Search

The alpha rhythm in human electroencephalography (EEG) is known to decrease in frequency with age. Previous study has shown that elderly individuals with dementia exhibit higher S values (spatial variability) and SD values (temporal variability) in the triple correlation of the occipital region (P3, P4, Oz) compared to healthy elderly individuals. The objective of this research is to examine changes in S and SD values of the alpha band with aging in healthy individuals using triple correlation values from the frontal region. The subjects were 50 healthy elderly subjects (mean age 73.0 ± 5.1 years), 34 healthy younger subjects (mean age 28.1 ± 4.6 years), and 21 dementia patients (mean age 70.1 ± 9.1 years). The methodology involved recording EEG for 5 min during rest with closed eyes, and then calculating S and SD values of the alpha band (8-13 Hz) using three electrodes in the frontal region (F3, F4, Fpz). The findings indicated that the S values of young individuals were significantly higher than those of elderly individuals (p < 0.01), whereas the SD values of young individuals tended to be lower than those of elderly individuals. The elevated S values in young individuals imply greater spatial variability akin to individuals with dementia, whereas the reduced SD values in young individuals suggest lower temporal variability unlike individuals with dementia. The discrepancy between the S value and SD value in healthy young individuals suggests that the normal cortical dipole in the frontal regions might be more abundant in them compared to healthy elderly individuals. [ABSTRACT FROM AUTHOR]

Nowadays, liquid cooling channels are used for cooling of electronic equipment. These channels have to change the cross-section to pass over elements, so they undergo sudden contractions or expansions. These changes create areas that are unfavorable for heat transfer. Various methods have been proposed to improve heat transfer in these areas. In the present study, the possibility of using a non-uniform magnetic field to improve heat transfer in a millichannel including two sudden contractions has been discussed. In this study, it is assumed that a ferrofluid (EMG-805-a commercial brand) flows in the channel with a laminar regime, fully developed and steady state conditions. The walls of the channel are adiabatic, while the walls of the steps, which are in the vicinity of the electronic element, have a constant heat flux. The effects of different parameters, including locations of dipoles on the bottom and top walls, the number of dipoles, the Reynolds number, and the strenth of the magnetic field on the improvement of heat transfer have been investigated. The obtained results show that the increase in Reynolds number and the strenth of the magnetic field causes an increase in local Nusselt. The results show that applying a magnetic dipole on the bottom wall and just after the steps results in a significant increase in the local Nusselt number and an increase of 164.05% in the average Nusselt number compared to the case without a magnetic field. [ABSTRACT FROM AUTHOR]

The problem of submerged body motion in a frozen channel is considered. The fluid in the channel is assumed to be inviscid and incompressible. Fluid flow is the potential. The ice cover has non-uniform compression along the principal coordinates. The damping of hydroelastic waves generated by the motion of submerged body is modeled by taking into account porosity of ice. The submerged body is modeled as a dipole, the potential of which is determined using mirror images from the channel walls. The main problem of the submerged body motion at constant speed along the central line of the channel is considered. Two subproblems are addressed: comparison of damping effects of the porosity and viscosity of ice and investigation of effects of symmetrically variable ice thickness relative to the central line of the channel. It was found that the most important compressive stress is the stress in the direction of the motion of the submerged body. The speed of the body, which was subcritical for uncompressed ice, may become critical or supercritical. Compressive stresses perpendicular to the direction of motion do not qualitatively change the character of the ice response. These stresses, in combination with compressive stresses along the direction of motion, strengthen the effect of the latter, making the transition from subcritical to supercritical regime faster. [ABSTRACT FROM AUTHOR]

The ternary copolymerization strategy has emerged as a promising strategy for developing high‐efficiency donor polymers in polymer solar cells (PSCs). Terpolymers based on the star polymer PM6 have already realized good photovoltaic performance. However, challenges such as the intricate synthesis of fluorine‐substituted benzodithiophene (F‐BDT) unit of PM6 and entropy increase induced by backbone disorder have hindered the construction of high‐performance donor terpolymers. In this work, these challenges are addressed by opting for the cost‐effective chlorinated‐substituted benzodithiophene unit (Cl‐BDT) as an alternative to F‐BDT and incorporating the large dipole moment and electron‐deficient TPD group as the third component into the high‐performance donor polymer of PM7. As expected, this approach effectively suppresses terpolymer backbone disorder while enhancing crystallinity, thereby optimizing morphology and improving charge generation and transport. Remarkably, the PM7‐TPD‐10‐based device with 10% TPD replacement achieves a champion power conversion efficiency (PCE) of 18.26%. After introducing PM7‐TPD‐10 as the third component into D18:L8‐BO blend, a dual mechanism for improving the efficiency to 19.40% is realized. This work demonstrates that the high dipole moiety as the third component to construct terpolymers is an important strategy to suppress the backbone disorder and increase the crystallinity, facilitating the optimization of morphology and device performance. [ABSTRACT FROM AUTHOR]

Previously synthesized six selected Pyridinium‐Benzimidazolate based zwitterions were investigated in this contribution. Of the selected molecules, two are TICT, two are PICT (twisted and planar intramolecular charge transfer types respectively), and the other two are PICT+TICT types. Generally, TICT vs PICT is the most widely used strategy for chromophore design by earlier researchers. In this work, impacts of PICT+TICT effects (two effects combined in one chromophore), through p‐phenylene bridges, on various fundamental properties like, dipole moments, polarizabilities, hyperpolarizabilities, adiabatic excitations were analyzed. Nonlinear optical (NLO) responses of the six molecules indicate that PICT more efficient than TICT (6‐11‐times enhanced β), and PICT+TICT more efficient than both PICT (~4 times enhanced β) and TICT (20–40 times enhanced β). Current work also shows the role of aromatic p‐phenylene bridge as an efficient communicator between the donor and acceptor, in enhancing the NLO and other response properties. This work suggests that inducing bridge aromatic control to a TICT chromophore (making it to exhibit an amalgamation of PICT and TICT effects) is an effective and efficient strategy in the designing of molecular nonlinear optical chromophores, over either PICT or TICT only. [ABSTRACT FROM AUTHOR]

Interfacial engineering of perovskite films has been the main strategies in improving the efficiency and stability of perovskite solar cells (PSCs). In this study, three new donor‐acceptor (D–A)‐type interfacial dipole (DAID) molecules with hole‐transporting and different anchoring units are designed and employed in PSCs. The formation of interface dipoles by the DAID molecules on the perovskite film can efficiently modulate the energy level alignment, improve charge extraction, and reduce non‐radiative recombination. Among the three DAID molecules, TPA‐BAM with amide group exhibits the best chemical and optoelectrical properties, achieving a champion PCE of 25.29 % with the enhanced open‐circuit voltage of 1.174 V and fill factor of 84.34 %, due to the reduced defect density and improved interfacial hole extraction. Meanwhile, the operational stability of the unencapsulated device has been significantly improved. Our study provides a prospect for rationalized screening of interfacial dipole materials for efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Poly-(vinylidene fluoride) (PVDF) is widely used as a ferroelectric polymer due to its good flexibility and stability. However, its ferroelectricity requires enhancement through doping or modification processes, and the necessity for prepoling significantly limits its applications. In the present work, we propose an interfacial ion-dipole induction method for preparing high-ferroelectric PVDF films using oppositely charged single-chain Janus nanoparticles (OC-SJNPs). The SJNPs possess a positive end with quaternized amino groups that allow for uniform electrodeposition on the substrate surface. After hydrolysis, due to the nanoscale size, proton transfer occurs between carboxyl and amino groups, thus promoting the degree of ionization and the charge density of both ends. The negatively charged (−45 mV) end of OC-SJNPs exhibits strong dipole interaction with PVDF chains, leading to a high β-phase content of 90.8%, with a residual polarization strength of 10.6 μC/cm2, nearing the theoretical maximum of pure PVDF films. Additionally, the orientation of OC-SJNPs induces the alignment of PVDF dipoles, thus achieving high piezoelectric energy generation without prepoling. Another polar polymer, polyacrylonitrile (PAN) also demonstrated higher piezoelectric energy generation by using the proposed method. It not only successfully prepared high-ferroelectric and poling-free PVDF films as piezoelectric energy generators but also offers a universal and efficient approach for the preparation of polar polymer materials. [ABSTRACT FROM AUTHOR]

The optical topology, which serves as a stable spatial electromagnetic structure, offers a new dimension for applications in the field of optical information processing, transmission, and storage. In recent years, there has been an increasing focus on these spatially structured light fields. By reversing the radiation of orthogonal dipole pairs, we propose an approach to generate Meron topologies within the focused light field while also investigating the evolution of the Meron structure along the longitudinal axis. Through introducing a dipole placed along the z -axis, we achieve precise positioning and fine adjustment of the topological center. The stability of Meron under a high numerical aperture objective lens (NA = 0.95) can be effectively demonstrated. [ABSTRACT FROM AUTHOR]

A test facility dipole is being developed at LBNL, targeting a 16 T field in a 144 mm wide aperture. The magnet uses a block design, with two double-pancake coils. In order to minimize motion under the large Lorentz forces, the coils are preloaded against a thick aluminum shell and iron yoke using bladder and key technology. It is then crucial to verify that the performance of the magnet is not degraded due to strain induced on the Nb3Sn conductor during assembly, cool-down and powering. The critical current of extracted strands was measured in a varying background magnetic field and as a function of the applied longitudinal strain. Finite element analysis was used to extract the strain state inside the superconducting strands during magnet assembly and operation. This strain was then compared to the measurements to evaluate potential reversible and irreversible effects on the magnet performances. The results suggest that the magnet can reach 16 T with sufficient margin, with no irreversible degradation in the high field region.

This study explores the spatiotemporal variability and determinants of rainfall patterns during the March to May (MAM) season in Rwanda, incorporating an analysis of teleconnections with oceanic–atmospheric indices over the period 1983–2021. Utilizing the Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) dataset, the study employs a set of statistical tools including standardized anomalies, empirical orthogonal functions (EOF), Pearson correlation, the Mann–Kendall (MK) trend test, and Sen's slope estimator to dissect the intricacies of rainfall variability, trends, and their association with large-scale climatic drivers. The findings reveal a distinct southwest to northwest rainfall gradient across Rwanda, with the MK test signaling a decline in annual precipitation, particularly in the southwest. The analysis for the MAM season reveals a general downtrend in rainfall, attributed in part to teleconnections with the Indian Ocean Sea surface temperatures (SSTs). Notably, the leading EOF mode for MAM rainfall demonstrates a unimodal pattern, explaining a significant 51.19% of total variance, and underscoring the pivotal role of atmospheric dynamics and moisture conveyance in shaping seasonal rainfall. The spatial correlation analysis suggests a modest linkage between MAM rainfall and the Indian Ocean Dipole, indicating that negative (positive) phases are likely to result in anomalously wet (dry) conditions in Rwanda. This comprehensive assessment highlights the intricate interplay between local rainfall patterns and global climatic phenomena, offering valuable insights into the meteorological underpinnings of rainfall variability during Rwanda's critical MAM season. [ABSTRACT FROM AUTHOR]

Magnetoencephalography (MEG) is a noninvasive neuroimaging technique widely recognized for epilepsy and tumor mapping. MEG clinical reporting requires a multidisciplinary team, including expert input regarding each dipole's anatomic localization. Here, we introduce a novel tool, the "Magnetoencephalography Atlas Viewer" (MAV), which streamlines this anatomical analysis. The MAV normalizes the patient's Magnetic Resonance Imaging (MRI) to the Montreal Neurological Institute (MNI) space, reverse-normalizes MNI atlases to the native MRI, identifies MEG dipole files, and matches dipoles' coordinates to their spatial location in atlas files. It offers a user-friendly and interactive graphical user interface (GUI) for displaying individual dipoles, groups, coordinates, anatomical labels, and a tri-planar MRI view of the patient with dipole overlays. It evaluated over 273 dipoles obtained in clinical epilepsy subjects. Consensus-based ground truth was established by three neuroradiologists, with a minimum agreement threshold of two. The concordance between the ground truth and MAV labeling ranged from 79% to 84%, depending on the normalization method. Higher concordance rates were observed in subjects with minimal or no structural abnormalities on the MRI, ranging from 80% to 90%. The MAV provides a straightforward MEG dipole anatomic localization method, allowing a nonspecialist to prepopulate a report, thereby facilitating and reducing the time of clinical reporting. [ABSTRACT FROM AUTHOR]

The water (H2O) dissociation is critical for various H2O‐associated reactions, including water gas shift, hydrogen evolution reaction and hydrolysis corrosion. While the d‐band center concept offers a catalyst design guideline for H2O activation, it cannot be applied to intermetallic or main group elements‐based systems because Coulomb interaction was not considered. Herein, using hydrolysis corrosion of Mg as an example, we illustrate the critical role of the dipole of the intermetallic catalysts for H2O dissociation. The H2O dissociation kinetics can be enhanced using MgxMey (Me=Co, Ni, Cu, Si and Al) as catalysts, and the hydrogen generation rate of Mg2Ni‐loaded Mg reached 80 times as high as Ni‐loaded Mg. The adsorbed H2O molecules strongly couple with the Mg−Me dipole of MgxMey, lowering the H2O dissociation barrier. The dipole‐based H2O dissociation mechanism is applicable to non‐transition metal‐based systems, such as Mg2Si and Mg17Al12, offering a flexible catalyst design strategy for controllable H2O dissociation. [ABSTRACT FROM AUTHOR]

In this paper, a compact unidirectional antenna consisting of a planar electric dipole and a shortened connecting element is introduced. This antenna is excited by a Γ-shaped feeding line. A wide impedance bandwidth in the frequency range of 1.3–3.3 GHz is observed in the output performance. Sufficient main lobe and low level back lobe have been introduced as other characteristics of the structure, based on radiation patterns. The antenna design process is evaluated step-by-step and using parametric study based on the antenna geometry. One of the main features of the desired antenna is the realization of circular polarization in a high percentage of the operational bandwidth 1.5–3.3 GHz. The radiation patterns of the orthogonal planes E-field and H-field along with the left-handed and right-handed circular polarization patterns for the desired antenna have been extracted and analyzed. A three-dimensional structure in the form of stacked stepped disks (SSD) is introduced to increase overall performance of antenna. There is an acceptable similarity between the E-field and H-field page patterns, which shows the accuracy of the design process. On the other hand, for studying the circular polarization, left-handed and right-handed patterns based on the main beam direction and orthogonal polarization level have acceptable performance. The maximum overall gain of the antenna in the designed frequency band is near to 13 dB. [ABSTRACT FROM AUTHOR]

This paper introduces a new and compact structure of a directional antenna consisting of an electric dipole and a truncated connection element. This antenna is fed by a Γ shaped power line. Wide impedance bandwidth in the frequency range of 1.3 GHz to 3 GHz will be observed in the output performance of this antenna. Base radiation patterns with high main loop and low side and back loop level are other features of the introduced antenna. The antenna design process is step-by-step and parametric based on the important parameters of antenna geometry. The main feature of the antenna is the realization of circular polarization at a high percentage of implicational bandwidth. The radiation patterns of orthogonal plates E & H along with left and right circular polarization patterns for the desired antenna have been extracted and analyzed. As predicted, there are many similarities between the E and H plane pattern, which indicates the accuracy of the design process. Is. The maximum total gain of the antenna in the designed frequency band is about 10 dBi..

This article proposes a new approach to designing dipole antennas that can create circular polarization. Using a meander-shaped parasitic element in the upper part of the dipole forms a Yagi-Uda-like structure, and the cooperation between the dipole and the parasitic element leads to the production of circular polarization. The main contribution of this work is introducing a new technique for generating circular polarization using dipole antennas. This simple technique leads to a low-profile structure and has provided satisfactory results. Furthermore, by using the introduced CP antenna in a $4\times 4$ array structure and by stimulating a sequentially rotated feeding network, the impedance bandwidth of the antenna is improved, circular polarization with higher purity is achieved, and high radiation gain is achieved. Experimental results approve that the proposed array antenna has an impedance bandwidth of 1.66–3.29 GHz and covers the 1.76–3.12 GHz range with circular polarization. The overall dimension of the proposed array antenna is ( $0.78\times 0.78 \times 0.13$ ) $\lambda ^{3}$ , and a peak gain equal to 11.48 dB was reported for this work.

The total energy of the potential geomagnetic field (up to the core-mantle boundary) is divided into dipole and non-dipole parts, which are determined by their evolution and frequency properties. The calculations presented here are based on the available and sufficiently reliable COV-OBS.x2 geomagnetic field model that covers the period of 1840–2020. The proposed approximations for longer periods are preliminary, as further work is required to estimate errors through comparison with other historical observational and paleomagnetic models of the geomagnetic field, as well as with numerical models of the geodynamo. The actual dipole energy (about 5 EJ) turned out to be only three times higher than the non-dipole energy, rather than the previously reported one order or more. It was found that the dipole energy decreases relatively slowly and monotonically, while the non-dipole part changes much faster and quasi-periodically. Therefore, the characteristic times are on the order of one thousand years for the dipole component and on the order of hundreds of years for the non-dipole component, respectively. If the quadrupole and octupole contributions to the geomagnetic field are only considered, which is a natural limitation for paleoand archaeomagnetologists, then the energy of such a “truncated” non-dipole part increases monotonically, and its evolutionary and frequency characteristics become different from the full (up to the 14th spherical harmonic) non-dipole part. The results show that the power or the time derivative of energy varies more significantly compared to the energy, being on the order of one hundred MW for both the dipole and non-dipole parts. Frequency values were obtained by analyzing the power/ energy ratios.

A simple and efficient method was developed to synthesize 1,2,3-triazolo quinoxalines derivatives under click conditions. 1,3-Dipolar cycloaddition was carried out where 2-azido methyl quinoxaline and trimethyl silyl acetylene are used as dipole and dipolarophile respectively. The products were characterized by NMR and mass spectroscopic methods. [ABSTRACT FROM AUTHOR]

The present study used a simplified axisymmetric biomagnetic fluid dynamics and porous mediamodel which includes FHD (Ferrohydrodynamics), porosity and inertia effects saturated by magnetic dipole to study the influences of the leading parameters on various flow variables along a flat plate.The governing equations are simplified and solved by finite difference approach. We clarify how the ferromagnetic interaction parameter, B and porosity,ε assumptions contribute in the bio-background of the problem of interest. Moreover, from the results of the flow profiles, accelerating and decelerating phenomena are noticed for B, and ε interaction.

A wideband circularly polarized (CP) dipole antenna with compact size and wide beamwidth is proposed. To achieve a wide half‐power beamwidth (HPBW), the dipole is designed to be a folded bowtie, and four rotationally symmetric vertical metal plates are placed on the square ground plane. A circular parasitic patch above the dipole arms improves the impedance bandwidth. By using a 3‐dB coupler, the proposed antenna achieves wideband CP performance. The measured results show that an impedance bandwidth for VSWR ≤ 2 and a 3‐dB axial‐ratio (AR) bandwidth are from 0.76 to 2.1 GHz (93.7%). Moreover, a bandwidth of HPBW ≥ 102° is from 0.76 to 1.8 GHz (81.2%). [ABSTRACT FROM AUTHOR]

A miniaturized and wideband circular-polarized (CP) dipole antenna with couple-feed has been developed for 5G base-station applications. In this design, two novel L-shaped short stubs working as the couple feed are introduced to excite the orthogonal dipole with the orthogonal phase difference. Therefore, CP radiation is realized on the orthogonally arranged dipoles. In addition, a stub-loaded square-ring dipole is utilized to generate another resonant frequency at low frequency, which broaden the working bandwidth and achieve the miniaturization design. To further expand the impedance and axial ratio bandwidths, four branch lines are adopted in the center of crossed square-loops dipoles. The proposed CP antenna using couple feed was finally fabricated and tested. The simulated and measured impedance bandwidth for |S11| < −10 dB is 65.0% from 1.55 to 3.05 GHz. The measured 3 dB axial ratio bandwidth is 37.5% (1.95–2.85 GHz). The measured results prove that this CP antenna can be applied to wideband base-station applications. [ABSTRACT FROM AUTHOR]

The problem of periodic oscillations of a dipole, specifically its strength, along the principal axes in a three-dimensional frozen channel is considered. The key points of the problem are taking into account the linear thickness of ice across the channel and ice porosity within Darcy's law. The fluid in the channel is inviscid and incompressible; the flow is potential. It is expected that the oscillations of a small radius dipole well approximate the oscillations of a small radius sphere at a sufficient depth of immersion of the dipole. It was found that during oscillations along the channel and vertical oscillations, waves are generated in the channel, propagating along the channel with a frequency equal to the frequency of dipole oscillations. These waves decay far from the dipole, and the rate of decay depends on the porosity coefficient. [ABSTRACT FROM AUTHOR]

Herein, the concept of triboelectric generators using dipolar polarization energy as an electrical power source is introduced. Dipolar polarization energy is stored in dielectric films by rubbing, and is conveyed to external circuits for use during the depolarization process. Pyromellitic dianhydride‐4,4'‐oxydianiline polyimide films are used as a possible candidate for triboelectric generators, where polarization is formed by rubbing owing to the orientational alignment of polar molecular groups. The current–voltage measurements are used to evaluate the equivalent‐circuit parameters of the generator. The current source Is is 0.07 nA at 30 °C, which is enhanced to 0.13 nA at 110 °C. It is indicated in these results that the depolarization process proceeds in a short time at higher temperatures, causing an increase in the current. Consequently, the maximum power increases from 18 nW (30 °C) to 33 nW (110 °C). The enhancement of the output power at higher temperatures well supports the idea of using dipolar polarization energy as a power source of triboelectric generators. [ABSTRACT FROM AUTHOR]

In order to meet the demands of dual-band and integrated conformal antenna for UAV (Unmanned Aerial Vehicle) swarm communication systems, an integrated wing conformal antenna is designed and fabricated. The antenna is realized by combining a broadband dipole antenna and a low pass and high-pass LC combiner. The antenna element is realized by three pairs of open branch lines to achieve effective choking characteristics and broad- band omnidirectional radiation. The combiner consists of K-m LC filters, which are used to realize dual - band operation with low insertion loss and high rejection. The measured Voltage Standing Wave Ratio(VSWR) of antenna is less than 2, the measured gain is more than 0 dBi, and the isolation is better than 30 dBc between L and S frequency band. By mounting only one wing conformal antenna, a dual-band simultaneous operation can be realized which meets the need of UAV swarm data link system for high communication rate. The proposed antenna is whole arranged in the tail wing of UAV to enhance the integration capability of the UAV swarm, and can be widely used in UAV field. [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical studies of the electrical conductivity of weakly concentrated solutions of liquid dielectrics (LDs) with a chemically active impurity and associated electrohydrodynamic (EHD) flows are presented. The studies are carried out on the basis of a multi-ion model of electrical conductivity, which makes it possible to adequately describe both the dissociation–recombination interactions of ions and the electrochemical injection of ions from the electrode surface. It is shown that the recombination processes in the volume of the LD lead to a slow disappearance of the space charge with a characteristic time of hours and days, which does not allow for significantly reducing the distribution of the space charge in the LD that reduces the intensity of EHD flows. Numerical calculations based on the obtained theoretical and experimental data on the electrical conductivity were carried out, and they confirmed the results of observations concerning the development and structure of EHD flows and current characteristics. [ABSTRACT FROM AUTHOR]

The values of the surface induced charges, the positions of their centers, and the value of the equivalent dipole of an oblate conducting spheroid are determined by transition from spheroidal coordinates to a spherical system of coordinates in the analytical asymptotic calculations of the first order of smallness with respect to the squared eccentricity. The characteristics of the equivalent dipole are obtained depending on the value of the electrostatic field strength, squared eccentricity, and the radius of an equal sphere. [ABSTRACT FROM AUTHOR]

Thin films of transition metal oxides such as molybdenum oxide (MoOx) are attractive for application in silicon heterojunction solar cells for their potential to yield large short‐circuit current density. However, full control of electrical properties of thin MoOx layers must be mastered to obtain an efficient hole collector. Here, we show that the key to control the MoOx layer quality is the interface between the MoOx and the hydrogenated intrinsic amorphous silicon passivation layer underneath. By means of ab initio modelling, we demonstrate a dipole at such interface and study its minimization in terms of work function variation to enable high performance hole transport. We apply this knowledge to experimentally tailor the oxygen content in MoOx by plasma treatments (PTs). PTs act as a barrier to oxygen diffusion/reaction and result in optimal electrical properties of the MoOx hole collector. With this approach, we can thin down the MoOx thickness to 1.7 nm and demonstrate short‐circuit current density well above 40 mA/cm2 and a champion device exhibiting 23.83% conversion efficiency. [ABSTRACT FROM AUTHOR]

The problem of submerged body motion in a frozen channel is considered. The fluid in the channel is assumed to be inviscid and incompressible. Fluid flow is the potential. The ice cover has non-uniform compression along the principal coordinates. The damping of hydroelastic waves generated by the motion of submerged body is modeled by taking into account porosity of ice. The submerged body is modeled as a dipole, the potential of which is determined using mirror images from the channel walls. The main problem of the submerged body motion at constant speed along the central line of the channel is considered. Two subproblems are addressed: comparison of damping effects of the porosity and viscosity of ice and investigation of effects of symmetrically variable ice thickness relative to the central line of the channel. It was found that the most important compressive stress is the stress in the direction of the motion of the submerged body. The speed of the body, which was subcritical for uncompressed ice, may become critical or supercritical. Compressive stresses perpendicular to the direction of motion do not qualitatively change the character of the ice response. These stresses, in combination with compressive stresses along the direction of motion, strengthen the effect of the latter, making the transition from subcritical to supercritical regime faster.

This paper elaborates on the results of an exhaustive study regarding the Earth's position in the universe based on the Cosmic Microwave Background (CMB) radiation map, which is the latest discovery in modern astronomy. CMB radiation provides crucial insights into the early distribution of mass and energy in the universe. The aim of this research is to understand the theory and mechanisms behind the formation of polarity structures in the CMB and analyze their correlation with Earth's position in the overall structure of the universe. Intensity measurement data of CMB radiation published by COBE, WMAP, and Planck present temperature distribution data in coordinates in FITS (Flexible Image Transport System) format files. Subsequently, a spherical harmonic transformation is performed to obtain spherical harmonic coefficients a_lm as equations that represent dipole, quadrupole, octupole models, and various other multipole models. The analysis of the correlation in the temperature distribution of CMB radiation involves detailing various patterns found in the dipole, quadrupole, and octopole models, demonstrating quasi-symmetry characteristics with Earth at its center. An analysis of anisotropic CMB data yields an interesting hypothesis that the Earth's position plays a role in shaping the structure of the universe on a certain scale. Even more extremely, it can be said that Earth is at the center of the universe. This finding prompts profound contemplation about Earth's position in the structure of the cosmos, opening the door for further research in this field.

A numerical beamforming method for correlated dipole-type sources in the frequency domain is developed. The typical configuration of the location of acoustic field sources and microphones is considered to analyze the noise generated under an aircraft flying in turbulent flow regimes. Three problems of numerical beamforming are studied, allowing one to take into account a priori information about connections between the components of the dipole function at a point. They differ in the number of real functions to be found: six (no connection), four (components are in phase) and two (the direction of the dipole moment is known). The discretization parameters of source function grids and microphones are estimated to ensure stable matrix inversion in numerical beamforming algorithms. The issues of nonuniqueness of solutions for the tangent components of the dipole function in the first and second problems are identified and discussed; for the third problem such an issue does not arise. [ABSTRACT FROM AUTHOR]

The quality of cervical spinal cord images can be improved by the use of tailored radiofrequency (RF) coil solutions for ultrahigh field imaging; however, very few commercial and research 7‐T RF coils currently exist for the spinal cord, and in particular, those with parallel transmission (pTx) capabilities. This work presents the design, testing, and validation of a pTx/Rx coil for the human neck and cervical/upper thoracic spinal cord. The pTx portion is composed of eight dipoles to ensure high homogeneity over this large region of the spinal cord. The Rx portion is made up of twenty semiadaptable overlapping loops to produce high signal‐to‐noise ratio (SNR) across the patient population. The coil housing is designed to facilitate patient positioning and comfort, while also being tight fitting to ensure high sensitivity. We demonstrate RF shimming capabilities to optimize B1+ uniformity, power efficiency, and/or specific absorption rate efficiency. B1+ homogeneity, SNR, and g‐factor were evaluated in adult volunteers and demonstrated excellent performance from the occipital lobe down to the T4‐T5 level. We compared the proposed coil with two state‐of‐the‐art head and head/neck coils, confirming its superiority in the cervical and upper thoracic regions of the spinal cord. This coil solution therefore provides a convincing platform for producing the high image quality necessary for clinical and research scanning of the upper spinal cord. [ABSTRACT FROM AUTHOR]

Context: With the advent of fast computing facilities, combined with rapid emerges of many new and intricate quantum mechanical functionals, computations with pure Hartree–Fock (HF) theory are now-a-days regarded as trivial or obsolete, or even considered as not reliable by many researchers. Consequently, current trends in computational chemistry show extensive use of post-HF theories for smaller molecular systems and various DFT methods for organic and inorganic chemistry related problems (larger molecules/systems). In this contribution, I have tried to show that sometimes, HF might be more suitable over DFT methodologies in addressing structure–property correlations. Molecules studied here were previously synthesized by Boyd in 1966 and important experimental data were produced by Alcalde and co-workers in 1987. Comparison of computed and experimental results clearly shows that HF method was more effective in reproducing the experimental data compared to especially the DFT methodologies. Reliability of HF method was further assured from the very similar results shown by the CCSD, CASSCF, CISD and QCISD methods. Current study also indicates that the localization issue associated with HF proved to be advantageous over delocalization issue of DFT based methodologies, in correctly describing the structure–property correlation for zwitterion systems. Methods: All computations were performed with Gaussian 09. A wide-range of quantum mechanical methodologies, HF, B3LYP, CAM-B3LYP, BMK, B3PW91, TPSSh, LC-ωPBE, M06-2X, M06-HF, ωB97xD, MP2, CASSCF, CCSD, QCISD, CISD and semi-empirical methods like, Huckel, CNDO, AM1, PM3MM and PM6, were used for investigations. [ABSTRACT FROM AUTHOR]

In this paper, design and development of a broadband printed dipole antenna is presented. Broadband performance is achieved by compressing the third order mode toward the first resonant mode. For this, the feed gap of the dipole is modified in the form of a symmetrical step in the feed gap. Operating frequency range of this antenna is 2.56 GHz to 7.8 GHz with 10 dB return loss. This dipole antenna is made directional using an Artificial Magnetic Conductor (AMC) as a reflector. This AMC reflector consists of an array of modified EBG cells of Compact Uniplanar Photonic Band Gap (UC-PBG). The UC-PBG Cell is modified by using cross-slot in it to have wide band characteristics compared to original UC-PBG. For performance optimisation of the dipole antenna, the parametric study is carried out in terms of variation in feed gap parameters. Simulated and measured results for dipole and dipole with AMC reflector are presented. [ABSTRACT FROM AUTHOR]

Magnetoencephalography (MEG) is a noninvasive neuroimaging technique widely recognized for epilepsy and tumor mapping. MEG clinical reporting requires a multidisciplinary team, including expert input regarding each dipole’s anatomic localization. Here, we introduce a novel tool, the “Magnetoencephalography Atlas Viewer” (MAV), which streamlines this anatomical analysis. The MAV normalizes the patient’s Magnetic Resonance Imaging (MRI) to the Montreal Neurological Institute (MNI) space, reverse-normalizes MNI atlases to the native MRI, identifies MEG dipole files, and matches dipoles’ coordinates to their spatial location in atlas files. It offers a user-friendly and interactive graphical user interface (GUI) for displaying individual dipoles, groups, coordinates, anatomical labels, and a tri-planar MRI view of the patient with dipole overlays. It evaluated over 273 dipoles obtained in clinical epilepsy subjects. Consensus-based ground truth was established by three neuroradiologists, with a minimum agreement threshold of two. The concordance between the ground truth and MAV labeling ranged from 79% to 84%, depending on the normalization method. Higher concordance rates were observed in subjects with minimal or no structural abnormalities on the MRI, ranging from 80% to 90%. The MAV provides a straightforward MEG dipole anatomic localization method, allowing a nonspecialist to prepopulate a report, thereby facilitating and reducing the time of clinical reporting.

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To date, the improvement of open‐circuit voltage (VOC) offers a breakthrough for the performance of perovskite solar cells (PSCs) toward their theoretical limit. Surface modification through organic ammonium halide salts (e.g., phenethylammonium ions PEA+ and phenmethylammonium ions PMA+) is one of the most straightforward strategies to suppress defect density, thereby leading to improved VOC. However, the mechanism underlying the high voltage remains unclear. Here, polar molecular PMA+ is applied at the interface between perovskite and hole transporting layer and a remarkably high VOC of 1.175 V is obtained which corresponds to an increase of over 100 mV in comparison to the control device. It is revealed that the equivalent passivation effect of surface dipole effectively improves the splitting of the hole quasi‐Fermi level. Ultimately the combined effect of defect suppression and surface dipole equivalent passivation effect leads to an overall increase in significantly enhanced VOC. The resulted PSCs device reaches an efficiency of up to 24.10%. Contributions are identified here by the surface polar molecules to the high VOC in PSCs. A fundamental mechanism is suggested by use of polar molecules which enables further high voltage, leading ways to highly efficient perovskite‐based solar cells. [ABSTRACT FROM AUTHOR]

Medium polarity plays a crucial role in charge-transfer processes and electrochemistry. The added supporting electrolyte in electrochemical setups, essential for attaining the needed electrical conductivity, sets challenges for estimating medium polarity. Herein, we resort to Lippert–Mataga–Ooshika (LMO) formalism for estimating the Onsager polarity of electrolyte organic solutions pertinent to electrochemical analysis. An amine derivative of 1,8-naphthalimide proves to be an appropriate photoprobe for LMO analysis. An increase in electrolyte concentration enhances the polarity of the solutions. This effect becomes especially pronounced for low-polarity solvents. Adding 100 mM tetrabutylammonium hexafluorophosphate to chloroform results in solution polarity exceeding that of neat dichloromethane and 1,2-dichloroethane. Conversely, the observed polarity enhancement that emerges upon the same electrolyte addition to solvents such as acetonitrile and N,N-dimethylformamide is hardly as dramatic. Measured refractive indices provide a means for converting Onsager to Born polarity, which is essential for analyzing medium effects on electrochemical trends. This study demonstrates a robust optical means, encompassing steady-state spectroscopy and refractometry, for characterizing solution properties important for charge-transfer science and electrochemistry. [ABSTRACT FROM AUTHOR]

The present study proposes a dual-polarized bandwidth-enhanced filtering specialized dipole antenna design for 5G by employing a wide printed dipole, filtering resonators, a reflector surface, and specially designed balun structures. Such a configuration is commonly deployed in conventional base stations. To increase the antenna impedance and radiation bandwidth, a specifically designed, wide-printed flared dipole antenna structure is used as the main radiator element. Transmission zeros are introduced at both pass band edges to create a filtering response by engaging parasitic elements. The parasitic element for the higher frequency edge of the filtering is placed close to the maximum amount of the induced current on the radiator at the operating frequency, whereas the parasitic element for the lower frequency edge of the filtering is located close to the perpendicularly polarized structure. The antenna aims to create radiation nulls at the impedance bandwidth limits; therefore, the parasitic arcs are used to create surface currents that cancel the broadside radiation at the limits of the impedance bandwidth. The study illustrates a complete analysis of the broadband printed patch antenna having a filtering effect by parametric investigations on the dimensions and resulting physical phenomenon in detail. To demonstrate the approach, a prototype of the antenna is fabricated and measured. According to the measurement results, the antenna performs 76% impedance bandwidth between 2.49 GHz and 5.59 GHz with $|S_{11}|$ and $|S_{22}| < -10$ dB by providing exceptional isolation values of $|S_{21}| < -20$ dB in entire operating band. The fabricated antenna has a stable radiation beamwidth with less than $\pm 5^{0}$ variation and the measured gain in the operating frequency is almost constant and equal to 8.2 dBi.

We propose and numerically validate a patch reflectarray modeling approach suitable for small patches that describes each patch as a pair of polarizable magnetic dipoles. We introduce an extraction technique to obtain the effective polarizability of the patch dipoles via full-wave simulations on individual patches, followed by a beamforming design routine valid under weakly scattering configurations. This dipole framework serves as an alternative to the ray tracing model often used in reflectarray designs, in which rays are drawn from the feed point and scattered off of the patch elements. Whereas the ray tracing method solves the design problem in terms of phase delays, the dipole framework presented here has the potential to accurately design and predict beam patterns using a fully dipolar treatment of empirically characterized patches. We illustrate this technique by applying it to two modulation strategies: a variable patch size reflectarray in which the phase can be continuously tuned (grayscale patch response), and a fixed patch size (binary patch response) in which on/off modulation is achieved through selective patch electrical shorting. Methods for incorporating these cases into the dipole design framework are discussed and the results compared to those from full wave simulation.

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This review includes information for around two last decades on cycloaddition reactions of enamines with various agents in order to build carbo‐ and heterocycles. In addition, the review presents organo‐catalytic reactions in which enamines are intermediate products generated in situ. This review covers the synthesis of four, five, six and eight‐membered carbocyclic compounds, as well as heterocycles as pyrroles, pyridines, etc. [ABSTRACT FROM AUTHOR]

Allylation of N-unsubstituted isatin N,N′-cyclic azomethine imines with Morita-Baylis-Hillman carbonates in the presence of 1–10 mol% DABCO in DCM at room temperature, rapidly gave N-allylated and N, β-diallylated isatin N,N′-cyclic azomethine imine 1,3-dipoles in moderate to high yields. The reaction features mild reaction conditions, easily practical operation, and short reaction times in most cases. Furthermore, the alkylated products were transformed into novel bicyclic spiropyrrolidine oxoindole derivatives through the [3+2] or [3+3]-cycloaddition with maleimides or Knoevenagel adducts. [ABSTRACT FROM AUTHOR]

A novel miniaturized dipole antenna design incorporating triple sleeves and shorting load leading to enhanced bandwidth is proposed in the present work. The Triple Sleeve Dipole Antenna with Shorting Loads is designed from 500 to 3000 MHz with no tuning mechanism. The concept of triple sleeve and distributed shorting loads reduced the length of the antenna by 51.5% compared to a half wave dipole antenna at the lowest frequency. The equivalent circuit of the antenna in terms of lumped elements is determined by using a Genetic algorithm. The proposed antenna is simulated in CST Microwave Studio, fabricated, evaluated and the results are presented. The antenna can be used for trans-receive applications of wireless communications in military systems. [ABSTRACT FROM AUTHOR]

The elliptic restricted three-body problem is used to investigate the motion behavior of the smallest body (test particle), where the primaries move in elliptical orbits around their common center of mass. Here the primary is taken as a radiating oblate body and the secondary is considered as a dipole, while the third smallest body is varying its mass according to the Jeans law. Under these assumptions we determine the equations of motion and the quasi-Jacobian integral for the test particle which is moving in space under the gravitational forces of the primaries. The locations of stationary points and their stability states are determined and then, after regions of motion, Poincaré surfaces of section and basins of attraction are illustrated. [ABSTRACT FROM AUTHOR]

A series of Dy3+ doped Gd2O3 nanophosphors was synthesized by combustion method using urea. The crystallite sizes of the samples are found to be in the range of 9–16 nm. Photoluminescence emission spectra of the doped samples show two intense peaks at 487 nm and 575 nm corresponding to 4F9/2–6H15/2 and 4F9/2–6H13/2 transitions, respectively. The intensity of the emission spectra increases with the increase of dopant concentration upto 1at% of Dy3+ due to the energy transfer from Gd3+ of the host to Dy3+ and decreases due to concentration quenching. The electric dipole–dipole interaction mechanism is the main mechanism for concentration quenching. The decay curves are well fitted with bi exponential equation. The CIE co-ordinates and CCT values of the doped samples are found to be closed to that of white light. [ABSTRACT FROM AUTHOR]

The problem of precisely estimating the position and orientation of multiple dipoles using synthetic EEG signals is considered in this paper. After determining a proper forward model, a nonlinear constrained optimization problem with regularization is solved, and the results are compared with a widely used research code, namely EEGLAB. A thorough sensitivity analysis of the estimation algorithm to the parameters (such as the number of samples and sensors) in the assumed signal measurement model is conducted. To confirm the efficacy of the proposed source identification algorithm on any category of data sets, three different kinds of data-synthetic model data, visually evoked clinical EEG data, and seizure clinical EEG data are used. Furthermore, the algorithm is tested on both the spherical head model and the realistic head model based on the MNI coordinates. The numerical results and comparisons with the EEGLAB show very good agreement, with little pre-processing required for the acquired data. [ABSTRACT FROM AUTHOR]