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Biological systems and their structural and functional adaptations provide valuable insights into increasing the longevity of engineered materials. A striking example is the hemiparasitic European mistletoe ( Viscum album ), which forms a lifelong (over 20 years) connection with its host tree, providing physiological supply and mechanical anchorage. The V-shaped interface between mistletoe and host is characterized by a lignification and cell wall gradient that bridges the mechanical differences between the adjacent tissues. These characteristics of the mistletoe–host interface can be transferred to functionally graded polymeric materials. Using extrusion molding and hot pressing, we developed a material system that combines pure and glass-fiber-reinforced polypropylene and exhibits a continuously graded mistletoe-inspired V-shaped interface. Microtomographic analyses quantified the gradual transition of the glass fiber content along one specimen from 0 to 30%, further revealing the random fiber orientation in the polymer matrix. Tensile tests showed that both Young’s modulus (by 38%) and ultimate tensile strength (by 62%) could be increased by introducing V-shaped interfaces. Digital image correlation analysis and the fracture images showed that the positioning of the area with the highest glass fiber content can lead to spatial control over local strain behavior and the failure point. Moreover, this phenomenon was transferred to metamaterial structures where the material gradient counteracts the geometric gradient (beam thickness). The results highlight the effective anchoring method of mistletoe through graded structuring of the interface with the host branch and provide a framework for creating bioinspired functionally graded material systems with programmable local strain and failure behavior.

In this study, six common fused filament fabrication (FFF) polymers—PEEK, PLA, PETG, ABS, Nylon, and TPU—were acclimatized at 15%, 45%, and 95% relative humidity (RH) to characterize tensile behavior, including Young’s modulus, maximum strain, and ultimate tensile strength. Separately, mechanical metamaterial samples at relative densities (RD) of 25%, 35%, and 45% were tested in compression at the same RH levels to evaluate stiffness, strength, and Poisson’s ratio. The water absorption process can generally be divided into different stages—rapid uptake (0–12 h), a plateau (12–60 h), and a late rebound (60–100 h)—with a total uptake ranking of Nylon > PETG > PLA ≈ ABS > TPU ≈ PEEK. Samples under tensile and compressive tests show a great difference between properties at different RD and RH levels. Poisson’s ratio indicates that material responses remain predictable at low-to-moderate RH, whereas high RH serves as a critical threshold inducing abrupt Poisson’s ratio behavioral shifts. This study provides systematic validation for the application of 3D-printed metamaterials under varying humidity conditions, such as biomedical implants in human body.

The material bone has attracted the attention of material scientists due to its fracture resistance and ability to self-repair. A mechanoregulated exchange of damaged bone using newly synthesized material avoids the accumulation of fatigue damage. This remodeling process is also the basis for structural adaptation to common loading conditions, thereby reducing the probability of material failure. In the case of fracture, an initial step of tissue formation is followed by a mechanobiological controlled restoration of the pre-fracture state. The present perspective focuses on these mechanobiological aspects of bone remodeling and healing. Specifically, the role of the control function is considered, which describes mechanoregulation as a link between mechanical stimulation and the local response of the material through changes in structure or material properties. Mechanical forces propagate over large distances leading to a complex non-local feedback between mechanical stimulation and material response. To better understand such phenomena, computer models are often employed. As expected from control theory, negative and positive feedback loops lead to entirely different time evolutions, corresponding to stable and unstable states of the material system. After some background information about bone remodeling and healing, we describe a few representative models, the corresponding control functions, and their consequences. The results are then discussed with respect to the potential design of synthetic materials with specific self-repair properties.

Thin films are used in a wide variety of computing and communication applications although their fatigue behavior and its dependence on alloying elements are not very well known. In this paper, we present an experimental implementation of a novel high-throughput fatigue testing method for metallic thin films. The methodology uses the fact that the surface strain amplitude of a vibrating cantilever decreases linearly from the fixed end to the free end. Therefore, a thin film attached to a vibrating cantilever will experience a gradient of strain and corresponding stress amplitudes along the cantilever. Each cantilever can be used to extract a lifetime diagram by measuring the fatigue-induced damage front that progresses along the cantilever during up to 10 8 load cycles.

As a relatively new class of hierarchically structured materials, nanotwinned (NT) metals exhibit an exceptional combination of high strength, good ductility, large fracture toughness, remarkable fatigue resistance, and creep stability. This article reviews current studies on fracture, fatigue, and creep of NT metals, with an emphasis on the fundamental deformation and failure mechanisms. We focus on the complex interactions among cracks, dislocations, and twin boundaries, the influence of microstructure, twin size, and twinning/detwinning on damage evolution, and the contribution of nanoscale twins to fatigue and creep under indentation and irradiation conditions. The article also includes critical discussions on the effects of twin thickness and grain size on the fracture toughness, fatigue resistance, and creep stability of NT metals.

Purpose An interorganizational learning (IOL) Web-based platform provides an ambidextrous working area, where employees can switch between exploration and exploitation-related activities. This study aims to present new indications on how to increase the acceptance and use of Web-based platforms for IOL. Specifically, it proposes how acceptance rates can be increased by focusing on the key mechanisms in Web-based platforms that are important from the users’ perspective. Design/methodology/approach Survey data were collected from employees in universities, companies, government agencies and research and technological development performers. Data analysis applies a multi-group analysis (MGA) based on the partial least squares structural equation modeling. Findings Performance expectancy is important in explorative, exploitative and ambidextrous organizations. Moreover, effort expectancy is an important driver of platform acceptance in explorative organizations, facilitating conditions in exploitative organizations and hedonic motivation in ambidextrous organizations. Originality/value This study contributes to the IOL literature by analyzing specific acceptance characteristics of potential users of a Web-based IOL platform for research and development. As the first paper published in this research context, it explicitly considers explorative, exploitative and ambidextrous organizations based on interactive and integrative interorganizational ambidexterity.

Background The use of assistive robotic systems in care is intended to relieve nursing staff. Differentiated and literature-based findings on current application possibilities, technological developments and empirical findings are necessary to enable a goal-oriented and participatory development of assistive robotic systems of care. The aim of this review was to identify assistive robotic systems and their areas of application in nursing settings. Furthermore, an overview of existing social and nursing science findings from the research field of assistive robotic systems will be described. Methods A systematic literature search was performed based on the JBI scoping review methodology. During the period from May to August 2020, the databases MEDLINE via PubMed, CINAHL, Cochrane Library, Web of Science, and IEEE Xplore Digital Library were searched. In order to reflect current developments and evidence in the present literature work, a supplementary search with these same requirements was conducted in January 2022. Results The 47 included publications are divided into 15 studies, 23 technical articles and nine opinion-based articles (text-opinion). A total of 39 different assistive robotic systems were identified. There were 55% in the testing phase and 29% of the systems in the development phase. Assistive robotic systems can be divided into six fields of application: Information and patient data processing, assistance with activities of daily living, fetch and bring activities, telepresence and communication, monitoring, safety and navigation, and complex assistance systems. The description of the study findings is divided into \"integration of technology and impact on practice\" and \"attitude and acceptance of elderly people towards assistive robotic systems\". Conclusion The results of the research show that the use of assistive robotic systems in care mainly take place in the context of development and testing phases. In addition to usability and acceptance issues, implementation factors must be integrated into theory-driven research projects.

The nervous system and the immune system both rely on an extensive set of modalities to perceive and act on perturbations in the internal and external environments. During feeding, the intestine is exposed to nutrients that may contain noxious substances and pathogens. Here we show that Vasoactive Intestinal Peptide (VIP), produced by the nervous system in response to feeding, potentiates the production of effector cytokines by intestinal type 2 and type 3 innate lymphoid cells (ILC2s and ILC3s). Exposure to VIP alone leads to modest activation of ILCs, but strongly potentiates ILCs to concomitant or subsequent activation by the inducer cytokines IL-33 or IL-23, via mobilization of cAMP and energy by glycolysis. Consequently, VIP increases resistance to intestinal infection by the helminth Trichuris muris and the enterobacteria Citrobacter rodentium. These findings uncover a functional neuro-immune crosstalk unfolding during feeding that increases the reactivity of innate immunity necessary to face potential threats associated with food intake.

The gut microbiome contributes to chronic inflammatory responses in ulcerative colitis (UC), but molecular mechanisms and disease-relevant effectors remain unclear. Here we analyze the pro-inflammatory properties of colonic fluid obtained during colonoscopy from UC and control patients. In patients with UC, we find that the pelletable effector fraction is composed mostly of bacterial extracellular vesicles (BEVs) that exhibit high IgA-levels and incite strong pro-inflammatory responses in IgA receptor-positive (CD89 + ) immune cells. Biopsy analyses reveal higher infiltration of CD89 + immune cells in the colonic mucosa from patients with UC than control individuals. Further studies show that IgA-coated BEVs, but not host-derived vesicles nor soluble IgA, are potent activators of pro-inflammatory responses in CD89 + cells. IgA-coated BEVs also exacerbate intestinal inflammation in a dextran sodium sulfate colitis model using transgenic mice expressing human CD89. Our data thus implicate a link between IgA-coated BEVs and intestinal inflammation via CD89 + immune cells, and also hint a potential new therapeutic target for UC. Gut microbiota contribute to the pathogenesis of ulcerative colitis (UC), but the molecular mechanisms are still unclear. Here the authors show that colonic fluid from patients with UC is enriched for bacteria extracellular vesicles (BEV) coated with host IgA, and that these IgA-coated BEV may activate CD89 + immune cells to aggravate inflammation and colitis in mouse models.

Burn injuries initiate numerous processes such as heat shock response, inflammation and tissue regeneration. Reliable burn models are needed to elucidate the exact sequence of local events to be able to better predict when local inflammation triggers systemic inflammatory processes. In contrast to other ex vivo skin culture approaches, we used fresh abdominal skin explants to introduce contact burn injuries. Histological and ultrastructural analyses confirmed a partial-thickness burn pathology. Gene expression patterns and cytokine production profiles of key mediators of the local inflammation, heat shock response, and tissue regeneration were analyzed for 24 h after burn injury. We found significantly increased expression of factors involved in tissue regeneration and inflammation soon after burn injury. To investigate purely inflammation-mediated reactions we injected lipopolysaccharide into the dermis. In comparison to burn injury, lipopolysaccharide injection initiated an inflammatory response while expression patterns of heat shock and tissue regeneration genes were unaffected for the duration of the experiment. This novel ex vivo human skin model is suitable to study the local, early responses to skin injuries such as burns while maintaining an intact overall tissue structure and it gives valuable insights into local mechanisms at the very beginning of the wound healing process after burn injuries.