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  • ItemOpen Access
    Dataset associated with "Trifluoroacetic acid deposition from emissions of HFO-1234yf in India, China, and the Middle East"
    (Colorado State University. Libraries, 2021) David, Liji M.
    We have investigated trifluoroacetic acid (TFA) formation from emissions of HFO-1234yf, its dry and wet deposition, and rainwater concentration over India, China, and the Middle East with GEOS-Chem and WRF-Chem models. We estimated the TFA deposition and rainwater concentrations between 2020 and 2040 for four previously published HFO-1234yf emission scenarios to bound the possible levels of TFA. We evaluated the capability of GEOS-Chem to capture the wet deposition process by comparing calculated sulfate in rainwater with observations. Our calculated TFA amounts over the U.S., Europe, and China were comparable to those previously reported when normalized to the same emission. A significant proportion of TFA was found to be deposited outside the emission regions. The mean and the extremes of TFA rainwater concentrations calculated for the four emission scenarios from GEOS-Chem and WRF-Chem were orders of magnitude below the no observable effect concentration. The ecological and human health impacts now and continued use of HFO-1234yf in India, China, and the Middle East are estimated to be insignificant based on the current understanding, as summarized by Neale et al. (2021).
  • ItemOpen Access
    Dataset associated with "Particle Size Distribution Dynamics Can Help Constrain the Phase State of Secondary Organic Aerosol"
    (Colorado State University. Libraries, 2021) He, Yicong; Akherati, Ali; Nah, Theodora; Nga, Ng; Garofalo, Lauren; Farmer, Delphine; Shiraiwa, Manabu; Zaveri, Rahul; Christopher, Cappa; Pierce, Jeff; Jathar, Shantanu
    Particle phase state is a property of atmospheric aerosols that has important implications for the formation, evolution, and gas/particle partitioning of secondary organic aerosol (SOA). In this work, we use a size-resolved chemistry and microphysics model (SOM-TOMAS), updated to include an explicit treatment of particle phase state, to constrain the bulk diffusion coefficient (Db) of SOA produced from alpha-pinene ozonolysis. By leveraging data from laboratory experiments performed in the absence of a seed and under dry conditions, we find that the Db for SOA can be constrained (1-5 ×10^-15 cm^2 s^-1 in these experiments) by simultaneously reproducing the time-varying SOA mass concentrations and the evolution of the particle size distribution. Another version of our model that used the predicted SOA composition to calculate the glass transition temperature, viscosity, and, ultimately, Db (~10-15 cm^2 s^-1) of the SOA was able to reproduce the mass and size distribution measurements when we included oligomer formation (oligomers accounted for about a fifth of the SOA mass). Our work highlights the potential of a size-resolved SOA model to constrain the particle phase state of SOA by utilizing historical measurements of the evolution of the particle size distribution.
  • ItemOpen Access
    Data associated with "Interpersonal relationships drive successful team science: an exemplary case-based study"
    (Colorado State University. Libraries, 2020) Love, Hannah; Cross, Jennifer; Fosdick, Bailey; Crooks, Kevin; VandeWoude, Susan; Fisher, Ellen
    Team science, or collaborations between groups of scientists with varying expertise, is required for researching solutions to complex problems of the 21st century. Despite the essential need for such transdisciplinary interactions, knowledge about training scientists and developing personal mastery, a set of principles and practices necessary for team learning, also referred to as the science of team science (SciTS) in productive team interactions is still in its nascent stages. This article reports on a longitudinal case study of an exemplary scientific team and evaluates the following question: How do scientists enhance their productivity through participation in transdisciplinary teams? Through a focused SciTS study applying mixed methods, including social network surveys, participant observation, focus groups, interviews, and historical social network data, we found that the interactions of an international, transdisciplinary scientific team trained scientists to become experts in their field, helped the team develop personal mastery, advanced their scientific productivity, and fulfilled the land grant mission. The team’s processes and practices to train new scientists propelled new ideas, collaborations, and research outcomes over a 15-year period. This case study highlights that in addition to specific scientific discoveries, scientific progress benefits from developing and forming interpersonal relationships among scientists from diverse disciplines.
  • ItemOpen Access
    Dataset associated with "Outdoor air pollution in India is not only an urban problem"
    (Colorado State University. Libraries, 2020) David, Liji M.
    Urban outdoor air pollution in the developing world, mostly due to particulate matter with diameters smaller than 2.5 µm (PM2.5), has been highlighted in recent years as it leads to millions of premature deaths. Outdoor air pollution has also been viewed mostly as an urban problem. We use satellite-derived demarcations to parse India's population into urban and non-urban regions (which agrees with the census data). We also use the satellite-derived surface PM2.5 levels to calculate the health impacts in the urban and non-urban regions. We show that the outdoor air pollution problem is just as severe in non-urban regions as in the urban regions of India, with implications to monitoring, regulations, health, and policy.
  • ItemOpen Access
    Dataset associated with "Could the exception become the rule? "Uncontrollable" air pollution events in the U.S. due to wildland fires"
    (Colorado State University. Libraries, 2020) David, Liji
    Exceptional events occur when air pollution in a specific location exceeds the National Ambient Air Quality Standards (NAAQS) due to an event that cannot be reasonably attributed to human activities, such as wildland fire. Ground-level ozone (O3) and particulate matter (PM) are EPA criteria pollutants regulated under the NAAQS. Smoke from wildland fires can increase PM and O3 concentrations downwind of fire and impact air quality, visibility, and health. Our analysis shows that the frequency of exceptional event reporting for particulate matter with aerodynamic diameters smaller than 2.5 m or 10 m (PM2.5 and PM10) had increased since 2007 when the air quality standards became more stringent. We also show that wildland fires and windblown dust drive many exceptional events in several EPA regions. We note the importance of growth in the number of exceptional event days due to wildfire smoke in the future due to climate change and point to possible changes to the NAAQS and implementations.
  • ItemOpen Access
    Data associated with the manuscript: Influence of single-nanoparticle electrochromic dynamics on the durability and speed of smart windows
    (Colorado State University. Libraries, 2019) Sambur, Justin B.; Evans, R. Colby; Ellingworth, Austin; Cashen, Christina J.; Weinberger, C. R.
    Nanomaterials have tremendous potential to increase electrochromic smart window efficiency, speed, and durability. However, nanoparticles vary in size, shape, and surface defects, and it is unknown how nanoparticle heterogeneity contributes to particle dependent electrochromic properties. Here, we use single-nanoparticle level electro-optical imaging to measure structure–function relationships in electrochromic tungsten oxide nanorods. Single nanorods exhibit a particle-dependent waiting time for tinting (from 100 ms to 10 s) due to Li-ion insertion at optically inactive surface sites. Longer nanorods tint darker than shorter nanorods and exhibit a Li-ion gradient that increases from the nanorod ends to the middle. The particle-dependent ion-insertion kinetics contribute to variable tinting rates and magnitudes across large-area smart windows. Next, we quantified how particle–particle interactions impact tinting dynamics and reversibility as the nanorod building blocks are assembled into a thin film. Interestingly, single particles tint 4 times faster and cycle 20 times more reversibly than thin films made of the same particles. These findings allow us to propose a nanostructured electrode architecture that optimizes optical modulation rates and reversibility across large-area smart windows.
  • ItemOpen Access
    Successful process evaluation provides insight into team development and goal attainment: science of team science
    (Colorado State University. Libraries, 2019) Love, Hannah; Fosdick, Bailey; Cross, Jeni; Fisher, Ellen; Suter, Meghan; Egan, Dinaida
    The Science of Team Science (SciTS) emerged as a field of study because scientists are increasingly charged with solving complex and large-scale societal, health, and environmental challenges. The SciTS field seeks to develop both methods for assessing teams and a knowledge base of effective practices in team science. What makes interdisciplinary scientific teams successful? Many early studies of team science success drew on existing data like bibliometrics and patent applications to examine the patterns of successful teams. However, these metrics have several shortcomings: they can only be used to characterize teams that were successful enough to produce publications, patents or grant proposals; and their creation lags years behind team formation. Studies which rely exclusively on existing data are not able explain the differences between successful and unsuccessful teams in their formation, interaction, and development. This study asks the questions: "How are team processes and interactions related to goal accomplishment in transdisciplinary teams? Can process metrics be used to predict team success and team outcomes?" This study aims to fill the gap in SciTS literature by longitudinally observing eight scientific transdisciplinary teams and correlating process metrics to outcome metrics. From 2015 through 2017, we used participant observation, informal interviews, turn-taking assessments, and social network surveys to follow teams through their first two years of formation. We then examined which metrics of team interaction and team processes are correlated with traditional team-defined outcome metrics such as conference presentations, grant proposals, journal articles, and invention disclosures. We found that the strength of relationships, role of women, and even participation were the biggest predictors of team success. We discuss how process evaluation can be used to assess team success in the early stages of team development and which measures are more strongly associated with team success.
  • ItemOpen Access
    Supporting data for the manuscript "Modeling the formation and composition of secondary organic aerosol from diesel exhaust using parameterized and semi-explicit chemistry and thermodynamic models"
    (Colorado State University. Libraries, 2018) Eluri, Sailaja; Cappa, Christopher D.; Friedman, Beth; Farmer, Delphine K.; Jathar, Shantanu
    Laboratory-based studies have shown that combustion sources emit volatile organic compounds that can be photo-oxidized in the atmosphere to form secondary organic aerosol (SOA). In some cases, this SOA can exceed direct emissions of primary organic aerosol (POA). Jathar et al. (2017a) recently reported on experiments that used an oxidation flow reactor (OFR) to measure the photochemical production of SOA from a diesel engine operated at two different engine loads (idle, load), two fuel types (diesel, biodiesel), and two aftertreatment configurations (with and without an oxidation catalyst and particle filter). In this work, we used two different SOA models, the Volatility Basis Set (VBS) model and the Statistical Oxidation Model (SOM), to simulate the formation and composition of SOA for those experiments. Leveraging recent laboratory-based parameterizations, both frameworks accounted for a semi-volatile and reactive POA; SOA production from semi-volatile, intermediate volatility, and volatile organic compounds (SVOC, IVOC and VOC); NOx -dependent parameterizations; multigenerational gas-phase chemistry; and kinetic gas–particle partitioning. Both frameworks demonstrated that for model predictions of SOA mass to agree with measurements across all engine load–fuel–aftertreatment combinations, it was necessary to model the kinetically limited gas–particle partitioning in OFRs and account for SOA formation from IVOCs, which were on average found to account for 70% of the model-predicted SOA. Accounting for IVOCs, however, resulted in an average underprediction of 28% for OA atomic O:C ratios. Model predictions of the gas-phase organic compounds (resolved in carbon and oxygen space) from the SOM compared favorably to gas-phase measurements from a chemical ionization mass spectrometer (CIMS), substantiating the semi-explicit chemistry captured by the SOM. Model–measurement comparisons were improved on using SOA parameterizations corrected for vapor wall loss. As OFRs are increasingly used to study SOA formation and evolution in laboratory and field environments, models such as those developed in this work can be used to interpret the OFR data.
  • ItemOpen Access
    Allostery in the dengue virus NS3 helicase: Insights into the NTPase cycle from molecular simulations
    (Colorado State University. Libraries, 2018-03-01) McCullagh, Martin; Davidson, Russell; Hendrix, Josie; Geiss, Brian
    The C-terminus domain of non-structural 3 (NS3) protein of the Flaviviridae viruses (e.g. HCV, dengue, West Nile, Zika) is a nucleotide triphosphatase (NTPase) -dependent superfamily 2 (SF2) helicase that unwinds double-stranded RNA while translocating along the nucleic polymer. Due to these functions, NS3 is an important target for antiviral development yet the biophysics of this enzyme are poorly understood. Microsecond-long molecular dynamic simulations of the dengue NS3 helicase domain are reported from which allosteric effects of RNA and NTPase substrates are observed. The presence of a bound single-stranded RNA catalytically enhances the phosphate hydrolysis reaction by affecting the dynamics and positioning of waters within the hydrolysis active site. Coupled with results from the simulations, electronic structure calculations of the reaction are used to quantify this enhancement to be a 150-fold increase, in qualitative agreement with the experimental enhancement factor of 10-100. Additionally, protein-RNA interactions exhibit NTPase substrate-induced allostery, where the presence of a nucleotide (e.g. ATP or ADP) structurally perturbs residues in direct contact with the phosphodiester backbone of the RNA. Residue-residue network analyses highlight pathways of short ranged interactions that connect the two active sites. These analyses identify motif V as a highly connected region of protein structure through which energy released from either active site is hypothesized to move, thereby inducing the observed allosteric effects. These results lay the foundation for the design of novel allosteric inhibitors of NS3.
  • ItemOpen Access
    Data associated with the manuscript: Investigating diesel engines as an atmospheric source of isocyanic acid in urban areas
    (Colorado State University. Libraries, 2017) Jathar, Shantanu H.; Heppding, Christopher; Link, Michael F.; Farmer, Delphine K.; Akherati, Ali; Kleeman, Michael J.; de Gouw, Joost A.; Veres, Patrick R.; Roberts, James M.
    Isocyanic acid (HNCO), an acidic gas found in tobacco smoke, urban environments and biomass burning-affected regions, has been linked to adverse health outcomes. Gasoline- and diesel-powered engines and biomass burning are known to emit HNCO and hypothesized to emit precursors such as amides that can photochemically react to produce HNCO in the atmosphere. Increasingly, diesel engines in developed countries like the United States are required to use Selective Catalytic Reduction (SCR) systems to reduce tailpipe emissions of oxides of nitrogen. SCR chemistry is known to produce HNCO as an intermediate product, and SCR systems have been implicated as an atmospheric source of HNCO. In this work, we measure HNCO emissions from an SCR system-equipped diesel engine and, in combination with earlier data, use a three-dimensional chemical transport model (CTM) to simulate the ambient concentrations and source/pathway contributions to HNCO in an urban environment. Engine tests were conducted at three different engine loads, using two different fuels and at multiple operating points. HNCO was measured using an acetate chemical ionization mass spectrometer. The diesel engine was found to emit primary HNCO (3-90 mg kg-fuel-1) but we did not find any evidence that the SCR system or other aftertreatment devices (i.e., oxidation catalyst and particle filter) produced or enhanced HNCO emissions. The CTM predictions compared well with the only available observational data sets for HNCO in urban areas but under-predicted the contribution from secondary processes. The comparison implied that diesel-powered engines were the largest source of HNCO in urban areas. The CTM also predicted that daily-averaged concentrations of HNCO reached a maximum of ~110 pptv but were an order of magnitude lower than the 1 ppbv level that could be associated with physiological effects in humans. Precursor contributions from other combustion sources (gasoline and biomass burning) and wintertime conditions could enhance HNCO concentrations but need to be explored in future work.