Search Results (351)

A number of phenomena were observed in experiments on the study of cosmic rays at mountain altitudes and in the stratosphere at ultra-high energies; in particular, the coplanarity of the most energetic particles and local subcascades in the so-called families of γ-rays and hadrons in the cores of extensive air showers at E₀ ≳ 2·10¹⁵ eV (√s ≳ 2 TeV). These effects are not described by theoretical models. To explain this phenomenon, it may be necessary to introduce a new process of generating the most energetic particles in the interactions of hadrons with the nuclei of atmospheric atoms. A new experimental array of cosmic ray detectors, including the ADRON-55 ionization calorimeter, has been created to study processes in EAS cores at ultra-high energies. The possibility of using it to study the coplanarity effect is being considered. Full article

The Standard Model (SM) fails to explain many problems (neutrino masses, dark matter, and matter–antimatter asymmetry, among others) that may be resolved with new particles beyond the SM. No observation of such new particles may be explained either by their exceptionally high mass or by considerably small coupling to SM particles. The latter case implies relatively long lifetimes. Such long-lived particles (LLPs) then to have signatures different from those of SM particles. Searches in the “central region” are covered by the LHC general purpose experiments. The forward small angle region far from the interaction point (IP) is unexplored. Such particles are expected to have the energy as large as E = $\mathcal{O}$(1 TeV) and Lorentz time dilation factor $\gamma =E/m\approx {10}^2$–${10}^3$ (with m the particle mass) hence long enough decay distances. A new class of specialized LHC detectors dedicated to LLP searches has been proposed for the forward regions. Among these experiments, FASER is already operational, and FACET is under consideration at a location 100 m from the LHC IP5 (the CMS detector intersection). However, some features of FACET require a specially enlarged beam pipe, which cannot be implemented for LHC Run 4. In this study, we explore a simplified version of the proposed detector PREFACE compatible with the standard LHC beam pipe in the HL-LHC Run 4. Realistic Geant4 simulations are performed and the background is evaluated. An initial analysis of the physics potential with the PREFACE geometry indicates that several significant channels could be accessible with sensitivities comparable to FACET and other LLP searches. Full article

PSR B1259-63/LS 2883 is a well-studied gamma-ray binary hosting a pulsar in a 3.4-year eccentric orbit around a Be-type star. Its non-thermal emission spans from radio to TeV energies, exhibiting a significant increase near the periastron passage. This paper is dedicated to the analysis of INTEGRAL observations of the system following its last periastron passage in June 2024. We aim to study the spectral evolution of this gamma-ray binary in the soft (0.3–10 keV) and hard (30–300 keV) X-ray energy bands. We performed a joint analysis of the data taken by INTEGRAL/ISGRI in July–August 2024 and quasi-simultaneous Swift/XRT observations. The spectrum of the system in the 0.3–300 keV band is well described by an absorbed power law with a photon index of $\Gamma =1.42\pm 0.03$. We place constraints on potential spectral curvature, limiting the break energy $E_{\mathrm{b}}>30$ keV for $\Delta \Gamma >0.3$ and cutoff energy $E_{\mathrm{cutoff}}>150$ keV at a 95% confidence level. For one-zone leptonic emission models, these values correspond to electron distribution spectral parameters of $E_{\mathrm{b},\mathrm{e}}>0.8$ TeV and $E_{\mathrm{cutoff},\mathrm{e}}>1.7$ TeV, consistent with previous constraints derived by H.E.S.S. Full article

In this work, bio-based thermoelectric composites were developed using acrylated epoxidized soybean oil (AESO) as the polymer matrix and bismuth telluride (Bi₂Te₃) as the thermoelectric filler. The materials were formulated for both UV-curing and thermal-curing processes, with a focus on Digital Light Processing (DLP) 3D printing. Although UV curing proved ineffective at high filler concentrations due to the light opacity of Bi₂Te₃, thermal curing enabled the fabrication of stable, homogeneously dispersed composites. The samples were thoroughly characterized through rheology, FTIR, TGA, XRD, SEM, and density measurements. Thermoelectric performance was assessed under a 70 °C temperature gradient, with Seebeck coefficients reaching up to 51 µV/K. Accelerated chemical degradation studies in basic media confirmed the degradability of the matrix. The results demonstrate the feasibility of combining additive manufacturing with sustainable materials for low-power thermoelectric energy harvesting applications. Full article

This study employs density functional theory (DFT) to investigate the electronic and optical properties of molybdenum (Mo) and chalcogen (S, Se, Te) co-doped anatase TiO₂. Two co-doping configurations were examined: Model 1, where the dopants are adjacent, and Model 2, where the dopants are farther apart. The incorporation of Mo into anatase TiO₂ resulted in a significant bandgap reduction, lowering it from 3.22 eV (pure TiO₂) to range of 2.52–0.68 eV, depending on the specific doping model. The introduction of Mo-4d states below the conduction band led to a shift in the Fermi level from the top of the valence band to the bottom of the conduction band, confirming the n-type doping characteristics of Mo in TiO₂. Chalcogen doping introduced isolated electronic states from Te-5p, S-3p, and Se-4p located above the valence band maximum, further reducing the bandgap. Among the examined configurations, Mo–S co-doping in Model 1 exhibited most optimal structural stability structure with the fewer impurity states, enhancing photocatalytic efficiency by reducing charge recombination. With the exception of Mo–Te co-doping, all co-doped systems demonstrated strong oxidation power under visible light, making Mo-S and Mo-Se co-doped TiO₂ promising candidates for oxidation-driven photocatalysis. However, their limited reduction ability suggests they may be less suitable for water-splitting applications. The study also revealed that dopant positioning significantly influences charge transfer and optoelectronic properties. Model 1 favored localized electron density and weaker magnetization, while Model 2 exhibited delocalized charge density and stronger magnetization. These findings underscore the critical role of dopant arrangement in optimizing TiO₂-based photocatalysts for solar energy applications. Full article

Occupied and unoccupied electronic states of altermagnetic MnTe(0001) single crystals were studied by photoemission and inverse-photoemission spectroscopies after establishing a reproducible surface cleaning procedure involving repeated sputtering and annealing cycles. The angle-resolved photoemission spectroscopy (ARPES) exhibited a hole-like band dispersion centered at the $\overline{\mathsf{\Gamma }}$ point, which was consistent with the reported ARPES results and our density functional theory (DFT) calculations with the on-site Coulomb interaction U. The observed Mn 3d↑-derived peak at −3.5 eV, however, significantly deviated from the DFT + U calculations. Meanwhile, the Mn 3d↓-derived peak at +3.0 eV observed by inverse-photoemission spectroscopy agreed well with the DFT + U results. Based on simulations of the spectral function employing an w-dependent model self-energy, we found significant relaxation effects in the electron-removal process, while such effects were negligible in the electron-addition process. Our study provides a comprehensive picture of electronic states, forming a solid foundation for understanding the magnetic and transport properties of MnTe. Full article

Aqueous zinc ion batteries (AZIBs) have considerable potential for energy storage owing to their cost-effectiveness, safety, and environmental sustainability. However, dendrite formation, hydrogen evolution reaction (HER), and corrosion of the bare zinc (B-Zn) anode tremendously impact the performance degradation and premature failure of AZIBs. This study introduces a glancing angle deposition (GLAD) approach during the sputtering process to fabricate tellurium nanostructured (TeNS) at the zinc (Zn) anode to avoid the aforementioned issues with the B-Zn anode. Three different deposition times (5, 10, and 30 min) were used to prepare TeNS at the Zn anode. The morphology, crystallinity, composition, and wettability of the TeNSs were analyzed. The TeNSs served as hydrophilic sites and a protective layer, facilitating uniform Zn nucleation and plating while inhibiting dendrite formation and side reactions. Consequently, the symmetric cell with TeNS deposited on the Zn anode for 10 min (Te@Zn_10 min) demonstrated an enhanced cycling stability of 350 h, the lowest nucleation overpotential of 10.65 mV at a current density of 1 mA/cm², and an areal capacity of 0.5 mAh/cm². The observed enhancement in the cycling stability and reduction in the nucleation overpotential can be attributed to the optimal open area fraction of the TeNSs on the Zn surface, which promotes uniform Zn deposition while effectively suppressing side reactions. Full article

A superconducting transition-edge sensor (TES) as a microcalorimeter detects incoming photons by measuring heat converted from photon energy. With high resolving power and low noise levels, a TES is sensitive to single photons and able to count photons within a wide spectral band from X-ray to near-infrared. We have developed a TES detector aiming at soft X-ray spectroscopy applications. In this work, the performance of this detector is characterized. It is shown that the energy resolution of this detector is about 1.8 eV for 1.5 keV photons. The good resolution is also kept in visible range, enabling photon-number resolving for 405 nm photons. Full article

This study presents the investigation of freezeout parameters, namely the kinetic freezeout temperature (T) and transverse flow velocity (${\beta }_T$), in different centrality intervals with fixed as well as with variable flow profile ($n_0$) in the blast-wave model (using Boltzmann Gibbs statistics). The model is used to fit the experimental data of transverse momentum spectra of ${\pi }^{+}$, $K^{+}$, and p in $Au$–$Au$ and $Pb$–$Pb$ collisions at 200 GeV and 2.76 TeV, respectively. In our observation, when the parameter $n_0$ is considered as a free parameter, the parameter T decreases from head-on to peripheral collisions, while it increases towards the periphery if $n_0$ is fixed. In addition, parameter ${\beta }_T$ decreases from central to peripheral collisions in both cases. These findings provide valuable insights into the dynamics of quark-gluon plasma formation and expansion in high-energy nuclear collisions. Moreover, the kinetic freezeout temperature T and the transverse flow velocity ${\beta }_T$ are mass-dependent; while the former becomes larger for massive particles, the latter becomes larger for light particles, showing the mass differential kinetic freezeout scenario. Full article

Synthesis and characterization of undoped and samarium-doped CuO–SnO₂:F thin films using the spray pyrolysis technique are presented. The effect of the samarium doping level on the physical properties of these films was thoroughly analyzed. X-ray diffraction patterns proved the successful synthesis of pure CuO–SnO₂:F thin films, free from detectable impurities. The smallest crystallite size was observed in 6% Sm-doped CuO–SnO₂:F thin films. The 6% Sm-doped CuO–SnO₂films demonstrated an increasedsurface area of 40.6 m²/g, highlighting improved textural properties, which was further validated by XPS analysis.The bandgap energy was found to increase from 1.90 eV for undoped CuO–SnO₂:F to 2.52 eV for 4% Sm-doped CuO–SnO₂:F, before decreasing to 2.03 eV for 6% Sm-doped CuO–SnO2:F thin films. Photoluminescence spectra revealed various emission peaks, suggesting a quenching effect. A numerical simulation of a new solar cell based on FTO/ZnO/Sm–CuO–SnO₂:F/X/Mo was carried out using Silvaco Atlas software, where X represented the absorber layer CIGS, CdTe, and CZTS. The results showed that the solar cell with CIGS as the absorber layer achieved the highest efficiency of 15.98. Additionally, the thin films demonstrated strong photocatalytic performance, with 6% Sm-doped CuO–SnO₂:F showing 86% degradation of ampicillin after two hours. This comprehensive investigation provided valuable insights into the synthesis, properties, and potential applications of Sm-doped CuO–SnO₂ thin films, particularly for solar energy and pharmaceutical applications. Full article

Searching for very-high-energy photons arising from dark matter interactions in selected astrophysical environments is a promising strategy to probe the existence and particle nature of dark matter. Among the many particle candidates, motivated by the extensions of the Standard Model, Weakly Interacting Massive Particles (WIMPs) are considered the most compelling candidate for the elusive dark matter in the universe. In this contribution, we report an overview of the important developments in the field of indirect searching for dark matter through cosmic gamma-ray observations. We mainly focus on the role of atmospheric Cherenkov telescopes in probing the dark matter. Finally, we emphasize the opportunities for the Major Atmospheric Cherenkov Experiment (MACE) situated in Hanle, India, to explore WIMPs in the mass range of 200 GeV to 10 TeV for Segue1 and Draco dwarf–spheroidal galaxies. Full article

In recent years, bipolar organic electrode materials have gained recognition as competitive alternatives to inorganic materials due to their unique multielectron redox mechanism for energy storage. In this study, we examined the mechanism of redox reactions in naphthalimide (NI) derivatives when used as electrodes in lithium half-cells with ionic liquid electrolytes. The NI derivatives consist of three building fragments: an aromatic naphthalene core, N-alkylated imide unit, and a peri-dichalcogenide bridge. The integration of electrochemical and microscopic methods with DFT calculations facilitates the delineation of the role of each fragment in the oxidation and reduction reactions of NI derivatives. It is found that the peri-dichalcogenide bridge is mainly involved in the oxidation of NI derivatives above 3.9 V, the charge compensation being achieved by electrolyte TFSI⁻ counter-ions. The reduction of NI derivatives with two Li⁺ ions is mainly due to the participation of the chalcogenide bridge, while after interaction with the next two Li⁺ ions, the imide fragment and the naphthalene moiety contribute equally to the reduction. Based on the leading role of the peri-dichalcogenide bridge, the redox properties of NI derivatives are effectively controlled by the gradual replacement of S with Se and Te atoms in the bridge. To improve the electronic conductivity of NIs, composites with rGO are also synthesized by a simple procedure of mechanical mixing in a centrifugal mixer. The composites rGO/NIs display a good storage performance, the best being the Se-containing analogue. Full article

Under mild conditions, the effective conversion of carbon dioxide (CO₂) into formic acid (HCOOH) and carbon monoxide (CO) represents a promising avenue for mitigating greenhouse gas emissions and addressing energy crises. In this work, we analyzed the electro-catalytic activities of six metals (Ti, Fe, Ni, Cu, Zn, and Cr) anchored on monolayer molybdenum telluride (TM@MoTe₂) for the CO₂ reduction reaction (CO₂RR) from CO₂ to HCOOH and CO. Compared to the reversible hydrogen electrode, the limiting potential for HCOOH production on Ni@MoTe₂ is only about −0.38 V, and it is only about −0.20 V for the CO production on Cu@MoTe₂. The limiting potential is concerned with the free energies of *OCHO and *COOH. Both the CO₂RRs suppress the competing hydrogen evolution reaction (HER) and exhibit good selectivity for the desired reaction products. These features enable the efficient conversion of CO₂ into HCOOH on Ni@MoTe₂ or CO on Cu@MoTe₂. Our calculations could provide valuable insights for the design and synthesis of high-performance catalysts based on MoTe₂. Full article

Silver nanoparticles belong to a highly versatile group of nanomaterials with an appealing range of potential applications. In the realm of antimicrobial and antioxidant application, silver nanoparticles (AgNPs) exhibit auspicious capabilities. This research, for the very first time, endeavors to carry out biosynthesis of AgNPs coupled with fermentation using Medusomyces gisevii and Origanum vulgare L. (O. vulgare) plant species. Fermentation (F) via Medusomyces gisevii is responsible for chemical, physical, biological, and electrochemical processes. During in vitro study of antioxidant activity, fermented O. vulgare herb extract showed strong reductive activity as evaluated by the cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) assay, with a value of 1.45 ± 0.048 mmol TE/g, 0.95 ± 0.04 mmol TE/g, and 0.59 ± 0.023 mmol TE/g, respectively. The highest antimicrobial activity was shown by Staphylococcus aureus in the inhibition zone, with values of 1.40 ± 0.12 mm of OrV and of 10.30 ± 0.04 mm and 11.54 ± 0.10 mm for OrV-AgNPs and OrV-F-AgNPs, respectively. Analysis of phenolic compounds revealed that the highest total amount of the apigenin, 87.78 µg/g, was detected in OrV-F-AgNPs and the lowest amount, 16.56 µg/g, in OrV-AgNPs. Moreover, in OrV-F-AgNPs, the collective amount of proanthocyanidins, hydroxycinnamic, and flavonoids was prominently high in all cases, i.e., 145.00 ± 0.02 mg EE/g DW, 2.86 ± 0.01 mg CAE/g DW, and 0.55 ± 0.01 mg RE/g DW, respectively, as compared to the original extract (102.1 ± 0.03 mg EE/g DW, 2.78 ± 0.02 mg CAE/g DW, and 0.47 ± 0.01 mg RE/g DW, respectively). During the characterization of biosynthesized nanoparticles by scanning electron microscopy (SEM), AgNPs demonstrated a uniform spherical shape with even distribution. The sample’s elemental composition was confirmed with a signal of 3.2 keV using energy-dispersive X-ray spectroscopy (EDS) analysis. Transmission electron microscopy (TEM) analysis showed silver nanoparticles that were round and spherical in shape in both stacked and congested form, with a size range of less than 30 nm. Thus, this green and sustainable synthesis of AgNPs, a blend of Medusomyces gisevii and O. vulgare herbal extract, has adequate potential for increased antimicrobial and antioxidant activity. Full article

New glasses in the xCdO-(90 − x)TeO₂-10GeO₂ system were obtained by the conventional melt-quenching process at 900 °C. The glasses were transparent to the naked eye. The diffraction patterns indicate that the samples were mostly amorphous, except for the CdO-rich glasses, in which the formation of nanocrystals of CdO and Cd₃TeO₆ were identified. Raman spectroscopy analysis of the samples displayed the existence of TeO₃, TeO₃₊₁, TeO₄, and GeO₄, structural units within the glass matrix. The optical band gap of the glass samples was determined by optical absorption spectroscopy using the Tauc method. Depending on the relative content of TeO₂, their values varied in the range of 2.32–2.86 eV. The refractive index was obtained from the band gap values. The XPS measurements showed that Ge 3d, O 1s and Te 3d_3/2, Te 3d_5/2, Cd 3d_5/2, and Cd 3d_3/2 doublets shifted to higher binding energy values as the amount of TeO₂ was increased. The binding energy values of the Te 3d doublet are related to the TeO₄ and TeO₃ groups. Full article