[en] Eu³⁺-doped Zn₂SiO₄/ZnO phosphor-based composites were prepared using a simple thermal treatment method. The effect of Eu³⁺ content on the morphological and photoluminescence performance was examined using XRD, FTIR, FESEM, UV-Vis, and PL measurement. The existence of two crystal phases by the XRD measurement confirmed the development of zincite (ZnO) and zinc silicate (Zn₂SiO₄) crystal phases. Besides, the FTIR spectra and FESEM micrograph support the XRD result by verifying ZnO and Zn₂SiO₄ phase formation through the existence of their characteristic Zn-O-Si and Zn-O vibration modes with the decrement of SiO₄ broad absorption band as the Eu³⁺ concentration increased. Also, UV-Vis absorption spectra presented by the composite samples displayed a broad absorbance that confirmed the addition of Eu!³⁺ ions in the ZnO/Zn₂SiO₄ has caused the absorption edge of the curve having red shift. The photoluminescence spectrum showed red shift light emissions at 485 and 615 nm, associating with the Zn₂SiO₄ crystal phase, in addition to the ZnO crystal phase. From the interesting results achieved, this ZnO/Zn₂SiO₄ phosphor-based composite material can be a potent candidate in optoelectronic applications. (author)

[en] In this paper, we investigate the study of glass properties compared to that of glass-ceramics with the composition of the system (in mol.%): 68 P₂O₅-20 ZnO-10 Li₂O-2 V₂O₅, which reveals interesting results. Glass sample was synthesized by quenched melt technique. The glass-ceramic composites contain fine nanocrystallites embedded in the glass matrix confirmed by XRD. The energy band gap and Urbach energy values were determined from their UV edges. Impedance spectroscopy was used, to investigate ionic conductivity and impedance measurements of the studied samples. The variation of electrical data, as a function of frequency and temperature, was analyzed using the Nyquist graph by applying Jonscher-s universal power laws and the Almond-West formalism. The ac and dc conductivities of all samples increase with increasing temperature indicating the presence of an ionic contribution. (author)

[en] The content and molecular state of paramagnetic ions were assessed by electron paramagnetic resonance (EPR) spectroscopy in ex vivo human brain samples from the globus pallidus, locus coeruleus, and substantia nigra. A dedicated pipeline of quantitative deconvolution and simulation-informed spectral fitting was employed to resolve five overlapping resonance peaks in the EPR signal present in the (whole tissue) brain samples. Simulated results showed good visual agreement with experimental spectral signals. Our quantitative analytical pipeline enabled theorizing understanding of the molecular roles of Iron and other ions in the evaluated specialized subcortical regions. Analysis of the absorption and linewidth of each peak-studied as a function of temperature-showed that four of these peaks behave like a Curie-Weiss paramagnet with an antiferromagnetic contribution, while a broader peak (centered at 320 mT) showed a strong antiferromagnetic behavior with ferro/ferrimagnetic contribution. Noticeably, a fifth peak, which shifts from 190 to 230 mT as temperature increases, was observed exclusively in the locus coeruleus region and can be specifically associated with a possible iron complex formed during the oxidation of dopamine. Our findings support the translational aspects of EPR to inform the cellular-molecular nature of Iron loads phenotypically visible in associated magnetic resonance susceptibility and relaxometry imaging techniques, that are broadly applied to the radiologic characterization of a plethora of neurologic disorders. (author)

[en] The aim of this paper is to study the effect of graded bandgap Al_xGa_1-xAs front layers on the optical properties and cell performance of a GaAs solar cell (SC) grown by molecular beam epitaxy on (111)A GaAs substrate. For comparison, a GaAs SC with the same structure but without graded bandgap Al_xGa_1-xAs layers was also grown. The two SCs were investigated by spectroscopic ellipsometry and photo-absorption techniques. The extracted optical constants and the calculated energy loss functions are interpreted as a function of photon energy in the photon energy range of 1-6 eV. The critical point energies are calculated and identified. SE results show that Al_xGa_1-xAs-graded layers have a major influence on conversion efficiency of the front-graded SC. Photocurrent results show that SC grown with graded bandgap Al_xGa_1-xAs front layers has much larger responsivity than that of the reference SC. Our results show that graded bandgap Al_xGa_1-xAs front layers can ameliorate performance of GaAs SCs grown on (111)A GaAs substrates due to the built-in electric field induced by the bandgap gradation. (author)

[en] In the present work, the intrinsic nuclear structures of the ^180–190W isotopes have been systematically investigated by employing the triaxial projected shell model within the deformed basis. The diagonalization of model Hamiltonian gives rise to yrast spectra, γ- and 2γ-bands which successfully describe the intrinsic band structure of these tungsten isotopes. In addition, the role of the i_13/2 neutron orbitals of the intruder major shell N = 6 in explaining nuclear structure properties is also highlighted. Further, other nuclear structure properties like back-bending in moment of inertia, interband and intraband transition probabilities, wave-functions, nuclear g-factors, etc. have also been calculated and are compared with the known experimental data to get an in-depth understanding of the intrinsic nuclear structure of ^180–190W isotopes. (author)

[en] Co₃O₄ nanorods and hybrid reduced graphene oxide (Co₃O₄/rGO) were synthesized on a Ni foam substrate using affordable and simple hydrothermal synthesis. Then, the structural and morphological investigations of nanoparticles were carried out using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) mapping, Raman spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. It was found that rGO increased the surface and short channels for the transfer of ions and electrons. The maximum capacitance of Co₃O₄/rGO was found to be 2870 F/g, while Co₃O₄/rGO/NF was observed to have the largest capacitance in the literature. Furthermore, rGO decreased resistance arising from charge and ion transfer by creating shorter channels. Therefore, the superior Co₃O₄/rGO/NF electrode in the tow-electrode system was investigated for asymmetric supercapacitor purposes. The rGO electrode served as the negative electrode, while the Co₃O₄/rGO/NF was assumed to be the positive electrode. A discharge time of 144 s led to a capacitance of 148 F/g, a power density of 486 W/kg, and an energy density of 20 Wh/kg. (author)

[en] Terahertz radiation generation by the interaction between Hermite-cosh Gaussian and hollow Gaussian laser beams in magnetized inhomogeneous plasmas is investigated. The inhomogeneity of the plasma density is sinusoidal on its surface, and the inhomogeneity of the external magnetic field is radial. Coupling between two laser beams can create a nonlinear ponderomotive force. Considering the nonlinear ponderomotive force, continuity, and momentum transfer equations, the nonlinear velocity and nonlinear plasma density are obtained. The nonlinear plasma density can produce a space-charge force that creates linear velocity and linear plasma density. By considering the above plasma densities and velocities, the nonlinear current density is obtained, and using the dielectric tensor and wave equation, the components of the generated terahertz electric field are achieved. Results show that by increasing the external magnetic field, the amplitude of the radial component of the generated terahertz electric field increases. Also, by increasing the decenter parameter, the amplitude of the electric field increases. By integrating the square of the generated terahertz electric field, the efficiency of the terahertz radiation is obtained and plotted for different values of the amplitude of the rippled density and the half-width of the initial laser pulse. (author)

[en] The present work evaluates the nitriding and deposition of niobium and vanadium films using the cathode cage technique and its influence on the formation of a double film generated from these two sequential treatments (duplex film) on AISI D2 steel substrates. The element niobium has attracted research because Brazil has the most significant deposits of this ore in the world, and the properties of this element are important for several applications. For example, niobium nitride has excellent properties such as high hardness and toughness, thermodynamic stability, and wear and corrosion resistance. Another nitride film that stands out due to its excellent properties is vanadium nitride (VN), which presents better corrosion resistance and reduced friction coefficient at high temperatures and favors high-speed machining. This work evaluated the wear resistance, microstructure, adhesion and composition of the deposited layer, and microhardness. (author)

[en] We investigated cross-sectional optical coherence tomography (OCT) images to determine the attenuation coefficients of moist and dry sound bovine teeth under near-infrared laser illumination. We acquired OCT images of the samples using a commercial swept-source OCT equipment, with a central wavelength of 1300 nm. In order to determine the attenuation coefficient of the samples, we studied the attenuation of light as it traveled through the dental tissue. The method considers only backscattered light, which restricts the contributions of speckles and reflective dispersion. To minimize errors related to the OCT equipment and because the operation influences the measurements, we revised various practical details associated with the OCT technique. Our results revealed significant differences between the attenuation coefficients of the dry and moist samples. We interpreted the values measured for dry/moist dentin (24.3/13.2 cm^-1) and dry/moist enamel (3.1 /2.1 cm^-1) based on the optical properties of the tooth. These differences were due to modifications in the optical properties of natural tissues when water evaporates from the tooth. The measured values can help us to obtain accurate optical parameters for in vivo and in vitro optical dental diagnosis techniques and therapies that use longer wavelengths. (author)

[en] Although the Pöschl-Teller potential is widely known for its ability to describe diatomic molecular energy spectra and vibrational excitations, the current effort focuses on parameterizing the above-mentioned potential for nuclear systems. The differential equation methodology to the problem in the representation space leads to the derivation of regular and Jost solutions for the Pöschl-Teller potential. For nucleon-nucleon and nucleon-nucleus systems, bound state energies and scattering phase shifts are computed using the derived Jost function. Using the phase parameters, the elastic scattering cross sections and analyzing powers have been calculated. The outcomes closely match the experimental ones. (author)