In multicellular organisms, oocytes and sperm undergo fusion during fertilization and the resulting zygote gives rise to a new individual. The ability of zygotes to produce a fully formed individual from a single cell when placed in a supportive environment is known as totipotency. Given that totipotent cells are the source of all multicellular organisms, a better understanding of totipotency may have a wide-ranging impact on biology. The precise delineation of totipotent cells in mammals has remained elusive, however, although zygotes and single blastomeres of embryos at the two-cell stage have been thought to be the only totipotent cells in mice. We now show that a single blastomere of two- or four-cell mouse embryos can give rise to a fertile adult when placed in a uterus, even though blastomere isolation disturbs the transcriptome of derived embryos. Single blastomeres isolated from embryos at the eight-cell or morula stages and cultured in vitro manifested pronounced defects in the formation of epiblast and primitive endoderm by the inner cell mass and in the development of blastocysts, respectively. Our results thus indicate that totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage.
γ-Graphyne,
a type of carbon material, has become one of
the potential candidates for improving fuel cell catalysts, but its
large oxygen permeation barrier during the oxygen reduction process
hinders the improvement of electrocatalytic performance. In this work,
we used plasma fluorination to treat γ-graphyne and combined
it with gamma irradiation technology to synthesize F-doped γ-graphyne/PtPd
nanoparticle nanocomposite, realizing the first application of γ-graphyne
in the field of oxygen reduction catalysis. The as-prepared F-doped
γ-graphyne/PtPd catalyst exhibits overall good ORR performance,
especially reaching the level of graphdiyne in terms of peak potential,
half-wave potential, and current density. Under alkaline conditions,
it was comparable to commercial Pt/C and showed more rapid kinetics.
Taken together, we found that the high catalytic activity originates
from the structural changes that the12-membered ring structure is
opened, which is brought about by plasma fluorination treatment and
gamma irradiation, which facilitates the diffusion of O2 in the catalytic process, adsorption, and electron transfer of O2 on the surface of the catalyst. The treated γ-graphyne
can be a carbon substrate material with high potential in the field
of oxygen reduction catalysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.