The European Physical Journal B最新文献

Rigorous, machine-checkable intervals for the critical exponents of the three-dimensional Ising universality class are established through a certificate-first methodology. Specifically, the objective is mathematical certainty for β, ν, η, and ω—rigorous enclosures rather than point estimates. This approach unifies conformal bootstrap, Borel-conformal resummation of perturbative and high-temperature series, and interval Monte Carlo under a single acceptance rule with machine-checkable certificates. Bootstrap islands for the leading operators are reconstructed using exact rational functionals, accompanied by feasibility or refutation logs, then mapped to exponents via exact scaling relations. Series expansions are resummed via Borel-conformal maps under explicit Gevrey control, yielding tail bounds and parameter boxes for rigorous enclosures. Monte Carlo outputs are enclosed using interval and ball arithmetic, combined with autocorrelation-aware concentration inequalities and finite-size scaling that incorporates verified crossings and sandwich fits. A topology-aware reconciliation enforces equality on overlaps and prevents cyclic tightening; acceptance requires unanimity across all anchors, subject to veto by any certified refutation. The main result is a theorem-level statement: the exponent set lies in the nonempty intersection of three independently certified boxes. The certified intervals are (upbeta in [text{0.32635,0.32650}]), (upnu in [text{0.62990,0.63005}]), (upeta in [text{0.03620,0.03640}]), and (upomega in [text{0.829,0.833}]) (closed, outward-rounded). These intervals match the sharpest values in the literature while providing solver-independent proofs and reproducible artifacts; they offer a transferable blueprint for other universality classes.

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Detection and adsorption behavior of the curcumin molecule on pristine boron nitride nanotube (BNNT) and transition metal (TM = Ti, Zr, Pd, and Pt)-doped (5,5) armchair BNNT was investigated using a density functional theory (DFT) analysis. Structural, energetic, and electronic properties of pristine and TM-doped BNNT, as well as their complexes with curcumin, were systematically investigated to assess their potential as drug delivery or sensing materials. The computed results display that the adsorption processes for all curcumin/BNNT and curcumin/TM-doped BNNT complexes are exothermic reaction. Two adsorption sites on the curcumin molecule were analyzed: the M site (central carbonyl and hydroxyl groups) and the H site (terminal phenolic OH and methoxy groups). Whereas pristine BNNT shows weak interactions at both sites, TM-doped BNNTs exhibit strong binding, particularly at the M site, in both gas and aqueous phases. A short adsorption distance and substantial charge transfer indicate a strong adsorption ability of the TM-doped BNNTs toward the curcumin molecule. The electronic structures of both pristine BNNT and TM-doped BNNTs are altered upon curcumin adsorption, as evidenced by changes in the energy gap, quantum molecular descriptors, and density of states plots. Therefore, the TM-doped BNNTs serve as a promising material for the delivery and sensing of curcumin molecule.

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The exploration of novel materials with half-metallic characteristics is essential for the advancement of both spintronic and thermoelectric technologies. In this study, we employ first-principles density functional theory to investigate the structural, electronic, magnetic, and thermoelectric properties of quaternary Heusler alloys LiXFeSb (X = Ba, Sr). Our calculations reveal that both the compounds crystallize in a stable type-I phase with F-43 m symmetry and exhibit ferromagnetic ground states, with total magnetic moments of 2.00 μB for LiBaFeSb and 1.99 μB for LiSrFeSb. The spin-resolved band structures confirm their half-metallic nature, with bandgaps of 0.47 eV (LiBaFeSb) and 0.2 eV (LiSrFeSb) in the up-spin channel and metallic character in the down-spin channel, resulting in 100% spin polarization. Importantly, thermoelectric analysis using the semi-classical Boltzmann transport theory and the Slack model shows that LiBaFeSb achieves a remarkable ZT ≈ 1.0 at 100 K in the up-spin channel, a rare feature for Heusler systems in the cryogenic regime. LiSrFeSb, on the other hand, exhibits ZT ≈ 0.63 at 800 K, demonstrating its potential at elevated temperatures. These results highlight the exceptional low-temperature thermoelectric efficiency and full spin polarization of LiBaFeSb, positioning the LiXFeSb family as a promising platform for multifunctional spin-caloritronic applications.

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Over the past decade, perovskite solar cells have garnered significant attention owing to their exceptional optoelectronic properties. The performance of perovskite solar cells is highly dependent on the efficient operation of both hole transport layers and electron transport layers, making the selection of cost-effective and compatible charge transport materials critically important. Phenyl-C₆₁-butyric acid methyl ester (PCBM) is widely utilized as an electron transport layer (ETL) in perovskite solar cells; however, several limitations persist, including low electron mobility, challenges in the deposition of uniform and high-quality films, and considerable interfacial recombination losses. In this study, potassium iodide (KI) doping of PCBM was investigated to enhance the photovoltaic parameters of perovskite solar cells. The incorporation of KI was found to enhance photovoltaic performance by optimizing surface morphology. Characterization techniques such as space charge limited current (SCLC) measurements confirmed a decrease in trap-state density within the perovskite layer, thereby mitigating charge recombination and contributing to improved device efficiency.

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Device fabrication under ambient air

High-temperature superconducting (HTS) magnets are promising in high-field applications. However, due to inevitable joint resistance, HTS magnets still face challenges in maintaining a persistent current in their closed-loop operation. HTS flux pumps are devices that can charge closed HTS magnets wirelessly in the way of electromagnetic coupling. Thus, high-capacity DC power supplies and thick resistive current leads, which are generally used for charging superconducting magnets, can be replaced by HTS flux pumps. Hence, on the one hand, the extra heat load caused by the resistive current leads are avoided, improving the safety operation of HTS magnets. On the other hand, the cost of charging HTS magnets can be reduced. In this review, published works about HTS flux pumps and dynamic resistance are summarized. These studies have laid a foundation for the follow-up researches of flux pumps applied in high-field HTS magnets.

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In this paper, we constructed a mathematical model of deep cellular crystal growth under anisotropic surface tension and anisotropic interface kinetics during directional solidification. Using the multivariate expansion method and the matched asymptotic expansion method, the dispersion relation of the rate of change of the perturbation amplitude at the deep cellular crystal interface and the quantization condition of the interface morphology are deduced, analyzed the stability of the growth of deep cellular crystal under the influence of anisotropic surface tension and anisotropic interface kinetics in the directional solidification, and revealed the influence of anisotropic parameters on the size of the unstable region. The results show that in the directional solidification considering anisotropic surface tension and anisotropic interface kinetics, there are two overall instability mechanisms for the morphology of deep cellular crystal growth interfaces: global oscillatory (GTW) instability and low-frequency (LF) instability. The stability analysis shows that the anisotropic surface tension and anisotropic interface kinetics have a significant effect on the global oscillatory instability mechanism in the low-order approximation. As the anisotropy parameter increases, the stable region of global oscillatory instability gradually expands. Relatively, the influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.

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These two images respectively depict the curves of the zeroth-order and first-order approximation GTW-S neutral modes under the influence of anisotropic surface tension parameters and anisotropic interface kinetics parameters. Comparison reveals that the critical stability parameter under the first-order approximation is smaller than that under the zeroth-order approximation. In both cases, the (n = 0) mode represents the most unstable state.

These two images display the curves of the first-order approximation GTW-S neutral modes for (n = 0). With increasing anisotropic parameters, the stable region associated with the overall oscillatory instability of highly oscillatory dendritic structures expands. The influence of the anisotropic interface kinetics parameter on the overall fluctuation instability of the interface morphology is more remarkable than the anisotropic surface tension parameter.

Single crystals of Piperazinium Nitrate were obtained by slow evaporation, crystallizing in a monoclinic system (P2₁/c), and stabilized by strong N–H···O hydrogen bonds in a three-dimensional network. structural integrity of the grown crystal was confirmed by X-ray diffraction (XRD) analysis. Experimental characterization using FT–IR and FT–Raman spectroscopy confirmed the presence of functional groups and characteristic vibrational modes corresponding to the molecular structure. Hirshfeld surface (HS) analysis and 2D fingerprint plots quantified the intermolecular contacts, highlighting the dominant role of hydrogen bonding in crystal packing and structural stability. HS analysis revealed that O···H interactions contribute 54.9% of the overall intermolecular contacts, confirming the dominance of hydrogen bonding in the crystal packing. Density Functional Theory (DFT) calculations at the B3LYP/6-311G (d, p) level were performed to optimize the molecular geometry and investigate the electronic structure, revealing a significant HOMO–LUMO energy gap of 5.391 eV, denoting the stability of molecule and low chemical reactivity. Time-Dependent DFT (TD-DFT) simulations of the UV–Visible (UV–Vis) spectrum provided insights into the electronic excitation behavior. The absorption peak at 255.76 nm, it exhibits the π → π* and n → π* electronic transitions in gas phase. Natural Bond Orbital (NBO) analysis indicated a strong intramolecular hyperconjugative interaction between the lone pair on LP(3) O₂ and antibonding orbital of the N1–O4 bond, contributing 144.41 kJ mol⁻¹ to molecular stabilization. Fukui function analysis identified the reactive sites susceptible to electrophilic and nucleophilic attack. Electron Localization Function (ELF) and Localized Orbital Locator (LOL) maps illustrated regions of electron localization and delocalization. Non-Covalent Interaction (NCI) analysis based on Reduced Density Gradient (RDG) plots revealed the presence of weak van der Waals forces and strong hydrogen bonding interactions. The calculated first-order hyperpolarizability (29.244 × 10⁻³¹ esu), which is 7.8 times greater than that of urea, and the calculated first-order hyperpolarizability confirms the strong NLO response and highlights the potential of the compound for nonlinear optical (NLO) and photonic applications.

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