Multifaceted design optimization for superomniphobic surfaces.

Superomniphobic textures are at the frontier of surface design for vast arrays of applications. Despite recent substantial advances in fabrication methods for reentrant and doubly reentrant microstructures, design optimization remains a major challenge. We overcome this in two stages. First, we develop readily generalizable computational methods to systematically survey three key wetting properties: contact angle hysteresis, critical pressure, and minimum energy wetting barrier. For each, we uncover multiple competing mechanisms, leading to the development of quantitative models and correction of inaccurate assumptions in prevailing models. Second, we combine these analyses simultaneously, demonstrating the power of this strategy by optimizing structures that are designed to overcome challenges in two emerging applications: membrane distillation and digital microfluidics. As the wetting properties are antagonistically coupled, this multifaceted approach is essential for optimal design. When large surveys are impractical, we show that genetic algorithms enable efficient optimization, offering speedups of up to 10,000 times.

The impact of surface geometry, cavitation, and condensation on wetting transitions: posts and reentrant structures.

The fundamental impacts of surface geometry on the stability of wetting states, and the transitions between them are elucidated for square posts and reentrant structures in three dimensions. We identify three principal outcomes of particular importance for future surface design of liquid-repellent surfaces. Firstly, we demonstrate and quantify how capillary condensation and vapour cavitation affect wetting state stabilities. At high contact angles, cavitation is enhanced about wide, closely-spaced square posts, leading to the existence of suspended states without an associated collapsed state. At low contact angles, narrow reentrant pillars suppress condensation and enable the suspension of even highly wetting liquids. Secondly, two distinct collapse mechanisms are observed for 3D reentrant geometries, base contact and pillar contact, which are operative at different pillar heights. As well as morphological differences in the interface of the penetrating liquid, each mechanism is affected differently by changes in the contact angle with the solid. Finally, for highly-wetting liquids, condensates are shown to critically modify the transition pathways in both the base contact and pillar contact modes.

Causal pathways linking environmental change with health behaviour change: Natural experimental study of new transport infrastructure and cycling to work.

BACKGROUND: Mechanisms linking changes to the environment with changes in physical activity are poorly understood. Insights into mechanisms of interventions can help strengthen causal attribution and improve understanding of divergent response patterns. We examined the causal pathways linking exposure to new transport infrastructure with changes in cycling to work. METHODS: We used baseline (2009) and follow-up (2012) data (N=469) from the Commuting and Health in Cambridge natural experimental study (Cambridge, UK). Exposure to new infrastructure in the form of the Cambridgeshire Guided Busway was defined using residential proximity. Mediators studied were changes in perceptions of the route to work, theory of planned behaviour constructs and self-reported use of the new infrastructure. Outcomes were modelled as an increase, decrease or no change in weekly cycle commuting time. We used regression analyses to identify combinations of mediators forming potential pathways between exposure and outcome. We then tested these pathways in a path model and stratified analyses by baseline level of active commuting. RESULTS: We identified changes in perceptions of the route to work, and use of the cycle path, as potential mediators. Of these potential mediators, only use of the path significantly explained (85%) the effect of the infrastructure in increasing cycling. Path use also explained a decrease in cycling among more active commuters. CONCLUSION: The findings strengthen the causal argument that changing the environment led to changes in health-related behaviour via use of the new infrastructure, but also show how some commuters may have spent less time cycling as a result.

Family-based interventions to increase physical activity in children: a systematic review, meta-analysis and realist synthesis.

OBJECTIVE: Family-based interventions represent a potentially valuable route to increasing child physical activity (PA) in children. A dual meta-analysis and realist synthesis approach examined existing interventions to assist those developing programmes to encourage uptake and maintenance of PA in children. DESIGN: Studies were screened for inclusion based on including participants aged 5-12 years, having a substantive aim of increasing PA by engaging the family and reporting on PA outcome. Duplicate data extraction and quality assessment were conducted. Meta-analysis was conducted in STATA. Realist synthesis included theory development and evidence mapping. RESULTS: Forty-seven studies were included, of which three received a 'strong' quality rating, 21 'moderate' and 23 'weak'. The meta-analysis (19 studies) demonstrated a significant small effect in favour of the experimental group (standardized mean difference: 0.41; 95%CI 0.15-0.67). Sensitivity analysis, removing one outlier, reduced this to 0.29 (95%CI 0.14-0.45). Realist synthesis (28 studies) provided insight into intervention context (particularly, family constraints, ethnicity and parental motivation), and strategies to change PA (notably, goal-setting and reinforcement combined). CONCLUSION: This review provides key recommendations to inform policy makers and other practitioners in developing evidence-based interventions aimed at engaging the family to increase PA in children, and identifies avenues for future research.

A longitudinal study of the distance that young people walk to school.

Walking or cycling to school has been associated with important health benefits. Distance between home and school is the main correlate of active commuting to school, but how far children walk to school and how this changes as children age is unknown. Mode of commuting and objectively-assessed distance to school were measured at 3 time points: aged 9/10 years, 10/11 years and 13/14 years. Data were analysed using ROC-curve analyses. With age, children walked further to school; the threshold distance that best discriminated walkers from passive commuters was 1421 m in 10-year-olds, 1627 m in 11-year-olds and 3046 m in 14-year-olds. Future interventions should consider the distance that young people actually walk.

Towards a differentiated understanding of active travel behaviour: using social theory to explore everyday commuting.

Fostering physical activity is an established public health priority for the primary prevention of a variety of chronic diseases. One promising population approach is to seek to embed physical activity in everyday lives by promoting walking and cycling to and from work ('active commuting') as an alternative to driving. Predominantly quantitative epidemiological studies have investigated travel behaviours, their determinants and how they may be changed towards more active choices. This study aimed to depart from narrow behavioural approaches to travel and investigate the social context of commuting with qualitative social research methods. Within a social practice theory framework, we explored how people describe their commuting experiences and make commuting decisions, and how travel behaviour is embedded in and shaped by commuters' complex social worlds. Forty-nine semi-structured interviews and eighteen photo-elicitation interviews with accompanying field notes were conducted with a subset of the Commuting and Health in Cambridge study cohort, based in the UK. The findings are discussed in terms of three particularly pertinent facets of the commuting experience. Firstly, choice and decisions are shaped by the constantly changing and fluid nature of commuters' social worlds. Secondly, participants express ambiguities in relation to their reasoning, ambitions and identities as commuters. Finally, commuting needs to be understood as an embodied and emotional practice. With this in mind, we suggest that everyday decision-making in commuting requires the tactical negotiation of these complexities. This study can help to explain the limitations of more quantitative and static models and frameworks in predicting travel behaviour and identify future research directions.

Attitudes, social support and environmental perceptions as predictors of active commuting behaviour in school children.

BACKGROUND: Environmental perceptions appear to play a role in determining behaviour in children, although their influence on active commuting remains unclear. This study examines whether attitudes, social support and environmental perceptions are associated with active commuting behaviour in school children and whether these associations are moderated by the distance to school. METHODS: Data were collected as part of the SPEEDY study (Sport, Physical activity and Eating behaviour: Environmental Determinants in Young people), a cross-sectional study of 2064 children from schools in Norfolk, UK. Data regarding the usual mode of travel to school, attitudes towards and social support for active commuting, perceptions of the neighbourhood and route to school were assessed using questionnaires completed by 2012 children and their parents. Distance to school was estimated using a Geographic Information System and this was used to compare associations between personal and environmental factors and active travel, across different distance categories. RESULTS: Forty per cent of children reported usually walking to school, with 9% cycling and the remainder using motorised travel. Parental attitudes and safety concerns, the presence of social support from parents and friends and parent-reported neighbourhood walkability were all found to be predictors of active commuting, with children receiving peer and family support and living in supportive environments being more likely to walk or cycle. There was some evidence of a moderating effect of distance whereby attitudes were more important for short distances and safety concerns long. CONCLUSION: Both attitudinal and environmental perceptions are associated with children's active commuting behaviours. Given the difficulty in modifying attitudes directly, the effect on them of interventions to provide more supportive environments should be evaluated.

The relationship between access and quality of urban green space with population physical activity.

OBJECTIVES: This study examined the association between access to quality urban green space and levels of physical activity. STUDY DESIGN: A cross-sectional examination of the relationship between access to quality urban green space and level of recreational physical activity in 4950 middle-aged (40-70 years) respondents from the European Prospective Investigation into Cancer and Nutrition (EPIC), who resided in Norwich, UK. METHODS: Using geographic information systems (GIS), three measures of access to open green space were calculated based on distance only, distance and size of green space and distance, size and quality of green space. Multiple regression models were used to determine the relationship between the three indicators of access to open green space and level of recreational physical activity. RESULTS: There was no evidence of clear relationships between recreational activity and access to green spaces. Non-significant associations were apparent for all variables, and there was no evidence of a clear trend in regression coefficients across quartiles of access for either the distance, size adjusted, and quality and size-adjusted models. Furthermore, the neighbourhood measures of access to green spaces showed non-significant associations with recreational physical activity. CONCLUSIONS: Access to urban green spaces does not appear to be associated with population levels of recreational physical activity in our sample of middle-aged adults.

Stability of toluene in blood: its forensic relevance.

Toluene is the chemical most frequently present in cases involving volatile solvents. Therefore, its stability is of prime forensic significance. Losses of toluene in three different blood standards stored at 24 degrees, 4 degrees, and -18 degrees C were studied at intervals of one, two, and seven weeks, and 34 and 46 months. The results were compared with previously published studies, and guidelines for the significant forensic analysis of toluene in blood are suggested. As previously cited, studies show that an accurate estimate of the initial toluene concentration is not possible, but its presence can be documented with an ion trap detector after 46 months if the initial concentration was above 0.04 mg/dL, even in specimens stored at 4 degrees C in a Vacutainer (90% filled) without preservative. If the specimen is collected in a Vacutainer at approximately 90% capacity and stored at 24 degrees C or below, up to 25% loss of toluene after one week can be expected.

Complex formation between naphthothiopheneethanolamines and deoxyribonucleic acids.

Reduced viscosities, viscometric titrations, fluorescence, and flow dichroism measurements indicate that the aromatic ring system of naphthothiopheneethanolamines (NA) is intercalated on binding to DNA. No marked change in binding was found on substituting a dibutylamino group for a piperidyl ring on the side chain. Ionic strength studies, however, did indicate that the positive charge on the side chain is quite important for binding. Both the binding equilibrium constant and the number of binding sites, as determined from a Scatchard plot of spectrophotometric results, decreased on increasing the sodium chloride concentration. The increase in Tm for several DNA samples, caused by adding NA to DNA at a fixed ratio, showed a marked dependence on the percentage of AT base pairs. The conclusion drawn from these data is that the DNA-NA complex involves high specificity of the NA for AT base pairs, intercalation of the aromatic ring system, and binding of the NA side chain in the DNA minor groove with strong interaction between the positively charged side chain and the DNA phosphate groups.