Resonant x-ray magnetic scattering is used to study magnetic order near the (001) surface of the antiferromagnetic oxide ${\mathrm{UO}}_2$ for temperatures between 10 and 35 K. It is found that for temperatures below the bulk Néel temperature a magnetically disordered region exists at the surface, and is separated from the magnetically ordered bulk by a diffuse magnetic interface. The width of the magnetic interface is temperature dependent, and appears to diverge as the sample temperature approaches the bulk Néel temperature. In contrast to the bulk, which exhibits a discontinuous magnetic ordering transition, the surface layers order continuously. These results are shown to be qualitatively consistent with the theory of surface induced disorder.

Delivery across the cell membrane is of critical importance for the development of therapeutics targeting intracellular proteins. The use of cell-penetrating peptides (CPPs), such as Penetratin (P16), has facilitated the delivery of otherwise cell-impermeable molecules allowing them to carry out their biological function. A truncated form of Penetratin (RRMKWKK) has been previously described as the minimal Penetratin sequence that is required for translocation across the cell membrane. Here, we performed a detailed comparison of cellular uptake by Penetratin (P16) and the truncated Penetratin peptide (P7), including their ability to deliver G7-18NATE, a cyclic peptide targeting the cytosolic cancer target Grb7-adapter protein into cells. We identified that both P16 and P7 were internalized by cells to comparable levels; however, only P16 was effective in delivering G7-18NATE to produce a biological response. Live-cell imaging of fluorescein isothiocyanate-labeled peptides suggested that while P7 may be taken up into cells, it does not gain access to the cytosolic compartment. Thus, this study has identified that the P7 peptide is a poor CPP for the delivery of G7-18NATE and may also be insufficient for the intracellular delivery of other bioactive molecules.