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Sample records for hyalella azteca electronic

  1. Toxicity of a cadmium-contaminated diet to Hyalella azteca.

    Science.gov (United States)

    Ball, Angela L; Borgmann, Uwe; Dixon, D George

    2006-09-01

    Four- and 10-week chronic toxicity tests were conducted using the freshwater amphipod Hyalella azteca and Cd-contaminated Chlorella sp. as a food source. Chlorella sp. was cultured in various Cd concentrations, filtered from solution, rinsed, dried, and ground into food flakes for the H. azteca. Unlike Cd toxicity from water sources, growth was found to be a more sensitive toxicological endpoint than survival, with calculated 50 and 25% effect concentrations (EC50s and EC25s, respectively) of 5.43 and 2.82 nmol/g, respectively, for Cd measured in food. Based on the regression of Cd in Chlorella sp. against Cd in filtered culture medium, the EC50 and EC25 corresponded to dissolved Cd concentrations of 11.30 and 5.09 nmol/L, respectively. Little or no bioaccumulation of Cd was found in the tissues of H. azteca that were fed contaminated food. These results demonstrate an apparent toxicological effect (either direct or indirect) of Cd-contaminated Chlorella sp. to H. azteca that is not associated with Cd accumulation. Toxicity of Cd-contaminated Chlorella sp. differs from waterborne Cd toxicity both in terms of the most sensitive endpoint (growth vs survival) and the relationship between toxicity and bioaccumulation. Unlike Cd toxicity through water exposure, Cd bioaccumulation by H. azteca cannot, therefore, be used to infer toxicity of Cd in a diet of Chlorella sp. Although the concentration of Cd in the algal culture medium that ultimately reduced growth of H. azteca in the present study was higher than Cd in water, which caused mortality to H. azteca in water-only tests during previous studies, further research regarding the contribution of dietary Cd to overall Cd toxicity is needed to verify that water-quality guidelines and risk assessments based on water-only exposures are fully protective.

  2. Reduced recruitment in Hyalella azteca (Saussure, 1858) exposed to copper.

    Science.gov (United States)

    Othman, M Shuhaimi; Pascoe, David

    2002-09-01

    Neonates of the amphipod Hyalella azteca were exposed for a 35-day period in the laboratory to a range of copper concentrations, nominally 18 microg/l, 40 microg/l, 70 microg/l and 260 microg/l. The reproductive status of the population was assessed by recording recruitment, the number of precopulatory pairs and number of gravid females. At the end of the experiment, the body lengths of individuals were measured using image analysis. There was a significant decrease in the final population size of H. azteca with increasing copper concentration and compared with the control. Copper significantly reduced recruitment of juveniles and length composition of the final population and there was also a trend toward reduced precopula number with increasing copper concentrations.

  3. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters

    Science.gov (United States)

    Ivey, Chris D.; Ingersoll, Christopher G.

    2016-01-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response ofH. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L.

  4. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  5. Modifying Foods and Feeding Regimes to Optimize the Performance of Hyalella azteca during Chronic Toxicity Tests

    Science.gov (United States)

    The amphipod Hyalella azteca is commonly used to assess the toxicity of sediments and waters. However, laboratories have reported varying success in maintaining healthy cultures and in obtaining consistent growth and reproduction (where applicable), especially during tests...

  6. REPRODUCTIVE TOXICITY OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY MIXTURES TO THE AMPHIPOD, HYALELLA AZTECA

    Science.gov (United States)

    Toxicological interactions were assessed on the reproduction of the amphipod Hyalella azteca throughout a chronic exposure to methyl mercury (0.9, 4.7, 23.3 nM), chlorpyrifos (0.01, 0.05, 0.24), dieldrin (0.5, 2.3, 11.4 nM) and their binary mixtures. H. azteca were exposed to the...

  7. Responses of Hyalella azteca to acute and chronic microplastic exposures.

    Science.gov (United States)

    Au, Sarah Y; Bruce, Terri F; Bridges, William C; Klaine, Stephen J

    2015-11-01

    Limited information is available on the presence of microplastics in freshwater systems, and even less is known about the toxicological implications of the exposure of aquatic organisms to plastic particles. The present study was conducted to evaluate the effects of microplastic ingestion on the freshwater amphipod, Hyalella azteca. Hyalella azteca was exposed to fluorescent polyethylene microplastic particles and polypropylene microplastic fibers in individual 250-mL chambers to determine 10-d mortality. In acute bioassays, polypropylene microplastic fibers were significantly more toxic than polyethylene microplastic particles; 10-d lethal concentration 50% values for polyethylene microplastic particles and polypropylene microplastic fibers were 4.64 × 10(4) microplastics/mL and 71.43 microplastics/mL, respectively. A 42-d chronic bioassay using polyethylene microplastic particles was conducted to quantify effects on reproduction, growth, and egestion. Chronic exposure to polyethylene microplastic particles significantly decreased growth and reproduction at the low and intermediate exposure concentrations. During acute exposures to polyethylene microplastic particles, the egestion times did not significantly differ from the egestion of normal food materials in the control; egestion times for polypropylene microplastic fibers were significantly slower than the egestion of food materials in the control. Amphipods exposed to polypropylene microplastic fibers also had significantly less growth. The greater toxicity of microplastic fibers than microplastic particles corresponded with longer residence times for the fibers in the gut. The difference in residence time might have affected the ability to process food, resulting in an energetic effect reflected in sublethal endpoints.

  8. Toxicity of manganese to Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Lasier, P.J.; Winger, P.V.; Bogenrieder, K.J.

    2000-01-01

    Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments and pore waters. Manganese can be present at toxic levels in anoxic solutions due to its increased solubility under chemically-reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for C. dubia in acute 48h tests and chronic 3-brood tests using animals Manganese concentrations were measured analytically at test initiation and after 96 h for calculations of toxicity endpoints and determinations of Mn precipitation during the tests. Minimal amounts of Mn (below 3%) precipitated within 96 h. LC50s determined for H. azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately-hard and hard waters, respectively. The tolerance of C. dubia to Mn was not significantly different between moderately-hard and hard waters, but was significantly lower in soft water. There was no significant difference in Mn sensitivity between the ages of C. dubia tested. Acute LC50 values for C. dubia averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC50 values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations near these levels.

  9. Acute toxicity of pyraclostrobin and trifloxystrobin to Hyalella azteca.

    Science.gov (United States)

    Morrison, Shane A; McMurry, Scott T; Smith, Loren M; Belden, Jason B

    2013-07-01

    Fungicide application rates on row crop agriculture have increased across the United States, and subsequently, contamination of adjacent wetlands can occur through spray drift or field runoff. To investigate fungicide toxicity, Hyalella azteca amphipods were exposed to 2 fungicide formulations, Headline and Stratego, and their active strobilurin ingredients, pyraclostrobin and trifloxystrobin. Water-only exposures resulted in similar median lethal concentration (LC50; 20-25 µg/L) values for formulations and strobilurin ingredients, suggesting that toxicity is due to strobilurin ingredients. These values were below concentrations that could occur following spray drift over embedded cropland wetlands. When fungicides were added to overlying water of sediment-water microcosms, toxicity was reduced by 500% for Headline and 160% for Stratego, compared with water-only exposures, based on the total amount of fungicide added to the systems. In addition, when fungicides were added to sediment prior to the addition of water, the reduction in toxicity was even greater, with no toxicity occurring at environmentally relevant levels. Differences in toxicity among exposure groups were explained by dissipation from water as toxicity values based on measured water concentrations were within 20% between all systems. The present study reinforces previous studies that Headline and Stratego are toxic to nontarget aquatic organisms. However, the presence of sediment is likely to ameliorate some toxicity of fungicide formulations, especially if spraying occurs prior to wetland inundation.

  10. Optimizing the performance of the amphipod, Hyalella azteca, in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod, Hyalella azteca, is a common organism used for sediment toxicity testing. Standard methods for 10-d and 42-d sediment toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. While Hyalella azteca methods exist for sediment tox...

  11. Optimizing the performance of the amphipod, Hyalella azteca, in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod, Hyalella azteca, is a common organism used for sediment toxicity testing. Standard methods for 10-d and 42-d sediment toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. While Hyalella azteca methods exist for sediment tox...

  12. DIFFERENTIAL DISPLAY ANALYSES OF THE AMPHIPOD HYALELLA AZTECA EXPOSED TO ETHYNYLESTRADIOL AT THREE DIFFERENT TROPHIC LEVELS

    Science.gov (United States)

    A study was conducted to determine if differential display could be used to detect differences in gene expression in the amphipod, Hyalella azteca. In a study of synthetic estrogen attenuation in different aquatic media, amphipods were exposed to 20 ng/L 17 a-ethynylestradiol in...

  13. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity of Hyalella azteca

    Science.gov (United States)

    The toxicity of a nutrient-pesticide mixture in non-vegetated and vegetated sections of a constructed wetland (60 X 30 X 0.3 m) was assessed using Hyalella azteca 48 h aqueous whole effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple super phosphate, dia...

  14. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosms

    Science.gov (United States)

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures such as nutrients only (N, P), pesticides only (atrazine, S-metolachlor, permethrin), and nutrients+pesticides on phytoplankton chlorophyll a, 48 h aqueous Hyalella azteca survival, and 10 d se...

  15. Hyalella azteca Responses to Coldwater River Backwater Sediments in Mississippi, USA

    Science.gov (United States)

    Sediment from three Coldwater River, Mississippi backwaters was examined using 28 d Hyalella azteca bioassays and chemical analyses for 33 pesticides, 7 metals and 7 PCBs. Hydrologic connectivity between the main river channel and backwater varied widely among the three sites. Mortality occurred i...

  16. Effect on Hyalella azteca after pulse exposure to environmentally realistic concentrations of permethrin

    DEFF Research Database (Denmark)

    Pedersen, Signe; Palmqvist, Annemette; Forbes, Valery E.

    realistic pulse exposure and concentration of a pyrethroid pesticide, permethrin, on the freshwater amphipod Hyalella azteca. Permethrin is a pyrethroid insecticide used in mosquito control and to control a wide range of insect pests on various crops and is known to be highly toxic to aquatic invertebrates...

  17. Efficiency of experimental rice (Oryza sativa L.) fields in mitigating diazinon runoff toxicity to Hyalella azteca

    Science.gov (United States)

    This study assessed the viability of using planted, mature rice fields in mitigating diazinon (an organophosphate insecticide) runoff toxicity using aqueous 48 h Hyalella azteca whole effluent toxicity bioassays. Rice fields decreased diazinon concentrations 80.1-99.9% compared with 10.8% in the unv...

  18. DIFFERENTIAL DISPLAY ANALYSES OF THE AMPHIPOD HYALELLA AZTECA EXPOSED TO ETHYNYLESTRADIOL AT THREE DIFFERENT TROPHIC LEVELS

    Science.gov (United States)

    A study was conducted to determine if differential display could be used to detect differences in gene expression in the amphipod, Hyalella azteca. In a study of synthetic estrogen attenuation in different aquatic media, amphipods were exposed to 20 ng/L 17 a-ethynylestradiol in...

  19. Toxicity and transcriptomic analysis in Hyalella azteca suggests increased exposure and susceptibility of epibenthic organisms to Zinc Oxide Nanoparticles.

    Science.gov (United States)

    Nanoparticles (NPs) are expected to make their way into the aquatic environment where sedimentation of particles will likely occur, putting benthic organisms at particular risk. Therefore, organisms such as Hyalella azteca, an epibenthic crustacean which forages at the sediment ...

  20. Toxicity and transcriptomic analysis in Hyalella azteca suggests increased exposure and susceptibility of epibenthic organisms to Zinc Oxide Nanoparticles.

    Science.gov (United States)

    Nanoparticles (NPs) are expected to make their way into the aquatic environment where sedimentation of particles will likely occur, putting benthic organisms at particular risk. Therefore, organisms such as Hyalella azteca, an epibenthic crustacean which forages at the sediment ...

  1. TOXICOKINETIC INTERACTIONS AND SURVIVAL OF HYALELLA AZTECA EXPOSED TO BINARY MIXTURES OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY

    Science.gov (United States)

    Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalella azteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals...

  2. Influence of bromide on the performance of the amphipod Hyalella azteca in reconstituted waters.

    Science.gov (United States)

    Ivey, Chris D; Ingersoll, Chris G

    2016-10-01

    Poor performance of the amphipod Hyalella azteca has been observed in exposures using reconstituted waters. Previous studies have reported success in H. azteca water-only exposures with the addition of relatively high concentrations of bromide. The present study evaluated the influence of lower environmentally representative concentrations of bromide on the response of H. azteca in 42-d water-only exposures. Improved performance of H. azteca was observed in reconstituted waters with >0.02 mg Br/L. Environ Toxicol Chem 2016;35:2425-2429. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

  3. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  4. Optimizing the performance of Hyalella azteca in chronic toxicity tests: Results of feeding studies with various foods and feeding regimes

    Science.gov (United States)

    The freshwater amphipod Hyalella azteca is a common organism used for sediment toxicity testing in the United States and elsewhere. Standard methods for 10-d and 42-d toxicity tests with H. azteca were last revised and published by USEPA/ASTM in 2000. Under the methods in the man...

  5. Effects of an atrazine, metolachlor, and fipronil mixture on Hyalella azteca (Saussure) in a modified backwater wetland

    Science.gov (United States)

    We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a mixture of three pesticides, atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first two hours...

  6. Evaluation of toxicity: Whole-sediment versus overlying-water exposures with amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, C.G.; Ivey, C.D.; Brunson, E.L.; Hardesty, D.K.; Kemble, N.E.

    2000-01-01

    A laboratory study was conducted to evaluate the toxicity of whole-sediment versus overlying-water exposures to the amphipod Hyalella azteca using field-collected sediments. Severe toxic effects (5-63% survival) were observed with amphipods exposed for 10 d in direct contact with sediment. In contrast, amphipods exposed only to overlying water in these sediment exposures did not exhibit any toxic effects.

  7. Modeling chronic dietary cadmium bioaccumulation and toxicity from periphyton to Hyalella azteca.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; Dixon, D George

    2011-07-01

    A chronic (28-d) Cd saturation bioaccumulation model was developed to quantify the Cd contribution from a natural periphyton diet to Cd in the freshwater amphipod Hyalella azteca. Bioaccumulation was then linked to chronic toxic effects. Juvenile H. azteca were exposed to treatments of Cd in water (3.13-100 nmol/L nominal) and food (389-26,300 nmol/g ash-free dry mass). Cadmium bioaccumulation, survival, and growth were recorded. Dietary Cd was estimated to contribute 21 to 31, 59 to 94, and 40 to 55% to bioaccumulated Cd in H. azteca exposed to treatments of Cd primarily in water, food, and food + water, respectively. Survival as a function of Cd lethal body concentration (679 nmol/g; 95% confidence limits, 617-747) was the most robust endpoint. Body concentration integrated all exposure routes. Based on the lethal body concentration, dietary Cd was predicted to contribute markedly (26-90%) to Cd in H. azteca. Cadmium concentration and food nutritional quality (biomass, chlorophyll a, total lipid, fatty acids, total protein) had no effect on H. azteca nutritional quality (total lipid, fatty acids, total protein) but did influence H. azteca dry weight. This research highlighted the importance of including a dietary component when modeling chronic effects of Cd and when refining endpoints for use in ecological risk assessment and water quality guidelines.

  8. The amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining

    Energy Technology Data Exchange (ETDEWEB)

    Couillard, Y. [Existing Substances Division, Science and Risk Assessment Directorate, Environment Canada, Place Vincent Massey, 351 St. Joseph Boulevard, 20th floor, Gatineau, Quebec, K1A 0H3 (Canada)], E-mail: yves.couillard@ec.gc.ca; Grapentine, L.C.; Borgmann, U. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, L7R 4A6 (Canada); Doyle, P. [Existing Substances Division, Science and Risk Assessment Directorate, Environment Canada, Place Vincent Massey, 351 St. Joseph Boulevard, 20th floor, Gatineau, Quebec, K1A 0H3 (Canada); Masson, S. [Parc Aquarium du Quebec, 1675 avenue des Hotels, Quebec, Quebec, Canada G1W 4S3 (Canada)

    2008-12-15

    Specimens of the amphipod Hyalella azteca were deployed, in June-July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi - James Bay region, northwestern Quebec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO{sub 4}{sup 2-} modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents. - Hyalella azteca accumulates dissolved metals in a dose-dependent manner.

  9. Interactive effects of phosphorus and copper on Hyalella azteca via periphyton in aquatic ecosystems.

    Science.gov (United States)

    Li, Miling; Costello, David M; Burton, G Allen

    2012-09-01

    This research examined the interaction between dissolved copper and phosphorus, with respect to their effects on the freshwater amphipod Hyalella azteca feeding on periphyton. Field-collected periphyton communities were exposed to different nutrient and metal conditions in indoor recirculating streams. H. azteca were then exposed to water and periphyton from these streams. There was rapid Cu accumulation by periphyton but the total Cu concentration of periphyton was not directly related to dissolved P. In terms of H. azteca growth, an interactive effect was found between Cu and P as growth was reduced more than expected in the low Cu-high P treatment. Our data suggest that eutrophic conditions result in greater Cu toxicity to benthic macroinvertebrates at lower metal concentrations, likely due to higher assimilation efficiency of dietary Cu from periphyton incubated under eutrophic conditions. These results imply that non-additive interactions between multiple stressors may cause ecosystem effects as detected in standard laboratory bioassays conducted under controlled conditions.

  10. Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosm.

    Science.gov (United States)

    Lizotte, Richard E; Testa, Sam; Locke, Martin A; Steinriede, R Wade

    2013-10-01

    We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures, such as nutrients only (NO) (nitrogen [N], phosphorus [P]), pesticides only (PO) (atrazine, S-metolachlor, permethrin), and nutrients + pesticides on phytoplankton chlorophyll-a, on 48-h aqueous Hyalella azteca survival and 10-day sediment H. azteca survival and growth. Water and sediment were collected at 10-, 20-, and 40-m distances from inflow and analyzed for nutrients, pesticides, chlorophyll-a, and H. azteca laboratory bioassays. Phytoplankton chlorophyll-a increased 4- to 10 -fold at 7 days after NO treatment. However, responses of chlorophyll-a to PO and nutrients + pesticides were more complex with associated decreases at only 20 m for pesticides only and 10 and 40 m for nutrients + pesticides treatments. H. azteca aqueous survival decreased within the first 48 h of dosing at 10- and 20-m distances during PO and nutrients + pesticides treatments in association with permethrin concentrations. H. azteca sediment survival was unaffected, whereas 10-day growth decreased within 1 day of dosing at all sites during nutrients + pesticides treatment. Constructed wetlands were shown to be an effective agricultural best-management tool for trapping pollutants and mitigating ecological impacts of run-off in agricultural watersheds.

  11. Testing sediment biological effects with the freshwater amphipod Hyalella azteca: the gap between laboratory and nature.

    Science.gov (United States)

    Wang, Feiyue; Goulet, Richard R; Chapman, Peter M

    2004-12-01

    The freshwater amphipod, Hyalella azteca, is widely used in laboratory sediment toxicity and bioaccumulation tests. However, its responses in the laboratory are probably very different from those in the field. A review of the literature indicates that in its natural habitat this species complex is primarily epibenthic, derives little nutrition from the sediments, and responds primarily to contaminants in the overlying water column (including water and food), not sediment or porewater. In laboratory sediment toxicity tests H. azteca is deprived of natural food sources such as algal communities on or above the sediments, and is subjected to constant light without any cover except that afforded by burial into the sediments. Under these constraining laboratory conditions, H. azteca has been reported to respond to sediment or porewater contamination. In nature, contamination of overlying water from sediment is less likely than in the laboratory because of the large, generally non-static sink of natural surface water. H. azteca does not appear to be the most appropriate test species for direct assessments of the bioavailability and toxicity of sediment contaminants, though it is probably appropriate for testing the toxicity of surface waters. Toxic and non-toxic responses will be highly conservative, though the latter are probably the most persuasive given the exposure constraints. Thus H. azteca is probably a suitable surrogate species for determining sediments that are likely not toxic to field populations; however, it is not suitable for determining sediments that are likely toxic to field populations.

  12. Effects of copper in flooded Florida agricultural soils on Hyalella azteca.

    Science.gov (United States)

    Hoang, Tham C; Schuler, Lance J; Rand, Gary M

    2009-04-01

    This study examined the uptake and effects of copper (Cu) from flooded agricultural soils to epibenthic amphipods (Hyalella azteca) using 10-day sediment toxicity tests. Soils were collected from 10 citrus agricultural sites in South Florida. One sediment toxicity test was conducted with one flooding of the 10 soils, and based on the results of this test a second sediment toxicity test was conducted with 4 of the soils, after four 14-day flooding and four 14-day drying intervals over 4 months. Sediment toxicity tests were conducted under flow-through conditions using U.S. EPA methodology. Effects on survival, dry weight, and whole-body Cu concentrations of H. azteca were determined. Cu concentrations in overlying water and sediment of both sediment toxicity tests exceeded regulatory criteria for aquatic organisms. Although survival of H. azteca was not consistently affected from the first to the second sediment toxicity tests, dry weight was consistently reduced and related to Cu concentrations in soil, overlying water, and pore water. Furthermore, whole-body tissue Cu concentrations were significantly higher in H. azteca in all 10 soil-water treatments in the first sediment toxicity test and in all 4 soil-water treatments in the second sediment toxicity test compared to controls. Whole-body tissue concentrations and effects on dry weight were related to Cu exposures in soil, overlying water, and pore water. In these managed soil-water systems, small fish consuming H. azteca with high concentrations of Cu may be at risk.

  13. Uptake and speciation of vanadium in the benthic invertebrate Hyalella azteca.

    Science.gov (United States)

    Jensen-Fontaine, Madeleine; Norwood, Warren P; Brown, Mitra; Dixon, D George; Le, X Chris

    2014-01-01

    Vanadium has the potential to leach into the environment from petroleum coke, an oil sands byproduct. To determine uptake of vanadium species in the biota, we exposed the benthic invertebrate Hyalella azteca with increasing concentrations of two different vanadium species, V(IV) and V(V), for seven days. The concentrations of vanadium in the H. azteca tissue increased with the concentration of vanadium in the exposure water. Speciation analysis revealed that V(IV) in the exposure water was oxidized to V(V) between renewal periods, and therefore the animals were mostly exposed to V(V). Speciation analysis of the H. azteca tissue showed the presence of V(V), V(IV), and an unidentified vanadium species. These results indicate the uptake and metabolism of vanadium by H. azteca. Because H. azteca are widely distributed in freshwater systems and are an important food supply for many fish, determining the uptake and metabolism of vanadium allows for a better understanding of the potential environmental effects on invertebrates.

  14. Interlaboratory study of precision: Hyalella azteca and Chironomus tentans freshwater sediment toxicity assays

    Science.gov (United States)

    Burton, G.A.; Norberg-King, T. J.; Ingersoll, C.G.; Benoit, D.A.; Ankley, G.T.; Winger, P.V.; Kubitz, J.; Lazorchak, J.M.; Smith, M.E.; Greer, E.; Dwyer, F.J.; Call, D.J.; Day, K.E.; Kennedy, P.; Stinson, M.

    1996-01-01

    Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.

  15. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, W.P. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada) and Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)]. E-mail: warren.norwood@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Branch, National Water Research Institute, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2006-10-15

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r {sup 2}: 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g{sup -1} appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment. - Bioaccumulation of As, Co, Cr and Mn follow a saturation model in Hyalella azteca and can be useful for environmental assessment.

  16. Effects of an atrazine, metolachlor and fipronil mixture on Hyalella azteca (Saussure) in a modified backwater wetland.

    Science.gov (United States)

    Lizotte, Richard E; Knight, Scott S; Shields, F Douglas; Bryant, Charles T

    2009-12-01

    We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a pesticide mixture of atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first 2 h of amendment at the upstream amendment site but not at any time at the downstream site. H. azteca survival varied spatially and temporally in conjunction with measured pesticide mixture concentrations. Hyalella azteca 96 h survival pesticide mixture effects concentrations ranges were 10.214–11.997, 5.822–6.658, 0.650–0.817, and 0.030–0.048 μg L−1 for atrazine, metolachlor, fipronil, and fipronil-sulfone, respectively.

  17. Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca.

    Science.gov (United States)

    Norwood, W P; Borgmann, U; Dixon, D G

    2006-10-01

    Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r(2): 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g(-1) appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment.

  18. Efficiency of experimental rice (Oryza sativa L.) fields in mitigating diazinon runoff toxicity to Hyalella azteca.

    Science.gov (United States)

    Moore, Matthew T; Lizotte, Richard E; Kröger, Robert

    2009-06-01

    This study assessed the viability of using planted, mature rice fields in mitigating diazinon (an organophosphate insecticide) runoff toxicity using aqueous 48 h Hyalella azteca whole effluent toxicity bioassays. Rice fields decreased diazinon concentrations 80.1%-99.9% compared with 10.8% in the unvegetated field control. H. azteca survival responses coincided with observed diazinon concentrations. Estimated LC50 effects dilutions (%) ranged from 1.15 to 1.47 for inflow samples and 1.66 (unvegetated), 6.44 (rice field A), and >100 (rice field B) outflow samples. Decreases in inflow versus outflow aqueous toxicity were 77.1%-100% in rice fields compared with 18.7% in the unvegetated field.

  19. Diclofenac-enriched artificial sediment induces oxidative stress in Hyalella azteca.

    Science.gov (United States)

    Oviedo-Gómez, Dennis Gloria Carolina; Galar-Martínez, Marcela; García-Medina, Sandra; Razo-Estrada, Celene; Gómez-Oliván, Leobardo Manuel

    2010-01-01

    Diclofenac is a nonsteroidal anti-inflammatory drug widely used in Mexico where it is sold over the counter. It enters water bodies through municipal and industrial discharges, posing a risk to water systems and aquatic organisms. Diclofenac-enriched artificial sediment was used to evaluate the toxicity of this pharmaceutical on the sentinel species Hyalella azteca, using oxidative stress biomarkers in order to determine if the set of tests used in this study is a suitable early damage biomarker. The median lethal concentration (72-h LC(50)) was determined and oxidative stress was evaluated using lipid peroxidation, protein carbonyl content to evaluate oxidized protein content, and the activity of superoxide dismutase, catalase, and glutathione peroxidase. All biomarkers were significantly altered. Diclofenac induces oxidative stress in H. azteca and the set of tests used (lipid peroxidation, protein carbonyl content, antioxidant enzyme activities) constitutes an adequate early damage biomarker for evaluating the toxicity of this pharmaceutical group in aquatic species.

  20. Hyalella azteca (Saussure) responses to Coldwater River backwater sediments in Mississippi, USA.

    Science.gov (United States)

    Knight, Scott S; Lizotte, Richard E; Shields, F Douglas

    2009-10-01

    Sediment from three Coldwater River, Mississippi backwaters was examined using 28 day Hyalella azteca bioassays and chemical analyses for 33 pesticides, seven metals and seven PCB mixtures. Hydrologic connectivity between the main river channel and backwater varied widely among the three sites. Mortality occurred in the most highly connected backwater while growth impairment occurred in the other two. Precopulatory guarding behavior was not as sensitive as growth. Fourteen contaminants (seven metals, seven pesticides) were detected in sediments. Survival was associated with the organochlorine insecticide heptachlor.

  1. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach.

    Science.gov (United States)

    Vukov, Oliver; Smith, D Scott; McGeer, James C

    2016-01-01

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23°C. Acute toxicity tests were done with azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (LogK values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The logK value for Dy(3+) toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and criteria for Dy and possibly REEs in general and offers insight into the complex bio-geochemical nature of this element.

  2. Water-sediment interactions for Hyalella azteca exposed to uranium-spiked sediment

    Energy Technology Data Exchange (ETDEWEB)

    Alves, L.C. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)], E-mail: Lara.Alves@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2008-05-01

    Data on the toxicity of uranium in sediments to Hyalella azteca and the effect of overlying water chemistry are limited. This study exposed H. azteca to sediments spiked with U (0-10,000 {mu}g U/g dry weight) and five different overlying waters, which varied independently in hardness and alkalinity. Water pH had a major effect on U bioavailability and uptake by H. azteca. Uranium toxicity was higher when overlying water pH was low, while desorption of U into the overlying water increased with increasing pH. There appears to be little effect of Ca on U uptake, other than its influence on U speciation. Experiments with caged animals indicate that U accumulation and toxicity occur mainly through the dissolved phase rather than the solid phase. Uranium bioaccumulation is a more reliable indicator of U toxicity than U concentration in water or sediment. Uranium bioaccumulation in the H. azteca and U adsorption to sediment can be satisfactorily explained using saturation models.

  3. Testing Local Adaptation in Five Populations of Hyalella azteca in Northern Alberta's Oil Sands Region.

    Science.gov (United States)

    Beery, Steven R; Gauthier, Patrick T; Pyle, Gregory G

    2017-02-01

    Canada's oil sands hold the third largest petroleum reserves worldwide and have experienced rapid economic growth. The oil sands region provides an ideal location for studying local adaptations through reciprocal transplant (RT) because populations within the region have been historically exposed to naturally occurring bitumen. Our objectives were to (1) determine if Hyalella azteca from habitats within the oil sands region exhibited increased tolerance to constituents associated with industrial bitumen extraction compared with H. azteca from habitats outside the region; and (2) determine if any observed tolerance was attributable to local adaptation. Five populations of H. azteca were reciprocally transplanted from reclaimed and reference wetlands: four from local wetlands plus one naïve laboratory population. Survival, toxicity, and behaviour were measured before and after the RT period. Survival varied by population and site. These results show that the differences in responses among populations are likely not attributable to local adaptation and that laboratory populations of H. azteca provide ecologically relevant results when tested in the field.

  4. Water-sediment interactions for Hyalella azteca exposed to uranium-spiked sediment.

    Science.gov (United States)

    Alves, L C; Borgmann, U; Dixon, D G

    2008-05-01

    Data on the toxicity of uranium in sediments to Hyalella azteca and the effect of overlying water chemistry are limited. This study exposed H. azteca to sediments spiked with U (0-10,000 microg U/g dry weight) and five different overlying waters, which varied independently in hardness and alkalinity. Water pH had a major effect on U bioavailability and uptake by H. azteca. Uranium toxicity was higher when overlying water pH was low, while desorption of U into the overlying water increased with increasing pH. There appears to be little effect of Ca on U uptake, other than its influence on U speciation. Experiments with caged animals indicate that U accumulation and toxicity occur mainly through the dissolved phase rather than the solid phase. Uranium bioaccumulation is a more reliable indicator of U toxicity than U concentration in water or sediment. Uranium bioaccumulation in the H. azteca and U adsorption to sediment can be satisfactorily explained using saturation models.

  5. Agricultural pesticides in Mississippi Delta oxbow lake sediments during autumn and their effects on Hyalella azteca.

    Science.gov (United States)

    Lizotte, Richard E; Knight, Scott S; Bryant, Charles T; Smith, Sammie

    2009-10-01

    Agricultural pesticide contamination of sediments from five Mississippi Delta oxbow lakes and their effects and bioavailablity to Hyalella azteca were assessed during a low-application season-autumn. Three reference oxbow lakes were located in the White River National Wildlife Refuge (WRNWR), Arkansas and two impaired lakes, according to the US Environmental Agency Sect. 303 (d) Clean Water Act, were located in Mississippi. Surface sediment (top 5 cm) was collected at three sites within each lake and analyzed for 17 current and historic-use pesticides and metabolites. Chronic 28-day H. azteca sediment bioassays and pesticide body residue analyses were completed to determine the degree of biological responses and bioavailability. The greatest number of detectable pesticides in WRNWR and 303 (d) sediment samples was 9 and 12, respectively, with historic-use pesticide metabolite, p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] ubiquitous. No significant (p > 0.05) differences in animal survival were observed among sites. Animal growth was significantly (p azteca with current-use pesticides detected at three sites; historic-use pesticides and metabolites detected at 11 sites. Animal body residues of a historic-use pesticide (dieldrin) and metabolite (p,p'-DDE) were associated with observed growth responses. Results show limited current-use pesticide contamination of sediments and H. azteca body tissues during autumn and that historic-use pesticides and metabolites are the primary contributors to observed biological responses.

  6. Influence of chloride on the chronic toxicity of sodium nitrate to Ceriodaphnia dubia and Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy

    2016-09-01

    While it has been well established that increasing chloride concentration in water reduces the toxicity of nitrite to freshwater species, little work has been done to investigate the effect of chloride on nitrate toxicity. We conducted acute and chronic nitrate (as sodium nitrate) toxicity tests with the cladoceran Ceriodaphnia dubia and the amphipod Hyalella azteca (chronic tests only) over a range of chloride concentrations spanning natural chloride levels found in surface waters representative of watersheds of the Great Lakes Region. Chronic nitrate toxicity test results with both crustaceans were variable, with H. azteca appearing to be one of the more sensitive invertebrate species tested and C. dubia being less sensitive. While the variability in results for H. azteca were to an extent related to chloride concentration in test water that was distinctly not the case for C. dubia. We concluded that the chloride dependent toxicity of nitrate is not universal among freshwater crustaceans. An additional sodium chloride chronic toxicity test with the US Lab strain of H. azteca in the present study suggested that when present as predominantly sodium chloride and with relatively low concentrations of other ions, there is a narrow range of chloride concentrations over which this strain is most fit, and within which toxicity test data are reliable.

  7. Pairing behaviour and reproduction in Hyalella azteca as sensitive endpoints for detecting long-term consequences of pesticide pulses

    DEFF Research Database (Denmark)

    Pedersen, Signe; Palmqvist, Annemette; Thorbek, Pernille

    2013-01-01

    The aim of the present study was to examine acute and delayed effects of pulse exposure of the pyrethroid pesticide, permethrin, on precopulatory pairs of Hyalella azteca. Pairs of H. azteca were exposed to a single 1 h pulse of different nominal concentrations of permethrin: 0, 0.3, 0.9 or 2.7 μg....../L, but not 0.3 μg/L, compared to the control groups. The long-term effects of short-term exposure on reproductive behavior of pairs could potentially have consequences for the population dynamics of H. azteca. However, since individual-level responses can both overestimate and underestimate effects...

  8. Oxidized Carbo-Iron causes reduced reproduction and lower tolerance of juveniles in the amphipod Hyalella azteca.

    Science.gov (United States)

    Weil, Mirco; Meißner, Tobias; Springer, Armin; Bundschuh, Mirco; Hübler, Lydia; Schulz, Ralf; Duis, Karen

    2016-12-01

    For in situ remediation of groundwater contaminated by halogenated hydrocarbons Carbo-Iron(®), a composite of microscale activated carbon and nano Fe(0), was developed. Against the background of intended release of Carbo-Iron into the environment in concentrations in the g/L-range, potential ecotoxicological consequences were evaluated in the present study. The nano Fei(0) in Carbo-Iron acts as reducing agent and is oxidized in aqueous systems by chlorinated solvents, groundwater constituents (e.g. dissolved oxygen) and anaerobic corrosion. As Carbo-Iron is generally oxidized rapidly after application into the environment, the oxidized state is environmentally most relevant, and Carbo-Iron was used in its oxidized form in the ecotoxicological tests. The amphipod Hyalella azteca was selected as a surrogate test species for functionally important groundwater crustaceans. Effects of Carbo-Iron on H. azteca were determined in a 10-d acute test, a 7-d feeding activity test and a 42-d chronic test. Additionally, a 56-d life cycle test was performed with a modified design to further evaluate effects of Carbo-Iron on adult H. azteca and their offspring. The size of Carbo-Iron particles in stock and test suspensions was determined via dynamic light scattering. Potential uptake of particles into test organisms was investigated using transmission and scanning electron microscopy. At the termination of the feeding and acute toxicity test (i.e. after 7 and 10 d of exposure, respectively), Carbo-Iron had a significant effect on the weight, length and feeding rate of H. azteca at the highest test concentration of 100mg/L. While an uptake of Carbo-Iron into the gut was observed, no passage into the surrounding tissue was detected. In both chronic tests, the number of offspring was the most sensitive endpoint and significant effects were recorded at concentrations ≥50mg/L (42-d experiment) and ≥12.5mg/L (56-d experiment). Parental exposure to oxidized Carbo-Iron significantly

  9. Interlaboratory testing of 42-d Hyalella azteca survival, growth and reproduction method with sediment and water-only exposures

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have conducted studies to refine the USEPA/ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with Hyalella azteca. In advanc...

  10. Evaluation of the Influence of Bromide or Iodide on the Performance the Amphipod Hyalella azteca in Reconstituted Waters

    Science.gov (United States)

    Survival, growth, or reproduction of the amphipod Hyalella azteca (HA) is reported to be poor when some reconstituted waters have been used to conduct chronic (>14-d) water-only or sediment toxicity tests, including ASTM reconstituted hard water (with no addition of Bromi...

  11. Influence of selected water quality characteristics on the toxicity of lambda-cyhalothrin and gamma-cyhalothrin to Hyalella azteca

    Science.gov (United States)

    This study was conducted to assess the influence of suspended solids, dissolved organic carbon, and phytoplankton (as chlorophyll a) water quality characteristics on lambda-cyhalothrin and gamma-cyhalothrin aqueous toxicity to Hyalella azteca using natural water from 12 ponds and lakes in Mississipp...

  12. Evaluation of the Influence of Bromide or Iodide on the Performance the Amphipod Hyalella azteca in Reconstituted Waters

    Science.gov (United States)

    Survival, growth, or reproduction of the amphipod Hyalella azteca (HA) is reported to be poor when some reconstituted waters have been used to conduct chronic (>14-d) water-only or sediment toxicity tests, including ASTM reconstituted hard water (with no addition of Bromi...

  13. Interlaboratory testing of 42-d Hyalella azteca survival, growth and reproduction method with sediment and water-only exposures

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have conducted studies to refine the USEPA/ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with Hyalella azteca. In advanc...

  14. An assessment of Hyalella azteca burrowing activity under laboratory sediment toxicity testing conditions.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2010-09-01

    Burrowing of the freshwater amphipod Hyalella azteca was evaluated under laboratory conditions similar to those recommended for standard sediment toxicity testing in Canada (EPS 1/RM/33; Environment Canada, 1997) and the United States (EPA/600/R-99/064; US EPA, 2000). Sediment type, time of day (light versus dark), size of animal, and the presence or absence of food were varied to assess their effects on burrowing activity. Hyalella azteca were found to burrow rapidly in fine, organic-rich sediments, but were slower to burrow in a sandy sediment. There was no increase in the number of animals occupying the sediment surface of a fine, organic-rich sediment after 4h of darkness compared to the previous 4h of light. Over a 9- to 10-d duration, a higher percentage of animals occupied the surface of the sandy sediment. The addition of food promoted burrowing in sandy sediment, as did using smaller animals. Overall, longer-duration tests involving older animals and coarse sediments may require formal observation to confirm burrowing and ensure adequate sediment exposure. The addition of food during a test may promote the burrowing of larger animals in coarse sediments, but may not be necessary in field-collected sediments that are not excessively sandy.

  15. 10-Day survival of Hyalella azteca as a function of water quality parameters.

    Science.gov (United States)

    Javidmehr, Alireza; Kass, Philip H; Deanovic, Linda A; Connon, Richard E; Werner, Inge

    2015-05-01

    Estuarine systems are among the most impacted ecosystems due to anthropogenic contaminants; however, they present unique challenges to toxicity testing with regard to varying water quality parameters. The euryhaline amphipod species, Hyalella azteca, is widely used in toxicity testing and well suited for testing estuarine water samples. Nevertheless, the influence of relevant water quality parameters on test endpoints must be quantified in order to efficiently use this species for routine monitoring. Here, we studied the influence of five water quality parameters: electrical conductivity, pH, un-ionized ammonia, dissolved oxygen and temperature, on H. azteca survival in a water column toxicity test. A model was developed to quantify and predict the independent and interacting effects of water quality variables on 10-day survival. The model allows simultaneous assessment of multiple potential predictors recorded during the tests. Data used for modeling came from 1089 tests performed on ambient water samples over a period of three years (2006-2008). The final model reflects significant effects of predictors and their two-way interactions. The effect of each level of all predictors on survival probability of H. azteca was examined by comparing levels of each predictor at a time, while holding all others at their lowest (reference) level. This study showed that predictors of survival in water column tests should not be evaluated in isolation in the interpretation of H. azteca water column tests. Our model provides a useful tool to predict expected control survival based on relevant water quality parameters, and thus enables the use of H. azteca tests for toxicity monitoring in estuaries with a wide range of water quality conditions.

  16. Assessment of the effect of water quality on copper toxicity in Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Richards, L. [Univ. of Guelph, Guelph, Ontario (Canada); Walsh, S.; Shultz, C.; Stuart, M. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2015-06-15

    The objective of this study was to test the hypothesis that when standard artificial media 5-salt culture water (SAM-5S) is used to test sediment toxicity of much lower ionic-strength aquatic ecosystems, the resulting toxicity estimates are lower than if the tests had been conducted in water of comparable ionic strength. Results showed that this concern was unfounded for testing of copper toxicity to Hyalella azteca (H. azteca) in Ottawa River water. Sediment testing is often conducted using a standard water that is prepared in the laboratory. However, this water may have an ionic strength that is different than local water bodies. It follows that laboratory results using the standard water may be unrepresentative. A study was undertaken to assess the copper tolerance of 2 strains of H. azteca in SAM-5S, diluted SAM-5S (similar in electrical conductivity to Ottawa River water), and Ottawa River water. Acute (96 h) copper toxicity tests were conducted with 9-16 day-old H. azteca. For a given water type, the 2 strains of H. azteca yielded comparable responses to copper. The highest copper tolerance was found in Ottawa River water (closely followed by SAM-5S), whereas the lowest copper tolerance was found in diluted SAM-5S. Our results suggest that sediment toxicity is not lowered by the higher ionic strength of SAM-5S and that sediment toxicity tests of Ottawa River sediments, conducted with SAM-5S, can be used to estimate the in situ toxicity of the sediments. (author)

  17. Chronic toxicity of the synthetic hormone 17alpha-ethinylestradiol to Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Dussault, Eve B; Balakrishnan, Vimal K; Solomon, Keith R; Sibley, Paul K

    2008-12-01

    The chronic toxicity of the synthetic hormone 17alpha-ethinylestradiol (EE2) was investigated in two benthic invertebrates, the midge Chironomus tentans and the freshwater amphipod Hyalella azteca, in life-cycle water-only assays. In C. tentans, a 50% decrease in emergence was observed at a concentration of 1.5 mg/L; emergence was a more sensitive endpoint than survival, growth, or biomass. Reproduction was not significantly affected by EE2 exposure until a concentration of 3.1 mg/L, where emergence, and therefore reproduction, did not occur. In contrast, reproduction was the most sensitive endpoint in H. azteca (50% decrease in reproduction observed at a concentration of 0.36 mg/L). The sensitivity of the F1 generation to EE2 was also investigated with H. azteca, but was not different from the F0 generation. The data from the present study were combined with those from previous 10-d toxicity assays, to derive acute to chronic toxicity ratios (ACRs) for EE2. The ACRs calculated for EE2 were 13 for C. tentans and 16 for H. azteca, indicating that the application factors currently used in ecological risk assessment for the derivation of chronic toxicity are protective and conservative for these organisms. The results of the present study suggest that chronic toxicity was not mediated by disruption of endocrine pathways. Using a hazard quotient approach, the risk associated with sublethal exposure to EE2 was azteca and C. tentans, indicating that adverse effects are not expected, and that environmental exposure to EE2 likely poses a low risk to benthic invertebrates.

  18. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach

    Energy Technology Data Exchange (ETDEWEB)

    Vukov, Oliver, E-mail: vuko3930@mylaurier.ca [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Smith, D. Scott [Chemistry Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); McGeer, James C. [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada)

    2016-01-15

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60 mg CaCO{sub 3} mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23 °C. Acute toxicity tests were done with <24 h old neonates for 48 h in the case of D. pulex and with 2–9 days old offspring for 96 h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5–2.0 mM), Na (0.5–2.0 mM) and Mg (0.125–0.5 mM). The effect of pH (6.5–8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13 mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (Log K values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The log K value for Dy{sup 3+} toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific

  19. Effect of test duration and feeding on relative sensitivity of genetically distinct clades of Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy; Major, Kaley M; McEwen, Abigail R

    2013-11-01

    The amphipod Hyalella azteca is widely used in ecotoxicology laboratories for the assessment of chemical risks to aquatic environments, and it is a cryptic species complex with a number of genetically distinct strains found in wild populations. While it would be valuable to note differences in contaminant sensitivity among different strains collected from various field sites, those findings would be influenced by acclimation of the populations to local conditions. In addition, potential differences in metabolism or lipid storage among different strains may confound assessment of sensitivity in unfed acute toxicity tests. In the present study, our aim was to assess whether there are genetic differences in contaminant sensitivity among three cryptic provisional species of H. azteca. Therefore, we used organisms cultured under the same conditions, assessed their ability to survive for extended periods without food, and conducted fed and unfed acute toxicity tests with two anions (nitrate and chloride) whose toxicities are not expected to be altered by the addition of food. We found that the three genetically distinct clades of H. azteca had substantially different responses to starvation, and the presence/absence of food during acute toxicity tests had a strong role in determining the relative sensitivity of the three clades. In fed tests, where starvation was no longer a potential stressor, significant differences in sensitivity were still observed among the three clades. In light of these differences in sensitivity, we suggest that ecotoxicology laboratories consider using a provisional species in toxicity tests that is a regionally appropriate surrogate.

  20. Role of vegetation in a constructed wetland on nutrient-pesticide mixture toxicity to Hyalella azteca.

    Science.gov (United States)

    Lizotte, Richard E; Moore, Matthew T; Locke, Martin A; Kröger, Robert

    2011-02-01

    The toxicity of a nutrient-pesticide mixture in nonvegetated and vegetated sections of a constructed wetland (882 m² each) was assessed using Hyalella azteca 48-h aqueous whole-effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple superphosphate, diazinon, and permethrin simulating storm-event agricultural runoff. Aqueous samples were collected at inflow, middle, and outflow points within each section 5 h, 24 h, 72 h, 7 days, 14 days, and 21 days postamendment. Nutrients and pesticides were detected throughout both wetland sections with concentrations longitudinally decreasing more in vegetated than nonvegetated section within 24 h. Survival effluent dilution point estimates-NOECs, LOECs, and LC₅₀s-indicated greatest differences in toxicity between nonvegetated and vegetated sections at 5 h. Associations of nutrient and pesticide concentrations with NOECs indicated that earlier toxicity (5-72 h) was from permethrin and diazinon, whereas later toxicity (7-21 days) was primarily from diazinon. Nutrient-pesticide mixture concentration-response assessment using toxic unit models indicated that H. azteca toxicity was due primarily to the pesticides diazinon and permethrin. Results show that the effects of vegetation versus no vegetation on nutrient-pesticide mixture toxicity are not evident after 5 h and a 21-day retention time is necessary to improve H. azteca survival to ≥90% in constructed wetlands of this size.

  1. Time-dependent lethal body residues for the toxicity of pentachlorobenzene to Hyalella azteca

    Science.gov (United States)

    Landrum, Peter F.; Steevens, Jeffery A.; Gossiaux, Duane C.; McElroy, Michael; Robinson, Sander; Begnoche, Linda; Chernyak, Sergei; Hickey, James

    2004-01-01

    The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 μmol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.

  2. The amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining.

    Science.gov (United States)

    Couillard, Y; Grapentine, L C; Borgmann, U; Doyle, P; Masson, S

    2008-12-01

    Specimens of the amphipod Hyalella azteca were deployed, in June-July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi-James Bay region, northwestern Québec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO4(2-) modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents.

  3. Response spectrum of pentachlorobenzene and fluoranthene for Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Schuler, Lance J; Landrum, Peter F; Lydy, Michael J

    2007-06-01

    The whole-body residues of pentachlorobenzene (PCBz) and fluoranthene (FLU) in Hyalella azteca and Chironomus tentans were determined for a variety of chronic sublethal effects. The endpoints evaluated for H. azteca included 28-d growth and survival and 42-d growth, survival, and reproduction. Adverse effects to C. tentans also were determined at multiple endpoints including 10-d growth, cumulative pupation and emergence, and reproduction. The lowest-observed-effect residue (LOER) based on whole-body residues associated with growth was consistent between compounds and species tested with concentrations ranging from 0.17 to 0.33 micromol/g. For H. azteca, the most sensitive endpoints were growth at 0.23 micromol/g and reproduction at 0.11 micromol/g for PCBz and FLU, respectively. For C. tentans, the most sensitive endpoints were emergence, development and reproduction at 0.02 micromol/g, and development and reproduction at 0.15 micromol/g for PCBz and FLU, respectively. Compared to residues associated with acute lethality, the most sensitive sublethal endpoints were approximately 4 and 60 times lower for PCBz and FLU, respectively. The relative consistency of the sublethal endpoints suggests that body residues can be a valuable tool to evaluate bioaccumulation data as part of a risk assessment to predict adverse effects to biota.

  4. Kinetics of uranium uptake in soft water and the effect of body size, bioaccumulation and toxicity to Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Alves, L.C. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G., E-mail: dgdixon@uwaterloo.c [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2009-08-15

    The kinetics of uptake and the effect of body size on uranium (U) bioaccumulation and toxicity to Hyalella azteca exposed to water-only U concentrations in soft water were evaluated. The effect of body size on U bioaccumulation was significant with a slope of -0.35 between log body concentration and log body mass. A saturation kinetic model was satisfactory to describe the uptake rate, elimination rate and the effect of gut-clearance on size-corrected U bioaccumulation in H. azteca. The one-week lethal water concentrations causing 50% mortality for juvenile and adult H. azteca were 1100 and 4000 nmol U/L, respectively. The one-week lethal body concentration causing 50% mortality was 140 nmol U/g for juvenile H. azteca and 220 nmol U/g for adult H. azteca. One-week bioaccumulation studies that properly account for body-size and gut-clearance times can provide valuable data on U bioavailability and toxicity in the environment. - Uranium accumulation by Hyalella azteca approaches steady state after one week but is strongly dependent on body size.

  5. Effect of diet quality on chronic toxicity of aqueous lead to the amphipod Hyalella azteca.

    Science.gov (United States)

    Besser, John M; Ivey, Chris D; Brumbaugh, William G; Ingersoll, Christopher G

    2016-07-01

    The authors investigated the chronic toxicity of aqueous Pb to the amphipod Hyalella azteca (Hyalella) in 42-d tests using 2 different diets: 1) the yeast + cereal leaf + trout pellet (YCT) diet, fed at the uniform low ration used in standard methods for sediment toxicity tests; and 2) a new diet of diatoms + TetraMin flakes (DT), fed at increasing rations over time, that has been optimized for use in Hyalella water-only tests. Test endpoints included survival, weight, biomass, fecundity, and total young. Lethal effects of Pb were similar for the DT and YCT tests (20% lethal concentration [LC20] = 13 μg/L and 15 μg/L, respectively, as filterable Pb). In contrast, weight and fecundity endpoints were not significantly affected in the DT test at Pb concentrations up to 63 µg/L, but these endpoints were significantly reduced by Pb in the YCT test-and in a 2005 test in the same laboratory with a diet of conditioned Rabbit Chow (RC-2005). The fecundity and total young endpoints from the YCT and RC-2005 tests were considered unreliable because fecundity in controls did not meet test acceptability criteria, but both of these tests still produced lower Pb effect concentrations (for weight or biomass) than the test with the DT diet. The lowest biotic ligand model-normalized effect concentrations for the 3 tests ranged from 3.7 μg/L (weight 20% effect concentration [EC20] for the RC-2005 test) to 8.2 μg/L (total young EC20 for the DT test), values that would rank Hyalella as the second or third most sensitive of 13 genera in a species sensitivity distribution for chronic Pb toxicity. These results demonstrate that toxicity tests with Hyalella fed optimal diets can meet more stringent test acceptability criteria for control performance, but suggest that results of these tests may underestimate sublethal toxic effects of Pb to Hyalella under suboptimal feeding regimes. Environ Toxicol Chem 2016;35:1825-1834. Published 2015 Wiley Periodicals Inc

  6. Effect of diet quality on chronic toxicity of aqueous lead to the amphipod Hyalella azteca

    Science.gov (United States)

    Besser, John M.; Ivey, Chris D.; Brumbaugh, William G.; Ingersoll, Christopher G.

    2016-01-01

    The authors investigated the chronic toxicity of aqueous Pb to the amphipod Hyalella azteca (Hyalella) in 42-d tests using 2 different diets: 1) the yeastþcereal leafþtrout pellet (YCT) diet, fed at the uniform low ration used in standard methods for sediment toxicity tests; and 2) a new diet of diatomsþTetraMin flakes (DT), fed at increasing rations over time, that has been optimized for use in Hyalella water-only tests. Test endpoints included survival, weight, biomass, fecundity, and total young. Lethal effects of Pb were similar for the DT and YCT tests (20% lethal concentration [LC20]¼13 mg/L and 15mg/L, respectively, as filterable Pb). In contrast, weight and fecundity endpoints were not significantly affected in the DT test at Pb concentrations up to 63 mg/L, but these endpoints were significantly reduced by Pb in the YCT test—and in a 2005 test in the same laboratory with a diet of conditioned Rabbit Chow (RC-2005). The fecundity and total young endpoints from the YCT and RC-2005 tests were considered unreliable because fecundity in controls did not meet test acceptability criteria, but both of these tests still produced lower Pb effect concentrations (for weight or biomass) than the test with the DT diet. The lowest biotic ligand model–normalized effect concentrations for the 3 tests ranged from 3.7mg/L (weight 20% effect concentration [EC20] for the RC-2005 test) to 8.2 mg/L (total young EC20 for the DT test), values that would rank Hyalella as the second or third most sensitive of 13 genera in a species sensitivity distribution for chronic Pb toxicity. These results demonstrate that toxicity tests with Hyalella fed optimal diets can meet more stringent test acceptability criteria for control performance, but suggest that results of these tests may underestimate sublethal toxic effects of Pb to Hyalella under suboptimal feeding regimes.

  7. Use of sublethal endpoints in sediment toxicity tests with the amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, Chris G.; Brunson, Eric L.; Dwyer, F. James; Hardesty, Douglas K.; Kemble, Nile E.

    1998-01-01

    Short-term sediment toxicity tests that only measure effects on survival can be used to identify high levels of contamination but may not be able to identify marginally contaminated sediments. The objective of the present study was to develop a method for determining the potential sublethal effects of contaminants associated with sediment on the amphipod Hyalella azteca (e.g., reproduction). Exposures to sediment were started with 7- to 8-d-old amphipods. On day 28, amphipods were isolated from the sediment and placed in water-only chambers where reproduction was measured on day 35 and 42. Typically, amphipods were first in amplexus at about day 21 to 28 with release of the first brood between day 28 to 42. Endpoints measured included survival (day 28, 35, and 42), growth (as length and weight on day 28 and 42), and reproduction (number of young/female produced from day 28 to 42). This method was used to evaluate a formulated sediment and field-collected sediments with low to moderate concentrations of contaminants. Survival of amphipods in these sediments was typically >85% after the 28-d sediment exposures and the 14-d holding period in water to measure reproduction. Reproduction was more variable than growth; hence, more replicates might be needed to establish statistical differences among treatments. Previous studies have demonstrated that growth of H. azteca in sediment tests often provides unique information that can be used to discriminate toxic effects of exposure to contaminants. Either length or weight can be measured in sediment tests with H. azteca. However, additional statistical options are available if length is measured on individual amphipods, such as nested analysis of variance that can account for variance in length within replicates. Ongoing water-only studies testing select contaminants will provide additional data on the relative sensitivity and variability of sublethal endpoints in toxicity tests with H. azteca.

  8. A simple control for sediment-toxicity exposures using the amphipod, Hyalella azteca.

    Science.gov (United States)

    Lasier, Peter J; Urich, Matthew L

    2014-09-01

    Sediment-toxicity exposures comparing survival and growth of the freshwater amphipod, Hyalella azteca, are often components of aquatic-habitat assessments. Standardized exposure methods have been established and require evaluations for quality assurance. Test acceptability using performance-based criteria can be determined from exposures to control sediments, which are collected from the environment or formulated from commercially available components. Amending sand with leached alfalfa solids provided a simple formulated sediment that elicited consistently acceptable survival and growth in 28-day exposures with and without a daily feeding regime. A procedure is described for preparing the sediment along with results from comparisons among sand, amended sand, and field-collected sediments that incorporated three feeding regimes.

  9. Synergistic effect of piperonyl butoxide on acute toxicity of pyrethrins to Hyalella azteca.

    Science.gov (United States)

    Giddings, Jeffrey; Gagne, James; Sharp, Janice

    2016-08-01

    A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrin toxicity. Concentrations of PBO <4 µg/L caused no toxicity enhancement, whereas toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrin toxicity (decrease in median lethal concentration) of 1.4-fold to 1.6-fold and varied only slightly between 4 µg/L and 15 µg/L PBO, whereas direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. The results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. Environ Toxicol Chem 2016;35:2111-2116. © 2016 SETAC.

  10. Effects of depleted uranium on the health and survival of Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Kuhne, W.W.; Caldwell, C.A.; Gould, W.R.; Fresquez, P.R.; Finger, S.

    2002-01-01

    Depleted uranium (DU) has been used as a substitute for the fissionable enriched uranium component of atomic weapons tested at Los Alamos National Laboratory (LANL) (Los Alamos, NM, USA) since the early 1950s, resulting in considerable concentrations of DU in the soils within the test sites. Although the movement of DU into major aquatic systems has been shown to be minimal, there are many small-order ephemeral streams and areas of standing water in canyons throughout LANL that may be affected by inputs of DU via runoff, erosion, and leaching. Ninety-six-hour acute and 7-d chronic toxicity assays were conducted to measure the toxicity of DU on survival and reproduction of Ceriodaphnia dubia. A 14-d water-only assay was conducted to measure survival and growth of Hyalella azteca. The estimated median lethal concentration (LC50) to produce 50% mortality of the test population for the 96-h Ceriodaphnia dubia assay was 10.50 mg/L. Reproductive effects occurred at a lowest-observable-effect concentration ???3.91 mg/L with a no-observable-effect concentration of 1.97 mg/L. The estimated 14-d LC50 for the Hyalella azteca assay was 1.52 mg/L No significant relationship was detected between growth and DU concentrations. Concentrations at which toxicity effects were observed in this study for both invertebrates exceeded concentrations of total uranium observed in runoff from LANL lands. Thus, it is likely that current runoff levels of uranium do not pose a threat to these types of aquatic invertebrates.

  11. NMR-based metabolomics for the environmental assessment of Kaohsiung Harbor sediments exemplified by a marine amphipod (Hyalella azteca).

    Science.gov (United States)

    Chiu, K H; Dong, C D; Chen, C F; Tsai, M L; Ju, Y R; Chen, T M; Chen, C W

    2017-03-03

    Inflow of wastewater from upstream causes a large flux of pollutants to enter Kaohsiung Harbor in Taiwan daily. To reveal the ecological risk posed by Kaohsiung Harbor sediments, an ecological metabolomic approach was employed to investigate environmental factors pertinent to the physiological regulation of the marine amphipod Hyalella azteca. The amphipods were exposed to sediments collected from different stream inlets of the Love River (LR), Canon River (CR), Jen-Gen River (JR), and Salt River (SR). Harbor entrance 1 (E1) was selected as a reference site. After 10-day exposure, metabolomic analysis of the Hyalella azteca revealed differences between two groups: {E1, LR, CR} and {JR, SR}. The metabolic pathways identified in the two groups of amphipods were significantly different. The results demonstrated that NMR-based metabolomics can be effectively used to characterize metabolic response related to sediment from polluted areas.

  12. Effect of gut clearance on metal body concentrations in Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, P.T.M.; Borgmann, U.; Norwood, W. [Environment Canada, Burlington, Ontario (Canada)

    1999-05-01

    Gut content can contribute significantly to the metal body burdens in sediment-exposed Hyalella azteca even if it has no direct effect on toxicity. To determine the duration and the effect of gut clearance on total body concentrations, the authors exposed H. azteca for 1 week to a spiked sediment (lead, cadmium, zinc, and copper); a second set of amphipods was kept in cages above the sediment. Following transfer into clean water (25 C) for 96 h, lead and zinc concentrations showed a biphasic decline, with a stronger decrease in the first 4 to 6 h, when gut clearance contributes significantly to metal loss. After 6 h, metal loss was apparently due to excretion from the body. Without gut clearance, the body concentrations of lead and zinc in sediment-exposed amphipods were overestimated by 438 and 44%, respectively. Gut clearance did not have a visible effect on cadmium and copper body burdens because the body and sediment concentrations were similar. After a depuration time of 6 h, direct excretion from the body resulted in a drop of less than 10% in the total body burdens of lead, cadmium, zinc, and copper compared to the gut-corrected time-zero body burdens. After 24 h, this loss increased up to 27%. Feeding during the depuration period did not have a significant influence on gut clearance. A model that allows estimation of the influence of gut content on the total body concentration of undepurated invertebrates from the bioconcentration factor is evaluated.

  13. Genotype and toxicity relationships among Hyalella azteca: II. Acute exposure to fluoranthene-contaminated sediment

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y.; Guttman, S.I.; Oris, J.T.; Huang, X.; Burton, G.A.

    2000-05-01

    This study examined the genotypic responses of Hyalella azteca to the toxicity of sediment contaminated by the polycyclic aromatic hydrocarbon (PAH) fluoranthene. The authors monitored the time to death for 696 H. azteca exposed to ultraviolet light and sediment spiked with fluoranthene. The survival distribution functions within the genotypes at each of these variable allozyme loci (acid phosphatase [ACP*], glucose-6-phosphate isomerase [GPI*], and phosphoglucomutase [PGM*]) were compared using a long-rank test. Results showed significant differences among SDFs at all three loci. No association of heterozygosity with time to death was observed. The homozygote ACP*-CC was associated with decreased survivorship compared with ACP*-AA, ACP*-BB, and ACP*-AB. However, GPI*-AA was associated with increased survivorship compared with GPI*-BB, GPI*-CC, and GPI*-BC. Significant differences in resistance also were observed for PGM*-BB versus either PGM*-AC or PGM*-BC. These results indicate that differential resistance to PAH phototoxicity was genetically related, producing significant alteration in the frequencies of several genotypes in the population.

  14. Decamethylcyclopentasiloxane (D5) spiked sediment: bioaccumulation and toxicity to the benthic invertebrate Hyalella azteca.

    Science.gov (United States)

    Norwood, W P; Alaee, M; Sverko, E; Wang, D; Brown, M; Galicia, M

    2013-10-01

    Chronic toxicity and bioaccumulation of decamethylcyclopentasiloxane (D5) to Hyalella azteca was examined in a series of spiked sediment exposures. Juvenile H. azteca were exposed for 28d (chronic) to a concentration series of D5 in two natural sediments of differing organic carbon content (O.C.) and particle size composition. The chronic, LC50s were 191 and 857μgD5g(-1) dry weight for Lakes Erie (0.5% O.C.) and Restoule (11% O.C.) respectively. Inhibition of growth only occurred with the L. Restoule spiked sediment with a resultant EC25 of 821μgg(-1)dw. Lethality was a more sensitive endpoint than growth inhibition. Biota sediment accumulation factors (BSAFs, 28d) were <1 indicating that D5 did not bioconcentrate based on lipid normalized tissue concentrations and organic carbon normalized sediment concentrations. Organic carbon (OC) in the sediment appeared to be protective, however normalization to OC did not normalize the toxicity. Normalization of D5 concentrations in the sediments to sand content did normalize the toxicity and LC50 values of 3180 and 3570μg D5g(-1) sand dw were determined to be statistically the same.

  15. Influence of container adsorption upon observed pyrethroid toxicity to Ceriodaphnia dubia and Hyalella azteca

    Science.gov (United States)

    Wheelock, Craig E.; Miller, Jeff L.; Miller, Mike J.; Phillips, Bryn M.; Gee, Shirley J.; Tjeerdema, Ronald S.; Hammock, Bruce D.

    2006-01-01

    Pyrethroid insecticides are known for their potential toxicity to aquatic invertebrates and many fish species. A significant problem in the study of pyrethroid toxicity is their extreme hydrophobicity. They can adsorb to test container surfaces and many studies, therefore, report pyrethroid levels as nominal water concentrations. In this study, pyrethroid adsorption to sampling and test containers was measured and several container treatments were examined for their ability to decrease pyrethroid adsorption. None of the chemical treatments were successful at preventing pyrethroid loss from aqueous samples, but vortexing of containers served to resuspend pyrethroids. The effects of the observed adsorption on Ceriodaphnia dubia and Hyalella azteca permethrin toxicity were examined. Species-specific results showed a time-dependent decrease in toxicity following pyrethroid adsorption to test containers for C. dubia, but not for H. azteca. These results demonstrate that pyrethroid adsorption to containers can significantly affect the observed outcome in toxicity-testing and serves as a caution for researchers and testing laboratories. PMID:15951033

  16. Comparative sensitivity of field and laboratory populations of Hyalella azteca to the pyrethroid insecticides bifenthrin and cypermethrin.

    Science.gov (United States)

    Clark, Stephen L; Ogle, R Scott; Gantner, Andrew; Hall, Lenwood W; Mitchell, Gary; Giddings, Jeffrey; McCoole, Matthew; Dobbs, Michael; Henry, Kevin; Valenti, Ted

    2015-10-01

    Hyalella azteca are epibenthic invertebrates that are widely used for toxicity studies. They are reported to be more sensitive to pyrethroid insecticides than most other test species, which has prompted considerable use of this species in toxicity testing of ambient surface waters where the presence of pyrethroids is suspected. However, resident H. azteca have been found in some ambient water bodies reported to contain surface water and/or sediment pyrethroid concentrations that are toxic to laboratory reared H. azteca. This observation suggests differences in the sensitivities of laboratory reared and field populations of H. azteca to pyrethroids. The goal of the present study was to determine the sensitivities of laboratory reared and field populations of H. azteca to the pyrethroids bifenthrin and cypermethrin. Specimens of H. azteca were collected from resident populations at field sites that are subject to varied land-use activities as well as from laboratory populations. These organisms were exposed to bifenthrin- or cypermethrin-spiked water in 96-h water-only toxicity tests. The resulting data demonstrated that: 1) field-collected populations in urban and agricultural settings can be >2 orders of magnitude less sensitive to the pyrethroids than laboratory reared organisms; 2) field-collected organisms varied in their sensitivity (possibly based on land-use activities), with organisms collected from undeveloped sites exhibiting sensitivities similar to laboratory reared organisms; and 3) the sensitivity of field-collected "tolerant" organisms increased in subsequent generations reared under laboratory conditions. Potential mechanisms for these differences are discussed.

  17. The common ecotoxicology laboratory strain of Hyalella azteca is genetically distinct from most wild strains sampled in eastern North America.

    Science.gov (United States)

    Major, Kaley; Soucek, David J; Giordano, Rosanna; Wetzel, Mark J; Soto-Adames, Felipe

    2013-11-01

    The amphipod Hyalella azteca is commonly used as a model for determining safe concentrations of contaminants in freshwaters. The authors sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene for representatives of 38 populations of this species complex from US and Canadian toxicology research laboratories and eastern North American field sites to determine their genetic relationships. With 1 exception, all US and Canadian laboratory cultures sampled were identified as conspecific. In 22 wild populations spanning 5 US states and 1 Canadian province, the commonly occurring laboratory species was found only in northern Florida, USA. Therefore, the diversity of the H. azteca species complex detected in the wild is not accurately represented in North American laboratories, questioning the reliability of H. azteca cultures currently in use to accurately predict the responses of wild populations in ecotoxicological assays. The authors also examined the utility of different COI nucleotide fragments presently in use to determine phylogenetic relationships in this group and concluded that saturation in DNA sequences leads to inconsistent relationships between clades. Amino acid sequences for COI were not saturated and may allow a more accurate phylogeny estimate. Hyalella azteca is crucial for developing water-quality regulations; therefore, laboratories should know and standardize the strain(s) they use to confidently compare toxicity tests across laboratories and determine whether they are an appropriate surrogate for their regions.

  18. Single versus combined exposure of Hyalella azteca to zinc contaminated sediment and food.

    Science.gov (United States)

    Nguyen, Lien T H; Muyssen, Brita T A; Janssen, Colin R

    2012-03-01

    The amphipod Hyalella azteca was exposed for 28 d to different combinations of Zn contaminated sediment and food. Sediment exposure (+clean food) resulted in increased Zn body burdens, increased mortality and decreased body mass when the molar concentrations of simultaneously extracted Zn were greater than the molar concentration of Acid Volatile Sulfide (SEM(Zn)-AVS>0), suggesting that dissolved Zn was a dominant route of exposure. No adverse effect was noted in the food exposure (+clean sediment), suggesting selective feeding or regulation. Combined exposure (sediment+food) significantly increased adverse effects in comparison with sediment exposure, indicating contribution of dietary Zn to toxicity and bioaccumulation. The observed enhanced toxicity also supports the assumption on the presence of an avoidance/selective feeding reaction of the amphipods in the single sediment or food exposures. During 14 d post-exposure in clean medium, the organisms from the same combined exposure history received two feeding regimes, i.e. clean food and Zn spiked food. Elevated Zn bioaccumulation and reduced reproduction were noted in amphipods that were offered Zn spiked food compared to the respective organisms that were fed clean food. This was explained by the failure of avoidance/selective feeding behavior in the absence of an alternative food source (sediment), forcing the amphipods to take up Zn while feeding. Increasing Zn body burdens rejected the assumption that Zn uptake from food was regulated by H. azteca. Our results show that the selective feeding behavior should be accounted for when assessing ecological effects of Zn or other contaminants, especially when contaminated food is a potential exposure route.

  19. A field assessment of long-term laboratory sediment toxicity tests with the amphipod Hyalella azteca

    Science.gov (United States)

    Ingersoll, Christopher G.; Wang, Ning; Hayward, Jeannie M. R.; Jones, John R.; Jones, Susan B.; Ireland, D. Scott

    2005-01-01

    Response of the amphipod Hyalella azteca exposed to contaminated sediments for 10 to 42 d in laboratory toxicity tests was compared to responses observed in controlled three-month invertebrate colonization exposures conducted in a pond. Sediments evaluated included a sediment spiked with dichlorodiphenyldichloroethane (DDD) or dilutions of a field sediment collected from the Grand Calumet River (GCR) in Indiana (USA) (contaminated with organic compounds and metals). Consistent effects were observed at the highest exposure concentrations (400 ??g DDD/goc [DDD concentrations normalized to grams of organic carbon (goc) in sedimentl or 4% GCR sediment) on survival, length, and reproduction of amphipods in the laboratory and on abundance of invertebrates colonizing sediments in the field. Effect concentrations for DDD observed for 10-d length and 42-d reproduction of amphipods (e.g., chronic value [ChV] of 66 ??g DDD/goc and 25% inhibition concentration [IC25] of 68 ??g DDD/goc for reproduction) were similar to the lowest effect concentrations for DDD measured on invertebrates colonizing sediment the field. Effect concentrations for GCR sediment on 28-d survival and length and 42-d reproduction and length of amphipods (i.e., ChVs of 0.20-0.66% GCR sediment) provided more conservative effect concentrations compared to 10-d survival or length of amphipods in the laboratory or the response of invertebrates colonizing sediment in the field (e.g., ChVs of 2.2% GCR sediment). Results of this study indicate that use of chronic laboratory toxicity tests with H. azteca and benthic colonization studies should be used to provide conservative estimates of impacts on benthic communities exposed to contaminated sediments. Bioaccumulation of DDD by oligochaetes colonizing the DDD-spiked sediment was similar to results of laboratory sediment tests previously conducted with the oligochaete Lumbriculus variegates, confirming that laboratory exposures can be used to estimate

  20. A comparison of the sublethal and lethal toxicity of four pesticides in Hyalella azteca and Chironomus dilutus.

    Science.gov (United States)

    Hasenbein, Simone; Connon, Richard E; Lawler, Sharon P; Geist, Juergen

    2015-08-01

    Laboratory toxicity testing is the primary tool used for surface water environmental risk assessment; however, there are critical information gaps regarding the sublethal effects of pesticides. In 10-day exposures, we assessed the lethal and sublethal (motility and growth) toxicities of four commonly used pesticides, bifenthrin, permethrin, cyfluthrin, and chlorpyrifos, on two freshwater invertebrates, Chironomus dilutus and Hyalella azteca. Pyrethroids were more toxic than the organophosphate chlorpyrifos in both species. Bifenthrin was most toxic to H. azteca survival and growth. Cyfluthrin was most toxic to C. dilutus. However, cyfluthrin had the greatest effect on motility on both H. azteca and C. dilutus. The evaluated concentrations of chlorpyrifos did not affect C. dilutus motility or growth, but significantly impacted H. azteca growth. Motility served as the most sensitive endpoint in assessing sublethal effects at low concentrations for both species, while growth was a good indicator of toxicity for all four pesticides for H. azteca. The integration of sublethal endpoints in ambient water monitoring and pesticide regulation efforts could improve identification of low-level pesticide concentrations that may eventually cause negative effects on food webs and community structure in aquatic environments.

  1. Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains of Hyalella azteca.

    Science.gov (United States)

    Soucek, David J; Mount, David R; Dickinson, Amy; Hockett, J Russell; McEwen, Abigail R

    2015-10-01

    The strain of Hyalella azteca (Saussure: Amphipoda) commonly used for aquatic toxicity testing in the United States has been shown to perform poorly in some standardized reconstituted waters frequently used for other test species. In 10-d and 42-d experiments, the growth and reproduction of the US laboratory strain of H. azteca was shown to vary strongly with chloride concentration in the test water, with declining performance observed below 15 mg/L to 20 mg/L. In contrast to the chloride-dependent performance of the US laboratory strain of H. azteca, growth of a genetically distinct strain of H. azteca obtained from an Environment Canada laboratory in Burlington, Ontario, Canada, was not influenced by chloride concentration. In acute toxicity tests with the US laboratory strain of H. azteca, the acute toxicity of sodium nitrate increased with decreasing chloride in a pattern similar not only to that observed for control growth, but also to previous acute toxicity testing with sodium sulfate. Subsequent testing with the Burlington strain showed no significant relationship between chloride concentration and the acute toxicity of sodium nitrate or sodium sulfate. These findings suggest that the chloride-dependent toxicity shown for the US laboratory strain may be an unusual feature of that strain and perhaps not broadly representative of aquatic organisms as a whole.

  2. Bioassays with caged hyalella azteca to determine in situ toxicity downstream of two Saskatchewan, Canada, uranium operations.

    Science.gov (United States)

    Robertson, Erin L; Liber, Karsten

    2007-11-01

    The main objectives of this in situ study were to evaluate the usefulness of an in situ bioassay to determine if downstream water bodies at the Key Lake and Rabbit Lake uranium operations (Saskatchewan, Canada) were toxic to Hyalella azteca and, if toxicity was observed, to differentiate between the contribution of surface water and sediment contamination to in situ toxicity. These objectives were achieved by performing 4-d in situ bioassays with laboratory-reared H. azteca confined in specially designed, paired, surface water and sediment exposure chambers. Results from the in situ bioassays revealed significant mortality, relative to the respective reference site, at the exposure sites at both Key Lake (p azteca at both operations, although this relationship was stronger at Key Lake. At Key Lake, the primary cause of aquatic toxicity to H. azteca did not appear to be correlated with the variables measured in this study, but most likely with a pulse of organic mill-process chemicals released during the time of the in situ study-a transient event that was caused by a problem with the mill's solvent extraction process. The suspected cause of in situ toxicity to H. azteca at Rabbit Lake was high levels of uranium in surface water, sediment, and pore water.

  3. Influence of dissolved organic matter on nickel bioavailability and toxicity to Hyalella azteca in water-only exposures.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2006-03-10

    Dissolved organic matter (DOM) is known to reduce the bioavailability of metals in aquatic systems. This study evaluated the effects of DOM from various sources (e.g., Little Bear Lake sediment, Suwannee River, peat moss) and various DOM fractions (humic acids, HA; fulvic acids, FA) on the bioavailability of nickel (Ni) to Hyalella azteca, a common freshwater benthic invertebrate. In particular, this study was conducted to evaluate the effect of surficial sediment DOM on Ni bioavailability. Short-term (48 h) acute toxicity tests with H. azteca conducted in synthetic water demonstrated that the aqueous Ni concentrations required for lethality were greater than what could be significantly complexed by environmentally relevant concentrations of dissolved organic carbon (DOC: 0.6-30.4 mg/L). At Ni concentrations sublethal to H. azteca (500 microg/L), the bioavailability of Ni was significantly reduced in the presence of representative surface water DOC concentrations regardless of DOC source or fraction. DOC fraction (i.e., FA and HA) differentially affected Ni speciation, but had little or no effect on Ni accumulation by H. azteca. Tissue Ni was found to be strongly dependent upon the Ni(2+) concentration in the exposure solutions and the Ni:DOC ratio. Overall, the concentration of DOC played a greater role than either DOC source or fraction in determining Ni speciation and hence bioavailability and toxicity to H. azteca.

  4. Kinetics of uranium uptake in soft water and the effect of body size, bioaccumulation and toxicity to Hyalella azteca.

    Science.gov (United States)

    Alves, L C; Borgmann, U; Dixon, D G

    2009-01-01

    The kinetics of uptake and the effect of body size on uranium (U) bioaccumulation and toxicity to Hyalella azteca exposed to water-only U concentrations in soft water were evaluated. The effect of body size on U bioaccumulation was significant with a slope of -0.35 between log body concentration and log body mass. A saturation kinetic model was satisfactory to describe the uptake rate, elimination rate and the effect of gut-clearance on size-corrected U bioaccumulation in H. azteca. The one-week lethal water concentrations causing 50% mortality for juvenile and adult H. azteca were 1100 and 4000 nmol U/L, respectively. The one-week lethal body concentration causing 50% mortality was 140 nmol U/g for juvenile H. azteca and 220 nmol U/g for adult H. azteca. One-week bioaccumulation studies that properly account for body-size and gut-clearance times can provide valuable data on U bioavailability and toxicity in the environment.

  5. Bioavailability-based toxicity endpoints of bifenthrin for Hyalella azteca and Chironomus dilutus.

    Science.gov (United States)

    Harwood, Amanda D; Landrum, Peter F; Lydy, Michael J

    2013-01-01

    Recent studies have determined that techniques, such as solid phase microextraction (SPME) fibers and Tenax beads, can predict bioaccumulation and potentially could predict toxicity for several compounds and species. Toxicity of bifenthrin was determined using two standard sediment toxicity tests with the benthic species Hyalella azteca and Chironomus dilutus in three reference sediments with different characteristics. The objectives of the current study were to establish bioavailability-based median lethal concentrations (LC50) and median effect concentrations (EC50) of the pyrethroid insecticide bifenthrin, compare their ability to assess toxicity to the use of whole sediment concentrations, as well as to make comparisons of the concentrations derived using each method in order to make assessments of accuracy and extrapolation potential. Four metrics were compared including SPME fiber concentration, pore water concentration derived using SPMEs, 6 h Tenax extractable concentration, and 24 h Tenax extractable concentration. The variation among the LC50s and EC50s in each sediment derived using bioavailability-based methods was comparable to variation among organic carbon normalized sediment concentrations, but improved over whole sediment concentrations. There was a significant linear relationship between SPME or Tenax and organic carbon normalized sediment concentrations. Additionally, there was a significant relationship between the SPME and Tenax concentrations across sediments. The significant linear relationship between SPME and Tenax concentrations further demonstrates that these bioavailability-based endpoints are interrelated. This study derived bioavailability-based benchmarks that may prove to be more accurate than sediment-based ones in predicting toxicity across sediment types.

  6. Toxicity of four sulfonamide antibiotics to the freshwater amphipod Hyalella azteca.

    Science.gov (United States)

    Bartlett, Adrienne J; Balakrishnan, V K; Toito, J; Brown, L R

    2013-04-01

    Sulfonamides are a widely used class of antibiotics; however, there are few toxicological data available with which to conduct environmental risk assessments for these compounds. Therefore, the toxicity of four sulfonamides (sulfaguanidine, sulfathiazole, sulfamerazine, and sulfasalazine) to Hyalella azteca was assessed in chronic (four-week), water-only exposures. Survival was evaluated weekly, and growth was measured at the end of the test. Four-week lethal concentrations associated with 50% mortality (LC50s) for sulfaguanidine, sulfathiazole, and sulfamerazine were 0.90, 1.6, and 3.9 µM, respectively. Sulfaguanidine caused effects on survival more quickly and at lower concentrations than sulfathiazole or sulfamerazine. These differences were more pronounced at week 1 than week 4, when sulfaguanidine LC50s were 8 to 20 times lower and 2 to 4 times lower, respectively. Growth was affected by sulfathiazole but was a less sensitive end point than survival, with an effective concentration associated with 50% reduction in growth (EC50) of 13 µM, whereas sulfaguanidine and sulfamerazine caused negligible effects on growth. Sulfasalazine had no effect on survival or growth at any concentration tested, up to 13 µM. The effects observed in the present study occurred at concentrations exceeding those typically found in environmental waters. However, given that LC50s decreased with exposure duration (except for sulfasalazine), the present study demonstrates the importance of conducting longer-term tests to adequately assess the environmental toxicity of sulfonamides.

  7. Lac Dufault sediment core trace metal distribution, bioavailability and toxicity to Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Nowierski, Monica [Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Dixon, D. George [Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Borgmann, Uwe [National Water Research Institute, Canada Centre for Inland Waters, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario L7R 4A6 (Canada)]. E-mail: uwe.borgmann@ec.gc.ca

    2006-02-15

    To determine changes in metal distribution, bioavailability and toxicity with sediment depth, two 20-cm-long replicate cores were collected from a lake historically subjected to the influence of metal mining and smelting activity. The vertical distribution of Pb, Cd and Cu in sediment was similar for all three metals, with the surface layers showing enrichment and the deeper (pre-industrial) layers showing lower concentrations. Toxicity of each sediment core section was determined in laboratory tests with the freshwater amphipod Hyalella azteca. Bioavailable metal in each sediment slice was estimated from metal concentrations in overlying water in these toxicity tests and, for Cd, also from metal bioaccumulation. The profile for Cd in tissue was comparable to Cd in sediment and overlying water, but relative Cd bioavailability from sediment increased with sediment depth. Survival increased with increasing sediment depth, suggesting that surface sediments were probably less or non-toxic before industrialization. - Toxicity and bioaccumulation tests with sediment cores provide more information on biological effects of metals than surface sediment tests.

  8. Acute and chronic toxicity of lead in water and diet to the amphipod Hyalella azteca

    Science.gov (United States)

    Besser, J.M.; Brumbaugh, W.G.; Brunson, E.L.; Ingersoll, C.G.

    2005-01-01

    We evaluated the influence of waterborne and dietary lead (Pb) exposure on the acute and chronic toxicity of Pb to the amphipod Hyalella azteca. Test solutions were generated by a modified diluter with an extended (24-h) equilibration period. Acute (96-h) toxicity of Pb varied with water hardness in the range of 71 to 275 mg/L as CaCO3, despite similar dissolved Pb concentrations. Acute toxicity was greatest in soft test water, with less than 50% survival at the lowest dissolved Pb concentration (151 ??g/L). Survival also was significantly reduced in medium-hardness water but not in hard test water. In chronic (42-d) studies, amphipods were exposed to waterborne Pb and fed either a control diet or a diet equilibrated with waterborne Pb levels. For animals fed the control diet, the median lethal concentration (LC50) for Pb was 24 ??g/L (as dissolved Pb), and significant reductions in survival occurred at 16 ??g/L. Exposure to Pb-treated diets significantly increased toxicity across a wide range of dissolved Pb concentrations, with a LC50 of 16 ??g/L and significant reductions in growth and reproduction at 3.5 ??g/L. Significant effects on growth and reproduction occurred at dissolved Pb concentrations close to the current U.S. chronic water-quality criterion. Our results suggest that both aqueous- and dietary-exposure pathways contribute significantly to chronic Pb exposure and toxic effects in aquatic biota. ?? 2005 SETAC.

  9. Fish and land use influence Gammarus lacustris and Hyalella azteca (Amphipoda) densities in large wetlands across the upper Midwest

    Science.gov (United States)

    Anteau, Michael J.; Afton, Alan D.; Anteau, Andrea C.E.; Moser, E. Barry

    2011-01-01

    Gammarus lacustrisK/i> and Ki>Hyalella azteca (hereafter G. lacustris and H. azteca, respectively) are important components of secondary production in wetlands and shallow lakes of the upper Midwest, USA. Within the past 50 years, amphipod densities have decreased while occurrences of fish and intensity of agricultural land use have increased markedly across this landscape. We investigated influences of fish, sedimentation, and submerged aquatic vegetation (SAV) on densities of G. lacustris and H. azteca in semipermanent and permanent wetlands and shallow lakes (n = 283) throughout seven eco-physiographic regions of Iowa, Minnesota, and North Dakota during 2004–2005. G. lacustris and H. azteca densities were positively correlated with densities of SAV (P P P = 0.01 and P = 0.013, respectively) and with high densities of fathead minnows (Pimephales promelas; P P = 0.033, respectively). H. azteca densities also were negatively correlated with densities of small fish (e.g., other minnows [Cyprinidae] and sticklebacks [Gasterosteidae]; P = 0.048) and common carp (Cyprinus spp.; P = 0.022). G. lacustris densities were negatively correlated with high levels of suspended solids (an index for sedimentation; P H. azteca densities were positively correlated with the width of upland-vegetation buffers (P = 0.004). Our results indicate that sedimentation and fish reduce amphipod densities and may contribute to the current low densities of amphipods in the upper Midwest. Thus, removing/excluding fish, and providing a thick buffer of upland vegetation around wetlands may help restore amphipod densities and wetland and water quality within this landscape.

  10. Multiple origins of pyrethroid insecticide resistance across the species complex of a nontarget aquatic crustacean, Hyalella azteca.

    Science.gov (United States)

    Weston, Donald P; Poynton, Helen C; Wellborn, Gary A; Lydy, Michael J; Blalock, Bonnie J; Sepulveda, Maria S; Colbourne, John K

    2013-10-08

    Use of pesticides can have substantial nonlethal impacts on nontarget species, including driving evolutionary change, often with unknown consequences for species, ecosystems, and society. Hyalella azteca, a species complex of North American freshwater amphipods, is widely used for toxicity testing of water and sediment and has frequently shown toxicity due to pyrethroid pesticides. We demonstrate that 10 populations, 3 from laboratory cultures and 7 from California water bodies, differed by at least 550-fold in sensitivity to pyrethroids. The populations sorted into four phylogenetic groups consistent with species-level divergence. By sequencing the primary pyrethroid target site, the voltage-gated sodium channel, we show that point mutations and their spread in natural populations were responsible for differences in pyrethroid sensitivity. At least one population had both mutant and WT alleles, suggesting ongoing evolution of resistance. Although nonresistant H. azteca were susceptible to the typical neurotoxic effects of pyrethroids, gene expression analysis suggests the mode of action in resistant H. azteca was not neurotoxicity but was oxidative stress sustained only at considerably higher pyrethroid concentrations. The finding that a nontarget aquatic species has acquired resistance to pesticides used only on terrestrial pests is troubling evidence of the impact of chronic pesticide transport from land-based applications into aquatic systems. Our findings have far-reaching implications for continued uncritical use of H. azteca as a principal species for monitoring and environmental policy decisions.

  11. Oxidative stress induced in Hyalella azteca by an effluent from a NSAID-manufacturing plant in Mexico.

    Science.gov (United States)

    Novoa-Luna, Karen Adriana; Romero-Romero, Rubí; Natividad-Rangel, Reyna; Galar-Martínez, Marcela; SanJuan-Reyes, Nely; García-Medina, Sandra; Martínez-Vieyra, Catalina; Neri-Cruz, Nadia; Gómez-Oliván, Leobardo Manuel

    2016-09-01

    Production in the pharmaceutical industry has increased and along with it, the amount of wastewater of various characteristics and contaminant concentrations. The main chemicals in these effluents are solvents, detergents, disinfectants-such as sodium hypochlorite (NaClO)-and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the oxidative stress induced in the amphipod Hyalella azteca by the effluent from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. The median lethal concentration (72 h-LC50) was determined and H. azteca were exposed to the lowest observed adverse effect level (0.0732 %) for 12, 24, 48 and 72 h, and biomarkers of oxidative stress were evaluated [hydroperoxide content (HPC), lipid peroxidation (LPX), protein carbonyl content (PCC), and the activity of the superoxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)]. Statistically significant increases with respect to the control group (P azteca at all exposure times. Antioxidant enzymes activity SOD, CAT and GPx activity also increased significantly (P azteca.

  12. Toxicity of sediment-associated pesticides to Chironomus dilutus and Hyalella azteca.

    Science.gov (United States)

    Ding, Yuping; Weston, Donald P; You, Jing; Rothert, Amanda K; Lydy, Michael J

    2011-07-01

    Two hundred sediment samples were collected and their toxicity evaluated to aquatic species in a previous study in the agriculturally dominated Central Valley of California, United States. Pyrethroid insecticides were the main contributors to the observed toxicity. However, mortality in approximately one third of the toxic samples could not be explained solely by the presence of pyrethroids in the matrices. Hundreds of pesticides are currently used in the Central Valley of California, but only a few dozen are analyzed in standard environmental monitoring. A significant amount of unexplained sediment toxicity may be due to pesticides that are in widespread use that but have not been routinely monitored in the environment, and even if some of them were, the concentrations harmful to aquatic organisms are unknown. In this study, toxicity thresholds for nine sediment-associated pesticides including abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin were established for two aquatic species, the midge Chironomus dilutus and the amphipod Hyalella azteca. For midges, the median lethal concentration (LC₅₀) of the pesticides ranged from 0.18 to 964 μg/g organic carbon (OC), with abamectin being the most toxic and propargite being the least toxic pesticide. A sublethal growth endpoint using average individual ash-free dry mass was also measured for the midges. The no-observable effect concentration values for growth ranged from 0.10 to 633 μg/g OC for the nine pesticides. For the amphipods, fenpropathrin was the most toxic, with an LC₅₀ of 1-2 μg/g OC. Abamectin, diazinon, and methyl parathion were all moderately toxic (LC₅₀s 2.8-26 μg/g OC). Dicofol, indoxacarb, oxyfluorfen, propargite, and pyraclostrobin were all relatively nontoxic, with LC₅₀s greater than the highest concentrations tested. The toxicity information collected in the present study will be helpful in decreasing the

  13. Survival, growth, and body residues of Hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms

    Science.gov (United States)

    We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g-1) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fip...

  14. Chronic TiO2 nanoparticle exposure to a benthic organism, Hyalella azteca: Impact of solar UV radiation and material surface coatings on toxicity

    Science.gov (United States)

    The present study examined the chronic toxicity of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca, using an industry standard, P25, and a coated nano-TiO2 used in commercial products. There is limited information on the chronic effects of nano...

  15. Chronic TiO2 nanoparticle exposure to a benthic organism, Hyalella azteca: Impact of solar UV radiation and material surface coatings on toxicity

    Science.gov (United States)

    The present study examined the chronic toxicity of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca, using an industry standard, P25, and a coated nano-TiO2 used in commercial products. There is limited information on the chronic effects of nano...

  16. Chronic toxicity of arsenic, cobalt, chromium and manganese to Hyalella azteca in relation to exposure and bioaccumulation

    Energy Technology Data Exchange (ETDEWEB)

    Norwood, W.P. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada) and Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada)]. E-mail: warren.norwood@ec.gc.ca; Borgmann, U. [Aquatic Ecosystems Protection Research Division, Environment Canada, P.O. Box 5050, Burlington, ON L7R 4A6 (Canada); Dixon, D.G. [Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2007-05-15

    Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model relative to total-body or water metal concentration. LBC25s (total-body metal concentrations resulting in 25% mortality in 4 weeks) were 125, 103, 152 and 57,900 nmol g{sup -1} dry weight for As, Co, Cr and Mn respectively. LC50s (metal concentrations in water resulting in 25% mortality in 4 weeks) were 5600, 183, 731, and 197,000 nmol L{sup -1}, respectively. A hormesis growth response to As exposure was observed. Growth was a more variable endpoint than mortality for all four toxicants; however, confidence limits based on growth and mortality all overlapped, except Cr which had no effect on growth. Mn toxicity was greater in glass test containers compared to plastic. Bioaccumulation of As, Co, Cr, and Mn was strongly correlated with, and is useful for predicting, chronic mortality. - Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model in relationship to total-body or water metal concentration.

  17. Bioaccumulation of the synthetic hormone 17alpha-ethinylestradiol in the benthic invertebrates Chironomus tentans and Hyalella azteca.

    Science.gov (United States)

    Dussault, Eve B; Balakrishnan, Vimal K; Borgmann, Uwe; Solomon, Keith R; Sibley, Paul K

    2009-09-01

    The present study investigated the bioaccumulation of the synthetic hormone 17alpha-ethinylestradiol (EE2) in the benthic invertebrates Chironomus tentans and Hyalella azteca, in water-only and spiked sediment assays. Water and sediment residue analysis was performed by LC/MS-MS, while biota extracts were analyzed using both LC/MS-MS and a recombinant yeast estrogen receptor assay. At the lowest exposure concentration, C. tentans accumulated less EE2 than H. azteca in the water-only assays (p=0.0004), but due to different slopes, this difference subsided with increasing concentrations; at the exposure concentration of 1mg/L, C. tentans had a greater body burden than H. azteca (p=0.02). In spiked sediments, C. tentans had the greatest EE2 accumulation (1.2+/-0.14 vs. 0.5+/-0.05 microg/gdw, n=4). Measurements in H. azteca indicated a negligible contribution from the sediments to the uptake of EE2 in this species. These differences were likely due to differences in the behavior and life history of the two species (epibenthic vs. endobenthic). Water-only bioaccumulation factors (BAFs) calculated at the lowest exposure concentration were significantly smaller in C. tentans than in H. azteca (31 vs. 142, respectively; pazteca (0.8 vs. 0.3; p<0.0001). Extracts of the exposed animals caused a response in a recombinant yeast estrogen receptor assay, thus confirming the estrogenic activity of the samples, presumably from EE2 and its estrogenic metabolites. The results of the present study suggest that consumption of invertebrate food items could provide an additional source of exposure to estrogenic substances in vertebrate predators.

  18. Greatly reduced bioavailability and toxicity of polycyclic aromatic hydrocarbons to Hyalella azteca in sediments from manufactured-gas plant sites.

    Science.gov (United States)

    Kreitinger, Joseph P; Neuhauser, Edward F; Doherty, Francis G; Hawthorne, Steven B

    2007-06-01

    The toxicity of polycyclic aromatic hydrocarbons (PAHs) to Hyalella azteca, was measured in 34 sediment samples collected from four manufactured-gas plant (MGP) sites ranging in total PAH16 (sum of 16 U.S. Environmental Protection Agency priority pollutant PAHs) concentrations from 4 to 5700 mg/kg, total organic carbon content from 0.6 to 11%, and soot carbon from 0.2 to 5.1%. The survival and growth of H. azteca in 28-d bioassays were unrelated to total PAH concentration, with 100% survival in one sediment having 1,730 mg/kg total PAH16, whereas no survival was observed in sediment samples with concentrations as low as 54 mg/kg total PAH16. Twenty-five of the 34 sediment samples exceeded the probable effects concentration screening value of 22.8 mg/kg total PAH13 (sum of 13 PAHs) and equilibrium partitioning sediment benchmarks for PAH mixtures (on the basis of the measurement of 18 parent PAHs and 16 groups of alkylated PAHs, [PAH34]); yet, 19 (76%) of the 25 samples predicted to be toxic were not toxic to H. azteca. However, the toxicity of PAHs to H. azteca was accurately predicted when either the rapidly released concentrations as determined by mild supercritical fluid extraction (SFE) or the pore-water concentrations were used to establish the bioavailability of PAHs. These results demonstrate that the PAHs present in many sediments collected from MGP sites have low bioavailability and that both the measurement of the rapidly released PAH concentrations with mild SFE and the dissolved pore-water concentrations of PAHs are useful tools for estimating chronic toxicity to H. azteca.

  19. The evaluation of 3 diets for rearing Hyalella azteca and the influence of diet on acute ammonia toxicity.

    Science.gov (United States)

    Kennedy, Lisa M; Watson-Leung, Trudy L; Poirier, David G

    2016-10-01

    Three Hyalella azteca cultures were reared on different diets since birth, reflecting the recommended diets of various investigators. The 3 diets consisted of fish flakes (FF), a mixture of fish flakes supplemented with the diatom Thalassiosira weissflogii (FF-D), and a mixture of fish flakes supplemented with yeast, cereal grass media, and trout chow (FF-YCT). The 3 diets were evaluated by comparing 20 wk of culturing data, along with the organism's response to standard 96-h toxicity testing with ammonium chloride over a range of pH and temperature. Hyalella azteca fed the FF-D diet had the highest overall survival rate (96.6%, standard deviation [SD] 4.3%) compared to those fed the FF diet (92.0%, SD 12.7%), or the FF-YCT diet (91.1%, SD 14.8%), although difference in survival was not statistically significant. Organisms fed the FF-D diet produced a higher number of young per week per adult (6.1, SD 2.8) than the FF diet (5.1, SD 2.2), or the FF-YCT diet (4.0, SD 1.2), although differences were not statistically significant. Of the diets evaluated, H. azteca reared on the FF-D diet were often significantly more resistant to total and un-ionized ammonia toxicity in acute 96-h testing than those reared on the other 2 diets across the 2 temperatures and 5 pHs tested, suggesting this may be the most optimal diet for this species. Environ Toxicol Chem 2016;35:2416-2424. © 2016 SETAC.

  20. Survival and precopulatory guarding behavior of Hyalella azteca (Amphipoda) exposed to nitrate in the presence of atrazine.

    Science.gov (United States)

    Pandey, Ram B; Adams, Ginny L; Warren, Laurie W

    2011-05-01

    Nitrate is one of the most commonly detected contaminants found in aquatic systems with other pesticides such as atrazine. The current study examined potential combined effects of nitrate and atrazine on adults of the freshwater amphipod Hyalella azteca, using survival and precopulatory guarding behavior as toxic endpoints. Although significant differences in acute toxicity with nitrate alone and in binary combination with atrazine (200 µg/L) in water-only tests were not consistently observed for each time point, potential biologically relevant trends in the data were observed. Posttest growth and behavioral observations (10-day period) conducted after 96-hour exposure suggested that atrazine and nitrate at these concentrations did not result in delayed effects on H. azteca. However, when test conditions were modified from standard toxicity tests by feeding amphipods, nitrate was found to be more toxic, with a reduction in median lethal concentration (LC50) values of approximately 80%. We also demonstrated that nitrate exhibits a dose-response effect on precopulatory guarding behavior of H. azteca, suggesting that reproductive effects may occur at environmentally relevant concentrations.

  1. Relative toxicity of bifenthrin to Hyalella azteca in 10 day versus 28 day exposures.

    Science.gov (United States)

    Anderson, Brian S; Phillips, Bryn M; Voorhees, Jennifer P; Petersen, Megan A; Jennings, Lydia L; Fojut, Tessa L; Vasquez, Martice E; Siegler, Catherine; Tjeerdema, Ronald S

    2015-04-01

    Many watersheds in the Central Valley region of California are listed as impaired due to pyrethroid-associated sediment toxicity. The Central Valley Regional Water Quality Control Board is developing numeric sediment quality criteria for pyrethroids, beginning with bifenthrin. Criteria are being developed using existing data, along with data from 10 d and 28 d toxicity tests with Hyalella azteca conducted as part of the current study. A single range-finder and 2 definitive tests were conducted for each test duration. Median lethal concentrations (LC50s), as well as LC20s and inhibition concentrations (IC20s) were calculated based on measured whole sediment bifenthrin concentrations and interstitial water concentrations. Sediment LC50s were also corrected for organic C content. Average LC50s were not significantly different in 10 d versus 28 d tests with H. azteca: 9.1 and 9.6 ng/g bifenthrin for 10 d and 28 d tests, respectively. Average LC20 values were also similar with concentrations at 7.1 and 7.0 for 10 d and 28 d tests, respectively. Bifenthrin inhibition concentrations (IC20s) based on amphipod growth were variable, particularly in the 28 d tests, where a clear dose-response relationship was observed in only 1 of the definitive experiments. Average amphipod growth IC20s were 3.9 and 9.0 ng/g for 10 d and 28 d tests, respectively. Amphipod growth calculated as biomass resulted in IC20s of 4.1 and 6.3 ng/g for the 10 d and 28 d tests, respectively. Lack of a clear growth effect in the longer term test may be related to the lack of food adjustment to account for amphipod mortality in whole sediment exposures. The average C-corrected LC50s were 1.03 and 1.09 μg/g OC for the 10 d and 28 d tests, respectively. Interstitial water LC50s were determined as the measured dissolved concentration of bifenthrin relative to interstitial water dissolved organic carbon. The average LC50s for dissolved interstitial water bifenthrin were

  2. Examining impacts of current-use pesticides in Southern Ontario using in situ exposures of the amphipod Hyalella azteca.

    Science.gov (United States)

    Bartlett, Adrienne J; Struger, John; Grapentine, Lee C; Palace, Vince P

    2016-05-01

    In situ exposures with Hyalella azteca were used to assess impacts of current-use pesticides in Southern Ontario, Canada. Exposures were conducted over 2 growing seasons within areas of high pesticide use: 1 site on Prudhomme Creek and 3 sites on Twenty Mile Creek. Three sites on Spencer Creek, an area of low pesticide use, were added in the second season. Surface water samples were collected every 2 wk to 3 wk and analyzed for a suite of pesticides. Hyalella were exposed in situ for 1 wk every 4 wk to 6 wk, and survival and acetylcholinesterase (AChE) activity were measured. Pesticides in surface waters reflected seasonal use patterns: lower concentrations in spring and fall and higher concentrations during summer months. Organophosphate insecticides (chlorpyrifos, azinphos methyl, diazinon) and acid herbicides (2,4-dichlorophenoxyacetic acid [2,4-D], mecoprop) were routinely detected in Prudhomme Creek, whereas neutral herbicides (atrazine, metolachlor) dominated the pesticide signature of Twenty Mile Creek. Spencer Creek contained fewer pesticides, which were measured at lower concentrations. In situ effects also followed seasonal patterns: higher survival and AChE activity in spring and fall, and lower survival and AChE activity during summer months. The highest toxicity was observed at Prudhomme Creek and was primarily associated with organophosphates. The present study demonstrated that current-use pesticides in Southern Ontario were linked to in situ effects and identified sites of concern requiring further investigation.

  3. Genotype and toxicity relationships among Hyalella azteca: I. Acute exposure to metals or low pH

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Y.; Guttman, S.I.; Oris, J.T.; Bailer, A.J.

    2000-05-01

    Comparative genotype and toxin interactions at three polymorphic enzyme loci were examined in a laboratory population of amphipods (Hyalella azteca) during acute exposure to cadmium, zinc, copper, lead, or low pH. Significant toxin-genotype interactions were observed using logistic regression to model mortality in ten of 15 analyses. Both stressor-specific and nonspecific modes of selection were observed. In general, low pH selected for different genotypes than those selected by metals, especially zinc. Different modes of selection were also observed when amphipods were exposed to different metals. These results suggest that exposure to low pH would significantly reduce the ability of H. azteca to survive subsequent contamination by metals; exposure to stressors in the reverse order would also compromise a population's chance of survival. A genetic distance analysis showed that the magnitude of genetic differentiation consistently increased among survivors compared with that of the initial populations. These increases in genetic divergence estimates suggest that acute exposure to metals or low pH may have an evolutionarily significant impact on the species. They also suggest that both genotype frequency and genetic distance measures (based on allozyme data) may be used as bioindicators for environmental monitoring programs. Validation of such bioindicators requires an understanding of the population's genetic background, genetic structure, and history.

  4. Screening differentially expressed genes in an amphipod (Hyalella azteca) exposed to fungicide vinclozolin by suppression subtractive hybridization.

    Science.gov (United States)

    Wu, Yun H; Wu, Tsung M; Hong, Chwan Y; Wang, Yei S; Yen, Jui H

    2014-01-01

    Vinclozolin, a dicarboximide fungicide, is an endocrine disrupting chemical that competes with an androgenic endocrine disruptor compound. Most research has focused on the epigenetic effect of vinclozolin in humans. In terms of ecotoxicology, understanding the effect of vinclozolin on non-target organisms is important. The expression profile of a comprehensive set of genes in the amphipod Hyalella azteca exposed to vinclozolin was examined. The expressed sequence tags in low-dose vinclozolin-treated and -untreated amphipods were isolated and identified by suppression subtractive hybridization. DNA dot blotting was used to confirm the results and establish a subtracted cDNA library for comparing all differentially expressed sequences with and without vinclozolin treatment. In total, 494 differentially expressed genes, including hemocyanin, heatshock protein, cytochrome, cytochrome oxidase and NADH dehydrogenase were detected. Hemocyanin was the most abundant gene. DNA dot blotting revealed 55 genes with significant differential expression. These genes included larval serum protein 1 alpha, E3 ubiquitin-protein ligase, mitochondrial cytochrome c oxidase, mitochondrial protein, proteasome inhibitor, hemocyanin, zinc-finger-containing protein, mitochondrial NADH-ubiquinone oxidoreductase and epididymal sperm-binding protein. Vinclozolin appears to upregulate stress-related genes and hemocyanin, related to immunity. Moreover, vinclozolin downregulated NADH dehydrogenase, related to respiration. Thus, even a non-lethal concentration of vinclozolin still has an effect at the genetic level in H. azteca and presents a potential risk, especially as it would affect non-target organism hormone metabolism.

  5. TRACKING PYRETHROID TOXICITY IN SURFACE WATER SAMPLES: EXPOSURE DYNAMICS AND TOXICITY IDENTIFICATION TOOLS FOR LABORATORY TESTS WITH HYALELLA AZTECA (AMPHIPODA).

    Science.gov (United States)

    Deanovic, Linda A; Stillway, Marie; Hammock, Bruce G; Fong, Stephanie; Werner, Inge

    2017-09-09

    Pyrethroid insecticides are commonly used in pest control and are present at toxic concentrations in surface waters of agricultural and urban areas worldwide. Monitoring is challenging due to their high hydrophobicity and low toxicity thresholds, which often fall below the detection limits of analytical methods. Standard daphnid bioassays used in surface water monitoring are not sensitive enough to protect more susceptible invertebrate species such as the amphipod, Hyalella azteca, and chemical loss during toxicity testing is of concern. In this study, we quantified toxicity loss during storage and testing, using both natural and synthetic water, and present a tool to enhance toxic signal strength for improved sensitivity of H. azteca toxicity tests. The average half-life during storage in LDPE cubitainers at 4°C of five pyrethroids (permethrin, bifenthrin, lambda-cyhalothrin, cyfluthrin, esfenvalerate) and one organophosphate (chlorpyrifos; used as reference) was 1.4 d, and piperonyl butoxide (PBO) proved an effective tool to potentiate toxicity. We conclude that toxicity tests on ambient water samples containing these hydrophobic insecticides are likely to underestimate toxicity present in the field, and mimic short pulse rather than continuous exposures. Where these chemicals are of concern, the addition of PBO during testing can yield valuable information on their presence or absence. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Pairing behavior and reproduction in Hyalella azteca as sensitive endpoints for detecting long-term consequences of pesticide pulses.

    Science.gov (United States)

    Pedersen, Signe; Palmqvist, Annemette; Thorbek, Pernille; Hamer, Mick; Forbes, Valery

    2013-11-15

    The aim of the present study was to examine acute and delayed effects of pulse exposure of the pyrethroid pesticide, permethrin, on precopulatory pairs of Hyalella azteca. Pairs of H. azteca were exposed to a single 1h pulse of different nominal concentrations of permethrin: 0, 0.3, 0.9 or 2.7 μg/L. During exposure, pairing behavior was observed, and during a 56 day post-exposure period the treatments were monitored for pairing behavior, survival and reproductive output. All permethrin-exposed pairs separated within minutes during exposure and shortly thereafter became immobile; however they regained mobility after transfer to clean water. The time to re-form pairs was significantly longer in all tested concentrations compared to the control, although all surviving pairs re-formed within the 56 day test period. Nevertheless not all pairs exposed to 0.9 and 2.7 μg/L reproduced. Furthermore the numbers of juveniles produced by pairs exposed to 0.9 and 2.7 μg/L, but not 0.3 μg/L, were lower throughout the entire post-exposure period compared to the control groups, and the total numbers of juveniles produced during 56 days were significantly lower in organisms exposed to 0.9 and 2.7 μg/L, but not 0.3 μg/L, compared to the control groups. The long-term effects of short-term exposure on reproductive behavior of pairs could potentially have consequences for the population dynamics of H. azteca. However, since individual-level responses can both overestimate and underestimate effects at the population level, appropriate population models are needed to reduce the uncertainty in extrapolating between these levels of biological organization.

  7. Responses of Hyalella azteca and phytoplankton to a simulated agricultural runoff event in a managed backwater wetland.

    Science.gov (United States)

    Lizotte, Richard E; Shields, F Douglas; Murdock, Justin N; Knight, Scott S

    2012-05-01

    We assessed the aqueous toxicity mitigation capacity of a hydrologically managed floodplain wetland following a synthetic runoff event amended with a mixture of sediments, nutrients (nitrogen and phosphorus), and pesticides (atrazine, S-metolachlor, and permethrin) using 48-h Hyalella azteca survival and phytoplankton pigment, chlorophyll a. The runoff event simulated a 1h, 1.27 cm rainfall event from a 16 ha agricultural field. Water (1L) was collected every 30 min within the first 4h, every 4h until 48 h, and on days 5, 7, 14, 21, and 28 post-amendment at distances of 0, 10, 40, 300 and 500 m from the amendment point for chlorophyll a, suspended sediment, nutrient, and pesticide analyses. H. azteca 48-h laboratory survival was assessed in water collected at each site at 0, 4, 24, 48 h, 5 d and 7 d. Greatest sediment, nutrient, and pesticide concentrations occurred within 3h of amendment at 0m, 10 m, 40 m, and 300 m downstream. Sediments and nutrients showed little variation at 500 m whereas pesticides peaked within 48 h but at azteca survival significantly decreased within 48 h of amendment up to 300 m in association with permethrin concentrations. Chlorophyll a decreased within the first 24h of amendment up to 40m primarily in conjunction with herbicide concentrations. Variations in chlorophyll a at 300 and 500 m were associated with nutrients. Managed floodplain wetlands can rapidly and effectively trap and process agricultural runoff during moderate rainfall events, mitigating impacts to aquatic invertebrates and algae in receiving aquatic systems.

  8. Inter-laboratory validation of organism recovery for use in 42 day sediment toxicity tests with Hyalella azteca.

    Science.gov (United States)

    Taylor, Lisa N; Novak, Lesley

    2016-10-03

    Environment and Climate Change Canada (ECCC) has developed a 42 day sediment toxicity test that includes a reproduction endpoint with the freshwater amphipod Hyalella azteca. The new methodology conducts the entire exposure in sediment; in contrast to existing standardized methods where adults are transferred to a water-only exposure before release of their first brood at Day 28. This mid-test transfer to clean water was due to the results of a juvenile H. azteca recovery trial conducted in the 1990s which concluded that reproductive endpoints could be biased because of low recovery of young amphipods from sediment. Using a new procedure and reduced volume of sediment, an inter-laboratory recovery trial was conducted using 2 to 5 day old H. azteca added to control sediment. A total of 29 technicians from eight laboratories participated in the present study. The average recovery for all laboratories and all technicians was 76% (Coefficient of Variation (CV) = 30%). Based on an initial target recovery of at least 80%, 19 out of 29 (66%) of technicians met this criterion, with an average recovery for this group of 88% (CV = 8.3%). Factors that reduced recovery success included: not using a light table, technicians with minimal sediment testing experience and the use of imported young amphipods with limited acclimation. Excluding those results, the overall average recovery which included 17 participating technicians, increased from 76 to 88% and lowered the CV from 30 to 8.6%. Based on these results, ECCC will recommend ≥85% average recovery of young in control sediment and require ≥80% as a technician performance criterion in its new test design for the reproduction methodology. This article is protected by copyright. All rights reserved.

  9. Sediment Zn-release during post-drought re-flooding: Assessing environmental risk to Hyalella azteca and Daphnia magna.

    Science.gov (United States)

    Nedrich, Sara M; Burton, G Allen

    2017-11-01

    Hydrologic variability exacerbated by climate change affects biogeochemical cycling in sediments through changes in pH, redox, and microbial activity. These alterations affect the lability and speciation of metals, such that toxicity may be observed in otherwise non-toxic sediments. In this study, we investigate the effects of drought and reflooding on metal bioavailability in sediments with low to moderate concentrations of Zn (18-270 mg kg(-1)). Sediments were collected from coastal wetlands in Michigan, dried (36-days) and re-inundated in lab microcosms. We investigated the relationships between key parameters, for surface/porewater (dissolved and particulate metals, dissolved oxygen, redox (Eh), reduced iron, and temperature) and sediment (simultaneously extracted metals (SEM), acid volatile sulfide (AVS), Fe/Mn-oxyhydroxide, organic carbon, water content analyses, and diffusive gradient in thin films (DGTs) metal concentrations). Porewater Zn increased with inundation of dried sediments for all sediment types, exceeding United States Environmental Protection Agency (U.S. EPA) chronic criteria for freshwater organisms, and decreased as sediments became reduced. Effects on Hyalella azteca (7-day exposure) and Daphnia magna (10-day exposure) were quantified. Results show decreased growth of H. azteca for sites with elevated Zn and increased Zn-body concentration (BCZn) in the most contaminated sediment type. Further, BCZn was negatively correlated with H. azteca growth. D. magna survival, growth, and reproduction were not affected. DGT metal concentrations were more reflective of porewater than organism bioaccumulation. Outcomes of predictive toxicology methods are compared to toxicity test results and suggestions are provided for model improvements. This study demonstrates that post-drought re-flooding of sediments affects Zn biogeochemical cycling with potentially adverse effects on benthic organisms, even in sediments with only moderately elevated

  10. Validation of a chronic dietary cadmium bioaccumulation and toxicity model for Hyalella azteca exposed to field-contaminated periphyton and lake water.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; Dixon, D George

    2011-11-01

    A model previously developed in the laboratory to predict chronic bioaccumulation and toxicity of cadmium to Hyalella azteca from a diet of periphyton was validated by comparing predictions with measurements of Cd in two exposure scenarios: laboratory-cultured H. azteca exposed for 28 d to field-contaminated water and periphyton, and Cd measured in field-collected H. azteca. In both exposure scenarios, model predictions of bioaccumulation were shown to be robust; however, effects on Cd bioaccumulation from complexation with dissolved organic carbon (DOC) and inhibition of Cd bioaccumulation by Ca²⁺ must be incorporated into the model to permit its wider application. The model predicted that 80 to 84% of Cd in H. azteca came from periphyton when H. azteca were chronically exposed to dissolved Cd in lake water at 2.63 to 3.01 nmol/L and periphyton at 1,880 to 2,630 nmol/g ash-free dry mass. Dietary Cd contributed markedly to the model-predicted decrease in 28-d survival to 74% at environmental Cd concentrations in food and water. In reality, survival decreased to 10%. The lower than predicted survival likely was due to the higher nutritional quality of periphyton used to develop the model in the laboratory compared with the field-collected periphyton. Overall, this research demonstrated that Cd in a periphyton diet at environmental concentrations can contribute to chronic toxicity in H. azteca.

  11. Cadmium bioavailability to Hyalella azteca from a periphyton diet compared to an artificial diet and application of a biokinetic model

    Energy Technology Data Exchange (ETDEWEB)

    Golding, Lisa A., E-mail: lisa.golding@csiro.au [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Borgmann, Uwe [Environment Canada, 867 Lakeshore Road, Burlington, Ontario L7R 4A6 (Canada); George Dixon, D. [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2013-01-15

    Differences between the bioavailability of cadmium in a periphyton diet and an artificial laboratory diet (TetraMin{sup Registered-Sign }) have important consequences for predicting bioaccumulation and toxicity in the freshwater amphipod Hyalella azteca. The assimilation efficiency (AE) of Cd was compared between periphyton and TetraMin{sup Registered-Sign} at low (1510 and 358 nmol/g ash-free dry mass respectively) and chronically lethal (31,200 and 2890 nmol/g ash-free dry mass respectively) Cd concentrations and in fresh and dry forms using a {sup 109}Cd radiotracer pulse-chase feeding technique. Assimilation efficiency of Cd from periphyton (AE = 3-14%) was lower than that for TetraMin{sup Registered-Sign} (AE = 44-86%) regardless of Cd concentration or food form. Ingestion rate (IR) was lower for dry than fresh forms of periphyton (0.042 and 0.16 g AFDM/g H. azteca/day respectively) and TetraMin{sup Registered-Sign} (0.19 and 0.87 AFDM/g H. azteca/day respectively) and depuration rate (k{sub e}) did not differ statistically with food type, form or Cd concentration (0.032-0.094 d{sup -1}). Biokinetic models with parameters of AE, IR and k{sub e} were used to estimate bioaccumulation from the separate food types. These estimates were compared to those from an independent chronic Cd saturation bioaccumulation model. While the model estimates did not concur, a sensitivity analysis indicated that AE and IR were the most influential biokinetic model parameters for Cd in periphyton and TetraMin{sup Registered-Sign} respectively. It was hypothesized that AE was underestimated for Cd in periphyton due to a non-adapted gut enzyme system and IR was overestimated for Cd in TetraMin{sup Registered-Sign} due to an initial rapid ingestion phase in H. azteca's feeding habits. This research demonstrated the importance of using ecologically relevant food types in laboratory experiments and verifying acute biokinetic model predictions of dietary metal contribution with

  12. Cadmium bioavailability to Hyalella azteca from a periphyton diet compared to an artificial diet and application of a biokinetic model.

    Science.gov (United States)

    Golding, Lisa A; Borgmann, Uwe; George Dixon, D

    2013-01-15

    Differences between the bioavailability of cadmium in a periphyton diet and an artificial laboratory diet (TetraMin(®)) have important consequences for predicting bioaccumulation and toxicity in the freshwater amphipod Hyalella azteca. The assimilation efficiency (AE) of Cd was compared between periphyton and TetraMin(®) at low (1510 and 358 nmol/g ash-free dry mass respectively) and chronically lethal (31,200 and 2890 nmol/g ash-free dry mass respectively) Cd concentrations and in fresh and dry forms using a (109)Cd radiotracer pulse-chase feeding technique. Assimilation efficiency of Cd from periphyton (AE=3-14%) was lower than that for TetraMin(®) (AE=44-86%) regardless of Cd concentration or food form. Ingestion rate (IR) was lower for dry than fresh forms of periphyton (0.042 and 0.16 g AFDM/g H. azteca/day respectively) and TetraMin(®) (0.19 and 0.87 AFDM/g H. azteca/day respectively) and depuration rate (k(e)) did not differ statistically with food type, form or Cd concentration (0.032-0.094 d(-1)). Biokinetic models with parameters of AE, IR and k(e) were used to estimate bioaccumulation from the separate food types. These estimates were compared to those from an independent chronic Cd saturation bioaccumulation model. While the model estimates did not concur, a sensitivity analysis indicated that AE and IR were the most influential biokinetic model parameters for Cd in periphyton and TetraMin(®) respectively. It was hypothesized that AE was underestimated for Cd in periphyton due to a non-adapted gut enzyme system and IR was overestimated for Cd in TetraMin(®) due to an initial rapid ingestion phase in H. azteca's feeding habits. This research demonstrated the importance of using ecologically relevant food types in laboratory experiments and verifying acute biokinetic model predictions of dietary metal contribution with those derived from a chronic exposure which is more representative of a field exposure scenario.

  13. Do pyrethroid-resistant Hyalella azteca have greater bioaccumulation potential compared to non-resistant populations? Implications for bioaccumulation in fish.

    Science.gov (United States)

    Muggelberg, Leslie L; Huff Hartz, Kara E; Nutile, Samuel A; Harwood, Amanda D; Heim, Jennifer R; Derby, Andrew P; Weston, Donald P; Lydy, Michael J

    2017-01-01

    The recent discovery of pyrethroid-resistant Hyalella azteca populations in California, USA suggests there has been significant exposure of aquatic organisms to these terrestrially-applied insecticides. Since resistant organisms are able to survive in relatively contaminated habitats they may experience greater pyrethroid bioaccumulation, subsequently increasing the risk of those compounds transferring to predators. These issues were evaluated in the current study following toxicity tests in water with permethrin which showed the 96-h LC50 of resistant H. azteca (1670 ng L(-1)) was 53 times higher than that of non-resistant H. azteca (31.2 ng L(-1)). Bioaccumulation was compared between resistant and non-resistant H. azteca by exposing both populations to permethrin in water and then measuring the tissue concentrations attained. Our results indicate that resistant and non-resistant H. azteca have similar potential to bioaccumulate pyrethroids at the same exposure concentration. However, significantly greater bioaccumulation occurs in resistant H. azteca at exposure concentrations non-resistant organisms cannot survive. To assess the risk of pyrethroid trophic transfer, permethrin-dosed resistant H. azteca were fed to fathead minnows (Pimephales promelas) for four days, after which bioaccumulation of permethrin and its biotransformation products in fish tissues were measured. There were detectable concentrations of permethrin in fish tissues after they consumed dosed resistant H. azteca. These results show that bioaccumulation potential is greater in organisms with pyrethroid resistance and this increases the risk of trophic transfer when consumed by a predator. The implications of this study extend to individual fitness, populations and food webs.

  14. Calculation and evaluation of sediment effect concentrations for the amphipod Hyalella azteca and the midge Chironomus riparius

    Science.gov (United States)

    Ingersoll, Christopher G.; Haverland, Pamela S.; Brunson, Eric L.; Canfield, Timothy J.; Dwyer, F. James; Henke, Chris; Kemble, Nile E.; Mount, David R.; Fox, Richard G.

    1996-01-01

    Procedures are described for calculating and evaluating sediment effect concentrations (SECs) using laboratory data on the toxicity of contaminants associated with field-collected sediment to the amphipod Hyalella azteca and the midge Chironomus riparius. SECs are defined as the concentrations of individual contaminants in sediment below which toxicity is rarely observed and above which toxicity is frequently observed. The objective of the present study was to develop SECs to classify toxicity data for Great Lake sediment samples tested with Hyalella azteca and Chironomus riparius. This SEC database included samples from additional sites across the United States in order to make the database as robust as possible. Three types of SECs were calculated from these data: (1) Effect Range Low (ERL) and Effect Range Median (ERM), (2) Threshold Effect Level (TEL) and Probable Effect Level (PEL), and (3) No Effect Concentration (NEC). We were able to calculate SECs primarily for total metals, simultaneously extracted metals, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The ranges of concentrations in sediment were too narrow in our database to adequately evaluate SECs for butyltins, methyl mercury, polychlorinated dioxins and furans, or chlorinated pesticides. About 60 to 80% of the sediment samples in the database are correctly classified as toxic or not toxic depending on type of SEC evaluated. ERMs and ERLs are generally as reliable as paired PELs and TELs at classifying both toxic and non-toxic samples in our database. Reliability of the SECs in terms of correctly classifying sediment samples is similar between ERMs and NECs; however, ERMs minimize Type I error (false positives) relative to ERLs and minimize Type II error (false negatives) relative to NECs. Correct classification of samples can be improved by using only the most reliable individual SECs for chemicals (i.e., those with a higher percentage of correct classification). SECs

  15. An evaluation of the ability of chemical measurements to predict polycyclic aromatic hydrocarbon-contaminated sediment toxicity to Hyalella azteca.

    Science.gov (United States)

    McDonough, Kathleen M; Azzolina, Nicholas A; Hawthorne, Steven B; Nakles, David V; Neuhauser, Edward F

    2010-07-01

    The present study examined the ability of three chemical estimation methods to predict toxicity and nontoxicity of polycyclic aromatic hydrocarbon (PAH) -contaminated sediment to the freshwater benthic amphipod Hyalella azteca for 192 sediment samples from 12 field sites. The first method used bulk sediment concentrations of 34 PAH compounds (PAH34), and fraction of total organic carbon, coupled with equilibrium partitioning theory to predict pore-water concentrations (KOC method). The second method used bulk sediment PAH34 concentrations and the fraction of anthropogenic (black carbon) and natural organic carbon coupled with literature-based black carbon-water and organic carbon-water partition coefficients to estimate pore-water concentrations (KOCKBC method). The final method directly measured pore-water concentrations (pore-water method). The U.S. Environmental Protection Agency's hydrocarbon narcosis model was used to predict sediment toxicity for all three methods using the modeled or measured pore-water concentration as input. The KOC method was unable to predict nontoxicity (83% of nontoxic samples were predicted to be toxic). The KOCKBC method was not able to predict toxicity (57% of toxic samples were predicted to be nontoxic) and, therefore, was not protective of the environment. The pore-water method was able to predict toxicity (correctly predicted 100% of the toxic samples were toxic) and nontoxicity (correctly predicted 71% of the nontoxic samples were nontoxic). This analysis clearly shows that direct pore-water measurement is the most accurate chemical method currently available to estimate PAH-contaminated sediment toxicity to H. azteca.

  16. Toxicity of fluorotelomer carboxylic acids to the algae Pseudokirchneriella subcapitata and Chlorella vulgaris, and the amphipod Hyalella azteca.

    Science.gov (United States)

    Mitchell, Rebecca J; Myers, Anne L; Mabury, Scott A; Solomon, Keith R; Sibley, Paul K

    2011-11-01

    Perfluorinated acids (PFAs) have elicited significant global regulatory and scientific concern due to their persistence and global pervasiveness. A source of PFAs in the environment is through degradation of fluorotelomer carboxylic acids (FTCAs) but little is known about the toxicity of these degradation products. Previous work found that FTCAs were two to three orders of magnitude more toxic to some freshwater invertebrates than their PFA counterparts and exhibited comparable chain-length-toxicity relationships. In this study, we investigated the toxicity of the 6:2, 8:2, and 10:2 saturated (FTsCA) and unsaturated (FTuCA) fluorotelomer carboxylic acids to two species of freshwater algae, Chlorella vulgaris and Pseudokirchneriella subcapitata, and the amphipod, Hyalella azteca. C. vulgaris was generally the most sensitive species, with EC₅₀s of 26.2, 31.8, 11.1, and 4.2 mg/L for the 6:2 FTsCA, 6:2 FTuCA, 8:2 FTuCA, and 10:2 FTsCA, respectively. H. azteca was most sensitive to the 8:2 FTsCA and 10:2 FTuCA, with LC₅₀s of 5.1 and 3.7 mg/L. The toxicity of the FTCAs generally increased with increasing carbon chain length, and with saturation for most of the species tested, with the exception of P. subcapitata, which did not exhibit any trend. These observations agree with chain-length-toxicity relationships previously reported for the PFCAs and support the greater toxicity of the FTCAs compared to PFCAs. However, the toxicity values are approximately 1000-fold above those detected in the environment indicating negligible risk to aquatic invertebrates.

  17. USE OF CARBOXYLESTERASE ACTIVITY TO REMOVE PYRETHROID-ASSOCIATED TOXICITY TO CERIODAPHNIA DUBIA AND HYALELLA AZTECA IN TOXICITY IDENTIFICATION EVALUATIONS

    Science.gov (United States)

    Wheelock, Craig E.; Miller, Jeff L.; Miller, Mike J.; Phillips, Bryn M.; Huntley, Sarah A.; Gee, Shirley J.; Tjeerdema, Ronald S.; Hammock, Bruce D.

    2006-01-01

    Increases in the use and application of pyrethroid insecticides have resulted in concern regarding potential effects on aquatic ecosystems. Methods for the detection of pyrethroids in receiving waters are required to monitor environmental levels of these insecticides. One method employed for the identification of causes of toxicity in aquatic samples is the toxicity identification evaluation (TIE); however, current TIE protocols do not include specific methods for pyrethroid detection. Recent work identified carboxylesterase treatment as a useful method for removing/detecting pyrethroid-associated toxicity. The present study has extended this earlier work and examined the ability of carboxylesterase activity to remove permethrin- and bifenthrin-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in a variety of matrices, including laboratory water, Sacramento River (CA, USA) water, and Salinas River (CA, USA) interstitial water. Esterase activity successfully removed 1,000 ng/L of permethrin-associated toxicity and 600 ng/L of bifenthrin-associated toxicity to C. dubia in Sacramento River water. In interstitial water, 200 ng/L of permethrin-associated toxicity and 60 ng/L of bifenthrin-associated toxicity to H. azteca were removed. The selectivity of the method was validated using heat-inactivated enzyme and bovine serum albumin, demonstrating that catalytically active esterase is required. Further studies showed that the enzyme is not significantly inhibited by metals. Matrix effects on esterase activity were examined with municipal effluent and seawater in addition to the matrices discussed above. Results confirmed that the esterase retains catalytic function in a diverse array of matrices, suggesting that this technique can be adapted to a variety of aquatic samples. These data demonstrate the utility of carboxylesterase treatment as a viable step to detect the presence of pyrethroids in receiving waters. PMID:16629136

  18. Comparing the effectiveness of chronic water column tests with the crustaceans Hyalella azteca (order: Amphipoda) and Ceriodaphnia dubia (order: Cladocera) in detecting toxicity of current-use insecticides.

    Science.gov (United States)

    Deanovic, Linda A; Markiewicz, Dan; Stillway, Marie; Fong, Stephanie; Werner, Inge

    2013-03-01

    Standard U.S. Environmental Protection Agency laboratory tests are used to monitor water column toxicity in U.S. surface waters. The water flea Ceriodaphnia dubia is among the most sensitive test species for detecting insecticide toxicity in freshwater environments.Its usefulness is limited, however, when water conductivity exceeds 2,000 µS/cm (approximately 1 ppt salinity) and test effectiveness is insufficient. Water column toxicity tests using the euryhaline amphipod Hyalella azteca could complement C. dubia tests; however, standard chronic protocols do not exist. The present study compares the effectiveness of two water column toxicity tests in detecting the toxicity of two organophosphate (OP) and two pyrethroid insecticides: the short-term chronic C. dubia test, which measures mortality and fecundity, and a 10-d H. azteca test, which measures mortality and growth. Sensitivity was evaluated by comparing effect data, and end point variability was evaluated by comparing minimum significant differences. Tests were performed in synthetic water and filtered ambient water to quantify the influence of water matrix on effect concentrations. The H. azteca test detected pyrethroid toxicity far more effectively, while the C. dubia test was more sensitive to OPs. Among endpoints, H. azteca mortality was most robust. The results demonstrate that the H. azteca test is preferable when conductivity of water samples is 2,000 to 10,000 µS/cm or if contaminants of concern include pyrethroid insecticides.

  19. Environmental fate of pyrethroids in urban and suburban stream sediments and the appropriateness of Hyalella azteca model in determining ecological risk.

    Science.gov (United States)

    Palmquist, Katherine; Fairbrother, Anne; Salatas, Johanna; Guiney, Patrick D

    2011-07-01

    According to several recent studies using standard acute Hyalella azteca sediment bioassays, increased pyrethroid use in urban and suburban regions in California has resulted in the accumulation of toxic concentrations of pyrethroids in sediments of area streams and estuaries. However, a critical review of the literature indicates that this is likely an overestimation of environmental risk. Hyalella azteca is consistently the most susceptible organism to both aqueous and sediment-associated pyrethroid exposures when compared to a suite of other aquatic taxa. In some cases, H. azteca LC50 values are less than the community HC10 values, suggesting that the amphipod is an overly conservative model for community- or ecosystem-level impacts of sediment-associated pyrethroids. Further, as a model for responses of field populations of H. azteca, the laboratory bioassays considerably overestimate exposure, because the amphipod is more appropriately characterized as an epibenthic organism, not a true sediment dweller; H. azteca preferentially inhabit aquatic macrophytes, periphyton mats, and leaf litter, which drastically reduces their exposure to contaminated sediments. Sediment-bound pyrethroids are transported via downstream washing of fine particulates resulting in longer range transport but also more efficient sequestration of the chemical. In addition, site-specific variables such as sediment organic carbon content, grain size, temperature, and microbial activity alter pyrethroid bioavailability, degradation, and toxicity on a microhabitat scale. The type and source of the carbon in particular, influences the pyrethroid sequestering ability of sediments. The resulting irregular distribution of pyrethroids in stream sediments suggests that sufficient nonimpacted habitat may exist as refugia for resident sediment-dwelling organisms for rapid recolonization to occur. Given these factors, we argue that the amphipod model provides, at best, a screening level assessment of

  20. Reduced metals concentrations of water, sediment and hyalella azteca from lakes in the vicinity of the sudbury metal smelters, Ontario, Canada.

    Science.gov (United States)

    Shuhaimi-Othman, M; Pascoe, D; Borgmann, U; Norwood, W P

    2006-06-01

    Hyalella azteca (Crustacea: Amphipoda), water and sediments from 12 circum-neutral lakes between Sudbury and North Bay in Ontario, Canada were sampled in August 1998 and analyzed for 10 metals including Cu, Zn, Cd, Ni, Pb, Co, Mo, V, Ba and Ti. Statistical analyses showed that concentrations of the metals in H. azteca, water and sediment differed significantly (ANOVA, Pazteca and Mo in water). There was a trend of declining metal concentration, especially for Cu, Ni and Co (in water, Hyalella and sediment), with distance from the smelters indicating the reduced impact of atmospheric pollution. Metal concentrations of lakes (water) in the Sudbury area were found to be lower compared to data from the 1970s and 1980s indicating an improvement in water quality. Metal concentrations in field-collected amphipods compared favorably with those measured in the laboratory in animals exposed to deep-water sediments, provided metal concentrations were not extremely low (e.g., Pb) and that water chemistry differences (e.g., pH) were taken into account for some metals (especially Cd). In general bioaccumulation of metals in H. azteca was predicted better from surface water than from sediment total metal.

  1. Single-walled carbon nanotubes toxicity to the freshwater amphipod Hyalella azteca: influence of sediment and exposure duration

    Directory of Open Access Journals (Sweden)

    Messika Revel

    2015-04-01

    Full Text Available Carbon nanomaterials are present in various industrial applications and therefore their release into the environment including freshwater ecosystem is expected to increase. The aim of the present study was to investigate the influence of several parameters on the toxicity of single-walled carbon nanotubes (SWCNT to the freshwater amphipod, Hyalella azteca. The effect of period of exposure, sediment presence and possible impurities released during SWCNT preparation on survival and/or growth of such organism was evaluated. We measured a reduction of survival at concentrations ranging from 10 to 40 mg/L after 96-h exposure, while no mortality was observed with the same concentrations and in the presence of artificial sediment after 14 days of exposure. It is possible that SWCNT are adsorbed on the organic matter from the artificial sediment leading to a decrease of SWCNT bioavailability. The survival and growth toxicity tests revealed a stronger effect at 28 days compared to the 14 days of exposure, and full mortality of organisms at 1000 mg/L for both exposure times. The presence of SWCNT in the gut of survived organisms was observed. The present study demonstrates that the interaction with sediment should be considered when carbon nanotubes toxicity through water exposure is investigated.

  2. Bioaccumulation of metals by Hyalella azteca exposed to contaminated sediments from the upper Clark Fork River, Montana

    Science.gov (United States)

    Ingersoll, Christopher G.; Brumbaugh, William G.; Dwyer, F. James; Kemble, Nile E.

    1994-01-01

    Macroinvertebrates contaminated with metals in the Clark Fork River of Montana have been demonstrated to be a potentially toxic component in the diet of trout Because sediment was the suspected source of metals to these invertebrates, bioaccumulation of As, Cd, Cu, Pb, and Zn from sediment was evaluated by exposing the amphipod Hyalella azteca for 28 d in the laboratory to samples of sediment collected from depositional areas of the Clark Fork River Benthic invertebrates collected from riffles adjacent to the depositional areas were also analyzed for metals The pattern of metal accumulation between laboratory-exposed and field-collected animals was similar, however, the concentrations of metals in laboratory exposed amphipods were often 50 to 75% less than were the concentrations of metals in the field collected invertebrates These findings indicate that sediment is a significant source of metals to invertebrates in the Clark Fork River Additional studies should be conducted to determine threshold concentrations for effects of dietary metals on fish Long-term monitoring of the river should include sampling benthic invertebrates for metal accumulation.

  3. Assessing sediment toxicity from navigational pools of the Upper Mississippi River using a 28-day Hyalella azteca test

    Science.gov (United States)

    Kemble, N.E.; Brunson, E.L.; Canfield, T.J.; Dwyer, F.J.; Ingersoll, C.G.

    1998-01-01

    To assess the extent of sediment contamination in the Upper Mississippi River (UMR) system after the flood of 1993, sediment samples were collected from 24 of the 26 navigational pools in the river and from one site in the Saint Croix River in the summer of 1994. Whole-sediment tests were conducted with the amphipod Hyalella azteca for 28 days measuring the effects on survival, growth, and sexual maturation. Amphipod survival was significantly reduced in only one sediment (13B) relative to the control and reference sediments. Body length of amphipods was significantly reduced relative to the control and reference sediments in only one sample (26C). Sexual maturation was not significantly reduced in any treatment when compared to the control and reference sediments. No significant correlations were observed between survival, growth, and maturation to either the physical or chemical characteristics of the sediment samples from the river. When highly reliable effect range medians (ERMs) were used to evaluate sediment chemistry, 47 of 49 (96%) of the samples were correctly classified as nontoxic. These results indicate that sediment samples from the Upper Mississippi River are relatively uncontaminated compared to other areas of known contamination in the United States.

  4. Using an interlaboratory study to revise methods for conducting 10-d to 42-d water or sediment toxicity tests with Hyalella azteca.

    Science.gov (United States)

    Ivey, Chris D; Ingersoll, Chris G; Brumbaugh, William G; Hammer, Edward J; Mount, Dave R; Hockett, J Russell; Norberg-King, Teresa J; Soucek, Dave; Taylor, Lisa

    2016-10-01

    Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast-cerophyll-trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca. Environ Toxicol Chem 2016;35:2439-2447. © 2016 SETAC.

  5. Using an interlaboratory study to revise methods for conducting 10-d to 42-d water or sediment toxicity tests with Hyalella azteca

    Science.gov (United States)

    Ivey, Chris D.; Ingersoll, Christopher G.; Brumbaugh, William G.; Hammer, Edward J.; Mount, David R.; Hockett, J. Russell; Norberg-King, Teresa J.; Soucek, Dave; Taylor, Lisa

    2016-01-01

    Studies have been conducted to refine US Environmental Protection Agency, ASTM International, and Environment Canada standard methods for conducting 42-d reproduction tests with Hyalella azteca in water or in sediment. Modifications to the H. azteca method include better-defined ionic composition requirements for exposure water (i.e., >15 mg/L of chloride and >0.02 mg/L of bromide) and improved survival, growth, and reproduction with alternate diets provided as increased rations over time in water-only or whole-sediment toxicity tests. A total of 24 laboratories volunteered to participate in the present interlaboratory study evaluating the performance of H. azteca in 42-d studies in control sand or control sediment using the refined methods. Improved growth and reproduction of H. azteca was observed with 2 alternate diets of 1) ramped diatoms (Thalassiosira weissflogii) + ramped Tetramin or 2) yeast–cerophyll–trout chow (YCT) + ramped Tetramin, especially when compared with results from the traditional diet of 1.8 mg YCT/d. Laboratories were able to meet proposed test acceptability criteria and in most cases had lower variation in growth or reproduction compared with previous interlaboratory studies using the traditional YCT diet. Laboratory success in conducting 42-d H. azteca exposures benefited from adherence to several key requirements of the detailed testing, culturing, and handling methods. Results from the present interlaboratory study are being used to help revise standard methods for conducting 10-d to 42-d water or sediment toxicity exposures with H. azteca.

  6. Behavioural alterations from exposure to Cu, phenanthrene, and Cu-phenanthrene mixtures: linking behaviour to acute toxic mechanisms in the aquatic amphipod, Hyalella azteca.

    Science.gov (United States)

    Gauthier, Patrick T; Norwood, Warren P; Prepas, Ellie E; Pyle, Greg G

    2016-01-01

    Phenanthrene (PHE) and Cu are two contaminants commonly co-occurring in marine and freshwater environments. Mixtures of PHE and Cu have been reported to induce more-than-additive lethality in the amphipod, Hyalella azteca, a keystone aquatic invertebrate, yet little is understood regarding the interactive toxic mechanisms that mediate more-than-additive toxicity. Understanding the interactions among toxic mechanisms among Cu and PHE will allow for better predictive power in assessing the ecological risks of Cu-PHE mixtures in aquatic environments. Here we use behavioural impairment to help understand the toxic mechanisms of Cu, PHE, and Cu-PHE mixture toxicity in the aquatic amphipod crustacean, Hyalella azteca. Our principal objective was to link alterations in activity and ventilation with respiratory rates, oxidative stress, and neurotoxicity in adult H. azteca. Adult amphipods were used for all toxicity tests. Amphipods were tested at sublethal exposures of 91.8- and 195-μgL(-1) Cu and PHE, respectively, and a Cu-PHE mixture at the same concentrations for 24h. Neurotoxicity was measured as acetylcholinesterase (AChE) activity, where malathion was used as a positive control. Oxidative stress was measured as reactive oxygen species (ROS) production. Phenanthrene-exposed amphipods exhibited severe behavioural impairment, being hyperstimulated to the extent that they were incapable of coordinating muscle movements. In addition, respiration and AChE activity in PHE-exposed amphipods were increased and reduced by 51% and 23% respectively. However, ROS did not increase following exposure to phenanthrene. In contrast, Cu had no effect on amphipod behaviour, respiration or AChE activity, but did lead to an increase in ROS. However, co-exposure to Cu antagonized the PHE-induced reduction in ventilation and negated any increase in respiration. The results suggest that PHE acts like an organophosphate pesticide (e.g., malathion) in H. azteca following 24h sublethal

  7. Evaluation of ability of reference toxicity tests to identify stress in laboratory populations of the amphipod Hyalella azteca

    Science.gov (United States)

    McNulty, E.W.; Dwyer, F.J.; Ellersieck, Mark R.; Greer, E.I.; Ingersoll, C.G.; Rabeni, C.F.

    1999-01-01

    Standard methods for conducting toxicity tests imply that the condition of test organisms can be established using reference toxicity tests. However, only a limited number of studies have evaluated whether reference toxicity tests can actually be used to determine if organisms are in good condition at the start of a test. We evaluated the ability of reference toxicants to identify stress associated with starvation in laboratory populations of the amphipod Hyalella azteca using acute toxicity tests and four reference toxicants: KCl, CdCl2, sodium pentachlorophenate (NaPCP), and carbaryl. Stress associated with severe starvation was observed with exposure of amphipods to carbaryl or NaPCP but not with exposure to KCl or CdCl2 (i.e., lower LC50 with severe starvation). Although the LC50s for NaPCP and carbaryl were statistically different between starved and fed amphipods, this difference may not be biologically significant given the variability expected in acute lethality tests. Stress associated with sieving, heat shock, or cold shock of amphipods before the start of a test was not evident with exposure to carbaryl or KCl as reference toxicants. The chemicals evaluated in this study provided minimal information about the condition of the organisms used to start a toxicity test. Laboratories should periodically perform reference toxicity tests to assess the sensitivity of life stages or strains of test organisms. However, use of other test acceptability criteria required in standard methods such as minimum survival, growth, or reproduction of organisms in the control treatment at the end of a test, provides more useful information about the condition of organisms used to start a test compared to data generated from reference toxicity tests.

  8. Toxicity of sediment cores collected from the ashtabula river in northeastern Ohio, USA, to the amphipod hyalella azteca

    Science.gov (United States)

    Ingersoll, C.G.; Kemble, N.E.; Kunz, J.L.; Brumbaugh, W.G.; MacDonald, D.D.; Smorong, D.

    2009-01-01

    This study was conducted to support a Natural Resource Damage Assessment and Restoration project associated with the Ashtabula River in Ohio. The objective of the study was to evaluate the chemistry and toxicity of 50 sediment samples obtained from five cores collected from the Ashtabula River (10 samples/core, with each 10-cm-diameter core collected to a total depth of about 150 cm). Effects of chemicals of potential concern (COPCs) measured in the sediment samples were evaluated by measuring whole-sediment chemistry and whole-sediment toxicity in the sediment samples (including polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], organochlorine pesticides, and metals). Effects on the amphipod Hyalella azteca at the end of a 28-day sediment toxicity test were determined by comparing survival or length of amphipods in individual sediment samples in the cores to the range of responses of amphipods exposed to selected reference sediments that were also collected from the cores. Mean survival or length of amphipods was below the lower limit of the reference envelope in 56% of the sediment samples. Concentrations of total PCBs alone in some samples or concentrations of total PAHs alone in other samples were likely high enough to have caused the reduced survival or length of amphipods (i.e., concentrations of PAHs or PCBs exceeded mechanistically based and empirically based sediment quality guidelines). While elevated concentrations of ammonia in pore water may have contributed to the reduced length of amphipods, it is unlikely that the reduced length was caused solely by elevated ammonia (i.e., concentrations of ammonia were not significantly correlated with the concentrations of PCBs or PAHs and concentrations of ammonia were elevated both in the reference sediments and in the test sediments). Results of this study show that PAHs, PCBs, and ammonia are the primary COPCs that are likely causing or substantially contributing to the toxicity to

  9. Evaluation of ability of reference toxicity tests to identify stress in laboratory populations of the amphipod Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    McNulty, E.W.; Ellersieck, M.R.; Rabeni, C.F. [Univ. of Missouri, Columbia, MO (United States); Dwyer, F.J.; Greer, E.I.; Ingersoll, C.G. [Geological Survey, Columbia, MO (United States). Columbia Environmental Research Center

    1999-03-01

    Standard methods for conducting toxicity tests imply that the condition of test organisms can be established using reference toxicity tests. However, only a limited number of studies have evaluated whether reference toxicity tests can actually be used to determine if organisms are in good condition, at the start of a test. The authors evaluated the ability of reference toxicants to identify stress associated with starvation in laboratory populations of the amphipod Hyalella azteca using acute toxicity tests and four reference toxicants: KCl, CdCl{sub 2}, sodium pentachlorophenate (NaPCP), and carbaryl. Stress associated with severe starvation was observed with exposure of amphipods to carbaryl or NaPCP but not with exposure to KCl or CdCl{sub 2} (i.e., lower LC50 with severe starvation). Although the LC50s for NaPCP and carbaryl were statistically different between starved and fed amphipods, this difference may not be biologically significant given the variability expected in acute lethality tests. Stress associated with sieving, heat shock, or cold shock of amphipods before the start of a test was not evident with exposure to carbaryl or KCl as reference toxicants. The chemicals evaluated in this study provided minimal information about the condition of the organisms used to start a toxicity test. Laboratories should periodically perform reference toxicity tests to assess the sensitivity of life stages or strains of test organisms. However, use of other test acceptability criteria required in standard methods, such as minimum survival, growth, or reproduction of organisms in the control treatment at the end of a test, provides more useful information about the condition of organisms used to start a test compared to data generated from reference toxicity tests.

  10. A comparative study of different diets to optimize cultivation of Hyalella azteca in the laboratory.

    Science.gov (United States)

    Fracácio, Renata; Dias, Geisa Soares; Zagatto, Pedro Antônio; Bidinotto, Paulo Maurício; Silva, Paulo

    2011-09-01

    The aim of this study was to assess the influence of four diets on the laboratory cultivation of H. azteca, seeking to improve production of young specimens through reduced mortality and better growth and number of offspring per couple. The best diet was composed of a mixture of diluted commercial fish food, diluted yeast and primrose oil, associated with fish food flakes containing spirulina. With this diet the maximum mortality was 25 percent (at the end of 28 days), the average number of offspring/couple was 11.4 ± 2.8 (at the end of twelve days) and the peak weight and length of the males (at the end of 40 days) were 0.930 μg and 5.26 ± 1.1mm, respectively.

  11. A two-step experimental design for a sediment bioassay using growth of the amphipod Hyalella azteca for the test end point

    Science.gov (United States)

    Kubitz, Jody A.; Besser, John M.; Giesy, John P.

    1996-01-01

    We designed a sediment bioassay using 25% growth inhibition of Hyalella azteca as the end point.Hyalella azteca exhibits size-specific fecundity, so growth is a surrogate of reproductive production. We investigated density effects on growth to address whether crowding could affect test interpretation; amphipods in 14,000/m2 exposures were 16 to 20% smaller than those at 7,000/m2. Using power analysis, we found that 20 to 25 samples are required to determine significance when α = 0.10 and 1 − β = 0.90. To minimize the need for laboratory resources, we designed a two-step (screening and confirmatory) bioassay, which we tested with field-collected sediments. The screening bioassay compared 11 sediments to a reference. Three sediments were “toxic” (significant growth inhibition when 1 − β = 0.66 and n = 5), five sediments were “nontoxic” (>90% of reference), and three sediments were “possibly toxic” (growth inhibition was insignificant). In the confirmatory bioassay, three possibly toxic and two nontoxic samples were reevaluated. Two were toxic (1 − β = 0.91 and n = 20), and the remaining four samples were nontoxic. In summary, five sediments were toxic and six sediments were nontoxic. The two-step analysis used minimal laboratory resources but maximized statistical power, where needed, to discriminate growth effects.

  12. Selection of food combinations to optimize survival, growth, and reproduction of the amphipod Hyalella azteca in static-renewal, water-only laboratory exposures.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy; Major, Kaley M

    2016-10-01

    Although standardized sediment toxicity testing methods have been developed for the amphipod Hyalella azteca, no standardized chronic water-only toxicity testing methods have been established. Furthermore, optimal feeding and water quality conditions for culturing and toxicity testing with this species remained unclear. The objective of the present study was to determine the food or combination of foods that best promotes survival, growth, and reproduction of the US Lab strain of Hyalella azteca under 42-d, water-only, static-renewal testing conditions. The authors conducted 7 42-d control (no toxicant) tests with various combinations of food (including Tetramin, yeast-cereal leaves-trout chow, diatoms, wheatgrass, alfalfa, and maple leaves) and substrate types (clean "unconditioned" Nitex screens vs "conditioned" Nitex screens that were colonized by live biofilms). Over all treatments, survival ranged from 18% to 96%, dry weight per individual from 0.084 mg to 1.101 mg, and reproduction from 0 young/female to 28.4 young/female. Treatments that included Tetramin tended to result in better performance than those that did not. In particular, treatments that included Tetramin and either conditioned screens or diatoms consistently had high survival, weight, and reproduction values as well as low variability among replicates (measured as coefficient of variation). A ramped Tetramin plus diatom suspension feeding regime appears to have the greatest potential to produce consistently good performance across laboratories using static-renewal systems. Environ Toxicol Chem 2016;35:2407-2415. © 2016 SETAC.

  13. Implications of Cu and Ni toxicity in two members of the Hyalella azteca cryptic species complex: Mortality, growth, and bioaccumulation parameters.

    Science.gov (United States)

    Leung, Jessica; Witt, Jonathan D S; Norwood, Warren; Dixon, D George

    2016-11-01

    Hyalella azteca, an amphipod crustacean, is frequently used in freshwater toxicity tests. Since the mid-1980s, numerous organizations have collected and established cultures of H. azteca originating from localities across North America. However, H. azteca is actually a large cryptic species complex whose members satisfy both the biological and the phylogenetic species concepts. Genetic analysis at the mitochondrial COI gene has revealed that only 2 clades are cultured in 17 North American laboratories; however, there are 85 genetically divergent lineages within this complex in the wild. In the present study, 2 members (clades 1 and 8) of the H. azteca species complex were identified using the mitochondrial COI gene. These 2 clades were exposed to Cu or Ni for 14 d. A saturation-based mortality model and the general growth model were used to determine mortality (lethal concentration, 25% and 50% [LC25 and LC50], lethal body concentration, 25% and 50% [LBC25 and LBC50]) and growth (inhibitory concentration, 25% [IC25, IBC25]) endpoints, respectively. A modified saturation-based model was used to estimate metal bioaccumulation parameters. Clade 8 was significantly more tolerant than clade 1, with differences in LC50s. However, the effects of the metals on growth were not significantly different between clades, even though clade 1 was significantly larger than then clade 8. Differences in Cu or Ni bioaccumulation were not observed between clades 1 and 8. The differences in Cu and Ni LC50s may have implications for risk assessments, and it is recommended that toxicity experiments should only be performed with properly identified members of the H. azteca complex to maintain consistency among laboratories. Environ Toxicol Chem 2016;35:2817-2826. © 2016 SETAC.

  14. The role of metabolism in the toxicity of 2,4,6-trinitrotoluene and its degradation products to the aquatic amphipod Hyalella azteca.

    Science.gov (United States)

    Sims, Jerre G; Steevens, Jeffery A

    2008-05-01

    Toxicological data on the effects of the explosive, 2,4,6-trinitrotoluene (TNT), and its degradation products suggests an unpredictable toxicological response in aquatic organisms. Several studies suggest TNT becomes more toxic as it degrades while others suggest TNT becomes less toxic. This study focused on the toxicity of TNT and several degradation products as well as the role of oxidative metabolism in the toxicity of TNT. The aquatic invertebrate Hyalella azteca was used to evaluate the toxicity of TNT and four of its degradation products. The most reduced degradation product, 2,4-diamino, 6-nitrotoluene (2,4-DANT) was the most toxic to H. azteca. However, 2,4-DANT was only a minor metabolite in H. azteca. The influence of metabolism on the toxicokinetics of TNT was assessed indirectly through the use of a CYP450 inducer and inhibitor. Treatment of organisms with beta-napthoflavone (BNF), a CYP450 inducer, increased the toxicity of TNT and increased the rate of elimination and metabolism of TNT. Similar to BNF, organisms treated with clotrimazole (CTZ), a CYP450 inhibitor, resulted in increased toxicity and TNT metabolism. It is likely the ability to metabolize or bioactivate TNT to a more reactive intermediate plays a significant role in the sensitivity of organisms to TNT.

  15. Causes of toxicity to Hyalella azteca in a stormwater management facility receiving highway runoff and snowmelt. Part I: polycyclic aromatic hydrocarbons and metals.

    Science.gov (United States)

    Bartlett, A J; Rochfort, Q; Brown, L R; Marsalek, J

    2012-01-01

    The Terraview-Willowfield Stormwater Management Facility (TWSMF) receives inputs of multiple contaminants, including metals, polycyclic aromatic hydrocarbons (PAHs), road salt, and nutrients, via highway and residential runoff. Contaminant concentrations in runoff are seasonally dependent, and are typically high in early spring, coinciding with the snowmelt. In order to investigate the seasonal fluctuations of contaminant loading and related changes in toxicity to benthic invertebrates, overlying water and sediment samples were collected in the fall and spring, reflecting low and high contaminant loading, respectively, and four-week sediment toxicity tests were conducted with Hyalella azteca. The effects of metals and PAHs are discussed here; the effects of salts, nutrients, and water quality are discussed in a companion paper. Survival and growth of Hyalella after exposure to fall samples were variable: survival was significantly reduced (64-74% of controls) at three out of four sites, but there were no significant growth effects. More dramatic effects were observed after Hyalella were exposed to spring samples: survival was significantly reduced at the two sites furthest downstream (0-75% of controls), and growth was significantly lower in four out of five sites when comparing Hyalella exposed to site sediment with overlying site water versus site sediment with overlying control water. These seasonal changes in toxicity were not related to metals or PAHs: 1. levels of bioavailable metals were below those expected to cause toxicity, and 2. levels of PAHs in sediment were lowest at sites with the greatest toxicity and highest in water and sediment at sites with no toxicity. Although not associated with toxicity, some metals and PAHs exceeded probable and severe effect levels, and could be a cause for concern if contaminant bioavailability changes. Toxicity in the TWSMF appeared to be primarily associated with water-borne contaminants. The cause(s) of these effects

  16. Predicting toxicity to Hyalella azteca in pyrogenic-impacted sediments-Do we need to analyze for all 34 PAHs?

    Science.gov (United States)

    Geiger, Stephen C; Azzolina, Nicholas A; Nakles, David V; Hawthorne, Steven B

    2016-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are major drivers of risk at many urban and/or industrialized sediment sites. The US Environmental Protection Agency (USEPA) currently recommends using measurements of 18 parent + 16 groups of alkylated PAHs (PAH-34) to assess the potential for sediment-bound PAHs to impact benthic organisms at these sites. ASTM Method D7363-13 was developed to directly measure low-level sediment porewater PAH concentrations. These concentrations are then compared to ambient water criteria (final chronic values [FCVs]) to assess the potential for impact to benthic organisms. The interlaboratory validation study that was used to finalize ASTM D7363-13 was developed using 24 of the 2-, 3-, and 4-ring PAHs (PAH-24) that are included in the USEPA PAH-34 analyte list. However, it is the responsibility of the user of ASTM Method D7363 to establish a test method to quantify the remaining 10 higher molecular weight PAHs that make up PAH-34. These higher molecular weight PAHs exhibit extremely low saturation solubilities that make their detection difficult in porewater, which has proven difficult to implement in a contract laboratory setting. As a result, commercial laboratories are hesitant to conduct the method on the entire PAH-34 analyte list. This article presents a statistical comparison of the ability of the PAH-24 and PAH-34 porewater results to predict survival of the freshwater amphipod Hyalella azteca, using the original 269 sediment samples used to gain ASTM D7363 Method approval. The statistical analysis shows that the PAH-24 are statistically indistinguishable from the PAH-34 for predicting toxicity. These results indicate that the analysis of freely dissolved porewater PAH-24 is sufficient for making risk-based decisions based on benthic invertebrate toxicity (survival and growth). This reduced target analyte list should result in a cost-saving for stakeholders and broader implementation of the method at PAH-impacted sediment sites

  17. Mixture toxicity of imidacloprid and cyfluthrin to two non-target species, the fathead minnow Pimephales promelas and the amphipod Hyalella azteca.

    Science.gov (United States)

    Lanteigne, Michelle; Whiting, Sara A; Lydy, Michael J

    2015-02-01

    Two species, the fathead minnow Pimephales promelas and the amphipod Hyalella azteca, were tested to examine acute toxicity to two insecticides, cyfluthrin and imidacloprid individually and as a mixture. Cyfluthrin was acutely toxic to P. promelas and H. azteca with EC50 values and 95 % confidence intervals of 0.31 µg L(-1) (0.26-0.35 µg L(-1)) and 0.0015 µg L(-1) (0.0011-0.0018 µg L(-1)), respectively. Imidacloprid was not acutely toxic to P. promelas at water concentrations ranging from 1 to 5000 µg L(-1), whereas it was toxic to H. azteca with a EC50 value of 33.5 µg L(-1) (23.3-47.4 µg L(-1)). For the P. promelas mixture test, imidacloprid was added at a single concentration to a geometric series of cyfluthrin concentrations bracketing the EC50 value. A synergistic ratio (SR) of 1.9 was found for P. promelas, which was calculated using the cyfluthrin-only exposure and mixture-exposure data. Because cyfluthrin and imidacloprid were toxic to H. azteca, the mixture test was designed based on an equipotent toxic unit method. Results from the mixture test indicated a model deviation ratio (MDR) of 1.7 or 2.7 depending on the model. Mixture test results from the simultaneous exposure to cyfluthrin and imidacloprid with both species indicated a greater than expected toxic response because the SR or MDR values were >1. Because these two insecticides are commonly used together in the same product formulations, nontarget species could be more affected due to their greater-than-additive toxicity observed in the current study.

  18. Direct and indirect toxicity of the fungicide pyraclostrobin to Hyalella azteca and effects on leaf processing under realistic daily temperature regimes.

    Science.gov (United States)

    Willming, Morgan M; Maul, Jonathan D

    2016-04-01

    Fungicides in aquatic environments can impact non-target bacterial and fungal communities and the invertebrate detritivores responsible for the decomposition of allochthonous organic matter. Additionally, in some aquatic systems daily water temperature fluctuations may influence these processes and alter contaminant toxicity, but such temperature fluctuations are rarely examined in conjunction with contaminants. In this study, the shredding amphipod Hyalella azteca was exposed to the fungicide pyraclostrobin in three experiments. Endpoints included mortality, organism growth, and leaf processing. One experiment was conducted at a constant temperature (23 °C), a fluctuating temperature regime (18-25 °C) based on field-collected data from the S. Llano River, Texas, or an adjusted fluctuating temperature regime (20-26 °C) based on possible climate change predictions. Pyraclostrobin significantly reduced leaf shredding and increased H. azteca mortality at concentrations of 40 μg/L or greater at a constant 23 °C and decreased leaf shredding at concentrations of 15 μg/L or greater in the fluctuating temperatures. There was a significant interaction between temperature treatment and pyraclostrobin concentration on H. azteca mortality, body length, and dry mass under direct aqueous exposure conditions. In an indirect exposure scenario in which only leaf material was exposed to pyraclostrobin, H. azteca did not preferentially feed on or avoid treated leaf disks compared to controls. This study describes the influence of realistic temperature variation on fungicide toxicity to shredding invertebrates, which is important for understanding how future alterations in daily temperature regimes due to climate change may influence the assessment of ecological risk of contaminants in aquatic ecosystems.

  19. Use of GC × GC/TOF-MS and LC/TOF-MS for metabolomic analysis of Hyalella azteca chronically exposed to atrazine and its primary metabolite, desethylatrazine.

    Science.gov (United States)

    Ralston-Hooper, Kimberly J; Adamec, Jiri; Jannash, Amber; Mollenhauer, Robert; Ochoa-Acuña, Hugo; Sepúlveda, Maria S

    2011-07-01

    Atrazine is one of the most commonly detected contaminants in the U.S. Little information is available on one of atrazine's metabolites, desethylatrazine (DEA). Two-dimensional gas chromatography and liquid chromatography coupled with time of flight- mass spectrometry were used to examine metabolite profiles of Hyalella azteca chronically exposed to 30 µg/L atrazine and DEA. The majority of identified metabolites were by-products of β-oxidation of fatty acids suggesting possible disruption in energy metabolism. Eicosanoids increased in exposed females suggesting possible perturbations in neuropeptide hormonal systems. Overall, this research demonstrates the feasibility of utilizing metabolomic profiling of invertebrate species exposed to environmental contaminants as a way to determine mechanisms of toxicity.

  20. Survival, growth, and body residues of hyalella azteca (Saussure) exposed to fipronil contaminated sediments from non-vegetated and vegetated microcosms.

    Science.gov (United States)

    Kröger, Robert; Lizotte, Richard E; Moore, Matthew T

    2009-09-01

    We assessed chronic effects of fipronil and metabolite contaminated sediments from non-vegetated and Thallia dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures. Mean sediment concentrations (ng g(-1)) ranged from 0.72-1.26, 0.01-0.69, 0.07-0.23, and 0.49-7.87 for fipronil, fipronil-sulfide, fipronil-sulfone, and fipronil-desulfinyl, respectively. No significant differences in animal survival or growth were observed between non-vegetated and vegetated microcosms during wet or dry exposures. Mean animal body residue concentrations (ng g(-1)) ranged from 28.4-77.6, 0-30.7, and 8.3-43.8 for fipronil, fipronil-sulfide, and fipronil-sulfone. Fipronil-desulfinyl was not detected in any animal samples.

  1. Chronic TiO{sub 2} nanoparticle exposure to a benthic organism, Hyalella azteca: impact of solar UV radiation and material surface coatings on toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Wallis, Lindsay K. [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States); Diamond, Stephen A. [Nanosafe Inc., Blacksburg, VA, 24060 (United States); Ma, Hongbo [University of Wisconsin-Milwaukee, Zilber School of Public Health, Milwaukee, WI, 53211 (United States); Hoff, Dale J. [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States); Al-Abed, Souhail R. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268 (United States); Li, Shibin, E-mail: lishibinepa@gmail.com [Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804 (United States)

    2014-11-15

    There is limited information on the chronic effects of nanomaterials to benthic organisms, as well as environmental mitigating factors that might influence this toxicity. The present study aimed to fill these data gaps by examining various growth endpoints (weight gain, instantaneous growth rate, and total protein content) for up to a 21 d sediment exposure of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) to a representative benthic species, Hyalella azteca. An uncoated standard, P25, and an Al(OH){sub 3} coated nano-TiO{sub 2} used in commercial products were added to sediment at 20 mg/L or 100 mg/L Under test conditions, UV exposure alone was shown to be a greater cause of toxicity than even these high levels of nano-TiO{sub 2} exposure, indicating that different hazards need to be addressed in toxicity testing scenarios. In addition, this study showed the effectiveness of a surface coating on the decreased photoactivity of the material, as the addition of an Al(OH){sub 3} coating showed a dramatic decrease in reactive oxygen species (ROS) production. However, this reduced photoactivity was found to be partially restored when the coating had been degraded, leading to the need for future toxicity tests which examine the implications of weathering events on particle surface coatings. - Highlights: • Chronic toxicity of nano-TiO{sub 2} to a benthic organism (Hyalella azteca) was examined. • Phototoxicity was investigated through exposure of solar simulated radiation (SSR). • The degradation of a surface coating resulted in an increase in photoactivity. • In this testing scenario, UV had a larger impact than chemical exposure in toxicity.

  2. Toxicity of uranium, molybdenum, nickel, and arsenic to Hyalella azteca and Chironomus dilutus in water-only and spiked-sediment toxicity tests.

    Science.gov (United States)

    Liber, Karsten; Doig, Lorne E; White-Sobey, Suzanne L

    2011-07-01

    A series of laboratory spiked-sediment toxicity tests with the amphipod Hyalella azteca and the midge Chironomus dilutus were undertaken to determine acute and chronic toxicity thresholds for uranium (U), molybdenum (Mo), nickel (Ni), and arsenic (As) based on both whole-sediment (total) and pore water exposure concentrations. Water-only toxicity data were also generated from separate experiments to determine the toxicities of these metals/metalloids under our test conditions and to help evaluate the hypothesis that pore water metal concentrations are better correlated with sediment toxicity to benthic organisms than whole-sediment metal concentrations. The relative toxicity of the four elements tested differed depending on which test species was used and whether whole-sediment or pore water metal concentrations were correlated with effects. Based on measured whole-sediment concentrations, Ni and As were the two most acutely toxic elements to H. azteca with 10-d LC50s of 521 and 532 mg/kg d.w., respectively. Measured pore water concentrations indicated that U and Ni were the two most acutely toxic elements, with 10-d LC50s to H. azteca of 2.15 and 2.05 mg/L, respectively. Based on pore water metal concentrations, the no-observed-effect concentrations (NOECs) for growth were (H. azteca and C. dilutus, respectively) 0.67 and 0.21 mg/L for U, azteca and C. dilutus, respectively) 2.99 and 0.48 mg/L for U, 0.37 and 2.33 mg/L for Ni, and 58.99 and 0.42 mg/L for As. For U and Ni, results from 96-h water-only acute toxicity tests correlated well with pore water metal concentrations in acutely toxic metal-spiked sediment. This was not true for As where metalloid concentrations in overlying water (diffusion from sediment) may have contributed to toxicity. The lowest whole-sediment LOEC reported here for As was 6.6- and 4-fold higher than the Canadian Council of Ministers of the Environment interim sediment quality guideline and the Canadian Nuclear Safety Commission (CNSC

  3. Variation in the toxicity of sediment-associated substituted phenylamine antioxidants to an epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) invertebrate.

    Science.gov (United States)

    Prosser, R S; Bartlett, A J; Milani, D; Holman, E A M; Ikert, H; Schissler, D; Toito, J; Parrott, J L; Gillis, P L; Balakrishnan, V K

    2017-08-01

    Substituted phenylamine antioxidants (SPAs) are produced in relatively high volumes and used in a range of applications (e.g., rubber, polyurethane); however, little is known about their toxicity to aquatic biota. Therefore, current study examined the effects of chronic exposure (28 d) to four sediment-associated SPAs on epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) organisms. In addition, acute (96-h), water-only exposures were conducted with H. azteca. Mortality, growth and biomass production were assessed in juvenile H. azteca exposed to diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). Mortality of adult T. tubifex and reproduction were assessed following exposure to the four SPAs. The 96-h LC50s for juvenile H. azteca were 1443, 109, 250, and >22 μg/L and 28-d LC50s were 22, 99, 135, and >403 μg/g dry weight (dw) for DPA, PNA, DPPDA, and MBA, respectively. Reproductive endpoints for T. tubifex (EC50s for production of juveniles > 500 μm: 15, 9, 4, 3.6 μg/g dw, for DPA, PNA, DPPDA, and MBA, respectively) were an order of magnitude more sensitive than endpoints for juvenile H. azteca and mortality of adult worms. The variation in toxicity across the four SPAs was likely related to the bioavailability of the sediment-associated chemicals, which was determined by the chemical properties of the SPAs (e.g., solubility in water, Koc). The variation in the sensitivity between the two species was likely due to differences in the magnitude of exposure, which is a function of the life histories of the epibenthic amphipod and the endobenthic worm. The data generated from this study will support effect characterization for ecological risk assessment. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  4. Binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and these pharmaceuticals in isolated form induce oxidative stress on Hyalella azteca.

    Science.gov (United States)

    Gómez-Oliván, Leobardo Manuel; Neri-Cruz, Nadia; Galar-Martínez, Marcela; Islas-Flores, Hariz; García-Medina, Sandra

    2014-11-01

    Toxicity in natural ecosystems is usually not due to exposure to a single substance, but is rather the result of exposure to mixtures of toxic substances. Knowing the effects of contaminants as a mixture compared to their effects in isolated form is therefore important. This study aimed to evaluate the oxidative stress induced by binary mixtures of diclofenac with paracetamol, ibuprofen, naproxen, and acetylsalicylic acid and by these nonsteroidal anti-inflammatory drugs (NSAIDs) in isolated form, using Hyalella azteca as a bioindicator. The median lethal concentration (LC50) and the lowest observed adverse effect level (LOAEL) of each NSAID were obtained. Amphipods were exposed for 72 h to the latter value in isolated form and as binary mixtures. The following biomarkers were evaluated: lipid peroxidation (LPX), protein carbonyl content (PCC), and activity of the antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Significant increases in LPX and PCC with respect to the control group (p ≤ 0.05) were induced by NSAIDs both in isolated form and as binary mixtures. Changes in SOD, CAT, and GPx activity likewise occurred with NSAIDs in isolated form and as binary mixtures. In conclusion, NSAIDs used in this study induce oxidative stress on H. azteca both in isolated form and as binary mixtures, and the interactions occurring between these pharmaceuticals are probably antagonistic in type.

  5. History and sensitivity comparison of two standard whole-sediment toxicity tests with crustaceans: the amphipod Hyalella azteca and the ostracod Heterocypris incongruens microbiotest

    Directory of Open Access Journals (Sweden)

    De Cooman W.

    2015-01-01

    Full Text Available The review first details the development of the test procedures with Hyalella azteca which historically emerged as one of the recommended test species for whole-sediment assays and its gradual standardization and endorsement by national and international organizations. The sensitivity and precision of the H. azteca test for application on chemicals and on real world sediments is discussed. The review subsequently addresses the development of the whole sediment microbiotest with the ostracod crustacean Heterocypris incongruens with larvae of this test species hatched from dormant eggs (cysts, rendering this assay stock culture/maintenance free. The application of the 6-day ostracod microbiotest on sediments in Canada and in Belgium is discussed, as well as its endorsement by the ISO subsequent to an extensive international interlaboratory ring test. The sensitivity of the amphipod and ostracod tests is compared by data from studies in which both assays were applied in parallel. A comparison of more than 1000 ostracod/amphipod data pairs of a 12-year river sediment monitoring study in Flanders/Belgium confirmed that both whole-sediment assays have a similar sensitivity and that the 6-day ostracod microbiotest is a valuable and cost-effective alternative to the 10−14 day amphipod test for evaluation of the toxic hazard of polluted sediments.

  6. Monitoring acute and chronic water column toxicity in the Northern Sacramento-San Joaquin Estuary, California, USA, using the euryhaline amphipod, Hyalella azteca: 2006 to 2007.

    Science.gov (United States)

    Werner, Inge; Deanovic, Linda A; Markiewicz, Dan; Khamphanh, Manisay; Reece, Charles K; Stillway, Marie; Reece, Charissa

    2010-10-01

    After the significant population decline of several pelagic fish species in the Northern Sacramento-San Joaquin (SSJ) Estuary (CA, USA) in 2002, a study was performed to monitor water column toxicity using the amphipod Hyalella azteca. From January 1, 2006 to December 31, 2007, water samples were collected biweekly from 15 to 16 sites located in large delta channels and main-stem rivers, selected based on prevalent distribution patterns of fish species of concern. Ten-day laboratory tests with H. azteca survival and relative growth as toxicity endpoints were conducted. The enzyme inhibitor piperonyl butoxide ([PBO], 25 µg/L) was added to synergize or antagonize pyrethroid or organophosphate (OP) insecticide toxicity, respectively. Significant amphipod mortality was observed in 5.6% of ambient samples. Addition of PBO significantly changed survival or growth in 1.1% and 10.1% of ambient samples, respectively. Sites in the Lower Sacramento River had the largest number of acutely toxic samples, high occurrence of PBO effects on amphipod growth (along with sites in the South Delta), and the highest total ammonia/ammonium concentrations (0.28 ± 0.15 mg/L). Ammonia/ammonium, or contaminants occurring in mixture with these, likely contributed to the observed toxicity. Pyrethroid insecticides were detected at potentially toxic concentrations. Overall, results of this study identified specific areas and contaminants of concern and showed that water in the Northern SSJ Estuary was at times acutely toxic to sensitive invertebrates.

  7. ACUTE AND CHRONIC TOXICITY OF ALUMINUM TO A UNIONID MUSSEL (LAMPSILIS SILIQUOIDEA) AND AN AMPHIPOD (HYALELLA AZTECA) IN WATER-ONLY EXPOSURES.

    Science.gov (United States)

    Wang, Ning; Ivey, Chris D; Brunson, Eric L; Cleveland, Danielle; Ingersoll, Chris G; Stubblefield, William A; Cardwell, Allison S

    2017-05-05

    The US Environmental Protection Agency (USEPA) is reviewing the protectiveness of the national ambient water quality criteria (WQC) for aluminum (Al) and compiling a toxicity dataset to update the WQC. Freshwater mussels are one of the most imperiled groups of animals in the world, but little is known about the sensitivity of mussels to Al. The objective of the present study was to evaluate acute 96-h and chronic 28-d toxicity of Al to a unionid mussel (Lampsilis siliquoidea) and a commonly tested amphipod (Hyalella azteca) at a pH of 6 and water hardness of 100 mg/L as CaCO3 . Acute 50% effect concentration (EC50) for survival of both species was >6,200 µg total Al/L. The EC50 was greater than all acute values in the USEPA acute Al dataset for freshwater species at pH range of 5.0 to azteca) as the 5th most sensitive species, indicating the two species were sensitive to Al in chronic exposures. The USEPA proposed acute and chronic WQC for Al would adequately protect the mussel and amphipod tested; however, inclusion of the chronic data from the present study and recalculation of the chronic criterion would likely lower the proposed chronic criterion. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Causes of toxicity to Hyalella azteca in a stormwater management facility receiving highway runoff and snowmelt. Part II: salts, nutrients, and water quality.

    Science.gov (United States)

    Bartlett, A J; Rochfort, Q; Brown, L R; Marsalek, J

    2012-01-01

    The Terraview-Willowfield Stormwater Management Facility (TWSMF) features a tandem of stormwater management ponds, which receive inputs of multiple contaminants from highway and residential runoff. Previous research determined that benthic communities in the ponds were impacted by poor habitat quality, due to elevated sediment concentrations of metals and polycyclic aromatic hydrocarbons (PAHS), and salinity in the overlying water, but did not address seasonal changes, including those caused by the influx of contaminants with the snowmelt. In order to address this issue, water and sediment samples were collected from the TWSMF during the fall and spring, and four-week sediment toxicity tests were conducted with Hyalella azteca. The effects of metals and PAHs are discussed in a companion paper; the effects of road salt, nutrients, and water quality are discussed here. After exposure to fall samples, survival of Hyalella was reduced (64-74% of controls) at three out of four sites, but growth was not negatively affected. After exposure to spring samples, survival was 0-75% of controls at the two sites furthest downstream, and growth was significantly lower in four out of five sites when comparing Hyalella exposed to site water overlying site sediment versus control water overlying site sediment. Toxicity appeared to be related to chloride concentrations: little or no toxicity occurred in fall samples (200 mg Cl(-)/L), and significant effects on survival and growth occurred in spring samples above 1550 mg Cl(-)/L and 380 mg Cl(-)/L, respectively. Sodium chloride toxicity tests showed similar results: four-week LC50s and EC25s (growth) were 1200 and 420 mg Cl(-)/L, respectively. Although water quality and nutrients were associated with effects observed in the TWSMF, chloride from road salt was the primary cause of toxicity in this study. Chloride persists during much of the year at concentrations representing a significant threat to benthic communities in the TWSMF.

  9. Acute and chronic toxicity of imidacloprid to the aquatic invertebrates Chironomus tentans and Hyalella azteca under constant- and pulse-exposure conditions.

    Science.gov (United States)

    Stoughton, Sarah J; Liber, Karsten; Culp, Joseph; Cessna, Allan

    2008-05-01

    The toxicity of imidacloprid, a nicotinic mimic insecticide, to the aquatic invertebrates Chironomus tentans and Hyalella azteca, was first evaluated in static 96-hour tests using both technical material (99.2% pure) and Admire, a commercially available formulated product (240 g a.i. L(-1)). The 96-h lethal concentration (LC)50 values for technical imidacloprid and Admire were 65.43 and 17.44 microg/L, respectively, for H. azteca, and 5.75 and 5.40 microg/L, respectively, for C. tentans. Admire was subsequently used in 28-day chronic tests with both species. Exposure scenarios consisted of a constant- and a pulse-exposure regime. The pulse exposure lasted for four days, after which time the animals were transferred to clean water for the remaining 24 days of the study. Assessments were made on both day 10 and day 28. In the C. tentans under constant exposure, larval growth on day 10 was significantly reduced at 3.57 microg/L imidacloprid, the lowest-observed-effect concentration (LOEC). The no-observed-effect concentration (NOEC) and LOEC for the 28-day exposure duration (adult survival and emergence) were 1.14 and greater than 1.14 mug/L, respectively; the associated LC50 and LC25 were 0.91 and 0.59 microg/L, respectively. The LOEC for the pulse treatment was greater than 3.47 microg/L, but the day 10 LC25 was 3.03 microg/L. In the H. azteca tests, the day 10 and 28 constant exposure, as well as the day 28 pulse exposure, LOEC (survival) values were similar at 11.95, 11.46, and 11.93 microg/L, respectively. The day 10 and 28 constant exposure effective concentration (EC)25s (dry weight) were also similar, at 6.22 and 8.72 microg/L, respectively, but were higher than the pulse-exposure day 10 LOEC and EC25 (dry weight) values of 3.53 and 2.22 microg/L, respectively. Overall, C. tentans was more sensitive to acute and chronic imidacloprid exposure, but less sensitive to a single pulse, than H. azteca. Chronic, low-level exposure to imidacloprid may therefore reduce

  10. Validation of a new standardized test method for the freshwater amphipod Hyalella azteca: Determining the chronic effects of silver in sediment.

    Science.gov (United States)

    Taylor, Lisa N; Novak, Lesley; Rendas, Martina; Antunes, Paula M C; Scroggins, Rick P

    2016-10-01

    Environment Canada has developed a new 42-d sediment toxicity test method that includes a reproduction test endpoint with the freshwater amphipod Hyalella azteca. Because of concerns that existing standard methodologies, whereby adults are transferred to a water-only exposure before release of their first brood at day 28, will lead to internal contaminant depuration and loss of sensitivity, the Environment Canada methodology conducts the entire exposure in sediment. To demonstrate applicability of the method for assessing the toxicity of chemical-spiked sediment, H. azteca were exposed for 42 d to sediment amended with silver nitrate (AgNO3 ). Mortality was significantly higher at the highest sediment concentration of Ag (2088 mg/kg dry wt); however, there was no significant reduction in biomass or reproduction as a result of Ag exposure despite significant bioaccumulation. Based on Ag measurements and speciation modeling, the principle route of Ag exposure was likely through the ingestion of complexed colloidal or particulate Ag. The techniques used to recover young amphipods from sediment were critical, and although this effort can be labor intensive (20-45 min/replicate), the technicians demonstrated 91% recovery in blind trials. For the first time, Environment Canada will require laboratories to report their recovery proficiency for the 42-d test-without this information, data will not be accepted. Overall, the reproduction test will be more applicable when only a few chemical concentrations need to be evaluated in laboratory-amended sediments or for field-collected contaminated site assessments (i.e., contaminated site vs reference site comparisons). Environ Toxicol Chem 2016;35:2430-2438. © 2016 SETAC.

  11. An analysis of lethal and sublethal interactions among type I and type II pyrethroid pesticide mixtures using standard Hyalella azteca water column toxicity tests.

    Science.gov (United States)

    Hoffmann, Krista Callinan; Deanovic, Linda; Werner, Inge; Stillway, Marie; Fong, Stephanie; Teh, Swee

    2016-10-01

    A novel 2-tiered analytical approach was used to characterize and quantify interactions between type I and type II pyrethroids in Hyalella azteca using standardized water column toxicity tests. Bifenthrin, permethrin, cyfluthrin, and lambda-cyhalothrin were tested in all possible binary combinations across 6 experiments. All mixtures were analyzed for 4-d lethality, and 2 of the 6 mixtures (permethrin-bifenthrin and permethrin-cyfluthrin) were tested for subchronic 10-d lethality and sublethal effects on swimming motility and growth. Mixtures were initially analyzed for interactions using regression analyses, and subsequently compared with the additive models of concentration addition and independent action to further characterize mixture responses. Negative interactions (antagonistic) were significant in 2 of the 6 mixtures tested, including cyfluthrin-bifenthrin and cyfluthrin-permethrin, but only on the acute 4-d lethality endpoint. In both cases mixture responses fell between the additive models of concentration addition and independent action. All other mixtures were additive across 4-d lethality, and bifenthrin-permethrin and cyfluthrin-permethrin were also additive in terms of subchronic 10-d lethality and sublethal responses. Environ Toxicol Chem 2016;35:2542-2549. © 2016 SETAC.

  12. Chronic TiO₂ nanoparticle exposure to a benthic organism, Hyalella azteca: impact of solar UV radiation and material surface coatings on toxicity.

    Science.gov (United States)

    Wallis, Lindsay K; Diamond, Stephen A; Ma, Hongbo; Hoff, Dale J; Al-Abed, Souhail R; Li, Shibin

    2014-11-15

    There is limited information on the chronic effects of nanomaterials to benthic organisms, as well as environmental mitigating factors that might influence this toxicity. The present study aimed to fill these data gaps by examining various growth endpoints (weight gain, instantaneous growth rate, and total protein content) for up to a 21 d sediment exposure of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca. An uncoated standard, P25, and an Al(OH)3 coated nano-TiO2 used in commercial products were added to sediment at 20 mg/L or 100 mg/L Under test conditions, UV exposure alone was shown to be a greater cause of toxicity than even these high levels of nano-TiO2 exposure, indicating that different hazards need to be addressed in toxicity testing scenarios. In addition, this study showed the effectiveness of a surface coating on the decreased photoactivity of the material, as the addition of an Al(OH)3 coating showed a dramatic decrease in reactive oxygen species (ROS) production. However, this reduced photoactivity was found to be partially restored when the coating had been degraded, leading to the need for future toxicity tests which examine the implications of weathering events on particle surface coatings.

  13. An effects addition model based on bioaccumulation of metals from exposure to mixtures of metals can predict chronic mortality in the aquatic invertebrate Hyalella azteca.

    Science.gov (United States)

    Norwood, Warren P; Borgmann, Uwe; Dixon, D George

    2013-07-01

    Chronic toxicity tests of mixtures of 9 metals and 1 metalloid (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Tl, and Zn) at equitoxic concentrations over an increasing concentration range were conducted with the epibenthic, freshwater amphipod Hyalella azteca. The authors conducted 28-d, water-only tests. The bioaccumulation trends changed for 8 of the elements in exposures to mixtures of the metals compared with individual metal exposures. The bioaccumulation of Co and Tl were affected the most. These changes may be due to interactions between all the metals as well as interactions with waterborne ligands. A metal effects addition model (MEAM) is proposed as a more accurate method to assess the impact of mixtures of metals and to predict chronic mortality. The MEAM uses background-corrected body concentration to predict toxicity. This is important because the chemical characteristics of different waters can greatly alter the bioavailability and bioaccumulation of metals, and interactions among metals for binding at the site of action within the organism can affect body concentration. The MEAM accurately predicted toxicity in exposures to mixtures of metals, and predicted results were within a factor of 1.1 of the observed data, using 24-h depurated body concentrations. The traditional concentration addition model overestimated toxicity by a factor of 2.7.

  14. Contaminants in stream sediments from seven United States metropolitan areas: part II--sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus.

    Science.gov (United States)

    Kemble, Nile E; Hardesty, Douglas K; Ingersoll, Christopher G; Kunz, James L; Sibley, Paul K; Calhoun, Daniel L; Gilliom, Robert J; Kuivila, Kathryn M; Nowell, Lisa H; Moran, Patrick W

    2013-01-01

    Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs, OC pesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants.

  15. Re-evaluation of metal bioaccumulation and chronic toxicity in Hyalella azteca using saturation curves and the biotic ligand model

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U.; Norwood, W.P.; Dixon, D.G

    2004-10-01

    Bioaccumulation by Hyalella of all metals studied so far in our laboratory was re-evaluated to determine if the data could be explained satisfactorily using saturation models. Saturation kinetics are predicted by the biotic ligand model (BLM), now widely used in modelling acute toxicity, and are a pre-requisite if the BLM is to be applied to chronic toxicity. Saturation models provided a good fit to all the data. Since these are mechanistically based, they provide additional insights into metal accumulation mechanisms not immediately apparent when using allometric models. For example, maximum Cd accumulation is dependent on the hardness of the water to which Hyalella are acclimated. The BLM may need to be modified when applied to chronic toxicity. Use of saturation models for bioaccumulation, however, also necessitates the need for using saturation models for dose-response relationships in order to produce unambiguous estimates of LC50 values based on water and body concentrations. This affects predictions of toxicity at very low metal concentrations and results in lower predicted toxicity of mixtures when many metals are present at low concentrations.

  16. No Evidence for Temporal Variation in a Cryptic Species Community of Freshwater Amphipods of the Hyalella azteca Species Complex

    Directory of Open Access Journals (Sweden)

    Christian Nozais

    2011-08-01

    Full Text Available The co-occurrence of cryptic species of Hyalella amphipods is a challenge to our traditional views of how species assemble. Since these species have similar morphologies, it is not evident that they have developed phenotypic differences that would allow them to occupy different ecological niches. We examined the structure of a community of Hyalella amphipods in the littoral zone of a boreal lake to verify if temporal variation was present in relative abundances. Morphological and molecular analyses using the mitochondrial cytochrome c oxidase I (COI gene enabled us to detect three cryptic species at the study site. No temporal variation was observed in the community, as one cryptic species was always more abundant than the two others. The relative abundances of each species in the community appeared constant at least for the open-water season, both for adult and juvenile amphipods. Niche differences are still to be found among these species, but it is suggested that migration from nearby sites may be an important factor explaining the species co-occurrence.

  17. Sediment contamination of residential streams in the metropolitan Kansas City area, USA: Part II. Whole-sediment toxicity to the amphipod Hyalella azteca.

    Science.gov (United States)

    Tao, J; Ingersoll, C G; Kemble, N E; Dias, J R; Murowchick, J B; Welker, G; Huggins, D

    2010-10-01

    This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects were explored. The sediments exhibited a low to moderate toxicity, with five samples identified as toxic to H. azteca. Metals did not likely cause the toxicity based on low concentrations of metals in the pore water and elevated concentrations of acid volatile sulfide in the sediments. Although individual polycyclic aromatic hydrocarbons (PAHs) frequently exceeded effect-based sediment quality guidelines [probable effect concentrations (PECs)], only four of the samples had a PEC quotient (PEC-Q) for total PAHs over 1.0 and only one of these four samples was identified as toxic. For the mean PEC-Q for organochlorine compounds (chlordane, dieldrin, sum DDEs), 4 of the 12 samples with a mean PEC-Q above 1.0 were toxic and 4 of the 8 samples with a mean PEC-Q above 3.0 were toxic. Additionally, four of eight samples were toxic, with a mean PEC-Q above 1.0 based on metals, PAHs, polychlorinated biphenyls (PCBs), and organochlorine pesticides. The increase in the incidence of toxicity with the increase in the mean PEC-Q based on organochlorine pesticides or based on metals, PAHs, PCBs, and organochlorine pesticides suggests that organochlorine pesticides might have contributed to the observed toxicity and that the use of a mean PEC-Q, rather than PEC-Qs for individual compounds, might be more informative in predicting toxic effects. Our study shows that stream sediments subject to predominant nonpoint sources contamination can be toxic and that many factors, including analysis of a full suite of PAHs and pesticides of both past and present urban applications and the origins of

  18. Sediment contamination of residential streams in the metropolitan kansas city area, USA: Part II. whole-sediment toxicity to the amphipod hyalella azteca

    Science.gov (United States)

    Tao, J.; Ingersoll, C.G.; Kemble, N.E.; Dias, J.R.; Murowchick, J.B.; Welker, G.; Huggins, D.

    2010-01-01

    This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects were explored. The sediments exhibited a low to moderate toxicity, with five samples identified as toxic to H. azteca. Metals did not likely cause the toxicity based on low concentrations of metals in the pore water and elevated concentrations of acid volatile sulfide in the sediments. Although individual polycyclic aromatic hydrocarbons (PAHs) frequently exceeded effect-based sediment quality guidelines [probable effect concentrations (PECs)], only four of the samples had a PEC quotient (PEC-Q) for total PAHs over 1.0 and only one of these four samples was identified as toxic. For the mean PEC-Q for organochlorine compounds (chlordane, dieldrin, sum DDEs), 4 of the 12 samples with a mean PEC-Q above 1.0 were toxic and 4 of the 8 samples with a mean PEC-Q above 3.0 were toxic. Additionally, four of eight samples were toxic, with a mean PEC-Q above 1.0 based on metals, PAHs, polychlorinated biphenyls (PCBs), and organochlorine pesticides. The increase in the incidence of toxicity with the increase in the mean PEC-Q based on organochlorine pesticides or based on metals, PAHs, PCBs, and organochlorine pesticides suggests that organochlorine pesticides might have contributed to the observed toxicity and that the use of a mean PEC-Q, rather than PEC-Qs for individual compounds, might be more informative in predicting toxic effects. Our study shows that stream sediments subject to predominant nonpoint sources contamination can be toxic and that many factors, including analysis of a full suite of PAHs and pesticides of both past and present urban applications and the origins of

  19. Does long-term fungicide exposure affect the reproductive performance of leaf-shredders? A partial life-cycle study using Hyalella azteca.

    Science.gov (United States)

    Baudy, Patrick; Zubrod, Jochen P; Konschak, Marco; Weil, Mirco; Schulz, Ralf; Bundschuh, Mirco

    2017-03-01

    Leaf-shredding amphipods play a critical role in the ecosystem function of leaf litter breakdown, a key process in many low order streams. Fungicides, however, may adversely influence shredders' behavior and the functions they provide, while there is only limited knowledge concerning effects on their reproductive performance. To assess the latter, a semi-static 56-day partial life-cycle bioassay using the model shredder Hyalella azteca (n = 30) was performed applying two environmentally relevant concentrations of a model fungicide mixture (i.e., 5 and 25 μg/L) composed of five fungicides with different modes of toxic action. Variables related to the food processing (leaf consumption and feces production), growth (body length and dry weight), energy reserves (lipid content), and reproduction (amplexus pairs, number and length of offspring) were determined to understand potential implications in the organisms' energy budget. While the fungicides did not affect leaf consumption, both fungicide treatments significantly reduced amphipods' feces production (∼20%) compared to the control. This observation suggests an increased food utilization to counteract the elevated and stress-related energy demand: although growth as well as energy reserves were unaffected, amplexus pairs were less frequently observed in both fungicide treatments (∼50-100%) suggesting a tradeoff regarding energy allocation favoring the maintenance of fundamental functions at the organism level over reproduction. As a result, the time to release of first offspring was delayed in both fungicide treatments (7 and 14 days) and the median number of offspring was significantly lower in the 25-μg/L treatment (100%), whereas offspring length remained unaffected. The results of this study thus indicate that chronic fungicide exposures can negatively impact shredders' reproductive performance. This may translate into lower abundances and thus a reduced contribution to leaf litter breakdown in

  20. 酸损害湖泊中底栖无脊椎动物(Stenacron interpunctatum,Stenonema femoratum和Hyalella azteca)的再集群现象%Recolonization of Acid-damaged Lakes by the Benthic Invertebrates Stenacron interpunctatum, Stenonema femoratum and Hyalella azteca

    Institute of Scientific and Technical Information of China (English)

    Ed Snucins

    2003-01-01

    本文描述了加拿大基拉尼公园里的酸损害湖中3种底栖无脊椎动物的再集群现象:它们是两种蜉蝣类动物(Stenonema femoratum,Stenacron interpunctatum)和一种端足类甲壳动物(Hyalella azteca)。1995-1997年间对119个湖的端足类甲壳动物以及77个湖的蜉蝣类动物进行了概要调查,同时确定Stenonema femoratum和Hyalella azteca的pH临界值是5.6。而Stenacron interpunctatum的pH临界值是5.3。从1997-2002年,通过对2个酸损害湖和2个参考湖深入研究。在能够估计出出现时间的地方,种的pH阈值达到后不到4-8年。就可以重建Stenacron interpunctatum,Stenonema femoratum和Hyalella azteca。在最小的湖(11hm2)中监测到集群现象之后3年。该湖内Stenacron interpunctatum到所有栖息地的扩散完成。可以预测,Stenacron interpunctatum在最大的湖(189hm2)内的扩散需要更长的时间。从估算的pH值恢复到湖内蜉蝣类动物重建,再到其后扩散到所有适合栖息地的时间滞后为11-22年之久或更长。虽然在恢复湖中Stenacron interpunctatum的密度增加到高于参考湖的水平。但在6年期间的监测中尚未达到稳定的终点。

  1. Redescription of the freshwater amphipod Hyalella faxoni from Costa Rica (Crustacea: Amphipoda: Hyalellidae

    Directory of Open Access Journals (Sweden)

    Exequiel R. González

    2002-06-01

    Full Text Available Hyalella faxoni Stebbing, 1903 from Costa Rica is redescribed. The species was previously in the synonymy of Hyalella azteca (Saussure, 1858. The morphological differences between these two species are discussedLa especie Hyalella faxoni Stebbing, 1903 de Costa Rica es redescrita. Esta especie estaba previamente en la sinonimia de Hyalella azteca (Saussure, 1858. Se discuten en este trabajo las diferencias morfológicas entre las dos especies

  2. Contaminants in stream sediments from seven United States metropolitan areas: part II—sediment toxicity to the amphipod Hyalella azteca and the midge Chironomus dilutus

    Science.gov (United States)

    Kemble, Nile E.; Hardesty, Douglas K.; Ingersoll, Christopher G.; Kunz, James L.; Sibley, Paul K.; Calhoun, Daniel L.; Gilliom, Robert J.; Kuivila, Kathryn; Nowell, Lisa H.; Moran, Patrick W.

    2013-01-01

    Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs,OCpesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants. Sediments are a repository for many contaminants released into surface waters. Because of this, organisms inhabiting sediments may be exposed to a wide range of contaminants (United States Environmental Protection Agency (USEPA) United States Environmental Protection Agency 2000; American Society for Testing and Materials [ASTM] American Society for Testing and Materials International 2012). Contaminants of potential concern in sediments typically include trace elements (metals

  3. Relative contribution of food and water to 27 metals and metalloids accumulated by caged Hyalella azteca in two rivers affected by metal mining

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)]. E-mail: uwe.borgmann@ec.gc.ca; Couillard, Y. [Existing Substances Division, Environment Canada, 351 Saint-Joseph Boulevard, Gatineau, QC, K1A 0H3 (Canada); Grapentine, L.C. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)

    2007-02-15

    Hyalella were caged at three sites in each of the two rivers for 17 days. Food added to the cages consisted of plant and detrital material collected from the same, or other, sites. Concentrations of some metals in Hyalella (e.g., Cd and Cu), but not others (e.g., Se), appeared to reach steady-state within 5 days in one of the rivers. Metal accumulation was minimal by day 5 in the other river, possibly due to the very low temperatures in this river for the first part of the exposure period. Both analysis of variance and analysis of covariance, using site as a categorical variable and metal in food as either a categorical or continuous variable, indicated that Cd, Cu and Se were the only metals for which concentration in food had a significant effect on concentration in Hyalella. Nevertheless, water was still a major source for these metals as well. Other metals which varied by over fivefold in food but for which concentration in food had no effect on concentration in Hyalella included Ag, As, Bi, Sb, U and Zn. Concentrations of the remaining metals varied less than fourfold in food, making it difficult to determine if these were accumulated from food. - Cadmium, copper and selenium were the only metals in food that correlated with increased body concentrations of metals in Hyalella, but even these metals were accumulated largely from water.

  4. Relative sensitivity of an amphipod Hyalella azteca, a midge Chironomus dilutus, and a unionid mussel Lampsilis siliquoidea to a toxic sediment.

    Science.gov (United States)

    Ingersoll, Chris G; Kunz, James L; Hughes, Jamie P; Wang, Ning; Ireland, D Scott; Mount, David R; Hockett, J Russell; Valenti, Theodore W

    2015-05-01

    The objective of the present study was to evaluate the relative sensitivity of test organisms in exposures to dilutions of a highly toxic sediment contaminated with metals and organic compounds. One dilution series was prepared using control sand (low total organic carbon [TOC; azteca; 10-d and 28-d exposures), a midge (Chironomus dilutus; 20-d and 48-d exposures started with azteca were more sensitive endpoints in 28-d exposures than in 10-d exposures. Weight and biomass of L. siliquoidea were sensitive endpoints in both sand and West Bearskin Lake sediment dilutions. Metals, ammonia, oil, and other organic contaminants may have contributed to the observed toxicity.

  5. SENSITIVITY DIFFERENCE AMONG VARIOUS STRAINS OF HYALLELA AZTECA

    Science.gov (United States)

    The North American amphipod Hyalella azteca is widely used in toxicity testing. H. azteca has a broad geographic distribution, and genetic evidence suggests that populations diverged from each other long ago. The importance of this genetic divergence to toxicity testing is uncle...

  6. SENSITIVITY DIFFERENCE AMONG VARIOUS STRAINS OF HYALLELA AZTECA

    Science.gov (United States)

    The North American amphipod Hyalella azteca is widely used in toxicity testing. H. azteca has a broad geographic distribution, and genetic evidence suggests that populations diverged from each other long ago. The importance of this genetic divergence to toxicity testing is uncle...

  7. Evaluation of toxicity to the amphipod, Hyalella azteca, and to the midge, Chironomus dilutus; and bioaccumulation by the oligochaete, Lumbriculus variegatus, with exposure to PCB-contaminated sediments from Anniston, Alabama

    Science.gov (United States)

    Ingersoll, Christopher G.; Steevens, Jeffery A.; MacDonald, Donald D.; Brumbaugh, William G.; Coady, Matthew R.; Farrar, J. Daniel; Lotufo, Guilherme R.; Kemble, Nile E.; Kunz, James L.; Stanley, Jacob K.; Sinclair, Jesse A.; Ingersoll, Christopher G.; Steevens, Jeffery A.; MacDonald, Donald D.

    2014-01-01

    The U.S. Environmental Protection Agency (USEPA) requested that as part of the remedial investigation for the Anniston, Alabama Polychlorinated Biphenyl (PCB) Site (Anniston PCB Site), that Pharmacia Corporation and Solutia Inc. (P/S) perform long-term reproduction toxicity tests with the amphipod, Hyalella azteca, and the midge, Chironomus dilutus, and bioaccumulation tests with the oligochaete, Lumbriculus variegatus, using sediment samples collected from reference locations and from Operable Unit 4 of the Anniston PCB Site. The sediment toxicity testing and sediment bioaccumulation results will be used by ARCADIS U.S., Inc. (ARCADIS) as part of a weight-of-evidence assessment to evaluate risks and establish sediment remediation goals for contaminants to sediment-dwelling organisms inhabiting the Anniston PCB Site. The goal of this study was to characterize relations between sediment chemistry and sediment toxicity and relations between sediment chemistry and sediment bioaccumulation in samples of sediments collected from the Anniston PCB Site. A total of 32 samples were evaluated from six test sites and one reference site to provide a wide range in concentrations of chemicals of potential concern (COPCs) including PCBs in samples of whole sediment. The goal of this study was not to determine the extent of sediment contamination across the Anniston PCB Site. Hence, the test sites or samples collected from within a test site were not selected to represent the spatial extent of sediment contamination across the Anniston PCB Site. Sediment chemistry, pore-water chemistry, and sediment toxicity data were generated for 26 sediment samples from the Anniston PCB Site. All of the samples were evaluated to determine if they qualified as reference sediment samples. Those samples that met the chemical selection criteria and biological selection criteria were identified as reference samples and used to develop the reference envelope for each toxicity test endpoint. Physical

  8. Toxicity Tests of Whole Sediment Samples Using the Hyallella (H. azteca) Survival and Growth Tests (ASTM E 1283-93)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — 10-day toxicity tests using Hyalella azteca were conducted with sediment samples collected by the U.S. Fish & Wildlife Service, Bloomington, Indiana facility to...

  9. Simultaneous determination of the Cd and Zn total body burden of individual, nearly microscopic, nanoliter-volume aquatic organisms (Hyalella azteca) by rhenium-cup in-torch vaporization (ITV) sample introduction and axially viewed ICP-AES

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Andrea T.; Badiei, Hamid R.; Karanassios, Vassili [University of Waterloo, Department of Chemistry, Waterloo, ON (Canada); Evans, J. Catherine [University of Waterloo, Department of Biology, Waterloo, ON (Canada)

    2004-09-01

    The Cd and Zn total body burden of individual, up to 7-day-old aquatic organisms (Hyalella aztecabenthic amphipod) with an average volume of approximately 100 nL was determined simultaneously by using rhenium-cup (Re-cup) in-torch vaporization (ITV) sample introduction and an axially viewed inductively coupled plasma atomic emission spectrometry (ICP-AES) system. The direct elemental analysis capabilities of this system (i.e., no sample digestion) reduced sample preparation time, eliminated contamination concerns from the digestion reagent and, owing to its detection limits (e.g., in the low pg range for Cd and Zn), vit enabled simultaneous determinations of Cd and Zn in individual, neonate and young juvenile specimens barely visible to the unaided eye (e.g., nearly microscopic). As for calibration, liquid standards and the standard additions method were tested. Both methods gave comparable results, thus indicating that in this case liquid standards can be employed for calibration, and in the process making use of the standard additions method unnecessary. Overall, the ITV-ICP-AES approach by-passed the time-consuming acid digestions, eliminated the potential for contamination from the digestion reagents, improved considerably the speed of acquisition of analytical information and enabled simultaneous determinations of two elements using individual biological specimens. (orig.)

  10. Preparation and characterization of a hetero functional system of gold nanoparticles labeled with {sup 99m}Tc and conjugated to the sequence Arg-Gly-Asp for detection in vivo of angio genesis and evaluation of their toxicity in Hyalella aztec; Preparacion y caracterizacion de un sistema heterofuncional de nanoparticulas de oro marcadas con Tecnecio-99m y conjugadas a la secuencia Arg-Gly-Asp para la deteccion in vivo de angiogenesis y la evaluacion de su toxicidad en Hyalella azteca

    Energy Technology Data Exchange (ETDEWEB)

    Morales A, E.

    2012-07-01

    Integrin s play critical roles in many physiological processes including angio genesis and also contribute to pathological events such as tumor invasion and metastasis. The {alpha}{sub v}{beta}{sub 3} integrin is expressed in normal endothelial cells but it is over-expressed in the tumor neo vasculature. Peptides based on the Arginine-Glycine-Aspartic acid (RGD) sequence have been reported as molecules with high affinity and selectivity for the {alpha}{sub v}{beta}{sub 3} integrin. Recent studies have demonstrated that conjugating peptides to gold nanoparticles (AuNP) produces biocompatible and stable multifunctional systems with target-specific molecular recognition due to multivalent effects produced by multiple simultaneous interactions between peptides and their receptors. The first aim of this research was to prepare a m ultimeric system of {sup 99m}Tc labeled gold particles conjugated to c[RGDfK(C)] and to evaluate its biological behavior as a potential radiopharmaceutical for molecular imaging of {alpha}{sub v}{beta}{sub 3} tumor expression. Hidrazinonicotinamide-G GC (HYNIC-G GC) and C[RGDfK(C)] peptides were synthesized and conjugated to AuNP (20 nm) by means of spontaneous reaction of the thiol groups of cysteine. The nano conjugate was characterized by transmission electron microscopy, Fourier transform-infrared, Ultraviolet-vis, X-ray photoelectron spectroscopy and Raman spectroscopy. To obtain {sup 99m}Tc-HYNIC-G GC-AuNP-c[RGDfK(C)], the {sup 99m}Tc-HYNIC-G GC radio peptide was first prepared and added to the AuNP solution followed by c[RGDfK(C)]. Radiochemical purity (Rp) was determined by size-exclusion HPLC and I TLC-Sg analyses. In vitro binding studies were carried out in {alpha}{sub v}{beta}{sub 3} receptor-positive C6 glioma cancer cells. Biodistribution studies were accomplished in athymic mice with C6-induced tumors with blocked and non blocked receptors, and images were obtained using a micro-SPECT/CT. Transmission electron microscopy and

  11. Effects of calcium, magnesium, and sodium on alleviating cadmium toxicity to Hyalella azteca

    Science.gov (United States)

    Jackson, B.P.; Lasier, P.J.; Miller, W.P.; Winger, P.V.

    2000-01-01

    Toxicity of trace metal ions to aquatic organisms, arising through either anthropogenic inputs or acidification of surface waters, continues to be both a regulatory and environmental problem. It is generally accepted that the free metal ion is the major toxic species (Florence et a1.,1992) and that inorganic or organic complexation renders the metal ion non-bioavailable (Meador, 1991, Galvez and Wood, 1997). However, water chemistry parameters such as alkalinity, hardness, dissolved organic carbon and pH influence metal ion toxicity either directly by lowering free metal ion concentration or indirectly through synergistic or antagonistic effects. Alkalinity and salinity can affect the speciation of metal ions by increasing ion-pair formation, thus decreasing free metal ion concentration. For example, Cu was found to be less toxic to rainbow trout in waters of high alkalinity (Miller and Mackay, 1980), due to formation of CuCO3 ion pair, and corresponding reduction in free Cu2+ concentration. The influence of salinity on the toxicity of cadmium to various organisms has been demonstrated in a number of studies (Bervoets et al., 1995, Hall et al., 1995, Lin and Dunson, 1993, Blust et al., 1992). In all these studies the apparent toxicity of cadmium was lowered as salinity was increased due to increased formation of CdC1+ and CDCl2 aqueous complexes that are non-toxic or of much lower toxicity than the free Cd2+ ion. Changes in pH exert both a biological and chemical effect on metal ion toxicity (Campbell and Stokes, 1985). Low pH favors greater metal ion solubility, and, in the absence of complexing ions, reduced speciation of the metal ion, which tends to increase toxicity compared to higher pH. However, Iow pH also enhances competition between H+ and metal ion for cell surface binding sites, which tends to decrease metal ion toxicity.

  12. BIOAVAILABILITY OF MERCURY IN SEDIMENTS FROM A FLOOD CONTROL RESERVOIR TO HYALELLA AZTECA

    Science.gov (United States)

    In the last three years, mercury contamination in North Mississippi flood control reservoirs has become a growing concern. Previous data indicate that three flood control reservoirs have similar total mercury sediment concentrations and that fish collected from one reservoir cont...

  13. Sediment quality assessment of Beasley Lake: Bioaccumulation and effects of pesticides in Hyalella azteca

    Science.gov (United States)

    Beasley Lake is a Conservation Evaluation Assessment Program (CEAP) watershed in the intensively cultivated Mississippi Delta, USA. Lake sediment quality at three sites was evaluated in 2004 and 2008 for biological impairment and uptake (viz. body residues) from 14 pesticides and three metabolites ...

  14. BIOAVAILABILITY OF MERCURY IN SEDIMENTS FROM A FLOOD CONTROL RESERVOIR TO HYALELLA AZTECA

    Science.gov (United States)

    In the last three years, mercury contamination in North Mississippi flood control reservoirs has become a growing concern. Previous data indicate that three flood control reservoirs have similar total mercury sediment concentrations and that fish collected from one reservoir cont...

  15. Acute toxicity of fire-retardant and foam-suppressant chemicals to yalella azteca (Saussure)

    Science.gov (United States)

    McDonald, Susan F.; Hamilton, Steven J.; Buhl, Kevin J.; Heisinger, James F.

    1997-01-01

    Acute toxicity tests were conducted with Hyalella azteca Saussure (an amphipod) exposed in soft and hard waters to three fire retardants (Fire-Trol GTS-R, Fire-Trol LCG-R, and Phos-Chek D75-F) and two foam suppressants (Phos-Chek WD-881 and Silv-Ex). The chemicals were slightly to moderately toxic to amphipods. The most toxic chemical to amphipods in soft and hard water was Phos-Chek WD-881 (96-h mean lethal concentration [LC50] equal to 10 mg/L and 22 mg/L, respectively), and the least toxic chemical to amphipods in soft water was Fire-Trol GTS-R (96-h LC50 equal to 127 mg/L) and in hard water was Fire-Trol LCG-R (96-h LC50 equal to 535 mg/L). Concentrations of ammonia in tests with the three fire retardants and both water types were greater than reported LC50 values and probably were the major toxic component. Estimated un-ionized ammonia concentrations near the LC50 were frequently less than the reported LC50 ammonia concentrations for amphipods. The three fire retardants were more toxic in soft water than in hard water even though ammonia and un-ionized ammonia concentrations were higher in hard water tests than in soft water tests. The accidental entry of fire-fighting chemicals into aquatic environments could adversely affect aquatic invertebrates, thereby disrupting ecosystem function.

  16. Analyse de Viaje al pasado: los aztecas

    Directory of Open Access Journals (Sweden)

    Denis Lucchinacci

    2005-11-01

    Full Text Available 1. Présentation du logiciel Viaje al pasado: los aztecas (el perfecto simple y el imperfecto en la narración y la descripción a été conçu par Annie Desnoyers, linguiste à l'université de Montréal et Matilde Asencio, enseignante au Cégep du Vieux Montréal (Collège d'enseignement général et professionnel [], pour un public d'étudiants d'Espagnol Langue Étrangère (ELE. Disponible en deux versions - en ligne et sous forme de cédérom -, il s'agit d'un exerciseur destiné à la pratique du passé e...

  17. Analyse de Viaje al pasado: los aztecas

    OpenAIRE

    Denis Lucchinacci

    2005-01-01

    1. Présentation du logiciel Viaje al pasado: los aztecas (el perfecto simple y el imperfecto en la narración y la descripción) a été conçu par Annie Desnoyers, linguiste à l'université de Montréal et Matilde Asencio, enseignante au Cégep du Vieux Montréal (Collège d'enseignement général et professionnel []), pour un public d'étudiants d'Espagnol Langue Étrangère (ELE). Disponible en deux versions - en ligne et sous forme de cédérom -, il s'agit d'un exerciseur destiné à la pratique du passé e...

  18. Interlaboratory Evaluation of Hyalella Azteca and Chironomus Tentans Short-term and Long-term Sediment Toxicity Tests

    Science.gov (United States)

    This paper presents the results of interlaboratory toxicity tests on sediment toxicity methods for use in routine testing and this data has been presented in an EPA report and this is a summary of that data.

  19. The Influence of Test Conditions on the Performance of Chironomus dilutus and Hyalella azteca in Sediment Toxicity Tests

    Science.gov (United States)

    In most all sediment toxicity assessments, the performance of organisms in control sediments is a key parameter in defining sediment toxicity, whether through direct statistical comparison to control or by normalizing to control performance to compare results across sites or batc...

  20. The acute and chronic toxicity of major geochemical ions to Hyalella azteca Ion interactions and comparisons to other species

    Science.gov (United States)

    We have previously reported that the acute and chronic toxicities of major geochemical ions (Na, K, Ca, Mg, Cl, SO4, HCO3) to Ceriodaphnia dubia can involve multiple, independent mechanisms. The toxicities of K, Mg, and Ca salts were best related to the chemical activity of the c...

  1. Responses of Hyalella azteca to a Pesticide-Nutrient Mixture in Vegetated and Non-vegetated Wetland Mesocosms

    Science.gov (United States)

    Aquatic vegetation has been shown to improve water quality by trapping and processing contaminants such as pesticides, nutrients and sediments. Currently there is little information regarding effects of pesticide and nutrient mixtures on aquatic biota in these systems and the influence aquatic vege...

  2. The acute and chronic toxicity of major geochemical ions to Hyalella azteca Ion interactions and comparisons to other species

    Science.gov (United States)

    We have previously reported that the acute and chronic toxicities of major geochemical ions (Na, K, Ca, Mg, Cl, SO4, HCO3) to Ceriodaphnia dubia can involve multiple, independent mechanisms. The toxicities of K, Mg, and Ca salts were best related to the chemical activity of the c...

  3. The Influence of Test Conditions on the Performance of Chironomus dilutus and Hyalella azteca in Sediment Toxicity Tests

    Science.gov (United States)

    In most all sediment toxicity assessments, the performance of organisms in control sediments is a key parameter in defining sediment toxicity, whether through direct statistical comparison to control or by normalizing to control performance to compare results across sites or batc...

  4. Interlaboratory Evaluation of Hyalella Azteca and Chironomus Tentans Short-term and Long-term Sediment Toxicity Tests

    Science.gov (United States)

    This paper presents the results of interlaboratory toxicity tests on sediment toxicity methods for use in routine testing and this data has been presented in an EPA report and this is a summary of that data.

  5. Revernacularizing Classical Nahuatl through Danza (Dance) Azteca-Chichimeca.

    Science.gov (United States)

    Tezozomoc

    Traditional Danza Azteca-Chichimeca (an indigenous dance society) contains the elements required for the intergenerational revernacularization of an indigenous language, in this case classical Nahuatl. These requirements entail creating an intergenerational environment in which participants can gain prestige, friendship, and affection and can…

  6. A new species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones, Argentina

    Science.gov (United States)

    Colla, María Florencia; César, Inés Irma

    2015-01-01

    Abstract The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina. PMID:25685030

  7. A new species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from the Atlantic Forest of Misiones, Argentina.

    Science.gov (United States)

    Colla, María Florencia; César, Inés Irma

    2015-01-01

    The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina.

  8. Pseudacteon Parasitoids of Azteca instabilis Ants in Southern Mexico (Diptera: Phoridae; Hymenoptera: Formicidae

    Directory of Open Access Journals (Sweden)

    Brian V. Brown

    2012-01-01

    Full Text Available Three new species of the genus Pseudacteon are described, all from Chiapas, Mexico, and all of which are parasitoids of the ant Azteca instabilis. Sternite 6 of Pseudacteon dorymyrmecis Borgmeier is illustrated for the first time, and P. confusus Disney is synonymized with this species. The natural history of the Azteca-Pseudacteon interaction is described.

  9. A new species of freshwater amphipod (Dogielinotidae, Hyalella from Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Rafaela Bastos-Pereira

    Full Text Available To the present 57 species of Hyalella were described for Americas, 15 of them found in Brazil, which is among the most diverse countries for this genus. This work aims to describe a new Hyalella species with benthic habits which is found in a water source on Southeastern Brazil. It is mainly characterized by a wide truncated process formed near the dactylus insertion on gnathopod 2, besides both coxal and sternall gills present on pereonits 2 to 7. This work improves the knowledge on biodiversity about Hyalella species.

  10. Water Quality And Sediment Evaluation for Inner Harbor Navigation Canal Lock Replacement Project, New Orleans, Louisiana

    Science.gov (United States)

    2011-08-01

    118 Figure 29. Hyalella azteca 10-day freshwater solid phase toxicity tests. .......................................... 123 Figure 30. Benthic...toxicity evaluation. Mean percent survival of Hyalella azteca exposed to IHNC dredged material...121 Table 40. Hyalella azteca 10-day freshwater solid phase toxicity tests

  11. Tensiones entre el esencialismo azteca y el universalismo New Age a partir del estudio de las danzas “conchero-aztecas

    OpenAIRE

    Torre, Renée de la

    2009-01-01

    El propósito del trabajo es describir y analizar comparativamente dos expresiones contemporáneas de la religiosidad mexhica que se manifiestan en los grupos de danza conocidos como concheros o aztecas. La primera es la versión mexicanista, que se opone al sincretismo con la religión católica y la cultura occidental y que plantea la esencialización de lo “auténticamente” azteca promoviendo la restauración del Anáhuac en el presente; la segunda es una versión sincrética, conocida como neomexica...

  12. Toxicity of stormwater treatment pond sediments to Hyallela azteca (Amphipoda)

    Science.gov (United States)

    Karouna-Renier, N.K.; Sparling, D.W.

    1997-01-01

    Stormwater wetlands are created to contain runoff from human developments and are designed to retain contaminants such as heavy metals, petroleum hydrocarbons, silt, pesticides, and nutrients before the runoff enter natural waterways. Because of this design, stormwater wetlands have a potential of becoming toxic sinks to organisms utilizing the wetlands for habitat. We conducted a 10-day sediment bioassay on Hyallela azteca as part of a larger study on the possible hazards of stormwater wetlands to aquatic invertebrates. Water and sediments from 10 wetlands separated into reference, residential, commercial, and highway land uses were used. No differences in survival were observed among land use categories, possibly because the ratio of acid volatile sulfides/simultaneously extractable metals (AVS/SEM) was > 1.0 for all of the ponds tested; values > 1 in this ratio are indications that toxic metals may not be bioavailable. Survival and growth rates correlated positively with AVS.

  13. Inter-lab testing of Hyalella azteca water and sediment methods: 3 Results from 10- to 42-d tests conducted with the new water-only method

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  14. Inter-lab testing of Hyalella azteca water and sediment methods: 1 Summary of 10- to 42-d data from 25 laboratories

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  15. Inter-lab testing of Hyalella azteca water and sediment methods: 1 background and overview of the 42-d survival, growth and reproduction test

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  16. Inter-lab testing of Hyalella azteca water and sediment methods: 4 Results from 10- to 42-d tests conducted with sediment substrates

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  17. Inter-lab testing of Hyalella azteca water and sediment methods: 4 Results from 10- to 42-d tests conducted with sediment substrates

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  18. Inter-lab testing of Hyalella azteca water and sediment methods: 1 Summary of 10- to 42-d data from 25 laboratories

    Science.gov (United States)

    Over the past four years, USEPA Duluth, USGS Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  19. Inter-lab testing of Hyalella azteca water and sediment methods: 1 background and overview of the 42-d survival, growth and reproduction test

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  20. Inter-lab testing of Hyalella azteca water and sediment methods: 3 Results from 10- to 42-d tests conducted with the new water-only method

    Science.gov (United States)

    Over the past four years, USEPA-Duluth, USGS-Columbia, the Illinois Natural History Survey, and Environment Canada have been conducting studies to refine the USEPA and ASTM International methods for conducting 10- to 42-d water or sediment toxicity exposures with the amphipod Hya...

  1. Toxicity of bed sediments from the Niagara River Area of Concern and tributaries, New York, to Chironomus dilutus and Hyalella azteca, 2014-15

    Science.gov (United States)

    George, Scott D.; Baldigo, Barry P.; Duffy, Brian T.

    2016-09-20

    The Niagara River was designated as an Area of Concern in 1987 on both the United States and Canadian sides of the international boundary line because past industrial discharges and hazardous waste sites had caused extensive degradation of aquatic habitats. The degradation of the “benthos”, or the benthic macroinvertebrate community, was identified as one of seven beneficial use impairments caused by contaminated bed sediments. The U.S. Geological Survey and the New York State Department of Environmental Conservation, in cooperation with the U.S. Environmental Protection Agency, conducted a study in 2014 and 2015 to gather more extensive data on (a) the toxicity of bed sediments and (b) the status of macroinvertebrate communities on the main stem and tributaries of the Niagara River. This report addresses the first component of that study (toxicity of bed sediments), and summarizes results from laboratory toxicity tests that compare the survival and growth of two macroinvertebrate species between bed sediments from study sites and laboratory controls. Sediment toxicity was negligible at most sites, however poor performance of one or both test species in bed sediments from several tributary sites suggests that the quality of sediments may be adversely affecting benthic macroinvertebrate communities in some tributaries to the Niagara River.

  2. The first hypothelminorheic Crustacea (Amphipoda, Dogielinotidae, Hyalella from South America

    Directory of Open Access Journals (Sweden)

    Stella Rodrigues

    2012-11-01

    Full Text Available Most of known troglobiotic species occur in caves and subterranean environments from great depths. However, recently more attention has been given to other subterranean environments, such as the hypothelminorheic habitats. It comprises the most superficial among all subterranean habitats. This kind of environment is characterized by the constant presence of wet spots, absence of light and very particular abiotic characteristics, comprising unique species. The first hypothelminorheic Amphipoda from South America is here described, a new species of the genus Hyalella which occurs in a wetland on Southern Brazil. The new species differs from other troglobiotics of the genus by the presence of a curved seta on the inner ramus of uropod 1 and elongation of appendices, as the first pair of antennae and peraeopods 6 and 7. However, human impacts in the area where the new species occurs have changed heavily their habitat, which may have led the species to a critical level of threat or even extinction, demonstrating the fragility of this environment.a

  3. First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae).

    Science.gov (United States)

    Cardoso, Danon Clemes; Cristiano, Maykon Passos; Barros, Luísa Antônia Campos; Lopes, Denilce Meneses; Pompolo, Silvia das Graças

    2012-01-01

    In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae). Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3) and sequential base-specific fluorochromes. The analysis shows that Azteca trigona has a diploid number of 28 chromosomes. The karyotype consists of five metacentric pairs, seven acrocentric pairs and two pseudo-acrocentric pairs, which represents a karyotype formula 2K= 10M + 14A + 4A(M) and a diploid number of the arms 2AN = 38. The analysis of heterochromatin distribution revealed a positive block on distal region of the short arm of fourth metacentric pair, which was coincident with Ag-NOR band and CMA3 fluorochrome staining, meaning that rDNA sequences are interspaced by GC-rich base pairs sequences. The C-banding also marked short arms of other chromosomes, indicating centric fissions followed by heterochromatin growth. The karyotype analysis of Azteca trigona allowed the identification of cytogenetic markers that will be helpful in a difficult taxonomic group as Azteca and discussion about evolutionary aspects of the genome organization.

  4. Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics.

    Science.gov (United States)

    Pringle, Elizabeth G; Ramírez, Santiago R; Bonebrake, Timothy C; Gordon, Deborah M; Dirzo, Rodolfo

    2012-07-01

    The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.

  5. Predation and aggressiveness in host plant protection: a generalization using ants from the genus Azteca

    Science.gov (United States)

    Dejean, Alain; Grangier, Julien; Leroy, Céline; Orivel, Jerôme

    2009-01-01

    In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers’ predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.

  6. Evolutionary history of the Azteca-like mariner transposons and their host ants

    Science.gov (United States)

    Palomeque, Teresa; Sanllorente, Olivia; Maside, Xulio; Vela, Jesús; Mora, Pablo; Torres, María I.; Periquet, Georges; Lorite, Pedro

    2015-08-01

    Three different complete mariner elements were found in the genome of the ant Tapinoma nigerrimum. One ( Tnigmar-Mr) was interrupted by a 900-bp insertion that corresponded to an incomplete member of a fourth mariner element, called Azteca. In this work, we isolate and characterize full-length Tnigmar-Az elements in T. nigerrimum. The purpose of this study is to clarify the evolutionary history of Azteca elements and their hosts as well as the possible existence of horizontal transfer processes. For this, Azteca-like elements were also retrieved from the available sequences of various ant genomes, representing four different ant subfamilies: Dolichoderinae, Formicinae, Myrmicinae, and Ponerinae. The tree topology resulting for the Azteca-like elements bore very little resemblance to that of their respective hosts. The pervasive presence of Azteca-like elements in all ant genomes, together with the observation that extant copies are usually younger than the genomes that host them, could be explained either by lineage sorting or by recent horizontal transfer of active elements. However, the finding of closer genetic relationships between elements than between the ants that host them is consistent with the latter scenario. This is clearly observed in Sinvmar-Az, Tnigmar-Az, Acepmar-Az, and Cflomar-Az elements, suggesting the existence of horizontal transfer processes. On the contrary, some elements displayed more divergence than did the hosts harboring them. This may reflect either further horizontal transfer events or random lineage sorting.

  7. Predation and aggressiveness in host plant protection: a generalization using ants from the genus Azteca.

    Science.gov (United States)

    Dejean, Alain; Grangier, Julien; Leroy, Céline; Orivel, Jerôme

    2009-01-01

    In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.

  8. Cuticular Hydrocarbon Cues Are Used for Host Acceptance by Pseudacteon spp. Phorid Flies that Attack Azteca sericeasur Ants.

    Science.gov (United States)

    Mathis, Kaitlyn A; Tsutsui, Neil D

    2016-04-01

    Parasitoids often use complex cues to identify suitable hosts in their environment. Phorid fly parasitoids that develop on one or a few host species often use multiple cues, ranging from general to highly specific, to home in on an appropriate host. Here, we describe the hierarchy of cues that Pseudacteon phorid flies use to identify Azteca ant hosts. We show, through behavioral observations in the field, that phorid flies are attracted to two cryptic Azteca species, but only attack Azteca sericeasur (Hymenoptera: Formicidae: Dolichoderinae). To test whether the phorid flies use cuticular hydrocarbons (CHCs) to distinguish between the two Azteca taxa, we first documented and compared cuticular hydrocarbons of the two Azteca taxa using gas chromatography/mass spectrometry. Then, using cuticular hydrocarbon-transfer experiments with live ants, we characterized the cuticular hydrocarbons of A. sericeasur as a short-range, host location cue used by P. lasciniosus (Diptera: Phoridae) to locate the ants.

  9. Las Armas de los Conquistadores. Las Armas de los Aztecas

    Directory of Open Access Journals (Sweden)

    Bruhn de Hoffmeyer, Ada

    1986-12-01

    Full Text Available ¿Qué clase de armas utilizaron los españoles en la conquista del Nuevo Mundo? No eran las mismas o idénticos tipos de armas en todas partes. Tampoco eran los mismos tipos y categorías que se utilizaban en aquella época en la Penínula Ibérica o en Europa occidental. Aunque los españoles llegaron al Nuevo Mundo con sus propias armas, fabricadas en España, en Italia, en Flandes, en Alemania —mejor dicho, en todo el mundo europeo del emperador Carlos V—, éstas no todas eran idóneas para los conquistadores de Méjico en el reino de los aztecas, o en Perú en el reino de los incas. Por varias razones. Las armas con que los conquistadores llegaron al Mundo Nuevo americano no eran completamente uniformes por razones económicas.

  10. Bayo Azteca, primera variedad mejorada de frijol con resistencia a Apion godmani Wagner Bayo Azteca, first improved bean variety with resistance to Apion godmani Wagner

    Directory of Open Access Journals (Sweden)

    Ramón Garza-García

    2010-12-01

    Full Text Available Bayo Azteca, la primera variedad mejorada de frijol (Phaseolus vulgaris L., con resistencia a una plaga insectil, ha sido obtenida por el programa de frijol del Campo Experimental Valle de México, del Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias por cruzas múltiples, esto involucró un largo proceso de mejora genética. Bayo Azteca es la primera variedad mejorada resistente al picudo del ejote (Apion godmani Wagner, un curculiónido que ataca al frijol en las zonas templadas de los valles altos de la Mesa Central de México, causando pérdidas que varían desde 50% hasta 90%. Al igual que otras variedades es también resistente a antracnosis [Colletotrichum lindemuthianum (Sacc & Magn. Briosi & Cav.] y tizón común [Xanthomonas campestris pv phaseoli (Smith Dye]. La nueva variedad fue desarrollada para los Valles Altos de la mesa central desde 1 800 a 2 300 m de altitud. Su hábito de crecimiento es indeterminado tipo III, guías cortas y flor blanca, las vainas son de tamaño mediano a grandes con 5 a 6 granos medianos, tiene alto potencial de rendimiento y plasticidad fenológica. En los Valles Altos, es de precocidad intermedia (102 a 118 días a madurez; Bayo Azteca es además de rápida cocción y con alto contenido de proteína.Bayo Azteca, the first improved bean variety (Phaseolus vulgaris L., with resistance to an insect plague, has been obtained via multiple crossing by bean program of the Valley of Mexico Experimental Station (CEVAMEX, of the National Research Forestry, Agriculture and Livestock Institute (INIFAP, which required a long process of genetic improvement. Bayo Azteca is the first improved variety resistant to bean pod weevil (Apion godmani Wagner, which is a curculionidae that attacks beans in template zones of the Central Highlands of Mexico and causes 50-90% losses. Similar to other varieties, the Bayo Azteca is resistant to anthracnose [Colletotrichum lindemuthianum (Sacc & Magn. Briosi

  11. The Effect of Symbiotic Ant Colonies on Plant Growth: A Test Using an Azteca-Cecropia System: e0120351

    National Research Council Canada - National Science Library

    Oliveira, Karla N; Coley, Phyllis D; Kursar, Thomas A; Kaminski, Lucas A; Moreira, Marcelo Z; Campos, Ricardo I

    2015-01-01

    .... In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry...

  12. First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae

    Directory of Open Access Journals (Sweden)

    Danon Cardoso

    2012-03-01

    Full Text Available In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae. Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3 and sequential base-specific fluorochromes. The analysis shows that A. trigona has a diploid number of 28 chromosomes. The karyotype consists of five metacentric pairs, seven acrocentric pairs and two pseudo-acrocentric pairs, which represents a karyotype formula 2K= 10M + 14A + 4AM and a diploid number of the arms 2AN = 38. The analysis of heterochromatin distribution revealed a positive block on distal region of the short arm of fourth metacentric pair, which was coincident with Ag-NOR band and CMA3 fluorochrome staining, meaning that rDNA sequences are interspaced by GC-rich base pairs sequences. The C-banding also marked short arms of other chromosomes, indicating centric fissions followed by heterochromatin growth. The karyotype analysis of A. trigona allowed the identification of cytogenetic markers that will be helpful in a difficult taxonomic group as Azteca and discussion about evolutionary aspects of the genome organization.

  13. AZTECA, a y-y diagram oriented interactive computer program for optical system design and optimization

    Science.gov (United States)

    Flores-Hernandez, Ricardo

    1995-09-01

    The Centro de Investigaciones en Optica is developing the AZTECA optical design program to exploit the full synthesis capabilities intrinsic to Delano's y-y method. Both the y- y diagram and its dual the (omega) -(omega) diagram, are manipulated in real time to introduce changes at any point or line in those diagrams. These changes result in altered new versions of the optical system by means of a specialized subroutine that incorporates the fundamental synthesis equations for those diagrams. To display results on the computer's screen as the optimization process progress, AZTECA makes wide use of the fact that the y-y and the (omega) -(omega) diagrams display graphically all the first order attributes of an optical system. This program adjoins to these features the calculation of Buchdahl's 3rd, 5th, and 7th order aberration coefficients to the output. This results in a real time display of the system's paraxial and aberrational behavior. Efficient graphic displays, the program's modular structure and an interactive mode of operation, also contribute to make the AZTECA a versatile platform. It will be further developed as a new tool for efficient optical system design.

  14. Toxicity of Trinitrotoluene to Sheepshead Minnows in Water Exposures

    Science.gov (United States)

    2010-02-06

    more toxic than TNT to an amphipod Hyalella azteca (2 times) and the cladoceran Ceriodaphia dubia (30 times) (Griest et al., 1998). Substantial...the aquatic amphipod Hyalella Azteca . Ecotoxicol. Environ. Saf. 70, 38–46. Smock, L.A., Stoneburner, D.L., Clark, J.R., 1976. The toxic effects of...tetranitro-1,3,5,7-tetrazocine in sediments to Chironomus tentans and Hyalella azteca : low-dose hormesis and high-dose mortality. Environ. Toxicol. Chem. 21

  15. Final Remedial Investigation/Baseline Risk Assessment for the Ravines and Beach Area Study of the Surplus Operable Unit, Fort Sheridan, Illinois. Volume 1: RI Text and RI Appendices A-I.

    Science.gov (United States)

    2007-11-02

    conducted on the invertebrates Hyalella azteca (H. azteca ) and Lumbriculus variegatus (L. variegatus). Groundwater acute toxicity tests were...control sediment tissue sample. Whole sediment chronic toxicity tests conducted with H. azteca in Janes Ravine sediment did not demonstrate any...Illinois the control sediment tissue sample. Whole sediment chronic toxicity tests conducted with H. azteca in Hutchinson Ravine sediment did not

  16. Pairing and reproductive success in two sympatric species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) from southern Brazil

    Science.gov (United States)

    da Silva Castiglioni, Daniela; Bond-Buckup, Georgina

    2008-01-01

    This study aimed at characterizing pairing and reproductive success in relation to male and female sizes of the sympatric freshwater gammarideans Hyalella pleoacuta and H. castroi from southern Brazil. These amphipods exhibit precopulatory mate guarding, in which a male will carry a potential mate beneath its ventral surface, guarding the female for several days until it molts and lays its eggs. The specimens were collected monthly with nets, from November 2003 to July 2004 in two trout aquaculture ponds at Sítio Vale das Trutas locality, São José dos Ausentes County, southern Brazil. The precopulatory pairs and ovigerous females were identified and separated in the field. In the laboratory, they were measured (cephalothorax length in mm), using a micrometer eyepiece in a stereoscopic microscope. Pairing success was estimated from the proportion of mating males and females related to their respective non-pairing individuals by size classes. Reproductive success was estimated from egg production. The mean cephalothorax length of paired males was larger than that of the unpaired males. For females, however, body size not affect pairing success for either species, because mean cephalothorax length of paired females did not differ significantly from unpaired females. Paired and unpaired males of both species of Hyalella were larger than the females. Positive assortative mating by size was observed in both species; i.e., larger males tended to pair with larger females. Male pairing success increased sharply with size. In both species, reproductive success in males increased with body size; however, the females of intermediate size classes showed greater reproductive success. This result supports the hypothesis that loading constraints play a part in structuring size-assortative pairing in these species.

  17. Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis.

    Science.gov (United States)

    Mathis, Kaitlyn A; Philpott, Stacy M; Moreira, Rayane F

    2011-05-01

    An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets.

  18. Toxicological Effects of Military Smokes and Obscurants on Aquatic Threatened and Endangered Species

    Science.gov (United States)

    2008-11-10

    Photooxidation products of smoke generator fuel (SGF) No. 2 fog oil and toxicity to Hyalella azteca . Env Toxicol & Chem 7:753-762. Quist MC, Fay PA...Brewer-Swarz S, and Thoeny WT (1997) A reformulated, reconstituted water for testing the freshwater amphipod, Hyalella azteca . Environ Toxicol & Chem 16

  19. Release of Metal Impurities from Carbon Nanomaterials Influences Aquatic Toxicity

    Science.gov (United States)

    2009-01-01

    in commerce. A 10 day sediment toxicity test for survival and growth of the freshwater amphipod, Hyalella azteca , exposed to sediments amended with a...reporting on the prepared leachate water quality (Table S1), solid phase soot contaminants (Table S2), Hyalella azteca toxicity data (Table S3

  20. Comparação metodológica de testes de toxicidade com Hyalella azteca (Crustacea, Amphipoda) e avaliação da qualidade do sedimento em reservatórios do rio Tietê (SP)

    OpenAIRE

    Ana Paula Cristiano do Nascimento

    2003-01-01

    O presente trabalho fez parte do Projeto QualiSed, uma cooperação entre UFSCar, Unicamp e Cetesb, o qual realizou um levantamento das bases técnico-científicas para a derivação de critérios de qualidade de sedimentos (CQS) para proteção da fauna aquática dos ecossistemas. Nos últimos anos tem havido um grande interesse no desenvolvimento, aperfeiçoamento e aplicação de metodologias para avaliar o grau de contaminação de sedimentos. Estes, apesar de fornecerem habitat para muitos organismos aq...

  1. Nest structure and occurrence of three species of Azteca (Hymenoptera, Formicidae in Cecropia pachystachya (Urticaceae in non-floodable and floodable pantanal areas Arquitetura de ninho e ocorrência de três espécies de Azteca (Hymenoptera, Formicidae em Cecropia pachystachya (Urticaceae em ambiente alagável e não alagável no Pantanal

    Directory of Open Access Journals (Sweden)

    Alexsandro S. Vieira

    2010-01-01

    Full Text Available Thirty Cecropia pachystachya trees were examined in non-floodable and floodable areas to investigate the association between C. pachystachya and Azteca ants in the Pantanal of Mato Grosso do Sul, Brazil. The species Azteca ovaticeps, Azteca isthmica, and Azteca alfari were found nesting inside domatia of C. pachystachya. A. ovaticeps was the most frequent species in the trees in the floodable area, while A. isthmica and A. alfari, in the non-floodable area. A. ovaticeps and A. isthmica maintained more entrance/exit holes in comparison to A. alfari. All Azteca species maintained entrance/exit holes in the closest domatia to the apical area of the branch, due to proximity to Müllerian and pearl bodies, suggesting that these species of Azteca were influenced by their environment during evolution and became specialized. All internodal septa of each examined branch were perforated by ants, indicating the branches were inhabited by a single colony.Foram analisadas 30 plantas de Cecropia pachystachya em cada ambiente alagável e não alagável no Pantanal sul-mato-grossense, Brasil, com o objetivo de investigar a associação entre formigas Azteca e C. pachystachya. Foram encontradas as espécies Azteca ovaticeps, Azteca isthmica e Azteca alfari nidificando nas domáceas da planta. A. ovaticeps foi mais frequente em plantas de área alagável, enquanto A. isthmica e A. alfari em plantas em área não alagável. A. ovaticeps e A. isthmica apresentaram maior quantidade de orifícios de entrada/saída em relação à A. alfari e todas as espécies mantêm próximo da região apical do ramo, orifícios de entrada/saída nas domáceas, devido à proximidade com os corpúsculos müellerianos e pérola. Isto é, essas espécies de Azteca especializaram-se ao longo da evolução influenciadas pelo ambientes. Todos os septos internodais de cada ramo analisados apresentaram-se perfurados pelas formigas, sugerindo que os mesmos são habitados por uma única colônia.

  2. Revisión de la distribución de Hyalella Smith, 1874 (Crustacea, Amphipoda en la Patagonia e islas adyacentes Revision of the distribution of Hyalella Smith, 1874 (Crustacea, Amphipoda in Patagonia and adjacent islands

    Directory of Open Access Journals (Sweden)

    Patricio De los Ríos-Escalante

    2012-07-01

    Full Text Available Se realiza una revisión de las especies de anfípodos del género Hyalella en aguas continentales de la Patagonia, isla Tierra del Fuego, Reserva de la Biosfera de Cabo de Hornos e islas adyacentes (38-54°S. Esta zona austral presenta numerosos tipos de ambientes acuáticos continentales como lagos, humedales y arroyos, y las principales especies en ambientes bentónicos corresponden a anfípodos del género Hyalella. La bibliografía menciona la presencia de H. costera, H. chiloensis, H. falklandensis, H. franciscae, H. neonoma, H. patagónica, H. rionegrina y H. simplex. La distribución de estas especies concuerda con estudios biogeográficos sobre la presencia de especies endémicas y de amplia distribución en el sur de la Patagonia y zona subantárticas. A pesar de la presencia de especies depredadoras introducidas, sobre la base de la literatura, los anfípodos serían más abundantes debido a la presencia de materia orgánica particulada.This study reviews the amphipod species of the genus Hyalella in the inland waters of Patagonia, Tierra del Fuego Island, Cape Horn Biosphere Reserve, and adjacent islands (38-54°S. This southern zone has numerous kinds of continental water bodies such as lakes, wetlands, and streams, and the main species in benthic assemblages are amphipods of the genus Hyalella. The literature mentions the presence of H. costera, H. chiloensis, H. falklaidensis, H. franciscae, H. neonoma, H. patagonica, H. rionegrina, and H. simplex. The distribution of these species agrees with biogeographical studies about the presence of widespread, endemic species in southern Patagonia and the sub-Antarctic zone. In spite of the presence of introduced predatory species, the literature indicates that the amphipods are more abundant due to the presence of particulated organic matter.

  3. Simulation Modeling of Zooplankton and Benthos in Reservoirs: Documentation and Development of Model Constructs.

    Science.gov (United States)

    1980-03-01

    des conditions ecologiques. Cahiers de Biologie Marine, 17: 37-43. BOVEE, E. C. 1949. Studies on the thermal death rate of Hyallela azteca , Saussure...1965. Dynamics and production of a natural population of fresh-water amphipod, Hyalella azteca . Ecological Monographs, 35: 377-394. CORNER, E. D. S...B. T. 1970. The utilization of benthic microflora by Hyalella azteca (Amphipoda). Journal of Animal Ecology, 39: 427-437. HARGRAVE, B. T. 1971. An

  4. Rational Selection of Tailored Amendment Mixtures and Composites for In Situ Remediation of Contaminated Sediments

    Science.gov (United States)

    2008-12-01

    toxicity observed for Thiol-SAMMS was moderate at a dose of 5% by dry weight with a reduction in H. Azteca survival from 98% to 73%. Although Thiol...arenaceodentata, Chironomus dilutus, Hyalella Azteca and Leptocheirus plumulosus. Tests were conducted as described in existing chronic sediment toxicity test...illustrates the survival of three benthic organisms (Chironomus dilutus (a), Hyalella Azteca (b) and Leptocheirus plumulosus(c) in the amendment treated

  5. Plant defense, herbivory, and the growth of Cordia alliodora trees and their symbiotic Azteca ant colonies.

    Science.gov (United States)

    Pringle, Elizabeth G; Dirzo, Rodolfo; Gordon, Deborah M

    2012-11-01

    The effects of herbivory on plant fitness are integrated over a plant's lifetime, mediated by ontogenetic changes in plant defense, tolerance, and herbivore pressure. In symbiotic ant-plant mutualisms, plants provide nesting space and food for ants, and ants defend plants against herbivores. The benefit to the plant of sustaining the growth of symbiotic ant colonies depends on whether defense by the growing ant colony outpaces the plant's growth in defendable area and associated herbivore pressure. These relationships were investigated in the symbiotic mutualism between Cordia alliodora trees and Azteca pittieri ants in a Mexican tropical dry forest. As ant colonies grew, worker production remained constant relative to ant-colony size. As trees grew, leaf production increased relative to tree size. Moreover, larger trees hosted lower densities of ants, suggesting that ant-colony growth did not keep pace with tree growth. On leaves with ants experimentally excluded, herbivory per unit leaf area increased exponentially with tree size, indicating that larger trees experienced higher herbivore pressure per leaf area than smaller trees. Even with ant defense, herbivory increased with tree size. Therefore, although larger trees had larger ant colonies, ant density was lower in larger trees, and the ant colonies did not provide sufficient defense to compensate for the higher herbivore pressure in larger trees. These results suggest that in this system the tree can decrease herbivory by promoting ant-colony growth, i.e., sustaining space and food investment in ants, as long as the tree continues to grow.

  6. Mycelial carton galleries of Azteca brevis (Formicidae) as a multi-species network

    Science.gov (United States)

    Mayer, Veronika E.; Voglmayr, Hermann

    2009-01-01

    Apart from growing fungi for nutrition, as seen in the New World Attini, ants cultivate fungi for reinforcement of the walls of their nests or tunnel-shaped runway galleries. These fungi are grown on organic material such as bark, epiphylls or trichomes, and form stable ‘carton structures’. In this study, the carton of the runway galleries built by Azteca brevis (Formicidae, Dolichoderinae) on branches of Tetrathylacium macrophyllum (Flacourtiaceae) is investigated. For the first time, molecular tools are used to address the biodiversity and phylogenetic affinities of fungi involved in tropical ant carton architecture, a previously neglected ant–fungus mutualism. The A. brevis carton involves a complex association of several fungi. All the isolated fungi were unequivocally placed within the Chaetothyriales by DNA sequence data. Whereas five types of fungal hyphae were morphologically distinguishable, our DNA data showed that more species are involved, applying a phylogenetic species concept based on DNA phylogenies and hyphal morphology. In contrast to the New World Attini with their many-to-one (different ant species—one fungal cultivar) pattern, and temperate Lasius with a one-to-two (one ant species—two mutualists) or many-to-one (different ant species share the same mutualist) system, the A. brevis–fungi association is a one-to-many multi-species network. Vertical fungus transmission has not yet been found, indicating that the A. brevis–fungi interaction is rather generalized. PMID:19556257

  7. The Azteca Chess experience: learning how to share concepts of ecological complexity with small coffee farmers

    Directory of Open Access Journals (Sweden)

    Luís García-Barrios

    2017-06-01

    Full Text Available Small-scale coffee farmers understand certain complex ecological processes, and successfully navigate some of the challenges emerging from the ecological complexity on their farms. It is generally thought that scientific knowledge is able to complement farmers' knowledge. However, for this collaboration to be fruitful, the gap between the knowledge frameworks of both farmers and scientists will need to be closed. We report on the learning results of 14 workshops held in Chiapas, Mexico during 2015 in which 117 small-scale coffee farmers of all genders (30% women and ages who had little schooling were exposed by researchers to a natural history narrative, a multispecies network representation, a board game, and a series of graphical quizzes, all related to a nine-species complex ecological network with potential for autonomous control of the ongoing and devastating coffee rust epidemic that was affecting them. Farmers' retention and understanding of direct and indirect bilateral interactions among organisms was assessed with different methods to elucidate the effect of adding Azteca Chess gaming sessions to a detailed and very graphical lecture. Evaluation methods that were better adapted to farmers' conditions improved learning scores and showed statistically significant age effect (players older than 40 had lower retention scores and gaming effect (lower retention of interactions included in the lecture but not in the game. The combination of lecture and game sessions helped participants better understand cascades of trait-mediated interactions. Participants' debriefings confirmed qualitatively that they learned that beneficial organisms and interactions occur on their farms, and that gaming was enjoyable, motivating, and critical to grasp complex interactions. Many of the farmers concluded that the outcome of these interactions is not unique and not always in favor of rust control but is context dependent. Many concluded that there are

  8. The effect of symbiotic ant colonies on plant growth: a test using an Azteca-Cecropia system.

    Science.gov (United States)

    Oliveira, Karla N; Coley, Phyllis D; Kursar, Thomas A; Kaminski, Lucas A; Moreira, Marcelo Z; Campos, Ricardo I

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ(15)N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ(15)N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change.

  9. The effect of symbiotic ant colonies on plant growth: a test using an Azteca-Cecropia system.

    Directory of Open Access Journals (Sweden)

    Karla N Oliveira

    Full Text Available In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry. We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ(15N, and investments in defense (total phenolics and leaf mass per area. We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ(15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change.

  10. The Effect of Symbiotic Ant Colonies on Plant Growth: A Test Using an Azteca-Cecropia System

    Science.gov (United States)

    Oliveira, Karla N.; Coley, Phyllis D.; Kursar, Thomas A.; Kaminski, Lucas A.; Moreira, Marcelo Z.; Campos, Ricardo I.

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ15N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change. PMID:25811369

  11. Does exogenic food benefit both partners in an ant-plant mutualism? The case of Cecropia obtusa and its guest Azteca plant-ants.

    Science.gov (United States)

    Dejean, Alain; Petitclerc, Frédéric; Roux, Olivier; Orivel, Jérôme; Leroy, Céline

    2012-03-01

    In the mutualisms involving the myrmecophyte Cecropia obtusa and Azteca ovaticeps or A. alfari, both predatory, the ants defend their host trees from enemies and provide them with nutrients (myrmecotrophy). A. ovaticeps provisioned with prey and then (15)N-enriched food produced more individuals than did control colonies (not artificially provisioned). This was not true for A. alfari colonies, possibly due to differences in the degree of maturity of the colonies for the chosen range of host tree sizes (less than 3m in height). Myrmecotrophy was demonstrated for both Azteca species as provisioning the ants with (15)N-enriched food translated into higher δ(15)N values in host plant tissues, indicating that nitrogen passed from the food to the plant. Thus, the predatory activity of their guest ants benefits the Cecropia trees not only because the ants protect them from defoliators since most prey are phytophagous insects but also because the plant absorbs nutrients.

  12. First report of two species of scarab beetles (Coleoptera, Scarabaeidae inside nests of Azteca cf. chartifex Forel (Hymenoptera, Formicidae in Brazilian Amazonian Rainforest

    Directory of Open Access Journals (Sweden)

    João Rafael Alves-Oliveira

    Full Text Available ABSTRACT We report for the first time the occurrence of two species of scarab beetles, Phileurus carinatus declivis Prell, 1914 (Scarabaeidae: Dynastinae and Cyclidius elongatus (Olivier, 1789 (Cetoniinae: Cremastocheilini inside nests of Azteca cf. chartifex Forel, 1896, a neotropical arboreal ant species. This report indicates that these two beetle species are associated, at least as inquilines, to this ant species, although the nature of this relationship remains unclear.

  13. Sex-specific nutrient use and preferential allocation of resources to a sexually selected trait in Hyalella amphipods.

    Science.gov (United States)

    Goos, Jared M; Cothran, Rickey D; Jeyasingh, Punidan D

    2016-03-01

    Although sexually dimorphic traits are often well studied, we know little about sex-specific resource use strategies that should underlie such dimorphism. We measured sex-specific responses in acquisition and assimilation of two fundamental resources, carbon (C) and phosphorus (P) in juvenile and mature Hyalella amphipods given low and high supplies of inorganic phosphate, analogous to oligotrophic and eutrophic conditions, respectively. Additionally, we quantified allocation of resources to sexual traits in males. Dual radiotracer ((14)C and (33)P) assays revealed substantial age- and sex-specific differences in acquisition and assimilation. Furthermore, a phenotypic manipulation experiment revealed that amphipods fed low-P food allocated more C to all traits than those fed high-P food. Importantly, we found that amphipods preferentially allocated more C to the development of a sexually selected trait (the posterior gnathopod), compared with a serially homologous trait (the fifth pereopod) not under sexual selection. Substantial differences in how the sexes use fundamental resources, and the impact of altered nutrient supply on such differences, illuminate sexual dimorphism at the lowest level of biological organization. Such information will be important in understanding how sex- and age-specific life history demands influence nutrient processing in a biosphere characterized by rapidly changing alterations to biogeochemical cycles.

  14. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates

    NARCIS (Netherlands)

    Sidney, L.A.; Diepens, N.J.; Guo, X.; Koelmans, A.A.

    2016-01-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We us

  15. CHRONIC EFFECTS OF THE HERBICIDE DIURON ON FRESHWATER CLADOCERANS,AMPHIPODS,MIDGES,MINNOWS,WORMS, AND SNAILS

    Science.gov (United States)

    The chronic effects of the herbicide diuron on survival and reproduction of Daphnia pulex, and survival and growth of the amphipod Hyalella azteca, the midge Chironomus tentans, juvenile and embro/larval fathead minnows, Pimephales promelas, annelid worms, Lumbriculus variegatus,...

  16. Trait-based modelling of bioaccumulation by freshwater benthic invertebrates

    NARCIS (Netherlands)

    Sidney, L.A.; Diepens, N.J.; Guo, X.; Koelmans, A.A.

    2016-01-01

    Understanding the role of species traits in chemical exposure is crucial for bioaccumulation and toxicity assessment of chemicals. We measured and modelled bioaccumulation of polychlorinated biphenyls (PCBs) in Chironomus riparius, Hyalella azteca, Lumbriculus variegatus and Sphaerium corneum. We

  17. Toxicity of major geochemical ions to freshwater species

    Science.gov (United States)

    Extensive testing regarding the toxicity of major geochemical ions to Ceriodaphnia dubia, Hyalella azteca, and Pimephales promelas will be presented. For C. dubia, tests of single salts and binary mixtures in various dilution waters demonstrated multiple mechanisms of toxicity an...

  18. Disentangling endogenous versus exogenous pattern formation in spatial ecology: a case study of the ant Azteca sericeasur in southern Mexico.

    Science.gov (United States)

    Li, Kevin; Vandermeer, John H; Perfecto, Ivette

    2016-05-01

    Spatial patterns in ecology can be described as reflective of environmental heterogeneity (exogenous), or emergent from dynamic relationships between interacting species (endogenous), but few empirical studies focus on the combination. The spatial distribution of the nests of Azteca sericeasur, a keystone tropical arboreal ant, is thought to form endogenous spatial patterns among the shade trees of a coffee plantation through self-regulating interactions with controlling agents (i.e. natural enemies). Using inhomogeneous point process models, we found evidence for both types of processes in the spatial distribution of A. sericeasur. Each year's nest distribution was determined mainly by a density-dependent relationship with the previous year's lagged nest density; but using a novel application of a Thomas cluster process to account for the effects of nest clustering, we found that nest distribution also correlated significantly with tree density in the later years of the study. This coincided with the initiation of agricultural intensification and tree felling on the coffee farm. The emergence of this significant exogenous effect, along with the changing character of the density-dependent effect of lagged nest density, provides clues to the mechanism behind a unique phenomenon observed in the plot, that of an increase in nest population despite resource limitation in nest sites. Our results have implications in coffee agroecological management, as this system provides important biocontrol ecosystem services. Further research is needed, however, to understand the effective scales at which these relationships occur.

  19. Financial effects of the corporative government and ethics in Mexico’s businesses: the case of Cemex and TV-Azteca

    OpenAIRE

    Pablo Lopez Sarabia

    2007-01-01

    Este artículo muestra que las malas prácticas de gobierno corporativo y falta de ética puede afectar el desempeño inanciero de las empresas y muy en particular su valor de mercado. Se analiza a TV-Azteca que enfrenta una demanda de fraude por una recompra de deuda violando la regulación del mercado bursátil de Estados Unidos de América en especial la Ley Sarbanes-Oxley, los resultados econométricos muestran que el valor de la empresa y el precio han disminuido a partir del inicio de investiga...

  20. In Situ Estuarine and Marine Toxicity Testing: A Review, Including Recommendations for Future Use in Ecological Risk Assessment

    Science.gov (United States)

    2009-09-01

    39 Lavoie et al. (2001) used the freshwater amphipod Hyallela azteca , as well as the cladoceran Daphnia magna, in caged exposures as part of an...54 pp., June 2003. Chappie DJ and Burton GA, Jr., 1997. Optimization of in situ bioassays with Hyalella azteca and Chironomus tentans. Environ

  1. Environmental and habitat drivers of relative abundance for a suite of azteca-attacking Pseudacteon phorid flies.

    Science.gov (United States)

    Reese, Katlynd M; Philpott, Stacy M

    2012-10-01

    Phoridae (Diptera) have widespread impacts on insect communities by limiting host ant behavior. However, phorid-ant interactions may vary with habitat or environmental conditions. Three Pseudacteon species parasitize Azteca instabilis Fr. Smith, a common ant in coffee agroecosystems, and limit A. instabilis foraging, indirectly benefiting other insects. However, little is known about how phorid abundance, behavior, and effects change with environmental conditions. In shaded coffee systems, coffee (Coffea arabica L.) grows under a range of shade conditions and management changes affect species interactions. For example, Pseudacteon spp. more strongly limit A. instabilis foraging in low-shade coffee habitats. We sampled relative abundance of three phorid species around A. instabilis nests in three coffee habitats varying in shade management during dry and wet seasons. We measured canopy cover, tree richness, tree density, leaf litter depth, and number of nearby trees with A. instabilis to determine whether these habitat factors correlate with phorid abundance. P. laciniosus Brown was the most abundant phorid in both seasons. Phorid relative abundance did not differ by habitat, but did differ by season. P. laciniosus accounted for a higher proportion of phorids in the wet season (91.4%) than in the dry season (78.9%), and P. planidorsalis Brown accounted for a larger percent in the dry season (21.1%) than in the wet season (7.3%). Phorid composition did not differ with habitat type, and none of the measured environmental variables correlated with changes in phorid composition. Thus, phorids in coffee agroecosystems respond to large seasonal differences, but not differences between coffee habitats.

  2. Hypothenemus hampei (Coleoptera: Curculionidae) and its interactions with Azteca instabilis and Pheidole synanthropica (Hymenoptera: Formicidae) in a shade coffee agroecosystem.

    Science.gov (United States)

    Jiménez-Soto, Estelí; Cruz-Rodríguez, Juan A; Vandermeer, John; Perfecto, Ivette

    2013-10-01

    The coffee berry borer is currently the most important insect pest of coffee worldwide. In shaded coffee farms such as Finca Irlanda in Chiapas, Mexico, natural enemies limit coffee berry borer and potentially prevent outbreaks. This research aimed to determine the effect of ants on coffee berry borer damage and to describe behaviors of Azteca instabilis F. Smith and Pheidole synanthropica (Longino 2009) when encountering the coffee berry borer. To these ends, an ant survey was conducted in a 2,500-m(2) plot within the farm. A 4- by 4-m coordinate system was established, and the coffee plant or shade tree closest to the coordinate point was sampled using tuna fish for a total of 168 coffee plants and 46 shade trees sampled. In addition, up to 100 berries were harvested from 138 coffee plants to measure damage and verify the presence of the coffee berry borer. Behavior was determined in the field by placing live coffee berry borer adults on berries and video recording all attacks. Results showed that plants with ants had less percentage of damaged berries and shorter coffee berry borer galleries than plants without ants. However, the length of galleries in plants with A. instabilis showed no significant differences from plants without ants. P. synanthropica was observed carrying coffee berry borer to the nest in 50% of the cases, whereas A. instabilis threw coffee berry borer off of the coffee plant in 79% of the cases. Results indicate that the presence of these species of ants reduce coffee berry borer damage and suggest that different behaviors could explain the pattern of coffee berry borer attack in this agroecosystem.

  3. Demonstration and Certification of Amphibian Ecological Risk Assessment Protocol. Cost and Performance Report (Version 2)

    Science.gov (United States)

    2009-07-01

    day benthic invertebrate toxicity tests conducted with the midge, Chironomus tentans, and the amphipod, Hyalella azteca . Actual unit costs for these...management decisions in wetlands often rely on site-specific benthic invertebrate toxicity testing using organisms such as the amphipod, H. azteca ...amphipod (H. azteca ), and the fathead minnow (Pimephales promelas). Although remediation has not yet occurred, the arsenic NOAEC from the amphibian

  4. Indirect interactions between ant-tended hemipterans, a dominant ant Azteca instabilis (Hymenoptera: Formicidae), and shade trees in a tropical agroecosystem.

    Science.gov (United States)

    Livingston, George F; White, Adam M; Kratz, Carley J

    2008-06-01

    The occurrence, intensity, and composition of mutualisms are dependent not only on the co-occurrence of mutualists, but also the broader biotic context in which they are embedded. Here, the influence of the specific nest tree identity of the ant Azteca instabilis (F. Smith) on the density of the green coffee scale (Coccus viridis Green) was studied in a coffee agroecosystem in southern Mexico. The hypothesis that an indirect competitive interaction for ant attendance occurs between a scale species (Octolecanium sp. Kondo) in the canopy of the shade tree Inga micheliana Harms and C. viridis, which inhabits coffee bushes (Coffea arabica) beneath the shade trees was tested. Coffee bushes beneath a different shade tree species (Alchornea latifolia Swartz) were used as an indication of C. viridis density in a noncompetitive environment. Results indicate that C. viridis occurs in significantly lower density adjacent to nests in Inga, supporting the hypothesis of indirect competition. Additional experimentation suggests that there is a mutualism between Azteca and Octolecanium and that this interaction may be mediated by a hierarchy in ant attendance of scale insects. Our results show the importance of considering the biotic context of ant-hemipteran mutualisms. In coffee agroecosystems, consideration of shade tree diversity and species composition may be directly applicable to the biological control of insect pests.

  5. Spatial patterns of Pisidium chilense (Mollusca Bivalvia and Hyalella patagonica (Crustacea, Amphipoda in an unpolluted stream in Navarino island (54° S, Cape Horn Biosphere Reserve

    Directory of Open Access Journals (Sweden)

    Patricio De Los Ríos Escalante

    2017-01-01

    Full Text Available The southern South American inland waters have many endemic species and some of them are considered as endangered for IUCN, that inhabits in unpolluted ecosystems, one of these ecosystems are the sub-Antarctic perennial forests located in the Cape Horn Biosphere Reserve at 54° S. The aim of the present study is to analyze the spatial patterns of Pisidium chilense Ituarte, 1999 (Mollusca Bivalvia and Hyalella patagonica (Cunningham, 1871 (Crustacea, Amphipoda in an unpolluted stream. Both species had aggregated spatial distribution, both have a negative binomial distribution pattern, and both are associated. The present results would agree with similar patterns in Patagonian rivers where both species coexist.

  6. Interação planta-inseto: Aspectos biológicos e ecológicos do mutualismo Cecropia-Azteca

    Directory of Open Access Journals (Sweden)

    2015-08-01

    Abstract. A well-known association is the mutualism between plants is between plant species of the genus Cecropia and ants, mostly belonging to the genus Azteca. In this association, the ants nest in domatia present in the hollow trunk of this myrmecophytes and feed on food bodies provided by the plant, known as mullerian bodies. In return, the ants protect the host plant against herbivore attacks and invasion by vines, and nourish it through waste laid in the trunk. However, the effectiveness of this association may vary with several factors, such as the associated ant species and the habitat type of the myrmecophyte. About 10% of Cecropia species lost their attractive characteristics, such as species living in high altitude and inhabit islands. Aspects like associated ant richness and molecular studies show that the colonization of these plants by ants occurred several times and independently by different genera. The selection pressure exerted by some species of ants may have been one of the decisive factors for the development of attractive traits for ants in Cecropia. With the evolution of these features ants might become an effective partner of the plant, facilitating the co-evolution of specific interactions.

  7. Efectos financieros del gobierno corporativo y ética en los negocios en México: el caso de Cemex y TV-Azteca

    Directory of Open Access Journals (Sweden)

    Pablo Lopez Sarabia

    2007-12-01

    Full Text Available Este artículo muestra que las malas prácticas de gobierno corporativo y falta de ética puede afectar el desempeño inanciero de las empresas y muy en particular su valor de mercado. Se analiza a TV-Azteca que enfrenta una demanda de fraude por una recompra de deuda violando la regulación del mercado bursátil de Estados Unidos de América en especial la Ley Sarbanes-Oxley, los resultados econométricos muestran que el valor de la empresa y el precio han disminuido a partir del inicio de investigación de la Securities and Exchange Commission (SEC. Por lo que se reiere a Cementos Mexicanos (Cemex es una empresa que ha desarrollado un código de ética interno y ajustado al Código de Mejores Prácticas Corporativas, así como un impulsor entusiasta de las buenas prácticas de gobierno corporativo.

  8. La participación de Televisa y TV Azteca en la construcción, promoción de imagen y percepción ciudadana, de candidatos y gobernantes mexicanos con financiamiento público

    OpenAIRE

    Orta Vélez, Juan Miguel

    2010-01-01

    En México, gobernantes y candidatos, han aplicado innovadoras formas de promover su imagen, la principal herramienta la constituye el duopolio: Televisa y TV Azteca. Inicialmente las campañas políticas en televisión, consistían en la compra de spots y cobertura en noticieros, es a partir del año 2000, cuando políticos y gobiernos en contubernio con las televisoras, irrumpen esta práctica mediante programas de entretenimiento, deportes, espectáculos, incluso comedia, tomando por sorpresa al te...

  9. La participación de Televisa y TV Azteca en la construcción, promoción de imagen y percepción ciudadana, de candidatos y gobernantes mexicanos con financiamiento público

    OpenAIRE

    Orta Vélez, Juan Miguel

    2010-01-01

    En México, gobernantes y candidatos, han aplicado innovadoras formas de promover su imagen, la principal herramienta la constituye el duopolio: Televisa y TV Azteca. Inicialmente las campañas políticas en televisión, consistían en la compra de spots y cobertura en noticieros, es a partir del año 2000, cuando políticos y gobiernos en contubernio con las televisoras, irrumpen esta práctica mediante programas de entretenimiento, deportes, espectáculos, incluso comedia, tomando por sorpresa al te...

  10. The Toxicity of Nitroguanidine and Photolyzed Nitroguandine to Freshwater Aquatic Organisms

    Science.gov (United States)

    1985-03-01

    teema R0.t) - 33ICY WORDfl1’CAtttewe amee~A ejolft~l ofc.. "**eef andatIA"b 5 Welt ftwaeo)•ute tox city • mannel cattish1,H allela azteca • ’Midge...of well water for transfer to the test chambers. One amphipod used ii testing was _Hyalella azteca , which was collected from Hunt’s Pvnd nedr Norwich...NY. H. azteca was keyed to species using Pennak. 12 The other amphipod tested was Gammarus minus, which was obtained from a spring in the Frederick M

  11. La psicología mesoamericana: ideas psicológicas, psicopatológicas y psicoterapéuticas en las culturas maya, purépecha y azteca

    OpenAIRE

    Pavón-Cuéllar, David

    2013-01-01

    El presente artículo ofrece una visión panorámica de las ideas psicológicas en las culturas mesoamericanas, particularmente en la época prehispánica, pero también en siglos posteriores. Se presta especial atención a las psicologías maya, purépecha y azteca. La psicología maya despliega sus clasificaciones psicopatológicas, sus técnicas terapéuticas y sus representaciones de la vinculación entre el alma y el cuerpo. Esta vinculación es profundizada en una psicología purépecha esencialmente soc...

  12. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

    Science.gov (United States)

    This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

  13. Toxicity evaluation of a conservation effects assessment program watershed, Beasley Lake, in the Mississippi Delta, USA

    Science.gov (United States)

    Beasley Lake was assessed monthly in 2005 for biological impairment from 17 historic and current-use pesticides in water and leaf litter using Hyalella azteca (Saussure). Sixteen pesticides were detected in both water and leaf litter with peak detections in spring and summer. Detections ranged fro...

  14. Phototoxicity of TiO{sub 2} nanoparticles to a freshwater benthic amphipod: Are benthic systems at risk?

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shibin, E-mail: li.shibin@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Wallis, Lindsay K.; Ma, Hongbo [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Diamond, Stephen A. [Nanosafe Inc., Blacksburg, VA (United States)

    2014-01-01

    This study investigated phototoxicity of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (> 77%) in LSW was observed after 0.5 h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m{sup 2}. Phototoxicity of nano-TiO{sub 2} under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5–23.3) Wh/m{sup 2} when exposed to 20 mg/L nano-TiO{sub 2}. Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO{sub 2} to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. - Graphical abstract: Display Omitted - Highlights: •Large aggregation of TiO{sub 2} nanoparticles in Lake Superior water was observed. •Phototoxicity was dependent on the dose of both solar radiation and nanoparticle. •A solar radiation favored surface attachment of nanoparticles was observed. •Hyalella azteca exhibited negative phototaxis in the presence of shelters. •Factors influencing

  15. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  16. Toxicity of fluoride to aquatic species and evaluation of toxicity modifying factors.

    Science.gov (United States)

    Pearcy, Krysta; Elphick, James; Burnett-Seidel, Charlene

    2015-07-01

    The present study was performed to investigate the toxicity of fluoride to a variety of freshwater aquatic organisms and to establish whether water quality variables contribute substantively to modifying its toxicity. Water hardness, chloride, and alkalinity were tested as possible toxicity modifying factors for fluoride using acute toxicity tests with Hyalella azteca and Oncorhynchus mykiss. Chloride appeared to be the major toxicity modifying factor for fluoride in these acute toxicity tests. The chronic toxicity of fluoride was evaluated with a variety of species, including 3 fish (Pimephales promelas, O. mykiss, and Salvelinus namaycush), 3 invertebrates (Ceriodaphnia dubia, H. azteca, and Chironomus dilutus), 1 plant (Lemna minor), and 1 alga (Pseudokirchneriella subcapitata). Hyalella azteca was the most sensitive species overall, and O. mykiss was the most sensitive species of fish. The role of chloride as a toxicity modifying factor was inconsistent between species in the chronic toxicity tests.

  17. Nidificação de Polybia rejecta (Fabricius (Hymenoptera: Vespidae Associada à Azteca chartifex Forel (Hymenoptera: Formicidae em Ecótono de Bioma Caatinga/Mata Atlântica, no Estado do Rio Grande do Norte

    Directory of Open Access Journals (Sweden)

    Francisco Virgínio

    2015-12-01

    Abstract. Some neotropical social wasps which are associated with some vertebrates and other insects like ants, and these interactions are reported for decades, but little is known about the presence of these in the Caatinga and Atlantic Forest. This study describes the first association's record between nests of Polybia rejecta (Fabricius wasp and Azteca chartifex Forel ants in the transition area of the Atlantic Forest and Caatinga in Rio Grande do Norte. The observations were in a private forest in Monte Alegre, from October 2009 to September 2014 through active search for colonies, use of ad libitum method, photography and collection of specimens with traceability. In the study area were found four active colonies and one abandoned of P. rejecta, all associated with nests of A. chartifex with approach of 20-30 cm. It was found that when the colony of P. rejecta was disturbed, they became aggressive towards the disturbance object, whereas the ants gathered in order to fend off a potential predators. These interactions appear to benefit wasps and ants, it is assumed that is possible that wasps attack ants's predators, whereas the ants attack the wasps's predators. This study corroborates the hypothesis that the association between the social wasps P. rejecta and A. chartifex ants is beneficial for both species, and probably the wasps are the most benefited, but also shows the non-exclusivity of this association for the biomes up then reported.

  18. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    In the fields of power conversion devices and broadcasting/communication amplifiers, high power, high frequency and low losses are desirable. Further, for electronic elements in aerospace/aeronautical/geothermal surveys, etc., heat resistance to 500degC is required. Devices which respond to such hard specifications are called hard electronic devices. However, with Si which is at the core of the present electronics, the specifications cannot fully be fulfilled because of the restrictions arising from physical values. Accordingly, taking up new device materials/structures necessary to construct hard electronics, technologies to develop these to a level of IC were examined and studied. They are a technology to make devices/IC of new semiconductors such as SiC, diamond, etc. which can handle higher temperature, higher power and higher frequency than Si and also is possible of reducing losses, a technology to make devices of hard semiconducter materials such as a vacuum microelectronics technology using ultra-micro/high-luminance electronic emitter using negative electron affinity which diamond, etc. have, a technology to make devices of oxides which have various electric properties, etc. 321 refs., 194 figs., 8 tabs.

  19. Electronic Cigarettes

    Science.gov (United States)

    ... New FDA Regulations Text Size: A A A Electronic Cigarettes Electronic cigarettes (e-cigarettes) are battery operated products designed ... more about: The latest news and events about electronic cigarettes on this FDA page Electronic cigarette basics ...

  20. The Electron

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, George

    1972-01-01

    Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

  1. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  2. Ambient Electronics

    Science.gov (United States)

    Sekitani, Tsuyoshi; Someya, Takao

    2012-10-01

    We report the recent research progress and future prospects of flexible and printed electronics, focusing on molecular electronic material-based thin-film transistors, which are expected to usher in a new era of electronics.

  3. Electron cooling

    Science.gov (United States)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  4. Electron Microscopy.

    Science.gov (United States)

    Beer, Michael

    1980-01-01

    Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

  5. Electron Microscopy.

    Science.gov (United States)

    Beer, Michael

    1980-01-01

    Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

  6. Understand electronics

    CERN Document Server

    Bishop, Owen

    2013-01-01

    Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

  7. Electronic components

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful

  8. Electronic Prescribing

    Science.gov (United States)

    ... Do you prescribe electronically?” For more information about electronic prescribing, call 1-800-MEDICARE (1-800-633- ... TTY users should call 1-877-486-2048 . Electronic eRx Prescribing I went to the pharmacy, and ...

  9. Basic electronics

    CERN Document Server

    Holbrook, Harold D

    1971-01-01

    Basic Electronics is an elementary text designed for basic instruction in electricity and electronics. It gives emphasis on electronic emission and the vacuum tube and shows transistor circuits in parallel with electron tube circuits. This book also demonstrates how the transistor merely replaces the tube, with proper change of circuit constants as required. Many problems are presented at the end of each chapter. This book is comprised of 17 chapters and opens with an overview of electron theory, followed by a discussion on resistance, inductance, and capacitance, along with their effects on t

  10. Electronic Government and Electronic Participation

    NARCIS (Netherlands)

    Tambouris, E.; Scholl, H.J.; Janssen, M.F.W.H.A.; Wimmer, M.A.; Tarabanis, K.; Gascó, M.; Klievink, A.J.; Lindgren, I.; Milano, M.; Panagiotopoulos, P.; Pardo, T.A.; Parycek, P.; Sæbø, O.

    2015-01-01

    Electronic government and electronic participation continue to transform the public sector and society worldwide and are constantly being transformed themselves by emerging information and communication technologies. This book presents papers from the 14th International Federation for Information P

  11. Electron Tree

    DEFF Research Database (Denmark)

    Appelt, Ane L; Rønde, Heidi S

    2013-01-01

    The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

  12. Electron Tree

    DEFF Research Database (Denmark)

    Appelt, Ane L; Rønde, Heidi S

    2013-01-01

    The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

  13. El amor no surge de los "ojos" sino de los "oídos": Asociaciones semánticas en lenguas yuto-aztecas (Love does not emerge from the "eyes" but from the "ears": Semantic associations in Uto-Aztecan languages

    Directory of Open Access Journals (Sweden)

    Lilián Guerrero

    2010-06-01

    Full Text Available Las asociaciones semánticas entre el vocabulario de partes del cuerpo y verbos de percepción física constituyen un patrón casi universal. Dentro del dominio de la percepción, se ha evidenciado la supremacía de los 'ojos' y la 'visión' como fuentes metafóricas no solo para otros verbos sensoriales ('ver' > 'oír', sino también de otros predicados cognitivos (Viberg, 1984; Sweetser, 1990. Los 'oídos' y la 'audición', en cambio, apenas se mencionan en estos patrones de cambio semántico (Evans y Wilkins, 2000. El presente estudio explora las extensiones semánticas de partes del cuerpo y modalidad sensorial en la familia yuto-azteca. Más que la visión, las lenguas yuto-aztecas prefieren la audición, seguida de otras sedes corporales como 'mente/corazón' y 'sangre', para desarrollar predicados de percepción física, intelectual y emocional. (The semantic associations between the lexicon of body parts and physical perception are almost universal. Within the domain of perception, it has been pointed out the supremacy of the 'eyes' and the 'visual' sense as metaphorical sources for other sensorial verbs ('see' > 'hear' as well as other cognitive domains (Viberg, 1984; Sweetser, 1990. In contrast, the 'ears' and the auditory modality are barely mentioned within these patterns of semantic changes (Evans and Wilkins, 2000. The present study explores the semantic extension of body parts and sensory verbs within the Yuto-Aztecan family. Rather than the vision, Yuto-Aztecan languages prefer the 'ears' and 'hearing', together to other vital body parts such as 'mind/heart' and 'blood', to develop physical, intellectual and emotional perception predicates.

  14. Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Slavko Đerić

    2016-12-01

    Full Text Available Electronic commerce can be defined in different ways. Any definition helps to understand and explain that concept as better as possible.. Electronic commerce is a set of procedures and technologies that automate the tasks of financial transactions using electronic means. Also, according to some authors, electronic commerce is defined as a new concept, which is being developed and which includes process of buying and selling or exchanging products, services or information via computer networks, including the Internet. Electronic commerce is not limited just to buying and selling, but it also includes all pre-sales and after-sales ongoing activities along the supply chain. Introducing electronic commerce, using the Internet and Web services in business, realizes the way to a completely new type of economy - internet economy.

  15. Micropower electronics

    CERN Document Server

    Keonjian, Edward

    1964-01-01

    Micropower Electronics deals with the operation of modern electronic equipment at micropower levels and the problems associated with micropower electronics. Topics covered include the relations between minimum required power density and frequency response for semiconductor triode amplifiers; physical realization of digital logic circuits; micropower microelectronic subsystems; and metal-oxide-semiconductor field-effect devices for micropower logic circuitry. This book is comprised of 10 chapters and begins with an analysis of fundamental relationships and basic requirements pertinent to the ph

  16. Microfluidic electronics.

    Science.gov (United States)

    Cheng, Shi; Wu, Zhigang

    2012-08-21

    Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e.g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.

  17. Paper electronics.

    Science.gov (United States)

    Tobjörk, Daniel; Österbacka, Ronald

    2011-05-03

    Paper is ubiquitous in everyday life and a truly low-cost substrate. The use of paper substrates could be extended even further, if electronic applications would be applied next to or below the printed graphics. However, applying electronics on paper is challenging. The paper surface is not only very rough compared to plastics, but is also porous. While this is detrimental for most electronic devices manufactured directly onto paper substrates, there are also approaches that are compatible with the rough and absorptive paper surface. In this review, recent advances and possibilities of these approaches are evaluated and the limitations of paper electronics are discussed.

  18. Electron holography

    CERN Document Server

    Tonomura, Akira

    1993-01-01

    Holography was devised for breaking through the resolution limit of electron microscopes The advent of a "coherent" field emission electron beam has enabled the use of Electron Holography in various areas of magnetic domain structures observation, fluxon observation in superconductors, and fundamental experiments in physics which have been inaccessible using other techniques After examining the fundamentals of electron holography and its applications to the afore mentioned fields, a detailed discussion of the Aharonov-Bohm effect and the related experiments is presented Many photographs and illustrations are included to elucidate the text

  19. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  20. Electronic Photography

    Science.gov (United States)

    Payne, Meredith Lindsay

    1995-01-01

    The main objective was to assist in the production of electronic images in the Electronic Photography Lab (EPL). The EPL is a new facility serving the electronic photographic needs of the Langley community. The purpose of the Electronic Photography lab is to provide Langley with access to digital imaging technology. Although the EPL has been in operation for less than one year, almost 1,000 images have been produced. The decision to establish the lab was made after careful determination of the centers needs for electronic photography. The LaRC community requires electronic photography for the production of electronic printing, Web sites, desktop publications, and its increased enhancement capabilities. In addition to general use, other considerations went into the planning of the EPL. For example, electronic photography is much less of a burden on the environment compared to conventional photography. Also, the possibilities of an on-line database and retrieval system could make locating past work more efficient. Finally, information in an electronic image is quantified, making measurements and calculations easier for the researcher.

  1. Electron Bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Peters, John W.; Miller, Anne-Frances; Jones, Anne K.; King, Paul W.; Adams, Michael W. W.

    2016-04-01

    Electron bifurcation is the recently recognized third mechanism of biological energy conservation. It simultaneously couples exergonic and endergonic oxidation-reduction reactions to circumvent thermodynamic barriers and minimize free energy loss. Little is known about the details of how electron bifurcating enzymes function, but specifics are beginning to emerge for several bifurcating enzymes. To date, those characterized contain a collection of redox cofactors including flavins and iron-sulfur clusters. Here we discuss the current understanding of bifurcating enzymes and the mechanistic features required to reversibly partition multiple electrons from a single redox site into exergonic and endergonic electron transfer paths.

  2. Printed Electronics

    Science.gov (United States)

    Crain, John M. (Inventor); Lettow, John S. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2016-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  3. Electron optics

    CERN Document Server

    Grivet, Pierre; Bertein, F; Castaing, R; Gauzit, M; Septier, Albert L

    1972-01-01

    Electron Optics, Second English Edition, Part I: Optics is a 10-chapter book that begins by elucidating the fundamental features and basic techniques of electron optics, as well as the distribution of potential and field in electrostatic lenses. This book then explains the field distribution in magnetic lenses; the optical properties of electrostatic and magnetic lenses; and the similarities and differences between glass optics and electron optics. Subsequent chapters focus on lens defects; some electrostatic lenses and triode guns; and magnetic lens models. The strong focusing lenses and pris

  4. Electronic diagrams

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Diagrams is a ready reference and general guide to systems and circuit planning and in the preparation of diagrams for both newcomers and the more experienced. This book presents guidelines and logical procedures that the reader can follow and then be equipped to tackle large complex diagrams by recognition of characteristic 'building blocks' or 'black boxes'. The goal is to break down many of the barriers that often seem to deter students and laymen in learning the art of electronics, especially when they take up electronics as a spare time occupation. This text is comprised of nin

  5. Digital electronics

    CERN Document Server

    Morris, John

    2013-01-01

    An essential companion to John C Morris's 'Analogue Electronics', this clear and accessible text is designed for electronics students, teachers and enthusiasts who already have a basic understanding of electronics, and who wish to develop their knowledge of digital techniques and applications. Employing a discovery-based approach, the author covers fundamental theory before going on to develop an appreciation of logic networks, integrated circuit applications and analogue-digital conversion. A section on digital fault finding and useful ic data sheets completes th

  6. Electronic identity

    CERN Document Server

    de Andrade, Norberto Nuno Gomes; Argles, David

    2014-01-01

    With the increasing availability of electronic services, security and a reliable means by which identity is verified is essential.Written by Norberto Andrade the first chapter of this book provides an overview of the main legal and regulatory aspects regarding electronic identity in Europe and assesses the importance of electronic identity for administration (public), business (private) and, above all, citizens. It also highlights the role of eID as a key enabler of the economy.In the second chapter Lisha Chen-Wilson, David Argles, Michele Schiano di Zenise and Gary Wills discuss the user-cent

  7. Stretchable electronics

    CERN Document Server

    Someya, Takao

    2012-01-01

    With its comprehensive coverage this handbook and ready reference brings together some of the most outstanding scientists in the field to lay down the undisputed knowledge on how to make electronics stretchable.As such, it focuses on gathering and evaluating the materials, designs, models and technologies that enable the fabrication of fully elastic electronic devices which can sustain high strain. Furthermore, it provides a review of those specific applications that directly benefit from highly compliant electronics, including transistors, photonic devices and sensors. In addition to stre

  8. Starting electronics

    CERN Document Server

    Brindley, Keith

    2005-01-01

    Starting Electronics is unrivalled as a highly practical introduction for hobbyists, students and technicians. Keith Brindley introduces readers to the functions of the main component types, their uses, and the basic principles of building and designing electronic circuits. Breadboard layouts make this very much a ready-to-run book for the experimenter; and the use of multimeter, but not oscilloscopes, puts this practical exploration of electronics within reach of every home enthusiast's pocket. The third edition has kept the simplicity and clarity of the original. New material

  9. Polymer electronics

    CERN Document Server

    Geoghegan, Mark

    2013-01-01

    Polymer electronics is the science behind many important new developments in technology, such as the flexible electronic display (e-ink) and many new developments in transistor technology. Solar cells, light-emitting diodes, and transistors are all areas where plastic electronics is likely to, or is already having, a serious impact on our daily lives. With polymer transistors and light-emitting diodes now being commercialised, there is a clear need for a pedagogic text thatdiscusses the subject in a clear and concise fashion suitable for senior undergraduate and graduate students. The content

  10. Aztecas Del Norte: The Chicanos of Aztlan.

    Science.gov (United States)

    Forbes, Jack D.

    The purpose of this book is to examine the Indian heritage of the Mexican Americans of the Southwest. It covers Mexican American history from the time of the Aztecs to the present. In the introduction, the Mexican approach to United States history is discussed. Topics covered are: the Tollecayotl and Mexicayotl heritage; the northward movement;…

  11. Aztecas Del Norte: The Chicanos of Aztlan.

    Science.gov (United States)

    Forbes, Jack D.

    The purpose of this book is to examine the Indian heritage of the Mexican Americans of the Southwest. It covers Mexican American history from the time of the Aztecs to the present. In the introduction, the Mexican approach to United States history is discussed. Topics covered are: the Tollecayotl and Mexicayotl heritage; the northward movement;…

  12. Ecotoxicological assessment of the pharmaceutical fluoxetine hydrochloride and the surfactant dodecyl sodium sulfate after their submission to ionizing radiation treatment; Avaliacao ecotoxicologica do farmaco cloridrato de fluoxetina e do surfactante dodecil sulfato de sodio quando submetidos a tratamento por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Dymes Rafael Alves dos

    2011-07-01

    The use of pharmaceuticals and personal care products and the consequent and continuous input of this substances in the environment generates an increasing need to investigate the presence, behavior and the effects on aquatic biota, as well as new ways to treat effluents containing such substances. Fluoxetine hydrochloride is an active ingredient used in the treatment of depressive disorders and anxiety. As the surfactant sodium dodecyl sulfate is present in many cleaning and personal care products. The present study aimed on assessing the acute toxicity of fluoxetine hydrochloride, sodium dodecyl sulfate and the mixture of both to the aquatic organisms Hyalella azteca, Daphnia similis and Vibrio ficheri. Reducing the toxicity of fluoxetine and the mixture after treatment with ionizing radiation from industrial electron beam accelerator has also been the focus of this study. For Daphnia similis the average values of CE50-4{sub 8h} found for the non-irradiated drug, surfactant and mixture were 14.4 %, 9.62 % and 13.8 %, respectively. After irradiation of the substances, the dose 5 kGy proved itself to be the most effective dose for the treatment of the drug and the mixture as it was obtained the mean values for CE50{sub 48h} 84.60 % and > 90 %, respectively. For Hyalella azteca the acute toxicity tests were performed for water column with duration of 96 hours, the mean values for CE50{sub 96h} found for the drug, the surfactant and the mixture non-irradiated were 5.63 %, 19.29 %, 6.27 %, respectively. For the drug fluoxetine and the mixture irradiated with 5 kGy, it was obtained 69.57 % and 77.7 %, respectively. For Vibrio ficheri the acute toxicity tests for the untreated drug and the drug irradiated with 5 kGy it was obtained CE50{sub 15min} of 6.9 % and 32.88 % respectively. These results presented a reduction of the acute toxicity of the test-substances after irradiation. (author)

  13. Power Electronics

    DEFF Research Database (Denmark)

    Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

    2008-01-01

    is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....

  14. Electronic Elections

    DEFF Research Database (Denmark)

    Schürmann, Carsten

    2009-01-01

    Electronic voting technology is a two edged sword. It comes with many risks but brings also many benefits. Instead of flat out rejecting the technology as uncontrollably dangerous, we advocate in this paper a different technological angle that renders electronic elections trustworthy beyond...... the usual levels of doubt. We exploit the trust that voters currently have into the democratic process and model our techniques around that observation accordingly. In particular, we propose a technique of trace emitting computations to record the individual steps of an electronic voting machine...... for a posteriori validation on an acceptably small trusted computing base. Our technology enables us to prove that an electronic elections preserves the voter’s intent, assuming that the voting machine and the trace verifier are independent....

  15. Electronic plants

    Science.gov (United States)

    Stavrinidou, Eleni; Gabrielsson, Roger; Gomez, Eliot; Crispin, Xavier; Nilsson, Ove; Simon, Daniel T.; Berggren, Magnus

    2015-01-01

    The roots, stems, leaves, and vascular circuitry of higher plants are responsible for conveying the chemical signals that regulate growth and functions. From a certain perspective, these features are analogous to the contacts, interconnections, devices, and wires of discrete and integrated electronic circuits. Although many attempts have been made to augment plant function with electroactive materials, plants’ “circuitry” has never been directly merged with electronics. We report analog and digital organic electronic circuits and devices manufactured in living plants. The four key components of a circuit have been achieved using the xylem, leaves, veins, and signals of the plant as the template and integral part of the circuit elements and functions. With integrated and distributed electronics in plants, one can envisage a range of applications including precision recording and regulation of physiology, energy harvesting from photosynthesis, and alternatives to genetic modification for plant optimization. PMID:26702448

  16. ELECTRONIC SIGNATURES

    African Journals Online (AJOL)

    10332324

    'electronic signature' means data attached to, incorporated in, or logically ... See Cwele v S 2012 4 All SA 497 (SCA); Mohlabeng v Minister of Safety and Security ... ZAKZPHC 51 (2 September 2010); Delta Finance, a Division of Wesbank, ...

  17. Electron Microprobe

    Data.gov (United States)

    Federal Laboratory Consortium — The JEOL JXA-8600 is a conventional hairpin filament thermal emission electron microprobe that is more than 20 years old. It is capable of performing qualitative and...

  18. Electronic commerce

    OpenAIRE

    Veselková, Zdeňka

    2012-01-01

    The thesis deals with a description of electronic commerce from its beginning up to present situation in this area. It explains basic terms connected with electronic commerce and it summarizes the relevant legislation. Moreover it describes e-contracts and rights and duties of both contractual parties. The main view is the view of Internet retailer, which is reflected in the practical part focused on concrete problems of retailers.

  19. Molecular Electronics

    DEFF Research Database (Denmark)

    Jennum, Karsten Stein

    This thesis includes the synthesis and characterisation of organic compounds designed for molecular electronics. The synthesised organic molecules are mainly based on two motifs, the obigo(phenyleneethynylenes) (OPE)s and tetrathiafulvalene (TTF) as shown below. These two scaffolds (OPE and TTF......) are chemically merged together to form cruciform-like structures that are an essential part of the thesis. The cruciform molecules were subjected to molecular conductance measurements to explore their capability towards single-crystal field-effect transistors (Part 1), molecular wires, and single electron......, however, was obtained by a study of a single molecular transistor. The investigated OPE5-TTF compound was captured in a three-terminal experiment, whereby manipulation of the molecule’s electronic spin was possible in different charge states. Thus, we demonstrated how the cruciform molecules could...

  20. Power Electronics

    DEFF Research Database (Denmark)

    Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

    2008-01-01

    energy at the end-user should also be set up. Deregulation of energy has in the past lowered the investment in larger power plants, which means the need for new electrical power sources will be high in the near future. Two major technologies will play important roles to solve the future problems. One...... is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...

  1. Electron Spectroscopy

    Science.gov (United States)

    Siegbahn, Kai

    Wilhelm Conrad Röntgen's discovery of X radiation in 1895 in Wörzburg resulted in an immediate break-through not only in physics but also in Society, the latter mainly because of its sensational radiological applications. Within a short time it furthermore indirectly led to the discovery of radioactivity by Henri Becquerel. The discovery of X radiation opened the gate to modern atomic physics, and radioactivity to nuclear physics. Later on, the discovery of X-ray diffraction by Laue, Friedrich and Knipping in 1912 initiated the field of X-ray spectroscopy with its fundamental contributions to atomic and crystal structures. Secondary electrons were early observed in the scattered radiation when X-rays were hitting a sample. The development of the corresponding electron spectroscopy had to wait a much longer time for its maturity. A survey of electron spectroscopy is presented.

  2. Electronic Commerce

    Energy Technology Data Exchange (ETDEWEB)

    Laird, N. [NRG Information Services Inc., Calgary, AB (Canada)

    1995-11-01

    The concept of electronic commerce in the gas industry was discussed. It was defined as the integration of communication technology, advanced information processing capability and business standards, to improve effectiveness of the business process. Examples of electronic data interchange from the automotive, airline, and banking industry were given. The objective of using this technology in the gas industry was described as the provision of one electronic facility to make seamless contractual and operational arrangements for moving natural gas across participating pipelines. The benefit of seamless integration - one readily available standard system used by several companies - was highlighted. A list of value-added services such as the free movement of bulletins, directories, nominations,and other documents was provided.

  3. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  4. Molecular Electronics

    DEFF Research Database (Denmark)

    Jennum, Karsten Stein

    ) are chemically merged together to form cruciform-like structures that are an essential part of the thesis. The cruciform molecules were subjected to molecular conductance measurements to explore their capability towards single-crystal field-effect transistors (Part 1), molecular wires, and single electron......This thesis includes the synthesis and characterisation of organic compounds designed for molecular electronics. The synthesised organic molecules are mainly based on two motifs, the obigo(phenyleneethynylenes) (OPE)s and tetrathiafulvalene (TTF) as shown below. These two scaffolds (OPE and TTF......, however, was obtained by a study of a single molecular transistor. The investigated OPE5-TTF compound was captured in a three-terminal experiment, whereby manipulation of the molecule’s electronic spin was possible in different charge states. Thus, we demonstrated how the cruciform molecules could...

  5. Greening Electronics

    DEFF Research Database (Denmark)

    Pizzol, Massimo; Søes Kokborg, Morten; Thomsen, Marianne

    Based on a literature review with focus on hazardous substances in waste electric and electronic equipment (WEEE) and numbers from a Danish treatment facility a flow analysis for specific substances has been conducted. Further, the accessible knowledge on human and environmental effects due...

  6. Superconducting electronics

    NARCIS (Netherlands)

    Rogalla, Horst

    1994-01-01

    During the last decades superconducting electronics has been the most prominent area of research for small scale applications of superconductivity. It has experienced quite a stormy development, from individual low frequency devices to devices with high integration density and pico second switching

  7. Electronic Portfolios.

    Science.gov (United States)

    Purves, Alan C.

    1996-01-01

    Outlines three forms of electronic portfolio based on a student's work, a class project about a specific topic, and a class seminar on a broad topic. Discusses logistical problems of management, access, and cross-referencing; technical problems of input, access, and copying; and theoretical issues of the lack of realia, of ownership and copyright,…

  8. Electronic Money.

    Science.gov (United States)

    Schilling, Tim

    Thirty years ago a cashless society was predicted for the near future; paper currency and checks would be an antiquated symbol of the past. Consumers would embrace a new alternative for making payments: electronic money. But currency is still used for 87% of payments, mainly for "nickel and dime" purchases. And checks are the payment…

  9. Electronic spectroscopies

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    2000-01-01

    Diffuse reflectance spectroscopy (DRS) in the ultraviolet, visible and near-infrared region is a versatile spectroscopic technique, as both d-d and charge transfer transitions of supported TMI can be probed. One of the advantages of electronic spectroscopy is that the obtained information is

  10. Electronic Homework.

    Science.gov (United States)

    Lee, Fong-lok; Heyworth, Rex M.

    The Electronic Homework assistant system is composed of two components: the Computer Tutor and the Homework Administrator. The Computer Tutor is an intelligent tutoring system that can provide personal assistance like supplying hints, checking errors, providing remediation and prioritizing problems. The Homework Administrator is a teacher's…

  11. Greening Electronics

    DEFF Research Database (Denmark)

    Pizzol, Massimo; Søes Kokborg, Morten; Thomsen, Marianne

    Based on a literature review with focus on hazardous substances in waste electric and electronic equipment (WEEE) and numbers from a Danish treatment facility a flow analysis for specific substances has been conducted. Further, the accessible knowledge on human and environmental effects due to po...

  12. Electronic Government

    DEFF Research Database (Denmark)

    Wimmer, Maria A.; Traunmüller, Roland; Grönlund, Åke

    This book constitutes the refereed proceedings of the 4th International Conference on Electronic Government, EGOV 2005, held in Copenhagen, Denmark, in August 2005. The 30 revised papers presented were carefully reviewed and selected from numerous submissions, and assess the state-of-the-art in e...

  13. Electronic detectors for electron microscopy.

    Science.gov (United States)

    Faruqi, A R; McMullan, G

    2011-08-01

    Electron microscopy (EM) is an important tool for high-resolution structure determination in applications ranging from condensed matter to biology. Electronic detectors are now used in most applications in EM as they offer convenience and immediate feedback that is not possible with film or image plates. The earliest forms of electronic detector used routinely in transmission electron microscopy (TEM) were charge coupled devices (CCDs) and for many applications these remain perfectly adequate. There are however applications, such as the study of radiation-sensitive biological samples, where film is still used and improved detectors would be of great value. The emphasis in this review is therefore on detectors for use in such applications. Two of the most promising candidates for improved detection are: monolithic active pixel sensors (MAPS) and hybrid pixel detectors (of which Medipix2 was chosen for this study). From the studies described in this review, a back-thinned MAPS detector appears well suited to replace film in for the study of radiation-sensitive samples at 300 keV, while Medipix2 is suited to use at lower energies and especially in situations with very low count rates. The performance of a detector depends on the energy of electrons to be recorded, which in turn is dependent on the application it is being used for; results are described for a wide range of electron energies ranging from 40 to 300 keV. The basic properties of detectors are discussed in terms of their modulation transfer function (MTF) and detective quantum efficiency (DQE) as a function of spatial frequency.

  14. Electronic Aggression

    Centers for Disease Control (CDC) Podcasts

    2007-11-20

    Aggression is no longer limited to the school yard. New forms of electronic media, such as blogs, instant messaging, chat rooms, email, text messaging, and the internet are providing new arenas for youth violence to occur.  Created: 11/20/2007 by National Center for Injury Prevention and Control, Division of Violence Prevention.   Date Released: 11/28/2007.

  15. Interacting Electrons

    Science.gov (United States)

    Martin, Richard M.; Reining, Lucia; Ceperley, David M.

    2016-06-01

    Preface; Part I. Interacting Electrons: Beyond the Independent-Particle Picture: 1. The many electron problem: introduction; 2. Signatures of electron correlation; 3. Concepts and models for interacting electrons; Part II. Foundations of Theory for Many-Body Systems: 4. Mean fields and auxiliary systems; 5. Correlation functions; 6. Many-body wavefunctions; 7. Particles and quasi-particles; 8. Functionals in many-particle physics; Part III. Many-Body Green's Function Methods: 9. Many-body perturbation theory: expansion in the interaction; 10. Many-body perturbation theory via functional derivatives; 11. The RPA and the GW approximation for the self-energy; 12. GWA calculations in practice; 13. GWA calculations: illustrative results; 14. RPA and beyond: the Bethe-Salpeter equation; 15. Beyond the GW approximation; 16. Dynamical mean field theory; 17. Beyond the single-site approximation in DMFT; 18. Solvers for embedded systems; 19. Characteristic hamiltonians for solids with d and f states; 20. Examples of calculations for solids with d and f states; 21. Combining Green's functions approaches: an outlook; Part IV. Stochastic Methods: 22. Introduction to stochastic methods; 23. Variational Monte Carlo; 24. Projector quantum Monte Carlo; 25. Path integral Monte Carlo; 26. Concluding remarks; Part V. Appendices: A. Second quantization; B. Pictures; C. Green's functions: general properties; D. Matsubara formulation for Green's functions for T ̸= 0; E. Time-ordering, contours, and non-equilibrium; F. Hedin's equations in a basis; G. Unique solutions in Green's function theory; H. Properties of functionals; I. Auxiliary systems and constrained search; J. Derivation of the Luttinger theorem; K. Gutzwiller and Hubbard approaches; References; Index.

  16. ELECTRON GUN

    Science.gov (United States)

    Christofilos, N.C.; Ehlers, K.W.

    1960-04-01

    A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

  17. Toxicity of carbon nanotubes to freshwater aquatic invertebrates

    Science.gov (United States)

    Mwangi, Joseph N.; Wang, Ning; Ingersoll, Christopher G.; Hardesty, Doug K.; Brunson, Eric L.; Li, Hao; Deng, Baolin

    2012-01-01

    Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the "metal-free" CNTs contributed to the toxicity.

  18. Basic electronics

    CERN Document Server

    Tayal, DC

    2010-01-01

    The second edition of this book incorporates the comments and suggestions of my friends and students who have critically studied the first edition. In this edition the changes and additions have been made and subject matter has been rearranged at some places. The purpose of this text is to provide a comprehensive and up-to-date study of the principles of operation of solid state devices, their basic circuits and application of these circuits to various electronic systems, so that it can serve as a standard text not only for universities and colleges but also for technical institutes. This book

  19. Electronic materials

    CERN Document Server

    Kwok, H L

    2010-01-01

    The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

  20. Electronic Router

    Science.gov (United States)

    Crusan, Jason

    2005-01-01

    Electronic Router (E-Router) is an application program for routing documents among the cognizant individuals in a government agency or other organization. E-Router supplants a prior 14 NASA Tech Briefs, May 2005 system in which paper documents were routed physically in packages by use of paper slips, packages could be lost, routing times were unacceptably long, tracking of packages was difficult, and there was a need for much photocopying. E-Router enables a user to create a digital package to be routed. Input accepted by E-Router includes the title of the package, the person(s) to whom the package is to be routed, attached files, and comments to reviewers. Electronic mail is used to notify reviewers of needed actions. The creator of the package can, at any time, see the status of the package in the routing structure. At the end of the routing process, E-Router keeps a record of the package and of approvals and/or concurrences of the reviewers. There are commercial programs that perform the general functions of E-Router, but they are more complicated. E-Router is Web-based, easy to use, and does not require the installation or use of client software.

  1. Practical electronics handbook

    CERN Document Server

    Sinclair, Ian R

    2013-01-01

    Practical Electronics Handbook, Third Edition provides the frequently used and highly applicable principles of electronics and electronic circuits.The book contains relevant information in electronics. The topics discussed in the text include passive and active discrete components; linear and digital I.C.s; microprocessors and microprocessor systems; digital-analogue conversions; computer aids in electronics design; and electronic hardware components.Electronic circuit constructors, service engineers, electronic design engineers, and anyone with an interest in electronics will find the book ve

  2. Electronic Preprints

    Science.gov (United States)

    Hanisch, R.

    1999-12-01

    Despite the tremendous advances in electronic publications and the increasing rapidity with which papers are now moving from acceptance into ``print,'' preprints continue to be an important mode of communication within the astronomy community. The Los Alamos e-preprint service, astro-ph, provides for rapid and cost-free (to authors and readers) dissemination of manuscripts. As the use of astro-ph has increased the number of paper preprints in circulation to libraries has decreased, and institutional preprint series appear to be waning. It is unfortunate, however, that astro-ph does not function in collaboration with the refereed publications. For example, there is no systematic tracking of manuscripts from preprint to their final, published form, and as a centralized archive it is difficult to distribute the tracking and maintenance functions. It retains documents that have been superseded or have become obsolete. We are currently developing a distributed preprint and document management system which can support both distributed collections of preprints (e.g., traditional institutional preprint series), can link to the LANL collections, can index other documents in the ``grey'' literature (observatory reports, telescope and instrument user's manuals, calls for proposals, etc.), and can function as a manuscript submission tool for the refereed journals. This system is being developed to work cooperatively with the refereed literature so that, for example, links to preprints are updated to links to the final published papers.

  3. Sustainable Management of Electronics

    Science.gov (United States)

    To provide information on EPAs strategy for electronics stewardship, certified electronics recyclers and the Challenge; as well as where to donate unwanted electronics, how to calculate benefits, and what's going on with electronics mgmt in their states.

  4. EDITORIAL: Synaptic electronics Synaptic electronics

    Science.gov (United States)

    Demming, Anna; Gimzewski, James K.; Vuillaume, Dominique

    2013-09-01

    Conventional computers excel in logic and accurate scientific calculations but make hard work of open ended problems that human brains handle easily. Even von Neumann—the mathematician and polymath who first developed the programming architecture that forms the basis of today's computers—was already looking to the brain for future developments before his death in 1957 [1]. Neuromorphic computing uses approaches that better mimic the working of the human brain. Recent developments in nanotechnology are now providing structures with very accommodating properties for neuromorphic approaches. This special issue, with guest editors James K Gimzewski and Dominique Vuillaume, is devoted to research at the serendipitous interface between the two disciplines. 'Synaptic electronics', looks at artificial devices with connections that demonstrate behaviour similar to synapses in the nervous system allowing a new and more powerful approach to computing. Synapses and connecting neurons respond differently to incident signals depending on the history of signals previously experienced, ultimately leading to short term and long term memory behaviour. The basic characteristics of a synapse can be replicated with around ten simple transistors. However with the human brain having around 1011 neurons and 1015 synapses, artificial neurons and synapses from basic transistors are unlikely to accommodate the scalability required. The discovery of nanoscale elements that function as 'memristors' has provided a key tool for the implementation of synaptic connections [2]. Leon Chua first developed the concept of the 'The memristor—the missing circuit element' in 1971 [3]. In this special issue he presents a tutorial describing how memristor research has fed into our understanding of synaptic behaviour and how they can be applied in information processing [4]. He also describes, 'The new principle of local activity, which uncovers a minuscule life-enabling "Goldilocks zone", dubbed the

  5. Electronic Mimosa

    Science.gov (United States)

    Gupta, Sanjay; Datta, Meera S.; Rana, Vivek; Grover, Shailesh

    1996-04-01

    This paper describes the design of a low-cost, 2D, electromagnetic tracking device for personal computers. This interface makes use of the well-known principle of electromagnetic induction to locate the position of a transmitter in an x-y plane. This device has a ring which is worn by the user on the index finger. The computer monitor is overlaid with a transparent screen equipped with tuned electromagnetic sensors. These sensors pick up the signals transmitted by the transmitter coil on the finger. The receiver circuit extracts the envelope of the received signal and digitizes it. These digitized values of x and y axis signals are read by the computer through the standard parallel port. The system software running on the computer calculates the x and y co-ordinates of the transmitter coil and displays a cursor at that location. The transmitter also has a button which can be used like a mouse button. This keypress information is also transmitted by the electromagnetic means. The device driver for this tracker replaces the standard mouse driver. Hence most applications which use a mouse can also use this tracker. Its name `Mimosa' indicates that the user need not touch the screen (Mimosa Pudica is the Latin name of a plant whose leaves wilt when touched). Presently work is on to achieve uniform sensitivity over the entire screen and reducing transmitter power consumption. In order to demonstrate its working, a small, 3D game was written. The player has to reach a pre-defined location after traversing through a maze. The paper describes the interface electronics, system software, mechanical design and the sample application.

  6. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  7. Nano-Electronics and Bio-Electronics

    Science.gov (United States)

    Srivastava, Deepak; Kwak, Dochan (Technical Monitor)

    2001-01-01

    Viewgraph presentation on Nano-Electronics and Bio-Electronics is discussed. Topics discussed include: NASA Ames nanotechnology program, Potential Carbon Nanotube (CNT) application, CNT synthesis,Computational Nanotechnology, and protein nanotubes.

  8. Electronics for LHC Experiments

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This document gathers the abstracts of most presentations made at this workshop on electronics for the large hadron collider (LHC) experiments. The presentations were arranged into 6 sessions: 1) electronics for tracker, 2) trigger electronics, 3) detector control systems, 4) data acquisition, 5) electronics for calorimeters and electronics for muons, and 6) links, power systems, grounding and shielding, testing and quality assurance.

  9. Interface Electronic Circuitry for an Electronic Tongue

    Science.gov (United States)

    Keymeulen, Didier; Buehler, Martin

    2007-01-01

    Electronic circuitry has been developed to serve as an interface between an electronic tongue and digital input/output boards in a laptop computer that is used to control the tongue and process its readings. Electronic tongues can be used for a variety of purposes, including evaluating water quality, analyzing biochemicals, analyzing biofilms, and measuring electrical conductivities of soils.

  10. Electron beam focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  11. Electronics and Information

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Previously founded as CCPITMachinery and Electronics Sub-council and CCOIC Machinery and Electronics Chamber of Corn-merce in June, 1988, CCPIT Electronics Sub-Council and CCOIC Electronics Chamber of Commerce were established in May, 1993, and then renamed as CCPIT Electronics and Information Industry Sub-council and CCOIC Electronics and Infor-mation Industry Chamber of Commerce (CCPITECC) in September 1999.

  12. Electronic Correlations in Electron Transfer Systems

    Science.gov (United States)

    Bulla, Ralf; Tornow, Sabine; Anders, Frithjof

    Electron transfer processes play a central role in many chemical and biological systems. Already the transfer of a single electron from the donor to the acceptor can be viewed as a complicated many-body problem, due to the coupling of the electron to the infinitely many environmental degrees of freedom, realized by density fluctuations of the solvent or molecular vibrations of the protein matrix. We focus on the quantum mechanical modelling of two-electron transfer processes whose dynamics is governed by the Coulomb interaction between the electrons as well as the environmental degrees of freedoms represented by a bosonic bath. We identify the regime of parameters in which concerted transfer of the two electrons occurs and discuss the influence of the Coulomb repulsion and the coupling strength to the environment on the electron transfer rate. Calculations are performed using the non-perturbative numerical renormalization group approach for both equilibrium and non-equilibrium properties.

  13. Electron Microscopy Center (EMC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Electron Microscopy Center (EMC) at Argonne National Laboratory develops and maintains unique capabilities for electron beam characterization and applies those...

  14. Fungal propagules and DNA in feces of two detritus-feeding amphipods.

    Science.gov (United States)

    Sridhar, Kandikere Ramaiah; Beaton, Margaret; Bärlocher, Felix

    2011-01-01

    Aquatic shredders (leaf-eating invertebrates) preferentially ingest and digest leaves colonized by aquatic hyphomycetes (fungi). This activity destroys leaf-associated fungal biomass and detritial resources in streams. Fungal counter-adaptations may include the ability to survive passage through the invertebrate's digestive tract. When fecal pellets of Gammarus tigrinus and Hyalella azteca were incubated with sterile leaves, spores of nine (G. tigrinus) and seven (H. azteca) aquatic hyphomycete species were subsequently released from the leaves, indicating the presence of viable fungal structures in the feces. Extraction, amplification, and sequencing of DNA from feces revealed numerous fungal phylotypes, two of which could be assigned unequivocally to an aquatic hyphomycete. The estimated contributions of major fungal groups varied depending on whether 18S or ITS sequences were amplified and cloned. We conclude that a variable proportion of fungal DNA in the feces of detritivores may originate from aquatic hyphomycetes. Amplified DNA may be associated with metabolically active, dormant, or dead fungal cells.

  15. Chronic effects of CuO Nanoparticles on Lymnaea stagnalis

    DEFF Research Database (Denmark)

    Falk, Nina; Zwicky, Julie; Rewentlow, Julie

    Due to their small size and high surface-to-volume ratio, the properties and reactivity of NPs are different from those of their bulk forms. However, these properties might cause different behaviour and effects in the environment and investigations of possible nano specific effects are thus highl...... relevant. Investigation of the long-term effects of CuO NPs on growth, mortality and precopulation of Hyalella azteca compared to CuCl2 and to further examine possible delayed effects and ability to recover from Cu exposure....

  16. Biological hazard evaluation of a pharmaceutical effluent before and after a photo-Fenton treatment.

    Science.gov (United States)

    Novoa-Luna, Karen Adriana; Mendoza-Zepeda, Arisbeht; Natividad, Reyna; Romero, Rubi; Galar-Martínez, Marcela; Gómez-Oliván, Leobardo Manuel

    2016-11-01

    The aim of this study was to evaluate the biological hazard of a pharmaceutical effluent before and after treatment. For the former, the determined 96h-LC50 value was 1.2%. The photo-Fenton treatment catalyzed with an iron-pillared clay reduced this parameter by 341.7%. Statistically significant increases with respect to the control group (Pheterogeneous photo-Fenton process decreases the presence of PCT, oxidative stress, genotoxic damage and LC50 in Hyalella azteca. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Investigations on Electronic Materials

    OpenAIRE

    E. Pugnor; T. Kormány

    1982-01-01

    Electronics has been described as a materials oriented technology. In this sense a short review is given concerning: the connection of materials characterization to the design and processing of electronic components; the most important materials characterization methods used for electronic materials; the strategy of organizing a complete material characterization system for selected electronic components.

  18. Electron-attachment processes

    Science.gov (United States)

    Christophorou, L. G.; McCorkle, D. L.; Christodoulides, A. A.

    Topics covered include: modes of production of negative ions, techniques for the study of electron attachment processes, dissociative electron attachment to ground state molecules, dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), molecular parent negative ions, and negative ions formed by ion pair processes and by collisions of molecules with ground state and Rydberg atoms.

  19. Electronic Health Records

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Electronic Health Records KidsHealth > For Teens > Electronic Health Records Print A A A What's in ... t happen overnight, they are coming. Understanding EHRs Electronic health records (EHR) — also called electronic medical records ( ...

  20. Introduction to electronics

    CERN Document Server

    CERN. Geneva

    2005-01-01

    Electronics in HEP experiments: specificities and evolution The Art of Electronics: is there something beyond Ohm's law? Basic building blocks of Analog electronics: quickly understanding a schematic Charge preamps, current preamps and future preamps, shaping and the rest Electronics noise: fundamental and practical Evolution of technology: ASICs, FPGAs...

  1. Introduction to Electronics course

    CERN Document Server

    CERN. Geneva HR-RFA

    2006-01-01

    Electronics in HEP experiments: specificities and evolution The Art of Electronics: is there something beyond Ohm's law? Basic building blocks of Analog electronics: quickly understanding a schematic Charge preamps, current preamps and future preamps, shaping and the rest Electronics noise: fundamental and practical Evolution of technology: ASICs, FPGAs...

  2. Electronic Health Records

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Electronic Health Records KidsHealth > For Teens > Electronic Health Records A A A What's in this ... t happen overnight, they are coming. Understanding EHRs Electronic health records (EHR) — also called electronic medical records ( ...

  3. Introduction to Electronic Marketing.

    Science.gov (United States)

    Dilbeck, Lettie

    These materials for a five-unit course were developed to introduce secondary and postsecondary students to the use of electronic equipment in marketing. The units cover the following topics: electronic marketing as a valid marketing approach; telemarketing; radio electronic media marketing; television electronic media marketing; and cable TV…

  4. Hybrid printed electronics

    NARCIS (Netherlands)

    Koetse, M.; Smits, E.; Rubingh, E.; Teunissen, P.; Kusters, R.; Abbel, R.; Brand, J. van den

    2016-01-01

    Although many electronic functionalities can be realized by printed or organic electronics, short-term marketable products often require robust, reproducible, and nondisturbing technologies. In this chapter we show how hybrid electronics, a combination of printed circuitry, thin-film electronics,

  5. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  6. Electronics engineer's reference book

    CERN Document Server

    Mazda, F F

    1989-01-01

    Electronics Engineer's Reference Book, Sixth Edition is a five-part book that begins with a synopsis of mathematical and electrical techniques used in the analysis of electronic systems. Part II covers physical phenomena, such as electricity, light, and radiation, often met with in electronic systems. Part III contains chapters on basic electronic components and materials, the building blocks of any electronic design. Part IV highlights electronic circuit design and instrumentation. The last part shows the application areas of electronics such as radar and computers.

  7. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  8. Electronics engineer's reference book

    CERN Document Server

    Turner, L W

    1976-01-01

    Electronics Engineer's Reference Book, 4th Edition is a reference book for electronic engineers that reviews the knowledge and techniques in electronics engineering and covers topics ranging from basics to materials and components, devices, circuits, measurements, and applications. This edition is comprised of 27 chapters; the first of which presents general information on electronics engineering, including terminology, mathematical equations, mathematical signs and symbols, and Greek alphabet and symbols. Attention then turns to the history of electronics; electromagnetic and nuclear radiatio

  9. Single electron-ics with carbon nanotubes

    NARCIS (Netherlands)

    Götz, G.T.J.

    2010-01-01

    We experimentally investigate Quantum Dots, formed in Carbon Nanotubes. The first part of this thesis deals with charge sensing on such quantum dots. The charge sensor is a metallic Single-electron-transistor, sensitive to the charge of a single electron on the quantum dot. We use this technique for

  10. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  11. VIRTUAL ELECTRONIC COMPONENTS OF THE ELECTRONIC EQUIPMENT

    Directory of Open Access Journals (Sweden)

    E. Lazarevich

    2013-01-01

    Full Text Available The article is present new idea of the creation, developments and improvements of the electronic equipment of complex systems by means of the virtual electronic components. The idea of the virtual electronic components is a presentation and perception of the creation and developments of the equipment on two forming: real – in the manner of standard marketed block of the intellectual property and image – in the manner of virtual component. The real component in most cases slows the development of the electronic equipment. The imaginary component is the «locomotive» of development of the electronic equipment. The Imaginary component contains the scientific has brushed against developer. The scientific has brushed against developer reveals of itself in the manner of virtual component on the modern level of the design rates of microelectronics.

  12. Electron transporting semiconducting polymers in organic electronics.

    Science.gov (United States)

    Zhao, Xingang; Zhan, Xiaowei

    2011-07-01

    Significant progress has been achieved in the preparation of semiconducting polymers over the past two decades, and successful commercial devices based on them are slowly beginning to enter the market. However, most of the conjugated polymers are hole transporting, or p-type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or n-type, materials that have lagged behind their p-type counterparts. Organic electron transporting materials are essential for the fabrication of organic p-n junctions, organic photovoltaic cells (OPVs), n-channel organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) and complementary logic circuits. In this critical review we focus upon recent developments in several classes of electron transporting semiconducting polymers used in OLEDs, OFETs and OPVs, and survey and analyze what is currently known concerning electron transporting semiconductor architecture, electronic structure, and device performance relationships (87 references).

  13. Electronics for dummies

    CERN Document Server

    Shamieh

    2015-01-01

    Explore the basic concepts of electronics, build your electronics workbench, and begin creating fun electronics projects right away! Electronics For Dummies, 3rd Edition is your guide to the world of electronics. Spanning circuitry, wiring, robotics, transmitters, amplifiers, and more, this book demystifies electricity basics and beyond. The third edition offers new content revised to reflect the latest advancements in the electronics field, and it offers full color project examples to spark your creativity and inspire you to put your new skills to use! Packed with projects that can be comple

  14. High energy electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Parkhomchuk, V. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  15. RHIC electron lenses upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Altinbas, Z. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Binello, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Costanzo, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Drees, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Harvey, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mi, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Michnoff, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Pikin, A. I. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Samms, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Shrey, T. C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Schoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tan, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015, two electron lenses were used to partially compensate for the head-on beam-beam effect for the first time. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.

  16. Electronic Commerce and Competitive Procurement

    Science.gov (United States)

    1991-06-01

    Explains the application of electronic commerce techniques (electronic data interchange (EDI), electronic mail (E-mail), electronic bulletin boards...purchase procedures of the Federal Acquisition Regulation (FAR). Changes to the FAR to recognize electronic commerce are recommended. Also discussed...are opportunities to use electronic commerce and small business and legal considerations of electronic commerce . This report describes how electronic

  17. Certified Electronics Recyclers

    Science.gov (United States)

    Learn how EPA encourages all electronics recyclers become certified by demonstrating to an accredited, independent third-party auditor and that they meet specific standards to safely recycle and manage electronics.

  18. Chapter 9: Electronics

    OpenAIRE

    Spieler, Helmuth G

    2008-01-01

    Sophisticated front-end electronics are a key part of practically all modern radiation detector systems. This chapter introduces the basic principles and their implementation. Topics include signal acquisition, electronic noise, pulse shaping (analog and digital), and data readout techniques.

  19. Chapter 9: Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Grupen, Claus; Shwartz, Boris A.

    2006-12-19

    Sophisticated front-end electronics are a key part of practically all modern radiation detector systems. This chapter introduces the basic principles and their implementation. Topics include signal acquisition, electronic noise, pulse shaping (analog and digital), and data readout techniques.

  20. Presidential Electronic Records Library

    Data.gov (United States)

    National Archives and Records Administration — PERL (Presidential Electronic Records Library) used to ingest and provide internal access to the Presidential electronic Records of the Reagan, Bush, and Clinton...

  1. THE ELECTRONIC SIGNATURE

    Directory of Open Access Journals (Sweden)

    Voiculescu Madalina Irena

    2009-05-01

    Full Text Available Article refers to significance and the digital signature in electronic commerce. Internet and electronic commerce open up many new opportunities for the consumer, yet, the security (or perceived lack of security of exchanging personal and financial data

  2. Electronic Submission of Labels

    Science.gov (United States)

    Pesticide registrants can provide draft and final labels to EPA electronically for our review as part of the pesticide registration process. The electronic submission of labels by registrants is voluntary but strongly encouraged.

  3. Chapter 9: Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Grupen, Claus; Shwartz, Boris A.

    2006-12-19

    Sophisticated front-end electronics are a key part of practically all modern radiation detector systems. This chapter introduces the basic principles and their implementation. Topics include signal acquisition, electronic noise, pulse shaping (analog and digital), and data readout techniques.

  4. Laboratory Handbook Electronics

    CERN Multimedia

    1966-01-01

    Laboratory manual 1966 format A3 with the list of equipment cables, electronic tubes, chassis, diodes transistors etc. One of CERN's first material catalogue for construction components for mechanical and electronic chassis.

  5. Electron shuttles in biotechnology.

    Science.gov (United States)

    Watanabe, Kazuya; Manefield, Mike; Lee, Matthew; Kouzuma, Atsushi

    2009-12-01

    Electron-shuttling compounds (electron shuttles [ESs], or redox mediators) are essential components in intracellular electron transfer, while microbes also utilize self-produced and naturally present ESs for extracellular electron transfer. These compounds assist in microbial energy metabolism by facilitating electron transfer between microbes, from electron-donating substances to microbes, and/or from microbes to electron-accepting substances. Artificially supplemented ESs can create new routes of electron flow in the microbial energy metabolism, thereby opening up new possibilities for the application of microbes to biotechnology processes. Typical examples of such processes include halogenated-organics bioremediation, azo-dye decolorization, and microbial fuel cells. Herein we suggest that ESs can be applied widely to create new microbial biotechnology processes.

  6. Electronics materials research

    Science.gov (United States)

    1982-01-01

    The electronic materials and is aimed at the establishment of quantitative relationships underlying crystal growth parameters, materials properties, electronic characteristics and device applications. The overall program evolves about the following main thrust areas: (1) crystal growth novel approaches to engineering of semiconductor materials; (2) investigation of materials properties and electronic characteristics on a macro and microscale; (3) surface properties and surface interactions with the bulk and ambients; (4) electronic properties controlling device applications and device performance.

  7. Thermography of electronic devices

    OpenAIRE

    Panfilova S. P.; Vlasov A. I.; Gridnev V. N.; Chervinsky A. S.

    2007-01-01

    The possibility of application of thermography to diagnose the electronic devices is analyzed in the article. Typical faults of electronic devices which can be found by means of thermography are given. Advantages of noncontact thermal inspection in comparison with the contact one are described. Some features of thermography of electronic devices are considered. Thermography apparatus is viewed and some pieces of advice about choosing it for electronic devices diagnosis are given. An example o...

  8. Electronics and computer acronyms

    CERN Document Server

    Brown, Phil

    1988-01-01

    Electronics and Computer Acronyms presents a list of almost 2,500 acronyms related to electronics and computers. The material for this book is drawn from a number of subject areas, including electrical, electronics, computers, telecommunications, fiber optics, microcomputers/microprocessors, audio, video, and information technology. The acronyms also encompass avionics, military, data processing, instrumentation, units, measurement, standards, services, organizations, associations, and companies. This dictionary offers a comprehensive and broad view of electronics and all that is associated wi

  9. Extreme environment electronics

    CERN Document Server

    Cressler, John D

    2012-01-01

    Unfriendly to conventional electronic devices, circuits, and systems, extreme environments represent a serious challenge to designers and mission architects. The first truly comprehensive guide to this specialized field, Extreme Environment Electronics explains the essential aspects of designing and using devices, circuits, and electronic systems intended to operate in extreme environments, including across wide temperature ranges and in radiation-intense scenarios such as space. The Definitive Guide to Extreme Environment Electronics Featuring contributions by some of the world's foremost exp

  10. Mechanical Engineering for Electronics.

    OpenAIRE

    Was, Loïc

    2012-01-01

    Schlumberger drilling tools are exposed to very hard loading conditions (shocks, vibrations, thermal cycling) while performing a job. As these tools are full of electronics, issues can quickly come from electronics failure. Mechanisms of failure occurring in electronics are very complex but can be predicted in some cases. The first part of the thesis describes in which context mechanical engineering applied to electronics is used in Schlumberger. The different kinds of failure which will be i...

  11. Handbook on electronic commerce

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M. [Illinois Univ., Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology; Blanning, R. [Vanderbilt Univ., Nashville, TN (United States). Owen Graduate School of Management; Strader, T. [Iowa State Univ., Ames, IA (United States). Management Information Systems; Whinston, A. [eds.] [Texas Univ., Austin, TX (United States). Dept. of Management Science and Information Systems

    2000-07-01

    The world is undergoing a revolution to a digital economy, with pronounced implications for corporate strategy, marketing, operations, information systems, customer services, global supply-chain management, and product distribution. This handbook examines the aspects of electronic commerce, including electronic storefront, on-line business, consumer interface, business-to-business networking, digital payment, legal issues, information product development, and electronic business models. Indispensable for academics, students and professionals who are interested in Electronic Commerce and Internet Business. (orig.)

  12. Atomicity in Electronic Commerce,

    Science.gov (United States)

    1996-01-01

    tremendous demand for the ability to electronically buy and sell goods over networks. Electronic commerce has inspired a large variety of work... commerce . It then briefly surveys some major types of electronic commerce pointing out flaws in atomicity. We pay special attention to the atomicity...problems of proposals for digital cash. The paper presents two examples of highly atomic electronic commerce systems: NetBill and Cryptographic Postage Indicia.

  13. Syringe-injectable electronics.

    Science.gov (United States)

    Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M

    2015-07-01

    Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

  14. Technology of Electronic Signatur

    OpenAIRE

    2004-01-01

    An electronic signature uses a hash of message and an asymetrical algorithm of encryption for its generation. During verification of message on receiver side the hash of original message must be identical with the hash of received message. Electronic message is secured autentization of author and integrity of transmission date. By electronic signature it is possible to sign everything what is in digital form.

  15. ELECTRONS IN NONPOLAR LIQUIDS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLROYD,R.A.

    2002-10-22

    Excess electrons can be introduced into liquids by absorption of high energy radiation, by photoionization, or by photoinjection from metal surfaces. The electron's chemical and physical properties can then be measured, but this requires that the electrons remain free. That is, the liquid must be sufficiently free of electron attaching impurities for these studies. The drift mobility as well as other transport properties of the electron are discussed here as well as electron reactions, free-ion yields and energy levels, Ionization processes typically produce electrons with excess kinetic energy. In liquids during thermalization, where this excess energy is lost to bath molecules, the electrons travel some distance from their geminate positive ions. In general the electrons at this point are still within the coulombic field of their geminate ions and a large fraction of the electrons recombine. However, some electrons escape recombination and the yield that escapes to become free electrons and ions is termed G{sub fi}. Reported values of G{sub fi} for molecular liquids range from 0.05 to 1.1 per 100 eV of energy absorbed. The reasons for this 20-fold range of yields are discussed here.

  16. Syringe injectable electronics

    Science.gov (United States)

    Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

    2015-01-01

    Seamless and minimally-invasive three-dimensional (3D) interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating syringe injection and subsequent unfolding of submicrometer-thick, centimeter-scale macroporous mesh electronics through needles with a diameter as small as 100 micrometers. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with > 90% device yield. We demonstrate several applications of syringe injectable electronics as a general approach for interpenetrating flexible electronics with 3D structures, including (i) monitoring of internal mechanical strains in polymer cavities, (ii) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (iii) in vivo multiplexed neural recording. Moreover, syringe injection enables delivery of flexible electronics through a rigid shell, delivery of large volume flexible electronics that can fill internal cavities and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics. PMID:26053995

  17. Arduino electronics blueprints

    CERN Document Server

    Wilcher, Don

    2015-01-01

    This book is intended for those who want to learn about electronics and coding by building amazing devices and gadgets with Arduino. If you are an experienced developer who understands the basics of electronics, then you can quickly learn how to build smart devices using Arduino. The only experience needed is a desire to learn about electronics, circuit breadboarding, and coding.

  18. Electron measurement in PHENIX

    Energy Technology Data Exchange (ETDEWEB)

    Akiba, Y. [Univ. of Tokyo, Tanashi (Japan)

    1995-07-15

    Electron Measurement in PHENIX detector at RHIC is discussed. The yield and S/N ratio at vector meson peaks ({phi}, {omega}, {rho}{sup o}, and J/{psi}) are evaluated. The electrons from open charm decay, and its consequence to the di-electron measurements is discussed.

  19. EFFECTIVE ELECTRONIC TUTORIAL

    Directory of Open Access Journals (Sweden)

    Andrei A. Fedoseev

    2014-01-01

    Full Text Available The article analyzes effective electronic tutorials creation and application based on the theory of pedagogy. Herewith the issues of necessary electronic tutorial functional, ways of the educational process organization with the use of information and communication technologies and the logistics of electronic educational resources are touched upon. 

  20. Polarized Electron Source Developments

    Energy Technology Data Exchange (ETDEWEB)

    Charles K. Sinclair

    1990-02-23

    Presently, only two methods of producing beams of polarized electrons for injection into linear accelerators are in use. Each of these methods uses optical pumping by circularly polarized light to produce electron polarization. In one case, electron polarization is established in metastable helium atoms, while in the other case, the polarized electrons are produced in the conduction band of appropriate semiconductors. The polarized electrons are liberated from the helium metastable by chemi-ionization, and from the semiconductors by lowering the work function at the surface of the material. Developments with each of these sources since the 1988 Spin Physics Conference are reviewed, and the prospects for further improvements discussed.

  1. Soldering in electronics assembly

    CERN Document Server

    Judd, Mike

    2013-01-01

    Soldering in Electronics Assembly discusses several concerns in soldering of electronic assemblies. The book is comprised of nine chapters that tackle different areas in electronic assembly soldering. Chapter 1 discusses the soldering process itself, while Chapter 2 covers the electronic assemblies. Chapter 3 talks about solders and Chapter 4 deals with flux. The text also tackles the CS and SC soldering process. The cleaning of soldered assemblies, solder quality, and standards and specifications are also discussed. The book will be of great use to professionals who deal with electronic assem

  2. Ultracold Ordered Electron Beam

    Science.gov (United States)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.

    1988-01-01

    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  3. Ultracold ordered electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Habs, D.; Kramp, J.; Krause, P.; Matl, K.; Neumann, R.; Schwalm, D.

    1988-01-01

    We have started an experimental program to develop an ultracold electron beam, which can be used together with a standard electron cooling device in the Heidelberg Test Storage Ring TSR. In contrast to the standard-type design using electron beam extraction beam extraction from a heated cathode, the ultracold beam is produced by photoemission of electrons from a cooled semiconductor crystal irradiated with an intense near-infrared laser light beam. Adiabatic acceleration is expected to provide ordering of the electron beam itself. Besides the cooling of ion beams to extremely low temperatures, with the aim of obtaining crystallization, the ultracold beam will constitute an excellent target for atomic physics experiments.

  4. Electronic equipment packaging technology

    CERN Document Server

    Ginsberg, Gerald L

    1992-01-01

    The last twenty years have seen major advances in the electronics industry. Perhaps the most significant aspect of these advances has been the significant role that electronic equipment plays in almost all product markets. Even though electronic equipment is used in a broad base of applications, many future applications have yet to be conceived. This versatility of electron­ ics has been brought about primarily by the significant advances that have been made in integrated circuit technology. The electronic product user is rarely aware of the integrated circuits within the equipment. However, the user is often very aware of the size, weight, mod­ ularity, maintainability, aesthetics, and human interface features of the product. In fact, these are aspects of the products that often are instrumental in deter­ mining its success or failure in the marketplace. Optimizing these and other product features is the primary role of Electronic Equipment Packaging Technology. As the electronics industry continues to pr...

  5. Advanced adhesives in electronics

    CERN Document Server

    Bailey, C

    2011-01-01

    Adhesives are widely used in the manufacture of electronic devices to act as passive and active components. Recently there has been considerable interest in the use of conductive adhesives. This book reviews key types of conductive adhesives, processing methods, properties and the way they can be modelled as well as potential applications.$bAdhesives for electronic applications serve important functional and structural purposes in electronic components and packaging, and have developed significantly over the last few decades. Advanced adhesives in electronics reviews recent developments in adhesive joining technology, processing and properties. The book opens with an introduction to adhesive joining technology for electronics. Part one goes on to cover different types of adhesive used in electronic systems, including thermally conductive adhesives, isotropic and anisotropic conductive adhesives and underfill adhesives for flip-chip applications. Part two focuses on the properties and processing of electronic ...

  6. Electron crystallography and aquaporins.

    Science.gov (United States)

    Schenk, Andreas D; Hite, Richard K; Engel, Andreas; Fujiyoshi, Yoshinori; Walz, Thomas

    2010-01-01

    Electron crystallography of two-dimensional (2D) crystals can provide information on the structure of membrane proteins at near-atomic resolution. Originally developed and used to determine the structure of bacteriorhodopsin (bR), electron crystallography has recently been applied to elucidate the structure of aquaporins (AQPs), a family of membrane proteins that form pores mostly for water but also other solutes. While electron crystallography has made major contributions to our understanding of the structure and function of AQPs, structural studies on AQPs, in turn, have fostered a number of technical developments in electron crystallography. In this contribution, we summarize the insights electron crystallography has provided into the biology of AQPs, and describe technical advancements in electron crystallography that were driven by structural studies on AQP 2D crystals. In addition, we discuss some of the lessons that were learned from electron crystallographic work on AQPs.

  7. Automotive electronics design fundamentals

    CERN Document Server

    Zaman, Najamuz

    2015-01-01

    This book explains the topology behind automotive electronics architectures and examines how they can be profoundly augmented with embedded controllers. These controllers serve as the core building blocks of today’s vehicle electronics. Rather than simply teaching electrical basics, this unique resource focuses on the fundamental concepts of vehicle electronics architecture, and details the wide variety of Electronic Control Modules (ECMs) that enable the increasingly sophisticated "bells & whistles" of modern designs.  A must-have for automotive design engineers, technicians working in automotive electronics repair centers and students taking automotive electronics courses, this guide bridges the gap between academic instruction and industry practice with clear, concise advice on how to design and optimize automotive electronics with embedded controllers.

  8. Medan Electronic Mall Arsitektur Ikonik

    OpenAIRE

    David,, A.

    2014-01-01

    With present the Medan Electronic Mall is intended to meet the needs of electronic goods from electronic of communication, Office Electronics, Household Electronics, Hobbies or electronic game, Medan Electronic Mall also hosts for the people of North Sumatra Province especially for people of Medan City to get particular information will be the development of electronic goods and also enjoy all kinds of things related to electronics such as Game Center, Cyber/Virtual Game, Internet...

  9. Amphipod densities and indices of wetland quality across the upper-Midwest, USA

    Science.gov (United States)

    Anteau, M.J.; Afton, A.D.

    2008-01-01

    Nutritional, behavioral, and diet data for lesser scaup (Aythya affinis [Eyton, 1838]) indicates that there has been a decrease in amphipod (Gammarus lacustris [G. O. Sars, 1863] and Hyalella azteca [Saussure, 1858]) density and wetland quality throughout the upper-Midwest, USA. Accordingly, we estimated densities of Gammarus and Hyalella in six eco-physiographic regions of Iowa, Minnesota, and North Dakota; 356 randomly selected semipermanent and permanent wetlands were sampled during springs 2004 and 2005. We also examined indices of wetland quality (e.g., turbidity, fish communities, aquatic vegetation) among regions in a random subset of these wetlands (n = 267). Gammarus and Hyalella were present in 19% and 54% of wetlands sampled, respectively. Gammarus and Hyalella densities in North Dakota were higher than those in Iowa and Minnesota. Although historical data are limited, our regional mean (1 to 12 m-3) amphipod densities (Gammarus + Hyalella) were markedly lower than any of the historical density estimates. Fish, important predators of amphipods, occurred in 31%-45% of wetlands in North Dakota, 84% of wetlands in the Red River Valley, and 74%-84% of wetlands in Iowa and Minnesota. Turbidity in wetlands of Minnesota Morainal (4.0 NTU geometric mean) and Red River Valley (6.1 NTU) regions appeared low relative to that of the rest of the upper-Midwest (13.2-17.5 NTU). We conclude that observed estimates of amphipods, fish, and turbidity are consistent with low wetland quality, which has resulted in lower food availability for various wildlife species, especially lesser scaup, which use these wetlands in the upper-Midwest. ?? 2008, The Society of Wetland Scientists.

  10. Engineered phages for electronics.

    Science.gov (United States)

    Cui, Yue

    2016-11-15

    Phages are traditionally widely studied in biology and chemistry. In recent years, engineered phages have attracted significant attentions for functionalization or construction of electronic devices, due to their specific binding, catalytic, nucleating or electronic properties. To apply the engineered phages in electronics, these are a number of interesting questions: how to engineer phages for electronics? How are the engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies to construct electronics devices with engineered phages? This review will highlight the early attempts to address these questions and explore the fundamental and practical aspects of engineered phages in electronics, including the approaches for selection or expression of specific peptides on phage coat proteins, characterization of engineered phages in electronics, assembly of electronic materials, patterning of engineered phages, and construction of electronic devices. It provides the methodologies and opens up ex-cit-ing op-por-tu-ni-ties for the development of a variety of new electronic materials and devices based on engineered phages for future applications.

  11. Scanning ultrafast electron microscopy.

    Science.gov (United States)

    Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

    2010-08-24

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

  12. Scanning ultrafast electron microscopy

    Science.gov (United States)

    Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

  13. Metamaterials for Ballistic Electrons

    CERN Document Server

    Dragoman, D; Dragoman, Daniela; Dragoman, Mircea

    2007-01-01

    The paper presents a metamaterial for ballistic electrons, which consists of a quantum barrier formed in a semiconductor with negative effective electron mass. This barrier is the analogue of a metamaterial for electromagnetic waves in media with negative electrical permittivity and magnetic permeability. Besides applications similar to those of optical metamaterials, a nanosized slab of a metamaterial for ballistic electrons, sandwiched between quantum wells of positive effective mass materials, reveals unexpected conduction properties, e.g. single or multiple room temperature negative differential conductance regions at very low voltages and with considerable peak-to-valley ratios, while the traversal time of ballistic electrons can be tuned to larger or smaller values than in the absence of the metamaterial slab. Thus, slow and fast electrons, analogous to slow and fast light, occur in metamaterials for ballistic electrons.

  14. Electrons in Nanostructures

    DEFF Research Database (Denmark)

    Flindt, Christian

    2007-01-01

    or a few electrons. Such few-electron devices are expected to form the building blocks of future electrical circuits and it is thus necessary to develop a thorough theoretical understanding of the physics of electrons in nanostructures. Re- garding applications there is a particular interest......-based communication. The statistical description of electron transport through nanostructures is based on rate equations, and the primary contribution of the thesis in that respect is the development of a method that allows for the calculation of the distribution of electrons passing through a device. The method......This thesis concerns theoretical aspects of electrons in man-made nanostruc- tures. Advances in nanofabrication technology during recent decades have made it possible to produce electrical devices on the nano-scale, whose func- tionality is determined by the quantum mechanical nature of a single...

  15. Single electron spintronics.

    Science.gov (United States)

    Dempsey, Kari J; Ciudad, David; Marrows, Christopher H

    2011-08-13

    Single electron electronics is now well developed, and allows the manipulation of electrons one-by-one as they tunnel on and off a nanoscale conducting island. In the past decade or so, there have been concerted efforts in several laboratories to construct single electron devices incorporating ferromagnetic components in order to introduce spin functionality. The use of ferromagnetic electrodes with a non-magnetic island can lead to spin accumulation on the island. On the other hand, making the dot also ferromagnetic introduces new physics such as tunnelling magnetoresistance enhancement in the cotunnelling regime and manifestations of the Kondo effect. Such nanoscale islands are also found to have long spin lifetimes. Conventional spintronics makes use of the average spin-polarization of a large ensemble of electrons: this new approach offers the prospect of accessing the quantum properties of the electron, and is a candidate approach to the construction of solid-state spin-based qubits.

  16. Electron transfer in proteins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1991-01-01

    Electron migration between and within proteins is one of the most prevalent forms of biological energy conversion processes. Electron transfer reactions take place between active centers such as transition metal ions or organic cofactors over considerable distances at fast rates and with remarkable...... specificity. The electron transfer is attained through weak electronic interaction between the active sites, so that considerable research efforts are centered on resolving the factors that control the rates of long-distance electron transfer reactions in proteins. These factors include (in addition......-containing proteins. These proteins serve almost exclusively in electron transfer reactions, and as it turns out, their metal coordination sites are endowed with properties uniquely optimized for their function....

  17. Nanocrystals for electronics.

    Science.gov (United States)

    Panthani, Matthew G; Korgel, Brian A

    2012-01-01

    Semiconductor nanocrystals are promising materials for low-cost large-area electronic device fabrication. They can be synthesized with a wide variety of chemical compositions and size-tunable optical and electronic properties as well as dispersed in solvents for room-temperature deposition using various types of printing processes. This review addresses research progress in large-area electronic device applications using nanocrystal-based electrically active thin films, including thin-film transistors, light-emitting diodes, photovoltaics, and thermoelectrics.

  18. Technology of Electronic Signatur

    Directory of Open Access Journals (Sweden)

    Jaroslav Sadovsky

    2004-01-01

    Full Text Available An electronic signature uses a hash of message and an asymetrical algorithm of encryption for its generation. During verification of message on receiver side the hash of original message must be identical with the hash of received message. Electronic message is secured autentization of author and integrity of transmission date. By electronic signature it is possible to sign everything what is in digital form.

  19. Modern electronic materials

    CERN Document Server

    Watkins, John B

    2013-01-01

    Modern Electronic Materials focuses on the development of electronic components. The book first discusses the history of electronic components, including early developments up to 1900, developments up to World War II, post-war developments, and a comparison of present microelectric techniques. The text takes a look at resistive materials. Topics include resistor requirements, basic properties, evaporated film resistors, thick film resistors, and special resistors. The text examines dielectric materials. Considerations include basic properties, evaporated dielectric materials, ceramic dielectri

  20. Field emission electron source

    Science.gov (United States)

    Zettl, Alexander Karlwalter; Cohen, Marvin Lou

    2000-01-01

    A novel field emitter material, field emission electron source, and commercially feasible fabrication method is described. The inventive field emission electron source produces reliable electron currents of up to 400 mA/cm.sup.2 at 200 volts. The emitter is robust and the current it produces is not sensitive to variability of vacuum or the distance between the emitter tip and the cathode. The novel emitter has a sharp turn-on near 100 volts.

  1. Introduction to electronics

    CERN Document Server

    Korneff, Theodore

    1966-01-01

    Introduction to Electronics focuses on the study of electronics and electronic devices. Composed of 14 chapters, the book starts with discussions on dc circuits, including resistance, voltmeter, ammeter, galvanometer, internal resistance, and positive and negative currents. This topic is followed by discussions on ac circuits, particularly addressing voltage and current, average power, resistive load, complex plane, and parallel circuits. Discussions also focus on filters and tuned circuits, diodes, and power supplies. Particularly given attention are the processes, diagrams, and analyses

  2. ETHICS AND ELECTRONIC VOTING

    OpenAIRE

    2014-01-01

    13 pages; International audience; In the first part, we will define the main properties of a democratic election, providing a typology of electronic devices and give a view on some legal documents pertaining to the matter. In the second part, the ethics of voting will be evaluated: our methodology is detailed, followed by an examination of pure paper-based elections, paperless electronic voting and verifiable electronic voting. The new concept of legally operative transparency is defined and ...

  3. Electronic collection management

    CERN Document Server

    Mcginnis, Suzan D

    2013-01-01

    Build and manage your collection of digital resources with these successful strategies! This comprehensive volume is a practical guide to the art and science of acquiring and organizing electronic resources. The collections discussed here range in size from small college libraries to large research libraries, but all are facing similar problems: shrinking budgets, increasing demands, and rapidly shifting formats. Electronic Collection Management offers new ideas for coping with these issues. Bringing together diverse aspects of collection development, Electronic Collection

  4. Introduction to printed electronics

    CERN Document Server

    Suganuma, Katsuaki

    2014-01-01

    This book describes in detail modern technologies for printed electronics, explaining how nanotechnology and modern printing technology are merging to revolutionize electronics fabrication of thin, lightweight, large, and inexpensive products. Readers will benefit from the explanations of materials, devices and circuits used to design and implement the latest applications of printed electronics, such as thin flexible OLED displays, organic solar cells, OLED lighting, smart wallpaper, sensors, logic, memory and more.

  5. Thallium contamination of water in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Cheam, V. [National Water Research Institute Branch, Burlington, ON (Canada). Aquatic Ecosystems Protection Research Branch

    2001-07-01

    A highly sensitive instrument, a Laser-Excited Atomic Fluorescence Spectrometer, has been developed to study thallium contamination in some important Canadian ecosystems from the Arctic (containing very low thallium concentration) to coal-related industries across Canada and even to the study of thallium toxicity in an invertebrate, Hyalella azteca. Overall, the data indicate that the coal power plants and mines contain higher thallium concentrations than the other ecosystems studied, and the eastern region has the highest Tl concentrations compared to other regions. The range of thallium concentration in ng/L for the Arctic snow and ice was between not detected and 8.4, for the Great Lakes waters 0.9 to 48, for pore waters 0.1 to 213, for western coal power plants and mines 0.1 to 1326, for central coal power plants 1.2 to 175, for eastern coal power plants and mines 0.2 to 23605, and for miscellaneous sites across Canada not detected to 4390 ng/L. Some of these high concentrations and those high ones reported in industrial wastewaters exceeded the chronic toxicity endpoints for Hyalella azteca mortality, growth and reproduction, and thus can cause serious distress to the environment. All data were integrated into a map of thallium distribution, the first one in Canada. Natural background level of thallium for the Arctic was estimated to be 0.02 to 0.03 pg/g.

  6. Electronic signal conditioning

    CERN Document Server

    NEWBY, BRUCE

    1994-01-01

    At technician level, brief references to signal conditioning crop up in a fragmented way in various textbooks, but there has been no single textbook, until now!More advanced texts do exist but they are more mathematical and presuppose a higher level of understanding of electronics and statistics. Electronic Signal Conditioning is designed for HNC/D students and City & Guilds Electronics Servicing 2240 Parts 2 & 3. It will also be useful for BTEC National, Advanced GNVQ, A-level electronics and introductory courses at degree level.

  7. Flying Electronic Warfare Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides NP-3D aircraft host platforms for Effectiveness of Navy Electronic Warfare Systems (ENEWS) Program antiship missile (ASM) seeker simulators used...

  8. Smart Electronic Textiles.

    Science.gov (United States)

    Weng, Wei; Chen, Peining; He, Sisi; Sun, Xuemei; Peng, Huisheng

    2016-05-17

    This Review describes the state-of-the-art of wearable electronics (smart textiles). The unique and promising advantages of smart electronic textiles are highlighted by comparing them with the conventional planar counterparts. The main kinds of smart electronic textiles based on different functionalities, namely the generation, storage, and utilization of electricity, are then discussed with an emphasis on the use of functional materials. The remaining challenges are summarized together with important new directions to provide some useful clues for the future development of smart electronic textiles.

  9. Electronic Wallets in Danger

    Directory of Open Access Journals (Sweden)

    Jean-Michel Sahut

    2006-10-01

    Full Text Available The erratic development of electronic wallets (EW illustrates thedifficulties of their adoption by the general public and shopkeepersalike. With exceptions, such as Proton in Europe and Octopus in Asia,a lot of electronic wallets are likely to disappear in the next fewyears. Yet the key factors of success are known by banks which oftenchoose to ignore them. However, the strategic change taken by some inorder to bring a fresh start to electronic wallets like Moneo couldreverse the tendency. Nevertheless, it will still be necessary to waitseveral years before seeing electronic wallets really imposethemselves as a credible alternative to payments in cash.

  10. Analytical Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — The Titan 80-300 is a transmission electron microscope (TEM) equipped with spectroscopic detectors to allow chemical, elemental, and other analytical measurements to...

  11. Fundamentals of electronics

    CERN Document Server

    Schubert, Thomas F

    2015-01-01

    This book, Electronic Devices and Circuit Application, is the first of four books of a larger work, Fundamentals of Electronics. It is comprised of four chapters describing the basic operation of each of the four fundamental building blocks of modern electronics: operational amplifiers, semiconductor diodes, bipolar junction transistors, and field effect transistors. Attention is focused on the reader obtaining a clear understanding of each of the devices when it is operated in equilibrium. Ideas fundamental to the study of electronic circuits are also developed in the book at a basic level to

  12. High-power electronics

    CERN Document Server

    Kapitsa, Petr Leonidovich

    1966-01-01

    High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

  13. Electron correlation in molecules

    CERN Document Server

    Wilson, S

    2007-01-01

    Electron correlation effects are of vital significance to the calculation of potential energy curves and surfaces, the study of molecular excitation processes, and in the theory of electron-molecule scattering. This text describes methods for addressing one of theoretical chemistry's central problems, the study of electron correlation effects in molecules.Although the energy associated with electron correlation is a small fraction of the total energy of an atom or molecule, it is of the same order of magnitude as most energies of chemical interest. If the solution of quantum mechanical equatio

  14. Flying Electronic Warfare Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides NP-3D aircraft host platforms for Effectiveness of Navy Electronic Warfare Systems (ENEWS) Program antiship missile (ASM) seeker simulators used...

  15. Electronics pocket book

    CERN Document Server

    Parr, E A

    1981-01-01

    Electronics Pocket Book, Fourth Edition is a nonmathematical presentation of the many varied topics covered by electronics. The book tackles electron physics, electronic components (i.e. resistors, capacitors, and conductors), integrated circuits, and the principles of a.c. and d.c. amplifiers. The text also discusses oscillators, digital circuits, digital computers, and optoelectronics (i.e., sensors, emitters, and devices that utilize light). Communications (such as line and radio communications, transmitters, receivers, and digital techniques); the principles and examples of servosystems; a

  16. Flexible Electronics Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Flexible Electronics Research Facility designs, synthesizes, tests, and fabricates materials and devices compatible with flexible substrates for Army information...

  17. Electron Transfer Chain Catalysis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Electron-transfer chain (ETC) catalysis belongs to the family of chain reactions where the electron is the catalyst. The ETC mechanism could be initiated by chemical activation, electrochemistry, or photolysis. If this pathway is applied to the preparation of organometallic complexes, it utilizes the greatly enhanced reactivity of organometallic 17e and 19e radicals. The chemical propagation is followed by the cross electron-transfer while the electron-transfer step is also followed by the chemical propagation, creating a loop in which reactants are facilely transformed into products. Interestingly the overall reaction is without any net redox change.

  18. Electron Transfer Chain Catalysis

    Institute of Scientific and Technical Information of China (English)

    LIU; LingKang

    2001-01-01

    Electron-transfer chain (ETC) catalysis belongs to the family of chain reactions where the electron is the catalyst. The ETC mechanism could be initiated by chemical activation, electrochemistry, or photolysis. If this pathway is applied to the preparation of organometallic complexes, it utilizes the greatly enhanced reactivity of organometallic 17e and 19e radicals. The chemical propagation is followed by the cross electron-transfer while the electron-transfer step is also followed by the chemical propagation, creating a loop in which reactants are facilely transformed into products. Interestingly the overall reaction is without any net redox change.  ……

  19. Nanosecond electron microscopes

    Science.gov (United States)

    Bostanjoglo; Elschner; Mao; Nink; Weingartner

    2000-04-01

    Combining electron optics, fast electronics and pulsed lasers, a transmission and a photoelectron emission microscope were built, which visualize events in thin films and on surfaces with a time resolution of several nanoseconds. The high-speed electron microscopy is capable to track fast laser-induced processes in metals below the ablation threshold, which are difficult to detect by other imaging techniques. The material response to nano- and femtosecond laser pulses was found to be very different. It was dominated by thermo/chemocapillary flow and chemical reactions in the case of nanosecond pulses, and by mechanical deformations and non-thermal electron emission after a femtosecond pulse.

  20. Electron caustic lithography

    Directory of Open Access Journals (Sweden)

    S. M. Kennedy

    2012-06-01

    Full Text Available A maskless method of electron beam lithography is described which uses the reflection of an electron beam from an electrostatic mirror to produce caustics in the demagnified image projected onto a resist–coated wafer. By varying the electron optics, e.g. via objective lens defocus, both the morphology and dimensions of the caustic features may be controlled, producing a range of bright and tightly focused projected features. The method is illustrated for line and fold caustics and is complementary to other methods of reflective electron beam lithography.

  1. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2011-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Ea

  2. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2007-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Each chapter ends with a set

  3. (Pulsed electron beam precharger)

    Energy Technology Data Exchange (ETDEWEB)

    Finney, W.C. (ed.); Shelton, W.N.

    1990-01-01

    This report discusses the following topics on electron beam guns: Precharger Modification; Installation of Charge vs. Radius Apparatus; High Concentration Aerosol Generation; and Data Acquisition and Analysis System.

  4. Electronic circuits fundamentals & applications

    CERN Document Server

    Tooley, Mike

    2015-01-01

    Electronics explained in one volume, using both theoretical and practical applications.New chapter on Raspberry PiCompanion website contains free electronic tools to aid learning for students and a question bank for lecturersPractical investigations and questions within each chapter help reinforce learning Mike Tooley provides all the information required to get to grips with the fundamentals of electronics, detailing the underpinning knowledge necessary to appreciate the operation of a wide range of electronic circuits, including amplifiers, logic circuits, power supplies and oscillators. The

  5. Electronics Environmental Benefits Calculator

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Electronics Environmental Benefits Calculator (EEBC) was developed to assist organizations in estimating the environmental benefits of greening their purchase,...

  6. Electronic Service Statistics - Quarterly Report

    Data.gov (United States)

    Social Security Administration — This is a quarterly report that compares electronic data vs non-electronic data for electronic services. Report contains six main sections namely, electronic access,...

  7. Optical Electronics. Electronics Module 9. Instructor's Guide.

    Science.gov (United States)

    Franken, Bill

    This module is the ninth of 10 modules in the competency-based electronics series. Introductory materials include a listing of competencies addressed in the module, a parts/equipment list, and a cross reference table of instructional materials. Five instructional units cover: fiber optic cable; optical coupler; lasers and masers; optical displays;…

  8. Notes on Electronic Lexicography

    CERN Document Server

    Parvanov, Yavor

    2011-01-01

    These notes are a continuation of topics covered by V. Selegej in his article "Electronic Dictionaries and Computational lexicography". How can an electronic dictionary have as its object the description of closely related languages? Obviously, such a question allows multiple answers.

  9. Managing electronic records

    CERN Document Server

    McLeod, Julie

    2005-01-01

    For records management courses, this book covers the theory and practice of managing electronic records as business and information assets. It focuses on the strategies, systems and procedures necessary to ensure that electronic records are appropriately created, captured, organized and retained over time to meet business and legal requirements.

  10. STEP electronic system design

    Science.gov (United States)

    Couch, R. H.; Johnson, J. W.

    1984-01-01

    The STEP electronic system design is discussed. The purpose of the design is outlined. The electronic system design is summarized and it is found that: an effective conceptual system design is developed; the design represents a unique set of capabilities; makes efficient use of available orbiter resources; the system capabilities exceed identified potential experiment needs.

  11. Electron tunnel sensor technology

    Science.gov (United States)

    Waltman, S. B.; Kaiser, W. J.

    1989-01-01

    The recent development of Scanning Tunneling Microscopy technology allows the application of electron tunneling to position detectors for the first time. The vacuum tunnel junction is one of the most sensitive position detection mechanisms available. It is also compact, simple, and requires little power. A prototype accelerometer based on electron tunneling, and other sensor applications of this promising new technology are described.

  12. Electron scattering violates parity

    CERN Multimedia

    2004-01-01

    Parity violation has been observed in collisions between electrons at the Stanford Linear Accelerator Center (SLAC) in the US. The resuls, which are in agreement with the Stanford Model of particle physics, also provide a new measurement of the weak charge of the electron (½ page)

  13. Pulsed Plasma Electron Sources

    Science.gov (United States)

    Krasik, Yakov

    2008-11-01

    Pulsed (˜10-7 s) electron beams with high current density (>10^2 A/cm^2) are generated in diodes with electric field of E > 10^6 V/cm. The source of electrons in these diodes is explosive emission plasma, which limits pulse duration; in the case E Hadas and Ya. E. Krasik, Europhysics Lett. 82, 55001 (2008).

  14. Electron transfer in peptides.

    Science.gov (United States)

    Shah, Afzal; Adhikari, Bimalendu; Martic, Sanela; Munir, Azeema; Shahzad, Suniya; Ahmad, Khurshid; Kraatz, Heinz-Bernhard

    2015-02-21

    In this review, we discuss the factors that influence electron transfer in peptides. We summarize experimental results from solution and surface studies and highlight the ongoing debate on the mechanistic aspects of this fundamental reaction. Here, we provide a balanced approach that remains unbiased and does not favor one mechanistic view over another. Support for a putative hopping mechanism in which an electron transfers in a stepwise manner is contrasted with experimental results that support electron tunneling or even some form of ballistic transfer or a pathway transfer for an electron between donor and acceptor sites. In some cases, experimental evidence suggests that a change in the electron transfer mechanism occurs as a result of donor-acceptor separation. However, this common understanding of the switch between tunneling and hopping as a function of chain length is not sufficient for explaining electron transfer in peptides. Apart from chain length, several other factors such as the extent of the secondary structure, backbone conformation, dipole orientation, the presence of special amino acids, hydrogen bonding, and the dynamic properties of a peptide also influence the rate and mode of electron transfer in peptides. Electron transfer plays a key role in physical, chemical and biological systems, so its control is a fundamental task in bioelectrochemical systems, the design of peptide based sensors and molecular junctions. Therefore, this topic is at the heart of a number of biological and technological processes and thus remains of vital interest.

  15. Single particle electron microscopy

    NARCIS (Netherlands)

    Boekema, Egbert J.; Folea, Mihaela; Kouril, Roman; Kouřil, Roman

    2009-01-01

    Electron microscopy (EM) in combination with image analysis is a powerful technique to study protein structures at low, medium, and high resolution. Since electron micrographs of biological objects are very noisy, improvement of the signal-to-noise ratio by image processing is an integral part of EM

  16. Electronic Mail Connections.

    Science.gov (United States)

    Tucker, Susan A.

    1987-01-01

    Provides an overview of new developments in electronic mail, including the interconnection of online networks, some on an international level; and news on system upgrades of specific information services. The growth of the electronic mail industry and possible future trends are discussed and a glossary of technical terms is included. (CLB)

  17. Electronically Controlled Resistor Bank

    Science.gov (United States)

    Ross, Walter L.

    1987-01-01

    Resistance quickly varied in small steps over wide range. Device with no moving parts provides variable electrical resistance. Used with analog or digital circuity to provide electronic selection of large number of resistance values for testing, simulation, control, or other purposes. Nearest electromechanical equivalent of all-electronic device is potentiometer driven by servomotor.

  18. Electronics and Lithuanian Terminology

    Directory of Open Access Journals (Sweden)

    Stasys Zajankauskas

    2011-04-01

    Full Text Available It is found that the vacuum triode, transistor, monolithic circuit and microprocessor were the most important inventions of traditional electronics. Thus, the origins of the traditional electronics should be associated with the invention of the vacuum triode, but not with the invention of vacuum diode. It is shown that the science of electronics is not as young as computer science or up-to-date information technologies: electronics, including active electronics, had already celebrated the centenary, and the period of 2004–2008 is the period of numerous already solid jubilees. Thus, the terminology of electronics is not at initial stage of evolution as well – general terms should be already systematized and normalized. However, Lithuanian terms for electronic devices invented before tens of years and terms for old-defined notions associated with these devices are still varying, some are worsened. Especially, the incorrectly motivated terms used for variations of transistors and microcircuits are analyzed in the article. It is motivated which terms are preferable, systematic and exact. The paper is dedicated to the 50th anniversary of monolithic circuit, as well as the 60th anniversary of transistor, the 40th jubilee of microprocessor and centenary of electronics.

  19. Electronically Induced Phase Transformations

    Science.gov (United States)

    1980-12-01

    ries (w hen the Slater free-electron exchange is used). A systematic the active researcher. study of relativistic electron densities and isomer...comp:wrees aux mesures actuelles d’effet dHvA d’Arko et Schirber. Le calu; du facteur de forme neutronique en presence d’un champ magnetique est en bon

  20. Una principessa azteca: Tecuichpotzin Ichcaxochitzin – Isabel de Moctezuma

    Directory of Open Access Journals (Sweden)

    Rosa Maria Grillo

    2016-12-01

    Full Text Available In the framework of the ‘gender studies’ dedicated to forgotten women in history, a prominent place is occupied by Tecuichpotzin Ichcaxochitzin (“Cotton flower, the revered daughter of the lord”   daughter of Moctezuma II, was probably born at the end of the first decade of the sixteenth century. Baptized as Isabel de Moctezuma, she lived a life straddling two worlds and two eras: daughter and wife of kings, repudiated by Cortés, she is sometimes described as the anti Malinche, loyal to her people but perfectly integrated in the colonial system. This paper will compare different sources – historical chronicles of that time and subsequent periods, historical fiction   in order to provide a credible profile and to correctly interpret such contradictory comments and opinions.

  1. El Calendario Azteca - para Colorear. (The Aztec Calendar - for Coloring.)

    Science.gov (United States)

    1977

    The Aztec calendar had a different god representing each month of the year. This color-by-number book illustrates each god and gives its name and the month it represents in Spanish. Each part of the god is numbered from 1 to 20 with a color corresponding to each number. (NQ)

  2. El Calendario Azteca - para Colorear. (The Aztec Calendar - for Coloring.)

    Science.gov (United States)

    1977

    The Aztec calendar had a different god representing each month of the year. This color-by-number book illustrates each god and gives its name and the month it represents in Spanish. Each part of the god is numbered from 1 to 20 with a color corresponding to each number. (NQ)

  3. Green and biodegradable electronics

    Directory of Open Access Journals (Sweden)

    Mihai Irimia-Vladu

    2012-07-01

    Full Text Available We live in a world where the lifetime of electronics is becoming shorter, now approaching an average of several months. This poses a growing ecological problem. This brief review will present some of the initial steps taken to address the issue of electronic waste with biodegradable organic electronic materials. Many organic materials have been shown to be biodegradable, safe, and nontoxic, including compounds of natural origin. Additionally, the unique features of such organic materials suggest they will be useful in biofunctional electronics; demonstrating functions that would be inaccessible for traditional inorganic compounds. Such materials may lead to fully biodegradable and even biocompatible/biometabolizable electronics for many low-cost applications. This review highlights recent progress in these classes of material, covering substrates and insulators, semiconductors, and finally conductors.

  4. LEIR electron cooler status

    CERN Document Server

    Tranquille, G; Parkhomchuk, V; Prieto, V; Sautier, R

    2006-01-01

    The electron cooler for LEIR is the first of a new generation of coolers being commissioned for fast phase space cooling of ion beams in storage rings. It is a stateof- the-art cooler incorporating all the recent developments in electron cooling technology (adiabatic expansion, electrostatic bend, variable density electron beam) and is designed to deliver up to 600 mA of electron current for the cooling and stacking of Pb54+ ions in the frame of the ions for LHC project. In this paper we present our experience with the commissioning of the new device as well as the first results of ion beam cooling with a high-intensity variable-density electron beam.

  5. Electron Cyclotron Emission Radiometer

    Science.gov (United States)

    Morales, Cristina

    2009-11-01

    There is much interest in studying plasmas that generate hot electrons. The goal of this project is to develop a wide band electron cyclotron radiometer to measure the non-Maxwellian rapid rises in electron temperature. These rapid increases in temperature will then be correlated to instabilities in the plasma. This project explores a type of noncontact temperature measurement. We will attempt to show the feasibility of electron cyclotron emissions to measure the Maryland Centrifugal Experiment's electron plasma temperature. The radiometer has been designed to have 100dB of gain and a sensitivity of 24mV/dB given by its logarithmic amplifier. If successful, this radiometer will be used as a diagnostic tool in later projects such as the proposed experiment studying magnetic reconnection using solar flux loops.

  6. Practical electronics for inventors

    CERN Document Server

    Scherz, Paul

    2013-01-01

    Spark your creativity and gain the electronics skills required to transform your innovative ideas into functioning gadgets. This hands-on, updated guide outlines electrical principles and provides thorough, easy-to-follow instructions, schematics, and illustrations. Findout how to select components, safely assemble circuits, perform error tests, and build plug-and-play prototypes. Practical Electronics for Inventors, Third Edition, features all-new chapters on sensors, microcontrollers, modular electronics, and the latest software tools. Coverage includes: Resistors, capacitors, inductors, and transformers Diodes, transistors, and integrated circuits Optoelectronics, solar cells, and phototransistors Sensors, GPS modules, and touch screens Op amps, regulators, and power supplies Digital electronics, LCD displays, and logic gates Microcontrollers and prototyping platforms, including Arduino DC motors, RC servos, and stepper motors Microphones, audio amps, and speakers Modular electronics and prototyping.

  7. Simulations of Gaussian electron guns for RHIC electron lens

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-02-28

    Simulations of two versions of the electron gun for RHIC electron lens are presented. The electron guns have to generate an electron beam with Gaussian radial profile of the electron beam density. To achieve the Gaussian electron emission profile on the cathode we used a combination of the gun electrodes and shaping of the cathode surface. Dependence of electron gun performance parameters on the geometry of electrodes and the margins for electrodes positioning are presented.

  8. Electronic Collection Management and Electronic Information Services

    Science.gov (United States)

    2003-04-01

    TITLE: Electronic Information Management for PfP Nations [La gestion electronique des informations pour les pays du PfP] To order the complete...banking and securities trading. E- commerce has moved into many other areas and it is now possible to purchase a wide variety of goods and services on line...include interactive e- commerce and e-governance services as well as various organizational database management needs (including registrations, membership

  9. Electron Cooling of RHIC

    CERN Document Server

    Ben-Zvi, Ilan; Barton, Donald; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Bruhwiler, David L; Burger, Al; Burov, Alexey; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Derbenev, Yaroslav S; Eidelman, Yury I; Favale, Anthony; Fedotov, Alexei V; Fischer, Wolfram; Funk, L W; Gassner, David M; Hahn, Harald; Harrison, Michael; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Koop, Ivan; Lambiase, Robert; Litvinenko, Vladimir N; MacKay, William W; Mahler, George; Malitsky, Nikolay; McIntyre, Gary; Meng, Wuzheng; Merminga, Lia; Meshkov, Igor; Mirabella, Kerry; Montag, Christoph; Nagaitsev, Sergei; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Parkhomchuk, Vasily; Parzen, George; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Sekutowicz, Jacek; Shatunov, Yuri; Sidorin, Anatoly O; Skrinsky, Aleksander Nikolayevich; Smirnov, Alexander V; Smith, Kevin T; Todd, Alan M M; Trbojevic, Dejan; Troubnikov, Grigory; Wang, Gang; Wei, Jie; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Zaltsman, Alex; Zhao, Yongxiang; ain, Animesh K

    2005-01-01

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.ags...

  10. Dissociative Electron Attachment

    Science.gov (United States)

    Arreola, Esmeralda; Esmeralda Arreola Collaboration; Leigh Hargreaves Collaboration

    Since the pioneering work of Boudiaffa et al., it has been understood that electrons, even with energies near or below the ionization threshold, are capable of initiating strand-breaks in human DNA. This discovery raised important questions for cancer treatments, since sub-ionizing electrons are known to be the most copiously produced secondary product of radiation therapy. But even to date these factors are largely excluded from dosimetry calculations. This lack of inclusion is, at least in part, certainly due to the dearth of fundamental data describing low-energy electron interactions with nucleotide molecules that form the basis of DNA. Understanding of how such slow electrons are able to damage DNA remains incomplete, but the strongly peaked nature of Boudiaffa et al.'s data gives strong hints at resonantly driven collision processes. DNA damage is therefore most likely driven by ``dissociative electron attachment'' (DEA). DEA is a rather complicated process to model due to the coupling of electronic and nuclear degrees of freedom in the molecule. At the California State University Fullerton, we are currently commissioning a new spectrometer to study dissociation channels, reaction rates and orientation effects in DEA collisions between slow electrons and nucleotide molecules. At the meeting we will present design parameters and commissioning data for this new apparatus.

  11. Electron heat flux instability

    Science.gov (United States)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  12. Aerogels for electronics

    Energy Technology Data Exchange (ETDEWEB)

    Hrubesh, L.W.

    1994-10-01

    In addition to their other exceptional properties, aerogels also exhibit unusual dielectric and electronic properties due to their nano-sized structures and high porosities. For example, aerogels have the lowest dielectric constants measured for a solid material (having values approaching 1.0); they have exceptionally high dielectric resistivities and strengths (i.e., ability to insulate very high voltages); they exhibit low dielectric loss at microwave frequencies; and some aerogels are electrically conductive and photoconductive. These properties are being exploited to provide the next generation of materials for energy storage, low power consumption, and ultra-fast electronics. We are working toward adapting these unusual materials for microelectronic applications, particularly, making thin aerogel films for dielectric substrates and for energy storage devices such as supercapacitors. Measurements are presented in this paper for the dielectric and electronic properties of aerogels, including the dielectric constant, loss factor, dielectric and electrical conductivity, volume resistivity, and dielectric strength. We also describe methods to form and characterize thin aerogel films which are being developed for numerous electronic applications. Finally, some of the electronic applications proposed for aerogels are presented. Commercialization of aerogels for electronics must await further feasibility, prototype development, and cost studies, but they are one of the key materials and are sure to have a major impact on future electronics.

  13. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  14. Electronic devices and circuits

    CERN Document Server

    Pridham, Gordon John

    1968-01-01

    Electronic Devices and Circuits, Volume 1 deals with the design and applications of electronic devices and circuits such as passive components, diodes, triodes and transistors, rectification and power supplies, amplifying circuits, electronic instruments, and oscillators. These topics are supported with introductory network theory and physics. This volume is comprised of nine chapters and begins by explaining the operation of resistive, inductive, and capacitive elements in direct and alternating current circuits. The theory for some of the expressions quoted in later chapters is presented. Th

  15. Power Electronics for Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Blaabjerg, Frede

    2016-01-01

    A microgrid (MG) is a stand-alone or grid-connected hybrid renewable system that uses distributed renewable and nonrenewable energy sources and energy storage systems (ESSs) to supply power to local loads. The system is ordinarily based on power electronics, with interface converters allowing...... a continuous supply of power in the presence of variable RES production. This chapter describes some specific features of DC MGs in terms of power architecture, control, and protection. It also reviews several uncommon power electronic interfaces. Regarding control, operation without critical communication...... are explained in this chapter. The chapter concludes with a review of power electronic intensive protection solutions for DC MGs....

  16. Quantum electronics basic theory

    CERN Document Server

    Fain, V M; Sanders, J H

    1969-01-01

    Quantum Electronics, Volume 1: Basic Theory is a condensed and generalized description of the many research and rapid progress done on the subject. It is translated from the Russian language. The volume describes the basic theory of quantum electronics, and shows how the concepts and equations followed in quantum electronics arise from the basic principles of theoretical physics. The book then briefly discusses the interaction of an electromagnetic field with matter. The text also covers the quantum theory of relaxation process when a quantum system approaches an equilibrium state, and explai

  17. Electronic components and systems

    CERN Document Server

    Dennis, W H

    2013-01-01

    Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn

  18. Consulting in Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Florentina Loredana Tache

    2010-10-01

    Full Text Available Economic development of electronic services provide advice and many agents of existingreferral systems to recommend and provide products, information and customized views of thecommunity through a personalized interaction in real time. Distributed systems of autonomous agentsare becoming increasingly important in electronic comet because the basic decisions of agents adviceon trust and reputation are taken in a similar way human society. If these decisions will be as a realconsumer protection, when new aspects of online consumer legislation will become usefulinformation in advice and consulting of electronic commerce.

  19. Electron Beam Materials Irradiators

    Science.gov (United States)

    Cleland, Marshall R.

    2012-06-01

    Radiation processing is a well established method for enhancing the properties of materials and commercial products by treating them with ionizing energy in the form of high-energy electrons, X-rays, and gamma rays. Beneficial effects include polymerizing, cross-linking, grafting and degrading plastics, sterilizing single-use medical devices, disinfecting and disinfesting fresh foods, purifying drinking water, treating wastewater and other toxic waste materials that harm the environment, and many other applications that are still being evaluated. Industrial electron accelerators of several types have been developed and are being used for these applications. More than 1800 electron accelerators are presently installed in facilities worldwide for these purposes.

  20. Field emission electronics

    CERN Document Server

    Egorov, Nikolay

    2017-01-01

    This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.

  1. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B

    1972-01-01

    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  2. Principles of quantum electronics

    CERN Document Server

    Marcuse, Dietrich

    1980-01-01

    Principles of Quantum Electronics focuses on the concept of quantum electronics as the application of quantum theory to engineering problems. It examines the principles that govern specific quantum electronics devices and presents their theoretical applications to typical problems. Comprised of 10 chapters, this book starts with an overview of the Dirac formulation of quantum mechanics. This text then considers the derivation of the formalism of field quantization and discusses the properties of photons and phonons. Other chapters examine the interaction between the electromagnetic field and c

  3. VLSI electronics microstructure science

    CERN Document Server

    1982-01-01

    VLSI Electronics: Microstructure Science, Volume 4 reviews trends for the future of very large scale integration (VLSI) electronics and the scientific base that supports its development.This book discusses the silicon-on-insulator for VLSI and VHSIC, X-ray lithography, and transient response of electron transport in GaAs using the Monte Carlo method. The technology and manufacturing of high-density magnetic-bubble memories, metallic superlattices, challenge of education for VLSI, and impact of VLSI on medical signal processing are also elaborated. This text likewise covers the impact of VLSI t

  4. Coding for Electronic Mail

    Science.gov (United States)

    Rice, R. F.; Lee, J. J.

    1986-01-01

    Scheme for coding facsimile messages promises to reduce data transmission requirements to one-tenth current level. Coding scheme paves way for true electronic mail in which handwritten, typed, or printed messages or diagrams sent virtually instantaneously - between buildings or between continents. Scheme, called Universal System for Efficient Electronic Mail (USEEM), uses unsupervised character recognition and adaptive noiseless coding of text. Image quality of resulting delivered messages improved over messages transmitted by conventional coding. Coding scheme compatible with direct-entry electronic mail as well as facsimile reproduction. Text transmitted in this scheme automatically translated to word-processor form.

  5. TIS - Beyond Electronic Mail.

    Science.gov (United States)

    1979-01-01

    AD-AI06 764 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH F/G 17/2 TIS - BEYOND ELECTRONIC MAIL .(U) 1979 D L OLSON, N T FLYNN, M I DARWISH...79-22§1_ 4~~~~~~~ SIXi.m.aihl -- . TYPE OF REPORT & PERIOD covERED TIS -SBeyond Electronic Mail . TlSS~cnA~r 6 PEFRI4 O11G. REPORT NUMBER Duane L.A:o...single-service provisions of so-called " electronic mail ." Approaches to be used in implementing a TIS are considered, and a time-frame scenario is

  6. Electron paramagnetic resonance

    CERN Document Server

    Al'tshuler, S A

    2013-01-01

    Electron Paramagnetic Resonance is a comprehensive text on the field of electron paramagnetic resonance, covering both the theoretical background and the results of experiment. This book is composed of eight chapters that cover theoretical materials and experimental data on ionic crystals, since these are the materials that have been most extensively studied by the methods of paramagnetic resonance. The opening chapters provide an introduction to the basic principles of electron paramagnetic resonance and the methods of its measurement. The next chapters are devoted to the theory of spectra an

  7. Reliable Electronic Equipment

    Directory of Open Access Journals (Sweden)

    N. A. Nayak

    1960-05-01

    Full Text Available The reliability aspect of electronic equipment's is discussed. To obtain optimum results, close cooperation between the components engineer, the design engineer and the production engineer is suggested.

  8. The art of electronics

    CERN Document Server

    Horowitz, Paul

    2015-01-01

    At long last, here is the thoroughly revised and updated third edition of the hugely successful Art of Electronics. It is widely accepted as the best single authoritative book on electronic circuit design. In addition to new or enhanced coverage of many topics, the Third Edition includes: 90 oscilloscope screenshots illustrating the behavior of working circuits; dozens of graphs giving highly useful measured data of the sort that's often buried or omitted in datasheets but which you need when designing circuits; 80 tables (listing some 1650 active components), enabling intelligent choice of circuit components by listing essential characteristics (both specified and measured) of available parts. The new Art of Electronics ​​retains the feeling of informality and easy access that helped make the earlier editions so successful and popular. It is an indispensable reference and the gold standard​​ for anyone, student or researcher, professional or amateur, who works with electronic circuits.

  9. Electronic Universal Vote

    Directory of Open Access Journals (Sweden)

    Cristian USCATU

    2008-01-01

    Full Text Available In the days of informational society everything is going online. Most aspects of our lives have online components. Since democracy is a big issue, it could not escape this trend. Governments themselves are moving to the online environment for the purpose of improving their internal efficiency and their availability to the citizens, businesses and other parties interested. Since governments are the result of elections, elections have also been touched by the electronic fever. New electronic voting solutions arise and each one brings new debates with many arguments in their favor and against them. Accessibility and ease of use leads the arguments in favor of electronic voting over the internet, while fear of fraud is the main reason people are avoiding electronics and clinging on classic paper ballots.

  10. Electron gun for SSRF

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A 100 kV triode-electron-gun has been designed and manufactured for the Linac of Shanghai Synchrotron Radiation Facility (SSRF). In this paper the performance of the gun and some key components are described.

  11. Pulsed plasma electron sourcesa)

    Science.gov (United States)

    Krasik, Ya. E.; Yarmolich, D.; Gleizer, J. Z.; Vekselman, V.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J.

    2009-05-01

    There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E ≤105 V/cm and duration ≤10-5 s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

  12. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope. Specifications / Capabilities: Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  13. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  14. Telecommunications--Electronic Mail.

    Science.gov (United States)

    Kelly, Luke E.; Zuckerman, B. Michael

    1989-01-01

    This article identifies resources needed in order for physical education, recreation, and dance professionals to use computer-based telecommunications; discusses electronic mail; and explains how telecommunications can enhance communication in the field, both within and across professions. (IAH)

  15. Introduction to electron crystallography.

    Science.gov (United States)

    Kühlbrandt, Werner

    2013-01-01

    From the earliest work on regular arrays in negative stain, electron crystallography has contributed greatly to our understanding of the structure and function of biological macromolecules. The development of electron cryo-microscopy (cryo-EM) then lead to the first groundbreaking atomic models of the membrane proteins bacteriorhodopsin and light harvesting complex II within lipid bilayers. Key contributions towards cryo-EM and electron crystallography methods included specimen preparation and vitrification, liquid-helium cooling, data collection, and image processing. These methods are now applied almost routinely to both membrane and soluble proteins. Here we outline the advances and the breakthroughs that paved the way towards high-resolution structures by electron crystallography, both in terms of methods development and biological milestones.

  16. Electron and Photon ID

    CERN Document Server

    Hryn'ova, Tetiana; The ATLAS collaboration

    2017-01-01

    The identification of prompt photons and the rejection of background coming mostly from photons from hadron decays relies on the high granularity of the ATLAS calorimeter. The electron identification used in ATLAS for run 2 is based on a likelihood discrimination to separate isolated electron candidates from candidates originating from photon conversions, hadron misidentification and heavy flavor decays. In addition, isolation variables are used as further handles to separate signal and background. Several methods are used to measure with data the efficiency of the photon identification requirements, to cover a broad energy spectrum. At low energy, photons from radiative Z decays are used. In the medium energy range, similarities between electrons and photon showers are exploited using Z->ee decays. At high energy, inclusive photon samples are used. The measurement of the efficiencies of the electron identification and isolation cuts are performed with the data using tag and probe techniques with large statis...

  17. Electronics Modernization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Current electronic packaging designs used in our most recent spacecraft are comprised of technologies from the 1980’s and 1990’s. The current approach...

  18. Electronics for guitarists

    CERN Document Server

    Dailey, Denton J

    2014-01-01

    Electronics for Guitarists focuses on analog circuitry, and is written for the guitarist interested in transistor and vacuum tube-based amplifiers. Topics include discrete transistors and diodes, classical filter circuits, and vacuum tube-based amplifiers.

  19. ELECTRONIC BANKING AND ELECTRONIC COMMERCE IN SERBIA

    Directory of Open Access Journals (Sweden)

    Ivana B. Petrevska

    2014-10-01

    Full Text Available Nowadays, we may witness to dramatic and visible changes in our life environment. Business ambient for companies is different every day, and it is very hard to predict a direction of future changes. There is an environment characterized by sharp competition and increasing number of competitors, fast technological improvements and highly sophisticated and informed costumers. Technological process influences the humanity strongly, changing the way that people live, work and spend. Electronic commerce and electronic banking has become incontinent, and makes a great part of today's total transactions. There are an increasing number of companies that perform their business that way and make profit. Social networks are proven to be the least expensive way of information exchange, and they are present in almost every part of the world. The globalization has reached the most distant parts of the Earth. Every resistance to new technologies is dangerous and may lead to bankruptcy. Due to the EU expansion, Internet users are to be expected, and prosperity of the e-commerce business models at the same time. In Serbia, electronic commerce is present, but not as developed as in EU countries. E-commerce, however it might be successful throughout the world, it is somewhat slow in its growth in Serbia. The reasons are numerous, and main obstacles are the lack of trust, still limited usage of banking cards, avoiding of e-payments by older population etc. Also, the recent scandals over the misuse of personal data, and e-crime are discouraging factors for the growth of e-trade and ebanking. The younger generations are ever more ready to use e-commerce, since they are open to new technologies and do not have the defensive attitude towards it. E-commerce and e-banking has growing potential even among older population, if the society prevents them from fear and mistrust.

  20. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...... is considered as extruded profiles are inadequate for compact designs. An optimal pin fin shape and configuration is sought also taking manufacturing costs into consideration. Standard methods for geometrical modeling and thermal analysis are applied....

  1. Electronic states of myricetin

    DEFF Research Database (Denmark)

    Vojta, Danijela; Karlsen, Eva; Spanget-Larsen, Jens

    2017-01-01

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40000 – 20000 cm–1 were characterized with respect to their wavenumbers......, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p)....

  2. Newnes electronics assembly handbook

    CERN Document Server

    Brindley, Keith

    2013-01-01

    Newnes Electronics Assembly Handbook: Techniques, Standards and Quality Assurance focuses on the aspects of electronic assembling. The handbook first looks at the printed circuit board (PCB). Base materials, basic mechanical properties, cleaning of assemblies, design, and PCB manufacturing processes are then explained. The text also discusses surface mounted assemblies and packaging of electromechanical assemblies, as well as the soldering process. Requirements for the soldering process; solderability and protective coatings; cleaning of PCBs; and mass solder/component reflow soldering are des

  3. Electron Beam Ion Sources

    OpenAIRE

    Zschornacka, G.; Schmidt, M.; Thorn, A.

    2014-01-01

    Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviole...

  4. 4D Electron Tomography

    OpenAIRE

    Kwon, Oh-Hoon; Zewail, Ahmed H.

    2010-01-01

    Electron tomography provides three-dimensional (3D) imaging of noncrystalline and crystalline equilibrium structures, as well as elemental volume composition, of materials and biological specimens, including those of viruses and cells. We report the development of 4D electron tomography by integrating the fourth dimension (time resolution) with the 3D spatial resolution obtained from a complete tilt series of 2D projections of an object. The different time frames of tomograms constitute a mov...

  5. Mathematics for electronic technology

    CERN Document Server

    Howson, D P

    1975-01-01

    Mathematics for Electronic Technology is a nine-chapter book that begins with the elucidation of the introductory concepts related to use of mathematics in electronic engineering, including differentiation, integration, partial differentiation, infinite series, vectors, vector algebra, and surface, volume and line integrals. Subsequent chapters explore the determinants, differential equations, matrix analysis, complex variable, topography, graph theory, and numerical analysis used in this field. The use of Fourier method for harmonic analysis and the Laplace transform is also described. The ma

  6. Electron scattering experiments

    Science.gov (United States)

    Heisenberg, J.

    1984-11-01

    Because of the elementary structure of the electron, it is considered a precise probe of the constituent nature of hadronic matter. Use of the electron as a probe of subnucleonic degrees of freedom in nuclei is discussed in this presentation. Experimentally determined charge distributions for a wide variety of nuclei are presented and compared with shell model calculations which include single particle modes, core polarization, corrections due to delta-hole components, and corrections due to inclusion of meson exchange currents. (AIP)

  7. Electronic Portfolios for Scientists

    OpenAIRE

    Dahn, I.; Christmann, A.

    2007-01-01

    Electronic portfolios (ePortfolios) are electronic versions of paper based portfolios. They are increasingly applied in education. Software for building and maintaining ePortfolios is emerging; open specifications for the exchange of ePortfolios exist. They show the potential to serve as a standard tool for documenting achievements in lifelong learning. In this paper we explore the potential of ePortfolios for scientists.

  8. Electrical and electronic principles

    CERN Document Server

    Knight, SA

    1988-01-01

    Electrical and Electronic Principles, 3 focuses on the principles involved in electrical and electronic circuits, including impedance, inductance, capacitance, and resistance.The book first deals with circuit elements and theorems, D.C. transients, and the series circuits of alternating current. Discussions focus on inductance and resistance in series, resistance and capacitance in series, power factor, impedance, circuit magnification, equation of charge, discharge of a capacitor, transfer of power, and decibels and attenuation. The manuscript then examines the parallel circuits of alternatin

  9. The Recycler Electron Cooler

    Energy Technology Data Exchange (ETDEWEB)

    Shemyakin, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Prost, L. R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-03-19

    The Recycler Electron cooler was the first (and so far, the only) cooler working at a relativistic energy (γ = 9.5). It was successfully developed in 1995-2004 and was in operation at Fermilab in 2005-2011, providing cooling of antiprotons in the Recycler ring. This paper describes the cooler, difficulties in achieving the required electron beam parameters and the ways to overcome them, cooling measurements, and details of operation.

  10. Trust in Consumer Electronics

    Science.gov (United States)

    Kursawe, Klaus; Katzenbeisser, Stefan

    While Trusted Computing is getting increasing attention in the PC world, consumer electronics devices have limited benefit from the Trusted Computing solutions currently under development. In this paper we outline the different requirements of consumer electronics devices, when compared to the PC world, and point out the technical consequences for standards like the Trusted Computing Group. In addition, we will touch on economic aspects that may inhibit or support Trusted Computing in this domain.

  11. Electron spectroscopy analysis

    Science.gov (United States)

    Gregory, John C.

    1992-01-01

    The Surface Science Laboratories at the University of Alabama in Huntsville (UAH) are equipped with x-ray photoelectron spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES) facilities. These techniques provide information from the uppermost atomic layers of a sample, and are thus truly surface sensitive. XPS provides both elemental and chemical state information without restriction on the type of material that can be analyzed. The sample is placed into an ultra high vacuum (UHV) chamber and irradiated with x-rays which cause the ejection of photoelectrons from the sample surface. Since x-rays do not normally cause charging problems or beam damage, XPS is applicable to a wide range of samples including metals, polymers, catalysts, and fibers. AES uses a beam of high energy electrons as a surface probe. Following electronic rearrangements within excited atoms by this probe, Auger electrons characteristic of each element present are emitted from the sample. The main advantage of electron induced AES is that the electron beam can be focused down to a small diameter and localized analysis can be carried out. On the rastering of this beam synchronously with a video display using established scanning electron microscopy techniques, physical images and chemical distribution maps of the surface can be produced. Thus very small features, such as electronic circuit elements or corrosion pits in metals, can be investigated. Facilities are available on both XPS and AES instruments for depth-profiling of materials, using a beam of argon ions to sputter away consecutive layers of material to reveal sub-surface (and even semi-bulk) analyses.

  12. Newnes electronics toolkit

    CERN Document Server

    Phillips, Geoff

    2013-01-01

    Newnes Electronics Toolkit brings together fundamental facts, concepts, and applications of electronic components and circuits, and presents them in a clear, concise, and unambiguous format, to provide a reference book for engineers. The book contains 10 chapters that discuss the following concepts: resistors, capacitors, inductors, semiconductors, circuit concepts, electromagnetic compatibility, sound, light, heat, and connections. The engineer's job does not end when the circuit diagram is completed; the design for the manufacturing process is just as important if volume production is to be

  13. Electronic states of myricetin

    DEFF Research Database (Denmark)

    Vojta, Danijela; Karlsen, Eva; Spanget-Larsen, Jens

    2016-01-01

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40000 – 20000 cm–1 were characterized with respect to their wavenumbers......, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p)....

  14. Electronics 3 checkbook

    CERN Document Server

    Knight, S A; May, A J C

    2013-01-01

    Electronics 3 Checkbook provides a concise coverage of the theories and definitions of concepts in electronics. The book provides problems and worked examples to supplement fuller textbooks of the same subject. The coverage of the text includes decibel measurement, operational amplifiers, DA and AD converters, controlled rectifiers, triggering devices, optoelectronic devices, fiber optics, and power amplifiers. The text will be of great use to electrical engineering students who wish to enhance their understanding of the basics of mechanical and electrical science.

  15. Electron Transfer Pathways in Cell

    OpenAIRE

    Yan Liu

    2012-01-01

    Analysis of the electron salvation process data indicates that the electron transfer between the electron donor and acceptor is hindered by the electron salvation process. It is proposed that the electron transfer in the cell environment must be assisted by intermediate messenger called the “transport protein”.

  16. Thermionics basic principles of electronics

    CERN Document Server

    Jenkins, J; Ashhurst, W

    2013-01-01

    Basic Principles of Electronics, Volume I : Thermionics serves as a textbook for students in physics. It focuses on thermionic devices. The book covers topics on electron dynamics, electron emission, and the themionic vacuum diode and triode. Power amplifiers, oscillators, and electronic measuring equipment are studied as well. The text will be of great use to physics and electronics students, and inventors.

  17. Netiquette in Electronic Communication

    Directory of Open Access Journals (Sweden)

    Tomáš Kozík

    2014-06-01

    Full Text Available Electronic mail and electronic communications systems are considered significant and effective tools of communication. One of the most widespread electronic communication tools is e - mail communication. In order to avoid misinterpretation of the report on the side of the recipient, it is need to pay attention to the writing of e - mail messages as well as to their content. With the continuous expansion of the use of electronic communication there have gradually developed certain rules of etiquette in electronic communications. The existing rules of the propriety ones are expressed in the term " etiqutte " and are not automatically applied in the new communications environment - media. For electronic communication, the new rules of etiquette have been stabilised into a term NETIQUETTE. The word netiquette was created by combining words NET (net and ETIKETA (a set of rules of social behavior and habits. Netiquette constitutes the rules of the behavior of users on a network. Although the netiquette is merely "an unwritten set of rules", their not using can be understood as a type of disrespect. Analysis of knowledge of domestic and foreign sources as well as results of a survey confirmed the justification of paying attention to the education of individuals in NETIQUETTE, irrespective of the degree of education.

  18. BOK-Printed Electronics

    Science.gov (United States)

    Ghaffarian, Reza

    2013-01-01

    The use of printed electronics technologies (PETs), 2D or 3D printing approaches either by conventional electronic fabrication or by rapid graphic printing of organic or nonorganic electronic devices on various small or large rigid or flexible substrates, is projected to grow exponentially in commercial industry. This has provided an opportunity to determine whether or not PETs could be applicable for low volume and high-reliability applications. This report presents a summary of literature surveyed and provides a body of knowledge (BOK) gathered on the current status of organic and printed electronics technologies. It reviews three key industry roadmaps- on this subject-OE-A, ITRS, and iNEMI-each with a different name identification for this emerging technology. This followed by a brief review of the status of the industry on standard development for this technology, including IEEE and IPC specifications. The report concludes with key technologies and applications and provides a technology hierarchy similar to those of conventional microelectronics for electronics packaging. Understanding key technology roadmaps, parameters, and applications is important when judicially selecting and narrowing the follow-up of new and emerging applicable technologies for evaluation, as well as the low risk insertion of organic, large area, and printed electronics.

  19. Good Security Practices for Electronic Commerce, Including Electronic Data Interchange

    Science.gov (United States)

    1993-12-01

    FROM - TO) xx-xx-2002 to xx-xx-2002 4. TITLE AND SUBTITLE Good Security Practices for Electronic Commerce , Including Electronic Data Interchange...Report 12/1/1993 4. TITLE AND SUBTITLE Good Security Practices for Electronic Commerce , Including Electronic Data Interchange 5. FUNDING NUMBERS 6...Maximum 200 Words) Electronic commerce (EC) is the use of documents in electronic form, rather than paper, for carrying out functions of business or

  20. Electron holes in inhomogeneous magnetic field: electron heating and electron hole evolution

    Science.gov (United States)

    Vasko, Ivan; Agapitov, Oleksiy; Mozer, Forrest; Artemyev, Anton; Drake, James

    2016-04-01

    Electron holes are electrostatic non-linear structures widely observed in the space plasma, e.g., in reconnecting current sheets, collisionless bow shocks, Earth auroral region and outer radiation belt etc. In the present paper we analyze the process of energy exchange between trapped electrons, untrapped electrons and electron hole propagating in weakly inhomogeneous magnetic field. We show that as electron hole propagates into the region with stronger magnetic field, trapped electrons are heated due to conservation of the first adiabatic invariant. At the same time electron hole may grow or dissipate in dependence on peculiarities of distribution functions of trapped and resonant untrapped electrons. The energy gain of trapped electrons is due to energy losses of resonant electrons and/or decrease of electron hole energy (electrostatic energy and kinetic energy of non-resonant electrons). We stress that taking into account the energy exchange with resonant untrapped electrons increases the heating factor of trapped electrons that is proportional to the magnetic field magnitude in the region up to what electron holes survive. We illustrate the suggested mechanism for H. Schamel's electron holes and show that during propagation along a positive magnetic field gradient their amplitude should grow. Neglect of energy exchange with resonant untrapped electrons would result electron hole dissipation with only modest heating factor of trapped electrons. We argue that the suggested mechanism may be responsible for generation of energetic electrons in the space plasma.