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991.
As gaseous nitric oxide (NO), a critical and multifaceted biomarker, diffuses easily once released, identifying the precise sources of NO release is a challenge. This study developed a new technique for real-time in vivo direct NO imaging by coupling an amperometric NO nanosensor with scanning electrochemical microscopy. This technique provides three-dimensional information of the NO releasing sites in an intact living mouse brain with high sensitivity and spatial resolution. Immunohistochemical analysis was carried out to confirm the anatomical reliability of the acquired electrochemical NO image. The real-time NO imaging results were well matched with the corresponding immunohistochemical analysis of neuronal NO synthase immunoreactive (nNOS-IR) cells, i.e., NO releasing sites in a living brain. The imaged NO local concentrations were confirmed to be closely related to the location in depth, the size of the nNOS-IR cell, and the intensity of nNOS immunoreactivity. This paper demonstrates the first direct electrochemical NO imaging of a living brain. 相似文献
992.
León-Mejía G Espitia-Pérez L Hoyos-Giraldo LS Da Silva J Hartmann A Henriques JA Quintana M 《The Science of the total environment》2011,409(4):686-691
Coal mining is one of the most important causes of environmental pollution, as large quantities of coal dust particles are emitted. Colombia-South America has large natural coal reserves and “El Cerrejón” is the world's largest open-cast mine located in the northern department of Guajira. The aim of the present study was to evaluate genotoxic effects in a population exposed to coal residues from the open-cast mine “El Cerrejón”. 100 exposed workers and 100 non-exposed control individuals were included in this study. The exposed group was divided according to different mining area activities: (i). Transport of extracted coal, (ii). Equipment field maintenance, (iii). Coal stripping and, (iv). Coal embarking. Blood samples were taken to investigate biomarkers of genotoxicity, specifically, primary DNA damage as damage index (DI), tail length and% of tail DNA using the Comet assay (alkaline version) and chromosome damage as micronucleus (MN) frequency in lymphocytes. Both biomarkers showed statistically significantly higher values in the exposed group compared to the non-exposed control group. No difference was observed between the exposed groups executing different mining activities. These results indicate that exposure to coal mining residues may result in an increased genotoxic exposure in coal mining workers. We did not find a correlation between age, alcohol consumption and service time with the biomarkers of genotoxicity. Our results are the first data of genotoxic effects induced by coal mining exposure in Colombia, and thus, contribute to the exploration of test batteries use for monitoring of exposed populations and may stimulate designing control, hygiene and prevention strategies for occupational health risk assessment in developing countries. 相似文献
993.
Zemba S Ames M Green L Botelho MJ Gossman D Linkov I Palma-Oliveira J 《The Science of the total environment》2011,409(20):4198-4205
Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits. 相似文献
994.
Advanced treatment technologies that control multiple contaminants are beneficial to drinking water treatment. This research applied UV/H2O2 for the simultaneous degradation of geosmin, 2-methylisoborneol, four trihalomethanes and six haloacetic acids. Experiments were conducted in de-ionized water at 24 ± 1.0 °C with ng/L amounts of odorants and μg/L amounts of disinfection byproducts. UV was applied with and without 6 mg/L H2O2. The results demonstrated that brominated trihalomethanes and brominated haloacetic acids were degraded to a greater extent than geosmin and 2-methylisoborneol. Tribromomethane and dibromochloromethane were degraded by 99% and 80% respectively at the UV dose of 1200 mJ/cm2 with 6 mg/L H2O2, whereas 90% of the geosmin and 60% of the 2-methylisoborneol were removed. Tribromoacetic acid and dibromoacetic acid were degraded by 99% and 80% respectively under the same conditions. Concentrations of trichloromethane and chlorinated haloacetic acids were not substantially reduced under these conditions and were not effectively removed at doses designed to remove geosmin and 2-methylisoborneol. Brominated compounds were degraded primarily by direct photolysis and cleavage of the C-Br bond with pseudo first order rate constants ranging from 10−3 to 10−2 s−1. Geosmin and 2-methylisoborneol were primarily degraded by reaction with hydroxyl radical with direct photolysis as a minor factor. Perchlorinated disinfection byproducts were degraded by reaction with hydroxyl radicals. These results indicate that the UV/H2O2 can be applied to effectively control both odorants and brominated disinfection byproducts. 相似文献
995.
Guimaraes JR Betancourt O Miranda MR Barriga R Cueva E Betancourt S 《The Science of the total environment》2011,409(23):5026-5033
Small-scale gold mining in Portovelo-Zaruma, Southern Equador, performed by mercury amalgamation and cyanidation, yields 9-10 t of gold/annum, resulting in annual releases of around 0.65 t of inorganic mercury and 6000 t of sodium cyanide in the local river system. The release of sediments, cyanide, mercury, and other metals present in the ore such as lead, manganese and arsenic significantly reduces biodiversity downstream the processing plants and enriches metals in bottom sediments and biota. However, methylmercury concentrations in sediments downstream the mining area were recently found to be one order of magnitude lower than upstream or in small tributaries. In this study we investigated cyanide, bacterial activity in water and sediment and mercury methylation potentials in sediments along the Puyango river watershed, measured respectively by in-situ spectrophotometry and incubation with 3H-leucine and 203Hg2+.Free cyanide was undetectable (< 1 μg·L− 1) upstream mining activities, reached 280 μg·L− 1 a few km downstream the processing plants area and was still detectable about 100 km downstream. At stations with detectable free cyanide in unfiltered water, 50% of it was dissolved and 50% associated to suspended particles. Bacterial activity and mercury methylation in sediment showed a similar spatial pattern, inverse to the one found for free cyanide in water, i.e. with significant values in pristine upstream sampling points (respectively 6.4 to 22 μgC·mg wet weight− 1·h− 1 and 1.2 to 19% of total 203Hg·g dry weight− 1·day− 1) and undetectable downstream the processing plants, returning to upstream values only in the most distant downstream stations. The data suggest that free cyanide oxidation was slower than would be expected from the high water turbulence, resulting in a long-range inhibition of bacterial activity and hence mercury methylation. The important mercury fluxes resultant from mining activities raise concerns about its biomethylation in coastal areas where many mangrove areas have been converted to shrimp farming. 相似文献
996.
This paper presents AsphaltOpen, a visualization tool for Hot Mix Asphalt (HMA) paving operations and a data collection process to collect the input data for AsphaltOpen from HMA paving operations. In detail, AsphaltOpen visualizes collected site-specific GIS data and GPS path tracing data of equipments' motions together with the HMA's temperature behavior. In this way, AsphaltOpen allows HMA paving professionals to understand and learn about the relation of machine operations and HMA temperature and its impact on the HMA compaction. To ensure the practical usability, we developed AsphaltOpen and the data collection process by conducting action research with HMA paving operators. Overall, AsphaltOpen offers an easy-to-use tool for HMA paving companies to visualize previous asphalting operations. In this way, it opens up new ways for HMA paving contractors to improve and professionalize their paving operations. 相似文献
997.
998.
999.
Ultrafast optical probing of electric field by means of electroabsorption combined with conventional photocurrent measurements was employed to investigate the drift and mobility dynamics of photo-generated charge carriers in the pristine PC61BM film and in the blend with a merocyanine dye. Electrons passed a 40 nm thick PC61BM film within a few picoseconds with time-independent and weakly dispersive mobility. The electron mobility is 1 cm2/(V s) at 1 MV/cm and an estimate of the zero-field mobility yields 5 ⋅ 10−2 cm2/(V s). The initial electron mobility in the blend is of the order of 10−2 cm2/(V s) and decreases rapidly. We conclude that electron motion in PC61BM based organic bulk hetero-junction solar cells is limited by barriers between PC61BM domains rather than by intrinsic PC61BM properties. 相似文献
1000.
Jacob Jensen Markus Hösel Inyoung Kim Jong‐Su Yu Jeongdai Jo Frederik C. Krebs 《Advanced functional materials》2014,24(9):1228-1233
Indium‐doped tin oxide free electrochromic devices are prepared by coating electrochromic polymers onto polyethylene terephthalate substrates encompassing two different silver grids as electrodes. One design comprises a flexoprinted highly conductive silver grid electrode, yielding electrochromic devices with a response time of 2 s for an optical contrast of 27%. The other design utilizes an embedded silver grid electrode whereupon response times of 0.5 s for a 30% optical contrast are realized when oxidizing the device. A commercially available conductive poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate acid) formulation (PEDOT:PSS) is coated onto the silver grids as a charge balancing polymer, and is in this setting found to be superior to a polypyrrole previously employed in electrochromic devices. In addition, the PEDOT:PSS layer increases the conductivity in the hexagonal grid structure. 相似文献