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Enhancement of coercivity,permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites for memory and high frequency devices

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Journal of Rare Earths 2024年第6期42卷 1128-1135,I0005页

作者： I.Sardar m.d.hossain m.S.Sikder m.N.I.Khan m.R.Rahman Physics discipline Khulna UniversityKhulna9208Bangladesh department of Physics Khulna University of Engineering&TechnologyKhulna9203Bangladesh department ofComputer Science and Engineering Northern University of Business&Technology KhulnaKhulna9100Bangladesh material Science division Atomic Energy CentreDhaka1000Bangladesh

Spinel cubic ferrites have huge applications in me mory and high frequency *** the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important *** article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and *** X-ray diffraction(XRd),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEm),energy dispersive X-ray(EdX),vibrating sample magnetometer(VSm),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the *** XRd patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped *** densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu *** FTIR analysis also proves the spinel cubic phase of the *** average grain size of the ferrites is obtained via FESEm images,and it is increased from 121 to 198 *** analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ***,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EdX study shows that there is no impurity contamination in the *** permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric *** dependent resistivity and impedance analysis also show the improved *** the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.

关键词： Ferrites Raree arths Coercivity Permeability EdX Resistivity

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Anti-amyloid antibodies in Alzheimer’s disease: what did clinical trials teach us?

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Neural Regeneration Research 2025年第4期20卷 1092-1093页

作者： danko Jeremic Lydia Jiménez-díaz Juan d.Navarro-López NeuroPhysiology&Behavior Lab University of Castilla-La ManchaBiomedical Research Center(CRIB)School of Medicine of Ciudad RealCiudad RealSpain

Although many causes of Alzheimer’s disease(Ad)may exist,both the original amyloid cascade and tau hypotheses posit that abnormal misfolding and accumulation of amyloid-β(Aβ)and tau protein is the central event causing the ***,that conclusion could be only partly true,and there is conflicting evidence about the role of both proteins in Ad,being able to precede and influence one *** researchers argue that these proteins are mere executors rather than primary causes of ***,there have been continuing refinements of both hypotheses,with alternative explanations proposed.Aβand tau proteins may be independently involved in specific neurotoxic pathways;yet there may be other crucial processes going on in early ***,accumulating evidence suggests that Aβand tau act synergistically,rather than additively in disease onset(Jeremic et al.,2021,2023a).

关键词： amyloid Alzheimer additive

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Remaking a connection:molecular players involved in post-injury synapse formation

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Neural Regeneration Research 2025年第6期20卷 1719-1720页

作者： diogo Tomé Ramiro d.Almeida iBimEd-Institute of Biomedicine Department of Medical SciencesUniversity of AveiroAveiroPortugal CNC-Center for Neuroscience and Cell Biology University of CoimbraCoimbraPortugal

Functional recovery from central nervous system(CNS)trauma depends not only on axon regeneration or compensatory sprouting of uninjured fibers but also on the ability of newly grown axons to establish functional synapses with appropriate *** several studies have successfully promoted long-distance axonal regeneration in distinct CNS injury models,none of them have resulted in a viable therapeutic approach for patient recovery.A possible reason may be the lack of new synaptogenesis for reestablishing the circuitry lost after ***,we discuss how our understanding of the mechanisms that instruct synapse formation in the injured nervous system may contribute to the design of new strategies to promote functional restoration in traumatic CNS disorders.

关键词： viable injury instru

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Comparative study of mo2Ga2C with superconducting mAX phase mo2GaC： First-principles calculations

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Chinese Physics B 2017年第3期26卷 297-302页

作者： m A Ali m R Khatun NJahan m m hossain department of Physics Chittagong University of Engineering and Technology Chittagong 4349 Bangladesh department of Physics University of Rajshahi Rajshahi 6205 Bangladesh

The structural, electronic, optical and thermodynamic properties of mo2Ga2C are investigated using density func- tional theory （dFT） within the generalized gradient approximation （GGA）. The optimized crystal structure is obtained and the lattice parameters are compared with available experimental data. The electronic density of states （dOS） is calculated and analyzed. The metallic behavior for the compound is confirmed and the value of dOS at Fermi level is 4.2 states per unit cell per eV. Technologically important optical parameters （e.g., dielectric function, refractive index, absorption coefficient, photo conductivity, reflectivity, and loss function） are calculated for the first time. The study of dielectric constant （ε1） indicates the drude-like behavior. The absorption and conductivity spectra suggest that the compound is metallic. The reflectance spectrum shows that this compound has the potential to be used as a solar reflector. The thermodynamic properties such as the temperature and pressure dependent bulk modulus, debye temperature, specific heats, and thermal expansion coefficient of mo2Ga2C mAX phase are derived from the quasi-harmonic debye model with phononic effect also for the first time. Analysis of Tc expression using available parameter values （dOS, debye temperature, atomic mass, etc.） suggests that the compound is less likely to be superconductor.

关键词： first-principles calculations density of states (dOS) optical properties thermodynamic properties

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Insights into the physical properties and anisotropic nature of ErPdBi with an appearance of low minimum thermal conductivity

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Chinese Physics B 2021年第1期30卷 398-406页

作者： S K mitro R majumder K m hossain md Zahid Hasan md Emran hossain m A Hadi Bangamata Sheikh Fojilatunnesa mujib Science and Technology University Jamalpur-2012Bangladesh Physics discipline Khulna UniversityKhulna-9208Bangladesh department of materials Science and Engineering University of RajshahiRajshahi-6205Bangladesh department of Electrical and Electronic Engineering International Islamic University ChittagongKumiraChittagong-4318Bangladesh department of Physics University of RajshahiRajshahi6205Bangladesh

We theoretically study the structural, elastic and optical properties of Er Pd Bi together with its anisotropic behaviors using density functional theory. It is observed that Er Pd Bi satisfies the Born stability criteria nicely and possesses high quality of machinability. The anisotropic behavior of Er Pd Bi is reported with the help of theoretical anisotropy indices incorporating 3 d graphical presentation, which suggests that Er Pd Bi is highly anisotropic in nature. It is noticed that the minimum thermal conductivity is very low for Er Pd Bi compared to the several species. This low value of minimum thermal conductivity introduces the potentiality of Er Pd Bi in high-temperature applications such as thermal barrier *** addition, deep optical insights of Er Pd Bi reveal that our material can be used in different optoelectronic and electronic device applications ranging from organic light-emitting diodes, solar panel efficiency, waveguides etc. to integration of integrated circuits. Therefore, we believe that our results will provide a new insight into high-temperature applications and will benefit for the development of promising optoelectric devices as well.

关键词： Er Pd Bi minimum thermal conductivity anisotropy density functional theory(dFT)

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Non-Newtonian effect on natural convection flow over cylinder of elliptic cross section

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Applied mathematics and mechanics(English Edition) 2020年第2期41卷 361-382页

作者： P.NAG m.m.mOLLA m.A.hossain department of mathematics and Physics North South UniversityDhaka 1229Bangladesh Center for Applied Scientific Computing(CASC) North South UniversityDhaka 1229Bangladesh department of mathematics University of DhakaDhaka 1000Bangladesh

The non-Newtonian effect in the boundary layer flow over a horizontal elliptical cylinder is investigated numerically. A modified power-law viscosity model is used to correlate the non-Newtonian characteristics of the fluid flow. For natural convectionflows, the surface of the cylinder is maintained by the uniform surface temperature(UST)or the uniform heat flux(UHF) condition. The governing equations corresponding to theflow are first transformed into a dimensionless non-similar form using suitable transformations. The resulting equations are solved numerically by an efficient finite difference scheme. The numerical results are presented for the skin friction coefficient and the local Nusselt number with the eccentric angle for different values of the power-law index n. The local skin friction coefficient and the local Nusselt number are found to be higher and lower, respectively, for the shear thickening fluids(n > 1) than the other fluids(n≤1).The effects of different elliptical configurations on the average Nusselt number are also presented and discussed for both conditions of the surface temperature.

关键词： non-Newtonian fluid free convection boundary layer elliptical cylinder

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distributed dC-Bus Signaling Control of Photovoltaic Systems in Islanded dC microgrid

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1741-1750页

作者： Noushin Poursafar m.J.hossain Seyedfoad Taghizadeh macquarie University SydneyNew South WalesAustralia

The stability of an islanded dC microgrid(dCmG)is highly dependent on the presence and performance of the backup energy storage system(BESS),due to the lack of main grid *** condition makes the dCmG vulnerable to the critical situation of absence of the BESS,which could be caused by a fault or being fully charged or *** paper presents an enhanced distributed dC-bus signaling control strategy for converters of photovoltaic systems(PVs)to make the islanded dCmG less dependent on the *** a conventional control approach that utilizes PVs to operate in maximum power point tracking(mPPT)mode and the BESS solely regulating dC-bus voltage,the proposed control method maintains dC-bus voltage via intelligently managing output powers of the *** proposed control method continuously monitors dC-bus voltage and regulates the output powers of all the PVs via switching between mPPT mode and voltage regulating ***,if the dC-bus voltage level is less than a predefined maximum level,the PVs work in mPPT mode;otherwise,the PVs work in voltage regulating mode to maintain dC-bus voltage at an acceptable *** switching between mPPT and voltage regulating control operations results in protecting the dCmG from unavoidable shutdowns conventionally necessary during the absence of the BESS ***,the proposed control method reduces oscillations on the dC-bus voltage during existence of the *** performance and effectiveness of the proposed control strategy are validated through different case studies in mATLAB/Simulink.

关键词： dC microgrid voltage stability islanding mode distributed control distributed generator(dG)

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magnetic, dielectric and Complex Impedance Properties of xBa_(0.95)Sr_(0.05)TiO_3–(1-x)BiFe_(0.9)Gd_(0.1)O_3multiferroic Ceramics

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Acta metallurgica Sinica(English Letters) 2016年第6期29卷 505-517页

作者： m.J.miah A.K.m.Akther hossain department of Physics Bangladesh University of Engineering and Technology department of Physics Comilla University

xBa_（0.95）Sr_（0.05）TiO_3–（1-x）BiFe_（0.9）Gd_（0.1）O_3[x BST–（1-x）BFGO]（x = 0.00, 0.10, 0.20 and 0.25） multiferroic ceramics were prepared by the standard solid-state reaction technique. Structural characterization was performed by X-ray diffraction. All the samples showed rhombohedral distorted perovskite structure. Surface morphology of the ceramics was studied by the field emission scanning electron microscope（FESEm）. From the FESEm observation, the grain size was observed to be decreased with increasing BST content. Enhanced magnetic properties were observed in BFGO with the increase in BST content because of large lattice distortion. The complex initial permeability increased with the increasing of BST content. The study of dielectric properties showed that the dielectric constant increased, whereas dielectric loss decreased with increasing of BST content due to the reduction of oxygen vacancies. An analysis of the electric impedance and modulus with frequency was performed at different temperatures. Non-debye-type relaxation processes occur in the compound which was confirmed from the nature of the Cole–Cole plot. The dC conductivity was found to increase with the rise in temperature which indicates the semiconducting behavior of the compound with characteristics of the negative temperature coefficient of resistance. The activation energy, responsible for the relaxation determined from the modulus spectra（0.246 eV）, was found to be almost same as the value obtained from the impedance study（0.240 eV）, indicating that charge carriers overcome the same energy barrier during relaxation. The frequency response of imaginary parts of electric impedance and modulus suggested that the relaxation in xB ST–（1-x）BFGO ceramics follows the same mechanism at various temperatures.

关键词： magnetic properties dielectric properties Impedance spectroscopy Activation energy

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dispersion Relations for Isothermal Plasma around the Horizon of Reissner-Nordstroem-de Sitter Black Hole

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Chinese Physics Letters 2009年第10期26卷 220-223页

作者： m. Khayrul Hasan m. hossain Ali department of mathematics Shahjalal University of Science and Technology Sylhet-3100 Bangladesh department of Applied mathematics University of Rajshahi Rajshahi-6205 Bangladesh

We formulate the general relativistic magnetohydrodynamic equations for isothermal plasma in spatially fiat Reissner-Nordstroem-de Sitter metric by using 3＋1 split of spacetime. Respective perturbed equations are linearized for rotating magnetized surroundings. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed both analytically and numerically in order to investigate the nature of waves with positive angular frequency around the horizon.

关键词： No English Keyword

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Conduction-radiation effect on transient natural convection with thermophoresis

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Applied mathematics and mechanics(English Edition) 2012年第3期33卷 271-288页

作者： S.m.mAHFOOZ m.A.hossain department of mathematics COMSATS Institute of Information TechnologyPark RoadChak ShahzadIslamabad 44000Pakistan

This paper discusses the effect of thermophoretic particle deposition on the transient natural convection laminar flow along a vertical fiat surface, which is immersed in an optically dense gray fluid in the presence of thermal radiation. In the analysis, the radiative heat flux term is expressed by adopting the Rosseland diffusion approximation. The governing equations are reduced to a set of parabolic partial differential equations. Then, these equations are solved numerically with a finite-difference scheme in the entire time regime. The asymptotic solutions are also obtained for sufficiently small and large time. The obtained asymptotic solutions are then compared with the numerical solutions, and they are found in excellent agreement. moreover, the effects of different physical pa- rameters, i.e., the thermal radiation parameter, the surface temperature parameter, and the thermophoretic parameter, on the transient surface shear stress, the rate of surface heat transfer, and the rate of species concentration, as well as the transient velocity, temperature, and concentration profiles are shown graphically for a fluid （i.e., air） with the Prandtl number of 0.7 at 20℃ and 1.013 × 10^5 Pa.

关键词： radiation optically dense fluid transient natural convection thermophorestic particle deposition

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