Magnitude Of Constant Research Articles

Trapped ions beyond carrier and sideband interactions

Trapped ions driven by electromagnetic radiation constitute one of the most developed quantum technologies to date. The scenarios range from proof-of-principle experiments to on-chip integration for quantum information units. In most cases, these systems have operated in a regime where the magnitude of the ion-radiation coupling constant is much smaller than the trap and electronic transition frequencies. This regime allows the use of simple effective Hamiltonians based on the validity of the rotating-wave approximation. However, novel trap and cavity designs now permit regimes in which the trap frequency and the ion-radiation coupling constant are commensurate. This opens up new avenues for faster quantum gates and state transfers from the ion to a photon and other quantum operations. From the theoretical side, however, there is not yet much known in terms of models and applications that go beyond the weak-driving scenario. In this work, we present two main results in the scenario of stronger driving. First, we revisit a known protocol to reconstruct the motional Wigner function and expand it to stronger-driving lasers. This extension is not trivial because the original protocol makes use of effective Hamiltonians valid only for weak driving. The use of stronger fields or faster operations is desirable since experimental reconstruction methods of that kind are usually hindered by decoherence. We then present a model that allows the analytical treatment of stronger driving and that works well for nonresonant interactions, which are generally out of the reach of previous models.

Magnetic properties and pH-controlled reversible interconversion of µ-oxido into µ-hydroxido in oxo-carboxylato bridged iron(III) dimers: Theoretical and experimental insights

Three dinuclear complexes of formula [FeIII2(µ-O)(µ-OOCR)(L)2](ClO4)·G, with R/G=H/(EtOAc)2 (1·2EtOAc), CH3/(Et2O)2 (2·2Et2O) and C6H5/(CH3OH)2(CH3CN)2 (3·2CH3OH·2CH3CN), [where HL = 2-((((1-methylbenzimidazol-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)phenol] have been prepared. The ligand provides a N,N,N,O donor set in its deprotonated form. X-ray diffraction analyses revealed that the complexes have a similar oxido-carboxylato-bridged structure where each metal ion has a tertiary amine, one imidazolyl N atom, one pyridyl N atom and a phenolate O atom as terminal coordination. Thus, each metal centre assumes a FeIIIN3O3 coordination in an octahedral environment. Addition of acid lead to the generation of similar dinuclear complexes formulated as [FeIII2(µ-OH)(µ-OOCR)(L)2](ClO4)2, with R=H (1H), CH3 (2H) and C6H5 (3H) in solution. This protonation of the µ-O bridge is reversible and addition of base regenerates the original complexes (1–3). Magnetic measurements showed intramolecular antiferromagnetic Fe···Fe interactions in compounds 1–3 with J = ‒276(1), ‒197(1) and ‒190(1) cm−1, respectively. DFT/B3LYP calculation helped us to explicitly state the sign and magnitude of the magnetic coupling constants along with an approaching to the spin density distribution.

Spin–Orbit Couplings of Open-Shell Systems with Restricted Active Space Configuration Interaction

In this work we perform electronic structure calculations to unravel the origin of spin-orbit couplings (SOCs) in open-shell molecules. For that, we select systems displaying di or polyradical character, e.g., trimethylene, and analyze the changes in the magnitude of SOC constants along molecular distortions of ethylene and in the presence of intermolecular interactions between open and closed-shell moieties in the O2-C2H4 system. Calculations were performed by using nonrelativistic wave functions obtained with the restricted active space configuration interaction (RASCI) method, in conjunction with a recent implementation for the calculation of SOC based on the spin-orbit mean field approximation. Our results demonstrate the suitability of RASCI in the calculation of SOCs of open-shell systems, while providing a deep understanding of the relationship between couplings and the nature of the electronic states. Moreover, we introduce a new definition of the SOC constant for the study of molecular aggregates.

An approximate line attractor in the hypothalamus encodes an aggressive state

The hypothalamus regulates innate social behaviors, including mating and aggression. These behaviors can be evoked by optogenetic stimulation of specific neuronal subpopulations within MPOA and VMHvl, respectively. Here, we perform dynamical systems modeling of population neuronal activity in these nuclei during social behaviors. In VMHvl, unsupervised analysis identified a dominant dimension of neural activity with a large time constant (>50 s), generating an approximate line attractor in neural state space. Progression of the neural trajectory along this attractor was correlated with an escalation of agonistic behavior, suggesting that it may encode a scalable state of aggressiveness. Consistent with this, individual differences in the magnitude of the integration dimension time constant were strongly correlated with differences in aggressiveness. In contrast, approximate line attractors were not observed in MPOA during mating; instead, neurons with fast dynamics were tuned to specific actions. Thus, different hypothalamic nuclei employ distinct neural population codes to represent similar social behaviors.

Исследование зависимости сдвига линии ферромагнитного резонанса от параметров пьезоэлектриков

In this research, we study the dependence of the shift of the ferromagnetic resonance line in layered structures based on yttrium iron garnet (YIG) on a gadolinium gallium garnet (GGG) substrate, on the magnitude of the external electric field and on the parameters of various piezoelectrics (plumbum zirconate titanate (PZT), Langasite)). The intense development of modern microwave technology leads to the study and creation of new layered structures of materials with different physical properties that can be combined: magnetic and ferroelectric, magnetic and semiconductor, etc. As a result of the study, we obtained the dependences of the shifts of the ferromagnetic resonance line on the parameters of piezoelectrics (mainly, on the magnitude of the dielectric constant) in the layered structures YIG-GGGPZT, YIG-GGG-Langasite. The obtained results show that the ferromagnetic resonance line shift effect can be used to develop new controllable microwave devices, the operating principle of which is based on the electronic tuning of resonance characteristics by means of an electric field and the choice of the type of piezoelectric.

Optical and temperature dependent electrical properties of poly (vinyl chloride)/copper alumina nanocomposites for optoelectronic devices

Abstract The practical applications of poly (vinyl chloride) have been constrained due to its poor thermal stability, low dielectric constant and inability to shield against ultraviolet (UV) radiation. In this study, we tried to improve the optical properties, thermal stability, temperature-dependent electrical conductivity and dielectric constant using copper alumina (Cu–Al2O3) nanoparticles reinforced poly (vinyl chloride) (PVC). Optical absorption measured with an ultraviolet-visible (UV-visible) spectrometer emphasises the blueshift in absorption edges and decreasing bandgap energies of PVC/Cu–Al2O3 nanocomposites compared to PVC. The presence of Cu–Al2O3 in PVC and its interaction with the polymer were confirmed by FTIR spectroscopy. Thermogravimetric analysis (TGA) demonstrates that nanocomposites have higher thermal stability than PVC, and that thermal stability increases with filler loading. Scanning electron microscopy (SEM) indicates the homogeneous dispersion of nanosized Cu–Al2O3 in the polymer matrix. The activation energy determined by the Arrhenius equation revealed that AC conductivity increases with the addition of nanoparticles up to a specific loading. The dielectric constant increases as a function of temperature and decreases with frequency. The magnitude of AC conductivity and dielectric constant were highest for 7 wt% loaded nanocomposites. The dielectric constant predicted by the Bruggeman and Maxwell-Garnet models were in good agreement with the experimental permittivity. The semiconducting nature of nanocomposites was investigated by impedance analysis. The semi-circular nature of Cole-Cole plots manifests the combination of parallel capacitance with low bulk resistance. The enhanced optical, thermal, electrical and dielectric properties of PVC/Cu–Al2O3 nanocomposites can be utilized in fabricating optoelectronic devices with excellent charge-storing ability.

Influence of stress-induced anisotropy on domain structure and magnetic properties of Fe-based nanocrystalline alloy under continuous tension annealing

The correlation among microstructures, magnetic properties and domain patterns for the FINEMET nanocrystalline ribbons treated in a home-made continuous tension annealing equipment under different tensile stresses (σ) were investigated in detail. Results show that the effective permeability (μe) of the nanocrystalline ribbons can be expediently adjusted from 412.83 to 1659.96 by manipulating the magnitude of stress-induced anisotropy constant (Ku), wherein the Ku and σ are in a linear relationship. Owing to the increasing domain wall energy induced by the increase of σ for the nanostructured ribbons, the attenuation of μe with the elevating applied field and frequency can be effectively suppressed, the average domain width between the strip-like domain patterns gradually decreases, and the domination of magnetization process alters from domain-wall displacement to homogeneous rotation. These results will provide a referable idea for current transformers to meet the requirements of higher precision and lower energy consumption.

Ultrahigh-Resolution Homo- and Heterodecoupled 1H and TOCSY NMR Experiments.

The original homonuclear decoupled (pure shift) experiments provide ultrahigh-resolution 1H spectra of compounds containing NMR-active heteronuclei of low natural isotopic abundance (e.g., 13C or 15N). In contrast, molecules containing highly abundant heteronuclei (like 31P or 19F) give doublets or a multiple of doublets in their homonuclear decoupled spectra, depending on the number of heteronuclear coupling partners and the magnitude of the respective coupling constants. In these cases, the complex and frequently overlapping signals may hamper the unambiguous assignment of resonances. Here, we present new heteronuclear decoupled (HD) PSYCHE 1H and TOCSY experiments, which result in simplified spectra with significantly increased resolution, allowing the reliable assessment of individual resonances. The utility of the experiments has been demonstrated on a challenging stereoisomeric mixture of a platinum-phosphine complex, where ultrahigh resolution of the obtained HD PSYCHE spectra made the structure elucidation of the chiral products feasible. HD PSYCHE methods can be potentially applied to other important 31P- or 19F-containing compounds in medicinal chemistry and metabolomics.

Larger Intrinsic Rate Constants of Alpha-amylase is Possible if Intrinsic Forward Rate Constant is ≠ Diffusion limited Rate of Encounter

Background: Previous research has shown that the intrinsic reverse (backward) and forward rate constants are larger than the effective or apparent rate constants for the formation and dissociation of an enzyme-substrate complex (ES). It is speculated that such intrinsic rate constants could be larger if an appropriate mathematical equation was adopted for their computation. 
 Methods: Theoretical, experimental (Bernfeld method), and computational methods.
 Objectives: 1) To rederive the equations for calculating the intrinsic rate constants for forward (k1) and reverse (i.e., backward) (k2) reactions; 2) to calculate the intrinsic rate constants; and 3) to show that the probability (1/g) (or req(r)) that an enzyme is at a distance from the substrate is a variable. 
 Results and Discussion: The equations for the determination of k2 and k1 were rederived. Unlike previous findings, the intrinsic (reverse) first order rate, k2 and forward second order rate, k1 were larger than their apparent counterparts, but they were, however, very similar in magnitude. The intrinsic rate constants were much larger than previously reported values when the enzyme (E) total concentration [ET] was much less than substrate’s total concentration [ST]. The k1 and apparent forward second order rate (kf) values where [ET] is much less than [ST] were > where [ET] is less than [ST]. Therefore, the magnitude of the second order rate constant is a function of [ET]. The values of k1 and k2 where [ET] is much less than [ST] and vice-versa were respectively, 7.41 exp. (+6) L/mol. min and 81.34 exp. (+4) /min, and 15.76 exp. (+6) L/mol. min and 58.08 exp.(+4) /min. It was discovered that the probability (1/g) (or req(r))) that an enzyme is at a distance from the substrate with the possibility of mutual attraction is not constant. 
 Conclusion: If the intrinsic forward rate constant (k1) is not equal to diffusion limited rate (kD) of encounter, the k1 and k2 values could be larger than values where k1 is equal to kD. The probability (1/g) (or req(r)) that an enzyme is at a distance from the substrate with the possibility of mutual attraction has been discovered to be a variable constant dependent on the concentration of the reaction mixture components and the enzyme's affinity for the substrate, and vice versa. Future research may attempt to derive an equation for the determination of an intrinsic catalytic rate constant for the formation of a product.

Elucidation of the O-antigen structure of Escherichia coli O93 and characterization of its biosynthetic genes.

The structure of the O-antigen from the international reference strain Escherichia coli O93:-:H16 has been determined. A nonrandom modal chain-length distribution was observed for the lipopolysaccharide, a pattern which is typical when long O-specific polysaccharides are expressed. By a combination of (i) bioinformatics information on the gene cluster related to O-antigen synthesis including putative function on glycosyl transferases, (ii) the magnitude of NMR coupling constants of anomeric protons, and (iii) unassigned 2D 1H, 13C-HSQC, and 1H,1H-TOCSY NMR spectra it was possible to efficiently elucidate the structure of the carbohydrate polymer in an automated fashion using the computer program CASPER. The polysaccharide also carries O-acetyl groups and their locations were determined by 2D NMR experiments showing that ~½ of the population was 2,6-di-O-acetylated, ~¼ was 2-O-acetylated, whereas ~¼ did not carry O-acetyl group(s) in the 3-O-substituted mannosyl residue of the repeating unit. The structure of the tetrasaccharide repeating unit of the O-antigen is given by: →2)-β-d-Manp-(1→3)-β-d-Manp2Ac6Ac-(1→4)-β-d-GlcpA-(1→3)-α-d-GlcpNAc-(1→, which should also be the biological repeating unit and it shares structural elements with capsular polysaccharides from E. coli K84 and K50. The structure of the acidic O-specific polysaccharide from Cellulophaga baltica strain NN015840T differs to that of the O-antigen from E. coli O93 by lacking the O-acetyl group at O6 of the O-acetylated mannosyl residue.

Measuring the inflaton coupling in the CMB

We study the perspectives to extract information about the microphysical parameters that governed the reheating process after cosmic inflation from CMB data. We identify conditions under which the inflaton coupling to other fields can be constrained for a given model of inflation without having to specify the details of the particle physics theory within which this model is realised. This is possible when the effective potential during reheating is approximately parabolic, and when the coupling constants are smaller than an upper bound that is determined by the ratios between the inflaton mass and the Planck mass or the scale of inflation. We consider scalar, Yukawa, and axion-like interactions and estimate that these conditions can be fulfilled if the inflaton coupling is comparable to the electron Yukawa coupling or smaller, and if the inflaton mass is larger than 105 GeV. Constraining the order of magnitude of the coupling constant requires measuring the scalar-to-tensor ratio at the level of 10-3, which is possible with future CMB observatories. Such a measurement would provide an important clue to understand how a given model of inflation may be embedded into a more fundamental theory of nature.

Interface Design Considering Intrinsic Properties of Dielectric Materials to Minimize Space‐Charge Layer Effect between Oxide Cathode and Sulfide Solid Electrolyte in All‐Solid‐State Batteries

AbstractIntroducing dielectric materials is a promising approach to mitigate space‐charge‐layer (SCL) formation, which negatively affects the electrochemical performance of sulfide‐based all‐solid‐state batteries (ASSBs). Most previous studies have focused on mitigating SCL formation by introducing dielectric materials, overlooking the fact that significant dielectric properties such as the dipole moment direction and the magnitude of the dielectric constant can influence SCL formation. To clarify the unclear mechanism of dielectric materials mitigating SCL formation, paraelectricity, ferroelectricity, and the magnitude of the dielectric constant are investigated to determine their effect on SCL formation. Paraelectric materials possessing no permanent dipole moment can effectively mitigate the SCL formation better than ferroelectric material with strong permanent dipole moment because of the intrinsic characteristics of the paraelectric material, in which the dipole moment can be aligned along the direction of the electric field applied inside of ASSB. Furthermore, paraelectric materials with a larger dielectric constant have a greater effect in mitigating SCL effect than paraelectric materials with a smaller dielectric constant. Thus, these properties should be considered in cathode‐solid‐electrolyte interface design. This study considers relevant dielectric material characteristics that had not been considered previously, suggesting a new paradigm for optimizing the interfacial resistance of sulfide‐based ASSBs originating from SCL formation.

Anisotropy of magnetoelastic properties in epitaxial Co2FexMn1−xSi Heusler alloy thin films

A strain modulated ferromagnetic resonance technique was applied to determine two cubic magnetoelastic constants of the epitaxially grown 30-nm-thick ${\mathrm{Co}}_{2}{\mathrm{Fe}}_{x}{\mathrm{Mn}}_{1\ensuremath{-}x}\mathrm{Si}$ magnetic layers with different Fe and Mn contents, which were deposited on a MgO substrate with a 20-nm-thick Cr buffer layer---MgO (001) $\ensuremath{\parallel}$ Cr(001) $\ensuremath{\parallel} {\mathrm{Co}}_{2}{\mathrm{Fe}}_{x}{\mathrm{Mn}}_{1\ensuremath{-}x}\mathrm{Si}$ (001). It was found that, for the samples with the Fe content $x=0.4$ or higher, the magnitudes of the two cubic magnetoelastic constants are clearly different, showing that the magnetoelastic properties of these samples are different than in the case of isotropic samples for which these two constants are expected to be equal. The magnitude of the cubic magnetocrystalline anisotropy constant reveals an evident maximum at the composition of $x=0.4$, which corresponds to the minimum of the minor spin density of states, and thus the correlation between the cubic magnetocrystalline anisotropy and the electronic band structure. For all the investigated samples, a large perpendicular component of the magnetocrystalline anisotropy was observed as well as inhomogeneous broadening of the ferromagnetic resonance linewidth.

Strain controlled antiferromagnetic insulating state along with ferroelectricity and magnetic anisotropy in Pb2CoTeO6

Controlling electronic and magnetic properties of materials by strain engineering is essential and extremely sought for high-performance spintronic devices as strain can be easily achieved experimentally. In this respect, antiferromagnetic (AFM) double perovskite oxides (DPO) have attracted a lot of attention due to ultrafast spin moments and small stray field, which is potentially desired for high-frequency and high-data storage devices. Herein, the electronic, magnetic, and ferroelectric properties of Pb 2 CoTeO 6 DPO under uniaxial ([100], [010], and [001]), biaxial ([110]), and hydrostatic ([111]) strains are investigated in the framework of first-principles calculations including Hubbard parameter U . Pristine motif emerges as AFM insulator having an indirect energy band gap of 1.88 eV due to anti-alignment of Co ions at the diagonal. The most striking feature of the present study is that system exhibits a substantial magnitude of spontaneous polarization of 32 μ C/cm 2 and magnetocrystalline anisotropy constant of 5.4 × 10 7 erg/cm 3 with an easy axis of [011]. Moreover, it is found that Co lies in a ＋ 2 state having an electronic configuration of t 2 g 3 ↑ e g 2 ↑ t 2 g 2 ↓ e g 0 ↓ with S= 1.5 and displays a spin moment of 2.71 μ B . The solidity of AFM state and robustness of the insulating nature is confirmed under the influence of strains. An indirect to direct band gap transition is established for compressively strained motifs, which is useful for optics as well as the solar cell industry. Finally, it is revealed that overall compressive and tensile strains show a negative and positive impact on the spontaneous polarization amplitude, respectively. • Anti-ferromagnetic (AFM) super-exchange coupling leads the system to AFM ground state. • System exhibits a reasonable magnitude of magnetic anisotropy energy constant. • The solidity of AFM state and robustness of the insulating nature is confirmed under the influence of strains. • A substantial amplitude of spontaneous polarization of 32 μ C/cm 2 .

Synthesis, molecular structural, optical, thermal and third harmonic nonlinear optical analysis of Piperazine-1,4-diium bis(2-carboxy-6-nitrobenzoate) tetrahydrate single crystal

Structure and molecular interactions of the title molecular salt (NPP) were established by X-ray diffraction. The elucidated structure model assigns centrosymmetric triclinic arrangement for the molecules. Molecular packing was established through robust O–H⋯O, N–H⋯O and C–H⋯O hydrogen bond network revealing infinite chains, sheets and spiral ladder patterns. The molecular patterns were abridged through C–H … π and π – π linkages expressing several S and R graph set motifs. Single crystals of NPP with defined morphology were grown by the method of slow evaporation from solution from 1: 1 mixed solvent of methanol and water. FT- IR, FT - Raman spectra reinforced the functional groups and with NMR spectra, the protonated-deprotonated nature of the title molecule. UV–visible, Urbach plot, photoluminescence and fluorescence spectral profiles endorsed the electronic transitions and photophysical properties of NPP. Z-scan profile in the closed and open aperture modes was deployed to estimate the magnitude of the third-order nonlinear optical constants. Thermogravimetry coupled with Differential Scanning Calorimetry (DSC) declare the optimal thermal stability of the material till 71.8 °C.

Influence of ZnO nanoparticles on the electric field induced birefringence of the Blue phase

We report the influence of a small concentration (0.1 wt%) of ZnO nanoparticles (NPs) on the birefringence of the liquid crystal Blue phase. The measurements carried out using the field-induced birefringence technique show that the inclusion of NP diminishes the magnitude of the Kerr constant. We propose that the field-induced disclination networks act as trapping centres for the NPs and enhance the elastic constant leading to a diminution in the birefringence.

NMR‐Based Cross‐Link Densities in EPDM and EPDM/ULDPE Blend Materials and Correlation with Mechanical Properties

AbstractThe role of cross‐linking in dictating the microstructural and mechanical properties in ethylene‐propylene‐diene‐monomer rubber (EPDM) and EPDM/ULDPE blends cross‐linked by different sulfur amounts is investigated by solid‐state1H time‐domain NMR spectroscopy and tensile‐tests. Analyses of spin‐spin relaxation time (T2), by combining free‐induction decay (FID), magic‐sandwich echo‐FID, and Hahn‐echo experiments demonstrate a reduction in crystal‐amorphous interface regions of pure ultralow‐density polyethylene (ULDPE) upon curative addition. The blends demonstrate a complete loss of these fractions due to curative‐induced plasticization and solvation by polyethylene segments of EPDM. Cross‐link densities, quantified by the magnitude of residual dipolar coupling constant (Dres), arising from topological restrictions to segmental motions, are measured by multiple‐quantum experiments. The entanglement‐dominated EPDMs demonstrate a significant reduction in ultimate tensile properties with increasingDres. The analogous blends yield similarDresvalues up to 0.36 phr of free sulfur. Thereafter, a deviation from the cross‐linking trend of the EPDMs is observed with the blends approaching a cross‐linking limit, thus emphasizing the migration of additives to the amorphous phase of the ULDPE. From the additional contributions of solvation and complex entanglement scenarios in the blends, restoration and even significant enhancement in ultimate tensile strength are achieved. Limitations in applying the popular Mooney–Rivlin analysis are also briefly discussed.

Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values

Studies are reported on the formation of low-spin six-coordinate [Fe(PPIX)L2] complexes from iron(II) protoporphyrin where L is one of a series of nitrogenous ligands (aliphatic, aromatic or heterocyclic). The bonding constants have been determined by titration of the metal complex with these ligands and are compared in relation to previous studies. The adduct formation was monitored utilising optical spectroscopy. In addition, Mӧssbauer spectroscopic experiments were conducted to monitor the electronic environment around the central iron atom in these complexes. The two complementary spectroscopic methods indicated that all nitrogen ligands formed low-spin octahedral complexes. The magnitude of the overall binding constants (β2 values) are discussed and related to (a) the pKa values of the free ligands and (b) the Mössbauer parameter ΔEQ, which represents the quadrupole splitting of the haem iron. The β2 and ΔEQ values are also discussed in terms of the structure of the ligand. Cooperative binding was observed for nearly all the ligands with Hill coefficients close to 2 for iron(II) protoporphyrin; one of these ligands displayed a much greater affinity than any we previously studied, and this was a direct consequence of the structure of the ligand. Overall conclusions on these and previous studies are drawn in terms of aliphatic ligands versus aromatic ring structures and the absence or presence of sterically hindered nitrogen atoms. The implications of the work for the greater understanding of haem proteins in general and in particular how the nitrogenous ligand binding results are relevant to and aid the understanding of the binding of inhibitor molecules to the cytochrome P450 mono-oxygenases (for therapeutic purposes) are also discussed.Graphical abstractChanges in the electronic absorption spectra of five-coordinate [Fe(II)(PPIX)(2-MeIm)] that occurred as the temperature was lowered from room temperature to 78° K

Interfacial Pockels Effect of Solvents with a Larger Static Dielectric Constant than Water and an Ionic Liquid on the Surface of a Transparent Oxide Electrode

The optical Pockels effect is a change in the refractive index proportional to an applied electric field. As a typical example of the interfacial Pockels effect occurring at interfaces where the spatial inversion symmetry is broken, it is known that water in the electric double layer (EDL) on the transparent oxide electrode surface has a large Pockels coefficient, but the physical factors that determine its size are not clear. Therefore, we experimentally studied the Pockels effect of water and other characteristic liquids—formamide (FA), methylformamide (NMF) (these two have larger static dielectric constants than water), dimethylformamide (DMF), and an ionic liquid that is itself salts (IL, [BMIM] [BF4])—and evaluated their Pockels coefficients in the EDL on the transparent electrode surface. The magnitude of the Pockels coefficient was found to be in the order of water, DMF, FA, NMF, and IL, with the magnitude of the static dielectric constant not being an important factor.

Horndeski-Proca stars with vector hair

We study Proca stars in a vector-tensor gravity model inspired by Horndeski's generalized Einstein-Maxwell field equations, supplemented with a mass term for the vector field. We discuss the effects of the non-minimal coupling term on the properties of the resulting Proca stars. %and show that they can form vector hair. We show that the sign of the coupling constant is crucial in determining the generic properties of these generalized Proca star solutions, as soon as the magnitude of the coupling constant is sufficiently large to allow for significant deviations from the standard Proca star case. For negative coupling constant we observe a new type of limiting behavior for the generalized Proca stars, where the spacetime splits into an interior region with matter fields and an exterior Schwarzschild region.