Efficient separation of arsenic species of oxyanion As (III) and As (V) by using effective polymer inclusion membranes (PIM).

The heavy metal contaminant arsenic exist in the form of arsenite (As(III)) and arsenate (As(V)) ions. These ions are highly carcinogenic that are usually present in the ground water. To date, most of the designed polymer inclusion membrane (PIM) involved only about separation without differentiating the oxidation states. Thus, there is a research gap on separation of element with different oxidation states. Thus, this study addresses such research gap which have been not explored previously. To extract such ions from water, the present study involves fabrication of PIM by varying the compositions of the base polymer, carrier and plasticizer. Also effect of the strip solution, and transport properties were studied. High performance membrane was obtained with 50% (w/w) Aliquat 336 and 50% (w/w) Cellulose triacetate (CTA). The production of 1 m2 of PIM may cost approximately 0.08-0.16$. Also, we have combined the separation capacity of polymer inclusion membrane (PIM) with the sensitivity and elemental detection using atomic absorption spectrometry (AAS) to detect and separate As(III) and As(V). AAS is limited to detecting only elemental arsenic (As) and does not distinguish between As(III) and As(V). Further, to address such limitations in this current study we were able to separate As(V) from As(III) within 5 h. In addition, to provide sole solution a device was fabricated to extract As(V) in the field studies which displayed outstanding efficiency of 99.7 ± 0.2%. The extracted samples was tested in AAS to differentiate between oxidation states of the arsenic species and these important results are supportive in finding out the redox potential of water and for other geochemical explorations.

The evolution of safety-adjusted transportation efficiency for the road system in China.

Traffic accident is a grievous problem that costs more than one million lives worldwide every year, but remains understudied in transportation efficiency literature. This paper develops safety-adjusted transportation efficiency to account for the negative outcomes in transportation including accidents, fatalities, injuries and property loss. We model the transportation efficiency under the data envelopment analysis (DEA) framework by treating the accident-related negative outcomes as undesirable outputs. Two DEA models, based on radial and non-radial structures respectively, are proposed for panel data. We apply the methods to 31 provinces in China over a 20-year horizon 1998-2017. We find that the evolution of China's overall safety-adjusted transportation efficiency follows a U-shaped path: It deteriorated between 1998 and 2002, steadily improved from 2002 to 2012, and stabilized during 2012-2017. The majority of the provinces improved their safety-adjusted transportation efficiency from 1998 to 2017, except for one province that maintained the status quo and three provinces that experienced a decline in performance. Improvement analysis is carried out to identify gaps in accident-related factors that each province should close to attain best-practice. Further, we find strong evidence of unconditional ß-convergence and σ-convergence in safety-adjusted transportation efficiency, indicating that the provinces with low initial efficiency generally grew more rapidly and the dispersion of provincial efficiency levels diminished. The main findings are substantially different from the regular transportation efficiency analysis that does not consider the accident-related undesirable factors. The safety-adjusted transportation efficiency can convey important information that the regular transportation efficiency fails to capture.

Strategy of landfilled waste reduction by a distributed materials recovery facility system in Surabaya, Indonesia.

Slow progress in municipal waste reduction and landfill space scarcity lead to numerous environmental problems in Indonesia and developing countries. Surabaya, the role model of an environmental management city in Indonesia and other countries, is no exception. Despite the situation, Surabaya's initiative of deploying a distributed materials recovery facility (MRF) and its performance in recovering recyclables show a potential to be developed for addressing the landfill waste reduction issues. This study proposes a new strategy with small-sized distributed MRFs to achieve 30% landfilled waste reduction and reducing greenhouse gas (GHG) emissions, focusing on Surabaya as the case study. Scenario 1 merged three pairs of transfer stations which shows some indistinguishable optimizations and failed to meet the target. Both Scenario 2 and Scenario 3 added six years of landfill lifetime for reaching the target. However, the distributed MRF system and different transportation systems in Scenario 3 accomplished the goal with only 24 new MRFs, whereas Scenario 2 needs to upgrade 48 transfer stations into MRFs. Scenario 3 decreased the GHG emissions generation by 29%, possibly contributing to Indonesia's GHG emissions target of 0.2%.

Left-turning vehicle-pedestrian conflicts at signalized intersections with traffic lights: Benefit or harm? A two-stage study.

PURPOSE: Vehicle-pedestrian conflicts are common at road intersections when traffic lights change. However, the impact of traffic light on transportation safety and efficiency remains poorly understood. METHODS: A two-stage study was used to survey the proportion of intersections with conflicting traffic lights and the related transportation efficiency and safety were evaluated as well. First, a cross-sectional study estimated the proportion of signalized intersections with conflicting left-turning vehicle-pedestrian traffic lights in Changsha city, China. Second, a natural experiment compared transportation efficiency and safety between intersections with and without conflicting left-turning vehicle-pedestrian traffic lights. Risky conflicts, where motor vehicles violated laws and failed to yield to pedestrians in crosswalk were used as a surrogate for transportation safety. The number of motor vehicles and pedestrians passing through the intersections per second and per meter were used to estimate transportation efficiency. Data were collected and analyzed in 2015 (from March to December). A search of online news from domestic media sources was also conducted to collect pedestrian injury data occurring at the intersections. RESULTS: About one-fourth (57/216) intersections had conflicting left-turning traffic lights (95% CI: 20.5%, 32.3%). Risky vehicle-pedestrian conflicts were more frequently observed at intersections with conflicting lights compared to those without (incidence rate ratio (IRR) = 3.13; pedestrians: IRR = 4.02), after adjusting for type of day (weekday vs. weekend), the time period of observation, and motor vehicles traffic flow. Intersections without conflicting vehicle-pedestrian traffic lights had similar transportation efficiency to those with conflicting lights after controlling for covariates (p > 0.05). The systematic review of news media reports yielded 10 left-turning vehicle-pedestrian crash events between 2011 and 2017, involving 11 moderate or severe pedestrian injuries and 3 fatal pedestrian injuries. CONCLUSION: Over one-fourth of road intersections in Changsha city, China have conflicting left-turning traffic lights. Conflicting traffic lights cannot improve transportation efficiency, but increase risky conflicts between vehicles and pedestrians.

Left-turning vehicle-pedestrian conflicts at signalized intersections with traffic lights: Benefit or harm? A two-stage study / 中华创伤杂志(英文版)

PURPOSE@#Vehicle-pedestrian conflicts are common at road intersections when traffic lights change. However, the impact of traffic light on transportation safety and efficiency remains poorly understood.@*METHODS@#A two-stage study was used to survey the proportion of intersections with conflicting traffic lights and the related transportation efficiency and safety were evaluated as well. First, a cross-sectional study estimated the proportion of signalized intersections with conflicting left-turning vehicle-pedestrian traffic lights in Changsha city, China. Second, a natural experiment compared transportation efficiency and safety between intersections with and without conflicting left-turning vehicle-pedestrian traffic lights. Risky conflicts, where motor vehicles violated laws and failed to yield to pedestrians in crosswalk were used as a surrogate for transportation safety. The number of motor vehicles and pedestrians passing through the intersections per second and per meter were used to estimate transportation efficiency. Data were collected and analyzed in 2015 (from March to December). A search of online news from domestic media sources was also conducted to collect pedestrian injury data occurring at the intersections.@*RESULTS@#About one-fourth (57/216) intersections had conflicting left-turning traffic lights (95% CI: 20.5%, 32.3%). Risky vehicle-pedestrian conflicts were more frequently observed at intersections with conflicting lights compared to those without (incidence rate ratio (IRR) = 3.13; pedestrians: IRR = 4.02), after adjusting for type of day (weekday vs. weekend), the time period of observation, and motor vehicles traffic flow. Intersections without conflicting vehicle-pedestrian traffic lights had similar transportation efficiency to those with conflicting lights after controlling for covariates (p > 0.05). The systematic review of news media reports yielded 10 left-turning vehicle-pedestrian crash events between 2011 and 2017, involving 11 moderate or severe pedestrian injuries and 3 fatal pedestrian injuries.@*CONCLUSION@#Over one-fourth of road intersections in Changsha city, China have conflicting left-turning traffic lights. Conflicting traffic lights cannot improve transportation efficiency, but increase risky conflicts between vehicles and pedestrians.

Spatial spread of an epidemic through public transportation systems with a hub.

This article investigates an epidemic spreading among several locations through a transportation system, with a hub connecting these locations. Public transportation is not only a bridge through which infections travel from one location to another but also a place where infections occur since individuals are typically in close proximity to each other due to the limited space in these systems. A mathematical model is constructed to study the spread of an infectious disease through such systems. A variant of the next generation method is proposed and used to provide upper and lower bounds of the basic reproduction number for the model. Our investigation indicates that increasing transportation efficiency, and improving sanitation and ventilation of the public transportation system decrease the chance of an outbreak occurring. Moreover, discouraging unnecessary travel during an epidemic also decreases the chance of an outbreak. However, reducing travel by infectives while allowing susceptibles to travel may not be enough to avoid an outbreak.