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Effects of rare-earth Pr3+-Dy3+ doping on structural,magnetic,optical and dielectric properties of Zn2Y hexaferrite

Journal of Rare Earths 2025年第2期43卷 329-336页

作者： Ibrahim Mohammed Mohamed E.El Sayed Ali Shawabkeh Mohammad N.Murshed Ibtehaj F.Alshdoukhi Zeinhom M.El-Bahy J.Mohammed A.K.Srivastava department of Physics Lovely Professional University department of science Technology Waziri Umaru Federal Polytechnic Birnin Kebbi Physics department Faculty of Science and ArtsKing Khalid University College of Engineering and Technology American University of the Middle East department of Basic sciences College of Science and Health ProfessionsKing Saud Bin Abdulaziz University for Health ScienceKing Abdullah International Medical Research Center department of Chemistry Faculty of ScienceAl-Azhar University department of Physics Faculty of ScienceFederal University Dutse

This study was conducted to investigate the properties of Pr3+-Dy3+doped Zn2Y-type hexaferrite for potential technological applications.X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FTIR） and field-emission scanning electron microscopy（FESEM） were used to analyze structural *** crystallite size in the synthesized samples varies between 57.54 and 68.57 *** vibrational bands at 400 and 600 cm-1,common to all hexaferrites,were confirmed through *** FESEM analysis reveals an agglomeration of magnetic grains and a decrease in the average grain size from 1.24 to1.06 μ*** M-H loops show that,with x values of 0.0,0.1,and 0.2,the saturation magnetization is determined to be 34.76,34.23,and 32.52 emu/g,*** corresponding coercivity values are21.24,30.39,and 33.99 ***-visible spectroscopy using Tauc theory reveals an increase in the optical band gap from 2.32 to 2.50 eV,indicating a tunable energy band structure by incorporating Pr3+-Dy3+*** dielectric constant increases,whereas AC conductivity decreases with increased Pr3+-Dy3+*** obtained results suggest the potential suitability of these materials for various technological applications.

关键词： Dielectric constant Magnetic hysteresis Optical band gap Pr3+-Dy3+ Rare earths Zn2Y-type hexaferrite

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Cross-correlations between signal's components

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Chinese Physics B 2025年第2期34卷 483-494页

作者： Quankun Zhao Sen Li Changgui Gu Haiying Wang Huijie Yang department of Systems science University of Shanghai for Science and TechnologyShanghai 200093China

Detecting coupling pattern between elements in a complex system is a basic task in data-driven analysis. The trajectory for each specific element is a cooperative result of its intrinsic dynamic, its couplings with other elements, and the environment. It is subsequently composed of many components, only some of which take part in the couplings. In this paper we present a framework to detect the component correlation pattern. Firstly, the interested trajectories are decomposed into components by using decomposing methods such as the Fourier expansion and the Wavelet transformation. Secondly, the cross-correlations between the components are calculated, resulting into a component cross-correlation matrix(network).Finally, the dominant structure in the network is identified to characterize the coupling pattern in the system. Several deterministic dynamical models turn out to be characterized with rich structures such as the clustering of the components. The pattern of correlation between respiratory(RESP) and ECG signals is composed of five sub-clusters that are mainly formed by the components in ECG signal. Interestingly, only 7 components from RESP(scattered in four sub-clusters) take part in the realization of coupling between the two signals.

关键词： coupling structure cross-correlation matrix component correlation network

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On Sawada-Kotera and Kaup-Kuperschmidt integrable systems

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Communications in Theoretical Physics 2025年第2期77卷 23-31页

作者： Metin Gürses Asl| Pekcan department of Mathematics Faculty of Science Bilkent University department of Mathematics Faculty of Science Hacettepe University

To obtain new integrable nonlinear differential equations there are some well-known methods such as Lax equations with different Lax representations. There are also some other methods that are based on integrable scalar nonlinear partial differential equations. We show that some systems of integrable equations published recently are the M2-extension of integrable such scalar equations. For illustration, we give Korteweg–de Vries, Kaup-Kupershmidt, and SawadaKotera equations as examples. By the use of such an extension of integrable scalar equations, we obtain some new integrable systems with recursion operators. We also give the soliton solutions of the systems and integrable standard nonlocal and shifted nonlocal reductions of these systems.

关键词： recursion operator nonlocal reductions Hirota bilinear form soliton solutions .M2-extension recursion operator nonlocal reductions Hirota bilinear form soliton solutions

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Transport mechanism in chemically reactive hybrid nanofluid flow containing gyrotactic micro-organisms over a curved oscillatory surface

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 177-192页

作者： M.NAVEED M.IMRAN T.ASGHAR Z.ABBAS department of Mathematics Division of Science and TechnologyUniversity of Education department of Mathematics The Islamia University of Bahawalpur

This paper examines the transport analysis, including both heat transfer and mass transfer, in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface. The influence of magnetic fields is also inspected in terms of their physical characteristics. To depict the phenomena of transport, modified versions of both Fick's and Fourier's laws are used. Additionally, the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated. Utilizing a curvilinear coordinate system, the flow problem is formulated as partial differential equations(PDEs)for momentum, concentration, microorganism field, and energy. An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAM).The effects of significant flow parameters on the pressure and microorganism fields, velocity, oscillation velocity, concentration, and temperature distributions are shown via graphs. Furthermore, the variations in skin friction, mass transfer rate, heat transfer rate, and local motile number due to different involved parameters are presented in tables and are analyzed in detail. Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables *** is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase, and it increases with the Schmidt number and the heterogeneous reaction strength *** outcomes show a favorable response of the motile number to advanced values of the Peclet number, the Schmidt number, the microorganism difference parameter, and the bio-convective Lewis number.

关键词： analytical solution Cattaneo-Christov heat and mass flux chemical reaction gyrotactic microorganism hybrid nanofluid O368 oscillating curved stretchable sheet

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Evidence for active generation and seepage of sub-salt natural gas/condensate blend in the east offshore Nile Delta, Egypt: Integrated geochemical, petrophysical and seismic attribute approaches

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Petroleum science 2025年第1期22卷 130-150页

作者： Mahmoud Leila Ahmed A.Radwan Amir Ismail Emad A.Eysa Geology department Faculty of Science Mansoura University School of Mining and Geosciences Nazarbayev University department of Geology Faculty of Science Al-Azhar UniversityAssiut Branch department of Geology Faculty of Science Helwan University department of Physical and Environmental sciences Texas A&M University—Corpus Christi Geology department Faculty of Science Zagazig University

Offshore Nile Delta in Egypt represents an enormous hydrocarbon province with recent projected gas and condensate discoveries of more than 50 trillion cubic feet “TCF”. Most of these occur in the post-salt hydrocarbon plays where biogenic gases are dominant. This study integrates organic geochemistry,seismic geomorphology and petrophysics in order to decipher the origin, and accumulation conditions of the wet gas/condensate blend in the Upper Miocene sub-salt Wakar Formation sandstones in Port Fouad Marine “PFM” Field, offshore Nile Delta. Hydrocarbon pay zones are scattered thin（ 1 w.t.%, hydrogen index“HI” > 200 mg HC/g TOC） and mature(Tmax> 430°C, vitrinite reflectance “VR” > 0.6 %R_o), source rocks are restricted to Upper Miocene Wakar and Oligo-Miocene Tineh formations. The latter contains more mature organofacies（up to 1.2 %R_o） and type II/III kerogen, thereby demonstrating a good capability to generate wet gases. The studied gas is wet and has thermogenic origin with signs of secondary microbial alteration, whereas the condensate contains a mixture of marine and terrestrial input. Molecular biomarkers of the condensate, isotopic and molecular composition of the gas reveals a generation of condensate prior to gas expulsion from the source. The Wakar sandstones have a heterogeneous pore system where three reservoir rock types（RRTI, RRTII and RRTIII）. RRTI rocks present the bulk composition of the Wakar pay zones. Spatial distribution of RRTI facies likely control the accumulation of the sub-salt hydrocarbons. Our results provide a new evidence on an active petroleum system in the sub-salt Paleogene successions in the offshore Nile Delta where concomitant generation of ga

关键词： Petrophysical evaluation Source rock Hydrocarbon geochemistry Biomarkers Gas chimneys Rock-typing

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Effect of divalent cations(Co^(2+) and Ni^(2+)) on microstructure,physical properties and application of NdFeO_(3)

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Journal of Rare Earths 2025年第1期43卷 89-97,I0004页

作者： M.M.Arman Materials science Lab(1) Physics DepartmentFaculty of ScienceCairo UniversityGiza12613Egypt

The nanocrystalline samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))were prepared using the citrate combustion *** X-ray diffraction(XRD)pattern confirmed that the nanoparticles were synthesized in an orthorhombic *** particle size of Nd_(1-x)M_(x)FeO_(3) is in the range of 29-59 *** selected area electron diffraction(SAED)indicates the samples were prepared in a polycrystalline *** samples Nd_(1-x)M_(x)FeO_(3)(x=0.0 and 0.1;M:Co^(2+)and Ni^(2+))have anti ferromagnetic *** Fe^(3+)spins are aligned antiparallel,forming the antiferromagnetic(AFM)properties,which are affected by many factors such as the bond angle between the Fe^(3+)(Fe^(3+)-O_(2)--Fe^(3+))and the Dzyaloshinskii-Moriya(D-M)*** doping of Co^(2+)and Ni^(2+)ions in NdFeO_(3) enhances the magnetic properties of the NdFeO_(3).The saturation magnetization(Ms)of Nd_(0.90)Co_(0.10)FeO_(3) increases 1.8times more than that of NdFeO_(3).The exchange bias field(HEX)of the Co-doped sample is two times greater than that of NdFeO_(3).The magnetic anisotropy constant(K)of the 10%Co-doped sample increases by 11 factors compared to that of NdFeO_(3).The Tauc plot illustrates that the samples have a direct optical *** divalent cation substitution(Co^(2+)and Ni^(2+))decreases the optical band gap of NdFeO_(3),leading to the recommendation of using the samples Nd_(0.90)Co_(0.10)FeO_(3) and Nd_(0.90)Ni_(0.10)FeO_(3) in photocatalysis of dye degradation from *** removal efficiencies of Cr6+at pH=6 are 88.06%,85.54%,and 85.52%for the samples NdFeO_(3),Nd_(0.90)Co_(0.10)FeO_(3),and Nd_(0.90)Ni_(0.10)FeO_(3),*** Freundlich isotherm mode is the best-fit model for NdFeO_(3) to adsorb Cr6+ions from aqueous solutions.

关键词： Optical properties Nanoparticles Magnetic properties Perovskites Removal efficiency Rareearths

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Graphene derivatives as efficient hole transport materials for lead-free double perovskite（Cs2SnI6） solar cells: a numerical study

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Optoelectronics Letters 2025年第3期21卷 155-159页

作者： Sarita YADAV Saral K.GUPTA Chandra Mohan Singh NEGI department of Physical science Banasthali Vidyapith

The double perovskite Cs2SnI6has notable optical and electrical characteristics, rendering it a highly prospective candidate for deployment as the absorber layer in perovskite solar cells （PSCs）. We simulated the performance of PSCs using lead-free Cs2SnI6double perovskite absorber layer and graphene derivatives, namely graphene oxide （GO） and reduced graphene oxide （rGO）, as hole transport layers （HTLs）. Our findings show that r GO offers an excellent hole extraction property with minimal interfacial recombination compared to GO.

关键词： A

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A Multi-faceted View of the X-Ray Spectral Variability in Seyfert Galaxy Ark 120

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Research in Astronomy and Astrophysics 2025年第1期25卷 228-239页

作者： Lu-Xin Ren Jun-Xian Wang Jia-Lai Kang CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of China School of Astronomy and Space science University of Science and Technology of China

Utilizing a range of techniques including multi-band light curves,softness ratio analysis,structure functions,rms spectra,cross-correlation functions,and ratios of spectra from different intervals,we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120,through re-analyzing its six XMM-Newton observations taken between 2003 and *** find a clear“softer-when-brighter”trend in the 2–10 ke V power-law component over long timescales,with this trend being timescale dependent,as it is much weaker on shorter timescales,similar to that previously detected in NGC ***,a rare“harder-when-brighter”trend is observed during one exposure,indicating dynamic changes in the spectral variability behavior of the power-law *** exceptional exposure,with the spectral variability indeed marked by a power-law pivoting at an unusually low energy of～2 ke V,suggests intricate variations in the thermal Comptonization processes within the ***,when the data below 2 ke V are included,we identify that the soft excess component adds significant complexity to the spectral variability,such as evidenced by a transition from“harder-when-brighter”to“softer-when-brighter”during another single *** extra complexity arises because the variability of the soft excess sometimes follows and sometimes does not follow the changes in the power-law *** findings underscore the necessity of applying multiple analytic techniques to fully capture the multifaceted spectral variability of AGNs.

关键词： galaxies: active galaxies: Seyfert X-rays: galaxies

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GPS: graph contrastive learning via multi-scale augmented views from adversarial pooling

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science China(Information sciences) 2025年第1期68卷 145-158页

作者： Wei JU Yiyang GU Zhengyang MAO Ziyue QIAO Yifang QIN Xiao LUO Hui XIONG Ming ZHANG School of Computer science National Key Laboratory for Multimedia Information ProcessingPeking University Artificial Intelligence Thrust The Hong Kong University of Science and Technology department of Computer science University of California

Self-supervised graph representation learning has recently shown considerable promise in a range of fields, including bioinformatics and social networks. A large number of graph contrastive learning approaches have shown promising performance for representation learning on graphs, which train models by maximizing agreement between original graphs and their augmented views(i.e., positive views). Unfortunately, these methods usually involve pre-defined augmentation strategies based on the knowledge of human experts. Moreover, these strategies may fail to generate challenging positive views to provide sufficient supervision signals. In this paper, we present a novel approach named graph pooling contrast(GPS) to address these *** by the fact that graph pooling can adaptively coarsen the graph with the removal of redundancy, we rethink graph pooling and leverage it to automatically generate multi-scale positive views with varying emphasis on providing challenging positives and preserving semantics, i.e., strongly-augmented view and weakly-augmented view. Then, we incorporate both views into a joint contrastive learning framework with similarity learning and consistency learning, where our pooling module is adversarially trained with respect to the encoder for adversarial robustness. Experiments on twelve datasets on both graph classification and transfer learning tasks verify the superiority of the proposed method over its counterparts.

关键词： graph representation learning graph neural networks graph contrastive learning graph augmentations graph pooling

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Application of feedforward and recurrent neural networks for model-based control systems

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Control Theory and Technology 2025年第1期23卷 91-104页

作者： Marek Krok Wojciech P.Hunek Szymon Mielczarek Filip Buchwald Adam Kolender department of Control science and Engineering Opole University of TechnologyOpolePoland

In this paper,a new study concerning the usage of artificial neural networks in the control application is *** is shown,that the data gathered during proper operation of a given control plant can be used in the learning process to fully embrace the control ***,the instances driven by neural networks have the ability to outperform the original analytically driven *** different control schemes,namely perfect,linear-quadratic,and generalized predictive controllers were used in the theoretical *** addition,the nonlinear recurrent neural network-based generalized predictive controller with the radial basis function-originated predictor was obtained to exemplify the main results of the paper regarding the real-world application.

关键词： Predictive control Linear-quadratic control Inverse problems Feedforward network Recurrent neural network Optimization

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