Dynamics of the Cluster of Vortex Points in Two-Dimensional Superfluid 4He

We have simulated the dynamics of cluster of quantized vortex points with the same circulation in two-dimensional superfluid ⁴He. In two-dimensional quantum turbulence, vortices are always distributed uniformly, but often form some clusters. We study the dynamics of a cluster at zero temperature and finite temperatures. At zero temperature the cluster rotates. The radius and the density of the cluster hardly change because of the conservation of the energy and the angular momentum. On the other hand, at finite temperatures, the cluster rotates with forming a lattice structure and expanding because of the mutual friction.     

Chemical Glycosylation by Single Electron Transfer

Oligosaccharides play important roles in nature; however, chemical synthesis of oligosaccharides is still difficult and not carried out in a fully automated manner. Among various methods, the activation of glycosyl donors by single electron transfer using electrochemical and photochemical methods has several benefits. In particular, electrochemical oxidation is a powerful method to activate glycosyl donors, including thioglycosides, which are one of the most popular class of glycosyl donors in modern chemical glycosylations. This review article covers the pioneering works of electrochemical glycosylations, other chemical glycosylations achieved by single electron transfer, and our recent approach to the automated solution-phase synthesis of oligosaccharides based on the electrochemical method.     

Hill Plot Focusing on Ce Compounds with High Magnetic Ordering Temperatures and Consequent Study of Ce<Subscript>2</Subscript>AuP<Subscript>3</Subscript>

The Hill plot is a well-known criterion of the f-electron element interatomic threshold distance separating the nonmagnetic state from the magnetic state in actinides and lanthanides. We have reinvestigated the Hill plot of Ce compounds using the commercial crystallographic database CRYSTMET, focusing on a relationship between the Ce-Ce distance and the magnetic ordering temperature because a Ce compound with no other magnetic elements rarely has a magnetic ordering temperature that is higher than 20 K. The Hill plot of approximately 730 compounds has revealed that a Ce compound, particularly a ferromagnet, showing a high magnetic ordering temperature would require a short Ce-Ce distance with a suppression of the valence instability of the Ce ion. From the study, we developed interest in Ce₂AuP₃ with a Curie temperature of 31 K. The ferromagnetic nature of this material has been examined in terms of a doping effect, which suggests a possible increase in magnetic anisotropy energy.     

Performance Evaluation of Magnetostrictive Small Wind Turbines Using Fe–Co Alloy–Based Clad Sheets

In this study, the Fe–Co alloy is combined with cobalt ferrite (CoFe₂O₄) and nickel (Ni) to form Fe–Co/CoFe₂O₄ and Fe–Co/Ni clad sheets and their energy-harvesting performance is evaluated. The Fe–Co/CoFe₂O₄ clad sheet exhibits an output voltage of 4.229 mV and an output power of 6.89 nW at a wind speed of 10 m s⁻¹. The energy-harvesting performance of both these clad sheets cannot be quantitatively compared owing to their different thicknesses, which result in varying volume and distance from the neutral plane. Nevertheless, the values of output voltage and power for Fe–Co/CoFe₂O₄ are higher than those for Fe–Co/Ni (2.107 mV and 0.294 nW).     

Synthesis of Short Peptides with Perfluoroalkyl Side Chains and Evaluation of Their Cellular Uptake Efficiency

With an increasing demand for macromolecular biotherapeutics, the issue of their poor cell-penetrating abilities requires viable and relevant solutions. Herein, we report tripeptides bearing an amino acid with a perfluoroalkyl (R_F) group adjacent to the α-carbon. R_F-containing tripeptides were synthesized and evaluated for their ability to transport a conjugated hydrophilic dye (Alexa Fluor 647) into the cells. R_F-containing tripeptides with the fluorophore showed high cellular uptake efficiency and none of them were cytotoxic. Interestingly, we demonstrated that the absolute configuration of perfluoroalkylated amino acids (R_F-AAs) affects not only nanoparticle formation but also the cell permeability of the tripeptides. These novel R_F-containing tripeptides are potentially useful as short and noncationic cell-penetrating peptides (CPPs).