Structures and CO-adsorption reactivities of nickel oxide cluster cations were investigated by ion mobility mass spectrometry. The series of Ni n O n−2 + , Ni n O n−1 + and Ni n O n + cluster cations were predominantly observed in a mass spectrum at high ion-injection energy into an ion-drift cell. From the arrival time distributions of Ni n O n + and Ni n O n−1 + in the ion mobility spectrometry, structural transition from two-dimensional (2D) ring to three-dimensional (3D) compact structures was found at n = 5. In addition, 2D and 3D structural isomers were found to coexist for Ni 5 O 5 + , Ni 6 O 5 + and Ni 7 O 6 + . By adding CO gas to buffer gas in the ion-drift cell, Ni 4 O 3 + and Ni 5 O 4 + cluster cations were found to be more reactive for the CO adsorption reactions than Ni 4 O 4 + and Ni 5 O 5 +. Under the pseudo-first-order approximation, rate constants for CO-adsorption were determined to be (8.4 ± 0.7) × 10 −11 cm 3 molecule −1 s −1 for Ni 4 O 3 + and (9.6 ± 0.8) × 10 −11 cm 3 molecule −1 s −1 for Ni 5 O 4 + . These rate constants are 2 orders of magnitude faster than those for Ni 4 O 4 + and Ni 5 O 5 + , which have reported previously. These differences of rate constants can be originated in the structures of the nickel oxide cluster ions.
Severe immunodeficient mice are widely used to examine human and animal cells behaviour in vivo. However, mice are short-lived and small in size; while large animals require specific large-scale equipment. Rabbits are also commonly employed as experimental models and are larger than mice or rats, easy to handle, and suitable for long-term observational and pre-clinical studies. Herein, we sought to develop and maintain stable strains of rabbits with X-linked severe combined immunodeficiency (X-SCID) via the CRISPR/Cas9 system targeting Il2rg. Consequently, X-SCID rabbits presented immunodeficient phenotypes including the loss of T and B cells and hypoplasia of the thymus. Further, these rabbits exhibited a higher success rate with engraftments upon allogeneic transplantation of skin tissue than did wild type controls. X-SCID rabbits could be stably maintained for a minimum of four generations. These results indicate that X-SCID rabbits are effective animals for use in a non-rodent model of severe immunodeficiency.
Structural assignments of gas-phase magnesium oxide cluster cations, Mg n O n + (n ≤ 24), have been achieved from a comparison of experimental collision cross sections (CCSs) measured using ion mobility mass spectrometry and theoretical CCSs calculated for equilibrium structures optimized by quantum chemical calculations. Various structures based on rock-salt and hexagonal-tube structures were assigned for n = 5−13 and 15. On the other hand, only rock-salt type structures were assigned for n = 4, 14, 16−21, and 24. The CCS values and the total energies were close for the hexagonal-tube and rock-salt structures of a given size in the small size range (n ≤ 15 except for 4 and 14). The hexagonal-tube structures of the cluster ions with n ≥ 16 were less stable and had larger CCSs than the rock-salt structures. These results indicate that the structures of the Mg n O n + clusters were changed from mixtures of rock-salt and hexagonal-tube structures to pure rock-salt structures with the growth of the cluster size. All atoms in the hexagonal-tube structures are located on the surface of the clusters, even if the cluster size increases. In contrast, the assigned rock-salt structures with n = 13, 14, and n ≥ 17 had atoms inside the clusters, which means that the average coordination numbers are substantially higher for the rock-salt structures than for the hexagonal tube structures. The structural change from the mixed structures to pure rock-salt with an increase in size n can be attributed to this difference in the coordination number.
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