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During the standard ac lock-in measurement of the resistance of a two-dimensional electron gas (2DEG) applying an ac current I = 2 I 0 sin (ω t) , the electron temperature T e oscillates with the angular frequency 2 ω due to the Joule heating ∝ I 2. We have shown that the highest (T H ) and the lowest (T L ) temperatures during a cycle of the oscillations can be deduced, at cryogenic temperatures, exploiting the third-harmonic (3 ω) component of the voltage drop generated by the ac current I and employing the amplitude of the Shubnikov–de Haas oscillations as the measure of T e. The temperatures T H and T L thus obtained allow us to roughly evaluate the thermal conductivity κ x x of the 2DEG via the modified 3 ω method, in which the method originally devised for bulk materials is modified to be applicable to a 2DEG embedded in a semiconductor wafer. κ x x thus deduced is found to be consistent with the Wiedemann–Franz law. The method provides a convenient way to access κ x x using only a standard Hall-bar device and the simple experimental setup for the resistance measurement. [ABSTRACT FROM AUTHOR]

In this paper, we study electrostatic and structural properties between pH-responsive polyelectrolyte brushes by using a strong stretching theory accounting for excluded volume interactions, the density of polyelectrolyte chargeable sites, and the Born energy difference between the inside and outside of the brush layer. In a free energy framework, we obtain self-consistent field equations to determine electrostatic properties between two pH-responsive polyelectrolyte brushes. We elucidate that in the region between two pH-responsive polyelectrolyte brushes, electrostatic potential at the centerline and osmotic pressure increase not only with excluded volume interaction but also with the density of chargeable sites on a polyelectrolyte molecule. Importantly, we clarify that when two pH-responsive polyelectrolyte brushes approach each other, the brush thickness becomes short and that a large excluded volume interaction and a large density of chargeable sites yield the enhanced contract of polyelectrolyte brushes. In addition, we also demonstrate how the influence of such quantities as pH, the number of Kuhn monomers, the density of charged sites, the lateral separation between adjacent polyelectrolyte brushes, and Kuhn length on the electrostatic and structural properties between the two polyelectrolyte brushes is affected by the exclusion volume interaction. Finally, we investigate the influence of the Born energy difference on the thickness of polyelectrolyte brushes and the osmotic pressure between two pH-responsive polyelectrolyte brushes. [ABSTRACT FROM AUTHOR]

Constant potential methods (CPMs) enable computationally efficient simulations of the solid–liquid interface at conducting electrodes in molecular dynamics. They have been successfully used, for example, to realistically model the behavior of ionic liquids or water-in-salt electrolytes in supercapacitors and batteries. CPMs model conductive electrodes by updating charges of individual electrode atoms according to the applied electric potential and the (time-dependent) local electrolyte structure. Here, we present a feature-rich CPM implementation, called ELECTRODE, for the Large-scale Atomic/Molecular Massively Parallel Simulator, which includes a constrained charge method and a thermo-potentiostat. The ELECTRODE package also contains a finite-field approach, multiple corrections for nonperiodic boundary conditions of the particle–particle particle–mesh solver, and a Thomas–Fermi model for using nonideal metals as electrodes. We demonstrate the capabilities of this implementation for a parallel-plate electrical double-layer capacitor, for which we have investigated the charging times with the different implemented methods and found an interesting relationship between water and ionic dipole relaxations. To prove the validity of the one-dimensional correction for the long-range electrostatics, we estimated the vacuum capacitance of two coaxial carbon nanotubes and compared it to structureless cylinders, for which an analytical expression exists. In summary, the ELECTRODE package enables efficient electrochemical simulations using state-of-the-art methods, allowing one to simulate even heterogeneous electrodes. Moreover, it allows unveiling more rigorously how electrode curvature affects the capacitance with the one-dimensional correction. [ABSTRACT FROM AUTHOR]

Low-temperature plasmas have seen increasing use for synthesizing high-quality, mono-disperse nanoparticles (NPs). Recent work has highlighted that an important process in NP growth in plasmas is particle trapping—small, negatively charged nanoparticles become trapped by the positive electrostatic potential in the plasma, even if only momentarily charged. In this article, results are discussed from a computational investigation into how pulsing the power applied to an inductively coupled plasma (ICP) reactor may be used for controlling the size of NPs synthesized in the plasma. The model system is an ICP at 1 Torr to grow silicon NPs from an Ar/SiH4 gas mixture. This system was simulated using a two-dimensional plasma hydrodynamics model coupled to a three-dimensional kinetic NP growth and trajectory tracking model. The effects of pulse frequency and pulse duty cycle are discussed. We identified separate regimes of pulsing where particles become trapped for one pulsed cycle, a few cycles, and many cycles—each having noticeable effects on particle size distributions. For the same average power, pulsing can produce a stronger trapping potential for particles when compared to continuous wave power, potentially increasing particle mono-dispersity. Pulsing may also offer a larger degree of control over particle size for the same average power. Experimental confirmation of predicted trends is discussed. [ABSTRACT FROM AUTHOR]

Constructing junction architectures is one of the most promising strategies to improve the photocatalytic activity of two-dimensional semiconductors for the splitting of water. Using first-principles calculations, we demonstrate that the van der Waals heterojunction consisting of PtS2 and GaSe monolayers is a potential step-scheme photocatalyst with high solar-to-hydrogen (STH) efficiency. The stability of the heterojunction is confirmed by phonon dispersion spectrum calculation and ab initio molecular-dynamics simulation. In such a step-scheme heterojunction, GaSe serves as a reduction photocatalyst and PtS2 acts as an oxidation photocatalyst. The built-in electric field and band bending are formed since the work function difference and electrostatic potential difference promote the photo-generated electron (hole) to the conductance band minimum (valence band maximum) of GaSe (PtS2), inducing a step-scheme migrating route and guaranteeing strong redox ability of photo-generated carriers. The hydrogen evolution reduction can proceed driven solely by the photogenerated electrons, while the barrier of the oxygen evolution reaction is only 0.89 eV. More intriguingly, the STH efficiency is predicted up to 36.9% along with the improvement of visible light absorption. The STH efficiency can be enhanced effectively by both in-plane strain and compressive vertical strain. Our findings provide valuable guidance for the potential applications of PtS2/GaSe heterojunction as a photocatalyst for the photocatalytic splitting of water. [ABSTRACT FROM AUTHOR]

Identification of the operating voltage of a lead acid battery with 30% sulfuric acid electrolyte flow has been carried out. The battery consists of six cells with Pb and PbO as electrodes. The battery is equipped with a 1200 ml reservoir system to collect electrolyte and supply electrolyte to each cell. Each cell has electrolyte inlets and outlets at the top and bottom that circulate through each cell using a peristaltic pump. The battery prototype built was tested for five charge-discharge cycles with a constant current of 2 A for the charging process and 0.5 A for the discharging process using Turnigy Accucell. During the charge-discharge cycle test, monitoring and recording of voltage data is carried out using a Laptop PC. Data processing uses WebplotDigitizer and Microsoft Excel for data graphing. The results are analyzed and used to identify the operating voltage of the battery by taking the average voltage over five charge-discharge cycles. The average voltage is 13.98 V for the charging process and 12.11 V for the discharging process. Six-cell battery with full capacity works at a voltage range of 12.11-13.98 V. In the process of charging with a constant current of 2 A, the battery takes an average of 7.49 hours. So, the charging capacity can be estimated at 14,980 mAh. Whereas the battery discharge process takes an average of 11 hours with a constant current of 0.5 A to a voltage drop of 10.81 V. The resulting capacity of the discharged battery is 5500 mAh. [ABSTRACT FROM AUTHOR]

NMR spectroscopy techniques can provide important information about protein‐ligand interactions. Here we tested an NMR approach which relies on the measurement of paramagnetic relaxation enhancements (PREs) arising from analogous cationic, anionic or neutral soluble nitroxide molecules, which distribute around the protein‐ligand complex depending on near‐surface electrostatic potentials. We applied this approach to two protein‐ligand systems, interleukin‐8 interacting with highly charged glycosaminoglycans and the SH2 domain of Grb2 interacting with less charged phospho‐tyrosine tripeptides. The electrostatic potential around interleukin‐8 and its changes upon binding of glycosaminoglycans could be derived from the PRE data and confirmed by theoretical predictions from Poisson‐Boltzmann calculations. The ligand influence on the PREs and NMR‐derived electrostatic potentials of Grb2 SH2 was localized to a narrow protein region which allowed the localization of the peptide binding pocket. Our analysis suggests that experiments with nitroxide cosolutes can be useful for investigating protein‐ligand electrostatic interactions and mapping ligand binding sites. [ABSTRACT FROM AUTHOR]

Charge sensitive infrared phototransistors (CSIPs) show great promise for sensitive mid-infrared photodetection, extending up to single-photon counting, owing to the built-in amplification mechanism. However, the operating temperature of previously reported CSIPs has been limited to below 30 K. In this work, we propose a technique that enhances the operating temperature to above liquid nitrogen temperature by dynamically controlling the electrostatic potential of the optical floating gate (FG). This control effectively suppresses the annihilation of photogenerated holes in the FG, mitigating the vertical recombination process of thermally excited electrons. We detected the photosignal up to ∼85 K under a photon flux of Φ ∼ 3.6 × 10 8 s − 1 . An outstanding photoresponsivity (R = 39.11 A / W) to external blinking light at the peak wavelength of λ = 11 μm is achieved at 77 K. Our work not only extends the practical application of CSIPs, meeting the high demand for high temperature operation, but also offers more flexibility in fabricating more general highly sensitive phototransistors. [ABSTRACT FROM AUTHOR]

Catalytic materials are effective in promoting sulfur utilization in lithium‐sulfur batteries. Co phthalocyanine (CoPc) presents a unique planner single‐molecular structure with a highly active Co‐N4 center for sulfur reduction catalysis. The high flexibility of phthalocyanines offers rich opportunities for electronic structure modulation toward enhanced catalytic activities. To guide future design and screening, this study aims to understand the impact of peripheral substitution, the most common method to obtain CoPc derivatives, by examining two typical substituents: the electron‐withdrawing nitro and electron‐donating amino groups. Co tetranitrophthalocyanine (CoTnPc) presents a significantly higher activity in promoting the liquid‐solid transition process than Co tetraaminophthalocyanine (CoTaPc). Substitution alters the stable binding geometry of Li2S4 by influencing the electrostatic potential and Li─bond, making the Co─S bond energetically favorable with the bridging S atoms on CoTnPc. CoTnPc also enables a greater electron donation from the S 3pz orbital to the singly occupied Co 3dz2${d}_{{z}^2}$ orbital, significantly weakening the bridging S─S bond to enhance the reactivity of Li2S4 for the subsequent liquid‐solid transition. A framework of theoretical calculation is tested, providing descriptors for the screening of related materials. The potential of CoPc derivatives is demonstrated by pouch cells with CoTnPc under high sulfur loading and limited electrolyte addition. [ABSTRACT FROM AUTHOR]

Electro‐coalescence is the fusion phenomenon between a pair or more microfluidic droplets that are immersed in an immiscible medium under an electric field. This technique is frequently used to merge confined droplets in surfactant‐stabilized microfluidic emulsions using local electric fields. Despite the necessity of miniaturized electrodes, this method has proven highly successful in microfluidics and lab‐on‐a‐chip applications. Miniaturized electrodes severely curtail the spatial and temporal flexibility of the electric potential, thus hindering real‐time and flexible operation and leading to high production costs. The current study addresses this problem with reconfigurable electric field potential by light‐driven functional virtual electrodes. These electrodes are light‐induced on a non‐centrosymmetric ferroelectric photovoltaic crystal placed below a microfluidic droplet channel. The photovoltaic effect in the crystal is responsible for the space charge distributions that act as virtual electrodes, whose evanescent field is screened by free charges into the two liquids inside the channel. A numerical model is developed to describe the evolution of the evanescent electric field causing electro‐coalescence. Based on this prediction, two coalescence processes occur at two different timescales and with different numbers of droplets involved. Controlled exposure time modulation allows either rapid on‐demand coalescence of droplet pairs or breakup of the entire emulsion. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the impact of interfacial imperfection on shear horizontal wave propagation in a microstructural coupled stress half-space beneath a porous piezoelectric layer adjacent to air. The validity of dispersion relations is shown by deriving special cases and comparing them with the classical dispersion relation of Love wave. Furthermore, a comparative analysis has been conducted to analyze the effect of various parameters on the phase velocity of shear wave by considering perfect and imperfect interfaces under electrically open and short conditions. The findings provide a theoretical framework for developing and designing underwater acoustic devices for sensing and nondestructive testing. [ABSTRACT FROM AUTHOR]

In this study, the effects of an Al2O3 interfacial layer (IL) on the characteristics of ferroelectric field-effect transistors (FeFETs) with Hf0.5Zr0.5O2 (HZO) gate dielectrics on Si substrates were investigated. FeFETs with HZO gate dielectrics have gained considerable attention owing to their compatibility with modern fabrication processes and scalability. However, during HZO deposition on Si substrates, an ultrathin metal silicate IL with a low dielectric constant is formed in an uncontrolled manner, leading to a significant voltage drop and the generation of interface traps during device operation. To address this issue, an ultrathin Al2O3 IL with a thickness less than 2 nm was introduced between the HZO film and Si substrate via in situ atomic layer deposition. The impact of this IL on a memory window (MW) and endurance characteristics was evaluated by comparing the devices with and without an intentional Al2O3 IL. The obtained results revealed that the Al2O3 IL effectively suppressed the interface trap generation, expanded the MW, and enhanced the transistor endurance characteristics. This described approach can be potentially used for improving the reliability of FeFETs fabricated on Si substrates. [ABSTRACT FROM AUTHOR]

Three new PbII complexes [Pb(LI)(SCN)]n, {[Pb(LII)](SCN)}n and {[Pb(HLIII)(SCN)](SCN)}n (HLI = N′-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide, HLII = N′-amino(pyrazin-2-yl)methylenethiosemicarbazide, HLIII = N′-amino(pyridin-2-yl)methylenethiosemicarbazide) have been synthesized and characterized by spectroscopic techniques and single crystal X-ray diffraction. In all complexes, the corresponding organic ligand behaves as a tridentate N,N′,S-chelating species. A 1D supramolecular polymeric aggregation in complex [Pb(LI)(SCN)]n is dictated by the Pb⋯NCS and Pb⋯S＝C tetrel bonds formed between the [Pb(LI)(SCN)] species. 1D cationic coordination polymers ([Pb(LII)])nn+ in the structure of complex {[Pb(LII)](SCN)}n are linked into a 2D supramolecular polymeric layer through the Pb⋯NCS tetrel bonds and Pb⋯π(NCS) interactions formed with the nitrogen atom and the conjugated system of the free SCN− anions, respectively. The cationic species [Pb(HLIII)(SCN)]+ in the structure of complex {[Pb(HLIII)(SCN)](SCN)}n produce a 1D supramolecular polymer due to the Pb⋯SCN and Pb⋯S＝C tetrel bonds, further stabilized by the Pb⋯π(NCS) interactions formed with the conjugated system of the coordinated NCS− anion. The latter anions also link these 1D chains through the Pb⋯SCN tetrel bonds, yielding 1D supramolecular polymeric ribbons. The energetic relevance of the Pb⋯S and Pb⋯N tetrel bonds has been studied by DFT calculations. The tetrel bonds have been characterized using QTAIM and NCIplot analysis and rationalized using molecular electrostatic potential surface calculations. [ABSTRACT FROM AUTHOR]

The study reported herein describes the synthesis of benzothiadiazole(BTD)-N-heterocycle derivatives by metal-catalyzed cross-coupling reactions with relatively good yields. The photophysical characteristics of these derivatives were assessed in solution through UV-vis absorption and steady-state fluorescence emission spectroscopies. These compounds show absorption maxima in the violet to blue region, related to spin and symmetry-allowed 1π → π* electronic transitions. The BTDs display fluorescence in the visible region of the electromagnetic spectrum, depending on their chemical structure and solvent, ranging from 499 to 570 nm. It was demonstrated that both ground and excited states are influenced by the substituents in the BTD core. In addition, a proof of concept was presented using these compounds as sensors for water in an organic environment. Theoretical calculations data provided a comprehensive insight into the structural and electronic factors that govern the photophysical behavior of these compounds. Solvent-induced twists result in a blueshift in the UV-vis spectra. The molecular electrostatic potential (MEP) provides insights into interactions, revealing that the addition of water influences both emission and molecular structure. [ABSTRACT FROM AUTHOR]

The variational implicit-solvent model (VISM) is an efficient approach to biomolecular interactions, where electrostatic interactions are crucial. The total VISM free energy of a dielectric boundary (i.e. solute–solvent interface) consists of the interfacial energy, solute–solvent interaction energy and dielectric electrostatic energy. The last part is the maximum value of the classical and concave Poisson–Boltzmann (PB) energy functional of electrostatic potentials, with the maximizer being the equilibrium electrostatic potential governed by the PB equation. For the consistency of energy minimization and computational stability, here we propose alternatively to minimize the convex Legendre-transformed Poisson–Boltzmann (LTPB) electrostatic energy functional of all dielectric displacements constrained by Gauss' Law in the solute region. Both integrable and discrete solute charge densities are treated, and the duality of the LTPB and PB functionals is established. A penalty method is designed for the constrained minimization of the LTPB functional. In application to biomolecular interactions, we minimize the total VISM free energy iteratively, while in each step of such iteration, minimize the LTPB energy. Convergence of such a min–min algorithm is shown. Our numerical results on the solvation of a single ion indicate that the LTPB performs better than the PB formulation, providing possibilities for efficient biomolecular simulations. [ABSTRACT FROM AUTHOR]

2-(3-Bromophenyl)-1-(4-morpholinyl)ethanone belongs to one of morpholine derivatives. In this paper, 2-(3-bromophenyl)-1-(4-morpholinyl)ethanone was synthesized by a two-step synthesis method. In order to determine the structure of the target compound, FT-IR,1H NMR,13C NMR and MS were used for detection. Meanwhile, X-ray diffraction was used to detect the single crystal and obtain the crystal structure data of the target compound. The molecular crystal structure was compared with that determined by density functional theory. The frontier molecular orbitals and molecular electrostatic potential energy were used to further study the physical properties of the compounds. [ABSTRACT FROM AUTHOR]

We study qualitative and quantitative properties of the solutions of a Vlasov–Poisson system modeling the interaction between a plasma and a cylindrical Langmuir probe. In particular, we exhibit a class of radial sheath solutions for which the electrostatic potential is increasing and strictly concave with a strong variation in the vicinity of the probe which scales as the inverse of the Debye length. These solutions are proven to exist provided the incoming distributions of particles from the plasma verify the so‐called generalized Bohm condition of plasma physics. It extends our previous studies. [ABSTRACT FROM AUTHOR]

The carbonyl-rich conjugated organic compound of PTO-AQ exhibits the potential application in aqueous sodium ion batteries with wide voltage window workability. [Display omitted] Organic compounds have become an important electrode material for aqueous electrochemical energy storage. However, organic electrodes still face poor performance in aqueous batteries due to insufficient electrochemical activity. In this work, a novel conjugated quinone compound containing a rich carbonyl group was designed. The quinone compound was synthesized by a simple dehydration reaction of pyrene-4,5,9,10-tetrone (PTO) and 1,2-diaminoanthraquinone (1,2-AQ); it contains 4 pyrazines (C N) from AQ and 4 carbonyl groups (C O), as well as a large number of active sites and the excellent conductivity brought by its conjugated structure ensures the high theoretical capacity of PTO-AQ. In the context of aqueous sodium ion batteries (ASIBs), the electrode material known as PTO-AQ exhibits a notable reversible discharge capacity of 117.9 mAh/g when subjected to a current density of 1 A/g; impressively, it maintained a capacity retention rate of 74.3 % even after undergoing 500 charge and discharge cycles, a performance significantly surpassing that of pristine PTO and AQ. Notably, PTO-AQ exhibits a wide operating voltage range (-1.0–0.5 V) and a cycle life of up to 10,000 cycles. In situ Raman and ex situ measurements were used to analyze the structural changes of PTO-AQ during charge and discharge and the energy storage mechanism in NaAC. The effective promotion of Na+ storage brought by a rich carbonyl group was obtained. The structural energy level and electrostatic potential of PTO-AQ were calculated, and the active center distribution of PTO-AQ was obtained. This work serves as a guide for designing high-performance aqueous organic electrode materials that operate across a wide voltage range while also explaining their energy storage mechanism. [ABSTRACT FROM AUTHOR]

Interpretation of extracellular recordings can be challenging due to the long range of electric field. This challenge can be mitigated by estimating the current source density (CSD). Here we introduce kCSD-python, an open Python package implementing Kernel Current Source Density (kCSD) method and related tools to facilitate CSD analysis of experimental data and the interpretation of results. We show how to counter the limitations imposed by noise and assumptions in the method itself. kCSD-python allows CSD estimation for an arbitrary distribution of electrodes in 1D, 2D, and 3D, assuming distributions of sources in tissue, a slice, or in a single cell, and includes a range of diagnostic aids. We demonstrate its features in a Jupyter Notebook tutorial which illustrates a typical analytical workflow and main functionalities useful in validating analysis results. Author summary: Recording electric potential with wires inserted in the brain is a standard method in neuroscientist's arsenal for a century. This extracellular potential reflects electric activity of billions of neural cells processing incoming information and our deepest thoughts. It is difficult to interpret because the effect of every single cell activity propagates in space like a wave in a lake after a stone is thrown. Therefore, every electric recording is a sum of billions of stronger and weaker contributions from close and remote cells, respectively. It is easier to understand the local activity of the brain when we reconstruct the distribution of the sources contributing to the measurements. This is similar to reconstructing the information on where and when stones where thrown into the lake from wiggling of multiple buoys placed on the water surface. The techniques for source reconstruction are called the Current Source Density methods. Early techniques required distributions of electrodes on regular grids. Our kernel Current Source Density method can reconstruct this activity from arbitrary distribution of electrodes and can take into account measurement noise. Here we present our software toolbox, kCSD-python, which implements this method. It comes with a number of tools for efficient estimation, for testing reliability of the results, and with several tutorials showing how to use it. [ABSTRACT FROM AUTHOR]

Solar photovoltaics in Malta have increased substantially over the years, both at large scale and residential scale. The present installed capacity is already having a negative impact on Malta's' grid infrastructure, causing problems due to the reverse power flows (resulting from oversupply) and related issues such as voltage rise. This paper considers the integration of a low voltage regulator in a low voltage feeder in a semi‐rural area in Malta. A thyristor‐controlled transformer‐based low voltage regulator was modelled and simulated in MATLAB/Simulink using the PLECS blockset. Experimental results were also obtained via measurements of the voltage profiles at 70% of the actual low voltage feeder that showed several instances of over and under voltage events. The outputs obtained from the simulation model strongly agreed with those obtained from the field testing thereby validating the simulation models that were developed in this study. Results show that the voltage on the feeder was successfully regulated to around the nominal voltage of 240 V. The regulator failed to correct the voltage to within ±10% in one occurrence where the load demand and hence the voltage drop was too high. [ABSTRACT FROM AUTHOR]

Achieving photothermal therapy (PTT) at ultralow laser power density is crucial for minimizing photo‐damage and allowing for higher maximum permissible skin exposure. However, this requires photothermal agents to possess not just superior photothermal conversion efficiency (PCE), but also exceptional near‐infrared (NIR) absorptivity. J‐aggregates, exhibit a significant redshift and narrower absorption peak with a higher extinction coefficient. Nevertheless, achieving predictable J‐aggregates through molecular design remains a challenge. In this study, we successfully induced desirable J‐aggregation (λabsmax: 968 nm, ϵ: 2.96×105 M−1 cm−1, λemmax: 972 nm, ΦFL: 6.2 %) by tuning electrostatic interactions between π‐conjugated molecular planes through manipulating molecular surface electrostatic potential of aromatic ring‐fused aza‐BODIPY dyes. Notably, by controlling the preparation method for encapsulating dyes into F‐127 polymer, we were able to selectively generate H‐/J‐aggregates, respectively. Furthermore, the J‐aggregates exhibited two controllable morphologies: nanospheres and nanowires. Importantly, the shortwave‐infrared J‐aggregated nanoparticles with impressive PCE of 72.9 % effectively destroyed cancer cells and mice‐tumors at an ultralow power density of 0.27 W cm−2 (915 nm). This phototherapeutic nano‐platform, which generates predictable J‐aggregation behavior, and can controllably form J‐/H‐aggregates and selectable J‐aggregate morphology, is a valuable paradigm for developing photothermal agents for tumor‐treatment at ultralow laser power density. [ABSTRACT FROM AUTHOR]

The density functional tight binding (DFTB) method and DFTB-based molecular dynamics (DFTB-MD) simulations were used to study the structure, intermolecular interactions, and dynamic properties of 2,4-dinitroimidazole (2,4-DNI) crystals doped with different amounts of 1,4-dinitroimidazole (1,4-DNI) at different temperatures. As the doping concentration increases, the stability of the system decreases. It is thermodynamically most favorable to arrange the doped defects in molecular layers. The doping of impurities changes the extreme point of the surface electrostatic potential (ESP) of the 2,4-DNI molecules, but would not change the position of the extreme point, which reduces the stability and safety of the 2,4-DNI molecules. The dynamic simulation showed that the doping of the impurities does not change the decomposition mechanism of the 2,4-DNI molecules, but effectively promotes their decomposition and the formation of intermediate products. At the initial decomposition stage, the 2,4-DNI molecules located around the impurity molecules become more easy to decompose. [ABSTRACT FROM AUTHOR]

The present study investigates the potential of a new compound containing sulfonamide and 4(3H)-quinazolinone to inhibit the hCA-IIX enzyme using in silico methods. Density functional theory-based calculations of electronic properties have been addressed through the analysis of frontier molecular orbitals, molecule electrostatic potential, and IR and UV–vis spectroscopy data. A molecular electrostatic potential analysis predicts that the target protein will be most inhibited by the sulfonamide groups since it has the highest potential spots for electrophile and nucleophile attack. The investigated compound exhibited good ADMET properties and satisfied the Lipinski rule of drug likeness. The hCA-IIX protein binding affinity with the proposed compound was determined by molecular docking analysis, which revealed a stable conformation with more negative binding energy (−12.19 kcal/mol) than the standard AZA drug (−7.36 kcal/mol). Moreover, a molecular dynamics study confirmed the docking results through trajectory analysis. The RMSD and RMSF both showed convergence and no significant fluctuations during the simulation time, which revealed a stable interaction within the active domain of the target protein. According to these findings, the proposed compound has a good pharmacological nature and could potentially be an efficient drug against hCAIX enzymes. [ABSTRACT FROM AUTHOR]

A pivotal feature of present research study is the synthesis of some new 2,5‐bis(pyrazolyl)‐1,3,4‐oxadiazoles as promising α‐glucosidase inhibitors. In this regard, a facile reaction scheme was designed to afford 1,3,4‐oxadiazole ring. In search of the most favourable reaction condition, a model reaction was first carried out between 1,3‐diphenyl‐1H‐pyrazole‐4‐carbohydrazide (3) and 1,3‐diphenyl‐1H‐pyrazole‐4‐carboxylic acid (4 a) using phosphorous oxychloride (POCl3). The results emanated from this model reaction were utilized to prepare other derivatives to highlight the scope of current synthetic approach and the structures of the prepared molecules were characterized from spectroscopic techniques. These derivatives were further investigated for their α‐glucosidase inhibitory potentials. 2,5‐Bis(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 a) and 2‐(3‐(4‐bromophenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)‐5‐(1,3‐diphenyl‐1H‐pyrazol‐4‐yl)‐1,3,4‐oxadiazole (5 c) displayed strong in vitro inhibitory activities with IC50 73.1±1.13 μM and IC50 87.3±1.12 μM respectively with least toxicity profiles. Molecular docking and computational studies including geometry optimization of synthesized molecular systems, calculations of their orbital energies, and molecular electrostatic potential (MEP) surface maps further helped to establish structural and electronic properties contributing towards their bioactivity. The electrophilicity index significantly quantifies the biological activity. The experimental and computational data altogether facilitated in understanding the therapeutic attributes of these versatile scaffolds in relation to their α‐glucosidase inhibition. [ABSTRACT FROM AUTHOR]

Although the inner potential plays a fundamental role in electrochemistry, its precise definition is not clear. In fact, there are two different concepts: a physical quantity which can be measured by high energy electron scattering and calculated by density functional theory. For water, it is of the order of 4 V, and it is irrelevant for electrochemistry. For our purpose, the relevant quantity is the electrostatic potential experienced by an ion, which enters into the electrochemical potential. This is of the order of 0 to - 0.5 V, and may be slightly different for different ions. [ABSTRACT FROM AUTHOR]

Copper(II) complexes [Cu(LI)2] and [Cu(LII)2] (HLI = N-cyclohexyl-3-methoxysalicylideneimine, HLII = N-cyclohexyl-3-ethoxysalicylideneimine) were investigated using computational methods. It was previously found that [Cu(LI)2] is a planar molecule with two cyclohexyl groups oriented on the opposite sites of the planar part of the molecule, whereas complex [Cu(LII)2] is a bent molecule with two cyclohexyl groups oriented on the convex part of the molecule. Global reactivity descriptors, nonlinear optical properties and molecular electrostatic potential surfaces were computed for both structures. It was revealed that the molecular electrostatic potential surface of [Cu(LI)2] is symmetric due to a centrosymmetric structure of the complex, whereas for [Cu(LII)2], due to a bent structure, the same surface differs significantly for the convex and concave parts. Nucleophilic and electrophilic centers were also identified. Besides, potential anti-corrosion properties of both complexes were estimated for a series of metals. The evaluation of corrosion inhibitory properties of the complexes showed that the most efficient electron charge transfer was established for Ni and Co. [ABSTRACT FROM AUTHOR]

The coupling of AC and DC power will impact the protective actions on the AC side and pose a threat to the stable operation of the interconnection system. Therefore, a new longitudinal protection method is proposed based on the comprehensive distance similarity of voltage waveforms. Initially, the measured voltage and current data are extracted to calculate the reference voltage, and the voltage waveform fitting is optimized. Subsequently, the Euclidean dynamic time warp (DTW) distance and entropy weight method are utilized to process the voltage waveform, enabling the calculation of its comprehensive distance similarity. This similarity is adopted to determine fault location. A hybrid DC multi-feed AC/DC interconnection system, incorporating a line commutated converter-voltage source converter (LCC-VSC) and a line commutated converter-modular multilevel converter (LCC-MMC), was established in PSCAD, and fault data were simulated and output. The effectiveness of the protection scheme was validated using MATLAB. Simulation results demonstrate that the proposed method can accurately distinguish between faults inside and outside a region. When compared to existing protection methods, it demonstrates superior performance in resisting transition resistance and noise interference, while also mitigating the impact of data asynchronicity. The speed and reliability of the method are further enhanced. [ABSTRACT FROM AUTHOR]

The synthesis of gold(III) and gold(I)–gold(III) complexes with phosphide bridges is still a matter that requires solutions for their marked instability, in spite of the affinity of this metal in both oxidation states for phosphorous donor ligands. In the course of our studies, we realized that the presence of perhalophenyl groups of the type pentafluorophenyl or 3,5-dichlorotrifluorophenyl in the complexes gives rise to an increase in their stability that eases their isolation and structural characterization. In this paper, we describe two new fully characterized neutral compounds of this type to extend the knowledge on this family of compounds, [{Au(C6Cl2F3)2}2(µ-PPh2)2] (1) and [{Au(C6Cl2F3)2(µ-PPh2)2Au}2] (2). In this work, we analyze the role of the perhalophenyl groups in the stability of these complexes by using quantum chemical topology methodologies, specifically employing an analysis of the non-covalent interactions (NCIs) in real space and evaluating the electrostatic potential surfaces (ESP). Our findings reveal the existence of appreciable π-stacking interactions among the perhalophenyl and phenyl groups in both compounds, significantly contributing to the stability of the systems. [ABSTRACT FROM AUTHOR]

Defining life is an arduous task that has puzzled philosophers and scientists for centuries. Yet biology suffers from a lack of clear definition, putting biologists in a paradoxical situation where one can describe at the atomic level complex objects that remain globally poorly defined. One could assume that such descriptions make it possible to perfectly characterize living systems. However, many cases of misinterpretation put this assumption into perspective. In this article, we focus on critical parameters such as time, water, entropy, space, quantum properties, and electrostatic potential to redefine the nature of living matter, with special emphasis on biological coding. Where does the DNA double helix come from, why cannot the reproduction of living organisms occur without mutations, what are the limitations of the genetic code, and why do not all proteins have a stable three-dimensional structure? There are so many questions that cannot be resolved without considering the aforementioned parameters. Indeed, (i) time and space constrain many biological mechanisms and impose drastic solutions on living beings (enzymes, transporters); (ii) water controls the fidelity of DNA replication and the structure/disorder balance of proteins; (iii) entropy is the driving force of many enzymatic reactions and molecular interactions; (iv) quantum mechanisms explain why a molecule as simple as hydrocyanic acid (HCN) foreshadows the helical structure of DNA, how DNA is stabilized, why mutations occur, and how the Earth magnetic field can influence the migration of birds; (v) electrostatic potential controls epigenetic mechanisms, lipid raft functions, and virus infections. We consider that raising awareness of these basic parameters is critical for better understanding what life is, and how it handles order and chaos through a combination of genetic and epigenetic mechanisms. Thus, we propose to incorporate these parameters into the definition of life. [ABSTRACT FROM AUTHOR]

For the first time, details of the spatial and temporal acceptable evolution of the merging process of co-rotating electron vortices in a potential well are successfully captured using a "single-shot method" with a high temporal resolution of 10 µs. Four-electron filaments are trapped inside the Beam eXperiment-Upgrade linear trap [H. Himura, Nucl. Instrum. Methods Phys. Res. A 811, 100 (2016)] with a uniform axial magnetic field and co-axial multi-ring electrodes. Images of non-emitting electron filaments are captured using a high-speed camera with up to 1 000 000 fps, a microchannel plate, a fast-decay phosphor screen of which fluorescence duration is 0.15 µs, and a super fine metallic mesh with an open area ratio of 89%. Images captured every 10 µs clearly show the growth of multiple short-wave instabilities in the wing trailing electron vortices. The experimental methods and measurement techniques presented in this paper can contribute to revealing exactly how small vortices evolve into a large structure or turbulence in a potential well through complex processes. [ABSTRACT FROM AUTHOR]

The gyrokinetic theory of the residual flow, in the electrostatic limit, is revisited, with optimized stellarators in mind. We consider general initial conditions for the problem, and identify cases that lead to a non-zonal residual electrostatic potential, i.e. one having a significant component that varies within a flux surface. We investigate the behaviour of the 'intermediate residual' in stellarators, a measure of the flow that remains after geodesic acoustic modes have damped away, but before the action of the slower damping that is caused by unconfined particle orbits. The case of a quasi-isodynamic stellarator is identified as having a particularly large such residual, owing to the small orbit width achieved by optimization. [ABSTRACT FROM AUTHOR]

This study comprehensively investigates the effect of DC voltage gradient (VG) on energy consumption and the removal of ions (total Cr, Na+, Clˉ, and K+) from salt-affected clayey soil. In this work, different VG (i.e., 0.5, 1, and 2 V cm−1) were applied over the artificially contaminated soil for 48 h during electrokinetic experiments to determine the electric potential distribution, electroosmotic flow (EOF), and electric current variation. The results revealed that the VG directly influences the EOF rate and electromigration of ionic species present in the pore solution of the soil samples. The higher removal of ions was achieved with the intensity of applied electric field (EF) due to electromigration and higher EOF rate. Therefore, the maximum ion removal was achieved at 2 V cm−1 [i.e., total Cr (71%), Na+ (91%), Clˉ (64%), and K+ (63%)]. In addition, the EOF rate decreased with increasing treatment time, which was attributed to the progression of acidic-alkaline fronts in soil samples. The collision of acidic-alkaline fronts resulted in a large VG in a narrow soil region of pH jump reducing the EOF and electromigration of ions. Regardless of low EF (i.e., 0.5 V cm−1), the EOF rate and removal of ions decreased [i.e., total Cr (36%), Na+ (58%), Clˉ (45%), and K+ (37%)]. Moreover, the higher EF (i.e., 2 V cm−1) resulted in higher energy consumption (218.6 kWh m−3) and a reduction in the electrical conductivityof soil from 5.2 to 1.29 dS m−1. [ABSTRACT FROM AUTHOR]

This paper presents an analytical analysis of a dual‐metal gate all around junctionless accumulation‐mode nanowire FET (DMGAA‐JAM‐NWFET) possessing a horizontal‐like non‐uniform doping profile. The 2‐D electrostatic potential distribution is evaluated using Poisson's equation under the applicable boundary conditions. Also, the impact of straggle length parameter and the peak doping concentration upon the device behavior is also examined. For authenticating the obtained analytical outcomes, TCAD simulations were also performed. Both the results were contrasted and found to be in good agreement. The outcomes obtained for non‐uniform doped DMGAA‐JAM‐NWFET are also compared with that of uniformly doped DMGAA‐JAM‐NWFET and finer electrical characteristics were noticed for non‐uniformly doped device. [ABSTRACT FROM AUTHOR]

New Cu (II), VO (II), Ag(I), and Pd (II)‐[BIP = 4,6‐dimethyl‐N‐(octahydro‐2H‐benzimidazol‐2‐ylidene)pyrimidin‐2‐amine] chelates have been synthesized by the reaction of BIP ligand resulting from the condensation of benzimidazole guanidine as well as acetylacetone with tested metal salts. The suggested structures of prepared compounds have been investigated spectroscopically through (FT‐IR, NMR, Mass spectra, and UV–Vis spectra), CHN analyses, conductivity, pH stability as well asmagnetic moment measurements. TGA studies have been also studied to govern the thermal behavior, stability, and decomposition of the metal chelates. Structural study of the tested chelates exposed their chemical transformation of ligand by chelation with the studied metals. The studies predicted a hexa‐coordinated geometry for the Cu and VO chelates, whereas tetra‐coordinated for the Ag and Pd chelates. DFT/B3LYP theoretical method was applied to obtain optimized geometry, molecular electrostatic potential (MEP) surface, and HOMO‐LUMO analysis for tested compounds. For estimation in the in vitro study, all the tested compounds have been screened for their biochemical features, including antioxidant, antimicrobial performances, and cytotoxicity. The antioxidant performance of prepared molecules has been studied by DPPH study and all the tested chelates displayed close antioxidant performance against the standard drugs. The cytotoxic analysis of tested compounds has been estimated against various cancer cell lines: (Hep‐G2, HCT‐116, and MCF‐7) using MTT analysis as well as calculated the cell viability for the corresponding human cell. The DNA binding capability for the tested compounds has been evaluated through absorption spectroscopic, viscosity estimation, as well as gel electrophoresis. The outcomes displayed a good binding tendency through the binding constant from 1.01 × 104 to 1.99 × 104 M−1 in the order BIPCu> BIPVO > BIPPd > BIPAg, respectively. Finally, docking simulation results indicated that the complexes were located in the intercalation site of DNA and confirmed experimental findings. [ABSTRACT FROM AUTHOR]

Hybrid Distribution Transformers (HDTs) offer a compelling alternative to traditional low-frequency transformers (LFTs), providing auxiliary services in addition to standard functionalities. By integrating LFTs with power converters, HDTs enhance the operational capabilities of the system. The specific configuration in which converters are connected to the transformer allows for the provision of multiple services. This can not only prevent network failures but also extend the lifespan of its components, an outcome that is highly desirable in a distribution grid. This article discusses an HDT developed to mitigate voltage fluctuations in the grid and to decrease the reactive power drawn from the secondary side of traditional LFTs. A finite-control-set model predictive control (FCS-MPC), in conjunction with linear controllers, is utilized for the effective management of the HDT converters. Two separate control loops are established to regulate voltage and reactive power on the secondary side of the transformer. Results from Hardware-in-the-Loop (HIL) testing affirm the proficiency of HDT in reducing grid voltage variations by 15% and in cutting reactive power consumption by up to 94%. The adopted control strategy and topology are demonstrated to be effective in stabilizing voltage and reactive power fluctuations while concurrently facilitating the charging of the converters' DC link directly from the grid. [ABSTRACT FROM AUTHOR]

The design and optimization of flotation machines hold significant importance in enhancing the industrial-grade coal beneficiation process. In this research, the flow field characteristics and flotation performance of a novel pulse jet flotation machine (PJFM) were investigated. The results showed that a PJFM equipped with an innovative pulse cavity can improve the mineralization efficiency of coal due to the coupling of multiple jet shapes. The aeration performance of this PJFM also exceeds the usual desired targets of coal flotation machines, which are characterized by an aeration uniformity coefficient higher than 70% and dominant bubbles of 100~200 μm and 200~300 μm, including a small amount of −100 μm bubbles. The cavitation of the pulse jet achieved the modification of the coal particle surface, and subsequently, the electric potential of the coal largely decreased in absolute value, and the floatability of the coal significantly improved. The concentrate yield of step release flotation increased by 12.42%, while the ash content was only 0.45% higher. Furthermore, in the early stage of flotation, the flotation rate of 0~0.074 mm coal slurry is the fastest and is preferentially floated; in the later stage, the flotation of 0.25–0.5 mm particles dominates. The PJFM demonstrates enhanced particle size selectivity and superior performance in selective flotation. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel energy minimization approach (called R-NCG) that combines a random batch idea with a nonlinear conjugate gradient method to accelerate the dynamics pre-equilibrium simulation of charged polymers in different systems. By using small but random batches, R-NCG can efficiently approximate the collective dynamics numerically while maintaining the numerical behaviours of standard NCG algorithm, and further improving its performance. Our simulation results suggest that the R-NCG can significantly reduce the computational cost of the minimization process for system with N-body interactions, thus reducing the time complexity to O(N). In other words, R-NCG method improves the problem of the dependence of CPU simulation time on the number of charged particles, and achieves acceptable accuracy in most cases. Our work can be helpful for accelerating the pre-equilibrium simulations of systems with N-body interactions, and confer new insights into the optimization of energy minimization algorithms in large electrostatic systems. In this work, we apply the random batch idea to the nonlinear conjugate gradient (NCG) method for improving the dependence of the CPU time on the number of charged particles in the energy minimization of the standard NCG method. Furthermore, we use the local iteration algorithm proposed in previous work to compute the spatial electrostatic potential distribution, which effectively improves the efficiency of the most time-consuming parts of calculating the electrostatic energy and its gradient values. Numerical results show that for different dielectric systems with N-body interactions, the NCG method based on random batch idea is computationally more efficient than the standard NCG method with acceptable accuracy in most cases (time complexity is reduced to O(N)). [ABSTRACT FROM AUTHOR]

This study investigates the counterintuitive behaviors of a microwave‐induced atmospheric pressure plasma jet (APPJ) under the influence of an external electrostatic field applied by one or a pair of parallel electrode plates subjected to DC voltages. The findings demonstrate that the plasma jet consistently deflects toward the electrode plate with an electrostatic potential, irrespective of the direction of the applied field. The deflection becomes more pronounced with increasing voltage on the electrode plate until the ionic wind generated by the high voltage significantly affects the jet's behavior. Remarkably, a negative voltage induces a greater deflection compared to a positive voltage. To further investigate this discovery, the dielectric properties and the non‐neutral characteristics of the APPJ are analyzed, and the simulations of the electric field distribution reveal a non‐uniform distribution, which plays a crucial role in understanding the mechanism behind the observed behaviors of the plasma jet. This study provides a comprehensive understanding of the underlying mechanism driving the observed phenomena and sheds light on the collective behavior of plasma jets under non‐uniform electric fields. The findings of this study offer valuable guidelines for investigating and controlling the behavior of APPJs. [ABSTRACT FROM AUTHOR]

In this paper, the electro-mechanical behavior of a flexoelectric nanobeam, considering the surface effect, is studied with an induced electric potential. Based on the modified strain gradient theory and Hamilton's variational principle, the governing differential equations of the nanobeam and the corresponding boundary conditions are obtained. The exact deflection solution of the flexoelectric nanobeam is derived from static bending. The relationship between the induced electric potential, including the surface effect, and the angle of the end of the cantilever beam is presented. Moreover, the characteristic equation of natural frequency is obtained by using a separate variable method under an open circuit with surface electrodes and an induced electric potential condition (OCI). The simulated results indicate the electro-mechanical response of the cantilever beam can be controlled by adjusting the flexoelectric coefficient, residual surface stress, and material length scale parameters of strain gradient theory. The free end of the beam with a platform phenomenon is also found by setting the appropriate parameters. The results also show that the residual surface stress and the ratio of beam thickness to material length scale parameters have a more significant effect on the effective frequency shift of the flexoelectric nanobeam. Therefore, considering the induced electric potential and surface effect is of great significance for the study of flexoelectric nanobeam sensors. [ABSTRACT FROM AUTHOR]

A dual output dual-frequency (DODF) resonant converter-based AC-AC induction heating (IH) by using asymmetrical duty cycle (ADC) control is presented in this paper. The proposed scheme gives two outputs with independent power control, which improves input power factor and achieves zero voltage switching (ZVS) with a wide range of operations. It includes two pairs of two half-bridge series resonant converters, each pair having one common capacitor along with various resonant frequencies. These converters are modulated with the ADC control scheme to obtain smooth operation. The proposed topology doesn't use the DC stage; it is directly connected to the power supply to produce high-frequency AC output. With the use of direct connection, the converter components are reduced when compared to conventional converters. There will be a reduction in voltage drop, power losses, cost of the converter and which will result in improved efficiency. Simulation results are obtained from PSIM 11.1.7 software. This scheme controls two different loads with an efficiency of 98.25%. [ABSTRACT FROM AUTHOR]

The modulation of electrostatic potential and optoelectronic characteristics of Janus MoSSe/MX2 (M = Mo, X = S, Se) van der Waals (vdW) heterostructures with strain engineering were studied by first principles. Based on the effection of uniaxial strain, the electronic properties of heterostructures not only are induced to form direct band gap and indirect band gap and even semiconductor-metal transformation, but also lead to strong interface-built electric field and excellent optical adsorption properties in the range of IR-visible. This work reveals the photophysical properties of MoSSe/MX2 vdW heterostructures as well as shows their strong potential for applications in novel optoelectronic devices and photocatalysis. [ABSTRACT FROM AUTHOR]

Ion evaporation from charged surfaces of ionic liquids has aroused significant interest due to its wide range of applications in various fields, such as ionic liquid ion sources (ILIS), electrospray thrusters, and high-precision etching, among others. This study delves into the transient electrohydrodynamics of ionic liquid drops undergoing ion evaporation with the assistance of an externally applied electric field. A transient electrohydrodynamic (EHD) model is developed to make up for the dearth of direct observation (visualization). A structure morphologically resembling the traditional cone-jet is depicted, featuring charged jets emitted from the drop's ends that subsequently break into tiny droplets. In contrast to the traditional cone-jet, this structure forms through a distinct mechanism, with charge depletion induced by ion evaporation playing a crucial role. A comprehensive exploration of parameter influences reveals the following key findings: (a) the normalized radius of the jets increases with the augmentation of the dimensionless number Ξ, which is defined as the ratio of the electric potential energy of ions to their activation energy for evaporation; (b) enhancing the electric Bond number Bo, which quantifies the ratio of Maxwell stress to surface tension, expedites the temporal evolution of tip streaming. [ABSTRACT FROM AUTHOR]

We treated the reconstruction process of pyrite-type transition metal sulfides (TMSs) during oxygen evolution reaction (OER) process as a potential-dependent electrochemical reaction similar to OER, i.e. , sulfide oxidation reaction (SOR). Based on this analysis method, the reconstruction mechanism of various TMSs was elucidated and new descriptors for TMSs reconstruction were proposed: U SOR and ΔU, which provides a significant contribution to the understanding of the mechanism and quantifying this surface behavior. [Display omitted] Reconstruction universally occurs over non-layered transition metal sulfides (TMSs) during oxygen evolution reaction (OER), leading to the formation of active species metal (oxy)hydroxide and thus significantly influences the OER performance. However, the reconstruction process and underlying mechanism quantitatively remain largely unexplored. Herein, we proposed an electrochemical reaction mechanism, namely sulfide oxidation reaction (SOR), to elucidate the reconstruction process of pyrite-type TMSs. Based on this mechanism, we evaluated the reconstruction capability of NiS 2 doped with transition metals V, Cr, Mn, Fe, Co, Cu, Mo, Ru, Rh, and Ir within different doped systems. Two key descriptors were thus proposed to describe the reconstruction abilities of TMSs: U SOR (the theoretical electric potential of SOR) and ΔU (the difference between the theoretical electric potential of SOR and OER), representing the initiation electric potential of reconstruction and the intrinsic reconstruction abilities of TMSs, respectively. Our finding shows that a lower U SOR readily initiate reconstruction at a lower potential and a larger ΔU indicating a poorer reconstruction ability of the catalyst during OER. Furthermore, Fe-doped CoS 2 was used to validate the rationality of our proposed descriptors, being consistent with the experiment findings. Our work provides a new perspective on understanding the reconstruction mechanism and quantifying the reconstruction of TMSs. [ABSTRACT FROM AUTHOR]

Context: Why are the halonium cations so effective in forming strongly-bound complexes? We directed our research to address this question and we present electrostatic potential data for the valence-state halogen atoms X and halonium cations X+, where X = Cl, Br, I. The electron densities and electrostatic potentials of the halonium cations show considerably greater anisotropy than do the valence state halogens. The distances from the electrostatic potential surface maxima to the halogen nuclei are about 0.5 Å smaller than the distances from the electrostatic potential surface minima to the nuclei, giving the halonium cations each a more disk-like shape than the corresponding neutral valence state halogens. Their surface electrostatic potentials are totally consistent with the directionalities of halonium cations in complexes and the strengths of their interactions. To add perspective to this brief report, we have included calculations of the isotropic cation K+ and noble gas Kr. Methods: The calculations of the electrostatic potentials of the valence states of the halogen atoms Cl, Br and I and the halonium cations Cl+, Br+ and I+, as well as K+ and Kr, on 0.001 au contours of their electronic densities were carried out with Gaussian O9 and the Wave Function Analysis – Surface Analysis Suite (WFA-SAS) at the M06-2X/6–31 + G(d,p) and M06-2X/3-21G* levels. [ABSTRACT FROM AUTHOR]

Luminal type breast cancer is a type of breast cancer that has a favorable prognosis in comparison to other forms. In accordance with the proliferation index, luminal-type breast malignancy is divided as luminal A and B types. The combination of two molecules will be a more effective strategy for the treatment of breast cancer. In this study, the structural and different spectroscopic parameters for the 4-hydroxy3, 5-dimethoxybenzoic acid-pyrazine 2-carboxamide cocrystal were calculated using quantum mechanics employing the B3LYP/6–311++G (d,p) approach. With the use of XRD data, the optimized geometrical parameters were compared. The HOMO-LUMO, molecule electrostatic potential surfaces, and vibrational investigations of the cocrystal are all computed. The possibility of charge transmission inside the particle is demonstrated by the minimal HOMO–LUMO energy gap. The existence of intermolecular OH...O hydrogen bonds, which are brought about by the interface of the oxygen lone pair with the anti-bonding orbital, was demonstrated by NBO examination. The drug-likeness possessions exhibited the safety profile of the 4-hydroxy-3,5-dimethoxybenzoic acid-pyrazine-2-carboxamide adduct. The results of molecular docking indicate that the cocrystal of 4-hydroxy3, 5-dimethoxybenzoic acid and pyrazine 2-carboxamide revealed better binding ability against luminal type breast cancer proteins with docking values of −8.3, −7.6, and −8.7 kcal/mol. [ABSTRACT FROM AUTHOR]

The present work focuses on the structural properties, spectroscopic signatures, intermolecular hydrogen bonding interactions, chemical and biological activity of nicotinamide (NIC) based on its monomeric and trimeric models using density functional theory and vibrational spectroscopy. FT-IR and FT-Raman spectra were obtained using the double-side forward-backward acquisition mode under vacuum. UV-Vis absorption spectra were recorded in methanol and compared with the calculated values. Geometry optimization and vibrational wavenumbers were obtained with the aid of Gaussian 09 program packages. The structural analysis of NIC revealed that the trimeric model was in better agreement with the experimental values than the monomer due to the incorporation of nearest hydrogen bond interactions. Spectroscopic results showed that NH2 and C = O groups of NIC were involved in intermolecular interactions in the trimeric model. The natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) analyses determined the presence, strength as well as nature of the hydrogen bonds were partially covalent. The lesser value of the HOMO-LUMO energy gap for the trimeric model indicated higher reactivity than monomer. Moreover, chemical reactivity was calculated using molecular electrostatic potential surface (MESP) and reactivity descriptors. The docking studies for NIC with several targets explored its biological activity. [ABSTRACT FROM AUTHOR]

Schiff bases have advanced physical, chemical, and medicinal properties, making them strong biological agents. Comparable FTIR, UV-VIS, 1HNMR, 13CNMR spectra confirmed the successful formation of N-N-(1,2-Phenylene)bis(1-(4-bromophenyl)methanimine) (CS3) compound. Geometry was optimized using DFT with B3LYP/cc-pVDZ basis set. Obtained energy gap of the compound was 2.07 eV. Carbon and oxygen atoms were electrophilic, according to molecular electrostatic potential analysis. Mulliken charge analysis found that C atoms have + ve and -ve charges, H atoms have only positive charges, while Br, O, and N atoms have only -ve charges. The ELF analyzed the molecule and found that the atoms of C, N, and Br all had delocalized electron density. The wave function LOL identified localized orbital positions in the hydrogen atoms. RDG maps provided various non-covalent interactions. Synthesized compound was docked using PDB: 2ZM5 protein, with the lowest binding attractions obtained, are −5.44 (7BYE) kcal/mol. [ABSTRACT FROM AUTHOR]

Present investigation deals with the response of a piezoelectric hollow sphere that is subjected to sudden thermal shock. Loading and boundary conditions are assumed to be symmetric so the response of the sphere is also considered to be symmetric. The governing equations of the vessel are obtained which are three in number. These equations include the equation of motion, the energy equation and the Maxwell equation. The energy equation is established in the framework of single relaxation time theory of Lord and Shulman. The established equations are written in terms of temperature change, radial displacement, and electric potential. These equations are provided in a dimensionless presentation for the sake of generality. After that with the aid of the generalized differential quadrature method, the established equations are discreted. Also Newmark time marching scheme is applied to trace the radial displacement, electric potential, and temperature change in time domain. Novel numerical results are then provided to explore the propagation and reflection of electrical, thermal and mechanical waves in a hollow sphere. It is shown that temperature wave propagates with finite speed within the framework of the Lord–Shulman theory. [ABSTRACT FROM AUTHOR]

Chitosan is a natural biopolymer that is classified among the most important biodegradable polysaccharides widely used in different environmental and industrial applications, such as tissue engineering, biomedical devices, electronics and supercapacitors, water filtration, and food packaging. Theoretical infrared spectra of chitosan were computed using both Hartree–Fock (HF) and Density Functional Theory (DFT) methods, with different basis sets, including 3-21g, 6-31g, 6-311g, LANL2DZ, and LANL2MB, to identify the ideal basis set that is closest to the experimental results. DFT:B3LYP/3-21g** was the best model for chitosan and was used to investigate its functionalization with various functional groups such as (OH, NH2, COOH, CH3, CHO, CN, SH) and graphene oxide (GO). Molecular electrostatic potential, total dipole moment, and HOMO–LUMO band gap (∆E) calculations indicated that Chitosan-GO is the most reactive and stable structure, with a ∆E of 0.3023 eV. Consequently, Chitosan–GO composite was prepared and analyzed using ATR–FTIR spectroscopy. The spectra revealed a new band at 1620 cm−1, which was attributed to the COOH group of GO and was red-shifted owing to the hydrogen bonding between the GO and NH2 of chitosan, confirming the synthesis of Chitosan–GO composite. The significant improvement in the electronic properties of Chitosan-GO based on the obtained results promotes it to be used in electronic applications such as the development of electrodes for supercapacitors. [ABSTRACT FROM AUTHOR]