The impact of habitat complexity on the structure of marine sessile communities and larvae supply.

Coastal infrastructure replaces complex and heterogeneous natural habitats with flat, two-dimensional concrete walls, reducing refuges against predation, which modifies the composition and identity of the dominant species in sessile communities. This modification in the community structure can also change the reproductive propagules available in plankton, affecting the recruitment dynamics in communities from natural habitats nearby. Here, we tested the combined effects of the habitat type (simple vs. complex with holes) and predation on the diversity, larval production, and structure of sessile communities from a recreational marina. Complex substrates showed a larger biomass and a greater abundance of solitary organisms, mainly ascidians and bivalves, that benefited from refuges. Barnacles and calcified encrusting bryozoans dominated simple, flat substrates. The difference in dominance affected the pool of larvae produced by the communities. After eight months, communities growing on flat substrates produced more barnacle larvae than those from complex substrates, where larvae of ascidians were more abundant. However, this difference disappeared after 18 months of community development. The difference in the pool of larvae between simple and complex substrates did not affect the structure of the community on flat substrates nearby, which was determined by the predation regime. In the studied region, communities in artificial environments are under intense predation control, suppressing eventual recruitment differences in communities developing in flat substrates. Large interventions that modify habitat topography, creating refuges in the subtidal zone, can change the dynamic of the sessile communities in artificial habitats and, consequently, the larval supply in the vicinities. However, differences in larval supply will only translate in distinct sessile communities when the scale of intervention encompasses large areas, and other processes do not buffer the differences in recruitment.

Osseointegration of functionally graded Ti6Al4V porous implants: Histology of the pore network.

The additive manufacturing of titanium into porous geometries offers a means to generate low-stiffness endosseous implants with a greater surface area available for osseointegration. In this work, selective laser melting was used to produce gyroid-based scaffolds with a uniform pore size of 300 µm or functionally graded pore size from 600 µm to 300 µm. Initial in vitro assessment with Saos-2 cells showed favourable cell proliferation at pore sizes of 300 and 600 µm. Following implantation into rabbit tibiae, early histological observations at four weeks indicated some residual inflammation alongside neovessel infiltration into the scaffold interior and some early apposition of mineralized bone tissue. At twelve weeks, both scaffolds were filled with a mixture of adipocyte-rich marrow, micro-capillaries, and mineralized bone tissue. X-ray microcomputed tomography showed a higher bone volume fraction (BV/TV) and percentage of bone-implant contact (BIC) in the implants with 300 µm pores than in the functionally graded specimens. In functionally graded specimens, localized BV/TV measurement was observed to be higher in the innermost region containing smaller pores (estimated at 300-400 µm) than in larger pores at the implant exterior. The unit cell topology of the porous implant was also observed to guide the direction of bone ingrowth by conducting along the implant struts. These results suggest that in vivo experimentation is necessary alongside parametric optimization of functionally graded porous implants to predict short-term and long-term bone apposition.

Bioinspired design proposal for a new external bone fixator device.

The article presents a new medical device through an authorial and interdisciplinary approach. It consists of a flexible external fixator, whose flexible property may bring advantages over rigid mechanisms. Its design was inspired by the DNA biological mechanism of condensation, while the modeling was based on the pseudo-rigid modeling technique. From the models obtained, this study conducted prototyping and computational tests to obtain a proof-of-concept of the bioinspired theory and dynamic functioning effectiveness. The prototyping relied on hot glue manufacturing and the computational simulations consisted of linear static analysis. The experimental analysis concluded that the prototype with fewer beams and thinner beams delivered better results in all three parameters: flexibility, height variation and rotation arc. In the computational analysis, among the design models with the variation of the number of beams, the model with 8 beams performed better. Concerning thickness variation, the one whose beams measured 8 mm in thickness showed better results. Among the models with length variation, the design made with 100 mm long beams better equilibrated the parameters.

Biomimetic Applications of Mimosa pudica L. in the Theoretical Development of a Pneumatic Actuator

Abstract For years, plants have tried to adapt to the environmental changes caused by time, improving and developing their biological structures. Many of these structural and functional properties of plants have great potential for the development of concepts in the field of biomimetics. Recent previous studies have shown that the movement of Mimosa pudica L. is caused by the variation of turgor pressure within the cells of organs motor, that is, the influx and efflux of water by osmosis, generating reversible changes in the shape of the plant. Thus, this article sought, through research and literature references, to carry out a survey of studies related to the seismonastic movements of the plant and its applications in the design of technological innovations. In addition, it presents the development of a pneumatic actuator based on the abstraction of the morphology of the primary pulvinus of the plant and the concept of bioinspired design of the theoretical model based on the technology of soft robots. As a result, the bioinspired actuator model of the plant movement is described. In addition, with a simulation, it was possible to observe that the flexible modules are capable of generating the proposed movement and allow movement of the actuator. With the study, it was possible to understand that the movement of the plant appears as an embryo for the projection of technologies, and that the proposed study appears as the basis for research with pneumatic actuators.