Structural Performance of Ferrocement Panels under Low- and High-Velocity Impact Load.

The primary objective of this experimental study is to examine the response and energy absorption capacity of ferrocement panels exposed to low- and high-velocity impact loads. The panels are reinforced with two different types of mesh layers, namely, welded wire grid (WWG) and expanded wire grid (EWG), with varying percentages of steel fibers (SF). The ferrocement panel system is made up of cement mortar reinforced with 0-2% SF with an increment of 1% and wire grid layers arranged in three different layers 1, 2, and 3. A consistent water-cement ratio (w/c) of 0.4 is maintained during mortar preparation, and all panels are subjected to a 28-day curing process in water. The study utilized square-shaped ferrocement panels measuring 290 mm × 290 mm × 50 mm. The panels are exposed to repeated impact blows from a 2.5 kg falling mass dropped from a height of 0.80 m. The count of blows necessary to commence the first crack formation and the cause of ultimate failure are recorded for each panel. The study reports that an increase in SF content and the number of wire grid layers increased the number of blows needed for both the first crack and the ultimate failure. In the high-velocity impact test, 7.62 mm bullets are fired at the panels from a distance of 10 m with a striking velocity of 715 m/s. The study observed and analyzed the extent of spalling, scabbing, and perforation. The results showed that an increase in fiber content and the number of wire grid layers led to a decrease in the area of scabbing and spalling compared with the control specimens. It was also possible to see the mode of failure and crack pattern for impacts with low and high velocities.

Solid state mononuclear divalent nickel spin crossover complexes.

Spin crossover complexes containing 3d4-3d7 transition metal ions with tunable electronic configurations in appropriate ligand field environments have been extensively investigated. In contrast, the development of 3d8 divalent nickel complexes displaying such a spin crossover behavior is far behind. The increasing number of X-ray single crystal structures along with magnetic evidence and thermodynamic equilibrium indicate that bistable divalent nickel complexes are gradually recognized to be a formal member of the "spin crossover family". Unfortunately, the rarity of nickel spin crossover complexes is occasionally mentioned. This Perspective article highlights examples of mononuclear 3d8 nickel spin crossover complexes in dynamic rearrangements with characterized solid state structures from the viewpoint of types of ligands utilized.