The European Physical Journal Plus最新文献

This study measures the natural radioactivity and calculates the radiological risk indices in terms of ingestion dose and cancer risk in some samples of powdered milk from 10 brands consumed by adults, children and infants that are available in almost all markets in Iraq by using a NaI(Tl) detector. The results showed that the mean activity corresponding to ²²⁶Ra was 1.003 ± 0.124 Bq/kg, while for ²³²Th was 2.098 ± 0.276 Bq/kg, but for ⁴⁰ K was 62.57 ± 2.82 Bq/kg. The mean total annual effective doses due to the ingestion of the powdered milk for infants, children and adults were calculated to be 0.233, 0.137 and 0.027 mSv/y, respectively. Hazard indices and radium equivalent were also calculated for all brands of powdered milk and resulted within the permissible limit set by UNSCEAR. This indicates that there is no significant threat to consumer health due to the ingestion of these brands of milk.

Systemic radiotherapy via suitable beta emitter radionuclides is an effective approach for palliative treatment of bone metastasis. Current study aims to evaluate the relative biologic effectiveness (RBE) of five beta emitter radionuclides (including ³²P, ⁸⁹Sr, ¹⁵³Sm, ¹⁸⁶Re, and ¹⁸⁸Re) during the systemic radiotherapy of bone metastasis using a hybrid Monte Carlo (MC) simulation approach. To estimate RBE values, different structures of femur and lumbar vertebrae phantoms were simulated by Geant4. Then, dose distributions and secondary electron spectra, relevant to the interactions of emitted radiation with simulated tissues, were scored. Finally, Monte Carlo damage simulation (MCDS) code was employed to calculate the induction of both DSBs and SSBs (double strand a single strand breaks, respectively) as the biological endpoints for RBE estimation. The obtained results showed a high absorbed dose within the cortical bone which decreased with moving to greater radial distances. The maximum RBE_DSB as well as minimum RBE_SSB values (RBE values relevant to the DNA double-strand and single strand breaks, respectively) were calculated for ¹⁵³Sm. In contrast, minimum RBE_DSB values were found for ³²P. From the results, ¹⁵³Sm can be regarded as a suitable option among the considered radionuclides because of tumor cell killing. However, to select the appropriate radionuclides for the treatment of bone metastasis, other factors and further studies should be taken into account.

In this study, the stochastic dynamics of Brownian particles with a time-increasing and sinusoidally modulated mass are systematically investigated. The motion is described by a one-dimensional Langevin equation with time-dependent damping under both white and colored (Ornstein–Uhlenbeck) stochastic forces. Key dynamical quantities, including the mean squared displacement, mean squared velocity, probability density functions, and the Shannon positional entropy, are analyzed using analytical methods and Euler–Maruyama simulations. The results show that periodic mass modulation and temporal noise correlations noticeably affect short- and long-time diffusion behavior, velocity fluctuations, and the evolution of the position distribution. In particular, colored noise enhances diffusion at early times due to its finite correlation structure, while the Shannon entropy exhibits similar long-time limits for both noise types. These findings clarify how time-dependent parameters and noise correlations shape the dynamical properties of stochastic systems and provide a framework for studying complex behaviors in generalized Langevin models.

The structural, optical, and radiation shielding properties of a newly produced lead-free poly (methyl methacrylate) (PMMA) Nanocomposite modified with silicon dioxide were evaluated. The solution casting method was adopted in the synthesis of the samples using chloroform as a solvent at room temperature. The nanocomposites were gradually integrated with 5%, 10%, 15%, 20%, and 25% wt. of SiO₂ into the dissolved PMMA. XRD analysis was employed for phase identification of the crystalline structures, FTIR for molecular structure analysis, and UV–visible spectrophotometry for optical analysis. The UV–visible data obtained were used to calculate the glasses' direct and indirect optical energy band gaps, refractive index, dielectric constant, and other properties. The direct and indirect optical energy band gaps decreased from 5.62 to 5.32 and 5.79 to 5.33, respectively, with increasing SiO₂ content. In contrast, the refractive index increased from 1.89 to 1.95 with increasing SiO₂ concentration. The linear attenuation coefficient (LAC) of the investigated materials was compared from 60 to 1332.5 keV, and it shows an inverse relation. The samples' HVL at constant photon energy is inversely correlated with their density. PMMA/SiO₂ nanocomposites gave the least tenth value layer (TVL), demonstrating their superiority as a shielding material. At the lowest energy (60 keV), the MFP range for these composites is 0.263–0.337 cm, which expands up to 7.102–8.003 cm at the highest energy (1332.5 keV). The synthesised transparent PMMA/SiO₂ nanocomposites show good properties for the structural, optical, and radiation shielding.

Dispersionless hierarchies are of much consideration because of their arising in many problems of physics and applied mathematics, like quantum field theories, string theory, etc. In this paper, we consider and explore the Darboux transformation as well as the binary Darboux transformation for discrete generalized coupled dispersionless system and calculate the multi-soliton and quasi-Grammian solutions. Furthermore, we present the explicit expressions of Grammians and soliton solutions. Finally, as an explicit example, we present Grammians, discrete breather, dark and bright soliton.

Controlled separation of microscopic particles in mixtures is in high demand for biological research and industrial applications, and traditional methods, which often rely on particle size, have inherent limitations. We consider an inertial Brownian particle moving in an oscillating potential and subjected to unbiased time-periodic forces and constant static forces. In the process, we find an effective mass separation mechanism that is based on the anomalous transport characteristics of negative migration, where particles of a specific mass move in a direction opposite to the hydrostatic force. We establish a multi-parameter regulation system containing driving frequency, particle mass, hydrostatic force and amplitude to utilize the negative migration effect for effective mass separation of Brownian particles, in addition, we explore the effect of stochastic resetting rate on the particle mass separation mechanism and reveal the regulation law of multiple parameters on the optimal separation mass. This study provides new theoretical guidance for microfluidic particle and biomolecule separation.

Carbon dioxide (CO₂) is often released during natural gas processing and is one of the major greenhouse gases (GHGs) contributing to environmental concerns. A promising and cost-effective method for CO₂ removal in natural gas processing is supersonic separation, which utilizes non-equilibrium condensation in supersonic swirling flows within a supersonic separator. In this study, a methane (CH₄)–CO₂ mixture was considered as natural gas. A three-dimensional (3D) supersonic separator was used to generate supersonic swirling flow under varying swirl generator angles, incorporating non-equilibrium condensation. A nucleation equation and a droplet growth equation were integrated into the governing compressible Navier–Stokes equations. The predicted results were validated against existing experimental data. The study further examined the effects of different supersonic separator configurations on the non-equilibrium condensation of CO₂ in the mixture flow. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was applied to determine the optimal configuration based on wetness (the mass fraction of liquid CO₂ relative to the total mass fraction of liquid and vapor CO₂ at the nozzle outlet) and kinetic energy. The results indicate that increasing the swirl generator angle in the supersonic separator enhances nucleation and increases CO₂ wetness.

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This study examines the operational safety of wound treatment accessories based on direct cold atmospheric plasma (CAP) in scenarios where unintended incomplete physical contact between the high-voltage electrode and biological tissue occurs during treatment. By mimicking incomplete contact using two experimental approaches, we systematically varied the effective electrode area and assessed key physical process parameters: electrical input power, patient leakage currents, surface temperature increase, UV radiation emission, and the emission rates of selected reactive oxygen and nitrogen species (RONS). Measurements were taken in accordance with DIN SPEC 91315 and relevant IEC standards, using metal meshes and tissue models, such as pig ears and hydrogels, as counter electrodes.

Experimental trends reveal increasing leakage current densities as electrode area is reduced. Absolute values for leakage currents remain consistently below established safety thresholds. As a result, CAP exposure causes a slight yet physiologically harmless heating effect (ΔT < 2.5 K). A comparable trend was observed for UV intensity, with spectrally weighted irradiances remaining at least 40-fold below risk-related limits. RONS analysis identified ozone as the predominant species, with only slight increases in emission rates during partial electrode ignition. The predictions for the expected average ozone concentrations during typical operating times of the devices indoors generally comply with air quality guidelines.

In conclusion, partial electrode contact does not compromise the key safety parameters of wound treatment accessories based on direct CAP technology. These findings support the safe use of such devices under variable clinical conditions and inform future optimization efforts, highlighting the need to further integrate efficacy and safety evaluations in translational plasma medicine.

Traditionally, the embedding procedure for spherically symmetric spacetimes has been restricted to the equatorial plane (theta = pi /2). This conventional approach, however, encounters a fundamental limitation: not every spherically symmetric geometry admits an isometric embedding of its equatorial slice into three-dimensional Euclidean space. When such embeddings are not possible, the standard geometric intuition becomes inapplicable. In this work, we generalize the embedding procedure to slices with arbitrary polar angles (theta ne pi /2), thereby extending the visualization and analysis of spacetimes beyond the reach of traditional methods. The formalism is applied to Schwarzschild-like wormholes and to a generalized Minkowski spacetime with angular deficit or excess, which are particularly relevant since their equatorial slices cannot be consistently embedded in (mathbb {R}^3). In these cases, we identify the explicit constraints on the radial coordinate, polar angle, and geometric parameters required to guarantee consistent embeddings into three-dimensional Euclidean space.