Sulfidation is a major transformation product for manufactured silver nanoparticles (Ag-MNPs) in the wastewater treatment process.We studied the dissolution, uptake, and toxicity of Ag-MNP and sulfidized Ag-MNPs (sAg-MNPs) to a model soil organism, Caenorhabditis elegans. Our results show that reproduction was the most sensitive endpoint tested for both Ag-MNPs and sAg-MNPs. We also demonstrate that sulfidation not only decreases solubility of Ag-MNP, but also reduces the bioavailability of intact sAg-MNP. The relative contribution of released Ag(+) compared to intact particles to toxicity was concentration dependent. At lower total Ag concentration, a greater proportion of the toxicity could be explained by dissolved Ag, whereas at higher total Ag concentration, the toxicity appeared to be dominated by particle specific effects.

This paper reports an interlaboratory comparison that evaluated a protocol for measuring and analysing the particle size distribution of discrete, metallic, spheroidal nanoparticles using transmission electron microscopy (TEM). The study was focused on automated image capture and automated particle analysis. NIST RM8012 gold nanoparticles (30 nm nominal diameter) were measured for area-equivalent diameter distributions by eight laboratories. Statistical analysis was used to (1) assess the data quality without using size distribution reference models, (2) determine reference model parameters for different size distribution reference models and non-linear regression fitting methods and (3) assess the measurement uncertainty of a size distribution parameter by using its coefficient of variation. The interlaboratory area-equivalent diameter mean, 27.6 nm ± 2.4 nm (computed based on a normal distribution), was quite similar to the area-equivalent diameter, 27.6 nm, assigned to NIST RM8012. The lognormal reference model was the preferred choice for these particle size distributions as, for all laboratories, its parameters had lower relative standard errors (RSEs) than the other size distribution reference models tested (normal, Weibull and Rosin–Rammler–Bennett). The RSEs for the fitted standard deviations were two orders of magnitude higher than those for the fitted means, suggesting that most of the parameter estimate errors were associated with estimating the breadth of the distributions. The coefficients of variation for the interlaboratory statistics also confirmed the lognormal reference model as the preferred choice. From quasi-linear plots, the typical range for good fits between the model and cumulative number-based distributions was 1.9 fitted standard deviations less than the mean to 2.3 fitted standard deviations above the mean. Automated image capture, automated particle analysis and statistical evaluation of the data and fitting coefficients provide a framework for assessing nanoparticle size distributions using TEM for image acquisition.

Objective: Our objectives were to assess in perinatal women: the most effective methods used to meet social support needs during COVID-19, the impact of COVID-19 on self-reported social support levels, and how perceived change in social support related to distress, depression, and mental health. Design: One-time survey administered from April to August 2020 Setting: Online Participants: Pregnant and postpartum women with infants less than 6 months of age Measurement and Findings: Participants indicated the methods they used to meet social support needs during COVID-19. They self-rated their social support level pre- and during pandemic and their distress, depression, and mental health changes on a Likert scale. Out of 1142 participants, the most effective methods for obtaining social support during the pandemic were virtual means (e.g. video call) and interaction with friends. There was a significant difference in distribution of self-reported levels of social support before and during the pandemic, with more respondents reporting a decrease in support. Decreases in social support were associated with higher distress levels, higher depression, and poorer mental health. Key Conclusions: Perinatal women reported decreased social support during the COVID-19 pandemic which was associated with poorer mental health. Using virtual means of social support and support provided by friends had the largest positive effect on perceived social support levels. Implications for Practice: Interventions using virtual support means from friends may be helpful to improve social support and mental health in this population.

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Context This study explores the long-term impact of the Professional Student Mentored Research Fellowship (PSMRF) program at the University of Kentucky College of Medicine (UKCOM) on medical students’ research productivity and career paths. Methods Demographic characteristics, academic profiles, number of publications and residency placements from 2007-2012 were used to assess 119 PSMRF graduates against a comparison cohort of 898 UKCOM (non-PSMRF) students. Results PSMRF students had higher MCAT scores at admission (31.5 ± 0.6 vs. 30.6 ± 0.2, p = 0.007) and achieved higher USMLE Step 1 scores (228 ± 4.2 vs. 223 ± 1.5, p = 0.03) than comparison group. PSMRF students were more likely to publish Pubmed-indexed papers (36.7% vs. 17.9%, p < 0.0001), achieve AOA status (19.3% vs. 8.5%, p = 0.0002) and match to top 25 U.S. News and World Report residency programs (23.4% vs. 12.1%, p = 0.008). A greater proportion of PSMRF fellows matched to top tier competitive specialties (23% vs. 14.2%, p= 0.07), however this difference was not statistically significant. Conclusions The PSMRF program shows a significant increase in enrollment, as well as positive associations with indicators of success in medical school and subsequent quality of residency program.