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magnetic properties of Sn-substituted Ni-Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe2O3, and SnO2

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Chinese Physics B 2017年第7期26卷 377-382页

作者： m A Ali m m Uddin m N i Khan F U Z Chowdhury S m Hoque S i Liba Department of Physics Chittagong University of Engineering and Technology (CUET) materials Science Division Atomic Energy Center

A series of Ni0.6-x/2Zn0.4-x/2SnxFe2O4(x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3)(NZSFO) ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction(XRD). The magnetic properties such as saturation magnetization(ms),remanent magnetization(mr), coercive field(Hc), and Bohr magneton(μ) are calculated from the hysteresis loops. The value of msis found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability(μ’) over a wide range of frequency. The decreasing trend of μ’ with increasing Sn content has been observed. Curie temperature TChas been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the NZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

关键词： magnetic properties saturation magnetization permeability Curie temperature

miNimUm CONGESTiON SPANNiNG TREES iN BiPARTiTE AND RANDOm GRAPHS

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Acta mathematica Scientia 2011年第2期31卷 634-640页

作者： m.i. Ostrovskii Department of mathematics and Computer Science St. John's University

The first problem considered in this article reads： is it possible to find upper estimates for the spanning tree congestion in bipartite graphs, which are better than those for general graphs？ it is proved that there exists a bipartite version of the known graph with spanning tree congestion of order n3/2, where n is the number of vertices. The second problem is to estimate spanning tree congestion of random graphs. it is proved that the standard model of random graphs cannot be used to find graphs whose spanning tree congestion has order greater than n3/2.

关键词： Bipartite graph random graph minimum congestion spanning tree

Collapse period of degrading SDOF systems

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 681-694页

作者： Borekci m Kircil mS Ekiz i Yildiz Technical University

Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. in this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.

关键词： collapse degradation dynamic instability hysteretic types,earthquake

Electron transport in electrically biased inverse parabolic double-barrier structure

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Chinese Physics B 2016年第5期25卷 326-332页

作者： m Bati S Sakiroglu i Sokmen Physics Department Faculty of Science Dokuz Eylül University Physics Department Graduate School of Natural and Applied Sciences Dokuz Eylül University Physics Department Faculty of Arts and Sciences Recep Tayyip Erdogan University

A theoretical study of resonant tunneling is carried out for an inverse parabolic double-barrier structure subjected to an external electric field. Tunneling transmission coefficient and density of states are analyzed by using the non-equilibrium Green＇s function approach based on the finite difference method. it is found that the resonant peak of the transmission coefficient, being unity for a symmetrical case, reduces under the applied electric field and depends strongly on the variation of the structure parameters.

关键词： inverse parabolic double-barrier structure resonant tunneling non-equilibrium Green's function electric field

Sleep as a window to understand and regulate Alzheimer's disease:emerging roles of thalamic reticular nucleus

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Neural Regeneration Research 2025年第6期20卷 1711-1712页

作者： Haoqi Sun Shiqian Shen Robert J.Thomas m.Brandon Westover Can Zhang Department of Neurology Beth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Center for Translational Pain Research Department of AnesthesiaCritical Care and Pain MedicineMassachusetis General HospitalHarvard Medical SchoolBostonMAUSA Division of Pulmonary Critical Care and Sleep MedicineDepartment of MedicineBeth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Genetics and Aging Research Unit McCance Center for Brain HealthMass General Institute for Neurodegenerative DiseaseDepartment of NeurologyMassachusetts General HospitalHarvard Medical SchoolBostonMAUSA

introduction:Alzheimer 's disease(AD) is a common neurodegenerative disorder and the primary cause of dementia. Considerable evidence supports the “amyloid hypothesis,” stating that the pathogenesis of AD is primarily caused by the deposition of amyloid-β(Aβ), which drives tau phosphorylation, neuroinflammation, and neurodegeneration in the brain. The amyloid hypothesis is strengthened by the significant and moderate benefit of lecanemab, a humanized antibody through an anti-amyloid mechanism,showing slowed clinical decline(van Dyck et al.,2023). The recent positive results of anti-amyloid trials have brought back focus on the amyloid hypothesis through biochemical, genetic, and pharmacological approaches(Zhang, 2023).

关键词： Alzheimer inflammation hypothesis

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

Experimental nuclear charge density and theoretical description of theabove-barrier light heavy-ion fusion process

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Chinese Physics C 2023年第8期47卷 64-74页

作者： i.i.Gontchar m.V.Chushnyakova Physics and Chemistry Department Omsk State Transport UniversityOmskRussia Physics Department Omsk State Technical UniversityOmskRussia

Theoretical modeling of nucleus-nucleus collisions is often based on the nucleus-nucleus *** of the advanced methods for constructing this potential is the semi-microscopical double-folding model with m3 YParis *** and neutron densities are significant components of this *** correct nucleon density(ND) must reproduce the experimental nuclear charge density(NCD).However,those who deal with modeling the fusion process typically disregard this *** aim to achieve a good description of both the nuclear charge density and above-barrier fusion cross sections of even-even light nuclei with Z=*** consider several versions of NDs available in literature and construct our own approximation for the ND of the even-even spherical nuclei^(12)C,^(16)O,and^(40)Ca,abbreviated as FE-density(Fermi+exponential).We carefully compare the NCDs resulting from different versions of NDs with the experimental *** finding the nucleus-nucleus potential using the double-folding model with the density dependent m3 Y-Paris NN-forces and FE densities,we evaluate the abovebarrier fusion cross sections for five reactions,^(12)C+^(12)C,^(12)C+^(16)O,^(16)O+^(16)O,^(16)O+^(40)Ca,and^(40)Ca+^(40)Ca,and40Ca+40Ca,for which experimental data are *** cross sections are calculated using two approaches:a) the barrier penetration model and b) the trajectory model with surface friction(Tm).To find the transmission coefficients for the Tm,the Langevin equations are *** all considered reactions,our Tm typically reproduces the above-barrier experimental cross sections within 10-15%.The only adjustable parameter of the model,the optimal friction strength KRm,is found to be approximately 90 zs·GeV-1for the light reactions12C+12C,12C+16O,and16O+16O and approximately 15zs·GeV-1for the heavy reactions16O+40Ca and40Ca+*** latter findings are in reasonable agreement with the systematics found ***,the FE-recipe allows highly accurate and s

关键词： nuclear charge densities nucleon densities heavy-ion fusion surface friction double-fold-ing model

Thomson effect with hyperbolic two-temperature on magneto-thermo-visco-elasticity

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Applied mathematics and mechanics(English Edition) 2021年第9期42卷 1311-1326页

作者： A.m.ALHARBi m.i.A.OTHmAN H.m.ATEF Department of mathematics College of ScienceTaif UniveristyTaif 21944Saudi Arabia Department of mathematics Faculty of ScienceZagazig UniversityZagazig 44519Egypt Department of mathematics Faculty of ScienceDamanhur UniversityDamanhur 22511Egypt

The study considers a homogeneous isotropic thermo-visco-elastic solid with hyperbolic two-temperature to cope up with its two-dimensional(2 D)*** heat conduction equation is influenced by the Thomson ***-Shulman’s theory is used to modify the basic governing equations.A method called"normal mode analysis"is utilized to attain the magnetic field,stress,conductive and thermodynamic temperature,and displacement ***,a number of numerical calculations are performed and discussed to understand the impact of hyperbolic two-temperatures,Thomson parameter,and viscosity on the material mentioned above.

关键词： thermo-visco-elasticity magnetic field hyperbolic two-temperature Lord-Shulman’s theory Thomson coefficient normal mode analysis

Transportation of heat through Cattaneo-Christov heat flux model in non-Newtonian fluid subject to internal resistance of particles

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Applied mathematics and mechanics(English Edition) 2020年第8期41卷 1157-1166页

作者： m.i.KHAN F.ALZAHRANi Department of mathematics Riphah International UniversityFaisalabad 38000Pakistan Nonlinear Analysis and Applied mathematics(NAAm)-Research Group Department of MathematicsFaculty of SciencesKing Abdulaziz UniversityJeddah 21589Saudi Arabia

Thermal conduction which happens in all phases(liquid,solid,and gas)is the transportation of internal energy through minuscule collisions of particles and movement of electrons within a working *** colliding particles comprise electrons,molecules,and atoms,and transfer disorganized microscopic potential and kinetic energy,mutually known as the internal *** engineering sciences,heat transfer comprises the processes of convection,thermal radiation,and sometimes mass ***,more than one of these procedures may happen in a given *** use the Cattaneo-Christov(CC)heat flux model instead of the Fourier law of heat conduction to discuss the behavior of heat transportation.A mathematical model is presented for the Cattaneo-Christov double diffusion(CCDD)in the flow of a non-Newtonian nanofluid(the Jeffrey fluid)towards a stretched *** magnetohydrodynamic(mHD)fluid is *** behaviors of heat and mass transportation rates are discussed with the *** models are based on Fourier’s and Fick’s *** convective transportation in nanofluids is discussed,subject to thermophoresis and Brownian *** nonlinear governing flow expression is first altered into ordinary differential equations via appropriate transformations,and then numerical solutions are obtained through the built-in-shooting *** impact of sundry flow parameters is discussed on the velocity,the skin friction coefficient,the temperature,and the concentration *** is reported that the velocity of material particles decreases with higher values of the Deborah number and the ratio of the relaxation to retardation time *** temperature distribution enhances when the Brownian motion and thermophoresis parameters *** concentration shows contrasting impact versus the Lewis number and the Brownian motion *** is also noticed that the skin friction coefficient decreases when the ratio of the relaxation to retarda

关键词： Cattaneo-Christov double diffusion(CCDD) non-Newtonian fluid model(Jeffrey model) viscous dissipation magnetohydrodynamic(mHD) Brownian diffusion thermophoresis diffusion