New Research in Physics

Abstract The growing challenge of membrane fouling in water treatment processes, especially in desalination plants, requires innovative approaches to enhance membrane performance. This study presents a novel surface modification strategy for different membranes (PES, PVDF, PP) using diamond-like carbon nanostructures via plasma-enhanced chemical vapor deposition. The primary objectives were to improve membrane hydrophilicity, enhance antifouling properties, and increase salt rejection efficiency while maintaining structural integrity. A systematic review compared diamond-like carbon nanostructure coating modifications under optimized plasma conditions (40 W power, 70 mTorr pressure, 30 min irradiation). The surface characterization of all three studied membranes demonstrated the successful incorporation of diamond-like carbon nanostructures, as confirmed by FTIR spectroscopy and Raman analysis, which revealed a uniform carbon coating without forming a crystalline structure. The modified membranes showed significant improvement in surface properties, indicating increased hydrophilicity. AFM analysis revealed significant surface smoothing, which contributes to improved antifouling properties. Performance evaluation revealed exceptional improvements in key parameters of PES, and PVDF membranes: pure water flux increased, while salt rejection improved by up to 99%. The modified membranes achieved high flux recovery rates compared to the unmodified membrane, indicating superior antifouling properties. Stability tests in saturated salt solutions revealed easy cleaning properties and hydrophilicity retention after multiple wash cycles, indicating excellent durability. This work introduces a cost-effective approach to developing high-performance antifouling membranes with potential applications in desalination plants and wastewater treatment facilities. The findings provide valuable insights into the relationship between surface modification, structural properties, and membrane performance, and contribute to the advancement of sustainable water treatment technologies.

Abstract Cancer remains one of humanity's most significant challenges, necessitating precise and effective therapeutic approaches. Advanced techniques such as stereotactic radiosurgery (SRS) and cutting-edge devices like Gamma Knife have been employed for the treatment of brain tumors. Convolution algorithms, recognized for their ability to detect tissue heterogeneity, and Monte Carlo simulations, known as the most accurate dose calculation method, have garnered considerable attention. In this study, the Gamma Knife system was simulated using Monte Carlo codes to calculate dose distribution on a heterogeneous phantom. Subsequently, the phantom underwent CT imaging and analysis within the Gamma Knife treatment planning system. Results indicated minimal dose distribution differences in central profiles but increased discrepancies at field margins. This research contributes to enhanced therapeutic precision and reduced side effects.

Abstract One of the effective methods for identifying high-mass neutron stars is to study binary systems containing millisecond pulsars. In such systems, the companion star is affected by intense pulsar irradiation, which alters its apparent brightness and allows for the estimation of the neutron star’s mass. This irradiation also displaces the optical center of the companion relative to its center of mass, which in turn increases the uncertainty in precisely determining the orbital parameters and the neutron star mass. In this study, we investigated the binary system PSR J2215+5135 using Eclipsing Light Curve (ELC) modeling along with combined photometric and spectroscopic data, and estimated the mass of the neutron star through comprehensive modeling of the system’s irradiation. The binary system lies at an estimated distance of ~ 3 kpc from Earth. Its neutron star is a rapidly rotating millisecond pulsar with a spin period of 2.61 ms, while the binary orbit has a period of 4.14 hr. To achieve this, we employed a physical model of the irradiated companion star and simultaneously fitted light curves in three different bands as well as radial velocity curves from two distinct spectral groups. Our results yield a center-of-mass velocity for the companion star of K1 = 414.6−2.6 +4.6 km/s and an orbital inclination angle of i = 64.1°. The neutron star’s mass was determined to be M2 = 2.28−0.11 +0.12 M☉, and the companion star’s mass was estimated at M1 = 0.32±0.10 M☉. In part of this work, the effect of hot spots on the companion's surface was examined and compared to models excluding such features. To avoid exclusivity in analyzing data from compact-object binaries, the use of accessible and general-purpose modeling tools is essential, as it enables independent reproduction and validation of results by various research groups. The significance of this study lies in the fact that, unlike many proprietary tools, the ELC model is publicly available to the scientific community. Achieving results with over 99% consistency compared to specialized codes underscores the credibility and reliability of this model for future studies—including projects related to the Iranian National Observatory. Moreover, the identification of a neutron star with such a high mass places stringent constraints on the equation of state of dense matter and may prompt revisions of existing theoretical models.

Abstract Graphene is a semiconductor without an nergy gap........

Abstract In the relativistic regime, we propose a method for deriving the relativistic version of the Hamiltonian, assuming the Lagrangian is available. We demonstrate that a minor modification in the definition of the Lagrangian is sufficient to achieve this goal. We will investigate the ability of the obtained Hamiltonian to describe field theory, and, by referring to canonical and mechanical momenta, we will reproduce the theories of interest. From the relativistic Hamiltonian obtained through two different approaches, we will construct the theories of bosonic and fermionic fields and clarify their interconnection. We explain the mechanism of the Legendre transformation between configuration space and phase space, and we extend the Poisson product. After deriving the Hamiltonian and the equations of motion attributed to the relativistic Hamiltonian, we extend the phase space and show that the creation of a dual phase space, along with the redefinition of the derivatives on the dual phase space and the original phase space, and the modification of the Poisson product structure will be necessary to approach the relativistic Poisson product. To establish a complete Lorentzian phase space, modifications to classical theory and an effective realization of the relativistic Hamiltonian are necessary.

Abstract Using quantum computational calculations, the electronic and optical properties of monolayer nanostructures of copper, silver, and gold compounds were investigated. The results of recent studies revealed that these compounds are stable in a centrosymmetric hexagonal phase and possess a completely planar structure. These materials exhibit metallic characteristics, such that the s and d orbitals contribute metallic states at the Fermi level. Optical calculations further demonstrate that intraband transitions play a dominant role up to energies of about 3 eV. The plasmonic frequency of these compounds appears around 4 eV. Moreover, quantum capacitance calculations indicate their remarkable capability for energy storage; specifically, within the potential window of aqueous systems, the charge storage density for the copper monolayer was obtained to be significant. The findings suggest that copper, silver, and gold monolayers hold great potential for applications in plasmonic resonance sensors as well as promising platforms for energy storage.

Abstract Fiber optic biosensors are highly effective tools for early disease diagnosis due to their exceptional sensitivity and low detection limit of biological samples. Label-free sensors based on refractive index (RI) variation measurements exhibit enhanced sensitivity and selectivity when integrated with localized surface plasmon resonance (LSPR) technology. In this study, a dual LSPR fiber optic sensor based on a concave-tip structure combined with hybrid nanoparticles (NPs) of gold nanoparticles (AuNPs) and gold@silver core-shell NPs (CSNPs) is developed for simultaneous detection of RI and temperature. The RI sensitivity of sensors functionalized with AuNPs and CSNPs was measured at 1845.71 nm/RIU and 1984.58 nm/RIU within the RI range of 1.3332 to 1.3604 RIU, respectively. For the dual LSPR sensor incorporating hybrid NPs, the RI sensitivities corresponding to the two resonance wavelengths were found to be 1567.67 nm/RIU and 1787.73 nm/RIU. The slight reduction in sensitivity compared to single NP configurations is due to a decrease in surface NP density, which is negligible. A critical challenge in fiber optic sensor operation is the influence of temperature fluctuations on measurement accuracy. To address this issue, the temperature sensitivity of the dual LSPR sensor was measured in the range 20–50°C, resulting S_Au = –1.2 nm/°C and S_CS = –1.32 nm/°C for AuNPs and CSNPs, respectively. To mitigate cross-sensitivity, a sensitivity matrix was employed, enabling accurate simultaneous measurement of RI and temperature. These results demonstrate that the developed lab-on-fiber sensor is a promising candidate for dual-parameter monitoring in label-free fiber optic biosensing applications.

Abstract There are several methods for solving Einstein's field equations in gravitational interactions between particles, one of which is the weak field approximation. In this approximation, gravitational fields behave similarly to electric and magnetic fields and are described by equations akin to Maxwell's equations, referred to as quasi-Maxwellian equations in gravity In electromagnetism, the path of motion of a test particle within these fields can be determined using vector and scalar potentials. This paper employs the weak field approximation to derive the equations governing the motion of a test particle in the electromagnetic gravitational field generated by a sphere and a rotating band. Additionally, numerical calculation methods and appropriate software were utilized to plot the trajectory of the test particle in these fields under various conditions. The results indicated that the path of the test particle is influenced by whether the sphere and band are stationary, rotating together, or rotating separately. Moreover, the angular velocities of the sphere and the ribbon significantly impact the test particle's trajectory. By examining the ratio of the angular velocities of the ribbon and the sphere, different patterns of the test particle's trajectory were observed.