Significantly high polarization degree of the very low-albedo asteroid (152679) 1998 KU2_\mathrm{2}

We present a unique and significant polarimetric result regarding the near-Earth asteroid (152679) 1998 KU$_\mathrm{2}$ , which has a very low geometric albedo. From our observations, we find that the linear polarization degrees of 1998 KU$_\mathrm{2}$ are 44.6 $\pm$ 0.5\% in the R$_\mathrm{C}$ band and 44.0 $\pm$ 0.6\% in the V band at a solar phase angle of 81.0\degr. These values are the highest of any known airless body in the solar system (i.e., high-polarization comets, asteroids, and planetary satellites) at similar phase angles. This polarimetric observation is not only the first for primitive asteroids at large phase angles, but also for low-albedo (< 0.1) airless bodies. Based on spectroscopic similarities and polarimetric measurements of materials that have been sorted by size in previous studies, we conjecture that 1998 KU$_\mathrm{2}$ has a highly microporous regolith structure comprising nano-sized carbon grains on the surface.Comment: 9 pages, 5 figures, and 3 tables, accepted for publication in A&

Dissimilar joining of alumina to aluminum at room temperature without applying a loading by two-step deposition

Low temperature joining is desirable for aluminum-ceramics joining because aluminum has a large coefficient of thermal expansion. In the present work, joining of Al₂O₃ to Al was performed at room temperature by the two-step deposition method including Ni electroless deposition and Cu electrodeposition. The joining strength was increased, and the fracture mode changed from a fracture at the Ni/Al₂O₃ interface to that in the Al₂O₃ substrate by using a porous Al₂O₃ or by etching a dense Al₂O₃ surface. Thus, the present work demonstrates that Al₂O₃ and Al are successfully joined at room temperature without applying a load by the deposition method

Large Cs adsorption capability of nanostructured Prussian Blue particles with high accessible surface areas

Very recently, we have reported preparation of several types of Prussian Blue (PB) particles with varying particle sizes by systematically tuning the synthetic conditions (Angew. Chem., Int. Ed., 2012, 51, 984-988). Here, the obtained PB particles are used for removal of Cs ions from aqueous solutions, which will be useful for remediation of nuclear waste. To evaluate the uptake ability of Cs ions into the PB particles, we utilize quartz crystal microbalance (QCM) for real-time monitoring of uptake behavior of Cs ions into the PB particles. The frequency of the QCM is promptly decreased after injection of Cs ions solution into the QCM cell. Hollow PB nanoparticles of 190 nm in diameter have very high surface area (338 m(2) g(-1)), in comparison with other PB particles, leading to efficient Cs adsorption capability eight times larger than that of the commercial PB particles. The diffusion in terms of dissociation constant (K-d), maximum amount of adsorbed Cs in PB particles (m(max)), and the adsorption kinetics (k) of Cs ions into the PB particles are also discussed. Due to the selective uptake for Cs ions based on K-d and k values, the PB particles can be proposed as good candidates in waste management consideration