Aqueous-phase secondary organic aerosol and organosulfate formation in atmospheric aerosols: a modeling study.

We have examined aqueous-phase secondary organic aerosol (SOA) and organosulfate (OS) formation in atmospheric aerosols using a photochemical box model with coupled gas-phase chemistry and detailed aqueous aerosol chemistry. SOA formation in deliquesced ammonium sulfate aerosol is highest under low-NO(x) conditions, with acidic aerosol (pH = 1) and low ambient relative humidity (40%). Under these conditions, with an initial sulfate loading of 4.0 µg m(-3), 0.9 µg m(-3) SOA is predicted after 12 h. Low-NO(x) aqueous-aerosol SOA (aaSOA) and OS formation is dominated by isoprene-derived epoxydiol (IEPOX) pathways; 69% or more of aaSOA is composed of IEPOX, 2-methyltetrol, and 2-methyltetrol sulfate ester. 2-Methyltetrol sulfate ester comprises >99% of OS mass (66 ng m(-3) at 40% RH and pH 1). In urban (high-NO(x)) environments, aaSOA is primarily formed via reversible glyoxal uptake, with 0.12 µg m(-3) formed after 12 h at 80% RH, with 20 µg m(-3) initial sulfate. OS formation under all conditions studied is maximum at low pH and lower relative humidities (<60% RH), i.e., when the aerosol is more concentrated. Therefore, OS species are expected to be good tracer compounds for aqueous aerosol-phase chemistry (vs cloudwater processing).

Inability to Catabolize Rhamnose by Sinorhizobium meliloti Rm1021 Affects Competition for Nodule Occupancy.

Rhizobium leguminosarum strains unable to grow on rhamnose as a sole carbon source are less competitive for nodule occupancy. To determine if the ability to use rhamnose as a sole carbon source affects competition for nodule occupancy in Sinorhizobium meliloti, Tn5 mutants unable to use rhamnose as a sole carbon source were isolated. S. meliloti mutations affecting rhamnose utilization were found in two operons syntenous to those of R. leguminosarum. Although the S. meliloti Tn5 mutants were complemented using an R. leguminosarum cosmid that contains the entire wild-type rhamnose catabolic locus, complementation did not occur if the cosmids carried Tn5 insertions within the locus. Through a series of heterologous complementation experiments, enzyme assays, gene fusion, and transport experiments, we show that the S. meliloti regulator, RhaR, is dominant to its R. leguminosarum counterpart. In addition, the data support the hypothesis that the R. leguminosarum kinase is capable of directly phosphorylating rhamnose and rhamnulose, whereas the S. meliloti kinase does not possess rhamnose kinase activity. In nodule competition assays, S. meliloti mutants incapable of rhamnose transport were shown to be less competitive than the wild-type and had a decreased ability to bind plant roots in the presence of rhamnose. The data suggests that rhamnose catabolism is a general determinant in competition for nodule occupancy that spans across rhizobial species.

Structured Reports and Radiology Residents: Friends or Foes?

Structured reports offer overall improvement in quality and safety, largely centered upon more effective communication. Structured reporting is helpful to trainees as a method to develop organized search patterns and include pertinent positive and negative findings. However, limitations of structured report use include lack of development of individualized search patterns and failure to recognize key elements of the report to be formulated in the impression. Instruction on the value of a structured reporting approach, its impact on patient care and clinical service, and compliance with billing requirements must be balanced with early and consistent feedback on appropriate use and reporting errors. It is incumbent upon radiology educators to integrate and optimize structured reporting in the learning environment. This manuscript addresses the impact of structured reporting on radiology education, reviewing quality and safety considerations, detailing benefits and drawbacks for trainees, and offering strategies for optimizing the use of structured reporting/templates in the training environment.

Environmental Earth Sciences Progress Report 2020 and Outlook 2021.

The present editorial 2020 continues the series of status reports in Environmental Earth Sciences (EES) in previous years 2017 and 2019 (Kolditz et al. in Environ Earth Sci 77: 8, 2018, Kolditz et al. in Environ Earth Sci 79: 11, 2020). The year 2020 coming to an end was heavily influenced by the COVID-19 pandemic affecting all areas of life including research work and, therefore, scientific publishing as well ("Introduction"). One bright spot which shows longevity of journals that produce a quality product is that Environmental Earth Sciences (EES) is celebrating its 45th anniversary of publication. To this extent EES continues the tradition to honor the most cited papers contributing to the 2020 Impact Factor (IF) ("Highly and most cited topics") and provide information on the current status of EES as well as an outlook to 2021 ("Progress report").

Gender Differences in Article Citations by Authors from American Institutions in Major Radiology Journals.

Objective To investigate gender difference patterns in article citations, by first and last authors, in four radiology journals. Materials and methods Articles by authors published in four major radiology journals from 1984, 1994, 2004, and 2014 were categorized into 12 subspecialties. The number of citations, references used, co-authors, and length of the article (number of pages) were documented. The genders of first/last authors were determined. Data were analyzed using chi-square and logistic regression. Results The gender of the first author was determined in 2679 articles and that of the last author in 2717 articles. Over the selected years, 1984 to 2014, female first authorship grew from 13.0% to 31.5% (p<0.001), and female last authorship grew from 9.3% to 22.1% (p<0.001). Primary female authorship papers were cited less often as compared to males (OR 0.9972, 95% CI: 0.9948-0.9996, p=0.021), after adjusting for publication year and subspecialty. Across most subspecialties, female first authorship received fewer citations. In 1984, primary female authorship papers received on average 28.9 citations versus males at 39.1; in 1994, 50.4 versus 60.8; in 2004, 41.5 versus 44.4; and in 2014, 7.0 versus 7.8. The mean difference in the number of citations received by male and female first authors decreased from 10.47±6.09 in 1984 and 9.49±7.12 in 1994 to 1.93±5.63 in 2004 and 0.79±0.39 in 2014. However, there was no statistical difference demonstrated in article citations between male and female last authorship (OR 0.9990, 95% CI: 0.9966-1.0013, p=0.392). Conclusions Primary female authorship garnered fewer citations than men, despite the increasing frequency of authorships. However, this differential in the number of citations is narrowing.

A Novel Technique to Measure the Intensity of Abnormality on GI Bleeding Scans: Development, Initial Implementation, and Correlation With Conventional Angiography.

PURPOSE: Develop a technique to quantify intensity of lower gastrointestinal bleeding (LGIB) on Tc-labeled red blood cell (RBC) scintigraphy, correlate with angiography, and determine the tool's predictive value. MATERIALS AND METHODS: An IRB-approved, single institution database query of GI bleeding scans performed between January 2013 and December 2015. Reports from all studies and imaging from all positive studies were reviewed. A technique was developed for scan analysis, allowing for calculation of percent increase of activity in the region of interest (ROI, area of bleeding) and ROI in the aorta and liver (controls). Database query determined which patients underwent angiography, and which had positive angiograms. Median ROI percent increase in patients with positive scintigraphy and positive angiography was compared to those with positive scintigraphy and negative angiography. RESULTS: Of 194 bleeding scans performed during the study period, 71 were positive for active LGIB, 37 had angiography, and 9 had active contrast extravasation. The new tool was used to analyze the 37 cases with positive nuclear scans sent for angiography. Median percent increase in ROI activity was 50% in those with positive scan and positive angiogram and 26.8% in those with positive scan but negative angiogram. Using ROI percent change quartiles, we observed a statistically significant association between percent increase in ROI activity from baseline and the probability of having a positive angiogram (Cochran-Armitage trend test, P = 0.01), such that there are no positive angiogram cases when ROI change was <20% and a majority of the positive angiogram cases (67%) in the highest quartile. CONCLUSIONS: Utilization of processing protocol to determine percent increase in activity from baseline within ROI of active LGIB on scintigraphy has predictive value in determining which patients will not benefit from conventional angiography.

Aqueous aerosol SOA formation: impact on aerosol physical properties.

Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.