The determination of gasoline and alkyl benzenes in aqueous solution and the development of a remote reaction chamber for fiber optic remote sensing

The development and optimization of a single-phase derivatization technique for small ring aromatics in water are presented. Also described are the design, optimization and application of a remote reaction chamber for fiber optic sensing. Aqueous solutions of the major aromatic compounds in gasoline are derivatized to o-nitrosophenol-Cu complexes with a modified Baudisch reaction. The rate of formation of the complex is spectrophotometrically monitored at 310 nm and related to the concentration of benzene and alkyl benzenes present. The measured rate for aqueous gasoline samples is then related to gasoline concentration by estimating the relative aromatic composition of the gasoline sample. The technique provides a detection limit (DL) of 4 x 10⁻⁵ % (v/v) and 4 x 10⁻⁴ % (v/v) for benzene and gasoline, respectively. The response is linear to 0.01% (v/v) for benzene and 0.005% (v/v) for gasoline. The technique was successfully applied as a bench top method for detecting gasoline and alkyl benzenes, but due to the loss in reactivity of the reagents once mixed, the methodology was not suited for remote sensing applications. A remote reaction chamber (RRC) optrode was developed to facilitate in situ monitoring using derivatization techniques to form a luminescent product. The RRC optrode is a submergible chamber into which excitation radiation is input with one optical fiber and emission radiation is collected and directed to a photodetection system with another optical fiber. The RRC optrode allows for the isolation of a sample by applying a vacuum to a one-way exhaust valve. When the vacuum is applied the sample enters through a one-way intake valve and partially fills the internal chamber. After the vacuum is terminated, up to three reagents are injected with automated syringes through injection lines. Mixing of the sample and injected reagents is accomplished with a miniature stir driver and stir bar contained in the RRC optrode. The formation of a luminescent species results, and the intensity of the emitted radiation is related to the concentration of the analyte being studied. The RRC optrode was developed and optimized for the determination of trace levels of Al(III) and Cr(VI). A modified method of standard addition was also developed for use with the RRC optrode and optimized for the Al(III) study. Trace levels of aluminum are determined by measuring the rate of formation of the fluorescent chelate of Al(III) with 2,4,2'-trihydroxy-azobenzene-5'-sulfonic acid. This method provides a DL of 0.13 ng/mL and a linear dynamic range of four orders of magnitude using the RRC optrode. One of the reagent lines of the RRC optrode was configured to inject an Al(III) standard solution to implement in situ standard addition measurements. Analysis of a tap water sample with external standards and the standard-addition procedure produced equivalent results. Low concentrations of Cr(VI) in water were determined by monitoring the intensity of the chemiluminescence (CL) produced when Cr(VI) is mixed with a lophine-H₂0₂-K0H reagent system in the RRC optrode. This technique exhibits a DL of 11 ng/mL with a linear response up to 10 μg/mL

Performance/outcomes data and physician process challenges for practical big data efforts in radiation oncology

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146290/1/mp13136.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146290/2/mp13136_am.pd

Supplemental Data 2 - Species Traits

Species trait values used in analyses

Data set for analyses

Includes study area, site, year, and species information as well as covariates used in the analyses. Exact location information is not included for sites due to the sensitive nature of many of the species. Please contact authors directly to request this information

Supplemental Data 1 - Code to fit model

Model code in bugs language

Data from: Quantifying climate sensitivity and climate-driven change in North American amphibian communities

Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 86 North American study areas. The effect of climate on local colonization and persistence probabilities varies among eco-regions and depends on local climate, species life-histories, and taxonomic classification. We found that local species richness is most sensitive to changes in water availability during breeding and changes in winter conditions. Based on the relationships we measure, recent changes in climate cannot explain why local species richness of North American amphibians has rapidly declined. However, changing climate does explain why some populations are declining faster than others. Our results provide important insights into how amphibians respond to climate and a general framework for measuring climate impacts on species richness