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"Robinson, Michael, A"
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Temperature-dependent sensitivity of iodide chemical ionization mass spectrometers
Iodide chemical ionization mass spectrometry (CIMS) is a common analytical tool used in both laboratory and field experiments to measure a large suite of atmospherically relevant compounds. Here, we describe a systematic ion molecule reactor (IMR) temperature dependence of iodide CIMS analyte sensitivity for a wide range of analytes in laboratory experiments. Weakly bound iodide clusters, such as HCl, HONO, HCOOH, HCN, phenol, 2-nitrophenol, and acyl peroxynitrate (PAN) detected via the peroxy radical cluster, all exhibit strong IMR temperature dependence of sensitivity ranging from −3.4 % ∘C−1 to 5.9 % ∘C−1 (from 37 to 47 ∘C). Strongly bound iodide clusters, such as Br2, N2O5, ClNO2, and PAN detected via the carboxylate anion, all exhibit little to no IMR temperature dependence ranging from 0.2 % ∘C−1 to −0.9 % ∘C−1 (from 37 to 47 ∘C). The IMR temperature relationships of weakly bound clusters provide an estimate of net reaction enthalpy, and comparison with database values indicates that these clusters are in thermal equilibrium. Ground site HCOOH data collected in the summer of 2021 in Pasadena (CA) are corrected and show a reversal in the diel cycle, emphasizing the importance of this correction (35±6 % during the day, -26±2 % at night). Finally, we recommend two approaches to minimize this effect in the field, namely heating or cooling the IMR; the latter technique has the added benefit of improving absolute sensitivity.
Journal Article
The Eagle has landed : 50 years of lunar science fiction
\"In celebration of the 50th anniversary of the Apollo 11 landing, the endlessly-mysterious moon is explored in this reprint short science fiction anthology from award-winning editor and anthologist Neil Clarke ... On July 20, 1969, mankind made what had only years earlier seemed like an impossible leap forward: when Apollo 11 became the first manned mission to land on the moon, and Neil Armstrong the first person to step foot on the lunar surface. While there have only been a handful of new missions since, the fascination with our planet's satellite continues, and generations of writers and artists have imagined the endless possibilities of lunar life. From adventures in the vast gulf of space between the earth and the moon, to journeys across the light face to the dark side, to the establishment of permanent residences on its surface, science fiction has for decades given readers bold and forward-thinking ideas about our nearest interstellar neighbor and what it might mean to humankind, both now and in our future. [This book] collects the best stories written in the fifty years since mankind first stepped foot on the lunar surface, serving as a shining reminder that the moon is and always has been our most visible and constant example of all the infinite possibility of the wider universe\"-- Provided by publisher.
BOOK
African Americans, Caribbean Blacks and Depression: Which Biopsychosocial Factors Should Social Workers Focus On? Results from the National Survey of American Life (NSAL)
Research suggests that African Americans may be more likely to experience depression, especially severe depression, than other racial or ethnic groups in the United States. Overall there is scant research comparing the relationship between ethnicity and depression among the U.S. Black population. The purpose of this study is to identify the most significant biopsychosocial factors social workers can address in the prevention and treatment of depression in African American and first generations Caribbean Black clients. Data was from the National Survey of American Life (NSAL). Bivariate associations showed that respondents who reported higher self-esteem, lower hopelessness, higher sense of mastery, and lower discrimination showed lower likelihood of having Major Depressive Disorder (MDD). The logistic regression model suggested that respondents who have ever had a chronic disease were more likely to report depression than those who have not ever had a chronic disease. Caribbean Blacks were more likely to report depression compared to African Americans. Additionally, respondents who reported higher discrimination scores were more likely to report depression. This study suggests that social workers should embrace the interconnectedness and holistic approach of the biopsychosocial model in their case conceptualizations, prevention strategies, and treatment modalities.
Journal Article
Urban ozone formation and sensitivities to volatile chemical products, cooking emissions, and NOx upwind of and within two Los Angeles Basin cities
Volatile chemical products (VCPs) and other non-traditional anthropogenic sources, such as cooking, contribute substantially to the volatile organic compound (VOC) budget in urban areas, but their impact on ozone formation is less certain. This study employs Lagrangian box modeling and sensitivity analyses to evaluate ozone response to sector-specific VOC and nitrogen oxide (NOx) emissions in two Los Angeles (LA) Basin cities during the summer of 2021. The model simulated the photochemical processing and transport of temporally and spatially gridded emissions from the FIVE-VCP-NEI17NRT inventory and accurately simulates the variability and magnitude of O3, NOx, and speciated VOCs in Pasadena, CA. VOC sensitivity analyses show that anthropogenic VOCs (AVOC) enhance the mean daily maximum 8 h average ozone in Pasadena by 13 ppb, whereas biogenic VOCs (BVOCs) contribute 9.4 ppb. Of the ozone influenced by AVOCs, VCPs represent the largest fraction at 45 %, while cooking and fossil fuel VOCs are comparable at 26 % and 29 %, respectively. NOx sensitivity analyses along trajectory paths indicate that the photochemical regime of ozone varies spatially and temporally. The modeled ozone response is primarily NOx-saturated across the dense urban core and during peak ozone production in Pasadena. Lowering the inventory emissions of NOx by 25 % moves Pasadena to NOx-limited chemistry during afternoon hours and shrinks the spatial extent of NOx saturation towards downtown LA. Further sensitivity analyses show that using VOCs represented by a separate state inventory requires steeper NOx reductions to transition to NOx sensitivity, further suggesting that accurately representing VOC reactivity in inventories is critical to determining the effectiveness of future NOx reduction policies.
Journal Article
The Effects of Hopelessness on Chronic Disease Among African Americans and Caribbean Blacks: Findings from the National Survey of American Life (NSAL)
This paper examines the relationship between hopelessness on chronic disease in a national sample of African Americans (3570) and Caribbean Blacks (1438) Using the National Survey of American Life. A multivariate negative binomial regression examined whether chronic disease is associated with hopelessness, controlling for sociodemographic characteristics. Overall, 13.14% of the sample reported they were highly hopeless, and 31.5% indicated they were moderately hopeless. About 19% of respondents experienced chronic disease. Bivariate associations showed that those who have ever had chronic disease significantly differed from those who did not in regard to age, gender and spirituality. Multivariate results showed that respondents who ever have had chronic disease reported significantly higher hopelessness scores than those with no chronic disease. The study findings contribute to the current body of literature by supporting findings from smaller studies on the relationship between depression and hopelessness in African Americans and Caribbean Blacks.
Journal Article
Characterization of water-soluble brown carbon chromophores from wildfire plumes in the western USA using size-exclusion chromatography
Wildfires are an important source of carbonaceous aerosol in the atmosphere. Organic aerosol that absorbs light in the ultraviolet to visible spectral range is referred to as brown carbon (BrC), and its impact on Earth's radiative budget has not been well characterized. We collected water-soluble brown carbon using a particle-into-liquid sampler (PILS) on board a Twin Otter aircraft during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign. Samples were collected downwind of wildfires in the western United States from August to September 2019. We applied size-exclusion chromatography (SEC) with ultraviolet-visible spectroscopy to characterize the molecular size distribution of BrC chromophores. The wildfire plumes had transport ages of 0 to 5 h, and the absorption was dominated by chromophores with molecular weights <500 Da. With BrC normalized to a conserved biomass burning tracer, carbon monoxide, a consistent decrease in BrC absorption with plume age was not observed during FIREX-AQ. These findings are consistent with the variable trends in BrC absorption with plume age reported in recent studies. While BrC absorption trends were broadly consistent between the offline SEC analysis and the online PILS measurements, the absolute values of absorption and their spectral dependence differed. We investigate plausible explanations for the discrepancies observed between the online and offline analyses. This included solvent effects, pH, and sample storage. We suspect that sample storage impacted the absorption intensity of the offline measurements without impacting the molecular weight distribution of BrC chromophores.
Journal Article
A better representation of volatile organic compound chemistry in WRF-Chem and its impact on ozone over Los Angeles
The declining trend in vehicle emissions has underscored the growing significance of volatile organic compound (VOC) emissions from volatile chemical products (VCPs). However, accurately representing VOC chemistry in simplified chemical mechanisms remains challenging due to its chemical complexity including speciation and reactivity. Previous studies have predominantly focused on VOCs from fossil fuel sources, leading to an underrepresentation of VOC chemistry from VCP sources. We developed an integrated chemical mechanism, RACM2B-VCP, that is compatible with WRF-Chem and is aimed at enhancing the representation of VOC chemistry, particularly from VCP sources, within the present urban environment. Evaluation against the Air Quality System (AQS) network data demonstrates that our model configured with RACM2B-VCP reproduces both the magnitude and spatial variability of O3 and PM2.5 in Los Angeles. Furthermore, evaluation against comprehensive measurements of O3 and PM2.5 precursors from the Reevaluating the Chemistry of Air Pollutants in California (RECAP-CA) airborne campaign and the Southwest Urban NOx and VOC Experiment (SUNVEx) ground site and mobile laboratory campaign confirm the model's accuracy in representing NOx and many VOCs and highlight remaining biases. Although there exists an underprediction in the total VOC reactivity of observed VOC species, our model with RACM2B-VCP exhibits good agreement for VOC markers emitted from different sectors, including biogenic, fossil fuel, and VCP sources. Through sensitivity analyses, we probe the contributions of VCP and fossil fuel emissions to total VOC reactivity and O3. Our results reveal that 52 % of the VOC reactivity and 35 % of the local enhancement of MDA8 O3 arise from anthropogenic VOC emissions in Los Angeles. Significantly, over 50 % of this anthropogenic fraction of either VOC reactivity or O3 is attributed to VCP emissions. The RACM2B-VCP mechanism created, described, and evaluated in this work is ideally suited for accurately representing ozone for the right reasons in the present urban environment where mobile, biogenic, and VCP VOCs are all important contributors to ozone formation.
Journal Article