Search

In this research, 2-amino-4,7-dihydro-5H-spiro[benzo[b]thiophene-6,2'- [1,3]dioxolane]-3-carbonitrile (ST) was synthesized using the Gewald method, starting with 1,4-dioxaspiro[4,5]decan-8-one ketone. The structures of compounds were characterized through FT-IR, 1H-NMR, and 13C-NMR spectra. The antimicrobial properties of the compounds were examined by the disk diffusion process. The compounds (N1-3) did not exhibit effectiveness against the E. Coli (ATCC) and S. Aureus (ATCC) bacteria. The molecular electrostatic potential surface (MEP) of all compounds was calculated via DFT calculations based on the optimized geometries at the B3LYP/6-31G (d,p) level of theory. Negative potential regions were located over the oxygen and nitrogen atoms, whereas positive potential regions were identified over the oxygen and sulfur atoms. Conceptually, computations of the molecular structures of the compounds were carried out using molecular modeling software, specifically GaussView 5.0 and the GAUSSIAN 09 package programs. Additionally, computations were performed for the HOMO and LUMO molecular orbitals of isolated molecules in the gas phase. Molecular electrostatic potential (MEP) surfaces were used to visualize potential interactions between receptors and ligands over the steady-state geometries of the molecules and to highlight the electrophilic and nucleophilic regions of the molecules. [ABSTRACT FROM AUTHOR]

For mining engineering and geological engineering, the deformation and fracture of coal and rock are the essential causes of dynamic disasters. In this paper, the loading experimental system was established on gas-bearing coal, to study the internal relationship between the spatial distribution of EP and the development process of damaging localization on coal mass. The results indicated the temporal response of EP signal could reflect the stress state and damage degree of gas-bearing coal, showing the precursor feather when coal mass failed. Particularly, when the stress dropped suddenly, the EP signal has a sudden mutation, and the acoustic emission (AE) signal suffered the pulsed increase, while the crack grew and expanded rapidly. Furthermore, when local severe damage occurs inside the coal mass, there was abnormal EP spatial distribution with high-value or dense contours in these zones, where simultaneously AE rupture events frequently occurred, and cracks expanded and gathered. The characteristics of EP spatial distribution can reveal the development process of coal mass damaging localization. Meanwhile, the mentioned zones with abnormal EP distribution above are hazard sources inducing coal mass’s instability and failure. The study results provide the foundational research work of fine forecasting on coal and gas outburst disaster hazard. [ABSTRACT FROM AUTHOR]

Critical values of voltage and ignition induction were determined for the self-sustained plasma discharge in the crossed electric and magnetic fields with both individual inert gases and their mixtures used as plasma-forming mediums. Ion current and the time derivative of the discharge current were the parameters used to visualize the ignition of the E × B discharge. The time dependences of the process are presented. The double structure of the ion current (discharge current) was discovered during ignition. The initial state of the working medium during the first jump in the discharge current was neutral gas, and the initial state for the second jump was plasma. The ion energy distributions obtained during ignition were characterized by the presence of the peak of ions created in the near-cathode region and the wide spectrum of energy that corresponded to the discharge gap. It was shown that the discharge ignition changes for the Penning pairs when the role of the plasma-forming gas changes between the main gas and the admixture. It was shown that the discharge properties are determined, among others, by the conditions under which the electric potential distribution is formed in the near-cathode layer. [ABSTRACT FROM AUTHOR]

This work was chiefly conceived to explore the substituent effects on thermodynamic, electronic and lipophilic characteristics of some quinazoline derivatives (Q1-Q4) from theoretical aspects. The variations caused by methyl, ethyl, chlorine and bromine substituents on the same carbon of the aromatic ring were evaluated with a computational approach. In accordance with this purpose, simultaneously, DFT-based calculations were performed for vacuum and two different surroundings (DMSO and water) on methaqualone (Q1), etaqualone (Q2), mecloqualone (Q3), and mebroqualone (Q4) compounds by using the B3LYP functional and 6-311++G (d, p) splitvalence triple zeta basis set. The computed thermodynamic quantities revealed that the halogen substitution was more preferable. The effect of substituent modification on electrostatic surface features was evaluated visually by molecular electrostatic potential (MEP) mapping technique. To shed light on the chemical reactivity behaviors of the Q1-Q4, DFT-based reactivity identifiers were computed. Also, the intramolecular interactions affected by substitution were evaluated on the basis of the Natural Bond Orbital (NBO) theory. The NBO results revealed that p-p* interactions predominate for each compound. The lipophilic character analyzes of the mentioned compounds were evaluated both numerically and visually. The data of both methods support each other. [ABSTRACT FROM AUTHOR]

Expanding upon the "Basic Physical Chemistry Laboratory" module focused on the measurement of primary battery electromotive force (EMF), this paper introduces a novel experimental design. The design incorporates the often-neglected liquid junction potential, investigating its relationship with reversible battery EMF and the total EMF of the primary battery. The revised apparatus is cost-effective, straightforward, and offers stable and reproducible measurements for liquid junction potential. This improved experiment provides a more comprehensive and accurate representation of the components contributing to the total EMF of the primary battery, transcending the limitations of merely measuring reversible battery EMF. As a result, the experiment aids students in forming a well-rounded and accurate understanding of primary batteries and the underlying principles of electrochemistry. Furthermore, the measured liquid junction potential is applicable in calculating ion transference numbers, allowing for the integration of this advanced concept into the curriculum and thereby bolstering students' comprehensive skill set. [ABSTRACT FROM AUTHOR]

A mesoscopic model for a polymer-based magnetoelectric (ME) composite film is developed. The film is assumed to consist of a piezoelectric polymer matrix of the PVDF type filled with CFO-like single-domain nanoparticles. The model is treated numerically and enables one to obtain in detail the intrinsic distributions of mechanical stress, polarization and electric potential and helps to understand the influence of the main configurational parameters, viz., the poling direction and the orientational order of the particle magnetic anisotropy axes on the electric response of the film. As the model is fairly simple—it uses the RVE-like (Representative Volume Element) approach with a single-particle cell—the results obtained are rather of qualitative than quantitative nature. However, the general conclusions seem to be independent of the particularities of the model. Namely, the presented results establish that the customary ME effect in composite films always comprises at least two contributions of different origins, viz., the magnetostrictive and the magnetoactive (magnetorotational) ones. The relative proportion between those contributions is quite movable depending on the striction coefficient of the particles and the stiffness of the polymer matrix. This points out the necessity to explicitly take into account the magnetoactive contribution when modeling the ME response of composite films and when interpreting the measurements on those objects. [ABSTRACT FROM AUTHOR]

This research presents a theoretical analysis based on structural and spectral data to elucidate the molecular interaction mechanism of propiconazole, a fungicide. The optimization, vibration bands, and electronic structure analysis were conducted using the B3LYP level density functional theory with the aug-cc-pVDZ basis set. Additionally, molecular docking simulations were performed to uncover the mechanism and modes of interaction between the propiconazole pesticide and DNA (PDB ID: 1BNA). The investigation revealed that the compound exhibits reactivity and polarizability, as indicated by the HOMO–LUMO energy range. The analysis of the molecular electrostatic potential surface (MEPS) and electrostatic potential surface (ESPS) demonstrated that the N6 and N7 atoms possess negative potential and serve as active sites for nucleophilic attacks. Similar observations were made for the oxygen and chlorine atoms. The molecular docking analysis indicated a preference for the propiconazole ligand to bind to DNA at sites involving nitrogen, oxygen, and chlorine atoms, specifically with guanine (G)-cytosine (C) interactions. Notably, the remarkable concordance between the MEP and molecular insertion results further supports these findings. These results provide valuable insights into the mechanism of DNA damage and the toxicological effects of the pesticide. Furthermore, the molecular docking analysis led to observations of changes in the optimized structure of the propiconazole molecule. For instance, the bond length between Cl1–C15, which was initially determined as 1.73 Å in the optimized structure, was recalculated as 1.77 Å following the molecular docking analysis. [ABSTRACT FROM AUTHOR]

In this work, electrospun polyvinylidene-trifluoroethylene (PVDF-TrFE) was utilized for its biocompatibility, mechanics, and piezoelectric properties to promote Schwann cell (SC) elongation and sensory neuron (SN) extension. PVDF-TrFE electrospun scaffolds were characterized over a variety of electrospinning parameters (1, 2, and 3 h aligned and unaligned electrospun fibers) to determine ideal thickness, porosity, and tensile strength for use as an engineered skin tissue. PVDF-TrFE was electrically activated through mechanical deformation using low-intensity pulsed ultrasound (LIPUS) waves as a non-invasive means to trigger piezoelectric properties of the scaffold and deliver electric potential to cells. Using this therapeutic modality, neurite integration in tissue-engineered skin substitutes (TESSs) was quantified including neurite alignment, elongation, and vertical perforation into PVDF-TrFE scaffolds. Results show LIPUS stimulation promoted cell alignment on aligned scaffolds. Further, stimulation significantly increased SC elongation and SN extension separately and in coculture on aligned scaffolds but significantly decreased elongation and extension on unaligned scaffolds. This was also seen in cell perforation depth analysis into scaffolds which indicated LIPUS enhanced perforation of SCs, SNs, and cocultures on scaffolds. Taken together, this work demonstrates the immense potential for non-invasive electric stimulation of an in vitro tissue-engineered-skin model. [ABSTRACT FROM AUTHOR]

The S4 segment of voltage-sensing domains (VSDs) directly responds to voltage changes by reorienting within the electric field as a permion. A narrow hydrophobic "gasket" or charge transfer center at the core of most VSDs focuses the electric field into a narrow region and catalyzes the sequential and reversible translocation of S4 positive gating charge residues across the electric field while preventing the permeation of physiological ions. Mutating specific S4 gating charges can cause ionic leak currents through the VSDs. These gating pores or omega currents play important pathophysiological roles in many diseases of excitability. Here, we show that mutating D129, a key countercharge residue in the Ciona intestinalis voltagesensing phosphatase (Ci-VSP), leads to the generation of unique anionic omega currents. Neutralizing D129 causes a dramatic positive shift of activation, facilitates the formation of a continuous water path through the VSD, and creates a positive electrostatic potential landscape inside the VSD that contributes to its unique anionic selectivity. Increasing the population or dwell time of the conducting state by a high external pH or an engineered Cd2+ bridge markedly increases the current magnitude. Our findings uncover a new role of countercharge residues in the impermeable VSD of Ci-VSP and offer insights into mechanisms of the conduction of anionic omega currents linked to countercharge residue mutations. [ABSTRACT FROM AUTHOR]

Flexoelectricity, referring to the electrical polarization generated by strain gradients, is an electromechanical coupling phenomenon in all dielectric materials. Based on the Kirchhoff plate theory, this paper investigates the influence of flexoelectricity on the electromechanical coupling response of piezoelectric circular nanoplates with different electric boundary conditions. Using the variational principle and Gibbs free energy, the governing equations and boundary conditions of piezoelectric nanoplates are derived. The analytical solutions of the deflection, polarization, and induced electric potential are obtained. The results show that the flexoelectric effect is size-dependent and has a more significant influence on the electrostatic responses than the piezoelectric effect at the nanoscale. The results also show that the induced electric potential due to the flexoelectric effect may be helpful for sensing or energy harvesting designs. [ABSTRACT FROM AUTHOR]

Based on the generalized thermoelastic theory, the physical changes of a finite length rod, which is composed of one-dimensional (1D) hexagonal piezoelectric quasicrystals (PQCs) fixed on both sides and subjected to a moving heat source, are studied. The numerical solutions are obtained using the Laplace transform and its numerical inversion. The effects of displacement, stress, temperature and electric potential on velocity of moving heat source and time were studied. It can be seen from the distribution that the temperature, displacement, electric potential and stress of the rod all increase when the time increases, while the influence of the heat source velocity is opposite. [ABSTRACT FROM AUTHOR]

The X-ray crystal structures of some aminopyridine derivatives as contained in CSD have been examined for structure optimization and quantum chemical analysis. The experimental data and quantum chemical analysis uncover intriguing findings. The research extensively explores optimized structural geometry, the frontier orbital energy gap, the distribution of atomic Mulliken charges, and the molecular electrostatic potential (MEP). The Hirshfeld surfaces and their 2D fingerprint plots confirm the existence of N-H... N, O-H...N, and N-H...O intermolecular interactions in the molecules. The void volume percentage, which has been calculated to determine the physical strength of each molecule, is generally consistent among all the identified molecules. The energy frameworks reveal that electrostatic energy emerges as the dominant factor in each structure. [ABSTRACT FROM AUTHOR]

In the present study, anionic hydrogels, acrylamide (AAm) monomer, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) comonomer were prepared in the presence of two different cross-linkers. Then, super-anionic hydrogels were prepared by converting the amide groups of neutral AAm in anionic hydrogels to hydroxamic acid with hydroxylamine hydrochloride. The hydrogels were characterized by FTIR, SEM, TG, and DSC analyses. Uranyl adsorption in the hydrogels was investigated by spectroscopic, kinetic, and equilibrium studies. It was determined that uranyl adsorption kinetics in hydrogels were compatible with pseudo-second-order and intra-particular diffusion models. It was determined that the uranyl adsorption isotherms on the hydrogels were L-type according to the Giles isotherm classification. Adsorption parameters were calculated by applying Freundlich and Langmuir models to these isotherms. In addition, it was determined that the amount of adsorbed uranyl increased with the increase in adsorbent mass, did not change with temperature, decreased in the range of pH 2–4, and increased at pH 4–7. It was observed that super-anionic hydrogels had the highest adsorption capacity among these new hydrogels. In addition, molecular electrostatic potential (MEP) mapping was performed to predict the reactive regions of the hydrogels. The results showed that the theoretical and experimental data of hydrogels are in agreement with each other. In conclusion, it can be said that the anionic and super-anionic hydrogels prepared in this study are unique hydrogels with fast and effective properties in removing uranyl. [ABSTRACT FROM AUTHOR]

In some power systems, the voltage waveform contains frequency components less than fundamental, called subharmonics or subsynchronous interharmonics. Voltage subharmonics can be both positive- and negative-sequence, independent of their frequency (order). Subharmonics exert harmful effects on sundry electrical equipment, especially on rotating machinery; they cause various noxious phenomena, such as a local saturation of the magnetic circuit, increases in power losses and windings temperature, and torque pulsations leading to vibration of unacceptable severity. Notably, previous works reported excessive vibration of rotating machinery only under no-load, while under full load, rather moderate vibration occurred. This study deals with vibration analysis of a line-start permanent magnet synchronous motor (LSPMSM) supplied with the voltage containing negative-sentence subharmonics. Experimental investigations were conducted for a 3 kW, four-pole production LSPMSM for subharmonics of various values and frequencies. Voltage subharmonics of values significantly less than reported in real power systems were found to cause unacceptable vibration, especially under full load. [ABSTRACT FROM AUTHOR]

A relation between classical electrostatic fields and Shrödinger-like Hamiltonians is evidenced. Hence, supersymmetric quantum potentials analogous to classical electrostatic fields can be constructed. Proposing an ansatz for the electrostatic potential as the natural logarithm of a nodeless function, it is demonstrated that the electrostatic fields fulfil the Bernoulli equation associated to a second-order confluent supersymmetric transformation. By using the so-called confluent algorithm, it is possible, given a charge density, to find the corresponding electrostatic field as well as the supersymmetric potentials. Furthermore, the associated charge density and the electrostatic field profile of Schrödinger-like solvable potentials can be determined. [ABSTRACT FROM AUTHOR]

To avoid false negative results due to the low cross-reactivity rate (CR) in rapid immunoassay, a group-specific antibody with homogeneous CR toward target compounds is needed for accuracy. In this study, tylosin (TYL) and tilmicosin (TM) were selected as model molecules. Firstly, two-dimensional similarity, electrostatic potential energy, spatial conformation and charge distribution of the haptens TYL-CMO, TYL-6-ACA, TYL-4-APA, TYL-CHO and DES-CMO and target compounds of TYL and TM were obtained using Gaussian 09W and Discovery Studio. The optimal hapten was DES-CMO because it is the most similar to TYL and TM. Subsequently, the mAb 14D5 cell line was obtained with IC50 values of 1.59 and 1.72 ng/mL for TYL and TM, respectively, and a CR of 92.44%. Finally, amorphous carbon nanoparticles (ACNPs) were conjugated with mAb 14D5 to develop an accurate lateral flow immunoassay (LFA) for detection of TYL and TM by the reflectance value under natural light. The recoveries of TYL and TM ranged from 77.18 to 112.04% with coefficient of variation < 13.43%. The cut-off value in milk samples was 8 ng/mL, and the limits of detection were 11.44, 15.96, 22.29 and 25.53 μg/kg for chicken muscle, bovine muscle, porcine muscle and porcine liver samples, respectively, and the results being consistent with HPLC–UV. The results suggest that the developed LFA is accurate and potentially useful for on-site screening of TYL and TM in milk and animal tissue samples. [ABSTRACT FROM AUTHOR]

In this study, the effects in terms of electric stress of composite voltages on a high-voltage disconnector were investigated. The main purpose of this study is to determine and evaluate the effects of the conditions that may occur in real working conditions but out of the type tests. As for the disconnector model, one phase of a center-break disconnector was considered. In order to examine the effects of composite voltages on high-voltage disconnectors, a model is defined in the Comsol Multiphysics program. Different types of voltages such as operating voltage, 50 Hz test voltage, lightning impulse voltage, and composite voltage, were applied to the 170 kV disconnector model separately. After applying a composite voltage consisting of power frequency voltage and lightning impulse voltage to the disconnector, electric potential and electric field distributions were obtained. It has been observed that the maximum electric potential and the maximum electric field strength values on the disconnector are higher when composite voltage is applied than when non-composite voltage is applied to the disconnector. It is observed that the intensity of the electric field lines increases near the contacts of the current-carrying arm and the main contacts of the disconnector. [ABSTRACT FROM AUTHOR]

Context: The complexes formed as a result of the interactions between cyanophosphine (CP, H2PCN) and hypohalous acid molecules (HOX, X = F, Cl, Br, and I) were studied by employing ab initio computations conducted at the MP2/aug-cc-pVTZ level. Three types of complexes were acquired (I, II, and III) as a result of the (O∙∙∙P) pnicogen bond, the (N∙∙∙H) hydrogen bond, and the (N∙∙∙X) halogen bond interaction, respectively. The results of harmonic vibrational frequency calculations with no imaginary frequencies confirmed the structures as minima. In addition, given the interaction energy of the complexes, hydrogen bond complexes of structure II have the highest stability compared to other structures. In all studied complexes, the strength of the interactions depended on the electronegativity of the halogen atoms. The characteristics and nature of the whole three types of complexes were examined and evaluated with natural bond orbital (NBO), atom in molecules (AIM), molecular electrostatic potential (MEP) maps, non-covalent interaction (NCI) index, and electron density difference (EDD) analyses. Method: The optimization of all complexes and corresponding monomers was conducted through the ab initio method, employing the MP2 level along with the aug/cc-pVTZ basis set for all atoms, except for the iodine (I) atom, for which the aug-cc-pVTZ (PP) basis set was employed. Subsequent frequency calculations were executed to ascertain the minimum energy state of the complexes at the MP2 level and the aug/cc-pVTZ basis set, utilizing Gaussian09 software. The MEP maps of the monomers were generated using the analysis-surface suite (WFA-SAS) software package. To probe the orbital interactions within the studied complexes, NBO analysis was performed employing NBO software. The assessment of bond nature, topological features, and electron density values at critical points for the studied complexes was undertaken using AIMAll software. The NCI index was derived utilizing Multiwfn software, and its three-dimensional representation was rendered using VMD software. [ABSTRACT FROM AUTHOR]

Context: In this work, we designed ten new organic phenothiazine dyes bridged by different πi-spacers (PTZ1-PTZ10) of D-π-A type based on the synthesized dye CC202-III for their efficacy in dye-sensitized solar cells (DSSC) applications. To learn how various π-spacers affect their performance in DSSCs, these isolated dyes and dye-cluster systems have had their geometries, electronic structures, absorption spectra, dipole moments, and molecular electrostatic potential examined and talked about. Additionally, a number of quantization parameters that affect power conversion efficiency (PCE), including light collection efficiency (LHE), reorganization energy (λtotal), vertical dipole moment (μnormal), strength electron injection driving force (ΔGinject), regeneration driving force (ΔGreg), excited state lifetime (τ), and open circuit voltage (VOC), were calculated in order to identify the organic dyes that would be best suited for DSSC applications. Calculated results revealed that the designed dyes PTZ3, PTZ4, PTZ5, and PTZ10 exhibit a lower energy gap among all dyes compared to the corresponding CC202-III. Additionally, PTZ3, PTZ4, PTZ5, PTZ7, PTZ8, PTZ9, and PTZ10 exhibit significant red-shifted absorption spectra compared to the other dyes with a larger oscillator strength, which improves the photocurrent density of the devices. The findings thus imply that bridge modification is a workable tactic to raise DSSC effectiveness. Method: We used density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to study the electronic and photovoltaic properties of the dyes designed (PTZ1–PTZ10) to assess their effectiveness in DSSCs. DFT and TD-DFT simulations are theoretically used to deeply analyze key characteristics of all organic dyes that affect open-circuit voltage (VOC) and short-circuit current (JSC) to identify structure–property relationships. [ABSTRACT FROM AUTHOR]

A quinoline-derived Schiff base ligand, namely 2,5-Dimethyl-N1,N4-bis((quinoline-4-yl)-methylene) benzene-1,4-diamine 1 was characterized by single crystal X-ray structural studies that included a thorough examination of visualizing and investigating intermolecular interactions in molecular crystals via the Hirshfeld surface. The crystal packing of 1 displays intermolecular π∙∙∙π stacking interactions, resulting in a one-dimensional array. The major role of π∙∙∙π stacking interactions in stabilizing the crystal is also supported by the pre-eminence of dispersion energy over the other components in interaction energy calculation and energy framework analysis. The electronic structure of the ligand computed at B3LYP/6-311++G(d,p) level shows a good correlation with the experimentally obtained structure. Additionally, the Fukui function is calculated to identify the electrophilic and nucleophilic active sites in the molecule. [ABSTRACT FROM AUTHOR]

Automotive relays are used in vehicles, subject to various mechanical vibration levels during regular operation. Vibration analysis helps ensure that the relay can withstand these vibrations without malfunctioning. It is essential for the relay's durability and long-term dependability. In this work, vibration analysis is carried out for the relay using an electrodynamic shaker, and the electrical contact resistance (ECR) is obtained. Relays used in vehicles undergo vibration because of the environmental and on-road conditions. Hence, vibration analysis is mandatory for automotive relays. ECR is obtained under DC and AC static environments with a frequency of 10 Hz to 70 Hz. Vibration analysis is carried out using an electrodynamic shaker experimental setup. Finite Element Analysis (FEA) using COMSOL Multiphysics is carried out to obtain the electrical and mechanical parameters of relay electrical contact. The highest current density occurs at the contact surface edges that have been visualized. Vibration analysis examines the dynamic behavior of electrical contacts in relays. This study also delves into prescribed displacement, Von Mises stress, and total displacement performance under dynamic conditions. [ABSTRACT FROM AUTHOR]

Anomalous transport of multi-species plasma related to the resistive ballooning and resistive drift wave turbulence is considered in a "cold" ion approximation. It is found that similar to the resistive drift wave turbulence [see A. R. Knyazev and S. I. Krasheninnikov, Phys. Plasmas 31, 012502 (2024); and S. I. Krasheninnikov and R. D. Smirnov, Phys. Plasmas (to be published)] the addition of the ballooning drive does not change the main features of anomalous transport of the multi-species plasma: (i) The transport of all ion species is described as a transport of the passive scalars in the turbulent field of the electrostatic potential and electron density perturbation; (ii) the density of ion species with a larger ratio of the mass to charge has the tendency to the accumulation/depletion in the vortices of plasma flow; and (iii) the cross-field transport of all plasma species (including electrons and ions) is described by the same anomalous transport coefficient. [ABSTRACT FROM AUTHOR]

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]

Diatoms are a group of marine algae that are responsible for a significant part of global oxygen production. Adapted to life in an aqueous environment dominated by the blue–green light, their major light-harvesting antennae—fucoxanthin–chlorophyll protein complexes (FCPs)—exhibit different pigment compositions than of plants. Despite extensive experimental studies, until recently the theoretical description of excitation energy dynamics in these complexes was limited by the lack of high-resolution structural data. In this work, we use the recently resolved crystallographic information of the FCP complex from Phaeodactylum tricornutum diatom [Wang et al., Science 363, 6427 (2019)] and quantum chemistry-based calculations to evaluate the chlorophyll transition dipole moments, atomic transition charges from electrostatic potential, and the inter-chlorophyll couplings in this complex. The obtained structure-based excitonic couplings form the foundation for any modeling of stationary or time-resolved spectroscopic data. We also calculate the inter-pigment Förster energy transfer rates and identify two quickly equilibrating chlorophyll clusters. [ABSTRACT FROM AUTHOR]

We present a density functional theory (DFT)-based, quantum mechanics/molecular mechanics (QM/MM) implementation with long-range electrostatic embedding achieved by direct real-space integration of the particle-mesh Ewald (PME) computed electrostatic potential. The key transformation is the interpolation of the electrostatic potential from the PME grid to the DFT quadrature grid from which integrals are easily evaluated utilizing standard DFT machinery. We provide benchmarks of the numerical accuracy with choice of grid size and real-space corrections and demonstrate that good convergence is achieved while introducing nominal computational overhead. Furthermore, the approach requires only small modification to existing software packages as is demonstrated with our implementation in the OpenMM and Psi4 software. After presenting convergence benchmarks, we evaluate the importance of long-range electrostatic embedding in three solute/solvent systems modeled with QM/MM. Water and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM/BF4) ionic liquid were considered as "simple" and "complex" solvents, respectively, with water and p-phenylenediamine (PPD) solute molecules treated at the QM level of theory. While electrostatic embedding with standard real-space truncation may introduce negligible errors for simple systems such as water solute in water solvent, errors become more significant when QM/MM is applied to complex solvents such as ionic liquids. An extreme example is the electrostatic embedding energy for oxidized PPD in BMIM/BF4 for which real-space truncation produces severe errors even at 2–3 nm cutoff distances. This latter example illustrates that utilization of QM/MM to compute redox potentials within concentrated electrolytes/ionic media requires carefully chosen long-range electrostatic embedding algorithms with our presented algorithm providing a general and robust approach. [ABSTRACT FROM AUTHOR]

Progress in sorting, separating, and characterizing ever smaller amounts of chemical and biological material depends on the availability of methods for the controlled interaction with nanoscale and molecular-size objects. Here, we report on the reversible, tunable trapping of single DNA molecules and other charged micro- and nanoparticles in aqueous solution using a direct-current (DC) corral trap setup. The trap consists of a circular, non-conductive void in a metal-coated surface that, when charged, generates an electrostatic potential well in the proximate solution. Our results demonstrate that stable, nanoscale confinement of charged objects is achievable over extended periods of time, that trap stiffness is controlled by the applied voltage, and that simultaneous trapping of multiple objects is feasible. The approach shows great promise for lab-on-a-chip systems and biomedical applications due to its simplicity, scalability, selectivity, and the capability to manipulate single DNA molecules in standard buffer solutions. [ABSTRACT FROM AUTHOR]

To reduce the false positive results caused by cross reactivity of the antibodies with other structural analogues, it is crucial to prepare a high specificity and sensitivity antibody against target for developing an accurate immunoassay. In this study, tilmicosin (TM) was selected as a model molecule. Firstly, two-dimensional similarity, electrostatic potential energy, mulliken atomic charges and overlapping of different haptens with TM were calculated using Gaussian 09W and Discovery studio, and the newly designed TM-HS was selected as the optimal hapten. Furthermore, a monoclonal antibody (mAb 12C8) was produced with the half maximal inhibitory concentration (IC50) of 0.36 ng/mL, and negligible cross-reactivity (CR) with other antibiotics. Finally, a lateral flow immunoassay (LFA) for the detection of TM based on amorphous carbon nanoparticles (ACNPs) labeled mAb 12C8 was developed by the reflectance value under natural light. The recoveries of TM ranged from 83.18% to 103.25% with a coefficient of variation (CV) < 12.47%. The results showed that the cut-off value of TM in milk samples was 1 ng/mL, and the limits of detection (LODs) for chicken muscle, bovine muscle, porcine muscle and porcine liver samples were 5.23, 5.98, 6.85 and 7.31 μg/kg, respectively. In addition, 40 real samples were tested by the LFA, and the detection results were consisted with that of high-performance liquid chromatography-UV detector (HPLC–UV). Those results indicated that the developed LFA is an accurate and useful tool for on-site screening of TM in milk and animal tissues. [ABSTRACT FROM AUTHOR]

The electric field potential of an intense axially symmetric electron beam with parameters typical of electron cooling systems in proton (ion) synchrotrons is calculated. A general case of electrons of relativistic energy is considered. [ABSTRACT FROM AUTHOR]

Ruppeiner scalar curvature can be considered as an empirical tool to explore the nature of interaction among the microstructures of black holes. In the extended phase space, the phase transitions and criticality are investigated for the dyonic black holes in an ensemble, where the electric potential Φ e is fixed. At first, we described the thermodynamic properties of dyonic black holes to investigate the P − V criticality. Further, the Ruppeiner scalar curvature is calculated in an ensemble with fixed Φ e utilizing the fluctuation coordinates (T , V). The behavior of interactions among the microstructures of the dyonic black holes in AdS is studied where the dominance of attractive or repulsive interaction is found to be dependent on the values of electric potential Φ e . [ABSTRACT FROM AUTHOR]

Heavy ion beam probe (HIBP) is a unique tool for studying the electric potential and various turbulence characteristics both in the core and at the edge of toroidal plasmas. The position of the HIBP measurement point in the plasma is determined by the probe beam energy and its entrance angle into the plasma. The probe beam energy is constant during the plasma discharge and determines the maximum penetration depth of the beam into the plasma. The beam entrance angle into the plasma can vary during the discharge, and the set of positions of HIBP measurement points for different beam entrance angles creates a so-called detector line. The set of detector lines for different probe beam energies represents a 2D region (detector array) in the vertical cross section of the plasma. The article presents a method for constructing 2D distributions of plasma parameters over the detector array on the T-10 tokamak by the example of the plasma electric potential. [ABSTRACT FROM AUTHOR]

The microwave‐assisted synthesis, crystallographic studies, in‐silico docking and the evaluation of in‐vitro biological activities of 2‐(3,4‐dimethoxy)‐6‐(substituted phenyl)‐ imidazo[2,1‐b][1,3,4]thiadiazole‐5‐carbaldehydes is represented here. Single‐crystal X‐ray diffraction experiments were used to identify the crystal structure of the 6‐(4‐chlorophenyl)‐2‐(3,4‐dimethoxybenzyl)imidazo[2,1‐b][1,3,4]thiadiazole‐5‐carbaldehyde. Using fingerprint plots, Hirshfeld surface analysis was used to confirm the contributions of distinct intermolecular interactions in the development of the crystal packing. Further, density functional theory calculations were employed to calculate the molecule's electronic properties. The chemically active regions on the molecule are identified by analysing the molecular electrostatic potential map. in‐silico studies revealed that the molecules can be effectively used as antibacterial agents by taking the 3q82 receptor with chloramphenicol as a standard. As compared to the chloramphenicol standard, in‐vitro tests showed that molecules 4 a, 4 b, 4 c, and 4 f had a zone of inhibition that ranged from 9 to 11 mm against both Gram‐positive (Bacillus subtilis) and Gram‐negative (Escherichia coli) bacteria. The minimum inhibitory concentration was between 40 to 70 μg/ml. These compounds′ Hydroxyl free radical scavenging activity was between 40 to 85 %. Whereas, DPPH radical scavenging activity was between 40 and 70 %. Percentage hemolysis or cell protective activity of the compounds was ineffective at 20–40 %. [ABSTRACT FROM AUTHOR]

The feasibility of using quantum dots fabricated from materials with built-in spontaneous polarizations for the electric potential stimulation of biological structures in aqueous environments is evaluated by modeling the electric potential produced in the vicinity of such quantum dots. By modeling the external potential created by the spherical nanoscale region of a material with spontaneous polarization, and by considering Debye screening in the vicinity of the quantum dot, it is found that electric potential around these nanostructures is sufficient to cause physiological effects in selected biological systems. These findings suggest that quantum dots may be used in lieu of quantum dots with polarizations produced using an external laser to cause physiological effects. The elimination of the external laser represents a significant benefit of using quantum dots with permanent, built-in spontaneous polarization. [ABSTRACT FROM AUTHOR]

In this study, tert-butyl 4-(5-bromopyridin-2-yloxy)piperidine-1-carboxylate was synthesized. The title compound was characterized using ¹H NMR, 13C NMR, MS, and FT-IR techniques, and its single crystal was evaluated using X-ray diffraction (XRD). The molecular structure was optimized using the density functional theory (DFT) at the B3LYP/6-311+G(2d, p) level. The optimized structure was also compared with the crystal structure determined using single-crystal (XRD), and the results were consistent. Molecular electrostatic potential (MEP) and frontier molecular orbital (FMOs) analyses of the title compound were preformed using computational methods. Infrared vibrational analysis of the target compound was also conducted. [ABSTRACT FROM AUTHOR]

The molecular properties of a biphenyl benzoate based ferroelectric liquid crystal compound were estimated using DFT/6-31G method. Non Linear Optical properties of the compound have been estimated by calculating its polarizability and hyperpolarizability. Frontier molecular orbital (FMO), Molecular electrostatic potential (MEP) and Infrared (IR) spectra have been simulated. Global parameter and a few thermodynamic parameters have also been calculated. The phase sequence has been confirmed by polarizing optical microscopy. The spontaneous polarization and rotational viscosity of the compound have been measured. From results the efficacy of the compound in NLO or electro optical applications have been inferred. [ABSTRACT FROM AUTHOR]

Closed-shell phenalenyl (PLY) systems are increasingly becoming more attractive as building blocks for developing promising catalysts and electroactive cathode materials, as they have tremendous potential to accept electrons and participate in redox reactions. Herein, we report a PLY-based dinuclear [Fe III2 (hmbh-PLY)3] complex, 1, and its utility as a cathode material in a H2O2 fuel cell. Complex 1 was synthesized from a new Schiff base ligand, (E)-9-(2-(2-hydroxy-3-methoxybenzylidene)hydrazineyl)-1H-phenalen-1-one, hmbh-PLYH2, designed using a PLY precursor, Hz-PLY. The newly derived ligand and complex 1 were characterized by various analytical techniques, including single-crystal X-ray diffraction (SCXRD). The cyclic voltammetry (CV) study revealed that complex 1 undergoes five electron reductions under an applied electric potential. When the electroactive complex 1 was employed as a cathode in a membrane-less one-compartment H2O2 fuel cell, with Ni foam as the corresponding anode, the designed fuel cell exhibited an exceptionally high peak power density (PPD) of 2.41 mW cm−2, in comparison with those of all the previously reported Fe-based molecular complexes. DFT studies were performed to gain reasonable insights into the two-electron catalytic reduction (pathway I) of H2O2 by the Fe-center of complex 1 and to explore the geometries, energetics of the electrocatalyst, reactive intermediates and transition states. [ABSTRACT FROM AUTHOR]

The current work describes the removal efficiency of a hazardous azo dye such as Eriochrome Black T from aqueous solution using Sardina fish scales as an inexpensive biosorbent which the characterisation results indicate the presence of hydroxyapatite and collagen fibres. Various parameters that can influence the uptake, like contact time, pH, biosorbent dose were investigated, and the optimal experimental removal efficiency was found at acidic pH. The adsorption behaviour of EBT dye on both collagen and hydroxyapatite (HDA) was highlighted using Metropolis Monte Carlo (MC), radial distribution function (RDF), the density functional theory (DFT), and the electrostatic potential surface (ESP) calculations. The findings result in evidence that the EBT dye presents more capabilityto be adsorbed on the collagen than on the HDA surface mainly in an acidic medium. A good agreement between experimental and theoretical conclusions is obtained. The results illustrated that the experimental data were well followed by the pseudo-second-order kinetic and Freundlich isotherm models. Thermodynamic parameters were determined and show that the biosorption of dye was endothermic. [ABSTRACT FROM AUTHOR]

With an aim to improve the overall physical stability of high-performing 3,5-dinitro-functionalised bispyrazolymethanes, a hydroxyl functionality was introduced at the fourth position to obtain 1,1′-methylenebis(3,5-dinitro-1H-pyrazol-4-ol) and its energetic salts. Superior oxygen balance and energy in comparison to the amino substituent at the 4th position and enhanced sensitivity with respect to the nitro and azido substituents helped in unlocking the potential of less explored N-alkylated-4-hydroxy-3,5-dinitropyrazoles. Fine-tuning of properties via dicationic salt formation, which is not feasible in any other reported symmetrically connected pyrazole-based energetic materials, resulted in improved physical and thermal stabilities, as well as energetic performance. Hirshfeld surface analysis, electrostatic potential analysis, the study of aromaticity and weakest Mayer-bond order analysis helped further in studying the structure–property relationship of the synthesized compounds with respect to different reported methylene-bridged symmetrical compounds. [ABSTRACT FROM AUTHOR]

The use of sulfur hexafluoride (SF6) as an electrical insulator and arc‐quenching gas in high‐voltage equipment raises serious environmental concerns. The search of a replacement gas for SF6 is hindered by a priori assessment on its interruption performance. The routine fluid or mathematic magneto‐hydrodynamic models for arc burning and extinguishing are too complex to be practical for virtual screening. Herein a state‐of‐the‐art quantum chemical model to predict the interruption capability of the dielectric gases straightforwardly has been established in terms of the rate of rise of the recovery voltage (RRRV). On the basis of the molecular electrostatic potentials, five sets of descriptors, including the global statistical parameters vσ2 and Π, the site‐specific parameter ΔVs, the total positive surface area As+, augmented with the product of polarizability and dipole moment αμ, were optimized to reveal the inherent mechanisms for interruption and thus a viable structure–activity relationship mode for RRRV has been developed with the correlation coefficient 0.975. Theoretical RRRV relative to SF6 = 100 for all the known dielectric gases are in good agreement with the experimental data by a mean absolute deviation of 3.6. Accordingly, the perfluorinated cycloalkenes and alkynes, in particular, 1,3,3,3‐tetrafluoropropyne, are found to be the promising candidates as the replacement dielectric gases for SF6. [ABSTRACT FROM AUTHOR]

The effect of positioning of the In0.8Ga0.2As quantum dots (QDs) array in the i-region of the solar cell (SC) on its photogenerated current and dark saturation currents, which determine the device operating voltage, have been investigated. It was found out that the indicated photoelectric characteristics depend on the location of the QD array relative to the electric field of the p–n junction. The displacement of the QD array to the boundary of the weakly doped base leads to a decrease in the photogenerated current. But at the same time, the voltage drop effect, which is well-known for nanoheterostructural SC, is minimal. [ABSTRACT FROM AUTHOR]