Abstract Metals, such as silver, gold, and copper are known for their biocidal properties, mimicking the host defense peptides (HDPs) of the immune system. Developing materials with such properties has great importance in medicine, especially when combined with 3D printing technology, which is an additional asset for various applications. In this work, copper nanoparticles were used as filler in stereolithography (SLA) ultraviolet (UV) cured commercial resin to induce such biocidal properties in the material. The nanocomposites developed featured enhanced mechanical responses when compared with the neat material. The prepared nanocomposites were employed to manufacture specimens with the SLA process, to be tested for their mechanical response according to international standards. The process followed was evaluated with Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric anal ysis (TGA). The antibacterial activity of the fabricated anocomposites was evaluated using the agar-well diffusion method. Results showed enhanced mechanical performance of approximately 33.7% in the tensile tests for the nanocomposites filled with 1.0 wt.%. ratios, when compared to the neat matrix material, while this loading showed sufficient antibacterial performance when compared to lower filler loadings, providing an added value for the fabrication of effective nanocomposites in medical applications with the SLA process.

Abstract The granular media friction pad (GMFP) inspired by the biological smooth attachment pads of cockroaches and grasshoppers employs passive jamming, to create high friction forces on a large variety of substrates. The granular medium inside the pad is encased by a flexible membrane which at contact formation greatly adapts to the substrate profile. Upon applying load, the granular medium undergoes the jamming transition and changes from fluid-like to solid-like properties. The jammed granular medium, in combination with the deformation of the encasing elastic membrane,results in high friction forces on a multitude of substrate topographies. Here we explore the effect of elasticity variation on the generation of friction by varying granular media filling quantity as well as membrane modulus and thickness. We systematically investigate contact area and robustness against substrate contamination, and we also determine friction coefficients for various loading forces and substrates. Depending on the substrate topography and loading forces, a low filling quantity and a thin, elastic membrane can be favorable, in order to generate the highest friction forces.

Abstract Here we demonstrate the possibility of using acyclic diethylacetal of acetaldehyde (ADA) with low cytotoxicity for the fabrication of hydrogels via Schiff bases formation between chitosan and acetaldehyde generated in situ from acetals in chitosan acetate solution. This approach is more convenient than a direct reaction between chitosan and acetaldehyde due to the better commercial availability and higher boiling point of the acetals. Rheological data confirmed the formation of intermolecular bonds in chitosan solution after the addition of acetaldehyde diethyl acetal at an equimolar NH2 : acetal ratio. The chemical structure of the reaction products was determined using elemental analysis and 13C NMR and FT-IR spectroscopy. The formed chitosan-acetylimine under went further irreversible redox transformations yielding a mechanically stable hydrogel insoluble in a broad pH range. The reported reaction is an example of when an inappropriate selection of acid type for chitosan dissolution prevents hydrogel formation.

Abstract In a previous paper, the authors dealt with the current showstoppers that inhibit commercial applicability of morphing systems. In this work, the authors express a critical vision of the current status of the proposed architectures and the needs that should be accomplished to make them viable for installation onboard of commercial aircraft. The distinction is essential because military and civil issues and necessities are very different, and both the solutions and difficulties to be overcome are widely diverse. Yet, still remaining in the civil segment, there can be other differences, depending on the size of the aircraft, from large jets to commuters or general aviation, which are classifiable in tourism, acrobatic, ultralight, and so on, each with their own peculiarities. Therefore, the paper aims to trace a common technology denominator, if possible, and envisage a future perspective of actual applications.

Abstract In this study, Cuprous Oxide (Cu2O), known for its mechanism against bacteria, was used as filler to induce biocidal properties on a common commercial resin stereolithography (SLA) 3D printing resin. The aim was to develop nanocomposites suitable for the SLA process with a low-cost process that mimic host defense peptides (HDPs). Such materials have a huge economic and societal influence on the global technological war on illness and exploiting 3D printing characteristics is an additional asset for these materials. Their mechanical performance was also investigated with tensile, flexural, Charpy’s impact, and Vickers microhardness tests. Morphological analysis was performed through scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectroscopy (EDS) analysis, while the thermal behavior was studied through Thermogravimetric Analysis (TGA). The antibacterial activity of the fabricated nanocomposites was investigated using a screening agar well diffusion method, for a gram-negative and a gram-positive bacterium. Three-dimensional printed nanocomposites exhibited antibacterial performance in all loadings studied, while their mechanical enhancement was approximately 20% even at low filler loadings, revealing a multi-functional performance and a potential of Cuprous Oxide implementation in SLA resin matrices for engineering and medical applications.

Abstract Bioinspired self-shaping is an approach used to transform flat materials into unusual three-dimensional (3D) shapes by tailoring the internal architecture of the flat material. Bioinspiration and bioinspired materials have a high potential for fostering sustainable development, yet are often fashioned out of expensive and synthetic materials. In this work, we use bioinspiration to endow clay with self-shaping properties upon drying. The composites created are based on clay and starch, and the internal architecture is built using celery fibers. The viscosity, shrinkage, and bending of the architected composite monolayers are studied for several compositions by measuring penetration depth and using optical characterization methods. Bilayer structures inspired from plants are then processed using a simple hand layup process to achieve bending, twisting, and combinations of those after drying. By layering a mixture of 32 vol% clay, 25.8 vol% starch, and 42.2 vol% water with 40 wt% embedded aligned celery fibers, it is possible to obtain the desired shape change. The work presented here aims at providing a simple method for teaching the concept of bioinspiration, and for creating new materials using only clay and plant-based ingredients. Rejuvenating clay with endowed self-shaping properties could further expand its use. Furthermore, the materials, methods, and principles presented here are affordable, simple, largely applicable, and could be used for sustainable development in the domain of education as well as materials and structures.

Abstract Urban growth has increased the risk of over-heating both in the microclimate and inside buildings, affecting thermal comfort and energy efficiency. That is why this research aims to evaluate the energy performance of buildings in terms of thermal comfort (operative temperature (OP) levels,satisfied hours of natural ventilation SHNV, thermal lag), and energy efficiency (roof heat gains and surface temperatures) in an urban area in Panama City, using superficial-heat-dissipation biomimetic strategies. Two case studies, a base case and a proposed case, were evaluated using the Designbuilder software through dynamic simulation. The proposed case is based on a combined biomimetic strategy; the reflective characteristics of the Saharan ant applied as a coating on the roofs through a segmented pattern such as the Zebra’s stripes (one section with coating, and another without). Results showed that the OP decreased from 8 to 10 ◦C for the entire urban zone throughout the year. A reduction of 3.13% corresponding to 8790 kWh per year was achieved for cooling energy consumption. A difference of 5 ◦C in external surface temperature was obtained, having a lower temperature in which the biomimetic strategy was applied. Besides, it was evidenced that a contrasted-reflectivity stripes pitched roof performed better than a fully reflective roof. Thus, the functionality of Zebra stripes, together with the reflective characteristics of the Saharan ant, provide better performance for buildings’ thermal regulation and energy needs for cooling.

Abstract Diabetes mellitus, a metabolic disease characterized by chronically elevated blood glucose levels, affects about 29 million Americans and more than 422 million adults all over the world. Particularly, type 2 diabetes mellitus (T2DM) accounts for 90–95% of the cases of vascular disease and its prevalence is increasing due to the rising obesity rates in modern societies. Although multiple factors associated with diabetes, such as reduced red blood cell (RBC) deformability, enhanced RBC aggregation and adhesion to the endothelium, as well as elevated blood viscosity are thought to contribute to the hemodynamic impairment and vascular occlusion, clinical or experimental studies cannot directly quantify the contributions of these factors to the abnormal hematology in T2DM. Recently, computational modeling has been employed to dissect the impacts of the aberrant biomechanics of diabetic RBCs and their adverse effects on microcirculation. In this review, we summarize the recent advances in the developments and applications of computational models in investigating the abnormal properties of diabetic blood from the cellular level to the vascular level. We expect that this review will motivate and steer the development of new models in this area and shift the attention of the community from conventional laboratory studies to combined experimental and computational investigations, aiming to provide new inspirations for the development of advanced tools to improve our understanding of the pathogenesis and pathology of T2DM.

Abstract Animal locomotion is influenced by a combination of constituent joint torques (e.g., due to limb inertia and passive viscoelasticity), which determine the necessary muscular response to move the limb. Across animal size-scales, the relative contributions of these constituent joint torques affect the muscular response in different ways. We used a multi-muscle biomechanical model to analyze how passive torque components change due to an animal’s size-scale during locomotion. By changing the size-scale of the model, we characterized emergent muscular responses at the hip as a result of the changing constituent torque profile. Specifically, we found that activation phases between extensor and flexor torques to be opposite between small and large sizes for the same kinematic motion. These results suggest general principles of how animal size affects neural control strategies. Our modeled torque profiles show a strong agreement with documented hindlimb torque during locomotion and can provide insights into the neural organization and muscle activation behavior of animals whose motion has not been extensively documented.

Abstract This study attempted to investigate the effect of sandblasting and H2O2 treatments on the microshear bond strength of two commercially available resin cements. A total of 90 cube-shaped specimens of commercially pure titanium (cp-Ti) were divided into two groups of Panavia and MHA cements (n = 45). Samples of the Panavia group were randomly divided into three subgroups of 15 samples, including subgroups (no treatment, aluminum oxide sandblasting, and immersion in 35% hydrogen peroxide solution with halogen light). Once the treatment was completed, Panavia V5 was applied on the cp-Ti surface by a Tygon tube. The 45 specimens of the MHA cement group were randomly divided into three subgroups (n = 15) similarly to the Panavia group. Then, the MHA was applied on the surface of cp-Ti. A universal testing machine was used to measure and examine the microshear bond strength of cement to cp-Ti subsequent to the step of thermocycling. According to results, in the Panavia cement group, the SBS of sandblasting treatment was significantly higher than that of the H2O2 treatment subgroup (p < 0.05), which displayed a significantly higher SBS than that of the no-treatment subgroup (p < 0.001). In regard to the MHA group, the SBS of the H2O2 treatment subgroup was significantly lower than that of the sandblasting treatment subgroup (p < 0.001), whereas there were no significant differences between the SBS of the no treatment and H2O2 treatment subgroups (p = 0.35). Considering the comparison between Panavia and MHA cases,there were no significant differences observed among the no-treatment subgroups (p = 0.34), as well as the sandblasting treatment subgroups (p = 0.67), while the SBS of the H2O2 treatment subgroup in Panavia cement was higher than that of the H2O2 subgroup in MHA cement (p < 0.001). In conclusion,in both Panavia V5 and MHA cements, sandblasting treatment could improve the bond strength between the titanium surface. However, H2O2 treatment proved to be capable of enhancing the bond strength of Panavia V5 cement without causing any positive effects on the bond strength of MHA cement.

Abstract Developing new barrier membranes with improved biomechanical characteristics has acquired much interest owing to their crucial role in the field of periodontal tissue regeneration. In this regard, we enriched the electrospun polycaprolactone (PCL)/gelatin (Gel) membranes by adding bioglass (BG) or Cu-doped bioglass (CuBG) and examined their cellular adhesion and proliferation potential in the presence of alveolar bone marrow-derived mesenchymal stem cells (aBMSCs). The membranes were fabricated and characterized using mechanical strength, SEM, FTIR, EDX, and ICP assay. Besides, aBMSCs were isolated, characterized, and seeded with a density of 35,000 cells in each experimental group. Next, the cellular morphology, cell adhesion capacity, proliferation rate, and membrane antibacterial activity were assessed. The results displayed a significant improvement in the wettability, pore size, and Young’s modulus of the PCL membrane following the incorporation of gelatin and CuBG particles. Moreover, all scaffolds exhibited reasonable biocompatibility and bioactivity in physiological conditions. Although the PCL/Gel/CuBG membrane revealed the lowest primary cell attachment, cells were grown properly and reached the confluent state after seven days. In conclusion, we found a reasonable level of attachment and proliferation of aBMSCs on all modified membranes. Meanwhile, a trace amount of Cu provided superiority for PCL/Gel/CuBG in periodontal tissue regeneration.

Abstract Since the invention of the aircraft, there has been a need for better surface design to enhance performance. This thirst has driven many aerodynamicists to develop various types of aerofoils. Most researchers have strongly assumed that smooth surfaces would be more suitable for air transport vehicles. This ideology was shattered into pieces when biomimetics was introduced. Biomimetics emphasized the roughness of a surface instead of smoothness in a fluid flow regime. In this research, the most popular 0012 aerofoils of the National Advisory Committee for Aeronautics (NACA) are considered to improve them, with the help of a surface pattern derived from the biological environment. Original and biomimetic aerofoils were designed in three dimensions with the help of olidworks software and analyzed in the computational flow domain using the commercial code ANSYS Fluent. The implemented biomimetic rough surface pattern upgraded the NACA 0012 aerofoil design in the transonic flow regime. Lift and viscous forces of the aerofoil improved up to 5.41% and 9.98%, respectively. This research has proved that a surface with a little roughness is better than a smooth surface.

Abstract With the development of the biomimicry approach, new and creative ideas have been established to solve problems in architectural design. In the designs based on this process, “nature” is used as a diverse data source for the transfer of these data to various processes, functions, materials,and structures. The primary purpose of this paper is to explore the development of biomimicry as an architectural approach, with a bibliometric review of research related to biomimicry and energy efficiency. Emphasis on the importance of the need for biomimicry in modern designs is another goal of this study. In this study, articles published in the Web of Science database (2010–2021) were analyzed. VOSviewer and SankeyMATIC software were used to represent the analysis results graphically. According to the results of this study, in addition to the inadequacy of biomimicry research, the need for further research became apparent. This review can serve as a reference for future studies to transfer natural phenomena to architecture in order to solve the problem of efficient energy consumption.