Electrochemically grown copper nanoclusters (CuNCs: < 3 nm) from single‐atom catalysts have recently attracted intensive attention as electrocatalysts for CO2 and CO reduction reaction (CO2RR/CORR) because they exhibit distinct product selectivity compared with conventional Cu nanoparticles (typically larger than 10 nm). Herein, we conducted a detailed investigation into the size dependence of CuNCs on selectivity for multicarbon (C2+) production in CORR. These nanoclusters were electrochemically grown from single Cu atoms dispersed on covalent triazine frameworks (Cu‐CTFs). Operando X‐ray absorption fine structure analysis revealed that Cu‐CTFs containing 1.21 wt% and 0.41 wt% Cu (Cu(h)‐CTFs and Cu(l)‐CTFs, respectively) formed CuNCs of 2.0 and 1.1 nm, respectively, at −1.0 V vs. RHE. The selectivity for CORR products was particularly dependent on the size of CuNCs, with the Faraday efficiencies of C2+ products being 52.3% and 32.7% at −1.0 V vs. RHE with Cu(h)‐CTFs and Cu(l)‐CTFs, respectively. Spherical CuNCs modeling revealed that larger cluster sizes led to a greater proportion of a surface coordination number (SCN) of 8 or 9. Density functional calculations revealed that the CO dimerization reaction was more likely to proceed at SCNs of 8 or 9 compared to SCN of 7 because of the stability of the *OCCO intermediate.
The potential of cyclodextrin derivatives to regulate the nasal absorption of morphine was examined in the rat, anticipating the optimized delivery of the opioid into the central nervous system.
The extent of systemic availability of morphine after the nasal administration of morphine hydrochloride in solution was much greater than that when the opioid was given orally in solution or rectally in a suppository, and was about 60% of that obtained after intravenous administration. Furthermore, higher levels of morphine in the cerebrospinal fluid were attained after nasal administration compared with the oral and rectal routes. Heptakis(2,6-di-O-methyl)-β-cyclodextrin significantly enhanced the rate of nasal absorption of morphine by facilitating the nasal epithelial permeability and consequently increasing the entry of the opioid into the cerebrospinal fluid. In contrast, 2-hydroxypropyl-γ-cyclodextrin sustained the plasma levels of morphine, probably through the formation of a complex that was less permeable through membranes.
The present results suggest that morphine is almost completely absorbed through the nasal epithelium with minimal first-pass metabolism and a proper use of the cyclodextrin derivatives is effective in controlling the nasal absorption of morphine and its entry into the central nervous system.
Abstracts Cannibalism is induced in larval‐stage populations of the Hokkaido salamander, Hynobius retardatus , under the control of a cannibalism reaction norm. Here, I examined phenotypic expression under the cannibalism reaction norm, and how the induction of a cannibalistic morph under the norm leads to populational morphological diversification. I conducted a set of experiments in which density was manipulated to be either low or high. In the high‐density treatment, the populations become dimorphic with some individuals developing into the cannibal morph type. I performed an exploratory analysis based on geometric morphometrics and showed that shape characteristics differed between not only cannibal and noncannibal morph types in the high‐density treatment but also between those morph types and the solitary morph type in the low‐density treatment. Size and shape of cannibal and noncannibal individuals were found to be located at either end of a continuum of expression following a unique size–shape integration rule that was different from the rule governing the size and shape variations of the solitary morph type. This result implies that the high‐density‐driven inducible morphology of an individual is governed by a common integration rule during the development of dimorphism under the control of the cannibalism reaction norm. Phenotypic expression under the cannibalism reaction norm is driven not only by population density but also by social interactions among the members of a population: variation in the populational expression of dimorphism is associated with contingent social interaction events among population members. The induced cannibalistic morph thus reflects not only by contest‐type exploitative competition but also interference competition.
