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C-type asteroids are the presumed home to carbonaceous chondrites, some of which contain abundant life-forming volatiles and organics. For the first time, samples from a C-type asteroid (162173 Ryugu) were successfully returned to Earth by JAXA’s Hayabusa2 mission. These pristine samples, uncontaminated by the terrestrial environment, allow a direct comparison with carbonaceous chondrites. This study reports the stable K isotopic compositions (expressed as δ41K) of Ryugu samples and seven carbonaceous chondrites to constrain the origin of K isotopic variations in the early Solar System. Three aliquots of Ryugu particles collected at two touchdown sites have identical δ41K values, averaged at -0.194 ± 0.038‰ (2SD). The K isotopic composition of Ryugu falls within the range of δ41K values measured on representative CI chondrites, and together, they define an average δ41K value of -0.185 ± 0.078‰ (2SE), which provides the current best estimate of the K isotopic composition of the bulk Solar System. Samples of CI chondrites with δ41K values that deviate from this range likely reflect terrestrial contaminations or compositional heterogeneities at sampled sizes. In addition to CI chondrites, substantial K isotopic variability is observed in other carbonaceous chondrites and within individual chondritic groups, with δ41K values inversely correlated with K abundances in many cases. These observations indicate widespread fluid activity occurred in chondrite parent bodies, which significantly altered the original K abundances and isotopic compositions of chondrules and matrices established at their accretion.

The world's largest sample of 1.31 billion $J/\psi$ events accumulated at the BESIII detector, provides a unique opportunity to investigate $\eta$ and $\eta^\prime$ physics via two body $J/\psi$ radiative or hadronic decays. For many $\eta^\prime$ decay channels the low background data samples are up to three orders of magnitude larger than collected in any previous experiment. Here we review the most significant results on $\eta$ and $\eta^\prime$ obtained at BESIII so far. The analyses range from detailed studies of the common decays dynamics, observations of new radiative and Dalitz decays, and search for rare/forbidden decays with sensitivity up to $\cal{B}\sim 10^{-5}$. Finally, prospects of the forthcoming runs at $J/\psi$ peak for the $\eta$ and $\eta^\prime$ physics are discussed., Comment: 17pages. 20 figures

Collagens are the most abundant proteins of the extracellular matrix, and the hierarchical folding and supramolecular assembly of collagens into banded fibers is essential for mediating cell-matrix interactions and tissue mechanics. Collagen extracted from animal tissues is a valuable commodity, but suffers from safety and purity issues, limiting its biomaterials applications. Synthetic collagen biomaterials could address these issues, but their construction requires molecular-level control of folding and supramolecular assembly into ordered banded fibers, comparable to those of natural collagens. Here, we show an innovative class of banded fiber-forming synthetic collagens that recapitulate the morphology and some biological properties of natural collagens. The synthetic collagens comprise a functional-driver module that is flanked by adhesive modules that effectively promote their supramolecular assembly. Multiscale simulations support a plausible molecular-level mechanism of supramolecular assembly, allowing precise design of banded fiber morphology. We also experimentally demonstrate that synthetic fibers stimulate osteoblast differentiation at levels comparable to natural collagen. This work thus deepens understanding of collagen biology and disease by providing a ready source of safe, functional biomaterials that bridge the current gap between the simplicity of peptide biophysical models and the complexity of in vivo animal systems.