物理最新文献

The innovation in energy storage technology is crucial to solving the world’s energy problems. Renewable resources have drawn the interest of researchers because the non-renewable resources are limited. Supercapacitors are revolutionary storage and energy conversion devices that are gaining popularity due to their higher specific power. The present study is about the fabrication of CaFeO₃ and Mo-doped CaFeO₃ through sustainable hydrothermal technique. To verify its electrochemical properties, different techniques were used, including charge-discharge as well as electrochemical surface area. The capacitance of the resulting Mo-doped CaFeO₃ material is 1722.5 F/g, which is greater than that of the CaFeO₃ material with capacitance of 897.8 F/g. The produced Mo-doped CaFeO₃ material has 237.5 W/kg of specific power and 54.1 Wh/kg of specific energy. The produced CaFeO₃ doped with Mo showed remarkable retention after undergoing 5000^th cycle. The electrochemical performance and the specific surface area of pure material was improved by doping. The results showed that the doped material’s electrochemical activity was enhanced and charges were stored more effectively than the pure material. The exceptional performance of Mo-doped CaFeO₃ nanomaterial indicates their significant potential for future energy storage technology.

Double perovskite system LaPrCo_1 − xFe_xMnO₆; (x = 0.2, 0.5, 0.8 and 1.0) was developed by sol-gel method and its structural, microstructural, optical as well as electrical properties were investigated. X-Ray Diffraction analysis inveterate the phase formation with monoclinic structure (P2₁/n) as well as a slight shifting of diffraction peaks towards left is noticed with substitution of Fe³⁺ for Co²⁺. The crystallite size as well as strain, both exhibited similar tendency with x and varies from 506 Å to 1100 Å and 0.94 × 10^− 3 to 1.87 × 10^− 3, respectively and both the parameters showed their maximum value for x = 0.5 composition. Field Emission Scanning Electron Microscopy study divulged that mean grain size is of micrometre order (1.27 to 1.96 μm, maximum for x = 0.5) and EDX analysis confirmed the availability of all anticipated elements. High Resolution Transmission Electron Microscopy with Selected Area Electron Diffraction (SAED) pattern confirmed the crystallinity as well as purity of prepared system with inter-planar spacing 0.286 nm for x = 0.2 composition. X-Ray Photoelectron Spectroscopy analysis inveterate coexistence of various oxidation states of transition metal cations such as + 2/+3 for cobalt and iron whereas + 3/+4 for manganese. Ultra Violet-Visible-Near Infrared (UV-Vis-NIR) reflectance spectra inveterate semiconductor type band gap of ~ 2 eV with a maximum optical band gap of 2.13 eV for x = 0.5 composition. DC conductivity analysis suggested semiconducting behaviour and followed both thermal activation and variable range hopping conduction mechanisms. Three different slopes in Arrhenius plot with distinct activation energies inveterate the presence of electronic as well as ionic conduction. DC conductivity decreased initially with Fe substitution, afterwards displayed increasing behaviour up to x = 0.8, and then again decreased for x = 1.0. The decrease in DC conductivity suggested weakening of double-exchange interactions due to decrease in ratio of Mn³⁺/Mn⁴⁺ (and Co²⁺/Co³⁺) on substitution of Fe³⁺ for Co²⁺. The synthesized LaPrCo_1 − xFe_xMnO₆ system displayed good electronic/ionic conductivity, making it apposite for electrochemical devices.

We propose a method which allows the inclusion of exclusive heavy vector-meson production data at low x in future global parton analyses. As an example we perform a study within xFitter to determine the gluon parton distribution function (PDF) at next-to-leading order (NLO) at moderate-to-low x using the measurements of exclusive (J/psi ) production in ep and pp collisions from HERA and LHC. We further study the constraints from the corresponding (Upsilon ) production process. We finish by discussing the possible effects at next-to-next-to-leading order (NNLO) through incorporation of a K factor for the exclusive heavy vector-meson coefficient function at NLO.

This study explores the synthesis and structural transformation of Ba-doped SrFeO_3−δ exhibiting interesting electronic and magnetic properties. These samples with the general formula Sr_1 − xBa_xFeO_3−δ (x = 0, 0.1, 0.15, 0.2) were prepared using the citrate auto-combustion method. X-ray diffraction analysis, complemented by Rietveld refinement, confirmed the formation of single-phase cubic structure with space group Pm-3 m for the undoped sample. However, the introduction of larger-radii Ba²⁺ ions caused lattice distortion, leading to symmetry reduction into the P1 space group. The impact of Ba doping on grain size evolution was further examined using field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The stretching vibrational mode of Fe-O at 600 cm⁻¹ supported the presence of an octahedral coordination. Room-temperature Mössbauer spectroscopy provided insights into the Fe⁴⁺/Fe³⁺ ratio and corroborated the structural transformation. Among the synthesized samples, Sr_0.8Ba_0.2FeO_3−δ demonstrated the highest magnetization (M_s=1.102 emu/g, M_r=0.026 emu/g) and enhanced ferroelectric properties (0.1 µC/cm²). These findings highlight the inherent flexibility of its perovskite structure, allowing for precise tuning and optimization of its functional properties.

This study used two-step sintering to prepare lead-free (1–x)[(K_0.48Na_0.48Li_0.04)(Nb_0.95Sb_0.05)O₃]– xBaZrO₃ [(1–x)KNNST–xBZ] ceramic samples with x = 0.0, 0.015, 0.03, 0.045, and 0.060. The influence of the content of BaZrO₃ (BZ) on the structure, microstructure, and physical properties of the (K_0.48Na_0.48Li_0.04)(Nb_0.95Sb_0.05)O₃ (KNLNS) ceramic was studied in detail. Experimental results showed that the KNLNS crystal structure transformed from the orthorhombic phase to a rhombohedral phase to construct the new phase boundary near room temperature for 0.03 ≤ x ≤0.045, improving the electrical properties of the ceramic at the optimized BZ content. Raman scattering, X-ray diffraction, scanning electron microscopy, and the electrical properties of the samples showed that the optimal BZ content was 0.03 mol, corresponding to the solubility limit of Ba²⁺ and Zr⁴⁺ ions in the KNLNS ceramics. Furthermore, substituting Ba²⁺ and Zr⁴⁺ at the A- and B-site induced lattice distortion in the (1–x)KNLNS– xBZ structure to increase the relaxation behavior and decrease the T_O−T values sharply to 45 °C, which was the optimum poling condition that could develop the possible piezoelectric properties. At the optimized BZ content of 0.03 mol, the 0.97KNNST– 0.03BZ ceramic had the best electrical properties: density = 4.56 g/cm³, dielectric constant (ε_r) = 1130, electromechanical coupling factors k_p = 0.39 and k_t = 0.40, piezoelectric constant (d₃₃) = 225 pC/N, remanent polarization (P_r) = 15.2 µC/cm², and normalized strain (d₃₃^*) = 470 pm/V. The highest Q_m value of 102 was for 0.045 mol BZ.

The deuteron is the lightest spin-1 nucleus, consisting of a weakly bound system of two spin-(frac{1}{2}) nucleons. One intriguing characteristic of the deuteron is the tensor polarized structure, which cannot be naively constructed combining the proton and neutron structure. The tensor structure of the deuteron provides unique insights into the quarks and gluons distributions and their dynamics within the nucleus. It can be studied experimentally through inclusive and semi-inclusive Deep Inelastic Scattering (DIS) of electrons on tensor polarized deuterons. One-dimensional (longitudinal-momentum-dependent) tensor structure functions are extracted from the inclusive DIS, whereas three-dimensional with additional transverse-momentum-dependent tensor structure functions are extracted from the semi-inclusive DIS. Experimentally, achieving high tensor polarization for such measurements has been a challenge. Significant progress has recently been made in enhancing the tensor polarization for polarized deuteron target, opening up a new window for experimental studies of the deuteron tensor structure. In this article, we discuss the tensor structure functions of the deuteron and the experimental schemes to extract these functions at Jefferson Lab, highlighting the potential measurements of the transverse-momentum-dependent tensor structure functions.

In this study, we have introduced a new multivariate regression model to solve the inverse problem in microwave characterization of dielectric materials. The probe is an open-ended coaxial line, whereas the dielectric sample is taken at its end. The relative dielectric permittivity (ε = ε'-jε'') is calculated from the measurements of the probe admittance on a broad band frequency (f from 1 MHz to 1.8 GHz). In order to fit the regression coefficients of the Multiple Linear Regression (MLR) model (inverse problem), a data set is generated by solving the direct problem for the probe admittance (Y(f) = G(f) + jB(f)) using Finite Elements Method (FEM). Unfortunately, the MLR model with the original three descriptors (f, G and B) as X bloc and ε' or ε'' as response (Y bloc) has given very bad results. In order to integrate the nonlinearity between inputs and output, more descriptors have been generated mathematically from the original ones (for example: 1/f, B/f², fB, 1/B, G/f, f²G/B, fG²B, f²GB², … etc.) using the extended X bloc method and the Multiple Non-Linear Regression (MNLR) model is created. In order to choose the most relevant or statistically significant descriptors, stepwise selection is adopted. Inversion results of experimental measurements on an ethanol sample have proved that the dielectric permittivity can be measured with excellent accuracy using MNLR as inversion tool.

Metal-organic frameworks (MOFs) have emerged as promising catalysts for the oxygen evolution reaction (OER) in water electrolysis. This study synthesizes a nickel-based MOF on a nickel foam substrate (NiMOF/NF) via a solvothermal method and fabricates NiMOF-FeOOH/NF composites through Fe electrodeposition. The NiMOF-FeOOH₆₀₀/NF composite, prepared with a 600 s electrodeposition time, exhibits an overpotential of 320 mV at 20 mA·cm^-2 and a Tafel slope of 126 mV·dec^-1. Compared to unmodified NiMOF/NF, the overpotential was reduced by 320 mV and the Tafel slope by 146 mV dec^-1. In addition, no significant performance degradation was observed during the 40 h stability test. Further results demonstrated that deposition of Fe ions significantly improved the intrinsic conductivity of NiMOF/NF, enabling more efficient charge transfer during the OER process. Additionally, the modified FeOOH surface morphology increased the number of accessible active sites and enhanced the exposure of catalytic centers. In summary, these structural and electronic modifications synergistically improve the overall catalytic performance and have guiding significance for the application of MOF to OER.

Zinc is an essential element that is readily available, inexpensive, and ecologically friendly, and it will be employed in both theranostic (diagnostic and therapeutic) applications in current industrial developments. Our current work used the green chemical approach to illuminate the zinc oxide nanoparticles (ZnO NPs) synthesized from Couroupita guianensis (CG) flower extract. Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), Energy-dispersive X-ray (EDX), X-ray diffraction (XRD) embedded and techniques characterize the produced CG-ZnO NPs and determine their characteristics. Following the addition of CG-ZnO NPs, the antioxidant, antibacterial, and human sperm viability followed by DNA damage inhibition may be assessed using the comet test. The characterization results show that phenols, phytosterols, aromatic nitrides, and phytosterols from the FT-IR functional groups, UV-Vis of 340 nm as ZnO NPs confirmatory, followed by XRD with a 2-theta value of 101^o shows the sample’s crystallinity and its pure phase were validated by the XRD signal and FE-SEM with 14–18 nm in size and a spherical structure, then EDX with Zn particles confirm the presence of Zn. According to the results, CG-ZnO NPs form zones with diameters of 18 mm, 15 mm, 13 mm, 11 mm, and 7 mm against both Gram-positive and Gram-negative bacteria. In addition, findings from antioxidant scavenging of free radicals quenching against specified DPPH methanol reveal that CG-ZnO NPs with 100 µg/ml (71.32%) are enough to act against free radicals, approximately equal to control ascorbic acid (72%). As a first effort, CG-ZnO NPs prevent DNA damage in human sperm cells against H₂O₂ and UV radiation compared to the negative control. CG-ZnO NPs improved sperm cell viability and inhibited DNA damage when compared to control and H₂O₂. This research evaluates the outcome of the Comet Assay Software Project (CASP) for evaluating comet photographs. The automated CASP system aids in the assessment of sperm motility and quality. Comet formation in sperm cells, indicating DNA damage, was observed, and sperm cells treated with CG-ZnO NPs were recognized and validated using CASP version 1.2.2. As a consequence, our CG-ZnO NPs may be used as cryoprotectants against the freeze/thaw of artificial reproduction technology centres, protecting them from ROS free radicals for extended periods. Overall, the comparison results are consistent in both antioxidants and antibacterials, with notable results in sperm DNA damage inhibition having the potential for usage in various therapeutic domains.