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Dermal armor, such as fish scales or armadillo osteoderms, has been known to exhibit high performance and good flexibility defending against attack. The top layer of the dermal armor usually consists of a segmented hard bony layer. The soft inner layer composed of collagen fibers connects and holds the hard layer. Inspired by the dermal armor of armadillos, bioinspired protection armor is studied for impact resistance. The hexagonal scales tessellate the surface continuously and work as the hard bony layer protecting the soft inner layer from penetration. Ultra-high molecular weight polyethylene (UHMWPE) is used as the connectivity layer to support and hold the scales. To investigate the dynamic response of the bioinspired protection armor, drop weight impact tests are carried out. A finite element model is established to study the dynamic response of bioinspired protection armor. The impact process images captured by a high speed camera and the experimental data of drop hammer acceleration tests verify the validity of the numerical model. The dynamic resistance behavior and the synergy effect of each part of the bioinspired protection armor combined with the protected objects are studied in detail by numerical simulation. The results show that the bioinspired protection armor has marked energy absorption ability. A synergistic dissipation mechanism is activated in the impact process, which can dissipate impact energy and make the impact load distribution more uniform. The UHMWPE between the outer layer and the soft substrate plays a significant role not only related to support and connection, but also for the force balance and energy absorption. The mechanism of energy absorption of the bioinspired protection armor revealed in this paper can be taken as a new guideline for designing a novel protective armor.

In petroleum production, microbial research has been widely carried out to serve different engineering applications. For instance, studies on microbial-induced corrosion (MIC) control and microbial-enhanced oil recovery (MEOR) focus on the microbial activities in surface pipelines and in subsurface strata (oil reservoirs), respectively. However, the living microorganisms attaching to the inner surfaces of vertical wells as biofilms has not attracted much attention In a normal water-flooded oil-production system, the water is transferred between the surface and subsurface reservoirs through the vertical wells so that the wellbore biofilms are able to constantly affect the surface and subsurface communities. Therefore, it is necessary to reveal the structure and function of the sessile community along the vertical wellbore. Since in situ sampling from underground vertical wells is technologically complex and expensive, in this study, biofilm samples were obtained during well workover from well tube segments corresponding to different original depths (approximately 0 m, 300 m, 800 m, and 1300 m). Moreover, the injection water was also sampled. The results of 16S rRNA gene library sequencing showed that the microbial community in the water phase was distinct from that found in the biofilms (dissimilarity 0.63–0.78), although they shared 200–272 OTUs. At the phylum level, the dominant phylum, Euryarchaeota, accounted for 21.5%–35.8% in the four biofilms, while only 11.7% in the water phase. Proteobacteria was the dominant phylum in the water phase (74.6%), while accounted for only 7.7%–20.1% in the biofilms. With increasing depth from 0 m to 1300 m, the richness and diversity of biofilms declined (Chao index of 608.8 to 442.4, Shannon index of 4.01 to 3.48), and the bacterial abundance of biofilms declined from 78.4% to 63.5%, while the archaeal abundance increased from 21.6% to 36.5%. The geothermal gradient, depleted oxygen and even turbulence were the significant factors affecting the depth-dependent variation in the communities. For instance, the relative abundance of the hydrogenotrophic genera increased from 8.62% to 28.8% with increasing depth. In addition, the sudden variation of wellbore biofilms suggested a presumed boundary of the microbial ecosystem around the depth of 1000 m, which is consistent with existing reports. This is the first study to directly investigate and reveal the depth-dependent distribution of the wellbore community along a deep well (depth >1300 m). The distinct and depth-dependent communities suggested that direct investigation is necessary for completely understanding and efficiently controlling microbial activities in oil production processes, including MIC control and MEOR.