Measurement of CO2 in Water from an Ultraviolet Oxidizer for a Space-Worthy Wastewater Recovery System Using Raman Spectroscopy.

NASA has been developing and testing a water recovery system for over two decades to minimize the amount of water required for long duration human space missions. A key system component is the total organic carbon analyzer (TOCA) that determines if the recovered water is below the toxicology-defined health limit of 5 mg/L TOC and is safe to drink. The TOCA is composed of a liquid phase loop and a gas phase loop. The TOCA employs an oxidizer to convert the organics in the liquid phase to carbon dioxide (CO2) and a liquid-gas separator to isolate the CO2 for measurement in the gas phase by infrared spectroscopy. In an effort to reduce the consumables, mass, volume, and power of the system, we investigated the ability of surface-enhanced Raman spectroscopy (SERS), and Raman spectroscopy to measure 5 mg/L carbon in water. The SERS measurement employed silver colloids to increase sensitivity, while the Raman measurements used multiple mirrors to increase sensitivity. Here, we present SERS measurements of carbonate (CO3=) at 3 mg/L carbon and Raman measurements of CO2 at 9 mg/L carbon in the effluent water of a new oxidizer being developed for a future TOCA. Both SERS and Raman techniques can determine TOC in the liquid phase, eliminating the need for the gas phase loop and associated supplies and replacement components, which could effectively decrease the size and weight of the current TOCA by as much as 50%.

Higher risk of auto versus pedestrian crashes in school-age children on school days.

BACKGROUND: This study examines the rates of pediatric auto versus pedestrian collision (APCs) and determined ages and periods of greatest risk. We hypothesized that the rate of APC in children would be higher on school days and in the timeframes correlating with travel to and from school. METHODS: Retrospective case-control study of APC on school and nonschool days for patients younger than 18 years at an urban Level II pediatric trauma center from January 2011 to November 2019. Frequency of APC by hour of the day was plotted overall, for school versus nonschool days and for age groups: 0 year to 4 years, 5 years to 9 years, 10 years to 13 years, and 14 years to 17 years. t Test was used with a p value less than 0.05, which was considered significant. RESULTS: There were 441 pediatric APC in the study period. Frequency of all APC was greater on school days (0.174 vs. 0.101; relative risk [RR], 1.72, p < 0.001), and APC with Injury Severity Score greater than 15 (0.039 vs. 0.024; p = 0.014; RR, 1.67; 95% confidence interval, 1.10-2.56). Comparing school day with nonschool day, the 0-year to 4-year group had no significant difference in APC frequency (0.021 vs. 0.014; p = 0.129), APC frequency was higher on school days in all other age groups: 5 years to 9 years (0.036 vs. 0.019; RR, 1.89; p = 0.0134), 10 years to 13 years (0.055 vs. 0.024; RR, 2.29; p < 0.001), and 14 years to 17 years (0.061 vs. 0.044; RR, 1.39; p = 0.045). The greatest increase in APC on school days was in the 10-year to 13-year age group. DISCUSSION: All school age children are at higher risk of APC on school days. The data support our hypothesis that children are at higher risk of APC during transit to and from school. The age 10-year to 13-year group had a 129% increase in APC frequency on school days. This age group should be a focus of injury prevention efforts. LEVEL OF EVIDENCE: Prognostic and Epidemiologic; Level IV.