Surface Response to Mechanics of Hardness and Wear Characteristics of Nanoscale Hydrophobic Film

There is an increase in demand for durable and efficient organic nanoscale coatings for modern manufacturing systems and/or components for various applications. In wake of this demand, a new superhydrophobic silane compound was deposited on mild steel, stainless steel and titanium substrates which were pre-treated with alumina via the atomic layer deposition (ALD) method. Three substrates were considered for evolving properties comparison, also, determination of the influence of substrates’ response to films mechanical properties. The mechanical properties and the failure mechanics were investigated through nanoindentation and nanoscratch while the morphologies were examined through a field emission scanning electron microscope. The morphological evolution and mechanical viability indicated that stainless steel showed the most robust properties when compared with other substrates. Therefore, a nanoscale coating’s mechanical strength can be influenced by the substrate’s material compositions.

Mechanistic insights from emergent landslides in physical experiments

Landslides pose a major natural hazard, and heterogeneous conditions and limited data availability in the field make it difficult to connect mapped landslide inventories to the underlying mass-failure mechanics. To test and build predictive links between landslide observations and mechanics, we monitored 67.89 h of physical experiments in which an incising and laterally migrating river generated landslides by undercutting banks of moist sand. Using overhead photos (every 20 s) and 1-mm-resolution laser topographic scans (every 15–30 min), we quantified the area, width, length, depth, volume, and time of every visible landslide, as well as the scarp angles for those within 3 min prior to a topographic scan. Both the landslide area–frequency distribution and area–volume relationship are consistent with those from field data. Cohesive strength controlled the peak in landslide area–frequency distribution. These results provide experimental support for inverting landslide inventories to recover the mechanical properties of hillslopes, which can then be used to improve hazard predictions.

Avalanches and power law behavior in aortic dissection propagation

Aortic dissection is a devastating cardiovascular disease known for its rapid propagation and high morbidity and mortality. The mechanisms underlying the propagation of aortic dissection are not well understood. Our study reports the discovery of avalanche-like failure of the aorta during dissection propagation that results from the local buildup of strain energy followed by a cascade failure of inhomogeneously distributed interlamellar collagen fibers. An innovative computational model was developed that successfully describes the failure mechanics of dissection propagation. Our study provides the first quantitative agreement between experiment and model prediction of the dissection propagation within the complex extracellular matrix (ECM). Our results may lead to the possibility of predicting such catastrophic events based on microscopic features of the ECM.