Modern Physics Letters B

Magnetic properties of Ag₂S doped with 3d-transition metals were studied using density functional theory (DFT). It was found that magnetic elements such as Co, Cr and Mn cause magnetism in the structure. The nature of this magnetism is mainly from the 3d-states of the magnetic elements. The magnetic moment of supercells containing various concentrations (x= 2.08%, 4.1%, 8.3%) of dopant atoms has been studied. It was determined that the contribution of the magnetic elements is significant in the total magnetic moment of supercells. Calculation results reveal that when doped with impurity atoms, supercells show half metallicity and ferromagnetic (FM) nature which makes them the best candidate to be used in the field of spintronics.

Iron oxide (FeO) nanoparticles have gained considerable interest from researchers over the past few decades and have a massive effect on wave absorption materials, magnetic fluid, adsorbent, and a variety of industrial applications. In this study, ferric nitrate, sodium hydroxide, and ammonium hydroxide coalesced to form FeO nanoparticles using the chemical co-precipitation approach. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), UV-VIS analysis, Photoluminesence (PL) spectrum analysis, and electrochemical measurements were used to characterize FeO nanoparticles. As per XRD, the sample’s crystallite size was 22.63nm and 22.64nm after it was annealed at 300^∘C and 400^∘C, respectively. Utilizing XRD, the diffraction patterns were seen. The particles appear to have a fine surface and smooth shape, as seen by SEM photographs. For the detection of FeO nanoparticles, optical and electrochemical examinations were carried out.

Excellent properties of gallium nitride (GaN) make it an ideal material for realizing gas sensors, especially for ammonia (NH${}_3)$ detection. Although many researchers have pursued to describe the characteristics of GaN-based NH₃ gas sensors by different approaches, few models have been reported. In this paper, with the consideration of the exponential distribution of interfacial states, a model for ammonia concentration detection of GaN gas sensors has been presented. The Poisson equation is applied to model the effect of defect states on the potential. By taking advantage of the current-voltage characteristics, the value of Schottky barrier height can be obtained. The concentration of the adsorbed NH₃ gas is derived by exploiting the surface potential. It indicates that densities of acceptor interfacial trap states are in the order of 10${}^{11}\sim 10^{12}$cm${}^{-2}$eV${}^{-1}$. The current increases with the NH₃ concentration at the same applied voltage. In addition, detailed investigations of physical mechanisms and the analysis of the sensitivity have been depicted. It shows that the sensitivity followed an approximately exponential dependence on NH₃ density. Results compared well with experimental data that verify the proposed model and simulation method.

Due to the increasing importance of nanosensors in the early diagnosis of diseases, the need for high-performance nanosensors is one of the goals of researchers. In this paper, a structure consisting of plasmonic nanoshells with spherical and ellipsoidal geometry has been proposed to calculate the refractive index (RI) changes in the range of 1–3. The sensitivity of the proposed nanosensor has been computed, and the effective factors on the performance of the nanosensor, including geometry, material, core dimensions, shell thickness, and RI of the surrounding environment are studied. To this end, various nanostructures have been modeled using the boundary element method. It has been shown that ellipsoidal nanoshells are more sensitive to RI changes than spherical nanoshells. Also, the results show that nanoshells with a core and shell made of plasmonic metals (bimetallic nanoshell) can exponentially increase the sensitivity of the nanosensor.

Taking the advantages of loop quantum gravity (LQG), the quasinormal mode frequency spectrum of black holes is studied with the first law of thermodynamics of black holes by calculating the tunneling rate. With the minimum event horizon area interval given by LQG, our results show that one group of the quasinormal mode spectrum for Kerr–Newman black hole depends only on the outer horizon parameters of the black hole. Choosing the minimum spin properly, we derive the quasinormal mode completely consistent with the present results. More importantly, our results show that the quasinormal modes of black holes should have a series of separated frequency spectra, which further proves that the space-time of black holes is quantized.

In this paper, we mainly focus on analyzing the fidelity, parity measurement, phase sensitivity and entanglement properties of the output states corresponding to three quantum superposition coherent states, i.e. even coherent state (ECS), Yurke-Stoler state (YSS) and odd coherent state (OCS). Our results show that the OCS characterizes super-resolution in the phase measurement via parity measurement at the output ports of a Mach–Zehnder interferometer. In addition, we find that the optimal phase sensitivity may approach the Heisenberg limit which is independent of the superposition coefficient of the coherent states. An interesting finding is that the macroscopically entangled coherent states can be experimentally prepared by adjusting the parameters of the nonlinear phase shifter of the MZI.

Membrane wetting by liquid absorbents limits the performance of membrane contactor, which shows the necessity of using superhydrophobic membranes in these systems. In recent years, the use of plasma irradiation to modify polymer membranes has received much attention from researchers. In this experimental research, the polypropylene membrane surface was irradiated with CF₄ plasma at different times to reduce the membrane wetting and create a superhydrophobic surface. The modified membranes were evaluated in terms of measurements of roughness and morphology, chemical properties, and hydrophilicity. In the results of the AFM and SEM tests, the structural difference caused by the surface modification and the resulting roughness can be well observed. The FTIR results showed the creation of new functional groups due to the surface modification process. The physicochemical changes of the modified surface led to an increase in the CA to 166^∘. Finally, the performance of modified membranes was evaluated for protein adsorption, and the results indicated a significant decrease in adsorption for modified superhydrophobic membranes compared to the control membrane. Achieving superhydrophobic PP membranes by plasma treatment without damaging the physical structure of these membranes is a significant result that is simply not achieved by other methods because it causes the membrane tissue to disintegrate. It has also been shown that the conditions of plasma application play a decisive role in the hydrophobicity of modified surfaces.

Based on density functional theory, the effects of tensile deformation on the stability, electronic properties and optical properties of $\beta$-Be₃N₂ adsorbed O atom system were investigated. The results show that the structure of $\beta$-Be₃N₂ is deformed because of the O atoms’ adsorption, which pulls up the Be atoms and repels the N atoms, leading to the re-hybridization of the N atoms with the Be atomic orbitals, thus changing its bandgap. With tensile deformation, the adsorption energy of $\beta$-Be₃N₂ adsorbed O atom system decreases with increasing tensile deformation, and the stability of the system increases. The energy bandgaps of $\beta$-Be₃N₂ adsorbed O atom system and $\beta$-Be₃N₂ systems exhibit different trends of change, respectively. As the stretching rate increases, the system’s maximum absorption and reflection peaks alter.