In Nature, directional surfaces on insect cuticle, animal fur, bird feathers, and plant leaves are composed of dual micro‐nanoscale features that tune roughness and surface energy. Here, experimental ...and theoretical approaches for the design, synthesis, and characterization of new bioinspired surfaces demonstrating unidirectional surface properties are summarized. The experimental approaches focus on bottom‐up and top‐down synthesis methods of unidirectional micro‐ and nanoscale films to explore and characterize their anomalous features. The theoretical component focuses on computational tools to predict the physicochemical properties of unidirectional surfaces.
Recent developments in the area of bioinspired directional surfaces with precisely tuned physicochemical surface properties are summarized. These surfaces, characterized by asymmetric features, can transport droplets, provide directional wet and dry adhesion, and exhibit directional friction.
ObjectiveThe efficacious Activate injury prevention exercise programme has been shown to prevent injuries in English schoolboy rugby union. There is now a need to assess the implementation and ...effectiveness of Activate in the applie setting.MethodsThis quasi-experimental study used a 24-hour time-loss injury definition to calculate incidence (/1000 hours) and burden (days lost/1000 hours) for individuals whose teams adopted Activate (used Activate during season) versus non-adopters. The dose-response relationship of varying levels of Activate adherence (median Activate sessions per week) was also assessed. Player-level rugby exposure, sessional Activate adoption and injury reports were recorded by school gatekeepers. Rate ratios (RR), adjusted by cluster (team), were calculated using backwards stepwise Poisson regression to compare rates between adoption and adherence groups.ResultsIndividuals in teams adopting Activate had a 23% lower match injury incidence (RR 0.77, 95% CI 0.55 to 1.07), 59% lower training injury incidence (RR 0.41, 95% CI 0.17 to 0.97) and 26% lower match injury burden (95% CI 0.46 to 1.20) than individuals on non-adopting teams. Individuals with high Activate adherence (≥3 sessions per week) had a 67% lower training injury incidence (RR 0.33, 95% CI 0.12 to 0.91) and a 32% lower match injury incidence (RR 0.68, 95% CI 0.50 to 0.92) than individuals with low adherence (<1 session per week). While 65% of teams adopted Activate during the season, only one team used Activate three times per week, using whole phases and programme progressions.Conclusion Activate is effective at preventing injury in English schoolboy rugby. Attention should focus on factors influencing programme uptake and implementation, ensuring Activate can have maximal benefit.
Developing biologically relevant models of human tissues and organs is an important enabling step for disease modeling and drug discovery. Recent advances in tissue engineering, biomaterials and ...microfluidics have led to the development of microscale functional units of such models also referred to as ‘organs on a chip’. In this review, we provide an overview of key enabling technologies and highlight the wealth of recent work regarding on-chip tissue models. In addition, we discuss the current challenges and future directions of organ-on-chip development.
Anisotropic textured surfaces allow water striders to walk on water, butterflies to shed water from their wings and plants to trap insects and pollen. Capturing these natural features in biomimetic ...surfaces is an active area of research. Here, we report an engineered nanofilm, composed of an array of poly(p-xylylene) nanorods, which demonstrates anisotropic wetting behaviour by means of a pin-release droplet ratchet mechanism. Droplet retention forces in the pin and release directions differ by up to 80 μN, which is over ten times greater than the values reported for other engineered anisotropic surfaces. The nanofilm provides a microscale smooth surface on which to transport microlitre droplets, and is also relatively easy to synthesize by a bottom-up vapour-phase technique. An accompanying comprehensive model successfully describes the film's anisotropic wetting behaviour as a function of measurable film morphology parameters.
Changes in fertility patterns are hypothesized to be among the many second-order consequences of armed conflict, but expectations about the direction of such effects are theoretically ambiguous. ...Prior research, from a range of contexts, has also yielded inconsistent results. We contribute to this debate by using harmonized data and methods to examine the effects of exposure to conflict on preferred and observed fertility outcomes across a spatially and temporally extensive population. We use high-resolution georeferenced data from 25 sub-Saharan African countries, combining records of violent events from the Armed Conflict Location and Event Data Project (ACLED) with data on fertility goals and outcomes from the Demographic and Health Surveys (n = 368,765 women aged 15–49 years). We estimate a series of linear and logistic regression models to assess the effects of exposure to conflict events on ideal family size and the probability of childbearing within the 12 months prior to the interview. We find that, on average, exposure to armed conflict leads to modest reductions in both respondents’ preferred family size and their probability of recent childbearing. Many of these effects are heterogeneous between demographic groups and across contexts, which suggests systematic differences in women’s vulnerability or preferred responses to armed conflict. Additional analyses suggest that conflict-related fertility declines may be driven by delays or reductions in marriage. These results contribute new evidence about the demographic effects of conflict and their underlying mechanisms, and broadly underline the importance of studying the second-order effects of organized violence on vulnerable populations.
Biomimetic gradient hydrogels for tissue engineering Sant, Shilpa; Hancock, Matthew J.; Donnelly, Joseph P. ...
Canadian journal of chemical engineering,
December 2010, Letnik:
88, Številka:
6
Journal Article
ObjectiveTo report match incidence, severity and burden of match concussions in multiple levels of rugby union in England using consistent consensus methods.DesignProspective cohort ...studies.SettingRugby teams in England (2017–18 and 2018–19 seasons).ParticipantsPlayers from 13 elite men’s teams, 10 elite women’s teams, 8 university men’s teams, 91 community men’s teams, 53 schoolboy teams.Assessment of Risk FactorsLevel of play.Outcome MeasuresConcussion incidence (/1000 h), proportion of all time-loss injuries that are concussion (%), days absence from rugby following concussion (days), and burden of concussion (incidence x days absence; days/1000 h).Main ResultsConcussion incidence, proportion of all injuries, mean severity and burden (95%CIs) were: Elite Men, 19.2/1000 h (17.2–21.5), 20%, 21 days (19–24), 397 days/1000 h (355–444); Elite Women, 6.7/1000 h (4.9–9.2), 19%, 50 days (32–67), 334 days/1000 h (245–455); University Men, 15.2/1000 h (12.1–18.3), 21%, 26 days (21–32), 401 days/1000 h (319–484); Community Men, 4.0/1000 h (3.4–4.6), 16%, 27 days (23–31), 108 days/1000 h (92–123); Schoolboy, 7.9/1000 h (6.4–9.7), 24%, 25 days (22–34), 233 days/1000 h (190–287).ConclusionsConcussion is the most common match injury at all levels of rugby union in England, accounting for between 16 and 24% of match injuries. The incidence and burden of concussion requires greater focus, with specific priority at elite men’s, university men’s and schoolboy levels. Further work is needed to explore the high severity of concussion in the elite women’s game.
Cerium atoms on the surfaces of nanoceria (i.e., cerium oxide in the form of nanoparticles) can store or release oxygen, cycling between Ce
and Ce
; therefore, they can cause or relieve oxidative ...stress within living systems. Nanoceria dissolution occurs in acidic environments. Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, namely citric acid, is used in many synthesis protocols. Citric acid adsorbs onto nanoceria surfaces, limiting particle formation and creating stable dispersions with extended shelf life. To better understand factors influencing the fate of nanoceria, its dissolution and stabilization have been previously studied in vitro using acidic aqueous environments. Nanoceria agglomerated in the presence of some carboxylic acids over 30 weeks, and degraded in others, at pH 4.5 (i.e., the pH value in phagolysosomes). Plants release carboxylic acids, and cerium carboxylates are found in underground and aerial plant parts. To further test nanoceria stability, suspensions were exposed to light and dark conditions, simulating plant environments and biological systems. Light induced nanoceria agglomeration in the presence of some carboxylic acids. Nanoceria agglomeration did not occur in the dark in the presence of most carboxylic acids. Light initiates free radicals generated by ceria nanoparticles. Nanoceria completely dissolved in the presence of citric, malic, and isocitric acid when exposed to light, attributed to nanoceria dissolution, release of Ce
ions, and formation of cerium coordination complexes on the ceria nanoparticle surface that inhibit agglomeration. Key functional groups of carboxylic acids that prevented nanoceria agglomeration were identified. A long carbon chain backbone containing a carboxylic acid group geminal to a hydroxy group in addition to a second carboxylic acid group may optimally complex with nanoceria. The results provide mechanistic insight into the role of carboxylic acids in nanoceria dissolution and its fate in soils, plants, and biological systems.
Cell‐laden hydrogels show great promise for creating engineered tissues. However, a major shortcoming with these systems has been the inability to fabricate structures with controlled ...micrometer‐scale features on a biologically relevant length scale. In this Full Paper, a rapid method is demonstrated for creating centimeter‐scale, cell‐laden hydrogels through the assembly of shape‐controlled microgels or a liquid–air interface. Cell‐laden microgels of specific shapes are randomly placed on the surface of a high‐density, hydrophobic solution, induced to aggregate and then crosslinked into macroscale tissue‐like structures. The resulting assemblies are cell‐laden hydrogel sheets consisting of tightly packed, ordered microgel units. In addition, a hierarchical approach creates complex multigel building blocks, which are then assembled into tissues with precise spatial control over the cell distribution. The results demonstrate that forces at an air–liquid interface can be used to self‐assemble spatially controllable, cocultured tissue‐like structures.
Centimeter‐scale cell‐laden hydrogel sheets are created by the directed assembly of shape‐controlled microgels followed by UV polymerization. A hierarchical assembly technique creates complex multigel building blocks, which are then assembled into gel sheets with precise spatial control over the cell distribution.
Rugby Union is team-based collision sport with increasing global popularity, particularly in the women's game. Despite this, there is currently no evidence demonstrating the frequency of match events ...outside of the international game. Therefore, the aim of this study is to outline the frequency and distribution of match events in non-international female rugby union to both outline the demands placed on players and to assess the patterns of play for future injury prevention strategies. Forty-eight games from three seasons of varsity rugby were coded and rates of events per match were calculated. Average ball in play percentage was 51%. The tackle was the most frequent contact match event 280.0 (95% CIs: 270.2-289.7) while passes were the most frequent non-contact match events 323.2 (95% CIs: 311.8-334.5). The distribution of events across match quarter was largely consistent and neither the fixture type, nor the season was consistently associated with differences in match event count per game. This study provides the first analysis of match events outside of international game and provides a useful reference for coaches in preparation of players as well as comparable data for the women's game when informing decision making on injury prevention.
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