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This study presents a new dual‐band terahertz absorber (DBTA) with ease of production consisting of a metallic base plane of a certain thickness, a dielectric layer on this plane, and a hexagonal metallic metasurface structure. The proposed absorber exhibits absorption band peaks above 99% at two distinct frequencies (7.51 and 8.08 THz). The absorption origin is explained as a dual‐band response using the LC resonance and dipolar response. In this way, the presented absorber facilitates production by improving absorption responses with a much simpler structure, unlike studies with complex geometries. The proposed dual‐band absorber results in sensitivity to the polarization of the incident light. Thus, it also makes the proposed structure very helpful for manipulating wave polarization and detecting waves with particular polarization. The hexagonal structure of the absorber is scaled to millimeter dimensions, and its transformation into another dual‐band absorber that can also operate in microwave frequency regions. Similarly, the hexagonal structure is transformed into a circular structure with the same geometric dimensions, and a different dual‐band absorber is obtained in the terahertz (THz) region. Moreover, the proposed concept can be extended for various applications such as bolometric sensing, thermal imaging, energy harvesting, sensing, and selective thermal emitters. [ABSTRACT FROM AUTHOR]

N-heterocyclic carbenes (NHCs) are an eminent class of carbenes having a heterocyclic ring in which a divalent carbon atom is attached directly to a nitrogen atom. In the NHCs, the donation of lone pair is another important research in the dative bonding and not only in NHCs the dative bond plays a functionalized role in the other classes of complex formation like ylidones L → E ← L and carbones L → C ← L. M–NHC bond is L-M sigma-dative bond and NHCs are considered as strong sigma-donor ligands. The clear picture of the M–NHC bond can be better understood by M–NHC pi-interaction. M-L pi interaction is comprised of two steps. One is L → M sigma-donation and M → L π* back bonding. This dative donor nature of NHC and also its behavior in organoselenium is studied through DFT in which it's optimized structure, bond lengths, molecular vibrations are calculated. [ABSTRACT FROM AUTHOR]

This study considers the dependence of the force caused by the dipolar interaction between small low-dimensional magnets such as single-molecule magnets and two-dimensional magnets on the distance between them within the framework of the dipolar Ising model with nearest-neighbor exchange interactions and long-range dipolar interactions. In particular, we focus on the rapid change in the force between ferromagnetic and antiferromagnetic plates, which arise from the transition of the spin states and explain that this behavior originates from the spin frustrations between magnetic plates. Furthermore, the size and temperature dependence of the interaction energy are investigated using a Monte Carlo simulation.

Abstract With a wide applicability in solid state mechanics, the theory of continuous dipolar materials with voids is a distinctive part of microstructure theory, a theory that emerged with the necessity of eliminating the discrepancies between the classical theory and its experimental applications. These inconsistencies are caused by the influence of the microstructure of materials on the general deformations of the bodies, such as ceramics, graphite or polymers. In the present work, we study the mixed boundary value problem with initial data for the thermoelasticity of three-phase-lag dipolar materials with voids, in order to obtain the corresponding constitutive laws, using the same method as in the classical elasticity. By going deeper into the study of these materials, we achieve a uniqueness result and a reciprocal relation, using less common methods, like the dissipative inequality regarding the result of uniqueness. Along with these aspects, we demonstrate a variational principle for anisotropic and non-homogeneous materials, derived from a well-known variational principle, but studied in the context of thermoelasticity of three-phase-lag dipolar materials with voids.

In this work, we propose a novel dual-broadband terahertz (THz) metamaterial absorber (MA) using a single asymmetric resonator, which is designed by diagonally splitting a single square gold patch with two opposite corner defects. The proposed absorber has the extended absorption bands with absorptivity above 90% in two frequency ranges of 2.36–3.82 THz and 5.37–6.33 THz. The physical origin of dual-broadband absorption is investigated by the impedance matching theory and the electric field distributions. We also investigate the influences of oblique incidence and polarization angles on dual-broadband absorption performance. Compared with other broadband THz MAs based on asymmetric resonators, our dual-broadband THz MA has excellent performances such as simple structure, high absorptivity, broadband and dual-band absorption characteristics. [ABSTRACT FROM AUTHOR]

The mechanism of dehydration of a water-in-oil emulsion is complex and involves the growth of an emulsion of polydispersed water droplets in oil, under an electric field, and their gravitational settling and phase separation. In this work, a simple configuration is chosen to understand the mechanism of this complex process. A population balance-based model is developed to predict the performance of an electrocoalescer. The model explicitly accounts for the coalescence of water drops by the action of dipolar forces and gravity settling. A distributed parameter plug flow and a tank-in-series model are developed to account for the gravity settling. The dynamics of electrocoalescence are captured by analyzing the drop size distribution and mean diameter along with the height of the coalescer and time. A simplified model - considering that monodispersity prevails throughout the process is also developed, and the separation curves are compared with the polydispersed system. The effect of operational parameters, such as the strength of the electric field, water cut, viscosity of oil, the height of the coalescer, and polydispersity in the initial drop size distribution, is investigated. The main insight from this work is that there are essentially three stages of electrocoalescence, a slow initial incubation stage where droplets grow to around 1 mm in size without much settling, followed by a rapid settling of these droplets to set in the fast coalescence stage where most water is removed to result in a lean emulsion, followed by a slow simultaneous electrocoalescence and separation stage of this lean emulsion to result in a final separation. A scaled masterplot for the performance of an electrocoalescer, encompassing the effect of the process parameters is obtained. The model also suggests that electrocoalescence essentially leads to a polydisperse system and a population balance approach is critical to its analysis. • Dehydration efficiency of W/O emulsion is predicted using population balance model. • Model accounts for droplet coalescence due to dipolar forces & gravity settling. • Effect of electric field, water cut, oil viscosity & other factors is investigated. • Scaled masterplot for performance, encompassing process parameters, is constructed. [ABSTRACT FROM AUTHOR]

In the present study we derive expressions for relaxation rate functions due to dipolar interactions between identical spins in the rotating frames of rank greater than or equal to 3. The rotating frames are produced due to fictitious magnetic field as generated by amplitude and frequency modulated radiofrequency (RF) pulses operating in non-adiabatic regime. This solution provides a means for description of the relaxations during method entitled Relaxation Along a Fictitious Field (RAFF) in the rotating frame of rank n (RAFFn), in which a fictitious field is created in a coordinate frame undergoing multi-fold rotation about n axes (i.e., rank n). We validate the proposed model by comparison with the accepted trigonometric relations for relaxation rates between tilted frames. The agreement between the proposed model for RAFF3 and the trigonometric model is excellent. [ABSTRACT FROM AUTHOR]

A quasi-periodic superlattice was designed, consisting of the epitaxial BaTiO 3 single crystal matrix and the Ni nanocrystals (NCs). For the in-plane Ni NCs the statistical interparticle spacing ( R ) with a log-normal distribution was controlled ranging from 9 to 28 nm. With the decrease of R , the preferential orientation of the Ni NCs was changed from (001) to (111), inducing the transition of magnetic anisotropy from the out-of-plane to the in-plane direction. Increasing the in-plane R modulated the collective magnetic behavior by effectively lowering the interparticle dipolar coupling. For the Ni NCs/BaTiO 3 system, it displayed a noninteracting system in the out-of-plane, and possesses an in-plane tunability between the interacting ( R < 21 nm) and noninteracting ( R ≥ 21 nm) system according to change the R . The increase of in-plane anisotropy energy induced the enhancement of dipole-dipole interaction among the Ni NCs. [ABSTRACT FROM AUTHOR]

• Cu x Fe 3-x O 4 with (x = 0.15, 0.31, and 0.47) nanoparticles were synthesized and coated with biopolymers (dextran) using the solvo-thermal route. • Lower coercivity (H c) and anisotropy were observed at room temperature implying nearly superparamagetic behavior. • The self-heating efficiency of uncoated and coated nanoparticles were analysed by taking into account the Brownian and Néel spin relaxations. It was concluded that after dextran coating, the temperature was controlled and that Néel relaxation was dominant on SAR. • The study also demonstrated that the dipolar interaction influenced the Néel relaxation mechanism which was important in the heat generation mechanism of the MNPs. The dipolar interaction and magnetic anisotropy effect are the key parameters to tune the self-heating effect of magnetic nanoparticles (MNPs). In this paper, we investigate the impact of Cu2+ doped Fe 3 O 4 and dextran coated nanoparticles (Cu x Fe 3-x O 4 with x = 0.15, 0.31, and 0.47) on thermal properties using specific absorption rate measurements (SAR). We look into the prospect of using dipolar and anisotropy effects to increase or decrease the heat released by magnetic nanoparticles, potentially boosting hyperthermia applications. Magnetic nanoparticles with an average particle size of 12–20 nm were observed via TEM. The influence of Cu2+ doping on the structural and magnetic properties of the samples was studied using a vibrating sample magnetometer (VSM). The effective anisotropy calculated for x = 0.15 and x = 0.47 were 5.5 and 4.4 j/m3 respectively. It was shown that increasing the copper doping reduced the effective anisotropy, lowering the SAR values. The SAR value obtained for x = 0.15 and dex-x = 0.15 were 787 and 591 W/g respectively. The uncoated Cu x Fe 3-x O 4 nanoparticles achieved hyperthermia temperatures (42–48 °C) much faster than the dextran-coated samples. Eventually temperature can be adjusted to the desired hyperthermia temperature range by altering the sample and Cu2+ concentration. The dextran coating has been shown to dramatically reduce SAR values while still assisting in magnetic hyperthermia temperature regulation. The study also demonstrated that the dipolar interaction influenced the Néel relaxation mechanism which was important in the heat generation mechanism of the MNPs [ABSTRACT FROM AUTHOR]

We propose and analyze a realizable scheme for performing a Heisenberg-limited Mach–Zehnder interferometry with a dipolar spin-1 condensate. Based upon adiabatic processes of sweeping the transverse magnetic field, we demonstrate a perfect phase transition, which accomplishes the beam splitter, phase shifter and recombiner as for a Mach–Zehnder interferometer. The attractive dipolar interaction ensures the existence of a path-entangled state which enhances the phase measurement precision to the Heisenberg limit. We also study the spin squeezing of the state generated in the beam splitter and show that the spin squeezing exhibits an extremum near the critical point of phase transition. [ABSTRACT FROM AUTHOR]

We consider N trapped bosons in R³ interacting via a pair potential w which has a long range of dipolar type. We show the convergence of the energy and of the minimizers for the many-body problem towards those of the dipolar Gross-Pitaevskii functional, when N tends to infinity. In addition to the usual cubic interaction term, the latter has the long range dipolar interaction. Our results hold under the assumption that the two-particle interaction is scaled in the form N3β-1w(Nβx) for some 0 ≤ < βmax with βmax = 1/3 + s/(45 + 42s), where s is related to the growth of the trapping potential. [ABSTRACT FROM AUTHOR]

The goal of this article is to combine the theory based on fractional order of strain with the theory of thermoelasticity of dipolar bodies with voids, in order to obtain the basic thermoelasticity equations with fractional order strain for dipolar materials with voids. [ABSTRACT FROM AUTHOR]

We provide a comprehensive account of the 1,3-dipolar cycloaddition reactions of azomethine ylides with carbonyl dipolarophiles. Many different azomethine ylides have been studied, including stabilized and non-stabilized ylides. Of the carbonyl dipolarophiles, aldehydes including formaldehyde are the most studied, although there are now examples of cycloadditions with ketones, ketenes and carboxyl systems, in particular isatoic anhydrides and phthalic anhydrides. Intramolecular cycloadditions with esters can also occur under certain circumstances. The oxazolidine cycloadducts undergo a range of reactions triggered by the ring-opening of the oxazolidine ring system. [ABSTRACT FROM AUTHOR]

A novel hybrid carrier-based pulse width modulation (CBPWM) scheme that combines unipolar and dipolar modulations is proposed for single-phase three-level rectifiers, which are widely applied in railway traction drive systems. The proposed CBPWM method can satisfy the volt-second balancing principle in the complete modulation index region through ovennodulation compensation. The modulation scheme features two modulation modes: unipolar and dipolar. The operation range limits of these modulation modes can be modified by changing the separation coefficient. In comparison with the traditional unipolar CBPWM, the proposed hybrid CBPWM scheme can provide advantageous features, such as lower high-order harmonic distortion of the line current and better utilization of switching frequency. The separation coefficient value is optimized to achieve the maximum utilization of these advantages. The experimental results verify the feasibility and effectiveness of the proposed hybrid CBPWM scheme. [ABSTRACT FROM AUTHOR]

We study solitons in a zig-zag lattice of magnetic dipoles. The lattice comprises two sublattices of parallel chains with magnetic dipoles at their vertices. Due to orthogonal easy planes of rotation for dipoles belonging to different sublattices, the total dipolar energy of this system is separable into a sum of symmetric and chiral long-ranged interactions between the magnets where the last takes the form of Dzyaloshinskii-Moriya (DM) coupling. For a specific range of values of the offset between sublattices, the dipoles realize an equilibrium magnetic state in the lattice plane, consisting of one chain settled in an antiferromagnetic (AF) parallel configuration and the other in a collinear ferromagnetic fashion. If the offset grows beyond this value, the internal DM field stabilizes two Bloch domain walls at the edges of the AF chain. The dynamics of these solitons is studied by deriving the long-wavelength lagrangian density for the easy axis antiferromagnet. We find that the chiral couplings between sublattices give rise to an effective magnetic field that stabilizes the solitons in the antiferromagnet. When the chains displace respect to each other, an emergent Lorentz force accelerates the domain walls along the lattice., (Creative Commons Attribution license.)

A series of mono- and di-branched donor-τ-acceptor charge-separated dyes incorporating triphenylamine as a donor and either Dalton's or benzothiadiazole group as strong acceptors was synthesized and its fundamental properties relevant to the sensitization of nanocrystalline NiO investigated. The dyes exhibited an intense visible absorption band with a strong charge transfer character favorable to NiO sensitization, shifting the electron density from the donor to the acceptor branches. Nevertheless, the computed exciton binding energy is circa twice that of a common literature standard (P1), suggesting a more difficult charge separation. When tested in p-type dye-sensitized solar cells the dyes successfully sensitized NiO electrodes, with photocurrent densities about half than that of the reference compound. Being recombination kinetics comparable, the larger photocurrent generated by P1 agrees with the superior charge separation capability originating by its smaller exciton binding energy. [ABSTRACT FROM AUTHOR]

Using a simple design method cutting away some parts of a circular metallic patch resonator, we propose an ultra-broadband terahertz metamaterial absorber (MA) with bandwidth of 4.11 THz. Simulation results demonstrate that the simple design method greatly improves the absorption performance compared with previously reported absorbers. The proposed absorber exhibits the co-polarization ultra-broadband absorption performance with absorptivity above 90% in the range of 2.65–6.76 THz and the relative absorption bandwidth (RAB) of 87.35%. Moreover, the proposed absorber can maintain high absorptivity above 80% for incident angles up to 40° under both transverse electric (TE) and transverse magnetic (TM) polarizations. The ultra-broadband absorption originates from the combination of dipolar and LC resonances. The simple design method can also be applied to some other structures such as square metallic patch resonator. Furthermore, by adjusting the dimensions of proposed absorber, a broadband microwave MA can be easily obtained. Therefore, it can become an effective design method to achieve broadband absorption in various frequency ranges from microwave to optical frequencies. • A simple design method for enhancement of absorption bandwidth was presented. • This method greatly improves the absorption performance of the metamaterial absorber. • This method provides us the flexibility to choose the resonator type and working frequency range. [ABSTRACT FROM AUTHOR]

With a wide applicability in solid state mechanics, the theory of continuous dipolar materials with voids is a distinctive part of microstructure theory, a theory that emerged with the necessity of eliminating the discrepancies between the classical theory and its experimental applications. These inconsistencies are caused by the influence of the microstructure of materials on the general deformations of the bodies, such as ceramics, graphite or polymers. In the present work, we study the mixed boundary value problem with initial data for the thermoelasticity of three-phase-lag dipolar materials with voids, in order to obtain the corresponding constitutive laws, using the same method as in the classical elasticity. By going deeper into the study of these materials, we achieve a uniqueness result and a reciprocal relation, using less common methods, like the dissipative inequality regarding the result of uniqueness. Along with these aspects, we demonstrate a variational principle for anisotropic and non-homogeneous materials, derived from a well-known variational principle, but studied in the context of thermoelasticity of three-phase-lag dipolar materials with voids. [ABSTRACT FROM AUTHOR]