Brazilian Journal of Physics最新文献

{"title":"Spectroscopic Properties of Blue Light-Emitting Li2SiO3:xGd3+ Phosphors for Solid State Lighting Applications","authors":"Priya Barik,&nbsp;Ishwar Prasad Sahu","doi":"10.1007/s13538-024-01673-x","DOIUrl":"10.1007/s13538-024-01673-x","url":null,"abstract":"<div><p>A series of blue light-emitting Li₂SiO₃:<i>x</i>Gd³⁺ phosphors were prepared via a solid-state reaction method at 950℃ for 3 h in an air atmosphere. According to the powder X-ray diffractometer (PXRD) and Rietveld refinment analysis, the crystalline structure of the Li₂SiO₃:<i>x</i>Gd³⁺ phosphors matrix did not significantly change. The optical band gaps E_g of the sintered Li₂SiO₃:0.03Gd³⁺ material has been calculated by 5.62 eV by the Tauc plot. Photoluminescence (PL) investigation of Li₂SiO₃:<i>x</i>Gd³⁺ phosphors displayed an intense blue emission peak of Gd³⁺ ions ⁸S_7/2 → ⁶I_7/2 transition, under near utra-violet (NUV) excitation of 276 nm. After the concentration of Gd³⁺ ions in the Li₂SiO₃ host reached 0.03 mol, the concentration quenching occurred, indicating that it had reached an optimal concentration. Under the UV excitation (276 nm); theLi₂SiO₃: 0.03Gd³⁺ materials exhibit good temperature stability. The emission intensity, Commission Internationale de lEclairage (CIE) chromaticity coordinates, correlated color temperature (CCT), color purity, and quantum efficiency of Li₂SiO₃:0.03Gd³⁺ phosphor were comprehensively enhanced by Gd³⁺ doping. The blue region's CIE coordinate value confirms that Li₂SiO₃:Gd³⁺ can be utilized as a component in solid-state display applications and artificial blue light-emitting diode (LED) generation.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142875163","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":"Investigation of Modulational Instability Drift Wave Packet in Non-uniform Magneto-Rotating Plasma","authors":"M. Eghbali,&nbsp;M. Mokari","doi":"10.1007/s13538-024-01659-9","DOIUrl":"10.1007/s13538-024-01659-9","url":null,"abstract":"<div><p>This paper addresses the modulation instability of ion-acoustic waves in a rotating plasma subjected to a magnetic field, focusing on how inhomogeneities in equilibrium density, electron temperature, and magnetic field influence wave behavior. We employ a combined hydrodynamic approach and perturbation method to derive the nonlinear Schrödinger equation (NLSE), effectively balancing nonlinearity with dispersive effects. Our analysis reveals various localized ion-acoustic excitations, including bright and dark envelope solitons, which emerge from modulational instability. We also demonstrate that specific solutions of the NLSE, such as the Peregrine soliton, Akhmediev breather, and Kuznetsov-Ma breather, represent rogue wave phenomena within this context. Numerical simulations indicate that plasma structural parameters, including rotational frequency and scale lengths, significantly impact modulation instability conditions. Notably, while these parameters enhance instability, further increases can lead to a reduction in rogue wave amplitude. Our findings provide insights into the formation mechanisms of nonlinear electrostatic excitations in both ultra-dense astrophysical and experimental plasma environments.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844781","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":"Synthesis and Magnetic Characterization of Dispersed Fe(_x)Ni(_{100-x}) (x = 10, 20, 30, 40, and 50) Nanoalloys Using the Thermal Decomposition Method","authors":"E. B. Peixoto,&nbsp;L. F. S. Andrade,&nbsp;M. H. Carvalho,&nbsp;J. D. T. Santos,&nbsp;L. S. Silva,&nbsp;J. G. S. Duque","doi":"10.1007/s13538-024-01679-5","DOIUrl":"10.1007/s13538-024-01679-5","url":null,"abstract":"<div><p>In this paper, we report on synthesis and magnetic properties of dispersed Fe<span>(_x)</span>Ni<span>(_{1-x})</span> (<i>x</i> = 10, 20, 30, 40, and 50) nanoalloys grown by thermal decomposition. X-ray diffraction patterns show that the majority crystalline phase is consistent with a <i>fcc</i> crystal structure (space group <i>Fm</i>3<i>m</i>) for all samples. Magnetization as a function of magnetic field and temperature shows that Fe<span>(_x)</span>Ni<span>(_{1-x})</span> are superparamagnetic with blocking temperatures around 10 K. However, for all samples, it is possible to observe a second very broad maximum, which can be ascribed to a bimodal nanoparticle size distribution and/or Ni nanoparticles for the case of samples grown with <i>x</i> = 10, 20, and 30. Finally, we argue that the nanoalloy size distribution and/or interaction effects should play a crucial role in determining the magnetic behavior of samples once we are not able to fit our <span>(H_C)</span>(<i>T</i>) data using the Néel relaxation and the Bean-Livingston approaches in a wide temperature range.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844785","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":"Estimation of Effective Momentum Diffusivity and Its Correlation with Neutral Particle Density Based on Toroidal Rotation Profiles in the TCABR Tokamak","authors":"Douglas Oliveira Novaes,&nbsp;José Helder Facundo Severo,&nbsp;Felipe Barbedo Rizzato,&nbsp;Gilson Ronchi,&nbsp;Tiago Fernandes,&nbsp;Mayara Yumi Ikeda,&nbsp;Vinícius Maia Neto,&nbsp;Fernando Albuquerque,&nbsp;Fellype do Nascimento,&nbsp;Juan Iraburu,&nbsp;Wanderley Pires de Sá,&nbsp;Leonardo Gimenes Sgubin,&nbsp;Jacques Levaton,&nbsp;Gustavo Paganini Canal,&nbsp;Zwinglio Guimarães Filho,&nbsp;Ricardo Magnus Osório Galvão,&nbsp;Michael Tendler","doi":"10.1007/s13538-024-01681-x","DOIUrl":"10.1007/s13538-024-01681-x","url":null,"abstract":"<div><p>An equation for estimating the effective diffusivity <span>(chi _varphi ^textrm{eff})</span> based on the thermal and frictional forces arising from the interactions with neutral particles is provided. These interactions are primarily attributed to charge-exchange processes between ions and neutral particles. Our analysis indicates that the proposed forces are strong candidates to act as sources or sinks of momentum at the plasma edge. Furthermore, although we only have an estimated profile of neutral particles, the results demonstrate a strong dependence of the effective diffusivity on the ion-neutral collision frequency and a comparatively weaker dependence on ion temperature. We showed that the toroidal rotation profile in the TCABR tokamak is well described by the Helander model for toroidal rotation velocity in the Pfirsch-Schlüter regime, which depends on the ion temperature gradient in the presence of the neutral particles. The toroidal rotation profile has been reconstructed by a sum of Bessel functions, derived from the solution of a second-order differential equation for the toroidal velocity. In this initial study on momentum transport in TCABR, our findings indicate that <span>(chi _varphi ^textrm{eff})</span>—which accounts for both the diffusivity and pinch terms in the momentum equation—increases significantly in the outer plasma region. Additionally, it achieves a reasonable maximum value of approximately <span>(chi _varphi ^textrm{eff} approx 20)</span> m<span>(^2/)</span>s near the plasma edge at <span>(r/a simeq 0.87)</span>, in the same radial position of the maximum ion-neutral collision frequency, demonstrating that the applied method successfully captures the general behaviour of this component as reported in other works, and guiding future experimental validation.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844782","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":"Quantum Chemical Calculations, Spectroscopic Properties, Molecular Docking and ADMET Studies of 2-(4-Tert-Butyl-2,6-Dimethyl-3-Hydroxybenzyl)-2-Imidazoline","authors":"Taner Kalayci","doi":"10.1007/s13538-024-01674-w","DOIUrl":"10.1007/s13538-024-01674-w","url":null,"abstract":"<div><p>This study focuses on examining the molecular geometry, biological activities, as well as the electronic and vibrational properties of 2-(4-tert-butyl-2,6-dimethyl-3-hydroxybenzyl)-2-imidazoline (oxymetazoline). The investigation integrates quantum chemical calculations, molecular docking, and experimental methods. The ground state geometry and electronic structure of oxymetazoline are optimized using the DFT/B3LYP/6–311 + + G(d,p) basis set. To predict the chemical reactivity of the title molecule, MEPS, frontier orbital analysis, and electronic reactivity descriptors were used. Charge transfer within the molecule was presented using HOMO and LUMO energies. The energies of intra and intermolecular hydrogen bonds in molecules, as well as their electronic properties, were examined using natural bond orbitals (NBOs). To determine the efficiency of the title chemical, molecular docking tests were undertaken against α1A and α2A adrenergic receptors (α1A; PDB ID: 7YM8, 4MQT, and α2A; PDB ID: 3QAK, 7EJ8). According to the results, we found that the situation with the lowest binding score and therefore the best binding affinity is the OMZ-7YM8 interaction. The analysis of drug-likeness, physicochemical properties, and ADMET results indicates that the title molecule possesses a favorable pharmacokinetic profile and adheres to Lipinski’s Rule of Five, demonstrating efficient absorption and distribution. Consequently, the study supports the use of oxymetazoline as an inhibitor of α1A and α2A adrenergic receptors.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142826151","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":"Results from ON-OFF Analysis of the Neutrinos-Angra Detector","authors":"Ernesto Kemp,&nbsp;Willian Vieira dos Santos,&nbsp;João C. dos Anjos,&nbsp;Pietro Chimenti,&nbsp;Luis Fernando Gomez Gonzalez,&nbsp;Germano P. Guedes,&nbsp;Herman P. Lima Jr.,&nbsp;Rafael Antunes Nóbrega,&nbsp;Iuri Muniz Pepe,&nbsp;Dion Barbosa dos Santos Ribeiro","doi":"10.1007/s13538-024-01667-9","DOIUrl":"10.1007/s13538-024-01667-9","url":null,"abstract":"<div><p>The Neutrinos Angra Experiment, a water-based Cherenkov detector, is located at the Angra dos Reis nuclear power plant in Brazil. Designed to detect electron antineutrinos produced in the nuclear reactor, the primary objective of the experiment is to demonstrate the feasibility of monitoring reactor activity using an antineutrino detector. This effort aligns with the International Atomic Energy Agency (IAEA) program to identify potential and novel technologies applicable to nonproliferation safeguards. Operating on the surface presents challenges such as high noise rates, necessitating the development of very sensitive, yet small-scale detectors. These conditions make the Angra experiment an excellent platform for both developing the application and gaining expertise in new technologies and analysis methods. The detector employs a water-based target doped with gadolinium to enhance its sensitivity to antineutrinos. In this work, we describe the main features of the detector and the electronics chain, including front-end and data acquisition components. We detail the data acquisition strategies and the methodologies applied for signal processing and event selection. Preliminary physics results suggest that the detector can reliably monitor reactor operations by detecting the inverse beta decay induced by electron antineutrinos from the reactor.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142826152","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":"Electrochemical Deposition of Ag/C Films: Effects of Silver Concentration on Structural, Optical, and Electrical Properties","authors":"Onur Nur,&nbsp;Alper Çetinel","doi":"10.1007/s13538-024-01675-9","DOIUrl":"10.1007/s13538-024-01675-9","url":null,"abstract":"<div><p>Silver-carbon (Ag/C) composite films were successfully fabricated on PET/ITO substrates using a novel two-step electrochemical deposition method. The impact of silver concentration on the structural, optical, and electrical properties of the films was systematically investigated. Scanning electron microscopy (SEM) revealed a heterogeneous film structure, with carbon conforming to the underlying silver morphology, which varied with silver concentration. Higher silver concentrations resulted in larger and denser silver structures. Optical characterization demonstrated that the addition of carbon significantly enhanced transmittance, particularly at lower silver concentrations, making these films promising candidates for transparent conductive electrodes. Both Ag and Ag/C films exhibited ohmic behavior, as evidenced by linear current–voltage (I-V) characteristics. Ag/C films showed superior conductivity compared to pure Ag films, attributed to the contribution of the carbon layer to electron transport. Hall measurements further confirmed the enhanced electrical properties of Ag/C films, revealing lower sheet resistance and resistivity compared to Ag films. The improved homogeneity of Ag/C films, due to the incorporation of carbon, is beneficial for achieving uniform electrical properties. These findings highlight the potential of electrochemically deposited Ag/C composites for various technological applications, including flexible electronics, optoelectronics, sensors, and energy storage devices.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821485","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":"A New Toroidal Capacitive Discharge Plasma Vessel Design and Implementation for Plasma Studies","authors":"E. Kurt,&nbsp;B. Dursun,&nbsp;K. Çelik","doi":"10.1007/s13538-024-01680-y","DOIUrl":"10.1007/s13538-024-01680-y","url":null,"abstract":"<div><p>A new toroidal capacitive discharge plasma (TCDP) system is designed and constructed for the first time to our knowledge. This device has been created for the exploration of plasma-material interactions including metal and semiconductor samples for different pressure rates. By using two materials, namely copper (Cu) and tungsten (W), initially, electrode couples have been tested for high-voltage DC excitations. The reactions of electron material to the low-pressure helium (He) have been observed. Then, Paschen’s curve exploration has been performed to find out the gas discharge threshold electrical potentials for various pressure (<i>P</i>) rates. The simulations of TCDP device have been performed in a particle in cell (PIC) analyzed 3D structure in the CST Studio medium for various excitation frequencies and toroidal/poloidal field values. It is observed that the breakdown voltage for He is <i>U</i>_<i>B</i> = 500 V. The DC excitation via the electrodes reveals that the torus-structured plasma gas media produces a stable torus-shaped media for plasma formation. Besides, toroidal and poloidal fields affect the plasma stabilization in the TCDP. Especially toroidal field coils in TCDP assist in keeping the plasma in the middle of the torus channel. According to the experiments, the poloidal fields increase the electric field strength in the angular direction and improve the electrical stability of the plasma between the electrodes.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142810913","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":"Weak Transitions Effect from First Excited States in Core of Massive Star in Pre-supernova Phase","authors":"S. C. Rocha,&nbsp;A. R. Samana,&nbsp;A. J. Dimarco,&nbsp;C. A. Barbero,&nbsp;M. dos Santos,&nbsp;C. De Conti","doi":"10.1007/s13538-024-01671-z","DOIUrl":"10.1007/s13538-024-01671-z","url":null,"abstract":"<div><p>Massive stars in the pre-supernova stage are characterized by a compound core of chemical elements of the iron group, subject to nuclear reactions provided by the weak interaction. The rates at which these reactions occur, particularly the <span>(varvec{beta })</span>-decay and the electron capture, influence the electron fraction in the core, and these particles are responsible for generating a degeneracy pressure that counteracts the gravitational collapse. We calculate electron capture and <span>(varvec{beta }^-)</span>-decay rates for a set of <span>(textbf{63})</span> nuclei (previously adopted in Dimarco et al., J. Phys. G Nucl. Part. Phys. 28 121 2002) of relevance in the pre-supernova stage for transitions not only from the ground state but also considering first excited states in the parent nucleus, using the gross theory of beta decay (GTBD) associated to Brink’s hypothesis. The evolution of the electron fraction has been calculated using these weak interaction rates, and the results have been compared with other models, showing that transitions between low-lying first excited states and Gamow-Teller resonances can contribute at this stage of stellar evolution as the temperature and density increase.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142798438","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":"Tuning the Disorder Structure of Complex Plasmas Using an Electric Field","authors":"Muhammad Asif Shakoori,&nbsp;Misbah Khan,&nbsp;Haipeng Li,&nbsp;Syed Ali Raza,&nbsp;Muhammad Riaz","doi":"10.1007/s13538-024-01666-w","DOIUrl":"10.1007/s13538-024-01666-w","url":null,"abstract":"<div><p>In this study, an electric field (<i>E</i>^<i>*</i>) has been used to tune the disorder structures of complex plasmas (CPs) using molecular dynamics (MD) simulations. The <i>ψ</i>(<i>τ</i>) (lattice correlation) and RDF (radial distribution function) are computed for CPs under the presence and absence of different <i>E</i>^<i>*</i> intensities to analyze structures. The influence of <i>E</i>^<i>*</i> strengths, coupling (<i>Γ</i>), and screening length (<i>κ</i>) on structure transitions is investigated. Without <i>E</i>^<i>*</i>, MD simulation results for <i>ψ(τ)</i> and RDF indicated self-organization of dust particles with increasing <i>Γ</i> and decreasing <i>κ</i>. Additionally, CPs subjected to higher <i>E</i>^<i>*</i> intensities exhibited signs of condensation and solidification. Achieving solidification required a significantly higher <i>E</i>^<i>*</i> intensity for disordered structures (nonideal gases), whereas liquid-like or nearly solid-like structures required intermediate to low <i>E</i>^<i>*</i> intensities. Moreover, to induce crystalline long-range order in the presence of <i>E</i>^<i>*</i>, by keeping the <i>Γ</i> constant, higher values of <i>κ</i> required a larger <i>E</i>^<i>*</i>. It was observed that CPs exhibited behavior akin to conventional electrorheological fluids in the presence of <i>E</i>^<i>*</i>. This characteristic renders CPs valuable for investigating electrorheological properties in soft and condensed matter physics.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142790312","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}