Higher Moments Research Articles

Ab initio prediction of coexistence of two magnetic states in Mn[formula omitted]Sn ([formula omitted]Sc, Ti, and V) Heusler alloys under applied pressure

The structural, magnetic and electronic properties of Mn2YSn (Y=Sc, Ti, and V) Heusler alloys under applied hydrostatic pressure are studied by the first-principle calculations and Monte Carlo simulations. We find that two magnetic reference states with low and high magnetic moment at the low and high crystal lattice volume, respectively, can coexist together due to the almost equal energy under applied pressure of 3.4, −2.9 and −3.25 GPa for Mn2ScSn, Mn2TiSn, and Mn2VSn, correspondingly. The positive/negative pressure correspond to the uniform lattice contraction/expansion. We show that for all compounds, the low magnetic state (LMS) is characterized by the almost half-metallic behavior and it is maintained against hydrostatic pressure. However, the electronic structure of the high magnetic state (HMS) takes on a metallic character. For HMS, the magnetic exchange parameters and Curie temperatures are found to be sufficiently larger values as compared to those of LMS. To identify stable phases at given pressures, the phase diagrams are constructed. The pressure-induced switching mechanism between almost half-metallic and metallic states with different magnetization is proposed.

Insight into Anion-Solvent Interactions to Boost Stable Operation of the Ether-Based Electrolytes in Pure-SiOx||LiNi0.8Mn0.1Co0.1O2 Full Cells.

Ether solvents with superior reductive stability promise excellent interphasial stability with high-capacity anodes while the limited oxidative resistance hinders their high-voltage operation. Extending the intrinsic electrochemical stability of ether-based electrolytes to construct stable-cycling high-energy-density lithium-ion batteries is challenging but rewarding. Herein, the anion-solvent interactions were concerned as the key point to optimize the anodic stability of ether-based electrolytes and an optimized interphase was realized on both pure-SiOx anodes and LiNi0.8Co0.1Mn0.1O2 cathodes. Specifically, the small-anion-size LiNO3 and tetrahydrofuran with high dipole moment to dielectric constant ratio realized strengthened anion-solvent interactions, which enhanced the oxidative stability of the electrolyte. The designed ether-based electrolyte enabled a stable cycling performance over 500 cycles (capacity retention of 81.7%) in pure-SiOx||LiNi0.8Co0.1Mn0.1O2 full cell, demonstrating its superior practical prospects. This work provides new insight into the design of advanced electrolytes for emerging high-energy-density lithium-ion batteries through the regulation of interactions between species in the electrolytes.

Insights into Anion‐Solvent Interactions to Boost Stable Operation of Ether‐Based Electrolytes in Pure‐SiOx||LiNi0.8Mn0.1Co0.1O2 Full Cells

AbstractEther solvents with superior reductive stability promise excellent interphasial stability with high‐capacity anodes while the limited oxidative resistance hinders their high‐voltage operation. Extending the intrinsic electrochemical stability of ether‐based electrolytes to construct stable‐cycling high‐energy‐density lithium‐ion batteries is challenging but rewarding. Herein, the anion‐solvent interactions were concerned as the key point to optimize the anodic stability of the ether‐based electrolytes and an optimized interphase was realized on both pure‐SiOx anodes and LiNi0.8Mn0.1Co0.1O2 cathodes. Specifically, the small‐anion‐size LiNO3 and tetrahydrofuran with high dipole moment to dielectric constant ratio realized strengthened anion‐solvent interactions, which enhance the oxidative stability of the electrolyte. The designed ether‐based electrolyte enabled a stable cycling performance over 500 cycles in pure‐SiOx||LiNi0.8Mn0.1Co0.1O2 full cell, demonstrating its superior practical prospects. This work provides new insight into the design of new electrolytes for emerging high‐energy density lithium‐ion batteries through the regulation of interactions between species in electrolytes.

Analysis of methods for calculating the stability of cellular structures

Introduction. Cellular structures are widely used in world practice to solve various problems. By means of such structures mooring and barrier constructions, and also the cofferdams are erected which allow to drain territory below a water level for the subsequent construction of the main structures on dry land. In domestic practice, these structures are often made of sheet piling profiles with high moment of inertia and moment of resistance as a part of anchored or interanchored thin walls. This design solution requires heavy-duty sheet piling sections and heavy anchoring devices at considerable water depths, which increases the steel intensity of the structure. For temporary structures the material and labor-intensive nature of the structure is undesirable. The honeycomb construction consists of flat sheet piles with cavities filled with soil.
 
 Materials and methods. Various stability tests of the cellular structure variant have been carried out in accordance with the current regulatory documents; recommendations for the design of these structures by the European company ArcelorMittal, which has extensive experience in designing realized projects of structures using this technical solution, have also been used. The stability indicator results are compared with the results of finite-element model calculations performed in the MIDAS FEA NX calculation complex.
 
 Results. Based on the calculation of a three-dimensional model of a cellular structure, a comparison was made with analytical methods for calculating stability. The analytical calculation of stability according to the deep shear scheme in accordance with current regulations has both a close convergence of the stability coefficient and a potential buckling surface in comparison with the FEM problem in a three-dimensional formulation.
 
 Conclusions. The main limiting factor in calculations of stability of cellular structures is the stability coefficient according to the scheme of deep shear.

Gadolinyum(III) Asetat İçeren Yeni Tetrapirazinoporfirazinin Sentezi ve Spektroskopik Özellikleri

A new tetrakis-(2-methylpyrazino)porphyrazinato gadolinium(III) acetate complex was synthesized. Elemental analysis, Fourier-Transform Infrared, Ultraviolet-visible, and fluorescence spectroscopy techniques clarified its structure. It can dissolve very well without aggregation in both Dimethyl sulfoxide and N, N-Dimethylformamide, which have high dielectric constant and high dipole moment from polar aprotic solvent type. Its aggregation property was also investigated in dimethyl sulfoxide at different concentrations, and it was determined to contain monomeric species. In addition, its fluorescence properties were investigated in Dimethyl sulfoxide and the effect of gadolinium(III) acetate metal ion as a heavy rare earth element was determined. According to the findings in this study, it may be used as an electronic and optical material and in various technological applications such as photocatalytic applications. In addition, these findings may be useful for systems that include changes in pyrazinoporphyrazine-like forms.

Measurement and calculation of CO (7-0) overtone line intensities.

Intensities of 14 lines in the sixth overtone (7-0) band of carbon monoxide (12C16O) are measured in the visible range between 14300 and 14500 cm-1 using a frequency-stabilized cavity ring-down spectrometer. This is the first observation of such a high and weak overtone spectrum of the CO molecule. A theoretical model is constructed and tested based on the use of a high accuracy abinitio dipole moment curve and a semi-empirical potential energy curve. Accurate studies of high overtone transitions provide a challenge to both experiment and theory as the lines are very weak: below 2 × 10-29cmmolecule-1 at 296K. Agreement between theory and experiment within the experimental uncertainty of a few percent is obtained. However, this agreement is only achieved after issues with the stability of the Davidson correction to the multi-reference configuration interaction calculations are addressed.

Carboxylated Poly (p-Phenylene Terephthalamide) Reinforced Polyetherimide for High-Temperature Dielectric Energy Storage.

Dielectric energy storage polymers play a vital role in advanced electronics and electrical systems, due to their high breakdown strength, excellent reliability, and easy fabrication. However, the low dielectric constant and poor thermal resistance of dielectric polymers limit their energy storage density and working temperatures, making them less versatile for broader applications. In this work, a novel carboxylated poly (p-phenylene terephthalamide) (c-PPTA) is synthesized and employed to simultaneously enhance the dielectric constant and thermal resistance of polyetherimide (PEI), leading to a discharged energy density of 6.4 J cm-3 at 150 °C. The introduction of c-PPTA molecules effectively reduces the ΠΠ stacking effect and increases the average chain spacing between polymer molecules, which is conducive to improving the dielectric constant. Additionally, c-PPTA molecules with stronger positive charges and high dipole moments can capture electrons, resulting in reduced conduction loss and enhanced breakdown strength at high temperatures. The coiled capacitor fabricated with the PEI/c-PPTA film exhibits superior capacitance performances and higher working temperatures compared to commercial metalized PP capacitors, demonstrating great potential for dielectric polymers in high-temperature electronic and electrical energy storage systems.

A general framework for removing point-spread function additive systematics in cosmological weak lensing analysis

ABSTRACT Cosmological weak lensing measurements rely on a precise measurement of the shear two-point correlation function (2PCF) along with a deep understanding of systematics that affect it. In this work, we demonstrate a general framework for detecting and modelling the impact of PSF systematics on the cosmic shear 2PCF and mitigating its impact on cosmological analysis. Our framework can detect PSF leakage and modelling error from all spin-2 quantities contributed by the PSF second and higher moments, rather than just the second moments, using the cross-correlations between galaxy shapes and PSF moments. We interpret null tests using the HSC Year 3 (Y3) catalogs with this formalism and find that leakage from the spin-2 combination of PSF fourth moments is the leading contributor to additive shear systematics, with total contamination that is an order-of-magnitude higher than that contributed by PSF second moments alone. We conducted a mock cosmic shear analysis for HSC Y3 and find that, if uncorrected, PSF systematics can bias the cosmological parameters Ωm and S8 by ∼0.3σ. The traditional second moment-based model can only correct for a 0.1σ bias, leaving the contamination largely uncorrected. We conclude it is necessary to model both PSF second and fourth moment contaminations for HSC Y3 cosmic shear analysis. We also reanalyse the HSC Y1 cosmic shear analysis with our updated systematics model and identify a 0.07σ bias on Ωm when using the more restricted second moment model from the original analysis. We demonstrate how to self-consistently use the method in both real space and Fourier space, assess shear systematics in tomographic bins, and test for PSF model overfitting.

High Orbital‐Moment Cooper Pairs by Crystalline Symmetry Breaking

AbstractThe pairing structure of superconducting materials is regulated by the point group symmetries of the crystal. The spin‐singlet multiorbital superconductivity of materials with unusually low crystalline symmetry content can host even‐parity (s‐wave) Cooper pairs with high orbital moment. The lack of mirror and rotation symmetries makes pairing states with quintet orbital angular momentum symmetry‐allowed. A remarkable fingerprint of this type of pairing state is provided by a nontrivial superconducting phase texture in momentum space with π‐shifted domains and walls with anomalous phase winding. The pattern of the quintet pairing texture is shown to depend on the orientation of the orbital polarization and the strength of the mirror and/or rotation symmetry breaking terms. Such a momentum dependent phase makes Cooper pairs with net orbital component suited to design orbitronic Josephson effects. This study discusses how an intrinsic orbital dependent phase can set out anomalous Josephson couplings by employing superconducting leads with nonequivalent breaking of crystalline symmetry.

Magnetic and Magnetocaloric Properties of the A2LnSbO6 Lanthanide Oxides on the Frustrated fcc Lattice.

Frustrated lanthanide oxides are promising candidates for cryogen-free magnetic refrigeration due to their suppressed ordering temperatures and high magnetic moments. While much attention has been paid to the garnet and pyrochlore lattices, the magnetocaloric effect in frustrated face-centered cubic (fcc) lattices remains relatively unexplored. We previously showed that the frustrated fcc double perovskite Ba2GdSbO6 is a top-performing magnetocaloric material (per mol Gd) because of its small nearest-neighbor interaction between spins. Here we investigate different tuning parameters to maximize the magnetocaloric effect in the family of fcc lanthanide oxides, A2LnSbO6 (A = {Ba2+, Sr2+} and Ln = {Nd3+, Tb3+, Gd3+, Ho3+, Dy3+, Er3+}), including chemical pressure via the A site cation and the magnetic ground state via the lanthanide ion. Bulk magnetic measurements indicate a possible trend between magnetic short-range fluctuations and the field-temperature phase space of the magnetocaloric effect, determined by whether an ion is a Kramers or a non-Kramers ion. We report for the first time on the synthesis and magnetic characterization of the Ca2LnSbO6 series with tunable site disorder that can be used to control the deviations from Curie-Weiss behavior. Taken together, these results suggest fcc lanthanide oxides as tunable systems for magnetocaloric design.

Zwitterions Functionalized by Optical Cycling Centers: Toward Laser-Coolable Polyatomic Molecular Cations.

Functionalization of large aromatic compounds and biomolecules with optical cycling centers (OCC) is of considerable interest for the design and engineering of molecules with a highly selective optical photoresponse. Both internal and external dynamics in such molecules can be precisely controlled by lasers, enabling their efficient cooling and opening up broad prospects for high-precision spectroscopy, ultracold chemistry, enantiomer separation, and various other fields. The way the OCC is bonded to a molecular ligand is crucial to the optical properties of the OCC, first of all, for the degree of closure of the optical cycling loop. Here we introduce a novel type of functionalized molecular cation where a positively charged OCC is bonded to various organic zwitterions with a particularly high permanent dipole moment. We consider strontium(I) complexes with betaine and other zwitterionic ligands and show the possibility of creating efficient and highly closed population cycling for dipole-allowed optical transitions in such complexes.

Advancing optoelectronic performance of organic solar cells: Computational modeling of non-fullerene donor based on end-capped triphenyldiamine (TPDA) molecules

In this study, quantum chemical and density functional theory (DFT) methods were used to investigate triphenyldiamine-based molecules for enhancing organic solar cells (OSCs). A reference molecule (XSln84) [(E)-2′-methoxy-N4,N4,N4″,N4″-tetrakis(4-methoxyphenyl)-5′-(4-methoxystyryl)-[1,1′:3′,1″-terphenyl]-4,4″-diamine)] and six modified molecules (A1 to A6) were analyzed. The molecular properties of these molecules were thoroughly investigated, including maximum absorption wavelength (λmax), frontier molecular orbitals (FMO), and quantum chemical parameters. A4 showed excellent miscibility, highest absorption wavelength, small energy gap, and high dipole moment in dichloromethane DCM solvent. Compared to the reference molecule, all modified molecules exhibited higher estimated open-circuit voltage (VOC) and remarkable power conversion efficiency (PCE), with A5 having the highest PCE. A3 had the highest electron mobility, while A6 showed the highest hole mobility. The end-capped modifications improved the optoelectronic properties, suggesting potential for efficient OSCs. These findings contribute to understanding these molecules and their renewable energy applications, benefiting the field of organic solar cells.

Structure and Bonding Patterns in C5H4 Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules

We have theoretically investigated nine unusual isomers of the molecular formula C5H4 using coupled cluster (CC) and density functional theory (DFT) methods. These molecules possess non-classical structures consisting of two pyramidanes, three planar tetracoordinate carbon (ptC), and four spiro types of isomers. Both the pyramidanes (tetracyclo-[2.1.0.01,3.02,5]pentane; py-1 and tricyclo-[2.1.0.02,5]pentan-3-ylidene; py-2) are minima on the potential energy surface (PES) of C5H4. Among the three isomers containing ptC, (SP4)-spiro [2.2]pent-1-yne (ptC-2) is a minimum, whereas isomer, (SP4)-spiro [2.2]pent-1,4-diene (ptC-1) is a fourth-order saddle point, and (SP4)-sprio[2.2]pent-1,4-diylidene (ptC-3) is a transition state. The corresponding spiro isomers spiro[2.2]pent-1,4-diene (spiro-1), sprio[2.2]pent-1,4-diylidene (spiro-3) and spiro[2.2]pent-4-en-1-ylidene (spiro-4) are local minima, except spiro[2.2]pent-1-yne (spiro-2), which is a second-order saddle point. All relative energies are calculated with respect to the global minimum (pent-1,3-diyne; 1) at the CCSD(T)/cc-pVTZ level of theory. Quantum chemical calculations have been performed to analyze the bonding and topological configurations for all these nine isomers at the B3LYP/6-311+G(d,p) level of theory for a better understanding of their corresponding electronic structures. ptC-2 was found to be thermodynamically more stable than its corresponding spiro counterpart (spiro-2) and possesses a high dipole moment (μ = 4.64 D). The stability of the ptC structures with their higher spin states has been discussed.

Construction of spontaneously polarized ceramic via synergistic mechanical activation‒Biomimetic mineralization for activating air and water

Spontaneously polarized crystals with intrinsic electric dipole moment have attracted immense interest as excellent functional materials for extensive applications. It is of great significance to engineer sustainable spontaneously polarized materials with fascinating characteristics and performance for activating air and water. Herein, a novel strategy based on the synergy of mechanical activation (MA) and biomimetic mineralization (BM) was created to construct spontaneously polarized ceramic. MA induced the structural damage of clay and promoted the dissolution of ions and the release of free proteins, contributing to the formation of silicate precursor in BM process. After high temperature firing, the silicate precursor in clay was converted to form KCa3AlCa3Si4O16 (hexagonal crystal system, L6 symmetry type, and P63 space group) in the resulting spontaneously polarized ceramic. The non-centrosymmetric structure of KCa3AlCa3Si4O16 and the high intrinsic electric dipole moments contributed by K(1) polyhedrons resulted in high spontaneous polarization (0.2322 μC/cm2) and far-infrared emissivity (0.951) of spontaneously polarized ceramic. In air, spontaneously polarized ceramic can activate H2O and O2 molecules to form negative air ions owing to surface electric field. In water, spontaneously polarized ceramic can disaggregate large water clusters to form small water clusters ascribed to surface electric field and far-infrared emission; water pH can be regulated from weak acidity to approximate neutrality via the capture of electrons by H+ ions to produce releasable hydrogen gas. This work provides great promise for rational design and synthesis of spontaneously polarized materials for functional applications.

A structural characterization of compactly supported OEP-based balanced dual multiframelets

Compared to scalar framelets, multiframelets have certain advantages, such as relatively smaller supports on generators, high vanishing moments, etc. The balancing property of multiframelets is very desired, as it reflects how efficient vector-valued data can be processed under the corresponding discrete multiframelet transform. Most of the literature studying balanced multiframelets is from the point of view of the function setting, but very few approaches are from the aspect of multiframelet filter banks. In this paper, we study structural characterizations of balanced dual multiframelets from the point of view of the Oblique Extension Principle (OEP). The OEP naturally connects framelets with filter banks, which makes it a very handy tool for analyzing the properties of framelets. With the OEP, we shall characterize compactly supported balanced dual multiframelets through the concept of balanced moment correction filters, which is the key notion that will be introduced in our investigation. The results of this paper demonstrate what essential structures a balanced dual multiframelet has in the most general setting, and bring us a more complete picture to understand balanced multiframelets and their underlying discrete multiframelet transforms.

Improving Hoeffding’s inequality using higher moments information

In this paper, we generalize and improve Hoeffding’s inequality using information on the random variables’ first p moments for any fixed integer p. Importantly, our generalized Hoeffding’s inequality is tighter than Hoeffding’s inequality and is given in a simple closed-form expression for any fixed integer p. Hence, the generalized Hoeffding’s inequality is easy to use in applications. To prove our results, we derive novel upper bounds on the moment-generating function of a random variable that depend on the random variable’s first p moments and show that these bounds satisfy appropriate convexity properties. We demonstrate the usefulness of the generalized Hoeffding’s inequality in obtaining refined confidence intervals when there is some information on the random variables’ high moments.

A stochastic analysis of hedge funds’ higher moments

Utilizing hedge fund data, we investigate the mobility properties of higher moments both individually and jointly. Using a Markov chain model, we estimate, for the first time, transition matrices for the sector and by investment strategy, describing the probabilistic structure of Skewness, Kurtosis and Joint transitions. We further apply various indices to provide the anatomy of the dynamics. Additionally, we estimate three Probit models as a validation tool. We find a near perfect mobility toward Nonnormality across the investment strategies and the sector as a whole, for both higher moments and their joint movement. Only a limited number of investment strategies are capable of maintaining Normality for consecutive periods in the joint framework, while mobility indices confirm the findings of the transition matrices.

Особливості дослідження деформаційної поведінки матеріалів при випробуваннях на згин

The application of bending tests is due to the widespread use of this load scheme in real operating conditions and its greater softness compared to tensile strength. This makes it possible to assess the properties of materials that are brittle when tensile. Bending tests are convenient for estimating the transition temperatures from brittle to plastic (for example, in cold-brittle BCC metals and intermetallics). The issue of determining the elastic characteristics, in particular the measurement of deflections, needs to be clarified. The aim of this work is to improve experimental methods for determining the characteristics of elasticity, in particular to determine the ratio of movement of internal rollers relative to external and deflection between internal rollers, as well as accurate determination of absolute deformation of the test machine depending on load. To obtain the deformation curve of the sample without the deflection meter, a method of subtracting from the total load curve the yield curve of the test machine, which can be obtained after testing the sample with a high axial moment of inertia to minimize its deflection. To test this technique, a ceramic sample based on Al2O3 was tested. After the adjustments, it was found that the modulus of elasticity was 371.3 GPa, which corresponds to the tabular values. The proposed technique allows to accurately measure the modulus of elasticity and obtain curves of microdeformation of low-plastic materials at different test temperatures in the absence of a deflector. The deflection of the central part of the sample relative to the inner rollers by four-point bending is 3/8 of the movement of the inner rollers relative to the outer ones. The improved method of determining the deflections allows to obtain diagrams of deformation of the samples without the deflection meter, as well as to measure the modulus of elasticity and obtain curves of microdeformation of low-plastic materials at different test temperatures. Comparison of the results of determining the modulus of elasticity by methods without a deflector and with it allows you to assess the accuracy of measuring the modulus of elasticity. It is experimentally established that the difference between the values of the Young's modules calculated by the proposed method and the corresponding values calculated taking into account the directly measured deflections does not exceed 1%. Keywords: bending, stress, deformation, deflection, angle of rotation, radius of curvature, axial moment of inertia, deflection meter.

Cd113 β -decay spectrum and gA quenching using spectral moments

We present an alternative analysis of the $^{113}\mathrm{Cd}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay electron energy spectrum in terms of spectral moments ${\ensuremath{\mu}}_{n}$, corresponding to the averaged values of $n\mathrm{th}$ powers of the $\ensuremath{\beta}$ particle energy. The zeroth moment ${\ensuremath{\mu}}_{0}$ is related to the decay rate, while higher moments ${\ensuremath{\mu}}_{n}$ are related to the spectrum shape. The here advocated spectral-moment method (SMM) allows for a complementary understanding of previous results, obtained using the so-called spectrum-shape method (SSM) and its revised version, in terms of two free parameters: $r={g}_{\mathrm{A}}/{g}_{\mathrm{V}}$ (the ratio of axial-vector to vector couplings) and $s$ (the small vectorlike relativistic nuclear matrix element, $s$-NME). We present numerical results for three different nuclear models with the conserved vector current hypothesis (CVC) assumption of ${g}_{\mathrm{V}}=1$. We show that most of the spectral information can be captured by the first few moments, which are simple quadratic forms (conic sections) in the $(r,\phantom{\rule{0.16em}{0ex}}s)$ plane: An ellipse for $n=0$ and hyperbolas for $n\ensuremath{\ge}1$, all being nearly degenerate as a result of cancellations among nuclear matrix elements. The intersections of these curves, as obtained by equating theoretical and experimental values of ${\ensuremath{\mu}}_{n}$, identify the favored values of $(r,\phantom{\rule{0.16em}{0ex}}s)$ at a glance, without performing detailed fits. In particular, we find that values around $r\ensuremath{\approx}1$ and $s\ensuremath{\approx}1.6$ are consistently favored in each nuclear model, confirming the evidence for ${g}_{\mathrm{A}}$ quenching in $^{113}\mathrm{Cd}$, and shedding light on the role of the $s$-NME. We briefly discuss future applications of the SMM to other forbidden $\ensuremath{\beta}$-decay spectra sensitive to ${g}_{\mathrm{A}}$.

Price‐endogenous technology, producer welfare, and ex ante impact assessment: The case of industrial hemp

AbstractThe emerging hemp industry is an example of an important class of agricultural products where the market extent is limited, in hemp's case by laws and regulations, causing technology adoption to interact through prices with market‐level equilibrium. In this paper, we show that the equilibrium adoption rate and producer welfare impact of new technology, such as improved hemp genetics and management, are determined by the interaction between market prices and the spatial distribution of returns of both current and new technologies in the farm population. Price changes affect adoption and welfare through shifts in both the location (mean) and dispersion (variance and higher moments) of the spatial distribution of gains to the new technology. We show that an output price change may either increase or decrease the adoption rate of a new technology and in turn impact the elasticity of the market supply function. Additionally, we derive market‐equilibrium measures of welfare change for both adopters and non‐adopters and show how these welfare measures are affected by the spatial distribution of returns to a new technology. Our finding suggests that the interplay between new technologies and price changes is likely to have empirically important effects on regional supply and farm welfare.