Development of bio-based materials with advanced properties is required to replace synthetic and per-and polyfluoroalkyl-based ingredients, particularly for applications involving solid-liquid-gas interfaces. To enable alkaline-resistant materials with tunable aerophobicity, bio-based chitosan/dialdehyde starch hydrogels were prepared through covalent Schiff base crosslinking. Chitosan molecular weight (250-1800 kDa) and concentration (1.5-4.0% w/v) were varied at fixed crosslinker content (1.0% w/v) to investigate the effect on network formation, viscoelasticity and functionality. Rheological analysis shows that systems with low chitosan content require long gelation times (>30 min) to form viscous materials with storage moduli of 1 Pa and internal porous structure (10-100 mu m). In contrast, highly concentrated chitosan gels formed rapidly (<4 min) reaching up to 150 Pa, indicating improved structural strength. Swelling experiments on freeze-dried hydrogels at pH 6.8, 10, and 12 showed water absorption with swelling ratios ranging from 5000 to 1300%, depending on composition. Most systems maintained structural stability over the 7-day swelling test, undergoing limited degradation in alkaline conditions (pH 12). Aerophobicity was evaluated by measuring contact angles of bubbles on submersed (in water or pH 12) hydrogels, which range from 130 to 170 degrees, increasing with both chitosan concentration and molecular weight. The material features were demonstrated for electrode development, improving performance at higher overpotentials (-0.67 V) and increasing alkaline water-splitting efficiency by 15%. The prepared materials thus provide alkaline resistance and tunable properties offering potential for various applications, including gas-evolving electrode coatings, alkaline electrolyzer membranes, anti-corrosion coatings, pollutant absorption, environmental remediation, and sensing technologies.
Autonomous Delivery Vehicles (ADVs) and Shared Delivery Locations (SDLs) provide alternative service options for urban last-mile logistics, but their effectiveness depends on customer acceptance and network design. To capture these features, we formulate the Time-Dependent Heterogeneous Vehicle Routing Problem with Delivery Options (TD-HVRPDO), which jointly models autonomous and manned fleets, home and SDL delivery modes, customer-specific acceptance constraints, and time-dependent travel times under urban congestion. The model jointly determines delivery mode, vehicle type, and routing decisions while accounting for the consolidation opportunities provided by shared delivery locations. We develop a hybrid matheuristic integrating Column Generation, Large Neighborhood Search, and Route-based Search. Computational experiments show that the proposed method produces high-quality solutions more efficiently than a commercial solver and adapted benchmark methods. Managerial analyses show that both ADVs and SDLs can reduce the costs, with SDLs yielding larger savings through delivery consolidation. However, the extent of these consolidation benefits depends strongly on SDL placement. Moreover, joint deployment can provide further savings while reducing reliance on manned vehicles. These findings therefore suggest that operators should coordinate investment in additional ADVs with SDL network design and efforts to broaden customer acceptance.
Monopisthocotylan parasites have been proposed as tags for studying host population structure due to their direct life cycles and short generation times. However, their effectiveness in reflecting host population connectivity remains under scrutiny. The poorly-understood connectivity of fisheries stocks in Lake Tanganyika, the second deepest lake in the world with a permanently stratified, relatively species-poor and well-delimited pelagic zone, serves as a case-study to test utility of parasites for fish stock identification. This study investigates the population structure of two Kapentagyrus species parasitizing dorosomatid fish in Lake Tanganyika, by analyzing variation in mitochondrial protein-coding genes across a geographic gradient. The study comprised 12 population genomic datasets from the central and southern subbasins of the lake sampled within the same week to account for host migration. We observed differences in geographic population structure of the two parasite species, with restricted gene flow in Kapentagyrus limnotrissae infecting a single dorosomatid species and smaller hosts preferring the littoral zone. Conversely, K. tanganicanus exhibited no geographical structure, reflecting its broader host range and preference for larger hosts preferring the pelagic zone. The results also highlight that other mitochondrial genes such as those from the dehydrogenase family or atp6 provide higher resolution for population genetic studies in these parasites than the frequently used cox1. The study also compared two sequencing strategies—individual versus pooled sequencing (PoolSeq)—for assessing population structure of monopisthocotylan parasites, and found that PoolSeq yielded similar results with lower demands on individual DNA quantity and sequencing costs. This work supports the use of host-specific, directly transmitted parasites as ecosystem tags and provides valuable insights into the role of host ecology and parasite life-history traits in shaping population dynamics.
Pedestrians are amongst the most vulnerable road user groups. Efforts to enhance pedestrian safety have mainly focused on intersections and midblock crossings. This study investigated the effect of bus stop environments on pedestrian safety in Kumasi, an area with a high incidence of pedestrian fatalities in Ghana. Crashes within a 50 m radius of bus stops were extracted using a spatial join. The Negative Binomial regression model was applied to model pedestrian crashes around bus stops as a function of three distinct non-collinear independent variable groups: road design features, bus stop characteristics, and pedestrian exposure measures. Formal bus stops were associated with higher crash rates than informal ones. The presence of medians and crosswalks was associated with lower crash rates, whereas wider carriageways were associated with higher crash rates. Higher crashes were linked to passing pedestrians and waiting pedestrians, while crossing pedestrians were associated with reduced crashes. These findings suggest that the combined effects of infrastructure and behavioural factors influence pedestrian safety at bus stops. Prioritising low-cost safety treatments, such as guard-railed waiting areas, marked crosswalks, medians, and raised crossings, around bus stops will yield substantial safety benefits for resource-constrained contexts and advance sustainable urban mobility.
Social media have substantially changed the opportunities for political engagement, both in how citizens become informed and learn about politics, as well as in their political participation. On the one hand, citizens can encounter a large diversity of political content on these platforms, both in terms of format and topic. On the other hand, social media are increasingly used by citizens to express their views and mobilize others in highly personalized ways. While social media seem to hold unique opportunities for political learning and participation, it remains unclear how these processes might be linked to each other. Therefore, following communication mediation theory, we explore whether and how political knowledge about current affairs might mediate the association between exposure to political content on social media and participation on these same platforms. Data from a cross-sectional study in Flanders, Belgium (n = 2,520), reveal a complex participatory cycle. While citizens do seem to learn from social media political content, those who are more knowledgeable engage less in social media political participation. While unexpected, these findings highlight the importance of considering the unique social media affordances when researching political socialization and participation.
