Brazilian Journal of Physics最新文献

{"title":"Exploration and Screening of Database of Polycyclic Aromatic Hydrocarbons to Find Compounds with Lower Enthalpy of Formation","authors":"Maymounah N. Alharthi,&nbsp;Tagir Kadyrov,&nbsp;Khadijah Mohammedsaleh Katubi,&nbsp;M. S. Al-Buriahi","doi":"10.1007/s13538-026-02130-7","DOIUrl":"10.1007/s13538-026-02130-7","url":null,"abstract":"<div><p>Accurate prediction of thermodynamic properties such as enthalpy of formation (ΔH_f) is essential for designing chemical compounds with targeted stability and performance. In this study, a computational screening of polycyclic aromatic hydrocarbons (PAHs) was conducted using machine learning (ML) models trained on experimentally reported ΔH_f values. Over 200 molecular descriptors were calculated via RDKit, with feature selection guided by correlation analysis to retain the most relevant parameters. Twelve ML algorithms were evaluated, with CatBoost and XGBoost demonstrating superior predictive accuracy, achieving R² scores above 0.95 on validation sets. These optimized models were applied to the COMPAS database of ~ 34,000 PAHs to identify candidates with low predicted ΔH_f values. Fifty top-ranked compounds were shortlisted based on predicted thermodynamic stability, synthetic accessibility (SA), and chemical similarity network (CSN) analysis. Selected candidates exhibited SA scores between 1.4 and 1.9, suggesting feasible synthesis routes. Visualization via t-SNE and CSN highlighted structural diversity while confirming clustering of low-ΔH_f compounds. The approach demonstrates the integration of ML prediction, synthetic feasibility assessment, and chemical space mapping as an efficient strategy for targeted molecular discovery.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466503","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":"Deep Learning of Charged Particles Motion in Media with Loss-Induced Topological Transitions of Dispersion Surfaces","authors":"Morteza Mohseni","doi":"10.1007/s13538-026-02129-0","DOIUrl":"10.1007/s13538-026-02129-0","url":null,"abstract":"<div><p>We study the dynamics of charged particles in uniaxial lossless and lossy magnetic media. For lossless case, the dispersion surfaces have spherical topology and the trajectories of the particles show no bifurcations. For the case where loss is present, the dispersion surfaces are hyperboloids and for some values of the particles momenta, bifurcations occur. This is shown by deploying the AI Poincaré algorithm to obtain the corresponding explained variance ratios. The behavior of these explained ratios change at bifurcations. We show this for some values of the permeability tensor components and some different choices of the initial conditions.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466502","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 Facile Synthesis of Nano-Phasic Bi5FeTi3O15 Layered Photoferroelectrics for Photocatalytic Application Induced With Visible Light","authors":"Srishti Rai,&nbsp;P. K. Bajpai,&nbsp;Amit Srivsatava,&nbsp;Rakesh Kumar Singh,&nbsp;Jai Singh","doi":"10.1007/s13538-026-02124-5","DOIUrl":"10.1007/s13538-026-02124-5","url":null,"abstract":"<div><p>In the present report, aurivillius phase Bi₅FeTi₃O₁₅ (BFTO) nanoparticles with enhanced charge separation, attributed to their ferroelectric properties, have been successfully synthesized through a sol-gel method, and subsequently investigated their photocatalytic activity. Various analytical techniques, including X-ray diffraction(XRD), Raman Spectroscopy, Scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDS), Fourier transform infrared spectroscopy (FTIR), Energy Dispersive X-Ray Fluorescence (EDXRF) and UV-Vis spectroscopy have been employed to investigate the structural features, surface morphology, and optical properties of the as-prepared samples. The XRD and subsequent Rietveld refinement confirmed that the BFTO nanoparticles exhibit a single-phase orthorhombic structure with the space group A21am. Furthermore, EDXRF and EDS confirm the formation of BFTO, UV-Vis spectra confirmed the occurrence of a direct band gap in the BFTO nanoparticles with a band gap energy of ~ 2.7 eV. Under an applied voltage of 8000 V, the remanent polarization (Pr) and coercive field have been evaluated as ~ 53.88 µC/cm² and 256.034 kV/cm, respectively. In addition, the degradation of Methyl Orange (MO) in an aqueous solution under visible light has been carried out to assess the photocatalytic activity of the as-synthesised BFTO nanoparticles. After nearly 3 h in white light irradiation, a notable rise in MO deterioration has been noted. Because of their high effectiveness in breaking down MO dye, BFTO nanoparticles show a lot of promise as a photocatalyst for the breakdown of hazardous &amp; vulnerable compounds and other organic pollutants when exposed to visible light.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465573","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":"Decay Parameter for Continuous-Time Open Quantum Walks","authors":"Newton Loebens","doi":"10.1007/s13538-026-02125-4","DOIUrl":"10.1007/s13538-026-02125-4","url":null,"abstract":"<div><p>In this paper we study the exponential decay parameter for continuous-time open quantum walks. This statistic is obtained by a composed function that associates the natural logarithm to the transition probability of the walk, being inspired by the classical decay parameter of continuous-time Markov chains. The existence of this statistic is proven for finite graphs where each vertex has a finite degree of freedom, and it is intimately connected to the spectrum of the Lindblad generator describing the dynamics. We show that faithful states yield the slowest decay, whereas non-faithful states can accelerate decay and modify the communication structure of the graph, a phenomenon with no classical analogue. Extensions to infinite graphs are discussed as open problems and conjectures. An equivalence theorem relating different notions of recurrence is established under the hypothesis that the decay parameter exists.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-026-02125-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465500","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":"Comment on “Investigation of physical properties of NaBaX3 (X = Cl, Br, and I) cubic perovskites using first-principles density-functional theory” [Braz. J. Phys. 55 (2025) 207]","authors":"Nadhira Bioud","doi":"10.1007/s13538-026-02126-3","DOIUrl":"10.1007/s13538-026-02126-3","url":null,"abstract":"<div><p>Very recently, Parosh et al. [1] report a theoretical results on many physical properties of NaBaX₃ (X = Cl, Br, and I) perovskite materials. Our examination of the paper [1] shows that some data are not calculated correctly, especially these of the longitudinal (<i>v</i>_<i>l</i>), transverse (<i>v</i>_<i>t</i>) and mean (<i>v</i>_<i>m</i>) sound velocities, Debye temperature (<i>θ</i>_<i>D</i>), and minimum thermal conductivity (<i>k</i>_<i>min</i>). Furthermore, some other inaccuracies have been found, notably: the expression of the formula used to calculate the Debye temperature (<i>θ</i>_<i>D</i>), in the trend of <i>θ</i>_<i>D</i> as a function of temperature, and in the Dulong–Petit limit for the heat capacity <i>C</i>_<i>V</i>. In this paper, we purpose to correct the expression of the formula used to calculate <i>θ</i>_<i>D</i>, as well as to correct the values of <i>v</i>_<i>l</i>, <i>v</i>_<i>t</i>, <i>v</i>_<i>m</i>, <i>θ</i>_<i>D</i>, and <i>k</i>_<i>min</i> for NaBaX₃ (X = Cl, Br, and I) compounds, using the lattice constants (<i>a</i>) and the elastic constants (<i>C</i>_<i>ij</i>) obtained by Parosh et al. [1].</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465431","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":"Sinusoidal Memristive Neuron Model for Hyperchaotic Dynamics: Microcontroller Implementation and Robust Synchronization via Non-Singular Sliding-Mode Control","authors":"Aicha Sidica Gboulie Pofoura,&nbsp;Romanic Kengne,&nbsp;André Rodrigue Tchamda,&nbsp;Raoul Mbakob Yonkeu,&nbsp;Marceline Motchongom Tingue,&nbsp;Timoléon Crépin Kofane","doi":"10.1007/s13538-026-02113-8","DOIUrl":"10.1007/s13538-026-02113-8","url":null,"abstract":"<div><p>This study explores a discrete memristive neuron model based on sinusoidal transformation (MBST), filling a gap in chaotic neural network research. By coupling a sinusoidal memristor to a discrete neuron model, the system exhibited improved hyperchaotic dynamics, as confirmed by phase portraits, bifurcation diagrams and Lyapunov spectra. The fixed-point method analyzes stability, whereas linear augmentation effectively controls multi-stability by moving the system to a monostable regime. For synchronization, a master-slave architecture with non-singular sliding-mode control outperforms traditional adaptive methods, ensuring robust coordination between neurons. Hardware validation using an ATmega 2560 microcontroller demonstrated real-time feasibility, with results matching those of numerical simulations. A TFT screen (320x480 pixels) was used to visualize the hyperchaotic dynamics, thereby confirming its practical implementation. The complex and controllable behavior of this model offers perspectives for chaos-based encryption, leveraging its unpredictability and synchronization properties.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465136","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":"Relativistic Entanglement in Muon Decay","authors":"S. Carneiro,&nbsp;F. C. Sobrinho","doi":"10.1007/s13538-026-02119-2","DOIUrl":"10.1007/s13538-026-02119-2","url":null,"abstract":"<div><p>We discuss the time evolution of quantum entanglement in the presence of non-collapsing interactions. In particular, the entanglement between the products of a muon decay in a magnetic field is revisited. It results from angular momentum conservation and leads to an anomaly in the measured muon <i>g</i> factor in precise agreement with that reported by the Brookhaven and Fermilab experiments, alleviating the present tension between data-driven and lattice theoretical values.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-026-02119-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148366004","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":"Astrophysical S-Factor for the 6Li(p,γ)7Be Reaction with Pionless Effective Field Theory at Low Energies","authors":"Masoumeh Dalvand,&nbsp;Hassan Khalili,&nbsp;Shahla Nahidinezhad,&nbsp;Seyed Amin Cheshmi,&nbsp;Amir Hooman Aranpour","doi":"10.1007/s13538-026-02121-8","DOIUrl":"10.1007/s13538-026-02121-8","url":null,"abstract":"<div><p>The proton -radiative capture reaction ⁶Li (p<i>, γ</i>)⁷Be is of outstanding importance in nuclear physics and astrophysics, in particular in understanding key processes of nucleosynthesis on cosmic scales. This reaction plays a decisive role not only in the early stages of Big Bang Nucleosynthesis (BBN), where the production of light elements is modeled in the first minutes after the Big Bang, but also in stellar fusion chains, in particular in the side branches of the proton-proton chain (pp-chain) in Sun-like stars. In addition, ⁶Li(p<i>,γ</i>)⁷Be acts as one of the channels for the loss of ⁶Li in relatively low-temperature stellar environments and is therefore also of importance in the study of the relative abundances of light elements in the Universe and the chemical evolution of galaxies. At very low energies relevant to astrophysical environments (especially in the range of a few keV), the nuclear cross section is strongly influenced by a range of non-nuclear influences, suppressed by the Coulomb potential and significant quantum mechanical effects. To normalize these effects and extract the intrinsic nuclear behavior, the astrophysical S-factor is used, which describes the behavior of the cross section in a regular manner in the low-energy limit, where the probability of Coulomb penetration is low. In the case of the ⁶Li (p<i>, γ</i>) ⁷Be reaction, the S-factor at sub-Coulomb energies is mainly controlled by electric dipole (E1) transitions from the S-wave input state (in the p + ⁶Li system) to the ground states of ⁷Be with ²P_1/2 and ²P_3/2.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380217","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":"Design, Synthesis, and Investigation of the Photodiode Performance of a Novel D–π–A–π–D-Type Organic Semiconductor Based on Dibenzosuberenone with Anthracenyl Donors","authors":"Khadijeh Ganjehyan,&nbsp;Zakir Çaldıran,&nbsp;Ali Rıza Deniz,&nbsp;Musa Erdoğan","doi":"10.1007/s13538-026-02122-7","DOIUrl":"10.1007/s13538-026-02122-7","url":null,"abstract":"<div><p>Organic photodiodes based on donor–π–acceptor (D–π–A) molecular architectures have attracted significant attention owing to their tunable optoelectronic properties, solution-processability, and potential for low-cost photodetection applications. However, despite the remarkable photophysical characteristics of dibenzosuberenone derivatives, studies investigating anthracene-functionalized dibenzosuberenone-based D–π–A–π–D systems for photodiode applications remain very limited in the literature. In this study, a novel π-conjugated organic semiconductor (BADA) possessing a D–π–A–π–D architecture was rationally designed and synthesized starting from dibenzosuberone through multistep aromatic functionalization and Sonogashira coupling reactions. The resulting molecule consists of anthracenyl donor units, linear ethynyl π-bridges, and a dibenzosuberenone acceptor core, providing an extended delocalized electronic framework. Subsequently, an Au/BADA/p-Si/Al Schottky-type photodiode was fabricated by spin-coating the BADA interfacial layer onto p-type silicon followed by thermal evaporation of Au and Al contacts. The electrical and photoresponse characteristics of the fabricated device were systematically investigated under illumination intensities ranging from 20 to 100 mW/cm². The ideality factor (n) increased from 1.74 in the dark to 3.96 under illumination, while the barrier height (Φ_b) decreased from 0.76 eV to 0.57 eV, indicating illumination-induced barrier modulation effects. The photocurrent exhibited a power-law dependence on light intensity with an exponent of m = 1.10, revealing nearly linear and slightly super-linear behavior. The responsivity (R) was found to vary between 1.46 × 10⁻⁶ and 1.60 × 10⁻⁶A/W, while the specific detectivity (D^*) ranged from 7.9 × 10⁷ to 9.3 × 10⁷ Jones within the investigated illumination range. The photosensitivity increased monotonically, reaching approximately 15 at 100 mW/cm². The obtained results demonstrate that the Au/BADA/p-Si/Al structure exhibits stable and reproducible photoresponse characteristics and represents a promising candidate for organic photodetector applications.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380883","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 Decoherence of the Surface Code: A Generalized Caldeira-Leggett Approach","authors":"E. Novais,&nbsp;A. H. Castro-Neto","doi":"10.1007/s13538-026-02120-9","DOIUrl":"10.1007/s13538-026-02120-9","url":null,"abstract":"<div><p>Standard quantum error correction (QEC) models typically assume discrete, Markovian noise. This assumption obscures the continuous quantum nature of physical environments. We investigate the fundamental limits of an actively corrected surface code coupled to a continuous, un-reset quantum environment at zero and finite temperature. Using the generalized Caldeira-Leggett framework, we map the long-time evolution of the logical qubit to a boundary conformal field theory, establishing an exact equivalence to the anisotropic Kondo model. We evaluate computational times for a finite code distance <i>L</i> for all spatial and temporal correlations. Our analysis reveals that a true thermodynamic threshold exists strictly for short-range environments (<span>(z&gt;1/(s+1))</span>), where <i>z</i> is the dynamical exponent of the environment and <i>s</i> is the exponent of the spectral density. In critical or long-range regimes, the macroscopic footprint of the code amplifies the continuous bath, hindering the topological protection.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"56 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13538-026-02120-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148323782","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}