•Ho-substituted nanocrystalline Nd-Fe-B alloys show a notable increase in coercivity.•Coercivity of Ho-substituted alloys is achieved an impressive 38% of its anisotropy field.•Coercivity mechanism ...of Nd-Fe-B alloys through Pr and Ho substitution is elucidated.•Ho exhibits a heightened propensity for incorporation into the RE2Fe14B grains.
Magnetocrystalline anisotropy field (HA) is an internal factor for determining the coercivity (Hc) of the magnetic materials. Despite a theoretical HA of 73 kOe, the melt-spun Nd-Fe-B alloy achieves only 20 % of this value for Hc. Comparing Ho2Fe14B and Pr2Fe14B compounds with an identical HA of 75 kOe, we reveal that Ho-substituted Nd-Fe-B alloys exhibit a more pronounced Hc enhancement than Pr-substituted alloys. The Hc value of (Nd1-xPrx)-Fe-B alloy increased from 16.9 kOe (x = 0) to 20.7 kOe of x = 1.0 alloy, achieving 28 % of its HA value. Notably, the Ho-substituted alloys exhibited a significantly higher coercivity, reaching 28.0 kOe at x = 1.0 and establishing an impressive 38 % ratio to its HA. The coercivity of Ho-substituted alloys is controlled by both nucleation and pinning, whereas the Pr-substituted alloys follow a nucleation-type mechanism. Microstructure characterization shows Ho substitution has a positive effect on grain refinement. Furthermore, Ho tends to concentrate in the RE2Fe14B grains, leading to an increased HA of the main phase and a substantial rise in Hc.
The transmission eigenvalue problem arising from the inverse scattering theory is of great importance in the theory of qualitative methods and in the practical applications. In this paper, we study ...the FEM for the transmission eigenvalue problem for anisotropic inhomogeneous media in Ω⊂Rd(d=2,3). Using the T-coercivity and the spectral approximation theory, we derive an a posteriori estimator of residual type and prove its effectiveness and reliability for eigenfunctions. In addition, we also prove the reliability of the estimator for transmission eigenvalues. The numerical experiments indicate our method is efficient and can reach the optimal order DoF−2m/d by using piecewise polynomials of degree m for real and complex eigenvalues.
We demonstrate that the simultaneous substitution of calcium and aluminum for strontium and iron in strontium hexaferrite results in a significant increase of coercivity up to a record high of 21.3 ...kOe. We propose that the effect is originated from a crystal structure distortion causing an increase of the magnetocrystalline anisotropy.
Embryo Implantation: War in Times of Love Ashary, Nancy; Tiwari, Abhishek; Modi, Deepak
Endocrinology (Philadelphia),
02/2018, Volume:
159, Issue:
2
Journal Article
Peer reviewed
Abstract
Contrary to widespread belief, the implantation of an embryo for the initiation of pregnancy is like a battle, in that the embryo uses a variety of coercive tactics to force its acceptance ...by the endometrium. We propose that embryo implantation involves a three-step process: (1) identification of a receptive endometrium; (2) superimposition of a blastocyst-derived signature onto the receptive endometrium before implantation; and finally (3) breaching by the embryo and trophoblast invasion, culminating in decidualization and placentation. We review here the story that is beginning to emerge, focusing primarily on the cells that are in “combat” during this process.
In the present review, we describe the mechanisms that are involved in implantation of the embryo to the uterus and initiation of pregnancy.
The rheological characteristics of manganese zinc (Mn-Zn) ferrite magnetic nanofluid synthesized using co-precipitation technique were examined in the absence and presence of magnetic fields. The ...research formulates required conditions needed for the formation of a gelly-like structure. The impact of magnetic field and temperature on the rheological properties of Mn-Zn ferrite ferrofluid is investigated. When a magnetic field was applied, higher magnetoviscoelasticity and magnetoviscosity were formed. Analysis was also done on other rheological parameters, such as the damping factor, which is crucial for regulating and restricting vibrations in a system. A stiff, gel-like structure is produced when a magnetic field is applied, and the gel-like quality grows as the magnetic field increases; when the magnetic field is removed, the gel-like and rigidity of the structure is lost. At low temperatures, the liquid phase is dominated by solid-like particles, whereas at high temperatures, the liquid-like structure is dominant. This study reveals the conditions required for the creation of high viscous effect and the viscoelastic behavior induced by the field offers important insights for optimizing the Mn-Zn ferrite ferrofluid for a range of applications. Other criterial for gel-like structure formation such as low torque and deflection angle of the ferrofluid were also established.
We consider a continuous coercive Hamiltonian H on the cotangent bundle of the compact connected manifold M which is convex in the momentum. If uλ:M→R is the viscosity solution of the discounted ...equation λuλ(x)+H(x,dxuλ)=c(H),where c(H) is the critical value, we prove that uλ converges uniformly, as λ→0, to a specific solution u0:M→R of the critical equation H(x,dxu)=c(H).We characterize u0 in terms of Peierls barrier and projected Mather measures. As a corollary, we infer that the ergodic approximation, as introduced by Lions, Papanicolaou and Varadhan in 1987 in their seminal paper on homogenization of Hamilton–Jacobi equations, selects a specific corrector in the limit.
It is shown that CuIn alloys can be effectively used as spacers in GMR multilayers. Attention is paid to the method of obtaining of the homogeneous CuIn alloys. Magnetron targets Cu1-xInx with an ...indium content х = 2–8.7 at% have been used for preparation of exchange-coupled multilayers of the composition glass/Ta(5)/Ni48Fe12Cr40(5)/Co90Fe10(1.3)/Cu1-xInx(2–2.2 nm)7/Ta(5). A decrease in GMR ratio was found with an increase in the content of indium in the alloy Cu1-xInx. For x < 4.7 at% a slight decrease in magnetoresistance is observed. The sharpest decrease in the GMR ratio from 23.3% to 3.2% is observed when the indium content changes in the range x = 4.7–8.7 at%. It is demonstrated that the coercivity of CoFe/Cu1-xInx multilayers decreases more than 5 times when the indium content increases in the range of х = 0–4.7 at. %. A correlation between the crystallite sizes in multilayers and the change of coercivity has been revealed. It is shown that the substitution in the multilayers studied of Co90Fe10 alloy by Co-rich ternary ferromagnetic alloys Co77Fe17Ni6 and Co70Fe20Ni10 made it possible to obtain CoFeNi/CuIn multilayers with GMR ratio of 25–29%, extremely low coercivity of several Oe, and high linearity of the field dependence of magnetoresistance. The combination of these characteristics is useful for practical applications.
•CuIn alloys can be effectively used as spacers in GMR multilayers.•Indium content in Cu1−xInx significantly affects the crystallite size of multilayers.•Correlation between crystallite size and coercivity has been found.•Extremely low coercivity of several Oe was obtained in CoFeNi/CuIn multilayers.•Multilayers with low coercivity and GMR ratio of 25–29% are useful for applications.
Fe, Fe-3wt%Si, and Fe-6.5 wt%Si alloys were subjected to high-pressure torsion (HPT) to achieve a nanostructure (<100 nm grain size). HPT processing was done at 77 and 293 K and heat treatments were ...performed on the deformed samples to reduce internal stresses that are known to deteriorate soft magnetic properties by impeding the movement of domain walls. X-ray line profile analysis (XLPA) was used to find out the crystallite/subgrain/domain size and the dislocation density in the deformed samples. The coercivity Hc was characterized on ring-shaped samples using a hysteresisgraph. Internal stresses in the deformed and heat-treated samples were determined using magnetic data and the dislocation density data and a comparison is made between the two approaches. HPT deformation increases the coercivity of the samples while heat treatment after deformation reduces the coercivity to a certain extent in Fe samples but has mixed results in Fe–Si alloys. In comparison with Herzer's theory, zero-frequency Hc was plotted against crystallite (or subgrain) size and it was found that coercivity follows a D1.5 relation, where D is crystallite size.
This paper deals with boundary value problems of the form −∑i=1nDi(ai(x,u(x),Du(x)))=f(x),x∈Ω,u(x)=0,x∈∂Ω. Assume that there exist c1,ν,θ>0 such that for almost all x∈Ω and all (s,z)∈R×Rn, ...|ai(x,s,z)|≤c11+|zi|pi−1,i=1,…,n, and ν∑i=1n|zi|pi(1+|s|)θ≤∑i=1nai(x,s,z)zi. We let f∈Lm(Ω) and we derive regularity results for weak solutions.
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