthesized compounds were structurally characterized and their antibacterial activity was in vitro evaluated against gram-negative and gram-positive bacteria using the inhibition zone method. The antibacterial activity of the tested compounds was moderate to good. Compound 12c showed the best activity compared to the standard drug (Ampicillin) against S. aureus and E. coli at the concentration of 0.16 mg/mL, with the highest inhibition zone diameters of 34 mm and 37 mm, respectively. Moreover, in silico molecular docking and ADME profile studies were investigated in order to understand the binding affinity and interactions along with the ADME properties of all designed hybrids. Additionally, Density functional theory (DFT) calculations were carried out at the B3LYP/6-311G++ level of theory. The study involved an examination of the optimized geometry, molecular electrostatic potential map, and the HOMO → LUMO electronic energy gap. In accordance with the findings, the newly synthesized hybrids could be beneficial for medicine and exhibit antibacterial activity. [ABSTRACT FROM AUTHOR]

This study computationally investigates the properties and competition of complexes formed by the interaction between hypohalous acids (HOX, where X = F, Cl, Br, and I) and carbonyl selenide (COSe) at the MP2/aug-cc-pVTZ computational level. Three distinct groups of complexes were obtained. The first group, consisting of complexes with a cyclic structure (HB-TB), exhibited the highest stability. remaining two groups formed less stable linear structures with different characteristics (ChB and XB). In the first group, the electronegativity of the halogen atom significantly influenced the stability of the complexes. Conversely, the stability of complexes in groups II and III was primarily determined by the acid and base strengths of the interacting monomers. To comprehensively evaluate the obtained results, various analyses were employed, including Molecular electrostatic potential (MEP), geometry Optimization, Spectroscopic, Interaction energy (SE), Natural bond orbital (NBO) analysis, Atoms in molecules (AIM) analysis, Non-covalent interaction (NCI) index, Energy decomposition analysis (EDA), and Electron density difference(EDD) analysis. [ABSTRACT FROM AUTHOR]

Some novel FeIII, CuII, and PdII chelates incorporating N′‐(1‐methyl‐2‐oxoindolin‐3‐ylidene)benzohydrazide (MIBA) were fabricated. The tested compounds were investigated using thermogravimetric analysis (TGA), CHN, spectra analysis (IR, mass spectra, and NMR), melting point, magnetic moments, molar conductance, ultraviolet–visible spectroscopy, powder X‐ray diffraction, and computational studies. The conductance results showed that the tested FeIII, CuII, and PdII chelates are electrolytes. Magnetic and electronic spectra are applied to deduce the coordinating ability of the tested ligand, and the geometric structure of the studied chelates is found to be octahedral, distorted octahedral, and square planar for FeIII, CuII, and PdII chelates, respectively. The TGA study of these studied complexes displays that the hydrated H2O molecules, acetate, and nitrate are removed in the first and second degradation steps followed directly by degradation of the studied ligand leaving metal oxide as residue. The thermodynamic factors, like ΔS*, ΔH*, E*, A, and ΔG* are evaluated from the TGA curves and explained. The density functional theory (DFT)/B3LYP computation method was applied for the estimation of the molecular electrostatic potential (MEP; highest occupied molecular orbital [HOMO] and lowest unoccupied molecular orbital [LUMO]) energy for the studied compounds. In an in vitro study, the antimicrobial effects of the prepared compounds were screened on various strains of bacteria and fungi. It was found that tested compounds exposed a good biological efficacy through IC50 results close to reference drugs and antitumor potential against (MCF‐7, Hep‐G2, and HC‐T116) cell lines. The data obtained displayed that the studied chelates showed promising antitumor activity. The studied metal chelates were screened for in vitro antioxidant efficacy using DPPH assay. The studied compounds explained dynamic satisfying performance. Also, the crystal structures of breast cancer protein (PDB ID: 3HB5) and Escherichia coli (PDB ID: 2VF5) were performed by molecular docking simulation. Data of docking simulation suggestions are which tested compounds have biological behavior as well as have obvious benefit in the pharmaceutical business. [ABSTRACT FROM AUTHOR]

Summary: According to recent research work, increasing electric power generation is one of the significant advantages of the dual‐rotor wind turbine (DRWT) compared to the other types for the same wind speed. In this research work, a modified super‐twisting sliding mode control (STSMC) based on the neural network (NN) is suggested to regulate the stator powers of a DRWT‐based doubly‐fed induction generator (DFIG) in normal and unbalanced grid fault modes. The design of this strategy involves replacing the gains of conventional STSMC with the NN algorithm to enhance robustness, mitigate the impact of unbalanced grid voltage, and consequently improve the quality of the generated power of DRWT‐based DFIG. This forms the primary contribution of this work. The suggested strategy is compared with vector control (VC) and conventional STSMC in terms of reference tracking, power ripples, response dynamics, harmonic distortion of stator current, and the effect of an unbalanced grid fault. Finally, the utility and effectiveness of the designed controller are confirmed through computer simulations. Furthermore, when the grid is subjected to a 20% voltage drop, the results demonstrate that the suggested strategy reduced the total harmonic distortion (THD) value of the stator current by 12.92% compared to VC and by 9.29% compared to conventional STSMC. [ABSTRACT FROM AUTHOR]

This article examines the use of LEGO bricks as a tool for modeling physics phenomena in laboratory courses. The author provides examples of how LEGO bricks can be used to represent various concepts in physics, such as parabolic trajectories and oscillation graphs. The article also discusses the benefits of using LEGO bricks for inquiry-based learning and fostering students' comprehension and creativity in physics. While the author emphasizes the pedagogical value of LEGO bricks in physics education, they acknowledge the need for further research in this area. The article concludes by clarifying that it is not funded or sponsored by the LEGO company. [Extracted from the article]

Asphalt aging is a natural process that causes changes in the properties of asphalt, particularly in asphalt adhesion. Previous studies show that the effect of aging on asphalt adhesion performance is not uniform and depends on the asphalt source and aging conditions. To investigate the effects of different SARA (saturates, aromatics, resins, and asphaltenes) ratios and structural changes on the adhesive properties of asphalt after aging, this study employs molecular dynamics simulation to calculate asphalt properties such as density, viscosity, and work of adhesion. The above properties were computed for 12 categories of asphalt molecules, individual SARA components, and asphalt models characterised by diverse SARA ratios, followed by a correlation analysis. The study reveals that asphalt aging increases density, viscosity, and adhesion to silica. The increase in polar functional groups, namely ketone and sulfoxide, is responsible for the enhanced adhesion of asphalt to silica due to the resulting increase in electrostatic potential energy. Different SARA ratios lead to different asphalt properties, with the RA/SA index ((asphaltene%+resin%)/(saturate% + aromatic%)) showing a better correlation with the properties. Positive correlations were observed among density, viscosity, and work of adhesion. This study advances our understanding of chemical and structural effects on aged asphalt properties. [ABSTRACT FROM AUTHOR]

The current study deals with the theoretical enquiries of 1-acetyl-4-piperidinecarboxylic acid, a derivative of piperidine. The moiety of piperidine has extensive spread of usages in the field of pharmacology. Employing DFT techniques, theoretical analysis on the caption compound was performed and optimised molecular structure was obtained. Energy gap between HOMO and LUMO along with global reactivity parameters, NLO behaviour, molecular electrostatic potential studies were computed and analysed for the heading compound in gaseous & solvent phases (methanol, ethanol and acetone). On the chemical in the title, topology research such as ELF, LOL and RDG were conducted in different phases. Electron2013hole analysis on excited states was executed. The TD-DFT methodology has been used to assist in the scrutiny of the UV–visible spectra in dissimilar solvents. The energy of interaction and densities of electron of acceptor and donor bonds were computed using NBO research. To confirm the reactive sites in the molecule, Fukui functions were accomplished. Additionally, docking studies against antithrombotic targets were achieved employing autodock tools and drug-like characteristics were also discovered. The steadiness of the targeted proteins has also been projected using Ramachandran plots. [ABSTRACT FROM AUTHOR]

Metasurfaces are sub-wavelength patterned layers for controlling waves in physical systems. In optics, metasurfaces are created by materials with different dielectric constants and are capable of unconventional functionalities. We develop a deep-learning framework for Dirac-material metasurface design for controlling electronic waves. The metasurface is a configuration of circular graphene quantum dots, each created by an electric potential. Employing deep convolutional neural networks, we show that the original scattering wave can be reconstructed with fidelity over 95%, suggesting the feasibility of Dirac electron holography. Additional applications such as plane wave generation and designing broadband and multi-functionality electronic metasurface in graphene are illustrated. [ABSTRACT FROM AUTHOR]

Dedicating more attention to renewable energies and power electronic improvements results in increased direct current microgrids (DC MGs) application. However, DC MGs have some challenges with voltage adjustment and power sharing. To do so, a two-layer hierarchical control structure, including a new fully distributed secondary control strategy and conventional primary droop control method, is proposed and employed in this paper to share power and swiftly adjust the voltage accurately. Indeed, a distributedaveraging proportional-integral (DAPI) secondary control strategy is introduced. Another problem in DC MGs is the existence of constant power loads (CPLs), which may result in instability. To overcome the problems caused by CPLs, a term based on the output voltage of CPL is added to the proposed DAPI to prevent instability. The required control inputs are obtained using localized data of the DC bus and their neighbor's secondary control inputs inspired by cooperative control. Besides, this strategy needs no knowledge of the microgrid topology, which enhances flexibility. For validating the proposed DAPI strategy in DC MGs, an islanded DC MG is simulated in the MATLAB/SIMULINK software. Comparing the results with those obtained from another existing method proves the performance of the proposed DAPI controller under different scenarios of plug-and-play, communication failure, and load changes. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the traditional short-circuit current calculation method is not applicable to Distributed Generation (DG) accessing the distribution network, the paper proposes a short-circuit current partitioning calculation method considering the degree of voltage drop at the grid-connected point of DG. Firstly, the output characteristics of DG in the process of low voltage ride through are analyzed, and the equivalent output model of DG in the fault state is obtained. Secondly, by studying the network voltage distribution law after fault in distribution networks under different DG penetration rates, the degree of voltage drop at the grid-connected point of DG is used as a partition index to partition the distribution network. Then, iterative computation is performed within each partition, and data are transferred between partitions through split nodes to realize the fast partition calculation of short-circuit current for high proportion DG access to distribution network, which solves the problems of long iteration time and large calculation error of traditional short-circuit current. Finally, a 62-node real distribution network model containing a high proportion of DG access is constructed on MATLAB/Simulink, and the simulation verifies the effectiveness of the short-circuit current partitioning calculation method proposed in the paper, and its calculation speed is improved by 48.35% compared with the global iteration method. [ABSTRACT FROM AUTHOR]

Accurate quantification of the uncertainty in the mechanical characteristics of dielectric solids is crucial for advancing their application in high-precision technological domains, necessitating the development of robust computational methods. This paper introduces a Conditional Generation Adversarial Network Isogeometric Analysis (CGAN-IGA) to assess the uncertainty of dielectric solids' mechanical characteristics. IGA is utilized for the precise computation of electric potentials in dielectric, piezoelectric, and flexoelectric materials, leveraging its advantage of integrating seamlessly with Computer-Aided Design (CAD) models to maintain exact geometrical fidelity. The CGAN method is highly efficient in generating models for piezoelectric and flexoelectric materials, specifically adapting to targeted design requirements and constraints. Then, the CGAN-IGA is adopted to calculate the electric potential of optimum models with different parameters to accelerate uncertainty quantification processes. The accuracy and feasibility of this method are verified through numerical experiments presented herein. [ABSTRACT FROM AUTHOR]

Industrial wireless mesh networks (WMNs) have been widely deployed in various industrial sectors, providing services such as manufacturing process monitoring, equipment control, and sensor data collection. A notable characteristic of industrial WMNs is their distinct traffic pattern, where the majority of traffic flows originate from mesh nodes and are directed towards mesh gateways. In this context, this paper adopts and revisits a routing algorithm known as ALFA (autonomous load-balancing field-based anycast routing), tailored specifically for anycast (one-to-one-of-many) networking in WMNs, where traffic flows can be served through any one of multiple gateways. In essence, the scheme is a hybrid-type routing strategy that leverages the advantages of both back-pressure routing and geographic routing. Notably, its novelty lies in being developed by drawing inspiration from another field, specifically from the movement of charges in an electrostatic potential field. Expanding on the previous work, this paper explores further in-depth discussions that were not previously described, including a detailed description of the analogy between an electrostatic system and a WMN system based on precise mapping perspectives derived from intensive analysis, as well as discussions on anycast, numerical methods employed in devising the ALFA scheme, its characteristics, and complexity. It is worth noting that this paper addresses these previously unexplored aspects, representing significant contributions compared to previous works. As a completely new exploration, a new scheduling strategy is proposed that is compatible with the routing approach by utilizing the potential-based metric not only in routing but also in scheduling. This assigns higher medium access priority to links with a larger potential difference. Extensive simulation results demonstrate the superior performance of the proposed potential-based joint routing and scheduling scheme across various aspects within industrial WMN scenarios. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of magnetic fields on the non-simple concentration phenomenon in the complex-valued nonlinear Schrödinger equations with a constant electric potential$ (\mathbf i \varepsilon\nabla + \boldsymbol A)^2 u + u - |u|^{p-1} u = 0 \qquad \text{in }\mathbb R^N. $We demonstrate that a multi-peak solution always exists at a non-degenerate local maximum or minimum point of the Frobenius norm $ \|\boldsymbol B\|_{\mathcal{F}}^2 $, where $ \boldsymbol B $ is the magnetic field generated from the magnetic potential $ \boldsymbol A $. Interestingly, the locations of peaks form a regular simplex near such a maximum point. It is also surprising that at such a minimum point, we can find a two-peak solution, which is distinct from the real-valued case. This is unexpected given that the non-existence of a multi-peak solution at a non-degenerate local minimum point of the electric potential has been proven in [24]. [ABSTRACT FROM AUTHOR]

Multinuclear (di/tri) copper(II) complexes bridged through hydroxyl groups are very interesting coordination complexes owing to their potential applications in various fields. In this work, three novel dinuclear (μ-hydroxo)-bridged copper(II) complexes in the crystal form, namely, [Cu2(3,5-DIFLB)2(H2tea)2](H2O) (1), [Cu2(4-ClB)2(H2tea)2](H2O) (2), and [Cu2(4-ETHB)2(H2tea)2](H2O)2 (3) (where DIFLB = difluorobenzoate, CLB = chlorobenzoate, ETHB = ethoxybenzoate, and H3tea = triethanolamine), were isolated at room temperature using methanol and water in a 4 : 1 v/v ratio as a solvent. Furthermore, all three complexes (1–3) were characterised using spectroscopic (UV-vis, DRS, and FT-IR), electrochemical (CV) and single-crystal X-ray diffraction techniques. Structural insights gained by packing analysis revealed the role of steric constraints of substituents and various non-covalent interactions in lattice stabilization, which were indeed supported by theoretical and molecular electrostatic potential illustrations. Hirshfeld surface analysis provided quantitative verification about various non-covalent interactions (interatomic contacts) involved in the packing of molecules. Interestingly, as a potential application, complexes 1–3 all exhibited remarkable visible light-mediated photo-Fenton degradation of approximately 98% for 50 ppm concentration of organic dyes (fuchsin basic (FB) and methyl orange (MO)) in 90 minutes with the optimized conditions of 1 mg mL−1 of dye solution. In all the cases, dye degradation by these materials was ascribed to the symbiotic relations among the molecular structures of complexes 1–3, which were endowed with various electron-withdrawing and electron-releasing substituents and ionic strength, with respect to the structure, shape and interacting patterns of dye molecules. The adsorption mechanism indicates that various weak interactions between the donor and acceptor groups of complexes and dyes, such as electrostatic, hydrogen bonding, and direct coordination to metal sites, play a crucial role, which is confirmed by molecular dynamics (MD) simulations. Theoretical studies by DFT-based descriptors, molecular electrostatic potentials, and band gaps provided deep insights into various electronic and reactivity parameters. For subsequent processes of dye degradation, complexes 1–3 were stable and recoverable. The successful integration of experimental and theoretical approaches sheds light on copper-based dinuclear stable coordination complexes, showcasing a significant step towards the development of novel heterogeneous photo-Fenton catalysts. [ABSTRACT FROM AUTHOR]

Pulsars often display systematic variations in the position and/or intensity of the subpulses, the components that comprise each single pulse. Although the drift of these subpulses was observed in the early years of pulsar research, and their potential for understanding the elusive emission mechanism was quickly recognized, there is still no consensus on the cause of the drift. We explore the electrodynamics of two recently proposed or refined drift models: one where plasma lags behind corotation, connecting the drift with the rotational pole; and another where plasma drifts around the electric potential extremum of the polar cap. Generally, these are different locations, resulting in different drift behaviours, that can be tested with observations. In this study, however, we specifically examine these models in the axisymmetric case, where the physics is well understood. This approach seems counter-intuitive as both models then predict similar large-scale plasma drift. However, it allows us to show, by studying conditions within the sparks for both models, that the lagging behind corotation model is inconsistent with Faraday's law. The modified carousel (MC) model, where plasma drifts around the electric potential extremum, not only aligns with Faraday's law, but also provides a future direction for developing a comprehensive model of plasma generation in the polar cap region. Unlike previous models, which considered the drift only inside the discharging regions, the MC model reveals that the electric field between the discharges is not completely screened, and plasma drifts there – a paradigm shift for the drifting subpulse phenomenon. [ABSTRACT FROM AUTHOR]

In order to study the competition between halogen bond acceptor sites of multifunctional N,O,X-based halogen bond acceptors (X = S, O, N or π aromatic ring) we have synthesized a family of oxazole derivatives and cocrystallized them with selected iodoperfluorinated benzenes as halogen bond donors. Out of 28 combinations, 19 experiments yielded crystals suitable for single-crystal X-ray diffraction. Structural analysis revealed that in all of the obtained cocrystals the most prominent supramolecular interaction is the I⋯Noxazole halogen bond with relative shortening values of up to 18%, comparable to I⋯Npyridine halogen bond shortening values. The acceptors are ditopic in 10 cocrystals and form additional I⋯N, I⋯O or I⋯π halogen bonds. A majority of cocrystals feature one donor molecule per one acceptor molecule. In order to rank the acceptor sites and establish how the electrostatic potential differences impact the supramolecular landscape around these molecules, the values of molecular electrostatic potentials (MEPs) were calculated on their optimized geometries. These calculations were in agreement with experimental observations, since the best (most negative MEP value) acceptor binding site in the series of used oxazoles is the oxazole nitrogen atom. Depending on the difference between MEP values of the oxazole oxygen atom and the peripheral functionalities, additional halogen bonds could potentially be formed with one of these acceptor sites, leading to the formation of two different types of halogen-bonded supramolecular chains. [ABSTRACT FROM AUTHOR]

Fluorination of azopyridine N-donors regulates the formation of either B ← N coordination adducts or a co-crystal with phenylboronic acid catechol ester. Specifically, the formation of B ← N adducts is promoted by azopyridines with up to four fluorines, while perfluorination affords a co-crystal via phenyl–perfluoropyridyl [π⋯πF] contacts. Electrostatic potential maps showed supramolecular bonding competition outcomes to be primarily determined by modulation of electron-donating capacity and π surfaces of azopyridine N-donors using fluorination. [ABSTRACT FROM AUTHOR]

The impact of targeted replacement of individual terms in empirical force fields is quantitatively assessed for pure water, dichloromethane (CH 2Cl 2), and solvated K + and Cl − ions. For the electrostatic interactions, point charges (PCs) and machine learning (ML)‐based minimally distributed charges (MDCM) fitted to the molecular electrostatic potential are evaluated together with electrostatics based on the Coulomb integral. The impact of explicitly including second‐order terms is investigated by adding a fragment molecular orbital (FMO)‐derived polarization energy to an existing force field, in this case CHARMM. It is demonstrated that anisotropic electrostatics reduce the RMSE for water (by 1.4 kcal/mol), CH 2Cl 2 (by 0.8 kcal/mol) and for solvated Cl − clusters (by 0.4 kcal/mol). An additional polarization term can be neglected for CH 2Cl 2 but further improves the models for pure water (by ∼1.0 kcal/mol) and hydrated Cl − (by 0.4 kcal/mol), and is key for solvated K +, reducing the RMSE by 2.3 kcal/mol. A 12‐6 Lennard‐Jones functional form performs satisfactorily with PC and MDCM electrostatics, but is not appropriate for descriptions that account for the electrostatic penetration energy. The importance of many‐body contributions is assessed by comparing a strictly 2‐body approach with self‐consistent reference data. Two‐body interactions suffice for CH 2Cl 2 whereas water and solvated K + and Cl − ions require explicit many‐body corrections. Finally, a many‐body‐corrected dimer potential energy surface exceeds the accuracy attained using a conventional empirical force field, potentially reaching that of an FMO calculation. The present work systematically quantifies which terms improve the performance of an existing force field and what reference data to use for parametrizing these terms in a tractable fashion for ML fitting of pure and heterogeneous systems. [ABSTRACT FROM AUTHOR]

ABSTRACT 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]

Distributed power networks have a large number of photovoltaic power sources. The bidirection of power flow, different transient control strategies, and installation locations make the transient characteristics highly complex and unpredictable. The vast network of the distribution system makes it almost impossible to predict the electrical quantities of each branch. Reasonable aggregation modeling of the distribution network can greatly simplify the network topology, facilitating transient control and the setting of relay protection settings. An aggregated equivalent modeling method based on the LSTM neural network for distributed PV fault external characteristics is proposed. This method equates the complex distribution network to a highly nonlinear but controllable current source. The method can output the I–V curves of equivalent PV system parallel points under any output power and is able to predict the fault characteristics of the equivalent system after a voltage drop at the parallel point. Compared to traditional mechanistic modeling, this method does not require specific modeling of complex physical systems and is able to accurately map the strong nonlinear inputs and outputs of distribution networks. The established LSTM model first uses a one-dimensional convolutional layer for feature extraction of the PV power coefficients (input), and then two hidden layers are utilized to process the sequence data; the vectors are mapped into a sequence of external characteristic curves (output) in a fully connected layer. A typical distribution network is built based on the traditional PV power model, and a large number of different output combinations are selected for simulation to provide an effective training set and validation set data for LSTM model training. By using the training set data, the weights and offset coefficients of each layer of the LSTM are continuously optimized until the model with the smallest overall error is obtained, which is the optimal model. Finally, the optimal model is utilized to establish an equivalent distribution network system, different degrees of voltage drops are set up at the grid-connected points, the fault characteristics are compared with those of the complete model, and the simulation results can prove the reliability and practicality of the proposed method. [ABSTRACT FROM AUTHOR]

In recent years, with the continuous growth in power demand, lithium-ion batteries (LIBs) have become an indispensable component of various electronic devices, transportation vehicles, and energy systems. The safety performance of LIBs is one of the most significant issues facing their continued development. In battery systems, the presence of arcs constitutes a significant safety hazard that necessitates attention; the thermal runaway (TR) of LIBs releases a large quantity of particles with elevated temperature and high velocity, probably resulting in arc failures. Changes in the insulation structure inside battery packs and the accumulation of particulate matter resulting from the TR of battery cells are potential causes of arc-induced disasters. In this study, we utilized fully charged 71 Ah ternary LIB Li (Ni0.8Co0.1Mn0.1) O2 (NCM811) pouch cell samples and collected the vented particles in an inert atmosphere after TR. All the settled particles were classified into six groups; by conducting experiments with different particle sizes, electrode spacings, and circuit loads, the patterns of the particle-induced arcs were understood. The results indicate that as the particle size increases, the critical breakdown voltage decreases. Regarding electrode spacing and circuit load resistance, larger values require higher critical breakdown voltages. The research results provide valuable guidance for the electrical protection and safety design of battery systems. [ABSTRACT FROM AUTHOR]

The performance of molecular docking can be improved by comparing the shape similarity of the flexibly sampled poses against the target proteins' inverted binding cavities. The effectiveness of these pseudo-ligands or negative image-based models in docking rescoring is boosted further by performing enrichment-driven optimization. Here, we introduce a novel shape-focused pharmacophore modeling algorithm O-LAP that generates a new class of cavity-filling models by clumping together overlapping atomic content via pairwise distance graph clustering. Top-ranked poses of flexibly docked active ligands were used as the modeling input and multiple alternative clustering settings were benchmark-tested thoroughly with five demanding drug targets using random training/test divisions. In docking rescoring, the O-LAP modeling typically improved massively on the default docking enrichment; furthermore, the results indicate that the clustered models work well in rigid docking. The C+ +/Qt5-based algorithm O-LAP is released under the GNU General Public License v3.0 via GitHub (https://github.com/jvlehtonen/overlap-toolkit). Scientific contribution: This study introduces O-LAP, a C++/Qt5-based graph clustering software for generating new type of shape-focused pharmacophore models. In the O-LAP modeling, the target protein cavity is filled with flexibly docked active ligands, the overlapping ligand atoms are clustered, and the shape/electrostatic potential of the resulting model is compared against the flexibly sampled molecular docking poses. The O-LAP modeling is shown to ensure high enrichment in both docking rescoring and rigid docking based on comprehensive benchmark-testing. [ABSTRACT FROM AUTHOR]