Experimental investigations of the photoelectric properties of CdGa2S4 single crystals were carried out. The study examined the temperature dependence of the photocurrent (within the 110–420 K range), as well as the spectral dependence and transient characteristics of optical quenching at T = 300 K. Optical quenching of the photocurrent was observed within a secondary light beam energy range of 0.6 - 2.49 eV. Measurements revealed energy levels at Ec - 0.21 eV, Ec - 0.42 eV, and Ec - 1.06 eV, as well as sensitizing levels at Ev + 0.89 eV. The decrease in photocurrent at temperatures above 300 K is attributed to thermal quenching. Both optical and thermal quenching of photoconductivity in CdGa2S4 crystals are ascribed to changes in the charge state and exchange dynamics of sensitizing and recombination centers.
ZnFe2-xYbxO4 with (x = 0, 0.01, 0.02, 0.03, 0.05, 0.07, and 0.09) have been successfully synthesized by the sol-gel method at 750°C. X-ray diffraction results showed a single phase and crystalline nanopowders of spinel-type structure with cubic symmetry and space group . The lattice parameters increase with Yb3+ concentrations. The BET specific area of ZnxFe2-xYbxO4 (x = 0.03) was determined to be the larger 13.59 m2/g. The crystallite size was determined by Rietveld to be in the range of 29-104 nm. FTIR spectra showed two strong absorption bands, a common characteristic of the spinel structure. Further, the shifting of the lower absorption band toward a higher frequency confirms that Yb3+ ions predominantly replaced Fe3+ ions in octahedral sites. The formation of the spinel phase in the samples was also validated by Raman scattering, with asymmetric broadening, and a systematic shift in the Raman spectra was observed as a function of Yb3+ concentration. Scanning electron microscopy SEM showed that powders consist of micrometric aggregation of smaller particles. EDS examinations verified that the chemical elements Zn, Fe, Yb, and O are present in all samples. The direct bandgap energy values are calculated by Tauc’s plot, and it indicates a semiconductor character of our compound, revealing an increase and enhancement in bandgap energy values from 1.82 to 2.4 eV with Yb3+ substitution.
A deformation (strain) model of the spectrum of the density of localized states Nss(E,X) in p-Si(B,Mn) under uniaxial pressure X is presented. It is shown that shifts of trap levels can be described by the deformation energy Ed = kappa X, a mechanical analog of kT. At a fixed temperature T = 77 K, increasing X leads to a shift and restructuring of the spectrum: thermodonor (TD) levels move toward the conduction band, whereas manganese (Mn) levels shift toward the valence band, which agrees with the opposite trends observed in rho(X) and mu(X).
The interaction behavior of 1.25 MeV Co ions with Si, ZnO, and Mg-doped ZnO (ZnO:Mg) targets has been systematically analyzed using the latest SRIM 2013 simulations. The findings show that atomic displacements, the production of vacancies and energy loss are greatly influenced by the composition and structural density of the target. The results reveal that the highest number of atomic displacements is observed in crystalline Si, followed by ZnO, whereas Mg-doped ZnO exhibits the lowest displacement level. On the other hand, ZnO exhibits moderate defect generation, as its high atomic density and bonding energy make it harder for the lattice to become disordered. Moreover, the presence of Mg in the ZnO matrix slightly reduces overall damage, indicating that the lattice is more stable and tolerant to radiation. These results indicate that Mg doping improves the structural robustness of ZnO against high-energy Co-ion bombardment, thereby making ZnO:Mg films more appropriate for radiation-resistant optoelectronic and sensing applications.
Background: HDR brachytherapy represents a cornerstone in prostate cancer management by enabling high tumor doses while sparing surrounding normal tissues. Radiobiological modelling allows quantitative assessment of tumour control and normal tissue complication probability for optimization of fractionation schedules. Objective: The purpose of this study is to comparatively appraise the radiobiological outcome of two HDR brachytherapy regimens, 13.5 Gy × 2 fractions versus 15 Gy × 1 fraction, regarding tumor control probability, normal tissue complication probability, and dose-effect metrics in patients presenting with intermediate- to high-risk prostate cancer. Materials and Methods: A retrospective analysis of 20 patients treated by Co-60 HDR brachytherapy was performed. The treatment planning was image-based, in which, target and organ-at-risk delineation was followed standard guidelines. BED, EQD2, and Deff were computed using the linear-quadratic model. TCP and NTCP modeling utilized Poisson-based and Lyman–Kutcher–Burman methods, respectively. Correlations between radiobiological parameters and TCP/NTCP were analyzed. Results: The single 15 Gy fraction regimen resulted in significantly higher BED, EQD2, Deff, and modeled TCP compared with 13.5 Gy×2 fractions (p ≤ 0.031). However, NTCP for urethra at 10% volume was higher in the 15 Gy group (8.42% ± 1.58 vs. 6.86% ± 1.24; p = 0.006). Strong positive correlations were observed between BED, EQD2, Deff and TCP (ρ = 0.984–1.000; p < 0.001). NTCP at 30% urethral volume negatively correlated with BED, EQD2, and Deff (ρ ≈ -0.52; p = 0.003). Conclusions: Higher radiobiological doses (BED, EQD2, Deff) in prostate HDR brachytherapy are strongly associated with improved tumor control, with Deff showing perfect correlation with TCP. A single 15 Gy fraction yields greater radiobiological effectiveness than 13.5 Gy × 2. Urethral toxicity shows no clear correlation at 10% volume but a strong negative correlation at 30%, indicating that higher doses may reduce toxicity at this level. Radiobiological modeling is thus valuable for optimizing HDR planning, enhancing tumor control prediction, and balancing urethral toxicity.
The study investigates the spectral distribution of photoconductivity, optical quenching, transient characteristics, thermally stimulated currents, and the temperature dependence of both dark and photocurrent in Cu-doped CdIn2S4 single crystals. Detailed analysis of the experimental data reveals the presence of deep donor levels with ionization energies located at Ес - 0.17 eV, Ес - 0.66 eV, Ес - 1.2 eV, and Ес - 1.55 eV. At 110 K, optical quenching of the photoconductivity was observed within the photon energy range of 0.86 to 1.63 eV. The energy positions of the photosensitivity centers relative to the valence band maximum were identified, yielding optical ionization energy of Eovr = 0.86 eV and a thermal ionization energy for the r-type levels of Etvr = 0.62 eV. The capture cross-sections ratio for holes and electrons at these r-centers was found to be Spr/Snr = 5×104. Both optical and thermal quenching phenomena are attributed to charge-state transitions and carrier-exchange dynamics between slow (r) and fast (s) recombination centers. The well-defined electronic structure and high photosensitivity of Cu-doped CdIn2S4 single crystals suggest they are promising candidates for advanced photodetector applications in the visible and near-infrared spectral regions.
This work presents a comprehensive experimental and theoretical investigation of polylactide (PLA) nanocomposites reinforced with zinc oxide (ZnO) nanoparticles at concentrations of 0.5, 1, 3, and 5 wt.%. The dispersion state and microstructural features of ZnO within the PLA matrix were examined using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, revealing homogeneous distribution at low filler contents and progressive agglomeration at higher loadings. X-ray diffraction analysis confirms that ZnO preserves its hexagonal wurtzite crystal structure after incorporation into the polymer matrix, while compositiondependent variations in crystallite size and lattice microstrain are found to correlate with the mechanical response of the composites. Fourier-transform infrared spectroscopy indicates interfacial interactions between PLA chains and ZnO nanoparticles, as evidenced by systematic shifts in the carbonyl stretching band and associated charge redistribution. Ultraviolet-visible spectroscopy demonstrates a significant enhancement of UV-shielding performance with increasing ZnO content, accompanied by the emergence of sub-bandgap absorption tails attributed to defect-related and interfacial electronic states. Density functional theory calculations support the experimental observations by revealing interfacial charge transfer and a slight modification of the electronic structure at the PLA/ZnO interface. The results show that ZnO incorporation improves both mechanical stiffness and UV-blocking efficiency, while an optimal ZnO loading below 1 wt.% is identified to maintain mechanical integrity and minimize agglomeration-induced degradation.
The quality of MRI images is often limited by spatially inhomogeneous noise, which negatively affects the accuracy of clinical interpretation and automatic analysis. Traditional deep learning methods often implicitly account for noise, leading to excessive smoothing and the loss of fine anatomical structures. In this paper, we propose an Enhanced Denoising U-Net architecture that employs a Feature-wise Linear Modulation (FiLM) mechanism to dynamically adapt to the noise profile of each slice. The model combines a vector of 8 statistical descriptors (including intensity, texture, and frequency characteristics), enabling dynamic control of the network’s internal representations based on specific scanning conditions. To improve physical correctness, training was performed on data with synthetically generated k-space noise. The architecture is enhanced with residual blocks, attention mechanisms, and a multiscale processing module. On synthetic data, the average Peak Signal-to-Noise Ratio (PSNR) improvement was ≈ 20.7 dB, and with an average Structural Similarity Index (SSIM) improvement of approximately 0.73, indicating a deep restoration of structural information. In clinical images, an increase in SNR and stabilization of the coefficient of variation (CV) were observed, confirming the method's physical correctness. Clinical validation on complex contoured structures (hippocampus, brainstem, optic chiasm) showed an increase in the Dice coefficient (DSC) by 0.07–0.12 and a decrease in the HD95 error by 30–50%. The proposed method enables a transition from universal denoising strategies to adaptive reconstruction, ensuring high accuracy of preserving anatomical boundaries. This makes it a promising tool for MRI processing in neuroimaging tasks and variable therapy planning.
Cu1.85S is of significant current interest due to its complex crystal chemistry, wide homogeneity range, and unique physicochemical properties. These materials belong to the class of digenites and exhibit various structural transformations and reversible phase transitions that are highly sensitive to copper content. The synthesis, growth, and investigation of the structural behavior of Cu1.85S single crystals provide essential insights into phase stability and transformation mechanisms in the Cu2-xS system. Such knowledge is crucial for potential applications in semiconductor devices, catalysts, and energy conversion systems, where the crystal structure and phase composition directly influence material performance. This paper presents the results of the synthesis, growth of single crystals, and X-ray phase analysis of the nonstoichiometric compound Cu1.85S, which belongs to the class of digenites. The single crystals were obtained by combining the Bridgman directional crystallization method with slow cooling. A comprehensive microstructural and X-ray analysis was carried out, including the use of Weissenberg photographs and temperature-dependent diffraction studies in the range from room temperature to 420℃. It was established that at room temperature, the Cu1.85S sample is biphasic and consists of orthorhombic (Pnma) and monoclinic ( ) phases. Upon heating, two structural transitions were observed: first to a tetragonal phase at approximately 93℃, and then to a high-temperature face-centered cubic (FCC) lattice at around 120℃. All transitions are reversible and occur via a single-crystal-to-single-crystal mechanism with well-defined orientational relationships between the lattices. The biphasic nature at room temperature is attributed to the accumulation of copper atoms in twin regions. This work contributes to understanding structural transformations in the Cu1.85S system and confirms the existence of stable interphase transitions that depend on copper content.
Laser-induced graphene (LIG) enables mask free direct writing of conductive carbon structures on polyimide substrates for flexible electronic and sensing applications. In femtosecond laser-induced graphene (FLIG), the scanning speed strongly affects the local temperature field, and thus the extent and quality of graphitization, but this dependence is still not fully quantified. In this study, a time dependent finite element model is implemented in COMSOL Multiphysics to resolve the temperature distribution generated by a femtosecond laser beam on a polyimide surface as a function of scanning speed. The laser is described as a moving Gaussian surface heat source, and the transient heat conduction equation is solved to capture ultrafast heating and cooling during a pulse train. Simulations for scan speeds between 0.05 and 0.20 m/s show that decreasing the speed increases the peak temperature and enlarges the heat affected zone, whereas higher speeds reduce both quantities. By comparison of the predicted peak temperatures with the graphitization thresholds in the literature for polyimide derived graphene, an intermediate scan speed window is identified in which the thermal budget is sufficient for graphene formation while avoiding excessive overheating and damage. This modeling framework provides a practical tool for pre selecting femtosecond laser parameters and for accelerating the optimization of FLIG processes for flexible graphene based devices.
This paper considers the influence of hydrostatic pressure on the energy spectrum of the density of localized states in doped silicon nSi, n-Si < Ni > and p-Si < B,Mn >. Based on the experimental dependence of the relative resistivity rho(p)/rho 0 on pressure, a model is constructed in which pressure enters via the deformation energy Ed = kappa P, yielding a linear shift of the trap levels Ei(P) = Ei(0)+alpha iEd. It is shown that for different impurity centers (Mn, Ni) the deformation sensitivity of the levels differs in both sign and magnitude, which is manifested in qualitatively different behavior of rho(p)/rho 0(P). A procedure is proposed for reconstructing the relative electron concentration N(P)/N0 and the associated spectrum N-ss(E,P) from the experimental rho(p)/rho 0(P) curves. A comparison is made with the conventional temperature DLTS model, and the possibility of using a "tenso-DLTS" approach to identify donor and acceptor centers, their deformation potentials and symmetry is substantiated. The results demonstrate that hydrostatic pressure is not only an external perturbation, but also an effective spectrum-forming parameter for controlling the electronic properties of doped silicon.
In this work, the effects of 0.5 wt.% Sn and 0.16-0.23 wt.% As on tensile properties of Pb-3.5%Sb grid alloy for lead-acid batteries were compared in the as-cast condition. The alloys were melted under different cooling-rate conditions in a casting mold preheated between 50 degrees C and 170 degrees C, with cooling rates ranging from 100 degrees C/s to 50 degrees C/s. Mechanical properties, such as ultimate tensile strength and percentage elongation, were measured at room temperature using the TIRAtest 2300 universal testing machine at a constant crosshead speed of 10 mm/min. It was established that as mold preheating temperatures rise, the elongation and ultimate tensile strength of the Pb-3.5%Sb-0.23%As alloy decrease by 13.9% and 11.8%, respectively. Addition of tin in place of some arsenic causes a decrease in ultimate tensile strength of the Pb-3.5%Sb-0.5%Sn-0.16%As alloy, but only by 2.8 %, whereas elongation increases by 2.4 %. It was concluded that additions of tin compensate for the negative effect of arsenic on the tensile properties of the Pb-3.5%Sb grid alloy, which relates to the formation of brittle arsenic-containing phases at the grain boundaries. Tin addition to the Pb-3.5 %Sb alloy produces higher tensile properties at room temperature than those obtained by the addition of arsenic.
This study investigates Sharma-Mittal Holographic Dark Energy (SMHDE) within the context of Brans-Dicke theory of gravitation in an Axially Symmetric Cosmological Model. By employing Sharma-Mittal entropy, which provides a unifying generalization of Tsallis and Renyi entropies, a modified form of holographic dark energy density is formulated to incorporate non-extensive thermodynamic effects. The corresponding field equations are derived and solved to obtain exact analytical solutions. Furthermore, key cosmological parameters such as the EoS parameter, deceleration parameter, and squared speed of sound are systematically analyzed to examine the dynamical behaviour and stability of the model. The results indicate that the proposed framework successfully describes the late-time accelerated expansion of the cosmos while also accommodating possible anisotropies in the early cosmos. Overall, the model presents a consistent and physically viable extension of conventional holographic dark energy scenarios within scalar-tensor gravitational theory.
This paper presents the theoretical investigation of the temperature-dependent shift of the Fermi level in porous silicon (por-Si). The study is based on the charge-state distribution model originally proposed for hydrogenated amorphous silicon (a-Si:H), with consideration of the unique physical and chemical properties of porous silicon (por-Si). The temperature dependence of the parameters in the charge-state density within the bandgap is accounted for in both simplified and advanced models. For each model, the Fermi-level shift behavior was calculated using numerical methods based on integral-differential equations. The results are presented in graphical form, and the physical mechanisms underlying the Fermi level shift across different temperature ranges are discussed. The conclusions obtained can be applied to explain carrier transport processes, reduce surface recombination, and improve the efficiency of por-Si/c-Si heterostructure-based solar cells.
The structural, mechanical, and optoelectronic properties of cubic halide perovskites AHgCl3 (A = Rb, Cs) were investigated using density functional theory (DFT) within the full-potential linearized augmented plane wave (FP-LAPW) method, as implemented in the WIEN2k code. The structural stability of the cubic phase was confirmed using the Goldschmidt tolerance factor and the octahedral factor, while the negative formation energies verified their thermodynamic stability. The calculated elastic parameters, including Poisson's ratio, Pugh's ratio, and Cauchy pressure, indicate that both compounds are mechanically stable, ductile, and exhibit a predominantly ionic bonding nature. The optoelectronic properties were examined using the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. The results reveal that RbHgCl3 and CsHgCl3 are indirect-band-gap semiconductors with band gaps of 1.25 eV and 1.16 eV, respectively. Furthermore, the optical properties were analyzed over the photon energy range of 0-20 eV. Both compounds exhibit strong absorption in the ultraviolet region and low reflectivity at zero photon energy, indicating favorable performance for optoelectronic applications. Overall, these findings suggest that AHgCl(3) (A = Rb, Cs) halide perovskites are promising candidates for applications in photovoltaic devices and ultraviolet photodetectors.
Irradiation of the industrial aluminum alloy AA6111 with a high-current pulsed electron beam (HCPEB) with particle energy of 0.35 MeV, a beam current of 2.0 kA, a pulse duration of 5 mu s, and a beam diameter of 3 cm results in the formation of a surface layer with improved physical and mechanical properties. However, the potential formation of craters on the surface of HCPEB-treated materials is one of the negative effects caused by HCPEB. This study examines the types and morphology of craters formed on the surface of AA6111 aluminum alloy after irradiation with HCPEB. The distribution of crater sizes and the crater density on the irradiated surface were studied. An analysis of the elemental composition of the crater walls and the adjacent melted surface was performed. The features of the grain microstructure, including shape and size, in the crater area were studied. The implications of these observations for a deeper understanding of the mechanisms underlying crater formation during HCPEB irradiation are discussed.
In this work, the photovoltaic properties and short-circuit current spectra of indium (In)-doped CdTe films were comprehensively investigated. The study covers the spectral sensitivity and light-absorption characteristics of undoped, freshly prepared, and thermally treated CdTe:In films. The effects of doping level and thermal treatment temperature on photovoltaic effect parameters were analyzed. The results showed that indium doping and subsequent thermal treatment significantly improve the photovoltaic efficiency of CdTe films. Using spectroscopic and electron microscopy methods, the chemical composition, surface morphology, and bandgap width of the films were determined, and their interrelation with optical and electrical properties was revealed. The obtained results indicate that CdTe: In films are promising for applications in solar energy devices.
A computationally efficient framework for optimizing multilayer radar-absorbing structures based on periodic planar gratings of resistive strips embedded in a dielectric slab is presented for the H-polarization case. The electromagnetic response is modeled using a rigorous singular integral equation (SIE) formulation combined with an operator-based cascading technique, providing high numerical accuracy and stability with low computational cost. This ultra-fast forward solver is integrated into a parallel differential evolution (DE) optimization framework implemented in a client-server architecture, enabling efficient solution of high-dimensional inverse design problems. The optimization targets broadband absorption under normal incidence while preserving optical transparency, with graphene used as a representative resistive material. Numerical results demonstrate effective suppression of resonance-induced spectral holes and stable, wideband absorption in multilayer structures with 10 layers, showing robustness under fabrication-inspired constraints and oblique incidence.
The crystal structure and thermophysical properties of the chalcogenide semiconductor Cu2NiTe2 were comprehensively investigated using X-ray diffraction and differential scanning calorimetry. Structural characterization at room temperature revealed that the synthesized compound crystallizes in the hexagonal crystal system with the space group P6(3)/mmc, indicating the formation of a highly ordered polycrystalline phase. The diffraction peaks were sharp and well-defined, confirming the material's good crystallinity and structural homogeneity. The absence of additional impurity peaks in the diffraction pattern also suggests that the synthesized compound possesses a predominantly single-phase structure.
In this work, we investigated synthesized porous aluminosilicate materials containing burnable additives, which form a single-phase cubic zeolite structure (Fm3m, a=4.056 Å). The porous ceramic with a zeolite composition at 200°C and a hydrogen pressure of 12 atm exhibited hydrogen absorption of 11 wt.%. We also studied the initial metallic lithium (BCC, a ≈ 3.507 Å), which was subjected to hydrogenation in the developed sealed reactor at 12 atm and 700 °C with the formation of LiH hydride (FCC, NaCl type, a ≈ 4.081 Å, d111 ≈ 2.356 Å). The average size of LiH crystallites does not exceed 100 nm, and the maximum hydrogen capacity of lithium reached 12.4 wt.%. The developed reactor enables safe, high-temperature, high-pressure hydrogenation. These data demonstrate the potential of lithium, titanium, and sodium hydrides, and porous aluminosilicates for the accumulation, storage, and transportation of hydrogen.
