Brazilian Journal of Physics最新文献

{"title":"Influence of the Reduction Temperature of TiO2/rGO Nanotubes on the Structural Defects Studied by Raman Spectroscopy","authors":"T. S. Pinheiro,&nbsp;W. Rondan,&nbsp;M. F. Malateaux,&nbsp;M. Lozada,&nbsp;I. Y. Abê,&nbsp;R. M. N. de Assunção,&nbsp;K. F. Albertin,&nbsp;A. Champi","doi":"10.1007/s13538-025-01781-2","DOIUrl":"10.1007/s13538-025-01781-2","url":null,"abstract":"<div><p>Titanium oxide (TiO2) is an excellent photocatalyst, under ultraviolet light irradiation, for the degradation of various organic pollutants. However, TiO₂ is limited by its high band gap value (3.2 eV). To overcome this limitation, graphene oxide (GO) and its derivatives, with their high specific surface area and excellent light absorption properties, can enhance the efficiency of the photocatalytic properties of TiO₂ nanotubes. In this study, a material with potential use in photocatalysis was prepared by thermally incorporating GO into titanium oxide nanotubes (TiO₂NTs) using dip-coating deposition. The samples were characterized by Raman spectroscopy, field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis/differential scanning calorimetry/differential thermogravimetry (TGA/DSC/DTG) GA/DSC/DTG and UV–Vis spectroscopy. These techniques allowed for the observation of the effect of thermal treatment on the nanocomposite. It was determined that the optimum temperature for the thermal treatment of the TiO₂NTs/GO nanocomposite is 420 °C, evidenced by the analyzed Raman parameters (G-band, FWHM, I_D/I_G, distance between defects—L_D and G-band position), which are consistent with a material that has few defects (increased L_D). Furthermore, the characterizations demonstrated the satisfactory formation of a reduction of functional groups for the formation of uniform TiO₂/rGO nanotubes, decrease in the edge defects of GO, tuning of the diameter TiO₂ and confirming the efficiency of the synthesis process of these nanostructures. Finally, the results are promising for potential applications in devices for photocatalysis and CO₂ storage.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The 3-3-1 Model with Exotic Electric Charges, Right-Handed Neutrinos with Type-I+II Seesaw Mechanism and Their Effects on LFV","authors":"Abrar Ahmad,&nbsp;Shakeel Mahmood,&nbsp;Farida Tahir,&nbsp;Fizza Atif,&nbsp;Wasi Uz Zaman","doi":"10.1007/s13538-025-01754-5","DOIUrl":"10.1007/s13538-025-01754-5","url":null,"abstract":"<div><p>In this research, we propose a modified version of the 3-3-1 model, incorporating a type-I+II seesaw mechanism and <span>(Z_{4})</span> discrete symmetry, as a framework for investigating lepton flavor-violating (LFV) decays. This model successfully yields the left-handed neutrino’s mass square differences in the eV scale, with specific values <span>(Delta m_{21}^{2}=7.12times 10^{-5}~eV^{2},)</span> <span>(Delta m_{31}^{2}=2.55times 10^{-3}~eV^{2})</span>, and generates mixing angles <span>(sin ^{2}theta _{12}=0.304,~sin ^{2}theta _{23}=0.595~)</span>and <span>(sin ^{2} theta _{13}=2.15times 10^{-2})</span> that align with experimental data. Furthermore, we develop SARAH and SPheno (Comput. Phy. Commun. <b>185</b>, 1773, 2014) algorithms tailored for our modified model, enabling us to estimate the magnitude of LFV observables. Our calculations indicate favorable results for various LFV branching ratios, including <span>(Br(mu rightarrow egamma )=7.82times 10^{-20},)</span> <span>(Br(tau rightarrow egamma )=3.66times 10^{-22},)</span> <span>(Br(tau rightarrow mu gamma )=1.03times 10^{-19},)</span> <span>(Br(tau rightarrow eee)=3.97times 10^{-12},)</span> <span>(Br(tau rightarrow mu mu mu )=1.33times 10^{-12},)</span> <span>(Br(tau rightarrow mu ee)=8.89times 10^{-13})</span>. These findings demonstrate improved agreement with experimental measurements compared to previously reported results, which typically fall within the range of <span>(10^{-2})</span> to <span>(10^{-6})</span>.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical and Structural Properties of Samarium-Doped Oxyfluoroborate Glasses for Optoelectronic Applications","authors":"Ayman M. Mostafa,&nbsp;M. Abdel-baki,&nbsp;M. A. Azooz,&nbsp;A. M. Fayad,&nbsp;Asmaa E. Farahat,&nbsp;Ashraf K. Eessaa","doi":"10.1007/s13538-025-01777-y","DOIUrl":"10.1007/s13538-025-01777-y","url":null,"abstract":"<div><p>A series of new oxyflouroborate glass systems with the composition 75B₂O₃-5Al₂O₃-(5-x) Li₂O-15MgF₂ embedded with samarium ions with different molar ratios are prepared and studied their optical properties based on vibrational, transitional, and photoluminescence characteristics to be applicable in optoelectronic applications. The gain results show that as the amounts of Sm₂O₃-embedding of oxyflouroborate glass increase, the absorption coefficient decreases with increasing wavelength up to a certain wavelength, which affects the energy band gap directly and indirectly, the network's polarizability and the skin depth. The skin effect may affect the optical energy band gap of any glass structure based on the VB to CB transition, affecting the ionicity of oxygens and the interatomic distance due to the charges on the oxygen anion in borate glasses made of Sm₂O₃ and Li₂O. Thus, it indicates ionic bond formation and a significant shift in polarizability, molar refractivity, steepness parameter, metallization, optical electronegativity, electron polarizability, and optical basicity. Besides, the 0.4 mol% Sm³⁺-embedded glass sample has the highest emission intensity, related to the non-bridging oxygen involved in Sm³⁺ incorporation into host glasses. Also, the glass samples showed that Sm₂O₃ concentration increased the two absorption bands at 700 cm⁻¹, related to the bond-bending vibrational mode of bridging oxygen atoms, and to some extent, the shifting of bands could not follow any trend with the continuous addition of samarium oxide. These results promise to know the influence of inserting Sm₂O₃ on the borate glass structure, as the junction point determines the optical band edge for up-conversion laser and photonic applications.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating Cnoidal Magnetosonic Waves in a Plasma with Non-Maxwellian Electrons","authors":"E. I. El-Awady,&nbsp;S. Hussain,&nbsp;N. Akhtar","doi":"10.1007/s13538-025-01766-1","DOIUrl":"10.1007/s13538-025-01766-1","url":null,"abstract":"<div><p>The two-fluid magnetohydrodynamic theory is applied to study periodic magnetosonic waves (cnoidal waves) in electron-ion (<span>(e-i)</span>) classically magnetized plasma. The mass of electrons is included in the momentum equation to incorporate the inertial effects, and they obey nonthermal distributions such as (<i>r</i>, <i>q</i>), <i>Q</i>-nonextensive, and kappa distributions via the equation of state. The dispersion relation (DR) for a magnetosonic wave (MWs) is derived by applying the Fourier transformation. The dispersion in the plasma system appears through electron skin depth. By employing the Reductive Perturbation Technique (RPT), a nonlinear evolution equation is formulated, which allows for the existence of solitons within the plasma system. To obtain the solution in the form of magnetosonic cnoidal waves, the Sagdeev pseudopotential method is utilized. The research comprehensively examines how changes in the electron flatness index (<i>r</i>) at low energy, the superthermal index (<i>q</i>) at high energy, the superthermal parameter (<span>(kappa )</span>), and the nonextensive parameter (<i>Q</i>) affect the propagation properties of magnetosonic waves. The findings reveal that when <span>(vartheta =Lambda =0)</span>, the cnoidal waves associated with magnetosonic waves undergo a transformation and become solitary waves. Overall, the findings enhance the understanding of ion-acoustic periodic magnetosonic waves in ionospheric plasmas and single-mode drift wave spectra.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-025-01766-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of Terahertz Radiation Generation via Sech-Shaped Laser Pulses in Collisional Homogenous Plasma","authors":"Jasveer Singh,&nbsp;Sunita Rani,&nbsp;Hitesh Kumar Midha,&nbsp;Vivek Sharma,&nbsp;Vishal Thakur","doi":"10.1007/s13538-025-01774-1","DOIUrl":"10.1007/s13538-025-01774-1","url":null,"abstract":"<div><p>The influence of the sech-shaped laser pulse and collisional plasma profile on the efficacy of terahertz (THz) production has been thoroughly investigated. The study assesses the impact of the sech parameter (b) on THz production, revealing that an increase in b results in a more focused laser pulse, hence augmenting plasma interaction and raising THz generation efficiency. The examination of transverse distance indicates that increased values of b lead to a more concentrated ideal region for THz production, with peak efficiency relocating to reduced transverse distances. The impact of collisional frequency is analysed, revealing that elevated collisional frequencies diminish THz generating efficiency owing to heightened dispersion and energy dissipation. Moreover, plasma density has a direct correlation with THz production, since elevated density promotes intensified nonlinear interactions and improved efficiency. These findings highlight the need of optimising these parameters for efficient THz production.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effectiveness of Nonlinear Kerr Medium in Statistical Measurements of (mathfrak {X})-type Five-Level Atom and Two Quantum Systems","authors":"Abdallah A. Nahla,&nbsp;M. M. A. Ahmed","doi":"10.1007/s13538-025-01758-1","DOIUrl":"10.1007/s13538-025-01758-1","url":null,"abstract":"<div><p>Statistical measurements for an optics model containing a five-level atom (5LA) and two quantum systems (2QS) are evaluated into two types of nonlinear Kerr-like media (NKLM). Two quantum systems represent the Boson and SU(1,1) systems. Suggest that the configuration of the 5LA and 2QS is <span>(mathfrak {X})</span>-type. The 5LA initial state is in excited state as well as the Boson and SU(1,1) quantum systems are in coherent and Barut-Girardello states, respectively. The nonlinear Kerr-like medium represents two different types for two quantum systems. Well-famous statistical measures such as population inversion, Shannon entropy, autocorrelation, coherence, and Cauchy-Schwarz inequality are evaluated and analyzed. The effectiveness of Kerr parameters in the proposed statistical measurements are discussed.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-025-01758-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143861375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing the Quality of Accelerated Electron Bunch Through the Circular Laguerre–Gauss Laser Pulses","authors":"Maryam Hamidi,&nbsp;Ali Shekari Firouzjaei,&nbsp;Hossein Akou","doi":"10.1007/s13538-025-01761-6","DOIUrl":"10.1007/s13538-025-01761-6","url":null,"abstract":"<div><p>This study examines the interaction of an electron bunch with a circularly polarized Laguerre–Gauss (LG) laser pulse. The distinct orbital angular momentum and intensity distribution of LG laser beams play a crucial role in their unique interactions with charged particles. The trajectory of the electrons is influenced by the interplay of the ponderomotive force and other forces acting on them. The energy of the electrons evolves over time, typically increasing rapidly during the interaction. The analysis suggests that the circular polarization of the LG laser pulse has advantages in terms of producing a more focused and energetic electron beam compared to linear polarization.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Continuous and Discrete Compartmental Models for Infectious Disease","authors":"Gustavo A. Sousa,&nbsp;Diogo L. M. Souza,&nbsp;Enrique C. Gabrick,&nbsp;Patrício D. C. dos Reis,&nbsp;Lucas E. Bentivoglio,&nbsp;Antonio M. Batista,&nbsp;José D. Szezech Jr.","doi":"10.1007/s13538-025-01771-4","DOIUrl":"10.1007/s13538-025-01771-4","url":null,"abstract":"<div><p>The study of infectious disease propagation is essential for understanding and controlling epidemics. One of the most useful tools for gaining insights into the spread of infectious diseases is mathematical modelling. In terms of mathematical epidemiology, the main models are based on compartments, such as Susceptible–Infected (SI), Susceptible–Infected–Recovered (SIR), and Susceptible–Exposed–Infected–Recovered (SEIR). These models offer mathematical frameworks for representing the proliferation dynamics of various diseases, for instance flu and smallpox. In this work, we explore these models using two distinct mathematical approaches, cellular automata (CA) and ordinary differential equations (ODEs). They are able to reproduce the spread dynamics of diseases with their own individuality. CA models incorporate the local interaction among individuals with discrete time and space, while ODEs provide a continuous and simplified view of a disease propagation in large and homogeneous populations. By comparing these two approaches, we find that the shape of the curves of all models is similar for both representations. Although the growth rates differ between CA and ODE, one of our results is to show that the CA yields a power-law growth, while the ODE growth rate is well-represented by an exponential function. Furthermore, a substantial contribution of our work is using a hyperbolic tangent to fit the initial growth of infected individuals for all the considered models. Our results display a strong correlation between simulated data and adjusted function. We mainly address this successful result by the fact that the hyperbolic function captures both growing: the power law (when considered the first terms of infinite sums) and combinations of exponential (when the hyperbolic function is written via exponential). Therefore, our work shows that when modelling a disease the choice of mathematical representation is crucial, in particular to model the onset of an epidemic.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Mono-energetic Electron Beam on Low-Frequency Localized Structures in Nonthermal Magnetoplasmas","authors":"Muhammad Khalid,&nbsp;Sahibzada Izhar Hussain Bacha,&nbsp;Mohammad Eghbali","doi":"10.1007/s13538-025-01768-z","DOIUrl":"10.1007/s13538-025-01768-z","url":null,"abstract":"<div><p>The study explores the nonlinear dynamics of a magnetized plasma system characterized by two types of electrons following a Cairns distribution, alongside warm ions and an electron beam. By employing the reductive perturbation technique (RPT), the governing nonlinear differential equation for this system has been established. The presence of the electron beam emerges as a distinctive factor that significantly influences wave propagation within the plasma environment. Findings indicate that soliton waves traversing this plasma medium undergo alterations in their amplitude, phase velocity, and nonlinear coefficient due to the electron beam’s influence. Furthermore, the results suggest that the electron number density of the beam can be manipulated to control the propagation of ion acoustic wave (IAWs) in plasmas, highlighting potential applications in plasma-laser interactions.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143840360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic and Thermal Radiation Effects on Hematocrit-Dependent Blood Nanofluid Flow in an Inclined Stenotic Artery with Heat Generation","authors":"Mesfin Zewde Kefene,&nbsp;Ebba Hindebu Rikitu","doi":"10.1007/s13538-025-01770-5","DOIUrl":"10.1007/s13538-025-01770-5","url":null,"abstract":"<div><p>This study investigates the hematocrit-dependent flow of blood nanofluid in an inclined stenotic artery, considering the effects of magnetic fields, thermal radiation, porous media, Hall effects, and heat generation. Using blood as the base fluid and iron oxide <span>((Fe_{3}O_{4}))</span> as nanoparticles, we model the flow through a cylindrical tube with mild stenosis. The governing equations, which are coupled nonlinear partial differential equations, are transformed into a non-dimensional form for analysis. Numerical solutions are obtained using the finite difference method (FDM) with MAPLE software. The study focuses on how the velocity and temperature profiles vary along the radial axis within the stenotic region for varying values of prominent parameters, along with an analysis of heat transfer rates and skin friction coefficients in relation to stenosis height. Key findings reveal that the magnetic field significantly reduces blood velocity due to the Lorentz force, while increased hematocrit levels elevate viscosity, further impeding flow. Thermal radiation enhances temperature profiles, promoting convective flow within the blood. Additionally, the temperature profiles near the centerline of the stenosed artery increase with the magnetic field and decrease with the Hall parameter; however, an opposite trend is observed near the stenotic walls of the artery. Furthermore, an increase in stenotic height leads to a significant rise in the skin friction coefficient, attributed to enhanced shear stress at the arterial walls. Conversely, the heat transfer rate exhibits a complex relationship; while lower stenotic heights facilitate improved thermal exchange due to increased flow velocity, higher stenotic heights tend to restrict flow, resulting in reduced heat transfer efficiency.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}