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This study analyses the emission and excitation spectra of Beryllium Oxide (BeO) unirradiated and irradiated with 60Co gamma radiation because of its potential use in radiation dosimetry. Deconvolution of the spectra showed that using an excitation wavelength λexc = 330 nm, four emission bands centered at 404, 430, 468 and 545 nm are obtained; These emission bands appear in both irradiated and non-irradiated BeO; however, the irradiated samples exhibited an extra emission band centered at 416 nm. The excitation spectrum was obtained by setting the emission monochromator at a wavelength λ0 = 400 nm. By means of deconvolution, it was obtained that the emission spectrum of the non-irradiated samples is constituted by two bands centered at 307 and 331 nm, while for the irradiated samples the spectrum has three components centered at 297, 334 and 317 nm. In addition, it was found that the area under the curve of all emission bands decreases after irradiation, this may be due to the formation of electron-hole pairs after irradiation, which have the effect of reducing radiative phenomena, which it could be favorable for the applications of BeO in ionizing radiation dosimetry.A compensation system based on NaI (Tl) detectors and cadmium sheet was proposed for thermal neutron detection in the neutron/gamma field. The system consisted of two identical NaI (Tl) detectors covered with copper and cadmium sheets, respectively. The Cd-covered NaI (Tl) recorded the prompt gamma rays produced by the 113Cd (n, γ)114Cd reaction, while the Cu-covered structure "rejected" the background gamma rays. The moderated thermal neutron fluxes at different distances from an Am-Be neutron source, calibrated by the activation foil method, were investigated using the compensation system. The thermal neutron detection efficiency of this compensation system was compared to those obtained by the CdZnTe detector and He-3 proportional counter. The feasibility of the compensation system used as a thermal neutron counter was demonstrated by the obtained results.Regional- and national-scale emissions of chlorofluorocarbons (CFCs), especially in Eastern China, are of great concern to environmentalists and policy makers. To determine the source-sink dynamics of coastal salt marshes for CFC-11 and CFC-12 in the local atmosphere, we studied a coastal salt marsh in Northern Jiangsu Province, taking measurements of the atmospheric concentrations and fluxes of CFC-11 and CFC-12 using static flux chambers in August (growing season) and December (non-growing season) of 2013, and along both creek-side and vegetated transects. We observed unexpectedly high concentrations of CFC-11 (676.5 × 10-12) and CFC-12 (794.6 × 10-12) in the salt marsh in 2013, with predominantly non-local emissions. Overall, the study salt marsh acted as a net sink for CFC-11 and CFC-12, with the average flux ranging from -11.4 μg m-2 h-1 to 5.0 μg m-2 h-1 for CFC-11 and from -7.4 μg m-2 h-1 to 0.7 μg m-2 h-1 for CFC-12. This clearly indicates that the high concentrations of CFC-11 and CFC-12 measured in the atmosphere were not caused by local emissions; terrigenous sources most likely act as the main exogenous input pathway. Our study suggests that salt marsh ecosystems may be worthy of attention as sinks for CFC-11 and CFC-12; as such, the ecological restoration of salt marshes is critical to better offset increasing CFC-11 and CFC-12 emissions.Areas in central Norway were heavily contaminated with fallout from the Chernobyl accident in 1986. In this study, we assess 137Cs in surface sediments and sediment cores collected in the Vefsnfjord in Nordland county. Concentrations of 137Cs in surface sediments ranged from 159 to 191 Bq kg-1 dry weight (d.w.). Sub-surface peaks of 137Cs were observed in all cores, with a maximum concentration of 432 Bq kg-1 d.w. Given that little is known about the distribution of naturally occurring radionuclides in Norwegian fjords and coastal areas, a better understanding of the total burden of radioactivity is important for the Norwegian fishing and aquaculture industries. Therefore, analyses of the natural radionuclides 40K, 226Ra, 228Ra and 210Pb were included in the study. Analyses of total sulphur (TS), total carbon (TC), total organic carbon (TOC) and grain size distribution have been performed to provide a sedimentologic context for interpreting the radionuclide results.In Taiwan, freshwater clams (Corbicula fluminea) and hard clams (Meretrix lusoria) are the most frequently raised shellfish in land-based pond aquaculture, but research on the accumulation of organochlorine pesticides (OCPs) in these shellfish is limited. We detected the levels of 14 OCPs in 62 shellfish from Taiwanese aquafarms by performing gas chromatography-tandem mass spectrometry. OCP residues were detected in 4.84% of the samples including readings of 0.04 mg/kg chlordane (in a freshwater clam), 0.03 mg/g p,p'-DDE (in a freshwater clam), and 0.02 mg/g p,p'-DDE (in a hard clam). However, the associated estimated daily intake values were less than the acceptable daily intake levels of chlordane and p,p'-DDE Therefore, the consumption of these shellfish presents no immediate health risks. SB203580 Our findings contribute to food safety and serve as a reference for OCP screenings for aquatic shellfish.Agriculture is a major contributor to marine nitrogen pollution, and treatment wetlands can be a strategy to reduce it. However, few studies have assessed the potential of treatment wetlands to mitigate nitrogen pollution in tropical regions. We quantify the nitrogen removal rates of four recently constructed treatment wetlands in tropical Australia. We measured denitrification potential (Dt), the inflow-outflow of nutrients, and tested whether the environment in these tropical catchments is favourable for nitrogen removal. Dt was detected in three of the four systems with rates between 2.0 and 12.0 mg m-2 h-1; the highest rates were measured in anoxic soils (ORP -100 to 300 mV) that were rich in carbon and nitrogen (>2% and >0.2%, respectively). The highest nitrogen removal rates were measured when NO3--N concentrations were >0.4 mg L-1 and when water flows were slow. Treatment wetlands in tropical regions can deliver high removal rates of nitrogen and other pollutants when adequately managed. This strategy can reduce nutrient loads and their impacts on sensitive coastal zones such as the Great Barrier Reef.The concept of nature-based solutions (NBSs) has become increasingly popular among urban policymakers and planners to help them tackle the urban challenges arising from urban expansion and climate change. Stakeholders' involvement is a fundamental step, and stakeholders' perceptions and preferences can affect the development of NBS projects. This study aims to identify stakeholders' perceptions of the most critical urban challenges, the priority interventions, the preferred NBSs and the benefits of the NBSs, and to identify the determinants of these perceptions. A survey was administered to assess stakeholders' perceptions and views on implementing NBSs in two Portuguese cities with distinct urban, geographical, and socio-economic contexts. A binary logistic regression model was used to understand the determinants of the likelihood of the stakeholders' answers. According to the stakeholders, climate change is one of the main concerns in the urban context. It is usually associated with the incidence of heatwaves and water scarcity. Additionally, stakeholders are concerned about the low quantity and poor management of green spaces (GSs). They believe that it will be necessary to increase the GS, to recover some degraded areas, and to increase mobility. The preferred NBSs were planting more urban trees, making green shaded areas, and rehabilitating riverbanks. The main expected benefits were benefits for leisure and relaxation, reductions in air temperature, purer air, and improvements in public health. link2 The results showed mostly coherent connections between the main concerns/priorities of the stakeholders and the perceived NBS benefits; however, some stakeholders did not present coherent connections, indicating low awareness of the current policy for implementing NBSs to overcome existing and future urban challenges.Algae production in nutrient rich sludge dewatering leachate after biogas production is a promising option for wastewater treatment plants. However, the ultra-violet (UV) absorbing characteristic of UV-quenching substances (UVQS) existing in these waters can notably reduce the light transmission within the liquid body. The present work demonstrates a comparative adsorptive removal of UVQS, and other organic substances (expressed as COD and TOC) onto the "acid catalyst" functionalised adsorbent (PPhA) and commercial activated carbon (CAC) from leachate originating from leftover sludge dewatering after biogas production. Laboratory scale column studies were performed to investigate the adsorption performance of selected parameters. The PPhA increased the UV transmittance of leachate more than 4 times and outperformed CAC. Bed Depth Service Time and Yan models were used on the experimental data in order to estimate the maximum adsorption capacity and evaluate the characteristics of the fixed-bed. The PPhA equilibrium uptake of COD and TOC amounted to 5.7 mg/g and 0.9 mg/g, respectively. The postulated removal mechanism in environmentally relevant conditions (e.g., pH neutral) suggested a complex interaction between the biochar and organic macromolecules. Diluted phosphoric acid solution (0.01 mol/L) was successfully used for the column regeneration. Beside the UVQS, PPhA showed affinity towards toxic heavy metals (e.g., Pb, Ni, Co) pointing out the rich surface chemistry of the PPhA. Based on the obtained results and successfully implemented scale-up methodology, the low-cost PPhA adsorbent might effectively compete with the CAC as a highly efficient platform in wastewaters leachate processing.In water, hydrogen peroxide (H2O2) is produced through abiotic and biotic reactions with organic matter, including algal cells. The production of H2O2 is influenced by harmful algal cell communities and toxicity. However, only a few studies have been conducted on H2O2 concentrations in natural water. Particularly, the seasonal and temporal patterns of H2O2 concentration suggest that H2O2 generation from aquatic microorganisms could be identified to compare of photochemical production from dissolved organic matter. Study area is a source of raw water and is a large artificial lake located near a metropolitan city. Due to various environmental conditions, harmful algal blooms frequently occur in summer. The purpose of this study was to trace the H2O2 concentration and water quality parameters of study area where algal bloom occurs and what factors directly affect the H2O2 concentration. Experiments were performed on the influencing factors via water samples from study area and lab-scale culture tank. The lake produces an average of 553 nM H2O2, which increases by more than three times (1460 nM) in summer compared the winter. The lake (18.6-23.8 nMh-1) produced more H2O2 than streams (7.4-9.0 nMh-1) during daylight hours. All water sites presented the lowest production rates in dark conditions (1.1-1.5 nMh-1). Daytime environment increased the generation rate more than the nighttime. link3 The trend of H2O2 produced by algal cells was similar to that of the growth of algal cells. The exposure to external substances (heavy metals and antibiotics) increased the incidence by approximately five times; antibiotics were more influential than heavy metals.
Here's my website: https://www.selleckchem.com/products/SB-203580.html
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