Field Of Electric Dipole Research Articles

Radiative Recombination Plasma Rate Coefficients for Multiply Charged Ions

Radiative recombination (RR) plasma rate coefficients are often applied to estimate electron densities and temperatures under quite different plasma conditions. Despite their frequent use, however, these rate coefficients are available only for selected (few-electron) ions and isoelectronic sequences, mainly because of the computational efforts required. To overcome this limitation, we report here a (relativistic) cascade model which helps compute fine-structure and shell-resolved as well as total RR plasma rate coefficients for many, if not most, elements of the periodic table. This model is based on Jac, the Jena Atomic Calculator, and supports studies on how the electron is captured in selected levels of the recombined ion, a relativistic (Maxwellian) electron distribution, or how the multipoles beyond the electric-dipole field in the electron-photon interaction affect the RR rate coefficients and, hence, the ionization and recombination dynamics of hot plasma. As a demonstration of this model, we compute, compare, and discuss different RR plasma rate coefficients for initially helium-like ions, with an emphasis especially on Fe24+ ions.

Broadband Magnetoelectric Dipole Filtering Antenna for 5G Application

A magnetoelectric (ME) dipole filtering antenna with high out-of-band suppression level and high selectivity is proposed in this letter. The intrinsic radiation null of the traditional ME dipole antenna is used, which produces a good filtering response at the edge of the lower passsband. A pair of vertical parasitic metal planes are introduced between the shorted walls and fed through slot coupling, which can be equivalent to an additional magnetic dipole. The radiated electric field of the magnetic dipole is opposite to that of the original antenna at higher frequency, forming a wide stopband radiation null, which greatly improves the high-frequency stopband suppression level of the antenna. Furthermore, a pair of T-shaped coupling stubs are inserted between the shorted wall and electric dipole, producing another radiation null with high roll-off rate at higher frequency. The measurement results show that the −10 dB impedance bandwidth of the proposed antenna is 49.4% (3.2–5.3 GHz). Its low-frequency stopband suppression level is greater than 16.6 dB and high-frequency stopband suppression level is greater than 26.0 dB. Moreover, the antenna radiation pattern is stable and symmetrical in the whole operating passband, and the filtering response is desirable.

Numerical Studies of the Impact of Electromagnetic Field of Radiation on Valine.

We present the results of numerical calculations of the effect of an electromagnetic field of radiation on valine, and compare them to experimental results available in the literature. We specifically focus on the effects of a magnetic field of radiation, by introducing modified basis sets, which incorporate correction coefficients to the s-, p- or only the p-orbitals, following the method of anisotropic Gaussian-type orbitals. By comparing the bond length, angle, dihedral angles, and condense-to-atom-all electrons, obtained without and with the inclusion of dipole electric and magnetic fields, we concluded that, while the charge redistribution occurs due to the electric field influence, the changes in the dipole momentum projection onto the y- and z- axes are caused by the magnetic field. At the same time, the values of the dihedral angles could vary by up to 4 degrees, due to the magnetic field effects. We further show that taking into account the magnetic field in the fragmentation processes provides better fitting of the experimentally obtained spectra: thus, numerical calculations which include magnetic field effects can serve as a tool for better predictions, as well as for analysis of the experimental outcomes.

Dynamics and conformational heterogeneity of the PIM1 G-quadruplex from polarizable molecular dynamics simulations.

Reproductive cancers, such as triple-negative breast cancer (TNBC), are often challenging to treat due to a lack of specific chemotherapeutic targets. Overproduction of PIM1, an anti-apoptotic protein, is common in TNBC. Thus, counteracting this overproduction could serve as a viable therapeutic strategy against TNBC. The promoter region of the PIM1 gene can adopt two G-quadruplexes (GQs) with distinct topologies. GQs are higher-order, noncanonical nucleic acid structures that are rich in guanine and have become intensely explored as potential novel drug targets due to their proposed involvement in transcriptional regulation and other critical cellular processes. Two GQ-duplex hybrid structures have been found to exist in equilibrium in the promoter region of PIM1. The dominant GQ structure, form 1, contains conventional guanine tetrads and a duplex loop region of three Watson-Crick base pairs, while form 2 adopts a fold containing a mixed guanine-cytosine (GCGC) tetrad via slippage of two canonical Watson-Crick base pairs, and also contains a duplex loop consisting of two additional Watson-Crick pairs. We performed unbiased simulations and Gaussian-accelerated molecular dynamics simulations of both GQs with the Drude-2017 polarizable force field to better understand the properties of these GQs and how they might interconvert. Given the role of ion binding and noncanonical base pairing in stabilizing GQ structures, we monitored ion coordination and electronic properties (base dipole moments and electric fields). We observed an increased dipole moment for cytosine bases in the GCGC mixed tetrad of form 2, suggesting electronic plasticity as a factor in structural rearrangement between forms 1 and 2. We also report on conformational sampling in each structure to provide atomistic details that will be essential in the future design of more specific chemotherapeutic agents that target PIM1 on the nucleic acid level.

Nonlocal effects investigation via the coupling between localized and acoustic plasmons.

A scheme to investigate nonlocal effects in metal using the coupling between localized graphene plasmons (GPs) and acoustic plasmons (APs) is proposed. Because of the extremely strong field confinement property, the APs on a configuration consisting of monolayer graphene and a metal film have different dispersions when the nonlocal response is considered or not. A graphene nanoribbon array can efficiently couple incident light to the localized GPs on the ribbons and subsequently the APs. The strong coupling between the two kinds of plasmon, equivalent to electric field dipole interaction, is highly related to the acoustic plasmonic dispersion and induces different absorption spectra, depending on the dispersion. Using a very simple model, nonlocal effects can be extracted from the spectra. The investigation provides a promising platform to manipulate nanophotonics and study nonlocal effects.

Polarization Controlled Assembly of Ultrathin Thiorphan Nanostructures on ZnO Surface Facets

Despite the importance of thiorphan as a small molecule with vital biological roles, its interactions with zinc oxide (ZnO) nanomaterials that are prospective in drug delivery and theranostic applications have not yet been sufficiently explored. Here the impact of surface polarity of different ZnO facets on thiorphan adsorption is studied both experimentally by atomic force microscopy (AFM) and angle resolved X-ray photoelectron spectroscopy (XPS) and theoretically by force field molecular dynamics (FFMD) and density functional tight binding simulations (DFTB). Polar ZnO surfaces cause the formation of thiorphan nanodots, where the size of the nanodots depends on the direction of dipoles: small (4 nm) nanodots are formed on Zn-face ZnO, while large (25 nm) nanodots are formed on O-face ZnO. Nonpolar ZnO surfaces cause self-assembly into layered nanoislands with characteristic 4 nm layer thickness, which subsequently merge into rigid nanolayers. The self-assembly is shown to be controlled solely by the effect of surface dipole electric field orientation and magnitude, whereas effects of surface chemistry or solution are negligible. The results thus also show a way for controlling the assembly of thiorphan and other molecular nanomaterials for diverse applications.

Method for Detecting Electrical Interface in Sea Area Based on Active Electric Field

To obtain the direction and distance of the electrical interface in the sea, the active electric field of the electric dipole and two three-component electric field intensity sensors are used to detect them. First, the structure design of the active electric field detection device is given, and then a method for active electric field detection of the electrical interface in the sea area is proposed, that is, the effect of the electrical interface on the active electric field is equivalent to the effect of the mirror electric dipole, locating the position of the mirror dipole can be done by measuring the change of the field strength, and then the interface parameters can be determined according to the symmetrical relationship between the position of the mirror dipole and the source dipole. Both simulation analysis and laboratory test results show that the interface detection method is feasible. The related research provides new ideas for target detection in the sea.

Metal-free carbon semi-tubes for oxygen reduction electrocatalysis

New carbon morphologies are desirable in the development of high-performance carbon-based electrocatalysts for cathodic oxygen reduction reaction (ORR) of polymer electrolyte membrane fuel cells. In this work, a carbon semi-tube (CST) is successfully constructed by polymerizing m-phenylenediamine (mPDA) using surfactant-assembled micelles as a soft template. After pyrolysis, the CST morphology is retained in the formed N-doped CST (N-CST) catalyst. This mPDA-induced catalyst can provide rich micropores, high N-content, and good conductivity, imbuing it with superior catalytic ORR activity, stability, and methanol tolerance to the commercial Pt/C catalyst. By using such a metal-free N-CST as a cathode catalyst, an alkaline polymer electrolyte fuel cell exhibits a maximum power density of about 200 mW cm−2. Furthermore, density functional theory (DFT) calculations suggest that high curvature can be greatly conducive to the excellent catalytic ORR activity by the induced strong OOH∗ adsorption on active sites through a strong dipole-electric field interaction.

Electrostatic Insect Repulsion, Capture, and Arc-Discharge Techniques for Physical Pest Management in Greenhouses

This article reviews the development of electrostatic apparatuses for controlling insect pests in greenhouses. The apparatuses control insects by repelling them, capturing them, and killing them by producing an arc discharge. The single-charged dipolar electric field screen (SD screen) repels insects due to insects’ inherent avoidance behavior toward entering the electric field produced. As this behavior is common to many insect pests, the SD screen effectively prevents many pests from entering a greenhouse. The double-charged dipolar electric field screen (DD screen) has a strong attractive force that captures insects entering its electric field. The DD screen is useful for capturing small insects that pass through a conventional insect net, and unique derivatives of this screen have been invented to trap various insect pests on-site in a greenhouse. An arc-discharge exposer was used as a soil cover to kill adult houseflies that emerged from underground pupae transferred along with cattle manure used for soil fertilization. The houseflies were subjected to arc discharge when they appeared at the soil surface. These apparatuses have the common characteristic of a simple structure, so ordinary workers can be encouraged to fabricate or modify them based on their own needs. This review provides an experimental basis for designing efficient physical measures for controlling insect pests in greenhouses.

Theoretical study on the electronic properties of different types of the donor:acceptor complexes

Non-fullerene organic solar cells can be classified into four forms in line with the different types of donor (D) and acceptor (A) in the active layer: all-polymer (PD:PA), polymer D:small-molecule A (PD:MA), small-molecule D:polymer A (MD:PA), and all-small-molecule (MD:MA). On the basis of having studied the electronic properties of a large number of related monomer molecules and D:A complexes, this work constructed four groups of D:A molecular pairs as described above as examples to investigate their electronic properties with first-principles density functional theory. The results show that the absolute value of the average binding energy of the PD:PA complex D18:P(NDI2HD-T) is larger than others, indicating the structure is relatively more stable. In accordance of the Bader charge analysis, the intra-molecular charge transfer of small-molecule is greater than polymers. For these blends, the intermolecular charge transfer of the all-polymer pair D18:P(NDI2HD-T) is larger, revealing that the PD:PA pair may result in a stronger intermolecular dipole electric field, which is beneficial to facilitate the separation of excitons. In addition, the MD:MA pair DRTB-T:FDICTF-2Cl and the PD:MA complex D18:FDICTF-2Cl all exhibit a larger amount of intra-molecular charge transfer, which indicates that the small-molecule acceptors in D:A complexes are conducive to promoting intra-molecular charge transfer.

Modification of Schottky barrier height for NiFe/p-Si contacts by inserting an ultra-thin HfO2 dielectric layer

The effects of HfO2 dielectric thickness (tHfO2) on the electrical properties of NiFe/HfO2/p-Si contacts were explored, and the microstructure and interfacial products of the contacts were analyzed. The results showed that Hf-O-Si bonds probably form at HfO2/p-Si interface and produce interface dipoles, and the number of the dipoles is positively linked to tHfO2. As tHfO2 grows from 0.5 to 1.5 nm, the enhanced dipole electric field will let the surface electric field of p-Si strengthen and the surface band of p-Si bend downwards, thus causing a rise in Schottky barrier height of the contacts and a dip in electric current.

Bias dependent dipolar electric field at self-assembled monolayer (SAM)/organic interface determines the hole drift mobility

The room-temperature current-voltage data of hole transport in ITO/PFB(400 nm)/Al organic diode (Khodabakhsh et al., 2004) where PFB is polyfluorene copolymer, and the related 5 devices of different self-assembled monolayer (SAM) with permanent molecular dipole moments chemisorbed onto the indium-tin-oxide (ITO) electrode are investigated. It is shown that the intrinsic hole mobility, μmax, within the diode is Ea independent but it is strongly dependent on the magnitude and the orientation of the SAM´s permanent molecular dipole moments. The current-density data jointly with the reported values of 4 SAM’s molecular dipole moments and their orientation with respect to the ITO normal at the contact enable to provide an estimate of the PEDOT:PSS, as well as pristine ITOP/PFB molecular dipole moments and their orientations. The dipolar electric field that is induced at the ITO/SAM/PFB interface, Eint, turns out to be a linear function of the applied field Ea of approximately SAM`s independent slope. The current-density induced dipolar electric field occurs even at the pristine ITO/PFB interface. The intrinsic hole mobility, μmax, multiplied by the given algebraic function of the Ea dependent interfacial electric field, Eint, combine into the Ea dependent hole drift mobility, μd, Influenced jointly by the dipolar and interfacial effects, it is the parameter that is amenable in the current-density-voltage measurements. The relevance of the stated findings to the current switching mechanism in the self-assembled supramolecular ferroelectric organic semiconductor diode is also briefly discussed.

Nonmonotonous temperature fluctuations of the orbital moment and spin-orbit coupling in multiferroic gallium ferrite thin films

Temperature dependent x-ray absorption spectroscopy and x-ray magnetic circular dichroism experiments were performed at the Fe ${L}_{2,3}$ edges to unveil the magnetic orbital moment and spin-orbit coupling (SOC) behavior in thin films of the multiferroic ${\mathrm{Ga}}_{0.6}{\mathrm{Fe}}_{1.4}{\mathrm{O}}_{3}$ (GFO) compound. A thorough analysis of the data evidenced a nonmonotonous behavior for both magnetic orbital moment and SOC with a minimum at approximately 120 K, accompanied with indications of disturbances of the magnetic exchange and electric field dipole. Resonant photoemission spectroscopy experiments performed at the Fe ${L}_{2,3}$ edges rendered an important modification of the crystal field configuration around this temperature value, pointing to a temperature-driven structural trigonal distortion. These instabilities can be compared to those observed in other iron oxides, in particular, during transitions such as the Verwey transition, with the difference that on GFO they do not have any impact on the macroscopic magnetic properties, such as the coercive field and the global magnetization. This work demonstrates that the absence of instabilities in magnetism at the macroscopic scale does not guarantee the absence of fluctuations at the atomic scale. Such atomic-scale fluctuations of the SOC are undoubtedly shown here and have an impact on the spin Hall magnetoresistance response of the films. This point is of importance for prospective applications of GFO in spin-orbitronics.

Flexible Liquid‐Based Continuous Direct‐Current Tribovoltaic Generators Enable Self‐Powered Multi‐Modal Sensing

AbstractFlexible tribovoltaic direct‐current (DC) generators are urgently expected by wearable applications. Traditional rigid contact‐separation type tribovoltaic DC generators normally have non‐ignorable friction loss and cannot sustain outstanding outputs. This hinders their serviceability in continuous motion scenarios. Here, flexible liquid‐based DC generators (FLGs) with metal‐liquid‐semiconductor indium gallium zinc oxide (IGZO) stack structures are reported. The FLG with Pt/H2O/IGZO structure delivers a peak short‐circuit current density up to 2.3 µA cm−2, a peak open‐circuit voltage up to 620 mV, and a power density up to 0.1 µW cm−2. The differences in the properties of different liquid–solid interfaces are studied by density functional theory, showing that the bond formation, charge‐transfer‐induced dipole electric field at the solid‐liquid interface, and the built‐in electric field are responsible for the generation and separation of electron‐hole pairs to form continuous DC. The proposed FLG can keep excellent performance even after >5 × 104 shaking cycles or exposing to ambient conditions for 30 days, showing extraordinary stability. Besides charging capacitors or driving LEDs, the FLG is further demonstrated to work for self‐powered multifunctional sensing, enabling pressure, position‐posture, or temperature detections. This design offers potential solutions and novel possibilities for next‐generation self‐powered wearable electronics.

Electrostatic Spore-Trapping Techniques for Managing Airborne Conidia Dispersed by the Powdery Mildew Pathogen

This review examines the progress of electrostatic spore-trapping research and the potential for the practical application of electrostatic apparatuses in powdery mildew control. These apparatuses produce an electric field by charging an insulated conductor wire (ICW). Airborne pathogen spores are subjected to an attractive force in the electric field and are drawn to the charged ICW as a result of dielectrophoretic movement. The strength of the attractive force is commensurate with the field strength (determined by the magnitude of the voltage applied to the ICW). Single-charged monopolar electric field screens (SM screens) are constructed by arraying negatively charged cylindrical ICWs in parallel at a specific interval. The connected electric fields of these ICWs form a gap-free air-shielding barrier. Wind-dispersed spores are precipitated by this barrier to create spore-free air. Oppositely charged SM screens have been combined to develop double-charged dipolar electric field screens, which generate a stronger spore attraction force under lower voltage application. Thus, electric field screens represent a promising physical method for creating spore-free spaces in cropping facilities, where plants can be cultivated without risk of infection by airborne fungal pathogens.

Biharmonic (ω, 2ω) ionization of atoms by elliptically-polarized light. Carving the photoelectron angular distributions

The biharmonic (ω, 2ω) photoionization of atomic inner-shell electrons opens up new perspectives for studying nonlinear light–atom interactions at intensities in the transition regime from weak to strong-field physics. In particular, the control of the frequency and polarization of biharmonic beams enables one to carve the photoelectron angular distribution and to enhance the resolution of ionization measurements by the (simultaneous) absorption of photons. Apart from its quite obvious polarization dependence, the photoelectron angular distributions are sensitive also to the (relative) intensity, the phase difference and the temporal structure of the incoming beam components, both at resonant and nonresonant frequencies. Here, we describe and analyze several characteristic features of biharmonic ionization in the framework of second-order perturbation theory and (so-called) ionization pathways, as they are readily derived from the interaction of inner-shell electrons with the electric-dipole field of the incident beam. We show how the photoelectron angular distribution and elliptical dichroism can be shaped in rather an unprecedented way by just tuning the properties of the biharmonic field. Since such fields are nowadays accessible from high-harmonic sources or free-electron lasers, these and further investigations might help extract photoionization amplitudes or the phase difference of incoming beams.

Unattended Trapping of Whiteflies Driven out of Tomato Plants onto a Yellow-Colored Double-Charged Dipolar Electric Field Screen

An unattended pest control system was developed to eliminate whiteflies (Bemisia tabaci) that settled on greenhouse tomato plants. The system exploited the whitefly’s habit of flying up from a plant that was mechanically tapped and then heading toward yellow objects. Remote-controlled dollies with arms that tapped plants and yellow-colored double-charged dipolar electric field screens (YDD-EFSs) (oppositely electrified transparent insulator tubes filled with yellow-colored water) attracted and trapped the whiteflies. The whiteflies flew up when the plants were mechanically tapped with the dolly’s arms during reciprocating movements and were subsequently trapped by YDD-EFSs that were automatically translocated to the target plants. The system was applied to rows of whitefly-infested tomato plants. Almost all whiteflies transferred to plants were successfully recovered by two dollies moving on either side of the plants, approaching all plants individually (via programmed movement). In summary, we present an efficient unattended method for controlling whiteflies on tomato plants in greenhouses.

Internal Electric Field-Induced Formation of Exotic Linear Acetonitrile Chains.

The application of external electric and magnetic fields is a powerful tool for aligning molecules in a controlled way, if the thermal fluctuations are small. Here we demonstrate that the same holds for internal electric fields in a molecular cluster. The electric field of a single molecular dipole, HCl, is used to manipulate the aggregation mechanism of subsequently added acetonitrile molecules. As a result, we could form exotic linear acetonitrile (CH3CN) chains at 0.37 K, as confirmed by infrared spectroscopy in superfluid helium nanodroplets. These linear chains are not observed in the absence of HCl and can be observed only when the internal electric field created by an HCl molecule is present. The accompanying simulations provide mechanistic insights into steric control, explain the selectivity of the process, and show that non-additive electronic polarization effects systematically enhance the dipole moment of these linear chains. Thus, adding more CH3CN monomers even supports further quasi-linear chain growth.

Electric-Field-Based Guidance for Percutaneous Catheter Vessel Crossing.

Percutaneous procedures to divert blood flow from one blood vessel to another can be performed with intravascular catheters but demand a method to align a crossing needle from one vessel to another. Fluoroscopic imaging alone is not adequate, and it is preferable to have a sensor on one catheter that detects the correct alignment of an incoming needle. This can be implemented by generating dipole electric fields from the crossing catheter which are detected by a receiving catheter in the target vessel and, thus, can calculate and display the degree of alignment, permitting the operator to rotate the crossing catheter to guarantee alignment when deploying a crossing needle. Catheters were built using this concept and evaluated in vitro. The results show that accurate alignment is achieved, and a successful crossing can be made. The concept is being further developed for further clinical evaluation.

Deep Learning-Assisted Investigation of Electric Field-Dipole Effects on Catalytic Ammonia Synthesis.

External electric fields can modify binding energies of reactive surface species and enhance catalytic performance of heterogeneously catalyzed reactions. In this work, we used density functional theory (DFT) calculations-assisted and accelerated by a deep learning algorithm-to investigate the extent to which ruthenium-catalyzed ammonia synthesis would benefit from application of such external electric fields. This strategy allows us to determine which electronic properties control a molecule's degree of interaction with external electric fields. Our results show that (1) field-dependent adsorption/reaction energies are closely correlated to the dipole moments of intermediates over the surface, (2) a positive field promotes ammonia synthesis by lowering the overall energetics and decreasing the activation barriers of the potential rate-limiting steps (e.g., NH2 hydrogenation) over Ru, (3) a positive field (>0.6 V/Å) favors the reaction mechanism by avoiding kinetically unfavorable N≡N bond dissociation over Ru(1013), and (4) local adsorption environments (i.e., dipole moments of the intermediates in the gas phase, surface defects, and surface coverage of intermediates) influence the resulting surface adsorbates' dipole moments and further modify field-dependent reaction energetics. The deep learning algorithm developed here accelerates field-dependent energy predictions with acceptable accuracies by five orders of magnitudes compared to DFT alone and has the capacity of transferability, which can predict field-dependent energetics of other catalytic surfaces with high-quality performance using little training data.