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Sample records for conditions influence bioavailability

  1. Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Different Enrichment Conditions Influence Bioavailability and Selection of Phenanthrene-Degrading Isolates

    PubMed Central

    Grosser, Robert J.; Friedrich, Michael; Ward, David M.; Inskeep, William P.

    2000-01-01

    The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments. We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions. Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms. Phenanthrene sorption coefficients (expressed as log KD values) ranged from 3.0 liters kg−1 for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg−1 for Biobeads polyacrylic resin (SM7) and 4.2 liters kg−1 for Biobeads divinyl benzene resin (SM2). Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula. The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum. Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 μmol day−1 for control and sand treatments to approximately 0.4 μmol day−1 in the presence of the SM7 sorptive phase. The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained. Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different

  2. [Bioavailability and factors influencing its rate].

    PubMed

    Vraníková, Barbora; Gajdziok, Jan

    2015-01-01

    Bioavailability can be defined as the rate and range of active ingredient absorption, when it becomes available in the systemic circulation or at the desired site of drug action, respectively. Drug bioavailability after oral administration is affected by anumber of different factors, including physicochemical properties of the drug, physiological aspects, the type of dosage form, food intake, biorhythms, and intra- and interindividual variability of the human population. This article is the first from the series dealing with the bioavailability and methods leading to its improvement. The aim of the present paper is to provide an overview of aspects influencing the rate of bioavailability after oral administration of the active ingredient. Subsequentarticles will provide detailed descriptions of methods used for dug bioavailability improvement, which are here only summarized.

  3. Factors influencing micronutrient bioavailability in biofortified crops.

    PubMed

    Bechoff, Aurélie; Dhuique-Mayer, Claudie

    2017-02-01

    Dietary and human factors have been found to be the major factors influencing the bioavailability of micronutrients, such as provitamin A carotenoid (pVAC), iron, and zinc, in biofortified crops. Dietary factors are related to food matrix structure and composition. Processing can improve pVAC bioavailability by disrupting the food matrix but can also result in carotenoid losses. By degrading antinutrients, such as phytate, processing can also enhance mineral bioavailability. In in vivo interventions, biofortified crops have been shown to be overall efficacious in reducing micronutrient deficiency, with bioconversion factors varying between 2.3:1 and 10.4:1 for trans-β-carotene and amounts of iron and zinc absorbed varying between 0.7 and 1.1 mg/day and 1.1 and 2.1 mg/day, respectively. Micronutrient bioavailability was dependent on the crop type and the presence of fat for pVACs and on antinutrients for minerals. In addition to dietary factors, human factors, such as inflammation and disease, can affect micronutrient status. Understanding the interactions between micronutrients is also essential, for example, the synergic effect of iron and pVACs or the competitive effect of iron and zinc. Future efficacy trials should consider human status and genetic polymorphisms linked to interindividual variations.

  4. Influence of carbon nanotubes on the bioavailability of fluoranthene.

    PubMed

    Linard, Erica N; van den Hurk, Peter; Karanfil, Tanju; Apul, Onur G; Klaine, Stephen J

    2015-03-01

    Concurrent with the increase in the use of carbon nanotubes (CNTs) in society is the rise of their introduction into the environment. Carbon nanotubes cause adverse effects themselves, and they have the potential to adsorb contaminants such as polycyclic aromatic hydrocarbons (PAHs). Although CNTs have a high adsorption capacity for PAHs and these contaminants can co-occur in the environment, few studies have characterized the bioavailability of CNT-adsorbed PAHs to fish. The goal of the present study was to characterize the bioavailability of fluoranthene adsorbed to suspended multiwalled-carbon nanotubes (MWNTs) in freshwater containing natural organic matter (NOM). Adsorption isotherms indicated that NOM influenced the adsorption of fluoranthene to MWNTs, although in the absence of MWNTs it did not influence the bioavailability of fluoranthene to Pimephales promelas. Pimephales promelas were exposed for 16 h in synthetic moderately hard water containing fluoranthene in the presence of different concentrations of NOM, and fluoranthene adsorbed to MWNTs in the presence of NOM. Bioavailable fluoranthene was quantified in each exposure through bile analysis using fluorescence spectrophotometry. By comparing the concentration of fluoranthene metabolites in the bile with the concentration of fluoranthene added to MWNT and NOM solutions, the relative bioavailability of fluoranthene adsorbed to MWNTs was quantified. Results indicate that approximately 60% to 90% of the fluoranthene was adsorbed to the MWNTs and that adsorbed fluoranthene was not bioavailable to P. promelas. The results also suggest that fluoranthene is not desorbed from ingested MWNT, and the bioavailable fraction is only the freely dissolved fluoranthene in the aqueous phase.

  5. Influence of biochar amendments on marine sediment trace metal bioavailability

    NASA Astrophysics Data System (ADS)

    Gehrke, G. E.; Hsu-Kim, H.

    2014-12-01

    Biochar has become a desirable material for use in agricultural application to enhance soil quality and in-situ soil and sediment remediation to immobilize organic contaminants. We investigated the effects of biochar sediment amendments on the bioavailability of a suite of inorganic trace metals (Cr, Co, Ni, Cu, Zn, Pb) in contaminated sediments from multiple sites in Elizabeth River, VA. We incubated sediments in microcosms with a variety of water column redox and salinity conditions and compared sediments amended with two types of woody biochar to sediments amended with charcoal activated carbon and unamended sediments. We leached sediments in artificial gut fluid mimic of the benthic invertebrate Arenicola marina as a measure of bioavailability of the trace metals analyzed. In unamended anaerobic sediments, the gut fluid mimic leachable fraction of each trace metal is 1-4% of the total sediment concentration for each metal. Initial results indicate that in anaerobic microcosms, woody biochar sediment amendments (added to 5% dry wt) decrease the gut fluid mimic leachable fraction by 30-90% for all trace metals analyzed, and have comparable performance to charcoal activated carbon amendments. However, in microcosms without controlled redox conditions, woody biochar amendments increase the bioavailable fraction of Ni and Cu by up to 80%, while decreasing the bioavailable fraction of Co, Zn, and Pb by approximately 50%; charcoal activated carbon amendments decreased the bioavailability of all trace metals analyzed by approximately 20%. In microcosms without an overlying water column, biochar and activated carbon amendments had no significant effects on trace metal bioavailability. This research demonstrates that biochar can effectively decrease the bioavailability of trace metals in marine sediments, but its efficiency is metal-specific, and environmental conditions impact biochar performance.

  6. Influence of sorption/desorption processes on the bioavailability of organic contaminants

    SciTech Connect

    Guerin, W.F.; Boyd, S.A.

    1990-01-01

    Many of the problem contaminants found in soils and groundwaters are non-ionic and relatively insoluble. Under appropriate conditions, many of these compounds are degradable by bacteria provided nutrients, electron acceptors and the compounds themselves are biologically available. However, non-ionic organic compounds (NOCs) bind tenaciously to soil particles potentially limiting their bioavailability. While the individual processes of sorption and biodegradation have received much attention in recent years, little is known about the interactions of these processes. The primary objective of our DOE-funded research project has been to elucidate the influences of sorption and desorption processes on the bioavailability of NOCs. Conflicting reports in the literature suggest that sorption may increase, decrease, or have no effect on bioavailability although the majority of published work has studied proteins, fatty acids, and other normal bacterial growth substrates as sorbates. Some of this variability arises because sorbed solutes interact with sorbents via different mechanisms including cation and anion exchange, adsorption, complexation with surface-associated metals and partitioning. Also, bacterial activities may be altered upon attachment of the cells to the sorbent surface. Clearly, resolution of this problem requires detailed knowledge of a system with multiple components. We are, therefore, approaching this problem on a fundamental level. 20 refs., 16 figs., 2 tabs.

  7. Assessment of metals bioavailability to vegetables under field conditions using DGT, single extractions and multivariate statistics

    PubMed Central

    2012-01-01

    Background The metals bioavailability in soils is commonly assessed by chemical extractions; however a generally accepted method is not yet established. In this study, the effectiveness of Diffusive Gradients in Thin-films (DGT) technique and single extractions in the assessment of metals bioaccumulation in vegetables, and the influence of soil parameters on phytoavailability were evaluated using multivariate statistics. Soil and plants grown in vegetable gardens from mining-affected rural areas, NW Romania, were collected and analysed. Results Pseudo-total metal content of Cu, Zn and Cd in soil ranged between 17.3-146 mg kg-1, 141–833 mg kg-1 and 0.15-2.05 mg kg-1, respectively, showing enriched contents of these elements. High degrees of metals extractability in 1M HCl and even in 1M NH4Cl were observed. Despite the relatively high total metal concentrations in soil, those found in vegetables were comparable to values typically reported for agricultural crops, probably due to the low concentrations of metals in soil solution (Csoln) and low effective concentrations (CE), assessed by DGT technique. Among the analysed vegetables, the highest metal concentrations were found in carrots roots. By applying multivariate statistics, it was found that CE, Csoln and extraction in 1M NH4Cl, were better predictors for metals bioavailability than the acid extractions applied in this study. Copper transfer to vegetables was strongly influenced by soil organic carbon (OC) and cation exchange capacity (CEC), while pH had a higher influence on Cd transfer from soil to plants. Conclusions The results showed that DGT can be used for general evaluation of the risks associated to soil contamination with Cu, Zn and Cd in field conditions. Although quantitative information on metals transfer from soil to vegetables was not observed. PMID:23079133

  8. Influence of mature compost amendment on total and bioavailable polycyclic aromatic hydrocarbons in contaminated soils.

    PubMed

    Wu, Guozhong; Kechavarzi, Cedric; Li, Xingang; Sui, Hong; Pollard, Simon J T; Coulon, Frédéric

    2013-02-01

    A laboratory microcosm study was carried out to assess the influence of compost amendment on the degradation and bioavailability of PAHs in contaminated soils. Three soils, contaminated with diesel, coal ash and coal tar, respectively, were amended with two composts made from contrasting feedstock (green waste and predominantly meat waste) at two different rates (250 and 750 t ha(-1)) and incubated for 8 months. During this period the treatments were sampled for PAH analysis after 0, 3, 6 and 8 months. Total and bioavailable fractions were obtained by sequential ultrasonic solvent extraction and hydroxypropyl-β-cyclodextrin extraction, respectively, and PAHs were identified and quantified by GC-MS. Bioavailability decrease due to sorption was only observed at the first 3 months in the diesel spiked soil. After 8 months, compost addition resulted in over 90% loss of total PAHs irrespective of soil types. Desorption and degradation contributed to 30% and 70%, respectively, of the PAH loss in the spiked soil, while PAH loss in the other two soils resulted from 40% enhanced desorption and 60% enhanced degradation. Compost type and application rates had little influence on PAH bioavailability, but higher PAH removal was observed at higher initial concentration during the early stage of incubation. The bioavailable fraction of PAH was inversely correlated to the number of benzene rings and the octanol-water partition coefficient. Further degradation was not likely after 8-month although over 30% of the residual PAHs were bioavailable, which highlighted the application of bioavailability concept during remediation activities.

  9. Recycled water sources influence the bioavailability of copper to earthworms.

    PubMed

    Kunhikrishnan, Anitha; Bolan, Nanthi S; Naidu, Ravi; Kim, Won-Il

    2013-10-15

    Re-use of wastewaters can overcome shortfalls in irrigation demand and mitigate environmental pollution. However, in an untreated or partially treated state, these water sources can introduce inorganic contaminants, including heavy metals, to soils that are irrigated. In this study, earthworms (Eisenia fetida) have been used to determine copper (Cu) bioavailability in two contrasting soils irrigated with farm dairy, piggery and winery effluents. Soils spiked with varying levels of Cu (0-1,000 mg/kg) were subsequently irrigated with recycled waters and Milli-Q (MQ) water and Cu bioavailability to earthworms determined by mortality and avoidance tests. Earthworms clearly avoided high Cu soils and the effect was more pronounced in the absence than presence of recycled water irrigation. At the highest Cu concentration (1,000 mg/kg), worm mortality was 100% when irrigated with MQ-water; however, when irrigated with recycled waters, mortality decreased by 30%. Accumulation of Cu in earthworms was significantly less in the presence of recycled water and was dependent on CaCl2-extractable free Cu(2+) concentration in the soil. Here, it is evident that organic carbon in recycled waters was effective in decreasing the toxic effects of Cu on earthworms, indicating that the metal-organic complexes decreased Cu bioavailability to earthworms.

  10. [Influence of Dissimilatory Iron Reduction on the Speciation and Bioavailability of Heavy Metals in Soil].

    PubMed

    Si, You-bin; Wang, Juan

    2015-09-01

    Fe(III) dissimilatory reduction by microbes is an important process of producing energy in the oxidation of organic compounds under anaerobic condition with Fe(III) as the terminal electron acceptor and Fe(II) as the reduction product. This process is of great significance in element biogeochemical cycle. Iron respiration has been described as one of the most ancient forms of microbial metabolism on the earth, which is bound up with material cycle in water, soil and sediments. Dissimilatory iron reduction plays important roles in heavy metal form transformation and the remediation of heavy metal and radionuclide contaminated soils. In this paper, we summarized the research progress of iron reduction in the natural environment, and discussed the influence and the mechanism of dissimilatory iron reduction on the speciation and bioavailability of heavy metals in soil. The effects of dissimilatory iron reduction on the speciation of heavy metals may be attributed to oxidation and reduction, methytation and immobilization of heavy metals in relation to their bioavailability in soils. The mechanisms of Fe(III) dissimilatory reduction on heavy metal form transformation contain biological and chemical interactions, but the mode of interaction remains to be further investigated.

  11. Influence of estuarine processes on spatiotemporal variation in bioavailable selenium

    USGS Publications Warehouse

    Stewart, Robin; Luoma, Samuel N.; Elrick, Kent A.; Carter, James L.; van der Wegen, Mick

    2013-01-01

    Dynamic processes (physical, chemical and biological) challenge our ability to quantify and manage the ecological risk of chemical contaminants in estuarine environments. Selenium (Se) bioavailability (defined by bioaccumulation), stable isotopes and molar carbon-tonitrogen ratios in the benthic clam Potamocorbula amurensis, an important food source for predators, were determined monthly for 17 yr in northern San Francisco Bay. Se concentrations in the clams ranged from a low of 2 to a high of 22 μg g-1 over space and time. Little of that variability was stochastic, however. Statistical analyses and preliminary hydrodynamic modeling showed that a constant mid-estuarine input of Se, which was dispersed up- and down-estuary by tidal currents, explained the general spatial patterns in accumulated Se among stations. Regression of Se bioavailability against river inflows suggested that processes driven by inflows were the primary driver of seasonal variability. River inflow also appeared to explain interannual variability but within the range of Se enrichment established at each station by source inputs. Evaluation of risks from Se contamination in estuaries requires the consideration of spatial and temporal variability on multiple scales and of the processes that drive that variability.

  12. How contamination sources and soil properties can influence the Cd and Pb bioavailability to snails.

    PubMed

    Pauget, Benjamin; Gimbert, Frédéric; Coeurdassier, Mickael; Druart, Coline; Crini, Nadia; de Vaufleury, Annette

    2016-02-01

    To better understand the fate of metals in the environment, numerous parameters must be studied, such as the soil properties and the different sources of contamination for the organisms. Among bioindicators of soil quality, the garden snail (Cantareus aspersus) integrates multiple sources (e.g. soil, plant) and routes (e.g. digestive, cutaneous) of contamination. However, the contribution of each source on metal bioavailability and how soil properties influence these contributions have never been studied when considering the dynamic process of bioavailability. Using accumulation kinetics, this study showed that the main assimilation source of Cd was lettuce (68%), whereas the main source of Pb was the soil (90%). The plant contribution increased in response to a 2-unit soil pH decrease. Unexpectedly, an increase in the soil contribution to metal assimilation accompanied an increase in the organic matter (OM) content of the soil. For both metals, no significant excretion and influence of source on excretion have been modelled either during exposure or depuration. This study highlights how the contribution of different sources to metal bioavailability changes based on changes in soil parameters, such as pH and OM, and the complexity of the processes that modulate metal bioavailability.

  13. Influence of organic matter transformations on the bioavailability of heavy metals in a sludge based compost.

    PubMed

    Ingelmo, Florencio; Molina, Maria José; Soriano, Maria Desamparados; Gallardo, Antonio; Lapeña, Leonor

    2012-03-01

    The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. This depends not only on the initial characteristics of the composted substrates but also on the organic matter transformations during composting which may influence the chemical form of the metals and their bioavailability. The objective of this work was to examine the relationships between the changes in the organic matter content and humus fractions, and the bioavailability of heavy metals. A detailed sampling at 0, 14, 84, and 140 days of the composting process was performed to measure C contents in humic acids (HAs), fulvic acids, (FAs) and humin, the total content of Zn, Pb, Cu, Ni, and Cd, and also their distribution into mobile and mobilisable (MB), and low bioavailability (LB) forms. Significant changes of C contents in HA, FA, and Humin, and in the FA/HA, HA/Humin and C(humus)/TOC ratios were observed during composting. The MB and LB fractions of each metal also varied significantly during composting. The MB fraction increased for Zn, Cu, Ni, and Cd, and the LB fraction increased for Pb. Stepwise linear regressions and quadratic curve estimation conducted on the MB and LB fractions of each metal as dependent on the measured organic variables suggested that Zn bioavailability was mainly associated to percentage of C in FAs. Bioavailability of Cu, Ni and Cd during composting was associated to humin and HAs. Pb concentration increased in the LB form, and its variations followed a quadratic function with the C(humus)/TOC ratio. Our results suggest that the composting process renders the metals in more available forms. The main forms of metal binding in the sludge and their availability in the final compost may be better described when metal fractionation obtained in sequential extraction and humus fractionation during composting are considered together.

  14. The Influence of Extracellular Superoxide on Iron Redox Chemistry and Bioavailability to Aquatic Microorganisms

    PubMed Central

    Rose, Andrew L.

    2012-01-01

    Superoxide, the one-electron reduced form of dioxygen, is produced in the extracellular milieu of aquatic microbes through a range of abiotic chemical processes and also by microbes themselves. Due to its ability to promote both oxidative and reductive reactions, superoxide may have a profound impact on the redox state of iron, potentially influencing iron solubility, complex speciation, and bioavailability. The interplay between iron, superoxide, and oxygen may also produce a cascade of other highly reactive transients in oxygenated natural waters. For microbes, the overall effect of reactions between superoxide and iron may be deleterious or beneficial, depending on the organism and its chemical environment. Here I critically discuss recent advances in understanding: (i) sources of extracellular superoxide in natural waters, with a particular emphasis on microbial generation; (ii) the chemistry of reactions between superoxide and iron; and (iii) the influence of these processes on iron bioavailability and microbial iron nutrition. PMID:22514548

  15. Abiotic and biotic factors that influence the bioavailability of gold nanoparticles to aquatic macrophytes.

    PubMed

    Glenn, J Brad; Klaine, Stephen J

    2013-09-17

    This research identified and characterized factors that influenced nanomaterial bioavailability to three aquatic plants: Azolla caroliniana Willd, Egeria densa Planch., and Myriophyllum simulans Orch. Plants were exposed to 4-, 18-, and 30-nm gold nanoparticles. Uptake was influenced by nanoparticle size, the presence of roots on the plant, and dissolved organic carbon in the media. Statistical analysis of the data also revealed that particle uptake was influenced by a 4-way (plant species, plant roots, particle size, and dissolved organic carbon) interaction suggesting nanoparticle bioavailability was a complex result of multiple parameters. Size and species dependent absorption was observed that was dependent on the presence of roots and nanoparticle size. The presence of dissolved organic carbon was found to associate with 4- and 18-nm gold nanoparticles in suspension and form a nanoparticle/organic matter complex that resulted in (1) minimized particle aggregation and (2) a decrease of nanoparticle absorption by the aquatic plants. The same effect was not observed with the 30-nm nanoparticle treatment. These results indicate that multiple factors, both biotic and abiotic, must be taken into account when predicting bioavailability of nanomaterials to aquatic plants.

  16. Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2016-04-01

    The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates.

  17. Influence of eutrophication on metal bioaccumulation and oral bioavailability in oysters, Crassostrea angulata.

    PubMed

    Li, Shun-Xing; Chen, Li-Hui; Zheng, Feng-Ying; Huang, Xu-Guang

    2014-07-23

    Oysters (Crassostrea angulata) are often exposed to eutrophication. However, how these exposures influence metal bioaccumulation and oral bioavailability (OBA) in oysters is unknown. After a four month field experimental cultivation, bioaccumulation factors (BAF) of metals (Fe, Cu, As, Cd, and Pb) from seawater to oysters and metal oral bioavailability in oysters by bionic gastrointestinal tract were determined. A positive effect of macronutrient (nitrate N and total P) concentration in seawater on BAF of Cd in oysters was observed, but such an effect was not significant for Fe, Cu, Pb, and As. Only OBA of As was significantly positively correlated to N and P contents. For Fe, OBA was negatively correlated with N. The regular variation of the OBA of Fe and As may be due to the effect of eutrophication on the synthesis of metal granules and heat-stable protein in oysters, respectively.

  18. Influence of the presence of ethanol on in vitro bioavailability of fungicide residues.

    PubMed

    Cermeño, S; Martínez, G; Oliva, J; Cámara, M A; Barba, A

    2016-07-01

    The influence of ethanol on the in vitro bioavailability of nine fungicides in wines of varying degrees of alcohol is studied by simulating the digestive process by dialysis in semipermeable membranes. The dose of each fungicide corresponds to its added Maximum Residue Limits in the different matrices (water, ethanol, wines of 7, 11, 13 and 14.5% ethanol). A validated analytical methodology was used which includes extraction, partition according to the modified QuEChERS multiresidue method and liquid chromatography with triple quadrupole tandem mass spectrometry analysis. Interaction between the ethanol content and bioavailability was confirmed and increases were found in the dialyzed percentages with respect to the blank (the standard in water) for ametoctradin, mepanipyrim, cyazofamid, pyraclostrobin and metrafenone, while a decrease was observed for dimethomorph, boscalid and kresoxim-methyl. Fenhexamid showed no significant differences by alcohol content.

  19. Effect of zinc on copper and iron bioavailability as influenced by dietary copper and fat source

    SciTech Connect

    Magee, A.C.; Jones, B.P.; Lin, F.; Sinthusek, G.; Frimpong, N.A.; Wu, S.

    1986-03-05

    In a number of experiments, they have observed that liver copper levels of young male rats fed low zinc diets were essentially the same as liver copper levels of rats fed adequate zinc. Liver iron levels of rats fed low zinc diets, however, tended to be markedly higher than liver iron levels of rats fed adequate zinc. Increases in dietary zinc (up to 200 ppm) were generally associated with decreases in liver iron deposition, but had little effect on liver copper deposition. Iron bioavailability appeared to be enhanced when fat sources high in saturated fatty acids were used, and there was evidence that the type of dietary fat influenced the effect of zinc on iron bioavailability. Liver copper deposition, however, did not appear to be markedly affected by the type of dietary fat suggesting that copper bioavailability is less affected by fat source. Increases in dietary copper were associated with increases in liver copper levels and decreases in liver iron levels of rats fed increasing levels of zinc. These data suggest that potential interrelationships between dietary factors not being considered as experimental variables could have significant effects on results and on the interrelationships between dietary variables which are being studied.

  20. Influence of natural dissolved organic carbon on the bioavailability of mercury to a freshwater alga

    USGS Publications Warehouse

    Gorski, P.R.; Armstrong, D.E.; Hurley, J.P.; Krabbenhoft, D.P.

    2008-01-01

    Bioavailability of mercury (Hg) to Selenastrum capricornutum was assessed in bioassays containing field-collected freshwater of varying dissolved organic carbon (DOC) concentrations. Bioconcentration factor (BCF) was measured using stable isotopes of methylmercury (MeHg) and inorganic Hg(II). BCFs for MeHg in low-DOC lake water were significantly larger than those in mixtures of lake water and high-DOC river water. The BCF for MeHg in rainwater (lowest DOC) was the largest of any treatment. Rainwater and lake water also had larger BCFs for Hg(II) than river water. Moreover, in freshwater collected from several US and Canadian field sites, BCFs for Hg(II) and MeHg were low when DOC concentrations were >5 mg L-1. These results suggest high concentrations of DOC inhibit bioavailability, while low concentrations may provide optimal conditions for algal uptake of Hg. However, variability of BCFs at low DOC indicates that DOC composition or other ligands may determine site-specific bioavailability of Hg.

  1. Influence of dispersants on petroleum bioavailability to primary producers in a brackish water food chain

    SciTech Connect

    Younghans-Haug, C.O.; Wolfe, M.F.; Tjeerdema, R.S.; Sowby, M.L.

    1994-12-31

    Petroleum is transported and processed within biologically rich brackish environments worldwide. Past research has investigated disposition of chemically dispersed oil in mammals, fish, and higher invertebrates, yet little is known about how chemical dispersion influences petroleum behavior within primary producers within brackish water food chains. One concern is whether chemical dispersion influences petroleum bioavailability to primary producers and the potential for increased petroleum bioaccumulation. This research examines changes in petroleum bioavailability to the euryhaline phytoplankton Isochrysis galbana by measuring bioconcentration factors (BCFS) including uptake and deputation rates for dispersed and undispersed brackish water oil spills. Isochrysis is a major food source for zooplankton which are consumed by a multitude of larval fish having both ecological and commercial importance. Prudhoe Bay Crude oil, Corexit 9527, and {sup 14}C-naphthalene were used for these studies. Constant-concentration flow-through exposures were employed for the uptake and BCF experiments. Work was performed below the ``no observable effect concentration`` to eliminate stress-induced metabolic altercations that could in themselves influence petroleum behavior. Exposure chamber and experimental design will be discussed, and study results presented. Understanding how chemical dispersion alters petroleum behavior within the lowest levels of the food chain leads to better delineation of consumer risks.

  2. Resolving the physiological conditions in bioavailability and bioequivalence studies: Comparison of fasted and fed state.

    PubMed

    Schneider, Felix; Grimm, Michael; Koziolek, Mirko; Modeß, Christiane; Dokter, Anne; Roustom, Tarek; Siegmund, Werner; Weitschies, Werner

    2016-11-01

    In the present study temperature, pH and pressure profiles of nine healthy human volunteers were investigated after ingestion of the SmartPill® under conditions simulating the fasted state treatment in bioavailability and bioequivalence studies. In a previously published study the same subjects received the SmartPill® under fed conditions as recommended by the FDA. Since large non-digestible objects are mainly emptied during phase III of the interdigestive migrating motor complex, the gastric residence time of the SmartPill® was found to be clearly shorter under fasting conditions. Intragastric pH values during the initial 5min were similar with an identical median value of pH 4.6. Interestingly, the median lowest observed intragastric pH value in fasted state was about one pH unit higher than that under fed conditions. Highest pressure activity was observed within the stomach, in relation to gastric emptying. In fasted state, pressure values upon gastric emptying varied strongly between 30mbar and 304mbar, whereas after fed state ingestion values of at least 240mbar could always be observed. The data showed highly variable gastrointestinal parameters even under fasting conditions which must be considered when evaluating clinical studies and developing biorelevant in vitro test methods especially for large non-disintegrating dosage forms.

  3. Carbon Nanotube Properties Influence Adsorption of Phenanthrene and Subsequent Bioavailability and Toxicity to Pseudokirchneriella subcapitata.

    PubMed

    Glomstad, Berit; Altin, Dag; Sørensen, Lisbet; Liu, Jingfu; Jenssen, Bjørn M; Booth, Andy M

    2016-03-01

    The bioavailability of organic contaminants adsorbed to carbon nanotubes (CNTs) remains unclear, especially in complex natural freshwaters containing natural organic matter (NOM). Here, we report on the adsorption capacity (Q(0)) of five CNTs exhibiting different physicochemical properties, including a single-walled CNT (SWCNTs), multiwalled CNTs (MWCNT-15 and MWCNT-30), and functionalized MWCNTs (hydroxyl, -OH, and carboxyl, -COOH), for the model polycyclic aromatic hydrocarbon phenanthrene (3.1-800 μg/L). The influence of phenanthrene adsorption by the CNTs on bioavailability and toxicity was investigated using the freshwater algae Pseudokirchneriella subcapitata. CNTs were dispersed in algal growth media containing NOM (DOC, 8.77 mg/L; dispersed concentrations: 0.5, 1.3, 1.3, 3.3, and 6.1 mg/L for SWCNT, MWCNT-15, MWCNT-30, MWCNT-OH, and MWCNT-COOH, respectively). Adsorption isotherms of phenanthrene to the dispersed CNTs were fitted with the Dubinin-Ashtakhov model. Q(0) differed among the CNTs, increasing with increasing surface area and decreasing with surface functionalization. SWCNT and MWCNT-COOH exhibited the highest and lowest log Q(0) (8.891 and 7.636 μg/kg, respectively). The presence of SWCNTs reduced phenanthrene toxicity to algae (EC50; 528.4) compared to phenanthrene-only (EC50; 438.3), and the presence of MWCNTs had no significant effect on phenanthrene toxicity. However, phenanthrene adsorbed to NOM-dispersed CNTs proved to be bioavailable and contribute to exert toxicity to P. subcapitata.

  4. Bioavailability of freshly added and aged naphthalene in soils under gastric pH conditions

    SciTech Connect

    Jin, Z.; Simkins, S.; Xing, B.

    1999-12-01

    The bioavailability of hydrophobic organic chemicals decreases with aging in soil because of sequestration. However, assessments of the risk of exposure to contaminated soils are usually dependent on either chemical concentrations, which are measured using vigorous extraction methods, or models that assume an equilibrium without considering the actual conditions. The objective of this research was to determine the availability and desorption kinetics of freshly added and aged naphthalene from a peat and a mineral soil; naphthalene was desorbed into solutions with pH levels that approximate those found in different gastric regions. Soil and peat samples were spiked with radiolabeled and unlabeled naphthalene at 2 and 20 {micro}g/g and were aged from 0 to 135 d. Desorption kinetics were determined using a simulated stomach solution and a neutral solution that represented the pH of intestinal conditions and most soils. Peat sorbed much more naphthalene than did soil, and it allowed little desorption. Though both acidic and neutral extracting solutions could desorb naphthalene, little apparent effect of aging was observed in peat, whereas desorption from soil declined markedly with aging. In addition, the percentage of naphthalene that desorbed from soil was greater for the higher incubation concentration. The desorption of naphthalene from the peat and soil was higher into the neutral solution than into the gastric solution. These results suggest that aging, exposure conditions, concentration effect, and organic matter content should be taken into account in predictive models and risk assessments.

  5. COMPETITIVE INFLUENCE OF PHOSPHORUS AND CALCIUM ON PB IN-VITRO BIOAVAILABILITY

    EPA Science Inventory

    The bioavailability of a metal is heavily related to the speciation of the particular metal. Further, the complexity of examining metal bioavailability is compounded by the presence of competitive ions. Thus, equally contaminated soils with varying concentrations of competitive e...

  6. Factors Influencing Oral Bioavailability of Thai Mango Seed Kernel Extract and Its Key Phenolic Principles.

    PubMed

    Jiamboonsri, Pimsumon; Pithayanukul, Pimolpan; Bavovada, Rapepol; Leanpolchareanchai, Jiraporn; Yin, Taijun; Gao, Song; Hu, Ming

    2015-11-30

    Mango seed kernel extract (MSKE) and its key components (gallic acid, GA; methyl gallate, MG; and pentagalloyl glucopyranose, PGG) have generated interest because of their pharmacological activities. To develop the potential use of the key components in MSKE as natural therapeutic agents, their pharmacokinetic data are necessary. Therefore, this study was performed to evaluate the factors affecting their oral bioavailability as pure compounds and as components in MSKE. The in vitro chemical stability, biological stability, and absorption were evaluated in Hanks' Balanced Salt Solution, Caco-2 cell and rat fecal lysates, and the Caco-2 cell model, respectively. The in vivo oral pharmacokinetic behavior was elucidated in Sprague-Dawley rats. The key components were unstable under alkaline conditions and in Caco-2 cell lysates or rat fecal lysates. The absorptive permeability coefficient followed the order MG > GA > PGG. The in vivo results exhibited similar pharmacokinetic trends to the in vitro studies. Additionally, the co-components in MSKE may affect the pharmacokinetic behaviors of the key components in MSKE. In conclusion, chemical degradation under alkaline conditions, biological degradation by intestinal cell and colonic microflora enzymes, and low absorptive permeability could be important factors underlying the oral bioavailability of these polyphenols.

  7. Influence of the consumption pattern of magnesium from magnesium-rich mineral water on magnesium bioavailability.

    PubMed

    Sabatier, Magalie; Grandvuillemin, Antoine; Kastenmayer, Peter; Aeschliman, Jean-Marc; Bouisset, Florilène; Arnaud, Maurice J; Dumoulin, Gilles; Berthelot, Alain

    2011-08-01

    It is generally considered that the absorption of Mg is inversely related to the ingested dose. The objective of the present study was to determine if the mode of administration (bolus v. consumption throughout the day) could influence Mg bioavailability from Mg-rich natural mineral water comparing the same nutritional Mg amount (126 mg). Using a 2 d cross-over design, twelve healthy men were asked to drink 1·5 litres Mg-rich mineral water either as 2 × 750 ml or 7 × 212 ml throughout the day. Two stable isotopes ((25)Mg and (26)Mg) were used to label the water in order to distinguish both regimens. Fractional apparent Mg absorption was determined by faecal monitoring and Mg retention was determined by measuring urinary excretion of Mg isotopes. Higher Mg absorption (50·7 (SD 12·7) v. 32·4 (SD 8·1) %; P = 0·0007) and retention (47·5 (SD 12·9) v. 29·0 (SD 7·5) %; P = 0·0008) from Mg-rich mineral water were observed when it was consumed in seven servings compared with larger servings. Thus, regular water consumption throughout the day is an effective way to increase Mg bioavailability from Mg-rich mineral water.

  8. The influence of benthic fish bioturbation on cadmium bioavailability to Daphnia magna

    SciTech Connect

    Wall, S.B.; Isely, J.J.; La Point, T.W.

    1994-12-31

    The authors are interested in how benthic fish bioturbation of contaminated sediments influences bioaccumulation into planktonic and, ultimately, nektonic organisms. They performed a series of exposures with cadmium-spiked sediment, 1 {mu}g/g nominal concentration, and koi carp Cyprinus carpio. Daphnia magna were placed in exposure aquaria with and without carp for six days and bioaccumulation after 48 h was measured. Preliminary results indicate that carp increased total suspended solids from 0.0 mg/L to 44.4 mg/L and mean total cadmium water concentrations, 1.4 {mu}g/L and 2.8 {mu}g/L, without and with fish, respectively. However, body burdens of Daphnia magna did not reflect the water concentration trend. Mean Cd residues of daphnids exposed without fish, 9.377 {mu}g/g, were not statistically different from those in the with-fish exposure, 8.348 {mu}g/g. Similarity in daphnid body burdens was probably due to cadmium binding with suspended sediment particles and dissolved organic carbon in the exposure chambers, therefore minimizing Cd bioavailability to D. magna. The present focus is on determining the bioavailable cadmium concentration.

  9. Influence of dissolved organic nitrogen on Ni bioavailability in Prorocentrum donghaiense and Skeletonema costatum.

    PubMed

    Huang, Xu-Guang; Li, Hao; Huang, Bang-qin; Liu, Feng-Jiao

    2015-07-15

    Dissolved organic nitrogen (DON) is an important nutrient in the aquatic environment. This study examined the influence of DON addition on the adsorption, absorption, and distribution in macromolecular forms of environmentally deleterious trace metal (Ni) in Prorocentrum donghaiense and Skeletonema costatum over eight days. Ni adsorption and absorption of two species increased with the addition of urea, while Ni adsorption and absorption of two species in the presence of humic substances (HS) decreased. Meanwhile, Ni adsorption and absorption of P. donghaiense were higher than that of S. costatum. Furthermore, Ni contents in the protein fraction of the cells, both in P. donghaiense and S. costatum, were increased with both urea and HS addition. Thus, urea and HS input could impact Ni biogeochemistry and bioavailability, and then affect the biodynamics thereafter.

  10. Biodegradation of aged diesel in diverse soil matrixes: impact of environmental conditions and bioavailability on microbial remediation capacity.

    PubMed

    Sutton, Nora B; van Gaans, Pauline; Langenhoff, Alette A M; Maphosa, Farai; Smidt, Hauke; Grotenhuis, Tim; Rijnaarts, Huub H M

    2013-07-01

    While bioremediation of total petroleum hydrocarbons (TPH) is in general a robust technique, heterogeneity in terms of contaminant and environmental characteristics can impact the extent of biodegradation. The current study investigates the implications of different soil matrix types (anthropogenic fill layer, peat, clay, and sand) and bioavailability on bioremediation of an aged diesel contamination from a heterogeneous site. In addition to an uncontaminated sample for each soil type, samples representing two levels of contamination (high and low) were also used; initial TPH concentrations varied between 1.6 and 26.6 g TPH/kg and bioavailability between 36 and 100 %. While significant biodegradation occurred during 100 days of incubation under biostimulating conditions (64.4-100 % remediation efficiency), low bioavailability restricted full biodegradation, yielding a residual TPH concentration. Respiration levels, as well as the abundance of alkB, encoding mono-oxygenases pivotal for hydrocarbon metabolism, were positively correlated with TPH degradation, demonstrating their usefulness as a proxy for hydrocarbon biodegradation. However, absolute respiration and alkB presence were dependent on soil matrix type, indicating the sensitivity of results to initial environmental conditions. Through investigating biodegradation potential across a heterogeneous site, this research illuminates the interplay between soil matrix type, bioavailability, and bioremediation and the implications of these parameters for the effectiveness of an in situ treatment.

  11. Assessing the Influences of Mercury Bioaccumulation and Bioavailability in Everglades Food Webs

    NASA Astrophysics Data System (ADS)

    Kendall, C.; Bemis, B. E.

    2005-05-01

    . Mosquitofish mercury does not correlate significantly with tissue d15N or the d15N difference between mosquitofish and periphyton (D15N). Thus, differences in trophic level (and bioaccumulation) among the fish do not contribute a detectable influence on mercury variations in the samples studied. In contrast with the d15N results, mosquitofish mercury levels show strong positive correlations with mosquitofish d34S and D34S. This suggests that during the period studied, mosquitofish mercury concentrations in the Everglades ecosystem were primarily influenced by the bioavailability of mercury, rather than by varied trophic position. Our findings also suggest that the d34S of biota may provide a useful indicator of potential hotspots of mercury methylation.

  12. Influence of organic matter on bio-availability of carbosulfan and its toxicity on a carabid beetle.

    PubMed

    Hautier, L; Jansen, J P; Mabon, N; Schiffers, B

    2007-01-01

    Study of factors influencing soil insecticide toxicity are needed to reduce negative impacts of these products on beneficial insects. To date, if high toxicity differences between different type of soils have been reported, there is few specific studies on soil parameters influence on selectivity of soil insecticides to beneficial arthropods. To assess the specific impact of organic matter, the relationship between bio-availability of a soil insecticide, carbosulfan [Sheriff 1 Gr], and its toxicity on a small Carabidae, Bembidion lampros (Herbst.) on a sand enriched with increasing quantities of organic matter was studied. In laboratory, adults of B. lampros were put on different substrate, made of sand or sand with addition of organic matter at 3, 6 and 9% w/w, and treated with carbosulfan applied as granule at the rate of 312.5, 625, 1250 and 6250 microg a.i./m corresponding respectively to 0.5, 1, 2 and 10% of the recommended field rate. Mortalities of B. lampros were assessed after 14 day of exposure. In parallel, the total carbosulfan residue (total extraction) and bioavailable fraction (CaCL2 aqueous extraction) were determined 48h after substrate treatments. According to the mortalities and bio-availability obtained, a dose--response relationship was calculated and compared with a reference relation dose--response obtained on sand, where the bio-availability of the product was considered as 100% of the amount of product applied. Carbosulfan was highly toxic on sand for B. lampros, with 100, 57 and 50% mortality at 10, 2 and 1% of the recommended field rate. When organic matter was added to the sand, the toxicity gradually decreased. This reduction in toxicity was more rapidly observed on sand + organic matter than on pure sand. The mortalities were strongly correlated with the bioavailability, indicating first that the organic matter is fixing an important part of the insecticide and secondly reduce its toxicity to beneficial arthropods. The results suggest

  13. Influence and interactions of multi-factors on the bioavailability of PAHs in compost amended contaminated soils.

    PubMed

    Wu, Guozhong; Li, Xingang; Kechavarzi, Cédric; Sakrabani, Ruben; Sui, Hong; Coulon, Frédéric

    2014-07-01

    Compost amendment to contaminated soils is a potential approach for waste recycling and soil remediation. The relative importance and interactions of multiple factors on PAH bioavailability in soils were investigated using conjoint analysis and five-way analysis of variance. Results indicated that soil type and contact time were the two most significant factors influencing the PAH bioavailability in amended soils. The other two factors (compost type and ratio of compost addition) were less important but their interactions with other factors were significant. Specifically the 4-factor interactions showed that compost addition stimulated the degradation of high molecular PAHs at the initial stage (3 month) by enhancing the competitive sorption within PAH groups. Such findings suggest that a realistic decision-making towards hydrocarbon bioavailability assessment should consider interactions among various factors. Further to this, this study demonstrated that compost amendment can enhance the removal of recalcitrant hydrocarbons such as PAHs in contaminated soils.

  14. Influence of chocolate matrix composition on cocoa flavan-3-ol bioaccessibility in vitro and bioavailability in humans.

    PubMed

    Neilson, Andrew P; George, Judy C; Janle, Elsa M; Mattes, Richard D; Rudolph, Ralf; Matusheski, Nathan V; Ferruzzi, Mario G

    2009-10-28

    Conflicting data exist regarding the influence of chocolate matrices on the bioavailability of epicatechin (EC) from cocoa. The objective of this study was to assess the bioavailability of EC from matrices varying in macronutrient composition and physical form. EC bioavailability was assessed from chocolate confections [reference dark chocolate (CDK), high sucrose (CHS), high milk protein (CMP)] and cocoa beverages [sucrose milk protein (BSMP), non-nutritive sweetener milk protein (BNMP)], in humans and in vitro. Six subjects consumed each product in a randomized crossover design, with serum EC concentrations monitored over 6 h post consumption. Areas under the serum concentration-time curve (AUC) were similar among chocolate matrices. However, AUCs were significantly increased for BSMP and BNMP (132 and 143 nM h) versus CMP (101 nM h). Peak serum concentrations (C(MAX)) were also increased for BSMP and BNMP (43 and 42 nM) compared to CDK and CMP (32 and 25 nM). Mean T(MAX) values were lower, although not statistically different, for beverages (0.9-1.1 h) versus confections (1.8-2.3 h), reflecting distinct shapes of the pharmacokinetic curves for beverages and confections. In vitro bioaccessibility and Caco-2 accumulation did not differ between treatments. These data suggest that bioavailability of cocoa flavan-3-ols is likely similar from typical commercial cocoa based foods and beverages, but that the physical form and sucrose content may influence T(MAX) and C(MAX).

  15. Influence of the Encapsulation Efficiency and Size of Liposome on the Oral Bioavailability of Griseofulvin-Loaded Liposomes.

    PubMed

    Ong, Sandy Gim Ming; Ming, Long Chiau; Lee, Kah Seng; Yuen, Kah Hay

    2016-08-26

    The objective of the present study was to investigate the influence of the encapsulation efficiency and size of liposome on the oral bioavailability of griseofulvin-loaded liposomes. Griseofulvin-loaded liposomes with desired characteristics were prepared from pro-liposome using various techniques. To study the effect of encapsulation efficiency, three preparations of griseofulvin, namely, griseofulvin aqueous suspension and two griseofulvin-loaded liposomes with different amounts of griseofulvin encapsulated [i.e., F1 (32%) and F2(98%)], were administered to rats. On the other hand, to study the effect of liposome size, the rats were given three different griseofulvin-loaded liposomes of various sizes, generated via different mechanical dispersion techniques [i.e., FTS (142 nm), MS (357 nm) and NS (813 nm)], but with essentially similar encapsulation efficiencies (about 93%). Results indicated that the extent of bioavailability of griseofulvin was improved 1.7-2.0 times when given in the form of liposomes (F1) compared to griseofulvin suspension. Besides that, there was an approximately two-fold enhancement of the extent of bioavailability following administration of griseofulvin-loaded liposomes with higher encapsulation efficiency (F2), compared to those of F1. Also, the results showed that the extent of bioavailability of liposomal formulations with smaller sizes were higher by approximately three times compared to liposomal formulation of a larger size. Nevertheless, a further size reduction of griseofulvin-loaded liposome (≤400 nm) did not promote the uptake or bioavailability of griseofulvin. In conclusion, high drug encapsulation efficiency and small liposome size could enhance the oral bioavailability of griseofulvin-loaded liposomes and therefore these two parameters deserve careful consideration during formulation.

  16. Influence of the Encapsulation Efficiency and Size of Liposome on the Oral Bioavailability of Griseofulvin-Loaded Liposomes

    PubMed Central

    Ong, Sandy Gim Ming; Ming, Long Chiau; Lee, Kah Seng; Yuen, Kah Hay

    2016-01-01

    The objective of the present study was to investigate the influence of the encapsulation efficiency and size of liposome on the oral bioavailability of griseofulvin-loaded liposomes. Griseofulvin-loaded liposomes with desired characteristics were prepared from pro-liposome using various techniques. To study the effect of encapsulation efficiency, three preparations of griseofulvin, namely, griseofulvin aqueous suspension and two griseofulvin-loaded liposomes with different amounts of griseofulvin encapsulated [i.e., F1 (32%) and F2(98%)], were administered to rats. On the other hand, to study the effect of liposome size, the rats were given three different griseofulvin-loaded liposomes of various sizes, generated via different mechanical dispersion techniques [i.e., FTS (142 nm), MS (357 nm) and NS (813 nm)], but with essentially similar encapsulation efficiencies (about 93%). Results indicated that the extent of bioavailability of griseofulvin was improved 1.7–2.0 times when given in the form of liposomes (F1) compared to griseofulvin suspension. Besides that, there was an approximately two-fold enhancement of the extent of bioavailability following administration of griseofulvin-loaded liposomes with higher encapsulation efficiency (F2), compared to those of F1. Also, the results showed that the extent of bioavailability of liposomal formulations with smaller sizes were higher by approximately three times compared to liposomal formulation of a larger size. Nevertheless, a further size reduction of griseofulvin-loaded liposome (≤400 nm) did not promote the uptake or bioavailability of griseofulvin. In conclusion, high drug encapsulation efficiency and small liposome size could enhance the oral bioavailability of griseofulvin-loaded liposomes and therefore these two parameters deserve careful consideration during formulation. PMID:27571096

  17. Influence of sediment-organic matter quality on growth and polychlorobiphenyl bioavailability in Echinodermata (Amphiura filiformis)

    SciTech Connect

    Gunnarsson, J.S.; Granberg, M.E.; Nilsson, H.C.; Rosenberg, R.; Hellman, B.

    1999-07-01

    Sediment total organic carbon (TOC) content is considered to be a primary food source for benthic invertebrates and a major factor influencing the partitioning and bioavailability of sediment-associated organic contaminants. Most studies report that both toxicity and uptake of sediment-associated contaminants by benthic organisms are inversely proportional to sediment TOC content. The aim of this study was to determine the importance of the TOC quality for the bioavailability of sediment-associated organic contaminants and the growth of benthic macrofauna. The common infaunal brittle star Amphiura filiformis was exposed to a base sediment covered by a {sup 14}C-polychlorobipenyl (3,3{prime}4,4{prime}-{sup 14}C-tetrachlorobiphenyl (TCB)) contaminated top layer (0--2 cm), enriched to the same TOC content with 31 g TOC/m{sup 2} of different quality and origin. The following carbon sources, ranging from labile to refractory, were used: (1) green macroalga (Ulva lactuca), (2) brown macroalga (Ascophyllum nodosum), (3) eelgrass (Zostera Marina), (4) phytoplankton (Ceratium spp.), and (5) lignins of terrestrial origin. Characterization of the organic matter quality was accomplished by measuring the content of amino acids, lipids, C, N, and polyphenolic compounds. The reactivity of the sedimentary organic matter was assessed by means of respiration and dissolved inorganic nitrogen flux measurements. The experiment was carried out in 1-L glass jars, each containing four brittle stars and the contaminated and enriched sediment. The jars were circulated in a flow-through mode with filtered seawater. Somatic growth (regeneration of a precut arm) and bioaccumulation of {sup 14}C-TCB were measured at 10 sampling occasions during 48 d of exposure. Growth rates, TCB uptake rates, and steady-state concentrations differed significantly between treatments and were correlated to the qualities of the organic substrates. The greatest TCB accumulation and growth were observed in

  18. Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia.

    PubMed

    Guo, Pengran; Jia, Xiaoyu; Duan, Taicheng; Xu, Jingwei; Chen, Hangting

    2010-09-01

    Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl(2), NH(4)NO(3), EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02M EDTA+0.5M NH(4)OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

  19. Understanding the influence of surface properties of nanoparticles and penetration enhancers for improving bioavailability in eye tissues in vivo.

    PubMed

    Mahaling, Binapani; Katti, Dhirendra S

    2016-03-30

    Nanoparticulate drug delivery systems, mucoadhesive polymers and penetration enhancers have been used individually to overcome ocular barriers and increase bioavailability to eye tissues. However the combined influence of mucoadhesive polymer coating and penetration enhancers on NP permeability has not been investigated. Hence, in this study, three types of core-shell nanoparticles with same hydrophobic core but different hydrophilic mucoadhesive shells were developed. Initially the influence of a single penetration enhancer (PE) [benzalkonium chloride (BAC)] on ocular permeability of all the three core-shell nanoparticles was studied. Then ocular permeability of a single nanoparticle system [polycaprolactone-pluronicF68 (PCL-PF68)] in presence of different types of PEs namely BAC, capric acid (CA), EDTA, sodium glycocolate (SG) and sodium taurocholate (ST) was studied. The results indicated that BAC differentially enhanced ocular permeability of nanoparticles depending on their surface properties. All the PEs except EDTA enhanced ocular permeability of PCL-PF68 nanoparticles to anterior part of the eye. BAC and CA showed increased bioavailability of PCL-PF68 nanoparticles in conjunctiva, SG in cornea, iris and ciliary body, and ST in cornea. Overall, the combination of PEs and surface properties of nanoparticles can differentially influence ocular permeability and bioavailability and can be advantageously used to develop improved ocular drug delivery systems.

  20. Aluminum bioavailability from drinking water is very low and is not appreciably influenced by stomach contents or water hardness.

    PubMed

    Yokel, R A; Rhineheimer, S S; Brauer, R D; Sharma, P; Elmore, D; McNamara, P J

    2001-03-21

    The objectives were to estimate aluminum (Al) oral bioavailability under conditions that model its consumption in drinking water, and to test the hypotheses that stomach contents and co-administration of the major components of hard water affect Al absorption. Rats received intragastric 26Al in the absence and presence of food in the stomach and with or without concomitant calcium (Ca) and magnesium (Mg) at concentrations found in hard drinking water. The use of 26Al enables the study of Al pharmacokinetics at physiological Al concentrations without interference from 27Al in the environment or the subject. 27Al was intravenously administered throughout the study. Repeated blood withdrawal enabled determination of oral 26Al bioavailability from the area under its serum concentrationxtime curve compared to serum 27Al concentration in relation to its infusion rate. Oral Al bioavailability averaged 0.28%. The presence of food in the stomach and Ca and Mg in the water that contained the orally dosed 26Al appeared to delay but not significantly alter the extent of 26Al absorption. The present and published results suggest oral bioavailability of Al from drinking water is very low, about 0.3%. The present results suggest it is independent of stomach contents and water hardness.

  1. The Influence of Multiwalled Carbon Nanotubes on Polycyclic Aromatic Hydrocarbon (PAH) Bioavailability and Toxicity to Soil Microbial Communities in Alfalfa Rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbon nanotubes (CNTs) may affect bioavailability and toxicity of organic contaminants due to their adsorption properties. Recent studies have observed the influence of multiwalled carbon nanotubes (MWNTs) on the fate of polycyclic aromatic hydrocarbons (PAHs) and other organic contaminants. Greenh...

  2. Influence of Dissolved Organic Matter on Tetracycline Bioavailability to an Antibiotic-Resistant Bacterium.

    PubMed

    Chen, Zeyou; Zhang, Yingjie; Gao, Yanzheng; Boyd, Stephen A; Zhu, Dongqiang; Li, Hui

    2015-09-15

    Complexation of tetracycline with dissolved organic matter (DOM) in aqueous solution could alter the bioavailability of tetracycline to bacteria, thereby alleviating selective pressure for development of antibiotic resistance. In this study, an Escherichia coli whole-cell bioreporter construct with antibiotic resistance genes coupled to green fluorescence protein was exposed to tetracycline in the presence of DOM derived from humic acids. Complexation between tetracycline and DOM diminished tetracycline bioavailability to E. coli, as indicated by reduced expression of antibiotic resistance genes. Increasing DOM concentration resulted in decreasing bioavailability of tetracycline to the bioreporter. Freely dissolved tetracycline (not complexed with DOM) was identified as the major fraction responsible for the rate and magnitude of antibiotic resistance genes expressed. Furthermore, adsorption of DOM on bacterial cell surfaces inhibited tetracycline diffusion into the bioreporter cells. The magnitude of the inhibition was related to the amount of DOM adsorbed and tetracycline affinity for the DOM. These findings provide novel insights into the mechanisms by which the bioavailability of tetracycline antibiotics to bacteria is reduced by DOM present in water. Agricultural lands receiving livestock manures commonly have elevated levels of both DOM and antibiotics; the DOM could suppress the bioavailability of antibiotics, hence reducing selective pressure on bacteria for development of antibiotic resistance.

  3. Erythrocyte fatty acid composition does not influence levels of free, bioavailable, and total 25-hydroxy vitamin D.

    PubMed

    Carlsson, Martin; Nilsson, Ingela; Brudin, Lars; Von, Siv-Ping; Wanby, Pär

    2017-02-01

    In vitro, mono- and polyunsaturated fatty acids (FAs) may decrease the binding affinity of vitamin D metabolites for vitamin D-binding protein, which in turn may influence their bioavailability. FAs incorporated as phospholipids in erythrocyte (ery-) cell membranes reflect dietary intake. The purpose of this study was to investigate ery-FA composition in relation to markers for vitamin D. In healthy females (age 22.6 ± 2.0 years) total 25(OH)D was measured by LC-MS/MS (n = 78), free 25(OH)D with ELISA (n = 64 of 78), and bioavailable 25(OH)D was calculated. Analysis of ery-FA composition was by gas chromatography (n = 56 of 78). A strong correlation between total 25(OH)D and free 25(OH)D was seen (r = .66, p < .001), and between total-25(OH)D and bioavailable 25(OH)D (r = .68, p < .001). No correlations between 25(OH)D fractions and specific fatty acids were found, and in particular, no associations with mono- and poly-unsaturated FA compositions. All 25(OH)D fractions were correlated with leptin (total 25(OH)D (r = -.33, p < .003); bioavailable 25(OH)D (r = -.47, p < .001); free 25(OH)D (r = -.44, p < .001). Associations were found between PTH and total 25(OH)D (r = -.35, p = .002) and weaker between bioavailable 25(OH)D (r = -.35, p = .040) and free 25(OH)D (r = -.28, p = .079). All fractions of 25(OH)D appear to correlate in a similar way to PTH, BMI and body fat (leptin). No association was found between ery-FA composition and free/bioavailable 25(OH)D. It is unlikely that FAs are a strong uncoupling factor of DBP-bound 25(OH)D.

  4. Influence of polyvinylpyrrolidone quantity on the solubility, crystallinity and oral bioavailability of fenofibrate in solvent-evaporated microspheres.

    PubMed

    Yousaf, Abid Mehmood; Kim, Dong Wuk; Kim, Dong Shik; Kim, Jong Oh; Youn, Yu Seok; Cho, Kwan Hyung; Yong, Chul Soon; Choi, Han-Gon

    2016-06-01

    The objective of this study is to explore the influence of polyvinylpyrrolidone (PVP) quantity on the solubility, crystallinity and oral bioavailability of poorly water-soluble fenofibrate in solvent-evaporated microspheres. Numerous microspheres were prepared with fenofibrate, sodium lauryl sulphate (SLS) and PVP using the spray-drying technique. Their aqueous solubility, dissolution, physicochemical properties and pharmacokinetics in rats were assessed. The drug in the solvent-evaporated microspheres composed of fenofibrate, PVP and SLS at the weight ratio of 1:0.5:0.25 was not entirely changed to the amorphous form and partially in the microcrystalline state. However, the microspheres at the weight ratio of 1:4:0.25 provided the entire conversion to the amorphous form. The latter microspheres, with an improvement of about 115 000-fold in aqueous solubility and 5.6-fold improvement in oral bioavailability compared with the drug powder, gave higher aqueous solubility and oral bioavailability compared with the former. Thus, PVP quantity played an important role in these properties of fenofibrate in the solvent-evaporated microspheres.

  5. Organic amendments' dissolved organic carbon influences bioavailability of agricultural soil DOC

    NASA Astrophysics Data System (ADS)

    Straathof, Angela L.; Chincarini, Riccardo; Hoffland, Ellis; Comans, Rob N. J.

    2013-04-01

    Agricultural soils benefit from additions of organic amendments because they improve soil structure, are a source of plant nutrients, and increase concentrations of soil organic carbon (SOC). The latter fuels microbial processes important for plant growth, including nutrient mineralization and the suppression of plant diseases. However, these amendment additions range in quality and quantity of C and little is known about how their properties interact with native soil C and affect turnover. The dissolved pool of SOC (DOC) may be the most important C source for these processes as it is more biologically available and thus relatively easily turned over by the soil microbial biomass. Using a rapid-batch DOC fractionation procedure, we studied the composition of different organic amendments' DOC pools and measured how their additions change the quantity and turnover of soil DOC. Fractions isolated and quantified with this procedure include humic and fulvic acids, hydrophobic neutral and hydrophilic compounds. We hypothesized that these range from biologically recalcitrant to readily available, respectively. Amendments analysed included composts of different source materials and maturation stages collected from two different compost facilities in the Netherlands. Both total DOC concentrations and proportions of the aforementioned fractions ranged highly between composts. Composts cured for >10 days had a lower proportion of hydrophilic C compounds, suggesting that these are the most bioavailable and released as CO2 via microbial activity during maturation. To measure the effects of compost DOC on soil DOC, we extracted the former and added it to a sandy soil in an incubation experiment. The amendment increased soil total DOC, CO2 production from the soil, and the pools of humic and fulvic acids as a proportion of total DOC. Turnover of C from the incubated soil was measured by substrate-induced CO2 production (an indicator of microbial activity) from a 96-well

  6. Influence of PEG coating on the oral bioavailability of gold nanoparticles in rats.

    PubMed

    Alalaiwe, Ahmed; Roberts, Georgia; Carpinone, Paul; Munson, John; Roberts, Stephen

    2017-11-01

    Metallic nanoparticles can be produced in a variety of shapes, sizes, and surface chemistries, making them promising potential tools for drug delivery. Most studies to date have evaluated uptake of metallic nanoparticles from the GI tract with methods that are at best semi-quantitative. This study used the classical method of comparing blood concentration area under the curve (AUC) following intravenous and oral doses to determine the oral bioavailability of 1, 2 and 5 kDa PEG-coated 5 nm gold nanoparticles (AuNPs). Male rats were given a single intravenous dose (0.8 mg/kg) or oral (gavage) dose (8 mg/kg) of a PEG-coated AuNP, and the concentration of gold was measured in blood over time and in tissues (liver, spleen and kidney) at sacrifice. Blood concentrations following oral administration were inversely related to PEG size, and the AUC in blood was significantly greater for the 1 kDa PEG-coated AuNPs than particles coated with 2 or 5 kDa PEG. However, bioavailabilities of all of the particles were very low (< 0.1%). Concentrations in liver, spleen and kidney were similar after the intravenous doses, but kidney showed the highest concentrations after an oral dose. In addition to providing information on the bioavailability of AuNPs coated with PEG in the 1-5 kDa range, this study demonstrates the utility of applying the blood AUC approach to assess the quantitative oral bioavailability of metallic nanoparticles.

  7. Influence of hard water on the bioavailability of enrofloxacin in broilers.

    PubMed

    Sumano, L H; Gutierrez, O L; Aguilera, R; Rosiles, M R; Bernard, B M J; Gracia, M J

    2004-05-01

    To define the impact that use of different levels of hard water has on the bioavailability of the antibacterial, enrofloxacin, in poultry, an oral bioavailability-pharmacokinetic study of the drug was carried out. Two hundred fifty clinically healthy broilers, divided into 5 groups, were individually dosed orally with 10 mg/kg of enrofloxacin diluted to 0.1%. The enrofloxacin was diluted with water of increasing hardness in accordance with an international grading system. After dosing, blood samples were obtained at predetermined times. Serum was recovered and quantified for enrofloxacin by means of an agar diffusion bacteriological method. The composite serum concentrations of enrofloxacin and metabolites vs. time relationships were analyzed using software for compartmental pharmacokinetics. Results show that there were statistically significant differences in the following pharmacokinetic variables: maximal serum concentrations (Csmax), area under the time vs. concentration curves, and half-lives of the elimination phases. The means of these values showed a linear decay of Csmax from one group to the next as water hardness increased. Chemical analysis of water calcium and magnesium ions revealed the formation of coordination groups. Lack of interference with the microbiological activity in vitro of enrofloxacin diluted in hard water indicated that diminished absorption may be partly responsible for reduction in bioavailability. These results stress the need for proper water supply when enrofloxacin is used and point out a factor that must be taken into account when clinical outcomes do not comply with expectations.

  8. Influence of Mycotoxin Binders on the Oral Bioavailability of Doxycycline in Pigs.

    PubMed

    De Mil, Thomas; Devreese, Mathias; De Saeger, Sarah; Eeckhout, Mia; De Backer, Patrick; Croubels, Siska

    2016-03-16

    Mycotoxin binders are feed additives that aim to adsorb mycotoxins in the gastrointestinal tract of animals, making them unavailable for systemic absorption. The antimicrobial drug doxycycline (DOX) is often used in pigs and is administered through feed or drinking water; hence, DOX can come in contact with mycotoxin binders in the gastrointestinal tract. This paper describes the effect of four mycotoxin binders on the absorption of orally administered DOX in pigs. Two experiments were conducted: The first used a setup with bolus administration to fasted pigs at two different dosages of mycotoxin binder. In the second experiment, DOX and the binders were mixed in the feed at dosages recommended by the manufacturers (= field conditions). Interactions are possible between some of the mycotoxin binders dosed at 10 g/kg feed but not at 2 g/kg feed. When applying field conditions, no influences were seen on the plasma concentrations of DOX.

  9. Influences of dietary uptake and reactive sulfides on metal bioavailability from aquatic sediments

    USGS Publications Warehouse

    Lee, B.-G.

    2000-01-01

    Understanding how animals are exposed to the large repository of metal pollutants in aquatic sediments is complicated and is important in regulatory decisions. Experiments with four types of invertebrates showed that feeding behavior and dietary uptake control bioaccumulation of cadmium, silver, nickel, and zinc. Metal concentrations in animal tissue correlated with metal concentrations extracted from sediments, but not with metal in porewater, across a range of reactive sulfide concentrations, from 0.5 to 30 micromoles per gram. These results contradict the notion that metal bioavailability in sediments is controlled by geochemical equilibration of metals between porewater and reactive sulfides, a proposed basis for regulatory criteria for metals.

  10. COMPETITIVE INFLUENCE OF PHOSPHORUS AND CALCIUM ON PB IN-VITRO BIOAVAILABILITY (S11-SCHECKEL101231-POSTER)

    EPA Science Inventory

    The bioavailability of a metal is heavily related to the speciation of the particular metal. Further, the complexity of examining metal bioavailability is compounded by the presence of competitive ions. Thus, equally contaminated soils with varying concentrations of competitive e...

  11. Influence of the nonionic surfactant Brij 35 on the bioavailability of solid and sorbed dibenzofuran.

    PubMed

    Garcia, J M; Wick, L Y; Harms, H

    2001-05-15

    The effect of the nonionic surfactant Brij 35 on the bioavailability of solid and Teflon-sorbed dibenzofuran for Sphingomonas sp. strain HH19k was studied in simple model systems. Growth with dibenzofuran and dibenzofuran-specific oxygen uptake in surfactant-free media and with Brij 35 above the critical micelle concentration (cmc) were compared with dissolution and desorption in the absence of bacteria. Brij 35 accelerated dissolution and biodegradation of solid dibenzofuran by a factor of 2. It also enhanced the initial desorption rate of dibenzofuran from Teflon by this factor. Continuously decreasing desorption rates were attributed to slow diffusion of dibenzofuran inside Teflon, leading to depletion of dibenzofuran in the exterior of the Teflon particles. Surprisingly, Brij 35 slowed the initial biodegradation of desorbing dibenzofuran. We propose two processes that led to low bioavailability of sorbed dibenzofuran in the presence of surfactant. First, desorbing dibenzofuran rapidly accumulated in surfactant micelles, leading to reduced truly water-dissolved dibenzofuran concentration as the factor controlling the biodegradation rate. Second, Brij 35 suppressed the contact between bacteria and Teflon. This increased the average diffusion distance of dibenzofuran to the bacteria, which in turn flattened the gradient of the dissolved dibenzofuran concentration between the sorbent and the cells as the driving force for desorption.

  12. The influence of seasonality (dry and rainy) on the bioavailability and bioconcentration of metals in an estuarine zone

    NASA Astrophysics Data System (ADS)

    Milazzo, Alexandre Dacorso Daltro; Silva, Ana Carina Matos; Oliveira, Daiane Aparecida Francisco de; Cruz, Manoel Jerônimo Moreira da

    2014-08-01

    Knowledge on the concentration of metallic elements is important to certify the quality of ecosystems. Such behaviors in estuarine environments are dependent of factors such as rainfall and temperature of the water, interfering directly on the metal concentrations in biotic and abiotic components. This study observed the role that seasonality (dry and rainy) had on the bioavailability of metals (Fe, Zn, Mn, Cu, Ni, and Al) in surface water and sediment, and bioconcentration in oysters (Cassostrea rhizophorae) in the mangrove area of the São Paulo river estuary, Todos os Santos Bay. The metals concentration in three matrices analyzed varied between the periods studied. The values of physicochemical parameters also had significant variations. High levels of Zn and Cu were found in mollusks. The highest concentrations of metals analyzed were Al in waters, Fe in sediments and Zn in mollusks. These results showed that seasonality interferes directly in the physicochemical parameters analyzed (pH, dissolved oxygen, temperature, salinity and Eh), as well as on the bioavailability of metals in both water and sediment, influencing directly on the concentrations found in mollusks.

  13. Diseases and Conditions That Influence Fertility

    MedlinePlus

    ... and Conditions That Influence Fertility Skip sharing on social media links Share this: Page Content Many different health issues can affect a woman's ability to get pregnant. Some of the more common ...

  14. Mineralogy affects geoavailability, bioaccessibility and bioavailability of zinc.

    PubMed

    Molina, Ramon M; Schaider, Laurel A; Donaghey, Thomas C; Shine, James P; Brain, Joseph D

    2013-11-01

    We correlated mineralogical and particle characteristics of Zn-containing particles with Zn geoavailability, bioaccessibility, and bioavailability following gavage and intranasal (IN) administration in rats. We compared samples of Zn/Pb mine waste and five pulverized pure-phase Zn minerals (<38 μm). Particles were neutron-activated to produce radioactive (65)Zn. We assessed geoavailability using sequential extractions and bioaccessibility using in vitro extraction tests simulating various pH and biological conditions. Zn in vivo bioavailability and in vitro bioaccessibility decreased as follows: mine waste > hydrozincite > hemimorphite > zincite ≈ smithsonite > sphalerite. We found significant correlations among geoavailability, bioaccessibility and bioavailability. In particular, Zn bioavailability post-gavage and post-IN was significantly correlated with bioaccessibility in simulated phagolysosomal fluid and gastric fluid. These data indicate that solid phase speciation influences biological uptake of Zn and that in vitro tests can be used to predict Zn bioavailability in exposure assessment and effective remediation design.

  15. Mineralogy affects geoavailability, bioaccessibility and bioavailability of zinc

    PubMed Central

    Molina, Ramon M.; Schaider, Laurel A.; Donaghey, Thomas C.; Shine, James P.; Brain, Joseph D.

    2013-01-01

    We correlated mineralogical and particle characteristics of Zn-containing particles with Zn geoavailability, bioaccessibility, and bioavailability following gavage and intranasal (IN) administration in rats. We compared samples of Zn/Pb mine waste and five pulverized pure-phase Zn minerals (<38 μm). Particles were neutron-activated to produce radioactive 65Zn. We assessed geoavailability using sequential extractions and bioaccessibility using in vitro extraction tests simulating various pH and biological conditions. Zn in vivo bioavailability and in vitro bioaccessibility decreased as follows: mine waste > hydrozincite > hemimorphite > zincite ≈ smithsonite ≫ sphalerite. We found significant correlations among geoavailability, bioaccessibility and bioavailability. In particular, Zn bioavailability post-gavage and post-IN was significantly correlated with bioaccessibility in simulated phagolysosomal fluid and gastric fluid. These data indicate that solid phase speciation influences biological uptake of Zn and that in vitro tests can be used to predict Zn bioavailability in exposure assessment and effective remediation design. PMID:23933126

  16. The influence of hydrocolloid patch composition on the bioavailability of triamcinolone acetonide in humans.

    PubMed

    Martin, G P; Ladenheim, D; Marriott, C; Hollingsbee, D A; Brown, M B

    2000-01-01

    Triamcinolone acetonide (TACA) is a corticosteroid; it is used in the systemic and topical treatment of a variety of inflammatory conditions, including eczema and psoriasis. Conventionally, for topical use, the drug is formulated in a cream or ointment. However, it has been observed in vitro that percutaneous penetration of corticosteroids can be influenced by hydrocolloid patches. Corticosteroids produce a pallor or blanching when applied to the skin that correlates with anti-inflammatory activity; this property has been used extensively as a bioassay. The aim of this study therefore was to evaluate the occlusive properties of a range of hydrocolloid patches containing TACA on the drug's penetration in vivo using visual assessment and a graded multiple measurement. The in vivo hydration of these dermatological patches was also investigated. Statistical analysis of the weight gains of patches containing either NaCMC 39% or pectin 39% showed that there was a significant difference in the rates of hydration of the two types of patch (p < .005). An increase in application time of the hydrocolloid patches allowed more TACA to be released, which was illustrated by an increase in both the maximum percentage total possible score (%TPS) values and AUC, although changes in the hydrocolloid composition did not significantly alter the blanching response. All of the patches adhered well, were unobtrusive to the normal activity of the wearers, and showed great potential for the convenient, localized, prolonged delivery of drugs to the skin.

  17. Bioavailability of Metal Ions and Evolutionary Adaptation

    PubMed Central

    Hong Enriquez, Rolando P.; Do, Trang N.

    2012-01-01

    The evolution of life on earth has been a long process that began nearly 3.5 × 109 years ago. In their initial moments, evolution was mainly influenced by anaerobic environments; with the rise of O2 and the corresponding change in bioavailability of metal ions, new mechanisms of survival were created. Here we review the relationships between ancient atmospheric conditions, metal ion bioavailability and adaptation of metals homeostasis during early evolution. A general picture linking geochemistry, biochemistry and homeostasis is supported by the reviewed literature and is further illustrated in this report using simple database searches. PMID:25371266

  18. [Physicochemical and microbiological factors influencing the bioavailability of organic contaminants in subsoils

    SciTech Connect

    Not Available

    1992-12-31

    We report progress in elucidating the microbiological variables important in determining the relative success of bacteria in utilizing soil-sorbed contaminants. Two bacterial species, Pseudomonas putida (ATCC 17484) and an Alcaligenes sp. isolated from petroleum contaminated soil are known to differ markedly in their ability to utilize soil-sorbed napthalene based on a kinetic comparison of their capability of naphthalene mineralization in soil-containing and soil-free systems. The kinetic analysis led us to conclude that strain 17484 had direct access to naphthalene present in a labile sorbed state which promoted the rapid desorption of naphthalene from the non-labile phase. Conversely, both the rate and extent of naphthalene mineralization by strain NP-Alk suggested that this organism had access only to naphthalene in solution. Desorption was thus limited and the efficiency of total naphthalene removal from these soil slurries was poor. These conclusions were based on the average activities of cells in soil slurries without regard for the disposition of the organisms with respect to the sorbent. Since both organisms degrade naphthalene by apparently identical biochemical pathways, have similar enzyme kinetic properties, and are both motile, gram negative organisms, we undertook a series of investigations to gain a better understanding of what microbiological properties were important in bioavailability.

  19. Lack of influence of sulglycotide on naproxen bioavailability in healthy volunteers.

    PubMed

    Berté, F; Feletti, F; di Valserra, M B; Nazzari, M; Cenedese, A; Cornelli, U

    1988-03-01

    We explored the bioavailability and kinetics of naproxen (N) in 12 healthy volunteers treated orally with single doses of 500 mg and retreated after a washout period with the same dose of N plus sulglycotide (S) 200 mg. Naproxen blood levels were measured by high-performance liquid chromatography (HPLC) in samples collected at 0.5, 1, 2, 4, 8, 12, and 24 h of dosing with N or with N + S. No statistically significant difference in terms of naproxen blood levels emerged as the product was administered alone or concurrently with sulglycotide. Peak plasma concentrations and AUC values were 71 +/- 3.16 micrograms/ml and 685 +/- 27 micrograms/ml/h, respectively for N alone, and 72.5 +/- 2.85 micrograms/ml and 651 +/- 28 micrograms/ml/h, respectively for N + S. The difference was not significant. Similarly, the kinetic behavior of naproxen was not modified by the simultaneous presence of sulglycotide, as shown by the t1/2 beta-values obtained with N alone (8.39 +/- 0.31 h) and with N + S (7.93 +/- 0.30 h), and likewise by the distribution volumes at equilibrium (7.63 +/- 0.42 and 7.9 +/- 0.38, respectively), Cmax (63.3 +/- 2.86 and 60.4 +/- 2.9 micrograms/ml, respectively) and tmax (0.95 +/- 0.06 and 1.10 +/- 0.10 h, respectively). From these findings it seems legitimate to claim that sulglycotide can be administered concurrently with naproxen to prevent possible gastric injury by the anti-inflammatory agent thanks to its wellknown antiulcer and cytoprotective activity on the gastric mucosa, without any undue interference with the absorption (hence effectiveness) of naproxen.

  20. Influences of humic acid on the bioavailability of phenanthrene and alkyl phenanthrenes to early life stages of marine medaka (Oryzias melastigma).

    PubMed

    Liu, Yangzhi; Yang, Chenghu; Cheng, Pakkin; He, Xiaojing; Zhu, Yaxian; Zhang, Yong

    2016-03-01

    The influences of humic acid (HA) on the environmental behavior and bioavailability of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs were investigated and compared using the early life stages of marine medaka (Oryzias melastigma, O. melastigma). It was demonstrated that the binding affinity of parent phenanthrene (PHE) with HA was smaller than that of 3-methyl phenanthrene (3-MP) and 9-ethyl phenanthrene (9-EP). Furthermore, the bioaccumulation of the three PAHs and the levels of lipid peroxidation (LPO) were calculated to study the changes in bioavailability of PAHs in presence of HA. The results indicated that the addition of HA significantly decreased the bioaccumulation and toxicity of PAHs by decreasing free PAHs concentrations. The bioavailable fractions of HA-bound PAHs in bioaccumulation (α) and toxicity (β) were evaluated, indicating that the HA-bound 3-MP and 9-EP show higher bioavailability in bioaccumulation and lower bioavailability in toxicity relative to those of PHE. The β/α values were less than 1 for all PAH treatment groups containing HA, suggesting that the fraction of HA-bound PAHs contributing to bioaccumulation was higher than that of HA-bound PAHs inducing toxic effect. In addition, we proposed that the free PAHs generated by desorption from HA in the cell were toxic by showing that the β/α ratio values are correlated with the log KOW values (p = 0.007 and R(2) = 0.8355). Thus, oil spill risk assessments should consider both alkyl PAHs and the factors that influence the bioavailability and toxicity of PAHs in the natural aquatic environments.

  1. Influence of hardness on the bioavailability of silver to a freshwater snail after waterborne exposure to silver nitrate and silver nanoparticles

    USGS Publications Warehouse

    Stoiber, Tasha L.; Croteau, Marie-Noele; Romer, Isabella; Tejamaya, Mila; Lead, Jamie R.; Luoma, Samuel N.

    2015-01-01

    The release of Ag nanoparticles (AgNPs) into the aquatic environment is likely, but the influence of water chemistry on their impacts and fate remains unclear. Here, we characterize the bioavailability of Ag from AgNO3 and from AgNPs capped with polyvinylpyrrolidone (PVP AgNP) and thiolated polyethylene glycol (PEG AgNP) in the freshwater snail, Lymnaea stagnalis, after short waterborne exposures. Results showed that water hardness, AgNP capping agents, and metal speciation affected the uptake rate of Ag from AgNPs. Comparison of the results from organisms of similar weight showed that water hardness affected the uptake of Ag from AgNPs, but not that from AgNO3. Transformation (dissolution and aggregation) of the AgNPs was also influenced by water hardness and the capping agent. Bioavailability of Ag from AgNPs was, in turn, correlated to these physical changes. Water hardness increased the aggregation of AgNPs, especially for PEG AgNPs, reducing the bioavailability of Ag from PEG AgNPs to a greater degree than from PVP AgNPs. Higher dissolved Ag concentrations were measured for the PVP AgNPs (15%) compared to PEG AgNPs (3%) in moderately hard water, enhancing Ag bioavailability of the former. Multiple drivers of bioavailability yielded differences in Ag influx between very hard and deionized water where the uptake rate constants (kuw, l g-1 d-1 ± SE) varied from 3.1 ± 0.7 to 0.2 ± 0.01 for PEG AgNPs and from 2.3 ± 0.02 to 1.3 ± 0.01 for PVP AgNPs. Modeling bioavailability of Ag from NPs revealed that Ag influx into L. stagnalis comprised uptake from the NPs themselves and from newly dissolved Ag.

  2. In vivo and in vitro testing for selenium and selenium compounds bioavailability assessment in foodstuff.

    PubMed

    Moreda-Piñeiro, Jorge; Moreda-Piñeiro, Antonio; Bermejo-Barrera, Pilar

    2017-03-04

    The assessment of selenium and selenium species bioavailability in foodstuff is of special concern on the context of human nutrition. In vivo (human and animal), and in vitro tests are important approaches for estimating the bioavailability of toxic and essential compounds to humans. An overview on in vivo and in vitro bioavailability assays for releasing selenium and selenium species in foodstuffs is summarized. Se and Se species content in a foodstuff critically influence Se bioavailability and bioactivity to humans and animals. Se bioavailability is affected by foodstuff-matrix major composition and minor components. Foodstuffs processing and/or treatments could enhancement or decrease Se bioavailability. Experimental conditions such as the selection of healthy status of examined people (in in vivo humans approaches), the selection of animal model (in vivo animals approaches), or the selection of GI conditions (in in vitro tests) could determines the results. Thus, international standardized protocol for in vivo and in vitro approaches assessment is mandatory.

  3. ALUMINUM BIOAVAILABILITY FROM DRINKING WATER IS VERY LOW AND IS NOT APPRECIABLY INFLUENCED BY STOMACH CONTENTS OR WATER HARDNESS. (R825357)

    EPA Science Inventory

    The objectives were to estimate aluminum (Al) oral bioavailability under conditions that model its consumption in drinking water, and to test the hypotheses that stomach contents and co-administration of the major components of hard water affect Al absorption. Rats received intra...

  4. Game theory, conditional preferences, and social influence.

    PubMed

    Stirling, Wynn C; Felin, Teppo

    2013-01-01

    Neoclassical noncooperative game theory is based on a simple, yet powerful synthesis of mathematical and logical concepts: unconditional and immutable preference orderings and individual rationality. Although this structure has proven useful for characterizing competitive multi-player behavior, its applicability to scenarios involving complex social relationships is problematic. In this paper we directly address this limitation by the introduction of a conditional preference structure that permits players to modulate their preference orderings as functions of the preferences of other players. Embedding this expanded preference structure in a formal and graphical framework provides a systematic approach for characterizing a complex society. The result is an influence network that allows conditional preferences to propagate through the community, resulting in an emergent social model which characterizes all of the social relationships that exist and which leads to solution concepts that account for both group and individual interests. The Ultimatum game is presented as an example of how social influence can be modeled with conditional preferences.

  5. Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.

    2000-01-01

    allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM - AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.Microcosms were used to simulate environmentally realistic metal, acid volatile sulfide (AVS), and geochemical gradients in sediments to evaluate effects of metal bioavailability. The 18-d study involved five test species: two bivalves and three polychaetes. Two series of experiments were designed to evaluate the effects of metal concentration and AVS on bioaccumulation, respectively. The metals of interest were cadmium, nickel, and zinc. Results showed that the concentrations of pore-water Cd, Ni, and Zn were controlled by the concentration of AVS. Organisms bioaccumulated significant amounts of metals from the sediments when the simultaneously extracted metal was only a small fraction of the AVS. Bioavailability increased linearly with the sediment metal concentration irrespective of AVS or pore-w

  6. Influence of compost addition on lead and arsenic bioavailability in reclaimed orchard soil assessed using Porcellio scaber bioaccumulation test.

    PubMed

    Udovic, M; McBride, M B

    2012-02-29

    Long-term application of lead arsenate in orchards has led to a significant accumulation of Pb and As in the topsoil. Reclamation of old orchards for agricultural purposes entails the exposure of humans to Pb and As, which can be reduced by adequate remediation actions. In this study, we assessed the remediation efficiency of compost addition, commonly used as a sustainable agricultural practice, in decreasing the human exposure Pb and As by direct ingestion. The remediation was evaluated based on Pb and As bioavailability, assessed by means of a selective non-exhaustive chemical extraction (modified Morgan extraction, MME), with a physiologically based extraction test (PBET) for the assessment of Pb and As bioavailability in ingested soils and with a novel in vivo bioaccumulation test with isopods (Porcellio scaber). All the tests showed that compost addition consistently reduced Pb, but increased As potential bioavailability. The bioaccumulation test with P. scaber was sensitive to changes in Pb and As bioavailability in test soils. However, the results indicate that the bioavailability of As could be under- or overestimated using solely chemical extraction tests. Indirect assessment of trace metal bioavailability with bioaccumulation in isopods can be used as complementary source of data to the existing in vitro chemical extraction test approach for the estimation of human exposure to trace elements in polluted and remediated soil. This is the first report on the use of As accumulation in P. scaber as a tool for the assessment of As bioavailability in contaminated orchard soil.

  7. Influence of two dietary fibers in the oral bioavailability and other pharmacokinetic parameters of ethinyloestradiol.

    PubMed

    García, J J; Fernández, N; Diez, M J; Sahagún, A; González, A; Alonso, M L; Prieto, C; Calle, A P; Sierra, M

    2000-11-01

    Dietary fibers are widely used in hypoglycaemic, hypolipidemic, slimming diets. It is probable that their ingestion coincides with the oral administration of drugs and a modification of their pharmacokinetics can appear. In the present study, the influence of two soluble fibers (guar gum and psyllium) was evaluated on the pharmacokinetics of ethinyloestradiol (EE) when they were administered together to female rabbits via the oral route. Three groups of rabbits were used. All animals received 1 mg/kg of EE; this compound was administered alone in the control group and with 3.5 g of guar gum or psyllium in the other two groups. When guar gum was administered, there was a decrease in the extent of EE absorbed, but no change was observed in the rate of absorption. When psyllium was administered, the extent of EE absorbed increased slightly and the rate of absorption was slower.

  8. Game Theory, Conditional Preferences, and Social Influence

    PubMed Central

    Stirling, Wynn C.; Felin, Teppo

    2013-01-01

    Neoclassical noncooperative game theory is based on a simple, yet powerful synthesis of mathematical and logical concepts: unconditional and immutable preference orderings and individual rationality. Although this structure has proven useful for characterizing competitive multi-player behavior, its applicability to scenarios involving complex social relationships is problematic. In this paper we directly address this limitation by the introduction of a conditional preference structure that permits players to modulate their preference orderings as functions of the preferences of other players. Embedding this expanded preference structure in a formal and graphical framework provides a systematic approach for characterizing a complex society. The result is an influence network that allows conditional preferences to propagate through the community, resulting in an emergent social model which characterizes all of the social relationships that exist and which leads to solution concepts that account for both group and individual interests. The Ultimatum game is presented as an example of how social influence can be modeled with conditional preferences. PMID:23451078

  9. Motivational conditions influence tongue motor performance.

    PubMed

    Kothari, Mohit; Svensson, Peter; Huo, Xueliang; Ghovanloo, Maysam; Baad-Hansen, Lene

    2013-04-01

    Motivation plays an important role in the outcome of motor learning but has not received attention in tongue-training-induced plasticity of the corticomotor pathways. The present study investigated the influence of two different motivational conditions and gender on performance during a complex tongue-training paradigm using the tongue drive system (TDS). In addition, subject-based reports of motivation, fun, pain, and fatigue were compared between groups and genders. Sixteen subjects were randomized into three groups and were asked to use the TDS for 40 min. A motivational condition (monetary reward or self-controlled practice) was introduced in two groups and the third group served as the control. The subjects were instructed to play a computer game using the TDS, having control of the computer cursor through a magnet attached to the tongue, and performance was compared among groups. Performance improved in all groups and in both genders. The monetary reward group tended towards higher performance scores compared with the control group, whereas the self-controlled practice group performed significantly better compared with the control group. There was no significant difference between groups and genders in the subject-based report for level of motivation, fun, pain, or fatigue. In conclusion, introduction of motivational conditions influenced tongue motor performance.

  10. Influence of soil type on the mobility and bioavailability of chelated zinc.

    PubMed

    Alvarez, Jose M

    2007-05-02

    The objective of this study was to compare the distribution, mobility, and relative effectiveness of Zn from Zn-amino acids (Zn-AA) and Zn-DTPA-HEDTA-EDTA (Zn-CH) (DTPA, diethylenetriaminepentaacetate; HEDTA, N-2-hydroxyethyl-ethylenedinitrilotriacetate; and EDTA, ethylenedinitrilotetraacetate) sources by applying different Zn levels to weakly acidic and neutral soils in laboratory (incubation and soil column studies) and greenhouse conditions. The experiments were carried out for 60 days in incubation and column experiments and for 45 days in a greenhouse experiment. The zinc soil behavior was evaluated by DTPA-TEA and Mehlich-3 extractions and sequential speciation. The incubation experiment showed that the highest concentrations of available Zn in weakly acidic soil occurred with Zn-AA treatments, whereas in the neutral soil Zn-CH treatments produced the highest quantities of available Zn. The column experiment showed that in neutral soil, with slow to moderate permeability in the Ap and Bt horizons, only Zn-CH significantly increased the mobility of Zn through the column with respect to the control and the Zn-AA source: 31% of the Zn applied as synthetic chelate was leached from the column. The greenhouse experiment showed that, at different rates of Zn application, the Zn carriers increased Zn uptake by maize (Zea mays L.). The use of applied Zn by maize, or Zn utilization, was greatest when the Zn treatments were Zn-CH (3.3%) at 20 mg kg-1 and Zn-CH (4.9%) at 10 mg kg-1, in weakly acidic and neutral soils, respectively.

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

    PubMed

    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.

  12. Influence of hardness on the bioavailability of silver to a freshwater snail after waterborne exposure to silver nitrate and silver nanoparticles.

    PubMed

    Stoiber, Tasha; Croteau, Marie-Noële; Römer, Isabella; Tejamaya, Mila; Lead, Jamie R; Luoma, Samuel N

    2015-01-01

    The release of Ag nanoparticles (AgNPs) into the aquatic environment is likely, but the influence of water chemistry on their impacts and fate remains unclear. Here, we characterize the bioavailability of Ag from AgNO(3) and from AgNPs capped with polyvinylpyrrolidone (PVP AgNP) and thiolated polyethylene glycol (PEG AgNP) in the freshwater snail, Lymnaea stagnalis, after short waterborne exposures. Results showed that water hardness, AgNP capping agents, and metal speciation affected the uptake rate of Ag from AgNPs. Comparison of the results from organisms of similar weight showed that water hardness affected the uptake of Ag from AgNPs, but not that from AgNO(3). Transformation (dissolution and aggregation) of the AgNPs was also influenced by water hardness and the capping agent. Bioavailability of Ag from AgNPs was, in turn, correlated to these physical changes. Water hardness increased the aggregation of AgNPs, especially for PEG AgNPs, reducing the bioavailability of Ag from PEG AgNPs to a greater degree than from PVP AgNPs. Higher dissolved Ag concentrations were measured for the PVP AgNPs (15%) compared to PEG AgNPs (3%) in moderately hard water, enhancing Ag bioavailability of the former. Multiple drivers of bioavailability yielded differences in Ag influx between very hard and deionized water where the uptake rate constants (k(uw), l g(-1) d(-1) ± SE) varied from 3.1 ± 0.7 to 0.2 ± 0.01 for PEG AgNPs and from 2.3 ± 0.02 to 1.3 ± 0.01 for PVP AgNPs. Modeling bioavailability of Ag from NPs revealed that Ag influx into L. stagnalis comprised uptake from the NPs themselves and from newly dissolved Ag.

  13. Influence of dissolved organic matter on the complexation of mercury under sulfidic conditions.

    PubMed

    Miller, Carrie L; Mason, Robert P; Gilmour, Cynthia C; Heyes, Andrew

    2007-04-01

    The complexation of Hg under sulfidic conditions influences its bioavailability for microbial methylation. Neutral dissolved Hg-sulfide complexes are readily available to Hg-methylating bacteria in culture, and thermodynamic models predict that inorganic Hg-sulfide complexes dominate dissolved Hg speciation under natural sulfidic conditions. However, these models have not been validated in the field. To examine the complexation of Hg in natural sulfidic waters, octanol/water partitioning methods were modified for use under environmentally relevant conditions, and a centrifuge ultrafiltration technique was developed. These techniques demonstrated much lower concentrations of dissolved Hg-sulfide complexes than predicted. Furthermore, the study revealed an interaction between Hg, dissolved organic matter (DOM), and sulfide that is not captured by current thermodynamic models. Whereas Hg forms strong complexes with DOM under oxic conditions, these complexes had not been expected to form in the presence of sulfide because of the stronger affinity of Hg for sulfide relative to its affinity for DOM. The observed interaction between Hg and DOM in the presence of sulfide likely involves the formation of a DOM-Hg-sulfide complex or results from the hydrophobic partitioning of neutral Hg-sulfide complexes into the higher-molecular-weight DOM. An understanding of the mechanism of this interaction and determination of complexation coefficients for the Hg-sulfide-DOM complex are needed to adequately assess how our new finding affects Hg bioavailability, sorption, and flux.

  14. Bioavailability of the Polyphenols: Status and Controversies

    PubMed Central

    D’Archivio, Massimo; Filesi, Carmelina; Varì, Rosaria; Scazzocchio, Beatrice; Masella, Roberta

    2010-01-01

    The current interest in polyphenols has been driven primarily by epidemiological studies. However, to establish conclusive evidence for the effectiveness of dietary polyphenols in disease prevention, it is useful to better define the bioavailability of the polyphenols, so that their biological activity can be evaluated. The bioavailability appears to differ greatly among the various phenolic compounds, and the most abundant ones in our diet are not necessarily those that have the best bioavailability profile. In the present review, we focus on the factors influencing the bioavailability of the polyphenols. Moreover, a critical overview on the difficulties and the controversies of the studies on the bioavailability is discussed. PMID:20480022

  15. Investigation of the Influence of Selected Soil and Plant Properties from Sakarya, Turkey, on the Bioavailability of Trace Elements by Applying an In Vitro Digestion Model.

    PubMed

    Altundag, Huseyin; Albayrak, Sinem; Dundar, Mustafa S; Tuzen, Mustafa; Soylak, Mustafa

    2015-11-01

    The main aim of this study was an investigation of the influence of selected soil and plant properties on the bioaccessibility of trace elements and hence their potential impacts on human health in urban environments. Two artificial digestion models were used to determine trace element levels passing from soil and plants to man for bioavailability study. Soil and plant samples were collected from various regions of the province of Sakarya, Turkey. Digestive process is started by addition of soil and plant samples to an artificial digestion model based on human physiology. Bioavailability % values are obtained from the ratio of the amount of element passing to human digestion to element content of soil and plants. According to bioavailability % results, element levels passing from soil samples to human digestion were B = Cr = Cu = Fe = Pb = Li < Al < Ni < Co < Ba < Mn < Sr < Cd < Na < Zn < Tl, while element levels passing from plant samples to human digestion were Cu = Fe = Ni = Pb = Tl = Na = Li < Co < Al < Sr < Ba < Mn < Cd < Cr < Zn < B. It was checked whether the results obtained reached harmful levels to human health by examining the literature.

  16. Epithelial transport of noscapine across cell monolayer and influence of absorption enhancers on in vitro permeation and bioavailability: implications for intestinal absorption.

    PubMed

    Chougule, Mahavir B; Patel, Apurva R; Patlolla, Ram; Jackson, Tanise; Singh, Mandip

    2014-07-01

    The purpose of this study was to investigate the permeation of Noscapine (Nos) across the Caco-2 and Madin-Darby canine kidney (MDCK) cell monolayers and to evaluate the influence of absorption enhancers on in vitro and in vivo absorption of Nos. The bidirectional transport of Nos was studied in Caco-2 and MDCK cell monolayers at pH 5.0-7.8. The effect of 0.5% w/v chitosan (CH) or Captisol (CP) on Nos permeability was investigated at pH 5.0 and 5.8. The effect of 1-5% w/v of CP on oral bioavailability of Nos (150 mg/kg) was evaluated in Sprague-Dawley rats. The effective permeability coefficients (Peff) of Nos across Caco-2 and MDCK cell monolayers was found to be in the order of pH 5.0 > 5.8 > 6.8 > 7.8. The efflux ratios of Peff < 2 demonstrated that active efflux does not limit the absorption of Nos. The use of CH or CP have shown significant (***, p < 0.001) enhancement in Peff of Nos across cell monolayer compared with the control group. The CP (1-5% w/v) based Nos formulations resulted in significant (***, p < 0.001) increase in the bioavailability of Nos compared with Nos solution. The use of CP represents viable approach for enhancing the oral bioavailability of Nos and reducing the required dose.

  17. Migration of (137)Cs, (90)Sr, and (239+240)Pu in Mediterranean forests: influence of bioavailability and association with organic acids in soil.

    PubMed

    Guillén, J; Baeza, A; Corbacho, J A; Muñoz-Muñoz, J G

    2015-06-01

    The understanding of downward migration of anthropogenic radionuclides in soil is a key factor in the assessment of their environmental behavior. There are several factors that can affect this process, such as the radionuclide source, their chemical form, soil and environmental characteristics, etc. Two Mediterranean pinewood ecosystems in Spain, which were affected mainly by global fallout, were selected to assess the migration of (137)Cs, (90)Sr, and (239+240)Pu. Using auxiliary modeling (diffusion-convection equation and compartmental model), it followed from field observations that the migration velocities of (90)Sr and (239+240)Pu were similar and higher than that of (137)Cs. The downward migration of radionuclides can be considered a consequence of their association with soil particles. A sequential speciation procedure also confirmed that (90)Sr was the most bioavailable radionuclide followed by (239+240)Pu and (137)Cs. Although this can explain the different velocity of (90)Sr and (137)Cs, bioavailability could not explain by itself the similar velocities of (239+240)Pu and (90)Sr. The presence of organic acids in the soil can also influence the migration of radionuclides attached to them, which decreased in the order: (239+240)Pu > (90)Sr > (137)Cs. Thus, the joint consideration of bioavailable and humic + fulvic acid fractions can explain the observed differences in the downward velocities.

  18. [Influence of sulfur on the bioavailability of arsenic uptake by rice (Oryza. sativa L. ) and its speciation in soil ].

    PubMed

    Yang, Shi-jie; Tang, Bing-pei; Wang, Dai-chang; Rao, Wei; Zhang, Ya-nan; Wang, Dan; Zhu, Yun-ji

    2014-09-01

    Pot experiments using exogenous arsenic-polluted paddy soils were carried out to investigate the influence of different forms of sulfur fertilizers (sulfur and gypsum) on As uptake by rice and its chemical speciation. Soil solution pH value ranged 7. 38-7. 45 in different growth period of rice, and the pH value of AsS0 and AsS1 treatments was higher than that of AsS2 treatment. Variation of Eh value in soil solution was about 200 mV and the Eh of AsS0 was higher than those of AsS1 and AsS2 treatments. From dry matter weight of root and stem and grain of rice, S-fertilizer applied by sulfur and gypsum could improve the amounts of dry matter in rice, while the effects of sulfur treatments and gypsum treatments were not significant. Concentrations of Fe and Mn in iron-manganese plaque on rice roots were 10-30 g.kg-1 and 0.1-1.3 g.kg-1, respectively. Contents of Fe-Mn plaque were mainly different in the tiller stage. Elemental S treatment could more greatly promote the formation of Fe-Mn plaque of rice root than gypsum treatment. Concentrations of As adsorbed by rice roots surface plaque were 583-719 mg.kg-' in tiller stage, 466-621 mg.kg-1 in boot stage, and 310-384 mg kg-1 in flower and matur stage. And it was consistent with the thickness of Fe-Mn plaque on rice root surface. Concentrations of As uptake in roots and stem and leaf and grain were significantly reduced by the application of S fertilizer, and it may be related to the amount of As adsorbed by Fe-Mn plaque at boot stage. According to chemical speciation of soil arsenic, As of non-specific and specific adsorption was most active, and their amounts of As adsorbed in AsS, treatment were significantly lower by 2.85 mg kg-~' than that in AsS2 treatment in tiller stage, and was 0.77 mg.kg- higher than that in AsS2 treatment in the flower stage. Perhaps soil arsenic was easily dissolved in the soil solution and the bioavailability of AsS, treatment was better than that of AsS, treatment.

  19. Influence of Mycotoxins and a Mycotoxin Adsorbing Agent on the Oral Bioavailability of Commonly Used Antibiotics in Pigs

    PubMed Central

    Goossens, Joline; Vandenbroucke, Virginie; Pasmans, Frank; De Baere, Siegrid; Devreese, Mathias; Osselaere, Ann; Verbrugghe, Elin; Haesebrouck, Freddy; De Saeger, Sarah; Eeckhout, Mia; Audenaert, Kris; Haesaert, Geert; De Backer, Patrick; Croubels, Siska

    2012-01-01

    It is recognized that mycotoxins can cause a variety of adverse health effects in animals, including altered gastrointestinal barrier function. It is the aim of the present study to determine whether mycotoxin-contaminated diets can alter the oral bioavailability of the antibiotics doxycycline and paromomycin in pigs, and whether a mycotoxin adsorbing agent included into diets interacts with those antibiotics. Experiments were conducted with pigs utilizing diets that contained blank feed, mycotoxin-contaminated feed (T-2 toxin or deoxynivalenol), mycotoxin-contaminated feed supplemented with a glucomannan mycotoxin binder, or blank feed supplemented with mycotoxin binder. Diets with T-2 toxin and binder or deoxynivalenol and binder induced increased plasma concentrations of doxycycline administered as single bolus in pigs compared to diets containing blank feed. These results suggest that complex interactions may occur between mycotoxins, mycotoxin binders, and antibiotics which could alter antibiotic bioavailability. This could have consequences for animal toxicity, withdrawal time for oral antibiotics, or public health. PMID:22606377

  20. Influence of mycotoxins and a mycotoxin adsorbing agent on the oral bioavailability of commonly used antibiotics in pigs.

    PubMed

    Goossens, Joline; Vandenbroucke, Virginie; Pasmans, Frank; De Baere, Siegrid; Devreese, Mathias; Osselaere, Ann; Verbrugghe, Elin; Haesebrouck, Freddy; De Saeger, Sarah; Eeckhout, Mia; Audenaert, Kris; Haesaert, Geert; De Backer, Patrick; Croubels, Siska

    2012-04-01

    It is recognized that mycotoxins can cause a variety of adverse health effects in animals, including altered gastrointestinal barrier function. It is the aim of the present study to determine whether mycotoxin-contaminated diets can alter the oral bioavailability of the antibiotics doxycycline and paromomycin in pigs, and whether a mycotoxin adsorbing agent included into diets interacts with those antibiotics. Experiments were conducted with pigs utilizing diets that contained blank feed, mycotoxin-contaminated feed (T-2 toxin or deoxynivalenol), mycotoxin-contaminated feed supplemented with a glucomannan mycotoxin binder, or blank feed supplemented with mycotoxin binder. Diets with T-2 toxin and binder or deoxynivalenol and binder induced increased plasma concentrations of doxycycline administered as single bolus in pigs compared to diets containing blank feed. These results suggest that complex interactions may occur between mycotoxins, mycotoxin binders, and antibiotics which could alter antibiotic bioavailability. This could have consequences for animal toxicity, withdrawal time for oral antibiotics, or public health.

  1. Influence of hydrophilic additives on the supersaturation and bioavailability of dutasteride-loaded hydroxypropyl-β-cyclodextrin nanostructures

    PubMed Central

    Kim, Min-Soo

    2013-01-01

    The objectives of this study were to develop a novel solid dutasteride formulation with improved physicochemical properties and oral bioavailability, and to examine the correlation between its in vitro dissolution and in vivo pharmacokinetic parameters. Hydroxypropyl-β-cyclodextrin (HP-β-CD) nanostructures with or without hydrophilic additives were manufactured using the supercritical antisolvent process. The dutasteride-loaded HP-β-CD nanoparticles formed aggregates with a mean particle size of less than 160 nm and a specific surface area greater than 100 m2/g. Increases in the supersaturation and dissolution rate for dutasteride were dependent on the type of additive; increases in maximum solubility and extended supersaturation were observed in dutasteride-loaded HP-β-CD nanostructures with hydroxypropylmethyl cellulose, whereas the dissolution rate was the highest for nanostructures containing d-α-tocopheryl polyethylene glycol 1000 succinate. In rats, the oral bioavailability of dutasteride increased with the supersaturation induced by the HP-β-CD nanostructures. In addition, compared with the in vitro drug release rate, the in vivo pharmacokinetic parameters were more closely correlated with in vitro parameters related to supersaturation (solubility). Further, the bioavailability of the dutasteride-loaded HP-β-CD nanostructures with hydroxypropylmethyl cellulose was similar to that of the commercially available soft gelatin capsule (Avodart®). In conclusion, preparation of dutasteride-loaded HP-β-CD nanostructures using the supercritical antisolvent process affords a viable alternative solid dosage form for dutasteride. PMID:23737668

  2. Influence of hydrophilic additives on the supersaturation and bioavailability of dutasteride-loaded hydroxypropyl-β-cyclodextrin nanostructures.

    PubMed

    Kim, Min-Soo

    2013-01-01

    The objectives of this study were to develop a novel solid dutasteride formulation with improved physicochemical properties and oral bioavailability, and to examine the correlation between its in vitro dissolution and in vivo pharmacokinetic parameters. Hydroxypropyl-β-cyclodextrin (HP-β-CD) nanostructures with or without hydrophilic additives were manufactured using the supercritical antisolvent process. The dutasteride-loaded HP-β-CD nanoparticles formed aggregates with a mean particle size of less than 160 nm and a specific surface area greater than 100 m(2)/g. Increases in the supersaturation and dissolution rate for dutasteride were dependent on the type of additive; increases in maximum solubility and extended supersaturation were observed in dutasteride-loaded HP-β-CD nanostructures with hydroxypropylmethyl cellulose, whereas the dissolution rate was the highest for nanostructures containing d-α-tocopheryl polyethylene glycol 1000 succinate. In rats, the oral bioavailability of dutasteride increased with the supersaturation induced by the HP-β-CD nanostructures. In addition, compared with the in vitro drug release rate, the in vivo pharmacokinetic parameters were more closely correlated with in vitro parameters related to supersaturation (solubility). Further, the bioavailability of the dutasteride-loaded HP-β-CD nanostructures with hydroxypropylmethyl cellulose was similar to that of the commercially available soft gelatin capsule (Avodart®). In conclusion, preparation of dutasteride-loaded HP-β-CD nanostructures using the supercritical antisolvent process affords a viable alternative solid dosage form for dutasteride.

  3. Copper toxicity and the influence of water quality of Dongnai River and Mekong River waters on copper bioavailability and toxicity to three tropical species.

    PubMed

    Bui, Thanh-Khiet L; Do-Hong, L Chi; Dao, Thanh-Son; Hoang, Tham C

    2016-02-01

    The present study investigated copper (Cu) toxicity and the influence of water quality characteristics of Dongnai River and Mekong River (Vietnam) surface waters to three tropical species; Daphnia lumholtzi, Ceriodaphnia cornuta, and Danio rerio. The river waters had a range of water quality parameters that modify Cu bioavailability and toxicity. The range of total hardness, alkalinity, pH and dissolved organic carbon were 15-64 mg/L as CaCO3, 18-58 mg/L as CaCO3, 6.62-7.88, and 6.9-14.7 mg/l, respectively. The US EPA acute toxicity test method with a modification to the light photoperiod and temperature for tropical organisms was used to investigate Cu toxicity. Result of the present study found that Cu produced toxic effect to the studied organisms at low concentrations. The 48-h LC50 ranged from 3.92 to 8.61 µg/l, 2.92-9.56 µg/l, and 15.71-68.69 µg/l dissolved Cu for D. lumholtzi, C. cornuta, and D. rerio, respectively. In general, water quality had an influence on Cu bioavailability and toxicity to the studied organisms. The toxicity of Cu was higher in water with lower hardness, DOC, and/or pH. The present study indicates a contribution of Cu hydroxide and carbonate to Cu bioavailability to Mekong organisms. Results of the present study will be used for calibrating the US Cu Biotic Ligand Model (BLM) to Mekong River water and organisms in support of application of the BLM for setting site-specific Cu water quality guidelines in the ecosystem of the Lower Mekong River Basin.

  4. From conceptual model to remediation: bioavailability, a key to clean up heavy metal contaminated soils.

    NASA Astrophysics Data System (ADS)

    Petruzzelli, Gianniantonio; Pedron, Francesca; Pezzarossa, Beatrice

    2013-04-01

    Processes of metal bioavailability in the soil To know the bioavailability processes at site specific levels is essential to understand in detail the risks associated with pollution, and to support the decision-making process, i.e. description of the conceptual model and choice of clean up technologies. It is particularly important to assess how chemical, physical and biological processes in the soil affect the reactions leading to adsorption, precipitation or release of contaminants. The measurement of bioavailability One of the main difficulties in the practical application of the bioavailability concept in soil remediation is the lack of consensus on the method to be used to measure bioavailability. The best strategy is to apply a series of tests to assess bioavailability, since no applicable method is universally valid under all conditions. As an example, bioavailability tests for phytotechnology application should consider two distinct aspects: a physico-chemical driven solubilization process and a physiologically driven uptake process. Soil and plant characteristics strongly influence bioavailability. Bioavailability as a tool in remediation strategies Bioavailability can be used at all stages in remediation strategies: development of the conceptual model, evaluation of risk assessment, and selection of the best technology, considering different scenarios and including different environmental objectives. Two different strategies can be followed: the reduction and the increase of bioavailability. Procedures that reduce bioavailability aim to prevent the movement of pollutants from the soil to the living organisms, essentially by: i) removal of the labile phase of the contaminant, i.e. the fraction which is intrinsic to the processes of bioavailability (phytostabilization); ii) conversion of the labile fraction into a stable fraction (precipitation or adsorption); iii) increase of the resistance to mass transfer of the contaminants (inertization). Procedures

  5. The influence of droplet size on the stability, in vivo digestion, and oral bioavailability of vitamin E emulsions.

    PubMed

    Parthasarathi, S; Muthukumar, S P; Anandharamakrishnan, C

    2016-05-18

    Vitamin E (α-tocopherol) is a nutraceutical compound, which has been shown to possess potent antioxidant and anticancer activity. However, its biological activity may be limited by its poor bioavailability. Colloidal delivery systems have shown wide applications in the food and pharmaceutical industries to deliver lipophilic bioactive compounds. In this study, we have developed conventional and nanoemulsions of vitamin E from food grade ingredients (sunflower oil, saponin, and water) and showed the nanoemulsion formulation increased the oral bioavailability when compared to the conventional emulsion. The mean droplet diameters in the nano and conventional emulsions were 0.277 and 1.285 μm, respectively. The stability of the emulsion formulation after thermal processing, long-term storage at different temperatures, mechanical stress and in plasma was determined. The results showed that the saponin coated nanoemulsion was stable to droplet coalescence during thermal processing (30-90 °C), long-term storage and mechanical stress when compared to the conventional emulsion. The biological fate of the emulsion formulations were studied using male Wistar rats as an animal model. The emulsion droplet stability during passage through the gastrointestinal tract was evaluated by their introduction into rat stomachs. Microscopy was used to investigate the structural changes that occurred during digestion. Both the conventional emulsion and nanoemulsion formulations showed strong evidence of droplet flocculation and coalescence during in vivo digestion. The in vivo oral bioavailability study revealed that vitamin E in a nanoemulsion form showed a 3-fold increase in the AUC when compared to the conventional emulsion. The information reported in this study will facilitate the design of colloidal delivery systems using nanoemulsion formulations.

  6. Cues of Maternal Condition Influence Offspring Selfishness

    PubMed Central

    Wong, Janine W. Y.; Lucas, Christophe; Kölliker, Mathias

    2014-01-01

    The evolution of parent-offspring communication was mostly studied from the perspective of parents responding to begging signals conveying information about offspring condition. Parents should respond to begging because of the differential fitness returns obtained from their investment in offspring that differ in condition. For analogous reasons, offspring should adjust their behavior to cues/signals of parental condition: parents that differ in condition pay differential costs of care and, hence, should provide different amounts of food. In this study, we experimentally tested in the European earwig (Forficula auricularia) if cues of maternal condition affect offspring behavior in terms of sibling cannibalism. We experimentally manipulated female condition by providing them with different amounts of food, kept nymph condition constant, allowed for nymph exposure to chemical maternal cues over extended time, quantified nymph survival (deaths being due to cannibalism) and extracted and analyzed the females’ cuticular hydrocarbons (CHC). Nymph survival was significantly affected by chemical cues of maternal condition, and this effect depended on the timing of breeding. Cues of poor maternal condition enhanced nymph survival in early broods, but reduced nymph survival in late broods, and vice versa for cues of good condition. Furthermore, female condition affected the quantitative composition of their CHC profile which in turn predicted nymph survival patterns. Thus, earwig offspring are sensitive to chemical cues of maternal condition and nymphs from early and late broods show opposite reactions to the same chemical cues. Together with former evidence on maternal sensitivities to condition-dependent nymph chemical cues, our study shows context-dependent reciprocal information exchange about condition between earwig mothers and their offspring, potentially mediated by cuticular hydrocarbons. PMID:24498046

  7. Chitosan microparticles: influence of the gelation process on the release profile and oral bioavailability of albendazole, a class II compound.

    PubMed

    Piccirilli, Gisela N; García, Agustina; Leonardi, Darío; Mamprin, María E; Bolmaro, Raúl E; Salomón, Claudio J; Lamas, María C

    2014-11-01

    Encapsulation of albendazole, a class II compound, into polymeric microparticles based on chitosan-sodium lauryl sulfate was investigated as a strategy to improve drug dissolution and oral bioavailability. The microparticles were prepared by spray drying technique and further characterized by means of X-ray powder diffractometry, infrared spectroscopy and scanning electron microscopy. The formation of a novel polymeric structure between chitosan and sodium lauryl sulfate, after the internal or external gelation process, was observed by infrared spectroscopy. The efficiency of encapsulation was found to be between 60 and 85% depending on the internal or external gelation process. Almost spherically spray dried microparticles were observed using scanning electron microscopy. In vitro dissolution results indicated that the microparticles prepared by internal gelation released 8% of the drug within 30 min, while the microparticles prepared by external gelation released 67% within 30 min. It was observed that the AUC and Cmax values of ABZ from microparticles were greatly improved, in comparison with the non-encapsulated drug. In conclusion, the release properties and oral bioavailability of albendazole were greatly improved by using spraydried chitosan-sodium lauryl sulphate microparticles.

  8. Liposomal-encapsulated Ascorbic Acid: Influence on Vitamin C Bioavailability and Capacity to Protect Against Ischemia–Reperfusion Injury

    PubMed Central

    Davis, Janelle L.; Paris, Hunter L.; Beals, Joseph W.; Binns, Scott E.; Giordano, Gregory R.; Scalzo, Rebecca L.; Schweder, Melani M.; Blair, Emek; Bell, Christopher

    2016-01-01

    Intravenous administration of vitamin C has been shown to decrease oxidative stress and, in some instances, improve physiological function in adult humans. Oral vitamin C administration is typically less effective than intravenous, due in part to inferior vitamin C bioavailability. The purpose of this study was to determine the efficacy of oral delivery of vitamin C encapsulated in liposomes. On 4 separate randomly ordered occasions, 11 men and women were administered an oral placebo, or 4 g of vitamin C via oral, oral liposomal, or intravenous delivery. The data indicate that oral delivery of 4 g of vitamin C encapsulated in liposomes (1) produces circulating concentrations of vitamin C that are greater than unencapsulated oral but less than intravenous administration and (2) provides protection from ischemia–reperfusion-mediated oxidative stress that is similar to the protection provided by unencapsulated oral and intravenous administrations. PMID:27375360

  9. The Nutraceutical Bioavailability Classification Scheme: Classifying Nutraceuticals According to Factors Limiting their Oral Bioavailability.

    PubMed

    McClements, David Julian; Li, Fang; Xiao, Hang

    2015-01-01

    The oral bioavailability of a health-promoting dietary component (nutraceutical) may be limited by various physicochemical and physiological phenomena: liberation from food matrices, solubility in gastrointestinal fluids, interaction with gastrointestinal components, chemical degradation or metabolism, and epithelium cell permeability. Nutraceutical bioavailability can therefore be improved by designing food matrices that control their bioaccessibility (B*), absorption (A*), and transformation (T*) within the gastrointestinal tract (GIT). This article reviews the major factors influencing the gastrointestinal fate of nutraceuticals, and then uses this information to develop a new scheme to classify the major factors limiting nutraceutical bioavailability: the nutraceutical bioavailability classification scheme (NuBACS). This new scheme is analogous to the biopharmaceutical classification scheme (BCS) used by the pharmaceutical industry to classify drug bioavailability, but it contains additional factors important for understanding nutraceutical bioavailability in foods. The article also highlights potential strategies for increasing the oral bioavailability of nutraceuticals based on their NuBACS designation (B*A*T*).

  10. El Nino. [influence on climatic conditions

    NASA Technical Reports Server (NTRS)

    Cane, M. A.

    1986-01-01

    An attempt is made to provide the background for a coupled model of ENSO (El Nino-Southern Oscillation) with emphasis placed on the oceanography (i.e. on El Nino). Observations of the normal annual cycle in the Pacific and of the evolution of a typical El Nino event are reviewed, and a theory for the oceanography of El Nino is proposed. The influence of SST anomalies on the tropical atmosphere is assessed, and results from a numerical model for the coupled system able to generate El Nino events are presented. Implications for the real ENSO cycle are discussed. In both the model and nature, ENSO has the character of a relaxation oscillation of the coupled system, and its cycle is aperiodic. Results on the predictability of dynamical systems show the impossibility of predicting ahead several events.

  11. Influence of particle surfaces on the bioavailability to different species of 2,4-dichlorophenol and pentachlorophenol

    SciTech Connect

    Davies, N.A.; Edwards, P.A.; Lawrence, M.A.M.; Taylor, M.G.; Simkiss, K. . School of Animal and Microbial Sciences)

    1999-07-15

    Studies on the bioavailability of contaminants that accumulate in sediments have been complicated by the chemical and structural variability of substrates and by the different biological properties of test organisms that are used by regulators. The purpose of this work was to overcome some of these difficulties by devising a test system that used artificial particles with known chemical surfaces. These were coated with 2,4-dichlorophenol or pentachlorophenol and fed to oligochete worms (Lumbriculus variegatus) and midge larvae (Chironimus riparius). The adsorption coefficient (K[sub d]) of the particle surface was compared with the concentration of contaminant accumulated by the test organisms. There were major differences in bioaccumulation between the two species used despite identical particles and pollutants. This clearly reflects differences in the uptake and detoxification pathways between species. The particle surface and its interaction with the chlorophenols was a major factor in the accumulation of the contaminants in an organism. The techniques that are described provide a way of standardizing results between different natural sediments and different test organisms and provide some insights into the processes involved in bioaccumulation from particle surfaces.

  12. Glucosinolates in Brassica vegetables: the influence of the food supply chain on intake, bioavailability and human health.

    PubMed

    Verkerk, Ruud; Schreiner, Monika; Krumbein, Angelika; Ciska, Ewa; Holst, Birgit; Rowland, Ian; De Schrijver, Remi; Hansen, Magnor; Gerhäuser, Clarissa; Mithen, Richard; Dekker, Matthijs

    2009-09-01

    Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

  13. Influences of bioavailability, trophic position, and growth on methylmercury in hakes (Merluccius merluccius) from Northwestern Mediterranean and Northeastern Atlantic.

    PubMed

    Cossa, D; Harmelin-Vivien, M; Mellon-Duval, C; Loizeau, V; Averty, B; Crochet, S; Chou, L; Cadiou, J-F

    2012-05-01

    Methylmercury (MeHg) determinations in hake, its food-chain, and the surrounding waters and sediments allowed us to show that the higher length or age normalized mercury concentrations of Northwestern Mediterranean (Gulf of Lions: GoL) muscle hakes compared to its Northeastern Atlantic (Bay of Biscay: BoB) counterpart are due to both biotic and abiotic differences between their ecosystems. Bioenergetic modeling reveals that the slower growth rate of Mediterranean hake favors the MeHg bioaccumulation in the fish muscle and explains most of the difference between GOL and BoB hake populations. In addition, the waters of the Mediterranean hake habitat favor a higher MeHg exposition, due to the upper position of the thermohalocline, where MeHg is formed. Furthermore, we show that, within the Mediterranean hake population, a major increase in the biomagnification power (the slope of the relationships between logMeHg and δ(15)N), from 0.36 up to 1.12, occurs when individuals enter adulthood, resulting from the combined effects of lowering growth rate and change in feeding habits. Finally, δ(15)N normalized Hg concentrations indicate that the highest Hg concentrations are for hake from the shelf edge and the lowest are for hake from the Rhône prodelta area, suggesting a lower Hg bioavailability in inshore environments, consistent with MeHg distributions in water, sediment, and preys.

  14. Influence of diets rich in Maillard reaction products on calcium bioavailability. Assays in male adolescents and in Caco-2 cells.

    PubMed

    Mesías, Marta; Seiquer, Isabel; Navarro, María Pilar

    2009-10-28

    The effects of the high intake of Maillard reaction products (MRP) on calcium availability in adolescents and across Caco-2 cell monolayers were examined. In a 2 week randomized two-period crossover trial, 18 male adolescents consumed two diets, named white diet (WD) and brown diet (BD), which were poor and rich in MRP, respectively. A 3 day balance was performed at the end of each period, and fasting blood samples were collected. Calcium solubility and absorption across Caco-2 cells were studied after the in vitro digestion of the diets. The in vitro assay showed similar solubility after the in vitro digestion and similar transport across Caco-2 cells. In accordance, calcium bioavailability in adolescents did not vary between the diets (%WD = 40.4 +/- 5.1, %BD = 38.2 +/- 3.6). Serum and urine biochemical parameters related to calcium status and bone metabolism remained unaltered. Only deoxypyridinoline values were significantly lower after consumption of the BD (13.0 +/- 1.1 compared to 18.3 +/- 2.1 nM/Mm Cr in the WD), possibly indicative of less efficient bone turnover during this period. As calcium acquired during adolescence is essential to maximize peak bone mass and to prevent osteoporosis, possible long-term effects of excessive MRP intake during this period warrant attention.

  15. [Physicochemical and microbiological factors influencing the bioavailability of organic contaminants in subsoils]. Progress report, [July 1, 1992--June 30, 1993

    SciTech Connect

    Not Available

    1992-12-31

    We report progress in elucidating the microbiological variables important in determining the relative success of bacteria in utilizing soil-sorbed contaminants. Two bacterial species, Pseudomonas putida (ATCC 17484) and an Alcaligenes sp. isolated from petroleum contaminated soil are known to differ markedly in their ability to utilize soil-sorbed napthalene based on a kinetic comparison of their capability of naphthalene mineralization in soil-containing and soil-free systems. The kinetic analysis led us to conclude that strain 17484 had direct access to naphthalene present in a labile sorbed state which promoted the rapid desorption of naphthalene from the non-labile phase. Conversely, both the rate and extent of naphthalene mineralization by strain NP-Alk suggested that this organism had access only to naphthalene in solution. Desorption was thus limited and the efficiency of total naphthalene removal from these soil slurries was poor. These conclusions were based on the average activities of cells in soil slurries without regard for the disposition of the organisms with respect to the sorbent. Since both organisms degrade naphthalene by apparently identical biochemical pathways, have similar enzyme kinetic properties, and are both motile, gram negative organisms, we undertook a series of investigations to gain a better understanding of what microbiological properties were important in bioavailability.

  16. The Influence of Iron and Zinc Supplementation on the Bioavailability of Provitamin A Carotenoids from Papaya Following Consumption of a Vitamin A-Deficient Diet.

    PubMed

    Kana-Sop, Marie Modestine; Gouado, Inocent; Achu, Mercy Bih; Van Camp, John; Amvam Zollo, Paul Henri; Schweigert, Florian J; Oberleas, Donald; Ekoe, Tetanye

    2015-01-01

    Iron deficiency anemia, zinc and vitamin A deficiencies are serious public health problems in Cameroon, as in many developing countries. Local vegetables which are sources of provitamin A carotenoids (PACs) can be used to improve vitamin A intakes. However, traditional meals are often unable to cover zinc and iron needs. The aim of this study was to determine the bioavailability of 3 PACs (α-carotene, β-carotene, and β-cryptoxanthin) in young men, who were fed with a vitamin A-free diet and received iron and zinc supplementation. Twelve healthy participants were divided into three groups and were supplemented with elemental iron (20 mg of iron fumarate), 20 mg of zinc sulfate or iron+zinc (20 mg of iron in the morning and 20 mg of zinc in the evening) for 11 d. They were given a vitamin A- and PAC-free diet from the 6th to the 11th day, followed by a test meal containing 0.55 kg of freshly peeled papaya as a source of PACs. Blood samples were collected four times successively on the 11th day (the test meal day), at T0 (just after the test meal), after 2 h (T2), after 4 h (T4) and after 7 h (T7). Ultracentrifugation was used to isolate serum chylomicrons. Retinol appearance and PAC postprandial concentrations were determined. The supplementation with zinc, iron and iron+zinc influenced the chylomicron appearance of retinol and PACs differently as reflected by retention times and maximum absorption peaks. Iron led to highest retinol levels in the chylomicron. Zinc and iron+zinc supplements were best for optimal intact appearance of α-carotene, β-carotene and β-cryptoxanthin respectively. Supplementation with iron led to the greatest bioavailability of PACs from papaya and its conversion to retinol.

  17. The influence of metal speciation on the bioavailability and sub-cellular distribution of cadmium to the terrestrial isopod, Porcellio dilatatus.

    PubMed

    Calhôa, Carla Filipa; Monteiro, Marta S; Soares, Amadeu M V M; Mann, Reinier M

    2011-04-01

    Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd(2+). Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-cellular distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO(3))(2) (64%, SE=5%) was higher than AE for isopods fed with Cd(Cys)(2) (20%, SE=3%). The sub-cellular distribution also depended on the Cd species provided. Those isopods fed Cd(Cys)(2) allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-cellular distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod.

  18. The influence of reactive oxygen species on local redox conditions in oxygenated natural waters

    NASA Astrophysics Data System (ADS)

    Rose, Andrew

    2016-11-01

    Redox conditions in natural waters are a fundamental control on biogeochemical processes and ultimately many ecosystem functions. While the dioxygen/water redox couple controls redox thermodynamics in oxygenated aquatic environments on geological timescales, it is kinetically inert in the extracellular environment on the much shorter timescales on which many biogeochemical processes occur. Instead, electron transfer processes on these timescales are primarily mediated by a relatively small group of trace metals and stable radicals, including the reactive oxygen species superoxide. Such processes are of critical biogeochemical importance because many of these chemical species are scarce nutrients, but may also be toxic at high concentrations. Furthermore, their bioavailability and potentially toxicity is typically strongly influenced by their redox state. In this paper, I examine to what extent redox conditions in oxygenated natural waters are expected to be reflected in the redox states of labile redox-active compounds that readily exchange electrons with the dioxygen/superoxide redox couple, and potentially with each other. Additionally, I present the hypothesis that that the relative importance of the dioxygen/superoxide and superoxide/hydrogen peroxide redox couples exerts a governing control on local redox conditions in oxygenated natural waters on biogeochemically important timescales. Given the recent discovery of widespread extracellular superoxide production by a diverse range of organisms, this suggests the existence of a fundamental mechanism for organisms to tightly regulate local redox conditions in their extracellular environment in oxygenated natural waters.

  19. Influence of weather-climatic conditions on biospheric processes

    NASA Astrophysics Data System (ADS)

    Govorushko, S. M.

    2012-12-01

    The significance of meteorological processes and phenomena in the biosphere functioning is revealed. The influence of various weather conditions on human health is considered; the factors and mechanisms of their action are described. The impact of meteorological processes on animals is discussed and concrete examples of such impacts are presented. The influence of meteorological processes and phenomena on plants at different stages of their life (pollination, growth, ripening, transport of seeds, damage, and death) and on some abiotic natural components is shown. It is inferred that weather-climatic conditions have a great influence on biospheric processes.

  20. Metal-solid interactions controlling the bioavailability of mercury from sediments to clams and sipunculans.

    PubMed

    Zhong, Huan; Wang, Wen-Xiong

    2006-06-15

    The bioavailability of sedimentary Hg(II) and methylmercury (MeHg) was quantified by measuring the assimilation efficiency (AE) in the clam Ruditapes philippinarum and the extraction of the gut juices from the sipunculan Sipunculus nudus. Three factors (Hg concentration in sediment, Hg sediment contact time, and organic content of sediments) were modified to examine metal-solid interactions in controlling Hg bioavailability. The Hg AEs in the clams were strongly correlated with the extraction from the sipunculan gut juices for both Hg species. The bioavailability of both Hg(II) and MeHg generally increased with increased sediment Hg concentration but decreased with sedimentmetal contact time and increasing organic content (except that MeHg was not influenced by organic content). Hg(II) speciation in sediments, quantified by sequential chemical extraction (SCE), was dependent on geochemical conditions and greatly controlled the mobility and bioavailability of Hg(II) in sediments. Most bioavailable Hg(II) originated from the strongly complexed phase (e.g., Hg bound up in Fe/Mn oxide, amorphous organosulfur, or mineral lattice), whereas Hg bound with the organocomplexed phase (Hg humic and Hg2Cl2) was not bioavailable. Hg bound with the other geochemical phases (water soluble, HgO, HgSO4, and HgS) contributed very little to the bioavailable Hg due to their low partitionings. Further, the amount of bioavailable Hg was inversely related to the particle reactivity of Hg with the sediments. Detailed analyses of metal-solid interactions provide a better understanding of how Hg in sediments can predict Hg concentration and therefore bioavailability in benthic invertebrates.

  1. Learning to Coach through Experience: Conditions that Influence Reflection

    ERIC Educational Resources Information Center

    Gilbert, Wade D.; Trudel, Pierre

    2005-01-01

    The goal of the present article is to describe conditions that influence coach reflection, and to provide suggestions for nurturing coach reflection. Coach reflection varies based on the interaction of four conditions: (a) peer access, (b) stage of learning, (c) issue characteristics, and (d) environment. Data are presented to support the four…

  2. The influence of urea and nitrate nutrients on the bioavailability and toxicity of nickel to Prorocentrum donghaiense (Dinophyta) and Skeletonema costatum (Bacillariophyta).

    PubMed

    Huang, Xu-Guang; Lin, Xie-Chang; Li, Shun-Xing; Xu, Song-Li; Liu, Feng-Jiao

    2016-12-01

    Nitrogen nutrients and nickel(Ni) are ubiquitous in aquatic environments, and they are important for primary production of ocean ecosystem. This study examined the interaction of nitrogen nutrients (specifically urea and nitrate) and Ni on chlorophyll (Chl a) concentration and photosynthesis parameters values of Prorocentrum donghaiense and Skeletonema costatum. The data presented here indicate that low concentration of Ni for P. donghaiense and S. costatum can enhance both Chl a concentration and photosynthesis parameters values when grown in urea containing environment. Despite this increase there was also an observed depression in both species tested when incubated in high concentration of Ni for P. donghaiense and S. costatum regardless of incubating in urea or nitrate. Additionally, EC50 values of Chl a and Fv/Fm for Ni at different time intervals were calculated in this study. These observations indicated that the Ni tolerance was higher in P. donghaiense as compared to S. costatum. The Ni tolerance of P. donghaiense incubated in urea was higher than that incubating in nitrate. The same phenomenon was not observed in S. costatum, which indicated that the influence of urea was dependent on the species investigated. Thus, urea input could impact Ni bioavailability and toxicity, and then affect the biodynamics thereafter.

  3. An in vitro digestion test that reflects rat intestinal conditions to probe the importance of formulation digestion vs first pass metabolism in Danazol bioavailability from lipid based formulations.

    PubMed

    Anby, Mette U; Nguyen, Tri-Hung; Yeap, Yan Yan; Feeney, Orlagh M; Williams, Hywel D; Benameur, Hassan; Pouton, Colin W; Porter, Christopher J H

    2014-11-03

    The impact of gastrointestinal (GI) processing and first pass metabolism on danazol oral bioavailability (BA) was evaluated after administration of self-emulsifying drug delivery systems (SEDDS) in the rat. Danazol absolute BA was determined following oral and intraduodenal (ID) administration of LFCS class IIIA medium chain (MC) formulations at high (SEDDSH-III) and low (SEDDSL-III) drug loading and a lipid free LFCS class IV formulation (SEDDS-IV). Experiments were conducted in the presence and absence of ABT (1-aminobenzotriazole) to evaluate the effect of first pass metabolism. A series of modified in vitro lipolysis tests were developed to better understand the in vivo processing of SEDDS in the rat. Danazol BA was low (<13%) following oral and ID administration of either SEDDS. Increasing drug loading, ID rather than oral administration, and administration of SEDDS-IV rather than SEDDS-III led to higher oral BA. After pretreatment with ABT, however, danazol oral BA significantly increased (e.g., 60% compared to 2% after administration of SEDDSL-III), no effect was observed on increasing drug loading, and differences between SEDDS-III and -IV were minimal. In vitro digestion models based on the lower enzyme activity and lower dilution conditions expected in the rat resulted in significantly reduced danazol precipitation from SEDDS-III or SEDDS-IV on initiation of digestion. At the doses administered here (4-8 mg/kg), the primary limitation to danazol oral BA in the rat was first pass metabolism, and the fraction absorbed was >45% after oral administration of SEDDS-III or SEDDS-IV. In contrast, previous studies in dogs suggest that danazol BA is less dependent on first pass metabolism and more sensitive to changes in formulation processing. In vitro digestion models based on likely rat GI conditions suggest less drug precipitation on formulation digestion when compared to equivalent dog models, consistent with the increases in in vivo exposure (fraction

  4. Enhanced ferrihydrite dissolution by a unicellular, planktonic cyanobacterium: a biological contribution to particulate iron bioavailability.

    PubMed

    Kranzler, Chana; Kessler, Nivi; Keren, Nir; Shaked, Yeala

    2016-12-01

    Iron (Fe) bioavailability, as determined by its sources, sinks, solubility and speciation, places severe environmental constraints on microorganisms in aquatic environments. Cyanobacteria are a widespread group of aquatic, photosynthetic microorganisms with especially high iron requirements. While iron exists predominantly in particulate form, little is known about its bioavailability to cyanobacteria. Some cyanobacteria secrete iron solubilizing ligands called siderophores, yet many environmentally relevant strains do not have this ability. This work explores the bioavailability of amorphous synthetic Fe-oxides (ferrihydrite) to the non-siderophore producing, unicellular cyanobacterium, Synechocystis sp PCC 6803. Iron uptake assays with (55) ferrihydrite established dissolution as a critical prerequisite for iron transport. Dissolution assays with the iron binding ligand, desferrioxamine B, demonstrated that Synechocystis 6803 enhances ferrihydrite dissolution, exerting siderophore-independent biological influence on ferrihydrite bioavailability. Dissolution mechanisms were studied using a range of experimental conditions; both cell-particle physical proximity and cellular electron flow were shown to be important determinants of bio-dissolution by Synechocystis 6803. Finally, the effects of ferrihydrite stability on bio-dissolution rates and cell physiology were measured, integrating biological and chemical aspects of ferrihydrite bioavailability. Collectively, these findings demonstrate that Synechocystis 6803 actively dissolves ferrihydrite, highlighting a significant biological component to mineral phase iron bioavailability in aquatic environments.

  5. Influencing and Facilitating Conditions for Developing Reflective Assessment Practice

    ERIC Educational Resources Information Center

    Rønsen, Anne Kristin; Smith, Kari

    2014-01-01

    By following a professional development project focusing on enhancing assessment competence amongst teachers, the current study examines how teachers use reflective writing and systematic discussions as tools for developing competence in assessment. More specifically, the article aims at identifying conditions that influence and facilitate…

  6. Flavonoid Bioavailability and Attempts for Bioavailability Enhancement

    PubMed Central

    Thilakarathna, Surangi H.; Rupasinghe, H. P. Vasantha

    2013-01-01

    Flavonoids are a group of phytochemicals that have shown numerous health effects and have therefore been studied extensively. Of the six common food flavonoid classes, flavonols are distributed ubiquitously among different plant foods whereas appreciable amounts of isoflavones are found in leguminous plant-based foods. Flavonoids have shown promising health promoting effects in human cell culture, experimental animal and human clinical studies. They have shown antioxidant, hypocholesterolemic, anti-inflammatory effects as well as ability to modulate cell signaling and gene expression related disease development. Low bioavailability of flavonoids has been a concern as it can limit or even hinder their health effects. Therefore, attempts to improve their bioavailability in order to improve the efficacy of flavonoids are being studied. Further investigations on bioavailability are warranted as it is a determining factor for flavonoid biological activity. PMID:23989753

  7. Influences of acidic conditions on formazan assay: a cautionary note.

    PubMed

    Johno, Hisashi; Takahashi, Shuhei; Kitamura, Masanori

    2010-11-01

    Formazan assay has been used for several decades to evaluate metabolic activity of eukaryotic and prokaryotic cells. In particular, it has been often applied for quantitative assessment of viable cells under acidic circumstances caused by, e.g., ischemia and hypoxia. However, little attention has been paid to the influence of acidic pH on formazan assays. We found that acidic culture conditions significantly affect outcomes of the assays. Absorbance of tetrazolium-formazan decreased in a pH-dependent manner without affecting cell viability. This nonspecific effect was ascribed to influences of acidic pH on the production of formazan. Replacement of culture media to fresh medium at physiologic pH partially overcame this problem. The influence of acidic culture conditions should be carefully considered when formazan assays are used for the assessment of viable cells under various experimental situations.

  8. Growth conditions influence the melatonin content of tomato plants.

    PubMed

    Arnao, Marino Bañón; Hernández-Ruiz, Josefa

    2013-06-01

    Melatonin (N-acetyl-5-methoxytryptamine) is an interesting molecule with well-known functions in vertebrates. Since its discovery in plants in 1995, many data indicate that its role as a cellular antioxidant is very relevant. Agents that induce stress cause increased melatonin levels in plant organs and melatonin levels fluctuate over the light:dark cycle; there are also conflicting data on the influence of environmental conditions on the melatonin content of plants. In this contribution we describe how cultivation conditions decisively influence melatonin levels in roots, stems and leaves of tomato plants, and we establish some guidelines for interpreting data with the intention of opening up new discussion options, given the lack of data on the place/s of melatonin biosynthesis and its mode of action in plant cells as an antioxidant.

  9. Dietary factors affecting polyphenol bioavailability.

    PubMed

    Bohn, Torsten

    2014-07-01

    While many epidemiological studies have associated the consumption of polyphenols within fruits and vegetables with a decreased risk of developing several chronic diseases, intervention studies have generally not confirmed these beneficial effects. The reasons for this discrepancy are not fully understood but include potential differences in dosing, interaction with the food matrix, and differences in polyphenol bioavailability. In addition to endogenous factors such as microbiota and digestive enzymes, the food matrix can also considerably affect bioaccessibility, uptake, and further metabolism of polyphenols. While dietary fiber (such as hemicellulose), divalent minerals, and viscous and protein-rich meals are likely to cause detrimental effects on polyphenol bioaccessibility, digestible carbohydrates, dietary lipids (especially for hydrophobic polyphenols, e.g., curcumin), and additional antioxidants may enhance polyphenol availability. Following epithelial uptake, polyphenols such as flavonoids may reduce phase II metabolism and excretion, enhancing polyphenol bioavailability. Furthermore, polyphenols may act synergistically due to their influence on efflux transporters such as p-glycoprotein. In order to understand polyphenol bioactivity, increased knowledge of the factors affecting polyphenol bioavailability, including dietary factors, is paramount.

  10. Concentration-dependent degradation of three termiticides in soil under laboratory conditions and their bioavailability to eastern subterranean termites (Isoptera: Rhinotermitidae).

    PubMed

    Saran, Raj K; Kamble, Shripat T

    2008-08-01

    Degradation and bioavailability of imidacloprid, fipronil, and bifenthrin applied at label rates ([AI], wt:wt in soil) in the loamy soil of Nebraska were determined over a 6-mo duration. Based on the calculated half-lives of the three termiticides, it was concluded that the degradation rate was lowest when a termiticide was applied at the highest label rate. Bioassays of Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) conducted at 8, 31, 65, 90, 135, 160, and 180 d posttreatment showed an inverse relationship between the LT90 values and the variable concentrations. At day 180, exposures to all the termiticide-treated soil samples (concentration x termiticide) resulted in 100% mortality of R. flavipes workers. However, lower LT90 values were observed for termites exposed to soils treated with highest label rates even when the treated soils were aged in the lab for 6 mo. This suggested a higher bioavailability of these three termiticides when applied at higher application rates. Termite mortality was fastest for bifenthrin followed by fipronil and imidacloprid.

  11. Conditions for Viral Influence Spreading through Multiplex Correlated Social Networks

    NASA Astrophysics Data System (ADS)

    Hu, Yanqing; Havlin, Shlomo; Makse, Hernán A.

    2014-04-01

    A fundamental problem in network science is to predict how certain individuals are able to initiate new networks to spring up "new ideas." Frequently, these changes in trends are triggered by a few innovators who rapidly impose their ideas through "viral" influence spreading, producing cascades of followers and fragmenting an old network to create a new one. Typical examples include the rise of scientific ideas or abrupt changes in social media, like the rise of Facebook to the detriment of Myspace. How this process arises in practice has not been conclusively demonstrated. Here, we show that a condition for sustaining a viral spreading process is the existence of a multiplex-correlated graph with hidden "influence links." Analytical solutions predict percolation-phase transitions, either abrupt or continuous, where networks are disintegrated through viral cascades of followers, as in empirical data. Our modeling predicts the strict conditions to sustain a large viral spreading via a scaling form of the local correlation function between multilayers, which we also confirm empirically. Ultimately, the theory predicts the conditions for viral cascading in a large class of multiplex networks ranging from social to financial systems and markets.

  12. Phoning while driving II: a review of driving conditions influence.

    PubMed

    Collet, C; Guillot, A; Petit, C

    2010-05-01

    The first paper examined how the variables related to driving performance were impacted by the management of holding a phone conversation. However, the conditions under which this dual task is carried out are dependent upon a set of factors that may particularly influence the risk of crash. These conditions are defined by several independent variables, classified into five main categories: i) legislation; ii) phone type (hands-free or hand-held); iii) drivers' features regarding age, gender, personal individual profile and driving experience; iv) conversation content (casual or professional) and its context (held with passengers or with a cell (mobile) phone); v) driving conditions (actual or simulated driving, road type, traffic density and weather). These independent variables determine the general conditions. The way in which these factors are combined and interact one with another thus determines the risk that drivers undergo when a cell phone is used while driving. Finally, this review defined the general conditions of driving for which managing a phone conversation is likely to elicit a high risk of car crash or, conversely, may provide a situation of lower risk, with sufficient acceptance to ensure safety.

  13. Influence of gastrointestinal digestion and edible plant combination on oral bioavailability of triterpene saponins, using a biomimetic digestion and absorption system and determination by HPLC.

    PubMed

    Li, Shun-Xing; Mu, Yang; Zheng, Feng-Ying

    2013-11-06

    Saponins have many biological activities, but their overload could cause toxicity to the human body. Bionic gastrointestinal digestion and monolayer liposome extraction were used for oral bioavailability assessment of triterpene saponins (notoginsenoside R1, ginsenosides Rb1 and Rd1) in an edible herb (San-Chi) and its compound herbal medicine (Pien Tze Huang, PZH). The concentrations of affinity-monolayer liposome saponins in the chyme were determined by HPLC and used for oral bioavailability assessment. With the digestion of San-Chi and PZH from the stomach to the intestine, the release of saponins in their chyme was increased. The intestinal absorption ratios of N-R1, G-Rb1, G-Rd1, and total saponins from San-Chi were 86.57, 18.56, 73.30, and 40.20%, respectively, which were more than those from PZH (i.e., 19.56, 10.11, 30.11, and 16.08%). The oral bioavailability of saponins was controlled by saponin species, gastrointestinal digestion, and edible plants combination.

  14. Modeling and interpreting bioavailability of organic contaminant mixtures in subsurface environments

    NASA Astrophysics Data System (ADS)

    Haws, Nathan W.; Ball, William P.; Bouwer, Edward J.

    2006-01-01

    Bioavailability often controls the fate of organic contaminants in surface and subsurface aquatic environments. Bioavailability can be limited by sorption, mass transfer, and intrinsic biodegradation potential and can be further altered by the presence of other compounds. This paper reviews current perspectives on the processes influencing subsurface contaminant bioavailability, how these processes are modeled, and how the relative role of the various processes can be assessed through bioavailability indices. Although these processes are increasingly well understood, the use of sophisticated models and indices often are precluded by an inability to estimate the many parameters that are associated with complex models. Nonetheless, the proper representation of sorption, mass transfer, biodegradation, and co-solute effects can be critical in predicting bio-attenuation. The influence of these processes on contaminant fate is illustrated with numerical simulations for the simultaneous degradation of toluene (growth substrate) and trichloroethylene (nongrowth cometabolite) in hypothetical, aerobic, solid-water systems. The results show how the relative impacts on contaminant fate of the model's various component processes depends upon system conditions, including co-solute concentrations. Slow biodegradation rates increase the inhibition effects of a cometabolite and suppress the rate enhancement effects of a growth substrate. Irrespective of co-solute effects, contaminant fate is less sensitive to biodegradation processes in systems with strong sorption and slow desorption rates. Bioavailability indices can be used to relate these findings and to help identify appropriate modeling simplifications. In general, however, there remains a need to redefine such indices in order that bioavailability concepts can be better incorporated into site characterization, remediation design, and regulatory oversight.

  15. Bioavailability of Micronutrients from Plant Foods: An Update.

    PubMed

    Platel, Kalpana; Srinivasan, Krishnapura

    2016-07-26

    Deficiencies of iron, zinc, iodine and vitamin A are widespread in the developing countries, poor bioavailability of these micronutrients from plant-based foods being the major reason for their wide prevalence. Diets predominantly vegetarian are composed of components that enhance as well as inhibit mineral bioavailability, the latter being predominant. However, prudent cooking practices and use of ideal combinations of food components can significantly improve micronutrient bioavailability. Household processing such as heat treatment, sprouting, fermentation and malting have been evidenced to enhance the bioavailability of iron and β-carotene from plant foods. Food acidulants amchur and lime are also shown to enhance the bioavailability of not only iron and zinc, but also of β-carotene. Recently indentified newer enhancers of micronutrient bioaccessibility include sulphur compound-rich Allium spices-onion and garlic, which also possess antioxidant properties, β-carotene-rich vegetables-carrot and amaranth, and pungent spices-pepper (both red and black) as well as ginger. Information on the beneficial effect of these dietary compounds on micronutrient bioaccessibility is novel. These food components evidenced to improve the bioavailability of micronutrients are common ingredients of Indian culinary, and probably of other tropical countries. Fruits such as mango and papaya, when consumed in combination with milk, provide significantly higher amounts of bioavailable β-carotene. Awareness of the beneficial influence of these common dietary ingredients on the bioavailability of micronutrients would help in devising dietary strategies to improve the bioavailability of these vital nutrients.

  16. Influence of overconsolidated condition on permeability evolution in silica sand

    NASA Astrophysics Data System (ADS)

    Kimura, S.; Kaneko, H.; Ito, T.; Nishimura, O.; Minagawa, H.

    2013-12-01

    Permeability of sediments is important factors for production of natural gas from natural gas hydrate bearing layers. Methane-hydrate is regarded as one of the potential resources of natural gas. As results of coring and logging, the existence of a large amount of methane-hydrate is estimated in the Nankai Trough, offshore central Japan, where many folds and faults have been observed. In the present study, we investigate the permeability of silica sand specimen forming the artificial fault zone after large displacement shear in the ring-shear test under two different normal consolidated and overconsolidated conditions. The significant influence of overconsolidation ratio (OCR) on permeability evolution is not found. The permeability reduction is influenced a great deal by the magnitude of normal stress during large displacement shearing. The grain size distribution and structure observation in the shear zone of specimen after shearing at each normal stress level are analyzed by laser scattering type particle analyzer and scanning electron microscope, respectively. It is indicated that the grain size and porosity reduction due to the particle crushing are the factor of the permeability reduction. This study is financially supported by METI and Research Consortium for Methane Hydrate Resources in Japan (the MH21 Research Consortium).

  17. Pharmacokinetics and bioavailability of drotaverine in humans.

    PubMed

    Bolaji, O O; Onyeji, C O; Ogundaini, A O; Olugbade, T A; Ogunbona, F A

    1996-01-01

    The pharmacokinetics and bioavailability of drotaverine was studied in 10 healthy volunteers after administration of single 80 mg oral and intravenous doses of the HCl salt of the drug, in a crossover fashion. Plasma and urine samples were analyzed for the unchanged drug by HPLC. The pharmacokinetic parameters, such as elimination half-life, plasma clearance, renal clearance and apparent volume of distribution, were not influenced by the route of drug administration. The drug was mainly eliminated by non-renal routes since renal clearance accounted for only 0.31 +/- 0.13% of the total plasma clearance. The absolute bioavailability was variable and ranged from 24.5-91% with a mean of 58.2 +/- 18.2% (mean +/- SD). It is suggested that the high variation in the bioavailability of drotaverine HCl after oral administration may result in significant interindividual differences in therapeutic response.

  18. Arsenic Bioavailability, Bioaccessibility, And Speciation

    EPA Science Inventory

    The term bioavailability has many different meanings across various disciplines. Often bioavailability is concerned with human health aspects such as the case of urban children interacting with contaminated soil. The still utilized approach to base risk assessment on total meta...

  19. Influence of Spanwise Boundary Conditions on Slat Noise Simulations

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Choudhari, Meelan M.; Buning, Pieter G.

    2015-01-01

    The slat noise from the 30P/30N high-lift system is being investigated through computational fluid dynamics simulations with the OVERFLOW code in conjunction with a Ffowcs Williams-Hawkings acoustics solver. In the present study, two different spanwise grids are being used to investigate the effect of the spanwise extent and periodicity on the near-field unsteady structures and radiated noise. The baseline grid with periodic boundary conditions has a short span equal to 1/9th of the stowed chord, whereas the other, longer span grid adds stretched grids on both sides of the core, baseline grid to allow inviscid surface boundary conditions at both ends. The results indicate that the near-field mean statistics obtained using the two grids are similar to each other, as are the directivity and spectral shapes of the radiated noise. However, periodicity forces all acoustic waves with less than one wavelength across the span to be two-dimensional, without any variation in the span. The spanwise coherence of the acoustic waves is what is needed to make estimates of the noise that would be radiated from realistic span lengths. Simulations with periodic conditions need spans of at least six slat chords to allow spanwise variation in the low-frequencies associated with the peak of broadband slat noise. Even then, the full influence of the periodicity is unclear, so employing grids with a fine, central region and highly stretched meshes that go to slip walls may be a more efficient means of capturing the spanwise decorrelation of low-frequency acoustic phenomena.

  20. Thermodynamically Correct Bioavailability Estimations

    DTIC Science & Technology

    1992-04-30

    6448 I 1. SWPPUMENTA* NOTIS lIa. OISTUAMJTiOAVAILAIILTY STATIMENT 121 OT REbT ostwosCo z I Approved for public release; distribution unlimited... research is to develop thermodynamically correct bioavailability estimations using chromatographic stationary phases as a model of the "interphase

  1. Anthocyanins in purple-orange carrots (Daucus carota L.) do not influence the bioavailability of beta-carotene in young women.

    PubMed

    Arscott, Sara A; Simon, Philipp W; Tanumihardjo, Sherry A

    2010-03-10

    Purple carrots contain anthocyanins in addition to the provitamin A carotenoids in typical orange carrots. Simultaneous consumption of these phytochemicals in carrots may affect the bioavailability of carotenoids. The bioavailability of beta-carotene in humans was assessed from an acute feeding of orange (OC) and purple (PC) carrots with white (WC) as a control. Carrot smoothies were served to female subjects (n = 5, aged 21-26 years) for breakfast after 1 week on a low carotenoid diet and overnight fast. OC and PC smoothies were equalized to 10.3 mg of all-trans beta-carotene. Plasma beta-carotene was measured for 144 h following treatments. Peak plasma concentrations of OC and PC treatments did not differ. The PC treatment 0-144 h area-under-the-curve for beta-carotene was 76% of the OC treatment (P < 0.05). However, when the first 24 h were compared, OC and PC treatments did not differ, suggesting that anthocyanins in purple carrots do not affect the absorption of beta-carotene postprandially.

  2. Significant Events or Persons Influencing College Decisions of Conditionally-admitted and Early-Admitted Freshmen.

    ERIC Educational Resources Information Center

    Nieves, Edwin; Hartman, Kathleen

    2001-01-01

    Examines reasons cited by conditionally-admitted and early-admitted freshmen for choosing to attend college. Finds that parents and family had the greatest influence on both groups; however, the conditionally-admitted students cited these influences more often as the primary influence. Discusses other influences cited by both groups, such as…

  3. The Influence of Soil Properties and Local Characteristics on the Distribution, Migration and Potential Bioavailability of Radio-Cesium in Bavarian Forest Ecosystems More Than 20 Years After the Chernobyl Accident

    NASA Astrophysics Data System (ADS)

    Winkelbauer, J.; Voelkel, J.; Leopold, M.; Huerkamp, K.; Dehos, R.

    2008-12-01

    Soil properties and local characteristics of landscapes and ecosystems influence the behaviour of Radio- Cesium. Humic horizons are a main factor in understanding the migration and potential bioavailability of radio-nuclides in soils. Until 1962 and in the year 1986, nuclear arms tests in the Pacific and the Chernobyl reactor accident emitted persistent radionuclides in the atmosphere that are stored in several European ecosystems. Short-term high as well as long-term low immissions lead to enrichments and increasing contamination of the environment up to superposition effects in certain ecosystems. South German forest ecosystems like the Bavarian Forest or the Northern pre-Alps are subareas of the cesium fallout affected sites after the Chernobyl accident. Cesium-137 is constantly contained in the vegetation and food chain in spite of decreasing local doses. Investigations have shown that the enrichment of cesium is mainly restricted to the organic top layers of the forest soils. Examples of several Bavarian forest ecosystems are given. Horizontal and vertical forest soil distributions of the cesium contamination and its bioavailability were determined to provide a default-document how to act in case of a repetition of a nuclear accident. Such a guideline has been created by order of the Bavarian State Government and its scope is presented here.

  4. The influence of scaffold material on chondrocytes under inflammatory conditions.

    PubMed

    Kwon, Heenam; Sun, Lin; Cairns, Dana M; Rainbow, Roshni S; Preda, Rucsanda C; Kaplan, David L; Zeng, Li

    2013-05-01

    Cartilage tissue engineering aims to repair damaged cartilage tissue in arthritic joints. As arthritic joints have significantly higher levels of pro-inflammatory cytokines (such as IL-1β and TNFα that cause cartilage destruction, it is critical to engineer stable cartilage in an inflammatory environment. Biomaterial scaffolds constitute an important component of the microenvironment for chondrocytes in engineered cartilage. However, it remains unclear how the scaffold material influences the response of chondrocytes seeded in these scaffolds under inflammatory stimuli. Here we have compared the responses of articular chondrocytes seeded within three different polymeric scaffolding materials (silk, collagen and polylactic acid (PLA)) to IL-1β and TNFα. These scaffolds have different physical characteristics and yielded significant differences in the expression of genes associated with cartilage matrix production and degradation, cell adhesion and cell death. The silk and collagen scaffolds released pro-inflammatory cytokines faster and had higher uptake water abilities than PLA scaffolds. Correspondingly, chondrocytes cultured in silk and collagen scaffolds maintained higher levels of cartilage matrix than those in PLA, suggesting that these biophysical properties of scaffolds may regulate gene expression and the response to inflammatory stimuli in chondrocytes. Based on this study we conclude that selecting the proper scaffold material will aid in the engineering of more stable cartilage tissues for cartilage repair, and that silk and collagen are better scaffolds in terms of supporting the stability of three-dimensional cartilage under inflammatory conditions.

  5. Personal and social conditions potentially influencing women's hearing loss management.

    PubMed

    Garstecki, D C; Erler, S F

    2001-12-01

    Little gender-specific data related to hearing loss and hearing loss management are available. The purpose of this investigation was to examine personal and social conditions affecting women at selected stages of the adult life course that may influence hearing loss management. In all, 191 women in three age groups, ranging from 35 to 85 years old, participated. None reported hearing problems. Participants completed a demographic data form and were given a standard audiometric evaluation to confirm age-normal hearing. Each completed assessments of speech understanding in quiet and noise, auditory signal duration discrimination, and binaural processing. Measures of hearing knowledge, behaviors, and attitudes; health-related locus of control; ego strength; and, social support were administered. Results revealed that although some variables deteriorate among subsequent age groups (i.e., hearing thresholds, central auditory processing, and ego strength), the reverse is true for others (i.e., social interaction and satisfaction with income). Age-specific sociodemographic burdens that may interfere with hearing loss management were noted. New psychosocial data are revealed against which women and men with impaired hearing may be compared.

  6. Influence of combined oral contraceptives on the periodontal condition

    PubMed Central

    DOMINGUES, Roberta Santos; FERRAZ, Bruna Fidêncio Rahal; GREGHI, Sebastião Luiz Aguiar; de REZENDE, Maria Lúcia Rubo; PASSANEZI, Euloir; SANT'ANA, Adriana Campos Passanezi

    2012-01-01

    Most studies investigating the impact of oral contraceptives have been performed some years ago, when the level of sexual hormones was greater than the actual formulations. Objective The aim of this study was to evaluate the effects of current combined oral contraceptives (COC) on periodontal tissues, correlating the clinical parameters examined with the total duration of continuous oral contraceptive intake. Material and methods Twenty-five women (19-35 years old) taking combined oral contraceptives for at least 1 year were included in the test group. The control group was composed by 25 patients at the same age range reporting no use of hormone-based contraceptive methods. Clinical parameters investigated included pocket probing depth (PD), clinical attachment level (CAL), sulcular bleeding index (SBI) and plaque index (Pl.I). Data were statistically evaluated by unpaired t test, Pearson's correlation test and Spearman's correlation test. Results The test group showed increased PD (2.228±0.011 x 2.154±0.012; p<0.0001) and SBI (0.229±0.006 x 0.148±0.005, p<0.0001) than controls. No significant differences between groups were found in CAL (0.435±0.01 x 0.412±0.01; p=0.11). The control group showed greater Pl.I than the test group (0.206±0.007 x 0.303±0.008; p<0.0001). No correlation between the duration of oral contraceptive intake, age and periodontal parameters was observed. Conclusions These findings suggest that the use of currently available combined oral contraceptives can influence the periodontal conditions of the patients, independently of the level of plaque accumulation or total duration of medication intake, resulting in increased gingival inflammation. PMID:22666846

  7. The Influence of Specific Physical Health Conditions on Retirement Decisions

    ERIC Educational Resources Information Center

    Shultz, Kenneth S.; Wang, Mo

    2007-01-01

    Physical health has consistently been shown to strongly influence the retirement decision-making process. Unfortunately, "physical health" is typically operationalized in global terms. As a result, we know little about the specific aspects of physical health that influence the decision to retire. Therefore, in the present study, data from three…

  8. The Influence of Meteorological Conditions on Air Pollution

    ERIC Educational Resources Information Center

    Campbell, N. A.; Gipps, J.

    1975-01-01

    Explains the distribution of air pollutants as related to such meteorological conditions as temperature inversions, ground inversion, and wind velocity. Uses a power station to illustrate the effect of some of the meteorological conditions mentioned. (GS)

  9. Chronic Heat Stress and Cognitive Development: An Example of Thermal Conditions Influencing Human Development

    ERIC Educational Resources Information Center

    Riniolo, Todd C.; Schmidt, Louis A.

    2006-01-01

    Although thermal conditions influence the development of living organisms in a wide variety of ways, this topic has been recently ignored in humans. This paper reintroduces thermal conditions as a topic of importance for developmentalists by presenting an example of how thermal conditions are hypothesized to influence a particular developmental…

  10. Suboptimal Light Conditions Influence Source-Sink Metabolism during Flowering

    PubMed Central

    Christiaens, Annelies; De Keyser, Ellen; Pauwels, Els; De Riek, Jan; Gobin, Bruno; Van Labeke, Marie-Christine

    2016-01-01

    Reliance on carbohydrates during flower forcing was investigated in one early and one late flowering cultivar of azalea (Rhododendron simsii hybrids). Carbohydrate accumulation, invertase activity, and expression of a purported sucrose synthase gene (RsSUS) was monitored during flower forcing under suboptimal (natural) and optimal (supplemental light) light conditions, after a cold treatment (7°C + dark) to break flower bud dormancy. Post-production sucrose metabolism and flowering quality was also assessed. Glucose and fructose concentrations and invertase activity increased in petals during flowering, while sucrose decreased. In suboptimal light conditions RsSUS expression in leaves increased as compared to optimal light conditions, indicating that plants in suboptimal light conditions have a strong demand for carbohydrates. However, carbohydrates in leaves were markedly lower in suboptimal light conditions compared to optimal light conditions. This resulted in poor flowering of plants in suboptimal light conditions. Post-production flowering relied on the stored leaf carbon, which could be accumulated under optimal light conditions in the greenhouse. These results show that flower opening in azalea relies on carbohydrates imported from leaves and is source-limiting under suboptimal light conditions. PMID:26973689

  11. A DGT technique for plutonium bioavailability measurements.

    PubMed

    Cusnir, Ruslan; Steinmann, Philipp; Bochud, François; Froidevaux, Pascal

    2014-09-16

    The toxicity of heavy metals in natural waters is strongly dependent on the local chemical environment. Assessing the bioavailability of radionuclides predicts the toxic effects to aquatic biota. The technique of diffusive gradients in thin films (DGT) is largely exploited for bioavailability measurements of trace metals in waters. However, it has not been applied for plutonium speciation measurements yet. This study investigates the use of DGT technique for plutonium bioavailability measurements in chemically different environments. We used a diffusion cell to determine the diffusion coefficients (D) of plutonium in polyacrylamide (PAM) gel and found D in the range of 2.06-2.29 × 10(-6) cm(2) s(-1). It ranged between 1.10 and 2.03 × 10(-6) cm(2) s(-1) in the presence of fulvic acid and in natural waters with low DOM. In the presence of 20 ppm of humic acid of an organic-rich soil, plutonium diffusion was hindered by a factor of 5, with a diffusion coefficient of 0.50 × 10(-6) cm(2) s(-1). We also tested commercially available DGT devices with Chelex resin for plutonium bioavailability measurements in laboratory conditions and the diffusion coefficients agreed with those from the diffusion cell experiments. These findings show that the DGT methodology can be used to investigate the bioaccumulation of the labile plutonium fraction in aquatic biota.

  12. Iron bioavailability to phytoplankton: an empirical approach.

    PubMed

    Lis, Hagar; Shaked, Yeala; Kranzler, Chana; Keren, Nir; Morel, François M M

    2015-03-17

    Phytoplankton are often limited by iron in aquatic environments. Here we examine Fe bioavailability to phytoplankton by analyzing iron uptake from various Fe substrates by several species of phytoplankton grown under conditions of Fe limitation and comparing the measured uptake rate constants (Fe uptake rate/ substrate concentration). When unchelated iron, Fe', buffered by an excess of the chelating agent EDTA is used as the Fe substrate, the uptake rate constants of all the eukaryotic phytoplankton species are tightly correlated and proportional to their respective surface areas (S.A.). The same is true when FeDFB is the substrate, but the corresponding uptake constants are one thousand times smaller than for Fe'. The uptake rate constants for the other substrates we examined fall mostly between the values for Fe' and FeDFB for the same S.A. These two model substrates thus empirically define a bioavailability envelope with Fe' at the upper and FeDFB at the lower limit of iron bioavailability. This envelope provides a convenient framework to compare the relative bioavailabilities of various Fe substrates to eukaryotic phytoplankton and the Fe uptake abilities of different phytoplankton species. Compared with eukaryotic species, cyanobacteria have similar uptake constants for Fe' but lower ones for FeDFB. The unique relationship between the uptake rate constants and the S.A. of phytoplankton species suggests that the uptake rate constant of Fe-limited phytoplankton has reached a universal upper limit and provides insight into the underlying uptake mechanism.

  13. Iron bioavailability to phytoplankton: an empirical approach

    PubMed Central

    Lis, Hagar; Shaked, Yeala; Kranzler, Chana; Keren, Nir; Morel, François M M

    2015-01-01

    Phytoplankton are often limited by iron in aquatic environments. Here we examine Fe bioavailability to phytoplankton by analyzing iron uptake from various Fe substrates by several species of phytoplankton grown under conditions of Fe limitation and comparing the measured uptake rate constants (Fe uptake rate/ substrate concentration). When unchelated iron, Fe′, buffered by an excess of the chelating agent EDTA is used as the Fe substrate, the uptake rate constants of all the eukaryotic phytoplankton species are tightly correlated and proportional to their respective surface areas (S.A.). The same is true when FeDFB is the substrate, but the corresponding uptake constants are one thousand times smaller than for Fe′. The uptake rate constants for the other substrates we examined fall mostly between the values for Fe′ and FeDFB for the same S.A. These two model substrates thus empirically define a bioavailability envelope with Fe′ at the upper and FeDFB at the lower limit of iron bioavailability. This envelope provides a convenient framework to compare the relative bioavailabilities of various Fe substrates to eukaryotic phytoplankton and the Fe uptake abilities of different phytoplankton species. Compared with eukaryotic species, cyanobacteria have similar uptake constants for Fe′ but lower ones for FeDFB. The unique relationship between the uptake rate constants and the S.A. of phytoplankton species suggests that the uptake rate constant of Fe-limited phytoplankton has reached a universal upper limit and provides insight into the underlying uptake mechanism. PMID:25350155

  14. Use of chemical methods to assess Cd and Pb bioavailability to the snail Cantareus aspersus: a first attempt taking into account soil characteristics.

    PubMed

    Pauget, B; Gimbert, F; Coeurdassier, M; Scheifler, R; de Vaufleury, A

    2011-09-15

    Bioavailability is a key parameter in conditioning contaminant transfer to biota. However, in risk assessment of terrestrial contamination, insufficient attention is being paid to the influence of soil type on trace metal bioavailability. This paper addresses the influence of soil properties on the chemical availability of cadmium (Cd) and lead (Pb) (CaCl(2) extraction and ionic activity) and bioavailability (accumulation kinetics) to the land snail Cantareus aspersus. Snails were exposed to nine contaminated soils differing by a single characteristic (pH or organic matter content or clay content) for 28 days. Toxicokinetic models were applied to determine metal uptake and excretion rates in snails and multivariate regression was used to relate uptake parameters to soil properties. The results showed that alkalinisation of soil and an increase of the organic matter content decreased Pb and Cd bioavailability to snails whereas kaolin clay had no significant influence. The CaCl(2)-extractable concentrations tended to overestimate the effects of pH when used to explain metal uptake rate. We conclude that factors other than those controlling the extractable fraction affect metal bioavailability to snails, confirming the requirement of biota measurements in risk assessment procedures.

  15. Bioavailability of voriconazole in hospitalised patients.

    PubMed

    Veringa, Anette; Geling, Sanne; Span, Lambert F R; Vermeulen, Karin M; Zijlstra, Jan G; van der Werf, Tjip S; Kosterink, Jos G W; Alffenaar, Jan-Willem C

    2017-02-01

    An important element in antimicrobial stewardship programmes is early switch from intravenous (i.v.) to oral antimicrobial treatment, especially for highly bioavailable drugs. The antifungal agent voriconazole is available both in i.v. and oral formulations and bioavailability is estimated to be >90% in healthy volunteers, making this drug a suitable candidate for such a transition. Recently, two studies have shown that the bioavailability of voriconazole is substantially lower in patients. However, for both studies various factors that could influence the voriconazole serum concentration, such as inflammation, concomitant intake of food with oral voriconazole, and gastrointestinal complications, were not included in the evaluation. Therefore, in this study a retrospective chart review was performed in adult patients treated with both oral and i.v. voriconazole at the same dose and within a limited (≤5 days) time interval in order to evaluate the effect of switching the route of administration on voriconazole serum concentrations. A total of 13 patients were included. The mean voriconazole trough concentration was 2.28 mg/L [95% confidence interval (CI) 1.29-3.26 mg/L] for i.v. voriconazole administration and 2.04 mg/L (95% CI 0.78-3.30 mg/L) for oral administration. No significant difference was found in the mean oral and i.v. trough concentrations of voriconazole (P = 0.390). The mean bioavailability was 83.0% (95% CI 59.0-107.0%). These findings suggest that factors other than bioavailability may cause the observed difference in voriconazole trough concentrations between oral and i.v. administration in the earlier studies and stress the need for an antimicrobial stewardship team to guide voriconazole dosing.

  16. Influence of gastric acid secretion blockade and food intake on the bioavailability of a potassium diclofenac suspension in healthy male volunteers.

    PubMed

    Poli, A; Moreno, R A; Ribeiro, W; Dias, H B; Moreno, H; Muscara, M N; De Nucci, G

    1996-02-01

    The bioavailability of a single dose of a potassium diclofenac (KDIC) suspension (Flogan, Merck, 7ml, 105 mg) was studied in 13 healthy male volunteers in the fasting state (placebo phase, PLA), after gastric acid secretion blockade (subacute pretreatment with omeprazole, OME phase) and after food intake (FOOD phase). A 14-day washout period between phases was adopted. Serum samples were obtained over a 24 hour interval and the diclofenac concentrations were determined by high pressure liquid chromatography with ultraviolet detection. From the serum diclofenac concentration vs time curves, the AUC[0-infinity] (area under the concentration vs time curves from 0 to infinity), Cmax (maximum achieved concentration), tmax (time to achieve Cmax), Ke (terminal first order elimination constant), half-life values (t1/2) and AUC[0-infinity]/t1/2 ratio as an index of diclofenac clearance, were obtained. All these variables were analyzed using both parametric and non-parametric statistics. In the presence of food, KDIC absorption was delayed (as shown by lower Cmax and greater tmax values) and decreased (as shown by lower AUC[0-infinity] values), and the serum diclofenac concentration vs time curves showed a biphasic pattern. Omeprazole pretreatment did not change the absorption parameters. Both of these treatments altered the diclofenac clearance, as assessed by the AUC[0-infinity]/t1/2, t1/2 and Ke values, although the changes were not considered to be clinically significant, because of the wide therapeutic range for diclofenac. The delay in the rate of diclofenac absorption produced by food intake was not due to an increase in the gastric pH, and could be of particular importance when rapid analgesia is desired.

  17. Influence of surfactants in self-microemulsifying formulations on enhancing oral bioavailability of oxyresveratrol: Studies in Caco-2 cells and in vivo.

    PubMed

    Sangsen, Yaowaporn; Wiwattanawongsa, Kamonthip; Likhitwitayawuid, Kittisak; Sritularak, Boonchoo; Graidist, Potchanapond; Wiwattanapatapee, Ruedeekorn

    2016-02-10

    Self-microemulsifying drug delivery systems (SMEDDS) containing two types (Tween80 and Labrasol) and two levels (low; 5% and high; 15%) of co-surfactants were formulated to evaluate the impact of surfactant phase on physical properties and oral absorption of oxyresveratrol (OXY). All formulations showed a very rapid release in the simulated gastric fluid (SGF) pH 1.2. After dilution with different media, the microemulsion droplet sizes of the Tween80-based (∼26 to 36 nm) were smaller than that of the Labrasol-based systems (∼34 to 45 nm). Both systems with high levels of surfactant increased the Caco-2 cells permeability of OXY compared to those with low levels of surfactant (1.4-1.7 folds) and the unformulated OXY (1.9-2.0 folds). It was of interest, that there was a reduction (4.4-5.3 folds) in the efflux transport of OXY from both systems compared to the unformulated OXY. The results were in good agreement with the in vivo absorption studies of such OXY-formulations in rats. Significantly greater values of Cmax and AUC(0-10h) (p<0.05) were obtained from the high levels of Tween80-based (F(r,0-10h) 786.32%) compared to those from the Labrasol-based system (F(r,0-10h) 218.32%). These finding indicate the importance of formulation variables such as type and quantity of surfactant in the SMEDDS to enhance oral drug bioavailability.

  18. Conditions that Influence Drivers' Yielding Behavior for Uncontrolled Crossings

    ERIC Educational Resources Information Center

    Bourquin, Eugene; Emerson, Robert Wall; Sauerburger, Dona

    2011-01-01

    Pedestrians with visual impairments need to cross streets where traffic signals and traffic signage are not present. This study examined the influences of several interventions, including a pedestrian's use of a mobility cane, on the behavior of drivers when they were expected to yield to a pedestrian crossing at an uncontrolled crossing.…

  19. Influence of impurity gases and operating conditions on PAFC performance

    SciTech Connect

    Hirai, K.; Iwasa, N.; Suzuki, M.; Okada, O.

    1996-12-31

    On-site Phosphoric Acid Fuel Cell (PAFC) Cogeneration system is installed at various test sites, such as at underground parking lot, within chemical plant premises and near urban streets. Since in the current PAFC system, cathode air is supplied to the cell with no particular pretreatment, impurity gases in the air might influence on cell performance. We have investigated the influence of various impurity gases in the cathode gas, on sub-scale single cells, and have found that NO{sub 2}, SO{sub 2} and toluene affect negatively on cell performance. The results of these experiments and the conceivable mechanism of these effects on cell degradation are reported. We have also investigated the influence of other operating parameters, such as temperature, current density, fuel utilization on cell performance. From these experiments, we have found that operating temperature is a significant factor, which mainly determines cell voltage decline rate. The results of sub-scale single cell tests and a short-stack verification test are also reported.

  20. Sensory system development influences the ontogeny of eyeblink conditioning.

    PubMed

    Goldsberry, Mary E; Elkin, Magdalyn E; Freeman, John H

    2014-09-01

    A rate-limiting factor in the ontogeny of auditory eyeblink conditioning (EBC) is the development of sensory inputs to the pontine nucleus. One possible way to facilitate the emergence of EBC would be to use a conditioned stimulus (CS) that activates an earlier-developing sensory system. The goal of the current study was to investigate whether using a vibration CS would facilitate the ontogeny of delay EBC relative to an auditory CS. Rat pups received six sessions of delay EBC or unpaired training using either a tone or vibration CS on postnatal day (P)14-15, 17-18, 21-22, or 24-25. Conditioning with a vibration CS resulted in rapid learning as early as P17-18, whereas conditioning with a tone CS did not result in rapid conditioning until after P17-18. Control experiments verified that the differences in EBC were due to CS-specific sensory properties. The results suggest that the ontogeny of EBC depends on sensory system development.

  1. Interoceptive awareness and unaware fear conditioning: are subliminal conditioning effects influenced by the manipulation of visceral self-perception?

    PubMed

    Raes, An K; De Raedt, Rudi

    2011-12-01

    Research has shown repeatedly that attention influences implicit learning effects. In a similar vein, interoceptive awareness might be involved in unaware fear conditioning: The fact that the CS is repeatedly presented in the context of aversive bodily experiences might facilitate the development of conditioned responding. We investigated the role of interoceptive attention in a subliminal conditioning paradigm. Conditioning was embedded in a spatial cueing task with subliminally presented cues that were followed by a masking stimulus. Response times to the targets that were either validly or invalidly predicted by the cues served as index of conditioning. Interoceptive attention was manipulated between-subjects. Half the participants completed a heartbeat detection task before conditioning. This task tunes attention to one's own bodily signals. We found that conditioned responding was facilitated in this latter group of participants. These results are in line with the hypothesis that a rise interoceptive attention enhances unaware conditioned responding.

  2. Eudragit L/HPMCAS blend enteric-coated lansoprazole pellets: enhanced drug stability and oral bioavailability.

    PubMed

    Fang, Yu; Wang, Guozheng; Zhang, Rong; Liu, Zhihua; Liu, Zhenghua; Wu, Xiaohui; Cao, Deying

    2014-06-01

    The objectives of the present work were to use blends of Eudragit L and hydroxypropyl methylcellulose acetate succinate (HPMCAS) as enteric film coatings for lansoprazole (LSP) pellets. The enteric-coated pellets were prepared with a fluid-bed coater. The influence of the blend ratio, type of plasticizer, plasticizer level, coating level, and curing conditions on gastric stability in vitro drug release and drug stability was evaluated. Furthermore, the bioavailability of the blend-coated pellets in beagle dogs was also performed. The blend-coated pellets exhibited significant improvement of gastric stability and drug stability compared to the pure polymer-coated pellets. Moreover, the AUC values of blend-coated pellets were greater than that of the pure polymer-coated pellets. It was concluded that the using blends of Eudragit L and HPMCAS as enteric film coatings for LSP pellets improved the drug stability and oral bioavailability.

  3. Body condition and forage type influence intramuscular and rump fat, and reproductive performance of postpartum Brahman-influenced cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multiparous Brahman-influenced cows were managed to achieve marginal (BCS = 4.9 ± 0.1; n = 55) or moderate (BCS = 6.5 ± 0.1; n = 55) body condition (BC) to determine the influence of forage type on estrous characteristics, intramuscular fat percentage (IMF), rump fat (RF), and reproductive performan...

  4. Influence of pavement condition on horizontal curve safety.

    PubMed

    Buddhavarapu, Prasad; Banerjee, Ambarish; Prozzi, Jorge A

    2013-03-01

    Crash statistics suggest that horizontal curves are the most vulnerable sites for crash occurrence. These crashes are often severe and many involve at least some level of injury due to the nature of the collisions. Ensuring the desired pavement surface condition is one potentially effective strategy to reduce the occurrence of severe accidents on horizontal curves. This study sought to develop crash injury severity models by integrating crash and pavement surface condition databases. It focuses on developing a causal relationship between pavement condition indices and severity level of crashes occurring on two-lane horizontal curves in Texas. In addition, it examines the suitability of the existing Skid Index for safety maintenance of two-lane curves. Significant correlation is evident between pavement condition and crash injury severity on two-lane undivided horizontal curves in Texas. Probability of a crash becoming fatal is appreciably sensitive to certain pavement indices. Data suggested that road facilities providing a smoother and more comfortable ride are vulnerable to severe crashes on horizontal curves. In addition, the study found that longitudinal skid measurement barely correlates with injury severity of crashes occurring on curved portions. The study recommends exploring the option of incorporating lateral friction measurement into Pavement Management System (PMS) databases specifically at curved road segments.

  5. Influence of anomalous thermal losses of ignition conditions

    SciTech Connect

    Coppi, B.; Tang, W.M.

    1986-05-01

    In the process of achieving ignition conditions, it is likely that microinstabilities, which lead to anomalous thermal transport of the fusing nuclei, will be present. When such phenomena are taken into account, an appropriate formulation of ignition criteria becomes necessary. In particular, a new type of plasma density limit is identified.

  6. Carbohydrate Supplementation Influences Serum Cytokines after Exercise under Hypoxic Conditions

    PubMed Central

    Caris, Aline Venticinque; Da Silva, Edgar Tavares; Dos Santos, Samile Amorim; Lira, Fabio Santos; Oyama, Lila Missae; Tufik, Sergio; Dos Santos, Ronaldo Vagner Thomatieli

    2016-01-01

    Introduction: Exercise performed at the hypoxia equivalent of an altitude of 4200 m is associated with elevated inflammatory mediators and changes in the Th1/Th2 response. By contrast, supplementation with carbohydrates has an anti-inflammatory effect when exercise is performed under normoxic conditions. The objective of this study was to evaluate the effect of carbohydrate supplementation on cytokines and cellular damage markers after exercise under hypoxic conditions at a simulated altitude of 4200 m. Methods: Seven adult male volunteers who exercised for 60 min at an intensity of 50% VO2Peak were randomly evaluated under three distinct conditions; normoxia, hypoxia and hypoxia + carbohydrate supplementation. Blood samples were collected at rest, at the end of exercise and after 60 min of recovery. To evaluate hypoxia + carbohydrate supplementation, volunteers received a solution of 6% carbohydrate (maltodextrin) or a placebo (strawberry-flavored Crystal Light®; Kraft Foods, Northfield, IL, USA) every 20 min during exercise and recovery. Statistical analyses comprised analysis of variance, with a one-way ANOVA followed by the Tukey post hoc test with a significance level of p < 0.05. Results: Under normoxic and hypoxic conditions, there was a significant increase in the concentration of IL-6 after exercise and after recovery compared to at rest (p < 0.05), while in the hypoxia + carbohydrate group, there was a significant increase in the concentration of IL-6 and TNF-α after exercise compared to at rest (p < 0.05). Furthermore, under this condition, TNF-α, IL-2 and the balance of IL-2/IL-4 were increased after recovery compared to at rest (p < 0.05). Conclusion: We conclude that carbohydrate supplementation modified the IL-6 and TNF-α serum concentrations and shifted the IL-2/IL-4 balance towards Th1 in response without glycemic, glutaminemia and cell damage effects. PMID:27827949

  7. Biodegradation of chitosan and its effect on metal bioavailability.

    PubMed

    Kamari, A; Pulford, I D; Hargreaves, J S J

    2015-02-01

    The microbial breakdown of chitosan, a fishery waste-based material, and its derivative cross-linked chitosans, in both non-contaminated and contaminated conditions was investigated in a laboratory incubation study. Biodegradation of chitosan and cross-linked chitosans was affected by the presence of heavy metals. Zn was more pronounced in inhibiting microbial activity than Cu and Pb. It was estimated that a longer period is required to complete the breakdown of the cross-linked chitosans (up to approximately 100 years) than unmodified chitosan (up to approximately 10 years). The influence of biodegradation on the bioavailable fraction of heavy metals was studied concurrently with the biodegradation trial. It was found that the binding behaviour of chitosan for heavy metals was not affected by the biodegradation process.

  8. Pharmacological activity of metal binding agents that alter copper bioavailability

    PubMed Central

    Helsel, Marian E.

    2015-01-01

    Iron, copper and zinc are required nutrients for many organisms but also potent toxins if misappropriated. An overload of any of these metals can be cytotoxic and ultimately lead to organ failure, whereas deficiencies can result in anemia, weakened immune system function, and other medical conditions. Cellular metal imbalances have been implicated in neurodegenerative diseases, cancer and infection. It is therefore critical for living organisms to maintain careful control of both the total levels and subcellular distributions of these metals to maintain healthy function. This perspective explores several strategies envisioned to alter the bioavailability of metal ions by using synthetic metal-binding agents targeted for diseases where misappropriated metal ions are suspected of exacerbating cellular damage. Specifically, we discuss chemical properties that influence the pharmacological outcome of a subset of metal-binding agents known as ionophores, and review several examples that have shown multiple pharmacological activities in metal-related diseases, with a specific focus on copper. PMID:25797044

  9. Display conditions that influence wayfinding in virtual environments

    NASA Astrophysics Data System (ADS)

    Browse, Roger A.; Gray, Derek W. S.

    2006-02-01

    As virtual environments may be used in training and evaluation for critical real navigation tasks, it is important to investigate the factors influencing navigational performance in virtual environments. We have carried out controlled experiments involving two visual factors known to induce or sustain vection, the illusory perception of self-motion. The first experiment had subjects navigate mazes with either a narrow or wide field of view. We measured the percentage of wrong turns, the total time taken for each attempt, and we examined subjects' drawings of the mazes. We found that a wide field of view can have a substantial effect on navigational abilities, even when the wide field of view does not offer any additional clues to the task, and really only provides a larger view of blank walls on the sides. The second experiment evaluated the effect of perspective accuracy in the scene by comparing the use of displays that were corrected for changing head position against those that were not corrected. The perspective corrections available through headtracking did not appear have any influence on navigational abilities. Another component of our study suggests that during navigation in a virtual environment, memory for directions may not be as effective as it could be with supplemental symbolic representations.

  10. Influence of interface condition on spin-Seebeck effects

    NASA Astrophysics Data System (ADS)

    Qiu, Z.; Hou, D.; Uchida, K.; Saitoh, E.

    2015-04-01

    The longitudinal spin-Seebeck effect (LSSE) has been investigated for Pt/yttrium iron garnet (YIG) bilayer systems. The magnitude of the voltage induced by the LSSE is found to be sensitive to the Pt/YIG interface condition. We observed a large LSSE voltage in a Pt/YIG system with a better crystalline interface, while the voltage decays steeply when an amorphous layer is introduced at the interface artificially.

  11. Can environmental conditions experienced in early life influence future generations?

    PubMed Central

    Burton, Tim; Metcalfe, Neil B.

    2014-01-01

    The consequences of early developmental conditions for performance in later life are now subjected to convergent interest from many different biological sub-disciplines. However, striking data, largely from the biomedical literature, show that environmental effects experienced even before conception can be transmissible to subsequent generations. Here, we review the growing evidence from natural systems for these cross-generational effects of early life conditions, showing that they can be generated by diverse environmental stressors, affect offspring in many ways and can be transmitted directly or indirectly by both parental lines for several generations. In doing so, we emphasize why early life might be so sensitive to the transmission of environmentally induced effects across generations. We also summarize recent theoretical advancements within the field of developmental plasticity, and discuss how parents might assemble different ‘internal’ and ‘external’ cues, even from the earliest stages of life, to instruct their investment decisions in offspring. In doing so, we provide a preliminary framework within the context of adaptive plasticity for understanding inter-generational phenomena that arise from early life conditions. PMID:24807254

  12. Influence of growth conditions on bacteriocin production by Brevibacterium linens.

    PubMed

    Motta, A S; Brandelli, A

    2003-08-01

    The influence of temperature, NaCl concentration and cheese whey media on growth of Brevibacterium linens ATCC 9175 and production of bacteriocin-like antimicrobial activity was studied. Bacteriocin production and activity were higher at 25 degrees C than at 30 degrees C. No significant growth or production of bacteriocins was observed at 37 degrees C. When bacteriocin production was investigated in media containing different concentrations of NaCl, increased activity was observed in media containing 40 or 80 g l(-1), but not 120 g l(-1) NaCl. The addition of NaCl resulted in a significant increase in specific production rates of bacteriocin-like activity. Antimicrobial activity was also observed by cultivation of B. linens at 25 degrees C in cheese whey media.

  13. Analysis of weather condition influencing fire regime in Italy

    NASA Astrophysics Data System (ADS)

    Bacciu, Valentina; Masala, Francesco; Salis, Michele; Sirca, Costantino; Spano, Donatella

    2014-05-01

    Fires have a crucial role within Mediterranean ecosystems, with both negative and positive impacts on all biosphere components and with reverberations on different scales. Fire determines the landscape structure and plant composition, but it is also the cause of enormous economic and ecological damages, beside the loss of human life. In addition, several authors are in agreement suggesting that, during the past decades, changes on fire patterns have occurred, especially in terms of fire-prone areas expansion and fire season lengthening. Climate and weather are two of the main controlling agents, directly and indirectly, of fire regime influencing vegetation productivity, causing water stress, igniting fires through lightning, or modulating fire behavior through wind. On the other hand, these relationships could be not warranted in areas where most ignitions are caused by people (Moreno et al. 2009). Specific analyses of the driving forces of fire regime across countries and scales are thus still required in order to better anticipate fire seasons and also to advance our knowledge of future fire regimes. The objective of this work was to improve our knowledge of the relative effects of several weather variables on forest fires in Italy for the period 1985-2008. Meteorological data were obtained through the MARS (Monitoring Agricultural Resources) database, interpolated at 25x25 km scale. Fire data were provided by the JRC (Join Research Center) and the CFVA (Corpo Forestale e di Vigilanza Ambientale, Sardinia). A hierarchical cluster analysis, based on fire and weather data, allowed the identification of six homogeneous areas in terms of fire occurrence and climate (pyro-climatic areas). Two statistical techniques (linear and non-parametric models) were applied in order to assess if inter-annual variability in weather pattern and fire events had a significant trend. Then, through correlation analysis and multi-linear regression modeling, we investigated the

  14. Influence of culture conditions on glutathione production by Saccharomyces cerevisiae.

    PubMed

    Santos, Lucielen Oliveira; Gonzales, Tatiane Araujo; Ubeda, Beatriz Torsani; Monte Alegre, Ranulfo

    2007-12-01

    A strategy of experimental design using a fractional factorial design (FFD) and a central composite rotatable design (CCRD) were carried out with the aim to obtain the best conditions of temperature (20-30 degrees C), agitation rate (100-300 rpm), initial pH (5.0-7.0), inoculum concentration (5-15%), and glucose concentration (30-70 g/l) for glutathione (GSH) production in shake-flask culture by Saccharomyces cerevisiae ATCC 7754. By a FFD (2(5-2)), the agitation rate, temperature, and pH were found to be significant factors for GSH production. In CCRD (2(2)) was obtained a second-order model equation, and the percent of variation explained by the model was 95%. The results showed that the optimal culture conditions were agitation rate, 300 rpm; temperature, 20 degrees C; initial pH, 5; glucose, 54 g/l; and inoculum concentration, 5%. The highest GSH concentration (154.5 mg/l) was obtained after 72 h of fermentation.

  15. Mycotoxins: toxicity, carcinogenicity, and the influence of various nutritional conditions*

    PubMed Central

    Newberne, Paul M.

    1974-01-01

    Toxicologic diseases of man and animals, associated with molds growing on foods, have been recognized for centuries. Only in recent years, however, have these mycotoxicoses received the attention of many laboratories and skilled scientists around the world in a broad inter-disciplinary effort. This review covers the literature on mycotoxicoses but centers on those about which most is known, particularly the diseases associated with metabolites elaborated by some strains of Aspergilli, Penicillia, Fusaria, Stachybotrys, and Claviceps. The ubiquitous nature of the aflatoxins, toxic metabolites produced by Aspergillus flavus, make them important to public health, especially since it is now known that certain areas of endemic liver disease coincide with consumption of aflatoxins and, often, malnutrition. The older disease of ergotism, the scourge of Europe for centuries, is considered in detail. Alimentary toxic aleukia, which has caused enormous suffering in Russian human and animal populations, is better understood as a result of relatively recent experimental investigations. Stachybotryotoxicosis, a disease previously considered to be of significance only to man has now been identified in domestic animals. Finally, Japanese studies have clearly revealed the hepatotoxicity of certain metabolites of Penicillium molds. Factors that influence susceptibility to mycotoxins and the hazards they present to man are also reviewed. ImagesFIGURE 2. PMID:4620330

  16. Pulping of holm oak wood. Influence of the operating conditions.

    PubMed

    López, Francisco; Alaejos, Joaquín; Rodríguez, Alejandro; Jiménez, Luis

    2008-03-01

    This paper reports on the influence of independent variables in the pulping of holm oak wood (Quercus ilex L.) [viz. temperature (135-195 degrees C), cooking time (30-90min) and soda concentration (10-20%)] on the yield, holocellulose content, alpha-cellulose content, brightness and viscosity of the resulting pulp. By using a central composite factorial design, equations relating each dependent variable to the different independent variables were derived that reproduced the experimental results for the dependent variables with errors less than 5-15% in all cases. The highest pulp yield (56.9%) was obtained with the lowest values of the operating variables. However, obtaining the optimum holocellulose content, alpha-cellulose content and viscosity (viz. 94.5%, 78.5% and 1395ml/g, respectively) entailed using values of the independent variables above their mean levels. Also, ensuring optimal brightness (viz. 24.3%) required using higher temperatures and soda concentrations. A compromise that saves equipment immobilized capital and about 25% of soda is using a soda concentration of 15% at 195 degrees C for 30min. The yield thus obtained differs by less than 29.5% from the highest level; also, the resulting holocellulose content, alpha-cellulose content and brightness differ by less than 12% from their respective optimum values.

  17. Comparing Observed Hurricane Conditions Against Potential Future Climate Change Influences

    NASA Astrophysics Data System (ADS)

    Graham, W. D.

    2012-12-01

    Climate Adaptation Science Investigators: (CASI) is to advance and apply NASA's scientific expertise and products to develop climate adaptation strategies that support NASA's overall mission by minimizing risks to each center's operations, physical assets, and personnel. Using Hurricane Katrina observations as a baseline, we use ADCIRC to model surge extent with simple modifications of the storm track. We examine two time now (T0) scenarios of present-day climatological factors: 1) translating the 2005 path 7 km west; and 2) rotating the approach angle from due-north to WNW. Second, we examine two future time scenarios (TX) by infusing climate change conditions, such as sea level rise and increased storm intensity, into a T0 baseline to assess future impacts. The primary goal of this work entails planning and protecting NASA assets and infrastructure. The adjacent communities, state and local emergency managers, gain benefit from this NASA work as data and analysis includes the surrounding geography.

  18. Influence of Musculoskeletal Conditions on Oral Health Among Older Adults

    PubMed Central

    Kelsey, Jennifer L.; Lamster, Ira B.

    2008-01-01

    Both musculoskeletal disorders and diseases of the oral cavity are common and potentially serious problems among older persons, yet little attention has been given to the links between them. Several musculoskeletal diseases, including osteoporosis, Paget’s disease, and arthritic disorders, may directly involve the oral cavity and contiguous structures. Drugs used to treat musculoskeletal diseases, including corticosteroids and bisphosphonates, increase the risk of suppression of the immune system and osteonecrosis of the jaw, respectively. Many people with disabling osteoarthritis, rheumatoid arthritis, and other conditions have difficulty practicing good oral hygiene and traveling to dental offices for professional help. Various inexpensive measures can help such individuals, including education of their caregivers and provision of antimicrobial mouthwashes and special toothbrushes. PMID:18511715

  19. Influence of ammonia on sulfate formation under haze conditions

    NASA Astrophysics Data System (ADS)

    Turšič, Janja; Berner, Axel; Podkrajšek, Boštjan; Grgić, Irena

    In the presence of hygroscopic material, stable aqueous droplets form at relative humidity below 100%. In this work, we examined the role and importance of NH 3 in SO 2 oxidation under haze conditions. Synthetic deposits composed mainly of NaCl and NaNO 3 were exposed to SO 2/NH 3/air gas mixture under controlled conditions, typical for heavily polluted atmosphere. In contrast to catalytic reaction by Mn(II) in the absence of NH 3, which is self-limited, the production of sulfate in the presence of NH 3 at RH 80% increases considerably and linearly with time. The catalytic effect of Mn(II) was observed only for NaNO 3 deposits. Non-catalytic SO 2 oxidation in the presence of NH 3 is negligible below the deliquescent relative humidity, i.e. RH<75%. Above this value a considerable increase of sulfate formation in a narrow range of relative humidity (75-80%) was noticed. We found out that the reaction rate is not proportional to the volume of condensed water; we suggest that available surface play a role in limiting the reaction. The rate of conversion for both pure salts at RH⩾80% was found to be 1.1% h -1 ([SO 2]=2 ppm, [NH 3]=1 ppm, T=10°C), which is more than an order of magnitude higher in comparison with our previous results on MnCl 2/NaCl and MnCl 2/NaNO 3 at RH=80% in the absence of NH 3.

  20. Potassium Intake, Bioavailability, Hypertension, and Glucose Control

    PubMed Central

    Stone, Michael S.; Martyn, Lisa; Weaver, Connie M.

    2016-01-01

    Potassium is an essential nutrient. It is the most abundant cation in intracellular fluid where it plays a key role in maintaining cell function. The gradient of potassium across the cell membrane determines cellular membrane potential, which is maintained in large part by the ubiquitous ion channel the sodium-potassium (Na+-K+) ATPase pump. Approximately 90% of potassium consumed (60–100 mEq) is lost in the urine, with the other 10% excreted in the stool, and a very small amount lost in sweat. Little is known about the bioavailability of potassium, especially from dietary sources. Less is understood on how bioavailability may affect health outcomes. Hypertension (HTN) is the leading cause of cardiovascular disease (CVD) and a major financial burden ($50.6 billion) to the US public health system, and has a significant impact on all-cause morbidity and mortality worldwide. The relationship between increased potassium supplementation and a decrease in HTN is relatively well understood, but the effect of increased potassium intake from dietary sources on blood pressure overall is less clear. In addition, treatment options for hypertensive individuals (e.g., thiazide diuretics) may further compound chronic disease risk via impairments in potassium utilization and glucose control. Understanding potassium bioavailability from various sources may help to reveal how specific compounds and tissues influence potassium movement, and further the understanding of its role in health. PMID:27455317

  1. Potassium Intake, Bioavailability, Hypertension, and Glucose Control.

    PubMed

    Stone, Michael S; Martyn, Lisa; Weaver, Connie M

    2016-07-22

    Potassium is an essential nutrient. It is the most abundant cation in intracellular fluid where it plays a key role in maintaining cell function. The gradient of potassium across the cell membrane determines cellular membrane potential, which is maintained in large part by the ubiquitous ion channel the sodium-potassium (Na+-K+) ATPase pump. Approximately 90% of potassium consumed (60-100 mEq) is lost in the urine, with the other 10% excreted in the stool, and a very small amount lost in sweat. Little is known about the bioavailability of potassium, especially from dietary sources. Less is understood on how bioavailability may affect health outcomes. Hypertension (HTN) is the leading cause of cardiovascular disease (CVD) and a major financial burden ($50.6 billion) to the US public health system, and has a significant impact on all-cause morbidity and mortality worldwide. The relationship between increased potassium supplementation and a decrease in HTN is relatively well understood, but the effect of increased potassium intake from dietary sources on blood pressure overall is less clear. In addition, treatment options for hypertensive individuals (e.g., thiazide diuretics) may further compound chronic disease risk via impairments in potassium utilization and glucose control. Understanding potassium bioavailability from various sources may help to reveal how specific compounds and tissues influence potassium movement, and further the understanding of its role in health.

  2. Bioavailability of tocotrienols: evidence in human studies

    PubMed Central

    2014-01-01

    As a minor component of vitamin E, tocotrienols were evident in exhibiting biological activities such as neuroprotection, radio-protection, anti-cancer, anti-inflammatory and lipid lowering properties which are not shared by tocopherols. However, available data on the therapeutic window of tocotrienols remains controversial. It is important to understand the absorption and bioavailability mechanisms before conducting in-depth investigations into the therapeutic efficacy of tocotrienols in humans. In this review, we updated current evidence on the bioavailability of tocotrienols from human studies. Available data from five studies suggested that tocotrienols may reach its target destination through an alternative pathway despite its low affinity for α-tocopherol transfer protein. This was evident when studies reported considerable amount of tocotrienols detected in HDL particles and adipose tissues after oral consumption. Besides, plasma concentrations of tocotrienols were shown to be higher when administered with food while self-emulsifying preparation of tocotrienols was shown to enhance the absorption of tocotrienols. Nevertheless, mixed results were observed based on the outcome from 24 clinical studies, focusing on the dosages, study populations and formulations used. This may be due to the variation of compositions and dosages of tocotrienols used, suggesting a need to understand the formulation of tocotrienols in the study design. Essentially, implementation of a control diet such as AHA Step 1 diet may influence the study outcomes, especially in hypercholesterolemic subjects when lipid profile might be modified due to synergistic interaction between tocotrienols and control diet. We also found that the bioavailability of tocotrienols were inconsistent in different target populations, from healthy subjects to smokers and diseased patients. In this review, the effect of dosage, composition and formulation of tocotrienols as well as study populations on the

  3. Bioavailability of syrup and tablet formulations of cefetamet pivoxil.

    PubMed Central

    Ducharme, M P; Edwards, D J; McNamara, P J; Stoeckel, K

    1993-01-01

    Two studies examining the bioavailability of cefetamet pivoxil in healthy male subjects were conducted. In the first, the bioavailabilities of the 250-mg (M250) and M500 tablet formulations of cefetamet pivoxil to be marketed were compared with that of a tablet used in clinical trials. All products were given with food at a dose of 500 mg. In the second study, the bioavailability of the syrup formulation was evaluated under both fasting and nonfasting conditions and compared with that of the M500 tablet formulation given with food. The absolute bioavailabilities of the M500 and M250 tablets (55.0% +/- 8.0% and 55.7% +/- 7.0%, respectively) were not significantly different from that of the clinical-trial formulation (49.8% +/- 8.5%). The newer tablet formulations exhibited faster absorption as evidenced by higher peak concentrations (3.8 [M500] and 3.9 [M250] mg/liter compared with 3.2 mg/liter for the clinical-trial formulation), a shorter time to peak concentration, and a shorter mean absorption time. The syrup formulation was found to have significantly lower absolute bioavailability (37.9% +/- 6.0%) compared with that of the M500 tablet (58.4% +/- 9.0%) when both were given with food. Food had no significant effect on the bioavailability of the syrup, which averaged 34.0% +/- 8.6% under fasting conditions, although absorption was delayed by food (mean absorption time increased from 2.2 to 3.9 h). This contrasts with the results of previous studies documenting significant increases in tablet bioavailability with food. Despite the lower bioavailability of the syrup, unbound-cefetamet concentrations are expected to remain above the MICs for 90% of the strains tested for susceptible organisms for approximately 10 h of the usual 12-h dosing interval with both syrup and tablet formulations of cefetamet pivoxil given with food. PMID:8109939

  4. Sample storage conditions significantly influence faecal microbiome profiles

    PubMed Central

    Choo, Jocelyn M; Leong, Lex EX; Rogers, Geraint B

    2015-01-01

    Sequencing-based studies of the human faecal microbiota are increasingly common. Appropriate storage of sample material is essential to avoid the introduction of post-collection bias in microbial community composition. Rapid freezing to −80 °C is commonly considered to be best-practice. However, this is not feasible in many studies, particularly those involving sample collection in participants’ homes. We determined the extent to which a range of stabilisation and storage strategies maintained the composition of faecal microbial community structure relative to freezing to −80 °C. Refrigeration at 4 °C, storage at ambient temperature, and the use of several common preservative buffers (RNAlater, OMNIgene.GUT, Tris-EDTA) were assessed relative to freezing. Following 72 hours of storage, faecal microbial composition was assessed by 16 S rRNA amplicon sequencing. Refrigeration was associated with no significant alteration in faecal microbiota diversity or composition. However, samples stored using other conditions showed substantial divergence compared to −80 °C control samples. Aside from refrigeration, the use of OMNIgene.GUT resulted in the least alteration, while the greatest change was seen in samples stored in Tris-EDTA buffer. The commercially available OMNIgene.GUT kit may provide an important alternative where refrigeration and cold chain transportation is not available. PMID:26572876

  5. Age at menarche: the influence of environmental conditions

    NASA Astrophysics Data System (ADS)

    Saar, E.; Shalev, C.; Dalal, I.; Sod-Moriah, U. A.

    1988-03-01

    Age at menarche was studied by the recollection method in two groups of Causasian Jewish high school girls, inhabitants of two towns in Israel, Safad and Elat. The two towns differ mainly in climatic conditions. The age at menarche was found to be significantly lower ( P<0.02) in the hot town of Elat than in the temperate town of Safad: 13.30±1.21 and 13.58±0.9 years, respectively (mean ±SD). A significant association was found between the age at menarche and the town in which the girls lived. Accordingly, in the hot town of Elat, the percentage of girls who had their first menstrual cycle by the age of 12 years and earlier, was more than double that of the girls in Safad (17.9% and 7.1%, respectively). It is concluded that the environmental temperature, with or without any possible interaction of humidity, is probably responsible for the tendency for an earlier onset of menarche in girls living in the hot town of Elat.

  6. Bioavailability: implications for science/cleanup policy

    SciTech Connect

    Denit, Jeffery; Planicka, J. Gregory

    1998-12-01

    This paper examines the role of bioavailability in risk assessment and cleanup decisions. Bioavailability refers to how chemicals ''behave'' and their ''availability'' to interact with living organisms. Bioavailability has significant implications for exposure risks, cleanup goals, and site costs. Risk to human health and the environment is directly tied to the bioavailability of the chemicals of concern.

  7. Trace metal speciation and bioavailability in anaerobic digestion: A review.

    PubMed

    Thanh, Pham Minh; Ketheesan, Balachandran; Yan, Zhou; Stuckey, David

    2016-01-01

    Trace metals are essential for the growth of anaerobic microorganisms, however, in practice they are often added to anaerobic digesters in excessive amounts, which can lead to inhibition. The concept of bioavailability of metals in anaerobic digestion has been poorly understood in the past, and a lack of deep understanding of the relationship between trace metal speciation and bioavailability can result in ineffective metal dosing strategies for anaerobic digesters. Sequential extraction schemes are useful for fractionating trace metals into their different forms, and metal sulfides can serve as a store and source for trace metals during anaerobic digestion, while natural/synthetic chelating agents (soluble microbial products-SMPs, extracellular polysaccharides-EPS, and EDTA/NTA) are capable of controlling trace metal bioavailability. Nevertheless, more work is needed to: investigate the speciation and bioavailability of Ca, Mg, Mn, W, and Se; compare the bioavailability of different forms of trace metals e.g. carbonates, sulfides, phosphates to different anaerobic trophic groups; determine what factors influence metal sulfide dissolution; investigate whether chelating agents can increase trace metal bioavailability; develop and adapt specialized analytical techniques, and; determine how trace metal dynamics change in an anaerobic membrane bioreactor (AnMBR).

  8. Zinc bioavailability in the chick

    SciTech Connect

    Hempe, J.M.

    1987-01-01

    Methods for assessing zinc bioavailability were evaluated in the chick. A low-zinc chick diet was developed using rehydrated, spray-dried egg white autoclaved at 121 C for 30 min as the primary protein source. The relative bioavailability of zinc from soy flour and beef was determined by whole-body retention of extrinsic /sup 65/Zn, and in slope ratio assays for growth rate and tissue zinc. Compared to zinc carbonate added to an egg white-based diet, all methods gave similar estimates of approximately 100% zinc bioavailability for beef but estimates for soy flour varied widely. The slope ratio assay for growth rate gave the best estimate of zinc bioavailability for soy flour. True absorption, as measured by percent isotope retention from extrinsically labeled soy flour, was 47%.

  9. Influence of meteorological conditions on RSV infection in Portugal

    NASA Astrophysics Data System (ADS)

    Oliveira-Santos, M.; Santos, J. A.; Soares, J.; Dias, A.; Quaresma, M.

    2016-12-01

    Acute viral bronchiolitis is a common cause for infant hospital admissions. Of all etiological agents, respiratory syncytial virus (RSV) is commonly the most frequent. The present study assesses relationships between atmospheric factors and RSV infections in under 3-year-old patients admitted to the Inpatient Paediatric Service of Vila Real (North of Portugal). For this purpose, (1) clinical files of children admitted with a diagnosis of acute bronchiolitis from September 2005 to December 2015 (>10 years) were scrutinised and (2) local daily temperature/precipitation series, as well as six weather types controlling meteorological conditions in Portugal, were used. Fifty-five percent of all 770 admitted children were effectively infected with a given virus, whilst 48 % (367) were RSV+, i.e. 87 % of virus-infected children were RSV+. The bulk of incidence is verified in the first year of age (82 %, 302), slightly higher in males. RSV outbreaks are typically from December to March, but important inter-annual variability is found in both magnitude and shape. Although no clear connections were found between monthly temperatures/precipitation and RSV outbreaks apart from seasonality, a linkage to wintertime cold spells is apparent on a daily basis. Anomalously low minimum temperatures from the day of admittance back to 10 days before are observed. This relationship is supported by anomalously high occurrences of the E and AA weather types over the same period, which usually trigger dry and cold weather. These findings highlight some predictability in the RSV occurrences, revealing potential for modelling and risk assessments.

  10. The influence of convection parameterisations under alternate climate conditions

    NASA Astrophysics Data System (ADS)

    Rybka, Harald; Tost, Holger

    2013-04-01

    In the last decades several convection parameterisations have been developed to consider the impact of small-scale unresolved processes in Earth System Models associated with convective clouds. Global model simulations, which have been performed under current climate conditions with different convection schemes, significantly differ among each other in the simulated precipitation patterns due to the parameterisation assumptions and formulations, e.g. the simplified treatment of the cloud microphysics. Additionally, the simulated transport of short-lived trace gases strongly depends on the chosen convection parameterisation due to the differences in the vertical redistribution of mass. Furthermore, other meteorological parameters like the temperature or the specific humidity show substantial differences in convectively active regions. This study presents uncertainties of climate change scenarios caused by different convection parameterisations. For this analysis two experiments (reference simulation with a CO2 concentration of 348 ppm; 2xCO2-simulation with a CO2 concentration of 696 ppm) are calculated with the ECHAM/MESSy atmospheric chemistry (EMAC) model applying four different convection schemes (Tiedtke, ECMWF, Emanuel and Zhang-McFarlane - Hack) and two resolutions (T42 and T63), respectively. The results indicate that the equilibrium climate sensitivity is independent of the chosen convection parameterisation. However, the regional temperature increase, induced by a doubling of the carbon dioxide concentration, demonstrates differences of up to a few Kelvin at the surface as well as in the UTLS for the ITCZ region depending on the selected convection parameterisation. The interaction between cloud and convection parameterisations results in a large disagreement of precipitation patterns. Although every 2xCO2 -experiment simulates an increase in global mean precipitation rates, the change of regional precipitation patterns differ widely. Finally, analysing

  11. Phenanthrene Bioavailability and Toxicity to Daphnia magna in the Presence of Carbon Nanotubes with Different Physicochemical Properties.

    PubMed

    Zindler, Florian; Glomstad, Berit; Altin, Dag; Liu, Jingfu; Jenssen, Bjørn M; Booth, Andy M

    2016-11-15

    Studies investigating the effect of carbon nanotubes (CNTs) on the bioavailability and toxicity of hydrophobic organic compounds in aquatic environments have generated contradictory results, and the influence of different CNT properties remains unknown. Here, the adsorption of the polycyclic aromatic hydrocarbon phenanthrene (70-735 μg/L) to five types of CNTs exhibiting different physical and chemical properties was studied. The CNTs were dispersed in the presence of natural organic matter (nominally 20 mg/L) in order to increase the environmental relevance of the study. Furthermore, the bioavailability and toxicity of phenanthrene to Daphnia magna in the absence and presence of dispersed CNTs was investigated. Both CNT dispersion and adsorption of phenanthrene appeared to be influenced by CNT physical properties (diameter and specific surface area). However, dispersion and phenanthrene adsorption was not influenced by CNT surface chemical properties (surface oxygen content), under the conditions tested. Based on nominal phenanthrene concentrations, a reduction in toxicity to D. magna was observed during coexposure to phenanthrene and two types of CNTs, while for the others, no influence on phenanthrene toxicity was observed. Based on freely dissolved concentrations, however, an increased toxicity was observed in the presence of all CNTs, indicating bioavailability of CNT-adsorbed phenanthrene to D. magna.

  12. Individualism-Collectivism as a Boundary Condition for Effectiveness of Minority Influence in Decision Making.

    PubMed

    Ng, K. Yee; Van Dyne, Linn

    2001-03-01

    Results of this experiment demonstrate that individualists and collectivists react differently to minority influence. Based on the distinction between objectivity and preference norms in the minority influence literature, we hypothesize that individualism and collectivism influence (A) responses to minority influence (focusing on the target of influence) and (B) effectiveness of minority influence (focusing on the influence agent). Our results replicate past research and demonstrate improved decision quality for individuals exposed to a minority perspective. Moreover, minority influence targets with high horizontal individualism and low horizontal collectivism made higher quality decisions. Influence targets with high vertical collectivism demonstrated higher quality decisions when the influence agent held a high status position in the group. Results also demonstrate that influence agents with high vertical individualism experienced less role stress than those with low vertical individualism. Finally, influence agents with low role stress were more effective in influencing the decision making of others. We discuss our findings in terms of boundary conditions to the minority influence process. Copyright 2000 Academic Press.

  13. Influence of soil type and organic matter content on the bioavailability, accumulation, and toxicity of alpha-cypermethrin in the springtail Folsomia candida.

    PubMed

    Styrishave, Bjarne; Hartnik, Thomas; Christensen, Peter; Andersen, Ole; Jensen, John

    2010-05-01

    The influence of organic matter (OM) content on alpha-cypermethrin porewater concentrations and springtail Folsomia candida accumulation was investigated in two soils with different levels of organic matter, a forest soil with a total organic carbon (TOC) content of 5.0% (OM=11.5%) and an agricultural soil with a TOC content of 1.3% (OM=4.0%). Also, the effects of alpha-cypermethrin concentrations in soil and pore water and the influence of soil aging on springtail reproduction were investigated. Springtail reproduction was severely affected by increasing alpha-cypermethrin in soil with 1.3% TOC; the median effective concentration value (EC50) was estimated to 23.4 mg/kg (dry wt). Reproduction was only marginally affected in the soil with 5.0% TOC, and no EC50 value could be estimated. However, when expressing alpha-cypermethrin accumulation as a function of soil alpha-cypermethrin concentrations, no difference was found between the two soil types, and no additional alpha-cypermethrin uptake was observed at soil concentrations above approximately 200 mg/kg (dry wt). By using solid-phase microextraction (SPME), it could be demonstrated that alpha-cypermethrin porewater concentrations were higher in the soil with low organic matter (LOM) content than in the soil with high organic matter (HOM) content. Furthermore, a clear relationship was found between alpha-cypermethrin concentrations in springtails and porewater. Soil aging was not found to exert any effect on alpha-cypermethrin toxicity toward springtails. The study indicates that the springtail's accumulation of alpha-cypermethrin and reproduction is governed by alpha-cypermethrin porewater concentrations rather than the total alpha-cypermethrin concentration in soil.

  14. Influence of discharge and urbanization on the concentration, speciation, and bioavailability of trace metals in the Raritan River, New Jersey. Final report

    SciTech Connect

    McLaughlin, F.B.; Ashley, G.M.; Renwick, W.H.

    1988-01-01

    The Raritan River and its tributaries are a vital drinking water and recreational resource in central New Jersey. These waters also serve as disposal media for municipal and industrial wastes and urban stormwater runoff. Rapid development over the last several decades has intensified the pressures on the quality and use of Raritan waters. The concentration and speciation of ten trace metals (Ag, As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn) were investigated in the Raritan Basin. From September 1985 to April 1987, one hundred twenty depth-integrated samples were collected at four locations and analyzed by Direct-Current Plasma Atomic Emission Spectrometry for concentrations of dissolved, particulate-associated, total, and suspended sediment trace metals. The concentrations of trace metals readily available, potentially available, and not available to aquatic and terrestrial biota are also reported. Discharge is the most important factor influencing the concentration and speciation of trace metals in the Raritan River and its tributaries. Seasonal variations affect speciation patterns, but have a minor impact on concentration and availability to biota. The sub-basin draining a more-urbanized area in the Raritan Basin appeared to have elevated concentrations and increased biological availability of trace metals relative to less-urbanized basins.

  15. Participation and influence of migrant workers on working conditions: a qualitative approach.

    PubMed

    López-Jacob, María J; Safont, Eva Canaleta; García, Ana M; Garí, Aitana; Agudelo-Suárez, Andrés; Gil, Angel; Benavides, Fernando G

    2010-01-01

    Workers participation in the management of employment and working conditions is an important determinant of both positive and negative effects of work on human health. Through a qualitative approach, this study analyzes the degree of control and influence that migrant workers in different Spanish cities have over their own working conditions (Immigration, Work, and Health [ITSAL] Project). Results showed that migrant workers had little influence on employment and working conditions. Immigrant workers are mostly interested in issues such as salaries, hiring, and hours of work. Fear of dismissal makes immigrant workers reluctant to demand improved working conditions. We received limited information about immigrant workers' understanding of their rights and their perceptions of the possibilities to influence working conditions through trade union activity. Informal social networks play an essential role in disseminating information on workers' rights, although the effect is not always positive. Unions need to increase attention to and adapt measures for this particularly vulnerable group of workers.

  16. Isoflavones: estrogenic activity, biological effect and bioavailability.

    PubMed

    Vitale, Daniela Cristina; Piazza, Cateno; Melilli, Barbara; Drago, Filippo; Salomone, Salvatore

    2013-03-01

    Isoflavones are phytoestrogens with potent estrogenic activity; genistein, daidzein and glycitein are the most active isoflavones found in soy beans. Phytoestrogens have similarity in structure with the human female hormone 17-β-estradiol, which can bind to both alpha and beta estrogen receptors, and mimic the action of estrogens on target organs, thereby exerting many health benefits when used in some hormone-dependent diseases. Numerous clinical studies claim benefits of genistein and daidzein in chemoprevention of breast and prostate cancer, cardiovascular disease and osteoporosis as well as in relieving postmenopausal symptoms. The ability of isoflavones to prevent cancer and other chronic diseases largely depends on pharmacokinetic properties of these compounds, in particular absorption and distribution to the target tissue. The chemical form in which isoflavones occur is important because it influences their bioavailability and, therefore, their biological activity. Glucose-conjugated isoflavones are highly polar, water-soluble compounds. They are hardly absorbed by the intestinal epithelium and have weaker biological activities than the corresponding aglycone. Different microbial families of colon can transform glycosylated isoflavones into aglycones. Clinical studies show important differences between the aglycone and conjugated forms of genistein and daidzein. The evaluation of isoflavone metabolism and bioavailability is crucial to understanding their biological effects. Lipid-based formulations such as drug incorporation into oils, emulsions and self-microemulsifying formulations have been introduced to increase bioavailability. Complexation with cyclodextrin also represent a valid method to improve the physicochemical characteristics of these substances in order to be absorbed and distributed to target tissues. We review and discuss pharmacokinetic issues that critically influence the biological activity of isoflavones.

  17. Influence of orbital flight conditions on formation of genitals in Muscari racemosum and Anethum graveolens.

    PubMed

    Kordyum, E L; Popova, A F; Mashinsky, A L

    1979-01-01

    It was shown that under space flight conditions development of male genitals in Muscari racemosum is accelerated compared to that of laboratory and natural field controls. Conditions of space flight produced an inhibitory effect on germination and germinative energy of Anethum graveolens seeds. The first stages of the plant development, right up to the flowering stage, also suffered from the inhibitory influence of space flight conditions. A cytoembryological study of the experiment and control plants found no essential differences between them.

  18. Bioavailability of long-chain omega-3 fatty acids.

    PubMed

    Schuchardt, Jan Philipp; Hahn, Andreas

    2013-07-01

    Supplements have reached a prominent role in improving the supply of long-chain omega-3 fatty acids, such as Eicosapentaenoic acid (EPA 20:5n-3) and Docosahexaenoic acid (DHA 22:6n-3). Similar to other nutrients, the availability of omega-3 fatty acids is highly variable and determined by numerous factors. However, the question of omega-3 fatty acids bioavailability has long been disregarded, which may have contributed to the neutral or negative results concerning their effects in several studies. This review provides an overview of the influence of chemical binding form (free fatty acids bound in ethylesters, triacylglycerides or phospholipids), matrix effects (capsule ingestion with concomitant intake of food, fat content in food) or galenic form (i.e. microencapsulation, emulsification) on the bioavailability of omega-3 fatty acids. There is a need to systematically investigate the bioavailability of omega-3 fatty acids formulations, which might be a key to designing more effective studies in the future.

  19. Investigations of copper speciation and bioavailability

    SciTech Connect

    Deaver, E.; Rodgers, J.H. Jr.

    1995-12-31

    Speciation, or form in which copper occurs, can effect the bioavailability and therefore, the toxicity of that element. One needs to determine the bioavailable forms of copper in sediment/water effects on organisms. In both water and sediment experiments, physical/chemical factors influencing copper speciation were evaluated and related to organism responses. Ten day aqueous experiments encompassing a range of pH (6.5--8.1), alkalinity (10--70 mg/L as CaCO{sub 3}), hardness (10--70 mg/L as CaCO{sub 3}) and conductivity (30--300 umhos/cm) were conducted using Hyalella azteca. Amphipod survival was evaluated relative to changes in water characteristics and concomitant changes in copper speciation as measured using atomic adsorption spectroscopy (AA) for acid extractable copper, and differential pulse anodic stripping voltammetry (DPASV) for labile copper. Ten day LC50s based on AA measured copper concentrations ranged from 42 to 142 ug/L Cu, and LC50s based on DPASV measured copper concentrations ranged from 17.4--24.8 ug/L Cu. Ten day sediment experiments encompassing a range of sediment pH, organic carbon content, acid volatile sulfides and redox concentrations were also conducted using H. azteca. Overlying water (AA and DPASV) and sediment copper concentrations (AA) were measured and evaluated relative to organism survival. Ten day sediment test LC50s based on DPASV measured copper concentrations in overlying water were 18.5 and 18 ug/L Cu for experiments in sandy and silty sediments, respectively. Organism survival, used as a measure of bioavailable copper, was evaluated in relation to measured copper species concentrations and used to develop guidelines for predicting copper toxicity in freshwater systems.

  20. BIOSURFACES AND BIOAVAILABILITY: A NANOSCALE OVERVIEW

    EPA Science Inventory

    Environmentally, contaminant bioavailability is a key parameter in determining exposure assessment and ultimately risk assessment/risk management. Defining bioavailability requires knowledge of the contaminant spatial/temporal disposition and transportability and the thermodyna...

  1. Growing rice aerobically markedly decreases mercury accumulation by reducing both Hg bioavailability and the production of MeHg.

    PubMed

    Wang, Xun; Ye, Zhihong; Li, Bing; Huang, Linan; Meng, Mei; Shi, Jianbo; Jiang, Guibin

    2014-01-01

    Rice consumption represents a major route of mercury (Hg) and methylmercury (MeHg) exposure for those living in certain areas of inland China. In this study we investigated the effects of water management on bioavailable Hg, MeHg, and sulfate-reducing bacteria (SRB, abundance and community composition) in rhizosphere soil, and total Hg (THg) and MeHg in rice plants grown under glasshouse and paddy field conditions. Aerobic conditions greatly decreased the amount of THg and MeHg taken up by rice plants and affected their distribution in different plant tissues. There were positive correlations between bioavailable Hg and THg in brown rice and roots and between numbers of SRB and MeHg in brown rice, roots, and rhizosphere soil. Furthermore, the community composition of SRB was dramatically influenced by the water management regimes. Our results demonstrate that the greatly reduced bioavailability of Hg and production of MeHg are due to decreased SRB numbers and proportion of Hg methylators in the rhizosphere under aerobic conditions. These are the main reasons for the reduced Hg and MeHg accumulation in aerobically grown rice. Water management is indicated as an effective measure that can be used to reduce Hg and MeHg uptake by rice plants from Hg-contaminated paddy fields.

  2. Bioavailability of Promethazine during Spaceflight

    NASA Technical Reports Server (NTRS)

    Boyd, Jason L.; Wang, Zuwei; Putcha, Lakshmi

    2009-01-01

    Promethazine (PMZ) is the choice anti-motion sickness medication for treating space motion sickness (SMS) during flight. The side effects associated with PMZ include dizziness, drowsiness, sedation, and impaired psychomotor performance which could impact crew performance and mission operations. Early anecdotal reports from crewmembers indicate that these central nervous system side effects of PMZ are absent or greatly attenuated in microgravity, potentially due to changes in pharmacokinetics (PK) and pharmacodynamics in microgravity. These changes could also affect the therapeutic effectiveness of drugs in general and PMZ, in particular. In this investigation, we examined bioavailability and associated pharmacokinetics of PMZ in astronauts during and after space flight. Methods. Nine astronauts received, per their preference, PMZ (25 or 50 mg as intramuscular injection, oral tablet, or rectal suppository) on flight day one for the treatment of SMS and subsequently collected saliva samples and completed sleepiness scores for 72 h post dose. Thirty days after the astronauts returned to Earth, they repeated the protocol. Bioavailability and PK parameters were calculated and compared between flight and ground. Results. Maximum concentration (Cmax) was lower and time to reach Cmax (tmax) was longer in flight than on the ground. Area under the curve (AUC), a measure of bioavailability, was lower and biological half-life (t1/2) was longer in flight than on the ground. Conclusion. Results indicate that bioavailability of PMZ is reduced during spaceflight. Number of samples, sampling method, and sampling schedule significantly affected PK parameter estimates.

  3. Drug Bioavailability Data: (Un)Available.

    ERIC Educational Resources Information Center

    Capomacchia, Anthony C.; And Others

    1979-01-01

    The obtainability of drug bioavailability data from both brand-name and generic-drug manufacturers was studied to document the relative change in availability to pharmacy students of drug bioavailability data between 1978 and 1976 for drugs exhibiting bioavailability problems. The results indicate no major change. (JMD)

  4. Lead Speciation And Bioavailability In Apatite-Amended Sediments

    EPA Science Inventory

    The in situ sequestration of lead (Pb) in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS) with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions ...

  5. Influence of body condition on influenza a virus infection in mallard ducks: Experimental infection data

    USGS Publications Warehouse

    Arsnoe, D.M.; Ip, H.S.; Owen, J.C.

    2011-01-01

    Migrating waterfowl are implicated in the global spread of influenza A viruses (IAVs), and mallards (Anas platyrhynchos) are considered a particularly important IAV reservoir. Prevalence of IAV infection in waterfowl peaks during autumn pre-migration staging and then declines as birds reach wintering areas. Migration is energetically costly and birds often experience declines in body condition that may suppress immune function. We assessed how body condition affects susceptibility to infection, viral shedding and antibody production in wild-caught and captive-bred juvenile mallards challenged with low pathogenic avian influenza virus (LPAIV) H5N9. Wild mallards (n = 30) were separated into three experimental groups; each manipulated through food availability to a different condition level (-20%, -10%, and normal ??5% original body condition), and captive-bred mallards (n = 10) were maintained at normal condition. We found that wild mallards in normal condition were more susceptible to LPAIV infection, shed higher peak viral loads and shed viral RNA more frequently compared to birds in poor condition. Antibody production did not differ according to condition. We found that wild mallards did not differ from captive-bred mallards in viral intensity and duration of infection, but they did exhibit lower antibody titers and greater variation in viral load. Our findings suggest that reduced body condition negatively influences waterfowl host competence to LPAIV infection. This observation is contradictory to the recently proposed condition-dependent hypothesis, according to which birds in reduced condition would be more susceptible to IAV infection. The mechanisms responsible for reducing host competency among birds in poor condition remain unknown. Our research indicates body condition may influence the maintenance and spread of LPAIV by migrating waterfowl. ?? 2011 Arsnoe et al.

  6. Influence of body condition on influenza A virus infection in mallard ducks: Experimental infection data

    USGS Publications Warehouse

    Arsnoe, Dustin M.; Ip, Hon S.; Owen, Jennifer C.

    2011-01-01

    Migrating waterfowl are implicated in the global spread of influenza A viruses (IAVs), and mallards (Anas platyrhynchos) are considered a particularly important IAV reservoir. Prevalence of IAV infection in waterfowl peaks during autumn pre-migration staging and then declines as birds reach wintering areas. Migration is energetically costly and birds often experience declines in body condition that may suppress immune function. We assessed how body condition affects susceptibility to infection, viral shedding and antibody production in wild-caught and captive-bred juvenile mallards challenged with low pathogenic avian influenza virus (LPAIV) H5N9. Wild mallards (n = 30) were separated into three experimental groups; each manipulated through food availability to a different condition level (-20%, -10%, and normal ±5% original body condition), and captive-bred mallards (n = 10) were maintained at normal condition. We found that wild mallards in normal condition were more susceptible to LPAIV infection, shed higher peak viral loads and shed viral RNA more frequently compared to birds in poor condition. Antibody production did not differ according to condition. We found that wild mallards did not differ from captive-bred mallards in viral intensity and duration of infection, but they did exhibit lower antibody titers and greater variation in viral load. Our findings suggest that reduced body condition negatively influences waterfowl host competence to LPAIV infection. This observation is contradictory to the recently proposed condition-dependent hypothesis, according to which birds in reduced condition would be more susceptible to IAV infection. The mechanisms responsible for reducing host competency among birds in poor condition remain unknown. Our research indicates body condition may influence the maintenance and spread of LPAIV by migrating waterfowl.

  7. A critical review of social and structural conditions that influence HIV risk among Mexican deportees

    PubMed Central

    Pinedo, Miguel; Burgos, José Luis; Ojeda, Victoria D.

    2014-01-01

    Mexican migrants who are deported from the US may be at elevated risk for HIV infection. Deportations of Mexican migrants by the US have reached record numbers. We critically reviewed existing literature to assess how social and structural conditions in post-deportation settings can influence Mexican deported migrants' HIV risk. We also identify critical research gaps and make research recommendations. PMID:24583278

  8. Past Experience Influences the Processing of Stimulus Compounds in Human Pavlovian Conditioning

    ERIC Educational Resources Information Center

    Melchers, Klaus G.; Lachnit, Harold; Shanks, David R.

    2004-01-01

    In two human skin conductance conditioning experiments we investigated whether processing of stimulus compounds can be influenced by past experience. Participants were either pre-trained with a discrimination problem that could be solved elementally (A+, B-, AB+, C- in Experiment 1 and A+, AB+, C-, CB- in Experiment 2) or one that required a…

  9. A critical review of social and structural conditions that influence HIV risk among Mexican deportees.

    PubMed

    Pinedo, Miguel; Burgos, José Luis; Ojeda, Victoria D

    2014-05-01

    Mexican migrants who are deported from the US may be at elevated risk for HIV infection. Deportations of Mexican migrants by the US have reached record numbers. We critically reviewed existing literature to assess how social and structural conditions in post-deportation settings can influence Mexican deported migrants' HIV risk. We also identify critical research gaps and make research recommendations.

  10. Antibacterial Properties of Copper Nanoparticle Dispersions: Influence of Synthesis Conditions and Physicochemical Characteristics

    NASA Astrophysics Data System (ADS)

    Godymchuk, A.; Frolov, G.; Gusev, A.; Zakharova, O.; Yunda, E.; Kuznetsov, D.; Kolesnikov, E.

    2015-11-01

    The production of bactericidal plasters, bandages and medicines with the inclusion of copper nanoparticles and copper ions may have a great potential in terms of their biomedical application. The work considers the influence of the synthesis conditions, size, aggregation status, and charge of nanoparticles in aqueous solutions as well as the type of microorganisms to the antibacterial properties of water suspensions of electroexplosive copper nanoparticles in the conditions in vitro in relation to strains Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus. Water dispersions of copper nanoparticles were shown to inhibit the growth of test cells for both G+ and G- microbacteria but the degree of such an influence strongly depended on the type of a test strain. The authors have demonstrated that use of deeply purified water and alcohol-containing stabilizers at the synthesis of nanoparticles via metals electric erosion in the liquid prevents the copper nanoparticles coagulation and significantly influences on their physicochemical characteristics and, consequently, antibacterial properties.

  11. Distribution, speciation, and bioavailability of lanthanides in the Rhine-Meuse estuary, The Netherlands.

    PubMed

    Moermond, C T; Tijink, J; van Wezel, A P; Koelmans, A A

    2001-09-01

    Changing environmental conditions may influence the fate and bioavailability of lanthanides (part of the rare earth elements [Ln]) in estuaries. The aim of this study was to quantify the variation in estuarine lanthanide solid/water distribution, speciation, and bioaccumulation. The latter was studied in the amphipod Corophium volutator under field and laboratory conditions. Calculations with the chemical equilibrium model MINEQL+ indicate that dissolved lanthanides are complexed mainly to carbonates and dissolved organic matter. In the water phase, the relative abundance of the free ion, LnCO3, and humic complexes decreases from lanthanum to lutetium, whereas the relative abundance of Ln(CO3)2 increases. Cerium and europium anomalies were found in the water. Europium anomalies were also found in some biota. The biota sediment accumulation factors (BSAFs) decreased across the series from lanthanum to lutetium. Regression analysis revealed that alkalinity correlated negatively with lanthanide uptake. This suggests that increasing complexation reduced bioavailability under the prevailing conditions. The BSAFs did not depend on salinity or pH, which may simplify sediment-quality criteria for fresh versus saline waters. Field BSAFs were significantly lower than laboratory values for the same sediments, which is explained by adaptation of the organisms to lanthanides.

  12. The influence of initial and surface boundary conditions on a model-generated January climatology

    NASA Technical Reports Server (NTRS)

    Wu, K. F.; Spar, J.

    1981-01-01

    The influence on a model-generated January climate of various surface boundary conditions, as well as initial conditions, was studied by using the GISS coarse-mesh climate model. Four experiments - two with water planets, one with flat continents, and one with mountains - were used to investigate the effects of initial conditions, and the thermal and dynamical effects of the surface on the model generated-climate. However, climatological mean zonal-symmetric sea surface temperature is used in all four runs over the model oceans. Moreover, zero ground wetness and uniform ground albedo except for snow are used in the last experiments.

  13. Vitamin B12 sources and bioavailability.

    PubMed

    Watanabe, Fumio

    2007-11-01

    The usual dietary sources of vitamin B(12) are animal foods, meat, milk, egg, fish, and shellfish. As the intrinsic factor-mediated intestinal absorption system is estimated to be saturated at about 1.5-2.0 microg per meal under physiologic conditions, vitamin B(12) bioavailability significantly decreases with increasing intake of vitamin B(12) per meal. The bioavailability of vitamin B(12) in healthy humans from fish meat, sheep meat, and chicken meat averaged 42%, 56%-89%, and 61%-66%, respectively. Vitamin B(12) in eggs seems to be poorly absorbed (< 9%) relative to other animal food products. In the Dietary Reference Intakes in the United States and Japan, it is assumed that 50% of dietary vitamin B(12) is absorbed by healthy adults with normal gastro-intestinal function. Some plant foods, dried green and purple lavers (nori) contain substantial amounts of vitamin B(12), although other edible algae contained none or only traces of vitamin B(12). Most of the edible blue-green algae (cyanobacteria) used for human supplements predominantly contain pseudovitamin B(12), which is inactive in humans. The edible cyanobacteria are not suitable for use as vitamin B(12) sources, especially in vegans. Fortified breakfast cereals are a particularly valuable source of vitamin B(12) for vegans and elderly people. Production of some vitamin B(12)-enriched vegetables is also being devised.

  14. Copper dynamics under alternating redox conditions is influenced by soil properties and contamination source.

    PubMed

    Balint, Ramona; Said-Pullicino, Daniel; Ajmone-Marsan, Franco

    2015-02-01

    Understanding the effect of soil redox conditions on contaminant dynamics is of significant importance for evaluating their lability, mobility and potential transfer to other environmental compartments. Under changing redox conditions, soil properties and constituents such as Fe and Mn (hydr)oxides and organic matter (OM) may influence the behavior of associated metallic elements (MEs). In this work, the redox-driven release and redistribution of Cu between different soil pools was studied in three soils having different contamination sources. This was achieved by subjecting soil columns to a series of alternating reducing and oxidizing cycles under non-limiting C conditions, and assessing their influence on soil pore water, leachate and solid phase composition. Results showed that, in all soils, alternating redox conditions led to an increase in the distribution of Cu in the more labile fractions, consequently enhancing its susceptibility to loss. This was generally linked to the redox-driven cycling of Fe, Mn and dissolved organic matter (DOM). In fact, results suggested that the reductive dissolution of Fe and Mn (hydr)oxides and subsequent reprecipitation as poorly-ordered phases under oxic conditions contributed to the release and mobilization of Cu and/or Cu-containing organometallic complexes. However, the behavior of Cu, as well as the mechanisms controlling Cu release and loss with redox cycling, was influenced by both soil properties (e.g. pH, contents of easily reducible Fe and Mn (hydr)oxides) and source of Cu contamination.

  15. Influence of Photospheric Magnetic Conditions on the Catastrophic Behaviors of Flux Ropes in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui; Liu, Jiajia

    2017-02-01

    Since only the magnetic conditions at the photosphere can be routinely observed in current observations, it is of great significance to determine the influences of photospheric magnetic conditions on solar eruptive activities. Previous studies about catastrophe indicated that the magnetic system consisting of a flux rope in a partially open bipolar field is subject to catastrophe, but not if the bipolar field is completely closed under the same specified photospheric conditions. In order to investigate the influence of the photospheric magnetic conditions on the catastrophic behavior of this system, we expand upon the 2.5-dimensional ideal magnetohydrodynamic model in Cartesian coordinates to simulate the evolution of the equilibrium states of the system under different photospheric flux distributions. Our simulation results reveal that a catastrophe occurs only when the photospheric flux is not concentrated too much toward the polarity inversion line and the source regions of the bipolar field are not too weak; otherwise no catastrophe occurs. As a result, under certain photospheric conditions, a catastrophe could take place in a completely closed configuration, whereas it ceases to exist in a partially open configuration. This indicates that whether the background field is completely closed or partially open is not the only necessary condition for the existence of catastrophe, and that the photospheric conditions also play a crucial role in the catastrophic behavior of the flux rope system.

  16. Bioavailability of iron, zinc, folic acid, and vitamin A from fortified maize.

    PubMed

    Moretti, Diego; Biebinger, Ralf; Bruins, Maaike J; Hoeft, Birgit; Kraemer, Klaus

    2014-04-01

    Several strategies appear suitable to improve iron and zinc bioavailability from fortified maize, and fortification per se will increase the intake of bioavailable iron and zinc. Corn masa flour or whole maize should be fortified with sodium iron ethylenediaminetetraacetate (NaFeEDTA), ferrous fumarate, or ferrous sulfate, and degermed corn flour should be fortified with ferrous sulfate or ferrous fumarate. The choice of zinc fortificant appears to have a limited impact on zinc bioavailability. Phytic acid is a major inhibitor of both iron and zinc absorption. Degermination at the mill will reduce phytic acid content, and degermed maize appears to be a suitable vehicle for iron and zinc fortification. Enzymatic phytate degradation may be a suitable home-based technique to enhance the bioavailability of iron and zinc from fortified maize. Bioavailability experiments with low phytic acid-containing maize varieties have suggested an improved zinc bioavailability compared to wild-type counterparts. The bioavailability of folic acid from maize porridge was reported to be slightly higher than from baked wheat bread. The bioavailability of vitamin A provided as encapsulated retinyl esters is generally high and is typically not strongly influenced by the food matrix, but has not been fully investigated in maize.

  17. The spatial structure of bacterial communities is influenced by historical environmental conditions.

    PubMed

    Andersson, Martin G I; Berga, Mercè; Lindström, Eva S; Langenheder, Silke

    2014-05-01

    The spatial structure of ecological communities, including that of bacteria, is often influenced by species sorting by contemporary environmental conditions. Moreover, historical processes, i.e., ecological and evolutionary events that have occurred at some point in the past, such as dispersal limitation, drift, priority effects, or selection by past environmental conditions, can be important, but are generally investigated much less. Here, we conducted a field study using 16 rock pools, where we specifically compared the importance of past vs. contemporary environmental conditions for bacterial community structure by correlating present differences in bacterial community composition among pools to environmental conditions measured on the same day, as well as to those measured 2, 4, 6, and 8 d earlier. The results prove that selection by past environmental conditions exists, since we were able to show that bacterial communities are, to a greater extent, an imprint of past compared to contemporary environmental conditions. We suggest that this is the result of a combination of different mechanisms, including priority effects that cause rapid adaptation to new environmental conditions of taxa that have been initially selected by past environmental conditions, and slower rates of turnover in community composition compared to environmental conditions.

  18. Influences of initial launch conditions on flight performance of high altitude balloon ascending process

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Liu, Dongxu

    2015-08-01

    Influences of initial launch conditions on flight performance are addressed for the high altitude balloon ascending process. A novel dynamic model was established to describe thermodynamic and kinetic characteristics of balloon which consists of atmospheric, thermal and dynamic submodels. Based on the model, ascending processes of a high altitude balloon under different initial launch conditions were simulated. The initial launch conditions were classified into three types: inflating quantity, launch time and launch position. The ascending velocity and the differential pressure were defined and used as evaluation parameters of flight performance. Results showed that the inflating quantity is the most effective factor for ascending process, and the upper and lower limits were also proposed separately from safety and performance perspectives. For both launch time and launch location conditions, different solar radiation is the main effect approach during ascending process. Specifically, the influence mechanism of launch time in one day and launch longitude are completely identical due to the Earth's rotation. Results also showed that the sunset process is the optimal selection for safety of balloon and efficient utilization of solar energy. Due to the Earth's revolution, the influence mechanism of launch date and launch latitude are identical and the effects are more seasonal and less effective. Launch time and location should be considered comprehensively in practical operation of ballooning.

  19. Body size and condition influence migration timing of juvenile Arctic grayling

    USGS Publications Warehouse

    Heim, Kurt C.; Wipfli, Mark S.; Whitman, Matthew S.; Seitz, Andrew C

    2016-01-01

    Freshwater fishes utilising seasonally available habitats within annual migratory circuits time movements out of such habitats with changing hydrology, although individual attributes of fish may also mediate the behavioural response to environmental conditions. We tagged juvenile Arctic grayling in a seasonally flowing stream on the Arctic Coastal Plain in Alaska and recorded migration timing towards overwintering habitat. We examined the relationship between individual migration date, and fork length (FL) and body condition index (BCI) for fish tagged in June, July and August in three separate models. Larger fish migrated earlier; however, only the August model suggested a significant relationship with BCI. In this model, 42% of variability in migration timing was explained by FL and BCI, and fish in better condition were predicted to migrate earlier than those in poor condition. Here, the majority (33%) of variability was captured by FL with an additional 9% attributable to BCI. We also noted strong seasonal trends in BCI reflecting overwinter mass loss and subsequent growth within the study area. These results are interpreted in the context of size and energetic state-specific risks of overwinter starvation and mortality (which can be very high in the Arctic), which may influence individuals at greater risk to extend summer foraging in a risky, yet prey rich, habitat. Our research provides further evidence that heterogeneity among individuals within a population can influence migratory behaviour and identifies potential risks to late season migrants in Arctic beaded stream habitats influenced by climate change and petroleum development.

  20. In vitro bioavailability of iron from the heme analogue sodium iron chlorophyllin.

    PubMed

    Miret, Silvia; Tascioglu, Serpil; van der Burg, Monique; Frenken, Leon; Klaffke, Werner

    2010-01-27

    The use of heme analogues from vegetable origin could provide an alternative iron source of potentially high bioavailability. Sodium iron chlorophyllin is a water-soluble semisynthetic chlorophyll derivative where the magnesium in the porphyrin ring has been substituted by iron. We have used an in vitro model that combines gastric and intestinal digestion followed by intestinal iron uptake in Caco-2 cells to determine the bioavailability of iron from sodium iron chlorophyllin. Our results demonstrate that sodium iron chlorophyllin is stable under simulated gastrointestinal conditions and is able to deliver bioavailable iron to Caco-2 cells. Similar to the heme, the bioavailability of iron from sodium iron chlorophyllin is dependent on the food matrix, and it was inhibited by calcium. Potentially, sodium iron chlorophyllin could be used as an iron fortificant from vegetable origin with high bioavailability.

  1. Influence of sound-conditioning on noise-induced susceptibility of distortion-product otoacoustic emissions.

    PubMed

    Luebke, Anne E; Stagner, Barden B; Martin, Glen K; Lonsbury-Martin, Brenda L

    2015-07-01

    Cochlear damage caused by loud sounds can be attenuated by "sound-conditioning" methods. The amount of adaptation for distortion product otoacoustic emissions (DPOAEs) measured in alert rabbits previously predicted an ear's susceptibility to a subsequent noise exposure. The present study investigated if sound-conditioning influenced the robustness of such DPOAE adaptation, and if such conditioning elicited more protection by increasing the amount of DPOAE adaptation. Toward this end, rabbits were divided into two study groups: (1) experimental animals exposed to a sound-conditioning protocol, and (2) unconditioned control animals. After base-line measures, all rabbits were exposed to an overstimulation paradigm consisting of an octave band noise, and then re-assessed 3 weeks post-exposure to determine permanent changes in DPOAEs. A major result was that prior sound-conditioning protected reductions in DPOAE levels by an average of 10-15 dB. However, DPOAE adaptation decreased with sound-conditioning, so that such conditioning was no longer related to noise-induced reductions in DPOAEs. Together, these findings suggest that sound-conditioning affected neural pathways other than those that likely mediate DPOAE adaptation (e.g., medial olivocochlear efferent and/or middle-ear muscle reflexes).

  2. Do conditional cash transfers influence migration? A study using experimental data from the Mexican PROGRESA program.

    PubMed

    Stecklov, Guy; Winters, Paul; Stampini, Marco; Davis, Benjamin

    2005-11-01

    Prior research on Mexican migration has shown that social networks and economic incentives play an important role in determining migration outcomes. We use experimental data from PROGRESA, Mexico's primary poverty-reduction program, to evaluate the effects of conditional cash transfers on migration both domestically and to the United States. Our study complements a growing body of literature aimed at overcoming longstanding hurdles to the establishment of causal validity in empirical studies of migration. Analysis based on the data collected before and after the program's onset shows that conditional transfers reduce U.S. migration but not domestic migration. The data also enable us to explore the role of existing family and community migration networks. The results show that migration networks strongly influence migration, but that the effect of conditional transfers on migration is apparently not mediated by existing migration network structures. Our results suggest that conditional transfers may be helpful in managing rural out-migration, particularly to the United States.

  3. [Advance in the bioavailability monitoring of heavy metal based on microbial whole-cell sensor].

    PubMed

    Hou, Qi-Hui; Ma, An-Shou; Zhuang, Xiu-Liang; Zhuang, Guo-Qiang

    2013-01-01

    Microbial whole-cell biosensor is an excellent tool to assess the bioavailability of heavy metal in soil and water. However, the traditional physicochemical instruments are applied to detect the total metal. Furthermore, microbial whole-cell biosensor is simple, rapid and economical in manipulating, and is thus a highly qualified candidate for emergency detection of pollution incidents. The biological component of microbial whole-cell biosensor mostly consists of metalloregulatory proteins and reporter genes. In detail, metalloregulatory proteins mainly include the MerR family, ArsR family and RS family, and reporter genes mainly include gfp, lux and luc. Metalloregulatory protein and reporter gene are related to the sensitivity, specificity and properties in monitoring. The bioavailability of heavy metals is alterable under different conditions, influenced by pH, chelate and detection methods and so on. Increasing the accumulation of intracellular heavy metal, modifying the metalloregulatory proteins and optimizing the detecting conditions are important for improving the sensitivity, specificity and accuracy of the microbial whole-cell biosensor. The future direction of microbial whole-cell biosensor is to realize the monitoring of pollutions in situ and on line.

  4. The contact condition influence on stability and energy efficiency of quadruped robot

    NASA Astrophysics Data System (ADS)

    Lei, Jingtao; Wang, Tianmiao; Gao, Feng

    2008-10-01

    Quadruped robot has attribute of serial and parallel manipulator with multi-loop mechanism, with more DOF of each leg and intermittent contact with ground during walking, the trot gait of quadruped robot belongs to dynamic waking, compared to the crawl gait, the walking speed is higher, but the robot becomes unstable, it is difficult to keep dynamically stable walking. In this paper, we mainly analyze the condition for the quadruped robot to realize dynamically stable walking, establish centroid orbit equation based on ZMP (Zero Moment Point) stability theory, on the other hand , we study contact impact and friction influence on stability and energy efficiency. Because of the periodic contact between foots and ground, the contact impact and friction are considered to establish spring-damp nonlinear dynamics model. Robot need to be controlled to meet ZMP stability condition and contact constraint condition. Based on the virtual prototyping model, we study control algorithm considering contact condition, the contact compensator and friction compensator are adopted. The contact force and the influence of different contact conditions on the energy efficiency during whole gait cycle are obtained.

  5. Genotypic influence on aversive conditioning in honeybees, using a novel thermal reinforcement procedure.

    PubMed

    Junca, Pierre; Carcaud, Julie; Moulin, Sibyle; Garnery, Lionel; Sandoz, Jean-Christophe

    2014-01-01

    In Pavlovian conditioning, animals learn to associate initially neutral stimuli with positive or negative outcomes, leading to appetitive and aversive learning respectively. The honeybee (Apis mellifera) is a prominent invertebrate model for studying both versions of olfactory learning and for unraveling the influence of genotype. As a queen bee mates with about 15 males, her worker offspring belong to as many, genetically-different patrilines. While the genetic dependency of appetitive learning is well established in bees, it is not the case for aversive learning, as a robust protocol was only developed recently. In the original conditioning of the sting extension response (SER), bees learn to associate an odor (conditioned stimulus - CS) with an electric shock (unconditioned stimulus - US). This US is however not a natural stimulus for bees, which may represent a potential caveat for dissecting the genetics underlying aversive learning. We thus first tested heat as a potential new US for SER conditioning. We show that thermal stimulation of several sensory structures on the bee's body triggers the SER, in a temperature-dependent manner. Moreover, heat applied to the antennae, mouthparts or legs is an efficient US for SER conditioning. Then, using microsatellite analysis, we analyzed heat sensitivity and aversive learning performances in ten worker patrilines issued from a naturally inseminated queen. We demonstrate a strong influence of genotype on aversive learning, possibly indicating the existence of a genetic determinism of this capacity. Such determinism could be instrumental for efficient task partitioning within the hive.

  6. Genotypic Influence on Aversive Conditioning in Honeybees, Using a Novel Thermal Reinforcement Procedure

    PubMed Central

    Junca, Pierre; Carcaud, Julie; Moulin, Sibyle; Garnery, Lionel; Sandoz, Jean-Christophe

    2014-01-01

    In Pavlovian conditioning, animals learn to associate initially neutral stimuli with positive or negative outcomes, leading to appetitive and aversive learning respectively. The honeybee (Apis mellifera) is a prominent invertebrate model for studying both versions of olfactory learning and for unraveling the influence of genotype. As a queen bee mates with about 15 males, her worker offspring belong to as many, genetically-different patrilines. While the genetic dependency of appetitive learning is well established in bees, it is not the case for aversive learning, as a robust protocol was only developed recently. In the original conditioning of the sting extension response (SER), bees learn to associate an odor (conditioned stimulus - CS) with an electric shock (unconditioned stimulus - US). This US is however not a natural stimulus for bees, which may represent a potential caveat for dissecting the genetics underlying aversive learning. We thus first tested heat as a potential new US for SER conditioning. We show that thermal stimulation of several sensory structures on the bee’s body triggers the SER, in a temperature-dependent manner. Moreover, heat applied to the antennae, mouthparts or legs is an efficient US for SER conditioning. Then, using microsatellite analysis, we analyzed heat sensitivity and aversive learning performances in ten worker patrilines issued from a naturally inseminated queen. We demonstrate a strong influence of genotype on aversive learning, possibly indicating the existence of a genetic determinism of this capacity. Such determinism could be instrumental for efficient task partitioning within the hive. PMID:24828422

  7. Observations on the Influence of Tool-Sheet Contact Conditions on an Incremental Forming Process

    NASA Astrophysics Data System (ADS)

    Durante, M.; Formisano, A.; Langella, A.

    2011-08-01

    The influence of tool-sheet contact conditions on features such as surface roughness, forming force, and formability was evaluated for components produced by incremental forming, a highly flexible innovative sheet metal-forming process. Experimental tests were carried out on sheets of AA7075T0 to create two types of component: pyramid frusta (for the evaluation of roughness and force) and cone frusta (for the evaluation of formability). Four different types of tool-sheet contact were analyzed, using two types of tool. From the experimental tests, the influence on the surface finishing and on the trend of the forming forces depending on contact type was revealed. Contact types do not, however, influence sheet formability.

  8. Topological quantum scattering under the influence of a nontrivial boundary condition

    NASA Astrophysics Data System (ADS)

    Mota, Herondy

    2016-04-01

    We consider the quantum scattering problem of a relativistic particle in (2 + 1)-dimensional cosmic string spacetime under the influence of a nontrivial boundary condition imposed on the solution of the Klein-Gordon equation. The solution is then shifted as consequence of the nontrivial boundary condition and the role of the phase shift is to produce an Aharonov-Bohm-like effect. We examine the connection between this phase shift and the electromagnetic and gravitational analogous of the Aharonov-Bohm effect and compare the present results with previous ones obtained in the literature, also considering non-relativistic cases.

  9. Influence of Experimental Conditions on Electronic Tongue Results—Case of Valsartan Minitablets Dissolution

    PubMed Central

    Wesoły, Małgorzata; Kluk, Anna; Sznitowska, Małgorzata; Ciosek, Patrycja; Wróblewski, Wojciech

    2016-01-01

    A potentiometric electronic tongue was applied to study the release of valsartan from pharmaceutical formulations, i.e., minitablets uncoated and coated with Eudragit E. Special attention was paid to evaluate the influence of medium temperature and composition, as well as to compare the performances of the sensor arrays working in various hydrodynamic conditions. The drug dissolution profiles registered with the ion-sensitive electrodes were compared with standard dissolution tests performed with USP Apparatus 2 (paddle). Moreover, the signal changes of all sensors were processed by principal component analysis to visualize the release modifications, related to the presence of the coating agent. Finally, the importance and influence of the experimental conditions on the results obtained using potentiometric sensor arrays were discussed. PMID:27563904

  10. Influence of meteorological conditions on correlation between aerosol and cloud in summer

    NASA Astrophysics Data System (ADS)

    Shi, Lamei; Zhang, Jiahua; Yao, Fengmei; Han, Xinlei; Igbawua, Tertsea; Liu, Yuqin; Zhang, Da

    2017-04-01

    Aerosols can affect the atmospheric radiation balance through direct and indirect effects. The formation and development of cloud and precipitation influenced by aerosols differ significantly from each other in different meteorological conditions. In this work, we used the MODIS's daily Aerosol Optical Depth (AOD), Cloud Effective Radius (CER), Cloud Top Temperature (CTT), Cloud Water Path (CWP) and ECMWF's Relative Humidity (RH), Vertical Velocity (VV) and Horizontal Wind (HW) (from 2005 to 2008) to reveal the influence of meteorological factors on the distribution of aerosols, and also the correlation between aerosols and clouds. The study was designed in such a way that, the RH, VV, Upwind (UW), Downwind (DW) and CWP were divided into several intervals, to quantify the relationship between AOD and CER by controlling one single variable or two comprehensive variables over the mountains and plains. At the same time, the effect of wind speed and direction on polluted conditions was analyzed through the superposed spatial distribution map of wind and AOD. The conclusions are as follows: (1) The wind coming from mountains dispelled aerosols while the sea breeze invigorated aerosols, and the upwind showed a markedly negative relevance with AOD. (2) The strong upwind contributed to the positive relationship between AOD and CER, and the correlation rose by 38% after excluding the condition where CWP < 34 g/m2. (3) For the horizontal wind, only the zonal wind over the plains had obvious effects on the correlation, while the meridonal wind did not show evident influence. (4) For the plains, when CWP values were within the interval of 0-34 g/m2 and 74-150 g/m2, the correlation was positive, while in 34-74 g/m2, it was negative. However, it is generally positive either over the mountains or in clean conditions. Moreover, the influence of RH on the correlation was consistent with that of CWP.

  11. Influence of temper condition on the nonlinear stress-strain behavior of boron-aluminum

    NASA Technical Reports Server (NTRS)

    Kennedy, J. M.; Herakovich, E. T.; Tenney, D. R.

    1977-01-01

    The influence of temper condition on the tensile and compressive stress-strain behavior for six boron-aluminum laminates was investigated. In addition to monotonic tension and compression tests, tension-tension, compression-compression, and tension--compression tests were conducted to study the effects of cyclic loading. Tensile strength results are a function of the laminate configuration; unidirectional laminates were affected considerably more than other laminates with some strength values increasing and others decreasing.

  12. Bioavailability of organically bound Fe to model phytoplankton of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Hassler, C. S.; Schoemann, V.

    2009-10-01

    Iron (Fe) is known to be mostly bound to organic ligands and to limit primary productivity in the Southern Ocean. It is thus important to investigate the bioavailability of organically bound Fe. In this study, we used four phytoplankton species of the Southern Ocean (Phaeocystis sp., Chaetoceros sp., Fragilariopsis kerguelensis and Thalassiosira antarctica Comber) to measure the influence of various organic ligands on Fe solubility and bioavailability. Short-term uptake Fe:C ratios were inversely related to the surface area to volume ratios of the phytoplankton. The ratio of extracellular to intracellular Fe is used to discuss the relative importance of diffusive supply and uptake to control Fe bioavailability. The effect of excess organic ligands on Fe bioavailability cannot be solely explained by their effect on Fe solubility. For most strains studied, the bioavailability of Fe can be enhanced relative to inorganic Fe in the presence of porphyrin, catecholate siderophore and saccharides whereas it was decreased in presence of hydroxamate siderophore and organic amine. For Thalassiosira, iron bioavailability was not affected by the presence of porphyrin, catecholate siderophore and saccharides. The enhancement of Fe bioavailability in presence of saccharides is presented as the result from both the formation of bioavailable (or chemically labile) organic form of Fe and the stabilisation of Fe within the dissolved phase. Given the ubiquitous presence of saccharides in the ocean, these compounds might represent an important factor to control the basal level of soluble and bioavailable Fe. Results show that the use of model phytoplankton is promising to improve mechanistic understanding of Fe bioavailability and primary productivity in HNLC regions of the ocean.

  13. Measurements of mercury methylation rates and bioavailability in the Allequash Creek Wetland, Northern Wisconsin

    NASA Astrophysics Data System (ADS)

    Creswell, J. E.; Babiarz, C. L.; Shafer, M. M.; Armstrong, D. E.

    2008-12-01

    amendments into homogenized sediments is that this spreads the amended mercury throughout the core section, avoiding injection channel effects. The influence of Hg(II) speciation on methylation is also being examined. Preliminary results show gross mercury methylation occurring at both sites sampled, although net methylation is negative throughout most of the depth profile, suggesting that the chemical conditions controlling the bioavailability of Hg(II) are highly variable. Because this is the first time such measurements have been made in this system, these data provide an important baseline for future studies of mercury bioavailability in northern wetlands.

  14. Bioavailability-Based In Situ Remediation To Meet Future Lead (Pb) Standards in Urban Soils and Gardens

    DOE PAGES

    Henry, Heather; Naujokas, Marisa F.; Attanayake, Chammi; ...

    2015-07-03

    Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to 5 μg/dL. The lower reference value combined with increased repurposing of postindustrial lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result, regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This study discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the context of lower SSLs and identifies research needs to better address those challenges. Althoughmore » in situ remediation with phosphate amendments is a viable option, the scope of the problem and conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total Pb concentrations. However, variability in soil composition can influence bioavailability testing and soil amendment effectiveness. Finally, more data are urgently needed to better understand this variability and increase confidence in using these approaches in risk-based decision making, particularly in urban areas.« less

  15. Bioavailability-Based In Situ Remediation To Meet Future Lead (Pb) Standards in Urban Soils and Gardens

    SciTech Connect

    Henry, Heather; Naujokas, Marisa F.; Attanayake, Chammi; Basta, Nicholas T.; Cheng, Zhongqi; Hettiarachchi, Ganga M.; Maddaloni, Mark; Schadt, Christopher; Scheckel, Kirk G.

    2015-07-03

    Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to 5 μg/dL. The lower reference value combined with increased repurposing of postindustrial lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result, regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This study discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the context of lower SSLs and identifies research needs to better address those challenges. Although in situ remediation with phosphate amendments is a viable option, the scope of the problem and conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total Pb concentrations. However, variability in soil composition can influence bioavailability testing and soil amendment effectiveness. Finally, more data are urgently needed to better understand this variability and increase confidence in using these approaches in risk-based decision making, particularly in urban areas.

  16. Bioavailability-Based In Situ Remediation To Meet Future Lead (Pb) Standards in Urban Soils and Gardens.

    PubMed

    Henry, Heather; Naujokas, Marisa F; Attanayake, Chammi; Basta, Nicholas T; Cheng, Zhongqi; Hettiarachchi, Ganga M; Maddaloni, Mark; Schadt, Christopher; Scheckel, Kirk G

    2015-08-04

    Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to 5 μg/dL. The lower reference value combined with increased repurposing of postindustrial lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result, regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This paper discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the context of lower SSLs and identifies research needs to better address those challenges. Although in situ remediation with phosphate amendments is a viable option, the scope of the problem and conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total Pb concentrations. However, variability in soil composition can influence bioavailability testing and soil amendment effectiveness. More data are urgently needed to better understand this variability and increase confidence in using these approaches in risk-based decision making, particularly in urban areas.

  17. Influence of pH and media composition on suspension stability of silver, zinc oxide, and titanium dioxide nanoparticles and immobilization of Daphnia magna under guideline testing conditions.

    PubMed

    Cupi, Denisa; Hartmann, Nanna B; Baun, Anders

    2016-05-01

    In aquatic toxicity testing of engineered nanoparticles (ENPs) the process of agglomeration is very important as it may alter bioavailability and toxicity. In the present study, we aimed to identify test conditions that are favorable for maintaining stable ENP suspensions. We evaluated the influence of key environmental parameters: pH (2-12) and ionic strength using M7, Soft EPA (S EPA) medium, and Very Soft EPA (VS EPA) medium; and observed the influence of these parameters on zeta potential, zeta average, and acute immobilization of Daphnia magna for three different ENPs. Despite being sterically stabilized, test suspensions of silver (Ag) ENPs formed large agglomerates in both VS EPA and M7 media; and toxicity was found to be higher in VS EPA medium due to increased dissolution. Low-agglomerate suspensions for zinc oxide (ZnO) could be obtained at pH 7 in VS EPA medium, but the increase in dissolution caused higher toxicity than in M7 medium. Titanium dioxide (TiO2) ENPs had a point of zero charge in the range of pH 7-8. At pH 7 in VS EPA, agglomerates with smaller hydrodynamic diameters (~200nm) were present compared to the high ionic strength M7 medium where hydrodynamic diameters reached micrometer range. The stable suspensions of TiO2 ENPs caused immobilization of D. magna, 48-h EC50 value of 13.7mgL(-1) (95% CI, 2.4mg-79.1mgL(-1)); whereas no toxicity was seen in the unstable, highly agglomerated M7 medium suspensions, 48-h EC50 >100mgL(-1). The current study provides a preliminary approach for methodology in testing and assessing stability and toxicity of ENPs in aquatic toxicity tests of regulatory relevance.

  18. Relative Bioavailability and Bioaccessability and Speciation of ...

    EPA Pesticide Factsheets

    Background: Assessment of soil arsenic (As) bioavailability may profoundly affect the extent of remediation required at contaminated sites by improving human exposure estimates. Because small adjustments in soil As bioavailability estimates can significantly alter risk assessments and remediation goals, convenient, rapid, reliable, and inexpensive tools are needed to determine soil As bioavailability. Objectives: We evaluated inexpensive methods for assessing As bioavailability in soil as a means to improve human exposure estimates and potentially reduce remediation costs. Methods: Nine soils from residential sites affected by mining or smelting activity and two National Institute of Standards and Technology standard reference materials were evaluated for As bioavailability, bioaccessibility, and speciation. Arsenic bioavailability was determined using an in vivo mouse model, and As bioaccessibility was determined using the Solubility/Bioavailability Research Consortium in vitro assay. Arsenic speciation in soil and selected soil physicochemical properties were also evaluated to determine whether these parameters could be used as predictors of As bio¬availability and bioaccessibility. Results: In the mouse assay, we compared bioavailabilities of As in soils with that for sodium arsenate. Relative bioavailabilities (RBAs) of soil As ranged from 11% to 53% (mean, 33%). In vitro soil As bioaccessibility values were strongly correlated with soil As RBAs (R

  19. Schwann cell migration and neurite outgrowth are influenced by media conditioned by epineurial fibroblasts.

    PubMed

    van Neerven, S G A; Pannaye, P; Bozkurt, A; Van Nieuwenhoven, F; Joosten, E; Hermans, E; Taccola, G; Deumens, R

    2013-11-12

    The regenerative capacity of the peripheral nervous system is largely related to Schwann cells undergoing proliferation and migration after injury and forming growth-supporting substrates for severed axons. Novel data show that fibroblasts to a certain extent regulate the pro-regenerative behavior of Schwann cells. In the setting of peripheral nerve injury, the fibroblasts that form the epineurium come into close contact with both Schwann cells and peripheral axons, but the potential influence on these latter two cell types has not been studied yet. In the present study we explored whether culture media, conditioned by epineurial fibroblasts can influence Schwann cells and/or neurite outgrowth from dorsal root ganglia neurons in vitro. Our data indicate that epineurial fibroblast-conditioned culture media substantially increase Schwann cell migration and the outgrowth of neurites. Schwann cell proliferation remained largely unaffected. These same read-out parameters were assayed in a condition where epineurial fibroblasts were subjected to stretch-cell-stress, a mechanical stressor that plays an important role in traumatic peripheral nerve injuries. Stretch-cell-stress of epineurial fibroblasts did not further change the positive effects of conditioned media on Schwann cell migration and neurite outgrowth. From these data we conclude that an as yet unknown pro-regenerative role can be attributed to epineurial fibroblasts, implying that such cells may affect the outcome of severe peripheral nerve injury.

  20. Influence of industrial processing on orange juice flavanone solubility and transformation to chalcones under gastrointestinal conditions.

    PubMed

    Gil-Izquierdo, Angel; Gil, María Isabel; Tomas-Barberan, Francisco Abraham; Ferreres, Federico

    2003-05-07

    Orange juice manufactured at industrial scale was subjected to digestion under in vitro gastrointestinal conditions (pH, temperature, and enzyme and chemical conditions) to evaluate the influence of individual industrial processing treatments on flavanone solubility, stability, and ability to permeate through a membrane under simulated physiological conditions. Four industrial processes including squeezing, standard pasteurization, concentration, and freezing were evaluated. Hand squeezing was compared with industrial squeezing. After in vitro gastrointestinal digestion of the orange juices, the flavanones able to permeate through a dialysis membrane, and those remaining in the retentate were evaluated by HPLC as were those present in the insoluble fraction. In all of the assayed orange juices, a high content of precipitated chalcones ( approximately 70% of the total flavanones) was formed under the physiological conditions of the gastrointestinal tract. Hand squeezing provided a higher concentration of flavanones in the permeated fraction and lower transformation to chalcones than industrial squeezing. Standard pasteurization did not influence the solubility and permeability of the orange juice flavanones and chalcones. Industrial concentration did not affect the amount of flavanones able to permeate but decreased the chalcones produced. Juices produced from frozen orange juice contained considerably smaller amounts of both soluble flavanones and insoluble chalcones.

  1. Bioavailability and Pharmacodynamics of Promethazine in Human Subjects

    NASA Technical Reports Server (NTRS)

    Putcha, Lakshmi; Flynn, Chris; Paloski, W. H. (Technical Monitor)

    2000-01-01

    Space Motion Sickness (SMS) is often treated in space with promethazine (PMZ). Anecdotal reports indicate that the common side effects of drowsiness and decrements in cognitive performance that are associated with PMZ administration (50 mg IM on the ground, are absent or less pronounced in space suggesting I that-the bioavailability and/or pharmacodynamic behavior of PMZ may be altered during space flight. There are limited flight opportunities available for clinical research in space, the NRA-99, therefore, solicits research required to improve, or answer specific questions about in-flight diagnosis, therapy, and post-flight rehabilitation. We propose here, to establish a noninvasive method for pharmacodynamic and therapeutic assessment of PMZ. The specific objectives of the proposed research are to, 1. Establish a saliva to plasma ratio of PMZ after administration, 2. Estimate the relative bioavailability of the three flight-specific dosage forms of PMZ, and 3. Establish the dose-response relationship of PMZ. We will estimate the bioavailability of intramuscular injection (IM), oral tablets and rectal suppositories in normal subjects during ambulatory and antiorthostatic; bed rest (ABR) conditions using novel stable isotope techniques. Drowsiness, cognitive performance and salivary flow rate will be measured as a function of circulating drug concentrations after administration of three IM doses of PMZ. We will compare and contrast the bioavailability of PMZ during normal and ABR conditions to examine whether or not ABR can simulate changes in drug, absorption and availability similar to those anticipated in a microgravity environment. Results of this study will validate methods for an approved study with this medication awaiting a flight opportunity for manifestation. These data will also provide the much needed information on the dynamics and therapeutic index. of this medication and their implications on crew fatigue and performance in space. Key words

  2. Influence of extreme ambient temperatures and anaerobic conditions on Peltigera aphthosa (L.) Willd. viability

    NASA Astrophysics Data System (ADS)

    Dyakov, M. Yu.; Insarova, I. D.; Kharabadze, D. E.; Ptushenko, V. V.; Shtaer, O. V.

    2015-11-01

    Lichen are symbiotic systems constituted by heterotrophic fungi (mycobionts) and photosynthetic microorganism (photobionts). These organisms can survive under extreme stress conditions. The aim of this work was to study the influence of low (- 70 °C) or high (+ 70 °C) temperatures, temperature fluctuations from + 70 °C to - 70 °C, and anaerobic conditions on P. aphthosa (L.) Willd. viability. None of the studied stress factors affected significantly photosynthetic and respiratory activity of the thalli. No changes in morphology or ultrastructure of the cells were revealed for both photobiont and mycobiont components after extreme temperature treatment of P. aphthosa thalli. The data show the extreme tolerance of P. aphthosa to some stress factors inherent to the space flight conditions.

  3. Influences of solution chemical conditions on mobilization of TNT from contaminated soil

    SciTech Connect

    Dante, D.A.; Tiller, C.L.; Pennell, K.D.

    1996-12-31

    2,4,6-trinitrotoluene (TNT) and its byproducts are common contaminants on US military installations. Many potential remediation processes are in part limited by the transfer of TNT from the contaminated soil into the aqueous phase. The purpose of this research is to assess the release of TNT from contaminated soil under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and addition of two surfactants is investigated. Uncontaminated soil was collected from a near-surface site at the Alabama Army Ammunition Plant and was artificially contaminated with TNT prior to the mobilization experiments. Results for the pH experiments show that more TNT is mobilized at neutral pH conditions than at low pH conditions. The presence of dissolved organic matter enhances the release of TNT from soil, but not by a large amount. Surfactant addition has the most significant effect on TNT mobilization.

  4. Recycling versus export of bioavailable dissolved organic matter in the coastal ocean and efficiency of the continental shelf pump

    NASA Astrophysics Data System (ADS)

    LøNborg, Christian; ÁLvarez-Salgado, Xosé Antón

    2012-09-01

    At least 15% of the 2 Pg y-1 of dissolved organic carbon (DOC) that accumulates in the surface layer of the open ocean has been exported from the ocean margins. The C: N: P stoichiometry of the production and microbial degradation of dissolved organic matter (DOM) in the coastal ocean conditions the quality of the exported substrates. In this work, DOC, dissolved organic nitrogen (DON) and phosphorus (DOP) bioavailability measurements from published bottle incubation experiments have been compiled and reanalyzed to examine the role of bioavailable DOM (BDOM) in the coastal ocean. DOM bioavailability decreased significantly (p< 0.001) in the sequence DOP > DON > DOC, with bioavailable DOC (BDOC) representing 22 ± 12% (mean ± SD) of the total DOC, bioavailable DON (BDON) 35 ± 13% of the total DON and bioavailable DOP (BDOP) 70 ± 18% of the total DOP. This suggests that the role of DOM on the recycled and export production of the coastal ocean is more relevant for the P than for the N and for the N than for the C biogeochemical cycles. First-order microbial degradation rate constants (κ) of BDOM (normalized to 15°C) increased significantly (p < 0.05) in the same sequence, with κC being 0.066 ± 0.065 day-1, κN 0.111 ± 0.096 and κP 0.154 ± 0.137 day-1. Significant (p < 0.001) power relationships were found among κC, κN and κP (R2 = 0.84-0.87). The C: N: P molar ratio of the DOM that resists microbial degradation was extremely depleted in N and P, 2835 (±3383): 159 (±187): 1, compared with the BDOM fraction, 197 (±111): 25 (±16): 1. The flushing time (τ) of the coastal ocean in relation to the turnover time of BDOM (1/κ), i.e., τ · κ, dictates the fate ―degradation versus accumulation― of the large scale export of BDOM, which could fuel parts of the oceanic new production and influence the N/P limitation of the open ocean.

  5. Influence of operating conditions on the optimum design of electric vehicle battery cooling plates

    NASA Astrophysics Data System (ADS)

    Jarrett, Anthony; Kim, Il Yong

    2014-01-01

    The efficiency of cooling plates for electric vehicle batteries can be improved by optimizing the geometry of internal fluid channels. In practical operation, a cooling plate is exposed to a range of operating conditions dictated by the battery, environment, and driving behaviour. To formulate an efficient cooling plate design process, the optimum design sensitivity with respect to each boundary condition is desired. This determines which operating conditions must be represented in the design process, and therefore the complexity of designing for multiple operating conditions. The objective of this study is to determine the influence of different operating conditions on the optimum cooling plate design. Three important performance measures were considered: temperature uniformity, mean temperature, and pressure drop. It was found that of these three, temperature uniformity was most sensitive to the operating conditions, especially with respect to the distribution of the input heat flux, and also to the coolant flow rate. An additional focus of the study was the distribution of heat generated by the battery cell: while it is easier to assume that heat is generated uniformly, by using an accurate distribution for design optimization, this study found that cooling plate performance could be significantly improved.

  6. Influence of incubation conditions on hydrolysis efficiency and iodine enrichment in baker's yeast.

    PubMed

    Dolińska, Barbara; Zieliński, Michał; Dobrzański, Zbigniew; Chojnacka, Katarzyna; Opaliński, Sebastian; Ryszka, Florian

    2012-06-01

    The influence of incubation conditions, enzyme type, hydrolysis time, and potassium iodide concentration on hydrolysis and iodine enrichment were studied in supernatant and pellets of Saccharomyces cervisiae hydrolysates. The type of enzyme used and incubation time significantly influence hydrolysis efficiency and protein concentration in supernatant and pellet. The highest protein hydrolysis efficiency was obtained by 24-h incubation with papain. Significantly lower values were observed for pepsin and autolysis. The potassium iodide concentration influences the iodine content of supernatant and pellet, but not hydrolysis. Iodide enrichment of supernatant and pellet depends on the concentration of iodide using during incubation. High concentration of iodide and long incubation times were the conditions for optimal iodide enrichment and high-protein hydrolysates. The optimal hydrolysis efficiency and iodine enrichment were obtained during 24-h incubation with papain in a 4.5-mM potassium iodide medium. The efficiency reached 98.22% with iodine concentrations of 2,664.91 and 9,200.67 μg/g iodine in pellet and supernatant, respectively.

  7. Individual condition and stream temperature influence early maturation of rainbow and steelhead trout, ncorhynchus mykiss

    USGS Publications Warehouse

    McMillan, John R.; Dunham, Jason B.; Reeves, Gordon H.; Mills, Justin S.; Jordan, Chris E.

    2012-01-01

    Alternative male phenotypes in salmonine fishes arise from individuals that mature as larger and older anadromous marine-migrants or as smaller and younger freshwater residents. To better understand the processes influencing the expression of these phenotypes we examined the influences of growth in length (fork length) and whole body lipid content in rainbow trout (Oncorhynchus mykiss). Fish were sampled from the John Day River basin in northeast Oregon where both anadromous ("steelhead") and freshwater resident rainbow trout coexist. Larger males with higher lipid levels had a greater probability of maturing as a resident at age-1+. Among males, 38% were maturing overall, and the odds ratios of the logistic model indicated that the probability of a male maturing early as a resident at age-1+ increased 49% (95% confidence interval (CI) = 23-81%) for every 5 mm increase in length and 33% (95% CI = 10-61%) for every 0.5% increase in whole body lipid content. There was an inverse association between individual condition and water temperature as growth was greater in warmer streams while whole body lipid content was higher in cooler streams. Our results support predictions from life history theory and further suggest that relationships between individual condition, maturation, and environmental variables (e.g., water temperature) are shaped by complex developmental and evolutionary influences.

  8. The influence of surface atmospheric conditions on the range and area reached by animal vocalizations.

    PubMed

    Larom, D; Garstang, M; Payne, K; Raspet, R; Lindeque, M

    1997-02-01

    Low-level vertical changes in temperature and wind exert powerful and predictable influences on the area ensonified by animal vocalizations. Computer modelling of low-frequency sound propagation in measured atmospheric conditions predicts that the calls of the savanna elephant at these frequencies can have ranges exceeding 10 km and that the calls will be highly directional in the presence of wind shear. Calling area is maximized under temperature inversions with low wind speeds. Calling area changes substantially over 24 h periods; on any given day, the calling area undergoes an expansion and contraction which may be as large as one order of magnitude. This cycle is modulated by topography, regional weather patterns, seasonality and possibly by climate variation. Similar influences affect the somewhat higher-frequency calls of lions and may be a selective pressure towards their crepuscular and nocturnal calling behaviour. Coyotes and wolves, which also live in areas with strong and prevalent nocturnal temperature inversions, show similar calling patterns, maximizing their chances of being heard over the longest possible distances. The pronounced dawn and evening vocalization peaks in other animals including birds, frogs and insects may reflect the same influences in combination with other factors which selectively limit high-frequency sound propagation. Atmospheric conditions therefore need to be taken into account in many field studies of animal behaviour. A simplified method for estimating sound propagation during field studies is presented.

  9. Zinc bioavailability in pork loin

    SciTech Connect

    Hortin, A.E.; Bechtel, P.J. Baker, D.H. )

    1991-03-15

    Pork loins were uniformly trimmed and divided into three groups: raw, roasted and braised. Following cooking, the loins were freeze dried and then ground to a fine granular consistency. Zinc levels of 51, 60 and 63 mg/kg dry matter (DM) were contained in the raw, roasted and braised products, respectively. The chick bioavailability (BV) assay employed a Zn-deficient soy isolate basal diet that was supplemented with 0, 5 or 10 mg Zn/kg from ZnSO{sub 4}{center dot}H{sub 2}O to produce a standard straight-line response in tibia Zn as a function of supplemental Zn intake. Experimental Zn sources were also added to the basal diet to provide 10 mg Zn/kg. Standard curve methodology indicated that Zn BV was unaffected by cooking. Roasted pork lion had a Zn BV of 184% relative to ZnSO{sub 4}{center dot}H{sub 2}O. Addition of 0.40% L-cysteine to the diet containing 10 mg Zn/kg from ZnSO{sub 4}{center dot}H{sub 2}O increased Zn BV to 175%. Results with histidine as a Zn-enhancing factor were variable. It is apparent that pork loin is an excellent source of bioavailable Zn, and SH-containing compounds such as cysteine and glutathione that are present in meat may contribute to enhanced gut absorption of meat-source Zn.

  10. On the Offshore Advection of Boundary-Layer Structures and the Influence on Offshore Wind Conditions

    NASA Astrophysics Data System (ADS)

    Dörenkämper, Martin; Optis, Michael; Monahan, Adam; Steinfeld, Gerald

    2015-06-01

    The coastal discontinuity imposes strong signals to the atmospheric conditions over the sea that are important for wind-energy potential. Here, we provide a comprehensive investigation of the influence of the land-sea transition on wind conditions in the Baltic Sea using data from an offshore meteorological tower, data from a wind farm, and mesoscale model simulations. Results show a strong induced stable stratification when warm inland air flows over a colder sea. This stratification demonstrates a strong diurnal pattern and is most pronounced in spring when the land-sea temperature difference is greatest. The strength of the induced stratification is proportional to this parameter and inversely proportional to fetch. Extended periods of stable stratification lead to increased influence of inertial oscillations and increased frequency of low-level jets. Furthermore, heterogeneity in land-surface roughness along the coastline is found to produce pronounced horizontal streaks of reduced wind speeds that under stable stratification are advected several tens of kilometres over the sea. The intensity and length of the streaks dampen as atmospheric stability decreases. Increasing sea surface roughness leads to a deformation of these streaks with increasing fetch. Slight changes in wind direction shift the path of these advective streaks, which when passing through an offshore wind farm are found to produce large fluctuations in wind power. Implications of these coastline effects on the accurate modelling and forecasting of offshore wind conditions, as well as damage risk to the turbine, are discussed.

  11. The influence of the sun, moon, climate and economic conditions on crisis incidence.

    PubMed

    Snoyman, P; Holdstock, T L

    1980-10-01

    Investigated the relationship between 2,344 cases of crisis incidence over a 1-year period (1976) and geophysical, climatic and seasonal conditions. Results revealed an intricate interactive effect between the variables of sex, nature of crisis, period of analysis, and environmental conditions. Males crisis became more likely, with downward economic trends or decreased solar activity. In contrast to female incidence of crisis, which peaked in spring, that of males peaked in autumn. Increased solar activity was related strongly to the incidence of crisis experienced by people who were retarded, abused drugs and were guilty of assault and/or rape. The waxing of the moon was related closely to cases of assault and/or rape, while retardates were influenced further by the moisture content in the air. Temporal considerations revealed a positive relationship between full moon and crisis incidence on alternate months only. Generally, the increased cloud cover, rainfall and temperature in summer, gave rise to more crisis consultations. Finally, geophysical, climatic and economic conditions also were seen to act in conjunction with each other to influence crisis incidence.

  12. Influence of the boundary conditions on the natural frequencies of a Francis turbine

    NASA Astrophysics Data System (ADS)

    Valentín, David; Ramos, David; Bossio, Matías; Presas, Alexandre; Egusquiza, Eduard; Valero, Carme

    2016-11-01

    Natural frequencies estimation of Francis turbines is of paramount importance in the stage of design in order to avoid vibration and resonance problems especially during transient events. Francis turbine runners are submerged in water and confined with small axial and radial gaps which considerably decrease their natural frequencies in comparison to the same structure in the air. Acoustic-structural FSI simulations have been used to evaluate the influence of these gaps. This model considers an entire prototype of a Francis turbine, including generator, shaft, runner and surrounding water. The radial gap between the runner and the static parts has been changed from the real configuration (about 0.04% the runner diameter) to 1% of the runner diameter to evaluate its influence on the machine natural frequencies. Mode-shapes and natural frequencies of the whole machine are discussed for all the boundary conditions tested.

  13. Genetic background influences nicotine-induced conditioned place preference and place aversion in mice.

    PubMed

    Ise, Yuya; Mori, Tomohisa; Katayama, Shirou; Suzuki, Tsutomu; Wang, Tzu-Chueh

    2014-01-01

    This study was designed to determine whether genetic differences influence the rewarding effects of nicotine in 4 inbred strains of mice (DBA/2, BALB/c, C3H, and C57BL/6). Nicotine (subcutaneous) induced a place preference in DBA/2 and BALB/c mice but a place aversion in C57BL/6 mice. A low dose of nicotine produced a significant place preference, whereas a high dose of nicotine produced place aversion in C3H mice. These effects were completely reversed by the nicotinic receptor antagonist mecamylamine. These results strongly suggest that a conditioned state, such as rewarding effects or aversive effects, can be influenced by genetic background.

  14. Influence of boundary conditions and confinement on nonlocal effects in flows of wormlike micellar systems.

    PubMed

    Masselon, Chloé; Colin, Annie; Olmsted, Peter D

    2010-02-01

    In this paper we report on the influence of different geometric and boundary constraints on nonlocal (spatially inhomogeneous) effects in wormlike micellar systems. In a previous paper, nonlocal effects were observable by measuring the local rheological flow curves of micelles flowing in a microchannel under different pressure drops, which appeared to differ from the flow curve measured using conventional rheometry. Here we show that both the confinement and the boundary conditions can influence those nonlocal effects. The role of the nature of the surface is analyzed in detail using a simple scalar model that incorporates inhomogeneities, which captures the flow behavior in both wide and confined geometries. This leads to an estimate for the nonlocal "diffusion" coefficient (i.e., the shear curvature viscosity) which corresponds to a characteristic length from 1 to 10 microm.

  15. Investigation of the solar influence on clean and dusty CO2-ice under Martian conditions

    NASA Astrophysics Data System (ADS)

    Kaufmann, E.; Hagermann, A.; Wolters, S.

    2015-10-01

    CO2 is the main component of the Martian atmosphere. Therefore the polar caps are - depending on hemisphere and season - partially or totally covered with CO2-ice. In contrast to rock and soil surface layers, which absorb and reflect incoming solar radiation immediately at the surface, ices are partially transparent in the visible spectral range, while they are opaque in the infrared. These properties are responsible for the so-called "Solid- State Greenhouse Effect" (SSGE). The SSGE may have a major influence on the sublimation and recondensation of CO2 and its circulation in the Martian atmosphere. Our work will concentrate on the influence of the SSGE on CO2-ice under Martian like conditions.

  16. Bioavailability and biodistribution of nanodelivered lutein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of the study was to evaluate the ability of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) to enhance lutein bioavailability. The bioavailability of free lutein and PLGA-NP lutein in rats was assessed by determining plasma pharmacokinetics and deposition in selected tissues. Lutein ...

  17. Marine lipid-based liposomes increase in vivo FA bioavailability.

    PubMed

    Cansell, Maud; Nacka, Fabienne; Combe, Nicole

    2003-05-01

    Liposomes made from an extract of natural marine lipids and containing a high n-3 PUFA lipid ratio were envisaged as oral route vectors for FA supplements in order to increase PUFA bioavailability. The absorption of FA in thoracic lymph duct-cannulated rats, after intragastric feeding of dietary fats in the form of liposomes or fish oil, was compared. Lipid and FA analyses were also performed on feces. Five mole percent alpha-tocopherol was added to fish oil and incorporated into the liposome membrane. The influence of alpha-tocopherol on FA lymph recovery was also investigated. In vivo, FA absorption in rats was favored by liposomes (98 +/- 1%) compared to fish oil (73 +/- 6%). In the same way, the DHA proportion in lymph was higher after liposome ingestion (78%) than after fish oil ingestion (47%). However, phospholipid (PL) concentration in lymph was not affected by the kind of dietary fat ingested, suggesting a PL regulation due to de novo TAG synthesis. The influence of the intramolecular distribution of n-3 PUFA in dietary lipids (TAG and PL) on the intramolecular FA distribution in TAG of chylomicrons was also investigated. The results obtained showed that the distribution of n-3 PUFA esterified on the sn-2 position of chylomicron TAG depended on the lipid source administered. All these results correlated, at least partly, with in vitro liposome behavior under conditions that mimic those of the gastrointestinal tract. As a whole, this study pointed out that marine PL may constitute an attractive material for the development of liposomes as oral PUFA supplements.

  18. Bioavailability and pharmacokinetic studies of eurycomanone from Eurycoma longifolia.

    PubMed

    Low, Bin-Seng; Ng, Bee-Hong; Choy, Wai-Peng; Yuen, Kah-Hay; Chan, Kit-Lam

    2005-09-01

    A validated HPLC analysis of eurycomanone (1), a bioactive quassinoid, in rat plasma following oral and intravenous administration of Eurycoma longifolia Jack extract was developed for pharmacokinetic and bioavailability studies. Relatively high plasma eurycomanone concentrations were detected after an intravenous injection of 10 mg/kg extract F2 containing 1.96 mg/kg of the quassinoid. However, it declined rapidly to zero after 8 h. Its mean elimination rate constant (k(e)), biological half-life (t(1/2)), volume of distribution (V(d)) and clearance (CL) were 0.88 +/- 0.19 h (-1), 1.00 +/- 0.26 h, 0.68 +/- 0.30 L/kg and 0.39 +/- 0.08 L/h/kg, respectively. Following oral administration of eurycomanone, its Cmax and Tmax values were detected as 0.33 +/- 0.03 microg/mL and 4.40 +/- 0.98 h, respectively. The plasma concentration of the quassinoid after oral administration was much lower than after intravenous application in spite of the oral dose being 5 times higher. The results indicate that eurycomanone is poorly bioavailable when given orally. A comparison of the AUC (0-->infinity) obtained orally to that obtained after an intravenous administration (normalized for dose differences) revealed that the absolute bioavailability of the compound was low with 10.5 %. Furthermore, the compound appeared to be well distributed in the extravascular fluids because of its relatively high V(d) value. The poor oral bioavailability was not attributed to instability problems because eurycomanone has been shown to be stable under different pH conditions. Thus, its poor oral bioavailability may be due to poor membrane permeability in view of its low P value and/or high first-pass metabolism.

  19. On the Influence of Boundary Conditions in Modeling Heat Transfer in Soil

    NASA Astrophysics Data System (ADS)

    Mikailsoy, F. D.

    2017-01-01

    A procedure to determine the thermal diffusivity of soils, which is based on the heat-transfer equation, has been developed. Experimental investigations were carried out to establish the influence of boundary conditions on the soil surface on the solution of inverse problems of modeling of heat transfer in soil. On the basis of these data, the author has calculated thermal diffusivity in soils with the proposed methods developed for the case with one and two harmonics and a comparison of these methods has been made; the calculated characteristics and experimental results have also been compared.

  20. [Conditions that influence bacterial luminescence in the presence of blood serum].

    PubMed

    Deriabin, D G; Poliakov, E G

    2005-01-01

    Conditions that influence the luminescence of natural and recombinant luminescent bacteria in the presence of blood serum were studied. In general, blood serum quenched the luminescence of the marine Photobacterium phosphoreum and the recombinant Escherichia coli strains harboring the luminescent system genes of Photobacterium leiognathi, but enhanced the luminescence of the soil bacterium Photorhabdus luminescens Zm1 and the recombinant E. coli strain harboring the lux operon of P. luminescens Zm1. The quenching effect of blood serum increased with its concentration and the time and temperature of incubation. The components of blood serum that determine the degree and specificity of its action on bacterial luminescence were identified.

  1. Interaction of hydrogen chloride with alumina. [influence of outgas and temperature conditions on adsorption

    NASA Technical Reports Server (NTRS)

    Bailey, R. R.; Wightman, J. P.

    1975-01-01

    The influence of outgas conditions and temperature on the adsorptive properties of two aluminas Alon-c and Al6sG were studied using adsorption isotherm measurements. Alon-C and Al6SG were characterized using X-ray powder diffraction, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and BET nitrogen surface areas. Some of these techniques were applied to two other aluminas but no isotherm data was obtained. Isotherm data and techniques applied to each alumina are summarized in tabular form.

  2. Influence of chemistry and hot rolling conditions on high permeability non-grain oriented silicon steel

    NASA Astrophysics Data System (ADS)

    Huňady, J.; Černík, M.; Hilinski, E. J.; Predmerský, M.; Magurová, A.

    2006-09-01

    This paper discusses the influence of chemical composition on the final electromagnetic properties in higher permeability material. Furthermore, the effect of the hot rolling practice and the end of austenite transformation temperature range on the hot band microstructure is described. The magnetic polarization J5000 better than 1.7 T, using hot rolling conditions 40 mm transfer bar thickness, finish mill entry temperature 1000 °C, and finishing temperature 800-840 °C and after decarburization heat treatment and grain growth treatment, was obtained.

  3. Accumulation and bioavailability of dietary carotenoids in vegetable crops.

    PubMed

    Kopsell, Dean A; Kopsell, David E

    2006-10-01

    Carotenoids are lipid-soluble pigments found in many vegetable crops that are reported to have the health benefits of cancer and eye disease reduction when consumed in the diet. Research shows that environmental and genetic factors can significantly influence carotenoid concentrations in vegetable crops, and that changing cultural management strategies could be advantageous, resulting in increased vegetable carotenoid concentrations. Improvements in vegetable carotenoid levels have been achieved using traditional breeding methods and molecular transformations to stimulate biosynthetic pathways. Postharvest and processing activities can alter carotenoid chemistry, and ultimately affect bioavailability. Bioavailability data emphasize the importance of carotenoid enhancement in vegetable crops and the need to characterize potential changes in carotenoid composition during cultivation, storage and processing before consumer purchase.

  4. Bioavailability of Glucosinolates and Their Breakdown Products: Impact of Processing

    PubMed Central

    Barba, Francisco J.; Nikmaram, Nooshin; Roohinejad, Shahin; Khelfa, Anissa; Zhu, Zhenzhou; Koubaa, Mohamed

    2016-01-01

    Glucosinolates are a large group of plant secondary metabolites with nutritional effects, and are mainly found in cruciferous plants. After ingestion, glucosinolates could be partially absorbed in their intact form through the gastrointestinal mucosa. However, the largest fraction is metabolized in the gut lumen. When cruciferous are consumed without processing, myrosinase enzyme present in these plants hydrolyzes the glucosinolates in the proximal part of the gastrointestinal tract to various metabolites, such as isothiocyanates, nitriles, oxazolidine-2-thiones, and indole-3-carbinols. When cruciferous are cooked before consumption, myrosinase is inactivated and glucosinolates transit to the colon where they are hydrolyzed by the intestinal microbiota. Numerous factors, such as storage time, temperature, and atmosphere packaging, along with inactivation processes of myrosinase are influencing the bioavailability of glucosinolates and their breakdown products. This review paper summarizes the assimilation, absorption, and elimination of these molecules, as well as the impact of processing on their bioavailability. PMID:27579302

  5. Overview on gastroretentive drug delivery systems for improving drug bioavailability.

    PubMed

    Lopes, Carla M; Bettencourt, Catarina; Rossi, Alessandra; Buttini, Francesca; Barata, Pedro

    2016-08-20

    In recent decades, many efforts have been made in order to improve drug bioavailability after oral administration. Gastroretentive drug delivery systems are a good example; they emerged to enhance the bioavailability and effectiveness of drugs with a narrow absorption window in the upper gastrointestinal tract and/or to promote local activity in the stomach and duodenum. Several strategies are used to increase the gastric residence time, namely bioadhesive or mucoadhesive systems, expandable systems, high-density systems, floating systems, superporous hydrogels and magnetic systems. The present review highlights some of the drugs that can benefit from gastroretentive strategies, such as the factors that influence gastric retention time and the mechanism of action of gastroretentive systems, as well as their classification into single and multiple unit systems.

  6. Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

    PubMed

    Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films.

  7. Conditions influencing the synthesis of acid protease by Mucor pusillus Lindt.

    PubMed

    Somkuti, G A; Babel, F J

    1967-11-01

    Protease synthesis by Mucor pusillus Lindt, in a wheat bran medium under submerged conditions, was influenced by substrate concentration, initial pH of the medium, and temperature of incubation. A 4% wheat bran (dry weight) concentration was satisfactory for enzyme production. The initial pH of the medium had a substantial effect on enzyme synthesis; adjustment of the enzyme production medium to pH 5.0 prior to sterilization was desirable. Incubation at 35 C resulted in the best enzyme yields. Under optimal conditions of enzyme production, maximal activity was detected after 5 days of incubation. The enrichment of the medium with glucose increased the yield of mycelia but lowered the amount of enzyme produced.

  8. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    NASA Astrophysics Data System (ADS)

    Escaler, X.; De La Torre, O.; Farhat, M.

    2015-12-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

  9. Influence of baking conditions on the quality attributes of sponge cake.

    PubMed

    Ureta, M Micaela; Olivera, Daniela F; Salvadori, Viviana O

    2017-03-01

    Sponge cake is a sweet bakery product characterized by its aerated and soft crumb and by its thin-coloured crust. The aim of this work is to analyse the influence of baking conditions (natural or forced convection, steam injection, oven temperature from 140 ℃ to 180 ℃) on sponge cake quality. Both crust and crumb regions were characterized by means of colour development, water content, crust/crumb relation, crust thickness and crumb structure (in terms of porosity, crumb density and texture). Colour measurements allowed obtaining an accurate model for browning kinetics. Crumb water content remains almost constant, while considerable dehydration occurs in the crust. In general, no significant differences due to baking conditions were found in the instrumental quality analysis.

  10. Environmental Conditions Influence Allometric Patterns in the Blow Fly, Chrysomya albiceps

    PubMed Central

    Horenstein, M Battán; Peretti, Av

    2011-01-01

    The objective of this research was to study variations in allometry of body characters in females and males of two populations of blow flies, Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), under different environmental conditions to establish patterns of morphological variation. Body size of both males and females in the experimental population was significantly higher than in the individuals of the natural population, indicating an important influence of food on body size. All genitalic and non-genitalic characters in males and females of the two populations showed a trend towards negative allometry rather than isometry. Allometric patterns were modified in both sexes and between populations. The data show generally larger allometric slopes in females than in males. We confirmed that the environmental conditions have an important effect on allometric patterns and body size. PMID:22224467

  11. Influence of emulsion composition and spray-drying conditions on microencapsulation of tilapia oil.

    PubMed

    Huang, Hui; Hao, Shuxian; Li, Laihao; Yang, Xianqing; Cen, Jianwei; Lin, Wanling; Wei, Ya

    2014-09-01

    The influence of processing conditions on the microencapsulation of tilapia oil by spray drying was studied. Trehalose, gelatin, sucrose and xanthan were used as emulsion composition. The experimental parameters of spray drying such as inlet air temperature, solid content, drying air flow rate and atomizing pressure were optimized using a central composite design. Encapsulation efficiency and lipid oxidation were determined. Bulk density, powder morphology and particle size were also analyzed. Trehalose improved the glass transition temperature of wall material significantly and prevented the oxidation of the fish oil. Encapsulation efficiency reached a maximum of 90 % under optimum conditions with an inlet air temperature of 121 °C, a drying air flow rate of 0.65 m(3)/min and a spray pressure of 100 kPa.

  12. Housing conditions influence motor functions and exploratory behavior following focal damage of the rat brain.

    PubMed

    Gornicka-Pawlak, Elzbieta; Jabłońska, Anna; Chyliński, Andrzej; Domańska-Janik, Krystyna

    2009-01-01

    The present study investigated influence of housing conditions on motor functions recovery and exploratory behavior following ouabain focal brain lesion in the rat. During 30 days post-surgery period rats were housed individually in standard cages (IS) or in groups in enriched environment (EE) and behaviorally tested. The EE lesioned rats showed enhanced recovery from motor impairments in walking beam task, comparing with IS animals. Contrarily, in the open field IS rats (both lesioned and control) traveled a longer distance, showed less habituation and spent less time resting at the home base than the EE animals. Unlike the EE lesioned animals, the lesioned IS rats, presented a tendency to hyperactivity in postinjury period. Turning tendency was significantly affected by unilateral brain lesion only in the EE rats. We can conclude that housing conditions distinctly affected the rat's behavior in classical laboratory tests.

  13. The Influence of Atmospheric Conditions on the Production of Ozone during VOC Oxidation

    NASA Astrophysics Data System (ADS)

    Coates, J.; Butler, T. M.

    2015-12-01

    Tropospheric ozone is a short-lived climate forcing pollutant that is detrimental to human health and crop growth. Reactions involving volatile organic compounds (VOC) and nitrogen oxides (NOx) in the presence of sunlight produce ozone. Ozone production is a non-linear function of the concentrations of both NOx and VOC, with VOC acting as the "fuel" for ozone production and NOx as the "catalyst". Different VOC, due to their differing structure and carbon content, have different maximum potential to produce ozone. Due to different degrees of reactivity, VOC also differ in the time taken to reach this maximum ozone production potential under ideal conditions. Ozone production is also influenced by meteorological factors such as radiation, temperature, advection and mixing, which may alter the rate of ozone production, and the degree to which VOC are able to reach their maximum ozone production potential. Identifying the chemical and meteorological processes responsible for controlling the degree to which VOC are able to reach their maximum ozone production potential could inform decisions on emission control to efficiently tackle high levels of tropospheric ozone. In this study we use a boxmodel to determine the chemical processes affecting ozone production under different meteorological and chemical conditions. The chemistry scheme used by the boxmodel is "tagged" for each initial VOC enabling attribution of ozone production to its VOC source. We systematically vary a number of meteorological parameters along with the source of NOx within the box model to simulate a range of atmospheric conditions. These simulations are compared with a control simulation done under conditions of maximum ozone formation to determine which parameters affect the rate at which VOC produce ozone and the extent to which they reach their maximum potential to produce ozone. We perform multi-day simulations in order to examine whether these processes can influence ozone production over

  14. Use of Tunable Whole-Cell Bioreporters to Assess Bioavailable Cadmium and Remediation Performance in Soils

    PubMed Central

    Yoon, Youngdae; Kim, Sunghoon; Chae, Yooeun; Kang, Yerin; Lee, Youngshim; Jeong, Seung-Woo; An, Youn-Joo

    2016-01-01

    It is important to have tools to measure the bioavailability to assess the risks of pollutants because the bioavailability is defined as the portions of pollutants showing the biological effects on living organisms. This study described the construction of tunable Escherichia coli whole-cell bioreporter (WCB) using the promoter region of zinc-inducible operon and its application on contaminated soils. It was verified that this WCB system showed specific and sensitive responses to cadmium rather than zinc in the experimental conditions. It was inferred that Cd(II) associates stronger with ZntR, a regulatory protein of zinc-inducible operon, than other metal ions. Moreover, the expression of reporter genes, egfp and mcherry, were proportional to the concentration of cadmium, thereby being a quantitative sensor to monitor bioavailable cadmium. The capability to determine bioavailable cadmium was verified with Cd(II) amended LUFA soils, and then the applicability on environmental systems was investigated with field soils collected from smelter area in Korea before and after soil-washing. The total amount of cadmium was decreased after soil washing, while the bioavailability was increased. Consequently, it would be valuable to have tools to assess bioavailability and the effectiveness of soil remediation should be evaluated in the aspect of bioavailability as well as removal efficiency. PMID:27171374

  15. Assessment of heavy metals bioavailability and toxicity toward Vibrio fischeri in sediment of the Huelva estuary.

    PubMed

    Rosado, Daniel; Usero, José; Morillo, José

    2016-06-01

    Relationship between toxicity and bioavailable metals in sediments from the Huelva estuary and its littoral of influence was analyzed. Toxicity was assessed with Microtox® bioassay using a marine luminescent bacterium: Vibrio fischeri. Bioavailable metals were considered as both, acid extractable fraction of BCR procedure and the sum of exchangeable and bound to carbonates fractions of Tessier sequential extraction. A bioavailable metals index was calculated to integrate results in a single figure. Toxicity and bioavailable metals showed a similar pattern. Higher levels were found in the estuary than in the littoral (140 TU/g). In Huelva estuary, highest levels were found in the Tinto estuary (5725 TU/g), followed by the Odiel estuary (5100 TU/g) and the Padre Santo Canal (2500 TU/g). Results in this area were well over than those in nearby estuaries. Furthermore, they are similar to or even higher than those in other polluted sediments around the world. Bioavailable metal index showed a stronger correlation with acid extractable fraction of BCR (R(2) = 0.704) than that for the sum of exchangeable and bound to carbonates fractions of Tessier (R(2) = 0.661). These results suggest that bioavailable metals are an important source of sediment toxicity in the Huelva estuary and its littoral of influence, an area with one of the highest mortality risks of Spain.

  16. Enhancing bioavailability through thermal processing.

    PubMed

    Keen, Justin M; McGinity, James W; Williams, Robert O

    2013-06-25

    Formulation intervention, through the application of processing technologies, is a requirement for enabling therapy for the vast majority of drugs. Without these enabling technologies, poorly soluble drugs may not achieve therapeutic concentrations in the blood or tissue of interest. Conversely, freely soluble and/or rapidly cleared drugs may require frequent dosing resulting in highly cyclic tissue concentrations. During the last several years, thermal processing techniques, such as melt mixing, spray congealing, sintering, and hot-melt extrusion, have evolved rapidly and several new technologies, specifically dry powder coating, injection molding, and KinetiSol(®) dispersing, have been adapted to the pharmaceutical arena. An examination of the contemporary literature is reported in this review to summarize the variety and utility of thermal processing technologies employed for solubility enhancement and controlled release. In particular, the impact of these processing technologies on bioavailability, considered in terms of both rate and extent, has been reviewed.

  17. Influence of storage conditions on the growth of Pseudomonas species in refrigerated raw milk.

    PubMed

    De Jonghe, Valerie; Coorevits, An; Van Hoorde, Koenraad; Messens, Winy; Van Landschoot, Anita; De Vos, Paul; Heyndrickx, Marc

    2011-01-01

    The refrigerated storage of raw milk throughout the dairy chain prior to heat treatment creates selective conditions for growth of psychrotolerant bacteria. These bacteria, mainly belonging to the genus Pseudomonas, are capable of producing thermoresistant extracellular proteases and lipases, which can cause spoilage and structural defects in pasteurized and ultra-high-temperature-treated milk (products). To map the influence of refrigerated storage on the growth of these pseudomonads, milk samples were taken after the first milking turn and incubated laboratory scale at temperatures simulating optimal and suboptimal preprocessing storage conditions. The outgrowth of Pseudomonas members was monitored over time by means of cultivation-independent denaturing gradient gel electrophoresis (DGGE). Isolates were identified by a polyphasic approach. These incubations revealed that outgrowth of Pseudomonas members occurred from the beginning of the dairy chain (farm tank) under both optimal and suboptimal storage conditions. An even greater risk for outgrowth, as indicated by a vast increase of about 2 log CFU per ml raw milk, existed downstream in the chain, especially when raw milk was stored under suboptimal conditions. This difference in Pseudomonas outgrowth between optimal and suboptimal storage was already statistically significant within the farm tank. The predominant taxa were identified as Pseudomonas gessardii, Pseudomonas gessardii-like, Pseudomonas fluorescens-like, Pseudomonas lundensis, Pseudomonas fragi, and Pseudomonas fragi-like. Those taxa show an important spoilage potential as determined on elective media for proteolysis and lipolysis.

  18. The blackberry fruit: a review on its composition and chemistry, metabolism and bioavailability, and health benefits.

    PubMed

    Kaume, Lydia; Howard, Luke R; Devareddy, Latha

    2012-06-13

    Blackberry (Rubus sp.) fruit contains high levels of anthocyanins and other phenolic compounds, mainly flavonols and ellagitannins, which contribute to its high antioxidant capacity and other biological activities. Blackberry phenolic composition and concentrations are known to be influenced by genetics, growing conditions, and maturation. Despite the current knowledge of their chemistry, research specific to blackberry phenolic compounds' health benefits, metabolism, bioavailability, and mechanism by which they confer health benefits is scarce. Blackberry phenolic compounds have protective effects on age-related neurodegenerative diseases and bone loss in vivo and can inhibit low-density lipoprotein and liposomal oxidation in vitro. Blackberry extracts have also exerted antimutagenic effects in vitro and in vivo by modifying cell signaling pathways and suppressing tumor promotion factors. However, the antiobesity, antidiabetic, antimicrobial, and anti-inflammatory properties of blackberry phenolic compounds need investigation. Similarly, studies that elucidate the in vivo physiologically effective concentrations of blackberry phenolic compounds are necessary.

  19. Effect of food and gastric pH on the bioavailability of grepafloxacin.

    PubMed

    Efthymiopoulos, C; Bramer, S L; Maroli, A

    1997-01-01

    Two open crossover studies were conducted to investigate the effects of food or concomitant treatment with the histamine H2-receptor antagonist famotidine on the pharmacokinetics of the new fluoroquinolone grepafloxacin. Each study involved 16 healthy male volunteers. In the first study, participants received grepafloxacin 600 mg, either after fasting or after consumption of a standard high-fat meal. There were no significant differences in any pharmacokinetic parameter under the fasting or nonfasting conditions. In the second study, participants received grepafloxacin 400 mg, either alone or after infusion of famotidine 20 mg; additional doses of famotidine were given, if necessary, to maintain intragastric pH above 6. Famotidine treatment had no significant effect on grepafloxacin pharmacokinetics. The results of these studies indicate that neither food nor the elevation of gastric pH influence the absorption or bioavailability of grepafloxacin. Therefore, grepafloxacin can be administered with or without food.

  20. Preirradiation grafting of acrylonitrile onto polypropylene monofilament for biomedical applications: I. Influence of synthesis conditions

    NASA Astrophysics Data System (ADS)

    Gupta, Bhuvanesh; Jain, Rachna; Anjum, Nishat; Singh, Harpal

    2006-01-01

    Graft polymerization of acrylonitrile onto polypropylene (PP) monofilament was carried out by a preirradiation method using a 60Co gamma radiation source. The influence of synthesis conditions, such as preirradiation dose, reaction time, monomer concentration, reaction temperature and additives was determined. The grafting was considerably influenced by the instantaneous swelling of the monofilament in the reaction mixture during the course of the grafting process. The order of dependence of the rate of grafting on monomer concentration was found to be 1.04. The nature of the medium of the grafting and the additives had profound influence over the grafting reaction. The accelerative effects of solvent medium on the grafting were higher in methylethyl ketone (MEK) and dimethylformamide (DMF) as compared to methanol. At the same time, partial replacement of DMF with water led to acceleration in the grafting with peak maxima at 20% solvent composition. The addition of a small amount of sulfuric acid to the reaction mixture also resulted in a significant acceleration of the degree of grafting.

  1. Influence of growth conditions on exchange bias of NiMn-based spin valves

    SciTech Connect

    Wienecke, Anja; Kruppe, Rahel; Rissing, Lutz

    2015-05-07

    As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with high exchange bias are thermally more stable than samples with low exchange bias. Those structures promoting a high exchange bias are seemingly the same suppressing thermally induced diffusion processes (A. Wienecke and L. Rissing, “Relationship between thermal stability and layer-stack/structure of NiMn-based GMR systems,” in IEEE Transaction on Magnetic Conference (EMSA 2014)). Many investigations were carried out on the influence of the sputtering parameters as well as the layer thickness on the magnetoresistive effect. The influence of these parameters on the exchange bias and the sample's thermal stability, respectively, was hardly taken into account. The investigation described here concentrates on the last named issue. The focus lies on the influence of the sputtering parameters and layer thickness of the “starting layers” in the stack and the layers forming the (synthetic) antiferromagnet. This paper includes a guideline for the evaluated sputtering conditions and layer thicknesses to realize a high exchange bias and presumably good thermal stability for NiMn-based spin valves with a synthetic antiferromagnet.

  2. Influences of surface hydrophilicity on frost formation on a vertical cold plate under natural convection conditions

    SciTech Connect

    Liu, Zhongliang; Zhang, Xinghua; Wang, Hongyan; Meng, Sheng; Cheng, Shuiyuan

    2007-07-15

    Surface hydrophilicity has a strong influence on frost nucleation according to phase transition theory. To study this effect, a close observation of frost formation and deposition processes on a vertical plate was made under free convection conditions. The formation and shape variation of frost crystals during the initial period are described and the frost thickness variation with time on both hydrophobic and plain copper cold surfaces are presented. The various influencing factors are discussed in depth. The mechanism of surface hydrophilicity influence on frost formation was analyzed theoretically. This revealed that increasing the contact angle can increase the potential barrier and restrain crystal nucleation and growth and thus frost deposition. The experimental results show that the initial water drops formed on a hydrophobic surface are smaller and remain in the liquid state for a longer time compared with ones formed on a plain copper surface. It is also observed that the frost layer deposited on a hydrophobic surface is loose and weak. Though the hydrophobic surface can retard frost formation to a certain extent and causes a looser frost layer, our experimental results show that it does not depress the growth of the frost layer. (author)

  3. The influence of weather conditions on the relative incident rate of fishing vessels.

    PubMed

    Wu, Yue; Pelot, Ronald P; Hilliard, Casey

    2009-07-01

    There is a long history of studying the relationship between weather and maritime activities. This article analyzes the link between relative incident rate (RIR) and general weather factors within certain gridded areas and time periods. The study area, which encompasses a broad extent of Atlantic Canadian waters, includes fishing incidents recorded by the Canadian Coast Guard from 1997 to 1999. Methodologies used for traffic track generation in a geographical information system and aggregation of all relevant weather data needed for the statistical analyses are presented. Ultimately, a regression tree was built to illustrate the relationship between incident rate and the following six weather factors: wave height; sea surface temperature; air temperature; ice concentration; fog presence; and precipitation. Results from the regression tree reveal that the RIR defined as (incident number per area-day)/(traffic amount per area-day) across grid cells with incidents, increases as the weather conditions deteriorate in a general way, and the concentration of ice has the biggest influence on the magnitude of incident rates for a given level of traffic exposure. The results from this analysis may assist administrators of maritime traffic, especially those associated with fishing activities, through a better understanding of the influence on RIR of certain weather conditions within given areas in specific time periods.

  4. Influence of beaver activity on summer growth and condition of age-2 Atlantic salmon parr

    USGS Publications Warehouse

    Sigourney, D.B.; Letcher, B.H.; Cunjak, R.A.

    2006-01-01

    The activity of beavers Castor canadensis in freshwater environments can have considerable localized impacts on the physical and biological components of riparian ecosystems. By changing the habitat of a stream, beaver dams can cause spatial variation in growth opportunity that may have direct consequences for the growth of resident fish. In a small stream in eastern Canada, we studied the effects of an ephemeral beaver pond on the growth and maturity of age-2 Atlantic salmon Salmo salar parr tagged with passive integrated transponder tags. Water temperature remained relatively uniform throughout the study site. We found very little movement of recaptured fish in the study site. Fish that were recaptured in the beaver pond displayed faster summer growth rates in both length and mass than fish that were recaptured immediately above or below the pond. We also found that parr in the pond maintained relatively high condition factors, whereas fish above and below the pond appeared to decrease in condition factor throughout the summer. In addition to growth, the maturation rates of age-2 males were higher above the dam than below. This study demonstrates the effect a beaver dam can have on individual growth rates. By influencing growth during sensitive periods, the beaver pond may also influence individual life history pathways. This information could be an important component in ecosystem models that predict the effect of beaver population dynamics on the growth of individual salmonids at the landscape scale. ?? Copyright by the American Fisheries Society 2006.

  5. The Influence of the Biological Pump on Marine Redox Conditions During Earth History

    NASA Astrophysics Data System (ADS)

    Meyer, K. M.; Ridgwell, A.; Payne, J.

    2015-12-01

    Evidence for bottom-water anoxia on the continental shelves waned over the course of the Phanerozoic, which may be influenced by secular changes in the biological pump that led to weaker positive feedbacks within the oceans. The biological pump describes the transfer of carbon from the atmosphere to the deep ocean, which creates vertical gradients in nutrients and oxygen, both important influences in the structure of marine ecosystems. We used the cGENIE Earth system model to quantitatively test the hypothesis that reductions in the efficiency of the nutrient recycling loop of the biological pump during the past 550 Ma reduced the extent of anoxia on the shelves and acted as an important control on marine animal ecosystems. When the modeled remineralization depth is shallow relative to the modern ocean, anoxia tends to be more widespread at continental shelf depths. As the modeled remineralization depth increases toward modern conditions, anoxia is less prevalent and occurs at depths below the continental shelves. Reduced marine productivity in the closed system configuration of cGENIE cannot produce the frequent bottom-water anoxia conditions envisioned for the Paleozoic. We hypothesize that evidence for greater animal abundance and metabolic demand during the Phanerozoic was driven by progressive oxygenation of shelf environments related to changes in the biological pump rather than greater food availability. In general, these model simulations suggest changes in the depth distribution of organic carbon remineralization may have controlled observed shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure during the Phanerozoic.

  6. Conditional symbolic analysis detects nonlinear influences of respiration on cardiovascular control in humans

    PubMed Central

    Porta, Alberto; Marchi, Andrea; Bari, Vlasta; Heusser, Karsten; Tank, Jens; Jordan, Jens; Barbic, Franca; Furlan, Raffaello

    2015-01-01

    We propose a symbolic analysis framework for the quantitative characterization of complex dynamical systems. It allows the description of the time course of a single variable, the assessment of joint interactions and an analysis triggered by a conditioning input. The framework was applied to spontaneous variability of heart period (HP), systolic arterial pressure (SAP) and integrated muscle sympathetic nerve activity (MSNA) with the aim of characterizing cardiovascular control and nonlinear influences of respiration at rest in supine position, during orthostatic challenge induced by 80° head-up tilt (TILT) and about 3 min before evoked pre-syncope signs (PRESY). The approach detected (i) the exaggerated sympathetic modulation and vagal withdrawal from HP variability and the increased presence of fast MSNA variability components during PRESY compared with TILT; (ii) the increase of the SAP–HP coordination occurring at slow temporal scales and a decrease of that occurring at faster time scales during PRESY compared with TILT; (iii) the reduction of the coordination between fast MSNA and SAP patterns during TILT and PRESY; (iv) the nonlinear influences of respiration leading to an increased likelihood to observe the abovementioned findings during expiration compared with inspiration one. The framework provided simple, quantitative indexes able to distinguish experimental conditions characterized by different states of the autonomic nervous system and to detect the early signs of a life threatening situation such as postural syncope. PMID:25548269

  7. Rearing conditions influence nutrient availability of plant extracts supplemented diets when fed to broiler chickens.

    PubMed

    Pirgozliev, V; Bravo, D; Rose, S P

    2014-08-01

    The effects of a standardised mixture of essential oils, including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum (XT 6930; Pancosma S.A), on dietary apparent metabolisable energy corrected for nitrogen retention (AMEn), nutrient digestibility and mucin secretions, measured as sialic acid (SA) were investigated in broilers fed on the same diet but reared under different conditions, that is, cages and floor pens littered with wood shavings used in previous broiler study. The use of XT reduced (p < 0.05) nitrogen digestibility (0.585 vs. 0.544) and tended (p = 0.072) to reduce dry matter digestibility (0.733 vs. 0.717) of the diet when fed to birds reared in cages. However, XT supplementation improved (p < 0.05) fat digestibility (0.844 vs. 0.862) and tended (p = 0.093) to increase AMEn (14.01 vs. 14.25 MJ/kg DM) of the same diet when fed to broilers reared in floor pens. Essential oils supplementation tended (p = 0.059) to increase the secretion of SA, when fed to birds reared in cages (11.24 vs. 14.18 μg), but did not influence (p > 0.05) the SA secretion from birds reared in floor pens. The results obtained from the cage study tend to be the opposite of those obtained from the floor pen study. This suggests that the efficiency of dietary plant extracts may be influenced by the rearing/hygienic conditions of poultry. Based on the overall results, it can be concluded that information on rearing conditions should be taken into account for more complete interpretation of the experimental data emanating from experiments involving use of essential oils typified by those considered in this study.

  8. Production of antibacterial compounds and biofilm formation by Roseobacter species are influenced by culture conditions.

    PubMed

    Bruhn, Jesper Bartholin; Gram, Lone; Belas, Robert

    2007-01-01

    Bacterial communities associated with marine algae are often dominated by members of the Roseobacter clade, and in the present study, we describe Roseobacter phenotypes that may provide this group of bacteria with selective advantages when colonizing this niche. Nine of 14 members of the Roseobacter clade, of which half were isolated from cultures of the dinoflagellate Pfiesteria piscicida, produced antibacterial compounds. Many non-Roseobacter marine bacteria were inhibited by sterile filtered supernatants of Silicibacter sp. TM1040 and Phaeobacter (formerly Roseobacter) strain 27-4, which had the highest production of antibacterial compound. In contrast, Roseobacter strains were susceptible only when exposed to concentrated compound. The production of antibacterial compound was influenced by the growth conditions, as production was most pronounced when bacteria were grown in liquid medium under static conditions. Under these conditions, Silicibacter sp. TM1040 cells attached to one another, forming rosettes, as has previously been reported for Phaeobacter 27-4. A spontaneous Phaeobacter 27-4 mutant unable to form rosettes was also defective in biofilm formation and the production of antibacterial compound, indicating a possible link between these phenotypes. Rosette formation was observed in 8 of 14 Roseobacter clade strains examined and was very pronounced under static growth in 5 of these strains. Attachment to surfaces and biofilm formation at the air-liquid interface by these five strains was greatly facilitated by growth conditions that favored rosette formation, and rosette-forming strains were 13 to 30 times more efficient in attaching to glass compared to strains under conditions where rosette formation was not pronounced. We hypothesize that the ability to produce antibacterial compounds that principally inhibit non-Roseobacter species, combined with an enhancement in biofilm formation, may give members of the Roseobacter clade a selective advantage and

  9. Influence of iron precipitated condition and light intensity on microalgae activated sludge based wastewater remediation.

    PubMed

    Anbalagan, Anbarasan; Schwede, Sebastian; Lindberg, Carl-Fredrik; Nehrenheim, Emma

    2017-02-01

    The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3-4 mg L(-1) were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L(-1)) at higher surface photosynthetic active radiation (250 and 500 μmol m(-2) s(-1)). Additionally, the rate approached a saturation phase at low MAAS (110 mg L(-1)) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L(-1). The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L(-1). The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92-106 m h(-1) and sludge volume index of 31-43 ml g(-1) in the studied cases.

  10. Carryover effects and climatic conditions influence the postfledging survival of greater sage-grouse

    PubMed Central

    Blomberg, Erik J; Sedinger, James S; Gibson, Daniel; Coates, Peter S; Casazza, Michael L

    2014-01-01

    Prebreeding survival is an important life history component that affects both parental fitness and population persistence. In birds, prebreeding can be separated into pre- and postfledging periods; carryover effects from the prefledging period may influence postfledging survival. We investigated effects of body condition at fledging, and climatic variation, on postfledging survival of radio-marked greater sage-grouse (Centrocercus urophasianus) in the Great Basin Desert of the western United States. We hypothesized that body condition would influence postfledging survival as a carryover effect from the prefledging period, and we predicted that climatic variation may mediate this carryover effect or, alternatively, would act directly on survival during the postfledging period. Individual body condition had a strong positive effect on postfledging survival of juvenile females, suggesting carryover effects from the prefledging period. Females in the upper 25th percentile of body condition scores had a postfledging survival probability more than twice that (Φ = 0.51 ± 0.06 SE) of females in the bottom 25th percentile (Φ = 0.21 ± 0.05 SE). A similar effect could not be detected for males. We also found evidence for temperature and precipitation effects on monthly survival rates of both sexes. After controlling for site-level variation, postfledging survival was nearly twice as great following the coolest and wettest growing season (Φ = 0.77 ± 0.05 SE) compared with the hottest and driest growing season (Φ = 0.39 ± 0.05 SE). We found no relationships between individual body condition and temperature or precipitation, suggesting that carryover effects operated independently of background climatic variation. The temperature and precipitation effects we observed likely produced a direct effect on mortality risk during the postfledging period. Conservation actions that focus on improving prefledging habitat for sage-grouse may have indirect benefits

  11. Carryover effects and climatic conditions influence the postfledging survival of greater sage-grouse

    USGS Publications Warehouse

    Blomberg, Erik J.; Sedinger, James S.; Gibson, Daniel; Coates, Peter S.; Casazza, Michael L.

    2014-01-01

    Prebreeding survival is an important life history component that affects both parental fitness and population persistence. In birds, prebreeding can be separated into pre- and postfledging periods; carryover effects from the prefledging period may influence postfledging survival. We investigated effects of body condition at fledging, and climatic variation, on postfledging survival of radio-marked greater sage-grouse (Centrocercus urophasianus) in the Great Basin Desert of the western United States. We hypothesized that body condition would influence postfledging survival as a carryover effect from the prefledging period, and we predicted that climatic variation may mediate this carryover effect or, alternatively, would act directly on survival during the postfledging period. Individual body condition had a strong positive effect on postfledging survival of juvenile females, suggesting carryover effects from the prefledging period. Females in the upper 25th percentile of body condition scores had a postfledging survival probability more than twice that (Φ = 0.51 ± 0.06 SE) of females in the bottom 25th percentile (Φ = 0.21 ± 0.05 SE). A similar effect could not be detected for males. We also found evidence for temperature and precipitation effects on monthly survival rates of both sexes. After controlling for site-level variation, postfledging survival was nearly twice as great following the coolest and wettest growing season (Φ = 0.77 ± 0.05 SE) compared with the hottest and driest growing season (Φ = 0.39 ± 0.05 SE). We found no relationships between individual body condition and temperature or precipitation, suggesting that carryover effects operated independently of background climatic variation. The temperature and precipitation effects we observed likely produced a direct effect on mortality risk during the postfledging period. Conservation actions that focus on improving prefledging habitat for sage-grouse may have indirect benefits

  12. Carryover effects and climatic conditions influence the postfledging survival of greater sage-grouse.

    PubMed

    Blomberg, Erik J; Sedinger, James S; Gibson, Daniel; Coates, Peter S; Casazza, Michael L

    2014-12-01

    Prebreeding survival is an important life history component that affects both parental fitness and population persistence. In birds, prebreeding can be separated into pre- and postfledging periods; carryover effects from the prefledging period may influence postfledging survival. We investigated effects of body condition at fledging, and climatic variation, on postfledging survival of radio-marked greater sage-grouse (Centrocercus urophasianus) in the Great Basin Desert of the western United States. We hypothesized that body condition would influence postfledging survival as a carryover effect from the prefledging period, and we predicted that climatic variation may mediate this carryover effect or, alternatively, would act directly on survival during the postfledging period. Individual body condition had a strong positive effect on postfledging survival of juvenile females, suggesting carryover effects from the prefledging period. Females in the upper 25th percentile of body condition scores had a postfledging survival probability more than twice that (Φ = 0.51 ± 0.06 SE) of females in the bottom 25th percentile (Φ = 0.21 ± 0.05 SE). A similar effect could not be detected for males. We also found evidence for temperature and precipitation effects on monthly survival rates of both sexes. After controlling for site-level variation, postfledging survival was nearly twice as great following the coolest and wettest growing season (Φ = 0.77 ± 0.05 SE) compared with the hottest and driest growing season (Φ = 0.39 ± 0.05 SE). We found no relationships between individual body condition and temperature or precipitation, suggesting that carryover effects operated independently of background climatic variation. The temperature and precipitation effects we observed likely produced a direct effect on mortality risk during the postfledging period. Conservation actions that focus on improving prefledging habitat for sage-grouse may have indirect benefits

  13. Statistical approach for assessing the influence of synoptic and meteorological conditions on ozone concentrations over Europe

    NASA Astrophysics Data System (ADS)

    Otero, Noelia; Butler, Tim; Sillmann, Jana

    2015-04-01

    Air pollution has become a serious problem in many industrialized and densely-populated urban areas due to its negative effects on human health, damages agricultural crops and ecosystems. The concentration of air pollutants is the result of several factors, including emission sources, lifetime and spatial distribution of the pollutants, atmospheric properties and interactions, wind speed and direction, and topographic features. Episodes of air pollution are often associated with stationary or slowly migrating anticyclonic (high-pressure) systems that reduce advection, diffusion, and deposition of atmospheric pollutants. Certain weather conditions facilitate the concentration of pollutants, such as the incidence of light winds that contributes to the increasing of stagnation episodes affecting air quality. Therefore, the atmospheric circulation plays an important role in air quality conditions that are affected by both, synoptic and local scale processes. This study assesses the influence of the large-scale circulation along with meteorological conditions on tropospheric ozone in Europe. The frequency of weather types (WTs) is examined under a novel approach, which is based on an automated version of the Lamb Weather Types catalog (Jenkinson and Collison, 1977). Here, we present an implementation of such classification point-by-point over the European domain. Moreover, the analysis uses a new grid-averaged climatology (1°x1°) of daily surface ozone concentrations from observations of individual sites that matches the resolution of global models (Schnell,et al., 2014). Daily frequency of WTs and meteorological conditions are combined in a multiple regression approach for investigating the influence on ozone concentrations. Different subsets of predictors are examined within multiple linear regression models (MLRs) for each grid cell in order to identify the best regression model. Several statistical metrics are applied for estimating the robustness of the

  14. The influence of variations in biophysical conditions on hemolysis near ultrasonically activated gas-filled micropores

    SciTech Connect

    Miller, D.L.; Thomas, R.M. )

    1990-05-01

    Hemolysis induced by 1.9-MHz ultrasound in 0.5% suspensions of canine erythrocytes with 3.7-{mu}m-diam micropore-trapped gas bodies was investigated for a variety of biophysical conditions. For isotonic media, hemolysis increased with exposure duration but did not greatly change with exposure temperature, or prior heat treatment. The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the ultrasonically activated gas bodies. Variations in osmolarity had little influence on the results. Increasing the viscosity of the medium decreased the effect, and this did not seem to depend on the molecular weight of the dextran additive. A medium with elevated mass density seemed to increase the effectiveness of the exposures. This condition eliminated the density difference between the cells and the medium, and might have been expected to reduce the effectiveness of the exposures, because the radiation force, which theoretically gathers cells to the gas bodies, is minimized for such conditions. This information should aid in developing refinements to the theoretical understanding of low-intensity ultrasonic bioeffects.

  15. Influence of temperature and relative humidity conditions on the pan coating of hydroxypropyl cellulose molded capsules.

    PubMed

    Macchi, Elena; Zema, Lucia; Pandey, Preetanshu; Gazzaniga, Andrea; Felton, Linda A

    2016-03-01

    In a previous study, hydroxypropyl cellulose (HPC)-based capsular shells prepared by injection molding and intended for pulsatile release were successfully coated with 10mg/cm(2) Eudragit® L film. The suitability of HPC capsules for the development of a colon delivery platform based on a time dependent approach was demonstrated. In the present work, data logging devices (PyroButton®) were used to monitor the microenvironmental conditions, i.e. temperature (T) and relative humidity (RH), during coating processes performed under different spray rates (1.2, 2.5 and 5.5g/min). As HPC-based capsules present special features, a preliminary study was conducted on commercially available gelatin capsules for comparison purposes. By means of PyroButton data-loggers it was possible to acquire information about the impact of the effective T and RH conditions experienced by HPC substrates during the process on the technological properties and release performance of the coated systems. The use of increasing spray rates seemed to promote a tendency of the HPC shells to slightly swell at the beginning of the spraying process; moreover, capsules coated under spray rates of 1.2 and 2.5g/min showed the desired release performance, i.e. ability to withstand the acidic media followed by the pulsatile release expected for uncoated capsules. Preliminary stability studies seemed to show that coating conditions might also influence the release performance of the system upon storage.

  16. Influence of housing conditions for mice on the results of a dermal oncogenicity bioassay.

    PubMed

    DePass, L R; Weil, C S; Ballantyne, B; Lewis, S C; Losco, P E; Reid, J B; Simon, G S

    1986-11-01

    Male C3H/HeJ mice were thrice weekly given 25 microliter applications of 0.25, 0.05, or 0.01% (w/w) benzo(a)pyrene (BaP) in acetone, or acetone alone, to clipped dorsal skin from 12 to 14 weeks of age for the remainder of their life spans. There were two groups of 40 mice for each treatment regimen, one group being housed in conventional stainless-steel wire mesh cages and the other in polycarbonate cages with wood shavings held in an enclosed ventilated cabinet. Under both housing conditions, tumor incidence was directly related and latency inversely related to BaP concentration. The time-adjusted incidence of epidermal neoplasms was significantly greater for the groups housed in polycarbonate cages. Mortality rates were directly related to BaP concentration and were significantly enhanced by the polycarbonate-cage housing conditions for the high and intermediate concentrations. Survival patterns for the two acetone control groups were similar. These findings indicate that differences in housing conditions can influence both the incidence and the latency of local neoplasms produced in response to the chronic application of a carcinogen in dermal oncogenesis bioassays.

  17. Influence of orthodontic derotation and extrusion on pulpal and periodontal condition of autotransplanted immature third molars.

    PubMed

    Bauss, Oskar; Schwestka-Polly, Rainer; Kiliaridis, Stavros

    2004-04-01

    The aim of this study was to determine the influence of orthodontic treatment on the pulpal and periodontal condition of 91 transplanted immature third molars. In patients with atrophy of the alveolar process or unfavorable root morphology, transplants had to be placed in extreme rotated or infraoccluded positions. After 3 to 6 months, these transplants were derotated (45 degrees to 90 degrees) to a correct position in the dental arch (derotation group; n = 28) or extruded to the occlusal plane (extrusion group; n = 21). Finally, approximal spaces were closed in both groups. A sample of 42 transplanted third molars with no orthodontic treatment need served as the control group. All transplants were followed clinically and radiologically for a mean period of 4.0 years. With respect to pulpal and periodontal conditions, no significant differences were observed between the control and the extrusion group. In contrast, compared with the control group, transplants in the derotation group had a significantly poorer pulpal and periodontal condition. In the derotated transplants, a significant correlation was detected between pulp necrosis and orthodontic treatment of multi-rooted transplants. This study indicates that orthodontic extrusion and minor lateral movements of autotransplanted immature third molars, as well as rotation of single-rooted third-molar transplants, represent no additional risk to transplant survival. In contrast, rotation of multi-rooted transplants seems to initiate later severance of the vascular and nerval supply to the pulp.

  18. Rain influences the physiological and metabolic responses to exercise in hot conditions.

    PubMed

    Ito, Ryo; Yamashita, Naoyuki; Suzuki, Eiko; Matsumoto, Takaaki

    2015-01-01

    Outdoor exercise often proceeds in rainy conditions. However, the cooling effects of rain on human physiological responses have not been systematically studied in hot conditions. The present study determined physiological and metabolic responses using a climatic chamber that can precisely simulate hot, rainy conditions. Eleven healthy men ran on a treadmill at an intensity of 70% VO2max for 30 min in the climatic chamber at an ambient temperature of 33°C in the presence (RAIN) or absence (CON) of 30 mm · h(-1) of precipitation and a headwind equal to the running velocity of 3.15 ± 0.19 m · s(-1). Oesophageal temperature, mean skin temperature, heart rate, rating of perceived exertion, blood parameters, volume of expired air and sweat loss were measured. Oesophageal and mean skin temperatures were significantly lower from 5 to 30 min, and heart rate was significantly lower from 20 to 30 min in RAIN than in CON (P < 0.05 for all). Plasma lactate and epinephrine concentrations (30 min) and sweat loss were significantly lower (P < 0.05) in RAIN compared with CON. Rain appears to influence physiological and metabolic responses to exercise in heat such that heat-induced strain might be reduced.

  19. Environmental Influences on the Release of Ophiosphaerella agrostis Ascospores Under Controlled and Field Conditions.

    PubMed

    Kaminski, John E; Dernoeden, Peter H; O'Neill, Nichole R

    2005-11-01

    ABSTRACT Ophiosphaerella agrostis, the causal agent of dead spot of creeping bentgrass (Agrostis stolonifera), can produce prodigious numbers of pseudothecia and ascospores throughout the summer. The environmental conditions and seasonal timings associated with O. agrostis ascospore release are unknown. The objectives of this research were to (i) determine the influence of light and relative humidity on ascospore release in a controlled environment, (ii) document the seasonal and daily discharge patterns of ascospores in the field, and (iii) elucidate environmental conditions that promote ascospore release under field conditions. In a growth chamber, a sharp decrease (100 to approximately 50%; 25 degrees C) in relative humidity resulted in a rapid (1- to 3-h) discharge of ascospores, regardless of whether pseudothecia were incubated in constant light or dark. In the field, daily ascospore release increased between 1900 and 2300 h and again between 0700 and 1000 h local time. The release of ascospores occurred primarily during the early morning hours when relative humidity was decreasing and the canopy began to dry, or during evening hours when relative humidity was low and dew began to form. Few ascospores were released between 1100 and 1800 h when the bentgrass canopy was dry. The release of ascospores also was triggered by precipitation. Of the ascospores collected during precipitation events, 87% occurred within 10 h of the beginning of each event.

  20. Bioavailability of mercury in East Fork Poplar Creek soils

    SciTech Connect

    Barnett, M.O.; Turner, R.R.

    1995-05-01

    The initial risk assessment for the East Fork Poplar Creek (EFPC) floodplain in Oak Ridge, Tennessee, a superfund site heavily contaminated with mercury, was based upon a reference dose for mercuric chloride, a soluble mercury compound not expected to be present in the floodplain, which is frequently saturated with water. Previous investigations had suggested mercury in the EFPC floodplain was less soluble and therefore less bioavailable than mercuric chloride, possibly making the results of the risk assessment unduly conservative. A bioavailability study, designed to measure the amount of mercury available for absorption in a child`s digestive tract, the most critical risk endpoint and pathway, was performed on twenty soils from the EFPC floodplain. The average percentage of mercury released during the study for the twenty soils was 5.3%, compared to 100% of the compound mercuric chloride subjected to the same conditions. Alteration of the procedure to test additional conditions possible during soil digestion did not appreciably alter the results. Therefore, use of a reference dose for mercuric chloride in the EFPC risk assessment without inclusion of a corresponding bioavailability factor may be unduly conservative.

  1. How Socio-Economic Conditions Influence Forest Policy Development in Central and South-East Europe

    NASA Astrophysics Data System (ADS)

    Vuletić, Dijana; Potočić, Nenad; Krajter, Silvija; Seletković, Ivan; Fürst, Christine; Makeschin, Franz; Galić, Zoran; Lorz, Carsten; Matijašič, Dragan; Zupanič, Matjaž; Simončič, Primož; Vacik, Harald

    2010-12-01

    In this article, several findings on socio-economic conditions derived from national reports and a web-based questionnaire are discussed and related to the changing role of forestry and the future forest policy development. A number of Central and South-eastern European countries taking part in a SEE-ERA-NET project ReForMan project ( www.reforman.de ) participated in data acquisition: Austria, Bosnia and Herzegovina, Croatia, Germany, Serbia and Slovenia. The aim of the research was to illustrate the present structure of forestry sector, as well as investigate newly emerging topics in forestry of Central and South-eastern Europe. The results indicated certain patterns in attitudes and perceptions among stakeholders that can be related to socio-economic conditions defined for each country. Clear differences between member and non-member countries exist only in level of implementation of EU legislation. Results showed consensus on main threats to the forests among all countries, but also some country specifics in perceptions of factors influencing forestry, their importance and professional competencies. These results could be additionally explained by influence of historical conditions which shaped development of forest sector in SEE region especially in its organizational dimension as well as in perceived role of forestry expressed through recognition of main forest functions. The influence of European forest policy processes in the region is evident through adaptation of EU legislation and perceived implications of international processes on national levels. Based on this observation, two possible options for future development of the forestry sector can be foreseen: (i) focusing on the productive function of forests and fostering its' sustainable use; or (ii) putting an emphasis on environmental and social issues. In both cases supporting public

  2. [Examination of physical and psychological health conditions and the influence factors of home helpers].

    PubMed

    Ashitomi, Ikuya

    2005-12-01

    The primary aim of this study was to examine the physical and psychological health conditions and the influence factors of home helpers. The secondary aim was to suggest a stress management system for home helpers. Self-report questionnaires were distributed to 1147 home helpers who were with home health care agencies in Kitakyushu-city. Responses from 979 home helpers were received, yielding a response rate of 85.5%. A total of 967 home helpers (excluding 12 male home helpers) were used for analysis. The Japanese version of the General Health Questionnaire 28 (GHQ-28) was used to measure the physical and psychological health conditions of the home helpers. In addition, as an influence factor, stress coping was measured by the Lazarus-type Stress Coping Inventory (SCI). Home helpers also filled out the Ego Aptitude Scale (EAS) as a personality measure. Furthermore, the subjects were asked questions about individual background factors, including age, marital status, working hours, years working as a home helper, type of home helper, job satisfaction, job continuation and awareness of stress. The data were analyzed using the Statistical Package for the Social Sciences (SPSS 11.5 J). The groups of full-time or part-time home helpers showed GHQ-28 total scores of 6.86 +/- 5.48 and 5.21 +/- 4.97 (Mean +/- SD): part-time home helpers had significantly higher scores than full-time home helpers. The GHQ-28 measure indicated that about 20% of home helpers had physical and psychological symptoms, and about 4% had mid-level depressive symptoms. About half of the subjects were aware of stress. There were significant negative correlations between GHQ-28 total scores and age. Also, there was a statistically significant relation between GHQ-28 and job satisfaction, awareness of stress, type of stress coping and individual personality. Furthermore, there was a statistically significant relation between GHQ-28 and the confrontive coping type, positive reappraisal of SCI, and

  3. Strategies to Overcome Heparins’ Low Oral Bioavailability

    PubMed Central

    Neves, Ana Rita; Correia-da-Silva, Marta; Sousa, Emília; Pinto, Madalena

    2016-01-01

    Even after a century, heparin is still the most effective anticoagulant available with few side effects. The poor oral absorption of heparins triggered the search for strategies to achieve oral bioavailability since this route has evident advantages over parenteral administration. Several approaches emerged, such as conjugation of heparins with bile acids and lipids, formulation with penetration enhancers, and encapsulation of heparins in micro and nanoparticles. Some of these strategies appear to have potential as good delivery systems to overcome heparin’s low oral bioavailability. Nevertheless, none have reached the market yet. Overall, this review aims to provide insights regarding the oral bioavailability of heparin. PMID:27367704

  4. Calcium bioavailability and its relation to osteoporosis.

    PubMed

    Weaver, C M

    1992-06-01

    The balance of data suggests that calcium intake has a positive influence on bone mass in premenopausal women and has a preventive effect on the rate of bone loss in postmenopausal women. Even small advantages in bone mass provide great reductions in fracture rates. However, the majority of studies have tested the relationship of calcium intake and bone mass using calcium supplements. Few intervention studies have manipulated calcium intake through foods. Calcium is only useful to the skeleton once it is absorbed. Therefore, the bioavailability of dietary calcium becomes important in the prevention and treatment of osteoporosis. Isotopic tracer techniques have only recently been employed in the labeling of foods with calcium isotopes for evaluation of calcium absorption. Milk calcium is usually the referent food which is typically absorbed at 20-40% depending on the calcium status of the subject. The absorptive efficiency of most vegetable sources is as good or better than for dairy foods, unless they have high concentrations of oxalic acid (spinach, for example) or phytic acid (wheat bran cereal, for example). Few vegetable sources are concentrated sources of calcium. Therefore, it would be difficult to obtain adequate intakes of calcium to protect against osteoporosis without liberal use of dairy products in the diet. Alternately, calcium supplements provide concentrated amounts of absorbable calcium, but they do not provide other nutrients necessary for skeletal growth and maintenance.

  5. Food microstructure affects the bioavailability of several nutrients.

    PubMed

    Parada, J; Aguilera, J M

    2007-03-01

    There is an increased interest in the role that some nutrients may play in preventing or ameliorating the effect of major diseases (for example, some types of cancer, cardiovascular diseases, eye disorders, among others). In this respect, the bioavailability or the proportion of an ingested nutrient that is made available (that is, delivered to the bloodstream) for its intended mode of action is more relevant than the total amount present in the original food. Disruption of the natural matrix or the microstructure created during processing may influence the release, transformation, and subsequent absorption of some nutrients in the digestive tract. Alternatively, extracts of bioactive molecules (for example, nutraceuticals) and beneficial microorganisms may be protected during their transit in the digestive system to the absorption sites by encapsulation in designed matrices. This review summarizes relevant in vivo and in vitro methods used to assess the bioavailability of some nutrients (mostly phytochemicals), types of microstructural changes imparted by processing and during food ingestion that are relevant in matrix-nutrient interactions, and their effect on the bioavailability of selected nutrients.

  6. Relative Influence of Initial Surface and Atmospheric Conditions on Seasonal Water and Energy Balances

    NASA Technical Reports Server (NTRS)

    Oglesby, Robert J.; Marshall, Susan; Roads, John O.; Robertson, Franklin R.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    We constructed and analyzed wet and dry soil moisture composites for the mid-latitude GCIP region of the central US using long climate model simulations made with the NCAR CCM3 and reanalysis products from NCEP. Using the diagnostic composites as a guide, we have completed a series of predictability experiments in which we imposed soil water initial conditions in CCM3 for the GCIP region for June 1 from anomalously wet and dry years, with atmospheric initial conditions taken from June 1 of a year with 'near-normal' soil water, and initial soil water from the near-normal year and atmospheric initial conditions from the wet and dry years. Preliminary results indicate that the initial state of the atmosphere is more important than the initial state of soil water determining the subsequent late spring and summer evolution of sod water over the GCIP region. Surprisingly, neither the composites or the predictability experiments yielded a strong influence of soil moisture on the atmosphere. To explore this further, we have made runs with extreme dry soil moisture initial anomalies imposed over the GCIP region (the soil close to being completely dry). These runs did yield a very strong effect on the atmosphere that persisted for at least three months. We conclude that the magnitude of the initial soil moisture anomaly is crucial, at least in CCM3, and are currently investigating whether a threshold exists, below which little impact is seen. In a complementary study, we compared the impact of the initial condition of snow cover versus the initial atmospheric state over the western US (corresponding to the westward extension of the GAPP program follow-on to GCIP). In this case, the initial prescription of snow cover is far more important than the initial atmospheric state in determining the subsequent evolution of snow cover. We are currently working to understand the very different soil water and snow cover results.

  7. Influence of Surface Condition over Siberia on the East Asian Climate

    NASA Astrophysics Data System (ADS)

    Arai, M.; Kimoto, M.

    2006-12-01

    Using observational data and atmospheric general circulation model, relationship between surface condition over Siberia and circulation over East Asia is examined. We notice particularly the influence of springtime surface temperature over Siberia, which becomes high when the snowmelt is encouraged in situ. It is found that when the surface temperature over Siberia is high in April, blocking events over northeastern Siberia and the Okhotsk Sea in May and June occur more frequently than climatology. In the year when the surface temperature over Siberia is high, a jet stream over the north of Siberia is formed in the upper troposphere corresponding to the enhanced meridional temperature gradient, and the polar frontal jet is observed earlier than climatology. Blocking anticyclones over northeastern Siberia and the Okhotsk Sea is considered to be formed by Rossby wave propagation along the polar frontal jet in early summer. Therefore, the early establishment of the polar frontal jet is consistent with the increase of the blocking frequency. Associated with the enhancement of blocking activity is the intensification of the surface Okhotsk high, and cold anomaly to its south over the northern part of Japan during the early summer season. The amplified Okhotsk high also causes the enhancement of the Baiu front, which is a part of East Asian monsoon. The finding of this study suggests monitoring the springtime surface condition over northern Siberia as one of the promising predictors for the early summer climate over East Asia. We also examined the future climate change on the Eurasian Continent and East Asia due to the global warming, using a general circulation model. The surface temperature over Siberia increases and springtime snowmelt is enhanced under doubled CO2 condition. Summertime blocking anticyclones are also increased and the Baiu front is enhanced, compared with the simulation of the present climate. These results are manifestation of relationship between

  8. Influence of support conditions on vertical whole-body vibration of the seated human body.

    PubMed

    M-Pranesh, Anand; Rakheja, Subhash; Demont, Richard

    2010-01-01

    The vibration transmission to the lumbar and thoracic segments of seated human subjects exposed to whole body vibration of a vehicular nature have been mostly characterised without the back and hand supports, which is not representative of general driving conditions. This non-invasive experimental study investigated the transmission of vertical seat vibration to selected vertebrae and the head along the vertical and fore-aft axes of twelve male human subjects seated on a rigid seat and exposed to random vertical excitation in the 0.5-20 Hz range. The measurements were performed under four different sitting postures involving combinations of back support conditions and hands positions, and three difference magnitudes of vertical vibration (0.25, 0.5 and 1.0 m/s(2) rms acceleration). The results showed significant errors induced by sensor misalignment and skin effects, which required appropriate correction methodologies. The averaged corrected responses revealed that the back support attenuates vibration in the vertical axis to all the body locations while increasing the fore-aft transmissibility at the C7 and T5. The hands position generally has a relatively smaller effect, showing some influences on the C7 and L5 vibration. Sitting without a back support resulted in very low magnitude fore-aft vibration at T5, which was substantially higher with a back support, suggestive of a probable change in the body's vibration mode. The effect of back support was observed to be very small on the horizontal vibration of the lower thoracic and lumbar regions. The results suggest that distinctly different target body-segment biodynamic functions need to be defined for different support conditions in order to represent the unique contribution of the specific support condition. These datasets may then be useful for the development of biodynamic models.

  9. Hydrodynamism and its influence on the reproductive condition of the edible sea urchin Paracentrotus lividus.

    PubMed

    Gianguzza, Paola; Bonaviri, Chiara; Prato, Ermelinda; Fanelli, Giovanni; Chiantore, Mariachiara; Privitera, Davide; Luzzu, Filippo; Agnetta, Davide

    2013-04-01

    Despite the large body of work published in the last two decades on the reproduction of the sea urchin Paracentrotus lividus, the reproductive aspects linked to hydrodynamic conditions and their influence on gonad production remain poorly understood. The present paper aims to evaluate the effect of hydrodynamism on the reproductive cycle of P. lividus. Variability in the gonadosomatic index (GSI) of P. lividus was estimated seasonally from 2007 to 2008 at two shallow sub-littoral flat basaltic areas at Ustica Island (Western Mediterranean). GSI was higher in the sites characterized by low hydrodynamism than in those with high hydrodynamism. Results also suggest a possible role for hydrodynamism in triggering processes of resource limitation (food shortage), probably by interfering with P. lividus feeding activity.

  10. Influence of home cooking conditions on Maillard reaction products in beef.

    PubMed

    Trevisan, Aurea Juliana Bombo; de Almeida Lima, Daniele; Sampaio, Geni Rodrigues; Soares, Rosana Aparecida Manólio; Markowicz Bastos, Deborah Helena

    2016-04-01

    The influence of home cooking methods on the generation of Maillard reaction products (MRP) in beef was investigated. Grilling and frying hamburgers to an internal temperature below 90 °C mainly generated furosine. When the temperature reached 90 °C and 100 °C, furosine content decreased by 36% and fluorescent compounds increased by up to 98%. Baking meat at 300 °C, the most severe heat treatment studied, resulted in the formation of carboxymethyllysine. Boiling in water caused very low MRP formation. Acrylamide concentrations in grilled, fried or baked meat were extremely low. Home cooking conditions leading to low MRP generation and pleasant colours were obtained and could be used to guide diabetic and chronic renal patients on how to reduce their carboxymethyllysine intake.

  11. Influence of growth conditions on the performance of InP nanowire solar cells.

    PubMed

    Cavalli, Alessandro; Cui, Yingchao; Kölling, Sebastian; Verheijen, Marcel A; Plissard, Sebastien R; Wang, Jia; Koenraad, Paul M; Haverkort, Jos E M; Bakkers, Erik P A M

    2016-11-11

    Nanowire based solar cells have attracted great attention due to their potential for high efficiency and low device cost. Photovoltaic devices based on InP nanowires now have characteristics comparable to InP bulk solar cells. A detailed and direct correlation of the influence of growth conditions on performance is necessary to improve efficiency further. We explored the effects of the growth temperature, and of the addition of HCl during growth, on the efficiency of nanowire array based solar cell devices. By increasing HCl, the saturation dark current was reduced, and thereby the nanowire solar cell efficiency was enhanced from less than 1% to 7.6% under AM 1.5 illumination at 1 sun. At the same time, we observed that the solar cell efficiency decreased by increasing the tri-methyl-indium content, strongly suggesting that these effects are carbon related.

  12. Influence of operating conditions on ceramic ultrafiltration membrane performance when treating textile effluents.

    PubMed

    Barredo-Damas, S; Alcaina-Miranda, M I; Gemma, M; Iborra-Clar, M I; Mendoza-Roca, J A

    2011-01-01

    This work studies the performance of three commercial ceramic ultrafiltration membranes (ZrO(2)-TiO(2)) treating raw effluent from a textile industry. The effect of crossflow velocity at 3, 4 and 5 m s(-1) as well as membrane characteristics, such as molecular weight cut-off (30, 50 and 150 kDa), on process performance were studied. Experiments were carried out in concentration mode in order to observe the effect of volume reduction factor simultaneously. Results showed a combined influence of both crossflow velocity and molecular weight cut-off on flux performance. TOC and COD removals up to 70% and 84% respectively were reached. On the other hand, almost complete color (>97%) and turbidity (>99%) removals were achieved for all the membranes and operating conditions.

  13. Influence of growth conditions on the performance of InP nanowire solar cells

    NASA Astrophysics Data System (ADS)

    Cavalli, Alessandro; Cui, Yingchao; Kölling, Sebastian; Verheijen, Marcel A.; Plissard, Sebastien R.; Wang, Jia; Koenraad, Paul M.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

    2016-11-01

    Nanowire based solar cells have attracted great attention due to their potential for high efficiency and low device cost. Photovoltaic devices based on InP nanowires now have characteristics comparable to InP bulk solar cells. A detailed and direct correlation of the influence of growth conditions on performance is necessary to improve efficiency further. We explored the effects of the growth temperature, and of the addition of HCl during growth, on the efficiency of nanowire array based solar cell devices. By increasing HCl, the saturation dark current was reduced, and thereby the nanowire solar cell efficiency was enhanced from less than 1% to 7.6% under AM 1.5 illumination at 1 sun. At the same time, we observed that the solar cell efficiency decreased by increasing the tri-methyl-indium content, strongly suggesting that these effects are carbon related.

  14. Modeling light and temperature influence on ammonium removal by Scenedesmus sp. under outdoor conditions.

    PubMed

    Ruiz-Martínez, Ana; Serralta, Joaquin; Seco, Aurora; Ferrer, Jose

    2016-10-01

    The ammonium removal rate of the microalga Scenedesmus sp. was studied under outdoor conditions. Microalgae were grown in a 500 L flat-plate photobioreactor and fed with the effluent of a submerged anaerobic membrane bioreactor. Temperature ranged between 9.5 °C and 32.5 °C and maximum light intensity was 1,860 μmol·m(-2)·s(-1). A maximum specific ammonium removal rate of 3.71 mg NH4(+)-N·g TSS(-1)·h(-1) was measured (at 22.6 °C and with a light intensity of 1,734 μmol·m(-2)·s(-1)). A mathematical model considering the influence of ammonium concentration, light and temperature was validated. The model successfully reproduced the observed values of ammonium removal rate obtained and it is thus presented as a useful tool for plant operation.

  15. Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

    SciTech Connect

    Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; Stephens, Graeme

    2016-06-16

    Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, in this paper we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 h per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. Finally, these regional differences of aerosol impacts may be linked to different meteorological conditions.

  16. Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

    DOE PAGES

    Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; ...

    2016-06-16

    Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, in this paper we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 hmore » per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. Finally, these regional differences of aerosol impacts may be linked to different meteorological conditions.« less

  17. Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; Stephens, Graeme

    2016-07-01

    Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3-24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3-30 h, 3-27 h, and 3-30 h per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20-22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. These regional differences of aerosol impacts may be linked to different meteorological conditions.

  18. Relative influence of meteorological conditions and aerosols on the lifetime of mesoscale convective systems

    PubMed Central

    Chakraborty, Sudip; Fu, Rong; Massie, Steven T.; Stephens, Graeme

    2016-01-01

    Using collocated measurements from geostationary and polar-orbital satellites over tropical continents, we provide a large-scale statistical assessment of the relative influence of aerosols and meteorological conditions on the lifetime of mesoscale convective systems (MCSs). Our results show that MCSs’ lifetime increases by 3–24 h when vertical wind shear (VWS) and convective available potential energy (CAPE) are moderate to high and ambient aerosol optical depth (AOD) increases by 1 SD (1σ). However, this influence is not as strong as that of CAPE, relative humidity, and VWS, which increase MCSs’ lifetime by 3–30 h, 3–27 h, and 3–30 h per 1σ of these variables and explain up to 36%, 45%, and 34%, respectively, of the variance of the MCSs’ lifetime. AOD explains up to 24% of the total variance of MCSs’ lifetime during the decay phase. This result is physically consistent with that of the variation of the MCSs’ ice water content (IWC) with aerosols, which accounts for 35% and 27% of the total variance of the IWC in convective cores and anvil, respectively, during the decay phase. The effect of aerosols on MCSs’ lifetime varies between different continents. AOD appears to explain up to 20–22% of the total variance of MCSs’ lifetime over equatorial South America compared with 8% over equatorial Africa. Aerosols over the Indian Ocean can explain 20% of total variance of MCSs’ lifetime over South Asia because such MCSs form and develop over the ocean. These regional differences of aerosol impacts may be linked to different meteorological conditions. PMID:27313203

  19. TECNAIRE winter field campaign: turbulent characteristics and their influence on air quality conditions

    NASA Astrophysics Data System (ADS)

    Yagüe, Carlos; Román Cascón, Carlos; Maqueda, Gregorio; Sastre, Mariano; Arrillaga, Jon A.; Artíñano, Begoña; Diaz-Ramiro, Elías; Gómez-Moreno, Francisco J.; Borge, Rafael; Narros, Adolfo; Pérez, Javier

    2016-04-01

    An urban field campaign was conducted at an air pollution hot spot in Madrid city (Spain) during winter 2015 (from 16th February to 2nd March). The zone selected for the study is a square (Plaza Fernández Ladreda) located in the southern part of the city. This area is an important intersection of several principal routes, and therefore a significant impact in the air quality of the area is found due to the high traffic density. Meteorological data (wind speed and direction, air temperature, relative humidity, pressure, precipitation and global solar radiation) were daily recorded as well as micrometeorological measurements obtained from two sonic anemometers. To characterize this urban atmospheric boundary layer (uABL), micrometeorological parameters (turbulent kinetic energy -TKE-, friction velocity -u∗- and sensible heat flux -H-) are calculated, considering 5-minute average for variance and covariance evaluations. Furthermore, synoptic atmospheric features were analyzed. As a whole, a predominant influence of high pressure systems was found over the Atlantic Ocean and western Spain, affecting Madrid, but during a couple of days (17th and 21st February) some atmospheric instability played a role. The influence of the synoptic situation and specially the evolution of the micrometeorological conditions along the day on air quality characteristics (Particulate Matter concentrations: PM10, PM2.5 and PM1, and NOx concentrations) are analyzed and shown in detail. This work has been financed by Madrid Regional Research Plan through TECNAIRE (P2013/MAE-2972).

  20. Rainforest air-conditioning: the moderating influence of epiphytes on the microclimate in tropical tree crowns

    NASA Astrophysics Data System (ADS)

    Stuntz, Sabine; Simon, Ulrich; Zotz, Gerhard

    2002-05-01

    Epiphytes are often assumed to influence the microclimatic conditions of the tree crowns that they inhabit. In order to quantify this notion, we measured the parameters "temperature" (of the substrate surface and the boundary layer of air above it), "evaporative drying rate" and "evapotranspiration" at various locations within tree crowns with differing epiphyte assemblages. The host tree species was Annona glabra, which was either populated by one of three epiphyte species ( Dimerandra emarginata, Tillandsia fasciculata, or Vriesea sanguinolenta) or was epiphyte-free. We found that during the hottest and driest time of day, microsites in the immediate proximity of epiphytes had significantly lower temperatures than epiphyte-bare locations within the same tree crown, even though the latter were also shaded by host tree foliage or branches. Moreover, water loss through evaporative drying at microsites adjacent to epiphytes was almost 20% lower than at exposed microsites. We also found that, over the course of several weeks, the evapotranspiration in tree crowns bearing epiphytes was significantly lower than in trees without epiphytes. Although the influence of epiphytes on temperature extremes and evaporation rates is relatively subtle, their mitigating effect could be of importance for small animals like arthropods inhabiting an environment as harsh and extreme as the tropical forest canopy.

  1. Influence of preparation conditions on 211 particle refinement in YBCO bulk superconductors with Ce addition

    NASA Astrophysics Data System (ADS)

    Diko, Pavel; Volochová, Daniela; Radušovská, Monika; Zmorayová, Katarína; Šefčiková, Martina; Antal, Vitalij; Jurek, Karel; Jirsa, Miloš; Kováč, Jozef

    2013-11-01

    The influence of CeO2 and BaCeO3 addition and the influence of processing conditions on Y2BaCuO5 (Y211) particle size and particle distribution in melt-processed YBa2Cu3O7/Y2BaCuO5 (Y123/Y211) bulk superconductors with nominal composition Y1.5Ba2Cu3Ox was investigated. Ce dissolved in the peritectic melt can actively hinder the Y211 particle growth by the Ostwald ripening process at melting stage. At sintering of intensively milled samples, Y211 particles in the charge free of CeO2 are smaller than Y211 particles formed in the charge with CeO2 addition and this behaviour can be related to the melt formation around added CeO2. The Y211 particle refinement in the mildly milled samples with large Y123 particles in the pressed green bodies is caused by very dense Y211 skeleton resistant to melt formation at the sintering stage. This skeleton is a barrier for pollution of the sample from the substrate and from the seed. BaCeO3 added instead CeO2 causes significant Y211 particle refinement also in the samples with homogenously distributed Y211 particles.

  2. Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms

    PubMed Central

    Hua, Yufeng; Oh, Je Hoon

    2015-01-01

    Purpose The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms. Materials and Methods Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases. Results Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length. Conclusion Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms. PMID:26256976

  3. Influence of Environmental Conditions on Methanogenic Compositions in Anaerobic Biogas Reactors

    PubMed Central

    Karakashev, Dimitar; Batstone, Damien J.; Angelidaki, Irini

    2005-01-01

    The influence of environmental parameters on the diversity of methanogenic communities in 15 full-scale biogas plants operating under different conditions with either manure or sludge as feedstock was studied. Fluorescence in situ hybridization was used to identify dominant methanogenic members of the Archaea in the reactor samples; enriched and pure cultures were used to support the in situ identification. Dominance could be identified by a positive response by more than 90% of the total members of the Archaea to a specific group- or order-level probe. There was a clear dichotomy between the manure digesters and the sludge digesters. The manure digesters contained high levels of ammonia and of volatile fatty acids (VFA) and were dominated by members of the Methanosarcinaceae, while the sludge digesters contained low levels of ammonia and of VFA and were dominated by members of the Methanosaetaceae. The methanogenic diversity was greater in reactors operating under mesophilic temperatures. The impact of the original inoculum used for the reactor start-up was also investigated by assessment of the present population in the reactor. The inoculum population appeared to have no influence on the eventual population. PMID:15640206

  4. Quantifying the local influence at a tall tower site in nocturnal conditions

    NASA Astrophysics Data System (ADS)

    Werth, David; Buckley, Robert; Zhang, Gengsheng; Kurzeja, Robert; Leclerc, Monique; Duarte, Henrique; Parker, Matthew; Watson, Thomas

    2017-02-01

    The influence of the local terrestrial environment on nocturnal atmospheric CO2 measurements at a 329-m television transmitter tower (and a component of a CO2 monitoring network) was estimated with a tracer release experiment and a subsequent simulation of the releases. This was done to characterize the vertical transport of emissions from the surface to the uppermost tower level and how it is affected by atmospheric stability. The tracer release experiment was conducted over two nights in May of 2009 near the Department of Energy's Savannah River Site (SRS) in South Carolina. Tracer was released on two contrasting nights—slightly stable and moderately stable—from several upwind surface locations. Measurements at the 329-m level on both nights indicate that tracer was able to mix vertically within a relatively short (˜24 km) distance, implying that nocturnal stable conditions do not necessarily prevent vertical dispersion in the boundary layer and that CO2 measurements at the tower are at least partly influenced by nearby emissions. A simulation of the tracer release is used to calculate the tower footprint on the two nights to estimate the degree to which the local domain affects the tower readings. The effect of the nocturnal boundary layer on the area sampled by the tower can be seen clearly, as the footprints were affected by changes in stability. The contribution of local sources to the measurements at the tower was minimal, however, suggesting that nocturnal concentrations at upper levels are contributed mostly by regional sources.

  5. The influence of coral reef benthic condition on associated fish assemblages.

    PubMed

    Chong-Seng, Karen M; Mannering, Thomas D; Pratchett, Morgan S; Bellwood, David R; Graham, Nicholas A J

    2012-01-01

    Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

  6. Rainforest air-conditioning: the moderating influence of epiphytes on the microclimate in tropical tree crowns.

    PubMed

    Stuntz, Sabine; Simon, Ulrich; Zotz, Gerhard

    2002-05-01

    Epiphytes are often assumed to influence the microclimatic conditions of the tree crowns that they inhabit. In order to quantify this notion, we measured the parameters "temperature" (of the substrate surface and the boundary layer of air above it), "evaporative drying rate" and "evapotranspiration" at various locations within tree crowns with differing epiphyte assemblages. The host tree species was Annona glabra, which was either populated by one of three epiphyte species (Dimerandra emarginata, Tillandsia fasciculata, or Vriesea sanguinolenta) or was epiphyte-free. We found that during the hottest and driest time of day, microsites in the immediate proximity of epiphytes had significantly lower temperatures than epiphyte-bare locations within the same tree crown, even though the latter were also shaded by host tree foliage or branches. Moreover, water loss through evaporative drying at microsites adjacent to epiphytes was almost 20% lower than at exposed microsites. We also found that, over the course of several weeks, the evapotranspiration in tree crowns bearing epiphytes was significantly lower than in trees without epiphytes. Although the influence of epiphytes on temperature extremes and evaporation rates is relatively subtle, their mitigating effect could be of importance for small animals like arthropods inhabiting an environment as harsh and extreme as the tropical forest canopy.

  7. Influence of conditioned reinforcement on the response-maintaining effects of quinpirole in rats.

    PubMed

    Collins, Gregory T; Woods, James H

    2009-09-01

    D2-like agonists, such as quinpirole, maintain responding in monkeys, rats, and mice when they are substituted for cocaine. This study examined the influence of operant history and cocaine-paired stimuli (CS) on quinpirole-maintained responding in rats trained to nose poke for cocaine. Upon acquisition of responding for cocaine, substitutions were performed in the presence or absence of injection-CS pairings. Although cocaine maintained responding regardless of whether injections were accompanied by CS, quinpirole maintained responding only when CS were paired with injections. To assess the influence of operant history, injections of cocaine, quinpirole, remifentanil, nicotine, or saline were made available on a previously inactive lever, while nose pokes continued to result in CS presentation. Although responding was reallocated from the nose poke to the lever when cocaine or remifentanil was available, lever presses remained low, and nose poking persisted when quinpirole or nicotine was made contingent upon lever presses. Finally, quinpirole pretreatments resulted in high rates of nose poking when nose pokes resulted in CS presentation alone, but failed to maintain nose poking when the CS was omitted. Taken together, these results suggest that the response-maintaining effects of quinpirole are primarily mediated by an enhancement of the conditioned reinforcing effects of earlier CS, rather than by a reinforcing effect of quinpirole.

  8. Influence of experimental conditions on data variability in the liver comet assay.

    PubMed

    Guérard, M; Marchand, C; Plappert-Helbig, U

    2014-03-01

    The in vivo comet assay has increasingly been used for regulatory genotoxicity testing in recent years. While it has been demonstrated that the experimental execution of the assay, for example, electrophoresis or scoring, can have a strong impact on the results; little is known on how initial steps, that is, from tissue sampling during necropsy up to slide preparation, can influence the comet assay results. Therefore, we investigated which of the multitude of steps in processing the liver for the comet assay are most critical. All together eight parameters were assessed by using liver samples of untreated animals. In addition, two of those parameters (temperature and storage time of liver before embedding into agarose) were further investigated in animals given a single oral dose of ethyl methanesulfonate at dose levels of 50, 100, and 200 mg/kg, 3 hr prior to necropsy. The results showed that sample cooling emerged as the predominant influence factor, whereas variations in other elements of the procedure (e.g., size of the liver piece sampled, time needed to process the liver tissue post-mortem, agarose temperature, or time of lysis) seem to be of little relevance. Storing of liver samples of up to 6 hr under cooled conditions did not cause an increase in tail intensity. In contrast, storing the tissue at room temperature, resulted in a considerable time-dependent increase in comet parameters.

  9. Invasive earthworms interact with abiotic conditions to influence the invasion of common buckthorn (Rhamnus cathartica).

    PubMed

    Roth, Alexander M; Whitfeld, Timothy J S; Lodge, Alexandra G; Eisenhauer, Nico; Frelich, Lee E; Reich, Peter B

    2015-05-01

    Common buckthorn (Rhamnus cathartica L.) is one of the most abundant and ecologically harmful non-native plants in forests of the Upper Midwest United States. At the same time, European earthworms are invading previously glaciated areas in this region, with largely anecdotal evidence suggesting they compound the negative effects of buckthorn and influence the invasibility of these forests. Germination and seedling establishment are important control points for colonization by any species, and manipulation of the conditions influencing these life history stages may provide insight into why invasive species are successful in some environments and not others. Using a greenhouse microcosm experiment, we examined the effects of important biotic and abiotic factors on the germination and seedling establishment of common buckthorn. We manipulated light levels, leaf litter depth and earthworm presence to investigate the independent and interactive effects of these treatments on buckthorn establishment. We found that light and leaf litter depth were significant predictors of buckthorn germination but that the presence of earthworms was the most important factor; earthworms interacted with light and leaf litter to increase the number and biomass of buckthorn across all treatments. Path analysis suggested both direct and moisture-mediated indirect mechanisms controlled these processes. The results suggest that the action of earthworms may provide a pathway through which buckthorn invades forests of the Upper Midwest United States. Hence, researchers and managers should consider co-invasion of plants and earthworms when investigating invasibility and creating preemptive or post-invasion management plans.

  10. 21 CFR 320.38 - Retention of bioavailability samples.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Retention of bioavailability samples. 320.38... (CONTINUED) DRUGS FOR HUMAN USE BIOAVAILABILITY AND BIOEQUIVALENCE REQUIREMENTS Procedures for Determining the Bioavailability or Bioequivalence of Drug Products § 320.38 Retention of bioavailability...

  11. Iron bioavailability of common beans (Phaseolus vulgaris L.) intrinsically labeled with (59)Fe.

    PubMed

    Brigide, Priscila; Ataide, Terezinha da R; Canniatti-Brazaca, Solange G; Baptista, Antônio S; Abdalla, Adibe L; Filho, Virgílio F Nascimento; Piedade, Sônia M S; Bueno, Nassib B; Sant'Ana, Antônio E G

    2014-07-01

    A radiobioassay was performed in rats with or without iron depletion to evaluate the iron bioavailability of diets enriched with common beans and with "multimixture", a nutritional supplement based on parts of foods that are not usually eaten. The full-body (59)Fe level was determined after 5h, the absorbed (59)Fe level was determined after 48 h, and the amount of (59)Fe retained was determined after 7 days. Iron bioavailability was assessed by the full-body radioactivity of the animals, determined using a solid scintillation detector. The iron bioavailability of common beans was higher in the iron-depleted animals (55.7%) than in the non-depleted animals (25.12%) because of the higher absorption rate in the iron-depleted animals. The multimixture did not influence dietary iron bioavailability. In addition, the iron bioavailability of common beans was similar to that observed in the standard source of iron for Wistar rats. Hence, common beans may be considered an adequate dietary iron source because of its high bioavailability.

  12. Bioavailability of cefuroxime axetil formulations.

    PubMed

    Donn, K H; James, N C; Powell, J R

    1994-06-01

    Cefuroxime axetil tablets have proved effective for the treatment of a variety of community-acquired infections. A suspension formulation has been developed for use in children. Two studies have been conducted to determine if the cefuroxime axetil formulations are bioequivalent. In the initial randomized, two-period crossover study, 24 healthy men received 250-mg doses of suspension and tablet formulations of cefuroxime axetil every 12 h after eating for seven doses. Each treatment period was separated by 4 days. Comparisons of serum and urine pharmacokinetic parameters indicated that the suspension and tablet formulations of cefuroxime axetil are not bioequivalent. Following the initial bioequivalency study, 0.1 % sodium lauryl sulfate (SLS) was added to the suspension to assure the homogeneity of the granules during the manufacturing process. In the subsequent randomized, three-period crossover study, 24 healthy men received single 250-mg doses of three cefuroxime axetil formulations: suspension without SLS, suspension with SLS, and tablet. Again each treatment period was separated by 4 days. Pharmacokinetic analyses demonstrated that while the suspension with SLS and suspension without SLS are bioequivalent, bioequivalence between the suspension with SLS and the tablet was not observed. Thus, the addition of the SLS surfactant to the suspension did not alter the bioavailability of the formulation.

  13. Winter conditioning of the Cascadian margin upwelling system: Remote forcing and coastal river influences (Invited)

    NASA Astrophysics Data System (ADS)

    Hales, B. R.; Goni, M. A.; Evans, W.; Harris, K. E.; Siedlecki, S. A.; Skyllingstad, E. D.; Wall, C.; Wetz, M.; White, A. E.

    2013-12-01

    The Cascadian margin stretches along the North American Pacific coast from Cape Mendocino to Vancouver Island, and across the land-ocean margin from the crest of the coastal mountains to the California Current. Carbonate system chemistry in these coastal waters is among the most dynamic in the world, with high net community productivity driving the system to a regionally important CO2 sink, while upwelled, respiration-influenced waters carry such elevated CO2 that they are often corrosive to biogenic carbonates. Most of the focus on this ecosystem has been on the influence of the seasonal upwelling and interaction with the upper thermocline of the ocean interior; recently, however, the downwelling-season has been recognized as critical in shaping the carbon cycling of the ecosystem. We present a combination of in-water survey and mooring data from river, estuary, and shelf waters; remote-sensing of coastal surface waters and watershed precipitation; and modeling results describing the physics of coastal circulation and storm-event precipitation and river discharge that shows how the winter conditions control carbon cycling. Coastally-trapped internal waves propagating northward from remote upwelling regions to the south lead to shoaling of the pycnocline such that upwelled source waters are present far inshore of the shelfbreak months before the onset of upwelling favorable winds. The close proximity of upwelled source waters to inner shelf upwelling locations leads to rapid transition in response to late winter and early spring upwelling favorable wind events. Winter storms and closely coupled flooding events deliver regionally significant amounts of nutrient-rich, low-CO2 fresh waters to the coastal ocean during downwelling conditions that retain these inputs on the shelf, and this fuels phytoplankton blooms that are a significant contribution to the annual net community production. These blooms and river influences maintain low coastal surface water pCO2 during

  14. Molecular dynamics study of non-nucleoside reverse transcriptase inhibitor 4-[[4-[[4-[(E)-2-cyanoethenyl]-2,6-dimethylphenyl]amino]-2-pyrimidinyl]amino]benzonitrile (TMC278/rilpivirine) aggregates: correlation between amphiphilic properties of the drug and oral bioavailability

    PubMed Central

    Frenkel, Yulia Volovik; Gallicchio, Emilio; Das, Kalyan; Levy, Ronald M.; Arnold, Eddy

    2009-01-01

    The non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC278/rilpivirine is an anti-AIDS therapeutic agent with high oral bioavailability despite its high hydrophobicity. Previous studies established a correlation between ability of the drug molecule to form stable, homogeneous populations of spherical nanoparticles (~100–120 nm in diameter) at low pH in surfactant-independent fashion, and good oral bioavailability. Here, we hypothesize that the drug is able to assume surfactant-like properties under physiologically relevant conditions, thus facilitating formation of nanostructuresin the absence of other surfactants. The results of all-atom molecular dynamics simulations indeed show that protonated drug molecules behave as surfactants at the water/aggregate interface while neutral drug molecules assist aggregate packing via conformational variability. Our simulation results suggest that amphiphilic behavior at low pH and intrinsic flexibility influence drug aggregation and are believed to play critical roles in the favorable oral bioavailability of hydrophobic drugs. PMID:19739675

  15. Influence of raised plastic floors compared with pine shaving litter on environment and Pekin duck condition.

    PubMed

    Karcher, D M; Makagon, M M; Fraley, G S; Fraley, S M; Lilburn, M S

    2013-03-01

    Commercial poultry production management practices have been under increased public scrutiny driven by concerns for food safety and animal welfare. Within the United States, wood shavings and raised plastic floors are common flooring systems used in duck production. It is intuitive that each flooring type would present different management challenges influencing physical characteristics of growing ducks. This study evaluated the relationship between flooring type and duck condition during the winter. Random samples of 20 ducks from 5 predetermined areas (n = 100) were examined in commercial duck houses (n = 9, litter; n = 11, raised plastic slats). Ducks were assessed at 7, 21, and 32 d of age for eye, nostril, and feather cleanliness, feather and foot pad quality, and gait. The data were analyzed to determine the proportion of ducks with a given score. In both housing types, the proportion of 0 scores for foot pad quality improved during the production cycle (P < 0.0001). Feather hygiene declined with age in ducks reared on litter flooring, whereas ducks reared on slatted flooring had cleaner feathers at d 32 (P < 0.011). With the exception of foot pad scores, the majority of ducks had no detectable problems for any single trait. The only main effect due to flooring pertained to feather quality with the proportion of ducks having a 0 or 1 score greater in litter flooring systems than slats (P < 0.05). Overall, the condition of ducks reared, regardless of flooring system, was considered to be good.

  16. Influence of taro (Colocasia esculenta L. Shott) growth conditions on the phenolic composition and biological properties.

    PubMed

    Gonçalves, Rui F; Silva, Artur M S; Silva, Ana Margarida; Valentão, Patrícia; Ferreres, Federico; Gil-Izquierdo, Angel; Silva, João B; Santos, Delfim; Andrade, Paula B

    2013-12-15

    Colocasia esculenta (L.) Shott, commonly known as taro, is an essential food for millions of people. The leaves are consumed in sauces, purees, stews, and soups, being also used in wound healing treatment. Nowadays, the consumers' demand for bioactive compounds from the diet led to the development of new agricultural strategies for the production of health-promoting constituents in vegetables. In this work, two strategies (variety choice and irrigation conditions) were considered in the cultivation of C. esculenta. The effect on the phenolic composition of the leaves was evaluated. Furthermore, a correlation between the biological activity of the different varieties and their chemical composition was established. Qualitative and quantitative differences in the phenolic composition were observed between varieties; furthermore, the irrigation conditions also influenced the composition. C. esculenta varieties were able to scavenge several oxidant species and to inhibit hyaluronidase, but data suggest that metabolites other than phenolics are involved. The results show that cultivation strategies can effectively modulate the accumulation of these types of bioactive compounds. Furthermore C. esculenta wound healing potential can be attributed, at least in part, to the protection of the wound site against oxidative/nitrosative damage and prevention of hyaluronic acid degradation.

  17. Bioethanol production from Scenedesmus obliquus sugars: the influence of photobioreactors and culture conditions on biomass production.

    PubMed

    Miranda, J R; Passarinho, P C; Gouveia, L

    2012-10-01

    A closed-loop vertical tubular photobioreactor (PBR), specially designed to operate under conditions of scarce flat land availability and irregular solar irradiance conditions, was used to study the potential of Scenedesmus obliquus biomass/sugar production. The results obtained were compared to those from an open-raceway pond and a closed-bubble column. The influence of the type of light source and the regime (natural vs artificial and continuous vs light/dark cycles) on the growth of the microalga and the extent of the sugar accumulation was studied in both PBRs. The best type of reactor studied was a closed-loop PBR illuminated with natural light/dark cycles. In all the cases, the relationship between the nitrate depletion and the sugar accumulation was observed. The microalga Scenedesmus was cultivated for 53 days in a raceway pond (4,500 L) and accumulated a maximum sugar content of 29 % g/g. It was pre-treated for carrying out ethanol fermentation assays, and the highest ethanol concentration obtained in the hydrolysate fermented by Kluyveromyces marxianus was 11.7 g/L.

  18. Intraoral environment conditions and their influence on marginal leakage in composite resin restorations.

    PubMed

    Mathias, Paula; Rocha, Viviane; Saraiva, Letícia; Cavalcanti, Andrea N; Azevedo, Juliana F; Paulillo, Luís Alexandre M S

    2010-01-01

    Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55 degrees C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

  19. Influence of imperfect end boundary condition on the nonlocal dynamics of CNTs

    NASA Astrophysics Data System (ADS)

    Fathi, Reza; Lotfan, Saeed; Sadeghi, Morteza H.

    2017-03-01

    Imperfections that unavoidably occur during the fabrication process of carbon nanotubes (CNTs) have a significant influence on the vibration behavior of CNTs. Among these imperfections, the boundary condition defect is studied in this investigation based on the nonlocal elasticity theory. To this end, a mathematical model of the non-ideal end condition in a cantilever CNT is developed by a strongly non-linear spring to study its effect on the vibration behavior. The weak form equation of motion is derived via Hamilton's principle and solved based on Rayleigh-Ritz approach. Once the frequency response function (FRF) of the CNT is simulated, it is found that the defect parameter injects noise to the FRF in the range of lower frequencies and as a result the small scale effect on the FRF remains undisturbed in high frequency ranges. Besides, in this work a process is introduced to estimate the nonlocal and defect parameters for establishing the mathematical model of the CNT based on FRF, which can be competitive because of its lower instrumentation and data analysis costs. The estimation process relies on the resonance frequencies and the magnitude of noise in the frequency response function of the CNT. The results show that the constructed dynamic response of the system based on estimated parameters is in good agreement with the original response of the CNT.

  20. Influence of Crystal Growth Cooling Conditions on Thermoelectric Properties of Aurivillius Phase Bi-V-O

    NASA Astrophysics Data System (ADS)

    Kohri, Hitoshi; Segawa, Mizuki; Yagasaki, Takayoshi

    2016-11-01

    Aurivillius phase Bi2VO5.5 is known as an oxygen ion conductor. In previous studies on Bi2VO5.5, the Seebeck coefficient of the sintered body was about 10 mVK-1 at 800 K. However, the resistivity was 103 Ω m at 800 K. It seemed that this high resistivity was caused by high grain boundary resistance because of cracks at boundaries. In this study, specimens have been prepared by a melting method, aimed at reducing the boundaries. The influence of crystal growth cooling conditions on the thermoelectric properties of Aurivillius phase Bi-V-O is discussed. The crystal growth cooling conditions investigated were slow cooling with cooling rate of 9 K h-1, furnace cooling, and quenching. The surface and cross-section of the sample were observed by scanning electron microscopy (SEM). The crystalline phase was identified by x-ray diffraction (XRD) analysis. The resistivity was measured by the direct current (DC) two or four terminals method. The Seebeck coefficient was measured by the small temperature difference method. The transgranular resistance and grain boundary resistance were evaluated by the complex impedance method. All samples consisted of layered grains. The grain thickness at cross section decreased with increasing cooling rate. The resistivity of the quenched and slowly cooled specimens was approximately 1000 times lower compared with the furnace cooled specimen and sintered body over the measured temperature range.

  1. Invited review: Influence of climatic conditions on the development, performance, and health of calves.

    PubMed

    Roland, L; Drillich, M; Klein-Jöbstl, D; Iwersen, M

    2016-04-01

    The objective of this review is to provide the reader with an overview of thermoregulatory mechanisms and the influence of climatic conditions in different housing systems on the development, performance, and health of calves. Thermic stress is observed in association with extreme temperatures and large temperature variations, but other variables such as relative humidity and wind speed can also contribute to thermic stress. Thermoregulation in calves is similar to that in adult cattle, but especially dystocial calves are more prone to heat loss. Heat or cold stress results in direct economic losses because of increased calf mortality and morbidity, as well as indirect costs caused by reduced weight gain, performance, and long-term survival. The climatic conditions in a variety of housing systems, associated health problems, and strategies to mitigate thermic stress are discussed in this review. The goal of housing is to alleviate the effect of climate on calves and provide a microclimate. Adequate ventilation with fresh air is essential to reduce respiratory disease. Common practices such as raising calves in individual outdoor enclosures have been challenged lately. Recent research seeks to evaluate the suitability of group housing under practical, economic, and animal welfare considerations. Limited results for reducing thermic stress can be achieved by simple measures such as shades or shelter, but additional heat or cold stress relieving strategies can be required depending on the housing system.

  2. Influence of Barometric Pressure Changes on Ventilation Conditions in Deep Mines

    NASA Astrophysics Data System (ADS)

    Wasilewski, Stanisław

    2014-10-01

    Barometric air pressure and its changes have a critical impact on ventilation conditions in the underground workings of deep mines. Changes in pressure are particularly important because they are responsible for the transient states of ventilation conditions, therefore, assessing the scale of pressure change is essential. Unfortunately, previously for many years in the Polish mining industry barometric pressure was recorded only on tapes of mechanical barographs by the ventilation department on the surface and therefore such dependencies of methane concentration due to barometric pressure changes have not been properly documented. Today, after the implementation in mines of instruments enabling the monitoring of absolute pressure in the workings of mines (Wasilewski, 2009) the conditions have been created to study the influence of pressure changes on changes of air parameters in the mine workings. Barometric pressure changes were observed and recorded over a course of approximately two years using monitoring system that utilized high accuracy pressure sensors on the surface and in selected workings of an underground mine. This paper presents a statistical analysis of the data that we generated from assessing pressure changes on the surface and at selected underground points in the mine. In the article, which presents the results of the first part of the study, some examples of when significant changes in pressure prior to the tragic events, which were not accompanied by changes in the methane concentration in mine workings, will also be shown. Interestingly, we found that the relationship between methane ignitions and explosions in longwall gob mined via the cave-in method is associated with changes in the barometric pressure. Several instances of methane ignitions and explosions in the gob of cave-in longwalls in recent years were compared with background barometric pressure changes. Research carried out in within the strategic project "Improving work safety in

  3. The influence of temperature on ozone production under varying NOx conditions - a modelling study

    NASA Astrophysics Data System (ADS)

    Coates, Jane; Mar, Kathleen A.; Ojha, Narendra; Butler, Tim M.

    2016-09-01

    Surface ozone is a secondary air pollutant produced during the atmospheric photochemical degradation of emitted volatile organic compounds (VOCs) in the presence of sunlight and nitrogen oxides (NOx). Temperature directly influences ozone production through speeding up the rates of chemical reactions and increasing the emissions of VOCs, such as isoprene, from vegetation. In this study, we used an idealised box model with different chemical mechanisms (Master Chemical Mechanism, MCMv3.2; Common Representative Intermediates, CRIv2; Model for OZone and Related Chemical Tracers, MOZART-4; Regional Acid Deposition Model, RADM2; Carbon Bond Mechanism, CB05) to examine the non-linear relationship between ozone, NOx and temperature, and we compared this to previous observational studies. Under high-NOx conditions, an increase in ozone from 20 to 40 °C of up to 20 ppbv was due to faster reaction rates, while increased isoprene emissions added up to a further 11 ppbv of ozone. The largest inter-mechanism differences were obtained at high temperatures and high-NOx emissions. CB05 and RADM2 simulated more NOx-sensitive chemistry than MCMv3.2, CRIv2 and MOZART-4, which could lead to different mitigation strategies being proposed depending on the chemical mechanism. The increased oxidation rate of emitted VOC with temperature controlled the rate of Ox production; the net influence of peroxy nitrates increased net Ox production per molecule of emitted VOC oxidised. The rate of increase in ozone mixing ratios with temperature from our box model simulations was about half the rate of increase in ozone with temperature observed over central Europe or simulated by a regional chemistry transport model. Modifying the box model set-up to approximate stagnant meteorological conditions increased the rate of increase of ozone with temperature as the accumulation of oxidants enhanced ozone production through the increased production of peroxy radicals from the secondary degradation of

  4. Influences of immunocontraception on time budgets, social behavior, and body condition in feral horses

    USGS Publications Warehouse

    Ransom, J.I.; Cade, B.S.; Hobbs, N.T.

    2010-01-01

    Managers concerned with shrinking habitats and limited resources for wildlife seek effective tools for limiting population growth in some species. Fertility control is one such tool, yet little is known about its impacts on the behavioral ecology of wild, free-roaming animals. We investigated influences of the immunocontraceptive porcine zona pellucida (PZP) on individual and social behavior in bands of feral horses (Equus caballus) in three discrete populations and used 14 hierarchical mixed effect models to gain insight into the influences of PZP treatment on feral horse behavior. A model of body condition was the strongest predictor of feeding, resting, maintenance, and social behaviors, with treated females allocating their time similarly to control females. Time spent feeding declined 11.4% from low condition to high condition females (F1,154 = 26.427, P < 0.001) and was partially reciprocated by a 6.0% increase in resting (F1,154 = 7.629, P = 0.006), 0.9% increase in maintenance (F1,154 = 7.028, P = 0.009), and 1.8% increase in social behavior (F1,154 = 15.064, P < 0.001). There was no difference detected in body condition of treated versus control females (F1,154 = 0.033, P = 0.856), but females with a dependent foal had lower body condition than those without a foal (F1,154 = 4.512, P = 0.038). Herding behavior was best explained by a model of treatment and the interaction of band fidelity and foal presence (AICc weight = 0.660) which estimated no difference in rate of herding behavior directed toward control versus treated females (F1,102 = 0.196, P = 0.659), but resident females without a dependent foal were herded 50.9% more than resident females with a foal (F3,102 = 8.269, P < 0.001). Treated females received 54.5% more reproductive behaviors from stallions than control mares (F1,105 = 5.155, P = 0.025), with the model containing only treatment being the most-supported (AICc weight = 0.530). Treated and control females received harem-tending behaviors

  5. The influence of different environmental and climatic conditions on vegetated aeolian dune landscape development and response

    NASA Astrophysics Data System (ADS)

    Nield, Joanna M.; Baas, Andreas C. W.

    2008-11-01

    Aeolian dune field development in coastal and semi-arid environments is a function of complex ecogeomorphic interactions which are sensitive to fluctuations in climatic and environmental conditions. We explore the relationships between ecological and geomorphic processes in the development of these landscape patterns and speculate on their response to variations in vegetation vitality and sediment transport capacity, indicating possible consequences of climate and land use change, using the Discrete ECogeomorphic Aeolian Landscape (DECAL) cellular automaton algorithm. This algorithm models dune field behaviour that reflects long-term trends prevalent in palaeo-records, but also elucidates possible evolutionary progressions, relaxation period sequences and threshold sensitivities. The landscape response is sensitive both to the perturbation itself and the state of the system when the disturbance occurs. Response amplitude decreases in simulated systems with reduced mobility unless an external disturbance mimicking fire or land clearance is applied concurrently with a reduction in growth vigour triggering a threshold type response when sufficient vegetation is removed. The model demonstrates that the relative response characteristics of the multiple vegetation types and their mutual feedback with geomorphic processes impart a significant influence on landscape equilibrium or attractor states. Fast growing vegetation enables the formation of hairpin (long-walled) parabolic dune systems, which eventually become sediment starved and stabilise, whereas inhospitable conditions inhibiting vegetation growth contribute to the development of active transgressive transverse dune fields. This simple vegetated dune model illustrates the power and versatility of a cellular automaton approach for exploring thresholds, sensitivities and possible evolutionary trajectories associated with the interactions between ecology, geomorphology and climatic conditions in complex earth surface

  6. Influence of treatment conditions on the oxidation of micropollutants by Trametes versicolor laccase.

    PubMed

    Margot, Jonas; Maillard, Julien; Rossi, Luca; Barry, D A; Holliger, Christof

    2013-09-25

    Many organic compounds present at low concentrations in municipal wastewater, such as various pharmaceuticals and biocides, are recalcitrant in conventional wastewater treatment plants (WWTPs). To improve their biodegradation, oxidoreductase enzymes such as laccases were tested. The goal was to find optimal conditions for the transformation of two anti-inflammatory pharmaceuticals (diclofenac (DFC) and mefenamic acid (MFA)), one biocide (triclosan (TCN)) and one plastic additive (bisphenol A (BPA)) by Trametes versicolor laccase. Experiments were conducted in spiked solutions at different pH values (from 3 to 9), enzyme concentrations (70-1400 Ul(-1)), reaction times (0-26 hours) and temperatures (10, 25 and 40°C) following a Doehlert experimental design. A semi-empirical model was developed to understand better the combined effects of the four factors and to determine optimal values. This model was able to fit well the experimental data (R(2)>0.97) and showed good predictive ability. All four factors had a significant effect on the micropollutant oxidation with the greatest influence shown by pH. Results for single compounds were different from those obtained for mixtures of micropollutants. For instance, DFC transformation occurred at much higher rates in mixtures under alkaline conditions. Optimal conditions were compound-dependent, but were found to be between pH 4.5 to 6.5 and between 25°C to more than 40°C. A laccase concentration of 730 Ul(-1) was sufficient to obtain a high removal rate (>90%) of the four individual compounds (range of times: 40 min to 5 hours), showing the potential of laccases to improve biodegradation of environmentally persistent compounds.

  7. Influence of Indoor Hygrothermal Conditions on Human Quality of Life in Social Housing

    PubMed Central

    Soares, Sara; Fraga, Silvia; Delgado, Joao M.P.Q.

    2015-01-01

    Background: Modern societies spend most of their time indoors, namely at home, and the indoor environment quality turns out to be a crucial factor to health, quality of life and well-being of the residents. The present study aims to understand how indoor environment relates with quality of life and how improving housing conditions impacts on individuals’ health. Design and Methods: This study case will rely on the following assessments in both rehabilitated and non-rehabilitated social housing: i) field measurements, in social dwellings (namely temperature, relative humidity, carbon dioxide concentration, air velocity, air change rate, level of mould spores and energy consumption); ii) residents’ questionnaires on social, demogaphic, behavioural, health characteristics and quality of life. Also, iii) qualitative interviews performed with social housing residents from the rehabilitated houses, addressing the self-perception of living conditions and their influence in health status and quality of life. All the collected information will be combined and analysed in order to achieve the main objective. Expected impact It is expected to define a Predicted Human Life Quality (PHLQ) index, that combines physical parameters describing the indoor environment measured through engineering techniques with residents’ and neighbourhood quality of life characteristics assessed by health questionnaires. Improvement in social housing should be related with better health indicators and the new index might be an important tool contributing to enhance quality of life of the residents. Significance for public health This study will contribute to understand how indoor environment relates with quality of life and how improving housing conditions impacts on individuals’ health, in social housing neighbourhoods. As so, it is important to share the undertaken methodology carried out by a multidisciplinary team, in order to allow other researchers following comparable studies to

  8. Bioavailability of iron from plant and animal ferritins.

    PubMed

    Lv, Chenyan; Zhao, Guanghua; Lönnerdal, Bo

    2015-05-01

    Iron deficiency is a major public health problem in the world. Ferritin is being explored as a novel and natural strategy for iron supplementation. The objective of this study was to evaluate iron bioavailability from ferritin isolated from plant and animal sources. The stability of plant ferritin and animal ferritin was studied by in vitro and in vivo digestion to determine whether these ferritins can pass through the gastrointestinal tract in intact form. Results from sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot indicate that both plant ferritin and animal ferritin can resist digestion (both under acidic and moderately acidic conditions). Furthermore, ferritin was labeled with (59)Fe, and bioavailability of iron from ferritin was assessed by uptake into Caco-2 cells. Our results indicate that iron is taken up from the ferritins and that iron bioavailability from soybean ferritin (rH-1:rH-2=1:1) is the highest. These results may be explained by the binding of ferritin to Caco-2 cells, which can be attributed to the interaction between ferritin and its putative receptor(s) at the surface of Caco-2 cells. In conclusion, ferritin from plant and animal sources may be developed as an iron source.

  9. Bioavailability of riboflavin from a gastric retention formulation.

    PubMed

    Ahmed, Iman S; Ayres, James W

    2007-02-07

    A gastric retention formulation (GRF) made of naturally occurring carbohydrate polymers and containing riboflavin was tested in vitro for swelling and dissolution characteristics as well as in fasting dogs for gastric retention. The bioavailability of riboflavin, a drug with a limited absorption site in the upper small intestine, from the GRF was studied in fasted healthy humans and compared to an immediate release formulation. It was found that when the GRF is dried and immersed in gastric juice it swells rapidly and releases its drug content in a zero-order fashion for a period of 24 h. In vivo studies in dogs showed that a rectangular shaped GRF stayed in the stomach of fasted dogs for more than 9 h, then disintegrated and reached the colon in 24 h. Endoscopic studies in dogs showed that the GRF hydrates and swells back to about 75% of its original size in 30 min. These in vivo results correlated with in vitro results. Pharmacokinetic parameters determined from urinary excretion data from six human subjects under fasting conditions showed that bioavailability depended on the size of the GRF. The biostudy indicated that bioavailability of riboflavin from a large size GRF was more than triple that measured after administration of an immediate release formulation. Deconvolved input functions from biostudy data suggest that the large size GRF stayed in the stomach for about 15 h.

  10. Rumen Microorganisms Decrease Bioavailability of Inorganic Selenium Supplements.

    PubMed

    Galbraith, M L; Vorachek, W R; Estill, C T; Whanger, P D; Bobe, G; Davis, T Z; Hall, J A

    2016-06-01

    Despite the availability of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study was to determine whether rumen microorganisms (RMO) alter the bioavailability of Se sources commonly used in Se supplements. Rumen microorganisms were isolated from ewes (n = 4) and incubated ex vivo with no Se (control), with inorganic Na selenite or Na selenate, or with organic selenomethionine (SeMet). Total Se incorporated into RMO and the amount of elemental Se formed were determined under equivalent conditions. Incorporation of Se from Na selenite, Na selenate, or SeMet into RMO was measured as fold change compared with control (no added Se). Incorporation of Se into microbial mass was greater for SeMet (13.2-fold greater than no-Se control) compared with inorganic Se supplements (P = 0.02); no differences were observed between inorganic Na selenate (3.3-fold greater than no-Se control) and Na selenite (3.5-fold greater than no-Se control; P = 0.97). Formation of non-bioavailable, elemental Se was less for RMO incubated with SeMet compared with inorganic Se sources (P = 0.01); no differences were observed between Na selenate and Na selenite (P = 0.09). The clinical importance of these results is that the oral bioavailability of organic SeMet should be greater compared with inorganic Se sources because of greater RMO incorporation of Se and decreased formation of elemental Se by RMO.

  11. An influence of normal stress and pore pressure on the conditions and dynamics of shear crack propagation in brittle solids

    NASA Astrophysics Data System (ADS)

    Shilko, Evgeny V.; Psakhie, Sergey G.; Popov, Valentin L.

    2016-11-01

    The paper is devoted to the study of the influence of crack-normal stress on the shear strength of the brittle material with initial crack and the geometrical condition of acceleration of dynamically growing crack towards the longitudinal wave speed. We considered elastic-brittle permeable materials with nanoscale pore size. We have shown that pore fluid in nanoporous brittle materials influences mainly the condition of shear crack propagation transition from conventional sub-Rayleigh regime to supershear one. The results of the study make it possible to assess the ability of initial cracks in brittle materials to develop in supershear regime under the condition of confined longitudinal shear.

  12. Influence of the Conditions of Electrode Position and Heat Treatment on the Structure and Properties of Metallic Coatings

    NASA Astrophysics Data System (ADS)

    Kovenskiy, I. M.; Kulemina, A. A.

    2016-04-01

    Influence of electrodeposition conditions and heat treatment on the structure and properties of metallic coatings has been considered. It has been that at different values of overvoltage, metals crystallize with a cellular, subgrain or monoblock structure. The final formation of the structure occurs during annealing, in the process of which either polygonization or recrystallization develops in the coatings. Varying the conditions of electrodeposition and heat treatment allows obtaining coatings with functional characteristics for specific operating conditions.

  13. Influence of environmental conditions on the kinetics and mechanism of dehydration of carbamazepine dihydrate.

    PubMed

    Han, J; Suryanarayanan, R

    1998-11-01

    The object of this project was to study the influence of temperature and water vapor pressure on the kinetics and mechanism of dehydration of carbamazepine dihydrate and to establish the relationship between the dehydration mechanism and the solid-state of the anhydrous phase formed. Three experimental techniques were utilized to study the kinetics of dehydration of carbamazepine dihydrate (C15H12N2O.2H2O)-thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and variable temperature powder X-ray diffractometry (VTXRD). These techniques respectively provide information about the changes in weight, heat flow and solid-state (phase) during the dehydration process. The instrumental setup was modified so that simultaneous control of both the temperature and the water vapor pressure was possible. The experiments were carried out at different temperatures, ranging from 26 to 64 degrees C. In the absence of water vapor, the dehydration followed the 2-dimensional phase boundary controlled model at all the temperatures studied. In the next stage, the water vapor pressure was altered while the studies were carried out at a single temperature of 44 degrees C. The dehydration was 2-dimensional phase boundary controlled at water vapor pressures < or = 5.1 torr while the Avrami-Erofeev kinetics (3-dimensional nucleation) was followed at water vapor pressures > or = 12.0 torr. In the former case, the anhydrous phase formed was X-ray amorphous while it was the crystalline anhydrous gamma-carbamazepine in the latter. Thus a relationship between the mechanism of dehydration and the solid-state of the product phase was evident. The dehydration conditions influence not only the mechanism but also the solid-state of the anhydrous phase formed. While the techniques of TGA and DSC have found extensive use in studying dehydration reactions, VTXRD proved to be an excellent complement in characterizing the solid-states of the reactant and product phases.

  14. Quantifying the local influence at a tall tower site in nocturnal conditions

    SciTech Connect

    Werth, David; Buckley, Robert; Zhang, Gengsheng; Kurzeja, Robert; Leclerc, Monique; Duarte, Henrique; Parker, Matthew; Watson, Thomas

    2015-10-17

    The influence of the local terrestrial environment on nocturnal atmospheric CO2 measurements at a 329-m television transmitter tower (and a component of a CO2 monitoring network) was estimated with a tracer release experiment and a subsequent simulation of the releases. This was done to characterize the vertical transport of emissions from the surface to the uppermost tower level and how it is affected by atmospheric stability. The tracer release experiment was conducted over two nights in May of 2009 near the Department of Energy’s Savannah River Site (SRS) in South Carolina. Tracer was released on two contrasting nights—slightly stable and moderately stable—from several upwind surface locations. Measurements at the 329-m level on both nights indicate that tracer was able to mix vertically within a relatively short (~24 km) distance, implying that nocturnal stable conditions do not necessarily prevent vertical dispersion in the boundary layer and that CO2 measurements at the tower are at least partly influenced by nearby emissions. A simulation of the tracer release is used to calculate the tower footprint on the two nights to estimate the degree to which the local domain affects the tower readings. The effect of the nocturnal boundary layer on the area sampled by the tower can be seen clearly, as the footprints were affected by changes in stability. The contribution of local sources to the measurements at the tower was minimal, however, suggesting that nocturnal concentrations at upper levels are contributed mostly by regional sources.

  15. Rapid and sensitive Nitrosomonas europaea biosensor assay for quantification of bioavailable ammonium sensu strictu in soil.

    PubMed

    Nguyen, Minh Dong; Risgaard-Petersen, Nils; Sørensen, Jan; Brandt, Kristian K

    2011-02-01

    Knowledge on bioavailable ammonium sensu strictu (i.e., immediately available for cellular uptake) in soil is required to understand nutrient uptake processes in microorganisms and thus of vital importance for plant production. We here present a novel ammonium biosensor approach based on the lithoautotrophic ammonia-oxidizing bacterium Nitrosomonas europaea transformed with a luxAB sensor plasmid. Bioluminescence-based ammonium detection was achieved within 10 min with a quantification limit in liquid samples of ∼20 μM and a linear response range up to 400 μM. Biosensor and conventional chemical quantification of ammonium in soil solutions agreed well across a range of sample and assay conditions. The biosensor was subsequently applied for a solid phase-contact assay allowing for direct interaction of biosensor cells with soil particle-associated (i.e., exchangeable plus fixed) ammonium. The assay successfully quantified bioavailable ammonium even in unfertilized soil and demonstrated markedly higher ratios of bioavailable ammonium to water- or 2 M KCl-exchangeable ammonium in anoxic soil than in corresponding oxic soil. Particle-associated ammonium contributed by at least 74% and 93% of the total bioavailable pool in oxic and anoxic soil, respectively. The N. europaea biosensor should have broad relevance for environmental monitoring of bioavailable ammonium and processes depending on ammonium bioavailability.

  16. Modeling the influence of varying hydraulic conditions on aerobic respiration and denitrification in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Trauth, N.; Schmidt, C.; Fleckenstein, J. H.

    2013-12-01

    Exchange of water and solutes across the stream-sediment interface is an important control for biogeochemical transformations in the hyporheic zone (HZ) with measurable impacts on nutrient cycling and solute attenuation in fluvial systems. Here we investigate the interplay between turbulent stream flow and HZ flow under various hydraulic conditions applied to two cases: a) three-dimensional generic pool-riffle sequences with different morphological properties, and b) a real mid-stream gravel-bar. Stream flow is simulated by the open source computational fluid dynamics (CFD) software OpenFOAM which provides the hydraulic head distribution at the streambed. It is sequentially coupled to the top of the groundwater model code MIN3P, simulating flow, solute transport, aerobic respiration (AR) and denitrification (DN) in the HZ. Flow in the HZ is directly influenced by the hydraulic head distribution at the streambed surface and the ambient groundwater flow. Three reactive transport scenarios are considered: 1) stream water as the primary source of dissolved oxygen (DO), nitrate (NO3) and dissolved organic carbon (DOC), 2) upwelling groundwater as an additionally source of NO3, and 3) upwelling groundwater as an additional source of DO in various concentrations. Results show an increase in hyporheic exchange flow for increasing stream discharge with a concurrent decrease in residence time. The fraction of circulating stream water through the HZ is in the range of 1x10-5 to 1x10-6 per unit stream length, decreasing with increasing discharge. Ambient groundwater flow in both the up- and downwelling direction diminishes significantly the hyporheic exchange flow and extent. Biogeochemical processes in the HZ are strongly controlled by ambient groundwater flow, even more so than by changes in stream discharge. AR and DN efficiencies of the HZ are significantly reduced by up- and downwelling groundwater and are positively correlated with median residence times. AR occurs in

  17. Meteorological conditions influencing the formation of level ice within the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Mazur, A. K.; Krezel, A.

    2012-12-01

    short term changes in sea ice cover and meteorological conditions. In following studies we analyzed the formation of level sea ice depending on some weather conditions (temperature, humidity, pressure at sea level, 10 meter wind). It can be clearly seen that the most important factors influencing formation of level ice are the temperature and wind.

  18. The influence of exogenous conditions on mobile measured gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Dierke, C.; Werban, U.; Dietrich, P.

    2012-12-01

    In the past, gamma ray measurements have been used for geological surveys and exploration using airborne and borehole logging systems. For these applications, the relationships between the measured physical parameter - the concentration of natural gamma emitters 40K, 238U and 232Th - and geological origin or sedimentary developments are well described. Based on these applications and knowledge in combination with adjusted sensor systems, gamma ray measurements are used to derive soil parameters to create detailed soil maps e.g., in digital soil mapping (DSM) and monitoring of soils. Therefore, not only qualitative but also quantitative comparability is necessary. Grain size distribution, type of clay minerals and organic matter content are soil parameters which directly influence the gamma ray emitter concentration. Additionally, the measured concentration is influenced by endogenous processes like soil moisture variation due to raining events, foggy weather conditions, or erosion and deposition of material. A time series of gamma ray measurements was used to observe changes in gamma ray concentration on a floodplain area in Central Germany. The study area is characterised by high variations in grain size distribution and occurrence of flooding events. For the survey, we used a 4l NaI(Tl) detector with GPS connection mounted on a sledge, which is towed across the field sites by a four-wheel-vehicle. The comparison of data from different time steps shows similar structures with minor variation between the data ranges and shape of structures. However, the data measured during different soil moisture contents differ in absolute value. An average increase of soil moisture of 36% leads to a decrease of Th (by 20%), K (by 29%), and U (by 41%). These differences can be explained by higher attenuation of radiation during higher soil moisture content. The different changes in nuclide concentration will also lead to varying ratios. We will present our experiences concerning

  19. Periphyton: an important regulator in optimizing soil phosphorus bioavailability in paddy fields.

    PubMed

    Wu, Yonghong; Liu, Junzhuo; Lu, Haiying; Wu, Chenxi; Kerr, Philip

    2016-11-01

    Periphyton is ubiquitous in paddy field, but its importance in influencing the bioavailability of phosphorus (P) in paddy soil has been rarely recognized. A paddy field was simulated in a greenhouse to investigate how periphyton influences P bioavailability in paddy soil. Results showed that periphyton colonizing on paddy soil greatly reduced P content in paddy floodwater but increased P bioavailability of paddy soil. Specifically, all the contents of water-soluble P (WSP), readily desorbable P (RDP), algal-available P (AAP), and NaHCO3-extractable P (Olsen-P) in paddy soil increased to an extent compared to the control (without periphyton) after fertilization. In particular, Olsen-P was the most increased P species, up to 216 mg kg(-1) after fertilization, accounting for nearly 60 % of total phosphorus (TP) in soil. The paddy periphyton captured P up to 1.4 mg g(-1) with Ca-P as the dominant P fraction and can be a potential crop fertilizer. These findings indicated that the presence of periphyton in paddy field benefited in improving P bioavailability for crops. This study provides valuable insights into the roles of periphyton in P bioavailability and migration in a paddy ecosystem and technical support for P regulation.

  20. Influence of food system conditions on N-acyl-L-homoserine lactones production by Aeromonas spp.

    PubMed

    Medina-Martínez, M S; Uyttendaele, M; Demolder, V; Debevere, J

    2006-12-01

    Eleven of 13 Aeromonas strains were shown to produce AHLs. Results of TLC showed that N-butanoyl-L-homoserine lactone (C4-HSL) was the main AHL produced in LB medium at 30 degrees C. The influence of different carbon sources, temperature, pH values and salt concentrations on AHL production was determined in eight A. hydrophila and one A. caviae strain. Additionally a quantitative study of C4-HSL production by A. hydrophila strain 519 under different conditions was performed. Positive results were found in the AHL induction assay for some Aeromonas strains in cultures in LB agar incubated at 12 degrees C after 72-96 h. The induction of the sensor strains by Aeromonas spp. occurred in LB medium supplemented with all carbon sources in a concentration of 0.5%. The production of C4-HSL by A. hydrophila 519 was found until 3.5% (w/v) of NaCl. For pHs close to the neutrality the C4-HSL production by A. hydrophila was evident after 24-48 h of incubation. A. hydrophila 519 produced C4-HSL under anaerobic conditions. Also, the AHL production by Aeromonas strains was studied in simulate agar of shrimp, fish and some vegetables. The production of AHLs was evident by almost all the test strains in shrimp simulated agar. In fish agar only for one of three fish species tested, positive results were found. Induction assay in vegetables simulated agar showed principally negative results, probably because of the presence of inhibitory compounds in these vegetables.

  1. Prior conditions influencing nurses' decisions to adopt evidence-based postoperative pain assessment practices.

    PubMed

    Carlson, Cathy L

    2010-12-01

    Over the past 30 years, postoperative pain relief has been shown to be inadequate. To provide optimal postoperative pain relief, it is imperative for nurses to use evidence-based postoperative pain assessment practices. This correlational descriptive study was conducted to identify factors, termed prior conditions, that influenced nurses' decisions to adopt three evidence-based postoperative pain assessment practices. A convenience sample of nurses who cared for adult postoperative patients in two Midwestern hospitals were surveyed, and 443 (46.9%) nurses responded. The previous practice and innovativeness of nurses were supportive of adoption of the three practices. Nurses felt that patients received adequate pain relief, which is unsupportive of adoption of the three practices because there is no impetus to change. Nurses who perceived the prior conditions as being supportive of adoption of pain management practices used multiple sources to identify solutions to clinical practice problems, and those who read professional nursing journals were more likely to have adopted the three practices and were more innovative. The number of sources used to identify solutions to clinical practice problems, previous practices, and innovativeness were predictive of nurses' adoption of the three evidence-based postoperative pain assessment practices. Nurses need to be encouraged to use multiple sources, including professional nursing journals, to identify solutions to clinical practice problems. Innovative nurses may be considered to be opinion leaders and need to be identified to promote the adoption of evidence-based postoperative pain assessment practices. Further exploration of the large unexplained variance in adoption of evidence-based postoperative pain assessment practices is needed.

  2. Site-specific conditions influence plant naturalization: The case of alien Proteaceae in South Africa

    NASA Astrophysics Data System (ADS)

    Moodley, Desika; Geerts, Sjirk; Rebelo, Tony; Richardson, David M.; Wilson, John R. U.

    2014-08-01

    The outcome of plant introductions is often considered in binary terms (invasive or non-invasive). However, most species experience a time lag before naturalization occurs, and many species become naturalized at some sites but not at others. It is therefore important to understand the site-specific mechanisms underlying naturalization. Proteaceae is an interesting case as some species are widespread invaders, while others, despite a long history of cultivation, show no signs of naturalization. At least 26 non-native Proteaceae species have been introduced to, and are cultivated in, South Africa. We mapped populations and examined differences between naturalized and non-naturalized populations (e.g. propagule pressure, land use and bioclimatic suitability). Of the 15 species surveyed, 6 were naturalized at one or more sites. Of these, Hakea salicifolia is most widely cultivated, but is only naturalizing in some areas (32 naturalized populations out of 62 populations that were surveyed). We found propagule pressure to be the most important determinant of naturalization for H. salicifolia. However, in suboptimal climatic conditions, naturalization only occurred if micro-site conditions were suitable, i.e. there was some disturbance and water available. For the other naturalized species there were few sites to compare, but we came to similar conclusions - Banksia integrifolia only naturalized at the site where it was planted the longest; Banksia serrata only naturalized at a site influenced by fire regimes; while Banksia formosa naturalized at sites with high propagule pressure, absence of fires and where there is no active clearing of the plants. Naturalization of Proteaceae in South Africa appears to be strongly mediated by site-specific anthropogenic activities (e.g. many planted individuals and water availability). More broadly, we argue that invasion biology needs to focus more closely on the mechanisms by which species and pathways interact to determine the

  3. Influence of microorganisms on the oxidation state distribution of multivalent actinides under anoxic conditions

    SciTech Connect

    Reed, Donald Timothy; Borkowski, Marian; Lucchini, Jean - Francois; Ams, David; Richmann, M. K.; Khaing, H.; Swanson, J. S.

    2010-12-10

    The fate and potential mobility of multivalent actinides in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium, uranium and neptunium are the near-surface multivalent contaminants of concern and are also key contaminants for the deep geologic disposal of nuclear waste. Their mobility is highly dependent on their redox distribution at their contamination source as well as along their potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. Under anoxic conditions, indirect and direct bioreduction mechanisms exist that promote the prevalence of lower-valent species for multivalent actinides. Oxidation-state-specific biosorption is also an important consideration for long-term migration and can influence oxidation state distribution. Results of ongoing studies to explore and establish the oxidation-state specific interactions of soil bacteria (metal reducers and sulfate reducers) as well as halo-tolerant bacteria and Archaea for uranium, neptunium and plutonium will be presented. Enzymatic reduction is a key process in the bioreduction of plutonium and uranium, but co-enzymatic processes predominate in neptunium systems. Strong sorptive interactions can occur for most actinide oxidation states but are likely a factor in the stabilization of lower-valent species when more than one oxidation state can persist under anaerobic microbiologically-active conditions. These results for microbiologically active systems are interpreted in the context of their overall importance in defining the potential migration of multivalent actinides in the subsurface.

  4. Mosses influence phosphorus cycling in rich fens by driving redox conditions in shallow soils.

    PubMed

    Crowley, Katherine F; Bedford, Barbara L

    2011-09-01

    Mosses play an integral role in the hydrologic regimes of ecosystems where they cover the soil surface, and thus affect biogeochemical cycling of elements influenced by soil oxidation-reduction (redox) reactions, including the plant growth-limiting nutrients, nitrogen and phosphorus (P). In rich fens where P often limits plant growth, we hypothesized that feedbacks between mosses and redox conditions would determine P availability to shallow-rooted forb species that constitute much of these wetlands' unusually high plant species diversity. In a moss removal experiment in three fens, forb tissue P and microbial P were greater while anion exchange membrane (AEM) resin P was lower where mosses occurred than where they were removed, suggesting both higher availability and greater demand for P in moss-covered soils. Coupled physicochemical and biological mechanisms drove moss effects on P cycling, ultimately through effects on soil oxygenation or reduction: higher redox potential underlying mosses corresponded to greater microbial activity, phosphatase enzyme activity, and colonization by arbuscular mycorrhizal fungi (AMF), all of which can promote greater P availability to plants. These more oxidized soils stimulated: (1) greater microbial activity and root vigor; (2) correspondingly greater P demand via microbial uptake, forb uptake, and iron (Fe)-P reactions; and (3) greater P supply through soil and root phosphatase activity and AMF colonization. This work demonstrates that mosses improve vascular plant P acquisition by alleviating stresses caused by reducing conditions that would otherwise prevail in shallow underlying soils, thus providing a mechanism by which mosses facilitate plant species diversity in rich fens.

  5. Cortical influences on brainstem circuitry responsible for conditioned pain modulation in humans.

    PubMed

    Youssef, Andrew M; Macefield, Vaughan G; Henderson, Luke A

    2016-07-01

    Conditioned pain modulation (CPM) is a powerful endogenous analgesic mechanism which can completely inhibit incoming nociceptor signals at the primary synapse. The circuitry responsible for CPM lies within the brainstem and involves the subnucleus reticularis dorsalis (SRD). While the brainstem is critical for CPM, the cortex can significantly modulate its expression, likely via the brainstem circuitry critical for CPM. Since higher cortical regions such as the anterior, mid-cingulate, and dorsolateral prefrontal cortices are activated by noxious stimuli and show reduced activations during other analgesic responses, we hypothesized that these regions would display reduced responses during CPM analgesia. Furthermore, we hypothesized that functional connectivity strength between these cortical regions and the SRD would be stronger in those that express CPM analgesia compared with those that do not. We used functional magnetic resonance imaging to determine sites recruited during CPM expression and their influence on the SRD. A lack of CPM analgesia was associated with greater signal intensity increases during each test stimulus in the presence of the conditioning stimulus compared to test stimuli alone in the mid-cingulate and dorsolateral prefrontal cortices and increased functional connectivity with the SRD. In contrast, those subjects exhibiting CPM analgesia showed no change in the magnitude of signal intensity increases in these cortical regions or strength of functional connectivity with the SRD. These data suggest that during multiple or widespread painful stimuli, engagement of the prefrontal and cingulate cortices prevents the generation of CPM analgesia, raising the possibility altered responsiveness in these cortical regions underlie the reduced CPM observed in individuals with chronic pain. Hum Brain Mapp 37:2630-2644, 2016. © 2016 Wiley Periodicals, Inc.

  6. On the enduring and substantial influence of Carl Rogers' not-quite necessary nor sufficient conditions.

    PubMed

    Farber, Barry A

    2007-09-01

    Carl Rogers' 1957 paper (see record 2007-14639-002) is arguably the most successful of his many attempts to clarify and render testable the ideas behind client-centered therapy. While each of the conditions that Rogers postulated has been linked to positive therapeutic outcome, taken together they have never been conclusively proved (nor disproved) to be either necessary or sufficient for positive outcome. Nevertheless, the overriding "take-home" message in this classic paper--that the therapist's attitude and caring presence is critical for therapeutic success--is one that has had virtually unparalleled influence in every segment of the psychotherapeutic community. Clinical and theoretical innovations in the psychoanalytic community serve as examples of the following proposition: that Rogers' concepts, while accepted more than ever by a remarkably wide variety of psychotherapists, remain essentially unacknowledged as originating with him or in the tradition of humanistic and client-centered therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  7. Influence of processing conditions on the thermal and mechanical properties of SU8 negative photoresist coatings

    NASA Astrophysics Data System (ADS)

    Feng, Ru; Farris, Richard J.

    2003-01-01

    The thermal and mechanical properties of a new negative photoresist, SU8, were characterized. The influence of curing conditions, such as baking temperature, baking time and UV dosage, on the thermal and mechanical properties of the resultant coatings was studied in detail. It was found that the glass-transition temperature (Tg) of the coatings was coincident with the baking temperature over the temperature range of 25 °C-220 °C for coatings being baked for just 20 min. However, the Tg reached a limiting value (about 240 °C) once the cross-linking reaction was complete, and would not increase further with the baking temperature. The peak temperature of the dimension versus temperature plots, where heat shrinkage occurred, was about a factor of 1.16 times higher than the baking temperature for the temperature range studied. Both the Tg and the shrinkage temperature were affected by the baking time. The thermal expansion coefficients (TEC), including the volumetric TEC (alphav), the in-plane TEC (alpha1) and the out-of-plane TEC (alpha2), were measured by a pressure-volume-temperature (PVT) apparatus and thermal-mechanical analyzer (TMA). Great residual stress could be generated during the process, and the change in residual stress with the environmental humidity was investigated using vibrational holographic interferometry.

  8. Influence of calcium and silica on hydraulic properties of sodium montmorillonite assemblages under alkaline conditions.

    PubMed

    Kinsela, Andrew S; Tjitradjaja, Alice; Collins, Richard N; Waite, T David; Payne, Timothy E; Macdonald, Bennett C T; White, Ian

    2010-03-01

    A sodium-washed montmorillonite was exposed to calcium and silica under alkaline conditions in order to gain insight into possible interactions of engineered clay barriers and cementitious leachates found in many waste storage facilities. The changes in physico-chemical properties of the material were investigated using a combination of dead-end filtration, electrophoresis and scanning electron microscopy. The results show minimal differentiation between unaltered Na-montmorillonite samples at the two pH values tested (9 and 12), with the structure of the resulting assemblages arising from repulsive tactoid interactions. The addition of calcium (50 mM) greatly decreases the size of the structural network, and in doing so, increases the hydraulic conductivity approximately 65-fold, with the effect being greatest at pH 12. Whilst the addition of silica alone (10 mM) produced little change in the hydraulic properties of montmorillonite, its combined effect with calcium produced alterations to the structural assemblages that could not be accounted for by the presence of calcium alone. The likely binding of calcium with multiple silanol groups appears to enhance the retention of water within the Na-montmorillonite assemblage, whilst still allowing the fluent passage of water. The results confirm that polyvalent cations such as Ca(2+) may have a dramatic effect on the structural and hydraulic properties of montmorillonite assemblages while the effects of solutions containing both silicate and calcium are complex and influenced by silica-cation interactions.

  9. Influence of indoor air conditions on radon concentration in a detached house.

    PubMed

    Akbari, Keramatollah; Mahmoudi, Jafar; Ghanbari, Mahdi

    2013-02-01

    Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden. In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was used to simulate radon entry into the building and air change rate, indoor temperature and relative humidity effects using a numerical approach. The results from analytical solution, measurements and numerical simulations showed that air change rate, indoor temperature and moisture had significant effects on indoor radon concentration. Increasing air change rate reduces radon level and for a specific air change rate (in this work Ach = 0.5) there was a range of temperature and relative humidity that minimized radon levels. In this case study minimum radon levels were obtained at temperatures between 20 and 22 °C and a relative humidity of 50-60%.

  10. Influence of solvothermal synthesis conditions in BiSI nanostructures for application in ionizing radiation detectors

    NASA Astrophysics Data System (ADS)

    Aguiar, I.; Mombrú, M.; Pérez Barthaburu, M.; Bentos Pereira, H.; Fornaro, L.

    2016-02-01

    BiSI belongs to the A V B VI C VII chalcohalides group of compounds. These compounds show several interesting properties such as ferroelectricity, piezoelectricity along the c axis, and photoconductivity. Moreover, BiSI is a potential semiconductor material for room-temperature gamma and x-ray detection, given its band gap of 1.57 eV and its high density, 6.41 g cm-3. In this work we present BiSI nanostructures synthesized by the solvothermal method with the intention of using them for ionizing radiation detection. The solvent was varied to study its influence in morphology, particle size and size distribution. Three different conditions were tested, using either water, monoethylene glycol and a mixture of both solvents. Nanostructures were characterized by XRD to determine the phase obtained and reaction completeness; TEM was used to observe nanostructures morphology, size, size distribution and crystallinity; and finally FT-IR diffuse reflectance was used to study monoethylene glycol presence in the samples. Nanorods in the range of 100-200 nm width were obtained in all samples, but round nanoparticles of around 10 nm in diameter were also detected in samples synthesized only with monoethylene glycol. Samples synthesized in monoethylene glycol were used to fabricate pellets to construct detectors. The detectors responded to ionizing radiation and a resistivity in the order of 1013 Ω cm was estimated. This work proposes, to our knowledge, the first study of BiSI for its application in ionizing radiation detection.

  11. Watershed-Scale Land Use Activities Influence the Physiological Condition of Stream Fish.

    PubMed

    King, Gregory D; Chapman, Jacqueline M; Midwood, Jonathan D; Cooke, Steven J; Suski, Cory D

    2016-01-01

    Land use changes within watersheds can have large effects on stream ecosystems, but the mechanistic basis of those effects remains poorly understood. While changes to population size presumably reflect underlying variation in organismal health and condition, such individual-level metrics are rarely evaluated in the context of ecosystem disturbance. To address this deficiency, we combined physiological sampling with geographic information systems to quantify the effects of land use on physiological indicators of health in largemouth bass. More specifically, we first quantified blood metrics relating to nutrition, oxidative stress, and the glucocorticoid stress response from largemouth bass residing in eight watersheds. We then used Akaike's information criterion to define relationships between these blood metrics and land cover, including forests, agricultural areas, urban areas, and wetlands. The proportion of forest cover in a watershed was the best predictor of blood metrics representing recent feeding and resistance to oxidative stress, whereas the proportion of wetlands was the best predictor of glucocorticoid function; however, further investigation is needed, as the explanatory power of the models was relatively low. Patterns in energy reserves were not influenced by any land use practices. Interestingly, anthropogenic land use categories, such as urban and agricultural areas, were not the best predictor for any blood metrics. Together, our results indicate that fish health is most related to natural features of a landscape rather than anthropogenic land uses. Furthermore, these findings suggest that physiological methods could supplement traditional population and community assessments to develop a more comprehensive understanding of ecosystem interactions and improve stream management.

  12. Conditions necessary for capillary hysteresis in porous media: Tests of grain size and surface tension influences

    NASA Astrophysics Data System (ADS)

    Tokunaga, Tetsu K.; Olson, Keith R.; Wan, Jiamin

    2004-05-01

    Hysteresis in the relation between water saturation and matric potential is generally regarded as a basic aspect of unsaturated porous media. However, the nature of an upper length scale limit for saturation hysteresis has not been previously addressed. Since hysteresis depends on whether or not capillary rise occurs at the grain scale, this criterion was used to predict required combinations of grain size, surface tension, fluid-fluid density differences, and acceleration in monodisperse systems. The Haines number (Ha), composed of the aforementioned variables, is proposed as a dimensionless number useful for separating hysteretic (Ha < 15) versus nonhysteretic (Ha > 15) behavior. Vanishing of hysteresis was predicted to occur for grain sizes greater than 10.4 ± 0.5 mm, for water-air systems under the acceleration of ordinary gravity, based on Miller-Miller scaling and Haines' original model for hysteresis. Disappearance of hysteresis was tested through measurements of drainage and wetting curves of sands and gravels and occurs between grain sizes of 10 and 14 mm (standard conditions). The influence of surface tension was tested through measurements of moisture retention in 7 mm gravel, without and with a surfactant (sodium dodecylbenzenesulfonate (SDBS)). The ordinary water system (Ha = 7) exhibited hysteresis, while the SDBS system (Ha = 18) did not. The experiments completed in this study indicate that hysteresis in moisture retention relations has an upper limit at Ha = 16 ± 2 and show that hysteresis is not a fundamental feature of unsaturated porous media.

  13. Influence of Sedimentary Bedding on Reactive Transport Parameters under Unsaturated Conditions

    SciTech Connect

    Mayes, Melanie; Tang, Guoping; Jardine, Philip M; McKay, Larry Donald; Yin, Xiangping Lisa; Pace, M. N.; Parker, Jack C; Zhang, Fan; Mehlhorn, Tonia L; Dansby-Sparks, Royce N

    2009-01-01

    Moisture and contaminant transport in partially saturated, heterogeneous, layered sediments is typically anisotropic. Solute transport parameters, including dispersivity and the adsorption coefficient, and the modeled concentration of reactive minerals may depend on the direction of flow with respect to sedimentary layering. Reaction rates, in contrast, should be independent of flow direction. We determined the influence of flow direction on transport parameters for nonreactive (Br{sup -}) and reactive (cobalt ethylenediaminetetraacetic acid [Co(II)EDTA{sup 2-}]) solutes under partially saturated conditions by imposing flow either parallel to or across sedimentary bedding in 11 intact sediment cores of various textures. Higher dispersivity of nonreactive tracers in parallel-bed cores suggested fluid channeling through permeable layers, while low-conductivity layers dampened channeling in cross-bed samples. Rates of transformation of Co(II)EDTA{sup 2-} into Co(III)EDTA{sup -} and of disassociation of Co{sup 2+} and EDTA{sup 4-} were modeled assuming that the reaction rates were independent of the flow direction. The concentration of Mn oxides that was responsible for the transformation reaction was dependent on the flow direction, which governed the extent of contact between the solution and the solid phase. Similarly, the adsorption constants of Co(II)EDTA{sup 2-} and Co(III)EDTA{sup -} were dependent on the flow direction but were also unique for each experiment. The modeled concentration of reactive minerals was the most sensitive parameter describing the reaction and transformation of Co(II)EDTA{sup 2-}.

  14. Influence of different treatment condition on biopolymer yield production for coagulation-flocculation process

    NASA Astrophysics Data System (ADS)

    Aisyah, I. S.; Murshed, M. F.; Norli, I.

    2016-06-01

    Two different agro wastes (banana pseudostem and rice straw) were utilized in order to extract biopolymer (pectin) known as coagulant aid in water and wastewater treatment. Factors such as pH, temperature and time were chosen due to the critical role in hot acid extraction process. The yield of biopolymer extraction from banana pseudostem was found to be higher at 28% meanwhile only 18% from rice straw was manage to produce from the dry weight 10 g, respectively. It was found that extraction temperature and extraction time were the most important factors influencing the biopolymer yield which increased with temperature and time or decreasing pH. Based on two level factorial design, the same condition of pH 1.5, temperature 90 oC and 4 hours extraction time can produce high amount of extracted biopolymer. Fourier Transform Infrared Spectroscopy (FTIR) was used to detect the existence of functional group which helps in the coagulation-flocculation process. Result indicates a similar functional group of biopolymer were detected for both difference agro wastes.

  15. Influence of packaging conditions on natural microbial population growth of endive.

    PubMed

    Charles, Florence; Rugani, Nathalie; Gontard, Nathalie

    2005-05-01

    The influence of three packaging conditions, i.e., unmodified atmosphere packaging (UAP), passive modified atmosphere packaging (MAP), and active MAP, on the natural microbial population growth of endive was investigated at 20 degrees C. For UAP, endive was placed in macroperforated oriented polypropylene pouches that maintained gas composition close to that of air (21 kPa O2 and 0 kPa CO2) but also limited superficial product dehydration. For MAP, endive was placed in low-density polyethylene pouches that induced a 3 kPa O2 and 5 kPa CO2 equilibrium atmosphere composition. Steady state was reached after 25 h of storage with an oxygen absorbing packet (active MAP) compared with 100 h without the packet (passive MAP) and was maintained for 200 h. After 312 h of storage, both active and passive MAP reduced total aerobic mesophile, yeast, and mold population growth compared with endive in UAP. Active MAP accelerated and improved the inhibition of Pseudomonas spp. and Enterobacteriaceae, respectively, probably because of the rapid O2 depletion during the transition period. A shift in the Enterobacteriaceae subpopulation from Rhanella aquatilis to Enterobacter agglomerans was observed for both passive and active MAP.

  16. MOCCA code for star cluster simulations - V. Initial globular cluster conditions influence on blue stragglers

    NASA Astrophysics Data System (ADS)

    Hypki, Arkadiusz; Giersz, Mirek

    2017-04-01

    In this paper, we present an analysis of the properties of blue straggler (BS) populations based on MOCCA simulations covering a range of initial globular cluster conditions. We broadly separate the BSs created in our simulations into two distinct types corresponding to their formation mechanism, namely evolutionary BSs formed from binary evolution and dynamical BSs formed from collisions or mergers induced by direct dynamical interactions between stars and binaries. We find that the dominant type of BS strongly depends on the initial semi-major axis distribution. With mostly compact binaries, the number of evolutionary BSs dominates. Conversely, with mostly wide binaries, dynamical BSs dominate. Higher cluster concentrations increase the contribution from dynamical BSs without affecting the numbers of evolutionary BSs, which are thus mostly descended from primordial binaries. We further consider the ratio between the number of BSs in binaries and as single stars (RB/S). Models that prefer compact and wide binaries begin with, respectively, high and low values of the ratio RB/S before converging to a nearly universal value ∼ 0.4. Finally, the initial eccentricity distribution has little to no influence on BS formation.

  17. The influence of different hydroponic conditions on thorium uptake by Brassica juncea var. foliosa.

    PubMed

    Wang, Dingna; Zhou, Sai; Liu, Li; Du, Liang; Wang, Jianmei; Huang, Zhenling; Ma, Lijian; Ding, Songdong; Zhang, Dong; Wang, Ruibing; Jin, Yongdong; Xia, Chuanqin

    2015-05-01

    The effects of different hydroponic conditions (such as concentration of thorium (Th), pH, carbonate, phosphate, organic acids, and cations) on thorium uptake by Brassica juncea var. foliosa were evaluated. The results showed that acidic cultivation solutions enhanced thorium accumulation in the plants. Phosphate and carbonate inhibited thorium accumulation in plants, possibly due to the formation of Th(HPO4)(2+), Th(HPO4)2, or Th(OH)3CO3 (-) with Th(4+), which was disadvantageous for thorium uptake in the plants. Organic aids (citric acid, oxalic acid, lactic acid) inhibited thorium accumulation in roots and increased thorium content in the shoots, which suggested that the thorium-organic complexes did not remain in the roots and were beneficial for thorium transfer from the roots to the shoots. Among three cations (such as calcium ion (Ca(2+)), ferrous ion (Fe(2+)), and zinc ion (Zn(2+))) in hydroponic media, Zn(2+) had no significant influence on thorium accumulation in the roots, Fe(2+) inhibited thorium accumulation in the roots, and Ca(2+) was found to facilitate thorium accumulation in the roots to a certain extent. This research will help to further understand the mechanism of thorium uptake in plants.

  18. Influence of Aerosol Chemical Composition on Heterogeneous Ice Formation under Mid-Upper Troposphere Conditions

    NASA Astrophysics Data System (ADS)

    Kanji, Z. A.; Niemand, M.; Saathoff, H.; Möhler, O.; Chou, C.; Abbatt, J.; Stetzer, O.

    2011-12-01

    Aerosols are involved in cooling/warming the atmosphere directly via interaction with incoming solar radiation (aerosol direct effect), or via their ability to act as cloud condensation or ice nuclei (IN) and thus play a role in cloud formation (indirect effect). In particular, the physical properties of aerosols such as size and solubility and chemical composition can influence their behavior and fate in the atmosphere. Ice nucleation taking place via IN is termed as heterogeneous ice nucleation and can take place with via deposition (ice forming on IN directly from the vapor phase), condensation/immersion (freezing via formation of the liquid phase on IN) or condensation (IN colliding with supercooled liquid drops). This presentation shows how the chemical composition and surface area of various tropospherically relevant aerosols influence conditions of temperature (T) and relative humidity (RH) required for heterogeneous ice formation conditions in the mid-upper troposphere regime (253 - 220K)? Motivation for this comes first from, the importance of being able to predict ice formation accurately so as to understand the hydrological cycle since the ice is the primary initiator of precipitation forming clouds. Second, the tropospheric budget of water vapour, an especially active greenhouse gas is strongly influenced by ice nucleation and growth. Third, ice surfaces in the atmosphere act as heterogeneous surfaces for chemical reactions of trace gases (e.g., SO2, O3, NOx and therefore being able to accurately estimate ice formation rates and quantify ice surface concentrations will allow a more accurate calculation of trace gas budgets in the troposphere. Ice nucleation measurements were conducted using a self-developed continuous flow diffusion chamber and static chamber. A number of tropospherically relevant particulates with naturally-varying and laboratory-modified surface chemistry/structure were investigated for their ice formation efficiency based on highest

  19. Pharmacokinetics and bioavailability of oxycodone and acetaminophen following single-dose administration of MNK-795, a dual-layer biphasic IR/ER combination formulation, under fed and fasted conditions

    PubMed Central

    Devarakonda, Krishna; Morton, Terri; Margulis, Rachel; Giuliani, Michael; Barrett, Thomas

    2014-01-01

    Background XARTEMIS™ XR (formerly MNK-795) is a combination oxycodone (OC) and acetaminophen (APAP) analgesic with both immediate-release and extended-release (ER) components (ER OC/APAP). The tablets are designed with gastric-retentive ER oral delivery technology that releases the ER component at a controlled rate in the upper gastrointestinal tract. Because consumption of food has demonstrated an impact on the pharmacokinetics (PK) of some marketed products using gastric-retentive ER oral delivery technology, a characterization of the effects of fed (high- and low-fat diets) versus fasted conditions on the PK of ER OC/APAP was performed. Methods This Phase I study used an open-label randomized single-dose three-period six-sequence crossover single-center design. Healthy adult participants (n=48) were randomized to receive two tablets of ER OC/APAP under three conditions: following a high-fat meal; following a low-fat meal; and fasted. Plasma concentration versus time data from predose throughout designated times up to 48 hours postdose was used to estimate the PK parameters of oxycodone and APAP. Results Thirty-one participants completed all three treatment periods. Both oxycodone and APAP were rapidly absorbed under fasted conditions. Total oxycodone and APAP exposures (area under the plasma drug concentration-time curve [AUC]) from ER OC/APAP were not significantly affected by food, and minimal changes to maximum observed plasma concentration for oxycodone and APAP were also noted. However, food marginally delayed the time to maximum observed plasma concentration of oxycodone and APAP. There was no indication that tolerability was affected by food. Conclusion The findings from this study suggest that ER OC/APAP can be administered with or without food. PMID:25170252

  20. Bioavailability enhancers of herbal origin: An overview

    PubMed Central

    Kesarwani, Kritika; Gupta, Rajiv

    2013-01-01

    Recently, the use of herbal medicines has been increased all over the world due to their therapeutic effects and fewer adverse effects as compared to the modern medicines. However, many herbal drugs and herbal extracts despite of their impressive in-vitro findings demonstrates less or negligible in-vivo activity due to their poor lipid solubility or improper molecular size, resulting in poor absorption and hence poor bioavailability. Nowadays with the advancement in the technology, novel drug delivery systems open the door towards the development of enhancing bioavailability of herbal drug delivery systems. For last one decade many novel carriers such as liposomes, microspheres, nanoparticles, transferosomes, ethosomes, lipid based systems etc. have been reported for successful modified delivery of various herbal drugs. Many herbal compounds including quercetin, genistein, naringin, sinomenine, piperine, glycyrrhizin and nitrile glycoside have demonstrated capability to enhance the bioavailability. The objective of this review is to summarize various available novel drug delivery technologies which have been developed for delivery of drugs (herbal), and to achieve better therapeutic response. An attempt has also been made to compile a profile on bioavailability enhancers of herbal origin with the mechanism of action (wherever reported) and studies on improvement in drug bioavailability, exhibited particularly by natural compounds. PMID:23620848

  1. Bioavailability enhancers of herbal origin: an overview.

    PubMed

    Kesarwani, Kritika; Gupta, Rajiv; Mukerjee, Alok

    2013-04-01

    Recently, the use of herbal medicines has been increased all over the world due to their therapeutic effects and fewer adverse effects as compared to the modern medicines. However, many herbal drugs and herbal extracts despite of their impressive in-vitro findings demonstrates less or negligible in-vivo activity due to their poor lipid solubility or improper molecular size, resulting in poor absorption and hence poor bioavailability. Nowadays with the advancement in the technology, novel drug delivery systems open the door towards the development of enhancing bioavailability of herbal drug delivery systems. For last one decade many novel carriers such as liposomes, microspheres, nanoparticles, transferosomes, ethosomes, lipid based systems etc. have been reported for successful modified delivery of various herbal drugs. Many herbal compounds including quercetin, genistein, naringin, sinomenine, piperine, glycyrrhizin and nitrile glycoside have demonstrated capability to enhance the bioavailability. The objective of this review is to summarize various available novel drug delivery technologies which have been developed for delivery of drugs (herbal), and to achieve better therapeutic response. An attempt has also been made to compile a profile on bioavailability enhancers of herbal origin with the mechanism of action (wherever reported) and studies on improvement in drug bioavailability, exhibited particularly by natural compounds.

  2. Integrating bioavailability approaches into waste rock evaluations

    USGS Publications Warehouse

    Ranville, James F.; Blumenstein, E. P.; Adams, Michael J.; Choate, LaDonna M.; Smith, Kathleen S.; Wildeman, Thomas R.

    2006-01-01

    The presence of toxic metals in soils affected by mining, industry, agriculture and urbanization, presents problems to human health, the establishment and maintenance of plant and animal habitats, and the rehabilitation of affected areas. A key to managing these problems is predicting the fraction of metal in a given soil that will be biologically labile, and potentially harmful ('bioavailable'). The molecular form of metals and metalloids, particularly the uncomplexed (free) form, controls their bioavailability and toxicity in solution. One computational approach for determining bioavailability, the biotic ligand model (BLM), takes into account not only metal complexation by ligands in solution, but also competitive binding of hardness cations (Ca 2+,Mg 2+,) and metal ions to biological receptor sites. The more direct approach to assess bioavailability is to explicitly measure the response of an organism to a contaminant. A number of microbial enzyme tests have been developed to assess the impact of pollution in a rapid and procedurally simple way. These different approaches in making bioavailability predictions may have value in setting landuse priorities, remediation goals, and habitat reclamation strategies.

  3. Measuring bioavailable copper using anodic stripping voltammetry

    SciTech Connect

    Deaver, E.; Rodgers, J.H. Jr.

    1996-11-01

    Since speciation can affect bioavailability and toxicity of copper in aquatic systems, accurate predictions of effects of bioavailable forms require detection and/or measurement of these forms. To develop an approach for measurement of bioavailable copper, a copper sulfate solution was used in 10-d aqueous and sediment toxicity tests with Hyalella azteca Saussure. These tests encompassed ranges of pH, alkalinity, hardness, and conductivity. Changes in copper speciation were measured using atomic absorption spectroscopy (AA) for dissolved copper and differential pulse anodic stripping voltammetry (DPASV) for labile copper, and concentrations were evaluated relative to amphipod survival. Ten-day LC50s based on AA-measured aqueous copper concentrations ranged from 42 to 142 {micro}g Cu/L, and LC50s based on DPASV-measured copper concentrations ranged from 17.4 to 24.8 {micro}g Cu/L. In 10-d tests using copper-amended sediments with diverse characteristics and AA-measured copper concentrations spanning an order of magnitude, total copper concentrations were not predictive of sediment toxicity, but H. azteca survival was explained by DPASV measurements that varied by {le}4%. In order to make defensible estimates of the potential risk of metals in sediments or water, it is essential to identify the fraction of total metal that is bioavailable. In these experiments, DPASV was useful for measuring bioavailable copper in aqueous and sediment tests with H. azteca.

  4. Radiographic detection of initial carious lesions on the proximal surfaces of teeth. Part I. The influence of exposure conditions

    SciTech Connect

    Arnold, L.V.

    1987-08-01

    The relationship between a number of technical exposure conditions and the diagnostic value of bitewing radiographs in the interpretation of initial proximal carious lesions was evaluated. The most important exposure factors for radiographs are tube voltage, filtration, and exposure time. Tube voltage and filtration were found to have an insignificant influence on the diagnostic quality. Exposure time proved to be the most critical factor in influencing diagnostic quality. The greatest difference in diagnostic quality, however, was caused by differences between observers.

  5. Bacterial biodegradation of polycyclic aromatic hydrocarbons (PAH) and potential effects of surfactants on PAH bioavailability

    SciTech Connect

    Aitken, M.D.; Grimberg, S.J.; Nagel, J.; Nagel, R.D.; Stringfellow, W.T.

    1996-02-01

    The purposes of this project were to evaluate whether indigenous microorganisms from polycyclic aromatic hydrocarbons (PAH)-contaminated soils produce surfactants (biosurfactants) as a means of enhancing the bioavailability of PAH; to improve the understanding of the general physiology of a diverse group of PAH-degrading bacteria; and to study in general how surfactants influence the biodegradation of hydrophobic chemicals.

  6. Autofluorescence of atmospheric bioaerosols - Biological standard particles and the influence of environmental conditions

    NASA Astrophysics Data System (ADS)

    Pöhlker, Christopher; Huffman, J. Alex; Förster, Jan-David; Pöschl, Ulrich

    2013-04-01

    standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We addressed the sensitivity and selectivity of autofluorescence based online techniques. Moreover, we investigated the influence of environmental conditions, such as relative humidity and oxidizing agents in the atmosphere, on the autofluorescence signature of standard bioparticles. Our results will support the molecular understanding and quantitative interpretation of data obtained by real-time FBAP instrumentation [5,6]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71. [6] Pöhlker, C., Huffman, J. A., Förster J.-D., & Pöschl, U., (2012) in preparation.

  7. A modeling approach of the influence of local hydrodynamic conditions on larval dispersal at hydrothermal vents.

    PubMed

    Bailly-Bechet, Marc; Kerszberg, Michel; Gaill, Françoise; Pradillon, Florence

    2008-12-07

    Deep-sea hydrothermal vent animal communities along oceanic ridges are both patchy and transient. Larval dispersal is a key factor in understanding how these communities function and are maintained over generations. To date, numerical approaches simulating larval dispersal considered the effect of oceanic currents on larval transportation over hundreds of kilometers but very seldom looked at the effect of local conditions within meters around chimneys. However, small scale significant variations in the hydrodynamics may influence larval fate in its early stages after release, and hence have a knock-on effect on both dispersal and colonization processes. Here we present a new numerical approach to the study of larval dispersal, considering small scales within the range of the biological communities, called "bio-hydrodynamical" scale, and ranging from a few centimeters to a few meters around hydrothermal sources. We use a physical model for the vent based on jet theory and compute the turbulent velocity field around the smoker. Larvae are considered as passive particles whose trajectories are affected by hydrodynamics, topography of the vent chimney and larval biological properties. Our model predicts that bottom currents often dominate all other factors either by entraining all larvae away from the vent or enforcing strong colonization rates. When bottom currents are very slow (<1 mms(-1)), general larvae motion is upwards due to entrainment by the main smoker jet. In this context, smokers with vertical slopes favor retention of larvae because larval initial trajectory is nearly parallel to the smoker wall, which increases the chances to settle. This retention phenomenon is intensified with increasing velocity of the main smoker jet because entrainment in the high velocity plume is preceded by a phase when larvae are attracted towards the smoker wall, which occurs earlier with higher velocity of the main jet. Finally, the buoyancy rate of the larvae, measured to be

  8. Bioavailability of Polyphenol Liposomes: A Challenge Ahead

    PubMed Central

    Mignet, Nathalie; Seguin, Johanne; Chabot, Guy G.

    2013-01-01

    Dietary polyphenols, including flavonoids, have long been recognized as a source of important molecules involved in the prevention of several diseases, including cancer. However, because of their poor bioavailability, polyphenols remain difficult to be employed clinically. Over the past few years, a renewed interest has been devoted to the use of liposomes as carriers aimed at increasing the bioavailability and, hence, the therapeutic benefits of polyphenols. In this paper, we review the causes of the poor bioavailability of polyphenols and concentrate on their liposomal formulations, which offer a means of improving their pharmacokinetics and pharmacodynamics. The problems linked to their development and their potential therapeutic advantages are reviewed. Future directions for liposomal polyphenol development are suggested. PMID:24300518

  9. Oral anticancer drugs: mechanisms of low bioavailability and strategies for improvement.

    PubMed

    Stuurman, Frederik E; Nuijen, Bastiaan; Beijnen, Jos H; Schellens, Jan H M

    2013-06-01

    unacceptable variation in the bioavailability and high investment costs. Furthermore, novel oral anticancer drugs are frequently associated with toxic effects including unacceptable gastrointestinal adverse effects. Therefore, compliance is often suboptimal, which may negatively influence treatment outcome.

  10. Cefpodoxime: comparative antibacterial activity, influence of growth conditions, and bactericidal activity.

    PubMed

    Knothe, H; Shah, P M; Eckardt, O

    1991-01-01

    The antimicrobial activity of cefpodoxime, the active metabolite of the new cephalosporin ester cefpodoxime proxetil, in comparison to cefixime, cefotiam, cefuroxime, and cefotaxime was determined against a broad spectrum of freshly isolated gram-positive and gram-negative bacterial strains. Cefpodoxime was demonstrated to be inhibitory at concentrations of less than or equal to 1 mg/l against 90% of strains of Moraxella catarrhalis, Haemophilus influenzae, Escherichia coli (beta-lactamase- negative strains), Klebsiella spp., Serratia spp., Proteus mirabilis, Proteus vulgaris, Providencia spp., and Salmonella spp. This antimicrobial activity of cefpodoxime was generally superior to that of cefuroxime and similar to that of cefixime. Cefpodoxime was active at less than or equal to 1 mg/l against 50% of the members of beta-lactamase-producing Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter spp., and Morganella morganii. Cefpodoxime proved to be highly inhibitory against group A, B, and G streptococci and Streptococcus pneumoniae (MIC90 less than 0.015 mg/l). The MICs of cefpodoxime and those of the other cephalosporins were less than 2 mg/l for greater than or equal to 90% of the strains of Staphylococcus aureus and Staphylococcus epidermidis, with the exception of cefixime which had no activity with MICs below 8 mg/l against these bacteria. Pseudomonas spp., Acinetobacter spp., and Enterococcus spp. were resistant to cefpodoxime. The antibacterial activity of cefpodoxime was only to a minor degree influenced by different growth conditions with the exception of high inoculum sizes against some beta-lactamase producing strains of gram-negative bacilli.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Protein secretory patterns of rat Sertoli and peritubular cells are influenced by culture conditions

    SciTech Connect

    Kierszenbaum, A.L.; Crowell, J.A.; Shabanowitz, R.B.; DePhilip, R.M.; Tres, L.L.

    1986-08-01

    An approach combining two-dimensional gel electrophoresis and autoradiography was used to correlate patterns of secretory proteins in cultures of Sertoli and peritubular cells with those observed in the incubation medium from segments of seminiferous tubules. Sertoli cells in culture and in seminiferous tubules secreted three proteins designated S70 (Mr 72,000-70,000), S45 (Mr 45,000), and S35 (Mr 35,000). Cultured Sertoli and peritubular cells and incubated seminiferous tubules secreted two proteins designated SP1 (Mr 42,000) and SP2 (Mr 50,000). SP1 and S45 have similar Mr but differ from each other in isoelectric point (pI). Cultured peritubular cells secreted a protein designated P40 (Mr 40,000) that was also seen in intact seminiferous tubules but not in seminiferous tubules lacking the peritubular cell wall. However, a large number of high-Mr proteins were observed only in the medium of cultured peritubular cells but not in the incubation medium of intact seminiferous tubules. Culture conditions influence the morphology and patterns of protein secretion of cultured peritubular cells. Peritubular cells that display a flat-stellate shape transition when placed in culture medium free of serum (with or without hormones and growth factors), accumulate various proteins in the medium that are less apparent when these cells are maintained in medium supplemented with serum. Two secretory proteins stimulated by follicle-stimulating hormone (FSH) (designated SCm1 and SCm2) previously found in the medium of cultured Sertoli cells, were also observed in the incubation medium of seminiferous tubular segments stimulated by FSH. Results of this study show that, although cultured Sertoli and peritubular cells synthesize and secrete proteins also observed in segments of incubated seminiferous tubules anther group of proteins lacks seminiferous tubular correlates.

  12. Comparative analysis of electric field influence on the quantum wells with different boundary conditions.

    PubMed Central

    Olendski, Oleg

    2015-01-01

    Analytical solutions of the Schrödinger equation for the one-dimensional quantum well with all possible permutations of the Dirichlet and Neumann boundary conditions (BCs) in perpendicular to the interfaces uniform electric field are used for the comparative investigation of their interaction and its influence on the properties of the system. Limiting cases of the weak and strong voltages allow an easy mathematical treatment and its clear physical explanation; in particular, for the small , the perturbation theory derives for all geometries a linear dependence of the polarization on the field with the BC-dependent proportionality coefficient being positive (negative) for the ground (excited) states. Simple two-level approximation elementary explains the negative polarizations as a result of the field-induced destructive interference of the unperturbed modes and shows that in this case the admixture of only the neighboring states plays a dominant role. Different magnitudes of the polarization for different BCs in this regime are explained physically and confirmed numerically. Hellmann-Feynman theorem reveals a fundamental relation between the polarization and the speed of the energy change with the field. It is proved that zero-voltage position entropies are BC independent and for all states but the ground Neumann level (which has ) are equal to while the momentum entropies depend on the edge requirements and the level. Varying electric field changes position and momentum entropies in the opposite directions such that the entropic uncertainty relation is satisfied. Other physical quantities such as the BC-dependent zero-energy and zero-polarization fields are also studied both numerically and analytically. Applications to different branches of physics, such as ocean fluid dynamics and atmospheric and metallic waveguide electrodynamics, are discussed. PMID:25914413

  13. Influence of storage conditions and shotshell wounding on the hygienic condition of hunted, uneviscerated pheasant (Phasianus colchicus).

    PubMed

    Paulsen, P; Nagy, J; Popelka, P; Ledecky, V; Marcincák, S; Pipová, M; Smulders, F J M; Hofbauer, P; Lazar, P; Dicakova, Z

    2008-01-01

    The effects of shot wounds on the hygienic conditions of pheasants (particularly those in the body cavity) were studied. Slaughtered (n = 33) and hunted pheasants (31 specimens with, and 33 specimens without shots in the body cavity) were stored uneviscerated at 0 and 4 degrees C. Specimens were taken at d 0, 3, 7, and 14. Hunted pheasants differed from slaughtered pheasants with respect to muscular hemorrhages and blood and fecal matter in the body cavity but also with regard to the presence of Escherichia coli in breast and thigh muscles. In addition, a higher thigh muscle pH (P < 0.05) was noted in hunted pheasants, with no significant (P > 0.05) increase observed during storage. Concentrations of biogenic amines in muscle tissue remained below the determination limit of 1 mg/kg for 90% of samples analyzed, with the maximum concentration for the remaining 10% of samples reaching 5.7 mg/kg, indicating a low incidence of contaminant bacteria. The observed changes in pH values and levels of biogenic amines failed to correlate with the presence or absence of shot lesions in the body cavity or abdominal region. Total aerobic counts increased significantly during storage, but the absolute numbers were consistently below 10(6) log(10) cfu/g. Although E. coli were <1 log(10) cfu/g in muscles of hunted pheasants on d 3 at 4 degrees C, counts of up to 3.7 log(10) cfu/g on d 7 at 4 degrees C indicated a loss of hygienic quality. Therefore, it is recommended that hunted, uneviscerated pheasants be stored 3 d at 4 degrees C, but not longer than 7 d after the hunt.

  14. Aggregation, sedimentation, dissolution and bioavailability of ...

    EPA Pesticide Factsheets

    Due to increasing use in flat screen applications, solar cells, ink–jet printing, and medical devices, cadmium-based quantum dots (QDs) are among the fastest growing classes of engineered nanomaterial. These wide-ranging consumer product applications and end of use disposal issues assure that QDs will eventually enter the marine environment. In an effort to understand the fate and transport of CdSe QDs in estuarine systems, the aggregation, sedimentation, dissolution, and bioavailability of CdSe QDs in seawater was investigated. The size of CdSe QDs increased from 40-60 nm to >1 mm within one hour once introduced to seawater, and the diffusion-limited aggregation led to highly polydispersed aggregates with loose structures. As a result, the sedimentation rate of CdSe QD aggregates in seawater was measured to be 4-10 mm/day, which was slow considering their relatively large size. Humic acid (HA), as a model natural organic matter, further increased the size and polydispersity of CdSe QDs, and slowed their sedimentation accordingly. Given the effect of light on CdSe QDs, natural sunlight and light filters were employed to simulate the photic conditions at different water depths in an estuarine system. It was observed that light played a vital role in promoting the dissolution of CdSe QDs and the release of dissolved Cd. The ZnS shell surrounding the CdSe core also significantly hindered the degradation of CdSe QDs into their ionic components. With sufficient

  15. Environmental factors and habitat use influence body condition of individuals in a species at risk, the grizzly bear

    PubMed Central

    Bourbonnais, Mathieu L.; Nelson, Trisalyn A.; Cattet, Marc R. L.; Darimont, Chris T.; Stenhouse, Gordon B.; Janz, David M.

    2014-01-01

    Metrics used to quantify the condition or physiological states of individuals provide proactive mechanisms for understanding population dynamics in the context of environmental factors. Our study examined how anthropogenic disturbance, habitat characteristics and hair cortisol concentrations interpreted as a sex-specific indicator of potential habitat net-energy demand affect the body condition of grizzly bears (n = 163) in a threatened population in Alberta, Canada. We quantified environmental variables by modelling spatial patterns of individual habitat use based on global positioning system telemetry data. After controlling for gender, age and capture effects, we assessed the influence of biological and environmental variables on body condition using linear mixed-effects models in an information theoretical approach. Our strongest model suggested that body condition was improved when patterns of habitat use included greater vegetation productivity, increased influence of forest harvest blocks and oil and gas well sites, and a higher percentage of regenerating and coniferous forest. However, body condition was negatively affected by habitat use in close proximity to roads and in areas where potential energetic demands were high. Poor body condition was also associated with increased selection of parks and protected areas and greater seasonal vegetation productivity. Adult females, females with cubs-of-year, juvenile females and juvenile males were in poorer body condition compared with adult males, suggesting that intra-specific competition and differences in habitat use based on gender and age may influence body condition dynamics. Habitat net-energy demand also tended to be higher in areas used by females which, combined with observed trends in body condition, could affect reproductive success in this threatened population. Our results highlight the importance of considering spatiotemporal variability in environmental factors and habitat use when assessing

  16. Environmental factors and habitat use influence body condition of individuals in a species at risk, the grizzly bear.

    PubMed

    Bourbonnais, Mathieu L; Nelson, Trisalyn A; Cattet, Marc R L; Darimont, Chris T; Stenhouse, Gordon B; Janz, David M

    2014-01-01

    Metrics used to quantify the condition or physiological states of individuals provide proactive mechanisms for understanding population dynamics in the context of environmental factors. Our study examined how anthropogenic disturbance, habitat characteristics and hair cortisol concentrations interpreted as a sex-specific indicator of potential habitat net-energy demand affect the body condition of grizzly bears (n = 163) in a threatened population in Alberta, Canada. We quantified environmental variables by modelling spatial patterns of individual habitat use based on global positioning system telemetry data. After controlling for gender, age and capture effects, we assessed the influence of biological and environmental variables on body condition using linear mixed-effects models in an information theoretical approach. Our strongest model suggested that body condition was improved when patterns of habitat use included greater vegetation productivity, increased influence of forest harvest blocks and oil and gas well sites, and a higher percentage of regenerating and coniferous forest. However, body condition was negatively affected by habitat use in close proximity to roads and in areas where potential energetic demands were high. Poor body condition was also associated with increased selection of parks and protected areas and greater seasonal vegetation productivity. Adult females, females with cubs-of-year, juvenile females and juvenile males were in poorer body condition compared with adult males, suggesting that intra-specific competition and differences in habitat use based on gender and age may influence body condition dynamics. Habitat net-energy demand also tended to be higher in areas used by females which, combined with observed trends in body condition, could affect reproductive success in this threatened population. Our results highlight the importance of considering spatiotemporal variability in environmental factors and habitat use when assessing

  17. Salinity effects on the bioavailability of aqueous metals for the estuarine killifish Fundulus heteroclitus.

    PubMed

    Dutton, Jessica; Fisher, Nicholas S

    2011-09-01

    Estuarine organisms experience varying salinity conditions on a daily and seasonal basis, and these fluctuations could influence the amount of metal accumulated from the aqueous phase. The present study experimentally assessed the role of salinity (0, 2, 6, 12, and 25 ppt) on the uptake of As, Cd, Cr, inorganic Hg [Hg(II)], and methylmercury (MeHg) into the euryhaline killifish (Fundulus heteroclitus) from the aqueous phase using gamma-emitting radioisotopes. Patterns of metal uptake as a function of salinity varied by metal. Chromium showed no relationship with salinity; Cd, which was most affected by salinity, showed an inverse relationship; and As, Hg(II), and MeHg uptake increased as salinity increased from 0 ppt to 25 ppt. Arsenic (salinities ≤ 6 ppt) and Cr were regulated by the fish, whereas Cd, Hg(II), and MeHg were not. Cadmium, Hg(II), and MeHg are chloro-complexed, increasing bioavailability for Hg(II) and MeHg, and reducing bioavailability for Cd. Concentration factors (CFs) were >1 at all salinities for Cd, Hg(II), and MeHg, indicating that the fish were more enriched in the metal than the surrounding water, whereas As and Cr CFs were <1 at all salinities. Uptake rate constants (k(u)s) were highest for MeHg (0.79-2.29 L g(-1) d(-1)), followed by Hg(II), Cd, Cr, and lowest for As (0.0004-0.0008 L g(-1) d(-1)). Tissue distribution of each metal was determined by dissections. Data for Cd showed that as salinity increased, the concentration of this metal increased in the viscera, whereas it decreased in the head and gills, suggesting that drinking to osmoregulate may account for a portion of Cd uptake from the aqueous phase in marine fish.

  18. Bioavailability of iron, vitamin A, zinc, and folic acid when added to condiments and seasonings.

    PubMed

    Degerud, Eirik M; Manger, Mari Skar; Strand, Tor A; Dierkes, Jutta

    2015-11-01

    Seasonings and condiments can be candidate vehicles for micronutrient fortification if consumed consistently and if dietary practices ensure bioavailability of the nutrient. In this review, we identify factors that may affect the bioavailability of iron, vitamin A, zinc, and folic acid when added to seasonings and condiments and evaluate their effects on micronutrient status. We take into consideration the chemical and physical properties of different forms of the micronutrients, the influence of the physical and chemical properties of foods and meals to which fortified seasonings and condiments are typically added, and interactions between micronutrients and the physiological and nutritional status of the target population. Bioavailable fortificants of iron have been developed for use in dry or fluid vehicles. For example, sodium iron ethylenediaminetetraacetic acid (NaFeEDTA) and ferrous sulfate with citric acid are options for iron fortification of fish and soy sauce. Furthermore, NaFeEDTA, microencapsulated ferrous fumarate, and micronized elemental iron are potential fortificants in curry powder and salt. Dry forms of retinyl acetate or palmitate are bioavailable fortificants of vitamin A in dry candidate vehicles, but there are no published studies of these fortificants in fluid vehicles. Studies of zinc and folic acid bioavailability in seasonings and condiments are also lacking.

  19. Bioavailability of iron, vitamin A, zinc, and folic acid when added to condiments and seasonings

    PubMed Central

    Degerud, Eirik M.; Manger, Mari Skar; Strand, Tor A.

    2015-01-01

    Seasonings and condiments can be candidate vehicles for micronutrient fortification if consumed consistently and if dietary practices ensure bioavailability of the nutrient. In this review, we identify factors that may affect the bioavailability of iron, vitamin A, zinc, and folic acid when added to seasonings and condiments and evaluate their effects on micronutrient status. We take into consideration the chemical and physical properties of different forms of the micronutrients, the influence of the physical and chemical properties of foods and meals to which fortified seasonings and condiments are typically added, and interactions between micronutrients and the physiological and nutritional status of the target population. Bioavailable fortificants of iron have been developed for use in dry or fluid vehicles. For example, sodium iron ethylenediaminetetraacetic acid (NaFeEDTA) and ferrous sulfate with citric acid are options for iron fortification of fish and soy sauce. Furthermore, NaFeEDTA, microencapsulated ferrous fumarate, and micronized elemental iron are potential fortificants in curry powder and salt. Dry forms of retinyl acetate or palmitate are bioavailable fortificants of vitamin A in dry candidate vehicles, but there are no published studies of these fortificants in fluid vehicles. Studies of zinc and folic acid bioavailability in seasonings and condiments are also lacking. PMID:26469774

  20. Arsenic bioavailability to rice is elevated in Bangladeshi paddy soils.

    PubMed

    Khan, K Asaduzzaman; Stroud, Jacqueline L; Zhu, Yong-Guan; McGrath, Steve P; Zhao, Fang-Jie

    2010-11-15

    Some paddy soils in the Bengal delta are contaminated with arsenic (As) due to irrigation of As-laden groundwater, which may lead to yield losses and elevated As transfer to the food chain. Whether these soils have a higher As bioavailability than other soils containing either geogenic As or contaminated by mining activities was investigated in a pot experiment. Fourteen soils varying in the source and the degree (4-138 mg As kg 1⁻¹) of As contamination were collected, 10 from Bangladeshi paddy fields (contaminated by irrigation water) and two each from China and the UK (geogenic or mining impacted), for comparison. Bangladeshi soils had higher percentages of the total As extractable by ammonium phosphate (specifically sorbed As) than other soils and also released more As into the porewater upon flooding. Porewater As concentrations increased with increasing soil As concentrations more steeply in Bangladeshi soils, with arsenite being the dominant As species. Rice growth and grain yield decreased markedly in Bangladeshi soils containing > 13 mg As kg 1⁻¹, but not in the other soils. Phosphate-extractable or porewater As was a better indicator of As bioavailability than total soil As. Rice straw As concentrations increased with increasing soil As concentrations; however, As phytotoxicity appeared to result in lower grain As concentrations. The relative proportions of inorganic As and dimethylarsinic acid (DMA) in grain varied among soils, and the percentage DMA was larger in greenhouse-grown plants than grain samples collected from the paddy fields of the same soil and the same rice cultivar, indicating a strong environmental influence on As species found in rice grain. This study shows that Bangladeshi paddy soils contaminated by irrigation had a higher As bioavailability than other soils, resulting in As phytotoxicity in rice and substantial yield losses.

  1. From Apprentice to Agenda-Setter: Comparative Analysis of the Influence of Contract Conditions on Roles in the Scientific Community

    ERIC Educational Resources Information Center

    Höhle, Ester

    2015-01-01

    Academic career paths in Europe are heterogeneous, and the chances for early career researchers to become a permanent member of the academic profession differ from country to country. In some countries, the employment prospects are very insecure. It is asked whether contract conditions at universities influence the chance of taking over a mature…

  2. Influence of weather conditions on splicing process and parameters of splicing single-mode telecommunication fibers of different types

    NASA Astrophysics Data System (ADS)

    Ratuszek, Marek; Zakrzewski, Zbigniew; Majewski, Jacek; Strozecki, Stefan; Zalewski, Jozef; Konefal, Tadeusz; Kula, Witold

    1999-05-01

    Results of research on the influence of weather conditions (t equals 10 divided by 27 degree(s)C; H equals 30 divided by 90%) on the process of splicing of standard single mode fibers SM (G.652) and fibers with dispersion shifted DS (G.653) have been presented as well as the results of optimization of splicing SM and DS fibers.

  3. Mouse Assay for Determination of Arsenic Bioavailability in Contaminated Soils

    EPA Science Inventory

    Background: Accurate assessment of human exposure estimates from arsenic-contaminated soils depends upon estimating arsenic (As) soil bioavailability. Development of bioavailability assays provides data needed for human health risk assessments and supports development and valida...

  4. Animal versus human oral drug bioavailability: do they correlate?

    PubMed

    Musther, Helen; Olivares-Morales, Andrés; Hatley, Oliver J D; Liu, Bo; Rostami Hodjegan, Amin

    2014-06-16

    Oral bioavailability is a key consideration in development of drug products, and the use of preclinical species in predicting bioavailability in human has long been debated. In order to clarify whether any correlation between human and animal bioavailability exist, an extensive analysis of the published literature data was conducted. Due to the complex nature of bioavailability calculations inclusion criteria were applied to ensure integrity of the data. A database of 184 compounds was assembled. Linear regression for the reported compounds indicated no strong or predictive correlations to human data for all species, individually and combined. The lack of correlation in this extended dataset highlights that animal bioavailability is not quantitatively predictive of bioavailability in human. Although qualitative (high/low bioavailability) indications might be possible, models taking into account species-specific factors that may affect bioavailability are recommended for developing quantitative prediction.

  5. Bioavailability of Cadmium in Inexpensive Jewelry

    PubMed Central

    Miller, Jennifer; Guinn, Daphne; Pearson, Janna

    2011-01-01

    Objectives: We evaluated the bioavailability of Cd in 86 components of 57 jewelry items found to contain high levels of Cd (> 10,000 ppm) by X-ray fluorescence (XRF), using extractions that simulate mouthing or swallowing of jewelry items. Methods: We screened jewelry for Cd content by XRF. Bioavailability was measured in two ways. Items were placed in saline solution at 37°C for 6 hr to simulate exposures from mouthing of jewelry items. Items were placed in dilute hydrochloric acid (HCl) at 37°C for 6–96 hr, simulating the worst-case scenario of a child swallowing a jewelry item. Damaged pieces of selected samples were also extracted by both methods to determine the effect of breaching the outer plating on bioavailability. Total Cd content of all items was determined by atomic absorption. Results: The 6-hr saline extraction yielded as much as 2,200 µg Cd, and 24-hr dilute HCl extraction yielded a maximum of > 20,000 µg Cd. Leaching of Cd in dilute HCl increased linearly over 6–96 hr, indicating potential for increasing harm the longer an item remains in the stomach. Damage to jewelry by breaching the outer plating generally, but not always, increased Cd release. Bioavailability did not correlate directly with Cd content. Conclusions: These results indicate the potential for dangerous Cd exposures to children who wear, mouth, or accidentally swallow high-Cd jewelry items. PMID:21377949

  6. BIOAVAILABILITY OF CHEMICAL CONTAMINANTS IN AQUATIC SYSTEMS

    EPA Science Inventory

    Before a chemical can elicit toxicity, the animal must accumulate a dose at a target tissue of sufficient magnitude to produce a response. Bioavailability refers to the degree to which this accumulation occurs relative to the amount of chemical present in the environment, and is ...

  7. Enhanced bioavailability of opiates after intratracheal administration

    SciTech Connect

    Findlay, J.W.A.; Jones, E.C.; McNulty, M.J.

    1986-03-01

    Several opiate analgesics have low oral bioavailabilities in the dog because of presystemic metabolism. Intratracheal administration may circumvent this first-pass effect. Three anesthetized beagles received 5-mg/kg doses of codeine phosphate intratracheally (i.t.), orally (p.o.) and intravenously (i.v.) in a crossover study. The following drugs were also studied in similar experiments: ethylmorphine hydrochloride (5 mg/kg), pholcodine bitartrate (10 mg/kg, hydrocodone bitartrate (4 mg/kg) and morphine sulfate (2.5 mg/kg). Plasma drug concentrations over the 24- to 48-hr periods after drug administrations were determined by radioimmunoassays. I.t. bioavailabilities (codeine (84%), ethylmorphine (100%), and morphine (87%)) of drugs with poor oral availabilities were all markedly higher than the corresponding oral values (14, 26, and 23%, respectively). I.t. bioavailabilities of pholcodine (93%) and hydrocodone (92%), which have good oral availabilities (74 and 79%, respectively), were also enhanced. In all cases, peak plasma concentrations occurred more rapidly after i.t. (0.08-0.17 hr) than after oral (0.5-2 hr) dosing and i.t. disposition often resembled i.v. kinetics. I.t. administration may be a valuable alternative dosing route, providing rapid onset of pharmacological activity for potent drugs with poor oral bioavailability.

  8. PREFACE: Quantum Field Theory Under the Influence of External Conditions (QFEXT07)

    NASA Astrophysics Data System (ADS)

    Bordag, M.; Mostepanenko, V. M.

    2008-04-01

    This special issue contains papers reflecting talks presented at the 8th Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT07), held on 17 21 September 2007, at Leipzig University. This workshop gathered 108 physicists and mathematicians working on problems which are focused on the following topics: •Casimir and van der Waals forces—progress in theory and new experiments, applications at micro- and nano-scale •Casimir effect—exact results, approximate methods and mathematical problems •Vacuum quantum effects in classical background fields—renormalization issues, singular backgrounds, applications to particle and high energy physics •Vacuum energy and gravity, vacuum energy in supersymmetric and noncommutative theories. This workshop is part of a series started in 1989 and 1992 in Leipzig by Dieter Robaschik, and continued in 1995, 1998 and 2001 in Leipzig by Michael Bordag. In 2003 this Workshop was organized by Kimball A Milton in Oklahoma, in 2005 by Emilio Elizalde in Barcelona and in 2007 it returned to Leipzig. The field of physics after which this series of workshops is named is remarkably broad. It stretches from experimental work on the measurement of dispersion forces between macroscopic bodies to quantum corrections in the presence of classical background fields. The underlying physical idea is that even in its ground state (vacuum) a quantum system responds to changes in its environment. The universality of this idea makes the field of its application so very broad. The most prominent manifestation of vacuum energy is the Casimir effect. This is, in its original formulation, the attraction between conducting planes due to the vacuum fluctuations of the electromagnetic field. In a sense, this is the long-range tail of the more general dispersion forces acting between macroscopic bodies. With the progress in nanotechnology, dispersion forces become of direct practical significance. On a more theoretical side

  9. Influence of reservoir conditions on multiphase flow in natural sandstone using lattice Boltzmann simulation: Investigation of suitable conditions in CCS and EOR

    NASA Astrophysics Data System (ADS)

    Tsuji, T.; Jiang, F.; Christensen, K. T.

    2015-12-01

    Microscopic two-phase fluid behavior in porous media is influenced by reservoir temperature, interfacial tension, pore structure, and porous medium characteristics (e.g., wettability), which vary significantly from one reservoir to the next. Pore-scale interfacial instabilities, such as snap-off and fingering phenomena, influence the stability, injectivity, mobility, and saturation within the reservoir. Therefore, understanding microscopic multiphase flow in porous media is crucial to estimating critical reservoir-scale characteristics, including storage capacity, leakage risk, and storage efficiency. Here we calculated fluid displacements within 3D pore spaces of natural sandstone using two-phase lattice Boltzmann (LB) simulation and characterized the influence of reservoir conditions upon multiphase flow. We classified the two-phase flow behavior that occurred under various conditions into three typical fluid displacement patterns on the diagram of capillary number (Ca) and viscosity ratio of the two fluids (M). Then the saturation of the nonwetting phase was calculated and mapped on the Ca-M diagram. The saturation map is useful to investigate suitable conditions in CCS and EOR. We further characterized dynamic pore-filling events (i.e., Haines jumps) from the fluid pressure variation. The results revealed the onset of capillary fingering in natural rock at a higher Ca than previously reported for homogeneous porous media, with the crossover region between typical displacement patterns much broader than in a homogeneous granular model. These differences between two-phase flow in natural rock and in a homogeneous porous structure could be the result of the heterogeneity of the natural rock.

  10. On the borderline of dissolved and particulate organic matter: partitioning and bioavailability of polycyclic aromatic hydrocarbons.

    PubMed

    Akkanen, Jarkko; Tuikka, Anita; Kukkonen, Jussi V K

    2012-04-01

    The functionality of dissolved organic matter (DOM) was studied by assessing the availability of polycyclic aromatic hydrocarbons (PAHs) spiked in pore water samples separated from sediments by water extraction and centrifugation with or without subsequent filtration. The purpose was to compare the effects of traditionally defined DOM (0.45-μm cut off) and larger colloidal material present in the separated pore water samples on the partitioning and bioavailability of PAHs. The tested PAHs included phenanthrene (Phe), fluoranthene (Flu), pyrene (Pyr) and benzo[a]pyrene (BaP). Bioavailability of the selected PAHs was tested with two ecologically different organisms: pelagic filter feeder Daphnia magna and sediment-dwelling deposit feeder Lumbriculus variegatus. Sorption to DOM (i.e. in filtered samples) was clearly higher for BaP than for the other PAH. This was also reflected in significantly reduced bioavailability for both model organisms in the filtered samples compared to DOM-free conditions. For the other PAHs the sorption was significant only in the unfiltered samples indicating the importance of larger colloidal material. Thus, the bioavailability of PAHs was also more effectively reduced by the colloidal material. This holds true for both the model organisms, indicating that the ecological differences i.e. filter feeder vs. deposit feeder do not affect in this respect. It appears that considering only traditionally defined DOM, material that may be present in environmental samples and is important for the speciation and bioavailability of contaminants is ignored.

  11. Targeted Removal of Bioavailable Metal as a Detoxification Strategy for Carbon Nanotubes

    PubMed Central

    Liu, Xinyuan; Guo, Lin; Morris, Daniel; Kane, Agnes B.; Hurt, Robert H.

    2008-01-01

    There is substantial evidence for toxicity and/or carcinogenicity upon inhalation of pure transition metals in fine particulate form. Carbon nanotube catalyst residues may trigger similar metal-mediated toxicity, but only if the metal is bioavailable and not fully encapsulated within fluid-protective carbon shells. Recent studies have documented the presence of bioavailable iron and nickel in a variety of commercial as-produced and vendor “purified” nanotubes, and the present article examines techniques to avoid or remove this bioavailable metal. First, data are presented on the mechanisms potentially responsible for free metal in “purified” samples, including kinetic limitations during metal dissolution, the re-deposition or adsorption of metal on nanotube outer surfaces, and carbon shell damage during last-step oxidation or one-pot purification. Optimized acid treatment protocols are presented for targeting the free metal, considering the effects of acid strength, composition, time, and conditions for post-treatment water washing. Finally, after optimized acid treatment, it is shown that the remaining, non-bioavailable (encapsulated) metal persists in a stable and biologically unavailable form up to two months in an in vitro biopersistence assay, suggesting that simple removal of bioavailable (free) metal is a promising strategy for reducing nanotube health risks. PMID:19255622

  12. Biogeochemical controls of uranium bioavailability from the dissolved phase in natural freshwaters

    USGS Publications Warehouse

    Croteau, Marie-Noele; Fuller, Christopher C.; Cain, Daniel J.; Campbell, Kate M.; Aiken, George R.

    2016-01-01

    To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater speciesLymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO2(CO3)2–2) best predicts U bioavailability to L. stagnalis, challenging the free-ion activity model postulate.

  13. Bioavailability of purified subcellular metals to a marine fish.

    PubMed

    Guo, Feng; Yao, Jie; Wang, Wen-Xiong

    2013-09-01

    In the present study, the authors used a supply of naturally contaminated oysters to investigate how the subcellular metal distribution and the metal burden in prey affected the transfer of metals to a marine fish, the grunt Terapon jarbua. The oysters, Crassostrea hongkongensis, each with different contamination histories, were collected and separated into 3 subcellular fractions: 1) metal-rich granules, 2) cellular debris, and 3) a combined fraction of organelles, heat-denatured proteins, and metallothionein-like proteins, defined as the trophically available metal (TAM). These purified fractions showed a wide range of metal concentrations and were fed to the fish for a period of 7 d at a daily comparable feeding rate of 3% of fish body weight. After 7 d exposure, the newly absorbed metals were mainly distributed in the intestine and liver, indicating a significant tissue-specific trophic transfer, especially for Cd and Cu. The trophic transfer factors (TTFs) showed a sequence of cellular debris >TAM > metal-rich granules, suggesting the impact of subcellular distribution in prey on metal bioavailability. However, significant inverse relationships between the TTFs and the metal concentrations in diets were also found in the present study, especially for Cd and Zn. The subcellular metal compartmentalization might be less important than the metal concentration in prey influencing the trophic transfer. The authors' results have important implications for bioavailability and environmental assessment of dietary metals.

  14. Enhancement of solubility, antioxidant ability and bioavailability of taxifolin nanoparticles by liquid antisolvent precipitation technique.

    PubMed

    Zu, Yuangang; Wu, Weiwei; Zhao, Xiuhua; Li, Yong; Wang, Weiguo; Zhong, Chen; Zhang, Yin; Zhao, Xue

    2014-08-25

    Taxifolin is a kind of flavanonol, whose antioxidant ability is superior to that of ordinary flavonoids compounds owing to its special structure. However, its low bioavailability is a major obstacle for biomedical applications, so the experiment is designed to prepare taxifolin nanoparticles by liquid antisolvent precipitation (LAP) to improve its bioavailability. We selected ethanol as solvent, deionized water as antisolvent, and investigated primarily the type of surfactant and adding amount, drug concentration, volume ratio of antisolvent to solvent, precipitation temperature, dropping speed, stirring speed, stirring time factors affecting drug particles size. Results showed that the poloxamer 188 was selected as the surfactant and the particle size of taxifolin obviously reduced with the increase of the poloxamer 188 concentration, the drug concentration and the dropping speed from 0.08% to 0.45%, from 0.04 g/ml to 0.12 g/ml, from 1 ml/min to 5 ml/min, respectively, when the volume ratio of antisolvent to solvent increased from 2.5 to 20, the particle size of taxifolin first increased and then decreased, the influence of precipitation temperature, stirring speed, stirring time on particle size were not obvious, but along with the increase of mixing time, the drug solution would separate out crystallization. The optimum conditions were: the poloxamer 188 concentration was 0.25%, the drug concentration was 0.08 g/ml, the volume ratio of antisolvent to solvent was 10, the precipitation temperature was 25 °C, the dropping speed was 4 ml/min, the stirring speed was 800 r/min, the stirring time was 5 min. Taxifolin nanosuspension with a MPS of 24.6 nm was obtained under the optimum conditions. For getting taxifolin nanoparticles, the lyophilization method was chosen and correspondingly γ-cyclodextrin was selected as cryoprotectant from γ-cyclodextrin, mannitol, lactose, glucose. Then the properties of raw taxifolin and taxifolin nanoparticles were characterized by

  15. Influence of Soil Moisture Conditions On The Flood Frequency Distribution: A Case Study With 10000 Years Synthetic Rainfall Series

    NASA Astrophysics Data System (ADS)

    Martina, M.; Todini, E.

    Soil moisture conditions within the catchment have a primary importance for the anal- ysis of flood risk but insufficiency of data or unavailability of measurements make them useless for operative purposes. Therefore classical simulation techniques to es- timate design flood can not consider the effects of the catchment initial soil moisture conditions. The aim of this work is to assess the influence of the soil conditions on water flow during flood event and especially on the flood frequency distribution. The proposed technique makes use of a stochastic point process, Neyman-Scott Rectan- gular Pulse, for generating a 10000 years rainfall series combined with a physically based rainfall-runoff model, TOPKAPI, for transforming rainfall into discharge and mean soil moisture conditions within the catchment. Finally the annual maximum floods have been extracted from the discharge series and their frequency distribution has been analyzed. The results have been compared with those from a traditional sim- ulation approach which uses a rainfall intensity-duration (IDF) relationship combined with the same rainfall-runoff TOPKAPI model but initialized by arbitrary soil mois- ture conditions. As it was expected the comparison shows that the influence of the soil conditions on flood frequency distribution is not negligible and gives reasonability to the methodology applied . The chosen study area is a North-Italian catchment where several years of hourly rainfall data series were available.

  16. Toxicity of DDT to Japanese quail as influenced by body weight, breeding condition, and sex

    USGS Publications Warehouse

    Gish, C.D.; Chura, N.J.

    1970-01-01

    Controlled experiments were utilized to simulate the stresses on wild birds of breeding condition and of weight loss due to migration. Light conditions in the laboratory were manipulated to produce Japanese quail (Coturnix coturnix japonica) in breeding condition and not in breeding condition. Within each of these groups, some birds were partially starved before dosage and some were fully fed. Birds were then fed dietary levels of 0, 700, 922, 1214, or 1600 ppm dry weight of p,p?-DDT for a period of 20 days or until death. Birds partially starved before dosage were more susceptible to DDT intoxication than nonstarved ones, and birds not in breeding condition were slightly more so than birds in breeding condition. Similarly, males died earlier than females, and the birds of the lighter weight strain used in the second half of the study died earlier than the birds of the heavier strain used in the first half. The heavier birds of each sex not only survived longer than lighter individuals receiving the same treatments, but they also lost a greater proportion of their weight before death. During the early portion of the dosage period, females in breeding condition were less sensitive to DDT than were females not in breeding condition and males. After 10 days on dosage, however, the cumulative mortality of females in breeding condition rapidly approached that of males and of females not in breeding condition. Food restriction prior to dosage, strains of quail, breeding conditions, and sexes resulted in weight differences and a corresponding accentuation or delay of the effects of the different levels of DDT.

  17. Boundary Behavior of Viscous Fluids: Influence of Wall Roughness and Friction-driven Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Bucur, Dorin; Feireisl, Eduard; Nečasová, Šárka

    2010-07-01

    We consider a family of solutions to the evolutionary Navier-Stokes system supplemented with the complete slip boundary conditions on domains with rough boundaries. We give a complete description of the asymptotic limit by means of Γ-convergence arguments, and identify a general class of boundary conditions.

  18. Microstimulation reveals opposing influences of prelimbic and infralimbic cortex on the expression of conditioned fear.

    PubMed

    Vidal-Gonzalez, Ivan; Vidal-Gonzalez, Benjamín; Rauch, Scott L; Quirk, Gregory J

    2006-01-01

    Recent studies using lesion, infusion, and unit-recording techniques suggest that the infralimbic (IL) subregion of medial prefrontal cortex (mPFC) is necessary for the inhibition of conditioned fear following extinction. Brief microstimulation of IL paired with conditioned tones, designed to mimic neuronal tone responses, reduces the expression of conditioned fear to the tone. In the present study we used microstimulation to investigate the role of additional mPFC subregions: the prelimbic (PL), dorsal anterior cingulate (ACd), and medial precentral (PrCm) cortices in the expression and extinction of conditioned fear. These are tone-responsive areas that have been implicated in both acquisition and extinction of conditioned fear. In contrast to IL, microstimulation of PL increased the expression of conditioned fear and prevented extinction. Microstimulation of ACd and PrCm had no effect. Under low-footshock conditions (to avoid ceiling levels of freezing), microstimulation of PL and IL had opposite effects, respectively increasing and decreasing freezing to the conditioned tone. We suggest that PL excites amygdala output and IL inhibits amygdala output, providing a mechanism for bidirectional modulation of fear expression.

  19. Estimating relative bioavailability of soil lead in the mouse.

    PubMed

    Bradham, Karen D; Green, William; Hayes, Hunter; Nelson, Clay; Alava, Pradeep; Misenheimer, John; Diamond, Gary L; Thayer, William C; Thomas, David J

    2016-01-01

    Lead (Pb) in soil is an important exposure source for children. Thus, determining bioavailability of Pb in soil is critical in evaluating risk and selecting appropriate strategies to minimize exposure. A mouse model was developed to estimate relative bioavailability of Pb in NIST SRM 2710a (Montana 1 Soil). Based on Pb levels in tissues, the mean relative bioavailability of this metal in this soil was 0.5. Estimates of relative bioavailabilities derived from mouse compared favorably with those obtained in juvenile swine. The mouse model is thus an efficient and inexpensive method to obtain estimates of relative bioavailability of soil Pb.

  20. Bioavailability Challenges Associated with Development of Anti-Cancer Phenolics

    PubMed Central

    Gao, Song; Hu, Ming

    2010-01-01

    Phenolics including many polyphenols and flavonoids have the potentials to become chemoprevention and chemotherapy agents. However, poor bioavailability limits their biological effects in vivo. This paper reviews the factors that affect phenolics absorption and their bioavailabilities from the points of view of their physicochemical properties and disposition in the gastrointestinal tract. The up-to-date research data suggested that solubility and metabolism are the primary reasons that limit phenolic aglycones’ bioavailability although stability and poor permeation may also contribute to the poor bioavailabilities of the glycosides. Future investigations should further optimize phenolics’ bioavailabilities and realize their chemopreventive and chemotherapeutic effects in vivo. PMID:20370701

  1. Bioavailability and Pharmacodynamics of Promethazine on Long Duration Missions to the International Space Station

    NASA Technical Reports Server (NTRS)

    Putcha, Lakshmi; Boyd, Jason L.; Cintron, Nitza; Berens, Kurt L.

    2004-01-01

    Space motion sickness (SMS) is often treated in space with promethazine (PMZ). Common side effects of PMZ administration (50 mg intramuscular) on the ground are drowsiness and impaired cognitive performance. Anecdotal reports indicate that these effects are absent or less pronounced in space. This suggests that the availability of PMZ to the body (bioavailability) and/or the response of the body to PMZ (pharmacodynamics) may change during space flight. Opportunities for clinical research in space are limited. The study described here is our response to a NASA Research Announcement for proposals for flight-based research needed to improve, or answer specific questions about, diagnosis and therapy during space flight, and post-flight rehabilitation. We propose here to evaluate noninvasive methods for determining the bioavailability and pharmacodynamics of PMZ. The specific objectives of the proposed research are to 1) compare pharmacokinetic and pharmacodynamic parameters of PMZ, estimated from saliva and plasma levels after administration of PMZ, 2) estimate the relative bioavailability of the three dosage forms of PMZ that are often administered to control motion sickness symptoms in space, and 3) establish the dose-response relationship of PMZ. We will estimate the bioavailability of an intramuscular injection (IM), oral tablet, and rectal suppository of PMZ in noma1 subjects during ambulatory and antiorthostatic bed rest (ABR) conditions using novel stable isotope techniques. We will compare and contrast the bioavailability of PMZ during normal and microgravity conditions to examine changes in drug absorption and bioavailability during microgravit. Results of this study will validate methods for an approved in-flight investigation with this medication awaiting an opportunity for manifestation..

  2. Thermal conditions influence changes in body temperature induced by intragastric administration of capsaicin in mice.

    PubMed

    Mori, Noriyuki; Urata, Tomomi; Fukuwatari, Tsutomu

    2016-08-01

    Capsaicin has been reported to have unique thermoregulatory actions. However, changes in core temperature after the administration of capsaicin are a controversial point. Therefore, we investigated the effects of environmental thermal conditions on changes in body temperature caused by capsaicin in mice. We showed that intragastric administration of 10 and 15 mg/kg capsaicin increased tail temperature and decreased colonic temperatures in the core temperature (CT)-constant and CT-decreasing conditions. In the CT-increasing condition, 15 mg/kg capsaicin increased tail temperature and decreased colonic temperature. However, 10 mg/kg capsaicin increased colonic temperature. Furthermore, the amount of increase in tail temperature was greater in the CT-decreasing condition and lower in the CT-increasing condition, compared with that of the CT-constant condition. These findings suggest that the changes in core temperature were affected by the environmental thermal conditions and that preliminary thermoregulation state might be more important than the constancy of temperature to evaluate the effects of heat diffusion and thermogensis.

  3. Influence of fabrication conditions on characteristics of phenanthrenequinone-doped poly(methyl methacrylate) photopolymer for holographic memory

    NASA Astrophysics Data System (ADS)

    Lin, Shiuan Huei; Cho, Sheng-Lung; Lin, June-Hua; Hsu, Ken Y.; Chi, Sien

    2014-06-01

    In this paper, we experimentally investigate the influence of the fabrication conditions on holographic characteristics in phenanthrenequinone-doped poly(methyl methacrylate) (PQ:PMMA) bulk photopolymer. In our investigation, the PQ:PMMA bulk samples are fabricated by use of a two-step thermo-polymerization method. We firstly propose to monitor relative viscosity of the monomer solution during the sample preparation to obtain a reliable criterion for material fabrication. We then compare experimentally characteristics of 2-mm thick samples fabricated with different conditions for holographic memory. The results show that the conditions in the first step play a important rule for fabricating bulk PQ:PMMA samples with good optical uniformity. In addition, the conditions in the second step play the rule for controlling the concentration of residual monomer and determine holographic characteristics. These results can provide a useful rule for fabricating bulk PQ:PMMA photopolymers for further applications on volume holographic data storage.

  4. Influences of acidic reaction and hydrolytic conditions on monosaccharide composition analysis of acidic, neutral and basic polysaccharides.

    PubMed

    Wang, Qing-Chi; Zhao, Xia; Pu, Jiang-Hua; Luan, Xiao-Hong

    2016-06-05

    Monosaccharide composition analysis is important for structural characterization of polysaccharides. To investigate the influences of acidic reaction and hydrolytic conditions on monosaccharide composition analysis of polysaccharides, we chose alginate, starch, chitosan and chondroitin sulfate as representative of acidic, neutral, basic and complex polysaccharides to compare the release degree of monosaccharides under different hydrolytic conditions. The hydrolysis stability of 10 monosaccharide standards was also explored. Results showed that the basic sugars were hard to release but stable, the acidic sugars (uronic acids) were easy to release but unstable, and the release and stability of neutral sugars were in between acidic and basic sugars. In addition, the hydrolysis process was applied to monosaccharide composition analysis of Hippocampus trimaculatus polysaccharide and the appropriate hydrolytic condition was accorded with that of the above four polysaccharides. Thus, different hydrolytic conditions should be used for the monosaccharide composition analysis of polysaccharides based on their structural characteristics.

  5. Influence of Experimental Conditions on the Outcome of Laboratory Investigations Using Natural Coastal Seawaters

    DTIC Science & Technology

    2010-01-01

    handling and storing natural coastal seawater, particularly methods for deaeration over time, influenced the chemistry and microflora . Bubbling nitrogen...or abstract) ( X ) Journal article (refereed) ( ) Oral Presentation, published ( ) Other, explain ( ) Abstract only, not...published ( ) Book chapter ( ) Conference Proceedings (not refereed) ( ) Multimedia report ) Journal article (not refereed) ) Oral

  6. Limitations on Change: Current Conditions Influencing Academic Intransigence in Educational Administration Programs.

    ERIC Educational Resources Information Center

    Logan, Connie Stokes; Pounder, Diana G.

    An analysis of academic intransigence (resistance to change) in educational administrative preparation programs is presented in this paper. Drawing upon two conceptual frameworks, the stakeholder perspective and Porter's (1980) five-force model of industry structure and competitive influence, two factors contributing to academic intransigence are…

  7. The Influence of Ground Moisture Conditions on Summertime Climate as Modeled in a GCM

    NASA Technical Reports Server (NTRS)

    Rind, D.

    1982-01-01

    To test the influence of the ground moisture on the summertime climate the GISS general circulation model is used. The version used had 8 x 10 deg horizontal resolution and 9 layers in the vertical. This version produces a good simulation of the current climate.

  8. INFLUENCE OF SUMMER TEMPERATURE SPATIAL VARIABILITY ON DISTRIBUTION AND CONDITION OF JUVENILE COHO SALMON

    EPA Science Inventory

    abstract

    Temperature during the summer months can influence the distribution, abundance and physiology of stream salmonids such as coho salmon (Oncorhynchus kisutch). Effects can be direct, via physiological responses, as well as indirect, via limited food resources, alter...

  9. University of South Carolina's Elementary Professional Development School Partnerships: Conditions Influencing Professional Development of Teachers

    ERIC Educational Resources Information Center

    Hawkins, Doris Lackey

    2010-01-01

    In education, the need to improve student achievement has been a focus of concern for several decades. Research has identified the teacher as being a powerful influence in the classroom and directly instrumental in how well students learn. The establishment of a link between teacher learning and student achievement indicates the importance of…

  10. Nitrogen sustainability and beef cattle feedyards: introduction and influence of pen surface conditions and diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Greater public awareness of the potential effects of agriculture on the environment calls for beef production systems that are sustainable with regard to the environment, society, and the economy. Reactive nitrogen (N) from feedyards could negatively influence air and water quality in the event of v...

  11. Influence of changes in initial conditions for the simulation of dynamic systems

    SciTech Connect

    Kotyrba, Martin

    2015-03-10

    Chaos theory is a field of study in mathematics, with applications in several disciplines including meteorology, sociology, physics, engineering, economics, biology, and philosophy. Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions—a paradigm popularly referred to as the butterfly effect. Small differences in initial conditions field widely diverging outcomes for such dynamical systems, rendering long-term prediction impossible in general. This happens even though these systems are deterministic, meaning that their future behavior is fully determined by their initial conditions, with no random elements involved. In this paperinfluence of changes in initial conditions will be presented for the simulation of Lorenz system.

  12. Influence of elevated ozone concentration on methanotrophic bacterial communities in soil under field condition

    NASA Astrophysics Data System (ADS)

    Huang, Y. Z.; Zhong, M.

    2015-05-01

    The open top chamber (OTC) method was used in combination with real-time quantitative PCR and terminal restriction fragment length polymorphism (T-RFLP) techniques in the wheat field to study the influence of different levels of O3 concentrations (ambient air filtered by activated carbons, 40 ppb, 80 ppb and 120 ppb) on the quantity and community structure of methanotrophic bacteria. O3 stress can influence the potential methane oxidation rate (PMOR) and potential methane production rate (PMPR) in the farmland soil. O3 treatment of 40 ppb improved significantly the 16S rRNA gene copy number in the total methanotrophic bacteria pmoA, and type I and type II methanotrophic bacteria in the soil depth of 0-20 cm. When the O3 concentration reached 120 ppb, the 16S rRNA gene copy number in the total methanotrophic bacteria pmoA and type I methanotrophic bacteria decreased significantly as compared to the control treatment in 10-20 cm layer. The 16s rRNA gene copy number of total methanotrophic bacteria pmoA and type I and type II methanotrophic bacteria were influenced by different O3 concentration and soil depth. The T-RFLP analysis indicated that O3 stress influenced significantly the community structure of the methanotrophic bacteria in soil, causing potential threat to the diversity of methanotrophic bacteria. It seems to imply that the rise of O3 concentration could produce an impact on the carbon cycling and the methane emission of the wheat field soil by changing the community structure and diversity of methanotrophic bacteria, which then influences the global climate change.

  13. Folate bioavailability: UK Food Standards Agency workshop report.

    PubMed

    Sanderson, Peter; McNulty, Helene; Mastroiacovo, Pierpaolo; McDowell, Ian F W; Melse-Boonstra, Alida; Finglas, Paul M; Gregory, Jess F

    2003-08-01

    The UK Food Standards Agency convened a group of expert scientists to review current research investigating folate bioavailability. The workshop aimed to overview current research and establish priorities for future research. Discrepancies were observed in the evidence base for folate bioavailability, especially with regard to the relative bioavailability of natural folates compared with folic acid. A substantial body of evidence shows folic acid to have superior bioavailability relative to food folates; however, the exact relative bioavailability still needs to be determined, and in particular with regard to mixed diets. The bioavailability of folate in a mixed diet is probably not a weighted average of that in the various foods consumed; thus the workshop considered that assessment of folate bioavailability of whole diets should be a high priority for future research.

  14. Social Interest and the Core Conditions: Could It Be that Adler Influenced Rogers?

    ERIC Educational Resources Information Center

    Watts, Richard E.

    1996-01-01

    Presents primary source documentation highlighting the similarities between Alfred Adler's social interest construct and the counselor-oriented core conditions of Carl Rogers. Implications of the similarities are discussed. (Author)

  15. Influence of Boundary Conditions on Simulated U.S. Air Quality

    EPA Science Inventory

    One of the key inputs to regional-scale photochemical models frequently used in air quality planning and forecasting applications are chemical boundary conditions representing background pollutant concentrations originating outside the regional modeling domain. A number of studie...

  16. [Conditioned reflex inhibition therapy for women addicted to sex under the influence of methamphetamine].

    PubMed

    Hirai, Shinji

    2010-08-01

    If behaviour which has a physiological reward is repeated, a chain of conditioned reflexes is established in the first signal system. When exposed to a signal which is connected to a particular physiological reward, the chain reaction of conditioned reflex begins and controls that behaviour. If one's thought (the second signal system conditioned reflex) tries to stop the behaviour, friction occurs between the two systems. This is experienced as a craving for the physiological reward. In several clinical cases, women who were conditioned to the physiological reward of taking methamphetamine and then having sex were examined. They succeeded in inhibiting this craving by repeatedly simulating the act of taking methamphetamine and simulating sex positions.

  17. Monitoring network-design influence on assessment of ecological condition in wadeable streams

    EPA Science Inventory

    We investigated outcomes of three monitoring networks for assessing ecological character and condition of wadeable streams in the Waikato region, New Zealand. Sites were selected 1) based on a professional judgment network, 2) within categories of stream and watershed characteris...

  18. Influence of the Tool Shoulder Contact Conditions on the Material Flow During Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Doude, Haley R.; Schneider, Judy A.; Nunes, Arthur C.

    2014-09-01

    Friction stir welding (FSWing) is a solid-state joining process of special interest in joining alloys that are traditionally difficult to fusion weld. In order to optimize the process, various numeric modeling approaches have been pursued. Of importance to furthering modeling efforts is a better understanding of the contact conditions between the workpiece and the weld tool. Both theoretical and experimental studies indicate the contact conditions between the workpiece and weld tool are unknown, possibly varying during the FSW process. To provide insight into the contact conditions, this study characterizes the material flow in the FSW nugget by embedding a lead (Pb) wire that melted at the FSWing temperature of aluminum alloy 2195. The Pb trace provided evidence of changes in material flow characteristics which were attributed to changes in the contact conditions between the weld tool and workpiece, as driven by temperature, as the tool travels the length of a weld seam.

  19. Influence of Geomagnetic and IMF conditions on High Latitude Upper Atmospheric winds and Temperatures

    NASA Astrophysics Data System (ADS)

    Dhadly, M. S.; Conde, M.; Emmert, J. T.

    2015-12-01

    We analyzed the climatological behavior of upper atmospheric winds (horizontal and vertical) and temperatures above Alaska by combining line-of-sight Doppler shifts of 630 nm optical emissions recorded during the 2011 and 2012 winters using a ground based all-sky wavelength scanning Doppler Fabry-Perot interferometer (SDI) located at Poker Flat (65.12N, 147.47W). The wide field of view covered a large geographic region above Alaska. This field was divided in software into multiple zones (115 used here), allowing independent spectra to be sampled from many directions simultaneously. As a result, it is capable of recording the wind field's spatial variations over a wide geographic region with high spatial resolution, and to resolve these variations over time. Although such climatological studies have been performed previously using satellites, models, and narrow field Fabry-Perot interferometers, there are no published climatological studies of thermospheric winds and temperatures using either SDI data or any other technique with comparable geographic coverage and resolution. Wind summary dial plots were produced to depict the climatology of the horizontal winds and temperatures for different geomagnetic conditions and orientation of interplanetary magnetic field (IMF). Results show that horizontal winds and temperatures had a strong dependence on geospace activity and orientation of IMF. The latitudinal shears in horizontal winds were stronger when geomagnetic conditions were active compared to the latitudinal shears for quiet conditions. Also, shears appeared earlier over Poker Flat when geomagnetic conditions were active. The latitudinal shears showed more dependence on IMF when geomagnetic conditions were active than they did during quieter conditions. F-region temperatures were higher under active geomagnetic conditions than during quiet conditions. They were also observed to be higher in pre-magnetic midnight sector (duskside) than they were post

  20. How habitual caffeine consumption and dose influence flavour preference conditioning with caffeine.

    PubMed

    Tinley, Elizabeth M; Durlach, Paula J; Yeomans, Martin R

    2004-09-15

    This study investigated the effects of both habitual caffeine use and dose administered in determining the ability of caffeine to reinforce conditioned changes in flavour preference. Thirty overnight-withdrawn moderate caffeine consumers and 30 non or low-dose caffeine (non/low) consumers evaluated five novel-flavoured fruit teas. Subsequently, their median-rated tea was used in four ensuing conditioning sessions. Either placebo, 1 or 2 mg/kg of caffeine (n=10 consumers, 10 non/low consumers in each condition), was added to the target tea, and all five teas were reevaluated at a final tasting. Pleasantness ratings over the four conditioning sessions indicated that non/low consumers' liking increased for the noncaffeinated fruit tea with no change for the tea containing either 1 or 2 mg/kg of caffeine. Among consumers, pleasantness ratings tended to decrease for the noncaffeinated fruit tea but increased significantly at the 1-mg dose and showed a tendency to increase at the 2-mg dose. Similar effects were shown in the evaluations made before and after conditioning, with no change in the nonexposed drinks. These results show that 1.0 mg/kg of caffeine reinforces changes in flavour pleasantness in acutely withdrawn habitual consumers but not in nonconsumers or nondependent low-caffeine consumers, further endorsing the negative-reinforcement theory of conditioning with caffeine.

  1. Influence of green waste compost on azimsulfuron dissipation and soil functions under oxic and anoxic conditions.

    PubMed

    García-Jaramillo, M; Cox, L; Hermosín, M C; Cerli, C; Kalbitz, K

    2016-04-15

    Concerns have been raised over the sustainability of intensive rice cultivation, where the use of chemical fertilizers and pesticides has been associated with numerous environmental problems. The objective of this study was to test the effect of the herbicide azimsulfuron on important soil functions as affected by amendment with a byproduct of the olive oil industry. Soil was collected from a Mediterranean rice field. Part of it was amended with alperujo compost (AC). Amended and unamended soils were incubated for 43days in presence or not of azimsulfuron, under anoxic-flooded (AF) and oxic-unflooded (OU) conditions. We monitored the dissipation of the herbicide azimsulfuron, C mineralization, soil microbial biomass (SMB) and dissolved organic carbon (DOC) content and its nature. Under AF conditions, the application of compost produced an increase in the dissipation of the herbicide (up to 12.4%). It was related with the higher DOC content, 4 times higher than under OU conditions. Though increases in carbon turnover (under AF and OU conditions) and reduction of SMBC after herbicide application (only under AF conditions) were observed, the differences were not statistically significant. The application of this organic amendment is presented as an efficient management strategy to increase C turnover in agricultural soils and reduce some of the negative effects derived from the application of azimsulfuron under flooded conditions.

  2. Varying hydric conditions during incubation influence egg water exchange and hatchling phenotype in the red-eared slider turtle.

    PubMed

    Delmas, Virginie; Bonnet, Xavier; Girondot, Marc; Prévot-Julliard, Anne-Caroline

    2008-01-01

    Environmental conditions within the nest, notably temperature and moisture of substrate, exert a powerful influence during embryogenesis in oviparous reptiles. The influence of fluctuating nest temperatures has been experimentally examined in different reptile species; however, similar experiments using moisture as the key variable are lacking. In this article, we examine the effect of various substrate moisture regimes during incubation on different traits (egg mass, incubation length, and hatchling mass) in a chelonian species with flexible-shelled eggs, the red-eared slider turtle (Trachemys scripta elegans). Our results show that the rate of water uptake by the eggs was higher in wet than in dry substrate and varied across development. More important, during the first third of development, the egg mass changes were relatively independent of the soil moisture level; they became very sensitive to moisture levels during the other two-thirds. Moreover, hydric conditions exerted a strong influence on the eggs' long-term sensitivity to the moisture of the substrate. Even short-term episodes of high or low levels of moisture modified permanently their water sensitivity, notably through modification of eggshell shape and volume, and in turn entailed significant effects on hatchling mass (and hence offspring quality). Such complex influences of fluctuating moisture levels at various incubation stages on hatchling phenotype better reflect the natural situation, compared to experiments based on stable, albeit different, moisture levels.

  3. Transport of cerium oxide nanoparticles in saturated silica media: influences of operational parameters and aqueous chemical conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaohan; Gao, Peng; Qiu, Ye; Liu, Guohong; Feng, Yujie; Wiesner, Mark

    2016-10-01

    This paper aimed to investigate the influences of operational parameters and aqueous chemical conditions on transport behaviors of cerium oxides nanoparticles (CeO2-NPs) in saturated silica media. Results indicated that increasing rates of attachment efficiency (α) were related with cationic types, and critical deposition concentration (CDC) for divalent cation (Ca2+ and Mg2+) were more than 31-fold of that for monovalent cation (Na+ and K+). Increase or reduction of electrolyte pH could both promote the mobility of CeO2-NPs in glass beads, while influence was more evident at alkaline conditions. α increased linearly with NPs concentrations, while decreased linearly with flow velocity in the column, and effects were related with electrolyte contents. Presence of surfactants could sharply decreased α, and SDS was more effective to facilitate CeO2-NPs transport than Triton X–100. With DOMs concentrations increasing, α firstly kept constant, then sharply declined, and finally reduced very slowly. The influence of DOMs on NPs deposition was in order of SA > HA > TA >  BSA. Overall, this study revealed that aqueous chemical conditions was crucial to NPs transport in porous media, and would provide significant information for our understanding on the fate and transport of nanoparticles in natural environment.

  4. Transport of cerium oxide nanoparticles in saturated silica media: influences of operational parameters and aqueous chemical conditions

    PubMed Central

    Zhang, Zhaohan; Gao, Peng; Qiu, Ye; Liu, Guohong; Feng, Yujie; Wiesner, Mark

    2016-01-01

    This paper aimed to investigate the influences of operational parameters and aqueous chemical conditions on transport behaviors of cerium oxides nanoparticles (CeO2-NPs) in saturated silica media. Results indicated that increasing rates of attachment efficiency (α) were related with cationic types, and critical deposition concentration (CDC) for divalent cation (Ca2+ and Mg2+) were more than 31-fold of that for monovalent cation (Na+ and K+). Increase or reduction of electrolyte pH could both promote the mobility of CeO2-NPs in glass beads, while influence was more evident at alkaline conditions. α increased linearly with NPs concentrations, while decreased linearly with flow velocity in the column, and effects were related with electrolyte contents. Presence of surfactants could sharply decreased α, and SDS was more effective to facilitate CeO2-NPs transport than Triton X–100. With DOMs concentrations increasing, α firstly kept constant, then sharply declined, and finally reduced very slowly. The influence of DOMs on NPs deposition was in order of SA > HA > TA >  BSA. Overall, this study revealed that aqueous chemical conditions was crucial to NPs transport in porous media, and would provide significant information for our understanding on the fate and transport of nanoparticles in natural environment. PMID:27694968

  5. Influence of Peri-Implant Soft Tissue Condition and Plaque Accumulation on Peri-Implantitis: a Systematic Review

    PubMed Central

    Poskevicius, Lukas; Juodzbalys, Gintaras; Kubilius, Ricardas; Jimbo, Ryo

    2016-01-01

    ABSTRACT Objectives To systematically examine influence of soft tissue condition and plaque accumulation around dental implants on peri-implantitis development. Material and Methods An electronic literature search was conducted of two databases - MEDLINE (Ovid) and EMBASE from 2011 to 2016. Sequential screenings at the title, abstract, and full-text levels were performed. Clinical human studies in the English language that had reported soft tissue condition or plaque accumulation influence on peri-implantitis development were included. The resulting articles were independently subjected to clear inclusion and exclusion criteria by two reviewers as follows. Results The search resulted in 8 articles meeting the inclusion criteria. These studies reported gingival index, plaque index, pocket depth, bleeding on probing/modified bleeding index for sites with “adequate” (≥ 2 mm) and “inadequate” (< 2 mm) width of keratinized mucosa. Results demonstrated that the amount of keratinized mucosa has little influence on soft-tissue inflammation in the presence of good oral hygiene. However, suboptimal oral hygiene due to difficulty in access for plaque control in the areas of minimal keratinized mucosa may lead to greater tissue damage. Conclusions In cases with insufficient keratinized gingiva in the vicinity of implants, the insufficiency does not necessarily mediate adverse effects on the hygiene management and soft tissue health condition. Nonetheless, the risk of the increase of gingival index, plaque index, pocket depth, bleeding on probing/modified bleeding index is present. Therefore, the presence of an appropriate amount of keratinized gingiva is required. PMID:27833727

  6. Effect of the boundary conditions and influence of the rotational inertia on the vibrational modes of an elastic ring.

    PubMed

    Clauvelin, Nicolas; Olson, Wilma K; Tobias, Irwin

    2014-04-01

    We present the small-amplitude vibrations of a circular elastic ring with periodic and clamped boundary conditions. We model the rod as an inextensible, isotropic, naturally straight Kirchhoff elastic rod and obtain the vibrational modes of the ring analytically for periodic boundary conditions and numerically for clamped boundary conditions. Of particular interest are the dependence of the vibrational modes on the torsional stress in the ring and the influence of the rotational inertia of the rod on the mode frequencies and amplitudes. In rescaling the Kirchhoff equations, we introduce a parameter inversely proportional to the aspect ratio of the rod. This parameter makes it possible to capture the influence of the rotational inertia of the rod. We find that the rotational inertia has a minor influence on the vibrational modes with the exception of a specific category of modes corresponding to high-frequency twisting deformations in the ring. Moreover, some of the vibrational modes over or undertwist the elastic rod depending on the imposed torsional stress in the ring.

  7. Transport of cerium oxide nanoparticles in saturated silica media: influences of operational parameters and aqueous chemical conditions.

    PubMed

    Zhang, Zhaohan; Gao, Peng; Qiu, Ye; Liu, Guohong; Feng, Yujie; Wiesner, Mark

    2016-10-03

    This paper aimed to investigate the influences of operational parameters and aqueous chemical conditions on transport behaviors of cerium oxides nanoparticles (CeO2-NPs) in saturated silica media. Results indicated that increasing rates of attachment efficiency (α) were related with cationic types, and critical deposition concentration (CDC) for divalent cation (Ca(2+) and Mg(2+)) were more than 31-fold of that for monovalent cation (Na(+) and K(+)). Increase or reduction of electrolyte pH could both promote the mobility of CeO2-NPs in glass beads, while influence was more evident at alkaline conditions. α increased linearly with NPs concentrations, while decreased linearly with flow velocity in the column, and effects were related with electrolyte contents. Presence of surfactants could sharply decreased α, and SDS was more effective to facilitate CeO2-NPs transport than Triton X-100. With DOMs concentrations increasing, α firstly kept constant, then sharply declined, and finally reduced very slowly. The influence of DOMs on NPs deposition was in order of SA > HA > TA >  BSA. Overall, this study revealed that aqueous chemical conditions was crucial to NPs transport in porous media, and would provide significant information for our understanding on the fate and transport of nanoparticles in natural environment.

  8. Bio-availability of iron from spinach (Spanicia oleracea) cultivated in soil fortified with graded levels of iron.

    PubMed

    Reddy, N S; Malewar, V G

    1992-10-01

    In vitro availability of iron along with ascorbic acid, oxalic acid and phosphorus contents of two varieties of spinach (Pusa Jyoti and Allgreen) cultivated in soil with different levels of added iron was determined. Addition of graded levels of iron to soil markedly increased the total iron and phosphorus contents and significantly decreased the bio-availability of iron, ascorbic acid and oxalic acid contents of spinach. Ascorbic acid and oxalic acid contents markedly exerted a positive influence while phosphorus exerted a negative influence on the bio-availability of iron.

  9. Influence of evisceration time and carcass ageing conditions on wild venison quality. Preliminary study.

    PubMed

    Soriano, A; Montoro, V; Vicente, J; Sánchez-Migallón, B F; Benítez, S; Utrilla, M C; García Ruiz, A

    2016-04-01

    The influence of common carcass preparation practices of wild red deer on the physicochemical, microbiological and sensory quality of venison was assessed by varying evisceration time and ageing method. Deer were head shot; half were eviscerated 30 min and the other half 4 h post mortem. In both groups (n=18), 6 carcasses were skinned immediately after evisceration and aged for 24 h; 6 were aged unskinned for 24 h and 6 were aged unskinned for 72 h at 10°C. Ageing method had a significant effect on the sensory quality of venison loin; unskinned ageing was associated with an increase of odour and taste intensity, and higher scores for gamey and sweet/caramel flavours. Carcasses aged for 72 h displayed darker and tender meat, but increased aerobic bacterial counts. Evisceration time had less influence on loin quality, although off-flavours were more often detected in deer eviscerated 4h post mortem.

  10. The Influence of Initial and Boundary Conditions on Gaseous Detonation Waves.

    DTIC Science & Technology

    1985-09-01

    Chapman - Jouguet Theory ............. 2 1.2.2 The Structure of a Detonation ...influence the detonability of a combustible imi xture. 1.2 Historical Background 1.2.1 The Discovery and Chapman - Jouguet Theory It has been more than...postulate that a UNCLASSIFIED UNCLASSIFIED 3. detonation wave consisted of a shock wave followed by a deflagration. The Chapman and Jouguet (C-J) theory

  11. The Influence of Radon (Gas and Progeny) and Weather Conditions on Ambient Dose Equivalent Rate.

    PubMed

    Márquez, J L; Benito, G; Saez, J C; Navarro, N; Alvarez, A; Quiñones, J

    2016-08-13

    The purpose of this study is to identify the influence of radon (gas and progeny) on the ambient dose equivalent rate measured at the reference station ESMERALDA, where continuous measurements of the ambient dose equivalent rate (every 10 min) combined with activity concentration measurements of radon gas and radon progeny as well as meteorological parameters have been collected. This study has been performed using a correlation study based on a principal components analysis and the Spearman's rank correlation coefficient.

  12. The Form of a Conditioned Stimulus Can Influence the Degree to Which It Acquires Incentive Motivational Properties

    PubMed Central

    Meyer, Paul J.; Cogan, Elizabeth S.; Robinson, Terry E.

    2014-01-01

    There is considerable individual variation in the extent to which food- and drug-associated cues (conditioned stimuli, CSs) acquire incentive salience, as indicated by whether they elicit approach towards them, and/or act as conditioned reinforcers. Here we asked whether this variation is influenced by properties of the CS itself. In rats, we assessed both the attractiveness and conditioned reinforcing properties of two CSs: a manipulable lever CS versus an auditory (tone) CS. There was considerable individual variation in the extent to which a lever CS acquired incentive motivational properties, as indicated by whether it became attractive (evoked a sign-tracking or goal-tracking conditioned response) or acted as a conditioned reinforcer. However, with a tone CS all rats learned a goal-tracking response, and the tone CS was an equally effective conditioned reinforcer in sign-trackers and goal-trackers. Even when presented in compound (a lever-tone CS), the two elements of the compound differentially acquired motivational properties. In contrast, amphetamine and stress potentiated the conditioned reinforcing properties of both visual and auditory CSs similarly in rats that primarily sign-tracked or goal-tracked. We conclude that variation in the to the ability of CSs to acquire incentive salience, and thus their ability to act as incentive stimuli capable of motivating behavior, is determined in part by properties of the CS itself. PMID:24905195

  13. The form of a conditioned stimulus can influence the degree to which it acquires incentive motivational properties.

    PubMed

    Meyer, Paul J; Cogan, Elizabeth S; Robinson, Terry E

    2014-01-01

    There is considerable individual variation in the extent to which food- and drug-associated cues (conditioned stimuli, CSs) acquire incentive salience, as indicated by whether they elicit approach towards them, and/or act as conditioned reinforcers. Here we asked whether this variation is influenced by properties of the CS itself. In rats, we assessed both the attractiveness and conditioned reinforcing properties of two CSs: a manipulable lever CS versus an auditory (tone) CS. There was considerable individual variation in the extent to which a lever CS acquired incentive motivational properties, as indicated by whether it became attractive (evoked a sign-tracking or goal-tracking conditioned response) or acted as a conditioned reinforcer. However, with a tone CS all rats learned a goal-tracking response, and the tone CS was an equally effective conditioned reinforcer in sign-trackers and goal-trackers. Even when presented in compound (a lever-tone CS), the two elements of the compound differentially acquired motivational properties. In contrast, amphetamine and stress potentiated the conditioned reinforcing properties of both visual and auditory CSs similarly in rats that primarily sign-tracked or goal-tracked. We conclude that variation in the to the ability of CSs to acquire incentive salience, and thus their ability to act as incentive stimuli capable of motivating behavior, is determined in part by properties of the CS itself.

  14. Experimental Study on the Influence of the Supporting Condition and Rod Motion on the Fuel Fretting Damage

    SciTech Connect

    Kim, Hyung-Kyu; Lee, Young-Ho

    2007-07-01

    Present study focuses on the influence of a supporting condition and a rod motion on a fuel fretting wear through experiments using a self-developed wear simulator, which was presented at the Water Reactor Fuel Performance Meeting, Kyoto Japan in 2005. In the experiment, a fuel rod specimen of two span lengths is vibrated by two perpendicularly aligned electromagnetic actuators. Both ends of the rod specimen are supported with a positive contact force and a variation of the supporting condition is simulated by moving each of the four grid strap specimens constituting a center grid cell. As for the supporting condition, 0.1 mm gap and 10 N force are used; a circular and a diagonal traces are applied for the rod motion. The contact shape of the spring/dimple is concave, to try and increase the contact area. Both the spring/dimple and fuel rod specimens were fabricated from the as-received materials (zirconium alloy) for a commercial fuel assembly. Experiments are carried out under a room temperature and distilled water condition. Experiment of each condition is carried out for 72 hours. Wear volume, area and depth on the cladding tubes are examined. As a result, the present concave shaped spring/dimple causes less wear when the rod moves in a circular manner than a diagonal one if there is a positive contact force (10 N). However, a diagonal motion causes more wear when a gap (0.1 mm) exists. Wear amount at the spring and dimple is influenced by the location of them and the rod motion. It is found that the wear is concentrated at the contact edges between the spring/dimple and rods due to the contact shape. The influence of the rod motion on the worn area and its shape is also discussed. (authors)

  15. The identification of orally bioavailable thrombopoietin agonists.

    PubMed

    Munchhof, Michael J; Antipas, Amy S; Blumberg, Laura C; Brissette, William H; Brown, Matthew F; Casavant, Jeffrey M; Doty, Jonathan L; Driscoll, James; Harris, Thomas M; Wolf-Gouveia, Lilli A; Jones, Christopher S; Li, Qifang; Linde, Robert G; Lira, Paul D; Marfat, Anthony; McElroy, Eric; Mitton-Fry, Mark; McCurdy, Sandra P; Reiter, Lawrence A; Ripp, Sharon L; Shavnya, Andrei; Thomasco, Lisa M; Trevena, Kristen A

    2009-03-01

    Recently, we disclosed a series of potent pyrimidine benzamide-based thrombopoietin receptor agonists. Unfortunately, the structural features required for the desired activity conferred physicochemical properties that were not favorable for the development of an oral agent. The physical properties of the series were improved by replacing the aminopyrimidinyl group with a piperidine-4-carboxylic acid moiety. The resulting compounds possessed favorable in vivo pharmacokinetic properties, including good bioavailability.

  16. Speciation and microalgal bioavailability of inorganic silver

    SciTech Connect

    Reinfelder, J.R.; Chang, S.I.

    1999-06-01

    Silver accumulation in aquatic organisms is primarily attributed to the bioavailability of the free Ag ion (Ag{sup +}). Some reports suggest that AgCl(aq) is also available for biological uptake, but few studies of Ag bioavailability used the range of chloride concentrations over which AgCl{sup 0}(aq) is the dominant Ag species. None used environmentally realistic, low Ag concentrations. To assess the bioavailability of inorganic Ag species and the importance of the low polarity AgCl(aq) complex to biological uptake, the authors determined the octanol-water partition coefficient of Ag over a range of chloride concentrations representative of fresh to brackish waters and measured short-term Ag uptake rates in the euryhaline marine microalga Thalassiosira weissflogii exposed to a total silver concentration of 50 pM. Overall octanol-water partition coefficients (D{sub ow}) of inorganic silver ranged from 0.02 to 0.06. The K{sub ow} of AgCl(aq) calculated using D{sub ow} values measured at 0.5, 5, and 50 mM Cl{sup {minus}} and the K{sub ow} of Ag{sup +} (0.03, measured in the absence of Cl{sup {minus}}) was 0.09. Silver D{sub ow} and uptake rate constants in phytoplankton were highest at the Cl{sup {minus}} concentration where uncharged AgCl(aq) is the dominant silver species. Their results demonstrate that AgCl(aq) is the principal bioavailable species of inorganic silver in phytoplankton and suggest that direct uptake of AgCl(aq) is important to the overall accumulation of Ag in aquatic invertebrates.

  17. Effect of bismuth subsalicylate on ciprofloxacin bioavailability.

    PubMed Central

    Rambout, L; Sahai, J; Gallicano, K; Oliveras, L; Garber, G

    1994-01-01

    A single oral dose of 528 mg of bismuth subsalicylate (30 ml of Pepto-Bismol) had no significant effect on the plasma pharmacokinetics of a single oral dose of 750 mg of ciprofloxacin administered to 12 healthy volunteers (six men and six women). These results suggest that ciprofloxacin bioavailability will not be significantly decreased by single doses of bismuth subsalicylate when the two medications are administered simultaneously. PMID:7811043

  18. Timing of SCH 23390 administration influences extinction of conditioned hyperactivity in mice.

    PubMed

    Rauhut, Anthony S

    2016-02-01

    The precise role of the dopamine subtype-1 (D1) receptor in differentially mediating extinction-related processes (memory retrieval vs. memory reconsolidation) in the conditioned hyperactivity paradigm is unknown. Thus, the present experiments determined the effect of a selective D1 receptor antagonist, SCH 23390, on extinction of conditioned hyperactivity when SCH 23390 was administered immediately after (memory reconsolidation; experiment 1) or before (memory retrieval; experiment 2) extinction sessions. Male, Swiss-Webster mice received subcutaneous injections of methamphetamine (1.0 mg/kg) associated with locomotor activity chambers (paired) or in their home cages (unpaired) during the acquisition phase. Following acquisition, paired and unpaired mice received an intraperitoneal injection of either vehicle (physiological saline) or SCH 23390 (0.0125, 0.025, 0.05 mg/kg) immediately after (experiment 1) or received vehicle or SCH 23390 (0.05 mg/kg) 30 min before (experiment 2), daily extinction sessions. Methamphetamine produced robust conditioned hyperactivity, followed by extinction. Furthermore, SCH 23390 (0.05 mg/kg) blocked expression of conditioned hyperactivity, without nonspecifically impairing locomotor activity, when administered before the extinction session, but did not alter the rate of extinction when administered immediately following the sessions. Taken together, these results suggest that the D1 receptor is involved in memory retrieval, but not memory reconsolidation, processes during extinction of conditioned hyperactivity.

  19. The influence of weather conditions during gestation on life histories in a wild Arctic ungulate.

    PubMed

    Douhard, Mathieu; Loe, Leif Egil; Stien, Audun; Bonenfant, Christophe; Irvine, R Justin; Veiberg, Vebjørn; Ropstad, Erik; Albon, Steve

    2016-10-26

    The internal predictive adaptive response (internal PAR) hypothesis predicts that individuals born in poor conditions should start to reproduce earlier if they are likely to have reduced performance in later life. However, whether this is the case remains unexplored in wild populations. Here, we use longitudinal data from a long-term study of Svalbard reindeer to examine age-related changes in adult female life-history responses to environmental conditions experienced in utero as indexed by rain-on-snow (ROSutero). We show that females experiencing high ROSutero had reduced reproductive success only from 7 years of age, independent of early reproduction. These individuals were able to maintain the same annual reproductive success between 2 and 6 years as phenotypically superior conspecifics that experienced low ROSutero Young females born after high ROSutero engage in reproductive events at lower body mass (about 2.5 kg less) than those born after low ROSutero The mean fitness of females that experienced poor environmental conditions in early life was comparable with that of females exposed to good environmental conditions in early life. These results are consistent with the idea of internal PAR and suggest that the life-history responses to early-life conditions can buffer the delayed effects of weather on population dynamics.

  20. Bioavailability and delivery of nutraceuticals using nanotechnology.

    PubMed

    Huang, Qingrong; Yu, Hailong; Ru, Qiaomei

    2010-01-01

    Nanotechnology is an enable technology that has the potential to revolutionize agriculture and food systems. Driven by increasing consumer demand for healthy food products, researchers have been applying tools and knowledge in nanotechnology to address the issues relevant to food and nutrition. This concise review is mainly focused on nanoemulsions and polymer micelles-based delivery systems which have shown enhanced oral bioavailability and biological efficacies (that is, antiinflammation, anti-cancer, and so on) of different phytochemicals. Nanoemulsions are a class of extremely small droplets that appear to be transparent or translucent with a bluish coloration. They are usually in the range 50 to 200 nm but much smaller than the range (from 1 to 100 mum) for conventional emulsions. Nanoemulsion preparation, characterization, and bioavailability have been discussed. Curcumin nanoemulsions show 85% inhibition of TPA-induced mouse ear inflammation as well as the inhibition of cyclin D1 expression, while dibenzoylmethane (DBM) nanoemulsion shows about 3-fold increase in oral bioavailability compared to the conventional DBM emulsion. Biopolymer micelles show significantly improved water solubility/dispersibility and in vitro anti-cancer activity of phytochemicals. More research efforts are still needed for the understanding of the potential impacts of nanoencapsulated phytochemicals on the human body and environment to address the public concerns.

  1. Bioavailability and biodistribution of nanodelivered lutein.

    PubMed

    Kamil, Alison; Smith, Donald E; Blumberg, Jeffrey B; Astete, Carlos; Sabliov, Cristina; Oliver Chen, C-Y

    2016-02-01

    The aim of the study was to evaluate the ability of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) to enhance lutein bioavailability. The bioavailability of free lutein and PLGA-NP lutein in rats was assessed by determining plasma pharmacokinetics and deposition in selected tissues. Lutein uptake and secretion was also assessed in Caco-2 cells. Compared to free lutein, PLGA-NP increased the maximal plasma concentration (Cmax) and area under the time-concentration curve in rats by 54.5- and 77.6-fold, respectively, while promoting tissue accumulation in the mesenteric fat and spleen. In comparison with micellized lutein, PLGA-NP lutein improved the Cmax in rat plasma by 15.6-fold and in selected tissues by ⩾ 3.8-fold. In contrast, PLGA-NP lutein had a lower uptake and secretion of lutein in Caco-2 cells by 10.0- and 50.5-fold, respectively, compared to micellized lutein. In conclusion, delivery of lutein with polymeric NP may be an approach to improve the bioavailability of lutein in vivo.

  2. Rapid screening assay for calcium bioavailability studies

    SciTech Connect

    Luhrsen, K.R.; Hudepohl, G.R.; Smith, K.T.

    1986-03-01

    Calcium bioavailability has been studied by numerous techniques. The authors report here the use of the gamma emitting isotope of calcium (/sup 47/Ca) in a whole body retention assay system. In this system, calcium sources are administered by oral gavage and subsequent counts are determined and corrected for isotopic decay. Unlike iron and zinc retention curves, which exhibit a 2-3 day equilibration period, calcium reaches equilibration after 24 hours. Autoradiographic analysis of the femurs indicate that the newly absorbed calcium is rapidly distributed to the skeletal system. Moreover, the isotope is distributed along the entire bone. Comparisons of calcium bioavailability were made using intrinsic/extrinsic labeled milk from two species i.e. rat and goat as well as CaCO/sub 3/. In addition, extrinsic labeled cow milk was examined. In the rat, the extrinsic labeled calcium from milk was better absorbed than the intrinsic calcium. This was not the case in goat milk or the calcium carbonate which exhibited no significant differences. Chromatographic analysis of the labeled milk indicates a difference in distribution of the /sup 47/Ca. From these data, the authors recommend the use of this assay system in calcium bioavailability studies. The labeling studies and comparisons indicate caution should be used, however, in labeling techniques and species milk comparison.

  3. Selenium in soybeans: bioavailability and form

    SciTech Connect

    Mason, A.C.

    1984-01-01

    Experiments are presented which evaluate the bioavailability of different forms of selenium from intrinsically and extrinsically labeled isolated soy protein and soy flour. The bioavailability of selenium from soy and egg is compared and some characteristics of selenium are described as it exists in soybeans. The metabolism of selenium was measured by whole-body and tissue radioactivity retention and selenium excretion. Selenium-75 was well absorbed from an isolated soy protein diet by rats. Selenium-75 from isolated soy protein labeled intrinsically and extrinsically with /sup 75/Se selenate was better absorbed than from protein labeled extrinsically with /sup 75/Se selenite or /sup 75/Se selenomethionine. Bioavailability of selenium from soy flour and egg was measured by whole-body and tissue radioactivity retention and glutathione peroxidase (GSH-Px) activity regeneration. Selenium-75 from soy flour intrinsically labeled with selenite was better absorbed than /sup 75/Se from flour intrinsically labeled with selenate. GSH-Px levels in the liver, kidney, platelets and heart fell when rats were fed a selenium deficient diet, but were not significantly raised on 0.0825 ppm Se repletion diets.

  4. Lycopene from heat-induced cis-isomer-rich tomato sauce is more bioavailable than from all-trans-rich tomato sauce in human subjects.

    PubMed

    Unlu, Nuray Z; Bohn, Torsten; Francis, David M; Nagaraja, Haikady N; Clinton, Steven K; Schwartz, Steven J

    2007-07-01

    Lycopene is present mainly as cis-isomers in human serum and tissues whereas all-trans-lycopene predominates in tomato products, suggesting that all-trans-lycopene is isomerised in the body or is less bioavailable. The objectives of the present study were to develop processing conditions for tomatoes to obtain products with different cis-trans-lycopene isomer distribution and to assess their bioavailability. Healthy adult subjects (n 12) were recruited for this randomised cross-over trial. Each intervention was preceded by a 2-week washout period. Two tomato sauces, one rich in all-trans-lycopene (32.5 mg total lycopene/100 g sauce; 5 % cis-isomers), the other high in cis-lycopene (26.4 mg total lycopene/100 g sauce; 45 % cis-isomers), were produced by different heat-processing techniques. Each sauce (150 g) was served in a standardised meal at 08.00 hours after overnight fasting. Plasma TAG-rich lipoprotein fractions over 9.5 h following test-meal consumption as a measure of lycopene absorption were obtained and expressed as baseline-corrected area under the concentration v. time curves (AUC), using HPLC-electrochemical detection. AUC values adjusted for the amount lycopene consumed showed that total, total cis-, and all-trans-lycopene responses were significantly higher from the cis-isomer-rich sauce, compared with the all-trans-rich sauce, being 7.30 (sem 1.45) v. 4.74 (sem 1.08) nmol x h/l (P = 0.002), 3.80 (sem 0.76) v. 1.98 (sem 0.37) nmol x h/l (P = 0.0005) and 3.50 (sem 0.76) v. 2.76 (sem 0.76) nmol x h/l (P = 0.01), respectively. The present study demonstrates significant lycopene bioavailability from cis-lycopene-rich tomato sauce and highlights the importance of considering isomer-distribution for lycopene bioavailability. Furthermore, processing parameters can be controlled to alter isomer patterns of tomato products and influence lycopene bioavailability.

  5. Influence of sedentary versus physically active conditions on regulation of plasma renin activity and vasopressin.

    PubMed

    Mueller, Patrick J

    2008-09-01

    Physical inactivity is an independent risk factor for cardiovascular disease. Sedentary animals compared to physically active controls exhibit enhanced sympathoexcitatory responses, including arterial baroreflex-mediated sympathoexcitation. Hypotension-induced sympathoexcitation is also associated with the release of vasoactive hormones. We hypothesized that sedentary conditions may enhance release of the vasoactive hormones AVP and ANG II. To test this hypothesis, the humoral response to hypotension was examined in conscious rats after 9-12 wk of sedentary conditions or "normally active" conditions. Normally active conditions were produced by allowing rats access to running wheels in their home cages. Running distance peaked after 4 wk (4.5 +/- 0.7 km/day), and the total distance run after 9 wk was 174 +/- 23 km (n = 25). Similar levels of hypotension were induced in conscious sedentary or physically active animals with the arterial vasodilator, diazoxide (25 mg/kg iv). Control experiments used a saline injection of equivalent volume. Plasma samples were collected and assayed for plasma AVP concentration and plasma renin activity (PRA). Sedentary conditions significantly enhanced resting and hypotension-induced PRA relative to normal physical activity. In contrast, resting and hypotension-induced AVP levels were not statistically different between groups. These data suggest that baroreflex-mediated activation of the renin-angiotensin system, but not AVP secretion, is enhanced by sedentary conditions. We speculate that augmented activation of the renin-angiotensin system may be related to enhanced sympathetic outflow observed in sedentary animals and may contribute to increased risk of cardiovascular disease in the sedentary population.

  6. Influence of culture conditions on growth and protective antigenicity of Clostridium chauvoei.

    PubMed

    Cortiñas, T I; Micalizzi, B; de Guzman, A M

    1994-10-01

    The effect of culture conditions on growth and immunogenicity of Clostridium chauvoei were examined. The pH control and partial feeding of the carbon source at high concentrations were beneficial for growth. The biomass yield was significatively improved, however the butanol concentration reached toxic levels hampering further growth. For each experimental condition the immunogenicity of cells was tested. No differences were found with cells obtained at different temperatures, but it decreased significatively with the partial supply of the carbon source and pH control.

  7. The Influence of Sporulation Conditions on the Spore Coat Protein Composition of Bacillus subtilis Spores

    PubMed Central

    Abhyankar, Wishwas R.; Kamphorst, Kiki; Swarge, Bhagyashree N.; van Veen, Henk; van der Wel, Nicole N.; Brul, Stanley; de Koster, Chris G.; de Koning, Leo J.

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence. 14N spores prepared on solid Schaeffer’s-glucose (SG) agar plates and 15N metabolically labeled spores prepared in shake flasks containing 3-(N-morpholino) propane sulfonic acid (MOPS) buffered defined liquid medium differ in their coat protein composition as revealed by LC-FT-MS/MS analyses. The former condition mimics the industrial settings while the latter conditions mimic the routine laboratory environment wherein spores are developed. As seen previously in many studies, the spores prepared on the solid agar plates show a higher thermal resistance than the spores prepared under liquid culture conditions. The 14N:15N isotopic ratio of the 1:1 mixture of the spore suspensions exposes that most of the identified inner coat and crust proteins are significantly more abundant while most of the outer coat proteins are significantly less abundant for the spores prepared on solid SG agar plates relative to the spores prepared in the liquid MOPS buffered defined medium. Sporulation condition-specific differences and variation in isotopic ratios between the tryptic peptides of expected cross-linked proteins suggest that the coat protein cross-linking may also be condition specific. Since the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the

  8. The influences of iron characteristics, operating conditions and solution chemistry on contaminants removal by zero-valent iron: A review.

    PubMed

    Sun, Yuankui; Li, Jinxiang; Huang, Tinglin; Guan, Xiaohong

    2016-09-01

    For successful application of a zero-valent iron (ZVI) system, of particular interest is the performance of ZVI under various conditions. The current review comprehensively summarizes the potential effects of the major influencing factors, such as iron intrinsic characteristics (e.g., surface area, iron impurities and oxide films), operating conditions (e.g., pH, dissolved oxygen, iron dosage, iron pretreatment, mixing conditions and temperature) and solution chemistry (e.g., anions, cations and natural organic matter) on the performance of ZVI reported in literature. It was demonstrated that all of the factors could exert significant effects on the ZVI performance toward contaminants removal, negatively or positively. Depending on the removal mechanisms of the respective contaminants and other environmental conditions, an individual variable may exhibit different effects. On the other hand, many of these influences have not been well understood or cannot be individually isolated in experimental or natural systems. Thus, more research is required in order to elucidate the exact roles and mechanisms of each factor in affecting the performance of ZVI. Furthermore, based on these understandings, future research may attempt to establish some feasible strategies to minimize the deteriorating effects and utilize the positive effects so as to improve the performance of ZVI.

  9. Heavy metals in soils from Baia Mare mining impacted area (Romania) and their bioavailability

    NASA Astrophysics Data System (ADS)

    Roba, Carmen; Baciu, Calin; Rosu, Cristina; Pistea, Ioana; Ozunu, Alexandru

    2015-04-01

    Keywords: heavy metals, soil contamination, bioavailability, Romania The fate of various metals, including chromium, nickel, copper, manganese, mercury, cadmium, and lead, and metalloids, like arsenic, antimony, and selenium, in the natural environment is of great concern, particularly in the vicinity of former mining sites, dumps, tailings piles, and impoundments, but also in urban areas and industrial centres. Most of the studies focused on the heavy metal pollution in mining areas present only the total amounts of metals in soils. The bioavailable concentration of metals in soil may be a better predictor for environmental impact of historical and current dispersion of metals. Assessment of the metal bioavailability and bioaccessibility is critical in understanding the possible effects on soil biota. The bioavailability of metals in soil and their retention in the solid phase of soil is affected by different parameters like pH, metal amount, cation-exchange capacity, content of organic matter, or soil mineralogy. The main objectives of the present study were to determine the total fraction and the bioavailable fraction of Cu, Cd, Pb and Zn from soil in a well-known mining region in Romania, and to evaluate the influence of soil pH on the metal bioavailability in soil. The heavy metal contents and their bioavailability were monitored in a total of 50 soil samples, collected during June and July 2014 from private gardens of the inhabitants from Baia-Mare area. The main mining activities developed in the area consisted of non-ferrous sulphidic ores extraction and processing, aiming to obtain concentrates of lead, copper, zinc and precious metals. After 2006, the metallurgical industry has considerably reduced its activity by closing or diminishing its production capacity. The analysed soil samples proved to have high levels of Pb (50 - 830 mg/kg), Cu (40 - 600 mg/kg), Zn (100 - 700 mg/kg) and Cd (up to 10 mg/kg). The metal abundance in the total fraction is

  10. The impact of sediment bioturbation by secondary organisms on metal bioavailability, bioaccumulation and toxicity to target organisms in benthic bioassays: Implications for sediment quality assessment.

    PubMed

    Remaili, Timothy M; Simpson, Stuart L; Amato, Elvio D; Spadaro, David A; Jarolimek, Chad V; Jolley, Dianne F

    2016-01-01

    Bioturbation alters the properties of sediments and modifies contaminant bioavailability to benthic organisms. These naturally occurring disturbances are seldom considered during the assessment of sediment quality. We investigated how the presence (High bioturbation) and absence (Low bioturbation) of a strongly bioturbating amphipod within three different sediments influenced metal bioavailability, survival and bioaccumulation of metals to the bivalve Tellina deltoidalis. The concentrations of dissolved copper decreased and manganese increased with increased bioturbation. For copper a strong correlation was observed between increased bivalve survival (53-100%) and dissolved concentrations in the overlying water. Increased bioturbation intensity resulted in greater tissue concentrations for chromium and zinc in some test sediments. Overall, the results highlight the strong influence that the natural bioturbation activities from one organism may have on the risk contaminants pose to other organisms within the local environment. The characterisation of field-based exposure conditions concerning the biotic or abiotic resuspension of sediments and the rate of attenuation of released contaminants through dilution or readsorption may enable laboratory-based bioassay designs to be adapted to better match those of the assessed environment.

  11. Thiol-Based Selective Extraction Assay to Comparatively Assess Bioavailable Mercury in Sediments

    PubMed Central

    Ticknor, Jonathan L.; Kucharzyk, Katarzyna H.; Porter, Kaitlyn A.; Deshusses, Marc A.; Hsu-Kim, Heileen

    2015-01-01

    Abstract Bioaccumulation of methylmercury in the aquatic food web is governed in part by the methylation of inorganic divalent mercury (Hg(II)) by anaerobic microorganisms. In sulfidic settings, a small fraction of total Hg(II) is typically bioavailable to methylating microorganisms. Quantification of this fraction is difficult due to uncertainties in the speciation of Hg(II) and the mechanisms of uptake by methylating microbes. However, recent studies have shown that the bioavailable fraction is likely to include a portion of Hg(II) associated with solid phases, that is, nanostructured mercuric sulfides. Moreover, addition of thiols to suspensions of methylating cultures coincides with increased uptake into cells and methylmercury production. Here, we present a thiol-based selective extraction assay to provide information on the bioavailable Hg fraction in sediments. In the procedure, sediment samples were exposed to a nitrogen-purged solution of glutathione (GSH) for 30 min and the amount of GSH-leachable mercury was quantified. In nine sediment samples from a marine location, the relative GSH-leachable mercury concentration was strongly correlated to the relative amount of methylmercury in the sediments (r2=0.91, p<0.0001) across an order of magnitude of methylmercury concentration values. The approach was further applied to anaerobic sediment slurry microcosm experiments in which sediments were cultured under the same microbial growth conditions but were amended with multiple forms of Hg with a known spectrum of bioavailability. GSH-leachable Hg concentrations increased with observed methylmercury concentrations in the microcosms, matching the trend of species bioavailability in our previous work. Results suggest that a thiol-based selective leaching approach is an improvement compared with other proposed methods to assess Hg bioavailability in sediment and that this approach could provide a basis for comparison of sites where Hg methylation is a concern

  12. Influence of varying focus of attention conditions on dart throwing performance in experts and novices.

    PubMed

    Schorer, J; Jaitner, T; Wollny, R; Fath, F; Baker, J

    2012-03-01

    Research suggests an external focus of attention positively affects motor learning more than an internal focus; however, little research has considered this relationship in motor control situations. The present study examined the role of varying focus of attention conditions on dart throwing performance. Experts (n = 6) and novices (n = 6) performed 84 throws under two internal and one external conditions and in the presence and absence of knowledge of results (KR). Results indicated clear differences between experts and novices on both performance and motor control outcomes. Further, there was some evidence that movement execution was slowed in experts but not in novices, although results were somewhat inconclusive. Our analyses suggest that varying focus of attention affects temporal parameters of movement execution in experts but not spatial parameters. Interestingly, both experts and novices generally perceived all instruction conditions to be hindrances to performance, with the exception of the external focus with KR condition. Further work is necessary to determine the extent to which these results apply to other open and closed skills.

  13. Influence of harvester and weather conditions on field loss and milling quality of rough rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A better understanding of factors affecting field losses and milling quality during harvest is needed to improve the economic value of rice. The main objective of this study was to evaluate the impact of harvester header, harvester type, and weather conditions on field loss and milling quality of ro...

  14. Keeping Older Adults with Vision Loss Safe: Chronic Conditions and Comorbidities that Influence Functional Mobility

    ERIC Educational Resources Information Center

    Riddering, Anne T.

    2008-01-01

    Age-related macular degeneration (AMD) is a leading cause of vision loss in Americans aged 60 and older. The loss of central vision from AMD can decrease visual acuity, contrast sensitivity, glare sensitivity, color discrimination, and the ability to adapt to changes in lighting conditions. Older adults with vision loss often have other chronic,…

  15. The Influence of Conditional Cash Transfers on Eligible Children and Their Siblings

    ERIC Educational Resources Information Center

    Lincove, Jane Arnold; Parker, Adam

    2016-01-01

    Conditional cash transfers (CCTs) are used to reduce poverty while incentivizing investments in children. Targeting CCTs to certain groups of children can improve efficiency, but positive effects on eligible children may be offset by reductions in investments for ineligible siblings. Using data from Nicaragua, we estimate program effects on…

  16. Identity of cofactor bound to mycothiol conjugate amidase (Mca) influenced by expression and purification conditions.

    PubMed

    Kocabas, Evren; Liu, Hualan; Hernick, Marcy

    2015-08-01

    Mycothiol serves as the primary reducing agent in Mycobacterium species, and is also a cofactor for the detoxification of xenobiotics. Mycothiol conjugate amidase (Mca) is a metalloamidase that catalyzes the cleavage of MS-conjugates to form a mercapturic acid, which is excreted from the mycobacterium, and 1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside. Herein we report on the metal cofactor preferences of Mca from Mycobacterium smegmatis and Mycobacterium tuberculosis. Importantly, results from homology models of Mca from M. smegmatis and M. tuberculosis suggest that the metal binding site of Mca is identical to that of the closely related protein N-acetyl-1-D-myo-inosityl-2-amino-2-deoxy-α-D-glucopyranoside deacetylase (MshB). This finding is supported by results from zinc ion affinity measurements that indicate Mca and MshB have comparable K(D)(ZnII) values (~10-20 pM). Furthermore, results from pull-down experiments using Halo-Mca indicate that Mca purifies with (stoichiometric) Fe(2+) when purified under anaerobic conditions, and Zn(2+) when purified under aerobic conditions. Consequently, Mca is likely a Fe(2+)-dependent enzyme under physiological conditions; with Zn(2+)-Mca an experimental artifact that could become biologically relevant under oxidatively stressed conditions. Importantly, these findings suggest that efforts towards the design of Mca inhibitors should include targeting the Fe(2+) form of the enzyme.

  17. Interstimulus Interval and Delivery Cues Influence Timed Conditioned Responding in Rats

    ERIC Educational Resources Information Center

    Williams, Douglas A.; Chubala, Chrissy M.; Mather, Amber A.; Johns, Kenneth W.

    2009-01-01

    Appetitive contextual excitation supported by intertrial unconditioned stimuli was more easily overcome by timed conditioned responding in rats using quiet (Experiment 1) rather than noisy (Experiment 2) food pellet deliveries. Head-entry responding in acquisition peaked above the contextual baseline when pellet delivery occurred 10, 30, 60, or 90…

  18. Influence of operating conditions on the air gasification of dry refinery sludge in updraft gasifier

    NASA Astrophysics Data System (ADS)

    Ahmed, R.; Sinnathambi, C. M.

    2013-06-01

    In the present work, details of the equilibrium modeling of dry refinery sludge (DRS) are presented using ASPEN PLUS Simulator in updraft gasifier. Due to lack of available information in the open journal on refinery sludge gasification using updraft gasifier, an evaluate for its optimum conditions on gasification is presented in this paper. For this purpose a Taguchi Orthogonal array design, statistical software is applied to find optimum conditions for DRS gasification. The goal is to identify the most significant process variable in DRS gasification conditions. The process variables include; oxidation zone temperature, equivalent ratio, operating pressure will be simulated and examined. Attention was focused on the effect of optimum operating conditions on the gas composition of H2 and CO (desirable) and CO2 (undesirable) in terms of mass fraction. From our results and finding it can be concluded that the syngas (H2 & CO) yield in term of mass fraction favors high oxidation zone temperature and at atmospheric pressure while CO2 acid gas favor at a high level of equivalent ratio as well as air flow rate favoring towards complete combustion.

  19. The influence of simulator input conditions on the wear of total knee replacements: An experimental and computational study

    PubMed Central

    Brockett, Claire L; Abdelgaied, Abdellatif; Haythornthwaite, Tony; Hardaker, Catherine; Fisher, John; Jennings, Louise M

    2016-01-01

    Advancements in knee replacement design, material and sterilisation processes have provided improved clinical results. However, surface wear of the polyethylene leading to osteolysis is still considered the longer-term risk factor. Experimental wear simulation is an established method for evaluating the wear performance of total joint replacements. The aim of this study was to investigate the influence of simulation input conditions, specifically input kinematic magnitudes, waveforms and directions of motion and position of the femoral centre of rotation, on the wear performance of a fixed-bearing total knee replacement through a combined experimental and computational approach. Studies were completed using conventional and moderately cross-linked polyethylene to determine whether the influence of these simulation input conditions varied with material. The position of the femoral centre of rotation and the input kinematics were shown to have a significant influence on the wear rates. Similar trends were shown for both the conventional and moderately cross-linked polyethylene materials, although lower wear rates were found for the moderately cross-linked polyethylene due to the higher level of cross-linking. The most important factor influencing the wear was the position of the relative contact point at the femoral component and tibial insert interface. This was dependent on the combination of input displacement magnitudes, waveforms, direction of motion and femoral centre of rotation. This study provides further evidence that in order to study variables such as design and material in total knee replacement, it is important to carefully control knee simulation conditions. This can be more effectively achieved through the use of displacement control simulation. PMID:27160561

  20. Various conditioning methods for root canals influencing the tensile strength of titanium posts.

    PubMed

    Schmage, P; Sohn, J; Nergiz, I; Ozcan, M

    2004-09-01

    Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufacturers' instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute Aplicap, Flexi-Flow cem, Panavia 21 EX, Twinlook) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer's recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 degrees C for 24 h and then thermocycled (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0.5 mm min(-1). The data were analysed statistically using anova and corrected with Scheffé test due to the significance levels (P < 0.05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 +/- 78 N) followed in descending order by Panavia 21 EX (442 +/- 97 N), Twinlook (430 +/- 78 N) and Compolute Aplicap (352 +/- 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 +/- 77 N) (P < 0.001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 +/- 102 N

  1. Novel synthesis of copper nanoparticles: influence of the synthesis conditions on the particle size

    NASA Astrophysics Data System (ADS)

    Zhu, Haitao; Zhang, Canying; Yin, Yansheng

    2005-12-01

    This paper presents a novel method for the preparation of copper nanoparticles by reducing CuSO4 with hydrazine in ethylene glycol under microwave irradiation. The influences of reaction parameters such as molar ratios of N2H4·H2O /CuSO4 and NaOH/CuSO4, heating method and reaction temperature on the particle size and composition of powder were investigated by x-ray diffractometry (XRD), transmission electron microscopy (TEM) and particle size analysis. Well-dispersed copper nanopowder with a diameter of about 15 nm was obtained in the absence of a protective polymer.

  2. Influence of Composition and Deformation Conditions on the Strength and Brittleness of Shale Rock

    NASA Astrophysics Data System (ADS)

    Rybacki, E.; Reinicke, A.; Meier, T.; Makasi, M.; Dresen, G. H.

    2015-12-01

    Stimulation of shale gas reservoirs by hydraulic fracturing operations aims to increase the production rate by increasing the rock surface connected to the borehole. Prospective shales are often believed to display high strength and brittleness to decrease the breakdown pressure required to (re-) initiate a fracture as well as slow healing of natural and hydraulically induced fractures to increase the lifetime of the fracture network. Laboratory deformation tests were performed on several, mainly European black shales with different mineralogical composition, porosity and maturity at ambient and elevated pressures and temperatures. Mechanical properties such as compressive strength and elastic moduli strongly depend on shale composition, porosity, water content, structural anisotropy, and on pressure (P) and temperature (T) conditions, but less on strain rate. We observed a transition from brittle to semibrittle deformation at high P-T conditions, in particular for high porosity shales. At given P-T conditions, the variation of compressive strength and Young's modulus with composition can be roughly estimated from the volumetric proportion of all components including organic matter and pores. We determined also brittleness index values based on pre-failure deformation behavior, Young's modulus and bulk composition. At low P-T conditions, where samples showed pronounced post-failure weakening, brittleness may be empirically estimated from bulk composition or Young's modulus. Similar to strength, at given P-T conditions, brittleness depends on the fraction of all components and not the amount of a specific component, e.g. clays, alone. Beside strength and brittleness, knowledge of the long term creep properties of shales is required to estimate in-situ stress anisotropy and the healing of (propped) hydraulic fractures.

  3. High Arctic sea ice conditions influence marine birds wintering in Low Arctic regions

    NASA Astrophysics Data System (ADS)

    McFarlane Tranquilla, Laura; Hedd, April; Burke, Chantelle; Montevecchi, William A.; Regular, Paul M.; Robertson, Gregory J.; Stapleton, Leslie Ann; Wilhelm, Sabina I.; Fifield, David A.; Buren, Alejandro D.

    2010-09-01

    Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird "wrecks" (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres ( Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2-3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region.

  4. Influence of in-tunnel environment to in-bus air quality and thermal condition in Hong Kong.

    PubMed

    Mui, K W; Shek, K W

    2005-07-15

    In this study, the potential exposure of bus commuters to significant air parameters (CO(2), CO and RSP) and thermal environment (air temperature and relative humidity) when buses traveled through tunnels in Hong Kong was investigated. It was found that air-conditioned buses provided a better commuting environment than non-air-conditioned buses. The blate increasing trend was found on air-conditioned buses as the in-bus air parameters concentration levels rose slowly throughout the traveling process. In contrast, the in-bus environment varied rapidly on non-air-conditioned buses as it depended on the out-bus environment. The measured in-bus CO concentration was 2.9 ppm on air-conditioned buses, while it was 4.6 ppm (even reaching the highest level at 12.0 ppm) on non-air-conditioned buses. Considering the in-bus thermal environment, air-conditioned buses provided thermally comfortable cabins (about 24 degrees C and 59% of relative humidity). However, on non-air-conditioned buses, the thermal environment varied with the out-bus environment. The mean in-bus air temperature was about 34 degrees C and 66% of relative humidity, and the in-bus air temperature varied between 29 and 38 degrees C. Also, the lower-deck to upper-deck air parameters concentration ratios indicated that the vertical dispersion of air pollutants in tunnels influenced non-air-conditioned buses as higher air parameters concentration levels were obtained on the lower-deck cabins.

  5. The influence of diet on nestling body condition of an apex predator: a multi-biomarker approach.

    PubMed

    Resano-Mayor, Jaime; Hernández-Matías, Antonio; Real, Joan; Parés, Francesc; Moleón, Marcos; Mateo, Rafael; Ortiz-Santaliestra, Manuel E

    2016-04-01

    Animal body condition refers to the health and physiological state of individuals, and multiple parameters have been proposed to quantify this key concept. Food intake is one of the main determinants of individual body condition and much debate has been generated on how diet relates to body condition. We investigated this relationship in free-living Bonelli's eagle (Aquila fasciata) nestlings sampled at two geographically distant populations in Spain. Nestlings' main prey consumption was estimated by isotopic analyses. A multi-biomarker approach, including morphometric and blood biochemical measures (i.e. hematocrit, plasma biochemistry and oxidative stress biomarkers), enabled us to integrate all the body condition measures taken. A greater consumption of a preferred prey [i.e. the European rabbit (Oryctolagus cuniculus)] improved nestling body condition, as indicated by lower levels of cholesterol in plasma, greater activity of enzymes mediating in protein catabolism, higher levels of tocopherol and glutathione, and less glutathione peroxidase activity, which also suggested lower degree of oxidative stress. On the other hand, increased diet diversity was positively correlated with higher levels of oxidized glutathione, which suggests that these nestlings had poorer body condition than those with a higher frequency of preferred prey consumption. Several factors other than diet [i.e. altitude of nesting areas, nestling sex and age, sampling time (before or after midday) and recent food ingestion] had an effect on certain body condition measures. Our study reveals a measurable effect of diet on a predator's body condition and demonstrates the importance of considering the potential influence of multiple intrinsic and extrinsic factors when assessing animal body condition.

  6. The influence of early-life conditions on cardiovascular disease later in life among ethnic minority populations: a systematic review.

    PubMed

    Bijker, Rimke; Agyemang, Charles

    2016-04-01

    Ethnic minority groups are disproportionately affected by cardiovascular diseases (CVDs). The reasons for the high prevalence of CVD in ethnic minority groups are not fully understood. Recently, the importance of early-life developmental factors and their impact on CVDs in adulthood is increasingly being recognised, but little is known about this among ethnic minority groups. Therefore, the current paper aimed to fill this knowledge gap by reviewing the available literature to assess the influence of early-life conditions on CVDs and its risk factors in ethnic minority populations residing in Western countries. A systematic search was performed in PubMed and EMBASE between 1989 and 2014. In total, 1418 studies were identified of which 19 met the inclusion criteria. Six studies investigated the relationship between early-life anthropometrics and CVD risk factors of which all except one found significant associations between the assessed anthropometric measures and CVD risk factors. Seven studies evaluated the influence of childhood socio-economic status (SES) on CVD and risk factors of which five found significant associations between childhood SES measures and CVD risk factors. Five studies investigated the relationship between other early-life conditions including early-life nutrition, physical development, and childhood psychosocial conditions, and CVD risk factors. Four of these studies found significant associations between the assessed childhood conditions and CVD risk factors. This review reinforces the importance of early-life conditions on adult CVD in ethnic minority groups. Improvement of early-life conditions among ethnic minority groups may contribute to reducing CVD risk in these populations.

  7. The influence of wheel/rail contact conditions on the microstructure and hardness of railway wheels.

    PubMed

    Molyneux-Berry, Paul; Davis, Claire; Bevan, Adam

    2014-01-01

    The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an "in-service" wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

  8. Strengthening and toughening mechanisms in low-c microalloyed martensitic steel as influenced by austenite conditioning

    NASA Astrophysics Data System (ADS)

    Kennett, Shane C.

    Three low-carbon ASTM A514 microalloyed steels were used to assess the effects of austenite conditioning on the microstructure and mechanical properties of martensite. A range of prior austenite grain sizes with and without thermomechanical processing were produced in a Gleeble RTM 3500 and direct-quenched. Samples in the as-quenched, low temperature tempered, and high temperature tempered conditions were studied. The microstructure was characterized with scanning electron microscopy, electron backscattered diffraction, transmission electron microscopy, and x-ray diffraction. The uniaxial tensile properties and Charpy V-notch properties were measured and compared with the microstructural features (prior austenite grain size, packet size, block size, lath boundaries, and dislocation density). For the equiaxed prior austenite grain conditions, prior austenite grain size refinement decreases the packet size, decreases the block size, and increases the dislocation density of as-quenched martensite. However, after high temperature tempering the dislocation density decreases with prior austenite grain size refinement. Thermomechanical processing increases the low angle substructure, increases the dislocation density, and decreases the block size of as-quenched martensite. The dislocation density increase and block size refinement is sensitive to the austenite grain size before ausforming. The larger prior austenite grain size conditions have a larger increase in dislocation density, but the small prior austenite grain size conditions have the largest refinement in block size. Additionally, for the large prior austenite grain size conditions, the packet size increases with thermomechanical processing. The strength of martensite is often related to an effective grain size or carbon concentration. For the current work, it was concluded that the strength of martensite is primarily controlled by the dislocation density and dislocation substructure; which is related to a grain

  9. Enhancement of oral bioavailability of an HIV-attachment inhibitor by nanosizing and amorphous formulation approaches.

    PubMed

    Fakes, Michael G; Vakkalagadda, Blisse J; Qian, Feng; Desikan, Sridhar; Gandhi, Rajesh B; Lai, Chiajen; Hsieh, Alice; Franchini, Miriam K; Toale, Helen; Brown, Jonathan

    2009-03-31

    BMS-488043 is an HIV-attachment inhibitor that exhibited suboptimal oral bioavailability upon using conventional dosage forms prepared utilizing micronized crystalline drug substance. BMS-488043 is classified as a Biopharmaceutics Classification System (BCS) Class-II compound with a poor aqueous solubility of 0.04mg/mL and an acceptable permeability of 178nm/s in the Caco2 cell-line model. Two strategies were evaluated to potentially enhance the oral bioavailability of BMS-488043. The first strategy targeted particle size reduction through nanosizing the crystalline drug substance. The second strategy aimed at altering the drug's physical form by producing an amorphous drug. Both strategies provided an enhancement in oral bioavailability in dogs as compared to a conventional formulation containing the micronized crystalline drug substance. BMS-488043 oral bioavailability enhancement was approximately 5- and 9-folds for nanosizing and amorphous formulation approaches, respectively. The stability of the amorphous coprecipitated drug prepared at different compositions of BMS-488043/polyvinylpyrrolidone (PVP) was evaluated upon exposure to stressed stability conditions of temperature and humidity. The drastic effect of exposure to humidity on conversion of the amorphous drug to crystalline form was observed. Additionally, the dissolution behavior of coprecipitated drug was evaluated under discriminatory conditions of different pH values to optimize the BMS-488043/PVP composition and produce a stabilized, amorphous BMS-488043/PVP (40/60, w/w) spray-dried intermediate (SDI), which was formulated into an oral dosage form for further development and evaluation.

  10. Flux influence on membrane fouling in a membrane bioreactor system under real conditions with urban wastewater.

    PubMed

    Poyatos, Jose M; Molina-Munoz, Marisa; Delgado, Fernando; Gonzalez-Lopez, Jesus; Hontoria, Ernesto

    2008-12-01

    In order to evaluate the effect of flux on membrane fouling, the performance of a bench-scale submerged membrane bioreactor (MBR) equipped with ultrafiltration membranes (ZENON) was investigated under real conditions at different flux rates. The pilot plant was located at the wastewater treatment plant of the city of Granada (Spain). Influent used in the experiments came from the primary settling tank. Assays carried out under different operating conditions indicated that dTMP/dt increased in accordance with the increase in flux. The results showed a significant impact on the rate of transmembrane pressure, while the behavior of membrane fouling was logarithmic with respect to the flux. These findings could be of some importance for understanding the behavior of the membrane, since over 20.57 L m(-2) h(-1) the flux rate produced a significant increase in transmembrane pressure. The data therefore suggest that an increase in the net flux significantly affects membrane fouling.

  11. The Influence of Crowding Conditions on the Thermodynamic Feasibility of Metabolic Pathways.

    PubMed

    Angeles-Martinez, Liliana; Theodoropoulos, Constantinos

    2015-12-01

    Intracellular reactions are carried out in a crowded medium where the macromolecules occupy ∼40% of the total volume. This decrease in the available volume affects the activity of the reactants. Scaled particle theory is used for the estimation of the activity coefficients of the metabolites, and thereby for the assessment of the impact of the presence of background molecules, on the estimation of the Gibbs free energy change (ΔrG) of the reactions. The lactic acid pathway and the central carbon metabolism of Actinobacillus succinogenes for the production of succinic acid from glycerol have been used as illustrative case studies. Results suggest the importance of maintaining intracellular crowded regions to favor the feasibility of a pathway that in other circumstances would be infeasible. Moreover, the crowding conditions may change the directionality of reactions and can modify the feasible range of fluxes estimated for a metabolic system compared with those obtained at standard biological conditions.

  12. Influence of Extreme Storage Conditions on Extra Virgin Olive Oil Parameters: Traceability Study

    PubMed Central

    Escudero, Alfredo; Pacheco, Rafael

    2016-01-01

    This study reflects the effect of extreme storage conditions on several extra virgin olive oil (EVOO) varieties (arbequina, hojiblanca, and picual). The conditions were simulated in the laboratory, by means of heating treatments in stove at different temperatures (40 and 60°C) and times (two and three weeks). The aim is the evaluation of the deterioration of the quality parameters and minority components, which are responsible for the nutritional and therapeutic properties (fatty acids, polyphenols, pigments, and tocopherols), and organoleptic qualities. The quality criteria and limits used in this work are according to International Olive Council. The results contribute to the control of the traSceability for the commercialization of the EVOO. PMID:28042493

  13. The Influence of Crowding Conditions on the Thermodynamic Feasibility of Metabolic Pathways

    PubMed Central

    Angeles-Martinez, Liliana; Theodoropoulos, Constantinos

    2015-01-01

    Intracellular reactions are carried out in a crowded medium where the macromolecules occupy ∼40% of the total volume. This decrease in the available volume affects the activity of the reactants. Scaled particle theory is used for the estimation of the activity coefficients of the metabolites, and thereby for the assessment of the impact of the presence of background molecules, on the estimation of the Gibbs free energy change (ΔrG) of the reactions. The lactic acid pathway and the central carbon metabolism of Actinobacillus succinogenes for the production of succinic acid from glycerol have been used as illustrative case studies. Results suggest the importance of maintaining intracellular crowded regions to favor the feasibility of a pathway that in other circumstances would be infeasible. Moreover, the crowding conditions may change the directionality of reactions and can modify the feasible range of fluxes estimated for a metabolic system compared with those obtained at standard biological conditions. PMID:26636950

  14. Influence of fermentation conditions on specific activity of the enzymes alcohol and aldehyde dehydrogenase from yeasts.

    PubMed

    Mauricio, J C; Ortega, J M

    1993-01-01

    The effects of anaerobic, semi-aerobic and short aeration fermentation conditions and the addition of ergosterol and oleic acid to musts on the specific activity of alcohol and aldehyde dehydrogenase (ADH and ALDH) from two yeast species, Saccharomyces cerevisiae and Torulaspora delbrueckii, were studied. ADH I biosynthesis only occurred during the first few hours of fermentation. ADH II from S. cerevisiae and ALDH-NADP+ from the two yeast species behaved as constitutive enzymes under all fermentation conditions. ADH II from T. delbrueckii was only synthesized in small amounts, and its activity was always lower than in S. cerevisiae, where it was responsible for the termination of alcoholic fermentation during the steady growth phase.

  15. A bridging technique to analyze the influence of boundary conditions on instability patterns

    SciTech Connect

    Hu Heng; Damil, Noureddine; Potier-Ferry, Michel

    2011-05-10

    In this paper, we present a new numerical technique that permits to analyse the effect of boundary conditions on the appearance of instability patterns. Envelope equations of Landau-Ginzburg type are classically used to predict pattern formation, but it is not easy to associate boundary conditions for these macroscopic models. Indeed, envelope equations ignore boundary layers that can be important, for instance in cases where the instability starts first near the boundary. In this work, the full model is considered close to the boundary, an envelope equation in the core and they are bridged by the Arlequin method . Simulation results are presented for the problem of buckling of long beams lying on a non-linear elastic foundation.

  16. Influence of dissolved oxygen conditions on toxicity of ammonium nitrate to larval natterjack toads.

    PubMed

    Ortiz-Santaliestra, Manuel E; Marco, Adolfo

    2015-07-01

    Temporary ponds, where many amphibians from temperate regions breed, show an annual cycle with a maximum water volume in spring followed by a progressive desiccation throughout late spring and summer. This desiccation leads to a decrease in dissolved oxygen and an increase in nitrogen levels, which can additionally increase because of anthropogenic sources such as chemical fertilizers. We analyzed the toxicity posed by environmentally relevant levels of a common nitrogenous fertilizer, ammonium nitrate, at different conditions of oxygen availability to Bufo calamita tadpoles, which typically develop in ephemeral ponds. Ammonium nitrate (90.3 mg N-NO3NH4/l) and hypoxic conditions (initial dissolved oxygen 4.53 ± 0.40 mg/l) caused significant lethal effects after 7 and 12 days of exposure, respectively. At the end of experiment (16 days), mortality rates were 32.5 % in individuals exposed to the fertilizer and 15 % in those growing under hypoxic conditions. When both stressors were combined, they showed an additive effect on tadpole survival. Malformations, such as oedemas and spinal curvatures, and locomotory abnormalities, were detected after 12 days of experiment in >90 % of individuals exposed to 45.2 mg N-NO3NH4/l under hypoxic conditions, whereas none of these stressors by separate related to abnormality rates >35 %. Delayed development was also observed in tadpoles exposed to ammonium nitrate with hypoxia affecting developmental rate only after 12 days of exposure. The results are discussed in terms of potential mechanisms linking negative effects of both factors as well as in terms of potential alterations of the ecological plasticity that often allows amphibians to survive in unpredictable environments.