Kinetic modelling for photosynthesis of hydrogen and Methane through catalytic reduction of carbon dioxide with water vapour

In a photocatalytic reduction process when products formed are not effectively desorbed, they could hinder the diffusion of intermediates on the surface of the catalyst, as well as increase the chance of collisions among the products, resulting photo-oxidation in a reserve reaction on the surface. This paper analyses a simple kinetic model incorporating the coupled effect of the adsorptive photocatalytic reduction and oxidation. The development is based on Langmuir–Hinshelwood mechanism to model the formation rates of hydrogen and methane through photocatalytic reduction of carbon dioxide with water vapour. Experimental data obtained from literatures have achieved a very good fit. Such model could aid as a tool for related areas of studies. A comparative study using the model developed, showed that product concentration in term of ppm would be an effective measurement of product yields through photocatalytic reduction of carbon dioxide with water vapour.

Promoting transportation cycling for women : the role of bicycle infrastructure

Objective.
Females are substantially less likely than males to cycle for transport in countries with low bicycle transport mode share. We investigated whether female commuter cyclists were more likely to use bicycle routes that provide separation from motor vehicle traffic.
Methods.
Census of cyclists observed at 15 locations (including off-road bicycle paths, on-road lanes and roads with no bicycle facilities) within a 7.4 km radius of the central business district (CBD) of Melbourne, Australia, during peak commuting times in February 2004.
Results.
6589 cyclists were observed, comprising 5229 males (79.4%) and 1360 females (20.6%). After adjustment for distance of the bicycle facility from the CBD, females showed a preference for using off-road paths rather than roads with no bicycle facilities (odds ratio [OR] = 1.43, 95% confidence interval [CI]: 1.12, 1.83), or roads with on-road bicycle lanes (OR = 1.34, 95% CI: 1.03, 1.75).
Conclusions.
Consistent with gender differences in risk aversion, female commuter cyclists preferred to use routes with maximum separation from motorized traffic. Improved cycling infrastructure in the form of bicycle paths and lanes that provide a high degree of separation from motor traffic is likely to be important for increasing transportation cycling amongst under-represented population groups such as women.

Area variation in recreational cycling in Melbourne : a compositional or contextual effect?

Objective: To examine whether compositional and/or contextual area characteristics are associated with area socioeconomic inequalities and between-area differences in recreational cycling.

Setting: The city of Melbourne, Australia.

Participants: 2349 men and women residing in 50 areas (58.7% response rate).

Main outcome measure: Cycling for recreational purposes (at least once a month vs never).

Design: In a cross-sectional survey participants reported their frequency of recreational cycling. Objective area characteristics were collected for their residential area by environmental audits or calculated with Geographic Information Systems software. Multilevel logistic regression models were performed to examine associations between recreational cycling, area socioeconomic level, compositional characteristics (age, sex, education, occupation) and area characteristics (design, safety, destinations or aesthetics).

Results: After adjustment for compositional characteristics, residents of deprived areas were less likely to cycle for recreation (OR 0.66; 95% CI 0.43 to 1.00), and significant between-area differences in recreational cycling were found (median odds ratio 1.48 (95% credibility interval 1.24 to 1.78). Aesthetic characteristics tended to be worse in deprived areas and were the only group of area characteristics that explained some of the area deprivation differences. Safety characteristics explained the largest proportion of between-area variation in recreational cycling.

Conclusion: Creating supportive environments with respect to safety and aesthetic area characteristics may decrease between-area differences and area deprivation inequalities in recreational cycling, respectively.

Walking and cycling to school : predictors of increases among children and adolescents

Background
Little is known about what happens to active commuting as children get older, and less is known about influences on changes in this behavior. This study examined predictors of increases in children's and adolescents' active commuting (walking or cycling) to/from school over a 2-year period.
Methods
Participants were initially recruited and assessed in 2001. Follow-up data were collected in 2004 and 2006 and analyzed in 2008. Participants were 121 children (aged 9.1±0.34 years in 2004) and 188 adolescents (aged 14.5±0.65 years in 2004) from Melbourne, Australia. Parents and adolescents reported their perceptions of individual-level factors and of the neighborhood social and physical environment. Weekly active commuting (walking or cycling) to/from school, ranging from 0 to 10 trips/week was also proxy- or self-reported at the initial measurement and again 2 years later. Logistic regression analyses examined predictors of increases in active commuting over time.
Results
Children whose parents knew many people in their neighborhood were more likely to increase their active commuting (OR=2.6; CI=1.2, 5.9; p=0.02) compared with other children. Adolescents whose parents perceived there to be insufficient traffic lights and pedestrian crossings in their neighborhood were less likely to increase their active commuting over 2 years (OR=0.4; CI=0.2, 0.8; p=0.01), whereas adolescents of parents who were satisfied with the number of pedestrian crossings were more likely to increase their active commuting (OR=2.4; CI=1.1, 5.4; p=0.03) compared with other adolescents.
Conclusions
Social factors and physical environmental characteristics were the most important predictors of active commuting in children and adolescents, respectively.

Effect of posture on high-intensity constant-load cycling performance in men and women

The time sustained during a graded cycle exercise is ~10% longer in an upright compared with a supine posture. However, during constant-load cycling this effect is unknown. Therefore, we tested the postural effect on the performance of high-intensity constant-load cycling. Twenty-two active subjects (11 men, 11 women) performed two graded tests (one upright, one supine), and of those 22, 10 subjects (5 men, 5 women) performed three high-intensity constant-load tests (one upright, two supine). To test the postural effect on performance at the same absolute intensity, during the upright and one of the supine constant-load tests subjects cycled at 80% of the peak power output achieved during the upright graded test. To test the postural effect on performance at the same relative intensities, during the second supine test subjects cycled at 80% of the peak power output achieved during the supine graded test. Exercise time on the graded and absolute intensity constant-load tests for all subjects was greater (P<0.05) in the upright compared with supine posture (17.9±3.5 vs. 16.1±3.1 min for graded; 13.2±8.7 vs. 5.2±1.9 min for constant-load). This postural effect at the same absolute intensity was larger in men (19.4±8.5 upright vs. 6.6±1.6 supine, P<0.001) than women (7.1±2 upright vs. 3.9±1.4 supine, P>0.05) and it was correlated (P<0.05) with both the difference in VO₂ between positions during the first minute of exercise (r=0.67) and the height of the subjects (r=0.72). In conclusion, there is a very large postural effect on performance during constant-load cycling exercise and this effect is significantly larger in men than women.