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As the sizes of noble metal catalysts, such as platinum, have been successfully minimized, fundamental insights into the electronic properties of metal sub-nanoclusters are increasingly sought for optimizing their catalytic performance. However, it is difficult to rationalize the catalytic activities of metal sub-nanoclusters owing to their more complex electronic structure compared with those of small molecules and bulky solids. In this study, the adsorption of molecular oxygen on a Pt13 sub-nanocluster supported on a graphene layer was analyzed using density functional theory. Unlike bulk Pt, the Pt13 sub-nanocluster has multiple adsorption sites, and the adsorption energy depends strongly on the type of adsorption site. The O2 adsorption energy does not correlate with the transferred charge between O2 and the Pt13 moiety; therefore, to elucidate the differences in the adsorption sites, we propose an original approach for analyzing the electronic structure change in metal sub-nanoclusters caused by molecular adsorption. Our analysis of the integrated local density of state (LDOS) revealed that O2 adsorption on the Pt13 sub-nanocluster has a distinct feature, different from that on a smaller Pt2 cluster or rather a larger Pt slab. The change in the electronic structure of the Pt13 moiety was primarily observed near the Fermi level, different from that of the Pt slab whose DOS was distributed over a wide energy range. Furthermore, the change in the integrated LDOS correlated well with the O2 adsorption energy on the Pt13 sub-nanocluster. [ABSTRACT FROM AUTHOR]

To complete microinjection as quickly as possible, we have developed Vibratory Microinjection Systems (VMSs) that vibrate a micropipette in its longitudinal direction and can significantly reduce the time needed for pronuclear microinjection compared to ordinary (non-vibratory) microinjection. The longest breakdown of the time is the time required to pierce the cell membrane and the pronuclear membrane simultaneously. Because cytoplasmic microinjection, which pierces the cell membrane alone, is far more difficult and time-consuming than pronuclear microinjection, we next aimed to develop a VMS capable of penetrating the cell membrane instantly. In this new and latest version, two types of ultrasonic-wave vibrators were developed: the first for commercially available micropipettes (Femtotip) and the second for self-made micropipettes. The two vibrators differ only in their airtight structure, where the micropipettes connect to their respective vibrators: a female screw plus O-ring for the first vibrator (VMS6_1) and a silicone-rubber tube for the second (VMS6_2). The tube-type joint used in VMS6_2 only slightly damped or amplified vibrations from the vibrator to the micropipette tip, propagating them much more accurately than the screw-type joint in VMS6_1. In addition, VMS6_2 significantly shortened the time taken to pierce the cell membrane of a fertilized egg: an average of 1.52 s (N = 410) vs. 3.62 s (N = 65) in VMS6_1. The VMS6_2 group achieved a piercing time of zero in 86.1% of the allocated eggs, while only 10.8% of the VMS6_1 group did. In each vibrator, we also compared vibratory microinjection (VM; N = 475) and ordinary microinjection (OM; N = 457), which uses injection pressure in place of vibration. None of the eggs in the OM group achieved the zero-second piercing time. Compared to the OM, the VM group showed a significantly shorter piercing time, 1.80 vs. 10.69 s on average, and a significantly better survival rate, 90.3 vs. 81.8% on average. VMS6_2 not only improved on the already demonstrated superiority of VM to OM but also enabled instantaneous piercing of the cell membrane. [ABSTRACT FROM AUTHOR]

Dirhodium complexes bearing bulky carboxylate ligands are synthesized and characterized. The steric bulk of carboxylate ligands could affect the reaction selectivity in Rh‐catalyzed intramolecular reactions: Rh catalysts with bulky carboxylate ligands provided five‐membered ring products preferentially via the insertion into a carbon–hydrogen bond. Meanwhile, six‐membered ring products were obtained using conventional Rh catalysts via the insertion of a carbon‐carbon double bond. [ABSTRACT FROM AUTHOR]