Science.gov

Sample records for active phenoloxidase po

  1. PO-CALC: a novel tool to correct common inconsistencies in the measurement of phenoloxidase activity.

    PubMed

    Kohlmeier, Philip; Dreyer, Heiko; Meunier, Joël

    2015-04-01

    A broad range of physiological and evolutionarily studies requires standard and robust methods to assess the strength and activity of an individual's immune defense. In insects, this goal is generally reached by spectrophotometrically measuring (pro-) phenoloxidase activity, an enzymatic and non-specific process activated after wounding and parasite infections. However, the literature surprisingly lacks a standard method to calculate these values from spectrophotometer data and thus to be able to compare results across studies. In this study, we demonstrated that nine methods commonly used to extract phenoloxidase activities (1) provide inconsistent results when tested on the same data sets, at least partly due to their specific sensitivity to the noise regularly present in enzymatic reaction curves. To circumvent this issue, we then (2) developed a novel, free and simple R-based program called PO-CALC and (3) demonstrated the robustness of its calculations for the different types of noises. Overall, we show that PO-CALC corrects overlooked though important inconsistencies in the measurement of phenoloxidase activities, and claim that its broad use would increase the significance and general validity of studies on invertebrate immunity. PMID:25783957

  2. Effect of different K+ concentrations on Cryptococcus neoformans phenoloxidase activity.

    PubMed

    Vidotto, Valerio; Defina, Nicola; Pugliese, Agostino; Aoki, Shigeji; Nakamura, Kenjrou; Takeo, Kanjj

    2002-01-01

    Melanin synthesis in Cryptococcus neoformans, catalyzed by phenoloxidase activity, is one of the oldest virulence factors known. However, until now, the relationship between melanin production in C. neoformans and its virulence has been poorly understood. Among different chemical compounds only Fe3+ and Cu2+ cations enhance the phenoloxidase activity in C. neoformans. A few reports in the literature describe the influence of different cations on C. neoformans phenoloxidase activity, excluding iron. In this study, 13 C. neoformans strains isolated from AIDS patients and 7 from bird droppings (B.D.), were examined in order to clarify the effect of different K+ concentrations on phenoloxidase activity. A new solid and liquid caffeic acid minimal synthetic medium (MSM-CAF) containing only caffeic acid and ferric citrate with different potassium concentrations was used to evaluate C. neoformans phenoloxidase activity. In the MSM-CAF solid medium the degree of brown pigmentation on the agar plates was read on days 1, 2 and 3 of incubation, and the pigmentation of the C. neoformans strains was classed into 5 categories. The brown pigment of the liquid MSM-CAF test tubes were checked after 24 hours of incubation by measuring the optical density (O.D.) at 480 nm. Three C. neoformans AIDS and B.D. strains, randomly chosen, were tested for phenoloxidase activity, according to the modified protocols of Polacheck et al., Torres-Guerrero et al. and Rhodes. According to the results obtained, it has been observed that K+ does not activate the phenoloxidase activity in the C. neoformans AIDS and B.D. strains. In particular, with an increase in potassium concentrations in the MSM-CAF solid and liquid medium, there was a corresponding inhibition of the phenoloxidase activity on both the C. neoformans AIDS and B.D. strains. PMID:12749580

  3. Phenoloxidase activity in larval and juvenile homogenates and adult plasma and haemocytes of bivalve molluscs.

    PubMed

    Luna-González, Antonio; Maeda-Martínez, Alfonso N; Vargas-Albores, Francisco; Ascencio-Valle, Felipe; Robles-Mungaray, Miguel

    2003-10-01

    Phenoloxidase (PO) activity was studied in larval and juvenile homogenates and in the plasma and haemocytes of adult Crassostrea gigas, Argopecten ventricosus, Nodipecten subnodosus, and Atrina maura. Samples were tested for the presence of PO activity by incubation with the substrate L-3, 4-dihydroxyphenylalanine using trypsin, alpha-chymotrypsin, laminarin, lipopolysaccharides (LPS), and sodium dodecyl sulphate (SDS) to elicit activation of prophenoloxidase (proPO) system. PO activity was not detected in larval homogenate. In juvenile homogenate, PO activity was found only in C. gigas and N. subnodosus. PO activity was present in adult samples and was enhanced by elicitors in the plasma of all species tested, but in haemocyte lysate supernatant (HLS) of only N. subnodosus. Activation of proPO by laminarin was suppressed by a protease inhibitor cocktail (P-2714) in plasma and HLS of all species tested.

  4. No Effect of Host Species on Phenoloxidase Activity in a Mycophagous Beetle

    PubMed Central

    Formica, Vincent; Chan, Amanda Kar-Men

    2015-01-01

    Ecological immunology is an interdisciplinary field that helps elucidate interactions between the environment and immune response. The host species individuals experience have profound effects on immune response in many species of insects. However, this conclusion comes from studies of herbivorous insects even though species of mycophagous insects also inhabit many different host species. The goal of this study was to determine if fungal host species as well as individual, sex, body size, and host patch predict one aspect of immune function, phenoloxidase activity (PO). We sampled a metapopulation of Bolitotherus cornutus, a mycophagous beetle in southwestern Virginia. B. cornutus live on three species of fungus that differ in nutritional quality, social environment, and density. A filter paper phenoloxidase assay was used to quantify phenoloxidase activity. Overall, PO activity was significantly repeatable among individuals (0.57) in adult B. cornutus. While there was significant variance among individuals in PO activity, there were surprisingly no significant differences in PO activity among subpopulations, beetles living on different host species, or between the sexes; there was also no effect of body size. Our results suggest that other factors such as age, genotype, disease prevalence, or natal environment may be generating variance among individuals in PO activity. PMID:26513243

  5. No Effect of Host Species on Phenoloxidase Activity in a Mycophagous Beetle.

    PubMed

    Formica, Vincent; Chan, Amanda Kar-Men

    2015-01-01

    Ecological immunology is an interdisciplinary field that helps elucidate interactions between the environment and immune response. The host species individuals experience have profound effects on immune response in many species of insects. However, this conclusion comes from studies of herbivorous insects even though species of mycophagous insects also inhabit many different host species. The goal of this study was to determine if fungal host species as well as individual, sex, body size, and host patch predict one aspect of immune function, phenoloxidase activity (PO). We sampled a metapopulation of Bolitotherus cornutus, a mycophagous beetle in southwestern Virginia. B. cornutus live on three species of fungus that differ in nutritional quality, social environment, and density. A filter paper phenoloxidase assay was used to quantify phenoloxidase activity. Overall, PO activity was significantly repeatable among individuals (0.57) in adult B. cornutus. While there was significant variance among individuals in PO activity, there were surprisingly no significant differences in PO activity among subpopulations, beetles living on different host species, or between the sexes; there was also no effect of body size. Our results suggest that other factors such as age, genotype, disease prevalence, or natal environment may be generating variance among individuals in PO activity. PMID:26513243

  6. Lipoprotein-induced phenoloxidase-activity in tarantula hemocyanin.

    PubMed

    Schenk, Sven; Schmidt, Juliane; Hoeger, Ulrich; Decker, Heinz

    2015-08-01

    Phenoloxidases play vital roles in invertebrate innate immune reactions, wound closure and sclerotization processes in arthropods. In chelicerates, where phenoloxidases are lacking, phenoloxidase-activity can be induced in the oxygen carrier hemocyanin in vitro by proteolytic cleavage, incubation with the artificial inducer SDS, or lipids. The role of protein-protein interaction has up to now received little attention. This is remarkable, as lipoproteins - complexes of proteins and lipids - are present at high concentrations in arthropod hemolymph. We characterized the three lipoproteins present in tarantula hemolymph, two high-density lipoproteins and one very high-density lipoprotein, and show that the two high-density lipoproteins have distinct structures: the more abundant high-density lipoprotein is an ellipsoid particle with axes of ~22.5 nm and ~16.8 nm, respectively. The second high-density lipoprotein, present only in trace amount, is a large discoidal lipoprotein with a diameter of ~38.4 nm and an on-edge thickness of ~7.1 nm. We further demonstrate that the interaction between lipoproteins and hemocyanin induces phenoloxidase activity in hemocyanin, and propose that this activation is due to protein-protein interaction rather than protein-lipid interaction, as neither lipid micelles nor lipid monomers were found to be activating. Activation was strongest in the presence of high-density lipoproteins; very high-density lipoproteins were found to be non-activating. This is the first time that the ability of lipoproteins to induce phenoloxidase activity of hemocyanin has been demonstrated, thus adding novel aspects to the function of lipoproteins apart from their known role in nutrient supply. PMID:25817204

  7. Phenoloxidase activity in the infraorder Isoptera: unraveling life-history correlates of immune investment.

    PubMed

    Rosengaus, Rebeca B; Reichheld, Jennifer L

    2016-02-01

    Within the area of ecological immunology, the quantification of phenoloxidase (PO) activity has been used as a proxy for estimating immune investment. Because termites have unique life-history traits and significant inter-specific differences exist regarding their nesting and foraging habits, comparative studies on PO activity can shed light on the general principles influencing immune investment against the backdrop of sociality, reproductive potential, and gender. We quantified PO activity across four termite species ranging from the phylogenetically basal to the most derived, each with their particular nesting/foraging strategies. Our data indicate that PO activity varies across species, with soil-dwelling termites exhibiting significantly higher PO levels than the above-ground wood nester species which in turn have higher PO levels than arboreal species. Moreover, our comparative approach suggests that pathogenic risks can override reproductive potential as a more important driver of immune investment. No gender-based differences in PO activities were recorded. Although termite PO activity levels vary in accordance with a priori predictions made from life-history theory, our data indicate that nesting and foraging strategies (and their resulting pathogenic pressures) can supersede reproductive potential and other life-history traits in influencing investment in PO. Termites, within the eusocial insects, provide a unique perspective for inferring how different ecological pressures may have influenced immune function in general and their levels of PO activity, in particular.

  8. Phenoloxidase activity in the infraorder Isoptera: unraveling life-history correlates of immune investment

    NASA Astrophysics Data System (ADS)

    Rosengaus, Rebeca B.; Reichheld, Jennifer L.

    2016-02-01

    Within the area of ecological immunology, the quantification of phenoloxidase (PO) activity has been used as a proxy for estimating immune investment. Because termites have unique life-history traits and significant inter-specific differences exist regarding their nesting and foraging habits, comparative studies on PO activity can shed light on the general principles influencing immune investment against the backdrop of sociality, reproductive potential, and gender. We quantified PO activity across four termite species ranging from the phylogenetically basal to the most derived, each with their particular nesting/foraging strategies. Our data indicate that PO activity varies across species, with soil-dwelling termites exhibiting significantly higher PO levels than the above-ground wood nester species which in turn have higher PO levels than arboreal species. Moreover, our comparative approach suggests that pathogenic risks can override reproductive potential as a more important driver of immune investment. No gender-based differences in PO activities were recorded. Although termite PO activity levels vary in accordance with a priori predictions made from life-history theory, our data indicate that nesting and foraging strategies (and their resulting pathogenic pressures) can supersede reproductive potential and other life-history traits in influencing investment in PO. Termites, within the eusocial insects, provide a unique perspective for inferring how different ecological pressures may have influenced immune function in general and their levels of PO activity, in particular.

  9. Phenoloxidase activity in the infraorder Isoptera: unraveling life-history correlates of immune investment.

    PubMed

    Rosengaus, Rebeca B; Reichheld, Jennifer L

    2016-02-01

    Within the area of ecological immunology, the quantification of phenoloxidase (PO) activity has been used as a proxy for estimating immune investment. Because termites have unique life-history traits and significant inter-specific differences exist regarding their nesting and foraging habits, comparative studies on PO activity can shed light on the general principles influencing immune investment against the backdrop of sociality, reproductive potential, and gender. We quantified PO activity across four termite species ranging from the phylogenetically basal to the most derived, each with their particular nesting/foraging strategies. Our data indicate that PO activity varies across species, with soil-dwelling termites exhibiting significantly higher PO levels than the above-ground wood nester species which in turn have higher PO levels than arboreal species. Moreover, our comparative approach suggests that pathogenic risks can override reproductive potential as a more important driver of immune investment. No gender-based differences in PO activities were recorded. Although termite PO activity levels vary in accordance with a priori predictions made from life-history theory, our data indicate that nesting and foraging strategies (and their resulting pathogenic pressures) can supersede reproductive potential and other life-history traits in influencing investment in PO. Termites, within the eusocial insects, provide a unique perspective for inferring how different ecological pressures may have influenced immune function in general and their levels of PO activity, in particular. PMID:26838762

  10. The roles of serine protease, intracellular and extracellular phenoloxidase in activation of prophenoloxidase system, and characterization of phenoloxidase from shrimp haemocytes induced by lipopolysaccharide or dopamine

    NASA Astrophysics Data System (ADS)

    Xie, Peng; Pan, Luqing; Xu, Wujie; Yue, Feng

    2013-09-01

    We investigated the effects of lipopolysaccharide (LPS) and dopamine (DA) on the activation of the prophenoloxidase (proPO) system of Litopenaeus vannamei. LPS and DA were shown with a negative dose-dependent effect on hyalne cells (HC), semi-granular cells (SGC), large granular cells (LGC), and total haemocyte count (THC). When haemocytes were treated with LPS or DA, serine proteinase activity and intracellular phenoloxidase (PO) activity were significantly reduced, but extracellular PO activity increased significantly. These findings indicated that the reduction in haemocyte counts was mainly because of the degranulation and activation of the proPO system from semi-granule and large granule cells. The PKC inhibitor, chelerythrine, and the TPK inhibitor, genistein, had an inhibitory effect on extracellular PO activity, while serine proteinase and intracellular PO activity increased. This suggests that the LPS and DA induce the activation of proPO in haemocytes via PKC and TPK-related signaling pathways, but serine proteinase may be activated only by PKC, as the genistein effects were not statistically significant. Electrophoresis analysis revealed that POs induced by LPS or DA have the same molecular mass and high diphenolase activity. Two PO bands at 526 kDa and 272 kDa were observed in PAGE, while in the haemocyte lysate supernatant (HLS), only a 272-kDa band was observed. This band was resolved after SDS-PAGE under non-reducing and reducing conditions into two groups of POs, 166 kDa and 126 kDa, and 78.1 kDa and 73.6 kDa, respectively, suggesting that PO in L. vannamei is an oligomer, which may have different compositions intra- and extracellularly.

  11. Production of diagnostic pigment by phenoloxidase activity of cryptococcus neoformans.

    PubMed

    Shaw, C E; Kapica, L

    1972-11-01

    Cryptococcus neoformans produces brown pigmented colonies when grown on agar media made from an extract of potatoes and carrots, broad beans (Vicia faba), or Guizotia abyssinica seeds. Since other yeasts do not produce the pigment, these media are useful as differential isolation media for C. neoformans. Similar specific pigment was produced by C. neoformans on chemically defined agar media which contained six different substrates of phenoloxidase (o-diphenol: oxygen oxidoreductase EC 1.10.3.1) an enzyme which catalyses the oxidation of o-diphenols to melanin. Substrates were incorporated singly into the media and included L-3, 4-dihydroxyphenylalanine (L-DOPA), chlorogenic acid, protocatechuic acid, catechol, norepinephrine, and 3-hydroxytyramine hydrochloride (dopamine). No pigment was produced on media without substrate. Phenoloxidase activity in (NH(4))(2)SO(4) precipitates of C. neoformans cell-free extract was assayed by measuring increases in absorbance at 480 nm produced in solutions of L-DOPA. This reaction showed oxygen uptake and was effectively inhibited by copper chelators, but not by catalase. The enzyme also oxidized the five other substrates which induced pigment formation. Electron micrographs of cells incubated in L-DOPA showed deposition of the pigment in the cell wall. PMID:4118328

  12. Ant sperm storage organs do not have phenoloxidase constitutive immune activity.

    PubMed

    Dávila, Francisco; Chérasse, Sarah; Boomsma, Jacobus J; Aron, Serge

    2015-07-01

    The prophenoloxidase system (proPO-AS) is a primordial constituent of insect innate immunity. Its broad action spectrum, rapid response time, and cytotoxic by-products induced by phenoloxidase (PO) production contribute to the effective clearing of invading pathogens. However, such immune reactions may not be optimal for insect organs that evolved to have mutualistic interactions with non-self-cells. Ant queens are long-lived, but only mate early in adult life and store the sperm in a specialized organ, the spermatheca. They never re-mate so their life-time reproductive success is ultimately sperm-limited, which maintains strong selection for high sperm viability before and after storage. The proPO-AS may therefore be inappropriate for the selective clearing of sexually transmitted infections, as it might also target sperm cells that cannot be replaced. We measured PO enzymatic activity in the sperm storage organs of three ant species before and after mating. Our data show that no PO is produced in the sperm storage organs, relative to other somatic tissues as controls, and that these negative results are not due to non-detection in small volumes as non-immune-relevant catalase activity in single spermatheca fluid samples of both virgin and mated queens was significant. The lack of PO activity in sperm storage organs across three different ant species may represent an evolutionarily conserved adaptation to life-long sperm storage by ant queens. We expect that PO activity will be similarly suppressed in queen spermathecae of other eusocial Hymenoptera (bees and wasps) and, more generally, of insect females that store sperm for long periods. PMID:25911976

  13. Ant sperm storage organs do not have phenoloxidase constitutive immune activity.

    PubMed

    Dávila, Francisco; Chérasse, Sarah; Boomsma, Jacobus J; Aron, Serge

    2015-07-01

    The prophenoloxidase system (proPO-AS) is a primordial constituent of insect innate immunity. Its broad action spectrum, rapid response time, and cytotoxic by-products induced by phenoloxidase (PO) production contribute to the effective clearing of invading pathogens. However, such immune reactions may not be optimal for insect organs that evolved to have mutualistic interactions with non-self-cells. Ant queens are long-lived, but only mate early in adult life and store the sperm in a specialized organ, the spermatheca. They never re-mate so their life-time reproductive success is ultimately sperm-limited, which maintains strong selection for high sperm viability before and after storage. The proPO-AS may therefore be inappropriate for the selective clearing of sexually transmitted infections, as it might also target sperm cells that cannot be replaced. We measured PO enzymatic activity in the sperm storage organs of three ant species before and after mating. Our data show that no PO is produced in the sperm storage organs, relative to other somatic tissues as controls, and that these negative results are not due to non-detection in small volumes as non-immune-relevant catalase activity in single spermatheca fluid samples of both virgin and mated queens was significant. The lack of PO activity in sperm storage organs across three different ant species may represent an evolutionarily conserved adaptation to life-long sperm storage by ant queens. We expect that PO activity will be similarly suppressed in queen spermathecae of other eusocial Hymenoptera (bees and wasps) and, more generally, of insect females that store sperm for long periods.

  14. Characterization of the circulating hemocytes in mud crab (Scylla olivacea) revealed phenoloxidase activity.

    PubMed

    Mangkalanan, Seksan; Sanguanrat, Piyachat; Utairangsri, Tanatchaporn; Sritunyalucksana, Kallaya; Krittanai, Chartchai

    2014-05-01

    This study focused on an isolation and characterization of the circulating hemocytes in mud crab, Scylla olivacea. Isolation of specific cell types of hemocytes from crab hemolymph was accomplished by using 60% Percoll density gradient centrifugation. Four separated bands of the hemocytes were successfully obtained. Characterization of these isolated hemocytes by light microscope using trypan blue-rose bengal staining, rose bengal-hematoxilin staining, and phase contrast revealed four distinct types of hemocyte cells. Using their specific morphology and granularity, they were identified as hyaline cell (HC), small granular cell (SGC), large granular cell (LGC) and mixed granular cell (MGC). Transmission electron microscopy (TEM) revealed more details on specific cell size, size of cytoplasmic granule, and nuclear to cytoplasmic ratio, and confirmed the classification. Relative abundance of these cells types in the hemolymph of an adult crab were 15.50±8.22% for HC, 55.50±7.15% for SGC, 13.50±5.28% for LGC, and 15.50±3.50% for MGC. Proteomic analysis of protein expression for each specific cell types by two-dimensional electrophoresis identified two highly abundant proteins, prophenoloxidase (ProPO) and peroxinectin in LGC. Determination of phenoloxidase (PO) activity in each isolated cell types using in vitro and in situ chemical assays confirmed the presence of PO activity only in LGC. Based on an increased PO activity of crab hemolymph during the course of White Spot Syndrome Virus (WSSV) infection, these results suggest that prophenoloxidase pathway was employed for host defense mechanism against WSSV and it may link to the role of large granular hemocyte.

  15. A masquerade-like serine proteinase homologue is necessary for phenoloxidase activity in the coleopteran insect, Holotrichia diomphalia larvae.

    PubMed

    Kwon, T H; Kim, M S; Choi, H W; Joo, C H; Cho, M Y; Lee, B L

    2000-10-01

    Previously, we reported the molecular cloning of cDNA for the prophenoloxidase activating factor-I (PPAF-I) that encoded a member of the serine proteinase group with a disulfide-knotted motif at the N-terminus and a trypsin-like catalytic domain at the C-terminus [Lee, S.Y., Cho, M.Y., Hyun, J.H., Lee, K.M., Homma, K.I., Natori, S. , Kawabata, S.I., Iwanaga, S. & Lee, B.L. (1998) Eur. J. Biochem. 257, 615-621]. PPAF-I is directly involved in the activation of pro-phenoloxidase (pro-PO) by limited proteolysis and the overall structure is highly similar to that of Drosophila easter serine protease, an essential serine protease zymogen for pattern formation in normal embryonic development. Here, we report purification and molecular cloning of cDNA for another 45-kDa novel PPAF from the hemocyte lysate of Holotrichia diomphalia larvae. The gene encodes a serine proteinase homologue consisting of 415 amino-acid residues with a molecular mass of 45 256 Da. The overall structure of the 45-kDa protein is similar to that of masquerade, a serine proteinase homologue expressed during embryogenesis, larval, and pupal development in Drosophila melanogaster. The 45-kDa protein contained a trypsin-like serine proteinase domain at the C-terminus, except for the substitution of Ser of the active site triad to Gly and had a disulfide-knotted domain at the N-terminus. A highly similar 45-kDa serine proteinase homologue was also cloned from the larval cDNA library of another coleopteran, Tenebrio molitor. By in vitro reconstitution experiments, we found that the purified 45-kDa serine proteinase homologue, the purified active PPAF-I and the purified pro-PO were necessary for expressing phenoloxidase activity in the Holotrichia pro-PO system. However, incubation of pro-PO with either PPAF-I or 45-kDa protein, no phenoloxidase activity was observed. Interestingly, when the 45-kDa protein was incubated with PPAF-I and pro-PO in the absence, but not in the presence of Ca2+, the 45-k

  16. Induction of phenoloxidase and other immunological activities in the humoral fluids of amphioxus Branchiostoma belcheri challenged with Lipopolysaccharide (LPS).

    PubMed

    Pang, Qiuxiang; Liu, Xuemei; Zhao, Bosheng; Sun, Huanhuan

    2012-12-01

    The knowledge concerning the humoral immunity is scarce in amphioxus Branchiostoma belcheri. This study measured the humoral parameters including phenoloxidase (PO) activity, lysozyme activity, antimicrobial activity, microbial agglutinin, and hemagglutinin in amphioxus humoral fluids before and after lipopolysaccharide (LPS) challenge. Humoral fluids from unchallenged Branchiostoma belcheri (B. belcheri) had PO activity, lysozyme, antimicrobial, microbial agglutinating, and hemagglutinating activities, which may represent part of the baseline level of innate immunity in this organism. After challenge with LPS, many humoral parameters were all increased significantly including the PO activity, lysozyme activity, growth-inhibiting activities against Gram-negative bacteria Escherichia coli (E. coli) and Vibrio alginolyticus (V. alginolyticus), growth-inhibiting activities against Gram-positive bacteria Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis), microbial agglutinating activities against Micrococcus lysodeikticus (M. lysodeikticus), B. subtilis, and S. aureus, and hemagglutinating activities against rabbit and human A and O erythrocytes. In contrast, the agglutinating activities against V. harveyi and E. coli and the hemagglutinating activity against human B erythrocytes in the humoral fluids were reduced in response to LPS challenge. It appears that the humoral fluids of B. belcheri contain components that are able to differentiate different microbes and different human blood cell types. PMID:22733094

  17. A putative link between phagocytosis-induced apoptosis and hemocyanin-derived phenoloxidase activation.

    PubMed

    Coates, Christopher J; Whalley, Tim; Wyman, Michael; Nairn, Jacqueline

    2013-11-01

    Apoptosis and phagocytosis are crucial processes required for developmental morphogenesis, pathogen deterrence and immunomodulation in metazoans. We present data showing that amebocytes of the chelicerate, Limulus polyphemus, undergo phagocytosis-induced cell death after ingesting spores of the fungus, Beauveria bassiana, in vitro. The observed biochemical and morphological modifications associated with dying amebocytes are congruent with the hallmarks of apoptosis, including: extracellularisation of phosphatidylserine, intranucleosomal DNA fragmentation and an increase in caspase 3/7-like activities. Previous studies have demonstrated that phosphatidylserine is a putative endogenous activator of hemocyanin-derived phenoloxidase, inducing conformational changes that permit phenolic substrate access to the active site. Here, we observed extracellular hemocyanin-derived phenoloxidase activity levels increase in the presence of apoptotic amebocytes. Enzyme activity induced by phosphatidylserine or apoptotic amebocytes was reduced completely upon incubation with the phosphatidylserine binding protein, annexin V. We propose that phosphatidylserine redistributed to the outer plasma membrane of amebocytes undergoing phagocytosis-induced apoptosis could interact with hemocyanin, thus facilitating its conversion into a phenoloxidase-like enzyme, during immune challenge. PMID:23925540

  18. A putative link between phagocytosis-induced apoptosis and hemocyanin-derived phenoloxidase activation.

    PubMed

    Coates, Christopher J; Whalley, Tim; Wyman, Michael; Nairn, Jacqueline

    2013-11-01

    Apoptosis and phagocytosis are crucial processes required for developmental morphogenesis, pathogen deterrence and immunomodulation in metazoans. We present data showing that amebocytes of the chelicerate, Limulus polyphemus, undergo phagocytosis-induced cell death after ingesting spores of the fungus, Beauveria bassiana, in vitro. The observed biochemical and morphological modifications associated with dying amebocytes are congruent with the hallmarks of apoptosis, including: extracellularisation of phosphatidylserine, intranucleosomal DNA fragmentation and an increase in caspase 3/7-like activities. Previous studies have demonstrated that phosphatidylserine is a putative endogenous activator of hemocyanin-derived phenoloxidase, inducing conformational changes that permit phenolic substrate access to the active site. Here, we observed extracellular hemocyanin-derived phenoloxidase activity levels increase in the presence of apoptotic amebocytes. Enzyme activity induced by phosphatidylserine or apoptotic amebocytes was reduced completely upon incubation with the phosphatidylserine binding protein, annexin V. We propose that phosphatidylserine redistributed to the outer plasma membrane of amebocytes undergoing phagocytosis-induced apoptosis could interact with hemocyanin, thus facilitating its conversion into a phenoloxidase-like enzyme, during immune challenge.

  19. A single locus from the entomopathogenic bacterium Photorhabdus luminescens inhibits activated Manduca sexta phenoloxidase.

    PubMed

    Eleftherianos, Ioannis; Waterfield, Nicholas R; Bone, Peter; Boundy, Sam; ffrench-Constant, Richard H; Reynolds, Stuart E

    2009-04-01

    Insect blood (hemolymph) contains prophenoloxidase, a proenzyme that is activated to protective phenoloxidase when the insect is damaged or challenged with microorganisms. The Gram-negative bacterium Photorhabdus luminescens kills the lepidopteron insect Manduca sexta by using a variety of toxins. We screened P. luminescens and Photorhabdus asymbiotica cosmid libraries in an Escherichia coli host against previously activated M. sexta hemolymph phenoloxidase and identified three overlapping cosmid clones from P. luminescens and five from P. asymbiotica that suppressed the activity of the enzyme both in vitro and in vivo. Genome alignments of cosmid end sequences from both species confirmed that they contained orthologous loci. We examined one of the cosmids from P. luminescens in detail: it induced the formation of significantly fewer melanotic nodules, proliferated faster within the insect host and was significantly more virulent towards fifth-stage larvae than E. coli control bacteria. Insertional mutagenesis of this cosmid yielded 11 transposon mutants that were no longer inhibitory. All of these were insertions into a single 5.5-kb locus, which contained three ORFs and was homologous to the maltodextrin phosphorylase locus of E. coli. The implications of this novel inhibitory factor of insect phenoloxidase for Photorhabdus virulence are discussed. PMID:19243439

  20. Differential water mite parasitism, phenoloxidase activity, and resistance to mites are unrelated across pairs of related damselfly species.

    PubMed

    Mlynarek, Julia J; Iserbyt, Arne; Nagel, Laura; Forbes, Mark R

    2015-01-01

    Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assessed relations between actual levels of parasitism and resistance to parasites seen in nature across multiple host species. The main goal of this study was to determine whether interspecific variation in resistance against ectoparasitic larval water mites either was predictive of interspecific variation in parasitism for ten closely related species of damselflies (grouped into five "species pairs"), or was predicted by interspecific variation in a commonly used measure of innate immunity (total Phenoloxidase or potential PO activity). Two of five species pairs had interspecific differences in proportions of individuals resisting larval Arrenurus water mites, only one of five species pairs had species differences in prevalence of larval Arrenurus water mites, and another two of five species pairs showed species differences in mean PO activity. Within the two species pairs where species differed in proportion of individuals resisting mites the species with the higher proportion did not have correspondingly higher PO activity levels. Furthermore, the proportion of individuals resisting mites mirrored prevalence of parasitism in only one species pair. There was no interspecific variation in median intensity of mite infestation within any species pair. We conclude that a species' relative ability to resist particular parasites does not explain interspecific variation in parasitism within species pairs and that neither resistance nor parasitism is reflected by interspecific variation in total PO or potential PO activity.

  1. A zymogen form of masquerade-like serine proteinase homologue is cleaved during pro-phenoloxidase activation by Ca2+ in coleopteran and Tenebrio molitor larvae.

    PubMed

    Lee, Kum Young; Zhang, Rong; Kim, Moon Suk; Park, Ji Won; Park, Ho Young; Kawabata, Shun-ichiro; Lee, Bok Luel

    2002-09-01

    To elucidate the biochemical activation mechanism of the insect pro-phenoloxidase (pro-PO) system, we purified a 45-kDa protein to homogeneity from the hemolymph of Tenebrio molitor (mealworm) larvae, and cloned its cDNA. The overall structure of the 45-kDa protein is similar to Drosophila masquerade serine proteinase homologue, which is an essential component in Drosophila muscle development. This Tenebrio masquerade-like serine proteinase homologue (Tm-mas) contains a trypsin-like serine proteinase domain in the C-terminal region, except for the substitution of Ser to Gly at the active site triad, and a disulfide-knotted domain at the amino-terminal region. When the purified 45-kDa Tm-mas was incubated with CM-Toyopearl eluate solution containing pro-PO and other pro-PO activating factors, the resulting phenoloxidase (PO) activity was shown to be independent of Ca2+. This suggests that the purified 45-kDa Tm-mas is an activated form of pro-PO activating factor. The55-kDa zymogen form of Tm-mas was detected in the hemolymph when PO activity was not evident. However, when Tenebrio hemolymph was incubated with Ca2+, a 79-kDa Tenebrio pro-PO and the 55-kDa zymogen Tm-mas converted to 76-kDa PO and 45-kDa Tm-mas, respectively, with detectable PO activity. Furthermore, when Tenebrio hemolymph was incubated with Ca2+ and beta-1,3-glucan, the conversion of pro-PO to PO and the 55-kDa zymogen Tm-mas to the 45-kDa protein, was faster than in the presence of Ca2+ only. These results suggest that the cleavage of the 55-kDa zymogen of Tm-mas by a limited proteolysis is necessary for PO activity, and the Tm-mas is a pro-PO activating cofactor.

  2. Identification and characterization of proteins with phenoloxidase-like activities in the sea urchin Strongylocentrotus nudus.

    PubMed

    Cheng, Yuhui; Jiang, Jingwei; Dong, Ying; Zhou, Zunchun

    2015-11-01

    Three proteins with PO-like activities in the coelomocytes of sea urchin Strongylocentrotus nudus were identified using electrophoretic method and named as SnPO1, SnPO2 and SnPO3 according to their molecular mass from high to low. The SnPOs were characterized for substrate specificity and the effects of temperature, pH, divalent metal ions and inhibitors on PO activities. They showed oxidative activities to L-3,4-dihydroxyphenylalanine. (l-DOPA), dopamine and hydroquinone, but failed to oxidize tyrosine, which illustrated the three proteins had laccase-like PO activities. The optimum temperature for the activities of SnPO1, SnPO2 and SnPO3 was 75 °C, 70 °C, 40 °C, and the optimum pH was 7.0, 9.0, 8.0, respectively. The SnPOs were notably activated after being incubated in boiled water for 60 min, suggesting that the three proteins are thermophilic. The activity of SnPO1 was greatly enhanced by Cu(2+), Mn(2+) and Fe(2+) and inhibited by Pb(2+), Cd(2+), EDTA, DETC, sodium sulfite and ascorbic acid, but SnPO2 and SnPO3 were not obviously affected by Pb(2+) and Cd(2+), suggesting the three proteins are copper-containing, and the catalytic properties of SnPO1 might be different from those of SnPO2 and SnPO3. Taken together, SnPO1, SnPO2 and SnPO3 might play different roles in the immune and physiological processes of S. nudus. PMID:26314521

  3. Effects of pink bollworm resistance to Bacillus thuringiensis on phenoloxidase activity and susceptibility to entomopathogenic nematodes.

    PubMed

    Gassmann, Aaron J; Fabrick, Jeffrey A; Sisterson, Mark S; Hannon, Eugene R; Stock, S Patricia; Carrière, Yves; Tabashnik, Bruce E

    2009-06-01

    Widespread planting of crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on many key agricultural pests to evolve resistance to Bt. Fitness costs can slow the evolution of Bt resistance. We examined effects of entomopathogenic nematodes on fitness costs of Bt resistance in the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), a major pest of cotton, Gossypium hirsutum L., in the southwestern United States that is currently controlled by transgenic cotton that produces Bt toxin Cry1Ac. We tested whether the entomopathogenic nematodes Steinernema riobrave Cabanillas, Poinar, and Raulston (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) affected fitness costs of resistance to Cry1Ac in two laboratory-selected hybrid strains of pink bollworm reared on non-Bt cotton bolls. The nematode S. riobrave imposed a recessive fitness cost for one strain, and H. bacteriophora imposed a fitness cost affecting heterozygous resistant individuals for the other strain. Activity of phenoloxidase, an important component of insects' immune response, did not differ between Bt-resistant and Bt-susceptible families. This suggests phenoloxidase does not affect susceptibility to entomopathogenic nematodes in Bt-resistant pink bollworm. Additionally, phenoloxidase activity does not contribute to Bt resistance, as has been found in some species. We conclude that other mechanisms cause higher nematode-imposed mortality for pink bollworm with Bt resistance genes. Incorporation of nematode-imposed fitness costs into a spatially explicit simulation model suggests that entomopathogenic nematodes in non-Bt refuges could delay resistance by pink bollworm to Bt cotton.

  4. Purification and characterization of phenoloxidase from clam Ruditapes philippinarum.

    PubMed

    Cong, Rishan; Sun, Wenjie; Liu, Guangxing; Fan, Tingjun; Meng, Xianghong; Yang, Lingling; Zhu, Liyan

    2005-01-01

    Using L-dihydroxyphenylalanine (L-DOPA) as a specific substrate, phenoloxidase (PO) from clam (Ruditapes philippinarum) was purified by Q Sepharose Fast Flow ion-exchange chromatography and Sephacryl S-100 gel-filtration, and characterized biochemically and enzymatically in this study. The molecular mass of PO in SDS-PAGE is about 76.9 kDa, and the prophenoloxidase (proPO) molecule, isolated as a monomeric protein, is 84.1 kDa. The PO molecule had a high oxidative activity, and the proPO molecule had almost no oxidative activity. The PO activity was optimal at pH 7.0 and temperature of 40 degrees C. The Km value of the PO for L-DOPA was 2.2 mmol l(-1). The PO was extremely sensitive to benzoic acid and sodium sulfite, very sensitive to citric acid, thio urea, 1-phenyl-2-thiourea and cysteine, but not sensitive to ascorbic acid. Combined with its specific enzyme activity on tyrosine and L-DOPA, it can be concluded that the Ruditapes PO is probably a kind of tyrosinase-type phenoloxidase. The PO activity was strongly inhibited by ethylenediaminetetraacetic acid (EDTA), diethyldithiocarbamate (DETC), Zn2+, Ca2+ and Cu2+, as well as by Mg2+. The results with EDTA, DETC, and some metal ions, combined with the perfect recovery effect of Cu2+ on DETC-inhibited PO activity, indicate that Ruditapes PO is most probably a copper-containing metalloenzyme. PMID:15450969

  5. Activated phenoloxidase from Tenebrio molitor larvae enhances the synthesis of melanin by using a vitellogenin-like protein in the presence of dopamine.

    PubMed

    Lee, K M; Lee, K Y; Choi, H W; Cho, M Y; Kwon, T H; Kawabata, S; Lee, B L

    2000-06-01

    One of the biological functions of activated phenoloxidase in arthropods is the synthesis of melanin around invaded foreign materials. However, little is known about how activated phenoloxidase synthesizes melanin at the molecular level. Even though it has been suggested that the quinone derivatives generated by activated phenoloxidase might use endogenous protein components for melanin synthesis in arthropods, there is no report of protein components engaged in melanin synthesis induced by activated phenoloxidase. In this study, to isolate and characterize proteins involved in melanin synthesis, we prepared in vitro prophenoloxidase activating solution (designated G-100 solution), specifically showing phenoloxidase activity in the presence of Ca2+ and beta-1, 3-glucan, from the hemolymph of larvae of the coleopteran Tenebrio molitor by using a Sephadex G-100 column. When G-100 solution was incubated with dopamine to induce melanin synthesis in the presence of Ca2+ and beta-1,3-glucan, four types of protein (160 kDa, prophenoloxidase, phenoloxidase and 45 kDa) disappeared from SDS/PAGE under reducing conditions. Under identical conditions, but including phenylthiourea as a phenoloxidase inhibitor added to the G-100 solution, three of these proteins (160 kDa, phenoloxidase and 45 kDa) did not disappear. To characterize these melanization-engaging proteins, we first purified the 160-kDa melanization-engaging protein to homogeneity and raised a polyclonal antibody against it. Analysis of the cDNA revealed that it consisted of 1439 amino-acid residues and showed partial homology with Caenorhabditis elegans vitellogenin precursor-6 (19.7%). Western blot analysis showed that it disappeared when active phenoloxidase induced melanin synthesis. Furthermore, when the purified 160-kDa melanization-engaging protein was added to a G-100 solution deficient in it, melanin synthesis was enhanced compared with the same solution without the protein. These data support the conclusion

  6. Phenoloxidase activity and thermostability of Cancer pagurus and Limulus polyphemus hemocyanin.

    PubMed

    Idakieva, Krassimira; Raynova, Yuliana; Meersman, Filip; Gielens, Constant

    2013-03-01

    The intrinsic and inducible o-diphenoloxidase (o-diPO) activity of Cancer pagurus hemocyanin (CpH) and Limulus polyphemus hemocyanin (LpH) were studied using catechol, l-Dopa and dopamine as substrates. The kinetic analysis shows that dopamine is a more specific substrate for CpH than catechol and l-Dopa (K(m) value of 0.01 mM for dopamine versus 0.67 mM for catechol, and 2.14 mM for l-Dopa), while k(cat) is highest for catechol (2.44 min(-1) versus 0.67 min(-1) for l-Dopa and 0.71 min(-1) for dopamine). On treatment with 4mM sodium dodecyl sulfate (SDS) or by proteolysis the o-diPO activity of CpH increases about twofold. In contrast, native LpH shows no o-diPO activity, and exhibits only a slight activity after incubation with SDS. Neither CpH nor LpH show intrinsic mono-PO activity with l-tyrosine and tyramine as substrates. To explore the possible correlation between the degree of PO activity and protein stability of arthropod hemocyanins, the thermal stability of CpH and LpH was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. CpH is found to be less thermostable (T(m)~80 °C), suggesting that the dicopper active sites are more accessible, thereby allowing the hemocyanin to show PO activity in the native state. The LpH, on the other hand, is more thermostable (T(m)~92 °C), suggesting the existence of a correlation between the thermal stability and the intrinsic PO activity of arthropod hemocyanins. PMID:23313741

  7. Effects of known phenoloxidase inhibitors on hemocyanin-derived phenoloxidase from Limulus polyphemus.

    PubMed

    Wright, Jamie; Clark, William McCaskill; Cain, Jennifer A; Patterson, Alan; Coates, Christopher J; Nairn, Jacqueline

    2012-01-01

    Inhibitors of phenoloxidase are used routinely to characterise the structural and functional properties of phenoloxidases. Hemocyanin-derived phenoloxidase activity is also sensitive to standard phenoloxidase inhibitors. In this study, we characterise the effects of a number of phenoloxidase inhibitors on hemocyanin-derived phenoloxidase activity from the chelicerate, Limulus polyphemus. Both inhibition type and K(i) values were similar to those observed for hemocyanin-derived phenoloxidase from another chelicerate, Eurypelma californicum. In addition, substrate inhibition was observed at concentrations above 2mM dopamine. The conformation in which two of the inhibitors, namely tropolone and kojic acid, would bind near the Cu(II) centre of hemocyanin is proposed. PMID:22885403

  8. Phenoloxidase in larvae of Plodia interpunctella (Lepidoptera: Pyralidae): molecular cloning of the proenzyme cDNA and enzyme activity in larvae paralyzed and parasitized by Habrobracon hebetor (Hymenoptera: Braconidae).

    PubMed

    Hartzer, Kris L; Zhu, Kun Yan; Baker, James E

    2005-06-01

    Phenoloxidase (PO) is a major component of the insect immune system. The enzyme is involved in encapsulation and melanization processes as well as wound healing and cuticle sclerotization. PO is present as an inactive proenzyme, prophenoloxidase (PPO), which is activated via a protease cascade. In this study, we have cloned a full-length PPO1 cDNA and a partial PPO2 cDNA from the Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae) and documented changes in PO activity in larvae paralyzed and parasitized by the ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae). The cDNA for PPO1 is 2,748 bp and encodes a protein of 681 amino acids with a calculated molecular weight of 78,328 and pI of 6.41 containing a conserved proteolytic cleavage site found in other PPOs. P. interpunctella PPO1 ranges from 71-78% identical to other known lepidopteran PPO-1 sequences. Percent identity decreases as comparisons are made to PPO-1 of more divergent species in the orders Diptera (Aa-48; As-49; and Sb-60%) and Coleoptera (Tm-58; Hd-50%). Paralyzation of host larvae of P. interpunctella by the idiobiont H. hebetor results in an increase in phenoloxidase activity in host hemolymph, a process that may protect the host from microbial infection during self-provisioning by this wasp. Subsequent parasitization by H. hebetor larvae causes a decrease in hemolymph PO activity, which suggests that the larval parasitoid may be secreting an immunosuppressant into the host larva during feeding.

  9. Changes in lipophorins are related to the activation of phenoloxidase in the haemolymph of Locusta migratoria in response to injection of immunogens.

    PubMed

    Mullen, L; Goldsworthy, G

    2003-07-01

    In Locusta migratoria, activation of phenoloxidase in the haemolymph in response to injection of laminarin is age-dependent: being absent in fifth instar nymphs and newly emerged adults, and only becoming evident four days after the final moult. This pattern of change in phenoloxidase activation correlates with the pattern of change in the concentration of apolipophorin-III (apoLp-III) in the haemolymph. Injection of a conspecific adipokinetic hormone (Lom-AKH-I) has no effect on the phenoloxidase response in nymphs or newly emerged adults but, in adults older than four days, co-injection of the hormone with laminarin prolongs the activation of phenoloxidase in the haemolymph: a similar enhancement of the response to laminarin is observed in locusts that have been starved for 48 h but not injected with AKH-I. During most of the fifth stadium, injection of laminarin results in a decrease in the level of prophenoloxidase in the haemolymph; an effect that is not observed in adults of any age. Marked changes in the concentration of apoLp-III, and the formation of LDLp in the haemolymph, are observed after injection of laminarin (or LPS) and these are remarkably similar, at least qualitatively, to those that occur after injection of AKH-I. The involvement of lipophorins in the activation of locust prophenoloxidase in response to immunogens is discussed. PMID:12826093

  10. Role and importance of phenoloxidase in insect hemostasis.

    PubMed

    Eleftherianos, Ioannis; Revenis, Christina

    2011-01-01

    In response to microbial infection, insects mount several defense reactions including the induction of proteolytic cascades that lead to localized melanization and coagulation. Melanization requires the activation of prophenoloxidase (proPO) to its active form phenoloxidase (PO), a key enzyme that leads to the formation of melanin at wound sites and around intruding microorganisms in the hemolymph. Clotting is critical in limiting hemolymph loss and initiating wound healing following injury; it quickly acts to form a solid barrier against infection by immobilizing microorganisms and promoting their killing. Recent advances in Drosophila and other insects imply a possible link between PO and the coagulation system, although the exact molecular mechanisms controlling this interaction appear to be complex and are still not well defined. The development of hemolymph experimental techniques in Drosophila larvae together with proteomic analysis have further led to the identification of proPO as a cross-linking component that is involved in the hardening and melanization of clots. However, clot PO activity varies between insect species and life stages, depending on physiological and ecological conditions. Here we review our current knowledge of the association between PO and coagulation and discuss the implications of the previous findings on insect innate immunity and hemostasis. PMID:21051882

  11. Negative regulation of prophenoloxidase (proPO) activation by a clip-domain serine proteinase homolog (SPH) from endoparasitoid venom.

    PubMed

    Zhang, Guangmei; Lu, Zhi-Qiang; Jiang, Haobo; Asgari, Sassan

    2004-05-01

    Most parasitic wasps inject maternal factors into the host hemocoel to suppress the host immune system and ensure successful development of their progeny. Melanization is one of the insect defence mechanisms against intruding pathogens or parasites. We previously isolated from the venom of Cotesia rubecula a 50 kDa protein that blocked melanization in the hemolymph of its host, Pieris rapae [Insect Biochem. Mol. Biol. 33 (2003) 1017]. This protein, designated Vn50, is a serine proteinase homolog (SPH) containing an amino-terminal clip domain. In this work, we demonstrated that recombinant Vn50 bound P. rapae hemolymph components that were recognized by antisera to Tenebrio molitor prophenoloxidase (proPO) and Manduca sexta proPO-activating proteinase (PAP). Vn50 is stable in the host hemolymph-it remained intact for at least 72 h after parasitization. Using M. sexta as a model system, we found that Vn50 efficiently down-regulated proPO activation mediated by M. sexta PAP-1, SPH-1, and SPH-2. Vn50 did not inhibit active phenoloxidase (PO) or PAP-1, but it significantly reduced the proteolysis of proPO. If recombinant Vn50 binds P. rapae proPO and PAP (as suggested by the antibody reactions), it is likely that the molecular interactions among M. sexta proPO, PAP-1, and SPHs were impaired by this venom protein. A similar strategy might be employed by C. rubecula to negatively impact the proPO activation reaction in its natural host.

  12. Examining the relationship between hemolymph phenoloxidase and resistance to a DNA virus, Plodia interpunctella granulosis virus (PiGV).

    PubMed

    Saejeng, A; Tidbury, H; Siva-Jothy, M T; Boots, M

    2010-09-01

    We have a detailed understanding of invertebrate immune responses to bacteria and fungal pathogens, but we know less about how insects respond to virus challenge. Phenoloxidase (PO) functions as an important immune response against many parasites and pathogens and is routinely used as a measure of immune competance. We examine the role of haemolymph PO activity in Plodia interpuncetella's response to its natural granulosis virus (PiGV). Larvae were challenged with virus by both oral inoculation of occluded virus (the natural infection route) and direct intrahaemocoelic injection of budded virus. Haemolymph was collected at time points post-viral challenge using a novel method that allows the volume of haemolymph to be quanitified. The haemolmyph was collected without killing the larvae so that haemolymph samples from individuals that developed viral disease could be distinguished from samples collected from those that fought off infection. The level of haemolymph PO activity in resistant larvae did not differ from control larvae. Therefore we have no evidence that PO is involved in resistance to virus in the haemocoel whether larvae are challenged naturally by oral innoculation or directly by intraheamocoelic injection. Phenoloxidase may therefore not be a relevant metric of immunocompetence for viral infection.

  13. Phenoloxidase and its zymogen are required for the larval-pupal transition in Bactrocera dorsalis (Diptera: Tephritidae).

    PubMed

    Bai, Ping-Ping; Xie, Yi-Fei; Shen, Guang-Mao; Wei, Dan-Dan; Wang, Jin-Jun

    2014-12-01

    Phenoloxidases (POs) play a key role in melanin production, are involved in invertebrate immune mechanisms, and are considered important enzymes in the insect development process. In the present study, we report the developmental stage and tissue-specific expression patterns of BdPPO1 and PO activity from Bactrocera dorsalis. The results showed that the activity of PO and its zymogen expression were closely related to the development of B. dorsalis during the larval-pupal transition, particularly in the integument. Additionally, biochemical characterization showed that PO from different developmental stages and tissues all had maximum activity at pH 7.5 and 37°C. After feeding a metal ion-containing artificial diet, the activity of PO and expression of BdPPO1 were significantly increased, indicating that PO was a metalloprotein and it could be activated by Zn2+, Mg2+, Ca2+, and Cu2+. The functional analysis showed that the expression of BdPPO1 could be regulated by 20-hydroxyecdysone (20E) after injection. Furthermore, injection of the double-stranded RNA of BdPPO1 into the 3rd instar larvae significantly reduced mRNA levels after 24 h and 48 h, and resulted in a lower pupation rate and abnormal phenotype. These results expand the understanding of the important role of PO and its zymogen in the growth of B. dorsalis. PMID:25450426

  14. Antiviral, anti-parasitic, and cytotoxic effects of 5,6-dihydroxyindole (DHI), a reactive compound generated by phenoloxidase during insect immune response.

    PubMed

    Zhao, Picheng; Lu, Zhiqiang; Strand, Michael R; Jiang, Haobo

    2011-09-01

    Phenoloxidase (PO) and its activation system are implicated in several defense responses of insects. Upon wounding or infection, inactive prophenoloxidase (proPO) is converted to active PO through a cascade of serine proteases and their homologs. PO generates reactive compounds such as 5,6-dihydroxyindole (DHI), which have a broad-spectrum antibacterial and antifungal activity. Here we report that DHI and its spontaneous oxidation products are also active against viruses and parasitic wasps. Preincubation of a baculovirus stock with 1.25 mM DHI for 3 h near fully disabled recombinant protein production. The LC₅₀ for lambda bacteriophage and eggs of the wasp Microplitis demolitor were 5.6 ± 2.2 and 111.0 ± 1.6 μM, respectively. The toxicity of DHI and related compounds also extended to cells derived from insects that serve as hosts for several of the aforementioned pathogens. Pretreatment of Sf9 cells with 1.0 mM DHI for 4 h resulted in 97% mortality, and LC₅₀ values of 20.3 ± 1.2 μM in buffer and 131.8 ± 1.1 μM in a culture medium. Symptoms of DHI toxicity in Sf9 cells included DNA polymerization, protein crosslinking, and lysis. Taken together, these data showed that proPO activation and DHI production is strongly toxic against various pathogens but can also damage host tissues and cells if not properly controlled.

  15. SAR of Sponge-Inspired Hemibastadin Congeners Inhibiting Blue Mussel PhenolOxidase

    PubMed Central

    Niemann, Hendrik; Hagenow, Jens; Chung, Mi-Young; Hellio, Claire; Weber, Horst; Proksch, Peter

    2015-01-01

    Hemibastadin derivatives, including the synthetically-derived 5,5′-dibromohemibastadin-1 (DBHB), are potent inhibitors of blue mussel phenoloxidase (PO), which is a key enzyme involved in the firm attachment of this invertebrate to substrates and, thus, a promising molecular target for anti-fouling research. For a systematic investigation of the enzyme inhibitory activity of hemibastadin derivatives, we have synthesized nine new congeners, which feature structural variations of the DBHB core structure. These structural modifications include, e.g., different halogen substituents present at the aromatic rings, different amine moieties linked to the (E)-2-(hydroxyimino)-3-(4-hydroxyphenyl)propionic acid, the presence of free vs. substituted aromatic hydroxyl groups and a free vs. methylated oxime group. All compounds were tested for their inhibitory activity towards the target enzyme in vitro, and IC50 values were calculated. Derivatives, which structurally closely resemble sponge-derived hemibastadins, revealed superior enzyme inhibitory properties vs. congeners featuring structural moieties that are absent in the respective natural products. This study suggests that natural selection has yielded structurally-optimized antifouling compounds. PMID:25988522

  16. In vitro antibacterial analysis of phenoloxidase reaction products from the sea cucumber Apostichopus japonicus.

    PubMed

    Jiang, Jingwei; Zhou, Zunchun; Dong, Ying; Cong, Cong; Guan, Xiaoyan; Wang, Bai; Chen, Zhong; Jiang, Bei; Yang, Aifu; Gao, Shan; Sun, Hongjuan

    2014-08-01

    Three phenoloxidases (POs) of Apostichopus japonicus, AjPOs (AjPO1, AjPO2 and AjPO3), were partially purified from the coelomocytes with an electrophoretic method, and then employed for the in vitro antibacterial analysis. Using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, AjPO1 and AjPO2-derived compounds inhibited the growth of Vibrio splendidus and Staphylococcus aureus, while AjPO3-derived compounds only inhibited the growth of V. splendidus. When dopamine was used as a substrate, AjPO1 and AjPO3-derived compounds inhibited the growth of V. splendidus and Vibrio harveyi, while AjPO2-derived compounds only inhibited the growth of V. splendidus. Moreover, AjPO1-derived compounds showed stronger inhibition in V. harveyi than AjPO3-derived compounds did. However, all of the three AjPO reaction products showed no inhibitions on the growth of Pseudoalteromonas nigrifaciens, Shewanella baltica, Micrococcus lysodeikticus, Streptococcus dysgalactiae and Nocardiopsis sp. with L-DOPA or dopamine as a substrate. Scanning electron microscope (SEM) observation of V. harveyi treated by AjPOs and dopamine showed that AjPO1-derived compounds resulted in massive bacteriolysis, AjPO2-derived compounds caused no obvious alteration on bacterial morphology, and AjPO3-derived compounds increased the ratio of spheroidal bacteria. All these results suggested that AjPO reaction products derived by L-DOPA and dopamine had different but limited antibacterial spectrum, and the different antibacterial effects observed among three AjPOs resulted from the different reaction products generated by AjPOs with the same substrate. PMID:24931626

  17. Effect of Ag+ and PO43‑ ratios on the microstructure and photocatalytic activity of Ag3PO4

    NASA Astrophysics Data System (ADS)

    Qin, Jiaqian; Zhang, Xinyu; Yang, Chengwu; Song, Aijun; Zhang, Bing; Rajendran, Saravanan; Ma, Mingzhen; Liu, Riping

    2016-09-01

    In this work, the catalyst silver phosphate (Ag3PO4) with different initial ratios of Ag+ and PO43‑ in aqueous solution was synthesized by a simple precipitation method from AgNO3 and NH4H2PO4 which were used as the precursor. After that, the prepared samples were characterized by different techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-DRS) and decomposition evolution of rhodamine B (RhB) solution. The results indicate that the initial ratios of Ag+/PO43‑ in aqueous solution can modify the morphology and also it can significantly affect the photocatalytic performance. During photocatalytic process, the rich Ag+ ion Ag3PO4 can form the surface plasmon resonance (SPR) of Ag nanoparticles, which inhibit the reduction of Ag3PO4 resulting in higher photocatalytic activity and stability.

  18. Molecular control of phenoloxidase-induced melanin synthesis in an insect.

    PubMed

    Kan, Hongnan; Kim, Chan-Hee; Kwon, Hyun-Mi; Park, Ji-Won; Roh, Kyung-Baeg; Lee, Hanna; Park, Bum-Joon; Zhang, Rong; Zhang, Jinghai; Söderhäll, Kenneth; Ha, Nam-Chul; Lee, Bok Luel

    2008-09-12

    The melanization reaction induced by activated phenoloxidase in arthropods must be tightly controlled because of excessive formation of quinones and excessive systemic melanization damage to the hosts. However, the molecular mechanism by which phenoloxidase-induced melanin synthesis is regulated in vivo is largely unknown. It is known that the Spätzle-processing enzyme is a key enzyme in the production of cleaved Spätzle from pro-Spätzle in the Drosophila Toll pathway. Here, we provide biochemical evidence that the Tenebrio molitor Spätzle-processing enzyme converts both the 79-kDa Tenebrio prophenoloxidase and Tenebrio clip-domain SPH1 zymogen to an active melanization complex. This complex, consisting of the 76-kDa Tenebrio phenoloxidase and an active form of Tenebrio clip-domain SPH1, efficiently produces melanin on the surface of bacteria, and this activity has a strong bactericidal effect. Interestingly, we found the phenoloxidase-induced melanization reaction to be tightly regulated by Tenebrio prophenoloxidase, which functions as a competitive inhibitor of melanization complex formation. These results demonstrate that the Tenebrio Toll pathway and the melanization reaction share a common serine protease for the regulation of these two major innate immune responses. PMID:18628205

  19. [Establishment and activity of PoKuNyoKwan].

    PubMed

    Lee, Bang Weon

    2008-06-01

    PoKuNyoKwan was established in 1887 by Meta Howard, a female doctor who was dispatched from Woman's Foreign Missionary Society, an evangelical branch affiliated with U.S. North Methodist Church. PoKuNyoKwan was equipped with dispensaries, waiting rooms, pharmacies, warehouses, operating rooms, and wards for about 30 patients. It used a traditional Korean house, which was renovated for its medical purpose, in Ewha Haktang. Residing in Chung Dong, the medical institution had taken care of women's mental and physical health for about 25 years, until it was merged with East Gate Lillian Harris Memorial Hospital in 1912, and then its dispensary function was abolished in 1913. Medical missionaries (Meta Howard, Rosetta Sherwood, Mary M. Cutler, Emma Ernsberger, Esther K. Pak, Amanda F. Hillman) and nurse missionaries (Ella Lewis, Margaret J. Edmunds, Alta I. Morrison, Naomi A. Anderson), who were professionally trained in the United States, and their helpers, who were trained by those missionaries, managed PoKuNyoKwan. Nurses who were educated in Nurses' Training School, which was also established by PoKuNyoKwan, helped to run the institution as well. At the beginning, they usually had worked as a team of one medical missionary and three helpers. Since its establishment in 1903, however, the helpers began to enter the Nurses' Training School to become professional nurses, and the helpers eventually faded out because of the proliferation of those nurses. PoKuNyoKwan did not only offer medical services but also executed educational and evangelical activities. Medical missionaries struggled to overcome Koreans' ignorance and prejudice against westerners and western medical services, while they took care of their patients at office, for calls, and in hospital dispensaries. Enlightening the public by criticizing Korean traditional medical treatments including fork remedies, acupuncture, and superstitions, they helped modernization of medical systems in Korea. In the area of

  20. Radiation-induced changes in melanization and phenoloxidase in Caribbean fruit fly larvae (diptera:tephritidae) as the basis for a simple test of irradiation

    SciTech Connect

    Nation, J.L.; Milne, K.; Smittle, B.J.

    1995-03-01

    First instars of the Caribbean fruit fly, Anastrepha suspensa (Loew), were irradiated with 0, 5, 10, 20, 50, 75, 100, and 150 Gy doses from a Cs-137 source, and observed for whole body melanization as late third instars. Control larvae rapidly melanized, whereas larvae irradiated at {ge}20 Gy failed to show typical melanization after freezing and thawing. Assays of phenoloxidase in control and irradiated larvae showed greatly decreased enzyme activity at {ge}20 Gy and substantial reduction at lower doses. Larvae were also irradiated on the 1st d of each instar, and phenoloxidase activity was determined when they became late third instars. Larvae irradiated on the 1st d of the first instar and on 1st d of the second instar has {approx}90% or greater reduction in phenoloxidase activity as late third instars. Larvae irradiated on the 1st d of the instar had {approx}50% reduction in phenoloxidase activity at the time they became late third instars leaving the food to pupate. A simple spot test for phenoloxidase was developed that produced a red color with a crushed control larvae and no color with a larva irradiated at {ge}25 Gy. The radiation induced changes in melanization and phenoloxidase activity, and a simple spot test may serve as tests for irradiation treatment of Caribbean fruit fly larvae. 10 refs., 2 figs., 2 tabs.

  1. Structure of C3PO and mechanism of human RISC activation

    SciTech Connect

    Ye, Xuecheng; Huang, Nian; Liu, Ying; Paroo, Zain; Huerta, Carlos; Li, Peng; Chen, She; Liu, Qinghua; Zhang, Hong

    2011-08-26

    Assembly of the RNA-induced silencing complex (RISC) consists of loading duplex (guide-passenger) siRNA onto Argonaute (Ago2) and removing the passenger strand. Ago2 contributes critically to RISC activation by nicking the passenger strand. Here we reconstituted duplex siRNA-initiated RISC activity using recombinant human Ago2 (hAgo2) and C3PO, indicating that C3PO has a critical role in hAgo2-RISC activation. Consistently, genetic depletion of C3PO compromised RNA silencing in mammalian cells. We determined the crystal structure of hC3PO, which reveals an asymmetric octamer barrel consisting of six translin and two TRAX subunits. This asymmetric assembly is critical for the function of C3PO as an endonuclease that cleaves RNA at the interior surface. The current work supports a Dicer-independent mechanism for human RISC activation, in which Ago2 directly binds duplex siRNA and nicks the passenger strand, and then C3PO activates RISC by degrading the Ago2-nicked passenger strand.

  2. Biochemical studies of phenoloxidase and utilization of catecholamines in Cryptococcus neoformans.

    PubMed Central

    Polacheck, I; Hearing, V J; Kwon-Chung, K J

    1982-01-01

    Protoplasts of Cryptococcus neoformans contain phenoloxidase as a membrane-bound enzyme. The enzyme appeared to be attached on the inner side of cytoplasmic membranes. Synthesis of the enzyme was derepressed by low levels of glucose but was not affected by the level of ammonium. Copper chelators which inhibited the phenoloxidase of other organisms did not affect cryptococcal enzymes. However, cyanide- or iron-chelating agents such as hydroximide derivates or 8-hydroxyquinoline were effective inhibitors, suggesting that cryptococcal phenoloxidase is an iron-containing enzyme. Phenoloxidase of C. neoformans catalyzed the oxidation of various diphenols via dopachrome and labile intermediates to melanin polymers. The kinetic constants (Km) of the phenoloxidase and the permease for dopamine and norepinephrine were low. The correlation between phenoloxidase and the preferential growth of C. neoformans in the host brain is discussed. PMID:6804439

  3. Hydroxyapatite supported Ag3PO4 nanoparticles with higher visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Hong, Xiaoting; Wu, Xiaohui; Zhang, Qiuyun; Xiao, Mingfeng; Yang, Gelin; Qiu, Meirong; Han, Guocheng

    2012-03-01

    Hydroxyapatite supported Ag3PO4 nanocomposites have been synthesized by a wet impregnation process. UV-vis absorption spectra show a red shift of the absorption edges for the composite systems compared to pure hydroxyapatite support. The surface structure and morphology of the nanocomposites were characterized by Brunauer-Emmett-Teller (BET) apparatus, X-ray diffraction (XRD), transmission electron microscopy (TEM). The results suggest that Ag3PO4 nanoparticles (6-17 nm in diameter) are well dispersed on the hydroxyapatite support and Ag3PO4 nanoparticles density is larger for the higher Ag+ loading sample. The as-prepared nanocomposite photocatalysts showed a pronounced photocatalytic activity upon decomposition of methylene blue dye in aqueous solution under both visible light (wavelength > 400 nm) and UV-vis light irradiation. A synergic mechanism of inherent photocatalytic capability of Ag3PO4 and the accelerated electron/hole separation resulting from the photoinduced electrons captured by the slow-released Ag+ at the interface of Ag3PO4 and hydroxyapatite is proposed for the nanocomposites on the enhancement of photocatalytic performance in comparison to that of pure Ag3PO4 nanoparticles. The support of hydroxyapatite may also act as an absorbent which favors the mass transfer in heterogeneous photocatalysis reaction.

  4. Unusually high (210)Po activities in the surface water of the Zhubi Coral Reef Lagoon in the South China Sea.

    PubMed

    Yang, Weifeng; Huang, Yipu; Chen, Min; Qiu, Yusheng; Li, Hongbin; Zhang, Lei

    2011-10-01

    Recent researches revealed the exciting application of (210)Po in tracing carbon and nitrogen cycling in the coral reef system. In order to quantify the recycling of particulate organic nitrogen (PON), both (210)Po and (210)Pb were examined at both high and low tides in the Zhubi Coral Reef lagoon, the South China Sea. Unusually, much higher (210)Po activities and (210)Po/(210)Pb ratios, in comparison with those found in the open seawater and the lagoon subsurface water, showed additional input of (210)Po besides production from in situ(210)Pb in the lagoon surface water. Statistical analysis identified that the reef flat seawater was the additional (210)Po source. Based on a mass balance model, the input rates of (210)Po varied from 0.04 Bq m(-3)year(-1) to 8.41 Bq m(-3)year(-1). On average, the additional (210)Po contributed more than 60% of the total (210)Po. The particulate (210)Po significantly correlated with the concentrations of PON, indicating that diffusion of (210)Po from sediment could be used to quantify the recycling of nitrogen. The average input rate of nitrogen was 16 mmol m(-3)year(-1), which can support up to 11% of the primary production rate. These results suggested that the unusual behavior of (210)Po could provide new insight into the nitrogen recycling in the coral reef system.

  5. C3PO, an endoribonuclease that promotes RNAi by facilitating RISC activation.

    PubMed

    Liu, Ying; Ye, Xuecheng; Jiang, Feng; Liang, Chunyang; Chen, Dongmei; Peng, Junmin; Kinch, Lisa N; Grishin, Nick V; Liu, Qinghua

    2009-08-01

    The catalytic engine of RNA interference (RNAi) is the RNA-induced silencing complex (RISC), wherein the endoribonuclease Argonaute and single-stranded small interfering RNA (siRNA) direct target mRNA cleavage. We reconstituted long double-stranded RNA- and duplex siRNA-initiated RISC activities with the use of recombinant Drosophila Dicer-2, R2D2, and Ago2 proteins. We used this core reconstitution system to purify an RNAi regulator that we term C3PO (component 3 promoter of RISC), a complex of Translin and Trax. C3PO is a Mg2+-dependent endoribonuclease that promotes RISC activation by removing siRNA passenger strand cleavage products. These studies establish an in vitro RNAi reconstitution system and identify C3PO as a key activator of the core RNAi machinery.

  6. An experimental analysis of the contribution of 210Po and of 210Po produced by 210Pb decay to the gross alpha-particle activity of water samples.

    PubMed

    Arndt, Michael F; West, Lynn E

    2008-09-01

    The contribution of 210Po and of 210Po produced by 210Pb decay to the gross alpha-particle activity of water samples by U.S. Environmental Protection Agency Method 900.0 is investigated as a function of residue mass and geometry and time between sample collection and analysis. It is shown that these factors can cause the contribution to gross alpha-particle activity of 210Po to be up to 2.0 and 1.1 times the initial 210Po activity for grab and quarterly composite samples, respectively, and can cause the contribution to gross alpha-particle activity of 210Po from 210Pb decay to be up to 1.1 times and 1.5 times the 210Pb activity for grab and quarterly composite samples, respectively. It is also shown qualitatively that at least for some residues, there is a loss of polonium due to volatilization when the sample is heated over a flame.

  7. Retrospective assessment of indoor radon exposure by measurements of embedded 210Po activity in glass objects

    NASA Astrophysics Data System (ADS)

    Ramola, R. C.; Gusain, G. S.; Prasad, Ganesh

    In most of the epidemiological studies contemporary radon measurements have been used as surrogates for radon concentrations in past decades even though changes in radon levels and residence may have occurred. Short-lived radon progeny may deposit on available surfaces in dwellings thus giving rise over time to a build up of long-lived progeny. Airborne radon decay products can be deposited and implanted through alpha recoil into the glass surfaces. On glass surface, activities of 210Po may arise as a result of the decay of recoil implanted activity following the alpha decay of surface deposited 218Po or 214Po. Measurement of 210Po implanted on a household glass is a method that can be employed to retrospectively determine the historic level of radon in dwellings. This method is based on the assumption that levels of recoil implanted 210Po in the glass provide a measure of time integrated radon concentration in the environment in which the glass has been located. The surface deposited activity of the radon progenies, which then become implanted in the glass by alpha recoil, is believed to reflect past exposure to airborne activity. Such retrospective measurements on glass are valuable in estimating the human dose derived from radon during the time of exposure. In this paper an account is given of the principles and some field applications of a retrospective technique, using the alpha track detectors, CR-39 and LR-115, to measure 210Po implanted in glass surfaces (surface traps). By using this CR-LR difference technique, the cumulative radon exposure in a dwelling in past decades may be estimated. This method provides reliable radon exposure data as a support to epidemiological studies concerning the health effects of radon exposure in the living environment.

  8. A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries.

    PubMed

    Ha, Jeonghyun; Park, Seung-Keun; Yu, Seung-Ho; Jin, Aihua; Jang, Byungchul; Bong, Sungyool; Kim, In; Sung, Yung-Eun; Piao, Yuanzhe

    2013-09-21

    A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.

  9. JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC) data availability, version 1-94

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Physical Oceanography Distributed Active Archive Center (PO.DAAC) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea-surface height, surface-wind vector, sea-surface temperature, atmospheric liquid water, and integrated water vapor. The JPL PO.DAAC is an element of the Earth Observing System Data and Information System (EOSDIS) and is the United States distribution site for Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

  10. Linker length and flexibility induces new cellobiohydrolase activity of PoCel6A from Penicillium oxalicum.

    PubMed

    Gao, Le; Wang, Lushan; Jiang, Xukai; Qu, Yinbo

    2015-06-01

    In a previous study, a novel cellobiohydrolase, PoCel6A, with new enzymatic activity against p-nitrophenyl-β-D-cellobioside (pNPC), was purified from Penicillium oxalicum. The cellulose-binding module and catalytic domain of PoCel6A showed a high degree of sequence similarity with other fungal Cel6As. However, PoCel6A had 11 more amino acids in the linker region than other Cel6As. To evaluate the relationship between the longer linker of PoCel6A and its enzymatic activity, 11 amino acids were deleted from the linker region of PoCel6A. The shortened PoCel6A linker nullified the enzymatic activity against pNPC but dramatically increased the enzyme's capacity for crystalline cellulose degradation. The shortened linker segment appeared to have no effect on the secondary structural conformation of PoCel6A. Another variant (PoCel6A-6pro) with six consecutive proline residues in the interdomain linker had a higher rigid linker, and no enzymatic activity was observed against soluble and insoluble substrate. The flexibility of the linker had an important function in the formation of active cellulase. The length and flexibility of the linker is clearly able to modify the function of PoCel6A and induce new characteristics of Cel6A.

  11. Linker length and flexibility induces new cellobiohydrolase activity of PoCel6A from Penicillium oxalicum.

    PubMed

    Gao, Le; Wang, Lushan; Jiang, Xukai; Qu, Yinbo

    2015-06-01

    In a previous study, a novel cellobiohydrolase, PoCel6A, with new enzymatic activity against p-nitrophenyl-β-D-cellobioside (pNPC), was purified from Penicillium oxalicum. The cellulose-binding module and catalytic domain of PoCel6A showed a high degree of sequence similarity with other fungal Cel6As. However, PoCel6A had 11 more amino acids in the linker region than other Cel6As. To evaluate the relationship between the longer linker of PoCel6A and its enzymatic activity, 11 amino acids were deleted from the linker region of PoCel6A. The shortened PoCel6A linker nullified the enzymatic activity against pNPC but dramatically increased the enzyme's capacity for crystalline cellulose degradation. The shortened linker segment appeared to have no effect on the secondary structural conformation of PoCel6A. Another variant (PoCel6A-6pro) with six consecutive proline residues in the interdomain linker had a higher rigid linker, and no enzymatic activity was observed against soluble and insoluble substrate. The flexibility of the linker had an important function in the formation of active cellulase. The length and flexibility of the linker is clearly able to modify the function of PoCel6A and induce new characteristics of Cel6A. PMID:25866282

  12. AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

    SciTech Connect

    Katsumata, Hideyuki; Hayashi, Takahiro; Taniguchi, Masanao; Suzuki, Tohru; Kaneco, Satoshi

    2015-03-15

    Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.

  13. Recombinant Drosophila prophenoloxidase 1 is sequentially cleaved by α-chymotrypsin during in vitro activation.

    PubMed

    Lu, Anrui; Li, Xuquan; Hillyer, Julián F; Beerntsen, Brenda T; Söderhäll, Kenneth; Ling, Erjun

    2014-07-01

    Insect prophenoloxidase (PPO) is an essential innate immunity protein to induce pathogen into melanization. In Bombyx mori, pro-phenoloxidase-activating enzyme (PPAE) can directly cleave and activate PPO. However, PPO in Manduca sexta cannot be cleaved into active phenoloxidase (PO) by serine proteases unless cofactors are involved, which indicates that PPO activation is complicated. Here we use recombinant Drosophila melanogaster prophenoloxidase 1 (rPPO1) to study the mechanism of PPO activation induced by a typical serine protease, α-chymotrypsin. Small amounts of α-chymotrypsin cleave rPPO1 at the N- and C-terminus to produce a large fragment rPPO1(N1/C1) that needs further cleavage by α-chymotrypsin to produce a smaller fragment rPO1(60-kD) with PO activity. rPO1(60-kD) oxidizes dopamine without being affected by high temperature, or by having salt and Ethylene diamine tetraacetic acid (EDTA) in the solution. After incubation with dopamine, rPO1(60-kD) cannot be detected using reducing SDS-PAGE due to formation of a large complex. Trypsin, another typical serine protease, cleaves rPPO1 at the N- and C-terminus to produce a small fragment rPPO1(N'/C') without PO activity. Several rPPO1 mutants were created through over-expressing active fragments that have direct PO activity. They are easily cleaved by low amounts of α-chymotrypsin without increasing PO activity. Therefore, rPPO1 can be sequentially cleaved in at least three places by α-chymotrypsin to produce activated rPO1(60-kD).

  14. (210)Po in drinking water, its potential health effects, and inadequacy of the gross alpha activity MCL.

    PubMed

    Seiler, Ralph

    2016-10-15

    Polonium-210 ((210)Po) is a naturally-occurring, carcinogenic member of the (238)U decay series and the granddaughter of (210)Pb. It has a half life of 138.4days and is rarely found in drinking water at levels exceeding 5mBq/L because it strongly binds to aquifer sediment. When the current US Maximum Contaminant Level (MCL) covering (210)Po was promulgated in December 2000, very little was known about its occurrence and the processes responsible for mobilizing it. More is now known about the processes that mobilize (210)Po from sediments and a review of recent occurrence data show that it may not be as rare in the US as the US Environmental Protection Agency (USEPA) thought in 2000. Worldwide, only about 2200 analyses for (210)Po in drinking water were identified, with activities exceeding 500mBq/L being found only in Finland, India, Sweden, and the US. The median of 400 (210)Po analyses from the US is 4.75mBq/L and >10% of the samples exceed 500mBq/L. Current compliance-monitoring regulations in the US essentially guarantee that (210)Po contamination will not be detected except in very contaminated wells. Major problems with the US Gross Alpha Activity MCL include the volatility of (210)Po and extended holding times and sample-compositing methods that can allow the majority of (210)Po in a sample bottle to decay before analysis. In light of new information, the radionuclide rule should be changed and direct measurements of (210)Po should be made in all public-water supply wells to rule out its presence. Much of the important biological and toxicological research on (210)Po is more than four decades old and new laboratory research using modern tools is needed. Biological and epidemiological investigations of known contaminated areas are needed to assess the effect (210)Po exposure is having on animals and humans consuming the water.

  15. A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Ha, Jeonghyun; Park, Seung-Keun; Yu, Seung-Ho; Jin, Aihua; Jang, Byungchul; Bong, Sungyool; Kim, In; Sung, Yung-Eun; Piao, Yuanzhe

    2013-08-01

    A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly

  16. A novel molecular sieve supporting material for enhancing activity and stability of Ag3PO4 photocatalyst

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Wang, Peifu; Niu, Futao; Huang, Cunping; Li, Yang; Yao, Weifeng

    2016-08-01

    A small-pore silicon-substituted silicon aluminum phosphate (SAPO-34) molecular sieve, for the first time, is reported to significantly increase both the activity and life span of Ag3PO4 photocatalyst for visible-light degradation of methylene blue (MB) and rhodamine B (RhB). Results show that 60 wt.% Ag3PO4/SAPO-34 exhibits the highest photocatalytic degradation efficiencies for both MB (91.0% degradation within 2.0 min) and RhB (91.0% degradation within 7.0 min). In comparison, pure Ag3PO4 powder photocatalyst requires 8.0 min and 12.0 min for decomposing 91.0% of MB and RhB, respectively. During MB degradation the rate constant for 60 wt.% Ag3PO4/SAPO-34 increases 317.2% in comparison with the rate constant of pure Ag3PO4. This activity is also much higher than literature reported composite or supported Ag3PO4 photocatalysts. In three photocatalytic runs for the degradation of RhB, the rate constant for 60 wt.% Ag3PO4/SAPO-34 reduces from 0.33 to 0.18 min-1 (45.5% efficiency loss). In contrast, the rate constant of pure Ag3PO4 catalyst decreases from 0.2 to 0.07 min-1 (80.0% efficiency loss). All experimental results have shown that small pores and zero light absorption loss of SAPO-34 molecular sieves minimize Ag3PO4 loading, enhance photocatalytic activity and prolong the lifespan of Ag3PO4 photocatalyst.

  17. Data catalog for JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC)

    NASA Technical Reports Server (NTRS)

    Digby, Susan

    1995-01-01

    The Physical Oceanography Distributed Active Archive Center (PO.DAAC) archive at the Jet Propulsion Laboratory contains satellite data sets and ancillary in-situ data for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Geophysical parameters available from the archive include sea-surface height, surface-wind vector, surface-wind speed, surface-wind stress vector, sea-surface temperature, atmospheric liquid water, integrated water vapor, phytoplankton pigment concentration, heat flux, and in-situ data. PO.DAAC is an element of the Earth Observing System Data and Information System and is the United States distribution site for TOPEX/POSEIDON data and metadata.

  18. Excess of polonium-210 activity in the surface urban atmosphere. Part 2: origin of ²¹⁰Po excess.

    PubMed

    Długosz-Lisiecka, Magdalena

    2015-02-01

    The presence of significant (210)Po activity, unsupported by its grandparent radionuclide (210)Pb, in the surface atmosphere of industrialized regions can originate from human technical activities. In urban air, the activity ratio of (210)Po to (210)Pb might increase as a result of natural condensation and coagulation processes of relatively volatile (210)Po-containing species emitted during coal combustion processes. The presence of excess of (210)Po cannot be explained by its in-growth from radioactive decay of (210)Bi. About 50% of (210)Po radionuclide released during coal combustion processes can be emitted into air as gaseous or ultrafine products. Subsequently, these products are quickly attached to the surface of fine particles suspended in the air. As a result, an excess of (210)Po activity in aerosols has been reported. However, in this manner, As much as 11 GBq of (210)Po per year can enter the urban air from the local coal power plants in Lodz city, Poland.

  19. Excess of polonium-210 activity in the surface urban atmosphere. Part 2: origin of ²¹⁰Po excess.

    PubMed

    Długosz-Lisiecka, Magdalena

    2015-02-01

    The presence of significant (210)Po activity, unsupported by its grandparent radionuclide (210)Pb, in the surface atmosphere of industrialized regions can originate from human technical activities. In urban air, the activity ratio of (210)Po to (210)Pb might increase as a result of natural condensation and coagulation processes of relatively volatile (210)Po-containing species emitted during coal combustion processes. The presence of excess of (210)Po cannot be explained by its in-growth from radioactive decay of (210)Bi. About 50% of (210)Po radionuclide released during coal combustion processes can be emitted into air as gaseous or ultrafine products. Subsequently, these products are quickly attached to the surface of fine particles suspended in the air. As a result, an excess of (210)Po activity in aerosols has been reported. However, in this manner, As much as 11 GBq of (210)Po per year can enter the urban air from the local coal power plants in Lodz city, Poland. PMID:25567664

  20. Activation of the prophenoloxidase cascade and initiation of nodule formation in locusts by bacterial lipopolysaccharides.

    PubMed

    Ratcliffe, N A; Brookman, J L; Rowley, A F

    1991-01-01

    The activation of the prophenoloxidase (proPO) system of the locusts, Schistocerca gregaria and Locusta migratoria, by several bacterial lipopolysaccharides (LPS) is described. Activation of proPO by LPS occurred only in the presence of whole blood homogenates and not with hemocyte lysate preparations alone. Levels of phenoloxidase generated by the different LPSs in vitro were also correlated with numbers of nodules formed in vivo by injection of these LPSs. This further strengthens the evidence for the involvement of proPO activation in the insect cellular defenses. Finally, the wisdom in using anticoagulants in order to stabilize fragile hemocytes in studies on the proPO system is discussed. PMID:1904828

  1. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in dogs' hair.

    PubMed

    Strumińska-Parulska, Dagmara I; Szymańska, Karolina; Skwarzec, Bogdan

    2015-01-01

    The aim of this study was to determine activity concentrations of radiolead (210)Pb as well as (210)Po/(210)Pb activity ratios in dog hair. The objectives of this research were also to investigate the utility of domestic animal hair as a noninvasive indicator of metal exposure for radiotoxic, naturally occurring (210)Pb and find the correlations between (210)Pb concentration in hair and age, gender, hair type or diet of analyzed animals. The highest (210)Pb concentrations were measured in a 2-year-old Shih Tzus (9.82 ± 0.53 Bq kg(-1) dw(-1)) and a 2-year-old Bichon Maltese (8.09 ± 0.42 Bq kg(-1) dw(-1)), both longhair males, while the lowest was found in a 15-year-old Yorkshire Terrier (0.44 ± 0.02 Bq kg(-1) dw(-1)), small longhair male as well. As results showed, mainly dog hair color as well as their age and gender influenced the differences in the values of (210)Pb concentrations in analyzed hair samples. Also the values of activity ratios of (210)Po/(210)Pb in analyzed dog hair samples were calculated and obtained results were similar to those observed in human hair. PMID:26191992

  2. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in dogs' hair.

    PubMed

    Strumińska-Parulska, Dagmara I; Szymańska, Karolina; Skwarzec, Bogdan

    2015-01-01

    The aim of this study was to determine activity concentrations of radiolead (210)Pb as well as (210)Po/(210)Pb activity ratios in dog hair. The objectives of this research were also to investigate the utility of domestic animal hair as a noninvasive indicator of metal exposure for radiotoxic, naturally occurring (210)Pb and find the correlations between (210)Pb concentration in hair and age, gender, hair type or diet of analyzed animals. The highest (210)Pb concentrations were measured in a 2-year-old Shih Tzus (9.82 ± 0.53 Bq kg(-1) dw(-1)) and a 2-year-old Bichon Maltese (8.09 ± 0.42 Bq kg(-1) dw(-1)), both longhair males, while the lowest was found in a 15-year-old Yorkshire Terrier (0.44 ± 0.02 Bq kg(-1) dw(-1)), small longhair male as well. As results showed, mainly dog hair color as well as their age and gender influenced the differences in the values of (210)Pb concentrations in analyzed hair samples. Also the values of activity ratios of (210)Po/(210)Pb in analyzed dog hair samples were calculated and obtained results were similar to those observed in human hair.

  3. Immune responses of phenoloxidase and superoxide dismutase in the manila clam Venerupis philippinarum challenged with Vibrio tapetis--part II: combined effect of temperature and two V. tapetis strains.

    PubMed

    Richard, Gaëlle; Le Bris, Cédric; Guérard, Fabienne; Lambert, Christophe; Paillard, Christine

    2015-05-01

    Manila clams, Venerupis philippinarum (Adams and Reeve, 1850), were experimentally infected with two different bacterial strains and challenged with two different temperatures. Bacterial strains used in this study were Vibrio tapetis strain CECT4600(T), the causative agent of Brown Ring Disease (BRD) and V. tapetis strain LP2, supposed less virulent to V. philippinarum. V. tapetis is considered to proliferate at low temperatures, i.e. under 21 °C. In a global warming context we could hypothesize a decrease of mass mortalities caused by V. tapetis but these thermal changes could also directly impact the immune system of the host V. philippinarum. Thus, the aim of this study was to investigate the effects of the extrapallial injection with V. tapetis combined with temperature challenge on two enzymes activities in V. philippinarum. More precisely, after infection, phenoloxidase (PO) and superoxide dismutase (SOD), two major enzymes involved in immune response, were studied for 30 days in two compartments: the mantle and the hemolymph. Conchyolin Deposit Stages (CDS) and Shell Repair Stages (SRS) were also determined 30 days post-injection as a proxy of the virulence of the tested strains. In this study, we highlighted that host-pathogen interaction in a varying environment affects the enzymatic response of the host. The coupled effect of V. tapetis injection and temperature challenge was detected 30 days post injection and resulted in virulence differences. These findings were supported by CDS and SRS determination in clams and lead to the conclusion that clam's immunity could be enhanced at 22 °C while V. tapetis virulence is lowered at this temperature. Another result of our study was the increase of PO and SOD basal activities as clams are exposed to warmer temperature.

  4. 210Po and 210Pb Activity Concentrations in Cigarettes Produced in Vietnam and Their Estimated Dose Contribution Due to Smoking

    NASA Astrophysics Data System (ADS)

    Tran, Thuy-Ngan N.; Le, Cong-Hao; Chau, Van-Tao

    Smoking cigarettes contributes significantly to the increase of radiation in human body because 210Po and 210Pb exist relatively high in tobacco leaves. Therefore, these two radioisotopes in eighteen of the most frequently sold cigarette brands produced in Vietnam were examined in this study. 210Po was determined by alpha spectroscopy using a passivated implanted planar silicon (PIPS) detector after a procedure including radiochemical separation and spontaneous deposition of polonium on a copper disc (the deposition efficiency of 210Po on a copper disc was approximately 94%). Sequentially, 210Pb was determined through the ingrowth of 210Po after storing the sample solutions for approximately six months. The activity concentrations of 210Po in cigarettes ranged from 13.8 to 82.6 mBq/cigarette (the mean value was 26.4 mBq/cigarette) and the activity concentrations of 210Pb in cigarettes ranged from 13.9 to 78.8 mBq/cigarette (the mean value was 25.8 mBq/cigarette). The annual committed effective dose for smokers who smoke one pack per day was also estimated to be 295.4 µSv/year (223.0 µSv/year and 72.4 µSv/year from 210Po and 210Pb, respectively). These indicated that smoking increased the risk of developing lung cancer was approximately 60 times greater for smokers than for non-smokers.

  5. (210)Po in drinking water, its potential health effects, and inadequacy of the gross alpha activity MCL.

    PubMed

    Seiler, Ralph

    2016-10-15

    Polonium-210 ((210)Po) is a naturally-occurring, carcinogenic member of the (238)U decay series and the granddaughter of (210)Pb. It has a half life of 138.4days and is rarely found in drinking water at levels exceeding 5mBq/L because it strongly binds to aquifer sediment. When the current US Maximum Contaminant Level (MCL) covering (210)Po was promulgated in December 2000, very little was known about its occurrence and the processes responsible for mobilizing it. More is now known about the processes that mobilize (210)Po from sediments and a review of recent occurrence data show that it may not be as rare in the US as the US Environmental Protection Agency (USEPA) thought in 2000. Worldwide, only about 2200 analyses for (210)Po in drinking water were identified, with activities exceeding 500mBq/L being found only in Finland, India, Sweden, and the US. The median of 400 (210)Po analyses from the US is 4.75mBq/L and >10% of the samples exceed 500mBq/L. Current compliance-monitoring regulations in the US essentially guarantee that (210)Po contamination will not be detected except in very contaminated wells. Major problems with the US Gross Alpha Activity MCL include the volatility of (210)Po and extended holding times and sample-compositing methods that can allow the majority of (210)Po in a sample bottle to decay before analysis. In light of new information, the radionuclide rule should be changed and direct measurements of (210)Po should be made in all public-water supply wells to rule out its presence. Much of the important biological and toxicological research on (210)Po is more than four decades old and new laboratory research using modern tools is needed. Biological and epidemiological investigations of known contaminated areas are needed to assess the effect (210)Po exposure is having on animals and humans consuming the water. PMID:27369089

  6. Customer Support Operations In Support Of The NASA/JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC)

    NASA Astrophysics Data System (ADS)

    Heinz, S. L.; Chen, Y. M.

    2004-12-01

    PO.DAAC is responsible for the ingest, archive and distribution of data relevant to the physical state of the ocean. The PO.DAAC provides a level of service for customer support for core Earth Observing System Data Information System (EOSDIS) missions such as TOPEX/POSEIDON, Jason, SeaWinds on QuikSCAT, SeaWinds on ADEOS-II, NOAA AVHRR and MODIS. PO.DAAC's level of support has broadened recently to include missions outside of the EOSDIS including, WindSat, GHRSST, Naval Oceanographic, Monterey Bay Aquarium, AirSAR and GOES. Customer support operations is managed and conducted in partnership between Raytheon ITSS and JPL and includes a full complement of services to accommodate the various PO.DAAC and Earth Observing System user communities. Customer support activities are ubiquitous to service industries from banking to shopping and this presentation will detail how two operational applications have been adopted for use in Earth Science data communities. Customer Response Management Operations System Integrated system that combines PO.DAAC's communications channels including web, email, phone and personal interactions into one intelligent knowledge base. The knowledge is shared with customers and the entire team to deliver consistent and timely information. The system allows 24 x 7 customer support service via extensive on-line searchable knowledge base. PO.DAAC has customized the system to fully integrate with PO.DAAC's existing legacy database and order tracking system. Website Communication Channel The newly redesigned PO.DAAC website (http://podaac.jpl.nasa.gov) is the central gateway to all of the Data, Tools and Services offered at the data center. The consistent look and feel was developed to enhance the ease of searching and ordering earth science data in particular. Data is accessible within a few clicks using the improved dynamic data catalog interface. New data products and information are delivered quickly to customers via the dynamic system and

  7. Point of departure (PoD) selection for the derivation of acceptable daily exposures (ADEs) for active pharmaceutical ingredients (APIs).

    PubMed

    Bercu, Joel P; Morinello, Eric J; Sehner, Claudia; Shipp, Bryan K; Weideman, Patricia A

    2016-08-01

    The Acceptable Daily Exposure (ADE) derived for pharmaceutical manufacturing is a health-based limit used to ensure that medicines produced in multi-product facilities are safe and are used to validate quality processes. Core to ADE derivation is selecting appropriate point(s) of departure (PoD), i.e., the starting dose of a given dataset that is used in the calculation of the ADE. Selecting the PoD involves (1) data collection and hazard characterization, (2) identification of "critical effects", and (3) a dose-response assessment including the determination of the no-observed-adverse-effect-level (NOAEL) or lowest-observed-adverse-effect-level (LOAEL), or calculating a benchmark dose (BMD) level. Compared to other classes of chemicals, active pharmaceutical ingredients (APIs) are well-characterized and have unique, rich datasets that must be considered when selecting the PoD. Dataset considerations for an API include therapeutic/pharmacological effects, particularities of APIs for different indications and routes of administration, data gaps during drug development, and sensitive subpopulations. Thus, the PoD analysis must be performed by a qualified toxicologist or other expert who also understands the complexities of pharmaceutical datasets. In addition, as the pharmaceutical industry continues to evolve new therapeutic principles, the science behind PoD selection must also evolve to ensure state-of-the-science practices and resulting ADEs.

  8. Natural variation in 210Po and 210Pb activity concentrations in the urine of Finnish population groups.

    PubMed

    Muikku, Maarit; Heikkinen, Tarja; Solatie, Dina; Vesterbacka, Pia

    2011-11-01

    A study to determine activity concentrations of (210)Pb and (210)Po in the urine of certain Finnish population groups was conducted, to investigate the variation in natural background level of urinary excretion. The study participants were divided into three groups mainly based on their diet. The first group comprised recreational fishermen and the second group represented people consuming more reindeer meat than an average Finn, while people using drinking water with very high activity concentrations of (210)Po were selected for the third group. The fourth group was a control group. The mean urinary excretion of (210)Po in groups 1 and 2 was 73 and 100 mBq d(-1), respectively. These values were higher than the value of the control group (20 mBq d(-1)) and the mean values reported in the literature. The mean daily urinary excretion of (210)Pb in groups 1 and 2, 70 and 52 mBq d(-1), was also slightly higher than that in the control group (32 mBq d(-1)). In contrast, the excretion rates of both (210)Po and (210)Pb for the members of group 3 were one to two orders of magnitude higher than those reported in the literature. This was clearly due to the elevated levels of natural radionuclides in their drinking water. The present study demonstrates the importance of possessing good knowledge of the background levels, in order to allow the determination of the additional exposure due, for example, to the malevolent use of radiation.

  9. Radioluminescence properties of Ce 3+-activated MGd(PO 3) 4 (M = Li, Na, K, Cs)

    NASA Astrophysics Data System (ADS)

    Zhong, Jiuping; Liang, Hongbin; Su, Qiang; Zhou, Jianying; Khodyuk, Ivan V.; Dorenbos, Pieter

    2009-12-01

    Rare-earth phosphates MGd(PO 3) 4:1.0 mol% Ce 3+ (M = Li, Na, K, Cs) powder samples were prepared by a solid-state reaction technique at high temperature. The radioluminescence spectra and light-yield characteristic of MGd(PO 3) 4:Ce 3+ under X-ray irradiation were determined. It was found that, from LiGd(PO 3) 4:Ce 3+ to CsGd(PO 3) 4:Ce 3+, with the increasing of M + radius, the doublet emission energy of Ce 3+ ions decrease gradually but the light-yield increase significantly. Especially, CsGd(PO 3) 4:1.0 mol% Ce 3+ has the highest X-ray excited light-yield of 24,400 photons/MeV with maximal emission peaks at 337 nm and 358 nm at room temperature. Due to its suitable emission wavelength range, high light-yield, high chemical stability and fast luminescence decay of Ce 3+ emission, CsGd(PO 3) 4:Ce 3+ may be a promising scintillation material.

  10. Sinuosity change of the Po River near Cremona (Northern Italy) - a result of neotectonic activity?

    NASA Astrophysics Data System (ADS)

    Petrovszki, Judit; Timár, Gábor

    2010-05-01

    In the map sheets of the Second Military Survey of the Habsburg Empire, Lombardia, Parma, Modena and Venice also can be seen (Timár et al., 2006). This area was surveyed between 1818 and 1829. In these map sheets, we can also follow the river Po from Vaccarizza to the delta. This river reach is about 350 km long. This river reach was digitized and sinuosity values were calculated with different window sizes, and displayed in a spectrum-like diagram (sinuosity spectra; after van Balen et al., 2008). At Cremona, a significante sinuosity change were identified. The sinuosity increasing, and we have high sinuosity values. In the summarizing geological map of Italy (Compagnoni and Calluzzo, 2004), at this place, a tectonic line was identified. So probably this fault line invokes the sinuosity change on the river. The vertical movements indicated on the maps are just the opposite like they would be according to the flume experiments of Ouchi (1985). In the case of the Po River at Cremona, the decrease of the channel slope results higher sinuosity. The reason is that the rate of the slope and water discharge is higher than it is required by the self-organized meandering and the river parameters fell to the range of the unorganized meandering (cf. Timár, 2003). Another possible explanation could be that the northern tributary, the Adda River has significant sediment load that lowers the sinuosity of the trunk river at the confluence. Compagnoni, B., Galluzzo, F. (eds., 2004): Geological Map of Italy. Agenzia per la Protezione dell'Ambiente per I Servizi Tecnici - Dipartimento Difesa del Suolo, Servizio Geologico d'Italia, Rome-Florence-Genoa. Map, scale=1:1250000, especially printed for the 32nd International Geological Congress. Ouchi, S. (1985): Response of alluvial rivers to slow active tectonic movement. Geol. Soc. Am. Bull. 96: 504-515. Timár, G. (2003): Controls on channel sinuosity changes: a case study of the Tisza River, the Great Hungarian Plain. Quaternary

  11. Transcriptomic Analysis of Musca domestica to Reveal Key Genes of the Prophenoloxidase-Activating System.

    PubMed

    Li, Dianxiang; Liang, Yongli; Wang, Xianwei; Wang, Lei; Qi, Mei; Yu, Yang; Luan, Yuanyuan

    2015-09-01

    The proPO system regulates melanization in arthropods. However, the genes that are involved in the proPO system in housefly Musca domestica remain unclear. Thus, this study analyzed the combined transcriptome obtained from M. domestica larvae, pupae, and adults that were either normal or bacteria-challenged by an Escherichia coli and Staphylococcus aureus mixture. A total of 54,821,138 clean reads (4.93 Gb) were yielded by Illumina sequencing, which were de novo assembled into 89,842 unigenes. Of the 89,842 unigenes, based on a similarity search with known genes in other insects, 24 putative genes related to the proPO system were identified. Eight of the identified genes encoded for peptidoglycan recognition receptors, two encoded for prophenoloxidases, three encoded for prophenoloxidase-activating enzymes, and 11 encoded for serine proteinase inhibitors. The expression levels of these identified genes were investigated by qRT-PCR assay, which were consistent with expected activation process of the proPO system, and their activation functions were confirmed by the measurement of phenoloxidase activity in bacteria-infected larvae after proPO antibody blockage, suggesting these candidate genes might have potentially different roles in the activation of proPO system. Collectively, this study has provided the comprehensive transcriptomic data of an insect and some fundamental basis toward achieving understanding of the activation mechanisms and immune functions of the proPO system in M. domestica.

  12. Transcriptomic Analysis of Musca domestica to Reveal Key Genes of the Prophenoloxidase-Activating System

    PubMed Central

    Li, Dianxiang; Liang, Yongli; Wang, Xianwei; Wang, Lei; Qi, Mei; Yu, Yang; Luan, Yuanyuan

    2015-01-01

    The proPO system regulates melanization in arthropods. However, the genes that are involved in the proPO system in housefly Musca domestica remain unclear. Thus, this study analyzed the combined transcriptome obtained from M. domestica larvae, pupae, and adults that were either normal or bacteria-challenged by an Escherichia coli and Staphylococcus aureus mixture. A total of 54,821,138 clean reads (4.93 Gb) were yielded by Illumina sequencing, which were de novo assembled into 89,842 unigenes. Of the 89,842 unigenes, based on a similarity search with known genes in other insects, 24 putative genes related to the proPO system were identified. Eight of the identified genes encoded for peptidoglycan recognition receptors, two encoded for prophenoloxidases, three encoded for prophenoloxidase-activating enzymes, and 11 encoded for serine proteinase inhibitors. The expression levels of these identified genes were investigated by qRT-PCR assay, which were consistent with expected activation process of the proPO system, and their activation functions were confirmed by the measurement of phenoloxidase activity in bacteria-infected larvae after proPO antibody blockage, suggesting these candidate genes might have potentially different roles in the activation of proPO system. Collectively, this study has provided the comprehensive transcriptomic data of an insect and some fundamental basis toward achieving understanding of the activation mechanisms and immune functions of the proPO system in M. domestica. PMID:26156588

  13. Emerging and priority contaminants with endocrine active potentials in sediments and fish from the River Po (Italy).

    PubMed

    Luigi, Viganò; Giuseppe, Mascolo; Claudio, Roscioli

    2015-09-01

    There is a substantial lack of information on most priority pollutants, related contamination trends, and (eco)toxicological risks for the major Italian watercourse, the River Po. Targeting substances of various uses and origins, this study provides the first systematic data for the River Po on a wide set of priority and emerging chemicals, all characterized by endocrine-active potentials. Flame retardants, natural and synthetic hormones, surfactants, personal care products, legacy pollutants, and other chemicals have been investigated in sediments from the River Po and its tributary, the River Lambro, as well as in four fish species from the final section of the main river. With few exceptions, all chemicals investigated could be tracked in the sediments of the main Italian river for tens or hundreds of kilometres downstream from the Lambro tributary. Nevertheless, the results indicate that most of these contaminants, i.e., TBBPA, TCBPA, TBBPA-bis, DBDPE, HBCD, BPA, OP, TCS, TCC, AHTN, HHCB, and DDT, individually pose a negligible risk to the River Po. In contrast, PBDE, PCB, natural and synthetic estrogens, and to a much lower extent NP, were found at levels of concern either to aquatic life or human health. Adverse biological effects and prohibition of fish consumption deserve research attention and management initiatives, also considering the transport of contaminated sediments to transitional and coastal environments of the Italian river. PMID:25956513

  14. BiPO{sub 4}/BiOBr p–n junction photocatalysts: One-pot synthesis and dramatic visible light photocatalytic activity

    SciTech Connect

    Liu, Zhang Sheng; Wu, Bian Tao; Niu, Ji Nan; Feng, Pei Zhong; Zhu, Ya Bo

    2015-03-15

    Highlights: • BiPO{sub 4}/BiOBr p–n junction photocatalysts were synthesized by a solvothermal method. • BiPO{sub 4}/BiOBr composites were constructed by inlaying BiPO{sub 4} particles into BiOBr microspheres. • BiPO{sub 4}/BiOBr photocatalysts exhibited the enhanced photocatalytic activity. • ·O{sub 2}{sup −} and h{sup +} were the main active species responsible for the degradation of RhB. - Abstract: BiPO{sub 4}/BiOBr p–n junction photocatalysts were successfully synthesized via a facile one-pot solvothermal method. The products were characterized by XRD, FE-SEM, HRTEM, XPS, DRS, PL and EIS. The obtained BiPO{sub 4}/BiOBr composites were constructed by inlaying BiPO{sub 4} nanoparticles into BiOBr hierarchical microspheres. Compared with BiPO{sub 4} and BiOBr, they exhibited significantly enhanced visible light photocatalytic activity towards the degradation of Rhodamine B (RhB). Among them, 10% BiPO{sub 4}/BiOBr showed the maximum value of the activity, whose degradation rate was about three times higher than that of pure BiOBr. The enhanced photocatalytic activity could be attributed to the formation of the BiPO{sub 4}/BiOBr p–n junction, which resulted in the effective separation and transfer of photogenerated electron–hole pairs. Moreover, the trapping experiments confirmed that ·O{sub 2}{sup −} and h{sup +} were the main active species responsible for the degradation of RhB.

  15. A high performance hybrid capacitor with Li2CoPO4F cathode and activated carbon anode

    NASA Astrophysics Data System (ADS)

    Karthikeyan, K.; Amaresh, S.; Kim, K. J.; Kim, S. H.; Chung, K. Y.; Cho, B. W.; Lee, Y. S.

    2013-06-01

    For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its initial value even after 30 000 C-D cycles. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described.For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its

  16. In situ fabrication of Ag3PO4/TiO2 nanotube heterojunctions with enhanced visible-light photocatalytic activity.

    PubMed

    Tong, Zhen Wei; Yang, Dong; Sun, Yuan Yuan; Tian, Yao; Jiang, Zhong Yi

    2015-05-14

    Ag3PO4/TiO2 nanotube (TNT) heterojunctions were fabricated via a facile in situ growth method. Hemispherical Ag3PO4 nanocrystals were uniformly grown on the TNT surface, and their size was confined to 5-10 nm. A joint area was distinctly observed between the Ag3PO4 nanocrystals and TNT, indicating the formation of a Ag3PO4/TNT heterojunction. Compared with pure Ag3PO4, the Ag3PO4/TNT heterojunction possesses more active sites, less bulk defects, more efficient electron-hole separation, as well as better dye adsorption properties, and thus exhibits a significantly elevated photocatalytic activity for Rhodamine B (RhB) degradation. The study of the reactive species demonstrates that the photocatalytic degradation of RhB over the Ag3PO4/TNT heterojunction is primarily driven by both photogenerated h(+) and ˙OH radicals. This easily-fabricated Ag3PO4/TNT heterojunction with promising photocatalytic activity may find potential applications in energy and environmental related areas. PMID:25884048

  17. In situ fabrication of Ag3PO4/TiO2 nanotube heterojunctions with enhanced visible-light photocatalytic activity.

    PubMed

    Tong, Zhen Wei; Yang, Dong; Sun, Yuan Yuan; Tian, Yao; Jiang, Zhong Yi

    2015-05-14

    Ag3PO4/TiO2 nanotube (TNT) heterojunctions were fabricated via a facile in situ growth method. Hemispherical Ag3PO4 nanocrystals were uniformly grown on the TNT surface, and their size was confined to 5-10 nm. A joint area was distinctly observed between the Ag3PO4 nanocrystals and TNT, indicating the formation of a Ag3PO4/TNT heterojunction. Compared with pure Ag3PO4, the Ag3PO4/TNT heterojunction possesses more active sites, less bulk defects, more efficient electron-hole separation, as well as better dye adsorption properties, and thus exhibits a significantly elevated photocatalytic activity for Rhodamine B (RhB) degradation. The study of the reactive species demonstrates that the photocatalytic degradation of RhB over the Ag3PO4/TNT heterojunction is primarily driven by both photogenerated h(+) and ˙OH radicals. This easily-fabricated Ag3PO4/TNT heterojunction with promising photocatalytic activity may find potential applications in energy and environmental related areas.

  18. Laccase 2 is the phenoloxidase gene required for beetle cuticle tanning

    PubMed Central

    Arakane, Yasuyuki; Muthukrishnan, Subbaratnam; Beeman, Richard W.; Kanost, Michael R.; Kramer, Karl J.

    2005-01-01

    Cuticle tanning (or sclerotization and pigmentation) in invertebrates involves the oxidative conjugation of proteins, which renders them insoluble and hardens and darkens the color of the exoskeleton. Two kinds of phenoloxidases, laccase and tyrosinase, have been proposed to participate in tanning, but proof of the true identity of the enzyme(s) responsible for this process has been elusive. We report the cloning of cDNAs for laccases and tyrosinases from the red flour beetle, Tribolium castaneum, as well as their developmental patterns of expression. To test for the involvement of these types of enzymes in cuticle tanning, we performed RNA interference experiments to decrease the levels of individual phenoloxidases. Normal phenotypes were obtained after dsRNA-mediated transcript depletion for all phenoloxidases tested, with the exception of laccase 2. Insects injected with dsRNA for the laccase 2 gene failed to tan, were soft-bodied and deformed, and subsequently died in a dsRNA dose-dependent fashion. The results presented here support the hypothesis that two isoforms of laccase 2 generated by alternative splicing catalyze larval, pupal, and adult cuticle tanning in Tribolium. PMID:16076951

  19. Fabrication of Z-scheme Ag3PO4/MoS2 composites with enhanced photocatalytic activity and stability for organic pollutant degradation

    NASA Astrophysics Data System (ADS)

    Zhu, Chaosheng; Zhang, Lu; Jiang, Bo; Zheng, Jingtang; Hu, Ping; Li, Sujuan; Wu, Mingbo; Wu, Wenting

    2016-07-01

    In this study, highly efficient visible-light-driven Ag3PO4/MoS2 composite photocatalysts with different weight ratios of MoS2 were prepared via the ethanol-water mixed solvents precipitation method and characterized by ICP, XRD, HRTEM, FE-SEM, BET, XPS, UV-vis DRS and PL analysis. Under visible-light irradiation, Ag3PO4/MoS2 composites exhibit excellent photocatalytic activity towards the degradation of organic pollutants in aqueous solution. The optimal composite with 0.648 wt% MoS2 content exhibits the highest photocatalytic activity, which can degrade almost all MB under visible-light irradiation within 60 min. Recycling experiments confirmed that the Ag3PO4/MoS2 catalysts had superior cycle performance and stability. The photocatalytic activity enhancement of Ag3PO4/MoS2 photocatalysts can be mainly ascribed to the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of Ag3PO4, Ag and MoS2, in which Ag particles act as the charge separation center. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag3PO4 by transferring the photogenerated electrons of Ag3PO4 to MoS2. The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts could be obtained from the active species trapping experiments and the photoluminescence technique.

  20. Excess of ²¹⁰polonium activity in the surface urban atmosphere. Part (1) fluctuation of the ²¹⁰Po excess in the air.

    PubMed

    Długosz-Lisiecka, Magdalena

    2015-02-01

    The concentrations of (210)Pb, (210)Bi, and (210)Po in the urban atmosphere of Lodz city were measured from February 2010 to May 2010 and from May 2011 to April 2012. The seasonal changes in the activity ratios for (210)Po/(210)Pb and (210)Bi/(210)Pb indicated that the observed fluctuations were independent of the concentration of tropospheric (210)Pb and its decay products, particularly (210)Po. A simple calculation method was proposed for the estimation of the excess of (210)Po in urban aerosols in relation to the fraction of its activity formed from (210)Pb. On the basis of the results obtained, it was concluded that a substantial part of the (210)Po in urban air did not come from the decay of atmospheric (222)Rn, but rather it was from artificial sources. The highest levels of measured total (210)Po activity were observed during the winter period. This observation suggests that the main source of (210)Po in the investigated region could be related to anthropogenic emissions from domestic heating systems and local coal power plants, rather than from other sources, such as soil resuspension or stratospheric air intrusion as usually suggested in the literature.

  1. Excess of ²¹⁰polonium activity in the surface urban atmosphere. Part (1) fluctuation of the ²¹⁰Po excess in the air.

    PubMed

    Długosz-Lisiecka, Magdalena

    2015-02-01

    The concentrations of (210)Pb, (210)Bi, and (210)Po in the urban atmosphere of Lodz city were measured from February 2010 to May 2010 and from May 2011 to April 2012. The seasonal changes in the activity ratios for (210)Po/(210)Pb and (210)Bi/(210)Pb indicated that the observed fluctuations were independent of the concentration of tropospheric (210)Pb and its decay products, particularly (210)Po. A simple calculation method was proposed for the estimation of the excess of (210)Po in urban aerosols in relation to the fraction of its activity formed from (210)Pb. On the basis of the results obtained, it was concluded that a substantial part of the (210)Po in urban air did not come from the decay of atmospheric (222)Rn, but rather it was from artificial sources. The highest levels of measured total (210)Po activity were observed during the winter period. This observation suggests that the main source of (210)Po in the investigated region could be related to anthropogenic emissions from domestic heating systems and local coal power plants, rather than from other sources, such as soil resuspension or stratospheric air intrusion as usually suggested in the literature. PMID:25567523

  2. Fungal spores and pollen in particulate matter collected during agricultural activities in the Po Valley (Italy).

    PubMed

    Telloli, Chiara; Chicca, Milvia; Leis, Marilena; Vaccaro, Carmela

    2016-08-01

    Airborne particulate matter (PM) containing fungal spores and pollen grains was sampled within a monitoring campaign of wheat threshing, plowing and sowing agricultural operations. Fungal spores and pollen grains were detected and identified on morphological basis. No studies were previously available about fungal spore and pollen content in agricultural PM in the Po Valley. Sampling was conducted in a Po Valley farmland in Mezzano (Ferrara, Italy). The organic particles collected were examined by scanning electron microscopy with energy dispersive X-ray spectrometer. Fungal spores and pollen grains were identified when possible at the level of species. The most frequent components of the organic particles sampled were spores of Aspergillus sp., which could represent a risk of developing allergies and aspergillosis for crop farmers. PMID:27521955

  3. Fabrication and efficient visible light-induced photocatalytic activity of Bi2MoO6/BiPO4 composite

    NASA Astrophysics Data System (ADS)

    Lin, Xue; Liu, Di; Guo, Xiaoyu; Sun, Nan; Zhao, Shuang; Chang, Limin; Zhai, Hongju; Wang, Qingwei

    2015-01-01

    Novel Bi2MoO6/BiPO4 composites with heterojunction structure were fabricated by a one-step hydrothermal method. The photocatalytic properties of Bi2MoO6/BiPO4 composites were evaluated by photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation (λ>420 nm). The results showed that Bi2MoO6/BiPO4 photocatalysts showed much higher photocatalytic activity for the Rh B degradation than the pure BiPO4 and Bi2MoO6 under visible light. The best photocatalytic performance of Bi2MoO6/BiPO4 with about 98.0% Rh B degradation located at molar ratio of 2:1 under visible light illumination for 30 min. The enhanced photocatalytic activity could be mainly ascribed to the formation of heterojunction interface in Bi2MoO6/BiPO4 composites, which is beneficial to the transfer and separation of photogenerated electron-hole pairs, as well as the strong visible light absorption resulting from the sensitization role of Bi2MoO6 to BiPO4. It was also observed that the photodegradation of Rh B is chiefly attributed to the oxidation action of the generated O2rad - radicals and the action of hvb+ through direct hole oxidation process.

  4. Graphene oxide wrapped Ag{sub 3}PO{sub 4} sub-microparticles with highly enhanced photocatalytic activity and stability under visible light irradiation

    SciTech Connect

    Xiu, Zhiliang; Wu, Yongzhong; Hao, Xiaopeng; Lu, Qifang; Liu, Suwen

    2014-11-15

    Highlights: • Graphene oxide wrapped Ag{sub 3}PO{sub 4} sub-microparticles were prepared. • The photocatalytic activity of Ag{sub 3}PO{sub 4} is increased by 6 times by GO wrapping. • The hybrid photocatalysts exhibited excellent stability. - Abstract: Graphene oxide (GO) wrapped Ag{sub 3}PO{sub 4} sub-microparticles were prepared by in situ deposition–precipitation method. By hybridization of Ag{sub 3}PO{sub 4} with GO nanosheets, a 6-fold enhancement in the photodegradation rate toward orange methyl (MO) under visible light irradiation (λ ≥ 420 nm) was observed compared with the pure Ag{sub 3}PO{sub 4} sub-microsparticles. The hybrid photocatalysts also exhibited excellent stability in the successive MO degradation experiments. The highly enhanced photocatalytic activity and stability were mainly attributed to the quick transfer of the photogenerated electrons from Ag{sub 3}PO{sub 4} to GO nanosheets, which could effectively suppress the electron–hole pairs recombination and thus inhibit the photocorrosion of Ag{sub 3}PO{sub 4}. These high-efficient and stable hybrid photocatalysts were expected to show considerable potential applications in wastewater treatment and water splitting.

  5. Atmospheric residence time of (210)Pb determined from the activity ratios with its daughter radionuclides (210)Bi and (210)Po.

    PubMed

    Semertzidou, P; Piliposian, G T; Appleby, P G

    2016-08-01

    The residence time of (210)Pb created in the atmosphere by the decay of gaseous (222)Rn is a key parameter controlling its distribution and fallout onto the landscape. These in turn are key parameters governing the use of this natural radionuclide for dating and interpreting environmental records stored in natural archives such as lake sediments. One of the principal methods for estimating the atmospheric residence time is through measurements of the activities of the daughter radionuclides (210)Bi and (210)Po, and in particular the (210)Bi/(210)Pb and (210)Po/(210)Pb activity ratios. Calculations used in early empirical studies assumed that these were governed by a simple series of equilibrium equations. This approach does however have two failings; it takes no account of the effect of global circulation on spatial variations in the activity ratios, and no allowance is made for the impact of transport processes across the tropopause. This paper presents a simple model for calculating the distributions of (210)Pb, (210)Bi and (210)Po at northern mid-latitudes (30°-65°N), a region containing almost all the available empirical data. By comparing modelled (210)Bi/(210)Pb activity ratios with empirical data a best estimate for the tropospheric residence time of around 10 days is obtained. This is significantly longer than earlier estimates of between 4 and 7 days. The process whereby (210)Pb is transported into the stratosphere when tropospheric concentrations are high and returned from it when they are low, significantly increases the effective residence time in the atmosphere as a whole. The effect of this is to significantly enhance the long range transport of (210)Pb from its source locations. The impact is illustrated by calculations showing the distribution of (210)Pb fallout versus longitude at northern mid-latitudes. PMID:27132252

  6. Atmospheric residence time of (210)Pb determined from the activity ratios with its daughter radionuclides (210)Bi and (210)Po.

    PubMed

    Semertzidou, P; Piliposian, G T; Appleby, P G

    2016-08-01

    The residence time of (210)Pb created in the atmosphere by the decay of gaseous (222)Rn is a key parameter controlling its distribution and fallout onto the landscape. These in turn are key parameters governing the use of this natural radionuclide for dating and interpreting environmental records stored in natural archives such as lake sediments. One of the principal methods for estimating the atmospheric residence time is through measurements of the activities of the daughter radionuclides (210)Bi and (210)Po, and in particular the (210)Bi/(210)Pb and (210)Po/(210)Pb activity ratios. Calculations used in early empirical studies assumed that these were governed by a simple series of equilibrium equations. This approach does however have two failings; it takes no account of the effect of global circulation on spatial variations in the activity ratios, and no allowance is made for the impact of transport processes across the tropopause. This paper presents a simple model for calculating the distributions of (210)Pb, (210)Bi and (210)Po at northern mid-latitudes (30°-65°N), a region containing almost all the available empirical data. By comparing modelled (210)Bi/(210)Pb activity ratios with empirical data a best estimate for the tropospheric residence time of around 10 days is obtained. This is significantly longer than earlier estimates of between 4 and 7 days. The process whereby (210)Pb is transported into the stratosphere when tropospheric concentrations are high and returned from it when they are low, significantly increases the effective residence time in the atmosphere as a whole. The effect of this is to significantly enhance the long range transport of (210)Pb from its source locations. The impact is illustrated by calculations showing the distribution of (210)Pb fallout versus longitude at northern mid-latitudes.

  7. Graphite-like C3N4 modified Ag3PO4 nanoparticles with highly enhanced photocatalytic activities under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Xiu, Zhiliang; Bo, Hai; Wu, Yongzhong; Hao, Xiaopeng

    2014-01-01

    Graphite-like C3N4 (g-C3N4) modified Ag3PO4 nanoparticles with highly enhanced photocatalytic activities under visible light irradiation (λ ≥ 400 nm) compared to the bare Ag3PO4 nanoparticles were prepared by a facile chemisorption method. The resulting C3N4/Ag3PO4 composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible diffuse reflectance spectra (DRS). Enhanced charge separation efficiency was confirmed by electrochemical impedance spectroscopy (EIS) measurements. The enhanced photocatalytic activities were mainly ascribed to the synergistic effect between C3N4 and Ag3PO4 which led to an improved separation efficiency of electron-hole pairs. The high-efficient hybrid photocatalysts are expected to show considerable potential applications in wastewater treatment and water splitting.

  8. Synthesis and characterization of high photocatalytic activity and stable Ag3PO4/TiO2 fibers for photocatalytic degradation of black liquor

    NASA Astrophysics Data System (ADS)

    Cai, Li; Long, Qiyi; Yin, Chao

    2014-11-01

    The TiO2 fiber was prepared by using cotton fiber as a template, and then Ag3PO4/TiO2 fibers were synthesized via in situ Ag3PO4 particles onto the surface of TiO2 fiber. Their structure and physical properties were characterized by means of scanning electron microscopy (SEM), specific surface analyzer, X-ray diffraction (XRD), UV-vis absorption spectra and photoluminescence spectra (PL). SEM analysis indicated that the well-defined surface morphology of natural cotton fiber was mostly preserved in TiO2 and Ag3PO4/TiO2 fibers. Compared with TiO2 fiber, the absorbance wavelengths of Ag3PO4/TiO2 fibers were apparently red shifted and the PL intensities revealed a significant decrease. By using the photocatalytic degradation of black liquor as a model reaction, the visible light and ultraviolet light catalytic efficiencies of TiO2, Ag3PO4 and Ag3PO4/TiO2 fibers were evaluated. The reaction results showed that Ag3PO4/TiO2 fibers had stronger photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared Ag3PO4/TiO2 fibers could act as an efficient catalyst for the photocatalytic degradation of black liquor, which suggested their promising applications. It was proposed that the •OH radicals played the leading role in the photocatalytic degradation of the black liquor by Ag3PO4/TiO2 fibers system.

  9. Preparation, characterization and enhanced visible-light photocatalytic activities of BiPO{sub 4}/BiVO{sub 4} composites

    SciTech Connect

    Wu, Siyuan; Zheng, Hong Lian, Youwei; Wu, Yiying

    2013-08-01

    Graphical abstract: - Highlights: • BiPO{sub 4}/BiVO{sub 4} composites were successfully prepared by the hydrothermal method. • BiPO{sub 4}/BiVO{sub 4} composites exhibited broad absorption in the visible region. • Visible-light photocatalytic activities of BiPO{sub 4}/BiVO{sub 4} composites were enhanced. • P/V molar ratio and pH value of the reaction affect photocatalytic activity. • The mechanism of enhanced visible-light photocatalytic activities was discussed. - Abstract: BiPO{sub 4}/BiVO{sub 4} composites with different P/V molar ratios were prepared by the hydrothermal method and the effect of pH values of hydrothermal reaction on photocatalytic activity of BiPO{sub 4}/BiVO{sub 4} composite was investigated. The photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic property of BiPO{sub 4}/BiVO{sub 4} was evaluated by photocatalytic degradation of Methylene blue under visible light irradiation. The results showed that the photocatalytic activity of the composites was much higher than that of pure BiPO{sub 4} and BiVO{sub 4}. The rate constant of Methylene blue degradation over BiPO{sub 4}/BiVO{sub 4} (P/V molar ratio of 5:1 and hydrothermal reaction pH value of 1.5) is 1.7 times that of pure BiVO{sub 4}. The photocatalytic activity enhancement of BiPO{sub 4}/BiVO{sub 4} composite is closely related to the BiVO{sub 4} functioning as a sensitizer to adsorb visible light and the heterojunction of BiPO{sub 4}/BiVO{sub 4} acting as an active center for hindering the rapid recombination of electron–hole pairs during the photocatalytic reaction.

  10. A chemical bath deposition route to facet-controlled Ag3PO4 thin films with improved visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B.; Pyun, Jae.-Chul.; Hwang, Seong-Ju

    2016-08-01

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag3PO4 thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag3PO4 nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag3PO4 from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag+]/[phosphate] ratio enables to maximize the loading amount of Ag3PO4 crystals per the unit area of the deposited film. All the fabricated Ag3PO4 thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag3PO4-ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid.

  11. Seasonal and spatial variations of 210Po and 210Pb activity concentrations in Mytilus galloprovincialis from Croatian coast of the Adriatic Sea.

    PubMed

    Rožmarić, Martina; Rogić, Matea; Benedik, Ljudmila; Štrok, Marko; Barišić, Delko

    2013-11-01

    Results of 2 years monitoring of (210)Po and (210)Pb activity concentrations in soft tissue of the species Mytilus galloprovincialis from Croatian part of the Adriatic coast are presented. The samples were collected at thirteen coastal stations (some of which are also a part of the Mediterranean Mussel Watch Project) in spring and autumn of 2010 and 2011. The collected mussels were ranging between 4 cm and 6 cm in shell length. After sample pre-treatment lead and polonium were radiochemically separated on Sr resin. (210)Po was determined by alpha-particle spectrometry and (210)Pb was determined, via (210)Bi, by a low-level gas proportional counter. The results of (210)Po activity concentrations were found to vary between (104±11) and (1421±81) Bq kg(-1) dry weight while (210)Pb activity concentrations were much lower and in range (8.2±5.3)-(94.1±29.8) Bq kg(-1) dry weight. Higher (210)Po and (210)Pb activity concentrations were determined in spring period. The inter-site differences seen in their activity concentrations can be due to natural background levels of sites. The (210)Po/(210)Pb activity concentration ratios in all cases exceeded unity for all mussel samples and ranged between 4.0 and 47.9.

  12. A novel Bi-based phosphomolybdate photocatalyst K{sub 2}Bi(PO{sub 4})(MoO{sub 4}): Crystal structure, electronic structure and photocatalytic activity

    SciTech Connect

    Huang, Hongwei; Chen, Gong; Wang, Shuobo; Kang, Lei; Lin, Zheshuai; Zhang, Yihe

    2014-03-01

    Graphical abstract: - Highlights: • A new type of phosphomolybdate K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) photocatalyst was successfully synthesized. • The products synthesized at 600 °C were mainly composed of nano-cubes. • The indirect band gap of K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) has been determined to be 2.93 eV. • K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) synthesized at 600 °C exhibits the highest photocatalytic activity. • The electronic structure was calculated by density functional calculations. - Abstract: A novel phosphomolybdate photocatalyst K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) has been successfully developed via a solid-state reaction. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectrum (DRS) and photoluminescence (PL) spectra. The photocatalytic activities of the samples prepared at different temperature were determined by the photooxidative decomposition of methylene blue (MB) in aqueous solution. The results revealed that K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) can be used as an effective photocatalyst under UV–vis irradiation and the nanocubes obtained at 600 °C exhibits the highest photocatalytic activity. The photodegradation of MB by K{sub 2}Bi(PO{sub 4})(MoO{sub 4}) nanocrystals followed the first-order kinetics. Theoretical calculations on electronic structure confirmed the indirect optical transitions property in the absorption edge region of K{sub 2}Bi(PO{sub 4})(MoO{sub 4}), and the orbital constitutions of CB and VB were also analyzed.

  13. Studies on enzymic browning of potatoes (Solanum tuberosum). III. Kinetics of potato phenoloxidase (EC 1.14.18.1 monophenol, dihydroxyphenylalanine: oxygen-oxidoreductase).

    PubMed

    Matheis, G; Belitz, H D

    1977-03-21

    From initial velocity studies a sequential mechanism for the reactions catalysed by phenoloxidase from potatoes is indicated. The data are in accordance with an ordered addition of oxygen and phenolic substrate to the enzyme, with oxygen being the first substrate bound at thermodynamic equilibrium. The Michaelis constants for L-tyrosine, L-dopa, and chlorogenic acid are 1.4 X 10(-3), 3.3 X 10(-4), and 1.4 X 10(-4) mol/l, respectively. The dissociation constant for the enzyme-oxygen complex is about 10(-3) mol/l. In the presence of chlorogenic acid no lag phase occurs in the course of L-tyrosine oxidation. With increasing amounts of chlorogenic acid the tyrosinase activity goes through a maximum. The significance of these findings for the in vivo action of the enzyme is discussed. PMID:404777

  14. Geochemical characterization and biomonitoring of reclaimed soils in the Po River Delta (Northern Italy): implications for the agricultural activities.

    PubMed

    Di Giuseppe, Dario; Bianchini, Gianluca; Vittori Antisari, Livia; Martucci, Annalisa; Natali, Claudio; Beccaluva, Luigi

    2014-05-01

    This geochemical study is focused on the easternmost part of the Po River alluvial plain in Northern Italy, which is interested by widespread agricultural activities, investigating a reclaimed sector of the Province of Ferrara, known as "Valle del Mezzano" (Mezzano Low Land, hereafter reported as MLL) characterized by peat-rich soils. The chemical-mineralogical characterization of these reclaimed soils is important to compare the local geochemical backgrounds with those recorded in other sectors of the River Po plain and to monitor if the observed concentration exceeds critical thresholds. The reported analyses include (a) measurement of the soil salinity, (b) nutrient evaluation, (c) major and trace element concentrations carried out on bulk soils, (d) tests of metal extraction with both aqua regia and EDTA to highlight the distinct elemental mobility and (e) phyto-toxicological measurement of heavy metal concentrations in plants (Lactuca sativa acephala) grown on the studied soils. The results indicate (1) high soil salinity, often with drastic increase of sodium and chloride along the soil profiles, (2) high nitrogen content (in part related to anthropogenic activities) on superficial horizons and nitrate decrease along the soil profiles and (3) comparative enrichments in heavy metals with respect to other soils of the province, which indicate that peat deposits are effective in trapping metals from anthropogenic sources. This, in turn, implies potential geochemical risks for the agricultural activities. In this regard, specific concerns are related to the high nickel and arsenic content of MLL soils due to the mobility of these elements and their attitude to be taken up by plants.

  15. Selectively enhanced expression of prophenoloxidase activating enzyme 1 (PPAE1) at a bacteria clearance site in the white shrimp, Litopenaeus vannamei

    PubMed Central

    2011-01-01

    Background The prophenoloxidase-activating (PO activating) system plays an important role in the crustacean innate immunity, particularly in wound healing and pathogen defense. A key member of this system is prophenoloxidase-activating enzyme (PPAE), which is the direct activator of prophenoloxidase (proPO). Despite their importance in crustacean PO activating system, the studies on them remain limited. Results Here we report on a PPAE of white shrimp, Litopenaeus vannamei (lvPPAE1), which showed 94% similarity to PPAE1 of Penaeus monodon. We found that lvPPAE1 in fluid hemocytes was down regulated after challenge by Vibrio harveyi but was enhanced when shrimps were exposed to a bacteria-rich environment for long-term. In vivo gene silence of lvPPAE1 by RNAi can significantly reduce the phenoloxidase activity (PO) and increase the susceptibility of shrimps to V. harveyi. Although lvPPAE1 was down-regulated in fluid hemocytes by Vibrio challenge, its expression increased significantly in gill after bacteria injection, which is the primary bacteria-clearance tissue. Conclusion Suppressed expression in fluid hemocytes and enhanced expression in gill indicates selectively enhanced expression at the bacterial clearance site. This is a novel feature for PPAE expression. The results will contribute to our understanding of the PO activating system in crustaceans. PMID:22208405

  16. IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF TWO SERINE PROTEASES AND THEIR POTENTIAL INVOLVEMENT IN PROPHENOLOXIDASE ACTIVATION IN Plutella xylostella.

    PubMed

    Gao, Gang; Xu, Xiao-Xia; Yu, Jing; Li, Lin-Miao; Ju, Wen-Yan; Jin, Feng-Liang; Freed, Shoaib

    2016-09-01

    The proteolytic activation of prophenoloxidase (proPO) is a humoral defense mechanism in insects and crustaceans. Phenoloxidase (PO) is produced as an inactive precursor namely, proPO and is activated via specific proteolytic cleavage by proPO-activating proteinase. The current research reports two novel serine proteinase genes (PxSP1-768 bp and PxSP2-816 bp) from Plutella xylostella, encoding 255 and 271 amino acid residues, respectively. Tissue distribution analyses by semiquantitative reverse transcription-PCR (RT-PCR) revealed the resultant genes to be primarily expressed in the hemocytes, while quantitative-RT-PCR (qRT-PCR) assay showed that transcription level of PxSP1 and PxSP2 increased significantly after injection of the fungal pathogen Beauveria bassiana. Purified recombinant fusion proteins of PxSP2 and PxSP1 were injected to New Zealand white rabbits and polyclonal antibodies were generated with the titers of 1:12,800. After silencing the expression of PxSP2 by RNAi, the PO activity decreased significantly. The results show that PxSP2 is involved in prophenoloxidase activation in P. xylostella. PMID:27306978

  17. Modification of the activity of Mg{sub 3}(PO{sub 4}){sub 2} in the gas-phase conversion of cyclohexanol by addition of sodium carbonate

    SciTech Connect

    Aramendia, M.A.; Borau, V.; Jimenez, C.

    1995-11-01

    This paper reports the synthesis and characterization of solid NaMgPO{sub 4}, obtained by adding Na{sub 2}CO{sub 3} to freshly formed Mg{sub 3}(PO{sub 4}){sub 2}{center_dot}22H{sub 2}O. The magnesium orthophosphate was prepared by gelling an aqueous solution of MgCl{sub 2} and Na{sub 2}HPO{sub 4} with 3 N NaOH. The solid products thus obtained were characterized by using various structural (XRD), surface (XPS, DRIFT,BET), and morphological (SEM) elucidation techniques. The results show that the NaMgPO{sub 4} surface also contains Na{sub 2}CO{sub 3}, NaCl, and MgO, which endow it with increased activity and selectivity. Thus, Mg{sub 3}(PO{sub 4}){sub 2} yields cyclohexene (CHE) preferentially, and some cyclohexanone (CHONE), in the gas-phase conversion of cyclohexanol. On the other hand, NaMgPO{sub 4} produces CHONE selectively under the same reaction conditions. 61 refs., 9 figs., 4 tabs.

  18. Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

    2014-10-01

    A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

  19. Copper-induced oxidative damage to the prophenoloxidase-activating system in the freshwater crayfish Procambarus clarkii.

    PubMed

    Wei, Keqiang; Yang, Junxian

    2016-05-01

    Previous studies have demonstrated copper-induced proteins damage in gill and hepatopancreas of the freshwater crayfish Procambarus clarkii, but little information is available about its effects on key component of the innate defense in haemolymph. In the present study, we evaluated the relationship between oxidative carbonylation and prophenoloxidase-activating system (proPO-AS) activity, by exposing P. clarkii to sub-lethal concentrations (1/50, 1/12, 1/6 and 1/3 of the 96 h LC50) Cu(2+) up to 96 h. Six biomarkers of oxidative stress, i.e. reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), protein carbonyl (PC), malondialdehyde (MDA) and DNA-protein crosslinks (DPCs), and six indicators of immune status, i.e. total hemocyte counts (THCs), differential hemocyte counts (DHCs), hemocyanin (HC), prophenoloxidase (proPO), serine protease (SP) and phenoloxidase (PO), were determined in haemolymph. The results indicated that there was a significant increase (P < 0.05) in the levels of ROS, PC, MDA and DPCs accompanied by markedly decreased (P < 0.05) activities of proPO, SP, PO and HC in a dose and time dependent manner. The significant and positive correlations (P < 0.01) between ROS production and the formation of PC, MDA and DPCs were observed in crayfish at 96 h. There was a significant negative correlation (P < 0.01) between the levels of protein carbonyls and the activities of proPO and SP in hemocyte lysate supernatant and PO and HC in haemolymph. Carbonylated proteins may be recognized not merely as a specific signal in oxidative stress pathways but also as a "non-self" molecule in proPO-AS. In crayfish species, copper-catalyzed protein carbonylation may be one of the main mechanisms for immunity dysfunction in proPO-AS. PMID:27033468

  20. Formation of disulfide bonds in insect prophenoloxidase enhances immunity through improving enzyme activity and stability.

    PubMed

    Lu, Anrui; Peng, Qin; Ling, Erjun

    2014-06-01

    Type 3 copper proteins, including insect prophenoloxidase (PPO), contain two copper atoms in the active site pocket and can oxidize phenols. Insect PPO plays an important role in immunity. Insects and other invertebrates show limited recovery from pathogen invasion and wounds if phenoloxidase (PO) activity is low. In most insect PPOs, two disulfide bonds are present near the C-terminus. However, in Pimpla hypochondriaca (a parasitoid wasp), each PPO contains one disulfide bond. We thus questioned whether the formation of two sulfide bonds in insect PPOs improved protein stability and/or increased insect innate immunity over time. Using Drosophila melanogaster PPO1 as a model, one or two disulfide bonds were deleted to evaluate the importance of disulfide bonds in insect immunity. rPPO1 and mutants lacking disulfide bonds could be expressed and showed PO activity. However, the PO activities of mutants lacking one or two disulfide bonds significantly decreased. Deletion of disulfide bonds also reduced PPO thermostability. Furthermore, antibacterial activities against Escherichia coli and Bacillus subtilis significantly decreased when disulfide bonds were deleted. Therefore, the formation of two disulfide bond(s) in insect PPO enhances antibacterial activity by increasing PO activity and stability.

  1. Preparation and textural characterisation of activated carbon from vine shoots ( Vitis vinifera) by H 3PO 4—Chemical activation

    NASA Astrophysics Data System (ADS)

    Corcho-Corral, B.; Olivares-Marín, M.; Fernández-González, C.; Gómez-Serrano, V.; Macías-García, A.

    2006-06-01

    An abundant and low-cost agricultural waste as vine shoots ( Vitis vinifera) (VS), which is generated by the annual pruning of vineyards, has been used as raw material in the preparation of powder activated carbon (AC) by the method of chemical activation with phosphoric acid. After size reduction, VS were impregnated for 2 h with 60 wt.% H 3PO 4 solution at room temperature, 50 and 85 °C. The three impregnated products were carbonised at 400 °C. The product impregnated at 50 °C was heated either first at 150-250 °C and then at 400 °C or simply at 350-550 °C in N 2 atmosphere. The time of isothermal treatment after each dynamic heating was 2 h. The carbons were texturally characterised by gas adsorption (N 2, -196 °C), mercury porosimetry, and density measurements. FT-IR spectroscopy was also applied. Better developments of surface area and microporosity are obtained when the impregnation of VS with the H 3PO 4 solution is effected at 50 °C and for the products heated isothermally at 200 and 450 °C. The mesopore volume is also usually higher for the products impregnated and heated at intermediate temperatures.

  2. Photoluminescence properties of Eu(3+)/ Sm(3+) activated CaZr4(PO4)6 phosphors.

    PubMed

    Nair, Govind B; Dhoble, S J

    2016-09-01

    Solid state reaction method was employed for the synthesis of a series of CaZr4(PO4)6: Eu(3+)/Sm(3+) phosphors. The red-emitting CaZr4(PO4)6:Eu(3+) phosphors can be efficiently excited at 396 nm and thereby, exhibit a strong red luminescence predominantly corresponding to the electric dipole transition at 615 nm. Under 405 nm excitation, CaZr4(PO4)6:Sm(3+) phosphors display orange emission with color temperatures approximately around 2200 K. The acquired results reveal that CaZr4(PO4)6: RE(3+) (RE = Eu, Sm) phosphors could be potential candidates for red and orange emitting phosphor, respectively, for UV/blue-pump LEDs. PMID:27411525

  3. Photoluminescence properties of Eu(3+)/ Sm(3+) activated CaZr4(PO4)6 phosphors.

    PubMed

    Nair, Govind B; Dhoble, S J

    2016-09-01

    Solid state reaction method was employed for the synthesis of a series of CaZr4(PO4)6: Eu(3+)/Sm(3+) phosphors. The red-emitting CaZr4(PO4)6:Eu(3+) phosphors can be efficiently excited at 396 nm and thereby, exhibit a strong red luminescence predominantly corresponding to the electric dipole transition at 615 nm. Under 405 nm excitation, CaZr4(PO4)6:Sm(3+) phosphors display orange emission with color temperatures approximately around 2200 K. The acquired results reveal that CaZr4(PO4)6: RE(3+) (RE = Eu, Sm) phosphors could be potential candidates for red and orange emitting phosphor, respectively, for UV/blue-pump LEDs.

  4. Manduca sexta proprophenoloxidase activating proteinase-3 (PAP3) stimulates melanization by activating proPAP3, proSPHs, and proPOs

    PubMed Central

    Wang, Yang; Lu, Zhiqiang; Jiang, Haobo

    2014-01-01

    Melanization participates in various insect physiological processes including antimicrobial immune responses. Phenoloxidase (PO), a critical component of the enzyme system catalyzing melanin formation, is produced as an inactive precursor prophenoloxidase (proPO) and becomes active via specific proteolytic cleavage by proPO activating proteinase (PAP). In Manduca sexta, three PAPs can activate proPOs in the presence of two serine proteinase homologs (SPH1 and SPH2). While the hemolymph proteinases (HPs) that generate the active PAPs are known, it is unclear how the proSPHs (especially proSPH1) are activated. In this study, we isolated from plasma of bar-stage M. sexta larvae an Ile-Glu-Ala-Arg-p-nitroanilide hydrolyzing enzyme that cleaved the proSPHs. This proteinase, PAP3, generated active SPH1 and SPH2, which function as cofactors for PAP3 in proPO activation. Cleavage of the purified recombinant proSPHs by PAP3 yielded 38 kDa bands similar in mobility to the SPHs formed in vivo. Surprisingly, PAP3 also can activate proPAP3 to stimulate melanization in a direct positive feedback loop. The enhanced proPO activation concurred with the cleavage activation of proHP6, proHP8, proPAP1, proPAP3, proSPH1, proSPH2, proPOs, but not proHP14 or proHP21. These results indicate that PAP3, like PAP1, is a key factor of the self-reinforcing mechanism in the proPO activation system, which is linked to other immune responses in M. sexta. PMID:24768974

  5. Staining electrophoretic gels for laccase and peroxidase activity using 1,8-diaminonaphthalene.

    PubMed

    Hoopes, J T; Dean, J F

    2001-06-01

    A new chromogenic substrate for laccases and peroxidases, 1,8-diaminonapthalene, was used to detect phenoloxidase activity in gels after SDS-PAGE. This substrate has several advantages over other widely used phenoloxidase stains in that it is inexpensive, and the oxidized product has both high molar absorptivity and very low solubility. Furthermore, neither the substrate nor the product is known to have toxicity problems of the type associated with many other phenoloxidase stains. The sensitivity of detection using 1,8-diaminonapthalene was comparable to that obtained using the most sensitive stains commonly used for phenoloxidases, e.g., 3,3-diaminobenzidine, and was close to that attainable for protein detection using silver staining. Zymograms developed with 1,8-diaminonapthalene can be used with video densitometry to monitor the specific enzymatic activity of phenoloxidases during enzyme purification. PMID:11373084

  6. Data Tools and Services at the NASA/JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC)

    NASA Astrophysics Data System (ADS)

    Sumagaysay-Aouda, R.; Bingham, A. W.; Chen, R. L.; Daffer, W. H.; Raskin, R.

    2004-12-01

    The PO.DAAC is responsible for archiving and distributing data relevant to the physical state of the ocean. PO.DAAC products, largely derived from satellite missions such as TOPEX/POSEIDON, Jason, GRACE, SeaWinds on QuikSCAT, SeaWinds on ADEOS-II, NOAA AVHRR, MODIS and GOES include ocean surface topography, ocean wind and sea surface temperature. To support users PO.DAAC provides various data tools and services that allow for subsetting by region and parameter, multiple output formats, global and regional quick-look of near-real-time data products, browse image and animation interfaces for selected data products, automated distribution of mission critical data, as well as use of a fast transport interface for downloading data. The following Data Tools and Services at the PO.DAAC will be highlighted: OCEANIDS (near-real-time data distribution), NEREIDS (near-real-time image distribution), POET (subsetting and vizualization interface), Selected Dataset Browse Image Tools, OPeNDAP (DODS) (remote data set access), VAP (scatterometry image and animation web server), EOS Data Gateway, Aspera Web Client Data Transfer Tool, and PO.DAAC's future release of a subscription interface for Seawinds on QuikSCAT data products.

  7. The synergetic effect of MoS2 and graphene on Ag3PO4 for its ultra-enhanced photocatalytic activity in phenol degradation under visible light

    NASA Astrophysics Data System (ADS)

    Peng, Wen-Chao; Wang, Xi; Li, Xiao-Yan

    2014-06-01

    The photo-degradation of organic pollutants using solar light is an attractive chemical process for water pollution control. In this study, we synthesized a new composite material consisting of silver phosphate (Ag3PO4) sub-microcrystals grown on a layered molybdenum disulfide (MoS2) and graphene (GR) hybrid as a high-performance photocatalyst for the degradation of toxic organic pollutants. This composite photocatalyst was prepared via a simple two-step hydrothermal process that used sodium molybdate, thiourea and graphene oxide as precursors for the MoS2/GR hybrid and silver nitrate for the Ag3PO4 sub-microcrystals. The composite Ag3PO4-0.02(MoS2/0.005GR) was found to be the most effective catalyst for the photo-decomposition of 2,4-dichlorophenol under simulated solar light and visible light (λ >= 420 nm). The photocatalyst was also highly active for the degradation of nitrophenol and chlorophenol. The ultra photocatalytic activity of the novel catalyst arose from the synergetic effects of MoS2 and GR as cocatalysts in the composite. MoS2/GR nanosheets served as electron collectors for the interfacial electron transfer from Ag3PO4 to electron acceptors in the aqueous solution and thus enhanced the separation of the photo-generated electron-hole pairs and made the holes more available for organic oxidation. In addition, the presence of MoS2 and GR provided more active adsorption sites and allowed for the activation of dissolved O2 for organic degradation in water.The photo-degradation of organic pollutants using solar light is an attractive chemical process for water pollution control. In this study, we synthesized a new composite material consisting of silver phosphate (Ag3PO4) sub-microcrystals grown on a layered molybdenum disulfide (MoS2) and graphene (GR) hybrid as a high-performance photocatalyst for the degradation of toxic organic pollutants. This composite photocatalyst was prepared via a simple two-step hydrothermal process that used sodium molybdate

  8. Structural features of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, and their catalytic activity in butan-2-ol conversion

    SciTech Connect

    Kacimi, Mohammed; Ziyad, Mahfoud; Hatert, Frederic . E-mail: fhatert@ulg.ac.be

    2005-04-20

    AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, were synthesized by a solid state reaction in air at 750 deg. C. The X-ray powder diffraction pattern of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} indicates the presence of small amounts of (Ca, Mg){sub 3}(PO{sub 4}){sub 2} with the whitlockite structure, as impurity, whereas AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3} is constituted by pure alluaudite. The Rietveld refinements of the X-ray powder diffraction patterns indicate an ordered cationic distribution for AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, with Ag on A(2)', Cd on A(1) and M(1), and Mg on M(2), whereas a disordered distribution of Cd and Ca between the A(1) and M(1) sites is observed for AgCaCdMg{sub 2}(PO{sub 4}){sub 3}. The catalytic properties of these compounds has been measured in reaction of butan-2-ol dehydrogenation. In the absence of oxygen, both samples exhibit poor dehydrogenation activity. All samples displayed no dehydration activity. Introduction of oxygen into the feed changed totally the catalytic behavior of the catalysts. The production of methyl ethyl ketone increases with time on stream and the reaction temperature. AgCaCdMg{sub 2}(PO{sub 4}){sub 3} is more efficient than AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}.

  9. Effect of firing temperature on the electrochemical performance of LiMn 0.4Fe 0.6PO 4/C materials prepared by mechanical activation

    NASA Astrophysics Data System (ADS)

    Baek, Dong-Ho; Kim, Jae-Kwang; Shin, Yong-Jo; Chauhan, Ghanshyam S.; Ahn, Jou-Hyeon; Kim, Ki-Won

    Carbon-coated LiMn 0.4Fe 0.6PO 4 composites (LiMn 0.4Fe 0.6PO 4/C) were synthesized for use as cathode materials in lithium batteries. The composites were synthesized by a mechanical activation process that consists of high-energy ball milling for 10 h, followed by thermal treatment at different temperatures. The structure, particle size and surface morphology of these cathode active materials were investigated by inductively coupled plasma (ICP) analysis, energy dispersive spectrometry (EDS), high-resolution Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The firing temperature was observed to affect morphology, particle size, elemental distribution, structure of the residual carbon, and consequently the electrochemical properties of the composites. LiMn 0.4Fe 0.6PO 4/C synthesized at 600 °C possessed the most desirable properties and it exhibited the best performance when used as cathode in lithium batteries at room temperature. The cell, comprising cathode of this composite, exhibited the initial discharge capacities of 144.5 mAh g -1 (85.0% of theoretical capacity) and 122.0 mAh g -1 (71.8%), respectively, at 0.1 and 1 C-rates. The cathode showed good cycle stability without substantial capacity fade up to 50 cycles.

  10. [Studies on enzymic browning of potatoes (Solanum tuberosum). I. Phenoloxidases and phenolic compounds from different varieties (author's transl)].

    PubMed

    Matheis, G; Belitz, H D

    1977-02-25

    31 samples of potato varieties with slow, medium and fast rates of browning were studies. Characteristic enzyme patterns were obtained from polyacrylamide gel electrophoresic of the phenoloxidases of varieties with different discolouration rates. The differences lie mainly in the intensities of the enzyme bands. The qualitative determinaiton of the phenols showed no significant differences. Tyrosine, chlorogenic acid and caffeic acid produce coloured oxidation products; the characteristic colour gradations of in vivo browning were only observed in the presence of tyrosine. It is concluded that the same reactions take place during the discolouration of all the varieties. PMID:404775

  11. Characterization and ciprofloxacin adsorption properties of activated carbons prepared from biomass wastes by H3PO4 activation.

    PubMed

    Sun, Yuanyuan; Li, Hong; Li, Guangci; Gao, Baoyu; Yue, Qinyan; Li, Xuebing

    2016-10-01

    As biomass wastes, Arundo donax Linn and pomelo peel were used as precursors for activated carbons (ALAC and PPAC) preparation by phosphoric acid activation. The pore structure and surface acidic functional groups of both carbons were characterized by nitrogen adsorption/desorption experiment, NH3-temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR). A batch of experiments was carried out to investigate the adsorption performances of ciprofloxacin under different conditions. Results showed that PPAC exhibited larger surface area (1252m(2)/g) and larger portion of mesoporous, while ALAC was typical of microporous materials. Results from NH3-TPD suggested that ALAC was characteristic of more acidic functional group than PPAC. The maximum monolayer adsorption capability was 244mg/g for ALAC and 400mg/L for PPAC. Kinetics studies showed intra-particle diffusion was not the unique rate-controlling step. Boundary layer resistance existed between adsorbent and adsorbate.

  12. Enhanced sunlight photocatalytic activity of Ag3PO4 decorated novel combustion synthesis derived TiO2 nanobelts for dye and bacterial degradation.

    PubMed

    Eswar, Neerugatti KrishnaRao; Ramamurthy, Praveen Chandrashekarapura; Madras, Giridhar

    2015-07-01

    This study demonstrates the synthesis of TiO2 nanobelts using solution combustion derived TiO2 with enhanced photocatalytic activity for dye degradation and bacterial inactivation. Hydrothermal treatment of combustion synthesized TiO2 resulted in unique partially etched TiO2 nanobelts and Ag3PO4 was decorated using the co-precipitation method. The catalyst particles were characterized using X-ray diffraction analysis, BET surface area analysis, diffuse reflectance and electron microscopy. The photocatalytic properties of the composites of Ag3PO4 with pristine combustion synthesized TiO2 and commercial TiO2 under sunlight were compared. Therefore the studies conducted proved that the novel Ag3PO4/unique combustion synthesis derived TiO2 nanobelt composites exhibited extended light absorption, better charge transfer mechanism and higher generation of hydroxyl and hole radicals. These properties resulted in enhanced photodegradation of dyes and bacteria when compared to the commercial TiO2 nanocomposite. These findings have important implications in designing new photocatalysts for water purification.

  13. BiPO4 photocatalyst employing synergistic action of Ag/Ag3PO4 nanostructure and graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Mohaghegh, N.; Rahimi, E.

    2016-06-01

    Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to be degraded over the other catalysts. This enhanced photocatalytic activity of Graphene-supported BiPO4/Ag/Ag3PO4 for all pollutants could be mainly ascribed to the reinforced charge transfer from BiPO4/Ag/Ag3PO4 to RGO, which suppresses the recombination of electron/hole pairs. Besides that, this photocatalyst can be used repetitively with a high photocatalytic activity and no apparent loss of activity occurs. The results reveal that the RGO nanosheets work as a photocatalyst promoter during the photocatalytic reaction, leading to an improved photocatalytic activity.

  14. Oleate-Assisted Room Temperature Synthesis and High Photocatalytic Activity of Ag3PO4 Nanoparticles for no Decomposition

    NASA Astrophysics Data System (ADS)

    Huang, Lijun; Yin, Shu; Guo, Chongshen; Huang, Yunfang; Wang, Ming; Dong, Qiang; Li, Huihui; Kimura, Takeshi; Tanaka, Miyuki; Sato, Tsugio

    2012-06-01

    An oleate-assisted approach was used to synthesize nanosized spherical silver phosphate (Ag3PO4) in different solvents. The silver phosphate nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible-infrared diffuse reflectance spectroscopy (DRS), thermogravimetric analysis (TDA), and surface area measurement by nitrogen adsorption and decomposition evolution of NOx gas. The as-prepared nanoparticles showed narrow size distribution. The black colored nanoparticles could absorb most of visible light with a wavelength up to 530 nm. The DeNOx experiments revealed that the nanosized Ag3PO4 possessed a photocatalytic ability being superior to commercial P25 sample both in ultraviolet light and visible light regions.

  15. Metabolism of 210Po in rats: volatile 210Po from faeces.

    PubMed

    Sadi, Baki B; Li, Chunsheng; Wyatt, Heather; Bugden, Michelle; Wilkinson, Diana; Kramer, Gary

    2011-04-01

    The metabolic formation of volatile (210)Po species in a rat that was intravenously administered with (210)Po-citrate was investigated in this study. A slurry of the faecal sample was prepared in water and was bubbled with nitrogen gas in a closed system. The discharged gas was passed through a trapping device filled with liquid scintillation cocktail in order to capture any volatile (210)Po species. The amount of (210)Po trapped in the scintillation cocktail was measured by a liquid scintillation analyser that provided evidence of the presence of volatile (210)Po species in the faeces. The presence of volatile (210)Po in the faeces indicates that the metabolic formation of volatile (210)Po is likely to occur in the gut due to bacterial activity. The amount of volatile (210)Po species was compared with the daily faecal excretion of (210)Po. After 2 h of bubbling, the volatile (210)Po collected from the faeces sample was found to be between 1.0 and 1.7 % of the daily faecal excretion for the 4 d following (210)Po-citrate administration.

  16. Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

    2014-02-01

    Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ΔG (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ΔH (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

  17. Direct Observation of Active Material Concentration Gradients and Crystallinity Breakdown in LiFePO4 Electrodes During Charge/Discharge Cycling of Lithium Batteries

    PubMed Central

    2014-01-01

    The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate. PMID:24790684

  18. 210Po microsphere radiological design for tumor vascular disruption

    PubMed Central

    2015-01-01

    The feasibility of disrupting a tumor’s vascular structure using 210Po microspheres is investigated using standard ion and photon absorbed dose methodologies. Calculated absorbed dose profiles for 210Po alpha particles are sufficient to disrupt a tumor’s arteriole structure while minimizing the dose outside the blood vessel wall. 210Po photons contribute minimal dose to healthy tissue. The requisite activity of 210Po to facilitate vascular disruption is calculated. PMID:26290796

  19. Melanosis in Penaeus monodon: Involvement of the Laccase-like Activity of Hemocyanin.

    PubMed

    Bris, Cédric Le; Cudennec, Benoit; Dhulster, Pascal; Drider, Djamel; Duflos, Guillaume; Grard, Thierry

    2016-01-27

    In shrimp, the development of postmortem melanosis resulting from phenoloxidase activities leads to important economic losses. Phenoloxidase enzymes include catechol oxidases, laccases, and tyrosinases, but hemocyanin is also capable of phenoloxidase activities. These activities have been explored in Penaeus monodon, using different substrates. Results highlighted that tyrosinase-specific substrates were little oxidized, whereas hydroquinone (laccase-specific substrate) was more highly oxidized than l-DOPA (nonspecific substrate) in the pereopods and pleopods. Global phenoloxidase activity, assayed with l-DOPA, did not appear thermally stable over time and probably resulted from phenoloxidase enzymes. Conversely, the laccase-like activity assayed with hydroquinone was thermally stable over time, reflecting the thermal stability of hemocyanin. Independently of the anatomical compartment, the temperature, or the substrate, the highest activities were assayed in the cuticular compartments. This study demonstrates the complexity of phenoloxidase activities in P. monodon, and the importance of considering all the activities, including laccase-like activities such as that of hemocyanin. PMID:26671070

  20. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    NASA Astrophysics Data System (ADS)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  1. Effect of plasma-chemical and thermal treatment in oxygen on the activity of Na3ZrM(PO4)3 phosphates (M = Zn, Co, Cu) in the transformation of butanol-2

    NASA Astrophysics Data System (ADS)

    Pylinina, A. I.; Povarova, E. I.; Mikhalenko, I. I.; Yagodovskaya, T. V.

    2013-06-01

    The catalytic properties of plasma-chemically and thermally treated triple zirconium orthophosphates Na3ZrM(PO4)3 (M = Zn, Co, Cu) in the transformation of butanol-2 are studied. X-ray photoelectron spectroscopy data indicate that the surface composition of the samples differs from the stoichiometry, especially in the case of M = Cu. The partial reduction of copper ions occurs during plasma-chemical treatment (PCT), while the amount of Cu on the surface of Na3ZrCu(PO4)3 diminishes. Treatment in an oxygen glow discharge results in a 3-8 times greater yield of the alcohol dehydrogenation product, methyl ethyl ketone. The energy of the alcohol's bonds with the surface is reduced and the dehydration active sites become fully inactivated. In contrast, thermal treatment (TT) results in an increase in the activity of Na3ZrM(PO4)3 in the dehydration of butanol-2.

  2. Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

    PubMed

    Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

    2016-09-01

    Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field. PMID:27494550

  3. Assessment of ²¹⁰Po in Italian diet.

    PubMed

    Meli, Maria Assunta; Desideri, Donatella; Roselli, Carla; Feduzi, Laura

    2014-07-15

    This research was dedicated to the study, in the Italian daily diet, of the background activity concentration of (210)Po, a radionuclide with a high radiotoxicity. (210)Po was determined by alpha spectrometry. For food products of vegetable origin, the (210)Po activity concentration follows the trend: leafy vegetable>flour>rice>fruits>pasta>other vegetables>fruit vegetable; for those of animal origin: eggs>cheese>milk. The (210)Po activity concentration was also compared with that found by the same authors in meat, sea food, water and beverages in a previous study. The committed effective doses to individuals of three population groups (infants, children and adults) were 379, 222 and 151 μSv y(-1), respectively. The intake of foods of marine origin contributed about 67% of the total dose due to (210)Po ingestion. The effective dose, from (210)Po ingested by total diet, accounts for only 5-12% of the natural radiation exposure in Italy.

  4. Assessment of ²¹⁰Po in Italian diet.

    PubMed

    Meli, Maria Assunta; Desideri, Donatella; Roselli, Carla; Feduzi, Laura

    2014-07-15

    This research was dedicated to the study, in the Italian daily diet, of the background activity concentration of (210)Po, a radionuclide with a high radiotoxicity. (210)Po was determined by alpha spectrometry. For food products of vegetable origin, the (210)Po activity concentration follows the trend: leafy vegetable>flour>rice>fruits>pasta>other vegetables>fruit vegetable; for those of animal origin: eggs>cheese>milk. The (210)Po activity concentration was also compared with that found by the same authors in meat, sea food, water and beverages in a previous study. The committed effective doses to individuals of three population groups (infants, children and adults) were 379, 222 and 151 μSv y(-1), respectively. The intake of foods of marine origin contributed about 67% of the total dose due to (210)Po ingestion. The effective dose, from (210)Po ingested by total diet, accounts for only 5-12% of the natural radiation exposure in Italy. PMID:24594158

  5. Occurrence of natural radioactivity in public water supplies in Germany: (238)U, (234)U, (235)U, (228)RA, (226)RA, (222)RN, (210)PB, (210)PO and gross alpha activity concentrations.

    PubMed

    Beyermann, M; Bünger, T; Schmidt, K; Obrikat, D

    2010-09-01

    The Federal Office for Radiation Protection performed a representative survey on the radiological quality of drinking water in Germany. The aim of this study was to determine regional variations of natural radionuclide concentrations and to estimate radiation exposures caused by drinking water consumption. The study includes analyses of the natural radionuclides (238)U, (234)U, (235)U, (228)Ra, (226)Ra, (222)Rn, (210)Pb, (210)Po and of gross alpha activity concentrations in drinking water from 564 public water supplies. This represents 3 % of all German water supplies providing about 37 Mio. inhabitants. Results on ranges, medians and distributions of radionuclide concentrations of drinking water as well as age-dependent ingestion and inhalation doses estimated for members of the public are presented. Generally, the dose due to uranium isotopes is negligibly low. Radiation exposures are predominantly caused by (222)Rn, (228)Ra, (210)Po and (210)Pb. The ingestion dose deduced for adults (>17 a) and infants (0-1 a) is dominated by (222)Rn and (228)Ra, respectively. A gross alpha activity analysis procedure using liquid scintillation counting has been tested. Measured gross alpha activities values were found to be well related to the summarised activities of (238)U, (234)U, (226)Ra and (210)Po.

  6. [Isolation and partial characterization of phenoloxidase from apples (Malus domestica, var. Anna)].

    PubMed

    Soto-Valdéz, H; Trejo-González, A

    1989-06-01

    This study pursued the isolation and partial characterization of the enzyme polyphenoloxidase from apple (Malus domestica Anna variety), grown in the Hermosillo Coast (State of Sonora, Mexico). The effects of pH and temperature as well as its specificity towards substrates, and its behavior under conditions of hydrophobic chromatography, were studied. The enzyme was isolated from a residual powder obtained from ripe apples homogenized with cold acetone. The extract thus prepared was used to characterize the enzyme, and it showed an optimum pH of 5.36 and an optimum temperature of 35 degrees C. The substrate specificity proved to decrease from 4-methyl catechol, chlorogenic acid, catechol, and caffeic acid, to 3,4-dihydroxiphenyl alanine (DOPA). The enzyme resulted to be more thermostable (temperature range: 35 degrees C to 60 degrees C) than the rest of oxidases of plant origin. When the extract was eluted under conditions of hydrophobic chromatography separation, it appeared as a single peak resulting in a 300 fold purification. The phenolase activity characteristics found in the present study were similar to those observed in other apples from temperate climates; however, this particular polyphenoloxidase is more thermostable under natural conditions. This explains why apples of the Anna variety, at the high harvesting temperature, show a very fast formation of brown spots even when there is a minor damage. The content of compounds with phenolic group was high (1.16 g/100 g fresh weight). Further increase of the velocity of fruit enzymatic browning was due to this reason.

  7. Phase transition and multicolor luminescence of Eu{sup 2+}/Mn{sup 2+}-activated Ca{sub 3}(PO{sub 4}){sub 2} phosphors

    SciTech Connect

    Li, Kai; Chen, Daqin; Xu, Ju; Zhang, Rui; Yu, Yunlong; Wang, Yuansheng

    2014-01-01

    Graphical abstract: We have synthesized Eu{sup 2+} doped and Eu{sup 2+}/Mn{sup 2+} co-doped Ca{sub 3}(PO{sub 4}){sub 2} phosphors. The emitting color varies from blue to green with increasing of Eu{sup 2+} content for the Eu{sup 2+}-doped phosphor, and the quantum yield of the 0.05Eu{sup 2+}: Ca{sub 2.95}(PO{sub 4}){sub 2} sample reaches 56.7%. Interestingly, Mn{sup 2+} co-doping into Eu{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi-color luminescence from green to red via Eu{sup 2+} → Mn{sup 2+} energy transfer. - Highlights: • A series of novel Eu{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} phosphors were successfully synthesized. • Phase transition of Ca{sub 3}(PO{sub 4}){sub 2} from orthorhombic to rhombohedral occurred when Mn{sup 2+} ions were doped. • The phosphors exhibited tunable multi-color luminescence. • The quantum yield of 0.05Eu{sup 2+}: Ca{sub 2.95}(PO{sub 4}){sub 2} phosphor can reach 56.7%. • The analyses of phosphors were carried out by many measurements. - Abstract: Intense blue-green-emitting Eu{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} and tunable multicolor-emitting Eu{sup 2+}/Mn{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} phosphors are prepared via a solid-state reaction route. Eu{sup 2+}-doped orthorhombic Ca{sub 3}(PO{sub 4}){sub 2} phosphor exhibits a broad emission band in the wavelength range of 400–700 nm with a maximum quantum yield of 56.7%, and the emission peak red-shifts gradually from 479 to 520 nm with increase of Eu{sup 2+} doping content. Broad excitation spectrum (250–420 nm) of Eu{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} matches well with the near-ultraviolet LED chip, indicating its potential applications as tri-color phosphors in white LEDs. Interestingly, Mn{sup 2+} co-doping into Eu{sup 2+}: Ca{sub 3}(PO{sub 4}){sub 2} leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi

  8. Electronic Properties of LiFePO4 and Li doped LiFePO4

    SciTech Connect

    Zhuang, G.V.; Allen, J.L.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2005-06-28

    The potential use of different iron phosphates as cathodematerials in lithium-ion batteries has recently been investigated.1 Oneof the promising candidates is LiFePO4. This compound has severaladvantages in comparison to the state-of-the-art cathode material incommercial rechargeable lithium batteries. Firstly, it has a hightheoretical capacity (170 mAh/g). Secondly, it occurs as mineraltriphylite in nature and is inexpensive, thermally stable, non-toxic andnon-hygroscopic. However, its low electronic conductivity (~;10-9 S/cm)results in low power capability. There has been intense worldwideresearch activity to find methods to increase the electronic conductivityof LiFePO4, including supervalent ion doping,2 introducingnon-carbonaceous network conduction3 and carbon coating, and theoptimization of the carbon coating on LiFePO4 particle surfaces.4Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL hasyield electronic conductivity increase up to 106.5 We studied electronicstructure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-rayemission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes theunoccupied partial density of states, while XES the occupied partialdensity of states. By combining XAS and XES measurements, we obtainedinformation on band gap and orbital character of both LiFePO4 and Lidoped LiFePO4. The occupied and unoccupied oxygen partial density ofstates (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented inFig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (~; 4 eV). This value is much larger than what is predicted byDFT calculation. For 5 percent Li doped LiFePO4, a new doping state wascreated closer to the Fermi level, imparting p-type conductivity,consistent with thermopower measurement. Such observation substantiatesthe suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 isdue to available number of charge carriers in the material. Furthermore,Hall effect

  9. Innate immune-stimulating and immune genes up-regulating activities of three types of alginate from Sargassum siliquosum in Pacific white shrimp, Litopenaeus vannamei.

    PubMed

    Yudiati, Ervia; Isnansetyo, Alim; Murwantoko; Ayuningtyas; Triyanto; Handayani, Christina Retna

    2016-07-01

    The Total Haemocyte Count (THC), phenoloxidase (PO), Superoxide Dismutase (SOD) activity, Phagocytic Activity/Index and Total Protein Plasma (TPP) were examined after feeding the white shrimp Litopenaeus vannamei with diets supplemented with three different types of alginates (acid, calcium and sodium alginates). Immune-related genes expression was evaluated by quantitative Real Time PCR (qRT-PCR). Results indicated that the immune parameters directly increased according to the doses of alginates and time. The 2.0 g kg(-1) of acid and sodium alginate treatments were gave better results. Four immune-related genes expression i.e. LGBP, Toll, Lectin, proPO were up regulated. It is therefore concluded that the supplementation of alginate of Sargassum siliquosum on the diet of L. vannamei enhanced the innate immunity as well as the expression of immune-related genes. It is the first report on the simultaneous evaluation of three alginate types to enhance innate immune parameters and immune-related genes expression in L. vannamei. PMID:26993614

  10. Innate immune-stimulating and immune genes up-regulating activities of three types of alginate from Sargassum siliquosum in Pacific white shrimp, Litopenaeus vannamei.

    PubMed

    Yudiati, Ervia; Isnansetyo, Alim; Murwantoko; Ayuningtyas; Triyanto; Handayani, Christina Retna

    2016-07-01

    The Total Haemocyte Count (THC), phenoloxidase (PO), Superoxide Dismutase (SOD) activity, Phagocytic Activity/Index and Total Protein Plasma (TPP) were examined after feeding the white shrimp Litopenaeus vannamei with diets supplemented with three different types of alginates (acid, calcium and sodium alginates). Immune-related genes expression was evaluated by quantitative Real Time PCR (qRT-PCR). Results indicated that the immune parameters directly increased according to the doses of alginates and time. The 2.0 g kg(-1) of acid and sodium alginate treatments were gave better results. Four immune-related genes expression i.e. LGBP, Toll, Lectin, proPO were up regulated. It is therefore concluded that the supplementation of alginate of Sargassum siliquosum on the diet of L. vannamei enhanced the innate immunity as well as the expression of immune-related genes. It is the first report on the simultaneous evaluation of three alginate types to enhance innate immune parameters and immune-related genes expression in L. vannamei.

  11. Effects of artificial infection of Litopenaeus vannamei by Micrococcus lysodeikticus and WSSV on the activity of immunity related enzymes.

    PubMed

    Sun, Cheng-Bo; Wang, Gang; Chan, Siuming F

    2015-10-01

    In this study, the activities of 5 immunity related enzymes namely acid phosphatase (ACP), alkaline phosphatase (AKP), phenoloxidase (PO), peroxidase (POD) and lysozyme phosphatase (LZM)) of Litopenaeus vannamei after they have been injected with different concentrations of Micrococcus lysodeikticus and the white spot syndrome virus (WSSV) were examined. The cumulative mortality at 0, 24, 48, 72, 96 h was obtained. Copy numbers of WSSV in L. vannamei after a single infection, secondary infection and concurrent infection were measured. Hemolymph samples of M. lysodeikticus and WSSV injected shrimp were collected at 0, 6, 12 24, 48, 72, 78, 84, 96 and 120 h. The results were: (i) The cumulative mortality of L. vannamei increased as the shrimp were infected with higher concentration of the bacteria; (ii) The most sensitive changes of ACP, AKP and LZM were in the 6.2 × 10(5), 6.2 × 10(6), 6.2 × 10(7) cfu/mL M. lysodeikticus group; (iii) ACP but LZM were more sensitive to M. lysodeikticus than WSSV, and AKP, PO and POD is more sensitive to WSSV; (iv) The copies of WSSV in the co-injected group were higher than WSSV-single infection and WSSV-bacteria-secondary infection group at 48 h. The amount of WSSV in L. vannamei of concurrent infection and WSSV-bacteria-secondary infection groups were higher than that of the WSSV-single infection group.

  12. Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Yujie; Xu, Yunhua; Liu, Yihang; Luo, Chao; Wang, Chunsheng

    2012-12-01

    Carbon-coated olivine NaFePO4 (C-NaFePO4) spherical particles with a uniform diameter of ~80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO4 (C-LiFePO4), which is synthesized by a solvothermal method. The C-NaFePO4 electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO4 except that Li ions in C-LiFePO4 are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO4 cathode in sodium-ion (Na-ion) batteries and C-LiFePO4 in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO4 are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO4 cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO4 cathodes, the rate performance of C-NaFePO4 in Na-ion batteries is much worse than that of C-LiFePO4 in Li-ion batteries. However, the cycling stability of C-NaFePO4 is almost comparable to C-LiFePO4 by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C.Carbon-coated olivine NaFePO4 (C-NaFePO4) spherical particles with a uniform diameter of ~80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO4 (C-LiFePO4), which is synthesized by a solvothermal method. The C-NaFePO4 electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO4 except that Li ions in C-LiFePO4 are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO4 cathode in

  13. Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.

    PubMed

    Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

    2015-05-01

    The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. PMID:25721981

  14. Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.

    PubMed

    Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

    2015-05-01

    The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater.

  15. Renal threshold phosphate concentration (TmPO4/GFR).

    PubMed Central

    Kruse, K; Kracht, U; Göpfert, G

    1982-01-01

    The ratio of maximum rate of renal tubular reabsorption of phosphate to glomerular filtration rate (TmPO4/GFR) was determined in 546 schoolchildren, aged between 6 and 17.9 years, using the nomogram of Walton and Bijvoet.1 TmPO4/GFR correlated with chronological age in girls and boys and in each remained significantly higher than in adults. TmPO4/GFR in the children correlated neither with fasting serum immunoreactive calcitonin and parathyroid hormone levels nor with the urinary cyclic AMP excretion. The study showed a parallel decrease in TmPO4/GFR, excretion of total hydroxyproline and serum alkaline phosphatase activities after puberty, with a significant relationship of both these indices of bone turnover to TmPO4/GFR values. This indicates that the high renal phosphate threshold of children may be an important factor for bone mineralisation by providing high extracellular inorganic phosphate concentrations during normal growth. PMID:6280622

  16. Spirulina elicits the activation of innate immunity and increases resistance against Vibrio alginolyticus in shrimp.

    PubMed

    Chen, Yu-Yuan; Chen, Jiann-Chu; Tayag, Carina Miranda; Li, Hui-Fang; Putra, Dedi Fazriansyah; Kuo, Yi-Hsuan; Bai, Jia-Chin; Chang, Yu-Hsuan

    2016-08-01

    The effect of Spirulina dried powder (SDP) on the immune response of white shrimp Litopenaeus vannamei was studied in vitro and in vivo. Incubating shrimp haemocytes in 0.5 mg ml(-1) SDP caused the degranulation of haemocytes and a reduction in the percentage of large cells within 30 min. Shrimp haemocytes incubated in 1 mg ml(-1) SDP significantly increased their phenoloxidase (PO) activity, serine proteinase activity, and respiratory burst activity (RB, release of superoxide anion). A recombinant protein of lipopolysaccharide and β-1,3-glucan binding protein (LGBP) of the white shrimp was produced, named rLvLGBP, and examined for its binding with SDP. An ELISA binding assay showed that rLvLGBP binds to SDP with a dissociation constant of 0.0507 μM. In another experiment, shrimp fed diets containing SDP at 0 (control), 30, and 60 g kg(-1) after four weeks were examined for LGBP transcript level and lysozyme activity, as well as phagocytic activity, clearance efficiency, and resistance to Vibrio alginolyticus. These parameters were significantly higher in shrimp receiving diets containing SDP at 60 g kg(-1) or 30 g kg(-1) than in controls. In conclusion, shrimp haemocytes receiving SDP provoked the activation of innate immunity as evidenced by the recognition and binding of LGBP, degranulation of haemocytes, reduction in the percentage of large cells, increases in PO activity, serine proteinase activity, superoxide anion levels, and up-regulated LGBP transcript levels. Shrimp receiving diets containing SDP had increased lysozyme activity and resistance against V. alginolyticus infection. This study showed the mechanism underlying the immunostimulatory action of Spirulina and its immune response in shrimp.

  17. Spirulina elicits the activation of innate immunity and increases resistance against Vibrio alginolyticus in shrimp.

    PubMed

    Chen, Yu-Yuan; Chen, Jiann-Chu; Tayag, Carina Miranda; Li, Hui-Fang; Putra, Dedi Fazriansyah; Kuo, Yi-Hsuan; Bai, Jia-Chin; Chang, Yu-Hsuan

    2016-08-01

    The effect of Spirulina dried powder (SDP) on the immune response of white shrimp Litopenaeus vannamei was studied in vitro and in vivo. Incubating shrimp haemocytes in 0.5 mg ml(-1) SDP caused the degranulation of haemocytes and a reduction in the percentage of large cells within 30 min. Shrimp haemocytes incubated in 1 mg ml(-1) SDP significantly increased their phenoloxidase (PO) activity, serine proteinase activity, and respiratory burst activity (RB, release of superoxide anion). A recombinant protein of lipopolysaccharide and β-1,3-glucan binding protein (LGBP) of the white shrimp was produced, named rLvLGBP, and examined for its binding with SDP. An ELISA binding assay showed that rLvLGBP binds to SDP with a dissociation constant of 0.0507 μM. In another experiment, shrimp fed diets containing SDP at 0 (control), 30, and 60 g kg(-1) after four weeks were examined for LGBP transcript level and lysozyme activity, as well as phagocytic activity, clearance efficiency, and resistance to Vibrio alginolyticus. These parameters were significantly higher in shrimp receiving diets containing SDP at 60 g kg(-1) or 30 g kg(-1) than in controls. In conclusion, shrimp haemocytes receiving SDP provoked the activation of innate immunity as evidenced by the recognition and binding of LGBP, degranulation of haemocytes, reduction in the percentage of large cells, increases in PO activity, serine proteinase activity, superoxide anion levels, and up-regulated LGBP transcript levels. Shrimp receiving diets containing SDP had increased lysozyme activity and resistance against V. alginolyticus infection. This study showed the mechanism underlying the immunostimulatory action of Spirulina and its immune response in shrimp. PMID:27368541

  18. Short-lived isomers in 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Hofmann, S.; Huyse, M.; Kalaninová, Z.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Lommel, B.; Nishio, K.; Page, R. D.; Sulignano, B.; Van Duppen, P.

    2016-06-01

    Isomeric states in 194Po and 192Po were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions 141Pr(56Fe, p 2 n )194Po and 144Sm(51V, p 2 n )192Po . Several new γ -ray transitions were attributed to the isomers and γ -γ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in 194Po, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (11-) to (10-). The de-excitation of the (11-) isomeric level in 192Po by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV (E 3 ) transition to (8+) level of the ground-state band was suggested. Moreover, side feeding to the (4+) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting 11- isomers in neighboring Po and Pb isotopes.

  19. 210Po in Nevada groundwater and its relation to gross alpha radioactivity

    USGS Publications Warehouse

    Seiler, R.L.

    2011-01-01

    Polonium-210 (210Po) is a highly toxic alpha emitter that is rarely found in groundwater at activities exceeding 1 pCi/L. 210Po activities in 63 domestic and public-supply wells in Lahontan Valley in Churchill County in northern Nevada, United States, ranged from 0.01 ± 0.005 to 178 ± 16 pCi/L with a median activity of 2.88 pCi/L. Wells with high 210Po activities had low dissolved oxygen concentrations (less than 0.1 mg/L) and commonly had pH greater than 9. Lead-210 activities are low and aqueous 210Po is unsupported by 210Pb, indicating that the 210Po is mobilized from aquifer sediments. The only significant contributors to alpha particle activity in Lahontan Valley groundwater are 234/238U, 222Rn, and 210Po. Radon-222 activities were below 1000 pCi/L and were uncorrelated with 210Po activity. The only applicable drinking water standard for 210Po in the United States is the adjusted gross alpha radioactivity (GAR) standard of 15 pCi/L. 210Po was not volatile in a Nevada well, but volatile 210Po has been reported in a Florida well. Additional information on the volatility of 210Po is needed because GAR is an inappropriate method to screen for volatile radionuclides. About 25% of the samples had 210Po activities that exceed the level associated with a lifetime total cancer risk of 1× 10−4 (1.1 pCi/L) without exceeding the GAR standard. In cases where the 72-h GAR exceeds the uranium activity by more than 5 to 10 pCi/L, an analysis to rule out the presence of 210Po may be justified to protect human health even though the maximum contaminant level for adjusted GAR is not exceeded.

  20. Biogeochemical factors affecting the presence of 210Po in groundwater

    USGS Publications Warehouse

    Seiler, R.L.; Stillings, L.L.; Cutler, N.; Salonen, L.; Outola, I.

    2011-01-01

    The discovery of natural 210Po enrichment at levels exceeding 500 mBq/L in numerous domestic wells in northern Nevada, USA, led to a geochemical investigation of the processes responsible for its mobilization. 210Po activities in 63 domestic and public-supply wells ranged from below 1 mBq/L to 6590 ± 590 mBq/L, among the highest reported levels in the USA. There is little spatial or depth variability in 210Pb activity in study-area sediments and mobilization of a few percent of the 210Po in the sediments would account for all of the 210Po in water. Stable-isotope measurements indicate SO4 reduction has occurred in all 210Po contaminated wells. Sulfide species are not accumulating in the groundwater in much of Lahontan Valley, probably because of S cycling involving microbial SO4 reduction, abiotic oxidation of H2S to S0 by Mn(IV), followed by microbial disproportionation of S0 to H2S and SO4. The high pH, Ca depletion, MnCO3 saturation, and presence of S0 in Lahontan Valley groundwater may be consequences of the anaerobic S cycling. Consistent with data from naturally-enriched wells in Florida, 210Po activities begin to decrease when aqueous sulfide species begin to accumulate. This may be due to formation and precipitation of PoS, however, Eh–pH diagrams suggest PoS would not be stable in study-area groundwater. An alternative explanation for the study area is that H2S accumulation begins when anaerobic S cycling stops because Mn oxides are depleted and their reduction is no longer releasing 210Po. Common features of 210Po-enriched groundwater were identified by comparing the radiological and geochemical data from Nevada with data from naturally-enriched wells in Finland, and Florida and Maryland in the USA. Values of pH ranged from 9 in Nevada wells, indicating that pH is not critical in determining whether 210Po is present. Where U is present in the sediments, the data suggest 210Po levels may be elevated in aquifers with (1) SO4-reducing waters with low H2S

  1. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ► The O{sup 2−}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ► The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ► There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2−}-Sm{sup 3+}, O{sup 2−}-Dy{sup 3+} and O{sup 2−}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2−}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

  2. Polonium 210Po in the phytobenthos from Puck Bay.

    PubMed

    Skwarzec, B; Ulatowski, J; Strumińska, D I; Falandysz, J

    2003-04-01

    The aim of the work was to determine the 210Po content in phytobenthos species (seaweeds and angiosperms) from Puck Bay (southern Baltic). Alpha spectrometry was used to measure and calculate the activities and concentrations of polonium 210Po in the phytobenthos. The activity of 210Po in Puck Bay waters was determined to estimate the bioconcentration factors (BCF) of these plants. The 210Po concentration in water was estimated at 0.25 mBq dm(-3). The lowest polonium concentration in the phytobenthos was found in Cladophora rupestris (0.12 Bq kg(-1) wet wt.), the highest in Chara crinita (1.12 Bq kg(-1) wet wt.). Polonium is accumulated in these phytobenthos species; the bioconcentration factors (BCF) ranged from 450 to 4400.

  3. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3

    NASA Astrophysics Data System (ADS)

    Yahia, H. Ben; Essehli, R.; Avdeev, M.; Park, J.-B.; Sun, Y.-K.; Al-Maadeed, M. A.; Belharouak, I.

    2016-06-01

    The new compounds NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 crystallize with a stuffed α-CrPO4-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 a statistical disorder Ni2+/Cr3+ was observed on both the 8g and 4a atomic positions, whereas in NaCoCr2(PO4)3 the statistical disorder Co2+/Cr3+ was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 delivered specific capacities of 352, 385, and 368 mA h g-1, respectively, which attests to the electrochemical activity of sodium in these compounds.

  4. Decay/ingrowth uncertainty correction of (210)Po/(210)Pb in seawater.

    PubMed

    Lin, Wuhui; Ma, Hao; Chen, Liqi; Zeng, Zhi; He, Jianhua; Zeng, Shi

    2014-11-01

    Due to increasing application of (210)Po/(210)Pb in studying particle dynamics, a consistent procedure and calculation to derive accurate and precise result of (210)Po and (210)Pb in seawater should be proposed in the framework of intercalibration by GEOTRACES. The associated uncertainty of radioactivity, which is a significant component of data report, plays a vital role in intercomparison and should be well evaluated. Although measurement uncertainty of laboratory result was well defined in ISO standards and IAEA technical documents, the decay/ingrowth uncertainty correction from laboratory result to in-situ result was less studied. It was demonstrated that the relative uncertainty of in-situ (210)Pb activity was independent of elapsed time and equal to relative uncertainty of laboratory measuring (210)Po activity at second spontaneous deposition date. The relative uncertainty of in-situ (210)Po activity decreases with in-situ activity ratio of (210)Po to (210)Pb and increases with elapsed time between sampling date and separation date, relative uncertainty of laboratory measuring (210)Po activity at first spontaneous deposition date and relative uncertainty of in-situ (210)Pb activity. It was more important to improve precision of (210)Po at first spontaneous deposition date than that of (210)Po at second spontaneous deposition date. To obtain a desirable relative uncertainty of in-situ (210)Po activity, the maximum allowing elapsed time for (210)Po, which was important for sampling strategy making and quality assurance, was calculated by in-situ activity ratio of (210)Po to (210)Pb and precision of analytical method for (210)Po. The methodology of decay/ingrowth uncertainty correction could also be applied for other radionuclide pairs ((234)Th/(238)U, (90)Y/(90)Sr, (210)Bi/(210)Pb), sample matrixes (aerosols), and disciplines. PMID:24992240

  5. Decay/ingrowth uncertainty correction of (210)Po/(210)Pb in seawater.

    PubMed

    Lin, Wuhui; Ma, Hao; Chen, Liqi; Zeng, Zhi; He, Jianhua; Zeng, Shi

    2014-11-01

    Due to increasing application of (210)Po/(210)Pb in studying particle dynamics, a consistent procedure and calculation to derive accurate and precise result of (210)Po and (210)Pb in seawater should be proposed in the framework of intercalibration by GEOTRACES. The associated uncertainty of radioactivity, which is a significant component of data report, plays a vital role in intercomparison and should be well evaluated. Although measurement uncertainty of laboratory result was well defined in ISO standards and IAEA technical documents, the decay/ingrowth uncertainty correction from laboratory result to in-situ result was less studied. It was demonstrated that the relative uncertainty of in-situ (210)Pb activity was independent of elapsed time and equal to relative uncertainty of laboratory measuring (210)Po activity at second spontaneous deposition date. The relative uncertainty of in-situ (210)Po activity decreases with in-situ activity ratio of (210)Po to (210)Pb and increases with elapsed time between sampling date and separation date, relative uncertainty of laboratory measuring (210)Po activity at first spontaneous deposition date and relative uncertainty of in-situ (210)Pb activity. It was more important to improve precision of (210)Po at first spontaneous deposition date than that of (210)Po at second spontaneous deposition date. To obtain a desirable relative uncertainty of in-situ (210)Po activity, the maximum allowing elapsed time for (210)Po, which was important for sampling strategy making and quality assurance, was calculated by in-situ activity ratio of (210)Po to (210)Pb and precision of analytical method for (210)Po. The methodology of decay/ingrowth uncertainty correction could also be applied for other radionuclide pairs ((234)Th/(238)U, (90)Y/(90)Sr, (210)Bi/(210)Pb), sample matrixes (aerosols), and disciplines.

  6. Performance and kinetics of LiFePO4-carbon bi-material electrodes for hybrid devices: A comparative study between activated carbon and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Varzi, Alberto; Ramirez-Castro, Claudia; Balducci, Andrea; Passerini, Stefano

    2015-01-01

    Activated Carbon (AC) and multi-walled carbon nanotubes (CNT) are investigated as components of LiFePO4 (LFP)-based bi-material electrodes for hybrid devices. Firstly, the influence of their different morphological and porosimetric characteristics is correlated to the electrochemical performance. Furthermore, kinetic aspects are carefully studied (by means of galvanostatic cycling and cyclic voltammetry), in order to address the processes which determine the power performance. The results indicate that, independently from the carbon, under high current loads the electrode kinetics are limited by the transport of reactant to the LFP particles. In such conditions CNT allow, better than AC, rapid electrons and Li+ ions flow through the open network established in the electrode, thus enabling superior high rate performance, especially during pulsed operation.

  7. Production and decay spectroscopy of 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.

    2015-10-01

    A γ-ray spectroscopy study of the (11-) isomers in 194Po and 192Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction 56Fe + 141Pr → 197At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  8. The sources and fate of (210)Po in the urban air: A review.

    PubMed

    Długosz-Lisiecka, Magdalena

    2016-09-01

    The origin of (210)Po activity and its fluctuations in the air are discussed in this paper. In the case of atmospheric aerosol samples, a comparison of the (210)Po/(210)Pb and (210)Bi/(210)Pb activity ratios makes it possible not only to determine aerosol residence times but also to appraise the contribution of the unsupported (210)Po coming from other sources than (222)Rn decay, such as human industrial activities, especially coal combustion. A simple mathematical method makes it possible to observe the seasonal fluctuations of the anthropogenic excess of (210)Po in the urban air. The average doses of (210)Po intake with food (including drinking water) and inhalation of urban aerosols are usually lower than those from (210)Po intake by cigarette smokers and negligible in comparison to total natural radiation exposure. PMID:27295049

  9. Role of PO4 tetrahedron in LiFePO4 and FePO4 system.

    PubMed

    Zeng, Yuewu

    2015-06-01

    Using high resolution transmission electron microscopy with image simulation and Fourier analysis, the Li1- x FePO4 (x < 0.01), Li1- x FePO4 (x ∼ 0.5), and FePO4 particles, prepared by charging or discharging the 053048 electrochemical cells (thickness: 5 mm, width: 30 mm, height: 48 mm) and dismantled inside an Ar-filled dry box, were investigated. The high resolution images reveal: (1) the solid solution of Li1- x FePO4 (x < 0.01) contains some missing Li ions leading PO4 group distorted around M1 tunnel of the unit cell; (2) the texture of the particles of Li1- x FePO4 (x ∼0.5) has homogeneously distributed compositional domains of LiFePO4 and FePO4 resulting from spinodal decomposition which promote Li ion easily getting into the particle due to uphill diffusion, (3) the particles of FePO4 formed in charging have heavily distorted lattice and contain some isolated LiFePO4 , (4) interface between LiFePO4 and FePO4 and between amorphous and crystal region provides the lattice distortion of small polarons.

  10. {sup 210}Po and {sup 210}Pb in Forest Soil and in Wild Berries in Finland

    SciTech Connect

    Vaaramaa, Kaisa; Lehto, Jukka; Solatie, Dina; Aro, Lasse

    2008-08-07

    The behaviour of {sup 210}Po and {sup 210}Pb was investigated in forests in the Southern Finland site and in the Northern Finland site. Sampling sites were in Scots pine (Pinus sylvestris) forests. Maximum activities of {sup 210}Po and {sup 210}Pb in soil columns were found in organic layers. According to preliminary results of wild berry samples, the lowest {sup 210}Po concentrations were found in berries. The highest concentration of {sup 210}Po was found in stems of the blueberry (Vaccinium myrtillus) and the lingonberry (Vaccinium vitis-idaea) samples.

  11. Baseline concentration of Polonium-210 ((210)Po) in tuna fish.

    PubMed

    Khan, M Feroz; Wesley, S Godwin

    2016-06-15

    Several species of tuna fish were analyzed for (210)Po content in their edible muscle tissues. This study was carried out as a part of baseline data generation around a large nuclear power plant situated at Kudankulam, southeast coast of India. The concentration of (210)Po in the muscle tissue ranged from 40.9±5.2 to 92.5±7.9Bq/kg of fresh fish, and the highest activity was recorded for the tuna Euthynnus affinis and the lowest for Auxis thazard. The committed effective dose to the local residents was calculated to be 62.7-141.8μSvyear(-1).

  12. Baseline concentration of Polonium-210 ((210)Po) in tuna fish.

    PubMed

    Khan, M Feroz; Wesley, S Godwin

    2016-06-15

    Several species of tuna fish were analyzed for (210)Po content in their edible muscle tissues. This study was carried out as a part of baseline data generation around a large nuclear power plant situated at Kudankulam, southeast coast of India. The concentration of (210)Po in the muscle tissue ranged from 40.9±5.2 to 92.5±7.9Bq/kg of fresh fish, and the highest activity was recorded for the tuna Euthynnus affinis and the lowest for Auxis thazard. The committed effective dose to the local residents was calculated to be 62.7-141.8μSvyear(-1). PMID:27045047

  13. Flow cytometric analysis of crayfish haemocytes activated by lipopolysaccharides

    USGS Publications Warehouse

    Cardenas, W.; Dankert, J.R.; Jenkins, J.A.

    2004-01-01

    Lipopolysaccharides (LPS) from Gram-negative bacteria are strong stimulators of white river crayfish, Procambarus zonangulus, haemocytes in vitro. Following haemocyte treatment with LPS and with LPS from rough mutant R5 (LPS Rc) from Salmonella minnesota, flow cytometric analysis revealed a conspicuous and reproducible decrease in cell size as compared to control haemocytes. These LPS molecules also caused a reduction in haemocyte viability as assessed by flow cytometry with the fluorescent dyes calcein-AM and ethidium homodimer. The onset of cell size reduction was gradual and occurred prior to cell death. Haemocytes treated with LPS from S. minnesota without the Lipid A moiety (detoxified LPS) decreased in size without a reduction of viability. The action of LPS on crayfish haemocytes appeared to be related to the activation of the prophenoloxidase system because phenoloxidase (PO)-specific activity in the supernatants from control and detoxified LPS-treated cells was significantly lower than that from LPS and LPS-Rc treated cells (P < 0.05). Furthermore, addition of trypsin inhibitor to the LPS treatments caused noticeable delays in cell size and viability changes. These patterns of cellular activation by LPS formulations indicated that crayfish haemocytes react differently to the polysaccharide and lipid A moieties of LPS, where lipid A is cytotoxic and the polysaccharide portion is stimulatory. These effects concur with the general pattern of mammalian cell activation by LPS, thereby indicting commone innate immune recognition mechanisms to bacterial antigens between cells from mammals and invertebrates. These definitive molecular approaches used to verify and identify mechanisms of invertbrate haemocyte responses to LPS could be applied with other glycoconjugates, soluble mediators, or xenobiotic compounds.

  14. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in calcium supplements and the assessment of their possible dose to consumers.

    PubMed

    Strumińska-Parulska, Dagmara I

    2016-08-23

    This paper presents the results of pioneer study of the most popular calcium supplements as a potential additional source of radiolead (210)Pb in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some came from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The idea was to investigate the naturally occurring (210)Pb activity in different calcium supplements and calculate the annual effective radiation dose from radiolead (210)Pb decay in consumed calcium supplement. The results showed (210)Pb concentrations in natural origin calcium supplements (especially sedimentary rocks) were significantly higher. The highest (210)Pb activity concentrations were determined in mineral tablets made from dolomite - 2.97 ± 0.18 mBq g(-1), while the lowest was observed in organic calcium compounds - both calcium lactate - 0.08 ± 0.01 and 0.13 ± 0.01 mBq g(-1). The highest annual radiation dose from (210)Pb taken with 1 tablet of calcium supplement per day was calculated for soluble calcium lactate sample - 1.19 ± 0.03 µSv year(-1), while the highest annual radiation dose from (210)Pb taken daily with 1 g of pure Ca for dolomite - 5.57 ± 0.34 µSv year(-1).

  15. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in calcium supplements and the assessment of their possible dose to consumers.

    PubMed

    Strumińska-Parulska, Dagmara I

    2016-08-23

    This paper presents the results of pioneer study of the most popular calcium supplements as a potential additional source of radiolead (210)Pb in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some came from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The idea was to investigate the naturally occurring (210)Pb activity in different calcium supplements and calculate the annual effective radiation dose from radiolead (210)Pb decay in consumed calcium supplement. The results showed (210)Pb concentrations in natural origin calcium supplements (especially sedimentary rocks) were significantly higher. The highest (210)Pb activity concentrations were determined in mineral tablets made from dolomite - 2.97 ± 0.18 mBq g(-1), while the lowest was observed in organic calcium compounds - both calcium lactate - 0.08 ± 0.01 and 0.13 ± 0.01 mBq g(-1). The highest annual radiation dose from (210)Pb taken with 1 tablet of calcium supplement per day was calculated for soluble calcium lactate sample - 1.19 ± 0.03 µSv year(-1), while the highest annual radiation dose from (210)Pb taken daily with 1 g of pure Ca for dolomite - 5.57 ± 0.34 µSv year(-1). PMID:27253716

  16. Recoil-deposited Po-210 in radon dwellings

    SciTech Connect

    Samuelsson, C.

    1990-12-31

    Short-lived decay products of Rn-222 plate out on all surfaces in a house containing radon gas. Following the subsequent alpha decays of the mother nuclei, the daughter products Pb-214 and Pb-210 are superficially and permanently absorbed. Due to its long half-life (22 y) the activity of absorbed Pb-210 accumulates in the surface. The activity of Pb-210, or its decay products, can thus reflect the past randon daughter and plate-out history of a house over several decades. Our results and experience from measurements of Po-210 and Rn-222 in 22 dwellings will be presented. In these studies the Po-210 surface activity of one plane glass sheet per dwelling (window panes were not used) has been determined and compared with the period of exposure times the mean radon concentration measured over a two-month period. Considering the large uncertainty in the integrated radon exposure estimate the surface {sup 210}Po correlates well (r=0.73) with the accumulated radon exposure. The {sup 210}Po activity of the glass samples has been measured non-destructively using an open-flow pulse ionization chamber and this detector has also been successfully applied in field exercises.

  17. The effect of banana (Musa acuminata) peels hot-water extract on the immunity and resistance of giant freshwater prawn, Macrobrachium rosenbergii via dietary administration for a long term: Activity and gene transcription.

    PubMed

    Rattanavichai, Wutti; Chen, Ying-Nan; Chang, Chin-Chyuan; Cheng, Winton

    2015-10-01

    The non-specific immune parameters, disease resistance and immune genes expressions in Macrobrachium rosenbergii were evaluated at 120 days of post feeding the diets containing the extracts of banana, Musa acuminate, fruit's peel (banana peels extract, BPE) at 0, 1.0, 3.0 and 6.0 g kg(-1). Results showed that prawns fed with a diet containing BPE at the level of 1.0, 3.0 and 6.0 g kg(-1) for 120 days had a significantly higher survival rate (30.0%, 40.0% and 56.7%, respectively) than those fed with the control diet after challenge with Lactococcus garvieae for 144 h, and the respective relative survival percentages were 22.2%, 33.3%, and 51.9%, respectively. Dietary BPE supplementation at 3.0 and/or 6.0 g kg(-1) for 120 days showed a significant increase total haemocyte count (THC), granular cell (GC), superoxide dismutase (SOD) activity, phenoloxidase (PO) activity, transglutaminase (TG) activity, and phagocytic activity and clearance efficiency to L. garvieae infection, and meanwhile, the significant decrease in haemolymph clotting times and respiratory bursts (RBs) per haemocyte of prawns were revealed. Furthermore, the mRNA expressions of prophenoloxidase (proPO), lipopolysaccharide and β-1,3-glucan binding protein (LGBP), peroxinectin (PE), transglutaminase (TG), and crustin (CT) were significantly increased. We therefore recommend that BPE can be used as an immunomodulator for prawns through dietary administration at 6.0 g kg(-1) for a long term (over 120 days) to modify immune responses and genes expression following the enhanced resistance against pathogens.

  18. Synthesis and characterization of CdS/BiPO{sub 4} heterojunction photocatalyst

    SciTech Connect

    Chen, Daimei Kuang, Zheng; Zhu, Qian; Du, Yue; Zhu, Honglei

    2015-06-15

    Highlights: • A CdS/BiPO{sub 4} heterojunction was prepared by the solvothermal method. • The CdS/BiPO{sub 4} composite has the higher photocatalytic activity than the individual ones. • The optimal mass ratio of CdS to BiPO{sub 4} was 0.5. • The heterojunction structure of CdS/BiPO{sub 4} induces an effective electron–hole separation. - Abstract: A series of CdS/BiPO{sub 4} heterojunction photocatalysts with the visible-light response were synthesized by the solvothermal method. The resulting products were characterized by X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection spectroscopy. CdS nanoparticles with the size at range of 5–7 nm were immobilized on the surface of BiPO{sub 4} nanorods. The CdS/BiPO{sub 4} composite exhibited much higher photodegradation rate of methylene blue under visible light irradation compared to the pure CdS and BiPO{sub 4}. The optimal mass ratio of CdS to BiPO{sub 4} was 0.5, the photodegradation rate of which is 2.1 times higher than that of CdS. The enhancement of photocatalytic activity is attributed to the heterojunction structure of CdS/BiPO{sub 4} composite which induced the effective electron–hole separation between CdS and BiPO{sub 4}.

  19. Kinetics of neutralization of Po-218

    SciTech Connect

    Chu, K.D.

    1987-01-01

    In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The mobilities of Po/sup +/ and PoO/sub 2//sup +/ are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small ion recombination rate has been found to be proportional to the square root of radon concentration. The electron scavenging mechanism is responsible for the neutralization of Po/sup +/ in NO/sub 2/ or H/sub 2/O in nitrogen. When PoO/sub 2//sup +/ is formed, the electron transfer mechanism dominates the neutralization process. The electron is transferred to PoO/sub 2//sup +/ from molecules with lower ionization potentials. The ionization potential of PoO/sub 2//sup +/ is also determined to be 10.44 +/- 0.05 eV.

  20. Excretion rates of 210Po and 210Pb in Prague inhabitants.

    PubMed

    Hölgye, Zoltán

    2013-01-01

    Excretion rates of (210)Po and (210)Pb in the urine were investigated in 40 healthy inhabitants of Prague (22 males, 18 females, age: 23-70 y, non-smokers). In 20 inhabitants the excretion rates of (210)Po and (210)Pb in faeces were also studied. The mean urinary excretion rates of (210)Po and (210)Pb were 4.1 and 6.0 mBq d(-1), respectively. It was demonstrated, statistically, that the urinary excretion rates of (210)Po and (210)Pb are higher in men than those in women. The highest excretion rates of (210)Po and (210)Pb found in the participants were 10.8 and 16.6 mBq d(-1), respectively. The mean activity ratio of (210)Po/(210)Pb in the urine was 0.73. The mean excretion rates of (210)Po and (210)Pb in faeces were 56.5 and 54.6 mBq d(-1). The mean activity ratio of (210)Po/(210)Pb in faeces was 1.0.

  1. The BiPo detector for ultralow radioactivity measurements

    SciTech Connect

    Bongrand, Mathieu

    2011-04-27

    The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in {sup 208}Tl and {sup 214}Bi for the SuperNEMO double beta decay source foils. A modular prototype called BiPo-1 with 0.8 m{sup 2} of sensitive surface area has been running in the Modane Underground Laboratory since February 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in {sup 208}Tl. After more than one year of background measurement a surface activity of the scintillators of A({sup 208}Tl) = 1.5 {mu}Bq/m{sup 2} is reported here.Given this level of background, a larger BiPo3 detector having 3.25 m{sup 2} of active surface area, will able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of A({sup 208}Tl)<3-4 {mu}Bq/kg(90% C.L.) with a six month measurement. This detector is actually under construction and will be installed in the Canfranc Underground Laboratory mid 2011.

  2. Tools for Scientist Engagement in E/PO: NASA SMD Community Workspace and Online Resources

    NASA Astrophysics Data System (ADS)

    Dalton, H.; Shipp, S. S.; Grier, J.; Gross, N. A.; Buxner, S.; Bartolone, L.; Peticolas, L. M.; Woroner, M.; Schwerin, T. G.

    2014-12-01

    The Science Mission Directorate (SMD) Science Education and Public Outreach (E/PO) Forums are here to help you get involved in E/PO! The Forums have been developing several online resources to support scientists who are - or who are interested in becoming - involved in E/PO. These include NASA Wavelength, EarthSpace, and the SMD E/PO online community workspace. NASA Wavelength is the one-stop shop of all peer-reviewed NASA education resources to find materials you - or your audiences - can use. Browse by audience (pre-K through 12, higher education, and informal education) or topic, or choose to search for something specific by keyword and audience. http://nasawavelength.org. EarthSpace, an online clearinghouse of Earth and space materials for use in the higher education classroom, is driven by a powerful search engine that allows you to browse the collection of resources by science topic, audience, type of material or key terms. All materials are peer-reviewed before posting, and because all submissions receive a digital object identifier (doi), submitted materials can be listed as publications. http://www.lpi.usra.edu/earthspace. The SMD E/PO online community workspace contains many resources for scientists. These include one-page guides on how to get involved, tips on how to make the most of your time spent on E/PO, and sample activities, as well as news on funding, policy, and what's happening in the E/PO community. The workspace also provides scientists and the public pathways to find opportunities for participation in E/PO, to learn about SMD E/PO projects and their impacts, to connect with SMD E/PO practitioners, and to explore resources to improve professional E/PO practice, including literature reviews, information about the Next Generation Science Standards, and best practices in evaluation and engaging diverse audiences. http://smdepo.org.

  3. Evaluation of uncertainty and detection limits in 210Pb and 210Po measurement in water by alpha spectrometry using 210Po spontaneous deposition onto a silver disk.

    PubMed

    Fernández, Pedro L; Gómez, José; Ródenas, Carmen

    2012-04-01

    An easy and accurate method for the determination of (210)Pb and (210)Po in water using (210)Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of (210)Pb, (210)Bi and (210)Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of (210)Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between (210)Pb and (210)Bi and the second after a sufficient time for the ingrowth of (210)Po from (210)Pb to be significant. As shown, for a recommended time interval of seven months between (210)Po measurements, the applicability of the proposed method is limited to water samples with a (226)Ra to (210)Pb activity ratio C(Ra)/C(Pb) ≤ 4, as usual in natural waters. Using sample and background counting times of 24h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1L sample typically varies between 0.7 and 16 mBq L(-1) for (210)Pb in water samples with an initial activity of (210)Po in the range 0-200 mBq L(-1), and between 0.6 and 8.5 mBq L(-1) for (210)Po in water samples with an initial activity of (210)Pb in the same range.

  4. Use of moss and lichen species to identify (210)Po-contaminated regions.

    PubMed

    Długosz-Lisiecka, Magdalena; Wróbel, Justyna

    2014-12-01

    (210)Po concentration in urban air fluctuates as a result of natural (222)Rn radionuclide exhalation and technical activity that is especially linked with high-temperature processes. Each year, an average 11 GBq of (210)Po is released from local power plants into urban air. Over two months, about 180 samples in central Poland were collected. To detect the concentration of (210)Po activity, two common species of biomonitors were chosen: the moss Pleurozium schreberi and the lichen Hypogymnia physodes. For the same locale, (210)Po in lichen shows an average of twice the amount of activity concentration than the moss. In moss, (210)Po concentrations in Lodz ranged from 41.5 Bq kg(-1) to 258.0 Bq kg(-1), while in lichen it ranges from 74.2 Bq kg(-1) to 670.9 Bq kg(-1). On the basis of the measured activity of (210)Po maps, radionuclide distribution has been prepared. For areas identified with higher concentrations of (210)Po, Quantum Gis has been applied.

  5. Use of moss and lichen species to identify (210)Po-contaminated regions.

    PubMed

    Długosz-Lisiecka, Magdalena; Wróbel, Justyna

    2014-12-01

    (210)Po concentration in urban air fluctuates as a result of natural (222)Rn radionuclide exhalation and technical activity that is especially linked with high-temperature processes. Each year, an average 11 GBq of (210)Po is released from local power plants into urban air. Over two months, about 180 samples in central Poland were collected. To detect the concentration of (210)Po activity, two common species of biomonitors were chosen: the moss Pleurozium schreberi and the lichen Hypogymnia physodes. For the same locale, (210)Po in lichen shows an average of twice the amount of activity concentration than the moss. In moss, (210)Po concentrations in Lodz ranged from 41.5 Bq kg(-1) to 258.0 Bq kg(-1), while in lichen it ranges from 74.2 Bq kg(-1) to 670.9 Bq kg(-1). On the basis of the measured activity of (210)Po maps, radionuclide distribution has been prepared. For areas identified with higher concentrations of (210)Po, Quantum Gis has been applied. PMID:25301434

  6. Modeling pO(2) distributions in the bone marrow hematopoietic compartment. I. Krogh's model.

    PubMed Central

    Chow, D C; Wenning, L A; Miller, W M; Papoutsakis, E T

    2001-01-01

    Human bone marrow (BM) is a tissue of complex architectural organization, which includes granulopoietic loci, erythroblastic islets, and lymphocytic nodules. Oxygen tension (pO(2)) is an important determinant of hematopoietic stem and progenitor cell proliferation and differentiation. Thus, understanding the impact of the BM architectural organization on pO(2) levels in extravascular hematopoietic tissue is an important biophysical problem. However, currently it is impossible to measure pO(2) levels and their spatial variations in the BM. Homogeneous Kroghian models were used to estimate pO(2) distribution in the BM hematopoietic compartment (BMHC) and to conservatively simulate pO(2)-limited cellular architectures. Based on biophysical data of hematopoietic cells and characteristics of BM physiology, we constructed a tissue cylinder solely occupied by granulocytic progenitors (the most metabolically active stage of the most abundant cell type) to provide a physiologically relevant limiting case. Although the number of possible cellular architectures is large, all simulated pO(2) profiles fall between two extreme cases: those of homogeneous tissues with adipocytes and granulocytic progenitors, respectively. This was illustrated by results obtained from a parametric criterion derived for pO(2) depletion in the extravascular tissue. Modeling results suggest that stem and progenitor cells experience a low pO(2) environment in the BMHC. PMID:11463616

  7. Ultrasonic-assisted synthesis of core-shell structure CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb nanophosphors and their photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Fan, Yao-yao; Hu, Zong-chao; Yang, Jian; Zhang, Chao; Zhu, Ling

    2013-02-01

    CePO4:Tb, CePO4:Tb/GdPO4, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4 (4-8) nm × (35-73) nm sized nanobars with the hexagonal crystal system have been obtained by ultrasonic-assisted synthesis and characterized by X-ray diffraction (XRD), FT-IR spectrum, transmission electron microscopy (TEM), photoluminescence (PL). The shell thickness of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb core/shell structure is 1.04 nm and 1.10 nm respectively. Under ultraviolet excitation, these nanophosphors show Tb3+ characteristic emission, 5D4-7FJ (J = {6, 5, 4, 3}) and the fluorescence of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb increases superficially compared with CePO4:Tb and the co-precipitated (Ce, Tb, Gd)PO4. The photoluminescence intensity of CePO4:Tb/GdPO4 is 33 times, 7 times, 2 times as high as that of CePO4:Tb, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4, respectively. It is worth mentioning that the increasing amount of intensity of CePO4:Tb/GdPO4 is double than that of GdPO4/CePO4:Tb. A possible formation mechanism for the fluorescent efficiency enhancement has been proposed. The results are helpful in developing effective phosphors and have potential applications in field emission display (FED) and plasma display panels (PDP).

  8. Polonium 210Po in cigarettes produced in Poland.

    PubMed

    Skwarzec, B; Strumińska, D I; Borylo, A; Ulatowski, J

    2001-01-01

    This paper discusses the results of 210Po determinations in the fourteen most frequently smoked brands of cigarettes, which constitute over 80% of total cigarette consumption in Poland. The 210Po activity in the cigarette samples analysed (tobacco, ash, filter before and after smoking) were measured using alpha spectrometry (Canberra-Packard). The data indicates that there is considerable variation in the polonium content of these brands. The highest 210Po content per sample was found in the cheap "Popularne" brand (24.12 mBq), the lowest in "Caro" (4.23 mBq). There was also a large difference between the polonium remaining in the ash in comparison with its total content in the tobacco in all the brands (from 4.3% for "Golden American" to 71.0% for "Sobieski King-Size"). The analysis has demonstrated that filters absorbed only a small amount of the polonium contained in the tobacco. "Caro" cigarettes have the most efficient filter, retaining 25.1% of the polonium contained in the tobacco, but most filters absorbed only 0.1-7.2% of polonium. The daily inhalation of 210Po by Polish smokers who get through one pack per day ranges from 20 to 215 mBq, but people smoking two or more packs of "Popularne" brand will inhale over 430 mBq of polonium per day.

  9. Bioaccumulation of polonium 210Po in marine birds.

    PubMed

    Skwarzec, B; Fabisiak, J

    2007-01-01

    The aim of this work was to determine the 210Po content in marine birds which permanently or temporally live in the Polish part of the Baltic Sea. We chose 11 species of sea birds: three species permanently residing at southern Baltic Sea, four species of wintering birds and three species of migrating birds. The results show that the polonium is non-uniformly distributed in the marine birds. The highest activities of 210Po were observed in feathers, muscles and liver and the lowest in skin and skeleton. Species of birds that eat crustaceans, molluscs, fish and plants (long-tailed duck Clangula hyemalis, white-winged scoter Melanitta fusca) accumulated more polonium than species that eat mainly fish (great cormorant Phalacrocorax carbo, common guillemot Uria aalge) or plants (tufted duck Aythya fuligula). Moreover, about 63% of the 210Po that was located in feathers of razorbil (Alca torda) and long-tailed duck (C. hyemalis) was apparently adsorbed, suggesting an external source such as the air. It means that the adsorption of 210Po on the feather surface may be an important transfer from air to water.

  10. Annual dose of Taiwanese from the ingestion of 210Po in oysters.

    PubMed

    Lee, Hsiu-wei; Wang, Jeng-Jong

    2013-03-01

    Oysters around the coast of Taiwan were collected, dried, spiked with a (209)Po tracer for yield, digested with concentrated HNO(3) and H(2)O(2), and finally dissolved in 0.5 N HCl. The polonium was then spontaneously deposited onto a silver disc, and the activity of (210)Po was measured using an alpha spectrum analyzer equipped with a silicon barrier detector. Meanwhile, the internal effective dose of (210)Po coming from the intake of oysters by Taiwanese was evaluated. The results of the present study indicate that (210)Po average activity concentrations ranged from 23.4 ± 0.4 to 126 ± 94 Bq kg(-1) of fresh oysters. The oysters coming from Penghu island and Kinmen island regions contain higher concentrations of (210)Po in comparison with oysters from other regions of Taiwan. The value of (210)Po weighted average activity concentrations for all oyster samples studied is 25.9 Bq kg(-1). The annual effective dose of Taiwanese due to the ingestion of (210)Po in oysters was estimated to be 4.1 × 10(-2) mSv y(-1).

  11. Characterization and expression analysis of the prophenoloxidase activating factor from the mud crab Scylla paramamosain.

    PubMed

    Wang, J; Jiang, K J; Zhang, F Y; Song, W; Zhao, M; Wei, H Q; Meng, Y Y; Ma, L B

    2015-01-01

    Prophenoloxidase activating factors (PPAFs) are a group of clip domain serine proteinases that can convert prophenoloxidase (pro-PO) to the active form of phenoloxidase (PO), causing melanization of pathogens. Here, two full-length PPAF cDNAs from Scylla paramamosain (SpPPAF1 and SpPPAF2) were cloned and characterized. The full-length SpPPAF1 cDNA was 1677 bp in length, including a 5'-untranslated region (UTR) of 52 bp, an open reading frame (ORF) of 1131 bp coding for a polypeptide of 376 amino acids, and a 3'-UTR of 494 bp. The full-length SpPPAF2 cDNA was 1808 bp in length, including a 5'-UTR of 88 bp, an ORF of 1125 bp coding for a polypeptide of 374 amino acids, and a 3'-UTR of 595 bp. The estimated molecular weight of SpPPAF1 and SpPPAF2 was 38.43 and 38.56 kDa with an isoelectric point of 7.54 and 7.14, respectively. Both SpPPAF1 and SpPPAF2 proteins consisted of a signal peptide, a characteristic structure of clip domain, and a carboxyl-terminal trypsin-like serine protease domain. Expression analysis by qRT-PCR showed that SpPPAF1 mRNA was mainly expressed in the gill, testis, and hemocytes, and SpPPAF2 mRNA was mainly expressed in hemocytes. In addition, SpPPAF1 and SpPPAF2 mRNA was expressed in a time-dependent manner after Vibrio parahaemolyticus challenge. The results showed that expression of both SpPPAF1 and SpPPAF2 was related to the bacterial challenge but the expression patterns differed. These findings suggest that SpPPAF is a serine proteinase and may be involved in the pro-PO activation pathway of the crab innate immune system. PMID:26345816

  12. Redetermination of AgPO3

    PubMed Central

    Terebilenko, Katherina V.; Zatovsky, Igor V.; Ogorodnyk, Ivan V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure. PMID:21522230

  13. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-02-09

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure.

  14. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure. PMID:21522230

  15. Estimating benthic fluxes of trace elements to hypoxic coastal waters using 210Po

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hoon; Kim, Guebuem

    2014-12-01

    The activities of colloidal (10 kDa-0.45 μm) and truly dissolved (<10 kDa) 210Po and 210Pb, dissolved inorganic nutrients, and trace elements (Al, V, Co, Ni, Cu, Mo, Mn, and Fe) were measured in the artificial and saline Lake Shihwa, South Korea in July 2011. The boundary between oxic and hypoxic layers, indexed by NH4+, Mn, and dissolved oxygen, was determined by the pycnocline formed at the depth of 2-4 m. The total activities of 210Po and 210Pb in Lake Shihwa were in the range of 10.5-20.4 dpm 100 L-1 and 6.4 to 9.8 dpm 100 L-1, respectively. The proportions of the truly dissolved, colloidal, and particulate phases were, respectively, 55 ± 6%, 29 ± 5%, and 16 ± 3% for 210Po, and 48 ± 6%, 29 ± 7%, and 23 ± 4% for 210Pb. The activities of 210Po were 20-55% higher than those of 210Pb. The benthic flux of 210Po is determined on the basis of the 210Po mass balance model in the water column. Since the excess activities of dissolved 210Po relative to 210Pb showed a positive correlation with the concentrations of trace elements (except for Al), the benthic fluxes of the trace elements from bottom sediment were successfully calculated using these relationships and the 210Po fluxes. Our study highlights that 210Po can be used as a powerful tracer for estimating trace element fluxes from bottom sediment in a hypoxic environment.

  16. Metabolism of 210Po in rats: volatile 210Po in excreta.

    PubMed

    Li, Chunsheng; Sadi, Baki; Wyatt, Heather; Bugden, Michelle; Priest, Nicholas; Wilkinson, Diana; Kramer, Gary H

    2010-07-01

    Polonium-210 ((210)Po) is one of the most toxic radionuclides and was used as a poison in the Alexander Litvinenko case. In this study of the metabolism of (210)Po in rats, volatile (210)Po in excreta was measured, filling a knowledge gap of the previous studies. Five rats were intravenously administrated with 2 kBq and another five with 10 kBq of (210)Po (citrate form). They were housed in a glass Metabowl system for 4 d following the administration. Volatile (210)Po from the excreta was collected in a trapping system filled with liquid scintillation cocktail and was measured by liquid scintillation counting. Results showed that the daily excretion of volatile (210)Po by the rats is in a very small percentage (0.002-0.009 %) of the administered amounts. However, if the administered amount is large, the excretion of volatile (210)Po can be significant.

  17. High efficient multifunctional Ag3PO4 loaded hydroxyapatite nanowires for water treatment.

    PubMed

    Li, Yaling; Zhou, Hangyu; Zhu, Genxing; Shao, Changyu; Pan, Haihua; Xu, Xurong; Tang, Ruikang

    2015-12-15

    Organic, inorganic, and biological pollutants are typical water contaminants and they seriously affect water quality. In this study, we suggested that a novel multifunctional Ag3PO4 loaded hydroxyapatite (HAP) material can remove the typical pollutants from water. The Ag3PO4/HAP composites were synthesized facilely via in-situ precipitation of Ag3PO4 on the pre-existing HAP nanowires. By optimizing the composition of Ag3PO4 and HAP, the material could achieve an optimal photocatalytic activity to decompose rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) under visible light irradiations with enhanced pH stability. Besides, the adsorption of Pb(II) on the Ag3PO4/HAP reached a maximum capacity of 250 mg/g and this value was approximately three times as that of pure HAP. Furthermore, the composite material exhibited excellent antibacterial activities towards gram-negative bacterium (Escherichia coli) and gram-positive bacterium (Stphylococcus aureus). The results highlighted the cooperative effect between Ag3PO4 and hydroxyapatite (HAP). The simultaneous removals of dyes, toxic metal ions, and bacteria with a high efficiency followed an easy approach for the purification of contaminated water via the rationally designed material, in which the Ag3PO4/HAP composite might be developed as a general water treatment material with multiple functions. PMID:26150280

  18. Lattice dynamics of LuPO{sub 4}

    SciTech Connect

    Nipko, J.C. |; Loong, C.-K.; Loewenhaupt, M.; Reichardt, W.; Braden, M.; Boatner, L.A.

    1996-06-01

    Lutetium orthophosphate is an important nonmagnetic host material for rare-earth-activated luminescence applications. We have measured the LuPO{sub 4} phonon density of states and dispersion curves along the [{xi}00],[{xi}{xi}0], and [00{xi}] symmetry directions by neutron spectroscopy using polycrystalline and single-crystal samples. A quantitative analysis of the neutron results was carried out using a lattice-dynamical shell model.

  19. Transfer of {sup 210}Po and {sup 210}Pb through the lichen-caribou-wolf food chain of northern Canada

    SciTech Connect

    Thomas, P.A.; Sheard, J.W.; Swanson, S.

    1994-06-01

    Natural background activity and food chain transfer of the uranium decay products, {sup 210}Po and {sup 210}Pb, were examined in the lichen-caribou-wolf food chain at two locations in the Northwest Territories of Canada. {sup 210}Po and {sup 210}Pb activities in lichens differed with species and location. Both {sup 210}Po and {sup 210}Pb were markedly higher in caribou bone than in wolf bone. {sup 210}Po activities in liver, kidney, and muscle were similar in both species. Caribou fetuses had lower activities of {sup 210}Po but higher activities of {sup 210}Pb than maternal muscle and placenta, suggesting greater placental transport of {sup 210}Pb than {sup 210}Po. Concentration ratios (CR = Bq kg{sup {minus}1} in consumer/Bq kg{sup {minus}1} in its food source) and f{sub f} values (f{sub f} in d kg{sup {minus}1} = Bq kg{sup {minus}1} in muscle/Bq d{sup {minus}1} ingested) showed that wolves retain more {sup 210}Po and less {sup 210}Pb from their diet than do caribou. {sup 210}Po CRs averaged 0.38 for caribou/lichens, 0.26 for caribou/rumen contents, and 0.40 for wolves/caribou. {sup 210}Pb CRs averaged 0.36 for caribou/lichens, 0.57 for caribou/rumen contents, and 0.13 for wolves/caribou. 43 refs., 4 figs., 5 tabs.

  20. Transfer of 210Po and 210Pb through the lichen-caribou-wolf food chain of northern Canada.

    PubMed

    Thomas, P A; Sheard, J W; Swanson, S

    1994-06-01

    Natural background activity and food chain transfer of the uranium decay products, 210Po and 210Pb, were examined in the lichen-caribou-wolf food chain at two locations in the Northwest Territories of Canada. 210Po and 210Pb activities in lichens differed with species and location. Both 210Po and 210Pb were markedly higher in caribou bone than in wolf bone. 210Po activities in liver, kidney, and muscle were similar in both species. Caribou fetuses had lower activities of 210Po but higher activities of 210Pb than maternal muscle and placenta, suggesting greater placental transport of 210Pb than 210Po. Concentration ratios (CR = Bq kg-1 in consumer/Bq kg-1 in its food source) and ff values (ff in d kg-1 = Bq kg-1 in muscle/Bq d-1 ingested) showed that wolves retain more 210Po and less 210Pb from their diet than do caribou. 210Po CRs averaged 0.38 for caribou/lichens, 0.26 for caribou/rumen contents, and 0.40 for wolves/caribou. 210Pb CRs averaged 0.36 for caribou/lichens, 0.57 for caribou/rumen contents, and 0.13 for wolves/caribou.

  1. Sky Fest: A Model of Successful Scientist Participation in E/PO

    NASA Astrophysics Data System (ADS)

    Dalton, H.; Shipp, S. S.; Shaner, A. J.; LaConte, K.; Shupla, C. B.

    2014-12-01

    Participation in outreach events is an easy way for scientists to get involved with E/PO and reach many people with minimal time commitment. At the Lunar and Planetary Institute (LPI) in Houston, Texas, the E/PO team holds Sky Fest outreach events several times a year. These events each have a science content theme and include several activities for children and their parents, night sky viewing through telescopes, and scientist presentations. LPI scientists have the opportunity to participate in Sky Fest events either by helping lead an activity or by giving the scientist presentation (a short lecture and/or demonstration). Scientists are involved in at least one preparation meeting before the event. This allows them to ask questions, understand what activity they will be leading, and learn the key points that they should be sharing with the public, as well as techniques for effectively teaching members of the public about the event topic. During the event, each activity is run by one E/PO specialist and one scientist, enabling the scientist to learn about effective E/PO practices from the E/PO specialist and the E/PO specialist to get more science information about the event topic. E/PO specialists working together with scientists at stations provides a more complete, richer experience for event participants. Surveys of event participants have shown that interacting one-on-one with scientists is often one of their favorite parts of the events. Interviews with scientists indicated that they enjoyed Sky Fest because there was very little time involved on their parts outside of the actual event; the activities were created and/or chosen by the E/PO professionals, and setup for the events was completed before they arrived. They also enjoyed presenting their topic to people without a background in science, and who would not have otherwise sought out the information that was presented.

  2. Po-210 and Pb-210 in water and fish from Taboshar uranium mining Pit Lake, Tajikistan.

    PubMed

    Skipperud, L; Jørgensen, A G; Heier, L S; Salbu, B; Rosseland, B O

    2013-09-01

    Polonium-210 in water and (210)Pb and (210)Po in different fish organs from 3 different fish species in Taboshar Pit Lake (n = 13), located in the uranium mining area in Tajikistan, and in Kairakkum Reservoir (reference lake, n = 3), have been determined as part of a Joint project between Norway, Kazakhstan, Kyrgyzstan and Tajikistan. The average activity concentration of (210)Pb and (210)Po in liver, muscle and bone of Carassius auratus was higher than the concentration in similar tissues of C. carpio and Sander lucioperca from the reference site. The accumulation of (210)Po was higher than for (210)Pb, and the accumulation of (210)Po was highest in the liver of C. auratus (3673 ± 434 Bq kg(-1) ww). Although the average activity concentration of (210)Pb in liver and bones of C. auratus from Pit Lake were fairly similar, a huge variation in the liver activity concentrations (25-327 Bq kg(-1) ww) was found. The results confirm direct uptake of unsupported (210)Po into the liver, and that the distributions of (210)Po and (210)Pb in fish organs were different. The BCF (L/kg) for (210)Po in bone, liver and muscle clearly demonstrates high accumulation of (210)Po in C. auratus, especially in the liver. The average BCFs of liver, bone and muscle were >1.4 × 10(5), >2.5 × 10(4) and >1.4 × 10(4), respectively. All fish in the Pit Lake were found to be in the same trophic level, however, a linear correlation between log (210)Po in liver and δ(15)N could indicate biomagnification of (210)Po in liver of C. auratus. In regards to the recommended Annual Limit of Intake (ALI) for (210)Po, the concentration of (210)Po in muscle tissues of C. auratus is alarming, as there is a high probability for the local population at risk to exceed the recommended ALI through consumption of fish from Taboshar Pit Lake.

  3. An Improved Method to Determine {sup 210}Pb, {sup 210}Bi and {sup 210}Po in air Aerosol Filters

    SciTech Connect

    Miguel, E. G. San; Bolivar, J. P.; Teran, T.

    2008-08-07

    {sup 222}Rn daughters (e.g. {sup 210}Pb, {sup 210}Po, {sup 210}Bi) have been widely used to study a variety of atmospheric processes. Many works in literature about {sup 222}Rn daughters do not specify the way by the activities of these radionuclides are calculated. Besides, {sup 210}Po corrections due to the in-growth of {sup 210}Bi, if taken into account, are not indicated. In this work, the increase in uncertainties of radionuclides activities due to delay between air sampling and radionuclides determinations have been evaluated and the influence of neglecting the contribution of {sup 210}Bi in-growth to {sup 210}Po determination has been estimated. The results indicate that, in general, ignoring the {sup 210}Bi in-growth in {sup 210}Po determinations lead to significant differences (could reach until 100%) between the estimation of {sup 210}Po activity and its true value.

  4. Structure and electrochemistry of NaFePO{sub 4} and Na{sub 2}FePO{sub 4}F cathode materials prepared via mechanochemical route

    SciTech Connect

    Kosova, N.V.; Podugolnikov, V.R.; Devyatkina, E.T.; Slobodyuk, A.B.

    2014-12-15

    Highlights: • Na{sub 2}FePO{sub 4}F is prepared by mechanochemically assisted solid state synthesis. • The crystal and local structure are studied by XRPD, FTIR, Mössbauer, and NMR. • Na{sup +}/Li{sup +} ion exchange is completed with the formation of NaLiFePO{sub 4}F. • The average D{sub Li} (10{sup −15} cm{sup 2} s{sup −1}) is determined from GITT measurements. - Abstract: Nanostructured NaFePO{sub 4} (space group Pmnb) and Na{sub 2}FePO{sub 4}F (space group Pbcn) were prepared by a quick and facile mechanochemically assisted solid state synthesis. Low-crystalline Na{sub 2}FePO{sub 4}F was formed as a result of direct mechanochemical reaction of NaFePO{sub 4} with NaF. It crystallizes upon subsequent heating to 600 °C and decomposes at higher temperatures. Crystal and local structure were analyzed by XRD using Rietveld refinement, FTIR, Mössbauer, and NMR spectroscopy. Electrochemical properties were studied by galvanostatic cycling in lithium cells and GITT. Although NaFePO{sub 4} showed some electrochemical activity, neither electrochemical nor chemical Na{sup +}/Li{sup +} exchange was observed by XRD. On contrary, electrochemical and chemical Na{sup +}/Li{sup +} ion exchange occurred in the case of Na{sub 2}FePO{sub 4}F and accomplished with the NaLiFePO{sub 4}F formation. Li{sup +} diffusion coefficient in NaLiFePO{sub 4}F at different delithiated/lithiated states was determined from GITT. Carbon-coated Na{sub 2}FePO{sub 4}F shows discharge capacity of 116 mA h g{sup −1} at 0.1 C rate within the 2.0–4.2 V voltage range and a good cyclability.

  5. Po-210 as long-term integrating radon indicator in the indoor environment

    SciTech Connect

    Samuelsson, C.

    1990-07-01

    The general objective is to improve the knowledge about the transferring processes leading from airborne radon/radon daughters to embedded Po-210 in hard surfaces in the indoor environment. The specific goal of the research is to identify situations in which the surface activity of Po-210 can be used as a long-term indicator of lung cancer risk from past or future radon exposures.

  6. A biokinetic study of 209Po in man.

    PubMed

    Henricsson, C F; Ranebo, Y; Hansson, M; Rääf, C L; Holm, E

    2012-10-15

    Five adult volunteers participated in a biokinetic study of radioactive polonium. Portions of about 10 Bq of (209)Po were orally administrated to four of the volunteers in a single ingestion. The fifth volunteer ingested a daily amount of 53 mBq of 209Po for 243 d to study the time to achieve equilibrium between intake and excretion for protracted intakes. For the subjects ingesting single intakes of (209)Po complete sampling of urine and feces was subsequently collected the first few days upon the ingestion. The samples were processed with radiochemical extraction and analyzed with alpha spectrometry. In the study, the maximum daily excretion rates in feces were 18-50% of the ingested activity, observed within 3 d after intake. Regarding the urine excretion, the daily excretion peaked, on average, at 0.15-1% of the ingested activity within two days upon intake. These results indicate an average gastro-intestinal uptake fraction of 0.46±0.08, which agrees well with earlier biokinetic studies of polonium in man.

  7. Experimental and theoretical studies on the linear and nonlinear optical properties of lead phosphate crystals LiPbPO4.

    PubMed

    Han, Guopeng; Liu, Qiong; Wang, Ying; Su, Xin; Yang, Zhihua; Pan, Shilie

    2016-07-28

    Phosphates with noncentrosymmetric (NCS) structures usually display short ultraviolet (UV) cut-off edges, but often exhibit weak powder second harmonic generation (SHG) intensities. Here we synthesized a NCS-phosphate, LiPbPO4, that achieves a desired balance between UV transparency, a cut-off edge of about 232 nm, and large SHG activity (about 3 × KDP). The three dimensional (3D) framework of LiPbPO4 consists of PO4 and LiO4 tetrahedra that are corner-shared, forming wide channels where lead cations reside. Local dipole moments for the PO4 and LiO4 tetrahedra as well as lead polyhedra in a unit cell were calculated. First-principles calculations have been performed for better understanding the structure-property relationships in LiPbPO4. In addition, to further explore spatial distribution of the electronic states dominating the NLO activity, the SHG density method was employed. PMID:27357234

  8. Variation of ²¹⁰Po daily urinary excretion for male subjects at environmental level.

    PubMed

    Hölgye, Z; Hýža, M; Mihalík, J; Rulík, P; Škrkal, J

    2015-05-01

    (210)Po was determined in 24-h urine of seven healthy males from Prague, Czech Republic, for ten consecutive days. The results show that for each volunteer, the urinary excretion of (210)Po changed only little from day to day in the studied time period. For two volunteers, the difference in the daily excreted (210)Po activity for two consecutive days was not significant, given the 95% confidence interval (two sigma) of the activity measurements. The same is valid for the excretion data of the other volunteers, except for some days where the differences were slightly higher. The range of daily urinary excretion of (210)Po of each volunteer in the studied time period was quite narrow. Among the volunteers, the maximum daily urinary excretion value of (210)Po was at most about a factor of 2.5 higher than the lowest excretion value. An attempt to explain the observed small inter-individual variability of (210)Po excretion in daily urine is made.

  9. Variation of ²¹⁰Po daily urinary excretion for male subjects at environmental level.

    PubMed

    Hölgye, Z; Hýža, M; Mihalík, J; Rulík, P; Škrkal, J

    2015-05-01

    (210)Po was determined in 24-h urine of seven healthy males from Prague, Czech Republic, for ten consecutive days. The results show that for each volunteer, the urinary excretion of (210)Po changed only little from day to day in the studied time period. For two volunteers, the difference in the daily excreted (210)Po activity for two consecutive days was not significant, given the 95% confidence interval (two sigma) of the activity measurements. The same is valid for the excretion data of the other volunteers, except for some days where the differences were slightly higher. The range of daily urinary excretion of (210)Po of each volunteer in the studied time period was quite narrow. Among the volunteers, the maximum daily urinary excretion value of (210)Po was at most about a factor of 2.5 higher than the lowest excretion value. An attempt to explain the observed small inter-individual variability of (210)Po excretion in daily urine is made. PMID:25712002

  10. Seasonal POC fluxes at BATS estimated from 210Po deficits

    NASA Astrophysics Data System (ADS)

    Stewart, Gillian M.; Bradley Moran, S.; Lomas, Michael W.

    2010-01-01

    In this study at the Bermuda Atlantic Time-series Study (BATS) site we demonstrate that the polonium-lead disequilibrium system may perform better as a tracer of organic carbon export under low-flux conditions (in this case, <2.5 mmol C m -2 d -1) than under bloom conditions in an oligotrophic setting. With very few exceptions, the POC flux predictions calculated from the water-column 210Po deficit were within a factor of 2 of the POC flux caught in surface-tethered sediment traps. However, we found higher correlation between size-fractionated particulate 210Po activity and POC concentration in November 2006 ( r=0.93) than in January ( r=0.79) and during the spring bloom in March 2007 ( r=0.80). We suggest that this is due to the ability of polonium to distinguish between bulk mass flux and organic carbon export under oligotrophic and lithogenic-driven flux regimes. Further, we found that the POC/Po ratio on particles was largely independent of size class between 10 and 100 μm ( P=0.13) during each season, supporting the notion that export in this oligotrophic system is driven by sinking aggregates of smaller cells and not by large, individual cells.

  11. PO2 Cycling Reduces Diaphragm Fatigue by Attenuating ROS Formation

    PubMed Central

    Zuo, Li; Diaz, Philip T.; Chien, Michael T.; Roberts, William J.; Kishek, Juliana; Best, Thomas M.; Wagner, Peter D.

    2014-01-01

    Prolonged muscle exposure to low PO2 conditions may cause oxidative stress resulting in severe muscular injuries. We hypothesize that PO2 cycling preconditioning, which involves brief cycles of diaphragmatic muscle exposure to a low oxygen level (40 Torr) followed by a high oxygen level (550 Torr), can reduce intracellular reactive oxygen species (ROS) as well as attenuate muscle fatigue in mouse diaphragm under low PO2. Accordingly, dihydrofluorescein (a fluorescent probe) was used to monitor muscular ROS production in real time with confocal microscopy during a lower PO2 condition. In the control group with no PO2 cycling, intracellular ROS formation did not appear during the first 15 min of the low PO2 period. However, after 20 min of low PO2, ROS levels increased significantly by ∼30% compared to baseline, and this increase continued until the end of the 30 min low PO2 condition. Conversely, muscles treated with PO2 cycling showed a complete absence of enhanced fluorescence emission throughout the entire low PO2 period. Furthermore, PO2 cycling-treated diaphragm exhibited increased fatigue resistance during prolonged low PO2 period compared to control. Thus, our data suggest that PO2 cycling mitigates diaphragm fatigue during prolonged low PO2. Although the exact mechanism for this protection remains to be elucidated, it is likely that through limiting excessive ROS levels, PO2 cycling initiates ROS-related antioxidant defenses. PMID:25299212

  12. 210Po Activity and concentrations of selected trace elements (As, Cd, Cu, Hg, Pb, Zn) in the muscle tissue of tunas Thunnus albacares and Katsuwonus pelamis from the Eastern Pacific Ocean.

    PubMed

    Ruelas-Inzunza, Jorge; Soto-Jiménez, Martín Federico; Ruiz-Fernández, Ana Carolina; Bojórquez-Leyva, Humberto; Pérez-Bernal, Hascibe; Páez-Osuna, Federico

    2012-12-01

    Daily mineral intake (DMI) of Cu and Zn, percentage weekly intake (PWI) of As, Cd, Hg, Pb, and doses of (210)Po were estimated by using their elemental concentration in muscle of two tuna species and the average tuna consumption in Mexico. Skipjack tuna Katsuwonus pelamis had significantly (p < 0.05) higher levels of As (1.38 μg g(-1) dw) and Cu (1.85 μg g(-1) dw) than yellowfin tuna Thunnus albacares, whereas Pb concentrations (0.18 μg g(-1) dw) were significantly (p < 0.05) higher in T. albacares. The sequence of elemental concentrations in both species was Zn > Cu > As > Hg > Pb > Cd. In T. albacares, concentrations of Cd and Pb in muscle tissue were positively correlated (p < 0.05) with weight of specimens, while Cu was negatively correlated. DMI values were below 10 %. PWI figures (<2 %) are not potentially harmful to human health. (210)Po concentration in T. albacares and K. pelamis accounts for 13.5 to 89.7 % of the median individual annual dose (7.1 μSv) from consumption of marine fish and shellfish for the world population. PMID:22684512

  13. Determination of (210)Po in calcium supplements and the possible related dose assessment to the consumers.

    PubMed

    Strumińska-Parulska, Dagmara I

    2015-12-01

    The aim of this pioneer study was to investigate the most popular calcium supplements as a potential additional source of polonium (210)Po in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The objectives of this research were to investigate the naturally occurring (210)Po activity concentrations in calcium supplements, find the correlations between (210)Po concentration in medicament and calcium chemical form, and calculate the effective radiation dose connected to analyzed calcium supplement consumption. As results showed, (210)Po concentrations in natural origin calcium supplements (especially sedimentary rocks) were higher than the other analyzed. Also the results of (210)Po analysis obtained for inorganic forms of calcium supplements were higher. The highest (210)Po activity concentrations were determined in mineral tablets made from sedimentary rocks: dolomite and chalk - 3.88 ± 0.22 and 3.36 ± 0.10 mBq g(-1) respectively; while the lowest in organic calcium compounds: calcium lactate and calcium gluconate - 0.07 ± 0.02 and 0.17 ± 0.01 mBq g(-1). The annual effective radiation doses from supplements intake were estimated as well. The highest annual radiation dose from (210)Po taken with 1 tablet of calcium supplement per day was connected to sample made from chalk - 2.5 ± 0.07 μSv year(-1), while the highest annual radiation dose from (210)Po taken with 1 g of pure calcium per day was connected to dolomite - 12.7 ± 0.70 μSv year(-1).

  14. Online Workspace to Connect Scientists with NASA's Science E/PO Efforts and Practitioners

    NASA Astrophysics Data System (ADS)

    Shipp, Stephanie; Bartolone , Lindsay; Peticolas, Laura; Woroner, Morgan; Dalton, Heather; Schwerin, Theresa; Smith, Denise

    2014-11-01

    There is a growing awareness of the need for a scientifically literate public in light of challenges facing society today, and also a growing concern about the preparedness of our future workforce to meet those challenges. Federal priorities for science, technology, engineering, and math (STEM) education call for improvement of teacher training, increased youth and public engagement, greater involvement of underrepresented populations, and investment in undergraduate and graduate education. How can planetary scientists contribute to these priorities? How can they “make their work and findings comprehensible, appealing, and available to the public” as called for in the Planetary Decadal Survey?NASA’s Science Mission Directorate (SMD) Education and Public Outreach (E/PO) workspace provides the SMD E/PO community of practice - scientists and educators funded to conduct SMD E/PO or those using NASA’s science discoveries in E/PO endeavors - with an online environment in which to communicate, collaborate, and coordinate activities, thus helping to increase effectiveness of E/PO efforts. The workspace offers interested scientists avenues to partner with SMD E/PO practitioners and learn about E/PO projects and impacts, as well as to advertise their own efforts to reach a broader audience. Through the workspace, scientists can become aware of opportunities for involvement and explore resources to improve professional practice, including literature reviews of best practices for program impact, mechanisms for engaging diverse audiences, and large- and small-scale program evaluation. Scientists will find “how to” manuals for getting started and increasing impact with public presentations, classroom visits, and other audiences, as well as primers with activity ideas and resources that can augment E/PO interactions with different audiences. The poster will introduce the workspace to interested scientists and highlight pathways to resources of interest that can help

  15. Determination of (210)Po in calcium supplements and the possible related dose assessment to the consumers.

    PubMed

    Strumińska-Parulska, Dagmara I

    2015-12-01

    The aim of this pioneer study was to investigate the most popular calcium supplements as a potential additional source of polonium (210)Po in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The objectives of this research were to investigate the naturally occurring (210)Po activity concentrations in calcium supplements, find the correlations between (210)Po concentration in medicament and calcium chemical form, and calculate the effective radiation dose connected to analyzed calcium supplement consumption. As results showed, (210)Po concentrations in natural origin calcium supplements (especially sedimentary rocks) were higher than the other analyzed. Also the results of (210)Po analysis obtained for inorganic forms of calcium supplements were higher. The highest (210)Po activity concentrations were determined in mineral tablets made from sedimentary rocks: dolomite and chalk - 3.88 ± 0.22 and 3.36 ± 0.10 mBq g(-1) respectively; while the lowest in organic calcium compounds: calcium lactate and calcium gluconate - 0.07 ± 0.02 and 0.17 ± 0.01 mBq g(-1). The annual effective radiation doses from supplements intake were estimated as well. The highest annual radiation dose from (210)Po taken with 1 tablet of calcium supplement per day was connected to sample made from chalk - 2.5 ± 0.07 μSv year(-1), while the highest annual radiation dose from (210)Po taken with 1 g of pure calcium per day was connected to dolomite - 12.7 ± 0.70 μSv year(-1). PMID:26318774

  16. Characterization of the shark myelin Po protein.

    PubMed

    Rotenstein, L; Herath, K; Gould, R M; de Bellard, M E

    2008-01-01

    Myelin, the insulating sheath made by extensive plasma membrane wrapping, is dependent on the presence of highly adhesive molecules that keep the two sides of the membrane in tight contact. The Po glycoprotein (Po) is the major component of the peripheral nervous system (PNS) myelin of mammals. The exact role that Po protein has played in the evolution of myelin is still unclear, but several phylogenetic observations suggest that it is a crucial component in the development of myelin as a multi-lamellar membrane structure. Sharks, which appeared in the fossil record about 400 million years ago, are the first fully myelinated organisms. In this study we investigated the expression pattern of shark myelin Po to suggest a way it might have played a role in the evolution of myelin in the central nervous system. We found that sharks have more than two isoforms (32, 28 and 25 kD), and that some of these might not be fully functional because they lack the domains known for Po homophilic adhesion.

  17. Effects of hot-water extract of banana (Musa acuminata) fruit's peel on the antibacterial activity, and anti-hypothermal stress, immune responses and disease resistance of the giant freshwater prawn, Macrobrachium rosenbegii.

    PubMed

    Rattanavichai, Wutti; Cheng, Winton

    2014-08-01

    The hot-extracts isolated from fruit's peel of banana, Musa acuminata, was evaluated on the antibacterial activity to pathogens from aquatic animals, and immunostimulating potential, disease resistance and anti-hypothermal stress in giant freshwater prawn, Macrobrachium rosenbergii through injection administration. The banana peel extract (BPE) showed good activity against 1 Gram-positive and 3 Gram-negative pathogens, including Lactococcus garvieae, Photobacteria damsella, Vibrio alginolyticus and Vibrio parahemolyticus especially in prawn pathogen of L. garvieae strain, which were carried out by a disk diffusion method. Prawn received BPE via injection administration at 1-6 μg (g prawn)(-1) significantly increased total haemocyte count (THC), hyaline cell (HC), granular cell (GC), phenoloxidase (PO) activity and phagocytic activity against L. garvieae from 3 to 6 days, and significantly increased clearance efficiency against L. garvieae and a significantly decreased coagulation time of prawn from 1 to 6 days. Prawn injected with BPE at 6.0 μg (g prawn)(-1) for 6 days showed significantly increased superoxide dismutase (SOD) activity, but significantly decreased respiratory bursts (RBs) of per haemocyte. Survival rates of M. rosenbergii injected with BPE at concentrations of 1, 3 and 6 μg (g prawn)(-1) were significantly higher than those injected with saline control after challenge with L. garvieae for 4-6 days, and the respective relative survival percentages of prawn were 28.6%, 38.1%, and 47.8%, respectively at 6 days. The sublethal time of prawns that had received saline and BPE at 1, 3 and 6 μg (g prawn)(-1) for 6 days and then were transferred from 28 °C to 14 °C were 69.4, 79.8, 83.6, and 90.2 h, respectively. It was concluded that the BPE can be used as the bacteriostat, and immunostimulant and physiological regulator for prawn through injection administration to enhance immunity, physiological responses, and resistance against L. garvieae.

  18. Optimization of LiFePO4 Nanoparticle Suspensions with Polyethyleneimine for Aqueous Processing

    SciTech Connect

    Li, Jianlin; Armstrong, Beth L; Kiggans, Jim; Daniel, Claus; Wood III, David L

    2012-01-01

    Addition of dispersants to aqueous based lithium-ion battery electrode formulations containing LiFePO{sub 4} is critical to obtaining a stable suspension. The resulting colloidal suspensions enable dramatically improved coating deposition when processing electrodes. This research examines the colloidal chemistry modifications based on polyethyleneimine (PEI) addition and dispersion characterization required to produce high quality electrode formulations and coatings for LiFePO{sub 4} active cathode material. The isoelectric point, a key parameter in characterizing colloidal dispersion stability, of LiFePO{sub 4} and super P C45 were determined to be pH = 4.3 and 3.4, respectively. PEI, a cationic surfactant, was found to be an effective dispersant. It is demonstrated that 1.0 wt % and 0.5 wt % PEI were required to stabilize the LiFePO{sub 4} and super P C45 suspension, respectively. LiFePO{sub 4} cathode suspensions with 1.5 wt % PEI demonstrated the best dispersibility of all components, as evidenced by viscosity and agglomerate size of the suspensions and elemental distribution within dry cathodes. The addition of PEI significantly improved the LiFePO{sub 4} performance.

  19. Modeling Li-ion conductivity in LiLa(PO3)4 powder

    NASA Astrophysics Data System (ADS)

    Mounir, Ferhi; Karima, Horchani-Naifer; Khaled, Ben Saad; Mokhtar, Férid

    2012-07-01

    Polycrystalline powder and single-crystal of LiLa(PO3)4 are synthesized by solid state reaction and flux technique, respectively. A morphological description of the obtained product was made based on scanning electron microscopy micrographs. The obtained powder was characterized by X-ray powder diffraction, FTIR and Raman spectroscopies. Ionic conductivity of the LiLa(PO3)4 powder was measured and evaluated over a temperature range from 553 to 913 K. Single crystals of LiLa(PO3)4 are characterized by single-crystal X-ray diffraction. The LiLa(PO3)4 structure was found to be isotypic with LiNd(PO3)4. It crystallizes in the monoclinic system with space group C2/c and cell parameters: a=16.635(6) Å, b=7.130(3) Å, c=9.913(3) Å, β=126.37(4)°, V=946.72(6) Å3 and Z=4. The LiLa(PO3)4 structure was described as an alternation between spiraling chains (PO3)n and (La3+, Li+) cations along the b direction. The small Li+ ions, coordinated to four oxygen atoms, were located in the large connected cavities created between the LaO8 polyhedra and the polyphosphate chains. The jumping of Li+ through tunnels of the crystalline network was investigated using complex impedance spectroscopy. The close value of the activation energies calculated through the analysis of conductivity data and loss spectra indicate that the transport in the investigated system is through hopping mechanism. The correlation between ionic conductivity of LiLa(PO3)4 and its crystallographic structure was investigated and the most probably transport pathway model was determined.

  20. Transcutaneous pO2 of volunteers during hyperbaric oxygenation.

    PubMed

    Huch, A; Huch, R; Hollmann, G; Hockerts, T; Keller, H P; Seiler, D; Sadzek, J; Lübbers, D W

    1977-01-01

    Continuous transcutaneous pO2 measurements (tcPO2 measurements) were performed in healthy volunteers who were breathing air and oxygen under hyperbaric conditions (max. 4 ata). The results show a close correlation of PO2 values measured by the noninvasive method, in blood from discret arterial punctures, chamber PO2, respectively, the PO2 of the inspiratory gas mixture which was checked up to maximal values of 2,200 mm Hg. The PO2 in the arterial blood samples was measured immediately after the puncture insight the hyperbaric chamber using a specially designed through electrode. PMID:610774

  1. Effect of the synthesis conditions on the electrochemical properties of LiFePO{sub 4} obtained from NH{sub 4}FePO{sub 4}

    SciTech Connect

    Prosini, Pier Paolo Gislon, Paola; Cento, Cinzia; Carewska, Maria; Masci, Amedeo

    2013-09-01

    Graphical abstract: - Highlights: • Four different samples of FAP were synthesized by precipitation techniques. • The samples were used as precursors to synthesize electrochemical active LiFePO{sub 4}. • Their morphology, composition, structure and electrochemical performance were studied. • The LiFePO{sub 4} electrochemical performance resulted affected by the preparation method - Abstract: In this paper the morphological, structural and electrochemical properties of crystalline lithium iron phosphate (LiFePO{sub 4}) obtained from ferrous ammonium phosphate (FAP) have been studied. The FAP was obtained following four different processes, namely: (1) homogeneous phase precipitation, (2) heterogeneous phase precipitation from stoichiometric sodium phosphate, (3) heterogeneous phase precipitation from stoichiometric ammonium phosphate, and (4) heterogeneous phase precipitation from over stoichiometric ammonium phosphate. Lithium iron phosphate was prepared by solid state reaction of FAP with lithium hydroxide. In order to evaluate the effect of reaction time and synthesis temperature the LiFePO{sub 4} was prepared varying the heating temperatures (550, 600 and 700 °C) and the reaction times (1 or 2 h). The morphology of the materials was evaluated by scanning electron microscopy while the chemical composition was determined by electron energy loss spectroscopy. X-ray diffraction was used to evaluate phase composition, crystal structure and crystallite size. The so obtained LiFePO{sub 4}'s were fully electrochemical characterized and a correlation was found between the crystal size and the electrochemical performance.

  2. Caspase-1-like regulation of the proPO-system and role of ppA and caspase-1-like cleaved peptides from proPO in innate immunity.

    PubMed

    Jearaphunt, Miti; Noonin, Chadanat; Jiravanichpaisal, Pikul; Nakamura, Seiko; Tassanakajon, Anchalee; Söderhäll, Irene; Söderhäll, Kenneth

    2014-04-01

    Invertebrates rely on innate immunity to respond to the entry of foreign microorganisms. One of the important innate immune responses in arthropods is the activation of prophenoloxidase (proPO) by a proteolytic cascade finalized by the proPO-activating enzyme (ppA), which leads to melanization and the elimination of pathogens. Proteolytic cascades play a crucial role in innate immune reactions because they can be triggered more quickly than immune responses that require altered gene expression. Caspases are intracellular proteases involved in tightly regulated limited proteolysis of downstream processes and are also involved in inflammatory responses to infections for example by activation of interleukin 1ß. Here we show for the first time a link between caspase cleavage of proPO and release of this protein and the biological function of these fragments in response to bacterial infection in crayfish. Different fragments from the cleavage of proPO were studied to determine their roles in bacterial clearance and antimicrobial activity. These fragments include proPO-ppA, the N-terminal part of proPO cleaved by ppA, and proPO-casp1 and proPO-casp2, the fragments from the N-terminus after cleavage by caspase-1. The recombinant proteins corresponding to all three of these peptide fragments exhibited bacterial clearance activity in vivo, and proPO-ppA had antimicrobial activity, as evidenced by a drastic decrease in the number of Escherichia coli in vitro. The bacteria incubated with the proPO-ppA fragment were agglutinated and their cell morphology was altered. Our findings show an evolutionary conserved role for caspase cleavage in inflammation, and for the first time show a link between caspase induced inflammation and melanization. Further we give a more detailed understanding of how the proPO system is regulated in time and place and a role for the peptide generated by activation of proPO as well as for the peptides resulting from Caspase 1 proteolysis.

  3. Synthesis and tunable luminescence of RbCaGd(PO4)2:Ce3+, Mn2+ phosphors

    NASA Astrophysics Data System (ADS)

    Chen, Xue; Lv, Fengzhu; Li, Penggang; Zhang, Yihe

    2016-04-01

    RbCaGd(PO4)2 doped with Ce3+, Mn2+ was synthesized by the sol-gel method. The crystal structure and crystallographic location of Ce3+ in RbCaGd(PO4)2 were identified by Rietveld refinement. Powder X-ray diffraction (XRD) revealed that the structure of RbCaGd(PO4)2:Ce3+ compounds is hexagonal structure which is similar to that of hexagonal LnPO4 with the lattice constant of a = b = 7.005(57) Å, c = 6.352(05) Å, and V (cell volume) = 269.980 Å3. The photoluminescence behavior and emission mechanism were studied systematically by doping activators in the RbCaGd(PO4)2 host. The Mn2+ incorporated RbCaGd(PO4)2:Ce3+, Mn2+ compounds exhibited blue emission from the parity- and spin-allowed f-d transition of Ce3+ and orange-to-red emission from the forbidden 4T1 → 6A1 transition of Mn2+. The emission chromaticity coordinates of RbCaGd(PO4)2:0.10Ce3+, xMn2+ (x = 0.16, 0.25) are close to the white region due to an energy transfer process and the energy transfer mechanism from Ce3+ to Mn2+ in the RbCaGd(PO4)2 host was dominated by dipole-dipole interactions.

  4. Tribolium castaneum Apolipophorin-III acts as an immune response protein against Bacillus thuringiensis Cry3Ba toxic activity.

    PubMed

    Contreras, Estefanía; Rausell, Carolina; Real, M Dolores

    2013-07-01

    In this study, a 2.1-fold Apolipophorin-III mRNA up-regulation was found in Tribolium castaneum larvae challenged with Bacillus thuringiensis Cry3Ba spore-crystal mixture. Knockdown of Apolipophorin-III by RNAi resulted in increased T. castaneum larvae susceptibility following Cry3Ba spore-crystal treatment, demonstrating Apolipophorin-III involvement in insect defense against B. thuringiensis. We showed that Apolipophorin-III participates in T. castaneum immune response to B. thuringiensis activating the prophenoloxidase cascade since: (i) phenoloxidase activity significantly increased after Cry3Ba spore-crystal treatment compared to untreated or Cry1Ac spore-crystal treated larvae and (ii) phenoloxidase activity in Cry3Ba spore-crystal treated Apolipophorin-III silenced larvae was 71±14% lower than that of non-silenced intoxicated larvae.

  5. (210)Po and (210)Pb in medicinal plants in the region of Karnataka, Southern India.

    PubMed

    Chandrashekara, K; Somashekarappa, H M

    2016-08-01

    The activity concentrations of naturally occurring radionuclides (210)Po and (210)Pb were estimated in some selected medicinal plants and soil samples of coastal Karnataka in India. The mean activity concentrations of (210)Po and (210)Pb varied in the range of 4.7-42.9 Bq kg(-1) (dry weight) and 36.1-124 Bq kg(-1) (dry weight) in the soil samples, and 3.3-63.7 Bq kg(-1) (dry weight) and 12.0-406 Bq kg(-1) (dry weight), in the medicinal plant samples, respectively. The plants, Ocimum sanctum L. and Plectranthus amboinicus (Lour.) Spreng had significantly higher activity concentrations of (210)Po and (210)Pb than other species sampled. In spite of disequilibrium between them, these two radionuclides were well correlated in both soil and medicinal plants. PMID:27155527

  6. Shape Coexistence in Neutron Deficient Po Nuclei

    SciTech Connect

    Helariutta, K.; Cocks, J.F.C.; Enqvist, T.; Greenlees, P.T.; Jones, P.; Julin, R.; Juutinen, S.; Jamsen, P.; Kankaanpaa, H.; Kettunen, H.; Kuiusiniemi, P.; Leino, M.; Muikkui, M.; Piiparinen, M.; Rahkila, P.; Savelius, A.; Trzaska, W.H.; Tormanen, S.; Uusitalo, J.; Allatt, R.G.; Butler, P.A.; Page, R.D.; Kapusta, M.

    1999-12-31

    The excited levels in {sup 192-195}Po have been studied using the recoil-decay tagging method. New levels have been identified. The data are in accordance with the scheme of the coexisting spherical and deformed intruder structures crossing each other with N<112.

  7. Shape coexistence in neutron deficient Po nuclei

    SciTech Connect

    Helariutta, K.; Cocks, J. F. C.; Enqvist, T.; Greenlees, P. T.; Jones, P.; Julin, R.; Juutinen, S.; Jaemsen, P.; Kankaanpaeae, H.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Piiparinen, M.; Rahkila, P.; Savelius, A.; Trzaska, W. H.; Toermaenen, S.; Uusitalo, J.; Allatt, R. G.

    1999-11-16

    The excited levels in {sup 192-195}Po have been studied using the recoil-decay tagging method. New levels have been identified. The data are in accordance with the scheme of the coexisting spherical and deformed intruder structures crossing each other with N<112.

  8. Electronic Properties of LiFePO4 and Li doped LiFePO4

    SciTech Connect

    Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

    2006-05-31

    LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that the charge created by doping is not delocalized in the manner of electrons or holes in a semiconductor.

  9. Electronic states and potential energy surfaces of H2Te, H2Po, and their positive ions

    NASA Astrophysics Data System (ADS)

    Sumathi, K.; Balasubramanian, K.

    1990-06-01

    Geometries, bond energies, ionization potentials, dipole moments, other one-electron properties, and potential energy surfaces of six valence electronic states of H2Te and H2Po species are obtained using the relativistic complete active space multiconfiguration self-consistent field (CASSCF) followed by full second-order configuration interaction (SOCI) and relativistic configuration interaction (RCI) calculations including spin-orbit coupling. In addition, Rydberg states of H2Te and H2Se are studied to interpret the experimental spectra. The potential energy surfaces of two electronic states of H2Te+ and H2Po+ are obtained. The ground states of both H2Te and H2Po are found to be of X 1A1(A1) symmetry with bent (C2v) equilibrium geometries of H2Te:re =1.668 Å, θe=91.2°; and H2Po:re =1.835 Å and θe=90.9°. The ground states of H2Te+ and H2Po+ are X 2B1 with H2Te+:re =1.676 Å, θe=90.7° and H2Po+:re =1.828 Å and θe=88°. The De (HTe-H) and De (HPo-H) including spin-orbit effects are calculated as 63.2 and 39.4 kcal/mol, respectively. The X 2B1(E)-A 2A1(E) energy separations of H2Te+ and H2Po+ ions are calculated as 66.6 and 76 kcal/mol, respectively. The adiabatic IPs of H2Te and H2Po are calculated as 8.47 and 7.79 eV, respectively. In addition CASSCF/SOCI/RCI calculations are also carried out on the X 2Π3/2 and 2Π1/2 states of TeH and PoH diatomics. The X 2Π3/2-2Π1/2 energy separations of TeH and PoH are computed as 3710 and 9920 cm-1, respectively. Spin-orbit effects are thus found to be very significant for PoH and H2Po. All excited states of H2Te and H2Po are above 3.7 and 3.1 eV, respectively. Properties and energy separations of H2Te and H2Po are compared with the lighter group (VI) H2Ch species.

  10. Distribution of Po-210 in two species of predatory marine fish from the Brazilian coast.

    PubMed

    Mársico, E T; Ferreira, M S; São Clemente, S C; Gouvea, R C S; Jesus, E F O; Conti, C C; Conte, C A; Kelecom, A G A C

    2014-02-01

    Polonium-210 ((210)Po) concentration was quantified in the muscle tissue and organs of two predatory marine fishes (Genypterus brasiliensis and Cynoscion microlepidotus) from Cabo Frio, Rio de Janeiro, Brazil. The species C. microlepidotus, a benthic carnivore, registered higher (210)Po in its tissue. The organs associated with digestion displayed the maximum radionuclide compared with other organs. The average activity was 2 mBq kg(-1) for G. brasiliensis and it was 6 mBq kg(-1) for C. microlepidotus. The activity concentrations varied significantly between the species and among organs.

  11. Distribution of Po-210 in two species of predatory marine fish from the Brazilian coast.

    PubMed

    Mársico, E T; Ferreira, M S; São Clemente, S C; Gouvea, R C S; Jesus, E F O; Conti, C C; Conte, C A; Kelecom, A G A C

    2014-02-01

    Polonium-210 ((210)Po) concentration was quantified in the muscle tissue and organs of two predatory marine fishes (Genypterus brasiliensis and Cynoscion microlepidotus) from Cabo Frio, Rio de Janeiro, Brazil. The species C. microlepidotus, a benthic carnivore, registered higher (210)Po in its tissue. The organs associated with digestion displayed the maximum radionuclide compared with other organs. The average activity was 2 mBq kg(-1) for G. brasiliensis and it was 6 mBq kg(-1) for C. microlepidotus. The activity concentrations varied significantly between the species and among organs. PMID:24334195

  12. Synthesis of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction with enhanced photocatalytic performance

    SciTech Connect

    He, Peizhi; Song, Limin; Zhang, Shujuan; Wu, Xiaoqing; Wei, Qingwu

    2014-03-01

    Graphical abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The results show that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} possesses a much higher activity for the decomposition of RhB than that of the pure Ag{sub 3}PO{sub 4} particles. The most mechanism is that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst can efficiently separate the photogenerated electron–hole pairs, enhancing the photocatalytic activity of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} composites. - Highlights: • g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction showed much higher activity than that of Ag{sub 3}PO{sub 4}. • The high activity could be attributed to g-C{sub 3}N{sub 4} for modifying Ag{sub 3}PO{sub 4}. • More ·OH radicals may be significant reason to improve Ag{sub 3}PO{sub 4} activity. - Abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The photocatalysts were characterized by X-ray powder diffraction, transmission electron microscopy, UV–vis absorption spectroscopy and Fourier transform infrared spectroscopy. The photocatalytic activities of the obtained samples were tested by using Rhodamine B (RhB) as the degradation target under visible light irradiation. g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} decomposed RhB more effectively than the pure Ag{sub 3}PO{sub 4} particles did, and 2 wt.% g-C{sub 3}N{sub 4} had the highest activity. Furthermore, 2 wt.% g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} degraded high-concentration RhB more potently than unmodified Ag{sub 3}PO{sub 4} did, probably because g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst enhanced the photocatalytic activity by efficiently separating the photogenerated electron–hole pairs.

  13. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Powers of a PO. 604.36 Section 604.36 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.36 Powers of a PO. A PO may: (a) Give notice...

  14. 49 CFR 604.46 - Recommended decision by a PO.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Recommended decision by a PO. 604.46 Section 604... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.46 Recommended decision by a PO. (a) The PO shall issue a recommended decision based on the record developed during the proceeding...

  15. 49 CFR 604.46 - Recommended decision by a PO.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Recommended decision by a PO. 604.46 Section 604... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.46 Recommended decision by a PO. (a) The PO shall issue a recommended decision based on the record developed during the proceeding...

  16. 49 CFR 604.46 - Recommended decision by a PO.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Recommended decision by a PO. 604.46 Section 604... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings. § 604.46 Recommended decision by a PO. (a) The PO shall issue a recommended decision based on the record developed during the proceeding...

  17. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Powers of a PO. 604.36 Section 604.36 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings. § 604.36 Powers of a PO. A PO may: (a) Give notice...

  18. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Powers of a PO. 604.36 Section 604.36 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings. § 604.36 Powers of a PO. A PO may: (a) Give notice...

  19. 49 CFR 604.46 - Recommended decision by a PO.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Recommended decision by a PO. 604.46 Section 604... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.46 Recommended decision by a PO. (a) The PO shall issue a recommended decision based on the record developed during the proceeding...

  20. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Powers of a PO. 604.36 Section 604.36 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.36 Powers of a PO. A PO may: (a) Give notice...

  1. 49 CFR 604.46 - Recommended decision by a PO.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Recommended decision by a PO. 604.46 Section 604... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings. § 604.46 Recommended decision by a PO. (a) The PO shall issue a recommended decision based on the record developed during the proceeding...

  2. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Powers of a PO. 604.36 Section 604.36 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL TRANSIT ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings § 604.36 Powers of a PO. A PO may: (a) Give notice...

  3. Accumulation of polonium 210Po in tissues and organs of deer carvidae from Northern Poland.

    PubMed

    Skwarzec, Bogdan; Prucnal, Malgorzata

    2007-01-01

    This study was undertaken to provide information on accumulation of polonium in tissues and organs of deer carvidae in order to assess the potential transport of this element via food-chain to game meat consumers. Livers, kidneys and muscles of large herbivorous animals belonging to three species: roe deer (Capreolus capreolus), red deer (Cervus elaphus) and fallow deer (Dama dama), collected in Northern Poland, were the subject of the present investigation. Activities of (210)Po were determined by means of alpha spectrometry along with relevant radiochemical procedures. The concentration of (210)Po in analyzed animals decreased in the order kidney > liver > muscle tissue. The average activity concentrations of (210)Po ranged between 0.02 +/- 0.01 Bq. kg(- 1) w.w. in muscles and 7.15 +/- 0.12 Bq. kg(- 1) w.w. in kidneys. Levels of polonium were not influenced by sampling location, sex, age and species of animals.

  4. [Effect of population density on enzymatic activity of antioxidative and phenol oxidase systems of imagoes and nymphs of the marble cockroach Nauphoeta cinerea].

    PubMed

    Murzagulov, G S; Saltykova, E S; Gaĭfullina, L R; Nikolenko, A G

    2013-01-01

    The work deals with effect of density of population on functional activity of components pf protective system of adult individuals and nymphs of the marble cockroach. The resistance of individuals has been noted to decrease both at individual maintenance and under conditions of overpopulation. Changes in activities of enzymes of antioxidative and phenoloxidase systems are studied ion the insect hemolymph and intestine. Possible consequences of isolation and overpopulation are discussed both for stability and for individual development.

  5. Development of an Ultra-Pure, Carrier-Free 209Po Solution Standard

    PubMed Central

    Collé, R.; Fitzgerald, R. P.; Laureano-Perez, L.

    2015-01-01

    Ultra-pure, carrier-free 209Po solution standards have been prepared and standardized for their massic alpha-particle emission rate. The standards, which will be disseminated by the National Institute of Standards and Technology (NIST) as Standard Reference Material SRM 4326a, have a mean mass of (5.169 ± 0.003) g of a solution of polonium in nominal 2.0 mol▪L−1 HCl (having a solution density of (1.032 ± 0.002) g▪ mL−1 at 20 °C) that are contained in 5 mL, flame-sealed, borosilicate glass ampoules. They are certified to contain a 209Po massic alpha-particle emission rate of (39.01 ± 0.18) s−1▪g−1 as of a reference time of 1200 EST, 01 December 2013. This new standard series replaces SRM 4326 that was issued by NIST in 1994. The standardization was based on 4πα liquid scintillation (LS) spectrometry with two different LS counting systems and under wide variations in measurement and counting source conditions. The methodology for the standardization, with corrections for detection of the low-energy conversion electrons from the delayed 2 keV isomeric state in 205Pb and for the radiations accompanying the small 0.45 % electron-capture branch to 209Bi, involves a unique spectral analysis procedure that is specific for the case of 209Po decay. The entire measurement protocol is similar, but revised and improved from that used for SRM 4326. Spectroscopic impurity analyses revealed that no photon-emitting or alpha-emitting radionuclidic impurities were detected. The most common impurity associated with 209Po is 208Po and the activity ratio of 208Po/209Po was < 10−7. PMID:26958444

  6. Development of an Ultra-Pure, Carrier-Free (209)Po Solution Standard.

    PubMed

    Collé, R; Fitzgerald, R P; Laureano-Perez, L

    2015-01-01

    Ultra-pure, carrier-free (209)Po solution standards have been prepared and standardized for their massic alpha-particle emission rate. The standards, which will be disseminated by the National Institute of Standards and Technology (NIST) as Standard Reference Material SRM 4326a, have a mean mass of (5.169 ± 0.003) g of a solution of polonium in nominal 2.0 mol▪L(-1) HCl (having a solution density of (1.032 ± 0.002) g▪ mL(-1) at 20 °C) that are contained in 5 mL, flame-sealed, borosilicate glass ampoules. They are certified to contain a (209)Po massic alpha-particle emission rate of (39.01 ± 0.18) s(-1)▪g(-1) as of a reference time of 1200 EST, 01 December 2013. This new standard series replaces SRM 4326 that was issued by NIST in 1994. The standardization was based on 4πα liquid scintillation (LS) spectrometry with two different LS counting systems and under wide variations in measurement and counting source conditions. The methodology for the standardization, with corrections for detection of the low-energy conversion electrons from the delayed 2 keV isomeric state in (205)Pb and for the radiations accompanying the small 0.45 % electron-capture branch to (209)Bi, involves a unique spectral analysis procedure that is specific for the case of (209)Po decay. The entire measurement protocol is similar, but revised and improved from that used for SRM 4326. Spectroscopic impurity analyses revealed that no photon-emitting or alpha-emitting radionuclidic impurities were detected. The most common impurity associated with (209)Po is (208)Po and the activity ratio of (208)Po/(209)Po was < 10(-7). PMID:26958444

  7. Enhanced visible-light photocatalytic performances of Ag3PO4 surface-modified with small amounts of TiO2 and Ag

    NASA Astrophysics Data System (ADS)

    Wang, Desong; Li, Lei; Luo, Qingzhi; An, Jing; Li, Xueyan; Yin, Rong; Zhao, Mangmang

    2014-12-01

    A novel approach has been developed to prepare an efficient visible-light photocatalyst using Ag3PO4 and TiO2 sol as precursors. First, Ag3PO4 particles were dipped into TiO2 sol for 5 min and were filtered quickly. Second, Ag3PO4 particles adsorbing a small amount of TiO2 sol were aged for 24 h to form TiO2 gel on their surface. Finally, Ag3PO4 particles covered by TiO2 gel were calcined at 450 °C for 2 h to obtain the surface-modified Ag3PO4 sample. The surface-modified Ag3PO4 was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The visible-light photocatalytic performances of the surface-modified Ag3PO4 were evaluated by the photodegradation of methyl orange or phenol solution. The results showed that the surface-modified Ag3PO4 exhibited much higher visible-light photocatalytic activity and stability than pure Ag3PO4. As the amount of TiO2 gel on the Ag3PO4 surface increased, the visible-light photocatalytic activity increased first and then decreased. The surface-modification of Ag3PO4 obviously decreased its solubility in water environment due to the protection of TiO2 and Ag nanocrystals on the surface. The visible-light photocatalytic mechanism of the surface-modified Ag3PO4 has been discussed.

  8. Half-life of /sup 218/Po

    SciTech Connect

    Potapov, V.G.; Soloshenkov, P.S.

    1986-10-01

    The decay of Po 218 is accompanied by the emission of 6.00-MeV alpha particles. The most suitable method for studying it is the alphaspectrometric method. To generate radon, the source for RaA, the authors used a preparation of Ra 226 with a high degree of purity. Targets were prepared for measuring the half-life on a radon setup. Approximately 30 sec after holding in a radon atmosphere the target was placed with the polonium deposited on it into a vacuum chamber. It was noted that the intensity of the peak at 6.70 MeV decreases at the same rate as the decay of Po 218, and the ratio of the intensities of their peaks was equal to 0.037 +/- 0.007%. The spectra (alpha was analyzed on an LP-4900 analyzer. The values of the half-life that were obtained are in good agreement with the values obtained previously.

  9. PoET: Polarimeters for Energetic Transients

    NASA Technical Reports Server (NTRS)

    McConnell, Mark; Barthelmy, Scott; Hill, Joanne

    2008-01-01

    This presentation focuses on PoET (Polarimeters for Energetic Transients): a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2-15 keV and a high energy polarimeter (Gamma-Ray Polarimeter Experiment - GRAPE) that will measure polarization in the 60-500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The PoET spacecraft provides a zenith-pointed platform for maximizing the exposure to deep space. Spacecraft rotation will provide a means of effectively dealing with systematics in the polarization response. PoET will provide sufficient sensitivity and sky coverage to measure statistically significant polarization for up to 100 GRBs in a two-year mission. Polarization data will also be obtained for solar flares, pulsars and other sources of astronomical interest.

  10. Occurrence and distribution of 210Pb and 210Po in selected California groundwater wells.

    PubMed

    Ruberu, Shiyamalie R; Liu, Yun-Gang; Perera, S Kusum

    2007-05-01

    Groundwater wells from across the State of California were sampled and analyzed for Pb and Po. The separation method involved Fe(OH)3 precipitation from a 5-L groundwater sample followed by electrodeposition of Po on a nickel disk. The resulting solution was passed through an ion-exchange resin column for the isolation of Pb. De-ionized water spiked at a concentration range from 4.92 mBq L(-1) to 755 mBq L(-1) with these radionuclide standards showed excellent accuracy and precision of the method. In the groundwater wells, overall activity of Pb ranged from 3.7 mBq L(-1) to 1,481 mBq L(-1) and the Po activity ranged from 0.25 mBq L(-1) to 555 mBq L(-1). Of the select wells tested, 27% for Pb and 19% for Po were above the proposed maximum contamination limits for these radionuclides, which are set at 37 mBq L(-1) and 26 mBq L(-1), respectively. From a public health perspective this is a concern, since the drinking water screening levels for gross alpha is at 555 mBq L(-1) and gross beta is at 1,850 mBq L(-1). At such high screening levels Pb and Po will not be captured, and this situation was found in several of the wells studied. The occurrence of Pb and Po are not correlated within the sources, however; the polonium concentrations were always lower than the lead concentrations. Activities of Pb measured from wells two years apart clearly demonstrated the continuous flux of groundwater within aquifers.

  11. DL-/PO-phosphatidylcholine restores restraint stress-induced depression-related behaviors and spatial memory impairment.

    PubMed

    Kanno, Takeshi; Jin, Yu; Nishizaki, Tomoyuki

    2014-09-01

    The present study investigated the effects of 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DL-PC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (PO-PC) on depression-related behaviors and spatial memory impairment in mice subjected to restraint stress. The immobility time in forced-swim and tail-suspension tests for mice subjected to restraint stress was significantly longer than that for nonstressed control mice, and oral coadministration of DL-PC and PO-PC (DL-/PO-PC; DL-PC : PO-PC=1 : 1) shortened the prolonged immobility time in a dose (0.1-5 mg/kg)-dependent manner. In the water maze test, the retention latency for stressed mice was significantly longer than that for control mice and DL-/PO-PC (1 mg/kg, per os) reversed the prolonged latency to control levels. Phosphorylation of Akt and glycogen synthase kinase 3β (GSK-3β) in the hypothalamus of stressed mice was significantly reduced compared with that for control mice, and DL-/PO-PC (1 mg/kg, per os) recovered the reduced phosphorylation of Akt and GSK-3β. The results of the present study indicate that DL-/PO-PC has the potential to ameliorate stress-induced depression-related behaviors and memory impairment, possibly by activating Akt and inhibiting GSK-3β.

  12. Preparation of LiCoPO 4/C nanocomposite cathode of lithium batteries with high rate performance

    NASA Astrophysics Data System (ADS)

    Doan, The Nam Long; Taniguchi, Izumi

    LiCoPO 4/C nanocomposites could be successfully prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment. X-ray diffraction analysis confirmed that the LiCoPO 4/C nanocomposites were well crystallized in an orthorhombic structure with Pmna space group. Scanning electron microscopy and transmission electron microscopy with equipped energy dispersive spectroscopy verified that the LiCoPO 4/C nanocomposites were the agglomerates of LiCoPO 4 primary particles with a geometric mean diameter of 87 nm, and the carbon was well distributed on the surface of the agglomerates. The LiCoPO 4/C nanocomposites were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1 M LiPF 6 in EC:DMC = 1:1|LiCoPO 4/C at various charge-discharge rates. The cells delivered first discharge capacities of 142 and 109 mAh g -1 at 0.05 and 20 C, respectively. Furthermore, the discharge capacity after 40 cycles corresponded to 87% of initial one at 0.1 C rate. The excellent rate capability of the cells is mainly due to the well distributed carbon on the LiCoPO 4 agglomerates, and a much smaller lithium ion diffusion distance in the electrode.

  13. sup 210 Po and sup 210 Pb remobilization from lake sediments in relation to iron and manganese cycling

    SciTech Connect

    Benoit, G.; Hemond, H.F. )

    1990-08-01

    The behavior of {sup 210}Po and {sup 210}Pb was studied in the water column of an oligotrophic, dimictic lake. Direct uptake of the radionuclides by sediments was negligible compared to removal on particles, and {sup 210}Pb scavenging was 4 times that of {sup 210}Po. Both nuclides were found to be significantly remobilized from sediments into the stratified, anoxic water column. Releases seem to be linked to the cycling of the transition metals, iron and possibly manganese. The distribution of both iron and {sup 210}Pb in stratified, anoxic waters can be modeled as constant release and rapid horizontal mixing/dilution; vertical turbulent transport had a negligible effect on element distributions. Upon contact with oxygen, iron rapidly reprecipitates, forming a particulate maximum and rescavenging {sup 210}Pb. Unlike {sup 210}Pb, much {sup 210}Po is released from sediments before overlying water becomes completely anoxic, leading to unsupported {sup 210}Po. {sup 210}Po cycling in the stratified water column is more complex than that of {sup 210}Pb, and additional removal mechanism(s) may be active, including perhaps oxidation of soluble Po(II) to insoluble Po(IV).

  14. Scientist-Educator Partnerships: the Cornerstone of Astrophysics E/PO

    NASA Astrophysics Data System (ADS)

    Meinke, Bonnie K.; Smith, Denise A.; Lawton, Brandon; Eisenhamer, Bonnie; Jirdeh, Hussein

    2015-11-01

    For nearly two decades, NASA has partnered scientists and educators by embedding Education and Public Outreach (E/PO) programs and funding in its science missions and research activities. This enables scientist and educators to work side-by-side in translating cutting-edge NASA science and technology for classrooms, museums, and public venues.The Office of Public Outreach at the Space Telescope Science Institute (STScI) is uniquely poised to foster collaboration between scientists with content expertise and educators with pedagogy expertise. As home to both Hubble Space Telescope and the future James Webb Space Telescope, STScI leverages the expertise of its scientists to create partnerships with its collocated Education Team to translate cutting-edge NASA science into new and effective learning tools. In addition, STScI is home of the NASA Science Mission Directorate (SMD) Astrophysics Science E/PO Forum, which facilitates connections both within the SMD E/PO community and beyond to scientists and educators across all NASA Astrophysics missions. These collaborations strengthen partnerships, build best practices, and enhance coherence for NASA SMD-funded E/PO missions and programs.We will present examples of astronomers’ engagement in our E/PO efforts, such as NASA Science4Girls.

  15. Comparison of various dissolution techniques for determination of Po-210 in biological samples.

    PubMed

    Planinšek, P; Benedik, L; Smodiš, B

    2013-11-01

    The aim of the present study was to compare three wet digestion procedures for dissolution of biological samples in the determination of Po-210. Classical wet ashing over a gas flame with acids in a long-necked Kjeldahl flask, digestion with acids in an Erlenmeyer flask and microwave digestion in a Teflon vessel at temperatures at up to 200°C were investigated. The results obtained showed that the activity concentrations of Po-210 found in the samples analysed were comparable for all the procedures used.

  16. NaCo(H2PO2)3: Crystal structure and physical study

    NASA Astrophysics Data System (ADS)

    El Bali, Brahim; Lachkar, Mohammed; Essehli, Rachid; Dusek, Michal; Rohlicek, Jan; Mircescu, Nicoleta; Haisch, Christoph

    2016-11-01

    NaCo(H2PO2)3 was synthesized in solution and its structure was studied by single-crystal X-ray diffraction. It crystallizes in the cubic space group P213 (#198), Z = 4, a = 9.2563(16) Å, V = 793.1(2) Å3. Final residual factors of the refined structure model R/Rw were 0.0367/0.0941. The cations Na+ and Co2+ are both octahedrally coordinated. [NaO6] and [CoO6] share edges to form channels propagating along [1,-1, -1] with the [H2PO2] pseudo-pyramids adjusted inside the channels to the above mentioned octahedra. The IR and Raman spectroscopic studies show the expected bands of the hypophosphite anion. NaCo(H2PO2)3 did not show any electrochemical activity under the electrochemical test conditions (2.4-4.5 V vs. Na/Na+).

  17. The disequilibrium between 210Po and 210Pb in raw and drinking waters.

    PubMed

    Idoeta, R; Herranz, M; Legarda, F

    2011-01-01

    Many countries have to monitor and control the radioactivity in drinking waters in order to ensure compliance with the requirements of their respective regulations. Among radionuclides responsible for this radioactivity there are (210)Po and (210)Pb, which are usually not in radioactive equilibrium in waters. This paper deals with the analysis of this disequilibrium and the way that the water treatment plants affect it. To do this, (210)Po and (210)Pb activity concentrations were measured in raw and drinking water. The measurements were performed by alpha-particle spectrometry and gas flow proportional counting and the corresponding formulae for uncertainties and detection limits are presented. The values obtained show that the Po/Pb ratio is lower in surface than in ground waters. Regarding water treatment, this ratio adopts values lower in drinking water than in raw waters. In any case, for the waters analysed in this work the committed effective doses due to these radionuclides, are negligible.

  18. Synthesis and luminescence properties of KSrPO4:Eu2+ phosphor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Palan, C. B.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The KSrPO4:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO4:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO4:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al2O3:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activation energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.

  19. STEREO-IMPACT E/PO: Getting Ready for Launch!

    NASA Astrophysics Data System (ADS)

    Mendez, B. J.; Peticolas, L. M.; Craig, N.

    2005-12-01

    The Solar Terrestrial Relations Observatory (STEREO) is scheduled for launch in April/May 2006. STEREO will study the Sun with two spacecraft on either side of Earth in orbit around the Sun. The primary science goal is to understand the nature of Coronal Mass Ejections (CMEs). The E/PO program for the IMPACT suite of instruments aboard the two crafts is planning several activities leading up to launch to raise awareness and interest in the mission and its scientific discoveries. We will be participating in NASA's Sun-Earth day events which are scheduled to coincide with a total solar eclipse in March. This event offers a good opportunity to engage the public in STEREO science, because an eclipse allows one to see the solar corona from where CMEs erupt. We will be conducting teacher workshops locally in California and also at the annual conference of the National Science Teachers Association. At these workshops, we will focus on the basics of magnetism and then its connection to CMEs and Earth's magnetic field, leading to the questions STEREO scientists hope to answer. In addition, we will be working with NASA's Public Relations office to ensure that STEREO E/PO programs are highlighted in press releases about the mission.

  20. Solid Solution Phases in the Olivine-Type LiMnPO4/MnPO4 System

    SciTech Connect

    Chen, Guoying; Richardson, Thomas J.

    2009-04-07

    Nonstoichiometry is reported in the LiMnPO{sub 4}/MnPO{sub 4} system for the first time. As lithium is removed from crystalline LiMnPO{sub 4} by chemical or electrochemical methods, the resulting two phase mixture consists of stoichiometric LiMnPO{sub 4} and a delithiated phase, Li{sub y}MnPO{sub 4}, whose lattice parameters depend upon the global extent of delithiation and on the crystalline domain size of the delithiated phase. This behavior is reproduced during electrochemical insertion of lithium. Again, no evidence for nonstoichiometry was found in the vicinity of LiMnPO{sub 4}. Attempts to create single phase solid solutions by heating mixtures of the two phases failed due to the thermal instability of Li{sub y}MnPO{sub 4}.

  1. [An increase in the immune system activity of the wax moth Galleria mellonella and of the Colorado potato beetle Leptinotarsa decemlineata under effect of organophosphorus insecticide].

    PubMed

    2013-01-01

    There has been performed evaluation of the effect of the organophosphorus insecticide (pirimifos-methyl) on some components of the insect immune response. The cellular (a change of the number of hemocytes and of intensity of incapsulation) and the humoral (a change of phenoloxidase activity) components of the immune response were studied in larvae of representatives of two orders--the Colorado potato beetle (Leptinotarsa decemlineata, Chrysomelidae, Coleoptera) and the wax moth (Galeriia mellonella, Pyralidae, Lepidoptera). The action of the insecticide has been found to lead to stimulation of immune reactions (an increase of phenoloxidase activities and of intensity of incapsulation, a rise of the number of hemocytes) at the contact treatment of both sublethal and the half-lethal doses of pirimifos-methyl. PMID:25509049

  2. [An increase in the immune system activity of the wax moth Galleria mellonella and of the Colorado potato beetle Leptinotarsa decemlineata under effect of organophosphorus insecticide].

    PubMed

    Dubovskiy, I M; Yaroslavtseva, O N; Kryukov, V Yu; Benkovskaya, G V; Glupov, V V

    2013-01-01

    There has been performed evaluation of the effect of the organophosphorus insecticide (pirimifos-methyl) on some components of the insect immune response. The cellular (a change of the number of hemocytes and of intensity of incapsulation) and the humoral (a change of phenoloxidase activity) components of the immune response were studied in larvae of representatives of two orders--the Colorado potato beetle (Leptinotarsa decemlineata, Chrysomelidae, Coleoptera) and the wax moth (Galeriia mellonella, Pyralidae, Lepidoptera). The action of the insecticide has been found to lead to stimulation of immune reactions (an increase of phenoloxidase activities and of intensity of incapsulation, a rise of the number of hemocytes) at the contact treatment of both sublethal and the half-lethal doses of pirimifos-methyl. PMID:25490848

  3. [An increase in the immune system activity of the wax moth Galleria mellonella and of the Colorado potato beetle Leptinotarsa decemlineata under effect of organophosphorus insecticide].

    PubMed

    Dubovskiy, I M; Yaroslavtseva, O N; Kryukov, V Yu; Benkovskaya, G V; Glupov, V V

    2013-01-01

    There has been performed evaluation of the effect of the organophosphorus insecticide (pirimifos-methyl) on some components of the insect immune response. The cellular (a change of the number of hemocytes and of intensity of incapsulation) and the humoral (a change of phenoloxidase activity) components of the immune response were studied in larvae of representatives of two orders--the Colorado potato beetle (Leptinotarsa decemlineata, Chrysomelidae, Coleoptera) and the wax moth (Galeriia mellonella, Pyralidae, Lepidoptera). The action of the insecticide has been found to lead to stimulation of immune reactions (an increase of phenoloxidase activities and of intensity of incapsulation, a rise of the number of hemocytes) at the contact treatment of both sublethal and the half-lethal doses of pirimifos-methyl.

  4. Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants.

    PubMed

    Al-Masri, M S; Haddad, Kh; Doubal, A W; Awad, I; Al-Khatib, Y

    2014-06-01

    Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased.

  5. Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants.

    PubMed

    Al-Masri, M S; Haddad, Kh; Doubal, A W; Awad, I; Al-Khatib, Y

    2014-06-01

    Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased. PMID:24602817

  6. Cloning, expression, and characterization of a milk-clotting aspartic protease gene (Po-Asp) from Pleurotus ostreatus.

    PubMed

    Yin, Chaomin; Zheng, Liesheng; Chen, Liguo; Tan, Qi; Shang, Xiaodong; Ma, Aimin

    2014-02-01

    An aspartic protease gene from Pleurotus ostreatus (Po-Asp) had been cloned based on the 3' portion of cDNA in our previous work. The Po-Asp cDNA contained 1,324 nucleotides with an open reading frame (ORF) of 1,212 bp encoding 403 amino acid residues. The putative amino acid sequence included a signal peptide, an activation peptide, two most possible N-glycosylation sites and two conserved catalytic active site. The mature polypeptide with 327 amino acid residues had a calculated molecular mass of 35.3 kDa and a theoretical isoelectric point of 4.57. Basic Local Alignment Search Tool analysis showed 68-80 % amino acid sequence identical to other basidiomycetous aspartic proteases. Sequence comparison and evolutionary analysis revealed that Po-Asp is a member of fungal aspartic protease family. The DNA sequence of Po-Asp is 1,525 bp in length without untranslated region, consisting of seven exons and six introns. The Po-Asp cDNA without signal sequence was expressed in Pichia pastoris and sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the molecular mass of recombinant Po-Asp was about 43 kDa. The crude recombinant aspartic protease had milk-clotting activity.

  7. The Legacy of NASA Astrophysics E/PO: Conducting Professional Development, Developing Key Themes & Resources, and Broadening E/PO Audiences

    NASA Astrophysics Data System (ADS)

    Lawton, Brandon L.; Smith, Denise A.; Meinke, Bonnie K.; Bartolone, Lindsay; Manning, Jim; Schultz, Gregory R.; NASA Astrophysics E/PO Community

    2016-01-01

    For the past six years, NASA's Science Mission Directorate (SMD) has coordinated the work of its mission- and program-embedded education and public outreach (E/PO) efforts through four forums representing its four science divisions. The Astrophysics Forum, as the others, has built on SMD's long-standing principle of partnering scientists and educators and embedding E/PO in its missions to encourage and coordinate collaborative efforts to make the most efficient and effective use of NASA resources, personnel, data and discoveries in leveraged ways, in support of the nation's science education. Three priorities established early in the Forum's period of activity were to collaboratively enhance professional development for formal and informal educators, develop key themes & resources centered on astrophysics topics, and broaden the reach of astrophysics E/PO to traditionally underserved audiences in STEM subjects. This presentation will highlight some of the achievements of the Astrophysics E/PO community and Forum in these priority areas. This work constitutes an ongoing legacy--a firm foundation on which the new structure of NASA SMD education efforts will go forward.

  8. Production and decay spectroscopy of {sup 192}Po and {sup 194}Po

    SciTech Connect

    Andel, B.

    2015-10-15

    A γ-ray spectroscopy study of the (11{sup −}) isomers in {sup 194}Po and {sup 192}Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction {sup 56}Fe + {sup 141}Pr → {sup 197}At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  9. Magnetic relaxation in Zn(PO3)2·Er(PO3)3 glass

    NASA Astrophysics Data System (ADS)

    Orendáč, M.; Tibenská, K.; Čižmár, E.; Tkáč, V.; Orendáčová, A.; Holubová, J.; Černošek, Z.; Černošková, E.

    2016-08-01

    The results of experimental studies of alternating (ac) magnetic susceptibility and specific heat of Zn(PO3)2·Er(PO3)3 glass are reported. Despite a high concentration of magnetic Er(III) ions the analysis of ac susceptibility ruled out the formation of a spin glass state in the used range of temperatures. Two relaxation processes were identified. The first one is thermally activated with a crossover in its temperature dependence observed at nominally 7 K. The relaxation at lower temperatures seems to be governed by a direct process with pronounced effect of phonon bottleneck. Striking deceleration of spin dynamics with increasing temperature found above 7 K is tentatively attributed to overcoming Ioffe - Regel crossover and strong scattering of acoustic phonons on local modes. Simplified prediction derived from a soft-mode-dynamics model confirms the presence of the boson peak observed in specific heat data and reasonably predicts the temperature of the crossover. The second process is consistent with a cross - tunneling relaxation. The obtained results suggest that magnetic doping of glasses and studying magnetic relaxation may represent an alternative tool for the investigation of lattice modes in glasses.

  10. Dosimetry of {sup 210}Po in humans, caribou, and wolves in northern Canada

    SciTech Connect

    Thomas, P.A.

    1994-06-01

    Effective doses from {sup 210}Po intake with caribou meat were determined for human residents in Baker Lake and Snowdrift in the Northwest Territories of Canada and compared to doses calculated from reported {sup 210}Po tissue activities in Alaskan and British residents. Effective doses were calculated to separate body tissues, using ICRP 60 human weighting factors and the ICRP 30 metabolic model for {sup 210}Po. Baker Lake and Alaskan effective doses were similar at 0.4 mSv y{sup {minus}1} and slightly higher than Snowdrift doses (0.3 mSv y{sup {minus}1}). Alaskan tissue activities indicated higher effective doses to liver, bone surfaces and red marrow and lower doses to spleen than the {sup 210}Po metabolic model (ICRP 1979a) predicts. Effective doses to Baker Lake and Snowdrift caribou and wolves, calculated from tissue activities, ranged from 7-20 mSv y{sup {minus}1} using human weighting factors for comparison to human doses only. Effective doses to northern Canadians and wildlife were, respectively, 7-11% and 1.8-5 times an estimated human background of 4 mSv y{sup {minus}} from all sources. 51 refs., 2 figs., 9 tabs.

  11. Radioactivity of cigarettes and the importance of (210)Po and thorium isotopes for radiation dose assessment due to smoking.

    PubMed

    Kubalek, Davor; Serša, Gregor; Štrok, Marko; Benedik, Ljudmila; Jeran, Zvonka

    2016-05-01

    Tobacco and tobacco smoke are very complex mixtures. In addition to various chemical and organic compounds they also contain natural radioactive elements (radionuclides). In this work, the natural radionuclide activity concentrations ((234)U, (238)U, (228)Th, (230)Th, (232)Th, (226)Ra, (210)Pb and (210)Po) of nine different cigarette samples available on the Slovenian market are reported. In addition to (210)Po, the transfer of thorium isotopes from a cigarette to a smoker's body and lungs have been determined for the first time. Cigarette smoke and exhaled air from smokers' lungs were collected from volunteer smokers (C-4 brand) to determinate what quantity of (210)Po and thorium isotopes is transferred from the tobacco to the smoker's lungs. Cigarette ash and smoked filters were also collected and analysed. Among the determined isotopes, (210)Pb and (210)Po showed the highest activity concentrations. During the smoking of one cigarette approximately 22% of (210)Po (and presumably its predecessor (210)Pb), 0.6% of (228)Th, 24% of (230)Th, and 31% of (232)Th are transferred from the cigarette and retained in the smoker's body. The estimated annual effective dose for smokers is 61 μSv/year from (210)Po; 9 μSv/year from (210)Pb; 6 μSv/year from (228)Th; 47 μSv/year from (230)Th, and 37 μSv/year from (232)Th. These results show the importance of thorium isotopes in contributing to the annual effective dose for smoking. PMID:26942842

  12. Photocatalytic Performances of Ag3PO4 Polypods for Degradation of Dye Pollutant under Natural Indoor Weak Light Irradiation.

    PubMed

    Teng, Fei; Liu, Zailun; Zhang, An; Li, Min

    2015-08-18

    It is still a big challenge for Ag3PO4 to be applied in practice mainly because of its low stability resistant to photo corrosion, although it is an efficient photocatalyst. Herein, we have mainly investigated its activity and stability under indoor weak light for the degradation of dye pollutants. It is amazing that under indoor weak light irradiation, rhodamine B (RhB) can be completely degraded by Ag3PO4 polypods after 36 h, but only 18% of RhB by N-doped TiO2 after 120 h. It is found that under indoor weak light irradiation, the degradation rate (0.08099 h(-1)) of RhB over Ag3PO4 polypods are 46 times higher than that (0.00173 h(-1)) of N-doped TiO2. The high activity of Ag3PO4 polypods are mainly attributed to the three-dimensional branched nanostructure and high-energy {110} facets exposed. After three cycles, surprisingly, Ag3PO4 polypods show a high stability under indoor weak light irradiation, whereas Ag3PO4 have been decomposed into Ag under visible light irradiation with an artificial Xe light source. This natural weak light irradiation strategy could be a promising method for the other unstable photocatalysts in the degradation of environmental pollutants.

  13. Radioactivity of cigarettes and the importance of (210)Po and thorium isotopes for radiation dose assessment due to smoking.

    PubMed

    Kubalek, Davor; Serša, Gregor; Štrok, Marko; Benedik, Ljudmila; Jeran, Zvonka

    2016-05-01

    Tobacco and tobacco smoke are very complex mixtures. In addition to various chemical and organic compounds they also contain natural radioactive elements (radionuclides). In this work, the natural radionuclide activity concentrations ((234)U, (238)U, (228)Th, (230)Th, (232)Th, (226)Ra, (210)Pb and (210)Po) of nine different cigarette samples available on the Slovenian market are reported. In addition to (210)Po, the transfer of thorium isotopes from a cigarette to a smoker's body and lungs have been determined for the first time. Cigarette smoke and exhaled air from smokers' lungs were collected from volunteer smokers (C-4 brand) to determinate what quantity of (210)Po and thorium isotopes is transferred from the tobacco to the smoker's lungs. Cigarette ash and smoked filters were also collected and analysed. Among the determined isotopes, (210)Pb and (210)Po showed the highest activity concentrations. During the smoking of one cigarette approximately 22% of (210)Po (and presumably its predecessor (210)Pb), 0.6% of (228)Th, 24% of (230)Th, and 31% of (232)Th are transferred from the cigarette and retained in the smoker's body. The estimated annual effective dose for smokers is 61 μSv/year from (210)Po; 9 μSv/year from (210)Pb; 6 μSv/year from (228)Th; 47 μSv/year from (230)Th, and 37 μSv/year from (232)Th. These results show the importance of thorium isotopes in contributing to the annual effective dose for smoking.

  14. We Need You! The Importance of Scientist Involvement in Education and Public Outreach (E/PO)

    NASA Astrophysics Data System (ADS)

    Buxner, S.; Hsu, B. C.; Meinke, B. K.; Shipp, S. S.; Schwerin, T. G.; Peticolas, L. M.; Smith, D.; Dalton, H.

    2013-12-01

    Active engagement of scientists in education and public outreach (E/PO) activities is beneficial for scientists, classrooms, and the general public. Scientist visibility in the public arena is important to garner public support, whose tax dollars fund scientific programs. Scientists are important disseminators of current, accurate scientific knowledge. They also, perhaps more importantly, understand the nature and process of science and have the means of understanding and addressing many of the issues facing society. Research has shown that while the public is interested in science, not all members are necessarily scientifically literate; additionally there is evidence than many students are not prepared for, or choosing to participate in science careers. And yet, a scientifically engaged, literate, and supportive public is a necessary partner in addressing important global challenges of the future. E/PO is a wonderful opportunity for scientists to demonstrate that science is interesting, exciting, fun, challenging, and relevant to society. In doing so, they can transfer ownership of science to the public through a variety of vehicles by increasing access to scientific thought and discovery. Through partnerships with E/PO professionals, teachers, or journalists, scientists can improve their communication and teaching skills, whether in an E/PO setting or their higher education careers. Sharing with the public what scientists do is an effective way to engage people in the scientific process and to express scientists' enthusiasm for what they do. Scientist involvement in E/PO also shows the public that scientists are real people and provides important role models for the next generation of scientists. There are many opportunities to get involved in E/PO! Find information on EarthSpace, a national clearinghouse for higher education materials in Earth and space science through an abstract by Nicholas Gross, et al. Learn about NASA Science Mission Directorate (SMD

  15. Facile deposition of Ag{sub 3}PO{sub 4} on graphene-like MoS{sub 2} nanosheets for highly efficient photocatalysis

    SciTech Connect

    Wang, Peifu; Shi, Penghui; Hong, Yuanchen; Zhou, Xuejun; Yao, Weifeng

    2015-02-15

    Graphical abstract: The photocatalytic performance of Ag{sub 3}PO{sub 4} was highly improved by the in situ deposition of Ag{sub 3}PO{sub 4} particles on graphene-like MoS{sub 2} nanosheets. - Highlights: • A novel composite photocatalyst was synthesized by depositing Ag{sub 3}PO{sub 4} on the graphene-like MoS{sub 2} nanosheets. • Ag{sub 3}PO{sub 4}/MoS{sub 2} photocatalyst exhibited a high photocatalytic activity for RhB degradation. • Graphene-like MoS{sub 2} nanosheets. • MoS{sub 2} nanosheets play an important role in photocatalytic activity by serving as an effective acceptor of the photogenerated carriers. - Abstract: A facile method for the in situ deposition of Ag{sub 3}PO{sub 4} on graphene-like MoS{sub 2} nanosheets was developed to improve the photocatalytic performance of Ag{sub 3}PO{sub 4} catalysts. The heterostructure of Ag{sub 3}PO{sub 4}/MoS{sub 2} composites was characterized by using X-ray diffraction spectra (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The prepared Ag{sub 3}PO{sub 4}/MoS{sub 2} photocatalyst exhibited a much higher photocatalytic activity than that of Ag{sub 3}PO{sub 4} for the degradation of Rhodamine B (RhB) under visible light irradiation (>400 nm). The improved photocatalytic activity of Ag{sub 3}PO{sub 4}/MoS{sub 2} is attributed to the efficient separation of photogenerated electron–hole pairs in the composite. This result provides a new perspective on the design of high-performance photocatalysts which is promising for energy applications.

  16. In vitro and in silico studies on cell adhesion protein peroxinectin from Fenneropenaeus indicus and screening of heme blockers against activity.

    PubMed

    Sivakamavalli, Jeyachandran; Selvaraj, Chandrabose; Singh, Sanjeev Kumar; Vaseeharan, Baskaralingam

    2016-05-01

    In invertebrates, the prophenoloxidase (proPO) pathway is involved in the phenol-like antioxidant production against invading pathogens. Overproduction of melanin and phenolic substances leads to the disruption of hemocytes (own host cells); therefore, there is a prerequisite to regulate the antioxidant production, which is performed by the proteases and proPO-associated cell adhesion protein peroxinectin (PX). PX is a macromolecular structure consisting of protein involved in the proPO pathway, which is a potential target in the regulatory mechanism in crustaceans. In the proPO cascade, pattern recognition proteins initiate the proPO cascade by the consequent reaction, and PX is involved in the key step in the regulatory mechanism of phenoloxidase enzyme synthesis. In the present study, Indian white shrimp Fenneropenaeus indicus PX (Fein-PX) gene sequence was used. Upregulation of Fein-PX was determined using immunostimulants β-glucan (agonists) and examined its expression by quantitative RT-PCR. To find the downregulation or negative regulation of Fein-PX, inhibitors were screened, and its 3D model provides molecular insights into the rationale inhibitor design for developing an effective molecule against Fein-PX. PMID:26686319

  17. Improved photoelectrochemical performance of Z-scheme g-C3N4/Bi2O3/BiPO4 heterostructure and degradation property

    NASA Astrophysics Data System (ADS)

    Li, Junqi; Yuan, Huan; Zhu, Zhenfeng

    2016-11-01

    In g-C3N4/Bi2O3/BiPO4, the p-n junction between p-type Bi2O3 and n-type BiPO4 was encapsulated by g-C3N4 and a direct Z-scheme was built between g-C3N4 and Bi2O3. The optical, morphological and photoelectrochemical (PEC) properties of BiPO4, g-C3N4/BiPO4, Bi2O3/BiPO4 and g-C3N4/Bi2O3/BiPO4 hierarchical Z-scheme system were studied. More than 90% photodegradation of methyl orange (MO) with the exposure of simulated solar light was achieved within 160 min with the g-C3N4/Bi2O3/BiPO4, which displayed remarkably promoted photocatalytic activities than other samples. The electrochemical impedance spectra and photocurrent results also proved that efficient charge separation and better electron transport properties were achieved by g-C3N4/Bi2O3/BiPO4. In general, the addition of g-C3N4 can guide the residual electrons on p-type Bi2O3 to recombine with photoholes of g-C3N4 and make sure the left carries exhibit stronger oxidation and reduction ability to boost the production of active groups.

  18. Tracing the Depositional Fluxes of Po-210 and Pb-210 As a Tool for Sediment Resuspension Study in a Shallow Water System in Southeast Michigan

    NASA Astrophysics Data System (ADS)

    Baskaran, M. M.; Mudbidre, R.

    2014-12-01

    From the measurements of 210Po and 210Pb in atmospheric dry and bulk depositional flux and in aerosols in southeast Michigan, we observed the following: i) the 210Po/210Pb activity ratio in bulk precipitation was lower than that in aerosols and this was attributed to the possible presence of volatile 210Po in the atmosphere; and ii) it was proposed that only a small fraction of aerosols actively participate in the scavenging of particle-reactive radionuclides based on lack of correlation between the activity of 210Pb and aerosol mass concentration. We extended this study to investigate the particle-cycling in a shallow, dynamic freshwater system in southeast Michigan. The 210Po/210Pb activity ratios in bulk deposition is mostly <0.1 while in benthic sediments, this ratio is usually ~1.0. This activity ratio in finer resuspended sedimentary particulate matter is altered from the scavenging of Po and Pb derived from the atmospheric deposition, and thus, the 210Po/210Pb activity ratio in suspended particulate matter can be utilized as a tracer for particle cycling. We measured the concentrations 210Po and 210Pb in a suite of surficial benthic sediments and particulate matter collected in sediment traps from five different locations in the Clinton River that discharges in to Lake St. Clair in southeast Michigan to quantify the sediment resuspension rates and to determine the particle residence time. The mean 210Po/210Pb activity ratio of suspended trap and surficial bottom sediments were 0.72 and 0.75, respectively, indicating that the sediment trap particles were mostly derived from resuspended bottom sediments. Particle residence time varied from 0.3 to 4 days for 210Pb and 0.9 to 13.4 days for 210Po. Sediment resuspension rate calculated via a single box model approach yielded a mean resuspension rate of 0.5 g cm-2 yr-1 using 210Pb and 0.2 g cm-2 yr-1 using 210Po. A comparison of the 210Po and 210Pb fluxes in the sediment trap to that in the direct atmospheric

  19. Collectivity of {sup 196}Po at low spin

    SciTech Connect

    Grahn, T.; Page, R. D.; Dewald, A.; Jolie, J.; Melon, B.; Pissulla, Th.; Greenlees, P. T.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Peura, P.; Rahkila, P.; Saren, J.; Scholey, C.; Sorri, J.; Uusitalo, J.

    2009-07-15

    Absolute electromagnetic transition probabilities in {sup 196}Po have been measured using the recoil distance Doppler-shift technique. The lifetimes of the three lowest yrast states in {sup 196}Po were extracted from singles {gamma}-ray spectra by using the recoil-decay tagging method. In addition, configuration mixing calculations of angular momentum projected mean-field states have been carried out for {sup 196}Po. The present study sheds light on the onset of collectivity and mixing of competing structures in neutron-deficient Po nuclei.

  20. Differential production of active oxygen species in photo-symbiotic and non-symbiotic bivalves.

    PubMed

    Nakayama, K; Maruyama, T

    1998-01-01

    We investigated the generation of active oxygen species in the bivalves, Crassostrea gigas, Fulvia mutica and Tridacna crocea in order to understand the defensive mechanisms in giant clams that allow a stable association with symbiotic zooxanthellae. C. gigas produced active oxygens, superoxide anion and nitric oxide upon stimulation by phorbol myristate acetate. F. mutica generated a little amount of superoxide anion and nitric oxide, and contained significant phenoloxidase activity which catalyzes formation of quinones. T. crocea did not generate any apparent active oxygen species or quinones. The importance of lacking rapid cytotoxic responses consisting of active oxygen species to foreign organisms in the symbiotic clam is discussed.

  1. The inflow of polonium (210)Po from Vistula river catchments area.

    PubMed

    Skwarzec, Bogdan; Jahnz, Anna

    2007-12-01

    The activities of polonium (210)Po in Vistula unfiltered water samples, collected from November 2002 to November 2003, were measured using the alpha spectrometry. In winter, the highest concentration of (210)Po was in Vistula river water from Torun (2.72 +/- 0.04 Bq x m(-3)) and from the Wieprz river (5.46 +/- 0.07 Bq x m(-3) [Bequerel per cubic metre]), and the lowest was in water from Nida river (0.59 +/- 0.02 Bq x m(-3)). During spring, the highest concentration of (210)Po was observed in Vistula water collected in Deblin (5.98 +/- 0.03 Bq x m(-3)) and the lowest in water from the Narew river (1.20 +/- 0.12 Bq x m(-3)). In summer, the highest concentration of (210)Po was in Nogat river water collected in Malbork (3.18 +/- 0.04 Bq x m(-3)) and the Bzura river (5.30 +/- 0.02 Bq x m(-3)), the lowest in Wieprz river (0.49 +/- 0.09 Bq x m(-3)) and Vistula river water from Kraków (1.44 +/- 0.05 Bq x m(-3)). In autumn, the highest (210)Po concentration was in Bzura river (8.93 +/- 0.03 Bq x m(-3)), the lowest in Vistula water from Grudziadz (1.51 +/- 0.04 Bq x m(-3)), and Toruń (1.89 +/- 0.05 Bq x m(-3)). The highest quantity of (210)Po was transported from Vistula catchments area to the Baltic Sea in spring and the lowest in summer. Annually, the southern Baltic Sea is enriched by about 73.7 GBq (210)Po (with Leniwka and Nogat rivers), with 71.6 GBq going to Gdańsk Bay and 2.1 GBq to Vistula Lagoon. The highest surface (210)Po runoff was observed in spring (to 1370 kBq x km(-2) x quarter(-1) for Dunajec catchment's area), the lowest in summer (for Nida catchment's area to 100 kBq x km(-2) x quarter(-1)).

  2. Polonium (210Po) and lead (210Pb) in marine organisms and their transfer in marine food chains.

    PubMed

    Carvalho, Fernando P

    2011-05-01

    The determination of (210)Po and (210)Pb was performed in marine organisms from the seashore to abyssal depths, encompassing a plethora of species from the microscopic plankton to the sperm whale. Concentrations of those radionuclides ranged from low values of about 5 × 10(-1) Bq kg(-1) (wet wt.) in jellyfish, to very high values of about of 3 × 10(4) Bq kg(-1) (wet wt.) in the gut walls of sardines, with a common pattern of (210)Po > (210)Pb.These radionuclides are primarily absorbed from water and concentrated by phyto- and microzooplankton, and then are transferred to the next trophic level along marine food chains. Investigation in epipelagic, mesopelagic, bathypelagic and abyssobenthic organisms revealed that (210)Po is transferred in the marine food webs with transfer factors ranging from 0.1 to 0.7, and numerically similar to those of the energy transfer in the marine food chains. As (210)Po preferentially binds to amino acids and proteins, its transfer in food chains likely traces protein transfer and, thus, (210)Po transfer factors are similar to ecotrophic coefficients. (210)Pb is transferred less efficiently in marine food chains and this contributes to increased (210)Po:(210)Pb activity ratios in some trophic levels.

  3. Natural radionuclides (210)Po and (210)Pb in the Delaware and Chesapeake Estuaries: modeling scavenging rates and residence times.

    PubMed

    Marsan, D; Rigaud, S; Church, T

    2014-12-01

    During the spring and summer months of 2012, (210)Po and (210)Pb activity were measured in the dissolved and particulate phases from the Delaware and upper Chesapeake estuaries. The upper Delaware estuary, near the freshwater end member, was characterized by high-suspended matter concentrations that scavenged dissolved (210)Po and (210)Pb. Box models were applied using mass balance calculations to assess the nuclides residence times in each estuary. Only 60% of the dissolved (210)Po and 55% of the dissolved (210)Pb from the Delaware estuary were exported to coastal waters. A large fraction of soluble (210)Po and (210)Pb within the estuary was either reversibly adsorbed onto suspended particles, trapped in sediment accumulation zones (such as intertidal marshes), bioaccumulated into phytoplankton and discharged to the coastal ocean. The upper Chesapeake estuary was largely characterized by sub-oxic bottom waters that contained higher concentrations of dissolved (210)Po and (210)Pb, hypothesized to be subjected to redox cycling of manganese. The Delaware and Chesapeake estuary mean residence times for (210)Po differed significantly at 86 ± 7 and 126 ± 10 days respectively, while they were similar for (210)Pb (67 ± 6-55 ± 5 days). The difference in residence times corresponds to the greater extent of biogeochemical scavenging and regeneration processes within the upper Chesapeake. PMID:25239647

  4. Natural radionuclides (210)Po and (210)Pb in the Delaware and Chesapeake Estuaries: modeling scavenging rates and residence times.

    PubMed

    Marsan, D; Rigaud, S; Church, T

    2014-12-01

    During the spring and summer months of 2012, (210)Po and (210)Pb activity were measured in the dissolved and particulate phases from the Delaware and upper Chesapeake estuaries. The upper Delaware estuary, near the freshwater end member, was characterized by high-suspended matter concentrations that scavenged dissolved (210)Po and (210)Pb. Box models were applied using mass balance calculations to assess the nuclides residence times in each estuary. Only 60% of the dissolved (210)Po and 55% of the dissolved (210)Pb from the Delaware estuary were exported to coastal waters. A large fraction of soluble (210)Po and (210)Pb within the estuary was either reversibly adsorbed onto suspended particles, trapped in sediment accumulation zones (such as intertidal marshes), bioaccumulated into phytoplankton and discharged to the coastal ocean. The upper Chesapeake estuary was largely characterized by sub-oxic bottom waters that contained higher concentrations of dissolved (210)Po and (210)Pb, hypothesized to be subjected to redox cycling of manganese. The Delaware and Chesapeake estuary mean residence times for (210)Po differed significantly at 86 ± 7 and 126 ± 10 days respectively, while they were similar for (210)Pb (67 ± 6-55 ± 5 days). The difference in residence times corresponds to the greater extent of biogeochemical scavenging and regeneration processes within the upper Chesapeake.

  5. The influence of reduced graphene oxide on electrical conductivity of LiFePO4-based composite as cathode material

    NASA Astrophysics Data System (ADS)

    Arifin, Muhammad; Aimon, Akfiny Hasdi; Winata, Toto; Abdullah, Mikrajuddin; Iskandar, Ferry

    2016-02-01

    LiFePO4 is fascinating cathode active materials for Li-ion batteries application because of their high electrochemical performance such as a stable voltage at 3.45 V and high specific capacity at 170 mAh.g-1. However, their low intrinsic electronic conductivity and low ionic diffusion are still the hindrance for their further application on Li-ion batteries. Therefore, the efforts to improve their conductivity are very important to elevate their prospecting application as cathode materials. Herein, we reported preparation of additional of reduced Graphene Oxide (rGO) into LiFePO4-based composite via hydrothermal method and the influence of rGO on electrical conductivity of LiFePO4-based composite by varying mass of rGO in composition. Vibration of LiFePO4-based composite was detected on Fourier Transform Infrared Spectroscopy (FTIR) spectra, while single phase of LiFePO4 nanocrystal was observed on X-Ray Diffraction (XRD) pattern, it furthermore, Scanning Electron Microscopy (SEM) images showed that rGO was distributed around LiFePO4-based composite. Finally, the 4-point probe measurement result confirmed that the optimum electrical conductivity is in additional 2 wt% rGO for range 1 to 2 wt% rGO.

  6. Morphology-controlled synthesis of Ag{sub 3}PO{sub 4} nano/microcrystals and their antibacterial properties

    SciTech Connect

    Wu, Aiping; Tian, Chungui; Chang, Wei; Hong, Yu; Zhang, Qi; Qu, Yang; Fu, Honggang

    2013-09-01

    Graphical abstract: The Ag{sub 3}PO{sub 4} with rhombic dodecahedral, spherical and small size particles were controllable fabricated just by changing the types of the solvent. The materials possess good antibacterial properties toward different kinds of bacteria. - Highlights: • The Ag{sub 3}PO{sub 4} with three morphologies were controllable fabricated. • The Ag{sub 3}PO{sub 4} as-prepared possess obvious antibacterial properties in the dark. • The antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation. - Abstract: We reported the controllable fabrication of Ag{sub 3}PO{sub 4} nano/microcrystals through a simple solution-based precipitation reaction. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. The results indicated that the Ag{sub 3}PO{sub 4} crystals with three different morphology, including the rhombic dodecahedron of 500 nm, the sphere of 100 nm and the particles with small-size of 20 nm, could be obtained in the solvents of water, ethylene glycol (EG) and dimethyl sulfoxide (DMSO). The antibacterial assay showed that all samples possess obvious antibacterial properties. In addition, the Ag{sub 3}PO{sub 4} with small size of 20 nm showed better activity due to their high specific surface areas. Notably, we have found that the antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation, which are superior to that in the dark and commercial streptomycin.

  7. Studies of {sup 194,195,197}Po

    SciTech Connect

    Carpenter, M.P.; Ahmad, I.; Crowell, B.

    1995-08-01

    The energy systematics of low-lying polonium states show sudden changes near N = 114. The observed drops in the low-lying levels of {sup 196,198}Po relative to the heavier isotopes indicate significant changes in the underlying structure of these nuclei. It is thought that this change is due to the onset of vibrational collectivity brought about by the quadrupole interaction between neutron and proton-pairs. In order to extend the Po systematics even further, we measured, for the first time, states in {sup 194,195,197}Po using the {sup 28}Si + {sup 170}Yb reaction at a beam energy of 142 MeV. The beam was supplied by ATLAS, and the data were taken with 10 Compton-suppressed Ge detectors placed at the target position of the Fragment Mass Analyzer. Preliminary level schemes were constructed for {sup 194,195,197}Po based on {gamma}-{gamma} and {gamma}-FMA coincidences. The results for {sup 194}Po show that the 2{sup +} - 0{sup +} transition energy decreased in energy by 140 keV relative to {sup 196}Po suggesting that this nucleus moved beyond the vibrational limit to more collective motion. An extrapolation of the systematics predicts that the 2{sup +} energy could drop another 140 keV between {sup 194}Po and {sup 192}Po which would indicate the onset of rotational motion. Currently, we have an approved experiment to investigate the decay of yrast isomers in {sup 194}Po which will allow us to (1) confirm our earlier level scheme of {sup 194}Po, and (2) assess the experimental conditions needed for a future study of {sup 192}Po.

  8. Investigations of the partitioning and residence times of Po-210 and Pb-210 in a riverine system in Southeast Michigan, USA.

    PubMed

    Mudbidre, R; Baskaran, M; Schweitzer, L

    2014-12-01

    Some of the daughter products in the (222)Rn-decay series, such as (210)Po and (210)Pb, have been widely used as tracers and chronometers in aqueous systems. We measured the concentrations of (210)Pb and (210)Po in the dissolved (≤0.5 μm), bulk (unfiltered) and particulate phases (≥1 μm) collected in the Clinton River in the Lake St. Clair watershed in Southeast Michigan in order to investigate their partitioning between particulate and dissolved phases. Activity measurements of the dissolved and particulate phases revealed that an average of 38% (range: 12-59%) and 33% (range: 12-66%) of the total (210)Pb and (210)Po, respectively, in the water column was found in the particulate phase. The activity of dissolved and total (210)Pb was higher than that of (210)Po because of the higher atmospheric depositional fluxes of (210)Pb compared to (210)Po. Although the calculated Kd values of (210)Pb and (210)Po were similar, there was an inverse relationship between the Kd and suspended particulate matter concentration, indicating the presence of a particle concentration effect and we attribute this observation to the presence of significant amounts of colloidal (210)Po and (210)Pb in the dissolved phase. The fractionation factors for Po and Pb were found to be less than 1 in most cases. The first-order box model calculation-based residence times with respect to scavenging varied from 2 to 25 days for (210)Pb and 19-78 days for (210)Po, indicating higher particle-reactivity of (210)Pb compared to (210)Po.

  9. A novel visible light-driven Ag3PO4/SBA-15 nanocomposite: Preparation and application in the photo-degradation of pollutants

    NASA Astrophysics Data System (ADS)

    Chai, Yuanyuan; Wang, Li; Ren, Jia; Dai, Wei-Lin

    2015-01-01

    A novel visible light-driven environmental-benign Ag3PO4/SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag3PO4/SBA-15 nanocomposite increases by 3 times compared with that of the Ag3PO4 particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag3PO4 nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag3PO4 loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag3PO4/SBA-15. Compared to pure Ag3PO4 nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag3PO4/SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and N2-adsorption-desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag3PO4/SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag3PO4 loading on the SBA-15 catalyst will not result in the extra environment and health problems and reduce the cost of wastewater treatment.

  10. Investigations of the partitioning and residence times of Po-210 and Pb-210 in a riverine system in Southeast Michigan, USA.

    PubMed

    Mudbidre, R; Baskaran, M; Schweitzer, L

    2014-12-01

    Some of the daughter products in the (222)Rn-decay series, such as (210)Po and (210)Pb, have been widely used as tracers and chronometers in aqueous systems. We measured the concentrations of (210)Pb and (210)Po in the dissolved (≤0.5 μm), bulk (unfiltered) and particulate phases (≥1 μm) collected in the Clinton River in the Lake St. Clair watershed in Southeast Michigan in order to investigate their partitioning between particulate and dissolved phases. Activity measurements of the dissolved and particulate phases revealed that an average of 38% (range: 12-59%) and 33% (range: 12-66%) of the total (210)Pb and (210)Po, respectively, in the water column was found in the particulate phase. The activity of dissolved and total (210)Pb was higher than that of (210)Po because of the higher atmospheric depositional fluxes of (210)Pb compared to (210)Po. Although the calculated Kd values of (210)Pb and (210)Po were similar, there was an inverse relationship between the Kd and suspended particulate matter concentration, indicating the presence of a particle concentration effect and we attribute this observation to the presence of significant amounts of colloidal (210)Po and (210)Pb in the dissolved phase. The fractionation factors for Po and Pb were found to be less than 1 in most cases. The first-order box model calculation-based residence times with respect to scavenging varied from 2 to 25 days for (210)Pb and 19-78 days for (210)Po, indicating higher particle-reactivity of (210)Pb compared to (210)Po. PMID:24525180

  11. 137Cs and 210Po in Pacific Walrus and Bearded Seal from St. Lawrence Island, Alaska

    SciTech Connect

    Hamilton, T F; Seagars, D J; Jokela, T; Layton, D

    2005-02-02

    The activity concentration of Cesium-137 ({sup 137}Cs) and naturally-occurring Polonium-210 ({sup 210}Po) were measured in the muscle tissue, kidney and liver of Pacific walrus (Odobenus rosmarus divergens) and bearded seal (Erignathus barbatus) collected by native hunters from the Bering Sea. The mean {sup 137}Cs concentrations in muscle, liver and kidney of Pacific walrus were 0.07, 0.09 and 0.07 Bq kg{sup -1} (N= 5, wet weight), respectively, and 0.17, 0.10, and 0.17 Bq kg{sup -1} (N=2, wet weight), respectively, in bearded seal. In general, {sup 137}Cs tissue concentrations are significantly lower than those previously reported for mammals from other regions. By comparison, {sup 210}Po activity concentrations appear to be higher than those reported elsewhere but a larger variation. The mean {sup 210}Po concentration in the muscle tissue, liver and kidney of Pacific walrus (N=5, wet weight) were 28.7, 189, and 174 Bq kg{sup -1}, respectively. This compares with {sup 210}Po concentration values (N=2, wet weight) of 27, 207, and 68 Bq kg{sup -1} measured in the muscle tissue, liver and kidney, of bearded seal, respectively. Estimated bioaccumulation factors--as defined by the radionuclide concentration ratio between the target tissue to that in sea water--were two to three orders of magnitude higher for {sup 210}Po that those of {sup 137}Cs. We conclude from radiological dose estimates that ingestion of {sup 137}Cs in foods derived from walrus and seal will pose no threat to human health. This work has important implications for assessing health risks to Alaskan coastal communities concerned about the dumping of nuclear waste in the Russia Arctic.

  12. 137Cs and 210Po in Pacific walrus and bearded seal from St. Lawrence Island, Alaska.

    PubMed

    Hamilton, Terry; Seagars, Dana; Jokela, Terry; Layton, David

    2008-06-01

    The activity concentration of Cesium-137 ((137)Cs) and naturally-occurring Polonium-210 ((210)Po) were measured in the muscle tissue, kidney and liver of Pacific walrus (Odobenus rosmarus divergens) and bearded seal (Erignathus barbatus) collected by native hunters from the Bering Sea during May 1996. The mean (137)Cs concentrations in muscle, liver and kidney of Pacific walrus were 0.07, 0.09 and 0.07 Bq kg(-1) (n=5, wet weight), respectively, and 0.17, 0.10, and 0.17 Bq kg(-1) (n=2, wet weight), respectively, in bearded seal. In general, (137)Cs tissue concentrations are significantly lower than those previously reported for mammals from other regions. By comparison, (210)Po activity concentrations are more variable and appear to be higher level compared with mammal data from other regions. The mean (210)Po concentration in the muscle tissue, liver and kidney of Pacific walrus (n=5, wet weight) were 28.7, 189, and 174 Bq kg(-1), respectively. This compares with (210)Po concentration values (n=2, wet weight) of 27, 207 and 68 Bq kg(-1) measured in the muscle tissue, liver and kidney, of bearded seal, respectively. Estimated concentration factors--as defined by the radionuclide concentration ratio between the target tissue to that in sea water--were two to three orders of magnitude higher for (210)Po that those of (137)Cs. We conclude from radiological dose estimates that ingestion of (137)Cs in foods derived from walrus and seal will pose no threat to human health. This work has important implications for assessment of risks of Alaskan coastal communities concerned about the dumping of nuclear waste in the Russia Arctic.

  13. CdZnTe Background Measurements at Balloon Altitudes with PoRTIA

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Barthelmy, S.; Bartlett, L.; Gehrels, N.; Naya, J.; Stahle, C. M.; Tueller, J.; Teegarden, B.

    2003-01-01

    Measurements of the CdZnTe internal background at balloon altitudes are essential to determine which physical processes make the most important background contributions. We present results from CdZnTe background measurements made by PoRTIA, a small CdZnTe balloon instrument that was flown three times in three different shielding configurations. PoRTIA was passively shielded during its first flight from Palestine, Texas and actively shielded as a piggyback instrument on the GRIS balloon experiment during its second and third flights from Alice Springs, Australia, using the thick GRIS Nal anticoincidence shield. A significant CdZnTe background reduction was achieved during the third flight with PoRTIA placed completely inside the GRIS shield and blocking crystal, and thus completely surrounded by 15 cm of Nal. A unique balloon altitude background data set is provided by CdZnTe and Ge detectors simultaneously surrounded by the same thick anticoincidence shield; the presence of a single coxial Ge detector inside the shield next to PoRTIA allowed a measurement of the ambient neutron flux inside the shield throughout the flight. These neutrons interact with the detector material to produce isomeric states of the Cd, Zn and Te nuclei that radiatively decay; calculations are presented that indicate that these decays may explain most of the fully shielded CdZnTe background.

  14. Hydrothermal preparation of LiFePO 4 nanocrystals mediated by organic acid

    NASA Astrophysics Data System (ADS)

    Ni, Jiangfeng; Morishita, Masanori; Kawabe, Yoshiteru; Watada, Masaharu; Takeichi, Nobuhiko; Sakai, Tetsuo

    Well-crystallized LiFePO 4 nanoparticles have been directly synthesized in a short time via hydrothermal process in the presence of organic acid, e.g. citric acid or ascorbic acid. These acid-mediated LiFePO 4 products exhibit a phase-pure and nanocrystal nature with size about 50-100 nm. Two critical roles that the organic acid mediator plays in hydrothermal process are recognized and a rational mechanism is explored. After a post carbon-coating treatment at 600 °C for 1 h, these mediated LiFePO 4 materials show a high electrochemical activity in terms of reversible capacity, cycling stability and rate capability. Particularly, LiFePO 4 mediated by ascorbic acid can deliver a capacity of 162 mAh g -1 at 0.1 C, 154 mAh g -1 at 1 C, and 122 mAh g -1 at 5 C. The crystalline structure, particle morphology, and surface microstructure were characterized by high-energy synchrotron X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and Raman spectroscopy, respectively. And the electrochemical properties were thoroughly investigated by galvanostatic test and electrochemical impedance spectroscopy (EIS).

  15. Improving thermal stability of KSrPO4:Tb3+ phosphors prepared by microwave assisted sintering

    NASA Astrophysics Data System (ADS)

    Peng, Yu-Ming; Su, Yan-Kuin; Yang, Ru-Yuan

    2013-10-01

    In this paper, KSr0.94PO4:Tb0.063+ phosphor was synthesized successfully by microwave assisted sintering method at 1200 °C for 1 h under an air atmosphere. Photoluminescence results show KSr0.94PO4:Tb0.063+ phosphor prepared by microwave assisted sintering method presents an observable improved effect on the enhancement of thermal stability. The emission intensity reduces slowly and marginally by approximately 7% for the maximum emission peak with the temperature increasing from 30 °C to 200 °C indicating great thermal stability KSrPO4:Tb3+ phosphors are. Additionally, the activation energy (ΔE) of thermal quenching of KSrPO4:Tb3+ phosphor was calculated to be 0.2 eV. Moreover, the chromaticity (x, y) located at (0.30, 0.52) was kept without variation when the temperature increased from 30 °C to 200 °C.

  16. Ra-228, Ra-226, Pb-210 and Po-210 variations in the water columns and the surface water plankton in the Luzon Strait and northern South China Sea

    NASA Astrophysics Data System (ADS)

    Chung, Y.; Lin, C.; Wang, P.; Su, Y.

    2006-12-01

    Profiles of Ra-228, Ra-226, Pb-210 and Po-210 were measured in the Luzon Strait (LS) and northern South China Sea (SCS) areas to delineate the exchanges between the western Philippine Sea (WPS) and the northern SCS waters across the LS. Plankton samples were also collected for Po-210 and Pb-210 measurements to assess the balance between the Po-210 excess over Pb-210 in the plankton and the deficit in the surface water. Profiles of Ra-228 and Ra-226 seem to indicate the out flow of the SCS water below the salinity minimum and above around 1500m depth, below which the WPS water flows into the SCS through the LS above a sill depth of about 2600m. This is consistent with previous studies conducted in the area. All the Pb-210 profiles show a strong subsurface maximum with higher activity in the LS area. This maximum is in large excess over its parent, Ra-226 due to atmospheric input. Po-210 profiles generally follow the associated Pb-210 profiles but with lower activities, showing Po-210 deficiency. Po-210 is strongly enriched over Pb-210 in the plankton samples with an activity ratio generally over 10 and up to 40. Both nuclides in the plankton are higher in the LS area, a trend similar to the surface water. The Po-210 excess in the plankton can account for at least 70 percent of the surface water deficit, part of which may be removed by sinking particles.

  17. Comparison of S, Se, and 210Po accumulation patterns in common squid Todarodes pacificus from the Yellow Sea and East/Japan Sea

    NASA Astrophysics Data System (ADS)

    Waska, Hannelore; Kim, Guebuem; Kim, Gi Beum

    2013-06-01

    Activities of 210Po and concentrations of the chalcogen elements S and Se, were measured in muscle, stomach, gill, and hepatopancreas tissues of two groups of the common squid, Todarodes pacificus, from common spawning grounds but different feeding grounds: The Yellow Sea and the East/Japan Sea. All elements displayed lowest concentrations in the muscle tissues, but while S was highest in stomach and gills tissues, Se and 210Po were highest in hepatopancreas tissues, probably due to compartmentalization based on their toxicity. Whole body burden calculations based on organ weight contributions confirmed that the majority of the squids total S is contributed by the muscle while the majority of 210Po is contributed by the hepatopancreas. Overall, squids from the East/Japan Sea displayed significantly higher 210Po activities than those from the Yellow Sea, in line with previous reports on higher activities of dissolved 210Po in the water column of the former compared to the latter, which likely affects bioaccumulation by the foodweb. Tissue-based correlation patterns of the three chalcogens with each other and with the toxic heavy metal Cd suggest S- and Se-containing detoxifying mechanisms for 210Po and Cd in stomach and gills, but not in the hepatopancreas, which supports previous hypotheses that both 210Po and Cd could be bound to S- and Se-depleted compounds in the squid hepatopancreas.

  18. 210Po and 210Pb trophic transfer within the phytoplankton-zooplankton-anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea).

    PubMed

    Strady, Emilie; Harmelin-Vivien, Mireille; Chiffoleau, Jean François; Veron, Alain; Tronczynski, Jacek; Radakovitch, Olivier

    2015-05-01

    The transfer of (210)Po and (210)Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of (210)Po and (210)Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes.

  19. 210Po, 210Pb, 40K and 137Cs in edible wild berries and mushrooms and ingestion doses to man from high consumption rates of these wild foods.

    PubMed

    Gwynn, Justin P; Nalbandyan, Anna; Rudolfsen, Geir

    2013-02-01

    This paper discusses activity concentrations of (210)Po, (210)Pb, (40)K and (137)Cs in edible wild berries and mushrooms collected from Øvre Dividalen national park, Northern Norway and derives committed effective ingestion doses to man based on high consumption rates of these wild foods. Edible wild berries and mushrooms accumulated similar levels of (210)Pb, but mushrooms accumulated higher levels of (210)Po and (40)K than berries. There appears to be a clear difference in the ability of Leccinum spp. of fungi to accumulate (210)Po and/or translocate (210)Po to mushrooms compared to Russula spp. of fungi. Activity concentrations of (137)Cs in edible wild berries and mushrooms from Øvre Dividalen national park reflected the lower levels of fallout of this radionuclide in Northern Norway compared to more central areas following the Chernobyl accident. For mushrooms, ingestion doses are dominated by (210)Po, while for berries, (40)K is typically the main contributor to dose. Based on high consumption rates, ingestion doses arising from the combination of (210)Po, (210)Pb and (40)K were up to 0.05 mSv/a for berries and 0.50 mSv/a for mushrooms. Consumption of such wild foods may result in a significant contribution to total annual doses when consumed in large quantities, particularly when selecting mushrooms species that accumulate high activity concentrations of (210)Po.

  20. 210Po and 210Pb trophic transfer within the phytoplankton-zooplankton-anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea).

    PubMed

    Strady, Emilie; Harmelin-Vivien, Mireille; Chiffoleau, Jean François; Veron, Alain; Tronczynski, Jacek; Radakovitch, Olivier

    2015-05-01

    The transfer of (210)Po and (210)Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of (210)Po and (210)Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes. PMID:25771222

  1. A novel p-LaFeO3/n-Ag3PO4 heterojunction photocatalyst for phenol degradation under visible light irradiation.

    PubMed

    Yang, Jun; Hu, Ruisheng; Meng, Wanwan; Du, Yanfei

    2016-02-11

    A novel heterojunction photocatalyst p-LaFeO3/n-Ag3PO4 has been prepared via a facile in situ precipitation method. It exhibits higher activity than individual Ag3PO4 and LaFeO3 in the degradation of phenol. The excellent activity is mainly attributed to its more effective separation of electron-hole pairs. PMID:26753187

  2. Transport properties of LiCoPO4 and Fe-substituted LiCoPO4

    NASA Astrophysics Data System (ADS)

    Allen, Jan L.; Thompson, Travis; Sakamoto, Jeff; Becker, Collin R.; Jow, T. Richard; Wolfenstine, Jeff

    2014-05-01

    LiCoPO4 is a promising cathode material to enable high energy, abuse tolerant Li-ion batteries. However, LiCoPO4 has relatively poor electronic conductivity which may be improved by chemical substitution. In this work, the ionic and electronic conductivities of dense, polycrystalline LiCoPO4 and Fe2+/Fe3+-substituted LiCoPO4 (Li1-xCo0.9Fe0.1PO4) are measured and compared. Both materials are predominantly ionic conductors with relatively good bulk ionic and relatively poor electronic conductivities. Li1-xCo0.9Fe0.1PO4 exhibits both higher bulk ionic and electronic conductivity. The increased bulk ionic conductivity of Li1-xCo0.9Fe0.1PO4 is believed to originate mainly from extra Li vacancies and the increased electronic conductivity is believed to originate mainly from creating more mobile hole polarons compared to LiCoPO4 as a result of Fe2+/Fe3+ substitution.

  3. Oxidase-like mimic of Ag@Ag3PO4 microcubes as a smart probe for ultrasensitive and selective Hg(2+) detection.

    PubMed

    Chai, Dong-Feng; Ma, Zhuo; Qiu, Yunfeng; Lv, Yu-Guang; Liu, Hong; Song, Chao-Yu; Gao, Guang-Gang

    2016-02-21

    An oxidase-like mimic system based on facilely synthesized Ag@Ag3PO4 microcubes (Ag@Ag3PO4MCs) was designed and utilized to detect mercury ions with high selectivity and ultrasensitivity. Ag@Ag3PO4MCs with an average size of ca. 1.6 μm were synthesized by the reaction of [Ag(NH3)2](+) complex and Na2HPO4 and subsequent photoreduction under ultraviolet light. The as-prepared Ag@Ag3PO4MCs can effectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) in the presence of dissolved oxygen in slightly acidic solution, exhibiting oxidase-like activities rather than peroxidase-like activity. Interestingly, the introduction of Ag nanoparticles (AgNPs) on the surfaces of Ag3PO4MCs can dramatically enhance the oxidase-like activities due to a synergistic effect between AgNPs and Ag3PO4MCs, as evidenced by the faster oxidation speed of TMB and OPD than that of native Ag3PO4MCs in the presence of dissolved oxygen. The enzyme kinetics can be well-explained by the Michaelis-Menten equation. As "poisoning" inhibitor, Hg(2+) ions can inhibit the enzyme reaction catalyzed by Ag3PO4MCs or Ag@Ag3PO4MCs. On the basis of this effect, a colorimetric Hg(2+) sensor was developed by the enzyme inhibition reaction of Ag3PO4MCs or Ag@Ag3PO4MCs. The excellent specific interaction of Hg-Ag or Hg(2+)-Ag(+) provides high selectivity for Hg(2+) over interfering metal ions. Meanwhile, the sensitivity of this sensor to Hg(2+) is extremely excellent with a limit of detection as low as 0.253 nM for Ag@Ag3PO4MCs. Considering the advantages of low detection limit, low cost, facile preparation, and visualization, the colorimetric Ag@Ag3PO4MCs sensor shows high promise for the testing of Hg(2+) in water samples. PMID:26763181

  4. Synthesis, crystal structure, and ionic conductivity of a new layered metal phosphate, Li2Sr2Al(PO4)3

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Chul; Kwak, Hyun-Jung; Yoo, Chung-Yul; Yun, Hoseop; Kim, Seung-Joo

    2016-11-01

    A new layered metal phosphate, Li2Sr2Al(PO4)3, was synthesized in the form of either a single-crystal or polycrystalline powder using the molten hydroxide flux method or a solid-state reaction, respectively. Li2Sr2Al(PO4)3 crystallizes to the P21/n (Z=4) monoclinic space group with lattice parameters a≈4.95 Å, b≈22.06 Å, c≈8.63 Å, and β≈91.5°. The structure is composed of stacked [LiSrAl(PO4)2] layers alternating regularly with [LiSrPO4] layers. In the [LiSrAl(PO4)2] sublattice, the AlO6 octahedra and PO4 tetrahedra are tilted cooperatively to form an anionic, corrugated, two-dimensional [Al(PO4)2]3- framework that can be regarded as a "distorted-glaserite" structure. The [LiSrPO4] sublattice is that of a layered block containing a six-membered ring formed from alternating linkages of LiO4 and PO4 tetrahedra. The six-membered rings show a boat-type arrangement with the up(U) or down(D) pointing sequence, UUDUUD. The interspace between the two sublattices generates a two-dimensional pathway for Li+ ion conduction. The impedance measurement indicated that Li2Sr2Al(PO4)3 had a moderate ion conductivity (σ≈1.30×10-4 S cm-1 at 667 K), with an activation energy Ea≈1.02 eV.

  5. Estimation of past radon exposure to indoor radon from embedded (210)Po in household glass.

    PubMed

    Gusain, G S; Rautela, B S; Ramola, R C

    2012-11-01

    In the present investigation, the surface-deposited polonium activities were measured in houses in the Ukhimath region of Garhwal Himalaya, India. The surface-deposited (210)Po activity concentrations were found to vary from 0.7 to 15.40 Bq m(-2) with an average of 5.95 Bq m(-2). The radon concentration estimated on the basis of (210)Po activity was found to vary from 0.29 to 700 Bq m(-3) with an average value 242 Bq m(-3). The contemporary radon concentration in the area was found to vary from 13 to 181 Bq m(-3) with an average of 46 Bq m(-3). The annual effective dose due to (210)Po activity in houses in the Garhwal Himalaya region was found to vary from 0.61 to 13.33 mSv with an average of 5.15 mSv. Some worldwide studies have shown the relation between the increased risk of lung cancer and smoking habits. Data on smoking have also been collected from the same dwellings. The significance of this work is also discussed in detail from a radiation protection point of view.

  6. Nanocomposite of exfoliated bentonite/g-C3N4/Ag3PO4 for enhanced visible-light photocatalytic decomposition of Rhodamine B.

    PubMed

    Ma, Jianfeng; Huang, Daiqin; Zhang, Wenyi; Zou, Jing; Kong, Yong; Zhu, Jianxi; Komarneni, Sridhar

    2016-11-01

    Novel visible-light-driven heterojunction photocatalyst comprising exfoliated bentonite, g-C3N4 and Ag3PO4 (EB/g-C3N4/Ag3PO4) was synthesized by a facile and green method. The composites EB/g-C3N4/Ag3PO4 were characterized by X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy and the Brunauer, Emmett, and Teller (BET) surface area method. Under visible light irradiation, EB/g-C3N4/Ag3PO4 composites displayed much higher photocatalytic activity than that of either pure g-C3N4 or pure Ag3PO4 in the degradation of Rhodamine B (RhB). Among the hybrid photocatalysts, EB/g-C3N4/Ag3PO4 composite containing 20 wt% Ag3PO4 exhibited the highest photocatalytic activity for the decolorization of RhB. Under the visible-light irradiation, the RhB dye was completely decolorized in less than 60 min. The enhanced photocatalytic performance is attributed to the stable structure, enlarged surface area, strong adsorbability, strong light absorption ability, and high-efficiency separation rate of photoinduced electron-hole pairs. Our finding paves a way to design highly efficient and stable visible-light-induced photocatalysts for practical applications in wastewater treatment. PMID:27505138

  7. Nanocomposite of exfoliated bentonite/g-C3N4/Ag3PO4 for enhanced visible-light photocatalytic decomposition of Rhodamine B.

    PubMed

    Ma, Jianfeng; Huang, Daiqin; Zhang, Wenyi; Zou, Jing; Kong, Yong; Zhu, Jianxi; Komarneni, Sridhar

    2016-11-01

    Novel visible-light-driven heterojunction photocatalyst comprising exfoliated bentonite, g-C3N4 and Ag3PO4 (EB/g-C3N4/Ag3PO4) was synthesized by a facile and green method. The composites EB/g-C3N4/Ag3PO4 were characterized by X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy and the Brunauer, Emmett, and Teller (BET) surface area method. Under visible light irradiation, EB/g-C3N4/Ag3PO4 composites displayed much higher photocatalytic activity than that of either pure g-C3N4 or pure Ag3PO4 in the degradation of Rhodamine B (RhB). Among the hybrid photocatalysts, EB/g-C3N4/Ag3PO4 composite containing 20 wt% Ag3PO4 exhibited the highest photocatalytic activity for the decolorization of RhB. Under the visible-light irradiation, the RhB dye was completely decolorized in less than 60 min. The enhanced photocatalytic performance is attributed to the stable structure, enlarged surface area, strong adsorbability, strong light absorption ability, and high-efficiency separation rate of photoinduced electron-hole pairs. Our finding paves a way to design highly efficient and stable visible-light-induced photocatalysts for practical applications in wastewater treatment.

  8. Determination of 210Po in various foodstuffs and its annual effective dose to inhabitants of Qena City, Egypt.

    PubMed

    Din, K Salahel

    2011-11-15

    The concentration of 210Po was determined in different foodstuffs of plant origin purchased from markets in Qena City, Upper Egypt. Measurement of 210Po has been carried out using alpha spectrometry technique in different food categories such as vegetables, fruits, cereals beverages and herbs. The general range of 210Po activity levels ranged widely from <0.010-18.6±0.910 mBq g(-1), with minimum being in cereal samples and maximum being in beverage samples. Tea samples recorded highest activity concentrations of 210Po with lowest value of 10±0.54 mBq g(-1) for Crown tea and highest value of 18.6±0.910 mBq g(-1) for El maabad tea. The daily intake of 210Po from food consumption reveals that vegetables are the biggest contributors, while beverages are the lowest. The effective ingestion dose has been estimated for Qena City residents and it was found in the range 0.008-38.3 μSv y(-1).

  9. Na(7)Mg(13)Nd(PO(4))(12).

    PubMed

    Jerbi, Hasna; Hidouri, Mourad; Mongi, Ben Amara

    2012-06-01

    Investigations of the quasi-ternary system Na(3)PO(4)-Mg(3)(PO(4))(2)-NdPO(4) allowed us to obtain the new phosphate hepta-sodium trideca-magnesium neodymium dodeca-kis-phosphate, Na(7)Mg(13)Nd(PO(4))(12), by applying a flux method. The crystal structure is isotypic with that of the previously reported Na(7)Mg(13)Ln(PO(4))(12) (Ln = Eu, La) compounds. It consists of a complex three-dimensional framework built up from an NdO(8) polyhedron (m symmetry), an MO(6) octa-hedron statistically occupied by M = Mg and Na, and eight MgO(x) (x = 5, 6) polyhedra (four with site symmetry m), linked either directely by sharing corners, edges and faces, or by one of the eight unique PO(4) tetra-hedra through common corners. Two of the PO(4) tetra-hedra are statisticaly disordered over a mirror plane. The whole structure can be described as resutling from an assembly of two types of structural units, viz [Mg(4)MP(4)O(22)](∞) (2) layers extending parallel to (100) and stacked along [100], and [Mg(4)NdP(4)O(36)](∞) (1) undulating chains running along the [010] direction. The six different Na(+) cations (five with site symmetry m and one with 0.5 occupancy) are situated in six distinct cavities delimited by the framework. The structure was refined from data of a racemic twin.

  10. (210)Po poisoning as possible cause of death: forensic investigations and toxicological analysis of the remains of Yasser Arafat.

    PubMed

    Froidevaux, Pascal; Bochud, François; Baechler, Sébastien; Castella, Vincent; Augsburger, Marc; Bailat, Claude; Michaud, Katarzyna; Straub, Marietta; Pecchia, Marco; Jenk, Theo M; Uldin, Tanya; Mangin, Patrice

    2016-02-01

    The late president of the Palestinian Authority, Yasser Arafat, died in November 2004 in Percy Hospital, one month after having experienced a sudden onset of symptoms that included severe nausea, vomiting, diarrhoea and abdominal pain and which were followed by multiple organ failure. In spite of numerous investigations performed in France, the pathophysiological mechanisms at the origin of the symptoms could not be identified. In 2011, we found abnormal levels of polonium-210 ((210)Po) in some of Arafat's belongings that were worn during his final hospital stay and which were stained with biological fluids. This finding led to the exhumation of Arafat's remains in 2012. Significantly higher (up to 20 times) activities of (210)Po and lead-210 ((210)Pb) were found in the ribs, iliac crest and sternum specimens compared to reference samples from the literature (p-value <1%). In all specimens from the tomb, (210)Po activity was supported by a similar activity of (210)Pb. Biokinetic calculations demonstrated that a (210)Pb impurity, as identified in a commercial source of 3MBq of (210)Po, may be responsible for the activities measured in Arafat's belongings and remains 8 years after his death. The absence of myelosuppression and hair loss in Mr Arafat's case compared to Mr Litvinenko's, the only known case of malicious poisoning with (210)Po, could be explained by differences in the time delivery-scheme of intake. In conclusion, statistical Bayesian analysis combining all the evidence gathered in our forensic expert report moderately supports the proposition that Mr Arafat was poisoned by (210)Po. PMID:26707208

  11. (210)Po poisoning as possible cause of death: forensic investigations and toxicological analysis of the remains of Yasser Arafat.

    PubMed

    Froidevaux, Pascal; Bochud, François; Baechler, Sébastien; Castella, Vincent; Augsburger, Marc; Bailat, Claude; Michaud, Katarzyna; Straub, Marietta; Pecchia, Marco; Jenk, Theo M; Uldin, Tanya; Mangin, Patrice

    2016-02-01

    The late president of the Palestinian Authority, Yasser Arafat, died in November 2004 in Percy Hospital, one month after having experienced a sudden onset of symptoms that included severe nausea, vomiting, diarrhoea and abdominal pain and which were followed by multiple organ failure. In spite of numerous investigations performed in France, the pathophysiological mechanisms at the origin of the symptoms could not be identified. In 2011, we found abnormal levels of polonium-210 ((210)Po) in some of Arafat's belongings that were worn during his final hospital stay and which were stained with biological fluids. This finding led to the exhumation of Arafat's remains in 2012. Significantly higher (up to 20 times) activities of (210)Po and lead-210 ((210)Pb) were found in the ribs, iliac crest and sternum specimens compared to reference samples from the literature (p-value <1%). In all specimens from the tomb, (210)Po activity was supported by a similar activity of (210)Pb. Biokinetic calculations demonstrated that a (210)Pb impurity, as identified in a commercial source of 3MBq of (210)Po, may be responsible for the activities measured in Arafat's belongings and remains 8 years after his death. The absence of myelosuppression and hair loss in Mr Arafat's case compared to Mr Litvinenko's, the only known case of malicious poisoning with (210)Po, could be explained by differences in the time delivery-scheme of intake. In conclusion, statistical Bayesian analysis combining all the evidence gathered in our forensic expert report moderately supports the proposition that Mr Arafat was poisoned by (210)Po.

  12. (7)Be, (210)Pb, and (210)Po in the surface air from the Arctic to Antarctica.

    PubMed

    Persson, Bertil R R; Holm, Elis

    2014-12-01

    In the present study we have investigated the activity concentrations of (210)Pb, (210)Po as well as (7)Be in surface air of the North and South Atlantic (1988-1989), the Arctic Ocean (1991), and along the coastline of Siberia (1994) during succeeding expeditions in the Swedish Polar Research program. During the cruises in the Arctic Ocean during 1991-07-28 to 1991-10-04 the average air concentrations of (7)Be was 0.6 ± 0.4 mBq/m(3), (210)Pb 40 ± 4 μBq/m(3) and (210)Po-38 ± 10 μBq/m(3). During the Swedish-Russian Tundra Ecology-94 expedition along the Siberian coastline the average air concentrations of (7)Be and (210)Pb measured during May-July were 11 ± 3, and 2.4 ± 0.4 mBq/m(3), and during July-September they were 7.2 ± 2 and 2.7 ± 1.1 mBq/m(3) respectively. The results from measurements of the activity concentration of (210)Pb in the air over the Arctic Ocean vary between 75 and 176 μBq/m(3). In the air close to land masses, however, the activity concentration of (210)Pb in the air increases to 269-2712 μBq/m(3). The activity concentration of (7)Be in the South Atlantic during the cruise down to Antarctica varied between 1.3 and 1.7 with an average of 1.5 ± 0.8 mBq/m(3). The activity concentration of (210)Pb in the South Atlantic down to Antarctica varied between 6 and 14 μBq/m(3). At the Equator the activity concentration recorded in November 1988 was 630 μBq/m(3) and in April 1989 it was 260 μBq/m(3). The average activity concentration of (210)Pb during the route Gothenburg-Montevideo in 1988 was 290 and on the return Montevideo-Gothenburg it was 230 μBq/m(3). The activity concentration of (210)Po in the South Atlantic down to Antarctica varied between 15 and 58 μBq/m(3). At the Equator the activity concentration in November 1988 was 170 and in April 1989 it was 70 μBq/m(3). The average activity concentration of (210)Po during the route Gothenburg-Montevideo in 1988 was 63 and on the return Montevideo

  13. (7)Be, (210)Pb, and (210)Po in the surface air from the Arctic to Antarctica.

    PubMed

    Persson, Bertil R R; Holm, Elis

    2014-12-01

    In the present study we have investigated the activity concentrations of (210)Pb, (210)Po as well as (7)Be in surface air of the North and South Atlantic (1988-1989), the Arctic Ocean (1991), and along the coastline of Siberia (1994) during succeeding expeditions in the Swedish Polar Research program. During the cruises in the Arctic Ocean during 1991-07-28 to 1991-10-04 the average air concentrations of (7)Be was 0.6 ± 0.4 mBq/m(3), (210)Pb 40 ± 4 μBq/m(3) and (210)Po-38 ± 10 μBq/m(3). During the Swedish-Russian Tundra Ecology-94 expedition along the Siberian coastline the average air concentrations of (7)Be and (210)Pb measured during May-July were 11 ± 3, and 2.4 ± 0.4 mBq/m(3), and during July-September they were 7.2 ± 2 and 2.7 ± 1.1 mBq/m(3) respectively. The results from measurements of the activity concentration of (210)Pb in the air over the Arctic Ocean vary between 75 and 176 μBq/m(3). In the air close to land masses, however, the activity concentration of (210)Pb in the air increases to 269-2712 μBq/m(3). The activity concentration of (7)Be in the South Atlantic during the cruise down to Antarctica varied between 1.3 and 1.7 with an average of 1.5 ± 0.8 mBq/m(3). The activity concentration of (210)Pb in the South Atlantic down to Antarctica varied between 6 and 14 μBq/m(3). At the Equator the activity concentration recorded in November 1988 was 630 μBq/m(3) and in April 1989 it was 260 μBq/m(3). The average activity concentration of (210)Pb during the route Gothenburg-Montevideo in 1988 was 290 and on the return Montevideo-Gothenburg it was 230 μBq/m(3). The activity concentration of (210)Po in the South Atlantic down to Antarctica varied between 15 and 58 μBq/m(3). At the Equator the activity concentration in November 1988 was 170 and in April 1989 it was 70 μBq/m(3). The average activity concentration of (210)Po during the route Gothenburg-Montevideo in 1988 was 63 and on the return Montevideo

  14. Extracellular enzymatic activities of Bipolaris sorokiniana isolates.

    PubMed

    Geimba, Mercedes P; Brandelli, Adriano

    2002-01-01

    Several enzymatic activities were investigated in six isolates of the fungus Bipolaris sorokiniana, originating from different areas of Brazil. Among the glycosidases studied, beta-glucosidase, beta-N-acetylglucosaminidase, beta-xylosidase, cellobiohydrolase, and chitobiohydrolase were the major activities. In some isolates, beta-glucuronidase, beta-galactosidase, and alpha-mannosidase activities were also present. Polysaccharide-hydrolyzing enzymes, such as pectin lyase and carboxymethyl cellulase were detected in significant amounts, and their activities were variable among the different isolates. Other enzymes, namely phosphatases, proteinases and phenol oxidase, were also examined, showing variable amounts depending on the isolate. The pH dependence of all enzymes tested was investigated. Endoproteinase, carboxymethyl cellulase, and phenoloxidase had maximum activity in the pH range of 6-8, whilst all other enzymes showed maximum activity at pH 4-6.

  15. Nurturing The STEM Pipeline: Graduate Student Leadership In NIRCam's Ongoing E/PO Mission For JWST

    NASA Astrophysics Data System (ADS)

    Schlingman, Wayne M.; Stock, N.; Teske, J.; Tyler, K.; Biller, B.; Donley, J.; Hedden, A.; Knierman, K.; Young, P.

    2011-01-01

    The Astronomy Camp for Girl Scout Leaders is an education and public outreach (E/PO) program offered by the science team of the Near-InfraRed Camera (NIRCam) for NASA's 6.5-meter James Webb Space Telescope (JWST). Since 2003, astronomy graduate students have helped design and lead biannual "Train the Trainer” workshops for adults from the Girl Scouts of the USA (GSUSA), engaging these trainers in the process of scientific inquiry and equipping them to host astronomy-related activities at the troop level. These workshops have helped revise the national GSUSA badge curriculum and directly benefitted thousands of young girls of all ages, not only in general science and math education but also in specific astronomical and technological concepts relating to JWST. To date, nine graduate students have become members of NIRCam's E/PO team. They have developed curriculum and activities used to teach concepts in stellar nucleosynthesis, lookback time, galaxy classification, etc. They have also contributed to the overall strategic approach and helped lead more general activities in basic astronomy (night sky, phases of the Moon, the scale of the Solar System and beyond, stars, galaxies, telescopes, etc.) as well as JWST-specific research areas in extrasolar planetary systems and cosmology, to pave the way for girls and women to understand the first images from JWST. The resulting experience has empowered these students to propose and to develop their own E/PO programs after graduation as postdocs and young faculty. They also continue as part of NIRCam's growing worldwide network of 160 trainers teaching young women essential STEM-related concepts using astronomy, the night sky environment, applied math, engineering, and critical thinking. NIRCam and its E/PO program are funded by NASA under contract NAS5-02105.

  16. Occurrence of 210Po in periwinkle (Littorina undulata, Gray, 1839) collected from Kudankulam (Gulf of Mannar (GOM), Southeast coast of India).

    PubMed

    Sunith Shine, S R; Feroz Khan, M; Godwin Wesley, S

    2013-10-15

    Polonium-210 activity concentration was analysed in the whole body tissue of periwinkle Littorina undulata collected from intertidal rocky shore along Kudankulam coast. We carried out the study for a period of 12 months (2011-2012) focusing on three seasons. (210)Po was found non-uniformly distributed among the periwinkles depending on the allometry. The (210)Po accumulation showed a significant difference between seasons (p<0.05). Smaller sized winkles registered higher activity of (210)Po compared to larger ones (p<0.05). The overall activity range of (210)Po varied from 13.5 to 58.9 Bq/kg (wet). The activity of (210)Po was also quantified in seawater and intertidal sediments to calculate the biological concentration factor (BCF) and radiation dose rate. The dose rate to the winkles was performed using ERICA Assessment Tool and it was within the prescribed limit. The intake of (210)Po through periwinkles delivered an effective dose in the range of 2.2-9.6 μSv/y to human beings.

  17. Occurrence of 210Po in periwinkle (Littorina undulata, Gray, 1839) collected from Kudankulam (Gulf of Mannar (GOM), Southeast coast of India).

    PubMed

    Sunith Shine, S R; Feroz Khan, M; Godwin Wesley, S

    2013-10-15

    Polonium-210 activity concentration was analysed in the whole body tissue of periwinkle Littorina undulata collected from intertidal rocky shore along Kudankulam coast. We carried out the study for a period of 12 months (2011-2012) focusing on three seasons. (210)Po was found non-uniformly distributed among the periwinkles depending on the allometry. The (210)Po accumulation showed a significant difference between seasons (p<0.05). Smaller sized winkles registered higher activity of (210)Po compared to larger ones (p<0.05). The overall activity range of (210)Po varied from 13.5 to 58.9 Bq/kg (wet). The activity of (210)Po was also quantified in seawater and intertidal sediments to calculate the biological concentration factor (BCF) and radiation dose rate. The dose rate to the winkles was performed using ERICA Assessment Tool and it was within the prescribed limit. The intake of (210)Po through periwinkles delivered an effective dose in the range of 2.2-9.6 μSv/y to human beings. PMID:23871576

  18. Muon spin relaxation study of Zr(H2PO4)(PO4).2H2O.

    PubMed

    Clayden, Nigel J; Cottrell, Stephen P

    2006-07-14

    Muon spin relaxation has been used to study the muon dynamics in the layered zirconium phosphate Zr(H(2)PO(4))(PO(4)).2H(2)O as a function of temperature. Radiofrequency decoupling was used to establish the origin of the local dipolar field as coupling with (1)H spins. Muons were trapped at two sites, one identified as HMuO and the other consistent with PO-Mu on the basis of their zero-field second moments. Although a small decrease in the local nuclear dipolar field was seen with temperature, the muons remained essentially static over the temperature range 20-300 K.

  19. K3Ga2(PO4)3 and Na3Ga(PO4)2.

    PubMed

    Beaurain, M; Astier, R; van der Lee, A; Armand, P

    2008-01-01

    The structures of tripotassium digallium tris(phosphate), K3Ga2(PO4)3, and trisodium gallium bis(phosphate), Na3Ga(PO4)2, have different irregular one-dimensional alkali ion-containing channels along the a axis of the orthorhombic and triclinic unit cells, respectively. The anionic subsystems consist of vortex-linked PO4 tetrahedra and GaO4 tetrahedra or GaO5 trigonal bipyramids in the first and second structure, respectively. PMID:18216425

  20. Scavenging and fractionation of particle-reactive radioisotopes 7Be, 210Pb and 210Po in the atmosphere

    NASA Astrophysics Data System (ADS)

    Chen, Jinfang; Luo, Shangde; Huang, Yipu

    2016-09-01

    The scavenging and fractionation of 7Be, 210Pb, and 210Po in the atmosphere are investigated by measuring their activities in rainwater collected from 68 rain events during March 2004 to April 2006 at a coastal station of Xiamen, southeastern China. In addition to documenting the large temporal variations in activities, fluxes, and isotope ratios of 7Be, 210Pb and 210Po in rainwater and the role of rainfall intensity in radionuclide scavenging, our results show that an enhanced deposition of 7Be and 210Pb occurs in the spring than in other seasons and is attributed to the "funnel effect" due to the increased atmospheric vertical convective mixing in the spring. This latter hypothesis is further supported by the observed seasonal and inter-annual variations in 7Be/210Pb and 210Po/210Pb ratios showing that the weakening of vertical convective mixing or stratosphere-troposphere exchange (STE) at the study site is linked with the enhancement of summer monsoons. It appears that the rainfall intensity, in connection with the vertical (e.g., STE) and horizontal (summer monsoons) air transport, exerts an important control on the activities, fluxes, and isotope ratios of 7Be, 210Pb, and 210Po in the atmosphere. Application of the observational data to a theoretical model shows that there are significant fractionations among 7Be, 210Pb, and 210Po in the atmosphere, with the scavenging rate constant or reciprocal of the residence time of radionuclide in the atmosphere being 210Pb > 7Be > 210Po. A revised Poet et al. (1972)'s method is proposed for quantitative constraint on the scavenging behavior of radionuclide, aerosols, and aerosol-associated trace pollutants in the atmosphere.

  1. Effects of TiO 2 coating on high-temperature cycle performance of LiFePO 4-based lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chang, Hao-Hsun; Chang, Chun-Chih; Su, Ching-Yi; Wu, Hung-Chun; Yang, Mo-Hua; Wu, Nae-Lih

    LiFePO 4 particles were coated with TiO 2 (molar ratio = 3%) via a sol-gel process, and the effects of the coating on cycle performance of LiFePO 4 cathode at 55 °C against either a Li or a C (mesocarbon microbead) anode were investigated. It was found that, while the coating reduces capacity fading of the LiFePO 4/Li cell, it imposes a deteriorating effect on the LiFePO 4/C cell. Analyses on cell impedance and electrode surface morphology and composition showed that the oxide coating reduced Fe dissolution from the LiFePO 4 cathode and hence alleviated the impedance increase associated with the erosion process. This leads to reduced capacity fading as observed for the LiFePO 4/Li cell. However, the oxide coating itself was eroded upon cycling, and the dissolved Ti ions were subsequently reduced at the anode surface. Ti deposit on the C anode was found to be more active than Fe in catalyzing the formation of the solid-electrolyte interphase (SEI) layer, causing accelerated capacity decay for the LiFePO 4/C cell. The results point out the importance of evaluating the effect of cathode coating material on the anode side, which has generally been overlooked in the past studies.

  2. Synthesis of LiFePO4/Li2SiO3/reduced Graphene Oxide (rGO) Composite via Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Arifin, M.; Iskandar, F.; Aimon, A. H.; Munir, M. M.; Nuryadin, B. W.

    2016-08-01

    LiFePO4 is a type of cathode active material used for lithium ion batteries. It has a high electrochemical performance. However, it suffers from certain disadvantages such as a very low intrinsic electronic conductivity and low ionic diffusion. This study was conducted to increase the conductivity of LiFePO4. We have investigated the addition of Li2SiO3 and reduced graphene oxide (rGO) to LiFePO4. The objective of this research was to synthesize LiFePO4/Li2SiO3/rGO via hydrothermal method. Fourier transform infrared spectroscopy (FTIR) measurement showed that the peaks corresponded to the vibration of LiFePO4/Li2SiO3. Further, X-ray diffraction (XRD) measurement confirmed a single phase of LiFePO4. Finally, scanning electron microscopy (SEM) images showed that rGO was distributed on the LiFePO4/Li2SiO3 structure.

  3. Search for mixed-symmetry states in 212Po

    NASA Astrophysics Data System (ADS)

    Kocheva, D.; Rainovski, G.; Jolie, J.; Pietralla, N.; Stahl, C.; Petkov, P.; Blazhev, A.; Hennig, A.; Astier, A.; Braunroth, Th.; Cortes, L.; Dewald, A.; Djongolov, M.; Fransen, C.; Gladnishki, K.; Karayonchev, V.; Litzinger, J.; Müller-Gatermann, C.; Scheck, M.; Scholz, Ph.; Schramm, C.; Tölle, P.; Werner, V.; Witt, W.; Wölk, D.; Van Isacker, P.

    2016-06-01

    In this work we present an experiment dedicated to searching for quarupole- collective isovector valence-shell excitation — the states with so-called mixed proton-neutron symmetry (MSSs), in the nucleus 212Po. The states of interest were populated and studied by an α-transfer reaction. The experiment provides indication for existence of one-phonon MSS in the nucleus 212Po which is the first experimentally identified MSS in the region around double magic nucleus 208Pb.

  4. Working with Local School Districts: A Possible Model for ROSS E/PO Programs

    NASA Astrophysics Data System (ADS)

    Grier, J. A.; Dussault, M. E.; Spaulding, K. L.; Reinfeld, E.; Steel, S. J.; Gould, R. R.

    2004-08-01

    We designed and implemented an effective professional development experience for the science teachers of the Cambridge Public School system. The experience included curriculum consultations, a series of workshops, night observing sessions, presentations by content experts, demonstrations and modeling, as well as activities directly applicable to the teachers' classrooms. Feedback and evaluation data from teachers and professional development coordinators in the system indicated a very positive response, and direct application of material learned in the workshops to the classroom setting. Several key strategies combined to make this effort successful, cost effective and high leverage. These strategies can be exported in whole or in part to other prospective E/PO programs to increase their potential level of success. The scope of the program was well suited to a ROSS E/PO level effort. This work was funded under the NASA Office of Space Science Education and Outreach Program.

  5. Relational Aggression in Children with Preschool Onset (PO) Psychiatric Disorders

    PubMed Central

    Belden, Andy C.; Gaffrey, Michael S.; Luby, Joan L.

    2012-01-01

    Objective The role of preschool onset (PO) psychiatric disorders as correlates and/or risk factors for relational aggression during kindergarten or 1st grade was tested in a sample of N = 146 preschool-age children (3 to 5.11). Method Axis-I diagnoses and symptom scores were derived using the Preschool Age Psychiatric Assessment. Children’s roles in relational aggression as aggressor, victim, aggressive-victim, or non-aggressor/non-victim were determined at preschool and again 24 months later at elementary school entry. Results Preschoolers diagnosed with PO-psychiatric disorders were 3 times as likely as the healthy preschoolers to be classified aggressors, victims, or aggressive-victims. Children diagnosed with PO-disruptive, depressive, and/or anxiety disorders were at least 6 times as likely as children without PO-psychiatric disorders to become aggressive-victims during elementary school after covarying for other key risk factors. Conclusions Findings suggested that PO-psychiatric disorders differentiated preschool and school-age children’s roles in relational aggression based on teacher-report. Recommendations for future research and preventative intervention aimed at minimizing the development of relational aggression in early childhood by identifying and targeting PO-psychiatric disorders are made. PMID:22917202

  6. Technologically enhanced 210Pb and 210Po in iron and steel industry.

    PubMed

    Khater, Ashraf E M; Bakr, Wafaa F

    2011-05-01

    Iron and steel manufacture has been ranked as the largest industrial source of environmental contamination in the USA; the wastes generated in their production processes contain heavy elements that can be a source of contamination, and natural radionuclides that can produce an occupational and/or public radiological impact. In this work the potential occupational effective dose rate (μSv/y) due to inhalation in four integrated steel-making factories from Egypt has been evaluated, by assuming a well defined scenario and with basis in the (210)Pb and (210)Po activity concentrations determined in ore and wastes collected in the aforementioned factories. Activity concentrations, in Bq/kg, of (210)Pb and (210)Po, and leachable Pb and Fe were measured using gamma-ray spectrometry based on HPGe detector, alpha particle spectrometry based on PIPS detector, and inductively coupled plasma-mass spectrometry (ICP-MS). Levels of (210)Pb and (210)Po in the range of

  7. Partnerships: The Key to Sustainability and Reach for E/PO

    NASA Astrophysics Data System (ADS)

    Eisenhamer, Bonnie; McCallister, D.; Ryer, H.

    2013-06-01

    The Space Telescope Science Institute (STScI) is the home institution for the E/PO activities of the Hubble and future James Webb space telescopes. Over time, STScI’s Office of Public Outreach has established the infrastructure needed for an E/PO program that reaches various audiences at the local, regional, and national levels. Partnerships are a critical element of this infrastructure, and sustainability of our E/PO program is ensured through our ongoing partnerships with organizations and institutions with staying power and reach. We have learned from past efforts that strategic partnerships can foster innovation, support diversity initiatives, and increase impact in a cost-effective way while providing target audiences with greater access to NASA SMD science and resources. Partnerships are utilized to field-test educational products and programs, disseminate materials and initiatives, and support professional development activities. Partners are selected based upon specific criteria such as potential for reach, the percentage of underrepresented educators and students served, complementary program goals, and willingness to collect and share evaluation data and results with us. This poster will highlight examples and benefits of strategic partnerships over time.

  8. Fabrication of a silica sphere with fluorescent and MR contrasting GdPO4 nanoparticles from layered gadolinium hydroxide.

    PubMed

    Yoon, Young-su; Lee, Byung-Il; Lee, Kyung Sig; Heo, Hyejung; Lee, Jung Hee; Byeon, Song-Ho; Lee, In Su

    2010-06-01

    The delaminated gadolinium hydroxide layers doped with Eu(3+) ions were assembled on the surface of silica spheres and annealed at high temperatures, resulting in the formation of fluorescent and MR active GdPO(4) : Eu nanoparticles at the surface.

  9. Lifetimes of (214)Po and (212)Po measured with Counting Test Facility at Gran Sasso National Laboratory.

    PubMed

    Miramonti, L; Bellini, G; Benziger, J; Bick, D; Bonfini, G; Bravo, D; Buizza Avanzini, M; Caccianiga, B; Cadonati, L; Calaprice, F; Carraro, C; Cavalcante, P; Chavarria, A; Chubakov, V; D'Angelo, D; Davini, S; Derbin, A; Etenko, A; Fomenko, K; Franco, D; Galbiati, C; Gazzana, S; Ghiano, C; Giammarchi, M; Göger-Neff, M; Goretti, A; Grandi, L; Guardincerri, E; Hardy, S; Ianni, Aldo; Ianni, Andrea; Kobychev, V; Korablev, D; Korga, G; Koshio, Y; Kryn, D; Laubenstein, M; Lewke, T; Lissia, M; Litvinovich, E; Loer, B; Lombardi, F; Lombardi, P; Ludhova, L; Machulin, I; Manecki, S; Maneschg, W; Mantovani, F; Manuzio, G; Meindl, Q; Meroni, E; Misiaszek, M; Montanari, D; Mosteiro, P; Muratova, V; Nisi, S; Oberauer, L; Obolensky, M; Ortica, F; Otis, K; Pallavicini, M; Papp, L; Perasso, L; Perasso, S; Pocar, A; Ranucci, G; Razeto, A; Re, A; Romani, A; Rossi, N; Sabelnikov, A; Saldanha, R; Salvo, C; Schönert, S; Simgen, H; Skorokhvatov, M; Smirnov, O; Sotnikov, A; Sukhotin, S; Suvorov, Y; Tartaglia, R; Testera, G; Vignaud, D; Vogelaar, R B; von Feilitzsch, F; Winter, J; Wojcik, M; Wright, A; Wurm, M; Xhixha, G; Xu, J; Zaimidoroga, O; Zavatarelli, S; Zuzel, G

    2014-12-01

    The decays of (214)Po into (210)Pb and of (212)Po into (208)Pb tagged by the previous decays from (214)Bi and (212)Bi have been studied inserting quartz vials inside the Counting Test Facility (CTF) at the underground laboratory in Gran Sasso (LNGS). We find that the mean lifetime of (214)Po is (236.00 ± 0.42(stat) ± 0.15(syst)) μs and that of (212)Po is (425.1 ± 0.9(stat) ± 1.2(syst)) ns. Our results are compatible with previous measurements, have a much better signal to background ratio, and reduce the overall uncertainties.

  10. Lifetimes of (214)Po and (212)Po measured with Counting Test Facility at Gran Sasso National Laboratory.

    PubMed

    Miramonti, L; Bellini, G; Benziger, J; Bick, D; Bonfini, G; Bravo, D; Buizza Avanzini, M; Caccianiga, B; Cadonati, L; Calaprice, F; Carraro, C; Cavalcante, P; Chavarria, A; Chubakov, V; D'Angelo, D; Davini, S; Derbin, A; Etenko, A; Fomenko, K; Franco, D; Galbiati, C; Gazzana, S; Ghiano, C; Giammarchi, M; Göger-Neff, M; Goretti, A; Grandi, L; Guardincerri, E; Hardy, S; Ianni, Aldo; Ianni, Andrea; Kobychev, V; Korablev, D; Korga, G; Koshio, Y; Kryn, D; Laubenstein, M; Lewke, T; Lissia, M; Litvinovich, E; Loer, B; Lombardi, F; Lombardi, P; Ludhova, L; Machulin, I; Manecki, S; Maneschg, W; Mantovani, F; Manuzio, G; Meindl, Q; Meroni, E; Misiaszek, M; Montanari, D; Mosteiro, P; Muratova, V; Nisi, S; Oberauer, L; Obolensky, M; Ortica, F; Otis, K; Pallavicini, M; Papp, L; Perasso, L; Perasso, S; Pocar, A; Ranucci, G; Razeto, A; Re, A; Romani, A; Rossi, N; Sabelnikov, A; Saldanha, R; Salvo, C; Schönert, S; Simgen, H; Skorokhvatov, M; Smirnov, O; Sotnikov, A; Sukhotin, S; Suvorov, Y; Tartaglia, R; Testera, G; Vignaud, D; Vogelaar, R B; von Feilitzsch, F; Winter, J; Wojcik, M; Wright, A; Wurm, M; Xhixha, G; Xu, J; Zaimidoroga, O; Zavatarelli, S; Zuzel, G

    2014-12-01

    The decays of (214)Po into (210)Pb and of (212)Po into (208)Pb tagged by the previous decays from (214)Bi and (212)Bi have been studied inserting quartz vials inside the Counting Test Facility (CTF) at the underground laboratory in Gran Sasso (LNGS). We find that the mean lifetime of (214)Po is (236.00 ± 0.42(stat) ± 0.15(syst)) μs and that of (212)Po is (425.1 ± 0.9(stat) ± 1.2(syst)) ns. Our results are compatible with previous measurements, have a much better signal to background ratio, and reduce the overall uncertainties. PMID:24725806

  11. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  12. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  13. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  14. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  15. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  16. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  17. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  18. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  19. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  20. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  1. Get Involved in Education and Public Outreach! The Science Mission Directorate Science E/PO Forums Are Here to Help

    NASA Astrophysics Data System (ADS)

    Shipp, S. S.; Buxner, S.; Schwerin, T. G.; Hsu, B. C.; Peticolas, L. M.; Smith, D.; Meinke, B. K.

    2013-12-01

    NASA's Science Mission Directorate (SMD) Education and Public Outreach (E/PO) Forums help to engage, extend, support, and coordinate the efforts of the community of E/PO professionals and scientists involved in Earth and space science education activities. This work is undertaken to maximize the effectiveness and efficiency of the overall national NASA science education and outreach effort made up of individual efforts run by these education professionals. This includes facilitating scientist engagement in education and outreach. The Forums have been developing toolkits and pathways to support planetary, Earth, astrophysics, and heliophysics scientists who are - or who are interested in becoming - involved in E/PO. These tools include: 1) Pathways to learn about SMD and E/PO community announcements and opportunities, share news about E/PO programs, let the E/PO community know you are interested in becoming involved, and discover education programs needing scientist input and/or support. These pathways include weekly e-news, the SMD E/PO online community workspace, monthly community calls, conferences and meetings of opportunity. 2) Portals to help you find out what education resources already exist, obtain resources to share with students of all levels - from K-12 to graduate students, - and disseminate your materials. These include E/PO samplers and toolkits (sampling of resources selected for scientists who work with students, teachers, and the public), the one-stop shop of reviewed resources from the NASA Earth and space science education portfolio NASAWavelength.org, and the online clearinghouse of Earth and space science higher education materials EarthSpace (http://www.lpi.usra.edu/earthspace). 3) Connections to education specialists who can help you design and implement meaningful E/PO programs - small to large. Education specialists can help you understand what research says about how people learn and effective practices for achieving your goals, place your

  2. Ag{sub 3}PO{sub 4}/ZnO: An efficient visible-light-sensitized composite with its application in photocatalytic degradation of Rhodamine B

    SciTech Connect

    Liu, Wei; Wang, Mingliang; Xu, Chunxiang; Chen, Shifu; Fu, Xianliang

    2013-01-15

    Graphical abstract: The free OH radicals generated in the VB of ZnO play the primary role in the visible-light photocatalytic degradation of RhB in Ag{sub 3}PO{sub 4}/ZnO system. The accumulated electrons in the CB of Ag{sub 3}PO{sub 4} can be transferred to O{sub 2} adsorbed on the surface of the composite semiconductors and H{sub 2}O{sub 2} yields. H{sub 2}O{sub 2} reacts with electrons in succession to produce active ·OH to some extent. Display Omitted Highlights: ► Efficient visible-light-sensitized Ag{sub 3}PO{sub 4}/ZnO composites were successfully prepared. ► Effect of Ag{sub 3}PO{sub 4} content on the catalytic activity of Ag{sub 3}PO{sub 4}/ZnO is studied in detail. ► Rate constant of RhB degradation over Ag{sub 3}PO{sub 4}(3.0 wt.%)/ZnO is 3 times that of Ag{sub 3}PO{sub 4}. ► The active species in RhB degradation are examined by adding a series of scavengers. ► Visible light degradation mechanism of RhB over Ag{sub 3}PO{sub 4}/ZnO is systematically studied. -- Abstract: The efficient visible-light-sensitized Ag{sub 3}PO{sub 4}/ZnO composites with various weight percents of Ag{sub 3}PO{sub 4} were prepared by a facile ball milling method. The photocatalysts were characterized by XRD, DRS, SEM, EDS, XPS, and BET specific area. The ·OH radicals produced during the photocatalytic reaction was detected by the TA–PL technique. The photocatalytic property of Ag{sub 3}PO{sub 4}/ZnO was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. Significantly, the results revealed that the photocatalytic activity of the composites was much higher than that of pure Ag{sub 3}PO{sub 4} and ZnO. The rate constant of RhB degradation over Ag{sub 3}PO{sub 4}(3.0 wt.%)/ZnO is 3 times that of single-phase Ag{sub 3}PO{sub 4}. The optimal percentage of Ag{sub 3}PO{sub 4} in the composite is 3.0 wt.%. It is proposed that the ·OH radicals produced in the valence band of ZnO play the leading role in the photocatalytic degradation of

  3. RAPID DETERMINATION OF {sup 210} PO IN WATER SAMPLES

    SciTech Connect

    Maxwell, S.

    2013-05-22

    A new rapid method for the determination of {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that can be used for emergency response or routine water analyses. If a radiological dispersive device (RDD) event or a radiological attack associated with drinking water supplies occurs, there will be an urgent need for rapid analyses of water samples, including drinking water, ground water and other water effluents. Current analytical methods for the assay of {sup 210}Po in water samples have typically involved spontaneous auto-deposition of {sup 210}Po onto silver or other metal disks followed by counting by alpha spectrometry. The auto-deposition times range from 90 minutes to 24 hours or more, at times with yields that may be less than desirable. If sample interferences are present, decreased yields and degraded alpha spectrums can occur due to unpredictable thickening in the deposited layer. Separation methods have focused on the use of Sr Resin, often in combination with 210Pb analysis. A new rapid method for {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that utilizes a rapid calcium phosphate co-precipitation method, separation using DGA Resin (N,N,N,N-tetraoctyldiglycolamide extractant-coated resin, Eichrom Technologies or Triskem-International), followed by rapid microprecipitation of {sup 210}Po using bismuth phosphate for counting by alpha spectrometry. This new method can be performed quickly with excellent removal of interferences, high chemical yields and very good alpha peak resolution, eliminating any potential problems with the alpha source preparation for emergency or routine samples. A rapid sequential separation method to separate {sup 210} Po and actinide isotopes was also developed. This new approach, rapid separation with DGA Resin plus microprecipitation for alpha source preparation, is a significant advance in radiochemistry for the rapid

  4. Visible light driven Ag/Ag3PO4/AC photocatalyst with highly enhanced photodegradation of tetracycline antibiotics

    NASA Astrophysics Data System (ADS)

    Wang, Huiqin; Ye, Zhefei; Liu, Chun; Li, Jinze; Zhou, Mingjun; Guan, Qingfeng; Lv, Peng; Huo, Pengwei; Yan, Yongsheng

    2015-10-01

    Ag/Ag3PO4/active carbon (AC) composite photocatalysts were successfully synthesized using the simple deposition and photoinduced methods. The structures, morphology and photocatalytic properties of as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag/Ag3PO4/AC composite photocatalysts exhibited a conspicuously improved photocatalytic performance for tetracycline (TC) degradation. The optimal conditions of loaded dosage and photoinduced time were investigated, and the results showed that the photoinduced time played an important role in prepared processes, and also that for the loaded dosage of Ag3PO4. The DRS analysis showed that the composite photocatalysts exhibited strong absorption ability in the visible light range. The radicals trap experiments demonstrated that there were multiple active species during the degrading process of TC. The possible mechanism of improved photocatalytic activity of Ag-Ag3PO4/AC composite was also proposed.

  5. BiPo: A dedicated radiopurity detector for the SuperNEMO experiment

    SciTech Connect

    Gómez, H.; Collaboration: SuperNEMO Collaboration; and others

    2013-08-08

    New generation experiments in Astroparticle Physics need to operate in really restrictive background conditions, which implies the use of high radiopure materials for the experimental setup construction. For this reason the screening of the materials with enough sensitivity has become a challenge that sometimes cannot be afforded with standard techniques like Germanium detector spectroscopy. BiPo is a dedicated detector, that operates in the Canfranc Underground Laboratory, designed to measure the radiopurity, mainly of the ββ sources of the SuperNEMO experiment, by the detection of BiPo events. It is composed of two modules with 40 optical lines each one, registering the energy and the time of the emitted particles. The well known features of the BiPo events (delayed coincidence between an electron and an alpha particle) facilitate the discrimination of other background events that could entangle the expected signal. In addition, the geometry of the detector, with an active area of around 3.6 m{sup 2}, has been optimized to reach the necessary sensitivity levels for the SuperNEMO source foils in the shortest time possible. Preliminary results of background measurements and calibrations taken since summer 2012 shows that the required sensitivity for the measurements of the source foils could be reached in few months. Routine measurements of samples are already started being an important point for the SuperNEMO source foils construction.

  6. The Legacy of NASA Astrophysics E/PO: Scientist Engagement and Higher Education

    NASA Astrophysics Data System (ADS)

    Manning, Jim; Smith, Denise A.; Meinke, Bonnie; Lawton, Brandon; Schulz, Gregory; Bartolone, Lindsay; Bianchi, Luciana; NASA SMD Astrophysics E/PO Community

    2016-01-01

    For the past six years, NASA's Science Mission Directorate has coordinated the work of its mission- and program-embedded education and public outreach (E/PO) efforts through four forums representing its four science divisions. The Astrophysics forum, as the others, has built on the long-standing mission E/PO 1% allocation and embedded scientist/educator partnerships to encourage and coordinate collaborative efforts to make the most efficient and effective use of NASA resources, personnel, data and discoveries in leveraged ways, in support of the nation's science education. Two of the priorities established early in the forum's period of activity were to enhance scientist engagement in E/PO and to coordinate the community in providing useful higher education resources based on determined needs. This presentation will highlight some of the achievements for these two priorities over the past six years, how the products and efforts are being preserved, and how they can continue to be accessed as NASA SMD transitions to a new Education and Communication landscape. The work constitutes an ongoing legacy--a firm foundation on which the new structure of NASA SMD Education efforts will go forward.

  7. Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)

    SciTech Connect

    Andersson, V.; Chen, P.; Kamae, T.; Madejski, G.; Mizuno, T.; Ng, J.; Tajima, H.; Thurston, T.; Bogaert, G.; Fukazawa, Y.; Saito, Y.; Takahashi, T.; Barbier, L.; Bloser, P.; Harding, A.; Hunter, S.; Krizmanic, J.; Mitchell, J.; Streitmatter, R.; Fernholz, R.; Groth, E.; /NASA, Goddard /Princeton U. /Royal Inst. Tech., Kista /Stockholm U. /Tokyo Inst. Tech. /Yamagata U.

    2005-06-30

    We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (30-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO is designed to detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter consisting of a fast plastic scintillator (the detection part), a slow plastic scintillator (the active collimator) and a BGO scintillator (the bottom anti-counter). PoGO consists of close-packed array of 217 hexagonal well-type phoswich counters and has a narrow field-of-view ({approx} 5 deg{sup 2}) to reduce possible source confusion. A prototype instrument has been tested in the polarized soft gamma-ray beams at Advanced Photon Source (ANL) and at Photon Factory (KEK). On the results, the polarization dependence of EGS4 has been validated and that of Geant4 has been corrected.

  8. Particulate Scavenging and Lateral Transport Processes in the Gaoping Submarine Canyon Deduced From Pb-210 and Po-210 Observations

    NASA Astrophysics Data System (ADS)

    Hung, G.; Wang, P.; Shen, Y.

    2009-05-01

    Pb-210 and Po-210 were measured on the suspended particulate matter(SPM) and filtered water samples collected in profile from five stations in the Gaoping Submarine Canyon (GPSC) during a cruise aboard R/V Ocean Researcher III in late November, 2006. These stations were selected along the axis of the GPSC, and denoted as CW1 through CW5 sequentially from the shallow part near the mouth of the Gaoping River to the deep-water region of the canyon. Except for CW4, the SPM profiles generally show a rapid increase to a maximum near bottom, the value of which is an order of magnitude higher than that observed above, suggesting a significant particulate resuspension or lateral input in the bottom layer. The SPM concentrations obtained at canyon head stations(CW1 to CW3) vary between 0.36 and 19.17 mg/kg. These values are generally higher than those obtained farther outward(CW4 and CW5), which range from 0.01 to 2.13 mg/kg, indicating a decrease away from the shore. The dissolved Pb-210 and Po-210 profiles observed from CW1 and CW2 are fairly uniform for the entire water column, with a mean of about 14 and 12 dpm/100kg, respectively. The other stations show a large variation in dissolved Pb-210 and Po-210 with a mean of about 23 and 14 dpm/100kg, respectively. At stations CW1, CW2 and CW3, the particulate Pb-210 and Po-210 profiles generally display a maximum around 28-38 and 27-48 dpm/100kg, respectively, in the bottom layer, suggesting significant particulate resuspension and scavenging. Variable Pb-210 and Po-210 activities in the particulates at CW4 and CW5 are observed in the surface layer. Both the dissolved and the total (dissolved + particulate) Po-210 to Pb-210 activity ratios vary between 0.1 and 1.7, mostly less than 1.0, with a mean of 0.7 and 0.8, indicating a variable deficiency of Po-210 relative to Pb- 210 in this study area. Total activities of Pb-210 are generally higher than those of Po-210. The Ra-226 profiles show much lower activities than those of

  9. Bioaccumulation of 210Po and 210Pb in cephalopods collected from Kudankulam (Southeastern coast of Gulf of Mannar, India) and assessment of dose in human beings.

    PubMed

    Khan, M Feroz; Wesley, S Godwin

    2011-11-01

    Activities of (210)Po and (210)Pb in various tissues of two common species of cephalopod molluscs (cuttlefishes) of Kudankulam coast were studied. Of all the tissues, (210)Po and (210)Pb were found accumulated more in the digestive gland, shell gland and intestine. Urotheuthis duvauceli accumulated more (210)Po and (210)Pb in certain organs when compared with Sepiella inermis. The activity ratio of (210)Po/(210)Pb fell within the range of 0.6-29.3 in the organs. The biological concentration factor for the organs ranged from 1.2×10(3) to 2×10(5) for (210)Po and 3.6×10(2) to 7.6×10(4) for (210)Pb. A significant variation in the accumulation of (210)Po and (210)Pb was noted between species, organs and seasons (p < 0.05). The whole-body internal dose rate due to (210)Po was 1.24 and 0.83 µGy h(-1) and it was 2×10(-3) and 3×10(-3) µGy h(-1) due to (210)Pb for both the species. The effective dose in humans due to (210)Po intake ranged from 96.3 to 376.6 µSv y(-1) and that of (210)Pb ranged from 35.2 to 105.7 µSv y(-1), respectively. The data generated will act as a reference database for these organisms of this coast in which a nuclear power station is under construction.

  10. PoSSUM: Polar Suborbital Science in the Upper Mesosphere

    NASA Astrophysics Data System (ADS)

    Reimuller, J. D.; Fritts, D. C.; Thomas, G. E.; Taylor, M. J.; Mitchell, S.; Lehmacher, G. A.; Watchorn, S. R.; Baumgarten, G.; Plane, J. M.

    2013-12-01

    Project PoSSUM (www.projectpossum.org) is a suborbital research project leveraging imaging and remote sensing techniques from Reusable Suborbital Launch Vehicles (rSLVs) to gather critical climate data through use of the PoSSUM Observatory and the PoSSUM Aeronomy Laboratory. An acronym for Polar Suborbital Science in the Upper Mesosphere, PoSSUM grew from the opportunity created by the Noctilucent Cloud Imagery and Tomography Experiment, selected by the NASA Flight Opportunities Program as Experiment 46-S in March 2012. This experiment will employ an rSLV (e.g. the XCOR Lynx Mark II) launched from a high-latitude spaceport (e.g. Eielson AFB, Alaska or Kiruna, Sweden) during a week-long deployment scheduled for July 2015 to address critical questions concerning noctilucent clouds (NLCs) through flights that transition the cloud layer where the clouds will be under direct illumination from the sun. The 2015 Project PoSSUM NLC campaign will use the unique capability of rSLVs to address key under-answered questions pertaining to NLCs. Specifically, PoSSUM will answer: 1) What are the small-scale dynamics of NLCs and what does this tell us about the energy and momentum deposition from the lower atmosphere? 2) What is the seasonal variability of NLCs, mesospheric dynamics, and temperatures? 3) Are structures observed in the OH layer coupled with NLC structures? 4) How do NLCs nucleate? and 5) What is the geometry of NLC particles and how do they stratify? Instrumentation will include video and still-frame visible cameras (PoSSUMCam), infrared cameras, a mesospheric temperatures experiment, a depolarization LiDAR, a mesospheric density and temperatures experiment (MCAT), a mesospheric winds experiment, and a meteoric smoke detector (MASS). The instrument suite used on PoSSUM will mature through subsequent campaigns to develop an integrated, modular laboratory (the ';PoSSUM Observatory') that will provide repeatable, low cost, in-situ NLC and aeronomy observations as well

  11. Local structure of spin Peierls compound TiPO4: 47/49Ti and 31P NMR study

    NASA Astrophysics Data System (ADS)

    Stern, Raivo; Heinmaa, Ivo; Leitmäe, Alexander; Joon, Enno; Tsirlin, Alexander; Kremer, Reinhard; Glaum, Robert

    TiPO4 structure is made of slightly corrugated TiO2 ribbon chains of edge-sharing TiO6 octahedra. The almost perfect 1D spin 1/2 Ti3 + chains are well separated by PO4 tetrahedra. By magnetic susceptibility and MAS-NMR measurements [1] it was shown that TiPO4 has nonmagnetic singlet ground state with remarkably high Spin-Peierls (SP) transition temperature. The high-T magnetic susceptibility of TiPO4 follows well that of a S =1/2 Heisenberg chain with very strong nearest-neighbor AF spin-exchange coupling constant of J =965K. On cooling TiPO4 shows two successive phase transitions at 111K and 74K, with incommensurate (IC) SP phase between them. We studied local structure and dynamics in TiPO4 single crystal using 47/49Ti and 31P NMR in the temperature range 40K to 300K, and determined the principal values and orientation of the magnetic shift tensors for 31P and 47,49Ti nuclei. Since 47,49Ti (S =5/2 and S =7/2, respectively) have quadrupolar moments, we also found the principal axis values and orientations of the electric field gradient (efg) tensor in SP phase and at 295K. In SP phase the structure contains 2 magnetically inequivalent P sites and only one Ti site. From the T-dependence of the relaxation rate of 31P and 47Ti nuclei we determined activation energy Ea = 550 K for spin excitations in SP phase. J. Law et al ., PRB 83, 180414(R) (2011).

  12. Distribution and biokinetic analysis of 210Pb and 210Po in poultry due to ingestion of dicalcium phosphate.

    PubMed

    Casacuberta, N; Traversa, F L; Masqué, P; Garcia-Orellana, J; Anguita, M; Gasa, J; Garcia-Tenorio, R

    2010-09-15

    Dicalcium phosphate (DCP) is used as a calcium supplement for food producing animals (i.e., cattle, poultry and pig). When DCP is produced via wet acid digestion of the phosphate rock and depending on the acid used in the industrial process, the final product can result in enhanced (210)Pb and (210)Po specific activities (approximately 2000 Bq.kg(-1)). Both (210)Pb and (210)Po are of great interest because their contribution to the dose received by ingestion is potentially large. The aims of this work are to examine the accumulation of (210)Pb and (210)Po in chicken tissues during the first 42 days of life and to build a suitable single-compartment biokinetic model to understand the behavior of both radionuclides within the entire animal using the experimental results. Three commercial corn-soybean-based diets containing different amounts and sources of DCP were fed to broilers during a period of 42 days. The results show that diets containing enhanced concentrations of (210)Pb and (210)Po lead to larger specific accumulation in broiler tissues compared to the blank diet. Radionuclides do not accumulate homogeneously within the animal body: (210)Pb follows the calcium pathways to some extent and accumulates largely in bones, while (210)Po accumulates to a large extent in liver and kidneys. However, the total amount of radionuclide accumulation in tissues is small compared to the amounts excreted in feces. The single-compartment non-linear biokinetic model proposed here for (210)Pb and (210)Po in the whole animal takes into account the size evolution and is self-consistent in that no fitting parameterization of intake and excretions rates is required.

  13. Introducing the Adler E/PO Partnership Template

    NASA Astrophysics Data System (ADS)

    Hammergren, M.

    2003-12-01

    Education is now a core mission of NASA. Other funding agencies are increasingly insistent that researchers become scientist-educators. This trend is reflected in the growing integration of education and public outreach (E/PO) efforts within research proposals of all scales. Given little guidance apart from a budget cap, scientists can often be confused regarding the appropriate audience, content, and scale of E/PO proposals. Opened to the public in 1930 as the first planetarium in the western hemisphere, the Adler Planetarium & Astronomy Museum has inspired generations of explorers through innovative astronomy education. The Adler has a long history of successfully working with outside partners on E/PO programs, and we are enthusiastic about developing new partnerships to improve astronomy education. As part of these efforts, we will present a comprehensive source of information on the Adler's unique strengths and resources, along with a template for proposing E/PO partnerships with the Adler. The two-way exchange of information will aid in setting realistic and realizable goals for the E/PO effort, and help both parties decide whether the partnership is something they want to pursue. This service will be available online through a link on the Adler website at www.adlerplanetarium.org.

  14. An assessment of the (210)Po ingestion dose due to the consumption of agricultural, marine, fresh water and forest foodstuffs in Gudalore (India).

    PubMed

    Sivakumar, R

    2014-11-01

    The activity concentration of (210)Po in cereals, pulses, food materials of animal origin, vegetables and spices collected from Gudalore (India) has been estimated by radiochemical method. The activity concentration of (210)Po in cereals is found to vary from 124 to 604 mBq kg(-1). Raw rice registered the highest mean activity 504 ± 61 mBq kg(-1). In pulses (210)Po activity concentration varies from 42 to 320 mBq kg(-1) and the highest activity is found in black lentil with the average value of 172 ± 38 mBq kg(-1). Leafy vegetables registered the highest (210)Po activity concentration (662-7336 mBq kg(-1)) and are followed by tuber vegetables (390-1269 mBq kg(-1)) and then by other vegetables (75-595 mBq kg(-1)). The higher concentration of (210)Po observed in leafy vegetables may be attributed to the dry deposition of (210)Po and other daughter products of (222)Rn on large leaf surfaces from the air. Among animal products fish of marine origin registered the highest (210)Po activity concentration 36,850-48,964 mBq kg(-1). The mean (210)Po activity concentration in coffee has been estimated as 7500 mBq kg(-1). The activity concentration of (210)Po in leaf and bark of tree Cinnamom zeylanicum, a popular spice, is found to vary from 3500 to 11,100 mBq kg(-1) and 1600-3400 mBq kg(-1). The consumption of marine and fresh water fish contribute 60.7% (506.1 μSv y(-1)) to the total ingestion dose received. Cereals being consumed in a large scale, contribute 23.4% (194.9 μSv y(-1)) of the total ingestion dose received. The contribution from spices and leafy vegetables consumed is 5.8% (48.1 μSv y(-1)) and 6.5% (54.3 μSv y(-1)), respectively. The remaining 3.6% (30.0 μSv y(-1)) contribution to the total ingestion dose comes from other food materials and vegetables.

  15. An assessment of the (210)Po ingestion dose due to the consumption of agricultural, marine, fresh water and forest foodstuffs in Gudalore (India).

    PubMed

    Sivakumar, R

    2014-11-01

    The activity concentration of (210)Po in cereals, pulses, food materials of animal origin, vegetables and spices collected from Gudalore (India) has been estimated by radiochemical method. The activity concentration of (210)Po in cereals is found to vary from 124 to 604 mBq kg(-1). Raw rice registered the highest mean activity 504 ± 61 mBq kg(-1). In pulses (210)Po activity concentration varies from 42 to 320 mBq kg(-1) and the highest activity is found in black lentil with the average value of 172 ± 38 mBq kg(-1). Leafy vegetables registered the highest (210)Po activity concentration (662-7336 mBq kg(-1)) and are followed by tuber vegetables (390-1269 mBq kg(-1)) and then by other vegetables (75-595 mBq kg(-1)). The higher concentration of (210)Po observed in leafy vegetables may be attributed to the dry deposition of (210)Po and other daughter products of (222)Rn on large leaf surfaces from the air. Among animal products fish of marine origin registered the highest (210)Po activity concentration 36,850-48,964 mBq kg(-1). The mean (210)Po activity concentration in coffee has been estimated as 7500 mBq kg(-1). The activity concentration of (210)Po in leaf and bark of tree Cinnamom zeylanicum, a popular spice, is found to vary from 3500 to 11,100 mBq kg(-1) and 1600-3400 mBq kg(-1). The consumption of marine and fresh water fish contribute 60.7% (506.1 μSv y(-1)) to the total ingestion dose received. Cereals being consumed in a large scale, contribute 23.4% (194.9 μSv y(-1)) of the total ingestion dose received. The contribution from spices and leafy vegetables consumed is 5.8% (48.1 μSv y(-1)) and 6.5% (54.3 μSv y(-1)), respectively. The remaining 3.6% (30.0 μSv y(-1)) contribution to the total ingestion dose comes from other food materials and vegetables. PMID:25036917

  16. Transfer of ²¹⁰Po, ²¹⁰Pb and ²³⁸U from some medicinal plants to their essential oils.

    PubMed

    Al-Masri, M S; Amin, Y; Ibrahim, S; Nassri, M

    2015-03-01

    Essential oils were extracted from 35 medicinal plants used by Syrians, organic compounds were determined in these oils and concentrations of (210)Po (210)Pb and (238)U were determined in the original plants and in the essential oils. The results showed that the highest activity concentrations of (210)Po and (210)Pb were found in leaves with large surfaces and in Sage were as high as 73.5 Bq kg(-1) and 73.2 Bq kg(-1), respectively. The activity concentration of (238)U was as high as 4.26 Bq kg(-1) in Aloe. On the other hand, activity concentrations of (210)Po ranged between 0.2 and 71.1 Bq kg(-1) in extracted essential oils for Rosemary and False yellowhead, respectively. The activity concentration of (210)Pb reached 63.7 Bq kg(-1) in Aloe oil. The activity concentrations of (238)U were very low in all extracted oils; the highest value was 0.31 Bq kg(-1) in peel of Orange oil. The transfer of (210)Po and (210)Pb from plant to its oil was the highest for Eugenia; 7.1% and 5.5% for (210)Po and (210)Pb, respectively. A linear relationship was found between the transfer factor of radionuclides from plant to its essential oil and the chemical content of this oil.

  17. Transfer of ²¹⁰Po, ²¹⁰Pb and ²³⁸U from some medicinal plants to their essential oils.

    PubMed

    Al-Masri, M S; Amin, Y; Ibrahim, S; Nassri, M

    2015-03-01

    Essential oils were extracted from 35 medicinal plants used by Syrians, organic compounds were determined in these oils and concentrations of (210)Po (210)Pb and (238)U were determined in the original plants and in the essential oils. The results showed that the highest activity concentrations of (210)Po and (210)Pb were found in leaves with large surfaces and in Sage were as high as 73.5 Bq kg(-1) and 73.2 Bq kg(-1), respectively. The activity concentration of (238)U was as high as 4.26 Bq kg(-1) in Aloe. On the other hand, activity concentrations of (210)Po ranged between 0.2 and 71.1 Bq kg(-1) in extracted essential oils for Rosemary and False yellowhead, respectively. The activity concentration of (210)Pb reached 63.7 Bq kg(-1) in Aloe oil. The activity concentrations of (238)U were very low in all extracted oils; the highest value was 0.31 Bq kg(-1) in peel of Orange oil. The transfer of (210)Po and (210)Pb from plant to its oil was the highest for Eugenia; 7.1% and 5.5% for (210)Po and (210)Pb, respectively. A linear relationship was found between the transfer factor of radionuclides from plant to its essential oil and the chemical content of this oil. PMID:25531268

  18. Engaging Scientists in Meaningful E/PO: How the NASA SMD E/PO Community Addresses the Needs of the Higher Ed Community

    NASA Astrophysics Data System (ADS)

    Manning, James; Meinke, Bonnie K.; Schultz, Gregory R.; Smith, Denise A.; Lawton, Brandon L.; Gurton, Suzanne; NASA Astrophysics E/PO Community

    2015-01-01

    The NASA Astrophysics Science Education and Public Outreach Forum (SEPOF) coordinates the work of NASA Science Mission Directorate (SMD) Astrophysics EPO projects and their teams to bring cutting-edge discoveries of NASA missions to the introductory astronomy college classroom. The Astrophysics Forum assists scientist and educator involvement in SMD E/PO (uniquely poised to foster collaboration between scientists with content expertise and educators with pedagogy expertise) and makes SMD E/PO resources and expertise accessible to the science and education communities. We present three new opportunities for college instructors to bring the latest NASA discoveries in Astrophysics into their classrooms.To address the expressed needs of the higher education community, the Astrophysics Forum collaborated with the Astrophysics E/PO community, researchers, and Astronomy 101 instructors to place individual science discoveries and learning resources into context for higher education audiences. Among these resources are two Resource Guides on the topics of cosmology and exoplanets, each including a variety of accessible sources.The Astrophysics Forum also coordinates the development of the Astro 101 slide set series--5 to 7-slide presentations on new discoveries from NASA Astrophysics missions relevant to topics in introductory astronomy courses. These sets enable Astronomy 101 instructors to include new discoveries not yet in their textbooks into the broader context of the course: http://www.astrosociety.org/education/astronomy-resource-guides/.The Astrophysics Forum also coordinated the development of 12 monthly Universe Discovery Guides, each featuring a theme and a representative object well-placed for viewing, with an accompanying interpretive story, strategies for conveying the topics, and supporting NASA-approved education activities and background information from a spectrum of NASA missions and programs: http://nightsky.jpl.nasa.gov/news-display.cfm?News_ID=611

  19. Assessing the 210At impurity in the production of 211At for radiotherapy by 210Po analysis via isotope dilution alpha spectrometry.

    PubMed

    Schultz, Michael K; Hammond, Michelle; Cessna, Jeffrey T; Plascjak, Paul; Norman, Bruce; Szajek, Lawrence; Garmestani, Kayhan; Zimmerman, Brian E; Unterweger, Michael

    2006-01-01

    A method for assessing the impurity 210At in cyclotron-produced 211At via isotope dilution alpha spectrometry is presented. The activity of 210At is quantified by measuring the activity of daughter nuclide 210Po. Counting sources are prepared by spontaneous deposition of Po on a silver disc. Activity of 210At (at the time of 210Po maximum activity) is found to be 83.5+/-9.0 Bq, corresponding to an atom ratio (210At:211At at the time of distillation) of 0.010+/-0.007% (k=2). The method produces high-quality alpha spectra, with baseline alpha-peak resolution and chemical yields of greater than 85%. PMID:16563782

  20. Optimization of Carbon Coatings on LiFePO4

    SciTech Connect

    Doeff, Marca M.; Wilcox, James D.; Kostecki, Robert; Lau, Grace

    2005-07-14

    The electrochemical performance of LiFePO{sub 4} in lithium cells is strongly dependent on the structure (disordered/graphene or D/G ratio) of the in situ carbon produced during synthesis from carbon-containing precursors. Addition of pyromellitic acid (PA) prior to final calcination results in lower D/G ratios, yielding a higher-rate material. Further, improvements in electrochemical performance are realized when graphitization catalysts such as ferrocene are also added during LiFePO{sub 4} preparation, although overall carbon content is still less than 2 wt.%.

  1. Evaluation of new primers for CSF1PO.

    PubMed

    Yoshida, K; Sekiguchi, K; Kasai, K; Sato, H; Seta, S; Sensabaugh, G F

    1997-01-01

    We describe new primers for the detection of the STR polymorphism at the CSF1PO locus. These primers have been designed to produce shorter amplicons (150-182 bp) than the primers in standard use (295-327 bp). The reliability of the new primers for CSF1PO typing has been demonstrated by testing on known samples and by sequence analysis. These primers are superior to the original primers with regard to electrophoretic resolution and utility for typing of severely degraded DNA.

  2. Crystal structure, thermally stability and photoluminescence properties of novel Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors

    SciTech Connect

    Guo, Qingfeng; Liao, Libing Mei, Lefu; Liu, Haikun

    2015-03-15

    A series of novel luminescent phosphors Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} with apatite structure were synthesized via a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples, and the selected Sr{sub 9.97}(PO{sub 4}){sub 6}O:0.03Eu{sup 2+} phosphor exhibits strong thermal quenching resistance, retaining the luminance of 88.73% at 150 °C. The quenching concentration of Eu{sup 2+} in Sr{sub 10}(PO{sub 4}){sub 6}O was about 0.03 attributing to the dipole–quadrupole interaction. The Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphor exhibited a broad-band blue emission at 439 nm upon excitation at 346 nm. The results indicate that Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Graphical abstract: Sr{sub 10}(PO{sub 4}){sub 6}O:Eu{sup 2+} phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Highlights: • Sr{sub 9.97}(PO{sub 4}){sub 6}O:0.03Eu{sup 2+} phosphor exhibits strong thermal quenching resistance. • Two different Eu{sup 2+} emission centers exists in Sr{sub 10}(PO{sub 4}){sub 6}O. • The activation energy was also estimated for the Eu{sup 2+} luminescence center.

  3. Structural and Electrochemical Characterization of Pure LiFePO 4 and Nanocomposite C- LiFePO 4 Cathodes for Lithium Ion Rechargeable Batteries

    DOE PAGES

    Kumar, Arun; Thomas, R.; Karan, N. K.; Saavedra-Arias, J. J.; Singh, M. K.; Majumder, S. B.; Tomar, M. S.; Katiyar, R. S.

    2009-01-01

    Pure limore » thium iron phosphate ( LiFePO 4 ) and carbon-coated LiFePO 4 (C- LiFePO 4 ) cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on LiFePO 4 particles. Ex situ Raman spectrum of C- LiFePO 4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of LiFePO 4 and C- LiFePO 4 showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively for LiFePO 4 where as in case of C- LiFePO 4 that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO 4 was 69% after 25 cycles where as that of C- LiFePO 4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.« less

  4. Dominant-negative effect on adhesion by myelin Po protein truncated in its cytoplasmic domain

    PubMed Central

    1996-01-01

    The myelin Po protein is believed to hold myelin together via interactions of both its extracellular and cytoplasmic domains. We have already shown that the extracellular domains of Po can interact in a homophilic manner (Filbin, M.T., F.S. Walsh, B.D. Trapp, J.A. Pizzey, and G.I. Tennekoon. 1990. Nature (Lond.). 344:871-872). In addition, we have shown that for this homophilic adhesion to take place, the cytoplasmic domain of Po must be intact and most likely interacting with the cytoskeleton; Po proteins truncated in their cytoplasmic domains are not adhesive (Wong, M.H., and M.T. Filbin, 1994. J. Cell Biol. 126:1089-1097). To determine if the presence of these truncated forms of Po could have an effect on the functioning of the full-length Po, we coexpressed both molecules in CHO cells. The adhesiveness of CHO cells expressing both full-length Po and truncated Po was then compared to cells expressing only full-length Po. In these coexpressors, both the full-length and the truncated Po proteins were glycosylated. They reached the surface of the cell in approximately equal amounts as shown by an ELISA and surface labeling, followed by immunoprecipitation. Furthermore, the amount of full-length Po at the cell surface was equivalent to other cell lines expressing only full-length Po that we had already shown to be adhesive. Therefore, there should be sufficient levels of full-length Po at the surface of these coexpressors to measure adhesion of Po. However, as assessed by an aggregation assay, the coexpressors were not adhesive. By 60 min they had not formed large aggregates and were indistinguishable from the control transfected cells not expressing Po. In contrast, in the same time, the cells expressing only the full-length Po had formed large aggregates. This indicates that the truncated forms of Po have a dominant-negative effect on the adhesiveness of the full-length Po. Furthermore, from cross-linking studies, full-length Po, when expressed alone but not when

  5. Size-dependent magnetic ordering and spin dynamics in DyPO4 and GdPO4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Evangelisti, Marco; Sorop, Tibi G.; Bakharev, Oleg N.; Visser, Dirk; Hillier, Adrian D.; Alonso, Juan J.; Haase, Markus; Boatner, Lynn A.; Jos de Jongh, L.

    2011-09-01

    Low-temperature magnetic susceptibility and heat-capacity measurements on nanoparticles (d≈ 2.6 nm) of the antiferromagnetic compounds DyPO4 (TN=3.4 K) and GdPO4 (TN=0.77 K) provide clear demonstrations of finite-size effects, which limit the divergence of the magnetic correlation lengths, thereby suppressing the bulk long-range magnetic ordering transitions. Instead, the incomplete antiferromagnetic order inside the particles leads to the formation of net magnetic moments on the particles. For the nanoparticles of Ising-type DyPO4 superparamagnetic blocking is found in the ac susceptibility at ≃1 K, those of the XY-type GdPO4 analog show a dipolar spin-glass transition at ≃0.2 K. Monte Carlo simulations for the magnetic heat capacities of both bulk and nanoparticle samples are in agreement with the experimental data. Strong size effects are also apparent in the Dy3+ and Gd3+ spin dynamics, which were studied by zero-field muon spin rotation (μSR) and high-field 31P-nuclear magnetic resonance (31P-NMR) nuclear relaxation measurements. The freezing transitions observed in the ac susceptibility of the nanoparticles also appear as peaks in the temperature dependence of the zero-field μSR rates, but at slightly higher temperatures, as to be expected from the higher frequency of the muon probe. For both bulk and nanoparticles of GdPO4, the muon and 31P-NMR rates are for T⩾5 K dominated by exchange-narrowed hyperfine broadening arising from the electron spin-spin interactions inside the particles. The dipolar hyperfine interactions acting on the muons and the 31P are, however, much reduced in the nanoparticles. For the DyPO4 analogs the high-temperature rates appear to be fully determined by electron spin-lattice relaxation processes.

  6. Size-dependent magnetic ordering and spin-dynamics in DyPO4 and GdPO4 nanoparticles

    SciTech Connect

    Evangelisti, Marco; Sorop, Tibi G; Bakharev, Oleg N; Visser, Dirk; Hillier, Adrian D.; Alonso, Juan; Haase, Markus; Boatner, Lynn A; De Jongh, L. Jos

    2011-01-01

    Low-temperature magnetic susceptibility and heat capacity measurements on nanoparticles (d 2.6 nm) of the antiferromagnetic compounds DyPO4 (TN = 3:4 K) and GdPO4 (TN = 0:77 K) provide clear demonstrations of finite-size effects, which limit the divergence of the magnetic correlation lengths, thereby suppressing the bulk long-range magnetic ordering transitions. Instead, the incomplete antiferromagnetic order inside the particles leads to the formation of net magnetic moments on the particles. For the nanoparticles of Ising-type DyPO4 superparamagnetic blocking is found in the ac-susceptibility at 1 K, those of the XY-type GdPO4 analogue show a dipolar spin-glass transition at 0:2 K. Monte Carlo simulations for the magnetic heat capacities of both bulk and nanoparticle samples are in agreement with the experimental data. Strong size effects are also apparent in the Dy3+ and Gd3+ spin-dynamics, which were studied by zero-field SR relaxation and high-field 31P-NMR nuclear relaxation measurements. The freezing transitions observed in the ac-susceptibility of the nanoparticles also appear as peaks in the temperature dependence of the zero-field SR rates, but at slightly higher temperatures - as to be expected from the higher frequency of the muon probe. For both bulk and nanoparticles of GdPO4, the muon and 31P-NMR rates are for T 5 K dominated by exchange-narrowed hyperfine broadening arising from the electron spin-spin interactions inside the particles. The dipolar hyperfine interactions acting on the muons and the 31P are, however, much reduced in the nanoparticles. For the DyPO4 analogues the high-temperature rates appear to be fully determined by electron spin-lattice relaxation processes.

  7. Post-test analysis of PIPER-ONE PO-IC-2 experiment by RELAP5/MOD3 codes

    SciTech Connect

    Bovalini, R.; D`Auria, F.; Galassi, G.M.; Mazzini, M.

    1996-11-01

    RELAP5/MOD3.1 was applied to the PO-IC-2 experiment performed in PIPER-ONE facility, which has been modified to reproduce typical isolation condenser thermal-hydraulic conditions. RELAP5 is a well known code widely used at the University of Pisa during the past seven years. RELAP5/MOD3.1 was the latest version of the code made available by the Idaho National Engineering Laboratory at the time of the reported study. PIPER-ONE is an experimental facility simulating a General Electric BWR-6 with volume and height scaling ratios of 1/2,200 and 1./1, respectively. In the frame of the present activity a once-through heat exchanger immersed in a pool of ambient temperature water, installed approximately 10 m above the core, was utilized to reproduce qualitatively the phenomenologies expected for the Isolation Condenser in the simplified BWR (SBWR). The PO-IC-2 experiment is the flood up of the PO-SD-8 and has been designed to solve some of the problems encountered in the analysis of the PO-SD-8 experiment. A very wide analysis is presented hereafter including the use of different code versions.

  8. X-ray excited luminescence of polystyrene-based scintillator loaded with LaPO4-Pr nanoparticles

    NASA Astrophysics Data System (ADS)

    Demkiv, T. M.; Halyatkin, O. O.; Vistovskyy, V. V.; Gektin, A. V.; Voloshinovskii, A. S.

    2016-10-01

    Polystyrene film nanocomposites of 0.3 mm thickness with embedded LaPO4-Pr nanoparticles (40 wt. %) have been synthesized. The luminescent and kinetic properties of these polystyrene composites with embedded LaPO4-Pr nanoparticles upon pulse X-ray excitation have been studied. The luminescence intensity of this polystyrene material significantly increases as it is loaded with inorganic LaPO4-Pr nanoparticles. Nanocomposite films reveal luminescence spectra typical for polystyrene activators (p-Terphenyl and POPOP) and two components of decay time kinetics of luminescence with 12 ns and 2.8 ns time constants, depending on nanoparticle sizes. The component with 12 ns decay constant arises due to the radiative transfer of the 5d-4f-emission of the Pr3+ ions in the LaPO4 nanoparticles to the polystyrene. The decay component with the time constant 2.8 ns originates from luminescence of polystyrene matrix excited by electrons emitted from nanoparticles due to the photoeffect. This nonradiative mechanism of energy transfer from nanoparticles to polystyrene matrices is determinative for nanoparticles, as their sizes are smaller than a mean free path of an electron.

  9. Lattice site dependent cathodoluminescence behavior and surface chemical changes in a Sr5(PO4)3F host

    NASA Astrophysics Data System (ADS)

    Nagpure, I. M.; Pitale, Shreyas S.; Coetsee, E.; Ntwaeaborwa, O. M.; Terblans, J. J.; Swart, H. C.

    2012-05-01

    Eu activated Sr5(PO4)3F phosphor powders have been subjected to the electron bombardment at 2 keV (10 μA) at an oxygen pressure of 1×10-6 Torr. The synthesized Sr5(PO4)3F phosphor was identical to the hexagonal apatite structure, with the Sr present at two different sites Cs (S1) and C3 (S2) in the Sr5(PO4)3F host, as inferred from the crystallographic study. Cathodoluminescence (CL) and Auger electron spectroscopy of the phosphor excited by the same electron beam were used to monitor changes in the surface state during prolonged electron bombardment. A direct correlation between the surface reactions and the degradation of the CL brightness was observed. Both C and F were depleted from the surface during electron bombardment. The postulated mechanism for the electron stimulated chemical reactions on the phosphor surface is electron beam dissociation of molecular species to atomic species, which subsequently react with C to form volatile compounds CO2, CH4, etc. and with Sr5(PO4)3F to form a non luminescence layer of metal oxides of Sr and P.

  10. Preparation and luminescence properties of orange-red Ba3Y(PO4)3:Sm3+ phosphors

    NASA Astrophysics Data System (ADS)

    Xu, Qiguang; Xu, Denghui; Sun, Jiayue

    2015-04-01

    Ba3Y(PO4)3:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties of the as-prepared phosphor. The results show that the phosphor can be efficiently excited by ultraviolet light and emit a satisfactory orange-red performance, nicely, fitting in well with the widely used UV LED chip. Under 403 nm excitation, the 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, and 11/2) emissions of Sm3+ are obviously observed. The optimum doping concentration is 5 mol% and corresponding quenching behavior is ascribed to be electric dipole-dipole interaction according to Dexter's theory. The temperature dependent luminescence of Ba3Y(PO4)3:Sm3+ phosphor is also discussed, and the activation energy for thermal quenching is calculated as 0.34 eV. Furthermore, the chromaticity coordinates of Ba3Y(PO4)3:Sm3+ phosphor are calculated to be (0.5558, 0.4380) and the lifetime values of Ba3Y0.995(PO4)3:0.005Sm3+ was 2.45 ms.

  11. America's Earliest Revolutionary Voice: Po-Pay--Not Patrick Henry.

    ERIC Educational Resources Information Center

    Owen, Gordon R.

    A full century before Patrick Henry's persuasive battle for the rights of oppressed people, a San Juan Pueblo Indian medicine man known only as Po-Pay was the masterful communicator and agitator who orchestrated the first American revolution to drive the Spanish back into Mexico. Seeking mineral wealth, cheap labor, and the maximum number of…

  12. PoGOLite measurement of Crab polarisation and future plans

    NASA Astrophysics Data System (ADS)

    Pearce, Mark

    2016-07-01

    (For the PoGOLite Collaboration) The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter designed for the observation of bright, ~1 Crab, sources. Polarisation is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an BGO anticoincidence well. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013 resulting in a near-circumpolar flight of two weeks duration. The linear polarisation of hard X-ray emissions from the Crab was measured in a previously unexplored energy interval, 20-120 keV. The polarimetric response was characterised prior to flight using both polarised and unpolarised calibration sources. Systematic effects were addressed through observations of a background field. An upgraded polarimeter, PoGO+, is scheduled to fly in summer 2016 from Esrange. Results from the 2013 Pathfinder flight and prospects for the 2016 flight will be discussed.

  13. Pinunuuchi Po'og'ani: Southern Ute Indian Academy.

    ERIC Educational Resources Information Center

    Oberly, Stacey Inez (Wachimamachi [Antelope Woman])

    2002-01-01

    Describes the Pinunuuchi Po'og'ani, the Southern Ute Indian Academy, providing Montessori education for Southern Ute tribal members ages 6 weeks through 10 years and reviving the use of the Southern Ute language and culture among young students and their families. Describes how the program supports families, students, and staff, and incorporates…

  14. Measurement of airborne {sup 218}Po - A Bayesian approach

    SciTech Connect

    Groer, P.G.; Lo, Y.

    1996-12-01

    The standard mathematical treatment of the buildup and decay of airborne radionuclides on a filter paper uses the solutions of the so-called bateman equations adapted to the sampling process. The equations can be interpreted as differential equations for the expectation of an underlying stochastic process, which describes the random fluctuations in the accumulation and decay of the sampled radioactive atoms. The process for the buildup and decay of airborne {sup 218}Po can be characterized as an {open_quotes}immigration-death process{close_quotes} in the widely adopted, biologically based jargon. The probability distribution for the number of {sup 218}Po atoms, accumulated after sampling time t, is Poisson. We show that the distribution of the number of counts, registered by a detector with efficiency {epsilon} during a counting period T after the end of sampling, it also Poisson, with mean dependent on {epsilon},t,T, the flowrate and N{sub o}, the number of airborne {sup 218}Po atoms per unit volume. This Poisson distribution was used to construct the likelihood given the observed number of counts. After inversion with Bayes` Theorem we obtained the posterior density for N{sub o}. This density characterizes the remaining uncertainty about the measured under of {sup 218}Po atoms per unit volume of air. 6 refs., 3 figs., 1 tab.

  15. Structure for Storing Properties of Particles (PoP)

    SciTech Connect

    Patel, N. R.; Mattoon, C. M.; Beck, B. R.; Summers, N. C.; Brown, D. A.

    2014-06-01

    Some evaluated nuclear databases are critical for applications such as nuclear energy, nuclear medicine, homeland security, and stockpile stewardship. Particle masses, nuclear excitation levels, and other “Properties of Particles” are essential for making evaluated nuclear databases. Currently, these properties are obtained from various databases that are stored in outdated formats. Moreover, the “Properties of Particles” (PoP) structure is being designed that will allow storing all information for one or more particles in a single place, so that each evaluation, simulation, model calculation, etc. can link to the same data. Information provided in PoP will include properties of nuclei, gammas and electrons (along with other particles such as pions, as evaluations extend to higher energies). Presently, PoP includes masses from the Atomic Mass Evaluation version 2003 (AME2003), and level schemes and gamma decays from the Reference Input Parameter Library (RIPL-3). The data are stored in a hierarchical structure. An example of how PoP stores nuclear masses and energy levels will be presented here.

  16. Design and network applications of PoE

    NASA Astrophysics Data System (ADS)

    Feng, Xiancheng; Yun, Xiang; Chen, Ying

    2008-12-01

    With the rapid development of digital networks, many of the appliances in life are widely used, particularly in wireless LAN and IP telephony. Ethernet-based data terminals have been widely used in many areas, although the device's power consumption is low, but in general stability and reliability of the power is of very high requirements. In this paper, PoE technology (a solution focused on long-distance power supply system) is focused on the PoE power supply equipment, power-operation process, the system configuration management, automatic detection, and other major technology. Also, at the same time it introduces the use of PoE technology for wireless access points designed to supply power as a kind of typical application in the local network, the programme through the network to provide power system solutions, and expand the use of PoE equipment and make full use of the existing network resources, providing users with convenient and stable service.

  17. Structure for Storing Properties of Particles (PoP)

    SciTech Connect

    Patel, N.R.; Mattoon, C.M.; Beck, B.R.; Summers, N.C.; Brown, D.A.

    2014-06-15

    Evaluated nuclear databases are critical for applications such as nuclear energy, nuclear medicine, homeland security, and stockpile stewardship. Particle masses, nuclear excitation levels, and other “Properties of Particles” are essential for making evaluated nuclear databases. Currently, these properties are obtained from various databases that are stored in outdated formats. A “Properties of Particles” (PoP) structure is being designed that will allow storing all information for one or more particles in a single place, so that each evaluation, simulation, model calculation, etc. can link to the same data. Information provided in PoP will include properties of nuclei, gammas and electrons (along with other particles such as pions, as evaluations extend to higher energies). Presently, PoP includes masses from the Atomic Mass Evaluation version 2003 (AME2003), and level schemes and gamma decays from the Reference Input Parameter Library (RIPL-3). The data are stored in a hierarchical structure. An example of how PoP stores nuclear masses and energy levels will be presented here.

  18. Mobility of Po and U-isotopes under acid mine drainage conditions: an experimental approach with samples from Río Tinto area (SW Spain).

    PubMed

    Barbero, L; Gázquez, M J; Bolívar, J P; Casas-Ruiz, M; Hierro, A; Baskaran, M; Ketterer, M E

    2014-12-01

    Under acid mine drainage (AMD) conditions, the solubilities and mobilities of many elements are vastly different from conditions prevailing in most natural waters. Studies are underway in the Río Tinto area (Iberian Pyrite Belt), in order to understand the behavior and mobility of long-lived U-series radionuclides under AMD conditions. A set of leaching experiments utilizing typical country rocks from the Tinto River basin, waste rock pile composite materials, iron-rich riverbed sediments and gossan (weathered naturally rock) were performed towards this purpose. Initial leaching experiments using distilled water kept in contact with solid material for 300, 100, 50 and 1 h resulted in very low concentrations of U with (234)U/(238)U activity ratios close to equilibrium and activity concentrations of (210)Po < 0.03 mBq/g. Leaching experiments performed with sulfuric acid media (0.1 and 0.01 M), and contact times between the solid and solution for 24 h were conducted to quantify the amount of U-isotopes and (210)Po leached, and the radioactive disequilibria generated between the radionuclides in the leachate. These experiments show that Po mobility in acidic conditions (pH around 1-2) is very low, with (210)Po activity in the leachate to be 6% in average for the solid sample. By contrast, mobility of U-isotopes is higher than that of Po, around 1.2%.

  19. Mobility of Po and U-isotopes under acid mine drainage conditions: an experimental approach with samples from Río Tinto area (SW Spain).

    PubMed

    Barbero, L; Gázquez, M J; Bolívar, J P; Casas-Ruiz, M; Hierro, A; Baskaran, M; Ketterer, M E

    2014-12-01

    Under acid mine drainage (AMD) conditions, the solubilities and mobilities of many elements are vastly different from conditions prevailing in most natural waters. Studies are underway in the Río Tinto area (Iberian Pyrite Belt), in order to understand the behavior and mobility of long-lived U-series radionuclides under AMD conditions. A set of leaching experiments utilizing typical country rocks from the Tinto River basin, waste rock pile composite materials, iron-rich riverbed sediments and gossan (weathered naturally rock) were performed towards this purpose. Initial leaching experiments using distilled water kept in contact with solid material for 300, 100, 50 and 1 h resulted in very low concentrations of U with (234)U/(238)U activity ratios close to equilibrium and activity concentrations of (210)Po < 0.03 mBq/g. Leaching experiments performed with sulfuric acid media (0.1 and 0.01 M), and contact times between the solid and solution for 24 h were conducted to quantify the amount of U-isotopes and (210)Po leached, and the radioactive disequilibria generated between the radionuclides in the leachate. These experiments show that Po mobility in acidic conditions (pH around 1-2) is very low, with (210)Po activity in the leachate to be 6% in average for the solid sample. By contrast, mobility of U-isotopes is higher than that of Po, around 1.2%. PMID:24308958

  20. Development of a Portable Motor Learning Laboratory (PoMLab).

    PubMed

    Takiyama, Ken; Shinya, Masahiro

    2016-01-01

    Most motor learning experiments have been conducted in a laboratory setting. In this type of setting, a huge and expensive manipulandum is frequently used, requiring a large budget and wide open space. Subjects also need to travel to the laboratory, which is a burden for them. This burden is particularly severe for patients with neurological disorders. Here, we describe the development of a novel application based on Unity3D and smart devices, e.g., smartphones or tablet devices, that can be used to conduct motor learning experiments at any time and in any place, without requiring a large budget and wide open space and without the burden of travel on subjects. We refer to our application as POrtable Motor learning LABoratory, or PoMLab. PoMLab is a multiplatform application that is available and sharable for free. We investigated whether PoMLab could be an alternative to the laboratory setting using a visuomotor rotation paradigm that causes sensory prediction error, enabling the investigation of how subjects minimize the error. In the first experiment, subjects could adapt to a constant visuomotor rotation that was abruptly applied at a specific trial. The learning curve for the first experiment could be modeled well using a state space model, a mathematical model that describes the motor leaning process. In the second experiment, subjects could adapt to a visuomotor rotation that gradually increased each trial. The subjects adapted to the gradually increasing visuomotor rotation without being aware of the visuomotor rotation. These experimental results have been reported for conventional experiments conducted in a laboratory setting, and our PoMLab application could reproduce these results. PoMLab can thus be considered an alternative to the laboratory setting. We also conducted follow-up experiments in university physical education classes. A state space model that was fit to the data obtained in the laboratory experiments could predict the learning curves

  1. Development of a Portable Motor Learning Laboratory (PoMLab)

    PubMed Central

    Shinya, Masahiro

    2016-01-01

    Most motor learning experiments have been conducted in a laboratory setting. In this type of setting, a huge and expensive manipulandum is frequently used, requiring a large budget and wide open space. Subjects also need to travel to the laboratory, which is a burden for them. This burden is particularly severe for patients with neurological disorders. Here, we describe the development of a novel application based on Unity3D and smart devices, e.g., smartphones or tablet devices, that can be used to conduct motor learning experiments at any time and in any place, without requiring a large budget and wide open space and without the burden of travel on subjects. We refer to our application as POrtable Motor learning LABoratory, or PoMLab. PoMLab is a multiplatform application that is available and sharable for free. We investigated whether PoMLab could be an alternative to the laboratory setting using a visuomotor rotation paradigm that causes sensory prediction error, enabling the investigation of how subjects minimize the error. In the first experiment, subjects could adapt to a constant visuomotor rotation that was abruptly applied at a specific trial. The learning curve for the first experiment could be modeled well using a state space model, a mathematical model that describes the motor leaning process. In the second experiment, subjects could adapt to a visuomotor rotation that gradually increased each trial. The subjects adapted to the gradually increasing visuomotor rotation without being aware of the visuomotor rotation. These experimental results have been reported for conventional experiments conducted in a laboratory setting, and our PoMLab application could reproduce these results. PoMLab can thus be considered an alternative to the laboratory setting. We also conducted follow-up experiments in university physical education classes. A state space model that was fit to the data obtained in the laboratory experiments could predict the learning curves

  2. Development of a Portable Motor Learning Laboratory (PoMLab).

    PubMed

    Takiyama, Ken; Shinya, Masahiro

    2016-01-01

    Most motor learning experiments have been conducted in a laboratory setting. In this type of setting, a huge and expensive manipulandum is frequently used, requiring a large budget and wide open space. Subjects also need to travel to the laboratory, which is a burden for them. This burden is particularly severe for patients with neurological disorders. Here, we describe the development of a novel application based on Unity3D and smart devices, e.g., smartphones or tablet devices, that can be used to conduct motor learning experiments at any time and in any place, without requiring a large budget and wide open space and without the burden of travel on subjects. We refer to our application as POrtable Motor learning LABoratory, or PoMLab. PoMLab is a multiplatform application that is available and sharable for free. We investigated whether PoMLab could be an alternative to the laboratory setting using a visuomotor rotation paradigm that causes sensory prediction error, enabling the investigation of how subjects minimize the error. In the first experiment, subjects could adapt to a constant visuomotor rotation that was abruptly applied at a specific trial. The learning curve for the first experiment could be modeled well using a state space model, a mathematical model that describes the motor leaning process. In the second experiment, subjects could adapt to a visuomotor rotation that gradually increased each trial. The subjects adapted to the gradually increasing visuomotor rotation without being aware of the visuomotor rotation. These experimental results have been reported for conventional experiments conducted in a laboratory setting, and our PoMLab application could reproduce these results. PoMLab can thus be considered an alternative to the laboratory setting. We also conducted follow-up experiments in university physical education classes. A state space model that was fit to the data obtained in the laboratory experiments could predict the learning curves

  3. (137)Cs, (40)K and (210)Po in marine mammals from the southern Baltic Sea.

    PubMed

    Ciesielski, Tomasz; Góral, Marta; Szefer, Piotr; Jenssen, Bjørn Munro; Bojanowski, Ryszard

    2015-12-15

    This study provides information on baseline concentrations of the radionuclides Cesium-137, Potassium-40 and Polonium-210 in sea mammals from the Baltic Sea. The radionuclides were analyzed in the liver, kidney and muscle of harbor porpoises, striped dolphins, and gray and ringed seals from the Polish coast by γ- and α-spectrometry. Median (137)Cs activities were 14.8, 13.2 and 23.2 Bq kg(-1) w.w. in the liver, kidney and muscles, respectively. Activities of (40)K and (210)Po in the respective tissues were found to be 79.1, 79.8 and 111 Bq kg(-1) for (40)K and 58.1, 59.2 and 32.9 Bq kg(-1) for (210)Po. The measured (137)Cs concentrations were extraordinarily high in comparison to those reported in sea mammals from other locations. However, dose assessments did not imply health effects from (137)Cs exposure in Baltic Sea mammals. Correlations between (137)Cs tissue activities and reported sea water concentrations highlight the potential use of marine mammals for biomonitoring purposes. PMID:26456908

  4. (137)Cs, (40)K and (210)Po in marine mammals from the southern Baltic Sea.

    PubMed

    Ciesielski, Tomasz; Góral, Marta; Szefer, Piotr; Jenssen, Bjørn Munro; Bojanowski, Ryszard

    2015-12-15

    This study provides information on baseline concentrations of the radionuclides Cesium-137, Potassium-40 and Polonium-210 in sea mammals from the Baltic Sea. The radionuclides were analyzed in the liver, kidney and muscle of harbor porpoises, striped dolphins, and gray and ringed seals from the Polish coast by γ- and α-spectrometry. Median (137)Cs activities were 14.8, 13.2 and 23.2 Bq kg(-1) w.w. in the liver, kidney and muscles, respectively. Activities of (40)K and (210)Po in the respective tissues were found to be 79.1, 79.8 and 111 Bq kg(-1) for (40)K and 58.1, 59.2 and 32.9 Bq kg(-1) for (210)Po. The measured (137)Cs concentrations were extraordinarily high in comparison to those reported in sea mammals from other locations. However, dose assessments did not imply health effects from (137)Cs exposure in Baltic Sea mammals. Correlations between (137)Cs tissue activities and reported sea water concentrations highlight the potential use of marine mammals for biomonitoring purposes.

  5. Aquifer recharge from infiltration basins in a highly urbanized area: the river Po Plain (Italy)

    NASA Astrophysics Data System (ADS)

    Masetti, M.; Nghiem, S. V.; Sorichetta, A.; Stevenazzi, S.; Santi, E. S.; Pettinato, S.; Bonfanti, M.; Pedretti, D.

    2015-12-01

    Due to the extensive urbanization in the Po Plain in northern Italy, rivers need to be managed to alleviate flooding problems while maintaining an appropriate aquifer recharge under an increasing percentage of impermeable surfaces. During the PO PLain Experiment field campaign in July 2015 (POPLEX 2015), both active and under-construction infiltration basins have been surveyed and analyzed to identify appropriate satellite observations that can be integrated to ground based monitoring techniques. A key strategy is to have continuous data time series on water presence and level within the basin, for which ground based monitoring can be costly and difficult to be obtained consistently.One of the major and old infiltration basin in the central Po Plain has been considered as pilot area. The basin is active from 2003 with ground based monitoring available since 2009 and supporting the development of a calibrated unsaturated-saturated two-dimensional numerical model simulating the infiltration dynamics through the basin.A procedure to use satellite data to detect surface water change is under development based on satellite radar backscatter data with an appropriate incidence angle and polarization combination. An advantage of satellite radar is that it can observe surface water regardless of cloud cover, which can be persistent during rainy seasons. Then, the surface water change is correlated to the reservoir water stage to determine water storage in the basin together with integrated ground data and to give quantitative estimates of variations in the local water cycle.We evaluated the evolution of the infiltration rate, to obtain useful insights about the general recharge behavior of basins that can be used for informed design and maintenance. Results clearly show when the basin becomes progressively clogged by biofilms that can reduce the infiltration capacity of the basin by as much as 50 times compared to when it properly works under clean conditions.

  6. Lipopolysaccharide and β-1,3-glucan-binding protein (LGBP) bind to seaweed polysaccharides and activate the prophenoloxidase system in white shrimp Litopenaeus vannamei.

    PubMed

    Chen, Yu-Yuan; Chen, Jiann-Chu; Kuo, Yi-Hsuan; Lin, Yong-Chin; Chang, Yu-Hsuan; Gong, Hong-Yi; Huang, Chien-Lun

    2016-02-01

    Lipopolysaccharide and β-1,3-glucan-binding protein (LGBP), important pattern recognition proteins (PRPs), recognize lipopolysaccharide (LPS) and β-1,3-glucan (βG), known as pathogen-associated molecular patterns (PAMPs), and subsequently trigger innate immunity. Several seaweed polysaccharides and seaweed extracts increase immune parameters and resistance to pathogens. Here, we constructed the expression vector pET28b-LvLGBP and transferred it into Escherichia coli BL21 (DE3) for protein expression and to produce the recombinant protein LGBP (rLvLGBP) in white shrimp Litopenaeus vannamei. We examined the binding of rLvLGBP with seaweed-derived polysaccharides including alginate, carrageenan, fucoidan, laminarin, Gracilaria tenuistipitata extract (GTE), and Sargassum duplicatum extract (SDE), and examined the phenoloxidase activity of shrimp haemocytes incubated with a mixture of rLvLGBP and each polysaccharide. We also examined the binding of rLvLGBP with LPS and βG, and the phenoloxidase activity of shrimp haemocytes incubated with a mixture of rLvLGBP and LPS (rLvLGBP-LPS) or a mixture of rLvLGBP and βG (rLvLGBP-βG). An ELISA binding assay indicated that rLvLGBP binds to LPS, βG, alginate, carrageenan, fucoidan, laminarin, GTE, and SDE with dissociation constants of 0.1138-0.1770 μM. Furthermore, our results also indicated that the phenoloxidase activity of shrimp haemocytes incubated with a mixture of rLvLGBP and LPS, βG, alginate, carrageenan, fucoidan, laminarin, GTE, and SDE significantly increased by 328%, 172%, 200%, 213%, 197%, 194%, 191%, and 197%, respectively compared to controls (cacodylate buffer). We conclude that LvLGBP functions as a PRP, recognizes and binds to LPS, βG, alginate, carrageenan, fucoidan, laminarin, GTE, and SDE, and subsequently leads to activating innate immunity in shrimp. PMID:26522339

  7. A synthesis of LiFePO{sub 4} starting from FePO{sub 4} under reducing atmosphere

    SciTech Connect

    Prosini, Pier Paolo; Cento, Cinzia; Masci, Amedeo; Carewska, Maria; Gislon, Paola

    2014-06-19

    A fast and easy way to produce LiFePO{sub 4} starting from FePO{sub 4}, used as iron and phosphorus source, is proposed. 5% hydrogen is employed as a reducing agent and various compounds containing lithium as lithiation agents. The selected lithiation agents included: LiCl, CH{sub 3}COOLi, LiOH, Li{sub 2}S, LiH, and Li{sub 2}CO{sub 3}. Solid state synthesis is used for the LiFePO{sub 4} preparation and the so obtained materials are structurally characterized by XRD. The materials are used to fabricate composite electrode and their specific capacity is evaluated by low rate galvanostatic charge/discharge cycles (C/10 rate). Among the various lithium salts, the acetate give rise to the LiFePO{sub 4} with the best electrochemical performance. The morphology of this material is further investigated by SEM microscopy and the specific capacity is evaluated as a function of the discharge rate and the cycle number.

  8. NASA's Planetary Science E/PO Forum: Reflections on Five Years of Effort to Support an E/PO Community

    NASA Astrophysics Data System (ADS)

    Shipp, S. S.; Shebby, S.; Buxner, S.; Boonstra, D.; Cobabe-Ammann, E. A.; Cobb, W. H.; Dalton, H.; Grier, J.; Klug Boonstra, S. L.; LaConte, K.; Ristvey, J.; Shupla, C. B.; Weeks, S.; Wessen, A. S.; Zimmerman-Brachman, R.

    2014-12-01

    Over the past decade, NASA's Science Mission Directorate (SMD) has funded four education and public outreach (E/PO) forums, aligned with each of its science divisions, including Astrophysics, Earth Science, Heliophysics, and Planetary Science. Together, these forums help organize individual division E/PO programs into a coordinated, effective, efficient, nationwide effort that shares the scientific discoveries of NASA across a broad array of audiences. In the past four-and-a-half years, the Planetary Science Division's Forum - in collaboration with the other three Forums - has worked to support its community of education professionals and scientists involved in E/PO to communicate, collaborate, and strengthen their efforts. The Forum's work encompasses identification of best practices based on educational research, increasing understanding of needs through audience-based working groups, the development of strategic collaborations and partnerships to increase programmatic reach, and the creation of strategic resources to support community members in their E/PO work (e.g., an online workspace for the community to communicate, collaborate, and share practices; recommendations to scientists for increasing impact in educational settings; a one-stop shop for NASA SMD classroom and informal education products, http://nasawavelength.org). Drawing on evaluation data, the presentation will explore what resources and support mechanisms are valued by the community, ways the community uses the available resources, and the outcomes of the effort to date.

  9. The Trypsin Inhibitor Panulirin Regulates the Prophenoloxidase-activating System in the Spiny Lobster Panulirus argus

    PubMed Central

    Perdomo-Morales, Rolando; Montero-Alejo, Vivian; Corzo, Gerardo; Besada, Vladimir; Vega-Hurtado, Yamile; González-González, Yamile; Perera, Erick; Porto-Verdecia, Marlene

    2013-01-01

    The melanization reaction promoted by the prophenoloxidase-activating system is an essential defense response in invertebrates subjected to regulatory mechanisms that are still not fully understood. We report here the finding and characterization of a novel trypsin inhibitor, named panulirin, isolated from the hemocytes of the spiny lobster Panulirus argus with regulatory functions on the melanization cascade. Panulirin is a cationic peptide (pI 9.5) composed of 48 amino acid residues (5.3 kDa), with six cysteine residues forming disulfide bridges. Its primary sequence was determined by combining Edman degradation/N-terminal sequencing and electrospray ionization-MS/MS spectrometry. The low amino acid sequence similarity with known proteins indicates that it represents a new family of peptidase inhibitors. Panulirin is a competitive and reversible tight-binding inhibitor of trypsin (Ki = 8.6 nm) with a notable specificity because it does not inhibit serine peptidases such as subtilisin, elastase, chymotrypsin, thrombin, and plasmin. The removal of panulirin from the lobster hemocyte lysate leads to an increase in phenoloxidase response to LPS. Likewise, the addition of increasing concentrations of panulirin to a lobster hemocyte lysate, previously depleted of trypsin-inhibitory activity, decreased the phenoloxidase response to LPS in a concentration-dependent fashion. These results indicate that panulirin is implicated in the regulation of the melanization cascade in P. argus by inhibiting peptidase(s) in the pathway toward the activation of the prophenoloxidase enzyme. PMID:24047891

  10. The trypsin inhibitor panulirin regulates the prophenoloxidase-activating system in the spiny lobster Panulirus argus.

    PubMed

    Perdomo-Morales, Rolando; Montero-Alejo, Vivian; Corzo, Gerardo; Besada, Vladimir; Vega-Hurtado, Yamile; González-González, Yamile; Perera, Erick; Porto-Verdecia, Marlene

    2013-11-01

    The melanization reaction promoted by the prophenoloxidase-activating system is an essential defense response in invertebrates subjected to regulatory mechanisms that are still not fully understood. We report here the finding and characterization of a novel trypsin inhibitor, named panulirin, isolated from the hemocytes of the spiny lobster Panulirus argus with regulatory functions on the melanization cascade. Panulirin is a cationic peptide (pI 9.5) composed of 48 amino acid residues (5.3 kDa), with six cysteine residues forming disulfide bridges. Its primary sequence was determined by combining Edman degradation/N-terminal sequencing and electrospray ionization-MS/MS spectrometry. The low amino acid sequence similarity with known proteins indicates that it represents a new family of peptidase inhibitors. Panulirin is a competitive and reversible tight-binding inhibitor of trypsin (Ki = 8.6 nm) with a notable specificity because it does not inhibit serine peptidases such as subtilisin, elastase, chymotrypsin, thrombin, and plasmin. The removal of panulirin from the lobster hemocyte lysate leads to an increase in phenoloxidase response to LPS. Likewise, the addition of increasing concentrations of panulirin to a lobster hemocyte lysate, previously depleted of trypsin-inhibitory activity, decreased the phenoloxidase response to LPS in a concentration-dependent fashion. These results indicate that panulirin is implicated in the regulation of the melanization cascade in P. argus by inhibiting peptidase(s) in the pathway toward the activation of the prophenoloxidase enzyme.

  11. Nanoscale LiFePO4 and Li4Ti5O12 for High Rate Li-ion Batteries

    SciTech Connect

    Jaiswal, A.; Horne, C.R.; Chang, O.; Zhang, W.; Kong, W.; Wang, E.; Chern, T.; Doeff, M. M.

    2009-08-04

    The electrochemical performances of nanoscale LiFePO4 and Li4Ti5O12 materials are described in this communication. The nanomaterials were synthesized by pyrolysis of an aerosol precursor. Both compositions required moderate heat-treatment to become electrochemically active. LiFePO4 nanoparticles were coated with a uniform, 2-4 nm thick carbon-coating using an organic precursor in the heat treatment step and showed high tap density of 1.24 g/cm3, in spite of 50-100 nm particle size and 2.9 wtpercent carbon content. Li4Ti5O12 nanoparticles were between 50-200 nm in size and showed tap density of 0.8 g/cm3. The nanomaterials were tested both in half cell configurations against Li-metal and also in LiFePO4/Li4Ti5O12 full cells. Nano-LiFePO4 showed high discharge rate capability with values of 150 and 138 mAh/g at C/25 and 5C, respectively, after constant C/25 charges. Nano-Li4Ti5O12 also showed high charge capability with values of 148 and 138 mAh/g at C/25 and 5C, respectively, after constant C/25 discharges; the discharge (lithiation) capability was comparatively slower. LiFePO4/Li4Ti5O12 full cells deliver charge/discharge capacity values of 150 and 122 mAh/g at C/5 and 5C, respectively.

  12. 76 FR 40849 - Post Office (PO) Box Fee Groups for Merged Locations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-12

    ... 111 Post Office (PO) Box Fee Groups for Merged Locations AGENCY: Postal Service. TM ACTION: Proposed... Service, Domestic Mail Manual (DMM ) 508.4 to allow Post Office TM (PO) Box fee groups to be merged due to... , with a subject line of ``PO Box Fee Group for Merged Locations.'' Faxed comments are not accepted....

  13. Thermal compensation in GaPO4 beam resonators: experimental evidence for length extensional mode.

    PubMed

    Sthal, Fabrice; Bigler, Emmanuel; Bourquin, Roger

    2007-01-01

    Temperature effects in gallium orthophosphate (GaPO4) vibrating beams are reported. In addition to the well-known, thickness-shear AT-cut, temperature-compensated cuts exist in GaPO4 for length extensional modes. Experimental evidence of a temperature-compensated cut in GaPO4 rectangular beam resonator vibrating in length extension is given. PMID:17225814

  14. Boron and Nitrogen Codoped Carbon Layers of LiFePO4 Improve the High-Rate Electrochemical Performance for Lithium Ion Batteries.

    PubMed

    Zhang, Jinli; Nie, Ning; Liu, Yuanyuan; Wang, Jiao; Yu, Feng; Gu, Junjie; Li, Wei

    2015-09-16

    An evolutionary composite of LiFePO4 with nitrogen and boron codoped carbon layers was prepared by processing hydrothermal-synthesized LiFePO4. This novel codoping method is successfully applied to LiFePO4 for commercial use, and it achieved excellent electrochemical performance. The electrochemical performance can be improved through single nitrogen doping (LiFePO4/C-N) or boron doping (LiFePO4/C-B). When modifying the LiFePO4/C-B with nitrogen (to synthesis LiFePO4/C-B+N) the undesired nonconducting N-B configurations (190.1 and 397.9 eV) are generated. This decreases the electronic conductivity from 2.56×10(-2) to 1.30×10(-2) S cm(-1) resulting in weak electrochemical performance. Nevertheless, using the opposite order to decorate LiFePO4/C-N with boron (to obtain LiFePO4/C-N+B) not only eliminates the nonconducting N-B impurity, but also promotes the conductive C-N (398.3, 400.3, and 401.1 eV) and C-B (189.5 eV) configurations-this markedly improves the electronic conductivity to 1.36×10(-1) S cm(-1). Meanwhile the positive doping strategy leads to synergistic electrochemical activity distinctly compared with single N- or B-doped materials (even much better than their sum capacity at 20 C). Moreover, due to the electron and hole-type carriers donated by nitrogen and boron atoms, the N+B codoped carbon coating tremendously enhances the electrochemical property: at the rate of 20 C, the codoped sample can elevate the discharge capacity of LFP/C from 101.1 mAh g(-1) to 121.6 mAh g(-1), and the codoped product based on commercial LiFePO4/C shows a discharge capacity of 78.4 mAh g(-1) rather than 48.1 mAh g(-1). Nevertheless, the B+N codoped sample decreases the discharge capacity of LFP/C from 101.1 mAh g(-1) to 95.4 mAh g(-1), while the commercial LFP/C changes from 48.1 mAh g(-1) to 40.6 mAh g(-1).

  15. 210Pb and 210Po concentrations in Italian cigarettes and effective dose evaluation.

    PubMed

    Taroni, Mattia; Zagà, Vincenzo; Bartolomei, Paolo; Gattavecchia, Enrico; Pacifici, Roberta; Zuccaro, Piergiorgio; Esposito, Massimo

    2014-09-01

    It has been known for a long time that cigarette tobacco contains naturally occurring radioactive nuclides such as 210Pb and 210Po. In this study, the concentrations of 210Pb and 210Po in the 10 most widely sold cigarette brands in Italy during the year 2010 were measured, and the effective dose to smokers has been calculated. The results of this study show that 210Pb concentration ranged from 11.6 to 20.0 mBq cig-1 with an arithmetic mean of 14.6 mBq cig-1, while the activity concentration of 210Po ranged from 13.1 to 19.0 mBq cig-1 with an arithmetic mean of 15.7 mBq cig-1, thus confirming previous results and showing that the radioactivity concentration was not reduced in the last few years. The annual effective dose for a typical smoker consuming 20 cigarettes per day ranged from an average of 55 μSv y-1 to about 81 μSv y-1. It is finally put in evidence the need to improve the knowledge about crucial data needed for accurate dose assessment deriving from the inhalation of both radioisotopes contained in the cigarettes, namely the dose conversion coefficients, which strongly depend on several parameters such as the inhalation speed through the mouth, the real fraction of radionuclide transferred from cigarette to mainstream smoke, the lung absorption behavior of the radioisotopes inhaled with mainstream smoke, and the AMAD of particles inhaled by smokers.

  16. 210Pb and 210Po concentrations in Italian cigarettes and effective dose evaluation.

    PubMed

    Taroni, Mattia; Zagà, Vincenzo; Bartolomei, Paolo; Gattavecchia, Enrico; Pacifici, Roberta; Zuccaro, Piergiorgio; Esposito, Massimo

    2014-09-01

    It has been known for a long time that cigarette tobacco contains naturally occurring radioactive nuclides such as 210Pb and 210Po. In this study, the concentrations of 210Pb and 210Po in the 10 most widely sold cigarette brands in Italy during the year 2010 were measured, and the effective dose to smokers has been calculated. The results of this study show that 210Pb concentration ranged from 11.6 to 20.0 mBq cig-1 with an arithmetic mean of 14.6 mBq cig-1, while the activity concentration of 210Po ranged from 13.1 to 19.0 mBq cig-1 with an arithmetic mean of 15.7 mBq cig-1, thus confirming previous results and showing that the radioactivity concentration was not reduced in the last few years. The annual effective dose for a typical smoker consuming 20 cigarettes per day ranged from an average of 55 μSv y-1 to about 81 μSv y-1. It is finally put in evidence the need to improve the knowledge about crucial data needed for accurate dose assessment deriving from the inhalation of both radioisotopes contained in the cigarettes, namely the dose conversion coefficients, which strongly depend on several parameters such as the inhalation speed through the mouth, the real fraction of radionuclide transferred from cigarette to mainstream smoke, the lung absorption behavior of the radioisotopes inhaled with mainstream smoke, and the AMAD of particles inhaled by smokers. PMID:25068956

  17. Stochastic analysis to assess the spatial distribution of groundwater nitrate concentrations in the Po catchment (Italy).

    PubMed

    Cinnirella, Sergio; Buttafuoco, Gabriele; Pirrone, Nicola

    2005-02-01

    A large database including temporal trends of physical, ecological and socio-economic data was developed within the EUROCAT project. The aim was to estimate the nutrient fluxes for different socio-economic scenarios at catchment and coastal zone level of the Po catchment (Northern Italy) with reference to the Water Quality Objectives reported in the Water Framework Directive (WFD 2000/60/CE) and also in Italian legislation. Emission data derived from different sources at national, regional and local levels are referred to point and non-point sources. While non-point (diffuse) sources are simply integrated into the nutrient flux model, point sources are irregularly distributed. Intensive farming activity in the Po valley is one of the main Pressure factors Driving groundwater pollution in the catchment, therefore understanding the spatial variability of groundwater nitrate concentrations is a critical issue to be considered in developing a Water Quality Management Plan. In order to use the scattered point source data as input in our biogeochemical and transport models, it was necessary to predict their values and associated uncertainty at unsampled locations. This study reports the spatial distribution and uncertainty of groundwater nitrate concentration at a test site of the Po watershed using a probabilistic approach. Our approach was based on geostatistical sequential Gaussian simulation used to yield a series of stochastic images characterized by equally probable spatial distributions of the nitrate concentration across the area. Post-processing of many simulations allowed the mapping of contaminated and uncontaminated areas and provided a model for the uncertainty in the spatial distribution of nitrate concentrations.

  18. Pressure-Induced Zircon-Type to Scheelite-Type Phase Transition in Orthophosphates YbPO4 and LuPO4

    SciTech Connect

    Zhang, F.; Maik, L; Ewing, R; Lian, J; Wang, Z; Hu, J; Boatner, L

    2008-01-01

    The tetragonal orthophosphates, YbPO4 and LuPO4, were studied by in situ X-ray diffraction (XRD) at pressures up to 52 and 43 GPa, respectively. A reversible phase transition from the zircon structure-type to the scheelite structure-type was found at not, vert, similar22 GPa for YbPO4 and 19 GPa for LuPO4. Coinciding with the transition from the zircon structure-type to the scheelite structure-type, there is a not, vert, similar 10% reduction in volume and a significant increase in the bulk modulus for both compounds.

  19. High pressure structural phase transitions of PbPo

    NASA Astrophysics Data System (ADS)

    Bencherif, Y.; Boukra, A.; Zaoui, A.; Ferhat, M.

    2012-09-01

    First-principles calculations have been performed to investigate the high pressure phase transitions and dynamical properties of the less known lead polonium compound. The calculated ground state parameters for the NaCl phase show good agreement with the experimental data. The obtained results show that the intermediate phase transition for this compound is the orthorhombic Pnma phase. The PbPo undergoes from the rocksalt to Pnma phase at 4.20 GPa. Further structural phase transition from intermediate to CsCl phase has been found at 8.5 GPa. In addition, phonon dispersion spectra were derived from linear-response to density functional theory. In particular, we show that the dynamical properties of PbPo exhibit some peculiar features compared to other III-V compounds. Finally, thermodynamics properties have been also addressed from quasiharmonic approximation.

  20. The BiPo detector for ultralow radioactivity measurements

    SciTech Connect

    Bongrand, M.

    2007-03-28

    The BiPo project is dedicated to the measurement of extremely low radioactivity contamination of SuperNEMO source foils (208Tl < 2 {mu}Bq/kg and 214Bi < 10 {mu}Bq/kg). The R and D phase is started : a modular BiPo prototype with its shielding test facility is under construction. The goal of this prototype is to study the background and particularly the surface contamination of scintillators. The first capsule has been installed in the Canfranc Underground Laboratory in October, 17th and is now taking data. After 10.7 days of measurements, a preliminary upper limit on the surface radiopurity of the scintillators of A(208Tl) < 60 {mu}Bq/m2 (90% C. L.) has been obtained.

  1. Graphs for Isotopes of 84-Po(Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides a graphic representation of nucleon separation energies and residual interaction parameters for isotopes of the chemical element 84-Po (Polonium, atomic number Z = 84).

  2. Stoichiometry, spin fluctuations, and superconductivity in LaNiPO

    SciTech Connect

    Klimczuk, Tomasz; Mcqueen, Tyrel M; Williams, Anthony J; Huang, Qiang; Cava, Robert J

    2009-01-01

    Superconductivity in LaNiPO is disrupted by small ({approx}5%) amounts of non-stoichiometry on the lanthanum site, even though the electronic contribution to the heat capacity increases with increasing non-stoichiometry. All samples also exhibit specific heat anomalies consistent with the presence of ferromagnetic spin fluctuations (T{sub sf}{approx} 14K). Comparison of layered nickel phosphide and nickel borocarbide superconductors reveals different structure-property correlations in the two families.

  3. Origin of the charge gap in LaMnPO

    DOE PAGES

    McNally, D. E.; Simonson, Jack W.; Post, K. W.; Yin, Zhiping P.; Pezzoli, M.; Smith, G. J.; Leyva, V.; Marques, C.; Debeer-Schmitt, Lisa M.; Kolesnikov, Alexander I.; et al

    2014-11-18

    In this paper, we present high temperature inelastic neutron scattering and magnetic susceptibility measurements of the antiferromagnetic insulator LaMnPO that are consistent with the presence of two-dimensional magnetic correlations up to a temperature Tmax≈700K»TN=375 K, the Néel temperature. Optical transmission measurements show the T=300 K direct charge gap Δ=1 eV has decreased only marginally by 500 K and suggest it decreases by only 10% at Tmax. Density functional theory and dynamical mean-field theory calculations reproduce a direct charge gap in paramagnetic LaMnPO only when a strong Hund's coupling JH=0.9 eV is included, as well as on-site Hubbard U=8 eV. Inmore » conclusion, our results show that LaMnPO is a Mott-Hund's insulator, in which the charge gap is rather insensitive to antiferromagnetic exchange coupling.« less

  4. Can Vanadium Be Substituted into LiFePO4

    SciTech Connect

    Omenya F.; Nam K.; Chernova N.A.; Upreti S.; Zavalij P.Y.; Nam K.-W.; Yang X.-Q.; Whittingham M.S.

    2011-11-08

    Vanadium is shown to substitute for iron in the olivine LiFePO{sub 4} up to at least 10 mol %, when the synthesis is carried out at 550 C. In the solid solution LiFe{sub 1-3y/2}V{sub y}PO{sub 4}, the a and b lattice parameters and cell volume decrease with increasing vanadium content, while the c lattice parameter increases slightly. However, when the synthesis is performed at 650 C, a NASICON phase, Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}, is also formed, showing that solid solution is a function of the synthesis temperature. X-ray absorption near-edge structure indicates vanadium is in the 3+ oxidation state and in an octahedral environment. Magnetic studies reveal a shift of the antiferromagnetic ordering transition toward lower temperatures with increasing vanadium substitution, confirming solid solution formation. The addition of vanadium enhances the electrochemical performance of the materials especially at high current densities.

  5. Origin of the charge gap in LaMnPO

    SciTech Connect

    McNally, D. E.; Simonson, Jack W.; Post, K. W.; Yin, Zhiping P.; Pezzoli, M.; Smith, G. J.; Leyva, V.; Marques, C.; Debeer-Schmitt, Lisa M.; Kolesnikov, Alexander I.; Zhao, Yang; Lynn, J. W.; Basov, D. N.; Kotliar, G.; Aronson, Meigan C.

    2014-11-18

    In this paper, we present high temperature inelastic neutron scattering and magnetic susceptibility measurements of the antiferromagnetic insulator LaMnPO that are consistent with the presence of two-dimensional magnetic correlations up to a temperature Tmax≈700K»TN=375 K, the Néel temperature. Optical transmission measurements show the T=300 K direct charge gap Δ=1 eV has decreased only marginally by 500 K and suggest it decreases by only 10% at Tmax. Density functional theory and dynamical mean-field theory calculations reproduce a direct charge gap in paramagnetic LaMnPO only when a strong Hund's coupling JH=0.9 eV is included, as well as on-site Hubbard U=8 eV. In conclusion, our results show that LaMnPO is a Mott-Hund's insulator, in which the charge gap is rather insensitive to antiferromagnetic exchange coupling.

  6. The Time History of Events and Macroscale Interactions during Substorms (THEMIS) Education and Outreach (E/PO) Program

    NASA Astrophysics Data System (ADS)

    Peticolas, L. M.; Craig, N.; Odenwald, S. F.; Walker, A.; Russell, C. T.; Angelopoulos, V.; Willard, C.; Larson, M. B.; Hiscock, W. A.; Stoke, J. M.; Moldwin, M. B.

    2008-12-01

    During the pre-launch phase of NASA’s THEMIS mission, the Education and Public Outreach (E/PO) program successfully brought the excitement of THEMIS to the public, students and teachers through a variety of programs. The Geomagnetic Event Observation Network by Students (GEONS) was the main effort during this time, a project in which 13 magnetometers were placed in or near 13 rural schools across the country. High school teachers and a few middle school teachers at these and/or neighboring schools took part in a long-term professional development program based around space science and the magnetometer data. The teachers created week-long to semester-long projects during which their students worked on THEMIS lessons that they, their colleagues, and the E/PO team created. In addition to this program, THEMIS E/PO also launched the only Lawrence Hall of Science (LHS) Great Explorations in Mathematics and Science (GEMS) site in Nevada. This site provides a sustainable place for teacher professional development using hands-on GEMS activities, and has been used by teachers around the state of Nevada. Short-term professional development for K-12 teachers (one-hour to two-day workshops), with a focus on the Tribal College and Society for the Advancement of Chicanos and Native Americans in Science (SACNAS) communities have reached hundreds of teachers across the country. A Space Telescope Science Institute (STScI) ViewSpace show on auroras and THEMIS was created and distributed, and shown in over a hundred science centers and museums nationwide. The THEMIS E/PO program developed and maintained a THEMIS E/PO Website for dissemination of (1) information and multimedia about the science and engineering of THEMIS, (2) updated news about the mission in language appropriate for the public, (3) the GEONS data, the GEONS teacher guides with classroom activities, and (4) information about the THEMIS E/PO program. Hundreds of thousands of visitors have viewed this website. In this

  7. Visible light assisted degradation of organic dye using Ag3PO4

    NASA Astrophysics Data System (ADS)

    Dhanabal, R.; Velmathi, S.; Bose, A. Chandra

    2015-06-01

    The study of visible light photodegradation of organic dye Methylene Blue (MB) have been investigated using silver phosphate (Ag3PO4) as a photocatalyst which is good efficient material for photocatalytic reaction. The simple ion-exchange method is used to prepare Ag3PO4. The structure of the material have been confirmed using X-ray diffraction which shows cubic structure of Ag3PO4. The functional group of the Ag3PO4 has been verified by Fourier transform infrared spectroscopy. The bandgap of Ag3PO4 is calculated using kubelka-munk function from the ultra violet-visible diffuse reflectance spectroscopy, the absorption of Ag3PO4 starts from 470 nm. Under simulated visible light irradiation, Ag3PO4 catalyst exhibits good catalytic ability for degrading MB dye.

  8. A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

    PubMed

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    2016-04-01

    The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile.

  9. Combined operando X-ray diffraction–electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    PubMed Central

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-01-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ∼20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4. PMID:26345306

  10. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries

    NASA Astrophysics Data System (ADS)

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-09-01

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ~20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4.

  11. A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

    PubMed

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    2016-04-01

    The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile. PMID:26645235

  12. Preparation of porous glass-ceramics with a skeleton of NASICON-type crystal CuTi{sub 2}(PO{sub 4}){sub 3}

    SciTech Connect

    Yamamoto, Kousuke, Kasuga, Toshihiro; Abe, Yoshihiro

    1997-03-01

    A novel porous glass-ceramic with a skeleton of CuTi{sub 2}(PO{sub 4}){sub 3} was prepared by controlled crystallization of a glass and subsequent chemical leaching of the resulting dense glass-ceramic. A volume-crystallized dense glass-ceramic composed of CuTi{sub 2}(PO{sub 4}){sub 3} and Cu{sub 3}(PO{sub 4}){sub 2} whose surface was covered by a CuO thin layer was prepared by reheating a glass with a nominal composition of 50 CuO{center_dot}20TiO{sub 2}{center_dot}30P{sub 2}O{sub 5} (in mol%) glass in air. When the resultant glass-ceramic was leached with dilute H{sub 2}SO{sub 4}, Cu{sub 3}(PO{sub 4}){sub 2} and CuO phases were dissolved out selectively, leaving a crystalline CuTi{sub 2}(PO{sub 4}){sub 3} skeleton. The specific surface area and the average pore radius of the porous glass-ceramic obtained were approximately 45 m{sup 2}{center_dot}g{sup {minus}1} and 9 nm, respectively. The porous glass-ceramic showed catalytic activity in the conversion reaction of propene into acrolein.

  13. Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries.

    PubMed

    Hess, Michael; Sasaki, Tsuyoshi; Villevieille, Claire; Novák, Petr

    2015-09-08

    Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ∼20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4.

  14. Luminescence and energy transfer in Eu2+, Mn2+ co-doped Ca2SrNaLa(PO4)3F

    NASA Astrophysics Data System (ADS)

    Shanshan, Hu; Wanjun, Tang

    2013-12-01

    A new compound Ca2SrNaLa(PO4)3F, isotypic with hexagonal Ca(Sr,Na,Ca)(Ca,Sr,Ce)3(PO4)3F, is reported. Its cell parameters have been determined from X-ray powder diffraction data. Crystallization occurs in the hexagonal space group P63 (No. 173) with a = 9.515(1) Å, c = 7.028(1) Å, and Z = 2. Eu2+ and Mn2+ activated Ca2SrNaLa(PO4)3F phosphors have been prepared. The energy transfer of Eu2+ → Mn2+ has been investigated. The resonant type energy transfer from Eu2+ to Mn2+ has been demonstrated, and the energy transfer efficiency has also been calculated according to their PL decay curves. A color-tunable emission in Ca2SrNaLa(PO4)3F phosphors can be realized by Eu2+ → Mn2+ energy transfer. White light can be achieved in a single-phased Ca2SrNaLa(PO4)3F host by co-doping Eu2+ and Mn2+ with CIE (0.32, 0.31). Our results demonstrate that the potential application of these phosphors in solid-state lighting and (or) other areas.

  15. Crystal structure and ion conductivity of a new mixed-anion phosphate LiMg3(PO4)P2O7

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Chul; Lee, Mi-Sun; Kang, Jinyeong; Kim, Young-Il; Kim, Seung-Joo

    2015-05-01

    A new lithium-containing phosphate, LiMg3(PO4)P2O7, was prepared by a solid-state reaction, and it was characterized by an ab initio structure determination method on the basis of synchrotron powder X-ray diffraction data. LiMg3(PO4)P2O7 was found to be orthorhombic (space group Pnma) with lattice parameters a=9.0387(1) Å, b=10.6072(1) Å, c=8.3065(1) Å, and V=796.39(1) Å3. The structure features infinite [Mg3O10]∞ layers that are parallel to the bc plane and that are interconnected along the a axis by PO4 and P2O7 groups. The [Mg3O10]∞ layer contains Mg3O14 trimers that are formed by three edge-shared MgO6 octahedra. The PO4 and P2O7 groups are located alternatively between [Mg3O10]∞ layers. This gives rise to a three-dimensional framework that contains large tunnels along the directions [1 0 0] and [0 1 0]; the Li+ ions are stabilized in these tunnels. AC impedance spectroscopy shows that LiMg3(PO4)P2O7 has an ionic conductivity of 3.40×10-5 S cm-1 at 769 K, with an activation energy of 1.17 eV.

  16. First-principles investigation of the electronic and Li-ion diffusion properties of LiFePO{sub 4} by sulfur surface modification

    SciTech Connect

    Xu, Guigui E-mail: zghuang@fjnu.edu.cn; Zhong, Kehua; Zhang, Jian-Min; Huang, Zhigao E-mail: zghuang@fjnu.edu.cn

    2014-08-14

    We present a first-principles calculation for the electronic and Li-ion diffusion properties of the LiFePO{sub 4} (010) surface modified by sulfur. The calculated formation energy indicates that the sulfur adsorption on the (010) surface of the LiFePO{sub 4} is energetically favored. Sulfur is found to form Fe-S bond with iron. A much narrower band gap (0.67 eV) of the sulfur surface-modified LiFePO{sub 4} [S-LiFePO{sub 4} (010)] is obtained, indicating the better electronic conductive properties. By the nudged elastic band method, our calculations show that the activation energy of Li ions diffusion along the one-dimensional channel on the surface can be effectively reduced by sulfur surface modification. In addition, the surface diffusion coefficient of S-LiFePO{sub 4} (010) is estimated to be about 10{sup −11} (cm{sup 2}/s) at room temperature, which implies that sulfur modification will give rise to a higher Li ion carrier mobility and enhanced electrochemical performance.

  17. Occurrence of 210Po and Biological Effects of Low-Level Exposure: The Need for Research

    PubMed Central

    Wiemels, Joseph L.

    2012-01-01

    Background: Polonium-210 (210Po) concentrations that exceed 1 Bq/L in drinking-water supplies have been reported from four widely separated U.S. states where exposure to it went unnoticed for decades. The radionuclide grandparents of 210Po are common in sediments, and segments of the public may be chronically exposed to low levels of 210Po in drinking water or in food products from animals raised in contaminated areas. Objectives: We summarized information on the environmental behavior, biokinetics, and toxicology of 210Po and identified the need for future research. Methods: Potential linkages between environmental exposure to 210Po and human health effects were identified in a literature review. Discussion: 210Po accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate 210Po, the ovary may be the critical organ in determining the lowest injurious dose for 210Po. 210Po also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to 210Po may have subtle, long-term biological effects because of its tropism towards reproductive and embryonic and fetal tissues where exposure to a single alpha particle may kill or damage critical cells. 210Po is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of 210Po. Conclusions: Much of the important biological and toxicological research on 210Po is more than four decades old. New research is needed to evaluate environmental exposure to 210Po and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary. PMID:22538346

  18. Thermal Stability and Phase Transformation of Electrochemically Charged/Discharged LiMnPO4 Cathode for Li-Ion Battery

    SciTech Connect

    Choi, Daiwon; Xiao, Jie; Choi, Young Joon; Hardy, John S.; Vijayakumar, M.; Bhuvaneswari, M. S.; Liu, Jun; Xu, Wu; Wang, Wei; Yang, Zhenguo; Graff, Gordon L.; Zhang, Jiguang

    2011-11-01

    Electrochemically active LiMnPO4 nanoplate at lithiated/delithiated state were subjected to thermal stability and phase transformation evaluate for safety as a cathode material for Li-ion battery. The phase transformation and oxygen evolution temperature on the delithiated MnPO4 were characterized using in-situ hot-stage X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), thermogravimetric - differential scanning calorimetry - mass spectroscopy (TGA-DSC-MS), transmission electron microscopy and scanning electron microscopy (SEM) - energy dispersive X-ray analysis (EDAX).

  19. Experimental studies about the ratio between 210Po deposited on surfaces and retrospective indoor 222Rn concentrations.

    PubMed

    Martín Sánchez, A; de la Torre Pérez, J; Ruano Sánchez, A B

    2014-07-01

    Measurements of radon concentration may not be sufficiently representative for the cumulative total exposure suffered by a person throughout his life. Retrospective dosimetry can help estimating from the direct measurement of 210Po (descendant of 222Rn) implanted on surfaces, because this quantity is related (through the conversion factor) with the mean indoor 222Rn concentration existing in a room for long time. This factor depends on multiple variables. Theoretical models can provide some values. Experiments are tedious and very time consuming. The 210Po activity concentration was measured in mirrors, which were previously exposed to 222Rn concentrations under real environmental conditions. This work deals with the preliminary results in two known places (a room and a cave), which have very different characteristics, in order to show experimentally the large differences found in the values of this factor.

  20. Experimental studies about the ratio between 210Po deposited on surfaces and retrospective indoor 222Rn concentrations.

    PubMed

    Martín Sánchez, A; de la Torre Pérez, J; Ruano Sánchez, A B

    2014-07-01

    Measurements of radon concentration may not be sufficiently representative for the cumulative total exposure suffered by a person throughout his life. Retrospective dosimetry can help estimating from the direct measurement of 210Po (descendant of 222Rn) implanted on surfaces, because this quantity is related (through the conversion factor) with the mean indoor 222Rn concentration existing in a room for long time. This factor depends on multiple variables. Theoretical models can provide some values. Experiments are tedious and very time consuming. The 210Po activity concentration was measured in mirrors, which were previously exposed to 222Rn concentrations under real environmental conditions. This work deals with the preliminary results in two known places (a room and a cave), which have very different characteristics, in order to show experimentally the large differences found in the values of this factor. PMID:24729559

  1. An Aqueous Symmetric Sodium-Ion Battery with NASICON-Structured Na3 MnTi(PO4 )3.

    PubMed

    Gao, Hongcai; Goodenough, John B

    2016-10-01

    A symmetric sodium-ion battery with an aqueous electrolyte is demonstrated; it utilizes the NASICON-structured Na3 MnTi(PO4 )3 as both the anode and the cathode. The NASICON-structured Na3 MnTi(PO4 )3 possesses two electrochemically active transition metals with the redox couples of Ti(4+) /Ti(3+) and Mn(3+) /Mn(2+) working on the anode and cathode sides, respectively. The symmetric cell based on this bipolar electrode material exhibits a well-defined voltage plateau centered at about 1.4 V in an aqueous electrolyte with a stable cycle performance and superior rate capability. The advent of aqueous symmetric sodium-ion battery with high safety and low cost may provide a solution for large-scale stationary energy storage.

  2. Relating the 3D electrode morphology to Li-ion battery performance; a case for LiFePO4

    NASA Astrophysics Data System (ADS)

    Liu, Zhao; Verhallen, Tomas W.; Singh, Deepak P.; Wang, Hongqian; Wagemaker, Marnix; Barnett, Scott

    2016-08-01

    One of the main goals in lithium ion battery electrode design is to increase the power density. This requires insight in the relation between the complex heterogeneous microstructure existing of active material, conductive additive and electrolyte providing the required electronic and Li-ion transport. FIB-SEM is used to determine the three phase 3D morphology, and Li-ion concentration profiles obtained with Neutron Depth Profiling (NDP) are compared for two cases, conventional LiFePO4 electrodes and better performing carbonate templated LiFePO4 electrodes. This provides detailed understanding of the impact of key parameters such as the tortuosity for electron and Li-ion transport though the electrodes. The created hierarchical pore network of the templated electrodes, containing micron sized pores, appears to be effective only at high rate charge where electrolyte depletion is hindering fast discharge. Surprisingly the carbonate templating method results in a better electronic conductive CB network, enhancing the activity of LiFePO4 near the electrolyte-electrode interface as directly observed with NDP, which in a large part is responsible for the improved rate performance both during charge and discharge. The results demonstrate that standard electrodes have a far from optimal charge transport network and that significantly improved electrode performance should be possible by engineering the microstructure.

  3. Assessment of committed effective dose due to the ingestion of (210)Po and (210)Pb in consumed Lebanese fish affected by a phosphate fertilizer plant.

    PubMed

    Aoun, M; El Samad, O; Bou Khozam, R; Lobinski, R

    2015-02-01

    Ingestion of radionuclides through seafood intake is a one of the sources contributing to the internal effective dose in the human organism. In order to evaluate the internal exposure and potential risks due to (210)Po and (210)Pb associated with fish consumption, these radionuclides were measured in commonly consumed fish species from a clean area and an area subjected to the impact of a Lebanese phosphate fertilizer plant. The highest concentration of (210)Pb was 98.7 Bq/kg fresh weight while (210)Po activity concentrations varied from 3.6 Bq/kg to 140 Bq/kg. A supplementary radiation exposure was detected; the highest committed effective dose due to (210)Po and (210)Pb was found to be 1110 μSv/y and 450 μSv/y, respectively. Moreover, the average mortality and morbidity risks due to the fish consuming were estimated.

  4. Assessment of committed effective dose due to the ingestion of (210)Po and (210)Pb in consumed Lebanese fish affected by a phosphate fertilizer plant.

    PubMed

    Aoun, M; El Samad, O; Bou Khozam, R; Lobinski, R

    2015-02-01

    Ingestion of radionuclides through seafood intake is a one of the sources contributing to the internal effective dose in the human organism. In order to evaluate the internal exposure and potential risks due to (210)Po and (210)Pb associated with fish consumption, these radionuclides were measured in commonly consumed fish species from a clean area and an area subjected to the impact of a Lebanese phosphate fertilizer plant. The highest concentration of (210)Pb was 98.7 Bq/kg fresh weight while (210)Po activity concentrations varied from 3.6 Bq/kg to 140 Bq/kg. A supplementary radiation exposure was detected; the highest committed effective dose due to (210)Po and (210)Pb was found to be 1110 μSv/y and 450 μSv/y, respectively. Moreover, the average mortality and morbidity risks due to the fish consuming were estimated. PMID:25461512

  5. Electrochemical properties of LiCoPO4-thin film electrodes in LiF-based electrolyte solution with anion receptors

    NASA Astrophysics Data System (ADS)

    Fukutsuka, Tomokazu; Nakagawa, Takuya; Miyazaki, Kohei; Abe, Takeshi

    2016-02-01

    Compatibility of LiF + anion receptors/propylene carbonate (PC) electrolyte solution with high potential positive electrode for lithium-ion batteries was examined by cyclic voltammetry. As anion receptors, tripropyl borate (TPB), tris(pentafluorophenyl) borane (TPFPB), and tris(hexafluoroisopropyl) borate (THFIPB) were used. LiCoPO4 thin-film electrodes were prepared by sol-gel method and used as both carbon- and binder-free model electrodes. From cyclic voltammograms, LiCoPO4 showed better cycleability in 0.1 mol dm-3 LiF + 0.1 mol dm-3 THFIPB/PC, however, other anion receptors did not give positive influence. It is indicated that the surface protecting layer from F--THFIPB complex and made LiCoPO4 stable. Electrochemical behavior depending on anion receptors was discussed according to reaction activity of F-.

  6. Three-dimensional seismo-tectonics in the Po Valley basin, northern Italy

    NASA Astrophysics Data System (ADS)

    Turrini, Claudio; Angeloni, Pamela; Lacombe, Olivier; Ponton, Maurizio; Roure, Francois

    2015-04-01

    The Po Valley (Northern Italy) is a composite foreland-foredeep basin caught in between the Southern Alps and Northern Apennine mountain belts. By integrating the 3D structural model of the region and the public earthquake dataset, the three-dimensional seismo-tectonics of the basin is here illustrated for the first time at different scales of observation across the region. Despite the overall uncertainty due to the original data distribution-quality as well as the crustal scale model dimension, the positive correlation that structures and seismicity do show inside and around the study area, validate the performed 3D geo-volume while confirming the related active tectonic framework. The association of structures and earthquakes shows how deformation mainly develops at the front of the Southern Alps and the Northern Apennines, these being, at present, advancing onto their common Po Valley foreland-foredeep domain. Here the hypocentres are essentially concentrated in the eastern sector of the basin. While the 3D picture of a "living" tectonic system is visualized and analysed across the faulted structures of the entire Northern Italy, this study eventually indicates that the methodology can be a powerful tool for the understanding and validation of highly complex seismo-tectonic situations at both regional and local scale.

  7. A High Sensitivity Balloon-Borne Soft Gamma-ray Polarimeter PoGOLite

    NASA Astrophysics Data System (ADS)

    Kamae, Tuneyoshi; Craig, W.; Madejski, G.; Ng, J.; Tajima, H.; Varner, G.; Carlson, P.; Klamra, W.; Pearce, M.; Bjornsson, C.; Larsson, S.; Ryde, F.; Kataoka, J.; Kawai, N.; Mizuno, T.; Takahashi, T.

    2006-09-01

    Development status of a new balloon-borne polarimeter, PoGOLite, will be presented. PoGOLite is designed to detect 10% polarization of a 100 mCrab source in one 6 hour balloon observation in the 25 keV - 100 keV energy range. Its design is based on the well-type phoswich counter technology. Polarization is measured by recording Compton scattering and photo-absorption in an array of 217 phoswich detector cells made of plastic and BGO scintillators, surrounded by active BGO shields. The design has been optimized through 4 rounds of tests at synchrotron beams and a proton beam, and flight model production has began: it can reduce the large background produced by cosmic-ray particles to about 10 mCrab level in most of its energy coverage. Potential systematic instrumental bias to the polarization measurement will be removed by rotating the polarimeter telescope around its axis. We plan to observe northern sky sources including the Crab pulsar/nebula, Cygnus X-1, and Hercules X-1 in the first flight scheduled in 2009. Our future plans include long duration balloon flights from Sweden to North America, and launching within a few weeks of gamma-ray flare detection from jet sources such as Mkn 501 by GLAST.

  8. 210Po and 210Pb as Tracers of Particle Cycling and Resuspension in a Dynamic Freshwater System: Case Study from the Clinton River, Southeast Michigan

    NASA Astrophysics Data System (ADS)

    Mudbidre, R.; Baskaran, M. M.; Schweitzer, L.

    2013-12-01

    Polonium-210 and 210Pb are constantly delivered to the surface waters through atmospheric deposition with a 210Po/210Pb activity ratio (AR) of < 0.10. Freshly produced suspended particles in surface waters are ';tagged' with this ratio which tends to grow towards the secular equilibrium value of 1.0. This disequilibrium between 210Po and 210Pb in freshwater system with a relatively short hydrological residence time can be utilized to quantify sediment resuspension rates and to investigate the extent of recycling of sedimentary particulate matter. From the measurements of 210Po and 210Pb in particulate matter collected in sediment traps and surficial bottom sediments at 5 different sites in the Clinton River in southeast Michigan over a period of 6 months (April - September, 2005) and subsequent modeling of these data, we report the following: i) The direct atmospheric deposition of 210Po and 210Pb collected in the sediment trap materials accounted for 1% and 0.1%, respectively, of the total deposited in the sediment trap; ii) The ranges and mean values of the 210Po and 210Pb in the sediment trap material and bottom sediments are comparable, with near identical 210Po/210Pb ratios, indicating that most of the trapped 210Po and 210Pb were delivered by the resuspension of bottom sediments; iii) The particle residence times varied from 0.3 to 4 days for 210Pb and 0.9 to 13.4 days for 210Po; and iv) The sediment resuspension rates calculated via single box model approach yielded resuspension rates ranging from 0.2 to 14.2 g cm-2 yr-1 using 210Pb and 0.1 to 1.0 g cm-2 yr-1 using 210Po. We propose that the distribution of 210Bi (and 210Bi/210Pb) would provide better insight on particle cycling in short-time scales and a brief discussion will be presented on the utility of 210Bi/210Pb ratio as a powerful tool for short-term particle cycling and as tracers of POC, PON export studies in deeper freshwater lakes.

  9. Using Na3PO4 to Enhance In vitro Animal Models of Aortic Valve Calcification

    PubMed Central

    Lerman, Daniel Alejandro; Prasad, Sai; Alotti, Nasri

    2016-01-01

    Background/Objectives The pathogenesis of calcific aortic valvular disease (CAVD) involves an active inflammatory process of valvular interstitial cells (VICs) characterized by the activation of specific osteogenic signaling pathways and apoptosis. This process can be studied by analyzing certain molecular markers and gene expression pathways of spontaneous calcification. The purpose of our study is to investigate the role of sodium phosphate (Na3PO4) as a calcification promoter, with the aim of improving in vitro animal models for testing potential calcification inhibitors. Materials and Methods VICs were extracted from 6 healthy 6-month-old fresh porcine hearts by serial collagenase digestion. Quantitative polymerase chain reaction (qPCR) was used to quantify trans-differentiation of genes of interest during spontaneous calcification of VICs. Spontaneous calcification of VICs was increased by adding Na3PO4 (3 mM, pH 7.4). The degree of calcification was estimated by Alizarin Red staining for calcium deposition, and Sirius Red staining for collagen. Colorimetric techniques were used to determine calcium and collagen deposition quantitatively. Additionally, the enzymatic activity of alkaline phosphatase (ALP) was measured by a kinetic assay. For statistical analysis we used SPSS and Microsoft Office Excel 2013. Results Porcine VICs calcify spontaneously with demonstrable calcium and collagen deposition. In this study we observed an increase of calcium and collagen deposition from day 0 to day 14 (calcium: 376%; P<0.001, collagen: 3553%; P<0.001). qPCR analysis of mRNA by day 14 showed the following results: α-actin, a marker of myoblast phenotype, was increased to 1.6-fold; P<0.001. Runx2, an osteoblast marker, rose to 1.3 fold; P<0.05, TGF-β, a promoter of osteogenesis, increased to 3.2-fold; P<0.001, and RhoA, a regulator of nodular formation in myoblasts, increased to 4.5-fold; P<0.001, compared to their levels at day 0. RANKL mRNA and calponin did not change

  10. Energetics of phosphate frameworks containing zinc and cobalt: NaZnPO{sub 4}, NaH(ZnPO{sub 4}){sub 2}, NaZnPO{sub 4}.H{sub 2}O, NaZnPO{sub 4}.4/3 H{sub 2}O, and NaCo{sub x}Zn{sub 1-x}PO{sub 4}.4/3 H{sub 2}O

    SciTech Connect

    Le, So-Nhu; Navrotsky, Alexandra

    2007-09-15

    Differential scanning calorimetry and high temperature oxide melt solution calorimetry were used to study the enthalpy of the {alpha}-{beta} phase transformation of NaZnPO{sub 4} and enthalpies of formation of {alpha}-NaZnPO{sub 4}, NaH(ZnPO{sub 4}){sub 2}, NaZnPO{sub 4}.H{sub 2}O, and NaCo{sub x}Zn{sub 1-x}PO{sub 4}.4/3 H{sub 2}O (x=0, 0.1, 0.2, 0.3). The enthalpies of formation from the oxides of cobalt substituted in NaZnPO{sub 4}.4/3 H{sub 2}O do not depend on cobalt content, confirming similar acid-base interactions for Zn-PO{sub 4} and Co-PO{sub 4}. While water molecules stabilize zinc phosphate frameworks through solvating a cation or forming extra hydrogen bonds, the partial substitution of water for sodium oxide to form NaH(ZnPO{sub 4}){sub 2} represents the formation of an acidic compound with weaker acid-base interactions and less exothermic enthalpy of formation from oxides than Na{sub 2}(ZnPO{sub 4}){sub 2}. - Graphical abstract: Relative stability of NaZnPO{sub 4} dense phases, open frameworks, and hydrated frameworks. Enthalpy of interaction between water and NaZnPO{sub 4} frameworks is presented by reaction: NaZnPO{sub 4} (cr, open framework) + nH{sub 2}O (l) {yields} NaZnPO{sub 4}.nH{sub 2}O (cr, hydrated framework)

  11. 210Po concentration analysis on tobacco and cigarettes in Malaysia

    NASA Astrophysics Data System (ADS)

    Azman, Muhammad Azfar; Rahman, Irman Abdul; Yasir, Muhammad Samudi

    2013-05-01

    Tobacco or better known as the cigarette was smoked since ages. Although many efforts had been made by the Ministry of Health to prevent or reduce the cigarette problem, the smokers still consider that cigarette are not harmful to health. This work is conducted to study the concentration of radionuclides alpha in tobacco and tobacco products in Malaysia. The radionuclide sought in this study is 210Po which is an alpha emitter. The sample used are tobacco and cigarettes, the tobacco samples were taken from tobacco farms in Malaysia while the sample branded cigarettes Marlboro and Gudang Garam were bought in the supermarket. The objectives of this study are to determine the concentration of radionuclides 210Po in tobacco and tobacco products as well as to estimate the radioactivity doses contributing to the smokers in Malaysia. The results for Marlboro cigarettes and Gudang Garam were found to be on the average radionuclide concentration of 210Po is 13.3 mBq/g (Marlboro cigarettes) and 11.9 mBq/g (Gudang Garam). From the total concentration of the cigarette, the estimated annual contribution dose to smokers for every 20 cigarettes smoked per day are 111.9 ± 14.7 μSv/year for Marlboro cigarettes and 100.2 ± 3.3 μSv/year for Gudang Garam cigarettes. The average concentration of radionuclides for tobacco leaf tobacco for each area taken is 3.6 mBq / g for Bachok, 2.4 mBq / g for Tumpat and 3.1 mBq / g for Semerak district.

  12. 210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

    USGS Publications Warehouse

    Swarzenski, Peter W.; McKee, Brent A.; Sorensen, Kai; Todd, James F.

    1999-01-01

    Vertical profiles of dissolved and particulate 210Po and 210b were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po and 210Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both 210Po and 210Pb are highly enriched at the O2/H2S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in 210Po, 210Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated.

  13. 210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

    USGS Publications Warehouse

    Swarzenski, Peter W.; McKee, Brent A.; Sorenson, Kai; Todd, James F.

    1999-01-01

    Vertical profiles of dissolved and particulate 201Po and 210Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po and 210Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both 210Po and 210Pb are highly enriched at the O2/H2S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in 210Po and 210Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated.

  14. Atomic Mass and Nuclear Binding Energy for Po-281 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-281 (Polonium, atomic number Z = 84, mass number A = 281).

  15. Atomic Mass and Nuclear Binding Energy for Po-277 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-277 (Polonium, atomic number Z = 84, mass number A = 277).

  16. Atomic Mass and Nuclear Binding Energy for Po-270 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-270 (Polonium, atomic number Z = 84, mass number A = 270).

  17. Atomic Mass and Nuclear Binding Energy for Po-284 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-284 (Polonium, atomic number Z = 84, mass number A = 284).

  18. Atomic Mass and Nuclear Binding Energy for Po-276 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-276 (Polonium, atomic number Z = 84, mass number A = 276).

  19. Atomic Mass and Nuclear Binding Energy for Po-269 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-269 (Polonium, atomic number Z = 84, mass number A = 269).

  20. Atomic Mass and Nuclear Binding Energy for Po-272 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-272 (Polonium, atomic number Z = 84, mass number A = 272).

  1. Atomic Mass and Nuclear Binding Energy for Po-266 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-266 (Polonium, atomic number Z = 84, mass number A = 266).

  2. Atomic Mass and Nuclear Binding Energy for Po-280 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-280 (Polonium, atomic number Z = 84, mass number A = 280).

  3. Atomic Mass and Nuclear Binding Energy for Po-274 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-274 (Polonium, atomic number Z = 84, mass number A = 274).

  4. Atomic Mass and Nuclear Binding Energy for Po-273 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-273 (Polonium, atomic number Z = 84, mass number A = 273).

  5. Atomic Mass and Nuclear Binding Energy for Po-271 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-271 (Polonium, atomic number Z = 84, mass number A = 271).

  6. An emergency bioassay method for (210)Po in urine.

    PubMed

    Guérin, Nicolas; Dai, Xiongxin

    2015-09-01

    A rapid method was developed to efficiently measure (210)Po in urine samples in an emergency situation. Polonium-210 in small urine samples (10 mL) was spontaneously deposited on a stainless steel disc in 1 M HCl at room temperature for 4 h in a polyethylene bottle. The metallic disc was then counted for 4 h by alpha spectrometry. The developed method allowed the preparation of large sample batch in a short time. The method meets the requirements for an emergency bioassay procedure.

  7. Atomic Mass and Nuclear Binding Energy for Po-278 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-278 (Polonium, atomic number Z = 84, mass number A = 278).

  8. Atomic Mass and Nuclear Binding Energy for Po-268 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-268 (Polonium, atomic number Z = 84, mass number A = 268).

  9. Atomic Mass and Nuclear Binding Energy for Po-282 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-282 (Polonium, atomic number Z = 84, mass number A = 282).

  10. Atomic Mass and Nuclear Binding Energy for Po-279 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-279 (Polonium, atomic number Z = 84, mass number A = 279).

  11. Atomic Mass and Nuclear Binding Energy for Po-267 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-267 (Polonium, atomic number Z = 84, mass number A = 267).

  12. Atomic Mass and Nuclear Binding Energy for Po-283 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-283 (Polonium, atomic number Z = 84, mass number A = 283).

  13. Atomic Mass and Nuclear Binding Energy for Po-275 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-275 (Polonium, atomic number Z = 84, mass number A = 275).

  14. Small earth station antenna synthesized by a direct PO method

    NASA Astrophysics Data System (ADS)

    Schlobohm, Bernd; Arndt, Fritz

    1990-11-01

    An efficient direct numerical synthesis method for dual offset reflector antennas is described which is based on the physical optics (PO) procedure. The method involves an evolution-strategy optimization algorithm in order to shape both reflectors directly, so as to generate the desired far field with prescribed criteria. The efficiency of the design method is demonstrated by the example of a compact Gregorian dual-offset earth-station antenna with high offset angle (70 deg) and small subreflector size (13 lambda); 75 percent antenna efficiency, 38 dB cross-polarization attenuation, and a very low sidelobe behavior of about 23-25 log theta dBi are achieved.

  15. Hydrogen--deuterium exchange in KD2PO4

    SciTech Connect

    Kucheyev, S O; Felter, T E; Siekhaus, W J; Nelson, A J; Hamza, A V

    2003-11-04

    Depth profiles of {sup 1}H and {sup 2}D in rapidly-grown KD{sub 2x}H{sub 2(1-x)}PO{sub 4} (DKDP) single crystals are studied by elastic recoil detection analysis. Results show that, at ambient conditions, deuteration in the first {approx} 500 nm from the sample surface significantly decreases within the first several days after D{sub 2}O surface polishing. This effect is attributed to the deuterium-hydrogen exchange. The effective diffusion coefficient of this process is strongly dependent on both the degree of deuteration and sample growth conditions. Physical mechanisms of the D/H exchange are discussed.

  16. An emergency bioassay method for (210)Po in urine.

    PubMed

    Guérin, Nicolas; Dai, Xiongxin

    2015-09-01

    A rapid method was developed to efficiently measure (210)Po in urine samples in an emergency situation. Polonium-210 in small urine samples (10 mL) was spontaneously deposited on a stainless steel disc in 1 M HCl at room temperature for 4 h in a polyethylene bottle. The metallic disc was then counted for 4 h by alpha spectrometry. The developed method allowed the preparation of large sample batch in a short time. The method meets the requirements for an emergency bioassay procedure. PMID:26115206

  17. Micro-Raman observation on the H2PO4- association structures in a supersaturated droplet of potassium dihydrogen phosphate (KH2PO4)

    NASA Astrophysics Data System (ADS)

    Syed, Kamran Ajmal; Pang, Shu-Feng; Zhang, Yun; Zhang, Yun-Hong

    2013-01-01

    The efflorescence of an individual KH2PO4 droplet on Teflon substrate was investigated by micro-Raman spectroscopy. With the decrease of relative humidity (RH) from 98.0% to 73.0%, the KH2PO4 droplet lost water gradually and entered into supersaturated state, which was reflected by the area ratio between the water stretching band to the sum of νs-PO2 and νs-P(OH)2 bands of the H2PO4- (A_{H_2 O} /(A_{(ν _s -PO_2 } {+ A}_{ν _s -P(OH)_2 {)}} {)}). In 1.0 mol l-1 KH2PO4 solution, the νs-P(OH)2 and νs-PO2 bands appeared at 877 and 1077 cm-1. In the KH2PO4 droplet, the two bands shifted to 894 and 1039 cm-1 at 98.0% RH, to 899 and 1031 cm-1 at 89.6% RH, and then to 904 and 997 cm-1 at 73.0% RH. Moreover, the aggregation process between the H2PO4- ions was observed from the spectral characteristic of the νs-P(OH)2 band in the concentration process, including the transitions of the H2PO4- ions from monomer in bulk solutions (0.5-1.0 mol l-1) to possible dimers at 98.0% RH and then further to oligomers in the droplet with the RH decrease, which were indicated by the blueshift of the νs-P(OH)2 band and its full width at half-height as a function of the RH. When the RH reached at 72.0%, the anhydrous crystal was obtained. A strong peak appeared at 928 cm-1, implying that the four oxygen atoms of the H2PO4- were all hydrogen bonding through the bridge hydrogen atoms to get the extensive hydrogen-bonded network structure of the H2PO4- association, leading to the symmetric increase of the H2PO4- ion from C2v in dilute solution to quasi-Td in the anhydrous crystal.

  18. Degassing dynamics at Mount Etna inferred from radioactive disequilibria (210Pb-210Bi-210Po) in volcanic gases

    NASA Astrophysics Data System (ADS)

    Terray, Luca; Gauthier, Pierre-Jean; Salerno, Giuseppe; La Spina, Alessandro; Giammanco, Salvatore; Sellitto, Pasquale; Briole, Pierre

    2016-04-01

    Volcanic gases are significantly enriched in the last short-half-life radionuclides of the 238U series, namely the so-called Radon daughters 210Pb, 210Bi and 210Po. Because of their contrasted volatilities, these isotopes are strongly fractionated upon degassing, which gives rise to significant radioactive disequilibria between them in the gas phase. These disequilibria carry precious information on shallow degassing processes beneath active volcanoes: they remarkably constrain the magma residence time in the degassing reservoir and the duration of gas extraction from magma to surface. On Mount Etna (Sicily), where the study of these disequilibria was initiated thirty years ago (Lambert et al., EPSL, 1985-86), no measurement of 210Pb, 210Bi and 210Po in the gases has been performed for the last twenty years. Here we present new 210Pb-210Bi-210Po radioactive disequilibria measurements in volcanic plume gases of Mount Etna. Samples were collected in the bulk diluted plume at kilometric distance from the summit area during the May 2015 eruption, then in more concentrated plumes arising from each summit crater of Etna during quiescent degassing in July 2015. We found values of (210Bi/210Pb) = 7.0 ± 0.3 and (210Po/210Pb) = 80 ± 6 during both periods. These results suggest that 210Pb, 210Bi and 210Po are not significantly fractionated during the transport of the plume from the crater rim to close-downslope sites (<1 km). None of the previous degassing models (Lambert et al., EPSL, 1985-86 ; Gauthier et al., JVGR, 2000) satisfactorily explain measured activity ratios. We propose here a new degassing model based on the previous conceptualization designed for basaltic open-conduit volcanoes, like Stromboli. This model considers extreme Radon enrichments in volcanic gases as a source of 210Pb atoms produced by radioactive decay of 222Rn within gas bubbles travelling to surface. We constrain a magma residence time of 470 ± 170 days and an extraction time of the gases of 4

  19. Formation and emission of volatile polonium compound by microbial activity and polonium methylation with methylcobalamin.

    PubMed

    Momoshima, N; Song, L X; Osaki, S; Maeda, Y

    2001-07-15

    We observed biologically mediated emission of Po from culture solution inoculated sea sediment extract and incubated under natural light/dark cycle condition or dark condition the emitted Po compound would be lipophilic because of effective collection in organic solvent. Sterilization of the culture medium with antibiotics or CuSO4 completely suppressed growth of microorganisms and resulted in no emission of Po, indicating biological activity of microorganisms is responsible for formation and emission of volatile Po compound. Po emission also occurred when seawater was used as a culture medium. Our finding indicates a possibility of biotic source for atmospheric Po in the environment, which has been believed to be originated from abiotic sources. We compared emission behavior of Po and S in the culture experiments, the elements belong to XVI group in the Periodical Table, and consider that their emission mechanisms involved would be different though the emission of both elements is supported by biological activity of microorganisms. One of the chemical forms of S emitted was confirmed to be dimethyl sulfide (DMS) but that of Po is not known. Methylation experiments of Po with methylcobalamin demonstrated a formation and emission of volatile Po compound. The methylation of Po with methylcobalamin might be related to the observed Po emission in the culture experiments.

  20. Nickel (II) incorporated AlPO-5 modified carbon paste electrode for determination of thioridazine in human serum.

    PubMed

    Amiri, Mandana; Sohrabnezhad, Shabnam; Rahimi, Azad

    2014-04-01

    In this approach, synthesis of nickel (II) incorporated aluminophosphate (NiAlPO-5) was performed by using hydrothermal method. The diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques were applied in order to characterize synthesized compounds. The NiAlPO-5 was used as a modifier in carbon paste electrode for the selective determination of thioridazine which is an antidepressant drug. This research is the first example of an aluminophosphate being employed in electroanalysis. The effective catalytic role of the modified electrode toward thioridazine oxidation can be attributed to the electrocatalytic activity of nickel (II) in the aluminaphosphate matrix. In addition, NiAlPO-5 has unique properties such as the high specific surface area which increases the electron transfer of thioridazine. The effects of varying the percentage of modifier, pH and potential sweep rate on the electrode response were investigated. Differential pulse voltammetry was used for quantitative determination as a sensitive method. A dynamic linear range was obtained in the range of 1.0×10(-7)-1.0×10(-5)mol L(-1). The determination of thioridazine in real samples such as commercial tablets and human serum was demonstrated.

  1. Natural and anthropogenic variations in the Po river waters (northern Italy): insights from a multi-isotope approach.

    PubMed

    Marchina, Chiara; Bianchini, Gianluca; Knoeller, Kay; Natali, Claudio; Pennisi, Maddalena; Colombani, Nicolò

    2016-12-01

    Po is the main Italian river and the δ(18)O and δ(2)H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca-HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ(13)CDIC and δ(34)SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ(15)NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO(-) 3 concentration. This implies that aquifers' pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination. PMID:26982695

  2. Natural and anthropogenic variations in the Po river waters (northern Italy): insights from a multi-isotope approach.

    PubMed

    Marchina, Chiara; Bianchini, Gianluca; Knoeller, Kay; Natali, Claudio; Pennisi, Maddalena; Colombani, Nicolò

    2016-12-01

    Po is the main Italian river and the δ(18)O and δ(2)H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca-HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ(13)CDIC and δ(34)SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ(15)NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO(-) 3 concentration. This implies that aquifers' pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.

  3. Crystal structure and ionic conductivity of the new cobalt polyphosphate NaCo(PO3)3

    NASA Astrophysics Data System (ADS)

    Ben Smida, Youssef; Guesmi, Abderrahmen; Georges, Samuel; Avdeev, Maxim; Zid, Mohamed Faouzi

    2016-02-01

    Polycrystalline sample of sodium cobalt triphosphate NaCo(PO3)3 was obtained by solid-state reaction and characterized by X-ray powder diffraction. The title compound is isostructural to NaZn(PO3)3 and its structure was refined by the Rietveld refinement in the cubic system, space group Pa 3 ̅, with a=14.2484(4) Å. The obtained structural model is supported by bond valence sum (BVS) and charge distribution (CD) methods. The structure is described as a three-dimensional open-anionic framework built up of corner-sharing CoO6 and PO4 polyhedra with interconnecting channels along the 3-axis, in which the Na+ cations are located. The ionic conductivity measurements are performed on pellets with relative density of 84%. The electrical conductivity is 1.01×10-5 S cm-1 at 480 °C and the activation energy deduced from the slope is 1.1 eV. The correlation between crystal structure and ionic conductivity was studied by the means of the bond-valence-site-energy (BVSE) model. The main result is that sodium transport is made mainly via Na2 and Na3 sites.

  4. Energy transfer from PO excited states to alkali metal atoms in the phosphorus chemiluminescence flame

    PubMed Central

    Khan, Ahsan U.

    1980-01-01

    Phosphorus chemiluminescence under ambient conditions of a phosphorus oxidation flame is found to offer an efficient electronic energy transferring system to alkali metal atoms. The lowest resonance lines, 2P3 / 2,½→2S½, of potassium and sodium are excited by energy transfer when an argon stream at 80°C carrying potassium or sodium atoms intersects a phosphorus vapor stream, either at the flame or in the postflame region. The lowest electronically excited metastable 4IIi state of PO or the (PO[unk]PO)* excimer is considered to be the probable energy donor. The (PO[unk]PO)* excimer results from the interaction of the 4IIi state of one PO molecule with the ground 2IIr state of another. Metastability of the donor state is strongly indicated by the observation of intense sensitized alkali atom fluorescence in the postflame region. PMID:16592925

  5. The source of first-cycle capacity loss in LiFePO 4

    NASA Astrophysics Data System (ADS)

    Andersson, A. S.; Thomas, J. O.

    The electrochemical extraction of lithium from solid-state synthesised LiFePO 4 has been studied by neutron powder diffraction. A "coffee-bag" type cell of configuration PO 4> has been charged to 4.1 V, dismantled in a glovebox, and the composite cathode powder sample scraped from the current collector. Two-phase Rietveld refinement gave a triphylite (LiFePO 4) to heterosite (FePO 4) phase-ratio of 18:82. In the absence of significant absorption effects, this ratio is a true representation of the conversion of LiFePO 4 to FePO 4. Possible mechanisms for lithium extraction/insertion during the first-cycle are discussed.

  6. Quantitative palaeodrainage analysis in the Pleistocene of the Po Plain (Italy)

    NASA Astrophysics Data System (ADS)

    Vezzoli, G.; Garzanti, E.; Sciunnach, D.

    2009-04-01

    During the Pleistocene, Po Plain deposits recorded repeated waxing and waning of Alpine ice caps, and thus provide an excellent opportunity to investigate the interactions between pronounced climatic fluctuations and background tectonic activity (Scardia et al., 2006), resulting in frequent changes of drainage patterns. A high-resolution Pleistocene stratigraphy, with a complete sedimentological, paleontological, petrographic-mineralogical, magneto-stratigraphic, and seismic data base, was recently obtained from eleven continuous cores drilled in the Lombardy Po Plain north of the Po River (ENI and Regione Lombardia, 2002). In the present study we focus on two cores in the proximal (Cilavegna) and distal plain (Pianengo), which best exemplify the drastic change in sedimentary systems and drainage patterns associated with the onset of major Pleistocene glaciations in the Alps (˜870ky; Muttoni et al., 2003). This climatic event is recorded by a regional unconformity (named R-unconformity by Muttoni et al., 2003), traced all across the Po Basin and encountered at -81 m depth in the Pianengo Core and at -98 m depth in the Cilavegna Core. The Cilavegna Core consists of metamorphiclastic floodplain sediments, capped by the R-unconformity and overlain by quartzofeldspathic braidplain deposits. The Pianengo Core consists of metamorphiclastic deltaic to floodpain sediments, capped by the R-unconformity and overlain by alluvial-fan gravels rich in carbonate pebbles; another unconformity at -39 m depth is overlain by metamorphiclastic braidplain deposits. Our quantitative approach to paleodrainage analysis is based on comprehensive information obtained from modern settings (Garzanti et al., 2004; 2006). End-member modelling and similarity analysis allows us to objectively compare detrital modes from modern and ancient deposits, and to reconstruct the evolution of sediment pathways through geologic time (Vezzoli and Garzanti 2009). The Cilavegna Core documents stepwise south

  7. Crystal structure and Temperature-Dependent Luminescence Characteristics of KMg4(PO4)3:Eu2+ phosphor for White Light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Liu, Yangai; Mei, Lefu; Liu, Haikun; Fang, Minghao; Huang, Zhaohui

    2015-04-01

    The KMg4(PO4)3:Eu2+ phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg4(PO4)3:Eu2+ were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu2+ in the KMg4(PO4)3 host was determined to be 1mol% and the quenching mechanism was certified to be the dipole-dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24eV. Upon excitation at 365nm, the internal quantum efficiency of the optimized KMg4(PO4)3:Eu2+ was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg4(PO4)3:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg4(PO4)3:Eu2+ is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs).

  8. In vitro cell irradiation systems based on 210Po alpha source: construction and characterisation

    NASA Technical Reports Server (NTRS)

    Szabo, J.; Feher, I.; Palfalvi, J.; Balashazy, I.; Dam, A. M.; Polonyi, I.; Bogdandi, E. N.

    2002-01-01

    One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed. c2002 Elsevier Science Ltd. All rights reserved.

  9. Numerical modeling of Po-218 deposition in a physiologically realistic lung bifurcation model

    NASA Astrophysics Data System (ADS)

    Mously-Soroujy, Khalid Ahmad

    Experimental data for lung bifurcations reveals complex geometries and distinct asymmetrical characteristic, which affects the localized distribution of particles deposited in the lung. This study is based on recently published numerical results for a symmetric physiological realistic bifurcation geometry Heistracher and Hofmann (1995) which has been extended here to the case of a asymmetric geometry. The asymmetric PRB model was used to study the flow field and the deposition of ultrafine particles for inspiratory and expiratory conditions. In the present study, we investigated the effect of different flow rates, representing human activity and deposition of different ultrafine particles representing radon daughter (Po-218), in the PRB model. Numerical results were compared with the limited available experimental and numerical data. The fluid dynamic computer program FIDAP was used for this purpose.

  10. Preparation and photocatalytic degradation performance of Ag3PO4 with a two-step approach

    NASA Astrophysics Data System (ADS)

    Li, Jiwen; Ji, Xiaojing; Li, Xian; Hu, Xianghua; Sun, Yanfang; Ma, Jingjun; Qiao, Gaowei

    2016-05-01

    Ag3PO4 photocatalysts were prepared via two and one-step through a facile ion-exchange route. The photocatalysts were then characterized through powder X-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated on the basis of the photocatalytic degradation of methyl orange (MO) and methylene blue (MB) under solar irradiation. The MO degradation rate of the Photocatalyst synthesized by the two-step ion-exchange route was 89.18% in 60 min. This value was four times that of the Photocatalyst synthesized by the one-step approach.The MB degradation rate was 97% in 40 min. After six cycling runs were completed, the MO degradation rate was 73%

  11. Harmful Algae Records in Venice Lagoon and in Po River Delta (Northern Adriatic Sea, Italy)

    PubMed Central

    Bilaničovà, Dagmar; Marcomini, Antonio

    2014-01-01

    A detailed review of harmful algal blooms (HAB) in northern Adriatic Sea lagoons (Po River Delta and Venice lagoon) is presented to provide “updated reference conditions” for future research and monitoring activities. In the study areas, the high mollusc production requires the necessity to identify better methods able to prevent risks for human health and socioeconomical interests. So, an integrated approach for the identification and quantification of algal toxins is presented by combining microscopy techniques with Liquid Chromatography coupled with High Resolution Time of Flight Mass Spectrometry (HPLC-HR-TOF-MS). The method efficiency was first tested on some samples from the mentioned coastal areas, where Dinophysis spp. occurred during summer in the sites directly affected by seawaters. Although cell abundance was always <200 cells/L, the presence of Pectenotoxin-2 (PTX2), detected by HPLC-HR-TOF-MS, indicated the potential release of detectable amounts of toxins even at low cell abundance. PMID:24683360

  12. Redetermination of β-Ba(PO3)2.

    PubMed

    Weil, Matthias

    2014-02-01

    In comparison with the previous structure determination of the β-modification of barium catena-polyphosphate that was based on Weissenberg film data [Grenier et al. (1967 ▶). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24-31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P-O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4 tetra-hedra. The Ba(2+) cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba-O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination.

  13. Assessment of river Po sediment quality by micropollutant analysis.

    PubMed

    Camusso, Marina; Galassi, Silvana; Vignati, Davide

    2002-05-01

    Trace metals, PCB congeners and DDT homologues were determined in composite sediment samples collected from 10 representative sites along the river Po in two separate seasons. The aim was to identify the most anthropogenically impacted areas for future monitoring programmes and to aid development of Italian sediment quality criteria. The surface samples were collected during low flow conditions. Trace metal concentrations were assayed by electrothermal (Cd, Co, Cr, Cu, Ni, Pb), flame (Fe, Mn, Zn) or hydride generation (As) atomic absorption spectrometry after microwave assisted acid digestion. Hg was determined on solid samples by automated analyser. Organic microcontaminants were determined by gas-chromatography with 63Ni electron capture detector after Soxhlet extraction. Concentrations of trace metals, total PCB and DDT homologues showed two distinct peaks at the sites immediately downstream of Turin and Milan, respectively, and in each case decreased progressively further downstream. Principal component analysis identified three major factors (from a multi-dimensional space of 35 variables) which explained 85-90% of the total observed variance. The first and second factors corresponded to anthropogenic inputs and geological factors on sediment quality; the third included seasonal processes of minor importance. Sediment quality assessment identified Cd, Cu, Hg, Pb, Zn and organic microcontaminants as posing the most serious threats to river sediment quality. A reference site within the Po basin provided useful background values. Moderate pollution by organochlorine compounds was ascribed both to local sources and to atmospheric deposition. PMID:12153015

  14. Novel synergistic 0.9LiMn0.9Fe0.1PO4·0.1Na3V2(PO4)2F3/C nano-hybrid cathode with enhanced electrochemical performance for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhijian; Hu, Guorong; Cao, Yanbing; Duan, Jianguo; Du, Ke; Peng, Zhongdong

    2016-01-01

    The nanostructured 0.9LiMn0.9Fe0.1PO4·0.1Na3V2(PO4)2F3/C composites are successfully synthesized by a facile solvothermal method followed by mechanical activation and subsequent carbonthermal reduction process. Behaviours of bi-phase co-existence and element mutual-substitution have been investigated by XRD, TEM/EDX and FTIR. The result shows that the composites have dual phase boundaries including the semi-coherent phase interface and incoherent phase interface, as well as the advantage of Na3V2(PO4)2F3 acting as ionic conductor. Due to the multifunctional phase and (Mn,Fe)-V mutual doping as well as nano-carbon continual conducting network, enhanced Li+ migration and charge transfer of nano-hybrid is obtained. Compared with pristine one, the 0.9LiMn0.9Fe0.1PO4·0.1Na3V2(PO4)2F3/C composites exhibit high rate capability and cycling ability, showing 125.5, 106.4 mAh g-1 at 1.0 C, 3.0 C at room temperature, respectively, with high capacity retention up to 93.9% after 600th at 2 C.

  15. The importance of acid digestion of urine prior to spontaneous deposition of 210Po.

    PubMed

    Fellman, A; Ralston, L; Hickman, D; Ayres, L; Cohen, N; Spitz, H; Robinson, B

    1989-10-01

    Historically, radiochemical analysis of 210Po in urine has used spontaneous deposition of the nuclide directly from raw urine onto a suitable metal disc. Consequently, the urinary excretion fraction for Po in some current metabolic and dosimetric models is based on studies which inherently assume that metabolized (i.e., filtered out of the blood by the kidneys) 210Po is plated with the same efficiency as tracer 210Po which has been added to urine samples. Urine samples collected after intravenous administration of 210Po citrate to two species of nonhuman primates were divided and simultaneously analyzed via two methods: the historical procedure of plating 210Po from raw urine for one sample and a method which includes the addition of 208Po tracer and sample digestion with concentrated HNO3 prior to 210Po deposition for the other sample. A more significant amount of 210Po was consistently recovered when the urine was wet ashed then when it was not wet ashed. A temporal relationship was found to describe the change in the ratio of the deposition recoveries for the two methods. Possible mechanisms for this phenomenon and its dosimetric implications are discussed. PMID:2507478

  16. Binary and ternary Po-containing molecules relevant for LBE cooled reactors at operating temperature

    NASA Astrophysics Data System (ADS)

    Van Yperen-De Deyne, Andy; Rijpstra, Kim; Waroquier, Michel; Van Speybroeck, Veronique; Cottenier, Stefaan

    2015-03-01

    Quantum-chemical calculations at several levels of theory were used to assess the stability at different temperatures of a set of 13 binary and ternary Po-containing molecules that could possibly be formed in an environment with lead, bismuth, oxygen and water. The conclusions are that especially PoPb, PbPoO and PoOH and to a lesser extent Po2 and PoO are stable. These small molecules are therefore likely to be found near the Lead-Bismuth eutectic (LBE) coolant at operational temperatures in a heavy liquid metal cooled fission reactor. In contrast, Po3 and PoBi are unlikely to be present under the assumed conditions. Several stability criteria, such as the dissociation into free atoms or into molecular fragments at realistic Po-concentrations or in the thermodynamic limit are discussed at different temperatures. The results obtained with a medium level of theory (Density Functional Theory, PBE0 with relativistic effective core potentials) show good qualitative correspondence with calculations performed at a much higher level of theory (Multi Reference Configuration Interaction, with spin-orbit coupling and scalar relativistic Hamiltonian).

  17. Role of graphene on the surface chemical reactions of BiPO4-rGO with low OH-related defects.

    PubMed

    Gao, Erping; Wang, Wenzhong

    2013-11-21

    Graphene has been widely introduced into photocatalysis to enhance photocatalytic performance due to its unique physical and chemical properties. However, the effect of graphene on the surface chemical reactions of photocatalysis has not been clearly researched, which is important for photocatalysis because photocatalytic reactions ultimately occur on the catalyst surface. Herein, a two-step solution-phase reaction has been designed to synthesize quasi-core-shell structured BiPO4-rGO cuboids and the role of graphene on the surface chemical reactions was investigated in detail. It was found that the introduced graphene modified the process and the mechanism of the surface chemical reactions. The change mainly originates from the interaction between graphene and the adsorbed O2 molecule. Due to the electron transfer from graphene to adsorbed O2, graphene could tune the interfacial charge transport and efficiently activate molecular oxygen to form O2˙(-) anions as the major oxidation species instead of ˙OH. In addition, the two-step synthesis approach could efficiently suppress the formation of OH-related defects in the lattice. As a result, the BiPO4-rGO composite exhibited superior photocatalytic activity to BiPO4 and P25, about 4.3 times that of BiPO4 and 6.9 times that of P25. PMID:24056863

  18. Shell-model description of sup 211 Bi(. beta. sup minus ) sup 211 Po and sup 211 At(EC) sup 211 Po and the spectroscopy of sup 211 Po

    SciTech Connect

    Warburton, E.K. )

    1991-10-01

    A recent treatment of first-forbidden {beta}{sup {minus}} decay in the lead region is extended to {beta}{sup +} decay and electron capture. The modified Kuo-Herling shell-model interaction recently described by Warburton and Brown is used to calculate wave functions and observables for {sup 211}Po. The log{ital f}{sub 0}{ital t} values for the {sup 211}Bi(9/2{sup {minus}}){r arrow}{sup 211}Po(9/2{sup +}) {beta}{sup {minus}} transition and the electron capture of {sup 211}At(9/2{sup {minus}}) into the 9/2 {sub 1}{sup +} and 11/2 {sub 1}{sup +} states of {sup 211}Po are predicted to be 6.008, 5.891, and 5.850 as compared to the experimental values of 6.026{plus minus}0.017, 5.960{plus minus}0.008, and 5.831{plus minus}0.090, respectively. The wave functions and spectrum of {sup 211}Po are calculated in the Kuo-Herling model space. The yrast spectrum is presented for comparison to anticipated results from fusion-evaporation reaction studies. The experimental {sup 210}Po({ital d},{ital p}){sup 211}Po spectroscopic factors are quite accurately reproduced.

  19. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism.

    PubMed

    Seifitokaldani, Ali; Gheribi, Aïmen E; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-01-01

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures. PMID:27604551

  20. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism.

    PubMed

    Seifitokaldani, Ali; Gheribi, Aïmen E; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-09-08

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures.

  1. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism

    NASA Astrophysics Data System (ADS)

    Seifitokaldani, Ali; Gheribi, Aïmen E.; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-09-01

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures.

  2. Ion-ion recombination of H3O+ with I- and PO3-/PO2- in flames

    NASA Astrophysics Data System (ADS)

    Chow, Christine C. Y.; Goodings, John M.

    1996-03-01

    Ion-ion recombination coefficients ki have been measured in a fuel-rich CH4---O2---Ar flame at 2582 K and atmospheric pressure for the H3O+ cation recombining with anions of iodine and phosphorus, relative to the electron-ion recombination of H3O+, assuming a rate coefficient ke of 4.1 × 10-7 cm3 molecule-1 s-1. Positive and negative ions were observed by sampling the flame through a nozzle into a mass spectrometer. Recombination coefficients were determined from the slopes of plots of the sampled inverse total positive ion current versus distance along the flame axis. For the H3O+/I- recombination, ki = (3.0 ± 1.0) × 10-8 cm3 molecule-1 s-1, considerably higher than the value of (1.2 ± 0.7) × 10-8 determined previously by other workers. A possible reason for the discrepancy involves the cooling which results from flame inhibition by iodine. With phosphorus additive, two major anions PO3- and PO2- jointly recombine with H3O+ to give a "global" rate coefficient ki = (3.7 ± 1.4) × 10-8 cm3 molecule-1 s-1.

  3. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism

    PubMed Central

    Seifitokaldani, Ali; Gheribi, Aïmen E.; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-01-01

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures. PMID:27604551

  4. 210Pb and 210Po Abundances in Dacites Erupted May, 2003 From Anatahan Volcano: Implications for the Time-scales of Magma Generation and Degassing

    NASA Astrophysics Data System (ADS)

    Reagan, M. K.; Matthew, W.; Brian, H.

    2003-12-01

    Six samples of dacite pumice and scoria erupted in May, 2003 and collected from a number of sites around Anathan by Tobias Fischer and David Hilton were analyzed for 210Po activities on three occasions between early June and the time of this writing. With two exceptions, all scoria and pumice samples have 210Po activities that plot on a single growth curve indicating initial (210Po)=0.15 +/-0.07 (1σ ) dpm/g and (210Pb)=1.08+/-0.20 dpm/g. More precise values for these initial activities will be presented at the meeting after further analyses are performed in November. Preliminary alpha spectrometry analyses for U and Th, and ICPMS analyses distributed by Terry Plank suggest that the average (238U) is about 0.53 dpm/g. Equilibrium (228Th)/( 232Th) ratios indicate that these samples do not have excess 228Ra. Assuming that (210Pb )< (226Ra) because of minor degassing of 210Pb (see Gauthier and Condomines, 1999, EPSL, v. 172), the degassing efficiency factor for 210Po is greater than or equal to about 0.85, which is identical to the value calculated for a basaltic andesitic lava from Arenal volcano in Costa Rica (Gill et al., 1985, GRL, v. 12). This is surprising, as the May 10 plinian eruption of Anatahan should have resulted in more closed-system degassing than a lava eruption. This and the similar 210Po values for the scoria and pumice samples suggest that the shallow-level degassing history has little impact on the efficiency of polonium degassing. The scoria and pumice samples from sample 8-1e both have significant excesses of 210Po over the calculated initial (210Pb) value for the other samples. These excesses were partially leachable, indicating that 210Po was sublimated onto these samples, and that these ejecta resided in the vent before being ejected and redeposited The high inferred (226Ra)/( 230Th) for the Anatahan dacites despite the nearly equilibrium (238U)/( 230Th) value measured for one sample contrasts with the values for these ratios in more mafic

  5. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-09-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using a Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM : OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  6. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Teinilä, K.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-03-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM:OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  7. Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X. S.

    2013-12-01

    In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co

  8. Incorporation of 210Pb and 210Po to Poultry through the Addition of Dicalcium Phosphate (DCP) to the Diet

    NASA Astrophysics Data System (ADS)

    Casacuberta, N.; Masqué, P.; Garcia-Orellana, J.; Gasa, J.; Anguita, M.

    2008-08-01

    Due to the replacement of calcium by uranium in the phosphorite, sedimentary phosphate rock contains high concentrations of 238U (i.e. from 1500 Bqṡkg-1 in Morocco to 4000 Bqṡkg-1 in Tanzania ores). Dicalcium Phosphate (DCP) is produced by the wet acid digestion of the phosphorite, and is used as a source of calcium and phosphorus for livestock feed supplement. If the phosphorite acid digestion is made with hydrochloric acid, DCP may present specific activities of about 103 Bqṡkg-1 of 238U and some of its decay chain daughters. In particular, due to its radiological implications, the presence of 210Pb and 210Po in DCP is of special relevance. The aim of this work was to investigate the potential incorporation of these radionuclides to poultry through its diet. Three different diets were therefore prepared with different contents of both DCP and 210Pb and 210Po. Diet A was used as a blank, and had a 2.5% in weight of monocalcium phosphate (MCP); diet B, with a 5% in weight of DCP; and diet C, with a 2.5% of DCP. Concentrations of 210Pb were 0.93, 101.4 and 51.2 Bqṡkg-1; whereas concentrations of 210Po were 0.92, 74 and 36 Bqṡkg-1 of food for diets A, B and C, respectively. Accumulation of 210Pb and 210Po was analysed at several times during poultry growth in samples of bone, liver, kidney, muscle, excrements as well as entire animals, with a total of 30 broilers fed with the 3 different diets. Results showed clear enhancements in the accumulation of both 210Pb and 210Po in chicken for diets B and C, and in particular in liver and bone. However, total accumulation of radionuclides in chicken, and especially in edible parts, is low compared to its expulsion through excrements. These results are interpreted in terms of the potential dose through consumption of chicken.

  9. Characteristics and short-term changes of the Po Delta seafloor morphology through high-resolution bathymetric and backscatter data

    NASA Astrophysics Data System (ADS)

    Madricardo, Fantina; Bosman, Alessandro; Kruss, Aleksandra; Remia, Alessandro; Correggiari, Anna; Fogarin, Stefano; Romagnoli, Claudia; Moscon, Giorgia

    2016-04-01

    River deltas are highly dynamical and valuable environments and often undergo strong natural and human-induced actions that need constant monitoring. Whereas remote sensing observations of the sub-aerial part of the delta are very important for the assessment of the morphological changes over long time scales (years-decades), the short time-scale evolution of the submerged part of the system remains often undetermined. In particular, the shallow-water submarine pro-delta front is commonly characterized by active depositional and erosional processes. This area is crucial for the understanding of the fluvial and coastal dynamics. In this study, we applied geophysical investigations to characterize the very shallow-water area of the Po river delta in the northern Adriatic Sea. The modern Po delta is the result of increased sediment flux derived from both climate change (Little Ice Age) and human impact (deforestation and diversion and construction of artificial levees) and in recent years is suffering erosion. Here, we present the results of two high-resolution multibeam echosounder surveys carried out in June 2013 and in September 2014 on the Po river mouth and delta front in the framework of the Ritmare Project. The Po delta front, as other modern deltas, has a complicated morphology, consisting of multiple terminal distributary channels, subaqueous levee deposits, and mouth bars. The high-resolution bathymetric data show that the prodelta slope has a curved shape with an overall southward asymmetry of the submerged delta due to prevalent longshore currents. The 2013 bathymetric map highlights a number of sedimentary features, such as depositional bars, radiating in the prodelta slope with an asymmetric section, with steeper southward lee side. The new bathymetric map collected in 2014 shows impressive changes: in correspondence with the depositional lobes, we observed extensive collapse depressions with bathymetric changes of over 1 m in 15 months and widespread

  10. Simple and fast PO-CL method for the evaluation of antioxidant capacity of hydrophilic and hydrophobic antioxidants

    NASA Astrophysics Data System (ADS)

    Zargoosh, Kiomars; Ghayeb, Yousef; Azmoon, Behnaz; Qandalee, Mohammad

    2013-08-01

    A simple and fast procedure is described for evaluating the antioxidant activity of hydrophilic and hydrophobic compounds by using the peroxyoxalate-chemiluminescence (PO-CL) reaction of Bis(2,4,6-trichlorophenyl) oxalate (TCPO) with hydrogen peroxide in the presence of di(tert-butyl)2-(tert-butylamino)-5-[(E)-2-phenyl-1-ethenyl]3,4-furandicarboxylate as a highly fluorescent fluorophore. The IC50 values of the well-known antioxidants were calculated and the results were expressed as gallic equivalent antioxidant capacity (GEAC). It was found that the proposed method is free of physical quenching and oxidant interference, for this reason, proposed method is able to determine the accurate scavenging activity of the antioxidants to the free radicals. Finally, the proposed method was applied to the evaluation of antioxidant activity of complex real samples such as soybean oil and sunflower oil (as hydrophobic samples) and honey (as hydrophilic sample). To the best of our knowledge, this is the first time that total antioxidant activity can be determined directly in soybean oil, sunflower oil and honey (not in their extracts) using PO-CL reactions.

  11. Spectroscopy of {sup 193,195,197}Po

    SciTech Connect

    Fotiades, N.; Cizewski, J.A.; McNabb, D.P.; Ding, K.Y.; Davids, C.N.; Janssens, R.V.; Seweryniak, D.; Carpenter, M.P.; Amro, H.; Decrock, P.; Reiter, P.; Nisius, D.; Brown, L.T.; Fischer, S.; Lauritsen, T.; Wauters, J.; Bingham, C.R.; Huyse, M.; Andreyev, A.; Seweryniak, D.; Conticchio, L.F.; Brown, L.T.

    1997-08-01

    Excited states built on the 13/2{sup +} isomers of the odd-mass {sup 193,195,197}Po isotopes have been observed via in-beam {gamma}-ray spectroscopy. The {alpha} radioactivity of these isotopes has been used to tag {gamma}-ray transitions following the {sup A}Er+164 MeV {sup 32}S reactions, where A=164, 166, 167, 168, and 170. Prompt {gamma} radiation was measured by ten Compton-suppressed Ge detectors at the target position and the Fragment Mass Analyzer was used to select evaporation residues. The results are compared with the first excited states of the heavier odd-mass polonium isotopes and of the even-mass cores. {copyright} {ital 1997} {ital The American Physical Society}

  12. PO*WW*ER mobile treatment unit process hazards analysis

    SciTech Connect

    Richardson, R.B.

    1996-06-01

    The objective of this report is to demonstrate that a thorough assessment of the risks associated with the operation of the Rust Geotech patented PO*WW*ER mobile treatment unit (MTU) has been performed and documented. The MTU was developed to treat aqueous mixed wastes at the US Department of Energy (DOE) Albuquerque Operations Office sites. The MTU uses evaporation to separate organics and water from radionuclides and solids, and catalytic oxidation to convert the hazardous into byproducts. This process hazards analysis evaluated a number of accident scenarios not directly related to the operation of the MTU, such as natural phenomena damage and mishandling of chemical containers. Worst case accident scenarios were further evaluated to determine the risk potential to the MTU and to workers, the public, and the environment. The overall risk to any group from operation of the MTU was determined to be very low; the MTU is classified as a Radiological Facility with low hazards.

  13. Comparison of LiFePO4 from different sources

    SciTech Connect

    Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

    2003-11-25

    The lithium iron phosphate chemistry is plagued by the poor conductivity and slow lithium diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study we obtained LiFePO4 electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from one with no carbon coating to one with 15 percent coating. In addition, particle sizes varied by as much as a order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of dopant on performance and ideas for making materials in order to maximize the power capability of this chemistry.

  14. Comparison of LiFePO4 from different sources

    SciTech Connect

    Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

    2004-06-21

    The lithium iron phosphate chemistry is plagued by the poor conductivity and slow diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study, we obtained LiFePO{sub 4} powders and/or electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from 0.4% to 15% ''in-situ'' carbon. In addition, particle sizes varied by as much as an order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of having a distribution in particle sizes, and ideas for making materials in order to maximize the power capability of this chemistry.

  15. Forecasting skills of the ensemble hydro-meteorological system for the Po river floods

    NASA Astrophysics Data System (ADS)

    Ricciardi, Giuseppe; Montani, Andrea; Paccagnella, Tiziana; Pecora, Silvano; Tonelli, Fabrizio

    2013-04-01

    The Po basin is the largest and most economically important river-basin in Italy. Extreme hydrological events, including floods, flash floods and droughts, are expected to become more severe in the next future due to climate change, and related ground effects are linked both with environmental and social resilience. A Warning Operational Center (WOC) for hydrological event management was created in Emilia Romagna region. In the last years, the WOC faced challenges in legislation, organization, technology and economics, achieving improvements in forecasting skill and information dissemination. Since 2005, an operational forecasting and modelling system for flood modelling and forecasting has been implemented, aimed at supporting and coordinating flood control and emergency management on the whole Po basin. This system, referred to as FEWSPo, has also taken care of environmental aspects of flood forecast. The FEWSPo system has reached a very high level of complexity, due to the combination of three different hydrological-hydraulic chains (HEC-HMS/RAS - MIKE11 NAM/HD, Topkapi/Sobek), with several meteorological inputs (forecasted - COSMOI2, COSMOI7, COSMO-LEPS among others - and observed). In this hydrological and meteorological ensemble the management of the relative predictive uncertainties, which have to be established and communicated to decision makers, is a debated scientific and social challenge. Real time activities face professional, modelling and technological aspects but are also strongly interrelated with organization and human aspects. The authors will report a case study using the operational flood forecast hydro-meteorological ensemble, provided by the MIKE11 chain fed by COSMO_LEPS EQPF. The basic aim of the proposed approach is to analyse limits and opportunities of the long term forecast (with a lead time ranging from 3 to 5 days), for the implementation of low cost actions, also looking for a well informed decision making and the improvement of

  16. On the role of the VO(H{sub 2}PO{sub 4}){sub 2} precursor for n-butane oxidation into maleic anhydride

    SciTech Connect

    Sananes, M.T. |; Hutchings, G.J.; Volta, J.C.

    1995-07-01

    The catalytic role of VO(H{sub 2}PO{sub 4}){sub 2}, the precursor of the VO(PO{sub 3}){sub 2} phase, has been studied for N-butane oxidation to maleic anhydride. By comparison with the activated VPO catalyst, derived from the VOHPO{sub 4} {center_dot} 0.5H{sub 2}O precursor phase, VO(H{sub 2}PO{sub 4}){sub 2} gives a highly selective final catalyst. The total oxidation products CO and CO{sub 2} are not observed under any of the conditions examined, a result confirmed by extensive catalyst testing and carbon mass balances. The final catalyst derived from VO(H{sub 2}PO{sub 4}){sub 2} has a low surface area, ca. 1 m{sup 2}/g, and consequently demonstrates low specific activity on the basis of n-butane conversion per unit mass. However, the intrinsic activity (activity per unit surface area) is found to be higher than that for catalysts derived from VOHPO{sub 4}{center_dot}0.5H{sub 2}O. Since some VO(H{sub 2}PO{sub 4}){sub 2} is present in VOHPO{sub 4}{center_dot}0.5H{sub 2}O, which is the precursor of the industrial catalyst, the results of this study complicate the simple model in which the (VO){sub 2}O{sub 7} phase derived from VOHPO{sub 4} {center_dot}0.5H{sub 2}O is responsible for the selective oxidation of n-butane. The observation that the precursor VO(H{sub 2}PO{sub 4}){sub 2} can generate catalysts of high specific activity and of total selectivity to partial oxidation products might provide a useful insight into the design of a new series of high activity and high selectivity partial oxidation catalysts. 36 refs., 12 figs., 2 tabs.

  17. Complete Genome Sequence of the Plant Pathogen Ralstonia solanacearum Strain Po82 ▿

    PubMed Central

    Xu, Jin; Zheng, Hua-jun; Liu, Lei; Pan, Zhe-chao; Prior, Philippe; Tang, Biao; Xu, Jing-sheng; Zhang, Hao; Tian, Qian; Zhang, Li-qing; Feng, Jie

    2011-01-01

    Ralstonia solanacearum strain Po82, a phylotype IIB/sequevar 4 strain, was found to be pathogenic to both solanaceous plants and banana. Here, we report the complete genome sequence of Po82 and its comparison with seven published R. solanacearum genomes. PMID:21685279

  18. Amphiphilic carbonaceous material-intervened solvothermal synthesis of LiFePO4

    NASA Astrophysics Data System (ADS)

    Chen, Ming-ming; Ma, Qian-qian; Wang, Cheng-yang; Sun, Xin; Wang, Li-qun; Zhang, Cui

    2014-10-01

    LiFePO4 samples with preferred facets on the ac plane were prepared by the solvothermal method with or without well-dispersed amphiphilic carbonaceous material (ACM). The effects of ACM on the particle morphology, crystal orientation and electrochemical reactivity of the prepared LiFePO4 nanoparticles were investigated in detail. ACM serves a dual purpose. One purpose is facilitating the plate-like morphologies of LiFePO4 nanoparticles parallel to the bPnma axis by decreasing the surface energy of (010) facets of newly created LiFePO4 nuclei. The other purpose is suppressing crystal growth along the [010] direction by adhering onto the (010) surface of LiFePO4 nanoplates. Furthermore, ACM coating was performed and optimized using a carbon coating precursor. The electrochemical properties of the prepared LiFePO4 particles were characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge cycling tests. After the optimized coating of ACM, the ACM-intervened LiFePO4 composite was observed to deliver discharge capacities of 151.3 mAh g-1 at 1C and 132.2 mAh g-1 at 10C. Even after 1000 cycles at a high rate of 10C, the LiFePO4 cathode could maintain 80% of its initial capacity.

  19. 40 CFR 721.9675 - Titanate [Ti6O13 (2-)], di-po-tas-sium.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Titanate , di-po-tas-sium. 721.9675 Section 721.9675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.9675 Titanate , di-po-tas-sium. (a) Chemical substance and significant new uses subject...

  20. 40 CFR 721.9675 - Titanate [Ti6O13 (2-)], di-po-tas-sium.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Titanate , di-po-tas-sium. 721.9675 Section 721.9675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.9675 Titanate , di-po-tas-sium. (a) Chemical substance and significant new uses subject...

  1. Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries.

    PubMed

    Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X S

    2014-01-21

    In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg(2+) doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg(2+) doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li(+) diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg(2+) doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of "cushion" as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.

  2. Double-Nanocarbon Synergistically Modified Na3V2(PO4)3: An Advanced Cathode for High-Rate and Long-Life Sodium-Ion Batteries.

    PubMed

    Shen, Wei; Li, Hui; Guo, Ziyang; Wang, Cong; Li, Zhihong; Xu, Qunjie; Liu, Haimei; Wang, Yonggang; Xia, Yongyao

    2016-06-22

    An advanced cathode material, nitrogen-doped carbon-coated Na3V2(PO4)3 hybriding with multiwalled carbon nanotubes (CNTs) composite, namely double-nanocarbon synergistically modified Na3V2(PO4)3 of sodium ion battery, was fabricated through a simple sol-gel approach. According to the systemical analysis of experimental results on this composite structure, it is found that N-doping not only increases Na-ion migration velocity across the carbon-coated layer but also improves the electric conductivity of the carbon layer. More importantly, the CNTs 3D conducting network could significantly accelerate the electron transport between multiple particles of Na3V2(PO4)3, due to the intimate contacts between active materials and CNTs. Consenquently, the electrochemical properties of this double-nanocarbon-modified Na3V2(PO4)3 are significantly enhanced, especially the high-rate capability and long cycle life. For instance, its initial capacity of 94.5 mAh g(-1) at 0.2 C decreases to 70 mAh g(-1) at 70 C, and the capacity retention is 74%. Moreover, when dischage rate increases to a higher 30 C, the capacity retention is still as high as 87% after 300 cycles.

  3. Radioactivity concentrations in mussel (Mytilus galloprovincialis) of Turkish Sea coast and contribution of ²¹⁰Po to the radiation dose.

    PubMed

    Kılıç, Önder; Belivermiş, Murat; Cotuk, Yavuz; Topçuoğlu, Sayhan

    2014-03-15

    Radionuclides levels were determined in indigenous and transplanted mussels (Mytilus galloprovincialis) collected from Turkish marine environment. Radioactivity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb were determined in the soft tissues of the mussel samples collected in Bosphorus Strait, Coasts of Black Sea, Marmara Sea and Aegean Sea. Mussel transplantation was carried out by using mussel cages in Levantine Sea coast since M. galloprovincialis did not naturally adapt along the coast. The average activity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb in the coastline of Turkey were found to be 0.7±0.1, 469±24, 0.9±0.1, 1.0±0.1, 122±4 and 10.9±0.9 Bq kg⁻¹ in dry weight (dw), respectively. The average of ²¹⁰Po/²¹⁰Pb ratio was found to be ∼14. Total annual effective ²¹⁰Po dose was calculated to be in the range of 0.25-3.30 μSv due to mussel consumption. Radioactivity and dose levels were compared with those of similar studies carried out in Mediterranean countries. PMID:24398417

  4. Electrochemical Investigation of Al–Li/LixFePO4 Cells in Oligo(ethylene glycol) Dimethyl Ether/LiPF6

    SciTech Connect

    Wang, X.J.; Zhou, Y.N.; Lee, H.S.; Nam, K.W.; Yang, X.Q.; Haas, O.

    2011-02-01

    1 M LiPF{sub 6} dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight, 500 g mol{sup -1} (OEGDME500, 1 M LiPF{sub 6}), was investigated as an electrolyte in experimental Al-Li/LiFePO{sub 4} cells. More than 60 cycles were achieved using this electrolyte in a Li-ion cell with an Al-Li alloy as an anode sandwiched between two Li x FePO{sub 4} electrodes (cathodes). Charging efficiencies of 96-100% and energy efficiencies of 86-89% were maintained during 60 cycles at low current densities. A theoretical investigation revealed that the specific energy can be increased up to 15% if conventional LiC{sub 6} anodes are replaced by Al-Li alloy electrodes. The specific energy and the energy density were calculated as a function of the active mass per electrode surface (charge density). The results reveal that for a charge density of 4 mAh cm{sup -2} about 160 mWh g{sup -1} can be reached with Al-Li/LiFePO{sub 4} batteries. Power limiting diffusion processes are discussed, and the power capability of Al-Li/LiFePO{sub 4} cells was experimentally evaluated using conventional electrolytes.

  5. Radioactivity concentrations in mussel (Mytilus galloprovincialis) of Turkish Sea coast and contribution of ²¹⁰Po to the radiation dose.

    PubMed

    Kılıç, Önder; Belivermiş, Murat; Cotuk, Yavuz; Topçuoğlu, Sayhan

    2014-03-15

    Radionuclides levels were determined in indigenous and transplanted mussels (Mytilus galloprovincialis) collected from Turkish marine environment. Radioactivity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb were determined in the soft tissues of the mussel samples collected in Bosphorus Strait, Coasts of Black Sea, Marmara Sea and Aegean Sea. Mussel transplantation was carried out by using mussel cages in Levantine Sea coast since M. galloprovincialis did not naturally adapt along the coast. The average activity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po and ²¹⁰Pb in the coastline of Turkey were found to be 0.7±0.1, 469±24, 0.9±0.1, 1.0±0.1, 122±4 and 10.9±0.9 Bq kg⁻¹ in dry weight (dw), respectively. The average of ²¹⁰Po/²¹⁰Pb ratio was found to be ∼14. Total annual effective ²¹⁰Po dose was calculated to be in the range of 0.25-3.30 μSv due to mussel consumption. Radioactivity and dose levels were compared with those of similar studies carried out in Mediterranean countries.

  6. Double-Nanocarbon Synergistically Modified Na3V2(PO4)3: An Advanced Cathode for High-Rate and Long-Life Sodium-Ion Batteries.

    PubMed

    Shen, Wei; Li, Hui; Guo, Ziyang; Wang, Cong; Li, Zhihong; Xu, Qunjie; Liu, Haimei; Wang, Yonggang; Xia, Yongyao

    2016-06-22

    An advanced cathode material, nitrogen-doped carbon-coated Na3V2(PO4)3 hybriding with multiwalled carbon nanotubes (CNTs) composite, namely double-nanocarbon synergistically modified Na3V2(PO4)3 of sodium ion battery, was fabricated through a simple sol-gel approach. According to the systemical analysis of experimental results on this composite structure, it is found that N-doping not only increases Na-ion migration velocity across the carbon-coated layer but also improves the electric conductivity of the carbon layer. More importantly, the CNTs 3D conducting network could significantly accelerate the electron transport between multiple particles of Na3V2(PO4)3, due to the intimate contacts between active materials and CNTs. Consenquently, the electrochemical properties of this double-nanocarbon-modified Na3V2(PO4)3 are significantly enhanced, especially the high-rate capability and long cycle life. For instance, its initial capacity of 94.5 mAh g(-1) at 0.2 C decreases to 70 mAh g(-1) at 70 C, and the capacity retention is 74%. Moreover, when dischage rate increases to a higher 30 C, the capacity retention is still as high as 87% after 300 cycles. PMID:27257712

  7. The Year of the Solar System: An E/PO Community's Approach to Sharing Planetary Science

    NASA Astrophysics Data System (ADS)

    Shipp, S. S.; Boonstra, D.; Shupla, C.; Dalton, H.; Scalice, D.; Planetary Science E/Po Community

    2010-12-01

    YSS offers the opportunity to raise awareness, build excitement, and make connections with educators, students and the public about planetary science activities. The planetary science education and public outreach (E/PO) community is engaging and educating their audiences through ongoing mission and program activities. Based on discussion with partners, the community is presenting its products in the context of monthly thematic topics that are tied to the big questions of planetary science: how did the Sun’s family of planets and bodies originate and how have they evolved; and how did life begin and evolve on Earth, has it evolved elsewhere in our solar system, and what are characteristics that lead to the origins of life? Each month explores different compelling aspects of the solar system - its formation, volcanism, ice, life. Resources, activities, and events are interwoven in thematic context, and presented with ideas through which formal and informal educators can engage their audiences. The month-to-month themes place the big questions in a logical sequence of deepening learning experiences - and highlight mission milestones and viewing events. YSS encourages active participation and communication with its audiences. It includes nation-wide activities, such as a Walk Through the Solar System, held between October 2010 to March 2011, in which museums, libraries, science centers, schools, planetariums, amateur astronomers, and others are kicking off YSS by creating their own scale models of the solar system and sharing their events through online posting of pictures, video, and stories. YSS offers the E/PO community the opportunity to collaborate with each other and partners. The thematic approach leverages existing products, providing a home and allowing a “shelf life” that can outlast individual projects and missions. The broad themes highlight missions and programs multiple times. YSS also leverages existing online resources and social media. Hosted on

  8. Immune indices and identical functions of two prophenoloxidases from the haemolymph of green tiger shrimp Penaeus semisulcatus and its antibiofilm activity.

    PubMed

    Ishwarya, Ramachandran; Jayanthi, Sangily; Muthulakshmi, Perumal; Anjugam, Mahalingam; Jayakumar, Rengarajan; Khudus Nazar, Abdul; Vaseeharan, Baskaralingam

    2016-04-01

    In the present study, we purified two prophenoloxidases (proPO) from haemolymph of green tiger shrimp, Penaeus semisulcatus by gel fermentation chromatography using blue Sepharose matrix. The two purified prophenoloxidase macromolecules are of about 76 and 75 kDa determined through SDS-PAGE and named as Penaeus semisulcatus prophenoloxidase I (PSproPO I) and Penaeus semisulcatus prophenoloxidase II (PSproPO II). It was further characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Circular Dichroism (CD) and High Performance Liquid Chromatography (HPLC) analysis. The purified PSproPO I and PSproPO II showed the strongest agglutination titre against human erythrocytes compared to goat RBC. The PSproPO I and PSproPO II showed phagocytic activity against yeast Saccharomyces cerevisiae and encapsulation activity against Sepharose CL 6B beads compared to CM Sepharose and Sodium alginate beads. The functional analysis of purified PSproPO I and PSproPO II showed enhanced PO activity when added with the triggering molecules such as pathogen associated molecular patterns (PAMPs), metals and chemicals. In addition, eluted fraction containing PSproPO I and PSproPO II showed antibiofilm activity against Gram positive and Gram negative bacteria. The above results concluded that no significant differences were found between the purified PSproPO I and PSproPO II immune indices and functions. This study might provide a sensitive platform to understand more about the critical roles of PSproPO I and PSproPO II in crustacean immune system. PMID:26899630

  9. Magnetic properties of Li(MnyFe1-y)PO4 and its delithiated phases

    NASA Astrophysics Data System (ADS)

    Yamada, Atsuo; Takei, Yuki; Koizumi, Hiroshi; Sonoyama, Noriyuki; Kanno, Ryoji

    2005-12-01

    A series of synthetic (MnyFe1-y)PO4 (y<0.8) phases with negligible disorder and impurities were obtained by chemical oxidation of crystallized isotypic Li(MnyFe1-y)PO4 under optimized conditions. This enabled us to perform the comparative magnetic study along the two solid-solution lines based on inherent susceptibility data with no parasitic magnetic signals. All samples exhibit antiferromagnetism but the decrease in Néel temperature is more than seven times larger in (MnyFe1-y)PO4 than in Li(MnyFe1-y)PO4. This was discussed in terms of the asymmetric superexchange interaction by an unusual synergetic effect of Jahn-Teller distortion and edge-shared interconnection with PO4 tetrahedra.

  10. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions. PMID:26863291

  11. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions.

  12. Processes controlling the distributions of Cd and PO4 in the ocean

    NASA Astrophysics Data System (ADS)

    Quay, Paul; Cullen, Jay; Landing, William; Morton, Peter

    2015-06-01

    Depth profiles of dissolved Cd and PO4 from a global data compilation were used to derive the Cd/P of particles exported from the surface layer, and the results indicate lowest values in the North Atlantic (0.17 ± 0.05), highest in the Southern (0.56 ± 0.24), and intermediate in the South Indian (0.31 ± 0.14) and North Pacific (0.36 ± 0.08) Ocean basins. The Cd/P of exported particles in high nutrient-low chlorophyll (HNLC) regions is twice that for particles exported in non-HNLC regions as is the fractionation effect during biological uptake of Cd and PO4, and these trends primarily determine the spatial trends of dissolved Cd/PO4 observed in the surface ocean. In deep waters the lowest dissolved Cd/PO4 of 0.23 ± 0.07 is found in the North Atlantic Ocean and the result primarily of low Cd/PO4 of North Atlantic Deep Water (0.23). In contrast, deep waters in the Southern Ocean have significantly higher dissolved Cd/PO4 (0.30 ± 0.06), which is a result of the Cd/PO4 of upwelled deep water from the South Pacific and South Indian (0.28) and the high Cd/P of degrading particles. A multibox model that accounts for the impacts of particle degradation and thermohaline circulation in the deep sea yields dissolved Cd and PO4 interbasin trends close to observations. Model experiments illustrate the dependence of the dissolved Cd/PO4 of the deep sea on the extent of HNLC conditions in the Southern Ocean and the impact on reconstructing paleo PO4 concentrations from a Cd proxy.

  13. Pnicogen bonded complexes of PO2X (X = F, Cl) with nitrogen bases.

    PubMed

    Alkorta, Ibon; Elguero, José; Del Bene, Janet E

    2013-10-10

    An ab initio MP2/aug'-cc-pVTZ study has been carried out on complexes formed between PO2X (X = F and Cl) as the Lewis acids and a series of nitrogen bases ZN, including NH3, H2C═NH, NH2F, NP, NCH, NCF, NF3, and N2. Binding energies of these complexes vary from -10 to -150 kJ/mol, and P-N distances from 1.88 to 2.72 Å. Complexes ZN:PO2F have stronger P(...)N bonds and shorter P-N distances than the corresponding complexes ZN:PO2Cl. Charge transfer from the N lone pair through the π-hole to the P-X and P-O σ* orbitals leads to stabilization of these complexes, although charge-transfer energies can be evaluated only for complexes with binding energies less than -71 kJ/mol. Complexation of PO2X with the strongest bases leads to P···N bonds with a significant degree of covalency, and P-N distances that approach the P-N distances in the molecules PO2NC and PO2NH2. In these complexes, the PO2X molecules distort from planarity. Changes in (31)P absolute chemical shieldings upon complexation do not correlate with changes in charges on P, although they do correlate with the binding energies of the complexes. EOM-CCSD spin-spin coupling constants (1p)J(P-N) are dominated by the Fermi-contact term, which is an excellent approximation to total J. (1p)J(P-N) values are small at long distances, increase as the distance decreases, but then decrease at short P-N distances. At the shortest distances, values of (1p)J(P-N) approach (1)J(P-N) for the molecules PO2NC and PO2NH2.

  14. Degradation diagnosis of aged Li4Ti5O12/LiFePO4 batteries

    NASA Astrophysics Data System (ADS)

    Castaing, Rémi; Reynier, Yvan; Dupré, Nicolas; Schleich, Donald; Jouanneau Si Larbi, Séverine; Guyomard, Dominique; Moreau, Philippe

    2014-12-01

    Li4Ti5O12/LiFePO4 cells are cycled under 4 different conditions of discharge profile (galvanostatic or driving-based) and cycling rates (C/8 or 1C) during 4-5 months. All the cells exhibit capacity fade whose extent is not correlated with the aging condition. In order to understand aging phenomena, cells are disassembled at the end of cycle life and the recovered electrodes are analyzed using electrochemistry, electron microscopy, XRD and MAS-NMR. Positive and negative electrodes show no loss in active material and no change in electrochemical activity, active material structure and composite electrode structure. This rules out any irreversible electrode degradation. Lithium stoichiometry estimated by both XRD and electrochemistry is unexpectedly low in the positive electrode when the aging is stopped at full discharge. That indicates a loss of cyclable lithium or electrons leading to cell balancing evolution. That loss may have been caused by parasitic reactions occurring at both electrodes, in accordance with their rich surface chemistry as evidenced by MAS-NMR.

  15. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

  16. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures. PMID:26328435

  17. 3D Quaternary deformation pattern in the central Po Plain (Northern Italy)

    NASA Astrophysics Data System (ADS)

    Sileo, G.; Mueller, K.; Michetti, A. M.; Livio, F.; Berlusconi, A.; Carcano, C.; Rogledi, S.; Vittori, E.

    2009-04-01

    The Po Plain is a foredeep basin flanked by the two major and active orogens of the Italian Peninsula, the Alps to the North and the Apennines to the South. The basin has a quasi - triangular shape and grades longitudinally to the East in the Adriatic Sea. We used petroleum industry seismic reflection data acquired by ENI E&P in the Central Po Plain, over an area spanning about 6800 km2 from Lake Como to the W to Lake Garda to the E, and from the Lombardian Southern Alps to the N and the Emilia Apennines to the S, in order to analyze and interpret selected seismic reflectors and to define the evolution in space and time of the local active tectonic structures. Folds associated with underlying thrusts were recognized based on deformation recorded by two regional sequence boundary horizons, i.e. the ‘A' Surface (1.6 Myr) and the ‘R' Surface (0. 9 Myr; e.g., Carcano & Piccin, 2002; Muttoni et al., 2003), characterized by good stratigraphic and age bracketing, and marking significant changes in the sedimentary architecture of the Po Basin. Age controls are based on stratigraphic, paleontological and magnetostratigraphic analysis by ENI E&P and Regione Lombardia (Carcano & Piccin, 2002; Scardia et al., 2006). The analysis of strain recorded by these horizons allowed us to: A) recognize a belt of active fold and thrust structures, each 10 to 20 km long, arranged with an en-echelon pattern across the whole Po Basin, and B) analyze their evolution over the Quaternary. 'A' surface (1.6 Myr) The ‘A' surface has been mapped over about 7800 Km2. From North to South four major morphobathymetric domains can be defined in the Pleistocene marine Po Basin: an Alpine platform domain, a slope that links it with the wider central basin domain, a smaller and steeper slope and an Apennine platform domain. The basin shape has an asymmetric transversal profile and is ca. 40 km wide. Several tectonic structures affect this surface. On the Alpine platform domain two small structures

  18. Cathode performance of LiMnPO 4/C nanocomposites prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment

    NASA Astrophysics Data System (ADS)

    Doan, The Nam Long; Taniguchi, Izumi

    LiMnPO 4/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment in the range of spray pyrolysis temperature from 200 to 500 °C. The ordered LiMnPO 4 olivine structure without any impurity phase could be identified by X-ray diffraction analysis for all samples. It could be also confirmed from scanning electron microscopy and transmission electron microscopy observations that the final samples were the LiMnPO 4/C nanocomposites with approximately 100 nm in primary particles size. The LiMnPO 4/C nanocomposite samples were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li|1 M LiPF 6 in EC:DMC = 1:1|LiMnPO 4/C at various charge/discharge rates in three charge modes. As a result, the final sample which was synthesized at 300 °C by spray pyrolysis showed the best electrochemical performance due to the largest specific surface area, the smallest primary particle size and a well distribution of carbon. At galvanostatic charge/discharge rates of 0.05 C, the cell delivered first discharge capacities of 123 and 165 mAh g -1 in correspondence to charge cutoff voltages of 4.4 and 5.0 V, respectively. Furthermore, in a constant current-constant voltage charge mode at 4.4 V, the cells also exhibited initial discharge capacities of 147 mAh g -1 at 0.05 C, 145 mAh g -1 at 0.1 C, 123 mAh g -1 at 1 C and 65 mAh g -1 at 10 C. Moreover, the cells showed fair good cycleability over 100 cycles.

  19. Biomonitoring of ²¹⁰Po and ²¹⁰Pb using lichens and mosses around coal-fired power plants in Western Turkey.

    PubMed

    Sert, Emel; Uğur, Aysun; Ozden, Banu; Saç, Müslim Murat; Camgöz, Berkay

    2011-06-01

    Mosses and lichens are useful biological indicators of environmental contamination for a variety of metals and radionuclides of both natural and artificial origin. These plants lack a well-developed root system and rely largely on atmospheric deposition for nourishment. Therefore in the study, different lichens (Cladonia convoluta, Cladonia foliacea) and mosses (Homalothecium sericeum, Hypnum lacunosum, Hypnum cupressiforme, Tortella tortuosa, Didymodon acutus, Syntrichia ruralis, Syntrichia intermedia, Pterogonium graciale, Isothecium alopecuroides, Pleurochatae squarrosa) were collected around the Yatağan (Muğla), Soma (Manisa), Seyitömer - Tunçbilek (Kütahya) coal-fired power plants and investigated for potential use as biomonitors for (210)Po and (210)Pb deposition. While the activity concentrations of (210)Po and (210)Pb in lichens are in the ranges of 151 ± 7-593 ± 21 and 97 ± 5-364 ± 13 Bq kg(-1), for mosses the ranges for (210)Po and (210)Pb are 124 ± 5-1125 ± 38 and 113 ± 4-490 ± 17 Bq kg(-1), respectively. In the study, the moss samples were observed to accumulate more (210)Po and (210)Pb compared to lichens. While the most suitable biomonitor was a moss species (H. lacunosum) for Yatağan (Muğla), it was another moss species (S. intermedia) for Soma (Manisa) and Seyitömer - Tunçbilek (Kütahya) sites. (210)Po concentrations were found higher than (210)Pb concentrations at the all sampling stations.

  20. Room-temperature miscibility gap in LixFePO4.

    PubMed

    Yamada, Atsuo; Koizumi, Hiroshi; Nishimura, Shin-Ichi; Sonoyama, Noriyuki; Kanno, Ryoji; Yonemura, Masao; Nakamura, Tatsuya; Kobayashi, Yo

    2006-05-01

    The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO(4), solves these problems, but has a kinetic problem involving strong electron/hole localization. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe(3+)PO(4)/LiFe(2+)PO(4) two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe(3+)/Fe(2+) mixed-valent intermediate LialphaFePO4 and Li1-betaFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be alpha=0.05 and 1-beta=0.89. The corresponding solid solution ranges outside the miscibility gap (0