A highly sensitive hydrogen peroxide probe that takes advantage of the amplified fluorescence quenching of conjugated polymers has been developed. The cationic conjugated polymer, poly(9,9‐bis(6′‐N,N,N‐trimethylammonium‐hexyl) fluorene phenylene) (PFP‐NMe3+) and peroxyfluor‐1 with boronate protecting groups (Fl‐BB) are used to detect H2O2 optically. Without the addition of H2O2, the absence of electrostatic interactions between the cationic PFP‐NMe3+ and the neutral Fl‐BB keeps the Fl‐BB well separated from the PFP‐NMe3+, and no fluorescence quenching of the PFP‐NMe3+ occurs. In the presence of H2O2, the formation of the anionic quencher, fluorescein, by specific reaction of the Fl‐BB with H2O2 results in strong electrostatic interactions between the PFP‐NMe3+ and the fluorescein, and therefore efficient fluorescence quenching of the PFP‐NMe3+ occurs. The absorption of fluorescein overlaps the emission of PFP‐NMe3+, which encourages fluorescence resonance energy transfer (FRET) from the PFP‐NMe3+ to the fluorescein. The H2O2 probe has very good sensitivity, with a detection range of 15 to 600 nM. Since glucose oxidase (GOx) can specifically catalyze the oxidation of β‐D‐(+)‐glucose to generate H2O2, glucose detection is also realized with the H2O2 probe as the signal transducer.

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The plastic responses of plants to abiotic and biotic environmental factors have generally been addressed separately; thus we have a poor understanding of how these factors interact. For example, little is known about the effects of plant–plant interactions on the plasticity of plants in response to water availability. Furthermore, few studies have compared the effects of intra‐ and interspecific interactions on plastic responses to abiotic factors. To explore the effects of intraspecific and interspecific plant–plant interactions on plant responses to water availability, we grew Leucanthemum vulgare and Potentilla recta with a conspecific or the other species, and grew pairs of each species as controls in pots with the roots, but not shoots, physically separated. We subjected these competitive arrangements to mesic and dry conditions, and then measured shoot mass, root mass, total mass and root : shoot ratio and calculated plasticity in these traits. The total biomass of both species was highly suppressed by both intra‐ and interspecific interactions in mesic soil conditions. However, in drier soil, intraspecific interactions for both species and the effect of P. recta on L. vulgare were facilitative. For plasticity in response to water supply, when adjusted for total biomass, drought increased shoot mass, and decreased root mass and root : shoot ratios for both species in intraspecific interactions. When grown alone, there were no plastic responses in any trait except total mass, for either species. Our results suggested that plants interacting with other plants often show improved tolerance for drought than those grown alone, perhaps because of neighbor‐induced shifts in plasticity in biomass allocation. Facilitative effects might also be promoted by plasticity to drought in root : shoot ratios.

Background The purpose of this study was to understand how the COVID-19 pandemic has affected health care patterns and outcomes for patients diagnosed with metastatic pancreatic ductal adenocarcinoma (mPDAC) in 2020 compared with those diagnosed with mPDAC in 2019. Patients and Methods We used the Flatiron Health database to identify adults diagnosed with mPDAC from March 1 to September 30, 2019 (pre-COVID-19 cohort) and March 1 to September 30, 2020 (post-COVID-19 cohort). Between-cohort comparisons included demographic and clinical characteristics and year-over-year data for diagnosis of mPDAC, newly treated patients, time to and types of first-line therapy, and adverse events (AEs) during first-line therapy. Overall survival (OS) and milestone survival rates were evaluated. Kaplan-Meier methods were used to assess OS. Results Pre-COVID-19 (n = 923) and post-COVID-19 (n = 796) cohorts had similar baseline demographic characteristics. A smaller proportion of patients in the pre-COVID-19 cohort were initially diagnosed with stage IV disease versus the post-COVID-19 cohort (62.2% vs 69.7%). Between 2019 and 2020, there was a 13.8% decrease in diagnosis of mPDAC and a 13.0% decrease in newly treated patients. Median (interquartile range) times to first-line treatment were similar (21 [13-40] and 19 [12-32] days). Median OS (months) was significantly longer in the pre-COVID-19 cohort (8·4 [95% CI: 7·5, 9·0]) versus the post-COVID-19 cohort (6·1 [95% CI: 5·4, 6·9]; P < .001). Survival rates were higher in the pre-COVID-19 versus post-COVID-19 cohorts. Conclusions During the pandemic, patients were initially diagnosed with PDAC at more advanced stages. While patients in both cohorts appeared to receive similar care, survival outcomes were adversely affected.

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