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The microbial community composition of coastal dunes can vary across environmental gradients, with the potential to impact erosion and deposition processes. In coastal foredunes, invasive plant species establishment can create and alter environmental gradients, thereby altering microbial communities and other ecogeomorphic processes with implications for storm response and management and conservation efforts. However, the mechanisms of these processes are poorly understood. To understand how changing microbial communities can alter these ecogeomorphic dynamics, one must first understand how soil microbial communities vary as a result of invasion. Towards this goal, bacterial communities were assessed spatially along foredune microhabitats, specifically in barren foredune toe and blowout microhabitats and in surrounding vegetated monocultures of native Ammophila breviligulata and invasive Carex kobomugi. Across dune microhabitats, microbial composition was more dissimilar in barren dune toe and blowout microhabitats than among the two plant species, but it did not appear that it would favor the establishment of one plant species over the other. However, the subtle differences between the microbial community composition of two species could ultimately aid in the success of the invasive species by reducing the proportions of bacterial genera associated exclusively with A. breviligulata. These results suggest that arrival time may be crucial in fostering microbiomes that would further the continued establishment and spread of either plant species.

In this study, the failure mechanisms of Cu-Cu joints under thermal cycling were investigated. Two structures of dielectrics (PBO/underfill/PBO and SiO2) were employed to seal the joints. Stress gradients induced in the joints with the different dielectrics were simulated using a finite element method (FEM) and correlated with experimental observations. We found that interfacial voids were forced to move in the direction from high stress regions to low stress ones. The locations of migrated voids varied with the dielectric structures. Under thermal cycling, such voids were likely to move forward to the regions with a small stress change. They relocated and merged with their neighboring voids to lower the interfacial energy.

This paper concerns the algorithm of transition piezoelectric elements for adaptive analysis of electro-mechanical systems. In addition, effectivity of the proposed elements in such an analysis is presented. The elements under consideration are assigned for joining basic elements which correspond to the mechanical models of either the first or higher order, while the electric model is of arbitrary order. In this work, three variants of the transition models are applied. The first one assures continuity of displacements between the basic models and continuity of electric potential between these models, as well. The second transition piezoelectric model guarantees additional continuity of the stress field between the basic models. The third transition model additionally enables continuous change of the strain state between the basic models. Based on the mentioned models, three types of the corresponding transition finite elements are introduced. The applied finite element approximations are hpq/hp-adaptive ones, which allows element-wise changes of the element size parameter h, and the element longitudinal and transverse orders of approximation, respectively, p and q, depending on the error level. Numerical effectiveness of the models and their approximations is investigated in the contexts of: ability to remove high stress gradients between the basic and transition models, and convergence of the numerical solutions for the model problems of piezoelectrics with and without the proposed transition elements.