Search Results (146)

Blazars are a class of active galactic nuclei characterized by having one of their relativistic jets oriented close to our line of sight. Their broad emission spectrum makes them exceptional laboratories for probing fundamental physics. In this review, we explore the potential impact on blazar observations of three scenarios beyond the standard paradigm: (i) the hadron beam model, (ii) the interaction of photons with axion-like particles (ALPs), and (iii) Lorentz invariance violation. We focus on the very-high-energy spectral features these scenarios induce in the blazars Markarian 501 and 1ES 0229+200, making them ideal targets for testing such effects. Additionally, we examine ALP-induced effects on the polarization of UV-X-ray and high-energy photons from the blazar OJ 287. The unique signatures produced by these models are accessible to current and upcoming instruments—such as the ASTRI Mini Array, CTAO, LHAASO, IXPE, COSI, and AMEGO—offering new opportunities to probe and constrain fundamental physics through blazar observations. Full article

In this study, we investigate the phase transition process during high-alumina, low-lithium glass-ceramics (ZnO-MgO-Li₂O-SiO₂-Al₂O₃) crystallization. The differential scanning calorimetry and high-temperature X-ray diffraction results show that approximately 10 wt.% of (Zn, Mg)Al₂O₄ crystals precipitated when the heat treatment temperature reached 850 °C, indicating that a large number of nuclei had already formed during the earlier stages of heat treatment. Field emission transmission electron microscopy used to observe the microstructure of glass-ceramics after staged heat treatment revealed that cation migration occurred during the nucleation process. Zn and Mg aggregated around Al to form (Zn, Mg)Al₂O₄ nuclei, which provided sites for crystal growth. Moreover, high-valence Zr aggregated outside the glass network, leading to the formation of nanocrystals. Raman spectroscopy analysis of samples at different stages of crystallization revealed that during spinel precipitation, the Q³ and Q⁴ structural units in the glass network increased significantly, along with an increase in the number of bridging oxygens. Highly coordinated Al originally present in the network mainly participated in spinel nucleation, effectively suppressing the subsequent formation of Li_xAl_xSi_1−xO₂, which eventually resulted in the successful preparation of glass-ceramics with (Zn, Mg)Al₂O₄ and ZrO₂ as the main crystalline phases. The grains in this glass-ceramic are all nanocrystals. Its Vickers hardness and flexural strength can reach up to 875 Hv and 350 MPa, respectively, while the visible light transmittance of the glass-ceramic reaches 81.5%. This material shows potential for applications in touchscreen protection, aircraft and high-speed train windshields, and related fields. Full article

Cancer is still the world’s most prevalent cause of death, and the limited efficacy of current treatments highlights the requirement for new therapeutic approaches. In this study, neodymium (Nd)-doped cobalt ferrite (CoFe_2₋zNd_zO₄, z = 0; 0.01; 0.02; 0.03; 0.05; 0.1) nanoparticles (Nd0-Nd5) were synthesized via the combustion method. The structural, morphological, and magnetic properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), and scanning transmission electron microscopy (STEM) analysis. The synthesized compounds demonstrated single-phase spinel structures, with morphological differences observed between undoped and Nd-doped samples. The biological activity of the nanoparticles was evaluated on immortalized human keratinocytes (HaCaT) and on cancer cell lines: melanoma (A375), breast adenocarcinoma (MCF-7), and pancreatic carcinoma (PANC-1). The cytotoxic effects of Nd0-Nd5 (50–1000 μg∙mL⁻¹) were assessed through Alamar Blue and lactate dehydrogenase (LDH) release assays. The results indicated a dose-dependent cytotoxic effect in cancer cell lines. Changes in cell morphology, suggesting the induction of the apoptotic processes, were observed through immunofluorescence staining of F-actin and nuclei. These findings highlight the potential of Nd-doped cobalt ferrite nanoparticles as selective anticancer agents, warranting further investigation to fully elucidate their mechanisms of action and therapeutic applicability. Full article

The main goal of this study was to investigate the properties of ZnO thin films, including pure films and those doped with indium (up to 8 mol%) that was deposited using a spray pyrolysis technique on glass and silicon substrates in order to prepare the position-sensitive structure, Si-SiO₂-ZnO:In. To this aim, the present work is focused on investigating the effect of indium concentration on the morphology, structure, and optical properties of the films. X-ray diffraction (XRD) analysis reveals a wurtzite polycrystalline structure. Scanning electron microscopy (SEM) images display a smooth and uniform surface characterized by closely packed nanocrystalline clusters. As the indium concentration rises to 8 mol%, the number of nuclei grows, resulting in uniformly distributed grains across the entire substrate surface. The estimated root mean square (RMS) roughness values for the thin films undoped and doped with 3 mol%, 5 mol%, and 8 mol% of ZnO measured using AFM are 6.13, 9.64, and 13.76 nm, respectively. The increase in indium concentration leads to a slight decrease in film transmittance. The measured LPV photosensitivity of about 44 mV/mm confirms the potential use of these thin films in practical applications. Full article

The Shapley Supercluster, one of the largest and most massive structures in the nearby (redshift $z\le 0.1$) Universe, located approximately 200 Mpc away, is a unique laboratory for high-energy astrophysics. Galaxy clusters that comprise it are promising targets for multimessenger study due to the presence in the intracluster medium of the necessary conditions for the acceleration of cosmic rays up to ultra-high energies and the generation by them of non-thermal electromagnetic and neutrino emission. Using the Shapley Supercluster’s observational data from the recent eROSITA-DE Data Release, we recover the physical parameters of 45 X-ray luminous galaxy clusters and calculate the expected multiwavelength—from radio to very-high-energy γ-ray as well as neutrino emission, with a particular focus on hadronic interactions of accelerated cosmic ray nuclei with the nuclei of the intracluster medium. The results obtained allow verification of cluster models based on multimessenger observations of clusters, especially in $\gamma$-ray (Fermi-LAT, H.E.S.S., CTAO-South for the Shapley Supercluster case), and neutrino (Ice Cube, KM3NeT). We also estimate the ability of the Shapley Supercluster to manifest as cosmic Zevatrons and show that it can contribute to the PAO Hot Spot in the Cen A region at UHECR energies over 50 EeV. Full article

Alzheimer’s disease (AD) is one of the primary causes of disability and dependency among aging populations worldwide. Neuroinflammation may be a potential therapeutic target in AD. Moreover, ionizing radiation may be a tool for modulating neuroinflammation. Here, we used three mouse lines—C57Bl/6 and the transgenic AD models 5xFAD and Tau P301S—to investigate the effects of combined ionizing radiation (γ-rays and carbon-12 nuclei) on emotional state, cognitive abilities, and markers of microglial activation. The obtained data show that combined irradiation results in enhanced exploratory behavior and spatial learning in the C57Bl/6 mice. The same changes, as well as a decrease in anxiety, were found in the Tau P301S mice. Irradiation of the 5xFAD mice resulted in improved welfare and ability to discriminate odors. At the same time, irradiation led to an increase in the level of pro- and anti-inflammatory cytokines in the prefrontal cortex and, to a lesser extent, in the hippocampus of the C57Bl/6 and Tau P301S mice. An increase in macrophage inflammatory protein-1α in the prefrontal cortex and a decrease in interleukin 2β in the hippocampus were found in the 5xFAD mice. Taken together, our data indicate that ionizing radiation exposure is an adequate tool to modulate microglial activity in the brain and may provide cognitive and non-cognitive behavioral benefits in neurodegenerative disease conditions. Full article

Boron Neutron Capture Therapy is a re-emerging therapy for the treatment of cancer, and the development of new neutron-reactive nuclei carriers with enhanced efficiency is of great importance. In this work we propose three new boron-based solid compounds, of formulas [Ca(H₂O)₆](C₁₄H₈O₆B)₂ (CaSB), [Cu(C₁₄H₈O₆B)] (CuSB), and [Li(C₁₄H₈O₆B)(H₂O)] (LiSB), usable as nanoparticles for the carriage of the ¹⁰B isotope. The copper atom in CuSB was introduced because it is known that its presence magnifies the effect of the radiation on cells. Furthermore, the lithium atom in LiSB also allows us to include the ⁶Li isotope, which can take part in the nuclear reactions, enhancing the efficiency of the anti-cancer treatment. The compounds were characterized with single-crystal X-ray diffraction to compare the densities of the reactive isotopes in the materials, a key parameter related to the efficiency of the materials. In this work, we used a computational method to calculate the dose absorbed by a tumor mass treated with nanoparticles of the compounds in order to select the most efficient one for the therapy. The results reported in this work are encouraging. Full article

Accreting white dwarf binaries (AWDs) comprise cataclysmic variables (CVs), symbiotics, AM CVns, and other related systems that host a primary white dwarf (WD) accreting from a main sequence or evolved companion star. AWDs are a product of close binary evolution; thus, they are important for understanding the evolution and population of X-ray binaries in the Milky Way and other galaxies. AWDs are essential for studying astrophysical plasmas under different conditions along with accretion physics and processes, transient events, matter ejection and outflows, compact binary evolution, mergers, angular momentum loss mechanisms, and nuclear processes leading to explosions. AWDs are also closely related to other objects in the late stages of stellar evolution, with other accreting objects in compact binaries, and even share common phenomena with young stellar objects, active galactic nuclei, quasars, and supernova remnants. As X-ray astronomy came to a climax with the start of the Chandra and XMM-Newton missions owing to their unprecedented instrumentation, new excellent imaging capabilities, good time resolution, and X-ray grating technologies allowed immense advancement in many aspects of astronomy and astrophysics. In this review, we lay out a panorama of developments on the study of AWDs that have been accomplished and have been made possible by these two observatories; we summarize the key observational achievements and the challenges ahead. Full article

New haloaminopyrazole derivatives differing in the number of pyrazole nuclei 4a–f and 5a–e, respectively, were synthesized and characterized by ¹H-NMR, ¹³C-NMR, IR, UV-Vis, and elemental analysis. The single-crystal X-ray diffraction method was used to describe compounds 4a and 5d. When tested on normal NCTC fibroblasts in vitro, the newly synthesized derivatives were shown to be non-cytotoxic at a dosage of 25 μg/mL. Two compounds 4a and 5d showed a high degree of biocompatibility. From the two series of compounds tested on HEp-2 human cervical carcinoma cells, compound 5d showed a more pronounced antiproliferative effect. Gram-positive strains of Staphylococcus aureus ATCC25923, Enterococcus faecalis ATCC29212, Gram-negative strains of Pseudomonas aeruginosa ATCC27853, and strains of Escherichia coli ATCC25922 were used to test the newly synthesized compounds antibacterial and antibiofilm properties. Among the studied pyrazole compounds, 2 compounds 4a and 5a with fluorine content on the phenyl ring and 4 compounds 4b, 4e, 4f, and 5b with chlorine content on the phenyl ring were noted, which proved to be the most active compared with the two reference drugs, metronidazole and nitrofurantoin. The six compounds showed a broad spectrum of action against all four tested bacterial strains, the most active being compound 4b, with a chlorine atom in the “4” position of the phenyl nucleus and a MIC of 460 μg/mL. Compounds 4a and 5a showed the best antibiofilm activity against the bacterial strain Staphylococcus aureus ATCC25923, with an MBIC of 230 μg/mL. Full article

To overcome chondrosarcoma’s (CHS) high chemo- and radioresistance, we used polyethylene glycol-encapsulated iron oxide nanoparticles (IONPs) for the controlled delivery of the chemotherapeutic doxorubicin (IONP_DOX) to amplify the cytotoxicity of proton radiation therapy. Human 2D CHS SW1353 cells were treated with protons (linear energy transfer (LET): 1.6 and 12.6 keV/µm) with and without IONP_DOX. Cell survival was assayed using a clonogenic test, and genotoxicity was tested through the formation of micronuclei (MN) and γH2AX foci, respectively. Morphology together with spectral fingerprints of nuclei were measured using enhanced dark-field microscopy (EDFM) assembled with a hyperspectral imaging (HI) module and an axial scanning fluorescence module, as well as scanning electron microscopy (SEM) coupled with energy-dispersive X-Ray spectroscopy (EDX). Cell survival was also determined in 3D SW3153 spheroids following treatment with low-LET protons with/without the IONP_DOX compound. IONP_DOX increased radiosensitivity following proton irradiation at both LETs in correlation with DNA damage expressed as MN or γH2AX. The IONP_DOX–low-LET proton combination caused a more lethal effect compared to IONP_DOX–high-LET protons. CHS cell biological alterations were reflected by the modifications in the hyperspectral images and spectral profiles, emphasizing new possible spectroscopic markers of cancer therapy effects. Our findings show that the proposed treatment combination has the potential to improve the management of CHS. Full article

The structure and physicochemical properties of polyvinyl alcohol (PVA) and PVA/glycerol films have been investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), and advanced scanning probe microscopy (SPM). In the pure PVA films, SPM allowed us to observe ribbon-shaped domains with a different frictional and elastic contrast, which apparently originated from a correlated growth or assembly of PVA crystalline nuclei located within individual PVA clusters. The incorporation of 22% w/w glycerol led to modification in shape of those domains from ribbon-like in pure PVA to rounded in PVA/glycerol 22% w/w films; changes in the relative intensities of the XRD peaks and a decrease in the amorphous halo in the XRD pattern were also detected, while the DTA peak corresponding to the melting point remained at almost the same temperature. For higher glycerol content, FT-IR revealed additional glycerol-characteristic peaks presumably related to the formation of glycerol aggregates, and XRD, FT-IR, and DTA all indicated a reduction in crystallinity. For more than 36% w/w glycerol, the plasticization of the films complicated the acquisition of SPM images without tip-induced surface modification. Our study contributes to the understanding of crystallinity in PVA and how it is altered by a plasticizer such as glycerol. Full article

X-ray polarization, which now can be measured by the Imaging X-ray Polarimetry Explorer (IXPE), is a new probe of jets in the supermassive black hole systems of active galactic nuclei (AGNs). Here, we summarize IXPE observations of radio-loud AGNs that have been published thus far. Blazars with synchrotron spectral energy distributions (SEDs) that peak at X-ray energies are routinely detected. The degree of X-ray polarization is considerably higher than at longer wavelengths. This is readily explained by energy stratification of the emission regions when electrons lose energy via radiation as they propagate away from the sites of particle acceleration as predicted in shock models. However, the 2–8 keV polarization electric vector is not always aligned with the jet direction as one would expect unless the shock is oblique. Magnetic reconnection may provide an alternative explanation. The rotation of the polarization vector in Mrk421 suggests the presence of a helical magnetic field in the jet. In blazars with lower-frequency peaks and the radio galaxy Centaurus A, the non-detection of X-ray polarization by IXPE constrains the X-ray emission mechanism. Full article

The fundamental plane of black hole activity is a very important tool to study accretion and jets. However, we found that the SEDs of AGNs and XRBs are different in the 2–10 keV energy band, and it seems inappropriate to use 2–10 keV X-ray luminosities to study the fundamental plane. In this work, we use the luminosity near the peak of the blackbody radiation of the active galactic nuclei and black hole binaries to replace the 2–10 keV luminosity. We re-explore the fundamental plane of black hole activity by using the 2500 $\mathring{\mathrm{A}}$ luminosity as the peak luminosity of the blackbody radiation of AGNs and 1 keV luminosity as the peak luminosity of the blackbody radiation of XRBs. We compile samples of black hole binaries and active galactic nuclei with luminosity near the peak luminosity of blackbody radiation and study the fundamental plane between radio luminosity ($L_{\mathrm{R}}$), the peak luminosity of blackbody radiation ($L_{\mathrm{peak}}$), and black hole mass ($M_{\mathrm{BH}}$). We find that the radio–peak luminosity correlations are $L_{5\mathrm{GHz}}/L_{\mathrm{Edd}}\propto {(L_{2500\mathring{\mathrm{A}}}/L_{\mathrm{Edd}})}^{1.55}$ and $L_{5\mathrm{GHz}}/L_{\mathrm{Edd}}\propto {(L_{1\mathrm{keV}}/L_{\mathrm{Edd}})}^{1.53}$ for AGN and XRB, respectively, in the radiatively efficient sample, and $L_{5\mathrm{GHz}}/L_{\mathrm{Edd}}\propto {(L_{2500\mathring{\mathrm{A}}}/L_{\mathrm{Edd}})}^{0.48}$ and $L_{5\mathrm{GHz}}/L_{\mathrm{Edd}}\propto {(L_{1\mathrm{keV}}/L_{\mathrm{Edd}})}^{0.53}$ in the radiatively inefficient sample, respectively. Based on the similarities in radio–peak correlations, we further propose a fundamental plane in radio luminosity, the peak luminosity of blackbody radiation, and black hole mass, which is radiatively efficient: $log{L}_{5\mathrm{GHz}}=1.{57}_{-0.01}^{+0.01}log{L}_{\mathrm{peak}}-0.{32}_{-0.16}^{+0.16}log{M}_{\mathrm{BH}}-27.{73}_{-0.34}^{+0.34}$ with a scatter of ${\sigma }_{\mathrm{R}}$ = 0.48 dex, and radiatively inefficient: $log{L}_{5\mathrm{GHz}}=0.{45}_{-0.01}^{+0.01}log{L}_{\mathrm{peak}}+0.{91}_{-0.10}^{+0.12}log{M}_{\mathrm{BH}}+12.{58}_{-0.38}^{+0.38}$ with a scatter of ${\sigma }_{\mathrm{R}}$ = 0.63 dex. Our results are similar to those of previous studies on the fundamental plane for radiatively efficient and radiatively inefficient black hole activity. However, our results exhibit a smaller scatter, so when using the same part of blackbody radiation (i.e., the peak luminosity of the blackbody radiation), the fundamental plane becomes a little bit tighter. Full article

Ultra-high-energy cosmic rays (UHECRs) are extremely rare energetic particles of ordinary matter in the Universe, traveling astronomical distances before reaching the Earth’s atmosphere. When primary cosmic rays interact with atmospheric nuclei, cascading extensive air showers (EASs) of secondary elementary particles are developed. Radio detectors have proven to be a reliable method for reconstructing the properties of EASs, such as the shower’s axis, its energy, and its maximum (${\mathrm{X}}_{\max }$). This aids in understanding fundamental astrophysical phenomena, like active galactic nuclei and gamma-ray bursts. Concurrently, data science has become indispensable in UHECR research. By applying statistical, computational, and deep learning methods to both real-world and simulated radio data, researchers can extract insights and make predictions. We introduce a convolutional neural network (CNN) architecture designed to classify simulated air shower events as either being generated by protons or by iron nuclei. The classification achieved a stable test error of 10%, with Accuracy and ${\mathrm{F}}_1$ scores of 0.9 and an MCC of 0.8. These metrics indicate strong prediction capability for UHECR’s nuclear composition, based on data that can be gathered by detectors at the world’s largest cosmic rays experiment on Earth, the Pierre Auger Observatory, which includes radio antennas, water Cherenkov detectors, and fluorescence telescopes. Full article

The present study investigated the effect of different polymers and manufacturing methods (hot melt extrusion, HME, and spray drying, SD) on the solid state, stability and pharmaceutical performance of amorphous solid dispersions. In the present manuscript, a combination of different binary amorphous solid dispersions containing 20% and 30% of drug loadings were prepared using SD and HME. The developed solid-state properties of the dispersions were evaluated using small- and wide-angle X-ray scattering (WAXS) and modulated differential scanning calorimetry (mDSC). The molecular interaction between the active pharmaceutical ingredients (APIs) and polymers were investigated via infrared (IR) and Raman spectroscopy. The in vitro release profile of the solid dispersions was also evaluated to compare the rate and extend of drug dissolution as a function of method of preparation. Thereafter, the effect of accelerated stability conditions on the physicochemical properties of the solid dispersions were also evaluated. The results demonstrated higher stability of Soluplus^® (SOL) polymer-based solid dispersions as compared to hydroxypropyl methylcellulose (HPMC)-based solid dispersions. Moreover, the stability of the solid dispersions was found to be higher in the case of API having high glass transition temperature (Tg) and demonstrated higher interaction with the polymeric groups. Interestingly, the stability of the melt-extruded dispersions was found to be slightly higher as compared to the SD formulations. However, the down-processing of melt-extruded strands plays critical role in inducing the API crystal nuclei formation. In summary, the findings strongly indicate that the particulate properties significantly influence the performance of the product. Full article