The study investigates the behavior of Hg-Xe systems after annealing to 20 K, finding that the lnR ~ T-1/4 relationship holds. These films do not exhibit superconductivity down to temperatures as low as 1.5 K. The behavior suggests a metal-to-nonmetal transition in the Hg-Xe system, which depends on concentration and is close to the critical concentration for continuous percolation in three dimensions. Beyond this threshold, the systems show negative TCR but remain superconductors. Further increasing Xe concentration leads to a regime dominated by hopping, likely transitioning to an insulating state through a Mott-Anderson transition, accompanied by the disappearance of superconductivity. In another study, the authors compare the properties of LaCu2Si2 and CeCu2Si2, noting that LaCu2Si2 behaves like a normal metal, while CeCu2Si2 shows low-temperature anomalies typical of "unstable 4f shell" behavior and transitions into a superconducting state at \( T_c \approx 0.5 \) K. The superconductivity in CeCu2Si2 is attributed to interactions between the unstable 4f shells and conduction electrons, leading to a Meissner effect in a significant fraction of the sample. The specific-heat jump at \( T_c \) suggests that Cooper-pair states are formed by heavy fermions, indicating that CeCu2Si2 is a high-temperature superconductor that cannot be described by conventional superconductivity theories.The study investigates the behavior of Hg-Xe systems after annealing to 20 K, finding that the lnR ~ T-1/4 relationship holds. These films do not exhibit superconductivity down to temperatures as low as 1.5 K. The behavior suggests a metal-to-nonmetal transition in the Hg-Xe system, which depends on concentration and is close to the critical concentration for continuous percolation in three dimensions. Beyond this threshold, the systems show negative TCR but remain superconductors. Further increasing Xe concentration leads to a regime dominated by hopping, likely transitioning to an insulating state through a Mott-Anderson transition, accompanied by the disappearance of superconductivity. In another study, the authors compare the properties of LaCu2Si2 and CeCu2Si2, noting that LaCu2Si2 behaves like a normal metal, while CeCu2Si2 shows low-temperature anomalies typical of "unstable 4f shell" behavior and transitions into a superconducting state at \( T_c \approx 0.5 \) K. The superconductivity in CeCu2Si2 is attributed to interactions between the unstable 4f shells and conduction electrons, leading to a Meissner effect in a significant fraction of the sample. The specific-heat jump at \( T_c \) suggests that Cooper-pair states are formed by heavy fermions, indicating that CeCu2Si2 is a high-temperature superconductor that cannot be described by conventional superconductivity theories.