Abstract. A nonlocal nonlinear Schrödinger (NNLS) equation with fourth-order dispersion and cubic-quintic nonlinearities has been studied analytically and numerically. Under the constraint conditions, auxiliary functions are introduced, and explicit one- and two-soliton solutions are obtained by the Hirota bilinear method. According to the solutions, the propagation dynamics of soliton pulses are investigated. The influences of different parameters on the dynamics of one- and two-soliton solutions have been analyzed. The results show that the two-soliton solution exhibits diverse dynamic characteristics under the suitable parameter selections. In addition, the stability of one- and two-soliton solutions against the constraint conditions deviations and under the initial perturbations are also studied numerically.

Abstract. The present work aims to examine a newly proposed (3+1)-dimensional integrable generalized Korteweg-de Vries (gKdV) equation. By employing the Weiss-Tabor-Carnevale technique in conjunction with Kruskal ansatz, we establish the complete integrability of the suggested model by demonstrating its ability to satisfy the Painlevé property. The bilinear form of the (3+1)-dimensional gKdV equation is employed to construct multiple soliton solutions. By manipulating the various values of the corresponding parameters, we generate a category of lump solutions that exhibit localization in all dimensions and algebraic decay.

Abstract. In this paper, we prove the existence of tau functions of the discrete modified Kadomtsev-Petviashvili (KP) hierarchy. Meanwhile, the Fay identity with its difference form, the squared eigenfunction potentials, and the symmetry flows acting on tau functions are obtained.

Abstract. This article deals with a simultaneous reconstruction of unknown initial conditions and space-dependent source function in multi-order time-fractional diffusion problems. We discuss the existence and uniqueness of the direct problem. The problem is presented as a regularized optimization problem and converted into a variational problem. The existence of the minimizer for the optimization problem is demonstrated. For the numerical part, a modified Levenberg-Marquardt regularization approach is constructed to identify the initial condition and source function. Several numerical examples in one and two dimensions are employed to test the performance of the identification technique.

Abstract. In this study, we delve into the ionization dynamics of noble gases exposed to an 800 nm sine-squared laser pulse, placing emphasis on the influence of the Coulomb interaction on the ionization rate. Calculations are conducted under two conditions: one with and the other without considering the Coulomb potential. The results reveal the significant role of the Coulomb interaction in the dynamics of ionization. Our findings foster a deeper understanding of ionization processes within intense laser fields and aid in enhancing our existing theoretical frameworks.

Abstract. The transverse momentum distributions of identified hadrons (π^±, K^±, p, p, K⁰_S, Λ, Λ, Ξ⁻, Ξ⁺, φ, Ω⁻, and Ω⁺) produced in Au+Au collisions at RHIC-BES energies are analyzed with Blast-Wave model and with Boltzmann-Gibbs statistics. The kinetic freeze-out temperature, the average transverse flow velocity and the flow profile exponent are extracted from the transverse momentum spectra of the particles. The study of system-size dependence of the kinetic freeze-out parameters showed that kinetic freeze-out temperature increases, while average transverse flow velocity decreases from central to peripheral collisions. The larger freeze-out temperature for peripheral collisions may indicate an earlier decoupling of the expanding system. For the same centrality class, it is observed that the transverse flow velocity and flow profile exponent have an increasing trend with increasing collision energy.

Abstract. In lieu of the traditional method of data encryption using Hadamard matrices we here propose a method which change in the encryption part mathematical with physical means, namely the mathematical Hadamard transform with the physical Fourier transform using a lens. The Fourier transform has a lower power of compression, but the advantage of using physical encoding compensated for this disadvantage. Our approach has two parts, an encryption-compression stage, and a decryption-decompression stage, which are supposed to be complementary and are coupled by means of a computer which controls both experiments and uses the output of the encryption-compression stage as input for the decryption-decompression stage.

Abstract. An approximation previously proposed by Garrett to evaluate the energy level of a particle in a finite square well using the expression of the corresponding level in an infinite one is extended to a spherical well. In this way, simple analytical approximations are obtained for the energy levels of a particle in a spherical cavity with penetrable walls, knowing the exact values of the corresponding levels in a similar cavity, with impenetrable walls. The relative errors of this approximation are of order of about 10⁻³. This approach can be extended to slightly deformed spherical dots (ellipsoidal dots with a small eccentricity), with interesting applications in nanophysics and nanotechnology.

Abstract. Developing nanocomposite materials based on conducting polymers (CPs) and metal-oxide nanoparticles, which combine redox electrochemistry of CPs with intrinsic properties of nano-scale semiconducting materials, may offer improved microbial fuel cells (MFCs) performances. Polypyrrole (PPY) based nanocomposites were synthesized by chemical oxidative polymerization method and were further used as an anode modifier in salt bridge MFCs. The PPY-based nanocomposites were characterized by X-ray diffraction, Fourier-Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscopy (SEM). The maximum power density of 16.7 mW/m², 20.1 mW/m², and 22.5 mW/m² were obtained for MFC2-PPY, MFC3-PPY/TiO₂ and MFC4-PPY/WO₃ respectively, suggesting that modification of the anode with PPY-based nanocomposites is beneficial in the electricity generation of the MFC, and have superior performance as compared to the controller MFC1-CC (11.6 mW/m²).

Abstract. We theoretically investigated the influence of pressure and temperature on the electronic and optical properties of a GaAs/Al_0.3Ga_0.7As quantum ring, described by a combination of a parabolic potential and an inverse square one, in the presence of the magnetic field. The results reveal a variation with pressure and temperature of the period of Aharonov-Bohm oscillations appearing in the electronic spectra in magnetic field. This period varies nonlinearly with pressure and temperature. In the absorption spectra and refractive index variation at 4 K, we found that with the increment of the magnetic field or of the pressure more transitions are allowed. When no external pressure is applied, the absorption maxima shift to lower energies at increasing magnetic field, but with increasing pressure, the absorption maxima red-shift at intermediate magnetic fields and blue-shift at high fields.

Abstract. Whole brain irradiation is largely used as an alternative radiotherapy of brain tumors that cannot be eliminated by surgery so the effects of ionizing radiation on brain healthy tissue represents an important research domain. The aim of this study is to evaluate the irradiation effects on in vitro brain tissue spheroids models as well as the whole mouse brain using standard cellular biology assays and a multi-energy X-ray imaging technique. The spheroids irradiated with gamma rays (dose between 0―30 Gy) and treated with biocompatible nanoparticles consisting of concentrations between 0―100 μM proved to be morphologically stable and with a high radio-resistance. The reactive oxygen species concentration and the γ-H2AX foci number increase with the irradiation dose, as expected. The X-ray imaging with dual-energy technique method proposed here was able to differentiate between irradiated and control samples (whole brain). Concluding, our results proved the expected effects of ionizing radiation on brain tissue. The dual-energy X-ray imaging method tested here appears as a promising method for characterizing the ionizing radiation effects on the whole brain level.

Abstract. Cellular metabolism implies a permanent transport through membranes of a great diversity of particles (e.g., ions, molecules, macromolecules, protein vesicles, etc.) in and out of the cells. The transport phenomena can be classified as passive (down the concentration gradients, driven solely by thermal agitation) or active (against the concentration gradients, driven by an energy supply) and selective (i.e., through specific pathways) or nonselective through membrane lipid bilayers. This paper will describe in an accessible manner all the types of membrane transport from a biophysical point of view along with their crucial roles in normal cellular functioning. This paper is the successor of a previous work (A. I. Popescu, C. G. Chilom, Rom. Rep. Phys. 75, 605 (2023), Ref. [1]) in a series aiming to disseminate Biophysics in an accessible manner.

Abstract. This study aims to provide a comparative analysis of two of the most used methods of spatial interpolation ― Thiessen Polygons (TP) and Inverse Distance Weighting (IDW) with a spatio-temporal approach ― Spatio-temporal kriging (STK) on a data series from Canada. The IDW parameter is optimized to obtain the best fitting for the studied series, based on the Root Mean Squared Errors (RMSE) and Mean Absolute Percentage Error (MAPE). The advantages and disadvantages of each algorithm are emphasized. Although TP registered the lowest RMSE and a MAPE, the analysis favors the STK use for modeling Montreal's maximum temperature series.

Abstract. This study aims to characterize urban air pollution in 33 cities across Romania in 2019 and 2020. The global COVID-19 pandemic that started in mid-March 2020 provided us with a unique opportunity to find out what would be the possible variation range of major air pollutants in Romanian urban areas under various strengths of anthropogenic activity. The time-series of atmospheric main pollutant mass concentrations, particulates PM₁₀ and PM_2.5 and gaseous species NO₂, CO, SO₂, O₃, were statistically analyzed for each city for the representative month of each season in 2019 and 2020 and then used to estimate the pollutant impact on the surrounding regions. Results show significant decreases for most pollutants in most cities especially in spring of 2020, during the hard lockdown period. Maps of interpolated mass concentrations reveal regional significant differences with pollutant-specific hot- and cold-spots in Romania. This work constitutes a good database to characterize de urban air pollution in Romanian major cities and the spatial distribution of their impact around.

Abstract. The management of radioactive waste is a costly process that involves several activities, including radiological characterization, treatment, conditioning, intermediate storage, and final storage. It is crucial to optimize these activities to reduce costs. Proper radiological characterization is essential to ensure correct classification of the waste and rational use of storage and final storage facilities. Overestimating the waste's activity reduces storage capacity, while underestimating it creates nuclear security issues. This paper describes the methodology used in the predisposal stage to evaluate the activity resulting from activation or contamination of a cast iron plate used to support the cast iron rings of the VVR-S nuclear research reactor block's biological protection. The reactor was decommissioned between 2010 and 2020, and the evaluation aimed to treat the piece as oversized radioactive waste within the Radioactive Waste Management Department at IFIN-HH.

Abstract. As technology continues to evolve, it is becoming of increasing importance for high school students to have a very strong foundation in physics, which would provide them with a fundamental understanding of how the physical world works. An integrated curriculum that blends physics with engineering can provide students with a deeper understanding of complex topics, which is critical to many emerging technologies, including renewable energy technologies such as photovoltaic cells. In this article are reviewed surveys testing interest in higher complexity high school physics courses, that were conducted among high school students and graduates from technological universities, and also, are reviewed approaches of high school physics courses on photovoltaic cells as renewable, sustainable energy sources, essential to combat climate change.

Abstract. In this paper an alternative way of conducting the physics laboratory exercise for determining the adiabatic index of air using the Clement-Desormes method is proposed. The process of isochoric cooling of air has been studied in terms of the dependence of pressure on time, and hence temperature on time, since it is proportional to pressure at a constant volume and mass of air. A theoretical model of the considered process was also made. The experimental results were processed statistically. The coefficient of determination R² and the F-test statistic were calculated and their values indicate a very good agreement between theory and experiment. The analysis of the residuals, however, implies that the model could be further improved through the inclusion of higher order terms.