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The activated carbon from marigold flowers (MG) was used to make an unlabeled electrochemical immunosensor to determine prostate cancer. MG was synthesized by hydrothermal carbonization and pyrolysis. MG had a large surface area, was highly conductive, and biocompatible. MG modified with graphene quantum dots produced excellent electron transfer for grafting poly(thionine) (PTH). The amine group of PTH bonded with anti-prostate-specific antigen (Anti-PSA) via glutaraldehyde, forming a layer that improved electron transfer. The binding affinity of the immunosensor, presented as the dissociation constant (Kd), was calculated using the Langmuir isotherm model. The results showed that a lower Kd value indicated greater antibody affinity. The immunosensor exhibited two different linear ranges under optimized conditions: 0.0125 to 1.0 ng mL−1 and 1.0 to 80.0 ng mL−1. The sensor could detect concentrations as low as 0.005 ng mL−1, and had a quantification limit of 0.017 ng mL−1. This immunosensor accurately quantified PSA levels of human serum, and the results were validated using enzyme-linked fluorescence assay (ELFA). [ABSTRACT FROM AUTHOR]

Increasing atmospheric CO2 concentrations in temperate forests may affect soil nitrogen (N)cycling processes due to the increased demand for nitrogen availability to support CO2uptake by trees through photosynthesis. This in turn can affect the emission of nitrous oxide(N2O), a potent greenhouse gas, from the forest soil leading to a potential trade-offbetween the enhanced canopy CO2 uptake and soil N2O emission. Our currentunderstanding of the response of N cycling processes and availability to elevatedatmospheric CO2 (eCO2) in mature, unmanaged temperate forests is limited. TheBirmingham Institute of Forest Research (BIFoR) established in 2017 a Free-AirCO2 Enrichment (FACE) facility in a mature temperate oak dominated forest inStaffordshire, UK, to study under 'real world’ conditions the risks of a changingclimate to forest ecosystems and the services they provide. In April 2018, one yearafter the start of fumigation with 550 ppm CO2, we collected soil samples (0 – 15cm depth) from the three eCO2 and three control plots. Being a N limited forestsoil in spite of enhanced atmospheric reactive N deposition (22 kg N ha−1 y−1),we hypothesized that N mineralisation will increase and N2O emission will bedown regulated to meet tree N demands under eCO2. Soils were amended in thelaboratory with 98 at % 15N-NH4+ and 15N-NO3− (at ∼ 20 % of the ambientsoil NH4+ and NO3− concentration) and were incubated in the dark for 24 hours.Gross N mineralisation and nitrification were estimated according to the isotopedilution technique, while N2O emission from nitrification (15N-NH4+ treatment)and denitrification (15N-NO3− treatment) were estimated according to the 15NGas-Flux method. Additionally, asymbiotic biological N fixation was measured with the15N2 direct assimilation method. Gross N mineralisation was significantly higher(t-Test: P < 0.05) in the eCO2 plots (mean: 2.25 μg N g−1 d−1) compared to thecontrol plots (mean: 0.61 μg N g−1 d−1) confirming our hypothesis, while therewas no significant difference in gross nitrification rates. N2O emission from bothdenitrification (mean: 2.85 ng N g−1 d−1) and nitrification (mean: 0.18 ng N g−1 d−1) wasmarginally higher in the eCO2 plots, but the difference was not statistically significant(t-Test: P > 0.05). Denitrification was a stronger source of N2O (16 times higherthan nitrification) in the eCO2 plots compared to the controls (denitrification 12times higher than nitrification). Finally, asymbiotic biological nitrogen fixation wasalso significantly higher in eCO2 plots. After one year of CO2 fumigation, there isindication of enhanced cycling and N availability to support enhanced canopy CO2uptake. As more soil inorganic N becomes available a shift towards higher N2Oemission is to be expected and continuous multiannual in situ monitoring is needed toestablish the balance between N availability for tree uptake relative to dissimilatory Nlosses including N2O emission under eCO2 to fully elucidate the implications of Navailability for meeting tree N demands under future CO2 enriched atmosphere. [ABSTRACT FROM AUTHOR]