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Shape-memory alloys, such as Ni-Ti and Cu-Zn-Al, show a large reversible strain of more than several percent due to superelasticity. In particular, the Ni-Ti-based alloy, which exhibits some ductility and excellent superelastic strain, is the only superelastic material available for practical applications at present. We herein describe a ferrous polycrystalline, high-strength, shape-memory alloy exhibiting a superelastic strain of more than 13%, with a tensile strength above 1 gigapascal, which is almost twice the maximum superelastic strain obtained in the Ni-Ti alloys. Furthermore, this ferrous alloy has a very large damping capacity and exhibits a large reversible change in magnetization during loading and unloading. This ferrous shape-memory alloy has great potential as a high-damping and sensor material.

In superelastic alloys, large deformation can revert to a memorized shape after removing the stress. However, the stress increases with increasing temperature, which limits the practical use over a wide temperature range. Polycrystalline Fe-Mn-Al-Ni shape memory alloys show a small temperature dependence of the superelastic stress because of a small transformation entropy change brought about by a magnetic contribution to the Gibbs energies. For one alloy composition, the superelastic stress varies by 0.53 megapascal/°C over a temperature range from −196 to 240°C.

We have identified cobalt-base superalloys showing a high-temperature strength greater than those of conventional nickel-base superalloys. The cobalt-base alloys are strengthened by a ternary compound with the L1₂ structure, [Formula: see text] Co₃(Al,W), which precipitates in the disordered [gamma] face-centered cubic cobalt matrix with high coherency and with high melting points. We also identified a ternary compound, [Formula: see text] Ir₃(Al,W), with the L1₂ structure, which suggests that the Co-Ir-Al-W-base systems with [Formula: see text] (Co,Ir)₃(Al,W) structures offer great promise as candidates for next-generation high-temperature materials.

Rheotaxis and migration of cells in a flow field have been investigated intensively owing to their importance in biology, physiology and engineering. In this study, first, we report our experiments showing that the microalgae Chlamydomonas can orient against the channel flow and migrate to the channel centre. Second, by performing boundary element simulations, we demonstrate that the mechanism of the observed rheotaxis and migration has a physical origin. Last, using a simple analytical model, we reveal the novel physical mechanisms of rheotaxis and migration, specifically the interplay between cyclic body deformation and cyclic swimming velocity in the channel flow. The discovered mechanism can be as important as phototaxis and gravitaxis, and likely plays a role in the movement of other natural microswimmers and artificial microrobots with non-reciprocal body deformation.

Cilia-driven nodal flow is important in the determination of left-right asymmetry in the body. Several theoretical and computational models have been proposed to explain the mechanics of ciliary motion, although the full mechanism remains unknown. Here, we developed a three-dimensional nodal cilia axoneme model using a finite element-boundary element coupling method, and investigated the mechanics of nodal ciliary motion. We found that the rotational orbit was strongly dependent on the dynein activation frequency. We also investigated flow field generated by the ciliary rotation, and the flow strength decayed as r-3 at the far field from the cilium. Our numerical results also suggest that experimentally observed tilt angle θ=2π/9 is sufficiently large to make a leftward flow. These findings are helpful in better understanding ciliary motion and nodal flow.

Eph receptor tyrosine kinases and their ephrin ligands have been implicated in neuronal development and neovascularization. Overexpression of ephrin-A1 has been implicated in tumor progression and poor prognosis. However, the mechanisms are not clear. Here, we report a role of the Eph/ephrin system in a cell adhesion mechanism. Clustered erythropoietin-producing hepatocellular receptor A1 (EphA1)/ephrin-A1 complexes on the plasma membrane did not undergo endocytosis, and the cell remained adherent to one another. The cell–cell contacts were maintained in an Eph tyrosine kinase activity-independent manner even in the absence of E-cadherin. EphA1 and ephrin-A1 co-localized in pulmonary endothelial cells, and regulated vascular permeability and metastasis in the lungs. We identified ADAM12 (A disintegrin and metalloproteinase 12) as an EphA1-binding partner by yeast two-hybrid screening and found that ADAM12 enhanced ephrin-A1 cleavage in response to transforming growth factor-β1 in primary tumors. Released soluble ephrin-A1 in the serum deteriorated the EphA1/ephrin-A1-mediated cell adhesion in the lungs in an endocrine manner, causing lung hyperpermeability that facilitated tumor cell entry into the lungs. Depletion of soluble ephrin-A1 by its neutralizing antibody significantly inhibited lung metastasis.

Polycrystalline Cu-Al-Mn shape memory alloys (SMAs) with a low degree of order of the β (L2 1 ) phase show excellent ductility and exhibit shape memory (SM) properties such as superelasticity, the one way memory effect and the two way memory effect based on martensitic transformation. These SM properties can be greatly enhanced by controlling microstructural factors such as grain size and texture by thermomechanical treatments. In the present paper, the SM properties of ductile Cu-Al-Mn based SMAs and microstructure control to obtain excellent SM characteristics are reviewed. Furthermore, an example of the application of Cu-Al-Mn based SMAs to a guidewire for medical use is also presented.

The diffusion of red blood cells (RBCs) in blood is important to the physiology and pathology of the cardiovascular system. In this study, we investigate flow-induced diffusion of RBCs in a semi-dilute system by calculating the pairwise interactions between RBCs in simple shear flow. A capsule with a hyperelastic membrane was used to model an RBC. Its deformation was resolved using the finite element method, whereas fluid motion inside and outside the RBC was solved using the boundary element method. The results show that shear-induced RBC diffusion is significantly anisotropic, i.e. the velocity gradient direction component is larger than the vorticity direction. We also found that the motion of RBCs during the interaction is strongly dependent on the viscosity ratio of the internal to external fluid, and the diffusivity decreases monotonically as the viscosity ratio increases. The scaling argument also suggests that the diffusivity is proportional to the shear rate and haematocrit, if the suspension is in a semi-dilute environment and the capillary number is invariant. These fundamental findings are useful to understand transport phenomena in blood flow.

In the electron driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 4 mini-trains with several gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. The beam loading is compensated by amplitude modulation on the input RF in the positron booster composed from L-band and S-band traveling wave RF cavity. In this article, we derive the exact solution for the compensation with the gaps. In addition, we evaluate the effect of the time constant (delay) of the input RF modulation due to klystron Q-value.

Phase equilibria including L 2 1 full- and C 1 b half-Heusler phases at 1373 K in the Ni-rich portion of the Ni-Ti-Sb system were determined by electron probe microanalysis, x-ray diffraction and differential scanning calorimetry. It was confirmed that both Heusler phases coexist at 1373 K, separated by C 1 b  +  L 2 1   two-phase region. The single-phase region of the C 1 b phase deviates slightly from the stoichiometric composition of NiTiSb to NiSb-rich direction. On the other hand, while existing in the vicinity of the stoichiometric composition of Ni 2 TiSb, the  L 2 1 phase is not stable at temperatures below about 1270 K, disappearing by an eutectoid reaction, L 2 1  →  C 1 b  + Ni 3 Ti- D 0 24 .