Confined water inside carbon nanotubes (CNTs) has attracted a lot of attention in recent years, amassing as a result a very large number of dedicated studies, both theoretical and experimental. This exceptional scientific interest can be understood in terms of the exotic properties of nanoconfined water, as well as the vast array of possible applications of CNTs in a wide range of fields stretching from geology to medicine and biology. This review presents an overreaching narrative of the properties of water in CNTs, based mostly on results from systematic nuclear magnetic resonance (NMR) and molecular dynamics (MD) studies, which together allow the untangling and explanation of many seemingly contradictory results present in the literature. Further, we identify still-debatable issues and open problems, as well as avenues for future studies, both theoretical and experimental.

We report a comparison of the $1/T_1$ spin-lattice relaxation rates for ${}^9\mathrm{Li}$ and ${}^8\mathrm{Li}$ in Pt and ${\mathrm{SrTiO}}_3$, in order to differentiate between magnetic and electric quadrupolar relaxation mechanisms. In Pt, the ratio of the $1/T_1$ spin relaxation rates $R_{\text{Pt}}$ was found to be 6.82(29), which is close to but less than the theoretical limit of $\sim 7.68$ for pure magnetic relaxation. In ${\mathrm{SrTiO}}_3$ this ratio was found to be 2.7(3), which is close to but larger than the theoretical limit of $\sim 2.14$ expected for pure electric quadrupolar relaxation. These results bring insight into the nature of the fluctuations in the local environment of implanted ${}^8\mathrm{Li}$ observed by $\beta$-NMR.

Using ion-implanted ${}^8\mathrm{Li} \beta$-detected NMR, we study the evolution of the correlated metallic state of ${\mathrm{LaNiO}}_3$ in a series of ${\mathrm{LaNiO}}_3/{\mathrm{LaAlO}}_3$ superlattices as a function of bilayer thickness. Spin-lattice relaxation measurements in an applied field of $6.55\mathrm{T}$ reveal two equal amplitude components: one with metallic ($T$ linear) $1/T_1$ and a second with a more complex $T$ dependence. The metallic character of the slow relaxing component is only weakly affected by the ${\mathrm{LaNiO}}_3$ thickness, while the fast component is much more sensitive, exhibiting the opposite temperature dependence (increasing toward low $T$) in the thinnest, most magnetic samples. The origin of this bipartite relaxation is discussed in terms of electronic phase separation.

We report measurements of the diffusion rate of isolated ion-implanted ${}^8{\mathrm{Li}}^{+}$ within $\sim 120\mathrm{nm}$ of the surface of oriented single-crystal rutile ${\mathrm{TiO}}_2$ using a radiotracer technique. The $\alpha$ particles from the ${}^8\mathrm{Li}$ decay provide a sensitive monitor of the distance from the surface and how the depth profile of ${}^8\mathrm{Li}$ evolves with time. The main findings are that the implanted ${\mathrm{Li}}^{+}$ diffuses and traps at the (001) surface. The $T$ dependence of the diffusivity is described by a bi-Arrhenius expression with activation energies of 0.3341(21) eV above 200 K, whereas at lower temperatures it has a much smaller barrier of 0.0313(15) eV. We consider possible origins for the surface trapping, as well the nature of the low-$T$ barrier.

A local area network (LAN) consists typically of several telecommunication nodes, all of which share a public IP address and a single point of contact with the Internet, namely the router. For an outside observer, the whole LAN with all its nodes would look point-like (having one, shared, "public IP" address and a single connection with the Internet), but in its interactions it would appear field-like, as a LAN of several nodes, each with its own "private IP" address, has an internal structure and interacts with the outside world differently than a single node would. In this study, the above particle/LAN analogy will be used as a basis of Átmiton theory, according to which, elementary particles are made of LANs consisting of a type of telecommunication node - called átmiton - and space is a 3D network of átmita with the simple cubic topology. In this work, it is demonstrated that connecting a particle/LAN entity on the lattice of space distorts its local topology, effectively introducing a crystal defect to the lattice of space. This defect increases the distance between points lying at opposite sides of it. The internal interactions of any massive object should be producing constantly copious numbers of such space-defects, which diffuse away from their source, by means of a random walk. Here it is suggested that general relativity's notion of spacetime's curvature is equivalent to the aforementioned diffusion-driven impurity model in the flat, discrete lattice of space of Átmiton theory. Their equivalency is demonstrated for the specific case of a spherical mass, around which the Schwarzschild metric is shown to be valid.