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  1. Histone H2AX in DNA repair

    International Nuclear Information System (INIS)

    Lewandowska, H.; Szumiel, I.

    2002-01-01

    The paper reviews the recent reports on the role of the phosphorylated histone H2AX (γ-H2AX). The modification of this histone is an important part of the cellular response to the induction of DNA double strand brakes (DSB) by ionising radiation and other DSB-generating factors. In irradiated cells the modification is carried out mainly by ATM (ataxia-telangiectasia mutated) kinase, the enzyme that starts the alarm signalling upon induction of DSB.γ-H2AX molecules are formed within 1-3 min after irradiation and form foci at the sites of DSB. This seems to be necessary for the recruitment of repair factors that are later present in foci of damaged nuclei. Modification of a constant percentage of H2AX molecules per DSB takes place, corresponding to chromatin domains of megabase of DNA. (author)

  2. Staining Against Phospho-H2AX (gamma-H2AX) as a Marker for DNA Damage and Genomic Instability in Cancer Tissues and Cells

    NARCIS (Netherlands)

    Nagelkerke, A.P.; Span, P.N.

    2016-01-01

    Phospho-H2AX or gamma-H2AX- is a marker of DNA double-stranded breaks and can therefore be used to monitor DNA repair after, for example, irradiation. In addition, positive staining for phospho-H2AX may indicate genomic instability and telomere dysfunction in tumour cells and tissues. Here, we

  3. Histone H2AX is a critical factor for cellular protection against DNA alkylating agents.

    Science.gov (United States)

    Meador, J A; Zhao, M; Su, Y; Narayan, G; Geard, C R; Balajee, A S

    2008-09-25

    Histone H2A variant H2AX is a dose-dependent suppressor of oncogenic chromosome translocations. H2AX participates in DNA double-strand break repair, but its role in other DNA repair pathways is not known. In this study, role of H2AX in cellular response to alkylation DNA damage was investigated. Cellular sensitivity to two monofunctional alkylating agents (methyl methane sulfonate and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)) was dependent on H2AX dosage, and H2AX null cells were more sensitive than heterozygous cells. In contrast to wild-type cells, H2AX-deficient cells displayed extensive apoptotic death due to a lack of cell-cycle arrest at G(2)/M phase. Lack of G(2)/M checkpoint in H2AX null cells correlated well with increased mitotic irregularities involving anaphase bridges and gross chromosomal instability. Observation of elevated poly(ADP) ribose polymerase 1 (PARP-1) cleavage suggests that MNNG-induced apoptosis occurs by PARP-1-dependent manner in H2AX-deficient cells. Consistent with this, increased activities of PARP and poly(ADP) ribose (PAR) polymer synthesis were detected in both H2AX heterozygous and null cells. Further, we demonstrate that the increased PAR synthesis and apoptotic death induced by MNNG in H2AX-deficient cells are due to impaired activation of mitogen-activated protein kinase pathway. Collectively, our novel study demonstrates that H2AX, similar to PARP-1, confers cellular protection against alkylation-induced DNA damage. Therefore, targeting either PARP-1 or histone H2AX may provide an effective way of maximizing the chemotherapeutic value of alkylating agents for cancer treatment.

  4. Phosphorylation of Histone H2AX in the Mouse Brain from Development to Senescence

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    Serena Barral

    2014-01-01

    Full Text Available Phosphorylation of the histone H2AXH2AX form is an early response to DNA damage and a marker of aging and disease in several cells and tissues outside the nervous system. Little is known about in vivo phosphorylation of H2AX in neurons, although it was suggested that γH2AX is an early marker of neuronal endangerment thus opening the possibility to target it as a neuroprotective strategy. After experimental labeling of DNA-synthesizing cells with 5-bromo-2-deoxyuridine (BrdU, we studied the brain occurrence of γH2AX in developing, postnatal, adult and senescent (2 years mice by light and electron microscopic immunocytochemistry and Western blotting. Focal and/or diffuse γH2AX immunostaining appears in interkinetic nuclei, mitotic chromosomes, and apoptotic nuclei. Immunoreactivity is mainly associated with neurogenetic areas, i.e., the subventricular zone (SVZ of telencephalon, the cerebellar cortex, and, albeit to a much lesser extent, the subgranular zone of the hippocampal dentate gyrus. In addition, γH2AX is highly expressed in the adult and senescent cerebral cortex, particularly the piriform cortex. Double labeling experiments demonstrate that γH2AX in neurogenetic brain areas is temporally and functionally related to proliferation and apoptosis of neuronal precursors, i.e., the type C transit amplifying cells (SVZ and the granule cell precursors (cerebellum. Conversely, γH2AX-immunoreactive cortical neurons incorporating the S phase-label BrdU do not express the proliferation marker phosphorylated histone H3, indicating that these postmitotic cells undergo a significant DNA damage response. Our study paves the way for a better comprehension of the role of H2AX phosphorylation in the normal brain, and offers additional data to design novel strategies for the protection of neuronal precursors and mature neurons in central nervous system (CNS degenerative diseases.

  5. ATM and SIRT6/SNF2H Mediate Transient H2AX Stabilization When DSBs Form by Blocking HUWE1 to Allow Efficient γH2AX Foci Formation

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    Yuko Atsumi

    2015-12-01

    Full Text Available In response to DNA double-strand breaks (DSBs, H2AX is rapidly phosphorylated at Ser139 to promote DSB repair. Here we show that H2AX is rapidly stabilized in response to DSBs to efficiently generate γH2AX foci. This mechanism operated even in quiescent cells that barely expressed H2AX. H2AX stabilization resulted from the inhibition of proteasome-mediated degradation. Synthesized H2AX ordinarily underwent degradation through poly-ubiquitination mediated by the E3 ligase HUWE1; however, H2AX ubiquitination was transiently halted upon DSB formation. Such rapid H2AX stabilization by DSBs was associated with chromatin incorporation of H2AX and halting of its poly-ubiquitination mediated by the ATM kinase, the sirtuin protein SIRT6, and the chromatin remodeler SNF2H. H2AX Ser139, the ATM phosphorylation site, was essential for H2AX stabilization upon DSB formation. Our results reveal a pathway controlled by ATM, SIRT6, and SNF2H to block HUWE1, which stabilizes H2AX and induces its incorporation into chromatin only when cells are damaged.

  6. Soluble histone H2AX is induced by DNA replication stress and sensitizes cells to undergo apoptosis

    Directory of Open Access Journals (Sweden)

    Duensing Stefan

    2008-07-01

    Full Text Available Abstract Background Chromatin-associated histone H2AX is a key regulator of the cellular responses to DNA damage. However, non-nucleosomal functions of histone H2AX are poorly characterized. We have recently shown that soluble H2AX can trigger apoptosis but the mechanisms leading to non-chromatin-associated H2AX are unclear. Here, we tested whether stalling of DNA replication, a common event in cancer cells and the underlying mechanism of various chemotherapeutic agents, can trigger increased soluble H2AX. Results Transient overexpression of H2AX was found to lead to a detectable fraction of soluble H2AX and was associated with increased apoptosis. This effect was enhanced by the induction of DNA replication stress using the DNA polymerase α inhibitor aphidicolin. Cells manipulated to stably express H2AX did not contain soluble H2AX, however, short-term treatment with aphidicolin (1 h resulted in detectable amounts of H2AX in the soluble nuclear fraction and enhanced apoptosis. Similarly, soluble endogenous H2AX was detected under these conditions. We found that excessive soluble H2AX causes chromatin aggregation and inhibition of ongoing gene transcription as evidenced by the redistribution and/or loss of active RNA polymerase II as well as the transcriptional co-activators CBP and p300. Conclusion Taken together, these results show that DNA replication stress rapidly leads to increased soluble H2AX and that non-chromatin-associated H2AX can sensitize cells to undergo apoptosis. Our findings encourage further studies to explore H2AX and the cellular pathways that control its expression as anti-cancer drug targets.

  7. Assessment of γ-H2AX levels in circulating tumor cells from patients receiving chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Villa, Alejandra; Balasubramanian, Priya; Miller, Brandon L. [William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH (United States); Lustberg, Maryam B.; Ramaswamy, Bhuvaneswari [Department of Internal Medicine, Breast Medical Oncology, James Cancer Hospital and Ohio State University Comprehensive Cancer Center, Columbus, OH (United States); Chalmers, Jeffrey J., E-mail: chalmers.1@osu.edu [William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH (United States)

    2012-10-25

    Circulating tumor cells (CTCs) are prognostic markers in a variety of solid tumor malignancies. The potential of CTCs to be used as a “liquid biopsy” to monitor a patient’s condition and predict drug response and resistance is currently under investigation. Using a negative depletion, enrichment methodology, CTCs isolated from the peripheral blood of breast cancer patients with stage IV breast cancer undergoing DNA damaging therapy with platinum-based therapy were enriched. The enriched cell suspensions were stained with an optimized labeling protocol targeting: nuclei, cytokeratins 8, 18, and 19, the surface marker CD45, and the presence of the protein γ-H2AX. As a direct or indirect result of platinum therapy, double-strand break of DNA initiates phosphorylation of the histone H2AX, at serine 139; this phosphorylated form is referred to as γ-H2AX. In addition to γ-H2AX staining in specific locations with the cell nuclei, consistent with previous reports and referred to as foci, more general staining in the cell cytoplasm was also observed in some cells suggesting the potential of cell apoptosis. Our study underscores the utility and the complexity of investigating CTCs as predictive markers of response to various therapies. Additional studies are ongoing to evaluate the diverse γ-H2AX staining patterns we report here which needs to be further correlated with patient outcomes.

  8. Human lymphocyte damage and phosphorylation of H2AX and ATM induced by γ-rays

    International Nuclear Information System (INIS)

    Tian Mei; Pan Yan; Liu Jianxiang; Ruan Jianlei; Su Xu

    2011-01-01

    Objective: To investigate 60 Co γ-ray induced damage in lymphocytes and the relationship between doses of 60 Co γ-ray irradiation and the levels of phosphorylated H2AX and ATM. Methods: Cells were irradiated with 60 Co γ-rays in the range of 0-8 Gy. The levels of phosphorylated H2AX and ATM were detected by Western blot and FACScan,respectively. The micronucleus(MN)was analyzed by CB method to evaluate DNA damage. Results: FACScan results showed the dose-effect relationship of γ-H2AX expression were linear.square at 0.5 h post-irradiation to different doses, and the fitting curve was shown as Y=3.96+11.29D-0.45D 2 . The level of phosphorylated ATM (p-ATM) was not changed significantly by using the same method. Western blot showed that p-ATM protein expression was significantly increased after irradiation compared with sham, irradiated group. The MN assay which represented DNA damage was sensitive to different doses. Conclusions: γ-ray irradiation could induce the phosphorylation of H2AX and ATM, which may play an important role in indicating DNA damage. Both of H2AX and ATM have the potential as sensitive biomarker and biodosimeter for radiation damage. (authors)

  9. Ultrasound-induced DNA damage and signal transductions indicated by gammaH2AX

    Science.gov (United States)

    Furusawa, Yukihiro; Fujiwara, Yoshisada; Zhao, Qing-Li; Hassan, Mariame Ali; Ogawa, Ryohei; Tabuchi, Yoshiaki; Takasaki, Ichiro; Takahashi, Akihisa; Ohnishi, Takeo; Kondo, Takashi

    2011-09-01

    Ultrasound (US) has been shown to induce cancer cell death via different forms including apoptosis. Here, we report the potential of low-intensity pulsed US (LIPUS) to induce genomic DNA damage and subsequent DNA damage response. Using the ionizing radiation-induced DNA double-strand breaks (DSBs) as the positive control, we were able to observe the induction of DSBs (as neutral comet tails) and the subsequent formation of gammaH2AX-positive foci (by immunofluorescence detection) in human leukemia cells following exposure to LIPUS. The LIPUS-induced DNA damage arose most likely from the mechanical, but not sonochemical, effect of cavitation, based on our observation that the suppression of inertial cavitation abrogated the gammH2AX foci formation, whereas scavenging of free radical formation (e.g., hydroxyl radical) had no protective effect on it. Treatment with the specific kinase inhibitor of ATM or DNA-PKcs, which can phosphorylate H2AX Ser139, revealed that US-induced gammaH2AX was inhibited more effectively by the DNA-PK inhibitor than ATM kinase inhibitor. Notably, these inhibitor effects were opposite to those with radiation-induced gammH2AX. In conclusion, we report, for the first time that US can induce DNA damage and the DNA damage response as indicated by gammaH2AX was triggered by the cavitational mechanical effects. Thus, it is expected that the data shown here may provide a better understanding of the cellular responses to US.

  10. Histone H2AX participates the DNA damage-induced ATM activation through interaction with NBS1.

    Science.gov (United States)

    Kobayashi, Junya; Tauchi, Hiroshi; Chen, Benjamin; Burma, Sandeep; Bruma, Sandeep; Tashiro, Satoshi; Matsuura, Shinya; Tanimoto, Keiji; Chen, David J; Komatsu, Kenshi

    2009-03-20

    Phosphorylated histone H2AX (gamma-H2AX) functions in the recruitment of DNA damage response proteins to DNA double-strand breaks (DSBs) and facilitates DSB repair. ATM also co-localizes with gamma-H2AX at DSB sites following its auto-phosphorylation. However, it is unclear whether gamma-H2AX has a role in activation of ATM-dependent cell cycle checkpoints. Here, we show that ATM as well as NBS1 is recruited to damaged-chromatin in a gamma-H2AX-dependent manner. Foci formation of phosphorylated ATM and ATM-dependent phosphorylation is repressed in H2AX-knockdown cells. Furthermore, anti-gamma-H2AX antibody co-immunoprecipitates an ATM-like protein kinase activity in vitro and recombinant H2AX increases in vitro kinase activity of ATM from un-irradiated cells. Moreover, H2AX-deficient cells exhibited a defect in ATM-dependent cell cycle checkpoints. Taken together, gamma-H2AX has important role for effective DSB-dependent activation of ATM-related damage responses via NBS1.

  11. Histone H2AX participates the DNA damage-induced ATM activation through interaction with NBS1

    International Nuclear Information System (INIS)

    Kobayashi, Junya; Tauchi, Hiroshi; Chen, Benjamin; Bruma, Sandeep; Tashiro, Satoshi; Matsuura, Shinya; Tanimoto, Keiji; Chen, David J.; Komatsu, Kenshi

    2009-01-01

    Phosphorylated histone H2AX (γ-H2AX) functions in the recruitment of DNA damage response proteins to DNA double-strand breaks (DSBs) and facilitates DSB repair. ATM also co-localizes with γ-H2AX at DSB sites following its auto-phosphorylation. However, it is unclear whether γ-H2AX has a role in activation of ATM-dependent cell cycle checkpoints. Here, we show that ATM as well as NBS1 is recruited to damaged-chromatin in a γ-H2AX-dependent manner. Foci formation of phosphorylated ATM and ATM-dependent phosphorylation is repressed in H2AX-knockdown cells. Furthermore, anti-γ-H2AX antibody co-immunoprecipitates an ATM-like protein kinase activity in vitro and recombinant H2AX increases in vitro kinase activity of ATM from un-irradiated cells. Moreover, H2AX-deficient cells exhibited a defect in ATM-dependent cell cycle checkpoints. Taken together, γ-H2AX has important role for effective DSB-dependent activation of ATM-related damage responses via NBS1.

  12. Study on ?H2AX Expression of Lymphocytes as a Biomarker In Radiation Biodosimetry

    OpenAIRE

    Pan, Yan; Gao, Gang; Ruan, Jian Lei; Liu, Jian Xiang

    2016-01-01

    Flow cytometry analysis was used to detect the changes of ?H2AX protein expression in human peripheral blood lymphocytes. In the dose-effect study, the expression of ?H2AX was detected 1 h after irradiation with 60Co ?-rays at doses of 0, 0.5, 1, 2, 4, and 6 Gy. Blood was cultivated for 0, 1, 2, 4, 6, 12, and 24 h after 4 Gy 60Co ?-rays irradiation for the time-effect study. At the same time, the blood was divided into four treatment groups (ultraviolet [UV] irradiation, 60Co ?-rays irradiati...

  13. A preliminary study to detect CT radiation doses by using the γH2AX focus formation assay

    International Nuclear Information System (INIS)

    Zhang Bo; Gong Jianping; Zhang Wei; Yu Zeyang; Zhou Liying; Zhang Hong; Fu Jinxiang

    2010-01-01

    To prospectively determine if γH2AX (phosphorylated form of H2AX histone variant)-based visualization and quantification of DNA damage induced in peripheral blood mononuclear cells (PBMCs) can be used to estimate the radiation dose received after multi-detector computed tomography (CT) by the in vitro study, comprehend the correlation between the dose and the induced γH2AX foci, and explore its prospect. The result showed that, DNA damage first presented as γH2AX foci after CT, which can be detected by fluorescence microscope. The γH2AX focus yields linearly depend on the radiation dose after CT. γH2AX focus yield in blood cells may be a useful quantitative biomarker of human radiation exposure by CT scans. (authors)

  14. Study of the dose-effect relationship of γ-H2AX radiation

    International Nuclear Information System (INIS)

    Cui Shuangshuang; Fan Yaguang; Gun Zhijuan; Wang Jixian; Zhao Yongcheng; Sun Yuping

    2010-01-01

    Objective: By using laser scanning confocal microscopy (LSCM) to test the dose-effects relationship between ionizing radiation intensity and quantity of the γ-H2AX in vivo and in vitro respectively, and the consistency relationship between the vivo and vitro retrial. Methods: To irradiate the peripheral blood from Wister female rats by 137 Cs at 7 with different doses (0, 0.5, 1, 2, 2.54, 4, 6, 8 Gy) extract the lymphocytes from the peripheral blood and detect the dose-effects relationship between irradiation intensity and number of γ-H2AX foci. Results: There are good dose-effects relationships between the irradiation and foci number both in vivo and in vitro, which are linear, Y vivo =0.096+0.13X; Y vitro =0.040+0.21X. And there is good consistency (R=0.98) between the γ-H2AX in vivo and in vitro. Conclusions: γ-H2AX has the possibility for clinical trial as an indicator, and we can use vitro trials in place of the vivo trails to evaluate the dose people received. (authors)

  15. Residual γH2AX foci as an indication of lethal DNA lesions

    Directory of Open Access Journals (Sweden)

    Banuelos C Adriana

    2010-01-01

    Full Text Available Abstract Background Evidence suggests that tumor cells exposed to some DNA damaging agents are more likely to die if they retain microscopically visible γH2AX foci that are known to mark sites of double-strand breaks. This appears to be true even after exposure to the alkylating agent MNNG that does not cause direct double-strand breaks but does produce γH2AX foci when damaged DNA undergoes replication. Methods To examine this predictive ability further, SiHa human cervical carcinoma cells were exposed to 8 DNA damaging drugs (camptothecin, cisplatin, doxorubicin, etoposide, hydrogen peroxide, MNNG, temozolomide, and tirapazamine and the fraction of cells that retained γH2AX foci 24 hours after a 30 or 60 min treatment was compared with the fraction of cells that lost clonogenicity. To determine if cells with residual repair foci are the cells that die, SiHa cervical cancer cells were stably transfected with a RAD51-GFP construct and live cell analysis was used to follow the fate of irradiated cells with RAD51-GFP foci. Results For all drugs regardless of their mechanism of interaction with DNA, close to a 1:1 correlation was observed between clonogenic surviving fraction and the fraction of cells that retained γH2AX foci 24 hours after treatment. Initial studies established that the fraction of cells that retained RAD51 foci after irradiation was similar to the fraction of cells that retained γH2AX foci and subsequently lost clonogenicity. Tracking individual irradiated live cells confirmed that SiHa cells with RAD51-GFP foci 24 hours after irradiation were more likely to die. Conclusion Retention of DNA damage-induced γH2AX foci appears to be indicative of lethal DNA damage so that it may be possible to predict tumor cell killing by a wide variety of DNA damaging agents simply by scoring the fraction of cells that retain γH2AX foci.

  16. Residual γH2AX foci as an indication of lethal DNA lesions

    International Nuclear Information System (INIS)

    Banáth, Judit P; Klokov, Dmitry; MacPhail, Susan H; Banuelos, C Adriana; Olive, Peggy L

    2010-01-01

    Evidence suggests that tumor cells exposed to some DNA damaging agents are more likely to die if they retain microscopically visible γH2AX foci that are known to mark sites of double-strand breaks. This appears to be true even after exposure to the alkylating agent MNNG that does not cause direct double-strand breaks but does produce γH2AX foci when damaged DNA undergoes replication. To examine this predictive ability further, SiHa human cervical carcinoma cells were exposed to 8 DNA damaging drugs (camptothecin, cisplatin, doxorubicin, etoposide, hydrogen peroxide, MNNG, temozolomide, and tirapazamine) and the fraction of cells that retained γH2AX foci 24 hours after a 30 or 60 min treatment was compared with the fraction of cells that lost clonogenicity. To determine if cells with residual repair foci are the cells that die, SiHa cervical cancer cells were stably transfected with a RAD51-GFP construct and live cell analysis was used to follow the fate of irradiated cells with RAD51-GFP foci. For all drugs regardless of their mechanism of interaction with DNA, close to a 1:1 correlation was observed between clonogenic surviving fraction and the fraction of cells that retained γH2AX foci 24 hours after treatment. Initial studies established that the fraction of cells that retained RAD51 foci after irradiation was similar to the fraction of cells that retained γH2AX foci and subsequently lost clonogenicity. Tracking individual irradiated live cells confirmed that SiHa cells with RAD51-GFP foci 24 hours after irradiation were more likely to die. Retention of DNA damage-induced γH2AX foci appears to be indicative of lethal DNA damage so that it may be possible to predict tumor cell killing by a wide variety of DNA damaging agents simply by scoring the fraction of cells that retain γH2AX foci

  17. DNA DSB measurements and modelling approaches based on gamma-H2AX foci time evolution

    Science.gov (United States)

    Esposito, Giuseppe; Campa, Alessandro; Antonelli, Francesca; Mariotti, Luca; Belli, Mauro; Giardullo, Paola; Simone, Giustina; Antonella Tabocchini, Maria; Ottolenghi, Andrea

    DNA double strand breaks (DSBs) induced by ionising radiation are considered the main dam-age related to the deleterious consequences in the cells. Unrepaired or mis-repaired DSBs can cause mutations or loss of chromosome regions which can eventually lead to cell death or neo-plastic transformation. Quantification of the number and complexity of DSBs induced by low doses of radiation remains a complex problem. About ten years ago Rogakou et al. proposed an immunofluorescent technique able to detect even a single DSB per cell. This approach is based on the serine 139 phosphorylation of many molecules (up to 2000) of histone H2AX (γg-H2AX) following the induction of a DSB in the DNA. DSB can be visualized as foci by immunofluores-cence by using phospho-specific antibodies, so that enumeration of foci can be used to measure DSB induction and processing. It is still not completely clear how γ-H2AX dephosphorylation takes place; however it has been related with DSB repair, in particular with the efficiency of DSB repair. In this work we analyse the H2AX phosphorylation-dephosphorylation kinetics after irradiation of primary human fibroblasts (AG1522 cell line) with radiation of differing quality, that is γ-rays and α-particles (125 keV/µm), with the aim of comparing the time evolution of γ-H2AX foci. Our results show that, after a dose of 0.5 Gy, both γ-rays and α-particles induce the maximum number of γ-H2AX foci within 30 minutes from irradiation, that this number depends on the radiation type and is consistent with the number of track traversal in α-irradiated nuclei, that the dephosphorylation kinetics are very different, being the α-induced foci rate of disappearence slower than that of γ-induced foci. In this work a modellistic approach to estimate the number of DSB induced by γ-rays detectable by using the γ-H2AX assay is presented. The competing processes of appearance and disappearance of visible foci will be modeled taking into account the

  18. Effect of prolonging radiation delivery time on retention of gammaH2AX

    International Nuclear Information System (INIS)

    Moiseenko, Vitali; Banáth, Judit P; Duzenli, Cheryl; Olive, Peggy L

    2008-01-01

    Compared to conventional external beam radiotherapy, IMRT requires significantly more time to deliver the dose. Prolonging dose delivery potentially increases DNA repair which would reduce the biological effect. We questioned whether retention of γH2AX, a measure of lack of repair of DNA damage, would decrease when dose delivery was protracted. Exponentially growing SiHa cervical carinoma cells were irradiated with 6 MV photons in a water tank using a VarianEX linear accelerator. Cells held at 37°C received 2 Gy in 0.5 min and 4 Gy in 1 min. To evaluate effect of dose delivery prolongation, 2 and 4 Gy were delivered in 30 and 60 min. After 24 h recovery, cells were analyzed for clonogenic survival and for residual γH2AX as measured using flow cytometry. Increasing the dose delivery time from 0.5 or 1 min to 30 or 60 min produced a signficant increase in cell survival from 0.45 to 0.48 after 2 Gy, and from 0.17 to 0.20 after 4 Gy. Expression of residual γH2AX decreased from 1.27 to 1.22 relative to background after 2 Gy and 1.46 to 1.39 relative to background after 4 Gy, but differences were not statistically significant. The relative differences in the slopes of residual γH2AX versus dose for acute versus prolonged irradiation bordered on significant (p = 0.055), and the magnitude of the change was consistent with the observed increase in surviving fraction. These results support the concept that DNA repair underlies the increase in survival observed when dose delivery is prolonged. They also help to establish the limits of sensitivity of residual γH2AX, as measured using flow cytometry, for detecting differences in response to irradiation

  19. Q{sub {gamma}-H2AX}, an analysis method for partial-body radiation exposure using {gamma}-H2AX in non-human primate lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Redon, Christophe E., E-mail: redonc@mail.nih.gov [NIH, NCI, CCR, Laboratory of Molecular Pharmacology, Bethesda, MD 20892 (United States); Nakamura, Asako J.; Gouliaeva, Ksenia [NIH, NCI, CCR, Laboratory of Molecular Pharmacology, Bethesda, MD 20892 (United States); Rahman, Arifur; Blakely, William F. [Armed Forces Radiobiology Research Institute, Uniformed Services University, Bethesda, MD 20889-5603 (United States); Bonner, William M. [NIH, NCI, CCR, Laboratory of Molecular Pharmacology, Bethesda, MD 20892 (United States)

    2011-09-15

    We previously used the {gamma}-H2AX assay as a biodosimeter for total-body irradiation (TBI) exposure ({gamma}-rays) in a rhesus macaque (Macaca mulatta) model. Utilizing peripheral blood lymphocytes and plucked hairs, we obtained statistically significant {gamma}-H2AX responses days after total-body exposure to 1-8.5 Gy ({sup 60}Co {gamma}-rays at 55 cGy min{sup -1}). Here, we introduce a partial-body exposure analysis method, Q{sub {gamma}-H2AX}, which is based on the number of {gamma}-H2AX foci per damaged cells as evident by having one or more {gamma}-H2AX foci per cell. Results from the rhesus monkey - TBI study were used to establish Q{sub {gamma}-H2AX} dose-response calibration curves to assess acute partial-body exposures. {gamma}-H2AX foci were detected in plucked hairs for several days after in vivo irradiation demonstrating this assay's utility for dose assessment in various body regions. The quantitation of {gamma}-H2AX may provide a robust biodosimeter for analyzing partial-body exposures to ionizing radiation in humans.

  20. Spatiotemporal kinetics of γ-H2AX protein on charged particles induced DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Niu, H., E-mail: hniu@mx.nthu.edu.tw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Chang, H.C. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China); Cho, I.C. [Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan (China); Chen, C.H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Liu, C.S. [Cancer Center of Taipei Veterans General Hospital, Taipei, Taiwan (China); Chou, W.T. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China)

    2014-08-15

    Highlights: • Charged particles can induce more complex DNA damages, and these complex damages have higher ability to cause the cell death or cell carcinogenesis. • In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in particle irradiated HeLa cells. • The HeLa cells were irradiated by 400 keV alpha-particles in four different dosages. • The result shows that a good linear relationship can be observed between foci number and radiation dose. • The data shows that the dissolution rate of γ-H2AX foci agree with the two components DNA repairing model, and it was decreasing as the radiation dose increased. • These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA repair. - Abstract: In several researches, it has been demonstrated that charged particles can induce more complex DNA damages. These complex damages have higher ability to cause the cell death or cell carcinogenesis. For this reason, clarifying the DNA repair mechanism after charged particle irradiation plays an important role in the development of charged particle therapy and space exploration. Unfortunately, the detail spatiotemporal kinetic of DNA damage repair is still unclear. In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in alpha-particle irradiated HeLa cells. The result shows that the intensity of γ-H2AX foci increased gradually, and reached to its maximum at 30 min after irradiation. A good linear relationship can be observed between foci intensity and radiation dose. After 30 min, the γ-H2AX foci intensity was decreased with time passed, but remained a large portion (∼50%) at 48 h passed. The data show that the dissolution rate of γ-H2AX foci agreed with two components DNA repairing model. These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA

  1. Generation of an alpaca-derived nanobody recognizing γ-H2AX

    Science.gov (United States)

    Rajan, Malini; Mortusewicz, Oliver; Rothbauer, Ulrich; Hastert, Florian D.; Schmidthals, Katrin; Rapp, Alexander; Leonhardt, Heinrich; Cardoso, M. Cristina

    2015-01-01

    Post-translational modifications are difficult to visualize in living cells and are conveniently analyzed using antibodies. Single-chain antibody fragments derived from alpacas and called nanobodies can be expressed and bind to the target antigenic sites in living cells. As a proof of concept, we generated and characterized nanobodies against the commonly used biomarker for DNA double strand breaks γ-H2AX. In vitro and in vivo characterization showed the specificity of the γ-H2AX nanobody. Mammalian cells were transfected with fluorescent fusions called chromobodies and DNA breaks induced by laser microirradiation. We found that alternative epitope recognition and masking of the epitope in living cells compromised the chromobody function. These pitfalls should be considered in the future development and screening of intracellular antibody biomarkers. PMID:26500838

  2. γH2AX foci as a marker for DNA double-strand breaks

    International Nuclear Information System (INIS)

    Deckbar, Dorothee

    2009-01-01

    Full text: The DNA double-strand break (DSB) is the most deleterious lesion of all DNA damages. Left unrepaired or being mis-rejoined it can lead to chromosome aberrations which compromise the genomic stability and carry the potential to initiate carcinogenesis. So DSB repair mechanisms are under intensive investigation for many years. As older techniques had to utilize non-physiological doses to monitor DSB repair, they did not allow repair studies on the cellular level or after in vivo irradiation. But during the last years, an upcoming method allows the detection of a single DSB after physiologically relevant doses. To maintain the genomic integrity after the occurrence of a DSB, cellular mechanisms have evolved that detect and repair DSBs and even halt cell cycle progression to provide time for repair. In these processes, one of the first steps is the phosphorylation of the histone H2AX at serine 139 (γH2AX). Within minutes after DSB induction, large numbers of H2AX molecules are phosphorylated around the break site leading to the accumulation of proteins involved in chromatin remodelling, to damage signal amplification, and eventually to checkpoint activation and DSB repair. The finding that DSB-surrounding proteins can be visualized as foci in immunofluorescence microscopy opened up new opportunities in cancer biology and radiation biology. It was now for the first time possible to measure DSB repair after physiologically relevant doses of ionizing radiation, i.e. after doses used for therapeutic as well as for diagnostic purposes. First reports even describe the measurement of DSB repair after in vivo irradiation in mice and humans. This did not only improve the basic research investigating the mechanisms of DSB repair but also the research on low-dose effects and radiation protection. So the potential of γH2AX foci analysis as a predictive marker for radiosensitivity or radiation induced side effects is actually discussed. (author)

  3. Age-related disease association of endogenous γ-H2AX foci in mononuclear cells derived from leukapheresis.

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    Shepherd H Schurman

    Full Text Available The phosphorylated form of histone H2AX (γ-H2AX forms immunohistochemically detectable foci at DNA double strand breaks. In peripheral blood mononuclear cells (PBMCs derived from leukapheresis from patients enrolled in the Baltimore Longitudinal Study of Aging, γ-H2AX foci increased in a linear fashion with regards to age, peaking at ~57 years. The relationship between the frequency of γ-H2AX foci and age-related pathologies was assessed. We found a statistically significant (p = 0.023 50% increase in foci in PBMCs derived from patients with a known history of vitamin D deficiency. In addition, there were trends toward increased γ-H2AX foci in patients with cataracts (34% increase, p<0.10 and in sleep apnea patients (44%, p<0.10. Among patients ≥57 y/o, we found a significant (p = 0.037 36% increase in the number of γ-H2AX foci/cell for patients with hypertension compared to non-hypertensive patients. Our results support a role for increased DNA damage in the morbidity of age-related diseases. γ -H2AX may be a biomarker for human morbidity in age-related diseases.

  4. Super-Resolution Localization Microscopy of γ-H2AX and Heterochromatin after Folate Deficiency.

    Science.gov (United States)

    Bach, Margund; Savini, Claudia; Krufczik, Matthias; Cremer, Christoph; Rösl, Frank; Hausmann, Michael

    2017-08-08

    Folate is an essential water-soluble vitamin in food and nutrition supplements. As a one-carbon source, it is involved in many central regulatory processes, such as DNA, RNA, and protein methylation as well as DNA synthesis and repair. Deficiency in folate is considered to be associated with an increased incidence of several malignancies, including cervical cancer that is etiologically linked to an infection with "high-risk" human papilloma viruses (HPV). However, it is still not known how a recommended increase in dietary folate after its deprivation affects the physiological status of cells. To study the impact of folate depletion and its subsequent reconstitution in single cells, we used quantitative chromatin conformation measurements obtained by super-resolution fluorescence microscopy, i.e., single molecule localization microscopy (SMLM). As a read-out, we examined the levels and the (re)positioning of γ-H2AX tags and histone H3K9me3 heterochromatin tags after immunostaining in three-dimensional (3D)-conserved cell nuclei. As model, we used HPV16 positive immortalized human keratinocytes that were cultivated under normal, folate deficient, and reconstituted conditions for different periods of time. The results were compared to cells continuously cultivated in standard folate medium. After 13 weeks in low folate, an increase in the phosphorylation of the histone H2AX was noted, indicative of an accumulation of DNA double strand breaks. DNA repair activity represented by the formation of those γ-H2AX clusters was maintained during the following 15 weeks of examination. However, the clustered arrangements of tags appeared to relax in a time-dependent manner. Parallel to the repair activity, the chromatin methylation activity increased as detected by H3K9me3 tags. The progress of DNA double strand repair was accompanied by a reduction of the detected nucleosome density around the γ-H2AX clusters, suggesting a shift from hetero- to euchromatin to allow access

  5. DNA damage and γH2AX expression in EJ cells induced by 60Co gamma-rays

    International Nuclear Information System (INIS)

    Pan Yan; Tian Mei; Liu Jianxiang; Ruan Jianlei; Su Xu

    2009-01-01

    Objective: To investigate 60 Co γ-rays induced DNA damage of human bladder cancer cell line EJ cells and the relationship between different doses of 60 Co γ-rays, γH2AX foci number and γH2AX expression level. Methods: EJ cells were exposed to different doses of 60 Co γ-rays and the oliver tail moment (TM) of EJ cells were analyzed with single cell gel electrophoresis (SCGE) . Immunofluorescent microscopy was used to analysis γH2AX foci formation in EJ cells after exposure to different doses of γ-ray irradiation and time-course after exposure to 2 Gy γ-ray irradiation. FACSAria was used to detect the changes of γH2AX protein expression in EJ cells. Results: The TMs of EJ cells were increased with the irradiation dose. The TM of 0 Gy group and 4 Gy group was 0.24 and 5.26, respectively. Immunofluorescent analysis demonstrated that γH2AX foci could be induced by γ-ray irradiation in dose-dependent and time-dependent manners. The foci number and size in nuclei of EJ cells was significantly increased after exposed to different doses of γ-ray irradiation and the foci remained detectable at 24 h after exposed to irradiation. The dose range in which foci could be clearly detected was from 0.1 to 4 Gy. FACSDiva showed that γH2AX protein expression was increased after exposure to different doses of γ-ray irradiation. γH2AX protein expression level of 0.1 Gy group and 4 Gy group was 7.4% and 29.2% , respectively. Conclusions: γH2AX foci could be the most sensitive indicator for DNA damage and repair in mammalian cells, and it might be a new biomarker for radiological emergency. (authors)

  6. Adapting the γ-H2AX assay for automated processing in human lymphocytes. 1. Technological aspects.

    Science.gov (United States)

    Turner, Helen C; Brenner, David J; Chen, Youhua; Bertucci, Antonella; Zhang, Jian; Wang, Hongliang; Lyulko, Oleksandra V; Xu, Yanping; Shuryak, Igor; Schaefer, Julia; Simaan, Nabil; Randers-Pehrson, Gerhard; Yao, Y Lawrence; Amundson, Sally A; Garty, Guy

    2011-03-01

    The immunofluorescence-based detection of γ-H2AX is a reliable and sensitive method for quantitatively measuring DNA double-strand breaks (DSBs) in irradiated samples. Since H2AX phosphorylation is highly linear with radiation dose, this well-established biomarker is in current use in radiation biodosimetry. At the Center for High-Throughput Minimally Invasive Radiation Biodosimetry, we have developed a fully automated high-throughput system, the RABIT (Rapid Automated Biodosimetry Tool), that can be used to measure γ-H2AX yields from fingerstick-derived samples of blood. The RABIT workstation has been designed to fully automate the γ-H2AX immunocytochemical protocol, from the isolation of human blood lymphocytes in heparin-coated PVC capillaries to the immunolabeling of γ-H2AX protein and image acquisition to determine fluorescence yield. High throughput is achieved through the use of purpose-built robotics, lymphocyte handling in 96-well filter-bottomed plates, and high-speed imaging. The goal of the present study was to optimize and validate the performance of the RABIT system for the reproducible and quantitative detection of γ-H2AX total fluorescence in lymphocytes in a multiwell format. Validation of our biodosimetry platform was achieved by the linear detection of a dose-dependent increase in γ-H2AX fluorescence in peripheral blood samples irradiated ex vivo with γ rays over the range 0 to 8 Gy. This study demonstrates for the first time the optimization and use of our robotically based biodosimetry workstation to successfully quantify γ-H2AX total fluorescence in irradiated peripheral lymphocytes.

  7. miR-24-mediated down-regulation of H2AX suppresses DNA repair in terminally differentiated blood cells

    Science.gov (United States)

    Lal, Ashish; Pan, Yunfeng; Navarro, Francisco; Dykxhoorn, Derek M.; Moreau, Lisa; Meire, Eti; Bentwich, Zvi; Lieberman, Judy; Chowdhury, Dipanjan

    2010-01-01

    Terminally differentiated cells have reduced capacity to repair double strand breaks (DSB), but the molecular mechanism behind this down-regulation is unclear. Here we find that miR-24 is consistently up-regulated during post-mitotic differentiation of hematopoietic cell lines and regulates the histone variant H2AX, a key DSB repair protein that activates cell cycle checkpoint proteins and retains DSB repair factors at DSB foci. The H2AX 3’UTR contains conserved miR-24 binding sites regulated by miR-24. Both H2AX mRNA and protein are substantially reduced during hematopoietic cell terminal differentiation by miR-24 up-regulation both in in vitro differentiated cells and primary human blood cells. miR-24 suppression of H2AX renders cells hypersensitive to γ-irradiation and genotoxic drugs. Antagonizing miR-24 in differentiating cells protects them from DNA damage-induced cell death, while transfecting miR-24 mimics in dividing cells increases chromosomal breaks and unrepaired DNA damage and reduces viability in response to DNA damage. This DNA repair phenotype can be fully rescued by over-expressing miR-24-insensitive H2AX. Therefore, miR-24 up-regulation in post-replicative cells reduces H2AX and thereby renders them highly vulnerable to DNA damage. PMID:19377482

  8. NBS1 localizes to gamma-H2AX foci through interaction with the FHA/BRCT domain

    International Nuclear Information System (INIS)

    Kobayashi, J.; Chen, D.J.; Sakamoto, S.; Matsuura, S.; Tanimoto, K.; Komatsu, K.

    2003-01-01

    Full text: DNA double-strand breaks (DSBs) represent the most potentially serious damage to a genome, and hence, many repair proteins are recruited to nuclear damage sites by as yet poorly characterized sensor mechanisms. Histone H2AX, one of histone H2A family, is phosphorylated within a few minutes in response to ionizing radiation (IR) and the phosphorylated H2AX (gamma-H2AX) forms foci at the region of DSBs. Moreover, Histone H2AX is essential for the IR-induced focus formation of DNA repair proteins such as BRCA1, NBS1 and 53BP1. Hence, we investigated that the function of histone H2AX for the recruitment of NBS1/hMRE11/ hRAD50 complex to DSBs sites. We clarify that NBS1 physically interacts with histone H2AX independent of DNA. We also show that the NBS1-binding can occur in the absence of interaction with hMRE11 or BRCA1. Furthermore, this NBS1 physical interaction was reduced when anti-gamma-H2AX antibody was introduced into normal cells. We also demonstrate that the FHA/BRCT domain of NBS1 is essential for this physical interaction by the immunoprecipitation studies and a pull-down assay with recombinant FHA/BRCT domain. These findings suggest that the FHA/BRCT domain have a crucial role for both binding to histone and for re-localization of hMRE11/hRAD50 nuclease complex to the vicinity of DNA damage

  9. High throughput measurement of γH2AX DSB repair kinetics in a healthy human population.

    Directory of Open Access Journals (Sweden)

    Preety M Sharma

    Full Text Available The Columbia University RABiT (Rapid Automated Biodosimetry Tool quantifies DNA damage using fingerstick volumes of blood. One RABiT protocol quantifies the total γ-H2AX fluorescence per nucleus, a measure of DNA double strand breaks (DSB by an immunofluorescent assay at a single time point. Using the recently extended RABiT system, that assays the γ-H2AX repair kinetics at multiple time points, the present small scale study followed its kinetics post irradiation at 0.5 h, 2 h, 4 h, 7 h and 24 h in lymphocytes from 94 healthy adults. The lymphocytes were irradiated ex vivo with 4 Gy γ rays using an external Cs-137 source. The effect of age, gender, race, ethnicity, alcohol use on the endogenous and post irradiation total γ-H2AX protein yields at various time points were statistically analyzed. The endogenous γ-H2AX levels were influenced by age, race and alcohol use within Hispanics. In response to radiation, induction of γ-H2AX yields at 0.5 h and peak formation at 2 h were independent of age, gender, ethnicity except for race and alcohol use that delayed the peak to 4 h time point. Despite the shift in the peak observed, the γ-H2AX yields reached close to baseline at 24 h for all groups. Age and race affected the rate of progression of the DSB repair soon after the yields reached maximum. Finally we show a positive correlation between endogenous γ-H2AX levels with radiation induced γ-H2AX yields (RIY (r=0.257, P=0.02 and a negative correlation with residuals (r=-0.521, P=<0.0001. A positive correlation was also observed between RIY and DNA repair rate (r=0.634, P<0.0001. Our findings suggest age, race, ethnicity and alcohol use influence DSB γ-H2AX repair kinetics as measured by RABiT immunofluorescent assay.

  10. Radiosensitivity in breast cancer assessed by the histone γ-H2AX and 53BP1 foci

    International Nuclear Information System (INIS)

    Djuzenova, Cholpon S; Elsner, Ines; Katzer, Astrid; Worschech, Eike; Distel, Luitpold V; Flentje, Michael; Polat, Bülent

    2013-01-01

    High expression of constitutive histone γ-H2AX, a sensitive marker of DNA damage, might be indicative of defective DNA repair pathway or genomic instability. 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor. This study explores the relationship between the clinical radiosensitivity of tumor patients and the expression/induction of γ-H2AX and 53BP1 in vitro. Using immunostaining, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53 BP1 in peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=57) undergoing radiotherapy (RT). Cells from apparently healthy donors (n=12) served as references. Non-irradiated cells from controls and unselected BC patients exhibited similar baseline levels of DNA damage assessed by γ-H2AX and 53BP1 foci. At the same time, the γ-H2AX assay of in vitro irradiated cells revealed significant differences between the control group and the group of unselected BC patients with respect to the initial (0.5 Gy, 30 min) and residual (2 Gy, 24 h post-radiation) DNA damage. The numbers of 53BP1 foci analyzed in 35 BC patients were significantly higher than in controls only in case of residual DNA damage. A weak correlation was found between residual foci of both proteins tested. In addition, cells from cancer patients with an adverse acute skin reaction (grade 3) to RT showed significantly increased radiation-induced γ-H2AX foci and their protracted disappearance compared to the group of BC patients with normal skin reaction (grade 0–1). The mean number of γ-H2AX foci after 5 clinical fractions was significantly higher than that before RT, especially in clinically radiosensitive patients. The γ-H2AX assay may have potential for screening individual radiosensitivity of breast cancer patients.

  11. The foci of DNA double strand break-recognition proteins localize with γH2AX after heat treatment

    International Nuclear Information System (INIS)

    Takahashi, Akihisa; Mori, Eiichiro; Ohnishi, Takeo

    2010-01-01

    Recently, there have been many reports concerning proteins which can recognize DNA double strand break (DSBs), and such proteins include histone H2AX phosphorylated at serine 139 (γH2AX), ataxia telangiectasia mutated (ATM) phospho-serine 1981, DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phospho-threonine 2609, Nijmegen breakage syndrome 1 (NBS1) phospho-serine 343, checkpoint kinase 2 (CHK2), phospho-threonine 68, and structural maintenance of chromosomes 1 (SMC1) phospho-serine 966. Thus, it should be possible to follow the formation of DSBs and their repair using immunohistochemical methods with multiple antibodies to detect these proteins. When normal human fibroblasts (AG1522 cells) were exposed to 3 Gy of X-rays as a control, clearly discernable foci for these proteins were detected, and these foci localized with γH2AX foci. After heat treatment at 45.5 deg C for 20 min, these proteins are partially localized with γH2AX foci. Here we show that there were slight differences in the localization pattern among these proteins, such as a disappearance from the nucleus (phospho-ATM) and translocation to the cytoplasm (phospho-NBS1) at 30 min after heat treatment, and some foci (phospho-DNA-PKcs and phospho-CHK2) appeared at 8 h after heat treatment. These results are discussed from perspectives of heat-induced denaturation of proteins and formation of DSBs. (author)

  12. Quantitative evaluation of radiation dose by γ-H2AX on a microfluidic chip in a miniature fluorescence cytometer

    International Nuclear Information System (INIS)

    Wang, Junsheng; Song, Wendong; Song, Yongxin; Xu, Dan; Zhang, Min; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

    2014-01-01

    Evaluation of radiation dose is very important for the detection of radiation damage. γ-H2AX is a popular biological dosimeter to evaluate the radiation effect. Typically, bulky and expensive commercial flow cytometers are used to detect γ-H2AX. This paper presents a miniaturized and high sensitive cytometer using a microfluidic chip for evaluating the radiation dose by detecting the mean immunofluorescence intensity of γ-H2AX. A compact optical focusing system and a shift-phase differential amplifier are designed to improve the detection sensitivity. Sample lymphocyte cells are stained by FITC fluorescent dye after being irradiated by UVC. Comparison experiments between the developed miniature cytometer and a commercial flow cytometer were conducted under different radiation doses. The developed microfluidic cytometer also demonstrates a good linear correlation between the measured fluorescence intensity and the irradiation dose with a detection limit similar to that of the commercial flow cytometer. The developed cytometer can evaluate quantitatively the radiation dose by the mean fluorescence intensity of γ-H2AX with a significantly smaller amount of blood samples than a commercial flow cytometer. - Highlights: • A new microfluidic cytometer for evaluating irradiation dose was developed. • The utility of this biosensor is verified by comparison experiments using FCM. • The developed cytometer is small size, high sensitivity, low cost, and simple. • The cytometer can dramatically reduce sample consumption and analysis time

  13. Genotoxicity testing: Comparison of the γH2AX focus assay with the alkaline and neutral comet assays.

    Science.gov (United States)

    Nikolova, Teodora; Marini, Federico; Kaina, Bernd

    2017-10-01

    Genotoxicity testing relies on the quantitative measurement of adverse effects, such as chromosome aberrations, micronuclei, and mutations, resulting from primary DNA damage. Ideally, assays will detect DNA damage and cellular responses with high sensitivity, reliability, and throughput. Several novel genotoxicity assays may fulfill these requirements, including the comet assay and the more recently developed γH2AX assay. Although they are thought to be specific for genotoxicants, a systematic comparison of the assays has not yet been undertaken. In the present study, we compare the γH2AX focus assay with the alkaline and neutral versions of the comet assay, as to their sensitivities and limitations for detection of genetic damage. We investigated the dose-response relationships of γH2AX foci and comet tail intensities at various times following treatment with four prototypical genotoxicants, methyl methanesulfonate (MMS), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), mitomycin C, and hydrogen peroxide (H 2 O 2 ) and we tested whether there is a correlation between the endpoints, i.e., alkali-labile sites and DNA strand breaks on the one hand and the cell's response to DNA double-strand breaks and blocked replication forks on the other. Induction of γH2AX foci gave a linear dose response and all agents tested were positive in the assay. The increase in comet tail intensity was also a function of dose; however, mitomycin C was almost completely ineffective in the comet assay, and the doses needed to achieve a significant effect were somewhat higher for some treatments in the comet assay than in the γH2AX foci assay, which was confirmed by threshold analysis. There was high correlation between tail intensity and γH2AX foci for MMS and H 2 O 2 , less for MNNG, and none for mitomycin C. From this we infer that the γH2AX foci assay is more reliable, sensitive, and robust than the comet assay for detecting genotoxicant-induced DNA damage. Copyright © 2017 Elsevier

  14. Dose-response relationship of γ-H2AX foci induction in human lymphocytes after X-rays exposure

    International Nuclear Information System (INIS)

    Mandina, Tania; Roch-Lefevre, Sandrine H.; Voisin, Pascale; Gonzalez, Jorge E.; Lamadrid, Ana I.; Romero, Ivonne; Garcia, Omar; Voisin, Philippe; Roy, Laurence

    2011-01-01

    Biological dosimeters are recommended for dose estimation in case of human overexposure to ionising radiation. Rapid measurement of γ-H2AX foci as a marker of DNA double-strand breaks (DSB) induction has been recently tested with this purpose. Here we reported a dose-response relationship after X-ray irradiation at different times post-exposure. Blood samples were obtained from several healthy donors and exposed to doses between 0 and 2 Gy. After irradiation, blood samples were incubated at 37 deg. C during 0.5 h, 5 h, and 8 h. Scoring of cells and γ-H2AX foci was performed by software. The dose-response curves for different incubation times were as follows: Y (0.5h) = 11.66D + 0.15 (R 2 = 0.99), Y (5h) = 2.44D + 0.15 (R 2 = 0.99), Y (8h) = 1.57D + 0.22 (R 2 = 0.99). At 0.5 h post-exposure, the dose-response relationship for X-irradiated lymphocytes was similar to the one obtained after gamma-irradiation using the same protocol. On the other hand, the results were not similar after 8 h due to different kinetics after gamma- and X-irradiation. Our results confirm the possibilities of using γ-H2AX foci method for dose estimation in a period from 0.5 h up to 8 h post X-irradiation and support the hypothesis of differences in γ-H2AX foci kinetics after gamma- and X-irradiation in vitro.

  15. Dose-response relationship of {gamma}-H2AX foci induction in human lymphocytes after X-rays exposure

    Energy Technology Data Exchange (ETDEWEB)

    Mandina, Tania [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Roch-Lefevre, Sandrine H.; Voisin, Pascale [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France); Gonzalez, Jorge E.; Lamadrid, Ana I.; Romero, Ivonne [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Garcia, Omar, E-mail: omar@cphr.edu.cu [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Voisin, Philippe; Roy, Laurence [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France)

    2011-09-15

    Biological dosimeters are recommended for dose estimation in case of human overexposure to ionising radiation. Rapid measurement of {gamma}-H2AX foci as a marker of DNA double-strand breaks (DSB) induction has been recently tested with this purpose. Here we reported a dose-response relationship after X-ray irradiation at different times post-exposure. Blood samples were obtained from several healthy donors and exposed to doses between 0 and 2 Gy. After irradiation, blood samples were incubated at 37 deg. C during 0.5 h, 5 h, and 8 h. Scoring of cells and {gamma}-H2AX foci was performed by software. The dose-response curves for different incubation times were as follows: Y{sub (0.5h)} = 11.66D + 0.15 (R{sup 2} = 0.99), Y{sub (5h)} = 2.44D + 0.15 (R{sup 2} = 0.99), Y{sub (8h)} = 1.57D + 0.22 (R{sup 2} = 0.99). At 0.5 h post-exposure, the dose-response relationship for X-irradiated lymphocytes was similar to the one obtained after gamma-irradiation using the same protocol. On the other hand, the results were not similar after 8 h due to different kinetics after gamma- and X-irradiation. Our results confirm the possibilities of using {gamma}-H2AX foci method for dose estimation in a period from 0.5 h up to 8 h post X-irradiation and support the hypothesis of differences in {gamma}-H2AX foci kinetics after gamma- and X-irradiation in vitro.

  16. Use of γ-H2AX Foci Assay on Human Peripheral Blood Lymphocytes as Sensitive Biomarker of Exposure

    International Nuclear Information System (INIS)

    Gajski, G.; Garaj-Vrhovac, V.; Geric, M.; Filipic, M.; Nunic, J.; Straser, A.; Zegura, B.

    2013-01-01

    In modern medicine, it is impossible to imagine diagnostics and treatments without equipment that emit radiation (X-ray, CT, PET, etc.). At the same time there is a need to minimize the amount of radiation that the patient will gain during such medical examination. In that manner ALARA (As Low As Reasonably Achievable) principle and dosimetry are the bases of assuring patients safety. The induction of gamma phosphorylated H2AX histone is newly developed tool in biodosimetry, which is more sensitive for the detection of radiation caused DNA damage than currently used micronucleus and comet assay. Gamma phosphorylation of H2AX histone is a consequence of DNA double strand breaks and its role is to trigger the DNA repair mechanisms. In this study, we tested the effect of 2 and 4 Gy X-rays on human peripheral blood lymphocytes from two healthy volunteers using γ-H2AX foci assay. The FITC signal from labelled antibodies was monitored using flow cytometry and clearly demonstrated the difference in control samples and irradiated samples. There was also the difference between the exposed blood samples from the two volunteers. The results of present study reveal new sensitive method that is capable of detecting changes in DNA when exposed to different doses of radiation, and thus potentially optimizing the ALARA principle.(author)

  17. Systematic identification of fragile sites via genome-wide location analysis of γ-H2AX

    Science.gov (United States)

    Szilard, Rachel K.; Jacques, Pierre-Étienne; Laramée, Louise; Cheng, Benjamin; Galicia, Sarah; Bataille, Alain R.; Yeung, ManTek; Mendez, Megan; Bergeron, Maxime; Robert, François; Durocher, Daniel

    2011-01-01

    Phosphorylation of histone H2AX is an early response to DNA damage in eukaryotes. In Saccharomyces cerevisiae, DNA damage or replication fork stalling results in histone H2A phosphorylation to yield γ-H2A (yeast γ-H2AX) in a Mec1 (ATR)- and Tel1 (ATM)- dependent manner. Here, we describe the genome-wide location analysis of γ-H2A as a strategy to identify loci prone to engage the Mec1 and Tel1 pathways. Remarkably, γ-H2A enrichment overlaps with loci prone to replication fork stalling and is caused by the action of Mec1 and Tel1, indicating that these loci are prone to breakage. Moreover, about half the sites enriched for γ-H2A map to repressed protein-coding genes, and histone deacetylases are necessary for formation of γ-H2A at these loci. Finally, our work indicates that high resolution mapping of γ-H2AX is a fruitful route to map fragile sites in eukaryotic genomes. PMID:20139982

  18. Effect of mild temperature shift on poly(ADP-ribose) and γH2AX levels in cultured cells

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, Sachiko [Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Tanaka, Masakazu [Department of Microbiology, Kansai Medical University, 2-5-1 Shin-machi, Hirakata City, Osaka 573-1010 (Japan); Sato, Teruaki [Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Ida, Chieri [Department of Applied Life Studies, College of Nagoya Women’s University, 3-40 Shioji-cho, Mizuho-ku, Nagoya-shi, Aichi 467-8610 (Japan); Ohta, Narumi; Hamada, Takashi; Uetsuki, Taichi; Nishi, Yoshisuke [Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan); Moss, Joel [Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1590 (United States); Miwa, Masanao, E-mail: m_miwa@nagahama-i-bio.ac.jp [Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829 (Japan)

    2016-08-05

    Poly (ADP-ribose) (PAR) is rapidly synthesized by PAR polymerases (PARPs) upon activation by DNA single- and double-strand breaks. In this study, we examined the quantitative amount of PAR in HeLa cells cultured within the physiological temperatures below 41 °C for verification of the effect of shifting-up or -down the temperature from 37.0 °C on the DNA breaks, whether the temperature-shift caused breaks that could be monitored by the level of PAR. While PAR level did not change significantly when HeLa cells were cultured at 33.5 °C or 37.0 °C, it was significantly increased 2- and 3-fold when cells were cultured for 12 h and 24 h, respectively, at 40.5 °C as compared to 37.0 °C. Similar to the results with HeLa cells, PAR level was increased 2-fold in CHO-K1 cells cultured at 40.5 °C for 24 h as compared to 37.0 °C. As the cellular levels of PAR polymerase1 (PARP1) and PAR glycohydrolase (PARG), a major degradation enzyme for PAR, did not seem to change significantly, this increase could be caused by activation of PARP1 by DNA strand breaks. In fact, γH2AX, claimed to be a marker of DNA double-strand breaks, was found in cell extracts of HeLa cells and CHO-K1 cells at elevated temperature vs. 37.0 °C, and these γH2AX signals were intensified in the presence of 3-aminobenzamide, a PARP inhibitor. The γH2AX immunohistochemistry results in HeLa cells were consistent with Western blot analyses. In HeLa cells, proliferation was significantly suppressed at 40.5 °C in 72 h-continuous cultures and decreased viabilities were also observed after 24–72 h at 40.5 °C. Flow cytometric analyses showed that the HeLa cells were arrested at G2/M after temperature shift-up to 40.5 °C. These physiological changes were potentiated in the presence of 3-aminobenzamide. Decrease in growth rates, increased cytotoxicity and G2/M arrest, were associated with the temperature-shift to 40.5 °C and are indirect evidence of DNA breaks. In addition to γH2AX

  19. Effect of mild temperature shift on poly(ADP-ribose) and γH2AX levels in cultured cells

    International Nuclear Information System (INIS)

    Yamashita, Sachiko; Tanaka, Masakazu; Sato, Teruaki; Ida, Chieri; Ohta, Narumi; Hamada, Takashi; Uetsuki, Taichi; Nishi, Yoshisuke; Moss, Joel; Miwa, Masanao

    2016-01-01

    Poly (ADP-ribose) (PAR) is rapidly synthesized by PAR polymerases (PARPs) upon activation by DNA single- and double-strand breaks. In this study, we examined the quantitative amount of PAR in HeLa cells cultured within the physiological temperatures below 41 °C for verification of the effect of shifting-up or -down the temperature from 37.0 °C on the DNA breaks, whether the temperature-shift caused breaks that could be monitored by the level of PAR. While PAR level did not change significantly when HeLa cells were cultured at 33.5 °C or 37.0 °C, it was significantly increased 2- and 3-fold when cells were cultured for 12 h and 24 h, respectively, at 40.5 °C as compared to 37.0 °C. Similar to the results with HeLa cells, PAR level was increased 2-fold in CHO-K1 cells cultured at 40.5 °C for 24 h as compared to 37.0 °C. As the cellular levels of PAR polymerase1 (PARP1) and PAR glycohydrolase (PARG), a major degradation enzyme for PAR, did not seem to change significantly, this increase could be caused by activation of PARP1 by DNA strand breaks. In fact, γH2AX, claimed to be a marker of DNA double-strand breaks, was found in cell extracts of HeLa cells and CHO-K1 cells at elevated temperature vs. 37.0 °C, and these γH2AX signals were intensified in the presence of 3-aminobenzamide, a PARP inhibitor. The γH2AX immunohistochemistry results in HeLa cells were consistent with Western blot analyses. In HeLa cells, proliferation was significantly suppressed at 40.5 °C in 72 h-continuous cultures and decreased viabilities were also observed after 24–72 h at 40.5 °C. Flow cytometric analyses showed that the HeLa cells were arrested at G2/M after temperature shift-up to 40.5 °C. These physiological changes were potentiated in the presence of 3-aminobenzamide. Decrease in growth rates, increased cytotoxicity and G2/M arrest, were associated with the temperature-shift to 40.5 °C and are indirect evidence of DNA breaks. In addition to γH2AX

  20. Plant γH2AX foci are required for proper DNA DSB repair responses and colocalize with E2F factors

    OpenAIRE

    Smetana, Ondrej; Sanchez-Calderon, Lenin; Lincker, Frédéric; Genestier, Julie; Schmit, Anne-Catherine; Houlné, Guy; Chabouté, Marie Edith

    2012-01-01

    Cellular responses to DNA double-strand breaks (DSBs) are linked in mammals and yeasts to the phosphorylated histones H2AX (cH2AX) repair foci which are multiproteic nuclear complexes responsible for DSB sensing and signalling. However, neither the components of these foci nor their role are yet known in plants. In this paper, we describe the effects of cH2AX deficiency in Arabidopsis thaliana plants challenged with DSBs in terms of genotoxic sensitivity and E2F-mediated transcriptional respo...

  1. High levels of γ-H2AX foci and cell membrane oxidation in adolescents with type 1 diabetes

    International Nuclear Information System (INIS)

    Giovannini, Caterina; Piaggi, Simona; Federico, Giovanni; Scarpato, Roberto

    2014-01-01

    Highlights: • We aimed to detect signs of very early damage in peripheral cells of T1DM adolescents. • T1DM patients had high levels of oxidized cells and reduced expression of iNOS and NO. • Highly mutagenic lesions were markedly increased in the diabetic group, mainly in females. • The observed damage might increase the risk of cancer in the patients later in life. - Abstract: Oxidative stress caused by an excess of free radicals is implicated in the pathogenesis and development of type 1 diabetes mellitus (T1DM) and, in turn, it can lead to genome damage, especially in the form of DNA double-strand break (DSB). The DNA DSB is a potentially carcinogenic lesion for human cells. Thus, we aimed to evaluate whether the level of oxidative stress was increased in peripheral blood lymphocytes of a group of affected adolescents. In 35 T1DM adolescents and 19 healthy controls we assessed: (1) spontaneous and H 2 O 2 -induced oxidation of cell membrane using a fluorescence lipid probe; (2) spontaneous and LPS-induced expression of iNOS protein and indirect NO determination via cytofluorimetric analysis of O 2 − ; (3) immunofluorescent detection of the basal level of histone H2AX phosphorylation (γ-H2AX foci), a well-validated marker of DNA DSB. In T1DM, the frequencies of oxidized cells, both spontaneous and H 2 O 2 -induced (47.13 ± 0.02) were significantly higher than in controls (35.90 ± 0.03). Patients showed, in general, both a reduced iNOS expression and production of NO. Furthermore, the level of spontaneous nuclear damage, quantified as γ-H2AX foci, was markedly increased in T1DM adolescents (6.15 ± 1.08% of γ-H2AX + cells; 8.72 ± 2.14 γ-H2AXF/n; 9.26 ± 2.37 γ-H2AXF/np), especially in females. In the present study, we confirmed the role that oxidative stress plays in the disease damaging lipids of cell membrane and, most importantly, causing genomic damage in circulating white blood cells of affected adolescents. This also indicates that

  2. Evaluation of the efficacy of radiation-modifying compounds using γH2AX as a molecular marker of DNA double-strand breaks.

    Science.gov (United States)

    Mah, Li-Jeen; Orlowski, Christian; Ververis, Katherine; Vasireddy, Raja S; El-Osta, Assam; Karagiannis, Tom C

    2011-01-25

    Radiation therapy is a widely used therapeutic approach for cancer. To improve the efficacy of radiotherapy there is an intense interest in combining this modality with two broad classes of compounds, radiosensitizers and radioprotectors. These either enhance tumour-killing efficacy or mitigate damage to surrounding non-malignant tissue, respectively. Radiation exposure often results in the formation of DNA double-strand breaks, which are marked by the induction of H2AX phosphorylation to generate γH2AX. In addition to its essential role in DDR signalling and coordination of double-strand break repair, the ability to visualize and quantitate γH2AX foci using immunofluorescence microscopy techniques enables it to be exploited as an indicator of therapeutic efficacy in a range of cell types and tissues. This review will explore the emerging applicability of γH2AX as a marker for monitoring the effectiveness of radiation-modifying compounds.

  3. Replication protein A and γ-H2AX foci assembly is triggered by cellular response to DNA double-strand breaks

    International Nuclear Information System (INIS)

    Balajee, Adayabalam S.; Geard, Charles R.

    2004-01-01

    Human replication protein A (RPA p34), a crucial component of diverse DNA excision repair pathways, is implicated in DNA double-strand break (DSB) repair. To evaluate its role in DSB repair, the intranuclear dynamics of RPA was investigated after DNA damage and replication blockage in human cells. Using two different agents [ionizing radiation (IR) and hydroxyurea (HU)] to generate DSBs, we found that RPA relocated into distinct nuclear foci and colocalized with a well-known DSB binding factor, γ-H2AX, at the sites of DNA damage in a time-dependent manner. Colocalization of RPA and γ-H2AX foci peaked at 2 h after IR treatment and subsequently declined with increasing postrecovery times. The time course of RPA and γ-H2AX foci association correlated well with the DSB repair activity detected by a neutral comet assay. A phosphatidylinositol-3 (PI-3) kinase inhibitor, wortmannin, completely abolished both RPA and γ-H2AX foci formation triggered by IR. Additionally, radiosensitive ataxia telangiectasia (AT) cells harboring mutations in ATM gene product were found to be deficient in RPA and γ-H2AX colocalization after IR. Transfection of AT cells with ATM cDNA fully restored the association of RPA foci with γ-H2AX illustrating the requirement of ATM gene product for this process. The exact coincidence of RPA and γ-H2AX in response to HU specifically in S-phase cells supports their role in DNA replication checkpoint control. Depletion of RPA by small interfering RNA (SiRNA) substantially elevated the frequencies of IR-induced micronuclei (MN) and apoptosis in human cells suggestive of a role for RPA in DSB repair. We propose that RPA in association with γ-H2AX contributes to both DNA damage checkpoint control and repair in response to strand breaks and stalled replication forks in human cells

  4. γ-H2AX as a biomarker of DNA damage induced by ionizing radiation in human peripheral blood lymphocytes and artificial skin

    Science.gov (United States)

    Redon, Christophe E.; Dickey, Jennifer S.; Bonner, William M.; Sedelnikova, Olga A.

    2009-04-01

    Ionizing radiation (IR) exposure is inevitable in our modern society and can lead to a variety of deleterious effects including cancer and birth defects. A reliable, reproducible and sensitive assessment of exposure to IR and the individual response to that exposure would provide much needed information for the optimal treatment of each donor examined. We have developed a diagnostic test for IR exposure based on detection of the phosphorylated form of variant histone H2AX (γ-H2AX), which occurs specifically at sites of DNA double-strand breaks (DSBs). The cell responds to a nascent DSB through the phosphorylation of thousands of H2AX molecules flanking the damaged site. This highly amplified response can be visualized as a γ-H2AX focus in the chromatin that can be detected in situ with the appropriate antibody. Here we assess the usability of γ-H2AX focus formation as a possible biodosimeter for human exposure to IR using peripheral blood lymphocytes irradiated ex vivo and three-dimensional artificial models of human skin biopsies. In both systems, the tissues were exposed to 0.2-5 Gy, doses of IR that might be realistically encountered in various scenarios such as cancer radiotherapies or accidental exposure to radiation. Since the γ-H2AX response is maximal 30 min after exposure and declines over a period of hours as the cells repair the damage, we examined the time limitations of the useful detectability of γ-H2AX foci. We report that a linear response proportional to the initial radiation dose was obtained 48 and 24 h after exposure in blood samples and skin cells respectively. Thus, detection of γ-H2AX formation to monitor DNA damage in minimally invasive blood and skin tests could be useful tools to determine radiation dose exposure and analyze its effects on humans.

  5. Low doses of X-rays induce prolonged and ATM-independent persistence of γH2AX foci in human gingival mesenchymal stem cells.

    Science.gov (United States)

    Osipov, Andreyan N; Pustovalova, Margarita; Grekhova, Anna; Eremin, Petr; Vorobyova, Natalia; Pulin, Andrey; Zhavoronkov, Alex; Roumiantsev, Sergey; Klokov, Dmitry Y; Eremin, Ilya

    2015-09-29

    Diagnostic imaging delivering low doses of radiation often accompany human mesenchymal stem cells (MSCs)-based therapies. However, effects of low dose radiation on MSCs are poorly characterized. Here we examine patterns of phosphorylated histone H2AXH2AX) and phospho-S1981 ATM (pATM) foci formation in human gingiva-derived MSCs exposed to X-rays in time-course and dose-response experiments. Both γH2AX and pATM foci accumulated linearly with dose early after irradiation (5-60 min), with a maximum induction observed at 30-60 min (37 ± 3 and 32 ± 3 foci/cell/Gy for γH2AX and pATM, respectively). The number of γH2AX foci produced by intermediate doses (160 and 250 mGy) significantly decreased (40-60%) between 60 and 240 min post-irradiation, indicating rejoining of DNA double-strand breaks. In contrast, γH2AX foci produced by low doses (20-80 mGy) did not change after 60 min. The number of pATM foci between 60 and 240 min decreased down to control values in a dose-independent manner. Similar kinetics was observed for pATM foci co-localized with γH2AX foci. Collectively, our results suggest differential DNA double-strand break signaling and processing in response to low vs. intermediate doses of X-rays in human MSCs. Furthermore, mechanisms governing the prolonged persistence of γH2AX foci in these cells appear to be ATM-independent.

  6. Phosphorylation of histone H2AX as an indicator of received dose of gamma radiation after whole-body irradiation of rats

    Directory of Open Access Journals (Sweden)

    Radim Havelek

    2011-01-01

    Full Text Available The aim of our study was to determine whether phosphorylation of histone H2AX can be used as an indicator of received dose of gamma radiation after whole-body irradiation of rats. Wistar rats were irradiated by 1-10 Gy of gamma radiation by 60Co source. Value LD50/60 was 7.37 (4.68-8.05 Gy. Histone H2AX is phosphorylated by ATM kinase on serine 139 (γH2AX quickly after the irradiation. It forms microscopically visible foci in the site of double strand breaks of DNA. Flow-cytometric method was used for quantitative detection. This study is the first one that evaluated dose-dependency of H2AX phosphorylation in peripheral lymphocytes of rats irradiated by whole-body dose 1-10 Gy. Our data show a dose-dependent increase in γH2AX in rat peripheral blood lymphocytes 1 h after whole-body irradiation by the dose of 1-10 Gy. We proved that phosphorylation of histone H2AX is a prompt and reliable indicator of the received radiation dose suitable for rapid measurement before the number of lymphocytes in peripheral blood starts to decrease. It can be used already 1 h after the irradiation for an estimation of the received dose of radiation. Blood samples can be stored in 4 °C for 23 h without significantly affecting the result.

  7. Biochemical Kinetics Model of DSB Repair and GammaH2AX FOCI by Non-homologous End Joining

    Science.gov (United States)

    Cucinotta, Francis, A.; Pluth, Janice M.; Anderson, Jennifer A.; Harper, Jane V.; O'Neill, Peter

    2007-01-01

    We developed a biochemical kinetics approach to describe the repair of double strand breaks (DSB) produced by low LET radiation by modeling molecular events associated with the mechanisms of non-homologous end-joining (NHEJ). A system of coupled non-linear ordinary differential equations describes the induction of DSB and activation pathways for major NHEJ components including Ku(sub 70/80), DNA-PK(sub cs), and the Ligase IV-XRCC4 hetero-dimer. The autophosphorylation of DNA-PK(sub cs and subsequent induction of gamma-H2AX foci observed after ionizing radiation exposure were modeled. A two-step model of DNA-PK(sub cs) regulation of repair was developed with the initial step allowing access of other NHEJ components to breaks, and a second step limiting access to Ligase IV-XRCC4. Our model assumes that the transition from the first to second-step depends on DSB complexity, with a much slower-rate for complex DSB. The model faithfully reproduced several experimental data sets, including DSB rejoining as measured by pulsed-field electrophoresis (PFGE), quantification of the induction of gamma-H2AX foci, and live cell imaging of the induction of Ku(sub 70/80). Predictions are made for the behaviors of NHEJ components at low doses and dose-rates, where a steady-state is found at dose-rates of 0.1 Gy/hr or lower.

  8. Microscopic evaluation of nuclear foci (gamma H2AX) in cells irradiated with protons and lithium ions

    International Nuclear Information System (INIS)

    Bracalente, C.; Molinari, Beatriz L.; Duran, Hebe; Ibanez, I.; Palmieri, M.; Kreiner, Andres J.; Burlon, Alejandro; Valda, Alejandro; Davidson, J.; Davidson, M.; Vazquez, Monica; Ozafran, Mabel J.

    2007-01-01

    Full text: The special properties of both physical and biological radiation particles with high-LET (Linear Transfer of Energy) have led to its increased use in cancer therapy. In this work, the effect of high and low LET radiation on cell lines with different radiosensitivity (Irs-20 and CHO-10B2) quantifying the number and size of nuclear foci obtained from histone H2AXH2AX) phosphorylation which plays an important role in DNA damage reparation is compared. Foci detection was performed by immunocytochemical methods and fluorescence microscopy. The cells cultures were irradiated with plateau-phase protons (14 MeV, LET: 3 keV/μ), on Bragg peak (3 MeV. LET: 14 KeV/μ) and with Lithium ions (7 MeV, LET: 250 KeV//μ) on the Tandar accelerator. A clonogenic analysis of the two cell lines was made. Irradiation with protons (low LET) showed a significant difference (p [es

  9. Endogenous and radiation-induced expression of γH2AX in biopsies from patients treated for carcinoma of the uterine cervix

    International Nuclear Information System (INIS)

    Olive, Peggy L.; Banuelos, C. Adriana; Durand, Ralph E.; Kim, Joo-Young; Aquino-Parsons, Christina

    2010-01-01

    Background and purpose: The possibility of using γH2AX foci as a marker of DNA damage and as a potential predictor of tumour response to treatment was examined using biopsies from 3 sets of patients with advanced carcinoma of the cervix. The relation between endogenous γH2AX expression and hypoxia was also examined. Materials and methods: Set 1 consisted of 26 biopsies that included pre-treatment and 24 h post-radiation treatment samples. Pre-treatment biopsies from 12 patients in Set 2 were used to develop image analysis software while pre-treatment biopsies from 33 patients in Set 3 were examined for the relation between staining for the hypoxia marker pimonidazole and endogenous γH2AX expression. Formalin-fixed paraffin-embedded sections were analyzed after antigen retrieval and fluorescence antibody labeling for the hypoxia markers CAIX or pimonidazole in combination with γH2AX staining. Results: Before treatment, 24 ± 19% of cells contained γH2AX foci, with most positive cells containing fewer than 5 foci per nucleus. Twenty-four hours after exposure to the first fraction of 1.8-2.5 Gy, 38 ± 19% contained foci. CAIX positive cells were 1.4 times more likely to exhibit endogenous γH2AX foci, and pimonidazole-positive cells were 2.8 times more likely to contain γH2AX foci. For 18 patients for whom both pre-treatment and 24 h post-irradiation biopsies were available, local control was unrelated to the fraction of cells that retained γH2AX foci. However, 24 h after irradiation, tumours that had received 2.5 Gy showed a significantly higher fraction of cells with residual γH2AX foci than tumours given 1.8 Gy. Conclusions: Endogenous γH2AX foci are enriched in hypoxic tumour regions. Small differences in delivered dose can produce quantifiable differences in residual DNA damage that can overshadow inter-tumour differences in response.

  10. Dicentric chromosomes and γ-H2AX foci formation in lymphocytes of human blood samples exposed to a CT scanner: A direct comparison of dose response relationships

    International Nuclear Information System (INIS)

    Golfier, S.; Jost, G.; Pietsch, H.; Lengsfeld, P.; Eckardt-Schupp, F.; Schmid, E.; Voth, M.

    2009-01-01

    Experiments using the induction of dicentric chromosomes (dicentrics) as well as the γ-H2AX foci formation in lymphocytes of blood samples from a healthy donor were performed to directly evaluate the radiation sensitivity of both biological endpoints. For computed tomography scans at dose levels from 0.025 to 1 Gy, a linear-quadratic dose - response relationship for dicentrics and a linear dose - response relationship for γ-H2AX foci were obtained. The coefficients of the dose - response relationship for dicentrics are α = (3.76 ± 0.29) x 10 -2 Gy -1 and β = (5.54 ± 0.45) x 10 -2 Gy -2 , the linear coefficient for γ-H2AX foci is (7.38 ± 0.11) Gy -1 . The findings indicate that scoring of dicentrics as well as microscopic analysis of γ-H2AX foci are sensitive methods to quantify a radiation-induced biological damage at low doses. However, since γ-H2AX foci can be partially repaired within a few hours, biological damages present for days or even months, which constitute the clinically relevant endpoints, can only be quantified reliably by scoring of chromosome aberrations. Thus currently the quantification of dicentrics or reciprocal translocations remains the recommended method for estimating the effect of exposures to low dose levels of radiation ('biological dosimetry'). However, owing to the high radiation sensitivity of the γ-H2AX foci assay observed in the present study, further investigations on the effectiveness of low-linear energy transfer radiation qualities in producing γ-H2AX foci in lymphocytes from healthy donors should be performed. (authors)

  11. Requirement for the Phospho-H2AX Binding Module of Crb2 in Double-Strand Break Targeting and Checkpoint Activation▿

    Science.gov (United States)

    Sanders, Steven L.; Arida, Ahmad R.; Phan, Funita P.

    2010-01-01

    Activation of DNA damage checkpoints requires the rapid accumulation of numerous factors to sites of genomic lesions, and deciphering the mechanisms of this targeting is central to our understanding of DNA damage response. Histone modification has recently emerged as a critical element for the correct localization of damage response proteins, and one key player in this context is the fission yeast checkpoint mediator Crb2. Accumulation of Crb2 at ionizing irradiation-induced double-strand breaks (DSBs) requires two distinct histone marks, dimethylated H4 lysine 20 (H4K20me2) and phosphorylated H2AX (pH2AX). A tandem tudor motif in Crb2 directly binds H4K20me2, and this interaction is required for DSB targeting and checkpoint activation. Similarly, pH2AX is required for Crb2 localization to DSBs and checkpoint control. Crb2 can directly bind pH2AX through a pair of C-terminal BRCT repeats, but the functional significance of this binding has been unclear. Here we demonstrate that loss of its pH2AX-binding activity severely impairs the ability of Crb2 to accumulate at ionizing irradiation-induced DSBs, compromises checkpoint signaling, and disrupts checkpoint-mediated cell cycle arrest. These impairments are similar to that reported for abolition of pH2AX or mutation of the H4K20me2-binding tudor motif of Crb2. Intriguingly, a combined ablation of its two histone modification binding modules yields a strikingly additive reduction in Crb2 activity. These observations argue that binding of the Crb2 BRCT repeats to pH2AX is critical for checkpoint activity and provide new insight into the mechanisms of chromatin-mediated genome stability. PMID:20679488

  12. Requirement for the phospho-H2AX binding module of Crb2 in double-strand break targeting and checkpoint activation.

    Science.gov (United States)

    Sanders, Steven L; Arida, Ahmad R; Phan, Funita P

    2010-10-01

    Activation of DNA damage checkpoints requires the rapid accumulation of numerous factors to sites of genomic lesions, and deciphering the mechanisms of this targeting is central to our understanding of DNA damage response. Histone modification has recently emerged as a critical element for the correct localization of damage response proteins, and one key player in this context is the fission yeast checkpoint mediator Crb2. Accumulation of Crb2 at ionizing irradiation-induced double-strand breaks (DSBs) requires two distinct histone marks, dimethylated H4 lysine 20 (H4K20me2) and phosphorylated H2AX (pH2AX). A tandem tudor motif in Crb2 directly binds H4K20me2, and this interaction is required for DSB targeting and checkpoint activation. Similarly, pH2AX is required for Crb2 localization to DSBs and checkpoint control. Crb2 can directly bind pH2AX through a pair of C-terminal BRCT repeats, but the functional significance of this binding has been unclear. Here we demonstrate that loss of its pH2AX-binding activity severely impairs the ability of Crb2 to accumulate at ionizing irradiation-induced DSBs, compromises checkpoint signaling, and disrupts checkpoint-mediated cell cycle arrest. These impairments are similar to that reported for abolition of pH2AX or mutation of the H4K20me2-binding tudor motif of Crb2. Intriguingly, a combined ablation of its two histone modification binding modules yields a strikingly additive reduction in Crb2 activity. These observations argue that binding of the Crb2 BRCT repeats to pH2AX is critical for checkpoint activity and provide new insight into the mechanisms of chromatin-mediated genome stability.

  13. High levels of γ-H2AX foci and cell membrane oxidation in adolescents with type 1 diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Giovannini, Caterina [Unità di Genetica, Dipartimento di Biologia, Pisa University, Pisa (Italy); Piaggi, Simona [Sezione di Patologia Sperimentale, Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Pisa University, Pisa (Italy); Federico, Giovanni [Unità di Endocrinologia Pediatrica e Diabete, Dipartimento di Medicina Clinica e Sperimentale Pisa University, Pisa (Italy); Scarpato, Roberto, E-mail: roberto.scarpato@unipi.it [Unità di Genetica, Dipartimento di Biologia, Pisa University, Pisa (Italy)

    2014-12-15

    Highlights: • We aimed to detect signs of very early damage in peripheral cells of T1DM adolescents. • T1DM patients had high levels of oxidized cells and reduced expression of iNOS and NO. • Highly mutagenic lesions were markedly increased in the diabetic group, mainly in females. • The observed damage might increase the risk of cancer in the patients later in life. - Abstract: Oxidative stress caused by an excess of free radicals is implicated in the pathogenesis and development of type 1 diabetes mellitus (T1DM) and, in turn, it can lead to genome damage, especially in the form of DNA double-strand break (DSB). The DNA DSB is a potentially carcinogenic lesion for human cells. Thus, we aimed to evaluate whether the level of oxidative stress was increased in peripheral blood lymphocytes of a group of affected adolescents. In 35 T1DM adolescents and 19 healthy controls we assessed: (1) spontaneous and H{sub 2}O{sub 2}-induced oxidation of cell membrane using a fluorescence lipid probe; (2) spontaneous and LPS-induced expression of iNOS protein and indirect NO determination via cytofluorimetric analysis of O{sub 2}{sup −}; (3) immunofluorescent detection of the basal level of histone H2AX phosphorylation (γ-H2AX foci), a well-validated marker of DNA DSB. In T1DM, the frequencies of oxidized cells, both spontaneous and H{sub 2}O{sub 2}-induced (47.13 ± 0.02) were significantly higher than in controls (35.90 ± 0.03). Patients showed, in general, both a reduced iNOS expression and production of NO. Furthermore, the level of spontaneous nuclear damage, quantified as γ-H2AX foci, was markedly increased in T1DM adolescents (6.15 ± 1.08% of γ-H2AX{sup +} cells; 8.72 ± 2.14 γ-H2AXF/n; 9.26 ± 2.37 γ-H2AXF/np), especially in females. In the present study, we confirmed the role that oxidative stress plays in the disease damaging lipids of cell membrane and, most importantly, causing genomic damage in circulating white blood cells of affected adolescents

  14. Flow cytometry-assisted quantification of γH2AX expression has potential as a rapid high-throughput biodosimetry tool.

    Science.gov (United States)

    Achel, Daniel G; Serafin, Antonio M; Akudugu, John M

    2016-08-01

    Large-scale radiological events require immediate and accurate estimates of doses received by victims, and possibly the first responders, to assist in treatment decisions. Although there are numerous efforts worldwide to develop biodosimetric tools to adequately handle triage needs during radiological incidents, such endeavours do not seem to actively involve sub-Saharan Africa which currently has a significant level of nuclear-related activity. To initiate a similar interest in Africa, ex vivo radiation-induced γH2AX expression in peripheral blood lymphocytes from fourteen healthy donors was assessed using flow cytometry. While the technique shows potential for use as a rapid high-throughput biodosimetric tool for radiation absorbed doses up to 5 Gy, significant inter-individual differences in γH2AX expression emerged. Also, female donors exhibited higher levels of γH2AX expression than their male counterparts. To address these shortcomings, gender-based in-house dose-response curves for γH2AX induction in lymphocytes 2, 4, and 6 h after X-ray irradiation are proposed for the South African population. The obtained results show that γH2AX is a good candidate biomarker for biodosimetry, but might need some refinement and validation through further studies involving a larger cohort of donors.

  15. Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predicts Poor Survival of Breast Carcinoma Patients

    Directory of Open Access Journals (Sweden)

    See-Hyoung Park

    2015-08-01

    Full Text Available BACKGROUND: Poly(ADP-ribose polymerase 1 (PARP1, γH2AX, BRCA1, and BRCA2 are conventional molecular indicators of DNA damage in cells and are often overexpressed in various cancers. In this study, we aimed, using immunohistochemical detection, whether the co-expression of PARP1, γH2AX, BRCA1, and BRCA2 in breast carcinoma (BCA tissue can provide more reliable prediction of survival of BCA patients. MATERIALS AND METHODS: We investigated immunohistochemical expression and prognostic significance of the expression of PARP1, γH2AX, BRCA1, and BRCA2 in 192 cases of BCAs. RESULTS: The expression of these four molecules predicted earlier distant metastatic relapse, shorter overall survival (OS, and relapse-free survival (RFS by univariate analysis. Multivariate analysis revealed the expression of PARP1, γH2AX, and BRCA2 as independent poor prognostic indicators of OS and RFS. In addition, the combined expressional pattern of BRCA1, BRCA2, PARP1, and γH2AX (CSbbph was an additional independent prognostic predictor for OS (P < .001 and RFS (P < .001. The 10-year OS rate was 95% in the CSbbph-low (CSbbph scores 0 and 1 subgroup, but that was only 35% in the CSbbph-high (CSbbph score 4 subgroup. CONCLUSION: This study has demonstrated that the individual and combined expression patterns of PARP1, γH2AX, BRCA1, and BRCA2 could be helpful in determining an accurate prognosis for BCA patients and for the selection of BCA patients who could potentially benefit from anti-PARP1 therapy with a combination of genotoxic chemotherapeutic agents.

  16. Induction and Rejoining of DNA Double Strand Breaks Assessed by H2AX Phosphorylation in Melanoma Cells Irradiated with Proton and Lithium Beams

    International Nuclear Information System (INIS)

    Ibanez, Irene L.; Bracalente, Candelaria; Molinari, Beatriz L.; Palmieri, Monica A.; Policastro, Lucia; Kreiner, Andres J.; Burlon, Alejandro A.; Valda, Alejandro; Navalesi, Daniela; Davidson, Jorge; Davidson, Miguel; Vazquez, Monica; Ozafran, Mabel; Duran, Hebe

    2009-01-01

    Purpose: The aim of this study was to evaluate the induction and rejoining of DNA double strand breaks (DSBs) in melanoma cells exposed to low and high linear energy transfer (LET) radiation. Methods and Materials: DSBs and survival were determined as a function of dose in melanoma cells (B16-F0) irradiated with monoenergetic proton and lithium beams and with a gamma source. Survival curves were obtained by clonogenic assay and fitted to the linear-quadratic model. DSBs were evaluated by the detection of phosphorylated histone H2AXH2AX) foci at 30 min and 6 h post-irradiation. Results: Survival curves showed the increasing effectiveness of radiation as a function of LET. γH2AX labeling showed an increase in the number of foci vs. dose for all the radiations evaluated. A decrease in the number of foci was found at 6 h post-irradiation for low LET radiation, revealing the repair capacity of DSBs. An increase in the size of γH2AX foci in cells irradiated with lithium beams was found, as compared with gamma and proton irradiations, which could be attributed to the clusters of DSBs induced by high LET radiation. Foci size increased at 6 h post-irradiation for lithium and proton irradiations in relation with persistent DSBs, showing a correlation with surviving fraction. Conclusions: Our results showed the response of B16-F0 cells to charged particle beams evaluated by the detection of γH2AX foci. We conclude that γH2AX foci size is an accurate parameter to correlate the rejoining of DSBs induced by different LET radiations and radiosensitivity.

  17. γ-H2AX as a marker for dose deposition in the brain of wistar rats after synchrotron microbeam radiation.

    Directory of Open Access Journals (Sweden)

    Cristian Fernandez-Palomo

    Full Text Available Synchrotron radiation has shown high therapeutic potential in small animal models of malignant brain tumours. However, more studies are needed to understand the radiobiological effects caused by the delivery of high doses of spatially fractionated x-rays in tissue. The purpose of this study was to explore the use of the γ-H2AX antibody as a marker for dose deposition in the brain of rats after synchrotron microbeam radiation therapy (MRT.Normal and tumour-bearing Wistar rats were exposed to 35, 70 or 350 Gy of MRT to their right cerebral hemisphere. The brains were extracted either at 4 or 8 hours after irradiation and immediately placed in formalin. Sections of paraffin-embedded tissue were incubated with anti γ-H2AX primary antibody.While the presence of the C6 glioma does not seem to modulate the formation of γ-H2AX in normal tissue, the irradiation dose and the recovery versus time are the most important factors affecting the development of γ-H2AX foci. Our results also suggest that doses of 350 Gy can trigger the release of bystander signals that significantly amplify the DNA damage caused by radiation and that the γ-H2AX biomarker does not only represent DNA damage produced by radiation, but also damage caused by bystander effects.In conclusion, we suggest that the γ-H2AX foci should be used as biomarker for targeted and non-targeted DNA damage after synchrotron radiation rather than a tool to measure the actual physical doses.

  18. Influence of Different Antioxidants on X-Ray Induced DNA Double-Strand Breaks (DSBs Using γ-H2AX Immunofluorescence Microscopy in a Preliminary Study.

    Directory of Open Access Journals (Sweden)

    Michael Brand

    Full Text Available Radiation exposure occurs in X-ray guided interventional procedures or computed tomography (CT and γ-H2AX-foci are recognized to represent DNA double-strand breaks (DSBs as a biomarker for radiation induced damage. Antioxidants may reduce the induction of γ-H2AX-foci by binding free radicals. The aim of this study was to establish a dose-effect relationship and a time-effect relationship for the individual antioxidants on DSBs in human blood lymphocytes.Blood samples from volunteers were irradiated with 10 mGy before and after pre-incubation with different antioxidants (zinc, trolox, lipoic acid, ß-carotene, selenium, vitamin E, vitamin C, N-acetyl-L-cysteine (NAC and Q 10. Thereby, different pre-incubation times, concentrations and combinations of drugs were evaluated. For assessment of DSBs, lymphocytes were stained against the phosphorylated histone variant γ-H2AX.For zinc, trolox and lipoic acid regardless of concentration or pre-incubation time, no significant decrease of γ-H2AX-foci was found. However, ß-carotene (15%, selenium (14%, vitamin E (12%, vitamin C (25%, NAC (43% and Q 10 (18% led to a significant reduction of γ-H2AX-foci at a pre-incubation time of 1 hour. The combination of different antioxidants did not have an additive effect.Antioxidants administered prior to irradiation demonstrated the potential to reduce γ-H2AX-foci in blood lymphocytes.

  19. γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Halm, Brunhild M.; Franke, Adrian A.; Lai, Jennifer F. [University of Hawaii Cancer Center, Honolulu, HI (United States); Turner, Helen C.; Brenner, David J.; Zohrabian, Vatche M. [Columbia University Medical Center, Center for Radiological Research, New York, NY (United States); DiMauro, Robert [Kapi' olani Medical Center for Women and Children, Honolulu, HI (United States)

    2014-10-15

    Computed tomography (CT) is an imaging modality involving ionizing radiation. The presence of γ-H2AX foci after low to moderate ionizing radiation exposure has been demonstrated; however it is unknown whether very low ionizing radiation exposure doses from CT exams can induce γ-H2AX formation in vivo in young children. To test whether very low ionizing radiation doses from CT exams can induce lymphocytic γ-H2AX foci (phosphorylated histones used as a marker of DNA damage) formation in vivo in young children. Parents of participating children signed a consent form. Blood samples from three children (ages 3-21 months) undergoing CT exams involving very low blood ionizing radiation exposure doses (blood doses of 0.22-1.22 mGy) were collected immediately before and 1 h post CT exams. Isolated lymphocytes were quantified for γ-H2AX foci by a technician blinded to the radiation status and dose of the patients. Paired t-tests and regression analyses were performed with significance levels set at P < 0.05. We observed a dose-dependent increase in γ-H2AX foci post-CT exams (P = 0.046) among the three children. Ionizing radiation exposure doses led to a linear increase of foci per cell in post-CT samples (102% between lowest and highest dose). We found a significant induction of γ-H2AX foci in lymphocytes from post-CT samples of three very young children. When possible, CT exams should be limited or avoided by possibly applying non-ionizing radiation exposure techniques such as US or MRI. (orig.)

  20. γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study

    International Nuclear Information System (INIS)

    Halm, Brunhild M.; Franke, Adrian A.; Lai, Jennifer F.; Turner, Helen C.; Brenner, David J.; Zohrabian, Vatche M.; DiMauro, Robert

    2014-01-01

    Computed tomography (CT) is an imaging modality involving ionizing radiation. The presence of γ-H2AX foci after low to moderate ionizing radiation exposure has been demonstrated; however it is unknown whether very low ionizing radiation exposure doses from CT exams can induce γ-H2AX formation in vivo in young children. To test whether very low ionizing radiation doses from CT exams can induce lymphocytic γ-H2AX foci (phosphorylated histones used as a marker of DNA damage) formation in vivo in young children. Parents of participating children signed a consent form. Blood samples from three children (ages 3-21 months) undergoing CT exams involving very low blood ionizing radiation exposure doses (blood doses of 0.22-1.22 mGy) were collected immediately before and 1 h post CT exams. Isolated lymphocytes were quantified for γ-H2AX foci by a technician blinded to the radiation status and dose of the patients. Paired t-tests and regression analyses were performed with significance levels set at P < 0.05. We observed a dose-dependent increase in γ-H2AX foci post-CT exams (P = 0.046) among the three children. Ionizing radiation exposure doses led to a linear increase of foci per cell in post-CT samples (102% between lowest and highest dose). We found a significant induction of γ-H2AX foci in lymphocytes from post-CT samples of three very young children. When possible, CT exams should be limited or avoided by possibly applying non-ionizing radiation exposure techniques such as US or MRI. (orig.)

  1. Relationship between spontaneous γH2AX foci formation and progenitor functions in circulating hematopoietic stem and progenitor cells among atomic-bomb survivors.

    Science.gov (United States)

    Kajimura, Junko; Kyoizumi, Seishi; Kubo, Yoshiko; Misumi, Munechika; Yoshida, Kengo; Hayashi, Tomonori; Imai, Kazue; Ohishi, Waka; Nakachi, Kei; Weng, Nan-Ping; Young, Lauren F; Shieh, Jae-Hung; Moore, Malcolm A; van den Brink, Marcel R M; Kusunoki, Yoichiro

    2016-05-01

    Accumulated DNA damage in hematopoietic stem cells is a primary mechanism of aging-associated dysfunction in human hematopoiesis. About 70 years ago, atomic-bomb (A-bomb) radiation induced DNA damage and functional decreases in the hematopoietic system of A-bomb survivors in a radiation dose-dependent manner. The peripheral blood cell populations then recovered to a normal range, but accompanying cells derived from hematopoietic stem cells still remain that bear molecular changes possibly caused by past radiation exposure and aging. In the present study, we evaluated radiation-related changes in the frequency of phosphorylated (Ser-139) H2AXH2AX) foci formation in circulating CD34-positive/lineage marker-negative (CD34+Lin-) hematopoietic stem and progenitor cells (HSPCs) among 226Hiroshima A-bomb survivors. An association between the frequency of γH2AX foci formation in HSPCs and the radiation dose was observed, but the γH2AX foci frequency was not significantly elevated by past radiation. We found a negative correlation between the frequency of γH2AX foci formation and the length of granulocyte telomeres. A negative interaction effect between the radiation dose and the frequency of γH2AX foci was suggested in a proportion of a subset of HSPCs as assessed by the cobblestone area-forming cell assay (CAFC), indicating that the self-renewability of HSPCs may decrease in survivors who were exposed to a higher radiation dose and who had more DNA damage in their HSPCs. Thus, although many years after radiation exposure and with advancing age, the effect of DNA damage on the self-renewability of HSPCs may be modified by A-bomb radiation exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Gamma-H2AX foci in cells exposed to a mixed beam of X-rays and alpha particles

    Science.gov (United States)

    2012-01-01

    Background Little is known about the cellular effects of exposure to mixed beams of high and low linear energy transfer radiation. So far, the effects of combined exposures have mainly been assessed with clonogenic survival or cytogenetic methods, and the results are contradictory. The gamma-H2AX assay has up to now not been applied in this context, and it is a promising tool for investigating the early cellular response to mixed beam irradiation. Purpose To determine the dose response and repair kinetics of gamma-H2AX ionizing radiation-induced foci in VH10 human fibroblasts exposed to mixed beams of 241Am alpha particles and X-rays. Results VH10 human fibroblasts were irradiated with each radiation type individually or both in combination at 37°C. Foci were scored for repair kinetics 0.5, 1, 3 and 24 h after irradiation (one dose per irradiation type), and for dose response at the 1 h time point. The dose response effect of mixed beam was additive, and the relative biological effectiveness for alpha particles (as compared to X-rays) was of 0.76 ± 0.52 for the total number of foci, and 2.54 ± 1.11 for large foci. The repair kinetics for total number of foci in cells exposed to mixed beam irradiation was intermediate to that of cells exposed to alpha particles and X-rays. However, for mixed beam-irradiated cells the frequency and area of large foci were initially lower than predicted and increased during the first 3 hours of repair (while the predicted number and area did not). Conclusions The repair kinetics of large foci after mixed beam exposure was significantly different from predicted based on the effect of the single dose components. The formation of large foci was delayed and they did not reach their maximum area until 1 h after irradiation. We hypothesize that the presence of low X-ray-induced damage engages the DNA repair machinery leading to a delayed DNA damage response to the more complex DNA damage induced by alpha particles. PMID:23121736

  3. Ionizing radiation-induced DNA double-strand break and repair assessed by γ-H2AX foci analysis in neurons in mice

    International Nuclear Information System (INIS)

    Dong Xiaorong; Wu Gang; Ruebe Claudia; Ruebe Christian

    2009-01-01

    Objective: To investigate if the γ-H2AX foci is a precise index for the DSB formation and repair in mature neurons of brain in vivo after clinically relevant doses irradiation. Methods: For the DSB formation experiment, the mature neurons in the neocortex of brain tissue of C57BL/6 mice were analyzed at 10 rain after whole-body irradiation with 0.1, 0.5 and 1.0 Gy. For the DSB repair kinetics experiment, the mature neurons in the neocortex of brain tissue of repair-proficient (C57BL/6 mice) and repair-deficient mouse strains (BALB/c, A-T and SCID mice) were analyzed at 0.5, 2.5, 5, 24 and 48 h after whole-body irradiation with 2 Gy. The mature neurons in the neocortex of brain tissue of sham-irradiated mice of each strain served as controls. γ-H2AX immunohistochemistry and γ-H2AX and NeuN double immunofluorescence analysis was used to measure DSBs formation and repair in the mature neurons in the neocortex of brain tissue of the different mouse strains. Results: For the DSB formation experiment, γ-H2AX foci levels with a clear linear close correlation and very low backgrounds in the nuclei in the neocortex of brain tissue were observed. Scoring the loss of γ-H2AX foci allowed us to verify the different, genetically determined DSB repair deficiencies, including the minor impairment of BALB/c mice. Repair-proficient C57BL/6 mice exhibited the fastest decrease in foci number with time, and displayed low levels of residual damage at 24 h and 48 h post-irradiation. In contrast, SCID mice showed highly increased γ-H2AX foci levels at all repair times (0.5 h to 48 h) while A-T mice exhibited a lesser defect which was most significant at later repair times (≥ 5 h). Radiosensitive BALB/c mice exhibited slightly elevated foci numbers compared with C57BL/6 mice at 5 h and 24 h but not at 48 h post-irradiation. Conclusion: Quantifying the γ-H2AX foci in normal tissue represents a sensitivie tool for the detection of induction and repair of radiation-induced DSBs at

  4. Induction and Persistence of Large γH2AX Foci by High Linear Energy Transfer Radiation in DNA-Dependent protein kinase–Deficient Cells

    International Nuclear Information System (INIS)

    Bracalente, Candelaria; Ibañez, Irene L.; Molinari, Beatriz; Palmieri, Mónica; Kreiner, Andrés; Valda, Alejandro

    2013-01-01

    Purpose: To evaluate the cell response to DNA double-strand breaks induced by low and high linear energy transfer (LET) radiations when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of the nonhomologous end-joining repair pathway, lacks kinase activity. Methods and Materials: CHO10B2, a Chinese hamster ovary cell line, and its derived radiosensitive mutant cell line, irs-20, lacking DNA-PKcs activity, were evaluated after 0 to 3 Gy of γ-rays, plateau and Bragg peak protons, and lithium beams by clonogenic assay, and as a measurement of double-strand breaks, phosphorylated H2AXH2AX) foci number and size were quantified by immunocytofluorescence. Results: Irs-20 exhibited greater radiosensitivity and a higher amount of γH2AX foci than CHO10B2 at 6 hours after irradiation for all types of radiations. Remarkably, CHO10B2 and irs-20 maintained their difference in radiosensitivity after high-LET radiation. Six hours after low-LET radiations, irs-20 did not reach basal levels of γH2AX at high doses, whereas CHO10B2 recovered basal levels for all doses. After high-LET radiation, only CHO10B2 exhibited a reduction in γH2AX foci, but it never reached basal levels. Persistent foci in irs-20 confirmed a repair deficiency. Interestingly, after 30 minutes of high-LET radiation both cell lines exhibited large foci (size >0.9 μm 2 ) related to the damage nature, whereas at 6 hours irs-20 showed a higher amount of large foci than CHO10B2, with a 7-fold increase at 3 Gy, that could also be associated to radiosensitivity. Conclusions: We demonstrated, for the first time, an association between deficient DNA-PKcs activity and not only high levels of H2AX phosphorylation but also persistence and size increase of γH2AX foci after high-LET irradiation

  5. Induction and Persistence of Large γH2AX Foci by High Linear Energy Transfer Radiation in DNA-Dependent protein kinase–Deficient Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bracalente, Candelaria; Ibañez, Irene L. [Departamento de Micro y Nanotecnología, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Molinari, Beatriz [Departamento de Radiobiología, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Palmieri, Mónica [Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Kreiner, Andrés [Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires (Argentina); Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Buenos Aires (Argentina); Valda, Alejandro [Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Buenos Aires (Argentina); and others

    2013-11-15

    Purpose: To evaluate the cell response to DNA double-strand breaks induced by low and high linear energy transfer (LET) radiations when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an essential protein of the nonhomologous end-joining repair pathway, lacks kinase activity. Methods and Materials: CHO10B2, a Chinese hamster ovary cell line, and its derived radiosensitive mutant cell line, irs-20, lacking DNA-PKcs activity, were evaluated after 0 to 3 Gy of γ-rays, plateau and Bragg peak protons, and lithium beams by clonogenic assay, and as a measurement of double-strand breaks, phosphorylated H2AXH2AX) foci number and size were quantified by immunocytofluorescence. Results: Irs-20 exhibited greater radiosensitivity and a higher amount of γH2AX foci than CHO10B2 at 6 hours after irradiation for all types of radiations. Remarkably, CHO10B2 and irs-20 maintained their difference in radiosensitivity after high-LET radiation. Six hours after low-LET radiations, irs-20 did not reach basal levels of γH2AX at high doses, whereas CHO10B2 recovered basal levels for all doses. After high-LET radiation, only CHO10B2 exhibited a reduction in γH2AX foci, but it never reached basal levels. Persistent foci in irs-20 confirmed a repair deficiency. Interestingly, after 30 minutes of high-LET radiation both cell lines exhibited large foci (size >0.9 μm{sup 2}) related to the damage nature, whereas at 6 hours irs-20 showed a higher amount of large foci than CHO10B2, with a 7-fold increase at 3 Gy, that could also be associated to radiosensitivity. Conclusions: We demonstrated, for the first time, an association between deficient DNA-PKcs activity and not only high levels of H2AX phosphorylation but also persistence and size increase of γH2AX foci after high-LET irradiation.

  6. Visualisation of γH2AX Foci Caused by Heavy Ion Particle Traversal; Distinction between Core Track versus Non-Track Damage

    Science.gov (United States)

    Nakajima, Nakako Izumi; Brunton, Holly; Watanabe, Ritsuko; Shrikhande, Amruta; Hirayama, Ryoichi; Matsufuji, Naruhiro; Fujimori, Akira; Murakami, Takeshi; Okayasu, Ryuichi; Jeggo, Penny; Shibata, Atsushi

    2013-01-01

    Heavy particle irradiation produces complex DNA double strand breaks (DSBs) which can arise from primary ionisation events within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, which have a range of distributions can create low linear energy transfer (LET) damage within but also distant from the track. DNA damage by delta-electrons distant from the track has not previously been carefully characterised. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe (∼200 keV/µm) ions, γH2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered γH2AX foci. These foci are repaired with slow kinetics by DNA non-homologous end-joining (NHEJ) in G1 phase with the magnitude of complexity diminishing with time. These clustered foci (containing 10 or more individual foci) represent a signature of DSBs caused by high LET heavy particle radiation. We also identified simple γH2AX foci distant from the track, which resemble those arising after X-ray exposure, which we attribute to low LET delta-electron induced DSBs. They are rapidly repaired by NHEJ. Clustered γH2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple γH2AX foci following X-irradiation. However, mitotic entry was observed when ∼10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle. PMID:23967070

  7. Comparative potency approach based on H2AX assay for estimating the genotoxicity of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Audebert, M; Zeman, F; Beaudoin, R; Péry, A; Cravedi, J-P

    2012-04-01

    Polycyclic Aromatic Hydrocarbons (PAHs) constitute a family of over one hundred compounds and can generally be found in complex mixtures. PAHs metabolites cause DNA damage which can lead to the development of carcinogenesis. Toxicity assessment of PAH complex mixtures is currently expressed in terms of toxic equivalents, based on Toxicity Equivalent Factors (TEFs). However, the definition of new TEFs for a large number of PAH could overcome some limitations of the current method and improve cancer risk assessment. The current investigation aimed at deriving the relative potency factors of PAHs, based on their genotoxic effect measured in vitro and analyzed with mathematical models. For this purpose, we used a new genotoxic assay (γH2AX) with two human cell lines (HepG2 and LS-174T) to analyze the genotoxic properties of 13 selected PAHs at low doses after 24h treatment. The dose-response for genotoxic effects was modeled with a Hill model; equivalency between PAHs at low dose was assessed by applying constraints to the model parameters. In the two cell lines tested, we observed a clear dose-response for genotoxic effects for 11 tested compounds. LS-174T was on average ten times more sensitive than HepG2 towards PAHs regarding genotoxicity. We developed new TEFs, which we named Genotoxic Equivalent Factor (GEF). Calculated GEF for the tested PAHs were generally higher than the TEF usually used. Our study proposed a new in vitro based method for the establishment of relevant TEFs for PAHs to improve cancer risk assessment. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Gamma-H2AX as a biomarker of DNA damage induced by ionizing radiation in targeted and bystander human artificial skin models and peripheral blood lymphocytes

    Science.gov (United States)

    Redon, Christophe; Dickey, Jennifer; Bonner, William; Sedelnikova, Olga

    Ionizing radiation (IR) exposure is inevitable. In addition to exposure from cosmic rays, the sun and radioactive substances, modern society has created new sources of radiation exposure such as space and high altitude journeys, X-ray diagnostics, radiological treatments and the increasing threat of radiobiological terrorism. For these reasons, a reliable, reproducible and sensitive assessment of dose and time exposure to IR is essential. We developed a minimally invasive diagnostic test for IR exposure based on detection of a phosphorylated variant of histone H2AX (gamma-H2AX), which occurs specifically at sites of DNA double-strand breaks (DSBs). The phosphorylation of thousands of H2AX molecules forms a gamma-H2AX focus in the chromatin flanking the DSB site that can be detected in situ. We analyzed gamma- H2AX focus formation in both directly irradiated cells as well as in un-irradiated "bystanders" in close contact with irradiated cells. In order to insure minimal invasiveness, we examined commercially available artificial skin models as a surrogate for human skin biopsies as well as peripheral blood lymphocytes. In human skin models, cells in a thin plane were microbeamirradiated and gamma-H2AX formation was measured both in irradiated and in distal bystander cells over time. In irradiated cells DSB formation reached a maximum at 15-30 minutes post- IR and then declined within several hours; all cells were affected. In marked contrast, the incidence of DSBs in bystander cells reached a maximum by 12-48 hours post-irradiation, gradually decreasing over the 7 day time course. At the maxima, 40-60% of bystander cells were affected. Similarly, we analyzed blood samples exposed to IR ex vivo at doses ranging from 0.02 to 3 Gy. The amount of DNA damage was linear in respect to radiation dose and independent of the age or sex of the blood donor. The method is highly reproducible and highly sensitive. In directly irradiated cells, the number of gamma-H2AX foci peaked

  9. Comparison of the induction and disappearance of DNA double strand breaks and gamma-H2AX foci after irradiation of chromosomes in G1-phase or in condensed metaphase cells.

    Science.gov (United States)

    Kato, Takamitsu A; Okayasu, Ryuichi; Bedford, Joel S

    2008-03-01

    The induction and disappearance of DNA double strand breaks (DSBs) after irradiation of G1 and mitotic cells were compared with the gamma-H2AX foci assay and a gel electrophoresis assay. This is to determine whether cell cycle related changes in chromatin structure might influence the gamma-H2AX assay which depends on extensive phosphorylation and dephosphorylation of the H2AX histone variant surrounding DSBs. The disappearance of gamma-H2AX foci after irradiation was much slower for mitotic than for G1 cells. On the other hand, no difference was seen for the gel electrophoresis assay. Our data may suggest the limited accessibility of dephosphorylation enzyme in irradiated metaphase cells or trapped gamma-H2AX in condensed chromatin.

  10. Comparison of the induction and disappearance of DNA double strand breaks and γ-H2AX foci after irradiation of chromosomes in G1-phase or in condensed metaphase cells

    International Nuclear Information System (INIS)

    Kato, Takamitsu A.; Okayasu, Ryuichi; Bedford, Joel S.

    2008-01-01

    The induction and disappearance of DNA double strand breaks (DSBs) after irradiation of G1 and mitotic cells were compared with the γ-H2AX foci assay and a gel electrophoresis assay. This is to determine whether cell cycle related changes in chromatin structure might influence the γ-H2AX assay which depends on extensive phosphorylation and dephosphorylation of the H2AX histone variant surrounding DSBs. The disappearance of γ-H2AX foci after irradiation was much slower for mitotic than for G1 cells. On the other hand, no difference was seen for the gel electrophoresis assay. Our data may suggest the limited accessibility of dephosphorylation enzyme in irradiated metaphase cells or trapped γ-H2AX in condensed chromatin

  11. Suberoylanilide hydroxamic acid affects γH2AX expression in osteosarcoma, atypical teratoid rhabdoid tumor and normal tissue cell lines after irradiation

    International Nuclear Information System (INIS)

    Blattmann, C.; Oertel, S.; Thiemann, M.; Weber, K.J.; Schmezer, P.; Zelezny, O.; Lopez Perez, R.; Kulozik, A.E.; Debus, J.; Ehemann, V.

    2012-01-01

    Osteosarcoma and atypical teratoid rhabdoid tumors are tumor entities with varying response to common standard therapy protocols. Histone acetylation affects chromatin structure and gene expression which are considered to influence radiation sensitivity. The aim of this study was to investigate the effect of the combination therapy with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) and irradiation on atypical teratoid rhabdoid tumors and osteosarcoma compared to normal tissue cell lines. Clonogenic assay was used to determine cell survival. DNA double-strand breaks (DSB) were examined by pulsed-field electrophoresis (PFGE) as well as by γH2AX immunostaining involving flow cytometry, fluorescence microscopy, and immunoblot analysis. SAHA lead to an increased radiosensitivity in tumor but not in normal tissue cell lines. γH2AX expression as an indicator for DSB was significantly increased when SAHA was applied 24 h before irradiation to the sarcoma cell cultures. In contrast, γH2AX expression in the normal tissue cell lines was significantly reduced when irradiation was combined with SAHA. Analysis of initial DNA fragmentation and fragment rejoining by PFGE, however, did not reveal differences in response to the SAHA pretreatment for either cell type. SAHA increases radiosensitivity in tumor but not normal tissue cell lines. The increased H2AX phosphorylation status of the SAHA-treated tumor cells post irradiation likely reflects its delayed dephosphorylation within the DNA damage signal decay rather than chromatin acetylation-dependent differences in the overall efficacy of DSB induction and rejoining. The results support the hypothesis that combining SAHA with irradiation may provide a promising strategy in the treatment of solid tumors. (orig.)

  12. Effect of dose rate on residual γ-H2AX levels and frequency of micronuclei in X-irradiated mouse lymphocytes.

    Science.gov (United States)

    Turner, H C; Shuryak, I; Taveras, M; Bertucci, A; Perrier, J R; Chen, C; Elliston, C D; Johnson, G W; Smilenov, L B; Amundson, S A; Brenner, D J

    2015-03-01

    The biological risks associated with low-dose-rate (LDR) radiation exposures are not yet well defined. To assess the risk related to DNA damage, we compared the yields of two established biodosimetry end points, γ-H2AX and micronuclei (MNi), in peripheral mouse blood lymphocytes after prolonged in vivo exposure to LDR X rays (0.31 cGy/min) vs. acute high-dose-rate (HDR) exposure (1.03 Gy/min). C57BL/6 mice were total-body irradiated with 320 kVP X rays with doses of 0, 1.1, 2.2 and 4.45 Gy. Residual levels of total γ-H2AX fluorescence in lymphocytes isolated 24 h after the start of irradiation were assessed using indirect immunofluorescence methods. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to determine apoptotic cell frequency in lymphocytes sampled at 24 h. Curve fitting analysis suggested that the dose response for γ-H2AX yields after acute exposures could be described by a linear dependence. In contrast, a linear-quadratic dose-response shape was more appropriate for LDR exposure (perhaps reflecting differences in repair time after different LDR doses). Dose-rate sparing effects (P effect across the dose range 24 h or 7 days post exposure. In conclusion, the γ-H2AX biomarker showed higher sensitivity to measure dose-rate effects after low-dose LDR X rays compared to MNi formation; however, confounding factors such as variable repair times post exposure, increased cell killing and cell cycle block likely contributed to the yields of MNi with accumulating doses of ionizing radiation.

  13. The use of gamma-H2AX as a biodosimeter for total-body radiation exposure in non-human primates.

    Directory of Open Access Journals (Sweden)

    Christophe E Redon

    2010-11-01

    Full Text Available There is a crucial shortage of methods capable of determining the extent of accidental exposures of human beings to ionizing radiation. However, knowledge of individual exposures is essential for early triage during radiological incidents to provide optimum possible life-sparing medical procedures to each person.We evaluated immunocytofluorescence-based quantitation of γ-H2AX foci as a biodosimeter of total-body radiation exposure ((60Co γ-rays in a rhesus macaque (Macaca mulatta model. Peripheral blood lymphocytes and plucked hairs were collected from 4 cohorts of macaques receiving total body irradiation doses ranging from 1 Gy to 8.5 Gy. Each cohort consisted of 6 experimental and 2 control animals. Numbers of residual γ-H2AX foci were proportional to initial irradiation doses and statistically significant responses were obtained until 1 day after 1 Gy, 4 days after 3.5 and 6.5 Gy, and 14 days after 8.5 Gy in lymphocytes and until 1 day after 1 Gy, at least 2 days after 3.5 and 6.5 Gy, and 9 days after 8.5 Gy in plucked hairs.These findings indicate that quantitation of γ-H2AX foci may make a robust biodosimeter for analyzing total-body exposure to ionizing radiation in humans. This tool would help clinicians prescribe appropriate types of medical intervention for optimal individual outcome. These results also demonstrate that the use of a high throughput γ-H2AX biodosimeter would be useful for days post-exposure in applications like large-scale radiological events or radiation therapy. In addition, this study validates a possibility to use plucked hair in future clinical trials investigating genotoxic effects of drugs and radiation treatments.

  14. Detection of DNA Double Strand Breaks by γH2AX Does Not Result in 53bp1 Recruitment in Mouse Retinal Tissues

    Directory of Open Access Journals (Sweden)

    Brigitte Müller

    2018-05-01

    Full Text Available Gene editing is an attractive potential treatment of inherited retinopathies. However, it often relies on endogenous DNA repair. Retinal DNA repair is incompletely characterized in humans and animal models. We investigated recruitment of the double stranded break (DSB repair complex of γH2AX and 53bp1 in both developing and mature mouse neuroretinas. We evaluated the immunofluorescent retinal expression of these proteins during development (P07-P30 in normal and retinal degeneration models, as well as in potassium bromate induced DSB repair in normal adult (3 months retinal explants. The two murine retinopathy models used had different mutations in Pde6b: the severe rd1 and the milder rd10 models. Compared to normal adult retina, we found increased numbers of γH2AX positive foci in all retinal neurons of the developing retina in both model and control retinas, as well as in wild type untreated retinal explant cultures. In contrast, the 53bp1 staining of the retina differed both in amount and character between cell types at all ages and in all model systems. There was strong pan nuclear staining in ganglion, amacrine, and horizontal cells, and cone photoreceptors, which was attenuated. Rod photoreceptors did not stain unequivocally. In all samples, 53bp1 stained foci only rarely occurred. Co-localization of 53bp1 and γH2AX staining was a very rare event (< 1% of γH2AX foci in the ONL and < 3% in the INL, suggesting the potential for alternate DSB sensing and repair proteins in the murine retina. At a minimum, murine retinal DSB repair does not appear to follow canonical pathways, and our findings suggests further investigation is warranted.

  15. Absence of DNA double-strand breaks in human peripheral blood mononuclear cells after 3 Tesla magnetic resonance imaging assessed by γH2AX flow cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Fasshauer, Martin; Staab, Wieland; Sohns, Jan M.; Ritter, Christian; Lotz, Joachim [Goettingen Heart Center, Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen (Germany); German Centre for Cardiovascular Research (DZHK), Goettingen (Germany); Kruewel, Thomas; Stahnke, Vera C. [Goettingen Heart Center, Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen (Germany); Zapf, Antonia [University Medical Center Goettingen, Department of Medical Statistics, Goettingen (Germany); Rave-Fraenk, Margret [University Medical Center Goettingen, Department of Radiotherapy and Radiooncology, Goettingen (Germany); Steinmetz, Michael [German Centre for Cardiovascular Research (DZHK), Goettingen (Germany); Goettingen Heart Center, Department of Pediatric Cardiology and Intensive Care Medicine, University Medical Center Goettingen (Germany); Unterberg-Buchwald, Christina [Goettingen Heart Center, Department of Diagnostic and Interventional Radiology, University Medical Center Goettingen (Germany); German Centre for Cardiovascular Research (DZHK), Goettingen (Germany); Goettingen Heart Center, Department of Cardiology and Pneumology, University Medical Center Goettingen (Germany); Schuster, Andreas [German Centre for Cardiovascular Research (DZHK), Goettingen (Germany); Goettingen Heart Center, Department of Cardiology and Pneumology, University Medical Center Goettingen (Germany)

    2018-03-15

    Magnetic resonance imaging (MRI) is regarded as a non-harming and non-invasive imaging modality with high tissue contrast and almost no side effects. Compared to other cross-sectional imaging modalities, MRI does not use ionising radiation. Recently, however, strong magnetic fields as applied in clinical MRI scanners have been suspected to induce DNA double-strand breaks in human lymphocytes. In this study we investigated the impact of 3-T cardiac MRI examinations on the induction of DNA double-strand breaks in peripheral mononuclear cells by γH2AX staining and flow cytometry analysis. The study cohort consisted of 73 healthy non-smoking volunteers with 36 volunteers undergoing CMRI and 37 controls without intervention. Differences between the two cohorts were analysed by a mixed linear model with repeated measures. Both cohorts showed a significant increase in the γH2AX signal from baseline to post-procedure of 6.7 % (SD 7.18 %) and 7.8 % (SD 6.61 %), respectively. However, the difference between the two groups was not significant. Based on our study, γH2AX flow cytometry shows no evidence that 3-T MRI examinations as used in cardiac scans impair DNA integrity in peripheral mononuclear cells. (orig.)

  16. USP22 Induces Cisplatin Resistance in Lung Adenocarcinoma by Regulating γH2AX-Mediated DNA Damage Repair and Ku70/Bax-Mediated Apoptosis

    Directory of Open Access Journals (Sweden)

    Aman Wang

    2017-05-01

    Full Text Available Resistance to platinum-based chemotherapy is one of the most important reasons for treatment failure in advanced non-small cell lung cancer, but the underlying mechanism is extremely complex and unclear. The present study aimed to investigate the correlation of ubiquitin-specific peptidase 22 (USP22 with acquired resistance to cisplatin in lung adenocarcinoma. In this study, we found that overexpression of USP22 could lead to cisplatin resistance in A549 cells. USP22 and its downstream proteins γH2AX and Sirt1 levels are upregulated in the cisplatin- resistant A549/CDDP cell line. USP22 enhances DNA damage repair and induce cisplatin resistance by promoting the phosphorylation of histone H2AX via deubiquitinating histone H2A. In addition, USP22 decreases the acetylation of Ku70 by stabilizing Sirt1, thus inhibiting Bax-mediated apoptosis and inducing cisplatin resistance. The cisplatin sensitivity in cisplatin-resistant A549/CDDP cells was restored by USP22 inhibition in vivo and vitro. In summary, our findings reveal the dual mechanism of USP22 involvement in cisplatin resistance that USP22 can regulate γH2AX-mediated DNA damage repair and Ku70/Bax-mediated apoptosis. USP22 is a potential target in cisplatin-resistant lung adenocarcinoma and should be considered in future therapeutic practice.

  17. Microwaves from GSM mobile telephones affect 53BP1 and gamma-H2AX foci in human lymphocytes from hypersensitive and healthy persons.

    Science.gov (United States)

    Markovà, Eva; Hillert, Lena; Malmgren, Lars; Persson, Bertil R R; Belyaev, Igor Y

    2005-09-01

    The data on biologic effects of nonthermal microwaves (MWs) from mobile telephones are diverse, and these effects are presently ignored by safety standards of the International Commission for Non-Ionizing Radiation Protection (ICNIRP). In the present study, we investigated effects of MWs of Global System for Mobile Communication (GSM) at different carrier frequencies on human lymphocytes from healthy persons and from persons reporting hypersensitivity to electromagnetic fields (EMFs). We measured the changes in chromatin conformation, which are indicative of stress response and genotoxic effects, by the method of anomalous viscosity time dependence, and we analyzed tumor suppressor p53-binding protein 1 (53BP1) and phosphorylated histone H2AX (gamma-H2AX), which have been shown to colocalize in distinct foci with DNA double-strand breaks (DSBs), using immunofluorescence confocal laser microscopy. We found that MWs from GSM mobile telephones affect chromatin conformation and 53BP1/gamma-H2AX foci similar to heat shock. For the first time, we report here that effects of MWs from mobile telephones on human lymphocytes are dependent on carrier frequency. On average, the same response was observed in lymphocytes from hypersensitive and healthy subjects.

  18. Reliability of a Fully Automated Interpretation of γ-H2AX Foci in Lymphocytes of Moderately Trained Subjects under Resting Conditions

    Directory of Open Access Journals (Sweden)

    Juliane Heydenreich

    2014-01-01

    Full Text Available Background. Analysis of γ-H2AX foci is a promising approach to evaluate exercise-induced DNA damage. However, baseline levels and day-to-day variability of γ-H2AX foci have not been investigated in healthy subjects at rest. Methods. Blood was taken from eight moderately trained healthy males (29 ± 3 yrs, 1.84 ± 0.03 m, and 85 ± 6 kg at two separate days (M1/M2 after 24-hour exercise cessation. Number of γ-H2AX foci per 100 lymphocytes (N, number of foci per affected lymphocyte (NAL, percentage of affected lymphocytes (PAL, and diameter (D of γ-H2AX foci were analyzed (mean ± SD. Differences between M1 and M2 were analyzed using paired t-tests (α = 0.05. Day-to-day variability was evaluated by calculating the coefficients of variation (CV%, bias, and limits of agreement (LoA. Results. There were no statistically significant differences between M1 (N: 7.6 ± 4.4, NAL: 1.2 ± 0.2, PAL: 5.9 ± 2.6%, and D: 0.63 ± 0.07 and M2 (N: 8.4 ± 4.6, NAL: 1.3 ± 0.1, PAL: 6.9 ± 4.2%, and D: 0.66 ± 0.06. CV was calculated to be 98.5% (N, 88.9% (PAL, 11.3% (NAL, and 8.0% (D. Bias (LoA was 0.75 (−15.2/13.7, −0.02 (−0.36/0.33, −1.0 (−11.9/9.9, and −0.04 (−0.16/0.09, respectively. Conclusions. Background level in healthy subjects is approximately 0.07 to 0.09 γ-H2AX foci/cell. NAL and D are reliable measures.

  19. Nucleosome acidic patch promotes RNF168- and RING1B/BMI1-dependent H2AX and H2A ubiquitination and DNA damage signaling.

    Directory of Open Access Journals (Sweden)

    Justin W Leung

    2014-03-01

    Full Text Available Histone ubiquitinations are critical for the activation of the DNA damage response (DDR. In particular, RNF168 and RING1B/BMI1 function in the DDR by ubiquitinating H2A/H2AX on Lys-13/15 and Lys-118/119, respectively. However, it remains to be defined how the ubiquitin pathway engages chromatin to provide regulation of ubiquitin targeting of specific histone residues. Here we identify the nucleosome acid patch as a critical chromatin mediator of H2A/H2AX ubiquitination (ub. The acidic patch is required for RNF168- and RING1B/BMI1-dependent H2A/H2AXub in vivo. The acidic patch functions within the nucleosome as nucleosomes containing a mutated acidic patch exhibit defective H2A/H2AXub by RNF168 and RING1B/BMI1 in vitro. Furthermore, direct perturbation of the nucleosome acidic patch in vivo by the expression of an engineered acidic patch interacting viral peptide, LANA, results in defective H2AXub and RNF168-dependent DNA damage responses including 53BP1 and BRCA1 recruitment to DNA damage. The acidic patch therefore is a critical nucleosome feature that may serve as a scaffold to integrate multiple ubiquitin signals on chromatin to compose selective ubiquitinations on histones for DNA damage signaling.

  20. The profiles of gamma-H2AX along with ATM/DNA-PKcs activation in the lymphocytes and granulocytes of rat and human blood exposed to gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Yin, Lina; Zhang, Junxiang; Zhang, Yaping; Zhang, Xuxia; Ding, Defang; Gao, Yun; Li, Qiang; Chen, Honghong [Fudan University, Department of Radiation Biology, Institute of Radiation Medicine, Shanghai (China)

    2016-08-15

    Establishing a rat model suitable for γ-H2AX biodosimeter studies has important implications for dose assessment of internal radionuclide contamination in humans. In this study, γ-H2AX, p-ATM and p-DNA-PKcs foci were enumerated using immunocytofluorescence method, and their protein levels were measured by Western blot in rat blood lymphocytes and granulocytes exposed to γ-rays compared with human blood lymphocytes and granulocytes. It was found that DNA double-strand break repair kinetics and linear dose responses in rat lymphocytes were similar to those observed in the human counterparts. Moreover, radiation induced clear p-ATM and p-DNA-PKcs foci formation and an increase in ratio of co-localization of p-ATM or p-DNA-PKcs with γ-H2AX foci in rat lymphocytes similar to those of human lymphocytes. The level of γ-H2AX protein in irradiated rat and human lymphocytes was significantly reduced by inhibitors of ATM and DNA-PKcs. Surprisingly, unlike human granulocytes, rat granulocytes with DNA-PKcs deficiency displayed a rapid accumulation, but delayed disappearance of γ-H2AX foci with essentially no change from 10 h to 48 h post-irradiation. Furthermore, inhibition of ATM activity in rat granulocytes also decreased radiation-induced γ-H2AX foci formation. In comparison, human granulocytes showed no response to irradiation regarding γ-H2AX, p-ATM or p-DNA-PKcs foci. Importantly, incidence of γ-H2AX foci in lymphocytes after total-body radiation of rats was consistent with that of in vitro irradiation of rat lymphocytes. These findings show that rats are a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans. ATM and DNA-PKcs participate together in DSB repair in rat lymphocytes similar to that of human lymphocytes. Further, rat granulocytes, which have the characteristic of delayed disappearance of γ-H2AX foci in response to radiation, may be a useful experimental system for biodosimetry studies. (orig.)

  1. The profiles of gamma-H2AX along with ATM/DNA-PKcs activation in the lymphocytes and granulocytes of rat and human blood exposed to gamma rays

    International Nuclear Information System (INIS)

    Wang, Jing; Yin, Lina; Zhang, Junxiang; Zhang, Yaping; Zhang, Xuxia; Ding, Defang; Gao, Yun; Li, Qiang; Chen, Honghong

    2016-01-01

    Establishing a rat model suitable for γ-H2AX biodosimeter studies has important implications for dose assessment of internal radionuclide contamination in humans. In this study, γ-H2AX, p-ATM and p-DNA-PKcs foci were enumerated using immunocytofluorescence method, and their protein levels were measured by Western blot in rat blood lymphocytes and granulocytes exposed to γ-rays compared with human blood lymphocytes and granulocytes. It was found that DNA double-strand break repair kinetics and linear dose responses in rat lymphocytes were similar to those observed in the human counterparts. Moreover, radiation induced clear p-ATM and p-DNA-PKcs foci formation and an increase in ratio of co-localization of p-ATM or p-DNA-PKcs with γ-H2AX foci in rat lymphocytes similar to those of human lymphocytes. The level of γ-H2AX protein in irradiated rat and human lymphocytes was significantly reduced by inhibitors of ATM and DNA-PKcs. Surprisingly, unlike human granulocytes, rat granulocytes with DNA-PKcs deficiency displayed a rapid accumulation, but delayed disappearance of γ-H2AX foci with essentially no change from 10 h to 48 h post-irradiation. Furthermore, inhibition of ATM activity in rat granulocytes also decreased radiation-induced γ-H2AX foci formation. In comparison, human granulocytes showed no response to irradiation regarding γ-H2AX, p-ATM or p-DNA-PKcs foci. Importantly, incidence of γ-H2AX foci in lymphocytes after total-body radiation of rats was consistent with that of in vitro irradiation of rat lymphocytes. These findings show that rats are a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans. ATM and DNA-PKcs participate together in DSB repair in rat lymphocytes similar to that of human lymphocytes. Further, rat granulocytes, which have the characteristic of delayed disappearance of γ-H2AX foci in response to radiation, may be a useful experimental system for biodosimetry studies. (orig.)

  2. The profiles of gamma-H2AX along with ATM/DNA-PKcs activation in the lymphocytes and granulocytes of rat and human blood exposed to gamma rays.

    Science.gov (United States)

    Wang, Jing; Yin, Lina; Zhang, Junxiang; Zhang, Yaping; Zhang, Xuxia; Ding, Defang; Gao, Yun; Li, Qiang; Chen, Honghong

    2016-08-01

    Establishing a rat model suitable for γ-H2AX biodosimeter studies has important implications for dose assessment of internal radionuclide contamination in humans. In this study, γ-H2AX, p-ATM and p-DNA-PKcs foci were enumerated using immunocytofluorescence method, and their protein levels were measured by Western blot in rat blood lymphocytes and granulocytes exposed to γ-rays compared with human blood lymphocytes and granulocytes. It was found that DNA double-strand break repair kinetics and linear dose responses in rat lymphocytes were similar to those observed in the human counterparts. Moreover, radiation induced clear p-ATM and p-DNA-PKcs foci formation and an increase in ratio of co-localization of p-ATM or p-DNA-PKcs with γ-H2AX foci in rat lymphocytes similar to those of human lymphocytes. The level of γ-H2AX protein in irradiated rat and human lymphocytes was significantly reduced by inhibitors of ATM and DNA-PKcs. Surprisingly, unlike human granulocytes, rat granulocytes with DNA-PKcs deficiency displayed a rapid accumulation, but delayed disappearance of γ-H2AX foci with essentially no change from 10 h to 48 h post-irradiation. Furthermore, inhibition of ATM activity in rat granulocytes also decreased radiation-induced γ-H2AX foci formation. In comparison, human granulocytes showed no response to irradiation regarding γ-H2AX, p-ATM or p-DNA-PKcs foci. Importantly, incidence of γ-H2AX foci in lymphocytes after total-body radiation of rats was consistent with that of in vitro irradiation of rat lymphocytes. These findings show that rats are a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans. ATM and DNA-PKcs participate together in DSB repair in rat lymphocytes similar to that of human lymphocytes. Further, rat granulocytes, which have the characteristic of delayed disappearance of γ-H2AX foci in response to radiation, may be a useful experimental system for biodosimetry studies.

  3. Survival Fraction at 2 Gy and γH2AX Expression Kinetics in Peripheral Blood Lymphocytes From Cancer Patients: Relationship With Acute Radiation-Induced Toxicities

    Energy Technology Data Exchange (ETDEWEB)

    Pouliliou, Stamatia E. [Department of Radiotherapy/Oncology, Radiobiology and Radiopathology Unit, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Lialiaris, Theodoros S. [Department of Medical Genetics, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Dimitriou, Thespis [Department of Anatomy, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Giatromanolaki, Alexandra [Department of Pathology, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Papazoglou, Dimitrios [Department of Internal Medicine, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Pappa, Aglaia [Department of Molecular Biology and Genetics, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Pistevou, Kyriaki [Department of Radiotherapy/Oncology, Aristotle University of Thessalonica, Thessalonica (Greece); Kalamida, Dimitra [Department of Radiotherapy/Oncology, Radiobiology and Radiopathology Unit, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece); Koukourakis, Michael I., E-mail: targ@her.forthnet.gr [Department of Radiotherapy/Oncology, Radiobiology and Radiopathology Unit, School of Health Sciences, Democritus University of Thrace, Alexandroupolis (Greece)

    2015-07-01

    Purpose: Predictive assays for acute radiation toxicities would be clinically relevant in radiation oncology. We prospectively examined the predictive role of the survival fraction at 2 Gy (SF2) and of γH2AX (double-strand break [DSB] DNA marker) expression kinetics in peripheral blood mononuclear cells (PBMCs) from cancer patients before radiation therapy. Methods and Materials: SF2 was measured with Trypan Blue assay in the PBMCs from 89 cancer patients undergoing radiation therapy at 4 hours (SF2{sub [4h]}) and 24 hours (SF2{sub [24h]}) after ex vivo irradiation. Using Western blot analysis and band densitometry, we further assessed the expression of γH2AX in PBMC DNA at 0 hours, 30 minutes, and 4 hours (33 patients) and 0 hour, 4 hours, and 24 hours (56 patients), following ex vivo irradiation with 2 Gy. Appropriate ratios were used to characterize each patient, and these were retrospectively correlated with early radiation therapy toxicity grade. Results: The SF2{sub (4h)} was inversely correlated with the toxicity grade (P=.006). The γH2AX-ratio{sub (30min)} (band density of irradiated/non-irradiated cells at 30 minutes) revealed, similarly, a significant inverse association (P=.0001). The DSB DNA repair rate from 30 minutes to 4 hours, calculated as the relative RγH2AX-ratio (γH2AX-ratio{sub (4h)}/γH2AX-ratio{sub (30min)}) showed a significant direct association with high toxicity grade (P=.01). Conclusions: Our results suggest that SF2 is a significant radiation sensitivity index for patients undergoing radiation therapy. γH2AX Western blot densitometry analysis provided 2 important markers of normal tissue radiation sensitivity. Low γH2AX expression at 30 minutes was linked with high toxicity grade, suggesting that poor γH2AX repair activity within a time frame of 30 minutes after irradiation predicts for poor radiation tolerance. On the other hand, rapid γH2AX content restoration at 4 hours after irradiation, compatible with

  4. Survival Fraction at 2 Gy and γH2AX Expression Kinetics in Peripheral Blood Lymphocytes From Cancer Patients: Relationship With Acute Radiation-Induced Toxicities

    International Nuclear Information System (INIS)

    Pouliliou, Stamatia E.; Lialiaris, Theodoros S.; Dimitriou, Thespis; Giatromanolaki, Alexandra; Papazoglou, Dimitrios; Pappa, Aglaia; Pistevou, Kyriaki; Kalamida, Dimitra; Koukourakis, Michael I.

    2015-01-01

    Purpose: Predictive assays for acute radiation toxicities would be clinically relevant in radiation oncology. We prospectively examined the predictive role of the survival fraction at 2 Gy (SF2) and of γH2AX (double-strand break [DSB] DNA marker) expression kinetics in peripheral blood mononuclear cells (PBMCs) from cancer patients before radiation therapy. Methods and Materials: SF2 was measured with Trypan Blue assay in the PBMCs from 89 cancer patients undergoing radiation therapy at 4 hours (SF2 [4h] ) and 24 hours (SF2 [24h] ) after ex vivo irradiation. Using Western blot analysis and band densitometry, we further assessed the expression of γH2AX in PBMC DNA at 0 hours, 30 minutes, and 4 hours (33 patients) and 0 hour, 4 hours, and 24 hours (56 patients), following ex vivo irradiation with 2 Gy. Appropriate ratios were used to characterize each patient, and these were retrospectively correlated with early radiation therapy toxicity grade. Results: The SF2 (4h) was inversely correlated with the toxicity grade (P=.006). The γH2AX-ratio (30min) (band density of irradiated/non-irradiated cells at 30 minutes) revealed, similarly, a significant inverse association (P=.0001). The DSB DNA repair rate from 30 minutes to 4 hours, calculated as the relative RγH2AX-ratio (γH2AX-ratio (4h) /γH2AX-ratio (30min) ) showed a significant direct association with high toxicity grade (P=.01). Conclusions: Our results suggest that SF2 is a significant radiation sensitivity index for patients undergoing radiation therapy. γH2AX Western blot densitometry analysis provided 2 important markers of normal tissue radiation sensitivity. Low γH2AX expression at 30 minutes was linked with high toxicity grade, suggesting that poor γH2AX repair activity within a time frame of 30 minutes after irradiation predicts for poor radiation tolerance. On the other hand, rapid γH2AX content restoration at 4 hours after irradiation, compatible with efficient DSB repair ability

  5. X-ray induced formation of γ-H2AX foci after full-field digital mammography and digital breast-tomosynthesis.

    Directory of Open Access Journals (Sweden)

    Siegfried A Schwab

    Full Text Available PURPOSE: To determine in-vivo formation of x-ray induced γ-H2AX foci in systemic blood lymphocytes of patients undergoing full-field digital mammography (FFDM and to estimate foci after FFDM and digital breast-tomosynthesis (DBT using a biological phantom model. MATERIALS AND METHODS: The study complies with the Declaration of Helsinki and was performed following approval by the ethic committee of the University of Erlangen-Nuremberg. Written informed consent was obtained from every patient. For in-vivo tests, systemic blood lymphocytes were obtained from 20 patients before and after FFDM. In order to compare in-vivo post-exposure with pre-exposure foci levels, the Wilcoxon matched pairs test was used. For in-vitro experiments, isolated blood lymphocytes from healthy volunteers were irradiated at skin and glandular level of a porcine breast using FFDM and DBT. Cells were stained against the phosphorylated histone variant γ-H2AX, and foci representing distinct DNA damages were quantified. RESULTS: Median in-vivo foci level/cell was 0.086 (range 0.067-0.116 before and 0.094 (0.076-0.126 after FFDM (p = 0.0004. In the in-vitro model, the median x-ray induced foci level/cell after FFDM was 0.120 (range 0.086-0.140 at skin level and 0.035 (range 0.030-0.050 at glandular level. After DBT, the median x-ray induced foci level/cell was 0.061 (range 0.040-0.081 at skin level and 0.015 (range 0.006-0.020 at glandular level. CONCLUSION: In patients, mammography induces a slight but significant increase of γ-H2AX foci in systemic blood lymphocytes. The introduced biological phantom model is suitable for the estimation of x-ray induced DNA damages in breast tissue in different breast imaging techniques.

  6. Gamma-H2Ax quantification of low dose irradiation-induced DNA damage in patients receiving intensity modulated radiotherapy (IRMT)

    International Nuclear Information System (INIS)

    Sivabalasingham, S.; Short, S.; Worku, M.; Marks, G.; Guerrero-Urbano, T.

    2013-01-01

    The full text of the publication follows. Purpose/Objective: IMRT (Intensity Modulated Radiotherapy) offers greater target dose compliance yet may produce a comparative higher whole body dose. The aim of this study is to quantify γH2Ax foci in lymphocytes (an established marker of DNA double strand breaks) in patients undergoing IMRT. Material/Methods: Radical inverse planned IMRT was delivered to patients with brain tumours. Peripheral blood samples were collected from each patient at the following time points: baseline; weekly- prior to and 30 minutes after one treatment fraction; 2 and 6 weeks following completion of treatment. Whole blood was centrifuged to separate lymphocytes, which were fixed and stained for fluorescent immunocytochemistry. 150 cells per sample were visualized. γH2Ax foci were identified and counted using confocal microscopy. Results A low basal level of foci was present in all samples prior to any radiation exposure (0.233, SD 0.028). There was a significant increase in mean foci per cell in post radiotherapy treatment samples(0.367 foci per cell pre-treatment and 0.612 foci per cell post treatment, p=0.000) and no significant difference between post-treatment foci numbers at different times during treatment(for example, 0.518 foci per cell at week 1 and 0.760 at week 6, p=0.279). Mean foci numbers returned to background levels at 6 weeks following completion of radiotherapy (0.239 foci per cell at baseline and 0.219 foci per cell at 6 weeks, p=0.529). Comparison between patients treated with different delivery methods is ongoing. Conclusion: γH2Ax is a feasible marker of DNA damage in lymphocytes during IMRT. These data demonstrate a reproducible level of foci induction in patients undergoing IMRT for tumour targets in brain. There is no significant accumulation of foci during treatment and foci numbers return to baseline post treatment. This assay may be useful to assess differences in whole body dose when different delivery methods

  7. DNA-PK inhibition causes a low level of H2AX phosphorylation and homologous recombination repair in Medaka (Oryzias latipes) cells

    International Nuclear Information System (INIS)

    Urushihara, Yusuke; Kobayashi, Junya; Matsumoto, Yoshihisa; Komatsu, Kenshi; Oda, Shoji; Mitani, Hiroshi

    2012-01-01

    Highlights: ► We investigated the effect of DNA-PK inhibition on DSB repair using fish cells. ► A radiation sensitive mutant RIC1 strain showed a low level of DNA-PK activity. ► DNA-PK dysfunction leads defects in HR repair and DNA-PKcs autophosphorylation. ► DNA-PK dysfunction leads a slight increase in the number of 53BP1 foci after DSBs. ► DNA-PK dysfunction leads an alternative NHEJ that depends on 53BP1. -- Abstract: Nonhomologous end joining (NHEJ) and homologous recombination (HR) are known as DNA double-strand break (DSB) repair pathways. It has been reported that DNA-PK, a member of PI3 kinase family, promotes NHEJ and aberrant DNA-PK causes NHEJ deficiency. However, in this study, we demonstrate that a wild-type cell line treated with DNA-PK inhibitor and a mutant cell line with dysfunctional DNA-PK showed decreased HR efficiency in fish cells (Medaka, Oryzias latipes). Previously, we reported that the radiation-sensitive mutant RIC1 strain has a defect in the Histone H2AX phosphorylation after γ-irradiation. Here, we showed that a DNA-PK inhibitor, NU7026, treatment resulted in significant reduction in the number of γH2AX foci after γ-irradiation in wild-type cells, but had no significant effect in RIC1 cells. In addition, RIC1 cells showed significantly lower levels of DNA-PK kinase activity compared with wild-type cells. We investigated NHEJ and HR efficiency after induction of DSBs. Wild-type cells treated with NU7026 and RIC1 cells showed decreased HR efficiency. These results indicated that aberrant DNA-PK causes the reduction in the number of γH2AX foci and HR efficiency in RIC1 cells. We performed phosphorylated DNA-PKcs (Thr2609) and 53BP1 focus assay after γ-irradiation. RIC1 cells showed significant reduction in the number of phosphorylated DNA-PKcs foci and no deference in the number of 53BP1 foci compared with wild-type cells. These results suggest that low level of DNA-PK activity causes aberrant DNA-PKcs autophosphorylation

  8. Investigation of early DNA damage after radioiodine therapy in patients with thyroid cancer using the gamma-H2AX focus assay

    International Nuclear Information System (INIS)

    Eberlein, U.; Lassmann, M.; Bluemel, C.; Buck, A.K.; Nowak, C.; Meineke, V.; Scherthan, H.

    2015-01-01

    Full text of publication follows. Objectives: the Aim of the study is to investigate the DNA damage formation in blood lymphocytes and the correlation to the absorbed dose to the blood in patients with differentiated thyroid carcinoma (DTC) after their first radionuclide therapy with I-131 as measured by the induction, persistence and decay behaviour of γ-H2AX and 53BP1 DNA damage-induced foci. Radiation-induced DNA double strand breaks (DSBs) cause in their vicinity the formation of microscopically visible foci of the phospho-histone H2AX (γ-H2AX) and the 53BP1 protein that binds to and signals damaged chromatin at the DSB site. Nuclear foci containing both markers thus represent radiation-induced DSBs. Methods: we investigated 19 patients with DTC during the first treatment with 3.5±0.3 GBq I-131. Between 7 and 10 sequential peripheral blood samples (at least four within the first 5 hours) were taken before and between 0.5 h and 144 h post administration. The physical dosimetry procedures were performed according to the EANM DTC SOP. White blood cells were recovered by density centrifugation in CPT tubes (BD Biosciences) and subjected to two-colour immunofluorescence staining. The average frequencies of the radiation-induced γ-H2AX foci/nucleus that co localized with 53BP1 foci were derived from immuno-stained mononuclear peripheral blood lymphocyte samples. The number of foci was counted manually using a red/green double band pass filter (Chroma) in a Zeiss microscope by an experienced observer. Results: The mean I-131 absorbed dose to the blood was (0.04±0.01) Gy at t=2 h, (0.07±0.02) Gy at t=4 h, and (0.21±0.05) Gy at t=24 h, respectively. The mean value of the total absorbed dose to the blood was (0.36±0.08) Gy. The highest number of radiation-induced foci per nucleus (RIF) and per absorbed dose (median: 8.8 RIF/Gy, range 3.1-10.9 RIF/Gy) was observed in the first three hours post administration. Four hours after radioiodine administration the number

  9. In vitro evaluation of relative biological effectiveness of 3MeV protons using γH2AX immuno-fluorescence

    International Nuclear Information System (INIS)

    Chaurasia, Rajesh K.; Desai, Utkarsha; Sirsath, K.B.; Bhat, N.N.; Sapra, B.K.; Gaur, Neeraj

    2018-01-01

    Use of charged particles for treating complicated tumors is gaining momentum. Their defined dose profile, near zero dose to normal tissue beyond tumour, skin sparing, more lethal effect than mutations, ability to focus beam with complex geometries are some of the advantages. Lack of scientific information on radiobiological efficacy, complexity and cost/maintenance of such facilities are hindering their use at present. Though a huge amount of time and resources are invested cancer treatment still primarily depends on chemotherapy and radiotherapy (γ-ray). Through this study we aim to demonstrate relative biological effectiveness of 3MeV proton beam with estimated LET of 13 keV/μm on cancerous mammalian cell line using highly reliable DNA double strand break γH2AX marker as a damage quantification tool

  10. Gamma-H2AX biodosimetry for use in large scale radiation incidents: comparison of a rapid ‘96 well lyse/fix’ protocol with a routine method

    Directory of Open Access Journals (Sweden)

    Jayne Moquet

    2014-03-01

    Full Text Available Following a radiation incident, preliminary dose estimates made by γ-H2AX foci analysis can supplement the early triage of casualties based on clinical symptoms. Sample processing time is important when many individuals need to be rapidly assessed. A protocol was therefore developed for high sample throughput that requires less than 0.1 ml blood, thus potentially enabling finger prick sampling. The technique combines red blood cell lysis and leukocyte fixation in one step on a 96 well plate, in contrast to the routine protocol, where lymphocytes in larger blood volumes are typically separated by Ficoll density gradient centrifugation with subsequent washing and fixation steps. The rapid ‘96 well lyse/fix’ method reduced the estimated sample processing time for 96 samples to about 4 h compared to 15 h using the routine protocol. However, scoring 20 cells in 96 samples prepared by the rapid protocol took longer than for the routine method (3.1 versus 1.5 h at zero dose; 7.0 versus 6.1 h for irradiated samples. Similar foci yields were scored for both protocols and consistent dose estimates were obtained for samples exposed to 0, 0.2, 0.6, 1.1, 1.2, 2.1 and 4.3 Gy of 250 kVp X-rays at 0.5 Gy/min and incubated for 2 h. Linear regression coefficients were 0.87 ± 0.06 (R2 = 97.6% and 0.85 ± 0.05 (R2 = 98.3% for estimated versus actual doses for the routine and lyse/fix method, respectively. The lyse/fix protocol can therefore facilitate high throughput processing for γ-H2AX biodosimetry for use in large scale radiation incidents, at the cost of somewhat longer foci scoring times.

  11. Duodenal crypt health following exposure to Cr(VI): Micronucleus scoring, γ-H2AX immunostaining, and synchrotron X-ray fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Chad M.; Wolf, Jeffrey C.; Elbekai, Reem H.; Paranjpe, Madhav G.; Seiter, Jennifer M.; Chappell, Mark A.; Tappero, Ryan V.; Suh, Mina; Proctor, Deborah M.; Bichteler, Anne; Haws, Laurie C.; Harris, Mark A.

    2015-08-01

    Lifetime exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water results in intestinal damage and an increase in duodenal tumors in B6C3F1 mice. To assess whether these tumors could be the result of a direct mutagenic or genotoxic mode of action, we conducted a GLP-compliant 7-day drinking water study to assess crypt health along the entire length of the duodenum. Mice were exposed to water (vehicle control), 1.4, 21, or 180 ppm Cr(VI) via drinking water for 7 consecutive days. Crypt enterocytes in Swiss roll sections were scored as normal, mitotic, apoptotic, karyorrhectic, or as having micronuclei. A single oral gavage of 50 mg/kg cyclophosphamide served as a positive control for micronucleus induction. Exposure to 21 and 180 ppm Cr(VI) significantly increased the number of crypt enterocytes. Micronuclei and γ-H2AX immunostaining were not elevated in the crypts of Cr(VI)-treated mice. In contrast, treatment with cyclophosphamide significantly increased numbers of crypt micronuclei and qualitatively increased γ-H2AX immunostaining. Synchrotron-based X-ray fluorescence (XRF) microscopy revealed the presence of strong Cr fluorescence in duodenal villi, but negligible Cr fluorescence in the crypt compartment. Together, these data indicate that Cr(VI) does not adversely effect the crypt compartment where intestinal stem cells reside, and provide additional evidence that the mode of action for Cr(VI)-induced intestinal cancer in B6C3F1 mice involves chronic villous wounding resulting in compensatory crypt enterocyte hyperplasia.

  12. In vitro studies for the introduction of γ-H2AX foci as an indicator of radiation damage in peripheral blood lymphocytes

    International Nuclear Information System (INIS)

    Mandina, Tania; Garcia, Omar; Roch-Lefevre, Sandrine; Voisin, Pascale; Voisin, Philippe; Roy, Laurence

    2008-01-01

    Biological indicators are used for assessing DNA damage and repair in cells exposed to ionising radiation. DNA Double-strand breaks (DSBs) have been known as one of the most significant lesion producing lethal and mutagenic effects in irradiated cells. A new biological marker for DSBs is the presence of γ-H2AX foci in cells nucleus after exposure to ionising radiation. γ-H2AX formation was analysed in human lymphocytes. The blood was obtained from a same donor in three different occasions and exposed to doses of 0, 0.2 and 0.5 Gy of gamma rays with a dose-rate of 1.2 Gy/min. After blood irradiation the lymphocytes were incubated 30 minutes at 37 C degrees, isolated, fixed with paraformaldehyde, and spread on a microscope slide using a Cytospin. The slides were stored at -20 C degrees and immuno-stained the next day and 14, 16, 27 and 37 days after irradiation to test the influence of the storage time on results. The number of foci per cell was scored automatically, in about 200 cells per dose using HISTOLAB and CARTOGRAPH software. The mean of number of foci/cell for samples was as follow 0 Gy= 0.15 ± 0.04, 0.2 Gy =2.06 ± 0.25 and 0.5 Gy=5.21 ± 0.36 without appreciable effect of the storage time on the final results. Nevertheless some aspects require additional research, particularly the background values of the assay. A higher variability of DNA damage was observed for control samples, than for exposed ones. The influence of the number of cells scored on this variability should be tested. (author)

  13. Mean frequency and relative fluorescence intensity measurement of γ-H2AX foci dose response in PBL exposed to γ-irradiation: An inter- and intra-laboratory comparison and its relevance for radiation triage.

    Science.gov (United States)

    Venkateswarlu, Raavi; Tamizh, Selvan G; Bhavani, Manivannan; Kumar, Arun; Alok, Amit; Karthik, Kanagaraj; Kalra, Namita; Vijayalakshmi, J; Paul, Solomon F D; Chaudhury, N K; Venkatachalam, Perumal

    2015-12-01

    Measurement of γ-H2AX protein changes in the peripheral blood lymphocytes (PBL) of individuals exposed to ionizing radiation is a simple, sensitive, and rapid assay for radiation triage and early marker of dose estimation. The qualitative and quantitative measurements of the protein changes were examined using flow cytometry and microscopy. Whole blood and isolated lymphocytes were exposed in vitro between 0.1 and 5 Gy doses of (60) Co γ-radiation at a dose rate of 1 Gy/min. Radiation induced γ-H2AX foci frequency (n = 3) and relative fluorescence intensity (n = 7) in PBL was measured at 0.5 and 2 hrs postexposure. The observed dose response for γ-H2AX foci frequency at both time points, for whole blood and isolated lymphocytes did not show any significant (P > 0.05) differences. However, when compared with γ-H2AX foci frequency scored manually (microscopy), the semiautomated analysis (captured images) showed a better correlation (r(2) = 0.918) than that obtained with automated (Metafer) scoring (r(2) = 0.690). It is noteworthy to mention that, the γ-H2AX foci frequency quantified using microscopy showed a dose dependent increase up to 2 Gy and the relative fluorescence intensity (RFI) measured with flow cytometry revealed an increase up to 5 Gy in the PBL exposed in vitro. Moreover, a better correlation was observed between the γ-H2AX foci frequency obtained by manual scoring and RFI (r(2) = 0.910). Kinetic studies showed that the γ-H2AX foci remain more or less unchanged up to 4 hrs and reduces gradually over 48 hrs of postexposure at 37°C. Further, inter and intra-laboratory comparisons showed consistency in the scoring of γ-H2AX foci frequency by manual and semiautomated scoring. The overall results suggest that measurement of γ-H2AX (microscopy and flow cytometry) should be employed within 4 to 6 hrs for a reliable dosimetry either by sharing the work load between the laboratories or investing more manpower; however, triage can be possible even up

  14. Induction and disappearance of γH2AX foci and formation of micronuclei after exposure of human lymphocytes to ⁶⁰Co γ-rays and p(66)+ Be(40) neutrons.

    Science.gov (United States)

    Vandersickel, Veerle; Beukes, Philip; Van Bockstaele, Bram; Depuydt, Julie; Vral, Anne; Slabbert, Jacobus

    2014-02-01

    To investigate both the formation of micronuclei (MN) and the induction and subsequent loss of phosphorylated histone H2AX foci (γH2AX foci) after in vitro exposure of human lymphocytes to either (60)Co γ-rays or p(66)+ Be(40) neutrons. MN dose response (DR) curves were obtained by exposing isolated lymphocytes of 10 different donors to doses ranging from 0-4 Gy γ-rays or 0-2 Gy neutrons. Also, γH2AX foci DR curves were obtained following exposure to doses ranging from 0-0.5 Gy of either γ-rays or neutrons. Foci kinetics for lymphocytes for a single donor exposed to 0.5 Gy γ-rays or neutrons were studied up to 24 hours post-irradiation. Micronuclei yields following neutron exposure were consistently higher compared to that from (60)Co γ-rays. All MN yields were over-dispersed compared to a Poisson distribution. Over-dispersion was higher after neutron irradiation for all doses > 0.1 Gy. Up to 4 hours post-irradiation lower yields of neutron-induced γH2AX foci were observed. Between 4 and 24 hours the numbers of foci from neutrons were consistently higher than that from γ-rays. The half-live of foci disappearance is only marginally longer for neutrons compared to that from γ-rays. Foci formations were more likely to be over-dispersed for neutron irradiations. Although neutrons are more effective to induce MN, the absolute number of induced γH2AX foci are less at first compared to γ-rays. With time neutron-induced foci are more persistent. These findings are helpful for using γH2AX foci in biodosimetry and to understand the repair of neutron-induced cellular damage.

  15. Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen; Parvin, Bahram; Rydberg, Bjorn

    2010-12-22

    To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.

  16. In vitro H2AX phosphorylation and micronuclei induction in human fibroblasts across the Bragg curve of a 577MeV/nucleon Fe incident beam

    Energy Technology Data Exchange (ETDEWEB)

    Desai, N. [NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX (United States); Sodolak, J. [Prairie View A and M University, Prairie View, TX (United States); Gersey, B. [Prairie View A and M University, Prairie View, TX (United States); Durante, M. [University Federico II, Naples (Italy); Lin, Z.W. [University of Alabama in Huntsville, Huntsville, AL (United States); Rusek, A. [Brookhaven National Laboratory, Upton, NY (United States); Cucinotta, F.A. [NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX (United States); Wu, H. [NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX (United States)]. E-mail: honglu.wu-1@nasa.gov

    2006-10-15

    The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the only major protection to astronauts from harmful exposure. Unlike low-linear energy transfer (LET) {gamma} or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure, since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak. The Bragg curve does not necessarily represent the biological damage along the particle traversal, and the 'biological Bragg curve' is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Here we used a unique irradiation geometry to measure the biological response across the Bragg curve in human fibroblasts exposed to 577MeV/nucleon incident Fe ions in vitro. Polyethylene shielding was used to achieve a Bragg curve distribution with the beam geometry parallel to a monolayer of fibroblast cells. Qualitative analyses of {gamma}-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high-LET particle traversal of cells beyond the Bragg peak in agreement with one-dimensional transport approximations. A quantitative biological response curve generated for micronuclei induction across the Bragg curve did not reveal an increased yield of micronuclei at the location of the Bragg peak. However, the percentage of mononucleated cells, which indicates inhibition in cell progression, increased at the location of the peak. These results confirm the argument that severely damaged cells at the Bragg peak, as observed by increased {gamma}-H2AX formation, are likely to go through reproduction death. Depending on the LET value of the primary particles, the yield of

  17. Persistence of Gamma-H2AX Foci in Irradiated Bronchial Cells Correlates with Susceptibility to Radiation Associated Lung Cancer in Mice

    Science.gov (United States)

    Ochola, Donasian O.; Sharif, Rabab; Bedford, Joel S.; Keefe, Thomas J.; Kato, Takamitsu A.; Fallgren, Christina M.; Demant, Peter; Costes, Sylvain V.; Weil, Michael M.

    2018-01-01

    The risk of developing radiation-induced lung cancer differs between different strains of mice, but the underlying cause of the strain differences is unknown. Strains of mice also differ in their ability to efficiently repair DNA double strand breaks resulting from radiation exposure. We phenotyped mouse strains from the CcS/Dem recombinant congenic strain set for their efficacy in repairing DNA double strand breaks during protracted radiation exposures. We monitored persistent gamma-H2AX radiation induced foci (RIF) 24 hours after exposure to chronic gamma-rays as a surrogate marker for repair deficiency in bronchial epithelial cells for 17 of the CcS/Dem strains and the BALB/cHeN founder strain. We observed a very strong correlation R2 = 79.18%, P cancer percent incidence measured in the same strains. Interestingly, spontaneous levels of foci in non-irradiated strains also showed good correlation with lung cancer incidence (R2=32.74%, P =0.013). These results suggest that genetic differences in DNA repair capacity largely account for differing susceptibilities to radiation-induced lung cancer among CcS/Dem mouse strains and that high levels of spontaneous DNA damage is also a relatively good marker of cancer predisposition. In a smaller pilot study, we found that the repair capacity measured in peripheral blood leucocytes also correlated well with radiogenic lung cancer susceptibility, raising the possibility that such phenotyping assay could be used to detect radiogenic lung cancer susceptibility in humans.

  18. Oocyte exposure to ZnO nanoparticles inhibits early embryonic development through the γ-H2AX and NF-κB signaling pathways.

    Science.gov (United States)

    Liu, Jing; Zhao, Yong; Ge, Wei; Zhang, Pengfei; Liu, Xinqi; Zhang, Weidong; Hao, Yanan; Yu, Shuai; Li, Lan; Chu, Meiqiang; Min, Lingjiang; Zhang, Hongfu; Shen, Wei

    2017-06-27

    The impacts of zinc oxide nanoparticles on embryonic development following oocyte stage exposure are unknown and the underlying mechanisms are sparsely understood. In the current investigation, intact nanoparticles were detected in ovarian tissue in vivo and cultured cells in vitro under zinc oxide nanoparticles treatment. Zinc oxide nanoparticles exposure during the oocyte stage inhibited embryonic development. Notably, in vitro culture data closely matched in vivo embryonic data, in that the impairments caused by Zinc oxide nanoparticles treatment passed through cell generations; and both gamma-H2AX and NF-kappaB pathways were involved in zinc oxide nanoparticles caused embryo-toxicity. Copper oxide and silicon dioxide nanoparticles have been used to confirm that particles are important for the toxicity of zinc oxide nanoparticles. The toxic effects of zinc oxide nanoparticles emanate from both intact nanoparticles and Zn2+. Our investigation along with others suggests that zinc oxide nanoparticles are toxic to the female reproductive system [ovaries (oocytes)] and subsequently embryo-toxic and that precaution should be taken regarding human exposure to their everyday use.

  19. Conformational temperature-dependent behavior of a histone H2AX: a coarse-grained Monte Carlo approach via knowledge-based interaction potentials.

    Directory of Open Access Journals (Sweden)

    Miriam Fritsche

    Full Text Available Histone proteins are not only important due to their vital role in cellular processes such as DNA compaction, replication and repair but also show intriguing structural properties that might be exploited for bioengineering purposes such as the development of nano-materials. Based on their biological and technological implications, it is interesting to investigate the structural properties of proteins as a function of temperature. In this work, we study the spatial response dynamics of the histone H2AX, consisting of 143 residues, by a coarse-grained bond fluctuating model for a broad range of normalized temperatures. A knowledge-based interaction matrix is used as input for the residue-residue Lennard-Jones potential.We find a variety of equilibrium structures including global globular configurations at low normalized temperature (T* = 0.014, combination of segmental globules and elongated chains (T* = 0.016,0.017, predominantly elongated chains (T* = 0.019,0.020, as well as universal SAW conformations at high normalized temperature (T* ≥ 0.023. The radius of gyration of the protein exhibits a non-monotonic temperature dependence with a maximum at a characteristic temperature (T(c* = 0.019 where a crossover occurs from a positive (stretching at T* ≤ T(c* to negative (contraction at T* ≥ T(c* thermal response on increasing T*.

  20. γH2AX/53BP1 foci as a potential pre-treatment marker of HNSCC tumors radiosensitivity - preliminary methodological study and discussion

    Science.gov (United States)

    Falk, Martin; Horakova, Zuzana; Svobodova, Marketa; Masarik, Michal; Kopecna, Olga; Gumulec, Jaromir; Raudenska, Martina; Depes, Daniel; Bacikova, Alena; Falkova, Iva; Binkova, Hana

    2017-09-01

    In order to improve patients' post-treatment quality of life, a shift from surgery to non-surgical (chemo)radio-treatment is recognized in head and neck oncology. However, about half of HNSCC tumors are resistant to irradiation and an efficient marker of individual tumor radiosensitivity is still missing. We analyzed whether various parameters of DNA double strand break (DSB) repair determined in vitro can predict, prior to clinical treatment initiation, the radiosensitivity of tumors. We compared formation and decrease of γH2AX/53BP1 foci in 48 h after irradiating tumor cell primocultures with 2 Gy of γ-rays. To better understand complex tumor behavior, three different cell type primocultures - CD90-, CD90+, and a mixed culture of these cells - were isolated from 1 clinically radioresistant, 2 radiosensitive, and 4 undetermined HPV-HNSCC tumors and followed separately. While DSB repair was delayed and the number of persisting DSBs increased in the radiosensitive tumors, the results for the radioresistant tumor were similar to cultured normal human skin fibroblasts. Hence, DSB repair kinetics/efficiency may correlate with clinical response to radiotherapy for a subset of HNSCC tumors but the size (and therefore practical relevance) of this subset remains to be determined. The same is true for contribution of different cell type primocultures to tumor radioresistance.

  1. γ-H2AX foci analysis in human lymphocytes: a biological tool for assessment of early triage during mass exposure of radiation

    International Nuclear Information System (INIS)

    Nayak, Akshay Kumar A.; Mumbrekar, Kamalesh D.; Satish Rao, B.S.

    2014-01-01

    Emergence of nuclear terrorism and increased use of nuclear technology for industry, energy production, and defence purpose has also increased the risk of mass exposure to radiation. During these scenarios of mass exposure to radiation, an efficient system which would measure the dose absorbed by an individual is required for early triage management. The present study aims to establish γ-H2AX as a biomarker for management of early triage. Radiation induced DNA DSB studied in lymphocytes isolated from 10 healthy individuals and challenged with 2 Gy of X-rays in vitro showed a gradual decrease in number of foci signals. As the persistence of foci signals is important for biodosimetry, phosphatase inhibitors like Calyculin A, Fostriecin and Okadiac Acid were used. Calyculin A was found to be the better inhibitor showing a 2 fold increase in retention of foci signals at 6 hours. The dose response curve was performed in lymphocytes isolated from healthy individuals by fluorescent microscopy and flow cytometry. Although both the methods indicated a linear increase in foci signals, microscopic analysis was found to be more sensitive. Influence of age and gender on dose response curve was studied and no significant difference was found. The effect of confounding factors like genetic factors and smoking habits on the dose response curve is being investigated. (author)

  2. A non-linear detection of phospho-histone H2AX in EA.hy926 endothelial cells following low-dose X-irradiation is modulated by reactive oxygen species

    International Nuclear Information System (INIS)

    Large, Martin; Reichert, Sebastian; Hehlgans, Stephanie; Fournier, Claudia; Rödel, Claus; Rödel, Franz

    2014-01-01

    A discontinuous dose response relationship is a major characteristic of the anti-inflammatory effects of low-dose X-irradiation therapy. Although recent data indicate an involvement of a variety of molecular mechanisms in these characteristics, the impact of reactive oxygen species (ROS) production to give rise or contribute to these phenomena in endothelial cells (EC) remains elusive. HUVEC derived immortalized EA.hy926 cells were stimulated by tumor necrosis factor-α (TNF-α, 20 ng/ml) 4 h before irradiation with doses ranging from 0.3 to 1 Gy. To analyse DNA repair capacity, phospho-histone H2AX foci were assayed at 1 h, 4 h and 24 h after irradiation. ROS production and superoxide dismutase (SOD) activity were analysed by fluorometric 2′,7′-dichlorodihydrofluorescein-diacetate (H2DCFDA) and colorimetric assays. A functional impact of ROS on γH2AX production was analysed by treatment with the scavenger N-acetyl-L-cysteine (NAC). Irrespective of stimulation by TNF-α, EA.hy926 cells revealed a linear dose response characteristic of γH2AX foci detection at 1 h and 4 h after irradiation. By contrast, we observed a discontinuity in residual γH2AX foci detection at 24 h after irradiation with locally elevated values following a 0.5 Gy exposure that was abolished by inhibition of ROS by NAC. Moreover, SOD protein expression was significantly decreased at doses of 0.5 Gy and 0.7 Gy concomitant with a reduced SOD activity. These data implicate a non-linear regulation of ROS production and SOD activity in EA.hy926 EC following irradiation with doses < 1 Gy that may contribute to a discontinuous dose-response relationship of residual γH2AX foci detection

  3. Clustering of DSB in DNA by X-Ray and a-particle irradiation in MCF-7 cells studied with anti γ-H2AX

    International Nuclear Information System (INIS)

    Tapia, O.; Soto, J.; Castro, F.A.; Berciano, Ma T; Lafarga, M.; Cos, S.; Sanchez-Barcelo, E.

    2007-01-01

    Among the effects produced by the ionizing radiations in cellular DNA, double strand breaks (DSB) are considered particularly important. These ruptures and their grouping in certain points, clustering, are acknowledged as the cause for mutagenic effects and cellular death. In this work we present the methodology and the results of the application of the DSB - DNA marking technique by using anti γ-H2AX, taking human cancerous cells MCF-7 as model and X-rays and a particles as irradiation agents. The obtained results are showed in a qualitative way like a set of figures. Are shows the effects of a dose of 2 Gy X-rays in the DSB - DNA after 30 minutes of the irradiation that responds to a certain pattern in which a spatially homogenous irradiation interacts with the DNA. As in previous case, the effects of X-rays in the DSB - DNA shows a different pattern affecting the cells that are in mitosis. Also, the effects of a dose of 2 Gy X-rays obtained after 24 hours of irradiation shows a number of DSB smaller, which is indicative of the repairing process. The results of the irradiation with a dose of 0.1 Gy originated from a particles cause a smaller number of DSB. Nevertheless, the existence of a bigger clustering with the appearance of clearly more intense points is appraised. Also, the effect of the irradiation is showed as an aligned trace of clusters that is possible to attribute to the passing of a a particle through the cellular nucleus. (Author)

  4. The comparative in vitro assessment of e-cigarette and cigarette smoke aerosols using the γH2AX assay and applied dose measurements.

    Science.gov (United States)

    Thorne, David; Larard, Sophie; Baxter, Andrew; Meredith, Clive; Gaҫa, Marianna

    2017-01-04

    DNA damage can be caused by a variety of external and internal factors and together with cellular responses, can establish genomic instability through multiple pathways. DNA damage therefore, is considered to play an important role in the aetiology and early stages of carcinogenesis. The DNA-damage inducing potential of tobacco smoke aerosols in vitro has been extensively investigated; however, the ability of e-cigarette aerosols to induce DNA damage has not been extensively investigated. E-cigarette use has grown globally in recent years and the health implications of long term e-cigarette use are still unclear. Therefore, this study has assessed the induction of double-strand DNA damage in vitro using human lung epithelial cells to e-cigarette aerosols from two different product variants (a "cigalike" and a closed "modular" system) and cigarette smoke. A Vitrocell ® VC 10 aerosol exposure system was used to generate and dilute cigarette smoke and e-cigarette aerosols, which were delivered to human bronchial epithelial cells (BEAS-2Bs) housed at the air-liquid-interface (ALI) for up to 120min exposure (diluting airflow, 0.25-1L/min). Following exposure, cells were immediately fixed, incubated with primary (0.1% γH2AX antibody in PBS) and secondary antibodies (DyLight™ 549 conjugated goat anti-mouse IgG) containing Hoechst dye DNA staining solution (0.2% secondary antibody and 0.01% Hoechst in PBS), and finally screened using the Cellomics Arrayscan VTI platform. The results from this study demonstrate a clear DNA damage-induced dose response with increasing smoke concentrations up to cytotoxic levels. In contrast, e-cigarette aerosols from two product variants did not induce DNA damage at equivalent to or greater than doses of cigarette smoke aerosol. In this study dosimetry approaches were used to contextualize exposure, define exposure conditions and facilitate comparisons between cigarette smoke and e-cigarette aerosols. Quartz crystal microbalance (QCM

  5. Application of translocation, γ-H2AX, and Sam68 as a biological indicators for the assessment of radiation exposure in nuclear power plant workers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kwang Hee; Park, Hyung Sun; Nam, Seon Young [Korea Hydro Nuclear Power Co., Seoul (Korea, Republic of)

    2014-05-15

    This study showed that confirmation of the initial dose estimated by dicentric analysis is provided by the subsequent FISH analysis for translocation frequency and provides further evidence for the valid use of FISH as a retrospective biological dosimeter. The IAEA manual on cytogenetic dosimetry recommends a halftime value of 3 y to correct for the decrease of dicentrics in case of delayed sampling based on the patient data of Buckton. Support for this comes from the cytogenetic follow up of an individual exposed to tritium, which also indicated a decline in dicentrics with a half-time of ∼3 y. Naturally, the RBE of tritium, as well as other kinds of ionizing radiation, depends on the dose, exposure conditions, and studied parameters. The information about the RBE of tritium that is most important from an applied standpoint is that associated with the range of low doses. In our study, the dose dependence of tritium RBE was not identified because of very low dose Tritium (< 1mSv). However, The strong smooth relationship between translocation yield and age is shown in Table 2. The translocation yields reported here are only slightly lower than already published. The implication is that the increase of yield with age could be due to environmental factors, to a natural aging process or both. In addition, we confirmed that γ-H2AX and Sam68 associated with DNA damage and apoptosis, can be new biological indicators for radiation exposure. Radiation workers are exposed to ionizing radiation from various sources. Ionizing radiation produces several types of DNA lesion, including DNA base alterations, DNA. DNA cross-links, and single- and double-strand breaks. As a protocol for biological dosimetry recommended by IAEA (2001), the analysis of solid stained dicentric chromosomes has been used since the mid 1960s. The intervening years have seen great improvements bringing the technique to a point where dicentric analysis has become a routine component of the radiological

  6. Utility of γH2AX as a molecular marker of DNA double-strand breaks in nuclear medicine: applications to radionuclide therapy employing auger electron-emitting isotopes.

    Science.gov (United States)

    Mah, Li-Jeen; Orlowski, Christian; Ververis, Katherine; El-Osta, Assam; Karagiannis, Tom C

    2011-01-01

    There is an intense interest in the development of radiopharmaceuticals for cancer therapy. In particular, radiopharmaceuticals which involve targeting radionuclides specifically to cancer cells with the use of monoclonal antibodies (radioimmunotherapy) or peptides (targeted radiotherapy) are being widely investigated. For example, the ultra-short range Auger electron-emitting isotopes, which are discussed in this review, are being considered in the context of DNAtargeted radiotherapy. The efficient quantitative evaluation of the levels of damage caused by such potential radiopharmaceuticals is required for assessment of therapeutic efficacy and determination of relevant doses for successful treatment. The DNA double-strand break surrogate marker, γH2AX, has emerged as a useful biomonitor of damage and thus effectiveness of treatment, offering a highly specific and sensitive means of assessment. This review will cover the potential applications of γH2AX in nuclear medicine, in particular radionuclide therapy.

  7. The influence of x-ray contrast agents in computed tomography on the induction of dicentrics and {gamma}-H2AX foci in lymphocytes of human blood samples

    Energy Technology Data Exchange (ETDEWEB)

    Jost, G; Golfier, S; Pietsch, H; Lengsfeld, P; Voth, M [Bayer Schering Pharma AG, 13353 Berlin (Germany); Schmid, T E [Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universitaet Muenchen, 81675 Munich (Germany); Eckardt-Schupp, F [Institute of Radiation Biology, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg (Germany); Schmid, E [Institute for Cell Biology, Center for Integrated Protein Science, University of Munich, 80336 Muenchen (Germany)], E-mail: Ernst.Schmid@lrz.uni-muenchen.de

    2009-10-21

    The aim of this study was to investigate and quantify two biomarkers for radiation exposure (dicentrics and {gamma}-H2AX foci) in human lymphocytes after CT scans in the presence of an iodinated contrast agent. Blood samples from a healthy donor were exposed to CT scans in the absence or presence of iotrolan 300 at iodine concentrations of 5 or 50 mg ml{sup -1} blood. The samples were exposed to 0.025, 0.05, 0.1 and 1 Gy in a tissue equivalent body phantom. Chromosome aberration scoring and automated microscopic analysis of {gamma}-H2AX foci were performed in parts of the same samples. The theoretical physical dose enhancement factor (DEF) was calculated on the basis of the mass energy-absorption coefficients of iodine and blood and the photon energy spectrum of the CT tube. No significant differences in the yields of dicentrics and {gamma}-H2AX foci were observed in the absence or presence of 5 mg iodine ml{sup -1} blood up to 0.1 Gy, whereas at 1 Gy the yields were elevated for both biomarkers. At an iodine concentration of 50 mg ml{sup -1} serving as a positive control, a biological DEF of 9.5 {+-} 1.4 and 2.3 {+-} 0.5 was determined for dicentrics and {gamma}-H2AX foci, respectively. A physical DEF of 1.56 and 6.30 was calculated for 5 and 50 mg iodine ml{sup -1}, respectively. Thus, it can be concluded that in the diagnostic dose range (radiation and contrast dose), no relevant biological dose-enhancing effect could be detected, whereas a clear biological dose-enhancing effect could be found for a contrast dose well outside the diagnostic CT range for the complete radiation dose range with both methods.

  8. Gadolinium-enhanced cardiac MR exams of human subjects are associated with significant increases in the DNA repair marker 53BP1, but not the damage marker γH2AX.

    Directory of Open Access Journals (Sweden)

    Jennifer S McDonald

    Full Text Available Magnetic resonance imaging is considered low risk, yet recent studies have raised a concern of potential damage to DNA in peripheral blood leukocytes. This prospective Institutional Review Board-approved study examined potential double-strand DNA damage by analyzing changes in the DNA damage and repair markers γH2AX and 53BP1 in patients who underwent a 1.5 T gadolinium-enhanced cardiac magnetic resonance (MR exam. Sixty patients were enrolled (median age 55 years, 39 males. Patients with history of malignancy or who were receiving chemotherapy, radiation therapy, or steroids were excluded. MR sequence data were recorded and blood samples obtained immediately before and after MR exposure. An automated immunofluorescence assay quantified γH2AX or 53BP1 foci number in isolated peripheral blood mononuclear cells. Changes in foci number were analyzed using the Wilcoxon signed-rank test. Clinical and MR procedural characteristics were compared between patients who had a >10% increase in γH2AX or 53BP1 foci numbers and patients who did not. The number of γH2AX foci did not significantly change following cardiac MR (median foci per cell pre-MR = 0.11, post-MR = 0.11, p = .90, but the number of 53BP1 foci significantly increased following MR (median foci per cell pre-MR = 0.46, post-MR = 0.54, p = .0140. Clinical and MR characteristics did not differ significantly between patients who had at least a 10% increase in foci per cell and those who did not. We conclude that MR exposure leads to a small (median 25% increase in 53BP1 foci, however the clinical relevance of this increase is unknown and may be attributable to normal variation instead of MR exposure.

  9. 3D-structured illumination microscopy reveals clustered DNA double-strand break formation in widespread γH2AX foci after high LET heavy-ion particle radiation.

    Science.gov (United States)

    Hagiwara, Yoshihiko; Niimi, Atsuko; Isono, Mayu; Yamauchi, Motohiro; Yasuhara, Takaaki; Limsirichaikul, Siripan; Oike, Takahiro; Sato, Hiro; Held, Kathryn D; Nakano, Takashi; Shibata, Atsushi

    2017-12-12

    DNA double-strand breaks (DSBs) induced by ionising radiation are considered the major cause of genotoxic mutations and cell death. While DSBs are dispersed throughout chromatin after X-rays or γ-irradiation, multiple types of DNA damage including DSBs, single-strand breaks and base damage can be generated within 1-2 helical DNA turns, defined as a complex DNA lesion, after high Linear Energy Transfer (LET) particle irradiation. In addition to the formation of complex DNA lesions, recent evidence suggests that multiple DSBs can be closely generated along the tracks of high LET particle irradiation. Herein, by using three dimensional (3D)-structured illumination microscopy, we identified the formation of 3D widespread γH2AX foci after high LET carbon-ion irradiation. The large γH2AX foci in G 2 -phase cells encompassed multiple foci of replication protein A (RPA), a marker of DSBs undergoing resection during homologous recombination. Furthermore, we demonstrated by 3D analysis that the distance between two individual RPA foci within γH2AX foci was approximately 700 nm. Together, our findings suggest that high LET heavy-ion particles induce clustered DSB formation on a scale of approximately 1 μm 3 . These closely localised DSBs are considered to be a risk for the formation of chromosomal rearrangement after heavy-ion irradiation.

  10. DNA Double-Strand Break Analysis by {gamma}-H2AX Foci: A Useful Method for Determining the Overreactors to Radiation-Induced Acute Reactions Among Head-and-Neck Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Goutham, Hassan Venkatesh; Mumbrekar, Kamalesh Dattaram [Division of Radiobiology and Toxicology, Manipal Life Sciences Centre, Manipal University, Manipal, Karnataka (India); Vadhiraja, Bejadi Manjunath [Manipal Hospital, Bangalore, Karnataka (India); Fernandes, Donald Jerard; Sharan, Krishna [Department of Radiotherapy and Oncology, Shiridi Sai Baba Cancer Hospital and Research Centre, Kasturba Hospital, Manipal, Karnataka (India); Kanive Parashiva, Guruprasad; Kapaettu, Satyamoorthy [Division of Biotechnology, Manipal Life Sciences Centre, Manipal University, Manipal, Karnataka (India); Bola Sadashiva, Satish Rao, E-mail: satishraomlsc@gmail.com [Division of Radiobiology and Toxicology, Manipal Life Sciences Centre, Manipal University, Manipal, Karnataka (India)

    2012-12-01

    Purpose: Interindividual variability in normal tissue toxicity during radiation therapy is a limiting factor for successful treatment. Predicting the risk of developing acute reactions before initiation of radiation therapy may have the benefit of opting for altered radiation therapy regimens to achieve minimal adverse effects with improved tumor cure. Methods and Materials: DNA double-strand break (DSB) induction and its repair kinetics in lymphocytes of head-and-neck cancer patients undergoing chemoradiation therapy was analyzed by counting {gamma}-H2AX foci, neutral comet assay, and a modified version of neutral filter elution assay. Acute normal tissue reactions were assessed by Radiation Therapy Oncology Group criteria. Results: The correlation between residual DSBs and the severity of acute reactions demonstrated that residual {gamma}-H2AX foci in head-and-neck cancer patients increased with the severity of oral mucositis and skin reaction. Conclusions: Our results suggest that {gamma}-H2AX analysis may have predictive implications for identifying the overreactors to mucositis and skin reactions among head-and-neck cancer patients prior to initiation of radiation therapy.

  11. Utilisation de l'essai comete et du biomarqueur gamma-H2AX pour detecter les dommages induits a l'ADN cellulaire par le 5-bromodeoxyuridine post-irradiation

    Science.gov (United States)

    La Madeleine, Carole

    Ce memoire est presente a la Faculte de medecine et des sciences de la sante de l'Universite de Sherbrooke en vue de l'obtention du grade de maitre es sciences (M.Sc.) en radiobiologie (2009). Un jury a revise les informations contenues dans ce memoire. Il etait compose de professeurs de la Faculte de medecine et des sciences de la sante soit : Darel Hunting PhD, directeur de recherche (departement de medecine nucleaire et radiobiologie), Leon Sanche PhD, directeur de recherche (departement de medecine nucleaire et radiobiologie), Richard Wagner PhD, membre du programme (departement de medecine nucleaire et radiobiologie) et Guylain Boissonneault PhD, membre exterieur au programme (departement de biochimie). Le 5-bromodeoxyuridine (BrdU), un analogue halogene de la thymidine reconnu depuis les annees 60 comme etant un excellent radiosensibilisateur. L'hypothese la plus repandue au sujet de l'effet radio sensibilisant du BrdU est qu'il augmente le nombre de cassures simple et double brin lorsqu'il est incorpore dans l'ADN de la cellule et expose aux radiations ionisantes. Toutefois, de nouvelles recherches semblent remettre en question les observations precedentes. Ces dernieres etudes ont confirme que le BrdU est un bon radiosensibilisateur, car il augmente les dommages radio-induits dans l'ADN. Mais, c'est en etant incorpore dans une region simple brin que le BrdU radiosensibilise l'ADN. Ces recherches ont egalement revele pour la premiere fois un nouveau type de dommages produits lors de l'irradiation de l'ADN contenant du BrdU : les dimeres interbrins. Le but de ces travaux de recherche est de determiner si la presence de bromodeoxyuridine dans l'ADN augmente l'induction de bris simple et / ou double brin chez les cellules irradiees en utilisant de nouvelles techniques plus sensibles et specifiques que celles utilisees auparavant. Pour ce faire, les essais cometes et la detection des foci H2AX phosphorylee pourraient permettre d'etablir les effets engendres par

  12. Epigenetic-based combinatorial resveratrol and pterostilbene alters DNA damage response by affecting SIRT1 and DNMT enzyme expression, including SIRT1-dependent γ-H2AX and telomerase regulation in triple-negative breast cancer

    International Nuclear Information System (INIS)

    Kala, Rishabh; Shah, Harsh N.; Martin, Samantha L.; Tollefsbol, Trygve O.

    2015-01-01

    Nutrition is believed to be a primary contributor in regulating gene expression by affecting epigenetic pathways such as DNA methylation and histone modification. Resveratrol and pterostilbene are phytoalexins produced by plants as part of their defense system. These two bioactive compounds when used alone have been shown to alter genetic and epigenetic profiles of tumor cells, but the concentrations employed in various studies often far exceed physiologically achievable doses. Triple-negative breast cancer (TNBC) is an often fatal condition that may be prevented or treated through novel dietary-based approaches. HCC1806 and MDA-MB-157 breast cancer cells were used as TNBC cell lines in this study. MCF10A cells were used as control breast epithelial cells to determine the safety of this dietary regimen. CompuSyn software was used to determine the combination index (CI) for drug combinations. Combinatorial resveratrol and pterostilbene administered at close to physiologically relevant doses resulted in synergistic (CI <1) growth inhibition of TNBCs. SIRT1, a type III histone deacetylase (HDAC), was down-regulated in response to this combinatorial treatment. We further explored the effects of this novel combinatorial approach on DNA damage response by monitoring γ-H2AX and telomerase expression. With combination of these two compounds there was a significant decrease in these two proteins which might further resulted in significant growth inhibition, apoptosis and cell cycle arrest in HCC1806 and MDA-MB-157 breast cancer cells, while there was no significant effect on cellular viability, colony forming potential, morphology or apoptosis in control MCF10A breast epithelial cells. SIRT1 knockdown reproduced the effects of combinatorial resveratrol and pterostilbene-induced SIRT1 down-regulation through inhibition of both telomerase activity and γ-H2AX expression in HCC1806 breast cancer cells. As a part of the repair mechanisms and role of SIRT1 in recruiting DNMTs

  13. Differences in quantification of DNA double-strand breaks assessed by 53BP1/γH2AX focus formation assays and the comet assay in mammalian cells treated with irradiation and N-acetyl-L-cysteine

    International Nuclear Information System (INIS)

    Kurashige, Tomomi; Shimamura, Mika; Nagayama, Yuji

    2016-01-01

    The biological effect of ionizing radiation (IR) on genomic DNA is thought to be either direct or indirect; the latter is mediated by IR induction of free radicals and reactive oxygen species (ROS). This study was designed to evaluate the effect of N-acetyl-L-cysteine (NAC), a well-known ROS-scavenging antioxidant, on IR induction of genotoxicity, cytotoxicity and ROS production in mammalian cells, and aimed to clarify the conflicting data in previous publications. Although we clearly demonstrate the beneficial effect of NAC on IR-induced genotoxicity and cytotoxicity (determined using the micronucleus assay and cell viability/clonogenic assays), the data on NAC's effect on DNA double-strand break (DSB) formation were inconsistent in different assays. Specifically, mitigation of IR-induced DSBs by NAC was readily detected by the neutral comet assay, but not by the γH2AX or 53BP1 focus assays. NAC is a glutathione precursor and exerts its effect after conversion to glutathione, and presumably it has its own biological activity. Assuming that the focus assay reflects the biological responses to DSBs (detection and repair), while the comet assay reflects the physical status of genomic DNA, our results indicate that the comet assay could readily detect the antioxidant effect of NAC on DSB formation. However, NAC's biological effect might affect the detection of DSB repair by the focus assays. Our data illustrate that multiple parameters should be carefully used to analyze DNA damage when studying potential candidates for radioprotective compounds

  14. Differences in quantification of DNA double-strand breaks assessed by 53BP1/γH2AX focus formation assays and the comet assay in mammalian cells treated with irradiation and N-acetyl-L-cysteine.

    Science.gov (United States)

    Kurashige, Tomomi; Shimamura, Mika; Nagayama, Yuji

    2016-06-01

    The biological effect of ionizing radiation (IR) on genomic DNA is thought to be either direct or indirect; the latter is mediated by IR induction of free radicals and reactive oxygen species (ROS). This study was designed to evaluate the effect of N-acetyl-L-cysteine (NAC), a well-known ROS-scavenging antioxidant, on IR induction of genotoxicity, cytotoxicity and ROS production in mammalian cells, and aimed to clarify the conflicting data in previous publications. Although we clearly demonstrate the beneficial effect of NAC on IR-induced genotoxicity and cytotoxicity (determined using the micronucleus assay and cell viability/clonogenic assays), the data on NAC's effect on DNA double-strand break (DSB) formation were inconsistent in different assays. Specifically, mitigation of IR-induced DSBs by NAC was readily detected by the neutral comet assay, but not by the γH2AX or 53BP1 focus assays. NAC is a glutathione precursor and exerts its effect after conversion to glutathione, and presumably it has its own biological activity. Assuming that the focus assay reflects the biological responses to DSBs (detection and repair), while the comet assay reflects the physical status of genomic DNA, our results indicate that the comet assay could readily detect the antioxidant effect of NAC on DSB formation. However, NAC's biological effect might affect the detection of DSB repair by the focus assays. Our data illustrate that multiple parameters should be carefully used to analyze DNA damage when studying potential candidates for radioprotective compounds. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  15. The Quiescent Cellular State is Arf/p53-Dependent and Associated with H2AX Downregulation and Genome Stability

    Directory of Open Access Journals (Sweden)

    Mitsuko Masutani

    2012-05-01

    Full Text Available Cancer is a disease associated with genomic instability and mutations. Excluding some tumors with specific chromosomal translocations, most cancers that develop at an advanced age are characterized by either chromosomal or microsatellite instability. However, it is still unclear how genomic instability and mutations are generated during the process of cellular transformation and how the development of genomic instability contributes to cellular transformation. Recent studies of cellular regulation and tetraploidy development have provided insights into the factors triggering cellular transformation and the regulatory mechanisms that protect chromosomes from genomic instability.

  16. Wip1 phosphatase is associated with chromatin and dephosphorylates gammaH2AX to promote checkpoint inhibition

    Czech Academy of Sciences Publication Activity Database

    Macůrek, Libor; Lindqvist, A.; Voets, O.; Kool, J.; Vos, H.R.; Medema, R.H.

    2010-01-01

    Roč. 29, č. 15 (2010), s. 2281-2291 ISSN 0950-9232 R&D Projects: GA ČR GPP305/10/P420 Institutional research plan: CEZ:AV0Z50520514 Keywords : DNA damage * checkpoint * phosphatase Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.414, year: 2010

  17. Radiochemical determination of 210Po

    International Nuclear Information System (INIS)

    Clarence, J.

    1961-04-01

    By spontaneous deposition of Po onto silver, and with the use of Po 208 as a tracer, the accurate spectrographic measurements are made possible. Quantitative recovery of Po 210 from radioactive cellulose filters is obtained by burning of samples in a golden lined calorimetric bomb. (author) [fr

  18. The quiescent and mitogen stimulated peripheral blood mononuclear cells after gamma irradiation and their P53, P21 and H2AX expression

    International Nuclear Information System (INIS)

    Vilasova, Z.; Vavrova, J.; Sinkorova, Z.; Tichy, A.; Oesterreicher, J.; Rezacova, M.; Zoelzer, F.

    2008-01-01

    The aim of this study was to compare reaction of quiescent and proliferating PHA (mitogenic lectin phytohemagglutinin)-stimulated human peripheral blood mononuclear cells (PBMCs) to γ-irradiation and analyze changes of proteins related to repair if DNA damage and apoptosis, such as γH2A.X, p53 and its phosphorylations on serine 15 and 392, and p21. Protein changes induced by radiation are different in quiescent and stimulated PBMCs. W e analyzed changes in proteins related to DNA damage repair and apoptosis using the western blot method in quiescent and stimulated PBMCs. Western blot technique can detect γH2A.X increase only at later times, when the phosphorylation of H2A.X is related to the onset of apoptosis (24-72 h after irradiation by the dose of 4 Gy). The level of H2A.X phosphorylation increased after stimulation of PBMC by PHA (72 h, 10 μg/ml) and as shown here it was detectable by western blot analysis. The increase in γH2A.X that we detected by western blot 4 h after irradiation of stimulated lymphocytes was dose dependent. It can be concluded that measurement of γH2A.X during the first hours after the irradiation is a good marker of the received dose of radiation. We compared the dynamics of p53 induction after irradiation by IR in both quiescent and stimulated lymphocytes. p53 increase was observed only in stimulated lymphocytes, as was p53 phosphorylation at serines-392 and -15. The increase in the amount of p53 was not dose-dependent 4 h after the irradiation. On the other hand, phosphorylation of p53 at serine-15 analyzed 4 h after the irradiation is dose-dependent over the studied dose range. Despite the fact that p53 was not detected in quiescent lymphocytes and a reaction to irradiation was not observed either, p21 levels increased after irradiation in both quiescent and stimulated lymphocytes in a dose-dependent manner. IR induces phosphorylation of p53 at both serines-15 and -392 in PHA stimulated human lymphocytes. However

  19. Distinct kinetics of DNA repair protein accumulation at DNA lesions and cell cycle-dependent formation of gammaH2AX- and NBS1-positive repair foci

    Czech Academy of Sciences Publication Activity Database

    Suchánková, Jana; Kozubek, Stanislav; Legartová, Soňa; Sehnalová, Petra; Kuntzinger, T.; Bártová, Eva

    2015-01-01

    Roč. 107, č. 12 (2015), s. 440-454 ISSN 0248-4900 R&D Projects: GA ČR(CZ) GBP302/12/G157; GA ČR(CZ) GA13-07822S Institutional support: RVO:68081707 Keywords : Cell cycle * DNA repair * Interphase Subject RIV: BO - Biophysics Impact factor: 2.552, year: 2015

  20. Evaluation of low-dose proton beam radiation efficiency in MIA PaCa-2 pancreatic cancer cell line vitality and H2AX formation

    Directory of Open Access Journals (Sweden)

    Aušra Liubavičiūtė

    2015-11-01

    Conclusions: Our data demonstrate that low-doses proton beam irradiation had an effect on MIA PaCa-2 pancreatic carcinoma cell line. Full extent of irradiation had an impact only 24 h postirradiation, triggering DNA arrested cell cycle in G1/0 phase. Formed DNA DSBs were found to be repaired via the NHEJ pathway mechanism within 72 h. Unsuccessful repaired DSBs induced apoptotic cell death. After 72 h reparation processes were completed, and cell cycle was released from arrest in G1/0 phase.

  1. gamma H2AX/53BP1 foci as a potential pre-treatment marker of HNSCC tumors radiosensitivity preliminary methodological study and discussion

    Czech Academy of Sciences Publication Activity Database

    Falk, Martin; Hořáková, Z.; Svobodová, M.; Masařík, M.; Kopečná, Olga; Gumulec, J.; Raudenská, M.; Depeš, Daniel; Bačíková, Alena; Falková, Iva; Binkova, H.

    2017-01-01

    Roč. 71, č. 9 (2017), č. článku 241. ISSN 1434-6079 R&D Projects: GA ČR(CZ) GA16-12454S Institutional support: RVO:68081707 Keywords : squamous-cell carcinoma * cancer -associated fibroblasts Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemistry and molecular biology

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

    Science.gov (United States)

    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. © 2015 Wiley Periodicals, Inc.

  3. Concentration of 210Po in cigars

    International Nuclear Information System (INIS)

    Kelecom, Alphonse; Gouvea, Rita C.S.; Santos, Pedro L.

    2000-01-01

    210 Po concentrations have been determined in 57 different cigar brands manufactured in 11 countries. Cuban and American cigars showed the lowest 210 Po content. The mean levels of 210 Po in Brazilian cigars were almost equal to those of European and Dominican cigars, and somewhat lower than cigars from Central American countries. (author)

  4. LiHo(PO34

    Directory of Open Access Journals (Sweden)

    Mokhtar Férid

    2009-02-01

    Full Text Available Lithium holmium(III polyphosphate(V, LiHo(PO34, belongs to the type I of polyphosphates with general formula ALn(PO34, where A is a monovalent cation and Ln is a trivalent rare earth cation. In the crystal structure, the polyphosphate chains spread along the b-axis direction, with a repeat period of four tetrahedra and 21 internal symmetry. The Li and Ho atoms are both located on twofold rotation axes and are surrounded by four and eight O atoms, leading to a distorted tetrahedral and dodecahedral coordination, respectively. The HoO8 polyhedra are isolated from each other, the closest Ho...Ho distance being 5.570 (1 Å.

  5. Accumulation of 210Po in Baltic invertebrates

    International Nuclear Information System (INIS)

    Skwarzec, B.; Falkowski, L.

    1988-01-01

    This paper presents the results of an investigation of the 210 Po contents of Baltic marine invertebrates. The 210 Po concentrations fall within the range 11.3-78.9 Bq kg -1 (dry wt), the higher values relating to polychaeta, priapulida and malacostraca and the lower levels to bivalvia. It is demonstrated that 210 Po is non-uniformly distributed within the isopod Mesidotea entomon and the bivalve Mya arenaria. The 210 Po contents of the internal organs decreasing in the order-hepatopancreas > alimentary tract > gill > muscle. Moreover, the results indicate the dominant role of the digestive organs of these invertebrates in controlling absorption and elimination of 210 Po. (author)

  6. Systems of Ba(PO3)2-Sr(Pu3)2, Cd(PO3)2-Ca(PO3)2

    International Nuclear Information System (INIS)

    Tokman, I.A.; Bukhalova, G.A.

    1977-01-01

    Phase diagrams of the Ba(PO 3 ) 2 -Sr(PO 3 ) 2 and Cd(PO 3 ) 2 -Ca(PO 3 ) 2 systems have been studied and plotted by the methods of differential-thermal analysis (DTA), visual-polythermal, X-ray phase and infrared spectroscopy. The Ba(PO 3 ) 2 -Sr(PO 3 ) 2 system is of the eutectic type. In the binary system Cd(PO 3 ) 2 -Ca(PO 3 ) 2 the existence of a continuous series of solid solutions with a minimum at 858 deg C and 27.5 mol.% Ca(PO 3 ) 2 has been established

  7. Kinetics of neutralization of Po-218

    International Nuclear Information System (INIS)

    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 + and PoO 2 + 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 + in NO 2 or H 2 O in nitrogen. When PoO 2 + is formed, the electron transfer mechanism dominates the neutralization process. The electron is transferred to PoO 2 + from molecules with lower ionization potentials. The ionization potential of PoO 2 + is also determined to be 10.44 +/- 0.05 eV

  8. The Ca(PO3)2-Sr(PO3)2 system

    International Nuclear Information System (INIS)

    Bukhalova, G.A.; Tokman, I.A.

    1977-01-01

    Phase diagram of the system Ca(PO 3 ) 2 -Sr(PO 3 ) 2 has been studied and plotted with the aid of differential thermal, visual polythermal, X-ray analysis, and infrared spectroscopy. Continuous solid solutions are formed in the system with a minimum at 968 deg C and 25 mol.% of Sr(PO 3 ) 2 . Solid solutions decompose with the formation of about 30 mol.% of Sr(PO 3 ) 2

  9. Complex phosphates in the Li(Na)3PO4-InPO4 systems

    International Nuclear Information System (INIS)

    Potapova, A.M.; Zimina, G.V.; Smirnova, I.N.; Novoselov, A.V.; Spiridonov, F.M.; Stefanovich, S.Yu.

    2008-01-01

    Subsolidus sections in the systems Li 3 PO 4 -InPO 4 (950 deg C) and Na 3 PO 4 -InPO 4 (800, 900, and 1000 deg C) have been studied by X-ray powder diffraction. The compound Li 3 In(PO 4 ) 2 has been synthesized, and the NASICON-type solid solution Li 3(1-x) In 2+x (PO 4 ) 3 (0.67 ≤ x ≤ 0.80) has been found to exist. In the system Na 3 PO 4 -InPO 4 , the solid solution Na 3(1-x) In x/3 PO 4 (0 ≤ x ≤ 0.2) and two complex phosphates exist: Na 3 In(PO 4 ) 2 and Na 3 In 2 (PO 4 ) 3 . These complex phosphates are dimorphic, with the irreversible-transition temperature equal to 675 and 820 deg C, respectively. Na 3 In(PO 4 ) 2 degrades at 920 deg C. Ionic conductivity has been measured in some phases in the system [ru

  10. Determination of 210 Po in cigarettes

    International Nuclear Information System (INIS)

    Peres, Ana Claudia; Hiromoto, Goro

    1999-01-01

    A radiochemical procedure for the determination of 110 Po in cigarettes is presented. The method is based on solvent extraction, followed by spontaneous deposition on copper disks and counting by alpha spectrometry. Some commercial cigarette brands available in the national market were analysed, obtaining 210 Po concentrations ranging from 15 to 26 mBq per gram of dry tobacco. (author)

  11. In-beam spectroscopy of 198Po and 200Po nuclei

    International Nuclear Information System (INIS)

    Maj, A.

    1988-01-01

    The main purpose of this thesis is to answer the question whether any signs of collectivity or deformation are evident in 198 Po and 200 Po nuclei, situated on the border of the predicted new region of oblate deformation. Bearing this in mind spectroscopic investigations were performed. The level schemes of 198 Po and 200 Po were established, transition rates were determined and g-factors of isomeric states and, for 200 Po, the quadrupole moment of the 8 + - state were measured. The experimental techniques are described and the methods of evaluating the obtained data are presented. 74 refs., 7 figs., 9 tabs. (M.F.W.)

  12. Po-210 excretion and radon exposure

    International Nuclear Information System (INIS)

    Breuer, F.; Clemente, G.F.

    1979-01-01

    A mathematical model is given to describe the metabolism of the 210 Po introduced into the systemic compartiments of the human body. The model has been based on the experimental data referred to the 210 Pb- 210 Po intake, excretion and body burden of members of the general italian population. The model fits also very well the experimental data of 210 Pb- 210 Po intake and excretion reported by other authors. The retention function of 210 Po in total body, soft tissue and bone has been evaluated together with the urinary excretion function and the absorbed fraction by ingestion. The model is very valuable to evaluate the lung exposure to Radon decay products on the basis of the 210 Pb- 210 Po urinary excretions

  13. Aberrant PO2 values in proficiency testing.

    Science.gov (United States)

    Fonzi, C E; Clausen, J L; Mahoney, J

    1993-03-01

    We prospectively determined the frequency of aberrant vials of fluorocarbon/buffer used for proficiency testing of measurements of pH, PCO2, and PO2, using 20 duplicate vials from 12 lots of fluorocarbon/buffer and two arterial blood gas analyzers in eight reference laboratories. We defined aberrant vials as vials for which both duplicate measurements differed from the mean value of repeated measurements for the specific instrument (for each lot of testing materials) by > 0.04 for pH, > 10% of the mean or 3.0 mm Hg, whichever was greater, for PCO2; or > 10% of the mean or 6 mm Hg, whichever was greater, for PO2. Four of 1620 vials (0.25%) were aberrant, all based on PO2 measurements (range of mean values: pH, 7.181-7.631; PCO2, 12.7-65.9; PO2, 32.5-150.1) were 0.0055 for pH, 0.67 mm Hg for PCO2, and 1.65 mm Hg for PO2. Deliberate contamination of the fluorocarbon emulsion with room air, as might occur during sampling from the vial, indicated that only minor increases in PO2 (e.g., 1.0 mm Hg at PO2 of 56 mm Hg) occur when samples are aspirated. Larger increases in PO2 (mean 7.1 mm Hg at a PO2 of 66 mm Hg) occurred when the syringe samples were contaminated with room air. We conclude that isolated aberrant measurements of PO2 in blood gas proficiency testing attributable to vial contents can occur, but the frequency is very low.

  14. Metabolism of 210Po in rats: Volatile 210Po from faeces

    International Nuclear Information System (INIS)

    Sadi, B. B.; Li, C.; Wyatt, H.; Bugden, M.; Wilkinson, D.; Kramer, G.

    2011-01-01

    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. (authors)

  15. Superconducting Coil of Po Dipole

    CERN Multimedia

    1983-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.

  16. Aspects on the analysis of 210Po.

    Science.gov (United States)

    Henricsson, F; Ranebo, Y; Holm, E; Roos, P

    2011-05-01

    There has been little development regarding analysis of polonium (Po) in environmental samples since the 1960 ies. This is due to the straightforward spontaneous deposition of this element on silver (Ag), nickel (Ni) or copper (Cu) without any radiochemical separation. For many years, no radiochemical yield determinant was used and it was generally supposed that the yield was 100% after two depositions. Counting was often done using ZnS scintillation counter coupled to a photomultiplier tube. However, the use of the yield determinants (208)Po and (209)Po and the development of alpha spectrometry showed that the yield was lower. Furthermore, the tendency of Po to volatilize at low temperatures constrains the sample preparation techniques; dry-ashing cannot be used. But during the wet-ashing procedure, there are still some losses. The aim of this study was to evaluate the Po losses during wet-ashing by the use of a double-tracer technique. We have found that the losses were about 30% when open glass beakers were used and about 17% when the samples were digested in microwave oven. When long-necked bottles (Kjeldahl flasks) were used, a loss of about 20% was registered. It has also been observed that (210)Pb to some extent is plating out together with its daughter nuclide Po during the electrochemical deposition. This will result in a systematic error since an unknown amount of supported (210)Po will be produced from the (210)Pb decay depending on the fraction of (210)Pb being deposited on the disc and the waiting time between deposition and measurement of the sample. A further consequence of this is that in the assessment of the (210)Pb content in the sample, very often the remaining liquid is stored after deposition for build-up of (210)Po. Since some (210)Pb is lost on the disc, the result for (210)Pb will be too low. Both these systematic errors give rise to a too high (210)Po/(210)Pb ratio. The fraction of (210)Pb which is plating out has been assessed in this

  17. Po2 temperature blood factor for blood gas apparatus.

    Science.gov (United States)

    Teisseire, B P; Hérigault, R A; Teisseire, L J; Laurent, D N

    1984-01-01

    PO2 temperature formulae supplied by manufacturers on automatic blood gas apparatus, PO2 corr. = PO2 37 degrees C X 10F X delta T were studied and compared to the experimental determination of the delta log PO2/delta T ratio (Hérigault et al. [10]). Acid-base status at 37 degrees C appeared to have a measurable influence on the PO2 temperature factor; alkalosis increased the delta log PO2/delta T ratio, and the contrary was found for acidosis in comparison with normal acid-base status at 37 degrees C. For the same PO2, measured at 37 degrees C, all the proposed formulae of commercial blood gas automatic apparatus did not give the same temperature corrected PO2. The observed difference between the corrected PO2 may be important and greater than the precision of the initial measurement. To correct the measured PO2 for temperature, a relationship between delta log PO2/delta T and PO2 is proposed, between PO2 zero and PO2 180 mmHg, which takes into account measured pH and PO2 values at 37 degrees C:delta log PO2/delta T = [(-0.35 pH + 0.658) X 10(-4) X PO2] + 0.035.

  18. Mixed phosphates of the Na3PO4 - LnPO4 systems

    International Nuclear Information System (INIS)

    Slivko, T.A.; Smirnova, I.N.; Zimina, G.V.; Spiridonov, F.M.; Chudinova, N.N.

    2002-01-01

    The phase relationships in the systems Na 3 PO 4 - LnPO 4 (subsolidus 950 Deg C cross-sections), where Ln=Sm, Eu, Tb, Dy, Ho, Tm, Yb, Lu, were studied by X-ray analysis. Reactions of the components were deduced, formed phases were separated and identified. The Na 6 Ln 3 (PO 4 ) 5 (Ln=Dy, Ho, Tm), Na 3 Ln 2 (PO 4 ) 3 (Ln=Tm, Yb, Lu) compounds and phases of the unstable composition Na 6+x Ln 3-x/3 (PO 4 ) 5 (Ln=Yb, Lu, 0 ≤ x ≤ 1.5) were detected for the first time. In all systems the existence of the Na 3-x Ln x/3 PO 4 unstable composition phase on the basis of the high temperature modification of sodium phosphate (sp. gr. Fm3m) is established, suggesting that stabilization of this modification by rare earth ions is possible [ru

  19. El lenguaje poético

    Directory of Open Access Journals (Sweden)

    Alfonso Hanssen

    1966-03-01

    Full Text Available Me parece absurdo pretender hallar la intención poética en cualesquiera rastros de la historia, por el solo hecho de que en ellos se afirma cierta reconditez que los hace misteriosos.

  20. Lifetime measurement in {sup 195}Po

    Energy Technology Data Exchange (ETDEWEB)

    Grahn, T.; Page, R.D. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Dewald, A.; Jolie, J.; Melon, B.; Pissulla, T. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); 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. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, Jyvaeskylae (Finland); Kroell, T.; Kruecken, R.; Maierbeck, P. [TU Muenchen, Physik-Department E12, Garching (Germany)

    2009-03-15

    The lifetime of the 17/2{sup +} yrast state in {sup 195}Po has been measured using the recoil distance Doppler-shift technique to be {tau}=43(11) ps. The lifetime was extracted from the singles {gamma}-ray spectra obtained by using the recoil-decay tagging method. The present work provides more information of the coupling schemes, shapes and configuration mixing in neutron-deficient odd-mass Po nuclei. (orig.)

  1. The onset collectivity in {sup 196}Po

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, L A; Cizewski, J A; Jin, H Q; Henry, R G; Farris, L P [Rutgers--the State Univ., New Brunswick, NJ (United States); Khoo, T L; Carpenter, M P; Janssens, R V.F.; Lauritsen, T [Argonne National Lab., IL (United States); Bearden, I G [Purdue Univ., Lafayette, IN (United States); Ye, D [Notre Dame Univ., IN (United States)

    1992-08-01

    We have studied the in-beam {gamma}-ray spectroscopy of {sup 196}Po, which is the first Po isotope to exhibit collective vibrational structure. The onset of collective motion occurs in this isotope because of the large overlap between valence protons in h{sub 9/2} and valence neutrons in i{sub 13/2} orbitals. (author). 7 refs., 2 tabs., 3 figs.

  2. The determination of 210Po in urine

    International Nuclear Information System (INIS)

    Bale, W.F.; Helmkamp, R.W.; Hrynyszyn, V.; Contreras, M.A.

    1975-01-01

    To measure 210 Po present in normal human urine a technique was developed in which a 4.5 x 11cm silver foil was shaken at room temperature for 48-hr periods in each of two successive volumes of 1.7 l. of urine acidified to 0.5N with HCl. Alpha rays were counted with an ionization chamber, coupled to a vibrating reed electrometer, and capable of measuring α-ray pulses originating on both sides of the silver foil serving as a central electrode. The background α-count was less than 2/hr. Analyses of human urine spiked with 0.29 to 0.58pCi of 210 Po, together with studies of urine from dogs carrying significant body burdens of 210 Pb, indicated that the average recovery of added 210 Po from 1.7 l. volumes of spiked human urine was 72%. If it is assumed that the same percentage of 210 Po is extracted from non-spiked urine, then the average 210 Po concentration found in 13 analyses of 2 x 1.7 l. samples from 26 different pools of fresh human urine was 0.023pCi/l. Substantial additional 210 Po was generated on short aging of the urine through radioactive decay of excreted 210 Bi. (author)

  3. Residual γH2AX foci induced by low dose x-ray radiation in bone marrow mesenchymal stem cells do not cause accelerated senescence in the progeny of irradiated cells.

    Science.gov (United States)

    Pustovalova, Margarita; Astrelina, Тatiana A; Grekhova, Anna; Vorobyeva, Natalia; Tsvetkova, Anastasia; Blokhina, Taisia; Nikitina, Victoria; Suchkova, Yulia; Usupzhanova, Daria; Brunchukov, Vitalyi; Kobzeva, Irina; Karaseva, Тatiana; Ozerov, Ivan V; Samoylov, Aleksandr; Bushmanov, Andrey; Leonov, Sergey; Izumchenko, Evgeny; Zhavoronkov, Alex; Klokov, Dmitry; Osipov, Andreyan N

    2017-11-21

    Mechanisms underlying the effects of low-dose ionizing radiation (IR) exposure (10-100 mGy) remain unknown. Here we present a comparative study of early (less than 24h) and delayed (up to 11 post-irradiation passages) radiation effects caused by low (80 mGy) vs intermediate (1000 mGy) dose X-ray exposure in cultured human bone marrow mesenchymal stem cells (MSCs). We show that γН2АХ foci induced by an intermediate dose returned back to the control value by 24 h post-irradiation. In contrast, low-dose irradiation resulted in residual γН2АХ foci still present at 24 h. Notably, these low dose induced residual γН2АХ foci were not co-localized with рАТМ foci and were observed predominantly in the proliferating Кi67 positive (Кi67+) cells. The number of γН2АХ foci and the fraction of nonproliferating (Кi67-) and senescent (SA-β-gal+) cells measured at passage 11 were increased in cultures exposed to an intermediate dose compared to unirradiated controls. These delayed effects were not seen in the progeny of cells that were irradiated with low-dose X-rays, although such exposure resulted in residual γН2АХ foci in directly irradiated cells. Taken together, our results support the hypothesis that the low-dose IR induced residual γH2AХ foci do not play a role in delayed irradiation consequences, associated with cellular senescence in cultured MSCs.

  4. Sistem Informasi Pada Perusahaan Otobus (Po) Waspada Bengkulu Berbasis Web

    OpenAIRE

    -, Khairil; Koesoemanegara, Eddy

    2011-01-01

    Web Sistem Informasi pada PO. Waspada Bengkulu berguna sebagai pusat informasi dan sarana promosi untuk mempilkan profil Perusahaan dan juga untuk menawarkan produk dan pelayanan yang ditawarkan oleh PO. Waspada. Sistem informasi ini ditujukan agar PO. Waspada lebih dikenal oleh masyarakat dan akhirnya dapat meningkatkan jumlah penumpang yang menggunakan jasa PO. Waspada Bengkulu.Web Sistem Informasi PO. Waspada Bengkulu dikembangkan menggunakan web editor Adobe Dreamweaver dengan web promgra...

  5. PO2 cycling reduces diaphragm fatigue by attenuating ROS formation.

    Science.gov (United States)

    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.

  6. PO2 cycling reduces diaphragm fatigue by attenuating ROS formation.

    Directory of Open Access Journals (Sweden)

    Li Zuo

    Full Text Available 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.

  7. Crystal structure of 4-RbHo(PO3)4, 4-RbTm(PO3)4 and 4-CsEr(PO3)4

    International Nuclear Information System (INIS)

    Maksimova, S.I.; Palkina, K.K.; Chibiskova, N.T.

    1982-01-01

    X-ray structural study of 4-RbLn(PO 3 ) 4 (Ln=Mo, Tm) and 4-CsEr(PO 3 ) 4 is carried out. The compounds are crystallized in monoclinic crystal system, sp. gr P2 1 /n. Parameters of their unit cell, atom coordinates, anisotropic heat parameters, interatomic distances and valent angles are given. 4-RbHo(PO 3 ) 4 , 4-RbTm(PO 3 ) 4 , 4-CsEr(PO 3 ) 4 are isostructural to previously studied TlNd(PO 3 ) and 4-RbNd(PO 3 ) 4 . Using as an example the structural type 4-M 1 Ln(PO 3 ) 4 it is shown that the change of the shortest distances Ln-Ln, M 1 -M 1 and M 1 -Ln, as well as of degree of polymorphous chain corrugation to a higher extent depends on rare earth atom dimensions, than on monovalent metal ion dimensions [ru

  8. α-decay properties of 190Po and the identification of 191Po

    International Nuclear Information System (INIS)

    Batchelder, J.C.; Batchelder, J.C.; Zganjar, E.F.; Toth, K.S.; Bingham, C.R.; Bingham, C.R.; Wauters, J.; Brown, L.T.; Davids, C.N.; Seweryniak, D.; Brown, L.T.; Conticchio, L.F.; Seweryniak, D.; Conticchio, L.F.; Wood, J.L.

    1997-01-01

    The α-decay properties of 190 Po were investigated through the use of a fragment mass analyzer in conjunction with a double-sided Si strip detector. The isotope was produced via the 96 Mo( 96 Mo,2n) reaction, and its α-decay energy and T 1/2 were measured as 7529(10) keV and 2.4 -0.3 +0.4 ms, respectively. The resulting reduced width is nearly identical to that of the 192,194 Po isotopes. This is believed to result from significant mixing between the ground state π(2p) and the low-lying 0 + π(4p-2h) intruder state in the Po parent. The result provides further evidence for shape coexistence in the light Po isotopes. In addition, 191 Po was unambiguously identified, and the 186 Pb α-decay branch was determined experimentally for the first time. copyright 1997 The American Physical Society

  9. Radioactive {sup 210}Po in magnesium supplements

    Energy Technology Data Exchange (ETDEWEB)

    Struminska-Parulska, Dagmara Ida [Gdansk Univ. (Poland). Environmental Chemistry and Radiochemistry Chair

    2016-08-01

    The aim of this pioneer study was to determine polonium {sup 210}Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring {sup 210}Po activity concentrations in magnesium supplements, find the correlations between {sup 210}Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest {sup 210}Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite - 3.84 ± 0.15 mBq g{sup -1} (sample Mg17). The highest annual radiation dose from {sup 210}Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) - 1.35 ± 0.5 and 8.44 ± 0.33 μSv year{sup -1} respectively.

  10. Radioactive 210Po in magnesium supplements

    International Nuclear Information System (INIS)

    Struminska-Parulska, Dagmara Ida

    2016-01-01

    The aim of this pioneer study was to determine polonium 210 Po in the most popular magnesium supplements in Poland and estimate the possible related dose assessment to the consumers. The analyzed magnesium pharmaceutics contained organic or inorganic magnesium compounds; some from natural sources. The objectives of this research were to investigate the naturally occurring 210 Po activity concentrations in magnesium supplements, find the correlations between 210 Po concentration in medicament and magnesium chemical form, and calculate the effective radiation dose connected to analyzed magnesium supplement consumption. The highest 210 Po activity concentrations were determined in mineral tablets made from sedimentary rocks, namely dolomite - 3.84 ± 0.15 mBq g -1 (sample Mg17). The highest annual radiation dose from 210 Po taken with 1 tablet of magnesium supplement per day or with 400 mg of pure Mg daily would come from sample Mg17 (dolomite) - 1.35 ± 0.5 and 8.44 ± 0.33 μSv year -1 respectively.

  11. Una poética del pliegue

    Directory of Open Access Journals (Sweden)

    Ana Porrúa

    2000-11-01

    Full Text Available La producción de Juan Gelman-de Violín y otras cuestiones a Relaciones- puede inscribirse dentro de la poética sesentista caracterizada por la hegemonía de la narración y la apertura del discurso poético al resto de los discursos sociales, pero también establece una compleja relación con las vanguardias históricas. La noción de pliegue permite revisar las articulaciones de este conflicto; como espacio el pliegue separa ambas poéticas, la "coloquialista" y vanguardista, que pueden leerse en el interior del corpus propuesto en estado puro, yuxtapuestas, o bajo la forma del cruce que instala la polémica entre libros o textos de un mismo libro. La idea depliegue como rasgo operatorio permite, por su parte, revisar la relación entre ambas poéticas en el interior de un poema, focalizando la materia, el lenguaje. En este caso la poética vanguardista funciona como cuestionamiento de la linealidad del texto sesentista.

  12. Una poética del pliegue

    Directory of Open Access Journals (Sweden)

    Ana Porrúa

    2001-11-01

    Full Text Available La producción de Juan Gelman-de Violín y otras cuestiones a Relaciones- puede inscribirse dentro de la poética sesentista caracterizada por la hegemonía de la narración y la apertura del discurso poético al resto de los discursos sociales, pero también establece una compleja relación con las vanguardias históricas. La noción de pliegue permite revisar las articulaciones de este conflicto; como espacio el pliegue separa ambas poéticas, la "coloquialista" y vanguardista, que pueden leerse en el interior del corpus propuesto en estado puro, yuxtapuestas, o bajo la forma del cruce que instala la polémica entre libros o textos de un mismo libro. La idea depliegue como rasgo operatorio permite, por su parte, revisar la relación entre ambas poéticas en el interior de un poema, focalizando la materia, el lenguaje. En este caso la poética vanguardista funciona como cuestionamiento de la linealidad del texto sesentista.

  13. On thermal expansion of RbD2PO4, CsH2PO4 and CsDrPO4 crystals

    International Nuclear Information System (INIS)

    Vlokh, O.G.; Shchur, Ya.I.; Klymiv, I.M.

    1994-01-01

    Thermal expansion of RbD 2 PO 4 , CsH 2 PO 4 , CsD 2 PO 4 crystals in a wide range of temperatures embracing points of phase transitions was studied. An explanation of anomalous behaviour of thermal expansion factor along directions b and c in the course of RbD 2 PO 4 transfer into intermediate phase was suggested. 10 refs., 4 figs

  14. RbCuFe(PO42

    Directory of Open Access Journals (Sweden)

    Mongi Ben Amara

    2013-08-01

    Full Text Available A new iron phosphate, rubidium copper(II iron(III bis(phosphate, RbCuFe(PO42, has been synthesized as single crystals by the flux method. This compound is isostructural with KCuFe(PO42 [Badri et al. (2011, J. Solid State Chem. 184, 937–944]. Its structure is built up from Cu2O8 units of edge-sharing CuO5 polyhedra, interconnected by FeO6 octahedra through common corners to form undulating chains that extend infinitely along the [011] and [01-1] directions. The linkage of such chains is ensured by the PO4 tetraedra and the resulting three-dimensional framework forms quasi-elliptic tunnels parallel to the [101] direction in which the Rb+ cations are located.

  15. Electronic Properties of LiFePO4 and Li doped LiFePO4

    International Nuclear Information System (INIS)

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

    2005-01-01

    The potential use of different iron phosphates as cathode materials in lithium-ion batteries has recently been investigated.1 One of the promising candidates is LiFePO4. This compound has several advantages in comparison to the state-of-the-art cathode material in commercial rechargeable lithium batteries. Firstly, it has a high theoretical capacity (170 mAh/g). Secondly, it occurs as mineral triphylite in nature and is inexpensive, thermally stable, non-toxic and non-hygroscopic. However, its low electronic conductivity (∼10-9 S/cm) results in low power capability. There has been intense worldwide research activity to find methods to increase the electronic conductivity of LiFePO4, including supervalent ion doping,2 introducing non-carbonaceous network conduction3 and carbon coating, and the optimization of the carbon coating on LiFePO4 particle surfaces.4 Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL has yield electronic conductivity increase up to 106.5 We studied electronic structure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-ray emission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes the unoccupied partial density of states, while XES the occupied partial density of states. By combining XAS and XES measurements, we obtained information on band gap and orbital character of both LiFePO4 and Li doped LiFePO4. The occupied and unoccupied oxygen partial density of states (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented in Fig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (∼ 4 eV). This value is much larger than what is predicted by DFT calculation. For 5 percent Li doped LiFePO4, a new doping state was created closer to the Fermi level, imparting p-type conductivity, consistent with thermopower measurement. Such observation substantiates the suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 is due to available number of charge carriers in the material

  16. Radiocesium in wheat of the Po plain

    International Nuclear Information System (INIS)

    Dominici, G.; Malvicini, A.

    1988-01-01

    The Cs-137 measurements of many wheat samples, which was cultivated in Po plain during 1986 and 1987, are reported. A relationship is also shown between the quantity of Cs-137, which is contained in total fall-out, and that in the wheat by direct deposition

  17. doped LiMgPO4 phosphor

    Indian Academy of Sciences (India)

    attention because of their remarkable luminescence proper- ties and .... Figure 1. (a) X-ray diffraction patterns of LiMgPO4:Tb3+ phosphor and (b) standard data. ICDD file. .... ground signal which affects the signal to noise ratio [17]. MDD was ...

  18. The system La(PO3)3-Ca(PO3)2-P2O5

    International Nuclear Information System (INIS)

    Jungowska, W.; Znamierowska, T.

    1993-01-01

    Ternary system La(PO 3 ) 3 -Ca(PO 3 ) 2 -P 2 O 5 has been studied by means of thermal and roentgenography analysis. The existence of single intermediate compound CaLa(PO 3 ) 5 has been observed. The phase diagrams for the ternary system as well as for two binary systems La(PO 3 ) 3 -Ca(PO 3 ) 2 and CaLa(PO 3 ) 5 -LaP 5 O 11 have been shown. 7 refs, 3 figs

  19. Le corps poétique ou la poétique du corps

    Directory of Open Access Journals (Sweden)

    Yvonne Goga

    2007-05-01

    Full Text Available Les réflexions sur la poésie de Valéry sont illustrées dans deux volumes : Album de vers anciens et Charmes. Parmi les images les plus représentatives est celle du corps de la femme. Par l’analyse des images sur le corps de la femme, le but de notre étude est celui de souligner l’un des principes de la poétique de Valéry : la relation entre le monde extérieur, le corps et l’esprit, pour créer le poème et le poète.

  20. Luminescent properties of LuPO4-Pr and LuPO4-Eu nanoparticles

    International Nuclear Information System (INIS)

    Vistovskyy, V.; Malyi, T.; Vas’kiv, A.; Chylii, M.; Mitina, N.; Zaichenko, A.; Gektin, A.; Voloshinovskii, A.

    2016-01-01

    Spectral-luminescence parameters of LuPO 4 -Eu and LuPO 4 -Pr nanoparticles of different sizes are studied upon excitation by the synchrotron radiation with photon energies 4–40 eV. Influence of the nanoparticle size on Eu 3+ and Pr 3+ impurity luminescence is analyzed for intracenter and recombination excitation. It is shown that the luminescence intensity of impurities in the case of recombination excitation significantly stronger decreases with decreasing of nanoparticle size compared to intracenter excitation. This feature is explained by the influence of thermalization length to nanoparticle size ratio on the recombination luminescence. Electron recombination luminescence inherent for LuPO 4 -Eu nanoparticles shows a weaker dependence on the nanoparticle size than the hole one in LuPO 4 -Pr nanoparticles. The difference between energy states of praseodymium impurity ions in nanoparticles of different sizes is revealed.

  1. Separation and electrodeposited of 210 Po

    International Nuclear Information System (INIS)

    Ordonez R, E.; Iturbe G, J.L.

    1991-12-01

    Presently work it was determined the selective separation of the 210 Po that is in an uraniferous mineral, by means of acid leaching of the mineral and the purification was carried out by means of partition chromatography whose stationary phase is 2-ethylhexyl phosphoric acid (D 2 EHPA), it has been possible to isolate the 210 Po of the rest of the radioactive elements that conform the family 4 N +2 , the optimal elutriation conditions of this element were settled down of manner of not dragging other radioelements. Another of the achievements presented in this communication has been the electrodeposition of this element has more than enough stainless steel discs with a superior yield to 95%. (Author)

  2. Measurement of 210Po in vegetables of Gudalore

    International Nuclear Information System (INIS)

    Selvasekarapandian, S.; Sivakumar, R.; Mugunthamanikandan, N.; Ragunath, V.M.; Meenashisundaram, V.

    1999-01-01

    Intake of 210 Po with food was determined for the population in Gudalore taluka of Nilgiri district. The content of 210 Po in different vegetable samples was determined. The annual intake of 210 Po due different vegetables was estimated on the basis of their average annual consumption. The intake of 210 Po varied from 0.056 to 11.97 Bq/kg. The largest intake of 210 Po was with tapioca. From the intake annual effective dose was calculated. Effective dose equivalent due to polonium in different vegetables varied between 0.0121 to 2.872 μSv/Y. (author)

  3. PoET: Polarimeters for Energetic Transients

    Science.gov (United States)

    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.

  4. Radiochemical determination of 210 Po in tobacco and farm food

    International Nuclear Information System (INIS)

    Chung, K. H.; Lee, H. P.; Cho, Y. H.; Choi, G. S.; Kim, C. K.; Lee, C. W.

    2002-01-01

    A method for measuring 210 Po in tobacco (cigarette and leaf) and farm food has been studied by alpha- spectrometry. Polonium was separated from HCl solution in the presence of other radionuclides and ascorbic acid (reduction of Fe 3+ ) by spontaneous deposition onto a silver disc. To determine the optimum conditions for plating polonium on a disc, the effects of reducing agent, plating time etc. were investigated. In the method, the samples are spiked with 208 Po (or 209 Po) as a chemical yield tracer. Because the main sources of 210 Po in the human body are food and cigarette smoke, this procedure to determine 210 Po has been applied to tobacco and farm food samples. Analyses of 210 Po in tobacco leaves and farm food samples using this method are in progress. The concentrations of 210 Po in cigarettes were ranged from 17 to 21 mBq/g and compared with published data on this natural radionuclide

  5. Forenzika elektronske pošte

    Directory of Open Access Journals (Sweden)

    Milorad S. Markagić

    2013-10-01

    Full Text Available U najopštijem smislu digitalna forenzika može se definisati kao skup metoda za prikupljanje, analizu i prezentaciju digitalnih dokaza koji se mogu pronaći na računarima, serverima, u računarskim mrežama, bazama podataka, mobilnim uređajima i svim drugim elektronskim uređajima na kojima se čuvaju podaci. U ovom radu su opisane metode prikupljanja digitalnih dokaza u elektronskoj pošti i njihova analiza. Uvod Elektronska pošta se kao dokazni materijal pojavljuje u velikom broju kako građanskih tako i kriminalnih forenzičkih istraga. Elektronska pošta i elektronska pošta zasnovana na internet serverima  širi se veoma brzo, pa lako i brzo završi i na računaru korisnika kome nije namenjena. Prvu elektronsku poruku poslao je Ray Tomilson 1971. godine, a deset godina kasnije u kombinaciji sa personalnim računarima i internetom prerasta u globalni način komuniciranja i personalnog i poslovnog. Takođe se koristi i u svrhu zabave, načina razmene podataka, ali predstavlja i nezamenjiv izvor digitalnih dokaza, kada dodje do računarskog incidenta. Analiza elektronske pošte Svaka elektronska poruka sastoji se od dva dela: zaglavlja i teksta poruke. Iz zaglavlja je moguće saznati izvorišnu i odredišnu adresu, pošiljaoca i namenjenog primaoca, a telo poruke sadrži tekst poruke. Ekstenzije dokumenata elektronske pošte U slučajevima kada je potrebno otkriti samo dokumente potrebne za pregled elektronskih poruka, ili kopirati pojedinačni dokument sačuvan unutar elektronske pošte, moguće je koristiti sistem na istraživanom računaru ili specijalizovani softver kao što je Outlook Extract Pro ili Outlook Export. Mnogo ispravniji, sigurniji i jednostavniji način je korišćenje forenzičkih alata kao što su EnCase ili FTK, sa ugrađenim pregledačima koji omogućavaju pregled i snimanje sadržaja baze podataka kao i njihovo kopiranje na druge medije za dalju analizu. Forenzički alati automatizuju proces skidanja i kopiranja

  6. Half-life of 214Po and 212Po measured with CTF at LNGS

    International Nuclear Information System (INIS)

    Bellini, G.; Benziger, J.; Bick, D.

    2013-01-01

    Polonium isotopes 214 Po and 212 Po are part of the 238 U and 232 Th decay chains, respectively. There exist only a few measurements of these two mean lifetimes with precision better than one or two percent. Since we have been studying decay spectra of 214 Bi and 212 Bi with the purpose of experimentally constraining anti-neutrino spectral shape important for geoneutrino studies, we have a large statistics of decays of 214 Po and 212 Po collected with the Counting Test Facility (CTF), which was operational in the underground I.N.F.N. Gran Sasso National Laboratory. The apparatus consisted of an external cylindrical water tank (diameter ∼ 11 m, high ∼ 10 m; ∼ 1000 tons of water) serving as passive shielding for 4.8 m 3 of liquid organic scintillator contained in an inner spherical vessel with a diameter of ∼ 2 m. The inner vessel was realized with a nylon membrane (∼ 500 ?m thick), with excellent optical clarity, which allowed the effective transmission of the scintillation light to the 100 phototubes (PMTs) forming the optical read-out, anchored on a 7 m diameter support structure inside the water tank. The high purity and low background in CTF allows a favourable signal to background ratio for these measurements. More specifically the ratio of signal to background of the present measurements is more than three orders of magnitude larger than the best existing measurements. We have studied the decays of 214 Po into 210 Pb and of 212 Po into 208 Pb tagged by the coincidence with the previously decays from 214 Bi and 212 Bi by using 222 Rn, 232 Th and 220 Rn sources sealed inside quartz vials and inserted in the CTF

  7. Temporal changes of 210Po in temperate coastal waters

    International Nuclear Information System (INIS)

    Wildgust, M.A.; White, K.N.; McDonald, P.

    1998-01-01

    The temporal variation of Polonium-210 ( 210 Po) was examined in coastal sea water, the mussel Mytilus edulis, the winkle Littorina littorea and green algae Ulva lactuca in order to investigate the entry of 210 Po into the marine food chain. More than 99% of 210 Po in the water column occurred in the particulate phase. Dissolved 210 Po concentrations peaked during the spring phytoplankton bloom and it is suggested this is related to preferential scavenging of 210 Po by the increased numbers of bacteria, viruses and small dissolved particulates. Changes in L. Littorea 210 Po specific activity are thought not to be related to food, but to a drop in body weight following spawning. Much of the 210 Po accumulated by M. edulis was located in the digestive gland. The specific activity of 210 Po in the digestive gland of M. edulis was shown to be strongly correlated with changes in sea water suspended particulate specific activity. Examination of other trace metal (Ag, Al, As, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni Sb, Se, Sn and Zn) variations in the digestive gland revealed that class B and borderline metals had a strong positive correlation with 210 Po. On-going work is investigating whether the accumulation and loss of 210 Po is affected by the presence of metallothioneins

  8. Temporal changes of 210Po in temperate coastal waters.

    Science.gov (United States)

    Wildgust, M A; McDonald, P; White, K N

    1998-06-18

    The temporal variation of Polonium-210 (210Po) was examined in coastal sea water, the mussel Mytilus edulis, the winkle Littorina littorea and green alga Ulva lactuca in order to investigate the entry of 210Po into the marine food chain. More than 99% of 210Po in the water column occurred in the particulate phase. Dissolved 210Po concentrations peaked during the spring phytoplankton bloom and it is suggested this is related to preferential scavenging of 210Po by the increased numbers of bacteria, viruses and small dissolved particulates. Changes in L. littorea 210Po specific activity are thought not to be related to food, but to a drop in body weight following spawning. Much of the 210Po accumulated by M. edulis was located in the digestive gland. The specific activity of 210Po in the digestive gland of M. edulis was shown to be strongly correlated with changes in sea water suspended particulate specific activity. Examination of other trace metal (Ag, Al, As, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Sb, Se, Sn and Zn) variations in the digestive gland revealed that class B and borderline metals had a strong positive correlation with 210Po. On-going work is investigating whether the accumulation and loss of 210Po is affected by the presence of metallothioneins.

  9. poCAMon personal online continuous airmonitor

    International Nuclear Information System (INIS)

    Streil, T.; Oeser, V.

    2015-01-01

    The poCAMon combines a very compact design with a high flow rate and long battery life. Its size and weight are still acceptable for carrying by one person. The unit measures long-lived aerosols as well as short-lived Radon/Thoron daughters by alpha spectroscopy and beta counting. The radioactive aerosols and particles are collected on the surface of a high resolution membrane filter. The alpha and beta decays on the filter are measured by a high-end semiconductor radiation detector (400 mm@). This allows a perfect separation of the different decay products. The increased pump rate (more than 3 l/ min) is suitable for lower detection limits. A sensor measures permanently the pressure drop on the filter in order to recognize an exhausted or perforated filter instantly. With the 3.8 Ah NiMH battery pack the poCAMon achieves an operation time of more than 30 hours. The quality control is a main issue of any radiation measurement. Therefore the poCAMon records a complete alpha spectrum for each measured value. This allows the monitoring of the device's perfect operation in each moment of the measurement. There are options for additional sensors for carbon monoxide and combustible gases as needed in underground mines. All measured data are stored in a 2GB memory card and can be accessed with a PC or laptop via a USB interface. Data transmission and device control can also be done via wireless ZigBee network or via a server for stationary operation with network access. A barometric pressure sensor and a GPS receiver are optional features of the device.

  10. Optimizacija razvoza po lastnih prodajalnah izbranega podjetja

    OpenAIRE

    Bagari, Jasmina

    2015-01-01

    V diplomskem delu obravnavamo problematiko optimizacije razvoza pekovskih izdelkov v lastne prodajalne. Reševanja problematike smo se lotili s pomočjo sledilnega sistema Trak 8. Najprej smo naredili posnetek stanja in nato analizirali pridobljene podatke. Prišli smo do zaključka, da lahko proge razvoza bolj racionalno in točno načrtujemo. S tem odpravimo podvojene kilometre, prazne kilometre in zmanjšamo stroške razvoza. Po prestrukturiranju vseh prog smo prišli do spoznanja, da lahko lastne ...

  11. Leaching of 210Po in human saliva from smokeless tobacco

    International Nuclear Information System (INIS)

    Syed, U.F.; Bari, A.; Husain, L.; Husain, L.

    2009-01-01

    Use of smokeless tobacco (SLT) is associated with cancer of the oral cavity. 210 Po, a known carcinogen present in SLT may leach into the saliva when the snuff is held in the mouth. Alpha emission from leached 210 Po can cause oral tissue damage, especially in the presence of non healing ulcers seen frequently in snuff users' mouth. Leaching of 210 Po from SLT in human saliva was determined for six popular US snuff brands. 210 Po was leached into human saliva for 30 min, separated radiochemically and its activity was determined by α-counting. Approximately 2-10% of 210 Po present in SLT was observed to leach. Annual exposure from leached 210 Po, based on average daily consumption of 15 g of SLT, was calculated to range from 1.1 to 3.8 Bq year -1 . (author)

  12. Vibrational modes of deuterium in KD2PO4

    International Nuclear Information System (INIS)

    Mizoguchi, Kohji; Agui, Akane; Tominaga, Yasunori; Nakai, Yusuke; Ikeda, Susumu.

    1993-01-01

    In order to study the deuteration effect in hydrogen-bonded compounds such as KH 2 PO 4 , hydrogen and deuterium modes in KH 2 PO 4 and K(D x H 1-x ) 2 PO 4 (x = 95 %) were investigated by means of inelastic neutron-scattering measurements over a wide energy range. By comparing Raman spectra of KH 2 PO 4 and KD 2 PO 4 with neutron-scattering spectra, the vibrational modes of deuterium and those of PO 4 tetrahedrons in the energy range of 30 < ε < 150 meV have been investigated. At least two deuterium modes have been found at 87 meV and 106 meV. (author)

  13. PO2 Cycling Reduces Diaphragm Fatigue by Attenuating ROS Formation

    OpenAIRE

    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 monito...

  14. Levels of 210 Pb and 210 Po in Brazilian cigarettes

    International Nuclear Information System (INIS)

    Santos, Pedro Lopes dos; Kelecom, Alphonse; Gouvea, Rita de Cassia dos Santos; Dutra, Iedo Ramos

    1996-01-01

    210 Po and 210 Pb concentrations have been determined in 18 Brazilian cigarette samples and compared with known data on U content. U is respectively 3-fold less and 4-fold less abundant than 210 Po or 210 Pb. No correlation could be observed between U concentration and those of Po or Pb. The mean concentration of 210 Pb is higher than that of 210 Pb observed in many other plants, even in plants frown in high background areas. (author)

  15. Assessment of 210Po in foodstuffs consumed in Korea

    International Nuclear Information System (INIS)

    Chang Woo Lee; Mun Ja Kang; Wanno Lee; Geun Sik Choi; Young Hyun Cho; Hee Reyoung Kim; Kun Ho Chung

    2009-01-01

    210 Po in the daily diet in Korea was analyzed and the ingestion dose from an intake of 210 Po was estimated by considering the dietary habit of a Korean person. The 210 Po concentrations of a leafy vegetable (0.36 Bq x kg -1 for lettuce) in the terrestrial food were higher than those of grain, whereas Chinese cabbage had a lesser 210 Po concentration (0.019 Bq x kg -1 ). The 210 Po concentration of the animal product was similar to those detected in the grain and vegetable. The 210 Po concentrations in the shell and crustaceous were high from 19.1 to 33.0 Bq x kg -1 , however, its value fell in the overall range of the reported values. The effective dose from 210 Po for an adult from the Korean population was about 269.4 μSv x y -1 . Nearly 80% of the ingestion dose from the intake of 210 Po was attributed to the consumption of seafood. It suggests that the marine food ingestion is a critical pathway for natural 210 Po to the Korean population. (author)

  16. Crystal structure of polyphosphates NaCd(PO3)3 and NaMn(PO3)3

    International Nuclear Information System (INIS)

    Murashova, E.V.; Chudinova, N.N.

    1997-01-01

    Crystal structure of NaCd(PO 3 ) 3 (1) and NaMn(PO 3 ) 3 (2) isostructural polyphosphates was determined for twin samples. Rhombic lattice parameters of (1): a = 14.678, b = 14.669, c = 14.705 A, sp. gr. P2 1 2 1 2 1 , Z = 16. The structure of compounds is of frame type. Polyphosphate chain with repetition period of 24 PO 4 tetrahedrons contacts with NaO 6 and M 2 O 6 octahedrons by means of common oxygen vertices. Similarities and differences in structure of mentioned polyphosphates and earlier analyzed NaMg(PO 3 ) 3 polyphosphate are noted [ru

  17. Effect of excitation energy and angular momentum on the characteristics of 208Po and 210Po compound nucleus fission fragments

    International Nuclear Information System (INIS)

    Itkis, M.G.; Kalpakchieva, R.; Okolovich, V.N.; Penionzhkevich, Yu.Eh.; Tolstikov, V.N.

    1982-01-01

    To study characteristics of fissioning nucleus fragments, investigated were reactiiiiiiiiiiiiiiiH8Pt+ 12 C → 210 Po in the 12 C ion energy range of 86-110.5 MeV, of 192 Os+ 16 O → 208 Po in 90-131 MeV range, 204 Pb+ 3 He → 207 Po, 206 Pb+ 3 He → 209 Po, 207 Pb+ 3 He → 210 Po with 60 MeV 3 He ion energy. Using a correlation technique for measuring energies of two fragments mass and energy distributions of fission fragments of 208 Po and 210 Po compound nuclei produced in the reactions have been studied. Mass and energy distributions of fragments from fission of 208 Po and 210 Po in the reactions with ions 16 O, 12 C and 3 He were investigated in an ample energy range, using the correlational techniques for measurement of energies of two fragments. An increase in the total kinetic energy with rise of the angular momentum was observed, the fact indicating a weak coupling of one-particle and collective modes of motion in the fissile nucleus resulting in that the rolational energy is transfered mainly to translation energies of the fragments

  18. Neutralization of Na2PO4: Reaction between Na3PO4 and CaCL2

    International Nuclear Information System (INIS)

    Xia Shenglan; Wang Luning

    1990-01-01

    The results of reaction Na 3 PO 4 with CaCl 2 in water at ambient and higher temperature are described. The reaction rate of Na 3 PO 4 with CaCl 2 is slow at ambient temperature and the reaction is complete at 260 deg C after 2 h. The products are Ca(OH) 2 and Ca 5 (PO 4 ) 3 (OH). The quantity of them is dependent upon the quanity of Na 3 PO 4 and CaCl 2 contained in water, all of them control pH of water

  19. pO2 measurements in arteriolar networks.

    Science.gov (United States)

    Torres Filho, I P; Kerger, H; Intaglietta, M

    1996-03-01

    Previous studies from our laboratory have shown that the average arteriolar pO2 in the hamster skinfold preparation is lower than arterial systemic pO2. In the present work we tested the hypothesis that there is a longitudinal gradient of pO2 along precapillary vessels. Experiments were performed in Syrian golden hamsters bearing a dorsal skin chamber. The oxygen-dependent quenching of phosphorescence of palladium-porphyrin complexes was used to measure intravascular pO2 in the microcirculation. Arterioles were classified in four orders according to their position in the network, first-order vessels being the entrance points. Simultaneous determinations of diameter (D), red blood cell velocity, and systemic blood gases were also made. There was a significant fall of pO2 between vessels of different orders. First-order arterioles (mean D = 64 microns) had pO2 of 51.8 +/- 9.8 mm Hg (mean +/- SD) which was equivalent to approximately equal to 73% of the arterial systemic pO2. Within the arteriolar network, further decreases of intravascular pO2 were measured, leading to a pO2 of 34.0 +/- 7.9 mm Hg in terminal arterioles (mean D = 7.7 microns). In some vessels pO2 was measured in different positions of the same arteriole. The average longitudinal arteriolar oxygen saturation gradient was 3.4 +/- 0.4 delta %/mm (range 0.8-7.2). A significant and positive correlation was found between pO2 and microhemodynamic parameters when arterioles were grouped according to their order. This relation was not significant for venules which showed a mean pO2 of 30.8 +/- 10.8 mm Hg. Tissue pO2 averaged 24.6 +/- 5.8 mm Hg. We conclude that: (1) There is an oxygen loss in arterial vessels larger than 100 micrograms in diameter, (2) arteriolar pO2 in this preparation depends on the position of the vessel within the network, (3) a substantial portion of oxygen delivery to the hamster skin is provided by the arteriolar network, and (4) only a small pO2 gradient exists between terminal

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

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Ahmad, I.; Crowell, B. [and others

    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.

  1. Effect of Phosphate Salts (Na3PO4, Na2HPO4, and NaH2PO4) on Ag3PO4 Morphology for Photocatalytic Dye Degradation under Visible Light and Toxicity of the Degraded Dye Products

    NARCIS (Netherlands)

    Amornpitoksuk, P; Intarasuwan, K; Suwanboon, S; Baltrusaitis, Jonas

    2013-01-01

    Ag3PO4 was synthesized by the precipitation method using three different types of phosphate salts (Na3PO4, Na2HPO4, and NaH2PO4) as a precipitating agent. Hydrolysis of each phosphate salt gave a specific pH that affected the purity and morphology of the prepared Ag3PO4. The Ag3PO4 prepared from

  2. Volatilization of Po by microorganisms at laboratory culture experiments

    International Nuclear Information System (INIS)

    Momoshima, N.; Ishida, A.; Yoshinaga, C.; Fukuda, A.

    2005-01-01

    The previous experiments proved the volatility of polonium form culture medium in which microorganisms were propagated from seed of seawater, river water or pond water, therefore we did not know what kind of species are responsible to Po volatility. To search microorganisms, which concerned with Po emission we carried out culture experiments using known microorganisms. Three microorganisms were examined; Escherichia coli K-12, Bacillus subtilis and Chromobacterium violaceum. The microorganisms were pre-cultured in LB medium at 30 degree C and a small portion of the pre-cultured was transferred to a culture bottle in which LB medium and 208 Po tracer were contained. The culture was done at 30 degree C with shaking the culture bottle and air passed through a filter was introduced. The Po volatilized was transferred into the trap vials in which scintillator for liquid scintillation counting (LSC) was contained. The Po activity was measured by LSC. All of the microorganisms examined volatilized Po but their ability was quite different each other. Highest ability was observed on Chromobacterium violaceum and then Escherichia coli K-12 followed by Bacillus subtilis, the relative magnitude of the ability was 10 2 , 10, 1, respectively. Chromobacterium violaceum and Escherichia coli K-12 showed high volatility for the first 24 h but Escherichia coli K-12 showed a decrease thereafter. However high volatility was continued on Chromobacterium violaceum during the culture. The low culture temperature suppressed Po volatility, supporting biologically mediated Po emission from the culture.

  3. Separation and electrodeposited of {sup 210} Po; Separacion y electrodeposito de {sup 210} Po

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E.; Iturbe G, J.L

    1991-12-15

    Presently work it was determined the selective separation of the {sup 210} Po that is in an uraniferous mineral, by means of acid leaching of the mineral and the purification was carried out by means of partition chromatography whose stationary phase is 2-ethylhexyl phosphoric acid (D{sub 2}EHPA), it has been possible to isolate the {sup 210} Po of the rest of the radioactive elements that conform the family 4 N{sup +2}, the optimal elutriation conditions of this element were settled down of manner of not dragging other radioelements. Another of the achievements presented in this communication has been the electrodeposition of this element has more than enough stainless steel discs with a superior yield to 95%. (Author)

  4. Synthesis and crystal structure of hydrogen phosphites RbH2PO3, CsH2PO3, and TlH2PO3

    International Nuclear Information System (INIS)

    Kosterina, E.V.; Troyanov, S.I.; Kemnits, Eh.; Aslanov, L.A.

    2001-01-01

    The crystal acid phosphites RbH 2 PO 3 , CsH 2 PO 3 and TlH 2 PO 3 were separated during reaction of Rb, Cs and Tl carbonates with phosphorous acid solution. The crystal structure of the compounds was analyzed by X-ray diffraction method at 150 K. CsH 2 PO 3 has a monoclinic system, a = 7.930(2), b = 8.929(2), c = 13.163(3) A, β = 104.84(3) Deg, V = 900.9(4) A 3 , Z 8, sp. gr. P2 1 /c, R 1 = 0.239. In the structure hydrogen bonds integrate the PHO 3 tetrahedrons in the unlimited zigzag chains [HPHO 3 ] n n- laying at the layers, which are alternate to the layers of metal cations. The layers of anion chains have a wavy form [ru

  5. Levels of 210Po and 210Pb in cigars

    International Nuclear Information System (INIS)

    Kelecom, A.; Gouvea, R.C.S.; Santos, P.L.

    2002-01-01

    210 Po and 210 Pb concentrations have been determined in 58 cigar brands manufactured in 11 countries. Cuban and American cigars showed the lowest 210 Po content. The mean levels of 210 Po in Brazilian, European and Dominican cigars were almost identical and somewhat lower than the levels observed for cigars from other Latin American countries. Cuban, American and European cigars contained low levels of 210 Pb. Cigars from the remaining countries contained twice as much 210 Pb. The mean 210 Po/ 210 Pb ratio showed an excess of polonium. In the case of one cigar-a-day smoker, the calculated annual absorbed dose due to 210 Po is ∼16 μGy. (author)

  6. Inelastic neutron scattering and lattice dynamics studies of AlPO4 and GaPO4

    International Nuclear Information System (INIS)

    Mittal, R.; Chaplot, S.L.; Kolesnikov, A.I.; Loong, C.-K.; Jayakumar, O.D.; Kulshreshtha, S.K.

    2006-01-01

    The compounds AlPO 4 and GaPO 4 show phase transitions at high pressure depending on the compressibility of the constituent tetrahedra. Semi-empirical interatomic potentials are available for AlPO 4 and GaPO 4 . Molecular dynamics simulations have been reported using these potentials to understand the nature of phase transitions in different polymorphs of these compounds. In order to check these potentials we have carried out lattice dynamical studies for AlPO 4 and GaPO 4 . The phonon density of states measurements from the polycrystalline samples of low-cristobalite phase of AlPO 4 and GaPO 4 are carried out using High-Resolution Medium-Energy Chopper Spectrometer at ANL in the energy transfer range 0-160 meV. The calculated phonon spectra for both the compounds using the available potentials show fair agreement with the experimental data. However, the agreement between the two is improved by including the polarizibility of the oxygen atoms in the framework of the shell model. The lattice dynamical model is used for the calculation of specific heat and thermal expansion

  7. Specific absorption spectra of hemoglobin at different PO2 levels: potential noninvasive method to detect PO2 in tissues.

    Science.gov (United States)

    Liu, Peipei; Zhu, Zhirong; Zeng, Changchun; Nie, Guang

    2012-12-01

    Hemoglobin (Hb), as one of main components of blood, has a unique quaternary structure. Its release of oxygen is controlled by oxygen partial pressure (PO2). We investigate the specific spectroscopic changes in Hb under different PO2 levels to optimize clinical methods of measuring tissue PO2. The transmissivity of Hb under different PO2 levels is measured with a UV/Vis fiber optic spectrometer. Its plotted absorption spectral curve shows two high absorption peaks at 540 and 576 nm and an absorption valley at 560 nm when PO2 is higher than 100 mm Hg. The two high absorption peaks decrease gradually with a decrease in PO2, whereas the absorption valley at 560 nm increases. When PO2 decreases to approximately 0 mm Hg, the two high absorption peaks disappear completely, while the absorption valley has a hypochromic shift (8 to 10 nm) and forms a specific high absorption peak at approximately 550 nm. The same phenomena can be observed in visible reflectance spectra of finger-tip microcirculation. Specific changes in extinction coefficient and absorption spectra of Hb occur along with variations in PO2, which could be used to explain pathological changes caused by tissue hypoxia and for early detection of oxygen deficiency diseases in clinical monitoring.

  8. 210Pb and 210Po in tobacco - with a special focus on estimating the doses of 210Po to man

    International Nuclear Information System (INIS)

    Takizawa, Y.; Zhang, L.; Zhao, L.

    1994-01-01

    Inhalation of tobacco smoke is ranked second to food as a source of 210 Pb and 210 Po exposure to man. assay of 210 Pb and 210 Po in commercially available tobacco collected from many countries have been carried out to assess the potential risk from 210 Po present in tobacco. The range of 210 Po contained in the tobacco grands varied from 10.08 to 15.0 mBq/tob or 13.0 to 20.1 mBq/g and the mean was 11.6 mBq/tob or 15.4 mBq/g. During the International Standard Smoking process about 50% of 210 Po present in tobaccos was transferred into the smoke and the other 50% remained in the ash and butt. About 10% of the total 210 Po of tobacco was inhaled by smoke through mainstream smoke. One pack-a-day smoker inhaled 24 mBq of 210 Po per day through smoking and the annual inhalation was 8.8 Bq. The risk of mortality from lung cancer caused by 210 Po in tobaccos was 18 per million persons for the above model. (author) 6 refs.; 1 fig.; 4 tabs

  9. In vitro cell culture pO2 is significantly different from incubator pO2.

    Science.gov (United States)

    Bambrick, L L; Kostov, Y; Rao, G

    2011-07-01

    Continuous noninvasive monitoring of peri-cellular liquid phase pO2 in adherent cultures is described. For neurons and astrocytes, this approach demonstrates that there is a significant difference between predicted and observed liquid phase pO2. Particularly at low gas phase pO2s, cell metabolism shifts liquid phase pO2 significantly lower than would be predicted from the O2 gas/air equilibrium coefficient, indicating that the cellular oxygen uptake rate exceeds the oxygen diffusion rate. The results demonstrate the need for direct pO2 measurements at the peri-cellular level, and question the widely adopted current practice of relying on setting the incubator gas phase level as means of controlling pericellular oxygen tension, particularly in static culture systems that are oxygen mass transfer limited. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

  10. Rhenium(V) and technetium(V) complexes of bis(o-hydroxyphenyl)phenylphosphine (PO22-) and (o-hydroxyphenyl)diphenylphosphine (PO-) ligands

    International Nuclear Information System (INIS)

    Luo, Hongyan; Setyawati, Ika; Rettig, S.J.; Orvig, C.

    1995-01-01

    The synthesis of several phosphine-based chelating compounds and chelates formed between these compounds and rhenium or technetium is discussed. Four categories of products result, (i) bis-(o-hydroxyphenyl) diphenylphosphine (PO) complexes, (ii) mono- (PO) complexes, (iii) bis-bis(o-hydroxyphenyl)-phenylphosphine (PO 2 ) complexes, and mixed-(PO) and (PO 2 ) complexes. Molecular structures of these compounds (including isomers) were probed by NMR, MS, and IR spectroscopies and by X-ray crystallography

  11. Mechanical and thermal-expansion characteristics of Ca10(PO46(OH2-Ca3(PO42 composites

    Directory of Open Access Journals (Sweden)

    Ruseska G.

    2006-01-01

    Full Text Available Three types of composites consisting of Ca10(PO46(OH2 and Ca3(PO42 with composition: 75% (wt Ca10(PO46(OH2: 25%(wt Ca3(PO42; 50%(wt Ca10(PO46(OH2: 50%(wtCa3(PO42 and 25 %(wt Ca10(PO46(OH2: 75%(wt Ca3(PO42 were the subject of our investigation. Sintered compacts were in thermal equilibrium, which was proved by the absence of hysteresis effect of the dependence ΔL/L=f(T during heating /cooling in the temperature interval 20-1000-200C. Sintered compacts with the previously mentioned composition possess 26-50% higher values of the E-modulus, G-modulus and K-modulus indicating the presence of a synergism effect. Several proposed model equations for predicting the thermal expansion coefficient in dependence of the thermal and elastic properties of the constitutive phases and their volume fractions, given by: Turner, Kerner, Tummala and Friedberg, Thomas and Taya, were used for making correlations between mechanical and thermal-expansion characteristics of the Ca10(PO46(OH2 - Ca3(PO42 composites. Application of the previously mentioned model equations to all kinds of composites leads to the conclusion that the experimentally obtained results for the thermal expansion coefficient are in an excellent agreement with the theoretical calculated values on account of the volume fraction of each constitutive phase and with all applied model equations, with a coefficient of correlation from 98.16-99.86 %.

  12. 210Po behaviour in terrestrial environment: a review

    International Nuclear Information System (INIS)

    Coppin, F.; Roussel-Debet, S.

    2004-01-01

    This bibliographical review illustrates the behaviour of 210 polonium in the terrestrial environment. Sources of 210 Po in the atmosphere vary especially with the geographical localization and the occurrence or the absence of mining activities. In soils, polonium, because of its atmospheric origin, is concentrated in the first upper centimeters. 210 Po is rather immobile and adsorbed on mineral surfaces; it can (co)precipitate with metallic (oxi)hydroxides or in the form of sulphide. The main transfer pathway of 210 Po to vegetation is foliar deposit, which is not, or only slightly, followed by incorporation or translocation. 210 Po is transferred to animals mainly by ingestion, with relatively high transfer factors. In fresh waters, 210 Po is generally immobile in the form of insoluble Po(IV) and/or associated with the particulate or colloidal phase. Plankton, invertebrates and fish concentrate the 210 Po, especially in soft tissues. Polonium, which is an omnipresent natural radionuclide, is likely to occasion a significant exposure to man, compared with other natural or artificial radioisotopes. Nearly all studies derive from in situ measurements and are very descriptive, therefore experimental work aiming at a better knowledge and modeling of its behaviour in the terrestrial environment would be useful. (author)

  13. Quantitative determination of 210Po in geochemical samples

    International Nuclear Information System (INIS)

    Dyck, W.; Bristow, Q.

    1984-01-01

    To test the usefulness of 210 Po in soils as a means of detecting buried U mineralization, methods for the determination of 210 Po were investigated and adapted for routine production of 210 Po data from geochemical samples. A number of conditions affecting autodeposition and detection of 210 Po were investigated. The optimum area of deposition with a 450 mm 2 solid state detector was found to be 300 mm 2 . Convenience dictated room temperature over-night deposition times, although increased temperature increased speed and efficiency of deposition. A clear inverse relationship was observed between volume of solution and deposition efficiency with stirring times of less than 2 hours. For routine analysis, soil and rock powders were dissolved by leaching 1 g samples in teflon beakers successively with conc. HNO 3 , HF, and HNO 3 -HClO 4 , evaporating the solution to dryness between leaches, and taking the residue up in 20 mL 0.5 M HCl. The 210 Po was deposited on 19 mm diameter Ni discs and counted with an alpha spectrometer system employing 450 mm 2 ruggedized surface barrier detectors. The method achieved 90 percent recovery of 210 Po from solution and a detection efficiency of 30 percent. With a counting time of 3 hours, the method is capable of detecting 0.2 pCi of 210 Po per gram of sample

  14. Concentration of Po-210 and Pb-210 in human tissues

    International Nuclear Information System (INIS)

    Zhao Lancai; Takizawa, Y.; Yamamoto, M.

    1990-01-01

    The levels of Pb-210 and Po-210 in human tissues of people in Japan were determined. Various tissue samples were obtained at autopsy from the cadavers of 22 oncologic cases, mainly in Niigata Prefecture in northern Japan during the period of 1986 to 1988. Wet ashing, followed by electrochemical deposition and alpha-ray spectrometry were used to separate and determine the Pb-210 and Po-210 presented. Among the tissues analyzed the highest concentrations of Pb-210 and Po-210 were observed in bone, liver and kidneys: 1.29, 1.69 and 1.22 Bq.kg -1 respectively for Po-210, and 1.27, 0.56 and 0.43 Bq/kg for Pb-210 respectively. The Po-210/Pb-210 ratios in liver and kidney are 3.0 and 2.9 respectively. Po-210/Pb-210 ratios in other tissues are close to one. The total body burden of Pb-210 and Po-210 was found to be approximately 15.8 Bq and 19.1 Bq respectively

  15. Spirit Pluralisme dalam Klenteng Sam Po Kong Semarang

    Directory of Open Access Journals (Sweden)

    Edi Nurwahyu Julianto

    2015-07-01

    Full Text Available Klenteng Sam Po Kong has very deep meaning as a symbol of multi cultural; multi ethnic and multi religious. Klenteng Sam Po Kong has a different function, not only used by people with background religious Tri Dharma (Budha, Tao and Konghuchu, but also used by Javanese ethnic with different religious backgrounds. Between ethnic China and Java, mutual respect and tolerance run beliefs and rituals of each. More over, Klenteng Sam Po Kong is a form of pluralism which reflected the fact Sino Javanese Muslim Culture is preserved to date both of sightings physical culture and system cultural in the form of religious rites performed by ethnic China and Java.

  16. Accumulation of 210Po by benthic marine algae

    International Nuclear Information System (INIS)

    Gouvea, R.C.; Branco, M.E.C.; Santos, P.L.

    1988-01-01

    The accumulation of polonium 210 Po by various species of benthic marine seaweeds collected from 4 different points on the coast of Rio de Janeiro, showed variations by species and algal groups. The highest value found was in red alga, Plocamium brasiliensis followed by other organisms of the same group. In the group of the brown alga, the specie Sargassum stenophylum was outstanding. The Chlorophyta presented the lowest content of 210 Po. The algae collected in open sea, revealed greater concentration factors of 210 Po than the same species living in bays. The siliceous residue remaining after mineralization of the algae did not interfere with the detection of polonium. (author)

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

    International Nuclear Information System (INIS)

    Seiler, Ralph L.; Stillings, Lisa L.; Cutler, Nichole; Salonen, Laina; Outola, Iisa

    2011-01-01

    Research highlights: → 210 Po activities in numerous domestic wells in Fallon NV exceed 500 mBq/L. → 210 Po levels in sediment are not the primary determinant on levels in groundwater. → δ 34 S measurements indicate SO 4 reduction occurred in all 210 Po contaminated wells. → 210 Po contaminated wells are anoxic, have high pH and low Ca. → Po mobilization probably involves an anaerobic S cycle in which H 2 S dissolves MnO 2 . - Abstract: The discovery of natural 210 Po 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. 210 Po 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 210 Pb activity in study-area sediments and mobilization of a few percent of the 210 Po in the sediments would account for all of the 210 Po in water. Stable-isotope measurements indicate SO 4 reduction has occurred in all 210 Po contaminated wells. Sulfide species are not accumulating in the groundwater in much of Lahontan Valley, probably because of S cycling involving microbial SO 4 reduction, abiotic oxidation of H 2 S to S 0 by Mn(IV), followed by microbial disproportionation of S 0 to H 2 S and SO 4 . The high pH, Ca depletion, MnCO 3 saturation, and presence of S 0 in Lahontan Valley groundwater may be consequences of the anaerobic S cycling. Consistent with data from naturally-enriched wells in Florida, 210 Po 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 H 2 S accumulation begins when anaerobic S cycling stops because Mn oxides are depleted and their reduction is no longer releasing 210 Po

  18. poCAMon personal online continuous airmonitor; poCAMon online Personen Aerosolmonitor

    Energy Technology Data Exchange (ETDEWEB)

    Streil, T.; Oeser, V. [SARAD GmbH, Dresden (Germany)

    2015-07-01

    The poCAMon combines a very compact design with a high flow rate and long battery life. Its size and weight are still acceptable for carrying by one person. The unit measures long-lived aerosols as well as short-lived Radon/Thoron daughters by alpha spectroscopy and beta counting. The radioactive aerosols and particles are collected on the surface of a high resolution membrane filter. The alpha and beta decays on the filter are measured by a high-end semiconductor radiation detector (400 mm@). This allows a perfect separation of the different decay products. The increased pump rate (more than 3 l/ min) is suitable for lower detection limits. A sensor measures permanently the pressure drop on the filter in order to recognize an exhausted or perforated filter instantly. With the 3.8 Ah NiMH battery pack the poCAMon achieves an operation time of more than 30 hours. The quality control is a main issue of any radiation measurement. Therefore the poCAMon records a complete alpha spectrum for each measured value. This allows the monitoring of the device's perfect operation in each moment of the measurement. There are options for additional sensors for carbon monoxide and combustible gases as needed in underground mines. All measured data are stored in a 2GB memory card and can be accessed with a PC or laptop via a USB interface. Data transmission and device control can also be done via wireless ZigBee network or via a server for stationary operation with network access. A barometric pressure sensor and a GPS receiver are optional features of the device.

  19. Superacid univalent metal phosphites (MH2PO3)2·H3PO3 (M Rb, Tl+) and MH2PO3·H3PO3 (M = K, Cs): synthesis and structure

    International Nuclear Information System (INIS)

    Kosterina, E.V.; Troyanov, S.I.; Aslanov, L.A.; Kemnits, Eh.

    2001-01-01

    Crystal superacid phosphites α-CsH 2 PO 3 ·H 3 PO 3 (1) and β-CsH 2 PO 3 ·H 3 PO 3 (2) were prepared by means of interaction between cesium carbonate and phosphoric acid excess. The structure of the compounds, i.e.: 1-rhombic crystal system, sp.gr. P2 1 2 1 2 1 , a = 6.033 (1), b = 6.444 (1), c = 18.345 (4) A: 2-monoclinic crystal system, sp.gr. C2/c, a = 9.990 (3), b = 12.197 (4), c = 6.866 (2) A, β = 118.14 (3) deg, was determined by the method of X-ray diffraction analysis of monocrystals at 150 K. Comparative analysis of the crystal structure and hydrogen bond systems in acid phosphites of different composition was conducted [ru

  20. Electroweak Higgs production with HiggsPO at NLO QCD

    International Nuclear Information System (INIS)

    Greljo, Admir; Isidori, Gino; Zhang, Hantian; Lindert, Jonas M.; Marzocca, David

    2017-01-01

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)

  1. Electroweak Higgs production with HiggsPO at NLO QCD

    Science.gov (United States)

    Greljo, Admir; Isidori, Gino; Lindert, Jonas M.; Marzocca, David; Zhang, Hantian

    2017-12-01

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p_T for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available.

  2. Electroweak Higgs production with HiggsPO at NLO QCD

    Energy Technology Data Exchange (ETDEWEB)

    Greljo, Admir [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Johannes Gutenberg-Universitaet Mainz, PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, Mainz (Germany); University of Sarajevo, Faculty of Science, Sarajevo (Bosnia and Herzegovina); Isidori, Gino; Zhang, Hantian [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); Lindert, Jonas M. [Durham University, Department of Physics, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Marzocca, David [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland); INFN, Sezione di Trieste(Italy); SISSA, Trieste (Italy)

    2017-12-15

    We present the HiggsPO UFO model for Monte Carlo event generation of electroweak VH and VBF Higgs production processes at NLO in QCD in the formalism of Higgs pseudo-observables (PO). We illustrate the use of this tool by studying the QCD corrections, matched to a parton shower, for several benchmark points in the Higgs PO parameter space. We find that, while being sizable and thus important to be considered in realistic experimental analyses, the QCD higher-order corrections largely factorize. As an additional finding, based on the NLO results, we advocate to consider 2D distributions of the two-jet azimuthal-angle difference and the leading jet p{sub T} for new physics searches in VBF Higgs production. The HiggsPO UFO model is publicly available. (orig.)

  3. Study on the excretion of pb-210 and po-210

    Energy Technology Data Exchange (ETDEWEB)

    Okabayashi, Hiroyuki [National Inst. of Radiological Sciences, Chiba (Japan)

    1982-06-01

    The amount of Po-210 excreted in urine and feces was more influenced by Po-210 that was taken with food and drink than taken through inhalation. The amount of Pb-210 in urine of mining workers among uranium mine workers was higher than that of the non-uranium mine workers. It was thought that this fact was due to the working environment in uranium mine the amount of Pb-210 being a few tens times higher than that in normal environment. The activity ratios of Po-210 of faecal to urinary excretion are widely distributed, however, the average value of many samples approached to 10. Urinary excretion of Po-210 was highest after 24 hours of ingestion, but for faecal excretion, it was highest after 3 day.

  4. Prediction of Wind Energy Resources (PoWER) Users Guide

    Science.gov (United States)

    2016-01-01

    ARL-TR-7573● JAN 2016 US Army Research Laboratory Prediction of Wind Energy Resources (PoWER) User’s Guide by David P Sauter...manufacturer’s or trade names does not constitute an official endorsement or approval of the use thereof. Destroy this report when it is no longer needed. Do...not return it to the originator. ARL-TR-7573 ● JAN 2016 US Army Research Laboratory Prediction of Wind Energy Resources (PoWER

  5. Study about excretion of 210 Po in urine

    International Nuclear Information System (INIS)

    Fonseca Azeredo, A.M.G. da.

    1988-01-01

    The urine of mines's workers are analysed to detect the presence of 210 Po. The results was compared with the workers and with a control population. Cigarettes samples was analysed two and confirmed the 210 presence. The control population individuals were divided in smokers and non smokers and them urine was investigated the influence of the smoke in the 210 Po excretion. (L.M.J.)

  6. Po-210 distribution in uranium-mill circuits

    International Nuclear Information System (INIS)

    McKlveen, J.W.; Hubele, N.D.; McDowell, W.J.; Case, G.N.

    1983-01-01

    Greater than 99% of all incoming Po-210 reports to the tailing piles for both the acid and the alkaline leach uranium circuits. Leached Po-210 may be carried along on small particles rather than dissolved in solution. There does not appear to be any radiologically significant buildup or accumulation in the acid leach circuit, but there are noteworthy amounts in the molybdenum recovery solution

  7. Water quality in Italy: Po River and its tributaries

    International Nuclear Information System (INIS)

    Crosa, G.; Marchetti, R.

    1993-01-01

    For Italy's Po River hydrological basin, artificial reservoirs have a great importance; water reserve is about 1600 million cubic meters for the hydroelectric reservoirs and about 76 million cubic meters for irrigation. The principal factors determining the water quality of the Po River and its tributaries are examined. Organic micropollutants, metals and the microbial load are the principal parameters altering the quality of the waters; dilution is the prevailing factor reducing this contamination

  8. Syntheses and characterizations of LiFePO4 powders

    OpenAIRE

    Jugović, Dragana; Kuzmanović, Maja; Mitrić, Miodrag; Cvjetićanin, Nikola; Uskoković, Dragan

    2011-01-01

    The olivine type compositions LiMPO4 (M = Fe, Mn, Co) are among the most attractive materials for the positive electrode of lithium-ion battery. The benefits of using LiFePO4 are excellent cycle life, high structural stability, low cost and environmental friendliness. Here will be presented our efforts to obtain LiFePO4 powders through several synthesis methods. The differences in phase purity, microstructure, morphology, and electrochemical performances of synthesized powders were investigat...

  9. Assessment of Po-210 exposure for the Italian population

    International Nuclear Information System (INIS)

    Clemente, G.F.; Renzetti, A.; Santori, G.; Breuer, F.

    1980-01-01

    Most of the natural internal dose of the general population due to alpha particles is associated with 210 Po exposure. The experimental data obtained to evaluate the levels of 210 Po exposure to members of the general Italian population and to some critical population groups exposed to high radon and daughter air concentration are summarized. The 210 Po content was measured in the following: a) daily diets; b) urinary excretions from members of the general population, both non-smokers and smokers; c) urinary excretions from workers in radioactive spas and non-uranium mines; d) teeth and bone samples from the general population. In most samples the content of 210 Pb, was also measured to assess the behaviour of 210 Po in man. A mathematical model fitting the experimental data was developed to describe the metabolism of systemic 210 Po. Four different levels of 210 Po exposure were detected according to the internal burden measured in the considered subjects. The corresponding dose rate to cortical and trabecular bone and soft tissue was evaluated. The values of the mean dose to the skeleton (cortical bone) were found to range from about 70 μGy/year for non-smokers of the general population to about 2 mGy/year for individuals working inside radioactive spas. (H.K.)

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

    Science.gov (United States)

    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

  11. Assessment of 210Po exposure for the Italian population

    International Nuclear Information System (INIS)

    Clemente, G.F.; Renzetti, A.; Santori, G.; Breuer, F.

    1980-01-01

    A summary is given of the data required to evaluate the 210 Po internal burden and the relative dose given to the members of the Italian general public and to those groups of subjects who are exposed in non-uranium mines and spas to high radon and daughter product air concentrations. Data on the daily intake, daily excretion, total body burden and skeletal burden of 210 Pb and 210 Po for the general public provide the components of the 210 Pb- 210 Po metabolic balance. A mathematical model has been developed on the basis of this data and can be used to evaluate the 210 Pb- 210 Po body burden of subjects exposed to high levels of radon and daughter products on the basis of their 210 Pb- 210 Po daily excretion. Data is presented for the 210 Pb- 210 Po skeletal and soft tissue burden and the yearly dose rate to the skeleton in non-smokers, smokers, non-uranium miners and spa employees. (UK)

  12. Personal monitoring of 218Po and 214Po radionuclide deposition onto individuals under normal environmental exposure conditions

    International Nuclear Information System (INIS)

    Eatough, J.P.; Worley, A.; Moss, G.R.

    1999-01-01

    Personal dosemeters have been utilized to monitor the deposition of the radon decay products 218 Po and 214 Po onto individuals under normal environmental exposure conditions. Each detector consists of TASTRAK alpha-sensitive plastic incorporated into an ordinary working wristwatch. Subsequent analysis provides energy discrimination of the detected alpha-particle decays, and allows events from the individual radon decay products 218 Po and 214 Po, attached to the detector surface, to be uniquely identified. Assuming similar deposition onto skin and detector surfaces, the activity per unit area of deposited radionuclides can be determined for exposed skin. Forty-one personal dosemeters were issued to volunteers selected through the hospital medical physics departments at Reading, Northampton, Exeter and Plymouth. Each volunteer was also issued with a personal radon dosemeter to determine their individual radon exposure. The volunteers wore the two dosemeters simultaneously and continuously for a period of around one month. Correlations were observed between the radon exposure of the individual and the activity per unit area of 218 Po and 214 Po on the detector surface. From these correlations it can be estimated that at the UK average radon exposure of 20 Bq m -3 , the number of decays/cm 2 /year on continuously exposed skin surface is between 3500 and 28 000 for 218 Po, and between 7000 and 21 000 for 214 Po. These results can be combined with theoretical modelling of the dose distribution in the skin to yield the alpha-particle radiation dose to any identified target cells. (author)

  13. Les poèmes ragusains de Dejan Despic

    Directory of Open Access Journals (Sweden)

    Stefanović Ana

    2005-01-01

    Full Text Available (francuski Les œuvres de Dejan Despic (1930, inspirées par Dubrovnik: Jadranski soneti op. 17 (1951-1954, Dubrovacki divertimento op. 18 (1952 et Dubrovacki kanconijer op. 96 (1989, révèlent, outre leur thème commun, une parenté supplémentaire importante. Elles sont incitées et, d'une manière essentielle, médiatisées par la poésie: soit par les vers de Jovan Ducic (1871-1943, poète du Parnasse et symbolisme serbe, soit par la poésie pétrarquiste ragusaine. Or, ces compositions ne se montrent pas seulement en tant qu` issues de l`inspiration par la poésie sur Dubrovnik, mais aussi d'un conditionnement spirituel plus profond: de l`inspiration poétique du compositeur lui-même par Dubrovnik. C`est le sentiment poétique du monde, en tant que constante de la vision créatrice de Dejan Despic, qui provient de cette inspiration particulière. Ce monde ragusain du compositeur est le monde classique dans une signification universelle du concept, selon la nature même du milieu évoqué. Or, cela n implique pas une monochromie stylistique des compositions considérées. Au contraire, les perspectives musicales de l`impressionnisme, du néoclassicisme, voire, de la néorennaissance, varient ce cadre stylistique général, tout en marquant les traits distincts d'une poétique de composition très individualisée.

  14. PoV-GAME: PUNTOS DE VISTA MEDIANTE JUEGOS PoV-GAME: VIEWPOINTS THROUGH GAMES

    Directory of Open Access Journals (Sweden)

    Carlos Zapata-Jaramillo

    2012-06-01

    Full Text Available El desarrollo de proyectos de software considera importante la consistencia entre la información entregada por todos los interesados de una aplicación. En otras palabras, se procura llegar a acuerdos entre los diferentes puntos de vista de cada actor y llevarlos a cabo durante todo el proyecto. Con los métodos de enseñanza tradicionales se procura formar habilidades en este campo, pero no se afianzan mediante la práctica que, generalmente, se emplea para el aprendizaje en este campo. Por ello, en este artículo se propone ''PoV-GAME'', una nueva forma de ''jugar aprendiendo'', la cual busca fortalecer algunos conceptos básicos en la ingeniería de software como la consistencia en la información que se maneja a lo largo de un proyecto y afianzar la importancia de los puntos de vista en el desarrollo de un producto de software. Posteriormente, se analizan los resultados obtenidos luego de realizar el juego en diferentes grupos de estudiantes.Information for software applications is delivered by the stakeholders. Software development projects need consistency as an important aspect of such information. In other words, agreement among the different viewpoints must be reached in order to be implemented in the project. Well-known teaching methods try to create capabilities in this field, but they fail in reinforcing them in practice, which is commonly used for teaching in this field. Therefore, in this paper we propose ''PoV GAME'' a new way of ''play-to-learn''. We aim the reinforcement of some basic concepts about software engineering such as consistency in the information handled throughout the project, and the importance of viewpoints in the software product development. Subsequently, we analyze the results obtained after holding the game in several groups of students.

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

    Science.gov (United States)

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

    2013-01-21

    Carbon-coated olivine NaFePO(4) (C-NaFePO(4)) spherical particles with a uniform diameter of ∼80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO(4) (C-LiFePO(4)), which is synthesized by a solvothermal method. The C-NaFePO(4) electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO(4) except that Li ions in C-LiFePO(4) are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO(4) cathode in sodium-ion (Na-ion) batteries and C-LiFePO(4) in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO(4) 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 LiFePO(4) cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO(4) cathodes, the rate performance of C-NaFePO(4) in Na-ion batteries is much worse than that of C-LiFePO(4) in Li-ion batteries. However, the cycling stability of C-NaFePO(4) is almost comparable to C-LiFePO(4) by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C.

  16. Natural levels of {sup 210}Po in human urine

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Frances, I.; Manjon, G.; Mantero, J.; Diaz, J. [Departament of Applied Phisic II, University of Seville, P.O. Box 41012 Seville (Spain); Garcia-Tenorio, R. [Departament of Applied Phisic II, University of Seville, P.O. Box 41012 Seville (Spain); National Accelerator Centre, P.O. Box 41092 Seville (Spain)

    2014-07-01

    Since the secret agent Alexander Litvinenko was murdered in 2006 by a {sup 210}Po lethal dose, presumably ingested, there is renovated interest on the toxicity of this radionuclide in humans. {sup 210}Po is a radioactive isotope naturally found in nature, mainly incorporated by humans via food and water ingestion, as well as inhaled through its progenitor, the {sup 222}Rn. The total amount of natural {sup 210}Po in the human body can vary from person to person depending on their lifestyle: dietary habits, drinking water source, place of residence (associated with exposure to {sup 222}Rn), etc- and therefore in the concentrations of this element to be found in urine. To analyze the influence of dietary habits on the amount of {sup 210}Po excreted in urine, two volunteers in Seville had a well-defined and time-varying diet for a month, following a daily collection of their urine and determination of the concentrations therein of this radionuclide. The results obtained and the conclusions derived from them form the core of this communication. {sup 210}Po determinations were performed daily in 200 ml aliquots of urine using the technique of high resolution alpha spectrometry. This has involved the application of a single radiochemical method for the concentration and isolation {sup 210}Po, followed by its auto-deposition on copper planchets for proper measure. Daily {sup 210}Po activity concentrations in voluntary urine analyzed during the month of study show high variability with a difference of up to an order of magnitude between maximum and minimum values obtained, and a clear dependence on the diet type followed in the various stages of the experiment. The lowest concentrations obtained are associated with a diet rich in carbohydrates and proteins 'terrestrial' (pork, beef,...), while the highest concentrations were obtained in the final phase of the experiment when the diet was enriched with presence of marine products in fair correspondence with the

  17. PoSSUM: Polar Suborbital Science in the Upper Mesosphere

    Science.gov (United States)

    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

  18. 210Pb and 210Po activities in French foodstuffs

    International Nuclear Information System (INIS)

    Renaud, Ph.; Roussel-Debet, S.; Pourcelot, L.; Thebault, H.; Loyen, J.; Gurriaran, R.

    2015-01-01

    The data on 210 Pb and 210 Po activities in French foodstuffs acquired during the last 15 years are numerous enough to derive reference values which will be usable to assess the dose to the French population due to the intake of these two natural radionuclides. The means and ranges are close to those observed in various countries and are most often higher than the reference values proposed by UNSCEAR. Mussels and oysters exhibit the highest 210 Po activities of all kinds of foodstuffs, with a mean value of 27 Bq.kg -1 fresh weight, followed by crustaceans and small fish species (anchovies, mullets, sardines, etc.) with 210 Po activities in the order of 3 to 10 Bq.k -1 fresh weight; cephalopods and other fish species presenting activities around 1 to 3 Bq.kg -1 fresh, close to the UNSCEAR reference value. Below these highest 210 Po activities are those of 210 Po and 210 Pb in terrestrial kinds of foodstuffs, by decreasing order: meats (around 1 Bq.kg -1 fresh), cereals (0.4 Bq.kg -1 ), leafy vegetables (0.3 Bq.kg -1 ), other vegetables and fruits (0.1 Bq.kg -1 ), and milk (from 0.03 to 0.1 Bq.L -1 ). (authors)

  19. Enhanced photo-stability and photocatalytic activity of Ag3PO4 via modification with BiPO4 and polypyrrole

    Science.gov (United States)

    Cai, Li; Jiang, Hui; Wang, Luxi

    2017-10-01

    Ag3PO4 photocatalysts modified with BiPO4 and polypyrrole (PPy) were successfully synthesized via a combination of co-precipitation hydrothermal technique and oxidative polymerization method. Their morphologies, structures and optical and electronic properties were characterized by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface areas, X-ray diffraction (XRD), fourier transform infrared spectra (FT-IR), X-ray photo-electron spectroscopy (XPS), UV-vis diffuse reflection spectra (UV-vis DRS), photocurrent technique and electrochemical impedance spectra (EIS). The typical triphenylmethane dye (malachite green) was chosen as a target organic contaminants to estimate the photocatalytic activities and photo-stabilities of Ag3PO4-BiPO4-PPy heterostructures under visible light irradiation. The results indicated that the existence of BiPO4 and PPy not only showed great influences on the photocatalytic activity, but also significantly enhanced photo-stability of Ag3PO4 in repeated and long-term applications. The degradation conversion of Ag3PO4-BiPO4-PPy heterostructures (ABP-3) was 1.58 times of that of pure Ag3PO4. The photo-corrosion phenomenon of Ag3PO4 was effectively avoided. The photocatalytic activity of up to 87% in the Ag3PO4-BiPO4-PPy heterostructures (ABP-3) can be remained after five repeated cycles, while only about 33% of the degradation efficiency can be reserved in pure Ag3PO4. The possible mechanism of enhanced photo-stability and photocatalytic activity of Ag3PO4-BiPO4-PPy heterostructures was also discussed in this work.

  20. Les poèmes ragusains de Dejan Despic

    OpenAIRE

    Stefanović Ana

    2005-01-01

    (francuski) Les œuvres de Dejan Despic (1930), inspirées par Dubrovnik: Jadranski soneti op. 17 (1951-1954), Dubrovacki divertimento op. 18 (1952) et Dubrovacki kanconijer op. 96 (1989), révèlent, outre leur thème commun, une parenté supplémentaire importante. Elles sont incitées et, d'une manière essentielle, médiatisées par la poésie: soit par les vers de Jovan Ducic (1871-1943), poète du Parnasse et symbolisme serbe, soit par la poésie pétrarquiste ragusaine. Or, ces compositions ne se mon...

  1. Co3(PO42·4H2O

    Directory of Open Access Journals (Sweden)

    Yang Kim

    2008-10-01

    Full Text Available Single crystals of Co3(PO42·4H2O, tricobalt(II bis[orthophosphate(V] tetrahydrate, were obtained under hydrothermal conditions. The title compound is isotypic with its zinc analogue Zn3(PO42·4H2O (mineral name hopeite and contains two independent Co2+ cations. One Co2+ cation exhibits a slightly distorted tetrahedral coordination, while the second, located on a mirror plane, has a distorted octahedral coordination environment. The tetrahedrally coordinated Co2+ is bonded to four O atoms of four PO43− anions, whereas the six-coordinate Co2+ is cis-bonded to two phosphate groups and to four O atoms of four water molecules (two of which are located on mirror planes, forming a framework structure. In addition, hydrogen bonds of the type O—H...O are present throughout the crystal structure.

  2. 210Pb and 210Po in Finnish cereals

    International Nuclear Information System (INIS)

    Turtiainen, Tuukka; Kostiainen, Eila; Hallikainen, Anja

    2011-01-01

    A survey was carried out on the activity concentrations of 210 Pb and 210 Po in cereal grains produced in Finland. The cereal species were wheat (Triticum aestivum), rye (Secale cereale), oats (Avena sativa) and barley (Hordeum vulgare), which account for 90% of the Finnish consumption of cereal products. The survey consisted of 18 flour and 13 unprocessed cereal samples and one hulled grain sample from 22 flour mills. According to the results, the mean 210 Pb/ 210 Po concentrations in wheat grains, wheat flour, rye flour, oat grains and barley grains were 0.29, 0.12, 0.29, 0.36 and 0.36 Bq kg -1 , respectively. Combined with the consumption rates of the products, we assess that the mean effective doses from 210 Pb and 210 Po in cereal products for the adult male and female population are 22 and 17 μSv per year, respectively.

  3. 210Pb and 210Po in Finnish cereals.

    Science.gov (United States)

    Turtiainen, Tuukka; Kostiainen, Eila; Hallikainen, Anja

    2011-05-01

    A survey was carried out on the activity concentrations of (210)Pb and (210)Po in cereal grains produced in Finland. The cereal species were wheat (Triticum aestivum), rye (Secale cereale), oats (Avena sativa) and barley (Hordeum vulgare), which account for 90% of the Finnish consumption of cereal products. The survey consisted of 18 flour and 13 unprocessed cereal samples and one hulled grain sample from 22 flour mills. According to the results, the mean (210)Pb/(210)Po concentrations in wheat grains, wheat flour, rye flour, oat grains and barley grains were 0.29, 0.12, 0.29, 0.36 and 0.36 Bq kg(-1), respectively. Combined with the consumption rates of the products, we assess that the mean effective doses from (210)Pb and (210)Po in cereal products for the adult male and female population are 22 and 17 μSv per year, respectively. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. 210Po radiation dose due to cigarette smoking

    International Nuclear Information System (INIS)

    Godwin, Wesley S.; Subha, Vincila R.; Feroz, Khan M.

    2010-01-01

    The level of 210 Po in eight brands of cigarettes and four brands of bidis popular in and around Nagercoil town was determined to evaluate the annual effective dose. The 210 Po activity in a full cigarette ranged from 32.8±3.6 to 68.4±5.9 mBq and from 34.3±3.5 to 62.9±5.8 mBq in a bidi. In tobacco, the highest 210 Po content was recorded in the brand C4 (23.0±1.2 mBq) whereas for bidis it was the highest in the brand B2 (21.1±1.1 mBq). The activity in mainstream varied from 15.2±0.75 to 36.8±2.1 mBq in a cigarette and from 20.7±3.1 to 39.8±4.0 mBq in a bidi. With regard to 210 Po activity concentration, not much specificity was noted with respect to the tobacco brand. The data showed a relatively wide range of activity concentration of 210 Po in the different cigarette/bidi brands and even within the same brand. The bidis showed a higher activity when compared to cigarettes. The popular brands concentrated more activity than the fine brands. Smokers who smoke one pack (10 cigarettes/bidis) per day may inhale about 100-300 mBq d -1 (0.1-0.3 Bq d -1 ) of 210 Po. In this study, radiation dose values in the range of 153.5-372.9 μSv Y - '1 from cigarettes and from 209.2 to 402.7 μSvY -1 from bidis was estimated for the whole body. (author)

  5. Po-210 and other radionuclides in terrestrial and freshwater environments

    Energy Technology Data Exchange (ETDEWEB)

    Gjelsvik, Runhild; Brown, Justin [eds.; Norwegian Radiation Protection Authority (Norway); Holm, Elis [Univ. of Lund (Sweden); Roos, Per [Risoe DTU (Denmark); Saxen, Ritva; Outola, Iisa [STUK - Radiation and Nuclear Safety Authority (Finland)

    2009-01-15

    This report provides new information on Po-210 (and where appropriate its grandparent Pb-210) behaviour in environmental systems including humans. This has primarily been achieved through measurements of Po-210 in aquatic and terrestrial environments that has led to the derivation of information on the levels of this radioisotope in plants, animals and the biotic components of their habitat (i.e. water, soil) providing basic information on transfer where practicable. For freshwater environments, Po-210 concentration ratios derived for freshwater benthic fish and bivalve mollusc were substantially different to values collated from earlier review work. For terrestrial environments, activity concentrations of Po-210 in small mammals (although of a preliminary nature because no correction was made for ingrowth from Pb-210) were considerably higher than values derived from earlier data compilations. It was envisaged that data on levels of naturally occurring radionuclides would render underpinning data sets more comprehensive and would thus allow more robust background dose calculations to be performed subsequently. By way of example, unweighted background dose-rates arising from internal distributions of Po-210 were calculated for small mammals in the terrestrial study. The biokinetics of polonium in humans has been studied following chronic and acute oral intakes of selected Po radioisotopes. This work has provided information on gastrointestinal absorption factors and biological retention times thus improving the database upon which committed effective doses to humans are derived. The information generated in the report, in its entirety, should be of direct relevance for both human and non-human impact assessments. (au)

  6. Po-210 and other radionuclides in terrestrial and freshwater environments

    International Nuclear Information System (INIS)

    Gjelsvik, Runhild; Brown, Justin; Roos, Per; Saxen, Ritva; Outola, Iisa

    2009-01-01

    This report provides new information on Po-210 (and where appropriate its grandparent Pb-210) behaviour in environmental systems including humans. This has primarily been achieved through measurements of Po-210 in aquatic and terrestrial environments that has led to the derivation of information on the levels of this radioisotope in plants, animals and the biotic components of their habitat (i.e. water, soil) providing basic information on transfer where practicable. For freshwater environments, Po-210 concentration ratios derived for freshwater benthic fish and bivalve mollusc were substantially different to values collated from earlier review work. For terrestrial environments, activity concentrations of Po-210 in small mammals (although of a preliminary nature because no correction was made for ingrowth from Pb-210) were considerably higher than values derived from earlier data compilations. It was envisaged that data on levels of naturally occurring radionuclides would render underpinning data sets more comprehensive and would thus allow more robust background dose calculations to be performed subsequently. By way of example, unweighted background dose-rates arising from internal distributions of Po-210 were calculated for small mammals in the terrestrial study. The biokinetics of polonium in humans has been studied following chronic and acute oral intakes of selected Po radioisotopes. This work has provided information on gastrointestinal absorption factors and biological retention times thus improving the database upon which committed effective doses to humans are derived. The information generated in the report, in its entirety, should be of direct relevance for both human and non-human impact assessments. (au)

  7. Concentrations of 210Po in fish and shellfish from southern region of Japan and evaluation of 210Po intake from seafood for Japanese people

    International Nuclear Information System (INIS)

    Momoshima, N.; Sugihara, S.; Nakao, H.

    2012-01-01

    Concentrations of 210 Po in fish and shellfish, mostly collected from southern region of Japan were analyzed. Values ranged from 0.2 to 229 Bq/kg fresh weight and higher concentrations were observed in samples analyzed with viscera. Intake of 210 Po through fish and shellfish was evaluated at different Japanese cities based on statistical consumption data. Phytoplankton, Heterosigma akashiwo was collected during a harmful algal bloom and 210 Po was analyzed. The phytoplankton occupied only 4.4% of 210 Po in seawater and a large fraction of 210 Po was observed in the particulate form. (orig.)

  8. Po Superconducting Magnet:detail of the windings

    CERN Multimedia

    1982-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam Po. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8307552X.

  9. Los 'Horizontes poéticos' (1881) de Francisca Sarasate

    OpenAIRE

    Mata-Induráin, C. (Carlos)

    1999-01-01

    Francisca Sarasate supone una excepción notable en el área de las letras navarras, por la escasez de mujeres en el ámbito literario. Cultivó, entre otros, la novela, el cuento, el teatro y la poesía. Destaca su obra 'Horizontes poéticos'. ------------------ Francisca Sarasate is a notable exception in the area of the letters of Navarra, by the scarcity of women in the literary field. She cultivated the novel, short stories, drama and poetry. She wrote, among others, 'Horizontes poéticos'....

  10. Thermal analysis of a LiFePo4 Battery

    OpenAIRE

    Balanguer Escolano, David

    2014-01-01

    The objective of this final thesis project was to study and test a 3,3V LiFePo4 battery in outer space conditions to be able to determine its working range, its limitations and its problems. To do so a measuring set-up to read and estimate the capacity of a battery was built and programmed. Then the LiFePo4 battery was tested at different temperatures between -20°C and 40°C in a vacuum chamber at a pressure under 100 microbars. The results showed that the battery can still operate prope...

  11. Structural and Electrochemical Characterization of Pure LiFePO4 and Nanocomposite C-LiFePO4 Cathodes for Lithium Ion Rechargeable Batteries

    Directory of Open Access Journals (Sweden)

    Arun Kumar

    2009-01-01

    Full Text Available Pure lithium iron phosphate (LiFePO4 and carbon-coated LiFePO4 (C-LiFePO4 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 LiFePO4 particles. Ex situ Raman spectrum of C-LiFePO4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of LiFePO4 and C-LiFePO4 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 LiFePO4 where as in case of C-LiFePO4 that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO4 was 69% after 25 cycles where as that of C-LiFePO4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.

  12. Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO4/FePO4 electrode

    Directory of Open Access Journals (Sweden)

    Kazuya Tokuda

    2014-07-01

    Full Text Available LiFePO4 is a potential positive electrode material for lithium ion batteries. We have experimentally observed an imbalance between the valence change of Fe ions and the structure change from the LiFePO4 phase to the FePO4 phase during delithiation by simultaneous in situ XRD and XANES measurements in an LiFePO4/FePO4 electrode. The ratio of structure change to valence change clearly indicates that the phase separation from LiFePO4 to FePO4 is suppressed at the beginning of delithiation, while it is accelerated at the latter stage, which is due to the coherent strain caused by the lattice misfit between the two phases.

  13. Poétique de l’invective dans les Poèmes aristophanesques de Laurent Tailhade

    Directory of Open Access Journals (Sweden)

    Laurent Robert

    2012-04-01

    Full Text Available Parmi l’abondant corpus traité par Marc Angenot dans La Parole pamphlétaire, les ouvrages de Laurent Tailhade Au Pays du mufle et À travers les Grouins [sic] constituent les seuls recueils poétiques. L’essayiste y voit une illustration du genre de la satire poétique, revivifié dès la fin du xviiie siècle avec les Iambes d’André Chénier, puis au xixe notamment par Auguste Barbier et Victor Hugo. Tailhade pourrait ainsi, superficiellement, être considéré comme le poète satiriste de la Troisième...

  14. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    Science.gov (United States)

    Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared with a value approximating normal resting Po2. Dihydrofluorescein was loaded into single frog (Xenopus) fibers, and fluorescence was used to monitor ROS using confocal microscopy. Myofibers were exposed to two maximal tetanic contractile periods (1 contraction/3 s for 2 min, separated by a 60-min rest period), each consisting of one of the following treatments: high Po2 (30 Torr), low Po2 (3–5 Torr), high Po2 with ebselen (antioxidant), or low Po2 with ebselen. Ebselen (10 μM) was administered before the designated contractile period. ROS formation during low Po2 treatment was greater than during high Po2 treatment, and ebselen decreased ROS generation in both low- and high-Po2 conditions (P Po2. Force was reduced >30% for each condition except low Po2 with ebselen, which only decreased ∼15%. We concluded that single myofibers under low Po2 conditions develop accelerated and more oxidative stress than at Po2 = 30 Torr (normal human resting Po2). Ebselen decreases ROS formation in both low and high Po2, but only mitigates skeletal muscle fatigue during reduced Po2 conditions. PMID:23576612

  15. Determination of 210Pb and 210Po in cigarette tobacco

    International Nuclear Information System (INIS)

    Peres, Ana Claudia

    1999-01-01

    Cigarette smoking is one of the important pathways that could contribute to enhance the radiation dose to man, due to the relatively large concentrations of 210 Pb and 210 Po found in tobacco leaves. In this work, concentrations of these two radionuclides were determined in eight of the most commercialized cigarette brands produced in Brazil. The samples analyzed were bought randomly in the market. The 210 Pb was determined by counting the beta activity of the 210 Bi in a gas flow proportional detector, after radiochemical separation and precipitation of the PbCr0 4 . The 210 Po was determined by alpha spectrometry, using a surface barrier detector, after radiochemical separation and spontaneous deposition of Po in copper disk. The results showed concentrations ranging from 11,9 to 30,2 mBq per gram of dry tobacco for 210 Pb and from 10,9 to 27,4 mBq per gram of dry tobacco for 210 Po. (author)

  16. Pb-210 and Po-210 from active volcanoes in Japan

    International Nuclear Information System (INIS)

    Komura, K.; Uchida, K.; Yamamoto, M.; Ueno, K.

    1991-01-01

    The concentration of Pb-210 and Po-210 in the surface air of volcanic areas is of considerable interest from the viewpoints of geochemistry, geophysics and also health physics, because these nuclides are the useful tracers for the estimation of the residence time or life time of aerosols, and give the significant radiation dose due to inhalation and ingestion through food stuffs. Since the establishment of Low Level Radioactivity Laboratory, Kanazawa University, in 1976, the measurement of environmental radioactivity has been one of the main subjects, and the measurement of Pb-210 and Po-210 in the surface air of Kagoshima was begun in 1987 to estimate the contribution from Volcano Sakurajima. In this study, the measurement of Pb-210 and Po-210 in air borne particles collected with air samplers, volcanic ash and lava of volcano Sakurajima of which the age of eruption is known. Moreover, the Po-210 in the volcanic gas and sulfur sublimate in the samples collected in four active volcanoes in Hokkaido was measured. The experiment and the results are reported. (K.I.)

  17. PO2 measurements in the rat intestinal microcirculation

    NARCIS (Netherlands)

    Sinaasappel, M.; Donkersloot, C.; van Bommel, J.; Ince, C.

    1999-01-01

    Microvascular partial oxygen pressure (PO2) data measured with the quenched phosphorescence of palladium-porphyrin (Pd-porphyrin) with the use of optical fibers have provided new insight into the behavior of the microvascular oxygenation in models of shock. However, the actual microcirculatory

  18. Spontaneous Fluctuations of PO2 in the Rabbit Somatosensory Cortex.

    Science.gov (United States)

    Linsenmeier, Robert A; Aksenov, Daniil P; Faber, Holden M; Makar, Peter; Wyrwicz, Alice M

    2016-01-01

    In many tissues, PO2 fluctuates spontaneously with amplitudes of a few mmHg. Here we further characterized these oscillations. PO2 recordings were made from the whisker barrel cortex of six rabbits with acutely or chronically placed polarographic electrodes. Measurements were made while rabbits were awake and while anesthetized with isoflurane, during air breathing, and during 100% oxygen inspiration. In awake rabbits, 90% of the power was between 0 and 20 cycles per minute (cpm), not uniformly distributed over this range, but with a peak frequently near 10 cpm. This was much slower than heart or respiratory rhythms and is similar to the frequency content observed in other tissues. During hyperoxia, total power was higher than during air-breathing, and the dominant frequencies tended to shift toward lower values (0-10 cpm). These observations suggest that at least the lower frequency fluctuations represent efforts by the circulation to regulate local PO2. There were no consistent changes in total power during 0.5 or 1.5% isoflurane anesthesia, but the power shifted to lower frequencies. Thus, both hyperoxia and anesthesia cause characteristic, but distinct, changes in spontaneous fluctuations. These PO2 fluctuations may be caused by vasomotion, but other factors cannot be ruled out.

  19. Increased intraretinal PO2 in short-term diabetic rats.

    Science.gov (United States)

    Lau, Jennifer C M; Linsenmeier, Robert A

    2014-12-01

    In diabetic retinopathy, neovascularization is hypothesized to develop due to hypoxia in the retina. However, evidence for retinal hypoxia is limited, and the progressive changes in oxygenation are unknown. The objective of this study was to determine if retinal hypoxia occurs early in the development of diabetes. Intraretinal oxygen (PO2) profiles were recorded with oxygen-sensitive microelectrodes in control and diabetic Long-Evans rats at 4 and 12 weeks after induction of diabetes. Diabetes did not affect oxygen consumption in the photoreceptors in either dark or light adaptation. Oxygenation of the inner retina was not affected after 4 weeks of diabetes, although vascular endothelial growth factor levels increased. At 12 weeks, average inner retinal PO2, normalized to choriocapillaris PO2, was higher in diabetic rats than in age-matched controls, which was opposite to what was expected. Thus retinal hypoxia is not a condition of early diabetes in rat retina. Increased inner retinal PO2 may occur because oxygen consumption decreases in the inner retina. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  20. Bioaccumulation of polonium 210Po in marine birds

    International Nuclear Information System (INIS)

    Skwarzec, B.; Fabisiak, J.

    2007-01-01

    The aim of this work was to determine the 210 Po 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 210 Po 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 210 Po 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 210 Po on the feather surface may be an important transfer from air to water

  1. Po kanalu TBTs pokazhut film o "Vaffen-SS"

    Index Scriptorium Estoniae

    2006-01-01

    Vene filmistuudio Treti Rim on tootnud lätivastase ajaloolise dokumentaali-propagandafilmi Teisest Maailmasõjast "Natslus Balti moodi" ("Natsizm po pribaltiski"). Filmi näitab täna Vene telekanal TVT, andes siiski võimaluse eetris esineda Läti Venemaa suursaadikule Andris Teikmanisele

  2. Measurement of airborne 218Po - A Bayesian approach

    International Nuclear Information System (INIS)

    Groer, P.G.; Lo, Y.

    1996-01-01

    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 218 Po can be characterized as an open-quotes immigration-death processclose quotes in the widely adopted, biologically based jargon. The probability distribution for the number of 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 ε during a counting period T after the end of sampling, it also Poisson, with mean dependent on ε,t,T, the flowrate and N o , the number of airborne 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 o . This density characterizes the remaining uncertainty about the measured under of 218 Po atoms per unit volume of air. 6 refs., 3 figs., 1 tab

  3. Adsorption gas chromatography with 150-ms {sup 216}Po

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, A [Bern Univ. (Switzerland); Gaeggeler, H W; Tuerler, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    A gas chromatography apparatus was developed, which allows experiments with volatile radionuclides having shorter half-lives than one second. This apparatus was tested with the 150-ms isotope {sup 216}Po. Experimental data were compared with a Monte Carlo model to determine the adsorption enthalpy {Delta}H{sub a}. (author) 2 figs., 2 refs.

  4. Environmental impact from inlet of radiocesium in the river Po

    International Nuclear Information System (INIS)

    Dominici, G.; Risposi, L.

    1991-01-01

    In this report are reported the environmental parameters from which effective dose equivalent and collective effective dose equivalent, due to a letting of 370 GBq of radiocesium, spread uniformly over a period of a year, into the waters of river Po, are computed

  5. Natural levels of 210Po in human urine

    International Nuclear Information System (INIS)

    Diaz-Frances, I.; Garcia-Tenorio, R.; Mantero, J.; Diaz, J.; Manjon, G.

    2013-01-01

    The daily activity of 2 10Po concentrations in the urine of a volunteer for a month analyzed studies show a high variability with a difference of up to an order of magnitude between the maximum and minimum values obtained, and a clear dependence on the type of diet followed in the various phases of the experiment. (Author)

  6. Pb-210 and Po-210 from active volcanoes in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Komura, K; Uchida, K; Yamamoto, M; Ueno, K [Kanazawa Univ. (Japan)

    1991-01-01

    The concentration of Pb-210 and Po-210 in the surface air of volcanic areas is of considerable interest from the viewpoints of geochemistry, geophysics and also health physics, because these nuclides are the useful tracers for the estimation of the residence time or life time of aerosols, and give the significant radiation dose due to inhalation and ingestion through food stuffs. Since the establishment of Low Level Radioactivity Laboratory, Kanazawa University, in 1976, the measurement of environmental radioactivity has been one of the main subjects, and the measurement of Pb-210 and Po-210 in the surface air of Kagoshima was begun in 1987 to estimate the contribution from Volcano Sakurajima. In this study, the measurement of Pb-210 and Po-210 in air borne particles collected with air samplers, volcanic ash and lava of volcano Sakurajima of which the age of eruption is known. Moreover, the Po-210 in the volcanic gas and sulfur sublimate in the samples collected in four active volcanoes in Hokkaido was measured. The experiment and the results are reported. (K.I.).

  7. Development of a Portable Motor Learning Laboratory (PoMLab).

    Science.gov (United States)

    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

  8. Development of a Portable Motor Learning Laboratory (PoMLab.

    Directory of Open Access Journals (Sweden)

    Ken Takiyama

    Full Text Available 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

  9. Crystal structures of Th(OH)PO4, U(OH)PO4 and Th2O(PO4)2. Condensation mechanism of M(IV)(OH)PO4 (M= Th, U) into M2O(PO4)2

    International Nuclear Information System (INIS)

    Dacheux, N.; Clavier, N.; Wallez, G.; Quarton, M.

    2007-01-01

    Three new crystal structures, isotypic with β-Zr 2 O(PO 4 ) 2 , have been resolved by the Rietveld method. All crystallize with an orthorhombic cell (S.G.: Cmca) with a = 7.1393(2) Angstroms, b = 9.2641(2) Angstroms, c 12.5262(4) Angstroms, V = 828.46(4) (Angstroms) 3 and Z = 8 for Th(OH)PO 4 ; a = 7.0100(2) Angstroms, b = 9.1200(2) Angstroms, c = 12.3665(3) Angstroms, V 790.60(4) (Angstroms) 3 and Z = 8 for U(OH)PO 4 ; a 7.1691(3) Angstroms, b 9.2388(4) Angstroms, c = 12.8204(7) Angstroms, V 849.15(7) (Angstroms) 3 and Z = 4 for Th 2 O(PO 4 ) 2 . By heating, the M(OH)PO 4 (M Th, U) compounds condense topotactically into M 2 O(PO 4 ) 2 , with a change of the environment of the tetravalent cation that lowers from 8 to 7 oxygen atoms. The lower stability of Th 2 O(PO 4 ) 2 compared to that of U 2 O(PO 4 ) 2 seems to result from this unusual environment for tetravalent thorium. (authors)

  10. Ocena urodynamiczna nietrzymania moczu po radykalnej prostatektomii - studium przypadku

    Directory of Open Access Journals (Sweden)

    Rafał Święcicki

    2010-06-01

    Full Text Available Nietrzymanie moczu po radykalnej prostatektomii we wczesnym okresie po zabiegu występuje u około 30% operowanych, natomiast w okresie późnym, ponad rok po zabiegu, objawy wysiłkowego nietrzymania moczu utrzymują się u około 5% badanych chorych. Obiektywnych danych na temat przyczyn i nasilenia nietrzymania moczu może dostarczyć kompleksowe badanie urodynamiczne. Zasadnicze znaczenie dla rokowania zależne jest od stopnia dysfunkcji aparatu zwieraczowego. Cel pracy: Celem pracy była ocena możliwości diagnostycznych pooperacyjnego nietrzymania moczu u chorego po prostatektomii radykalnej, na podstawie diagnostyki urodynamicznej. Materia! i metody: W pracowni urodynamicznej 10. Wojskowego Szpitala Klinicznego z Polikliniką (WSKzP wykonano kompleksowe badanie urodynamiczne u chorego skarżącego się na nietrzymanie moczu 12 miesięcy po radykalnej prostatektomii. W ramach badania wykonano przepływ cewkowy, cystometrię, badanie ciśnieniowo-przepływowe oraz profiłometrię spoczynkową. Wyniki: Maksymalne ciśnienie zamknięcia cewki moczowej było wyraźnie obniżone, do wartości 8 cm H20, c o sugerowało obecność wysiłkowego nietrzymania moczu. Stwierdzono również objawy niestabilności wypieracza oraz cechy uszkodzenia mechanizmu zwieraczowego. Wynik ten miał duże znaczenie dla dalszych możliwości leczenia chorego. Wnioski: Kompleksowe badanie urodynamiczne ma istotne znaczenie w diagnozowaniu chorych z pooperacyjnym nietrzymaniu moczu.

  11. Experiments for detection of gaseous Po-210 originated from microbial activity in the environment

    International Nuclear Information System (INIS)

    Ishimoto, A.; Momoshima, N.

    2006-01-01

    We attempted to detect gaseous Po-210 (half-life 138d) emitted from organisms in the environment. Gaseous Po-210 was tried to collect in 0.5 M nitric acid solution after passing the atmospheric air through filters and a distilled water bubbler, which would remove aerosols existing in the air. The activity of Po-210 was determined by alpha spectrometry after radiochemical separation and electrolytic deposition of Po-210 on a silver disk. Twenty seven point four mBq of Po-210 was observed when 800 m 3 atmospheric air was sampled. Blank of Po-210 in regents and the sampling system was 4.9-6.8 mBq. The concentration of Po-210 observed in the atmospheric air was, thus about 5 times higher than the background; the results strongly support existence of gaseous Po-210 in the environment. (author)

  12. Acid indium strontium phosphate SrIn2[PO3(OH)]4: synthesis and crystal structure

    International Nuclear Information System (INIS)

    Rusakov, D.A.; Bobylev, A.P.; Komissarova, L.N.; Filaretov, A.A.; Danilov, V.P.

    2007-01-01

    Acid indium-strontium phosphate SrIn 2 [PO 3 (OH)] 4 is synthesized and characterized. Crystal structure and lattice parameters ate determined. In atoms in SrIn 2 [PO 3 (OH)] 4 structure are in distorted InO 6 octahedrons and form with PO 3 (OH) tetrahedrons mixed paraskeleton {In 2 [PO 3 (OH)] 4 } 3∞ 2- with emptinesses occupied by big Sr 2+ cations. The compound is thermally stable up to 400 Deg C [ru

  13. High-spin yrast states in the 206Po, 208Po, 209At and 210At nuclei

    International Nuclear Information System (INIS)

    Rahkonen, Vesa.

    1980-08-01

    High-spin yrast states in the 206 , 208 Po and 209 , 210 At nuclei have been studied with methods of in-beam γ-ray and conversion-electron spectroscopy and with the (α,3n), (α,4n), (p,2n) and ( 3 He,3n) reactions. Several new high-spin states have been identified up to angular momenta of 18-19 h/2π in these nuclei except in 206 Po where the highest spin was (13 - ). In the course of this work two new isomers with half-lives of 15+-3 ns and 4+-2 μs have been observed at 1689 and 4028 keV in 210 At, which have been interpreted as (10 - ) and 19 + states. The previously-known half-lives of 29+-2 and 680+-75 ns have been established for the three-proton states of Jsup(π)=21/2 - and 29/2 + at 1428 and 2429 keV in 209 At, respectively. A half-life of 1.0+-0.2 μs was measured for the 9 - isomer in 206 Po. Shell-model calculations based on the use of the empirical single- and two-particle interaction energies or of the experimental excitation energies belonging to the relevant one-, two- and three-particle states, have been carried out for these 4-6 particle nuclei. Most of the medium-spin yrast states in 206 Po, 208 Po and 209 At have been successfully described assuming the core for these nuclei being 204 Pb or 206 Pb rather than 208 Pb, and including an extra core polarization interaction described by the P 2 force. (author)

  14. Stability of luminescence in LaPO4, LaPO4 :RE(3+) (RE = Dy, Eu) nanophosphors.

    Science.gov (United States)

    Pimpalshende, D M; Dhoble, S J

    2015-03-01

    The property of high refractive index, low solubility in water as well as stability to high temperature variation of lanthanum phosphate (LaPO4 ) proved it was the most effective candidate for the production of display lamps, and plasma display panel devices and sensors. The morphological and nanostructural characteristics play a key role in the working efficiency of the luminescent material. These properties can be controlled by the synthesis method, which we have adopted in this paper. We have prepared LaPO4 nanoparticles at a relatively low temperature (110 ºC) in polyethylene glycol medium by using a wet chemical one-step synthesis. The phase composition and structural properties of the sample have been characterized by X-ray diffraction, Fourier transform infrared, transmission electron microscopy and the luminescent property by photoluminescence and thermoluminescence. The samples were well crystallized and the average crystallite size of 15 nm has been calculated for pure LaPO4 using the Debye-Scherrer equation. The result from heat-treated samples shows the phase combination and morphological structure of the powder depend on the annealing temperature. The heat treatment changes the structure of LaPO4 from cuboid rods to fine grains at about 600 °C. The emission spectrum of LaPO4 shows the broad emission band at 368 nm and shoulder at 465 nm with emission of blue color when monitored at an excitation wavelength at 256 nm. The stability of phosphor has been studied with respect to humidity, temperature, doping, doping concentration, γ-ray exposures, etc. The prepared nanosized phosphors were thermally stable and may be a promising blue phosphor for lighting technology as well as radiation dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.

  15. Ra-226, Pb-210, and Po-210 in the Black Forest

    International Nuclear Information System (INIS)

    Schuettelkopf, H.; Kiefer, H.

    1981-01-01

    By measuring Pb-210, Po-210 and Ra 226 in air, water, ground, plants, and food samples the concentration ranges of the radionuclide and the transfer factor important for the calculation of the ingestion dose of man were determined. Po 210 was found to have the lowest radiotoxicity. The highest Po-210 concentrations were found in protein-containing food. (DG) [de

  16. Hydrothermal synthesis of LiFePO4 nanorods composed of ...

    Indian Academy of Sciences (India)

    Administrator

    LiFePO4 nanorods composed of nanoparticles were synthesized from ... olivine structure; belongs to Pnma space group. ... LiFePO4 has one-dimensional (1D) channel along the ... phases of LiFePO4 ... Among the various synthesis techniques available, the .... Prosini P, Lisi M, Zane D and Pasquali M 2002 Solid State. Ion.

  17. New equations to calculate temperature correction factors for PO2 in human blood.

    Science.gov (United States)

    Inaba, H; Ohwada, T; Sato, J; Mizuguchi, T; Hirasawa, H

    1986-01-01

    Effects of hemoglobin concentration (Hb), pH, and body temperature (T) on the relationships between delta log PO2/delta T and PO2 were studied by means of a mathematical model using a Newton-Raphson iteration method. The functions between delta log PO2/delta T and PO2 were affected by the above three factors. New equations considering the effects of Hb, pH, and T were proposed by modifying the equation reported by Severinghaus: delta log PO2/delta T = (L +(U-L)/(A(vPO237)B + 1))(10(-2) where U = 3.15-0.45(7.4-pH37) L = 0.68-0.09(7.4-pH37) A = 5.86(exp10(0.074(T)-0.294(7.4-pH37)-11))((Hb)0.913) B = 6.33(exp10(-0.0051(T)))((Hb)-0.113) + 0.24(7.4-pH37) and vPO237 is virtual PO237 which may exist when PO237 is corrected to standard conditions (pH = 7.4, BE = 0) by the following equations: vPO237 = PO237(exp10(fB(7.4-pH37)-0.0013(BE))) fB = (PO237/26.6)0.08-1.52 where fB is the Bohr factor. The above equations provided values of delta log PO2/delta T which fit closely to those obtained by the complex iteration method with maximum differences of less than 1.3 X 10(-3) at T = 27, indicating that maximum % errors for PO2 at T (PO2T) are less than 3.0% at T = 27 and that our equations can be applied over a wide range of Hb, pH37 and T.

  18. Conductivity And Thermal Stability of Solid Acid Composites CsH2PO4 /NaH2PO4/ SiO2

    International Nuclear Information System (INIS)

    Norsyahida Mohammad; Abu Bakar Mohamad; Abu Bakar Mohamad; Abdul Amir Hassan Kadhum

    2016-01-01

    Solid acid composites CsH 2 PO 4 / NaH 2 PO 4 / SiO 2 with different mole ratios of CsH 2 PO 4 and NaH 2 PO 4 to SiO 2 were synthesized and characterized. Preliminary infrared measurements of CsH 2 PO 4 and its composites indicated that hydrogen bonds breaking and formation were detected between 1710 to 2710 cm -1 , while the rotation of phosphate tetrahedral anions occurred between 900 and 1200 cm -1 . The superprotonic transition of CsH 2 PO 4 / NaH 2 PO 4 / SiO 2 composite was identified at superprotonic temperatures between 230 and 260 degree Celcius, under atmospheric pressure. This study reveals higher conductivity values for composites with higher CsH 2 PO 4 (CDP) content. Solid acid composite CDP 613 appeared as the composite with the highest conductivity that is 7.2x10 -3 S cm -1 at 230 degree Celcius. Thermal stability of the solid acid composites such as temperature of dehydration, melting and decomposition were investigated. The addition of NaH 2 PO 4 lowers the dehydration temperature of the solid acid composites. (author)

  19. Ternary phosphates in Ca3(PO4)2-Na3Ln(PO4)2 (Ln-Nd, Eu, Er) systems

    International Nuclear Information System (INIS)

    Lazoryak, B.I.; Ivanov, L.N.; Strunenkova, T.V.; Golubev, V.N.; Viting, B.N.

    1990-01-01

    Ternary phosphates, formed in Ca 3 (PO 4 ) 2 -Na 3 Ln(PO 4 ) 2 (Ln-Nd, Eu, Er) systems were investigated by the methods of X-ray phase, luminescent analyses and IR spectroscopy. 5 regions of homogeneity were found. Two of them (I and II) were distinguished for all systems. Samples in the region of up to 14.285 mol.% Na 3 Ln(PO 4 ) 2 crystallize on the basis of β-Ca 3 (PO 4 ) 2 structure, and in other homogeneity regions - on the basis of β-K 2 SO 4 structure

  20. AHP 47: A RIG RGAD PO VISITS LHA SA

    Directory of Open Access Journals (Sweden)

    Pad ma skyid པདྨ་སྐྱིད།

    2017-04-01

    Full Text Available My name is Pad ma skyid. I was born in 1981 in Pan yag Community, 'Bo spa Township, Pad ma County, Mgo log Tibetan Autonomous Prefecture, Mtsho sngon (Qinghai Province. I have eight siblings. Growing up in a black yak-hair tent, we spent our days playing with lambs, foals, and calves. We told all sorts of stories when everyone was in bed - stories about King Ge sar, ghosts, marriages, and tricksters. It was a time for my whole family to relax and share. I heard many A rig rgad po stories from my parents, siblings, and guests. A rig rgad po became part of my childhood. These stories bring back many beautiful memories. ...

  1. The low lying yrast structure of 212Po

    International Nuclear Information System (INIS)

    Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.

    1987-07-01

    The properties of states in 212 Po populated by the 208 Pb( 9 Be,αn) 212 Po reaction have been investigated. the previously proposed yrast scheme below 3MeV has been verified and eight further transitions placed in the level scheme. Mean lives of the 6 + , 8 + and (10 + ) states at 1355, 1476 and 1834 keV have been measured as 1.1(3), 24.6(3) and 0.8(2)ns respectively. Shell model calculations using effective interactions were used to interpret the observed scheme. A synthesis of all available theoretical and experimental evidence allows the 65s isomer to be identified clearly as the 18 + level arising primarily from the π(h 9/2 2 )*ν(g 9/2 i 11/2 ) configuration

  2. The low-lying yrast structure of 212Po

    International Nuclear Information System (INIS)

    Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.

    1987-01-01

    The properties of states in 212 Po populated by the 208 Pb( 9 Be,αn) 212 Po reaction have been investigated. The previously proposed yrast scheme below ≅ 3 MeV has been verified and eight further transitions placed in the level scheme. Mean lives of the 6 + , 8 + and (10 + ) states at 1355, 1476 and 1834 keV have been measured at 1.1 (3), 24.6 (3) and 0.8 (2) ns respectively. Shell model calculations using effective interactions were used to interpret the observed scheme. A synthesis of all available theoretical and experimental evidence allows the τ m = 65 s isomer to be identified clearly as the 18 + level arising primarily from the π(h 2 9/2 ) * ν(g 9/2 i 11/2 ) configuration. (orig.)

  3. International intercomparison on glass implanted 210Po in Yugoslavian houses

    International Nuclear Information System (INIS)

    Zunic, Z.S.; Trotti, F.; Birovljev, A.; Bissolo, F.; Falk, R.; Mc Laughlin, J.P; Tanferi, A.; Walsh, C.

    2000-01-01

    Measurements of 210 Po embedded in glass have been performed with passive detectors in houses of three rural communities of Yugoslavia. Field work has been initiated and carried out by the VINCA Institute of nuclear sciences, Belgrade, and analyses have been conducted by SSI (Sweden), UCD (Ireland), NRPA (Norway) and CRR (Italy). Based on 210 Po concentration assessments, radon retrospective estimates have been produced. Fairly good agreement amongst laboratories resulted both for polonium and radon determinations. Comparison of radon retrospective estimates with contemporary levels has identified a small number of contemporary concentrations which are certainly not representative of the past. Retrospective measurements give clear indication of higher levels for one of the three communities (Gornja Stubla). From the analysis of retrospective and contemporary levels in different rooms of a high concentration house in Gornja Stubla, less data dispersion has come out for retrospective estimates, indicating a sort of better spatial stability of these estimates. (author)

  4. Deuteron momentum distribution in KD2PO4

    International Nuclear Information System (INIS)

    Reiter, G; Shukla, A; Platzman, P M; Mayers, J

    2008-01-01

    The momentum distribution in KD 2 PO 4 (DKDP) has been measured using neutron Compton scattering above and below the weakly first-order paraelectric-ferroelectric phase transition (T=229 K). There is very little difference between the two distributions, and no sign of the coherence over two locations for the proton observed in the paraelectric phase, as in KH 2 PO 4 (KDP). We conclude that the tunnel splitting must be much less than 20 meV. The width of the distribution indicates that the effective potential for DKDP is significantly softer than that for KDP. As electronic structure calculations indicate that the stiffness of the potential increases with the size of the coherent region locally undergoing soft mode fluctuations, we conclude that there is a mass-dependent quantum coherence length in both systems

  5. Levels of 210Po in some beverages and in tobacco

    International Nuclear Information System (INIS)

    Colangelo, C.H.; Huquet, M.R.; Palacios, M.A.; Oliveira, A.A.

    1992-01-01

    The objective of the present work is the estimation of the 210 Po content in some beverages and in tobacco, in order to assess the corresponding collective doses to the population in Argentina. Yerba mate, tea leaves, their infusions and ground coffee were analyzed, as well as tobacco. Collective doses due to the annual consumption of the beverages described were found to be from 6 man.Sv to 1200 man.Sv. Results for 210 Po in tobacco ranged from 10 Bq*kg -1 to 80 Bq*kg -1 . Lung doses due to the use of tobacco vary from 75 μSv*y -1 to 600 μSv*y -1 . (author) 14 refs.; 1 fig.; 5 tabs

  6. The role of 210Po and 210Pb in low radioactivity experiments and ultrapure water

    International Nuclear Information System (INIS)

    Giammarch, Marco G.

    2013-01-01

    210 Po and 210 Pb isotopes constitute a major background for low background nuclear physics experiments searching for rare events. Searches for solar neutrinos, double beta decay, dark matter and other rare phenomena need to control and monitor radioactivity from Po and Pb through measurements and purification processes. Ultrapure water is often used in these experiments; therefore the issue of minimizing Po and Pb content in water will also be discussed. Finally, the role of 214 Po and 212 Po in low background experiments will be briefly recalled. (author)

  7. Towards a construction grammar account of the distributive PO in Polish

    Directory of Open Access Journals (Sweden)

    Adam Przepiórkowski

    2015-11-01

    Full Text Available Towards a construction grammar account of the distributive PO in Polish Polish distributive constructions involving the form po are well known for their syntactic and semantic idiosyncrasy. The aim of this paper is to show that, contrary to the received wisdom, two different lexemes po take part in such constructions: a preposition and an adnumeral operator. This explains some of the idiosyncratic behaviour, namely, the apparent ability of po to combine with different grammatical cases. A preliminary Construction Grammar analysis is proposed which eschews the potential problem of missed generalisations that such a dual account of po might engender.

  8. Improvement on LiFePO4 Cell Balancing Algorithm

    OpenAIRE

    Vencislav C. Valchev; Plamen V. Yankov; Dimo D. Stefanov

    2018-01-01

    The paper presents improvement on operation time of cell balancing algorithm compared to conventional multiple cell LiFePO4 charge methodology. A flowchart is synthesised to explain the main steps of the software design, which afterwards is implemented in a microcontroller. Experimental results are provided to clarify the transition between charge and balance process. Graphical data for a voltage equalization of eight cells is presented to verify the proposed improvement.

  9. Comparison of LiFePO4 from different sources

    OpenAIRE

    Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

    2003-01-01

    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 carb...

  10. Improvement on LiFePO4 Cell Balancing Algorithm

    Directory of Open Access Journals (Sweden)

    Vencislav C. Valchev

    2018-02-01

    Full Text Available The paper presents improvement on operation time of cell balancing algorithm compared to conventional multiple cell LiFePO4 charge methodology. A flowchart is synthesised to explain the main steps of the software design, which afterwards is implemented in a microcontroller. Experimental results are provided to clarify the transition between charge and balance process. Graphical data for a voltage equalization of eight cells is presented to verify the proposed improvement.

  11. A new determination of the 209Po half-life

    International Nuclear Information System (INIS)

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

    2014-01-01

    A substantial 25% error in the then-known and accepted (102 ± 5) year half-life of 209 Po was reported on in 2007. This error was detected from decay data from two separate primary standardizations of a 209 Po solution standard, which were performed approximately 12 years apart. Despite author claims that this observation was not a new half-life determination, it was nevertheless included in subsequent nuclear data evaluations and compilations to obtain a currently tabulated value of (115 ± 13) a, computed from the median and range of the two half-life reports. A third primary standardization on the identical 209 Po solution has since been performed to derive a new half-life value of (125.2 ± 3.3) a. This half-life determination was obtained from 30 distinct data sets over a period of 20.7 years, encompassing over 700 liquid scintillation measurements with nearly 50 counting sources all prepared from the same solution, and as obtained over a very broad range of measurement conditions (composition of cocktails, characteristics of counters, time sequencing) during five periods in 1993, 1994, 2005, and 2013. (paper)

  12. Alpha-particle and electron capture decay of 209Po

    International Nuclear Information System (INIS)

    Schima, F.J.; Colle, R.

    1996-01-01

    Gamma-ray and Kα X-ray emissions have been measured from a very pure 209 Po source containing less than 0.13% 208 Po activity and no detectable 210 Po (≤2 x 10 -4 %). The alpha-particle emission rate for this source has previously been determined. Data are presented that confirm alpha decay to the 205 Pb excited level at 262.8 keV, with an alpha-particle emission probability (±standard uncertainty) of 0.00559±0.00008. The ratio of K-shell electron capture to total electron capture for the second forbidden unique electron capture decay to the 896.6 keV level in 209 Bi was determined to be 0.594±0.018. The electron capture decay fraction was found to be 0.00454±0.00007, while the probabilities per decay for the 896.6, 262.8, and 260.5 keV gamma rays and the Bi Kα and Pb Kα X-rays were measured as 0.00445±0.00007, 0.00085±0.00002, 0.00254±0.00003, 0.00202±0.00005, and 0.00136±0.00005, respectively. (orig.)

  13. A biokinetic study of {sup 209}Po in man

    Energy Technology Data Exchange (ETDEWEB)

    Henricsson, C.F.; Ranebo, Y. [Department of Medical Radiation Physics, Clinical Sciences in Lund, Lund University, Skane University Hospital in Lund (Sweden); Hansson, M. [Medical Radiation Physics, Department of Clinical Sciences in Malmoe, Lund University, Skane University Hospital in Malmoe (Sweden); Raeaef, C.L., E-mail: Christopher.Raaf@med.lu.se [Medical Radiation Physics, Department of Clinical Sciences in Malmoe, Lund University, Skane University Hospital in Malmoe (Sweden); Holm, E. [Norwegian Radiation Protection Authority, Osteras (Norway)

    2012-10-15

    Five adult volunteers participated in a biokinetic study of radioactive polonium. Portions of about 10 Bq of {sup 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 {sup 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. -- Highlights: Black-Right-Pointing-Pointer Human metabolism of an oral intake of polonium. Black-Right-Pointing-Pointer 4 individuals were administrated about 10 Bq polonium-209. Black-Right-Pointing-Pointer Gastro-intestinal uptake fraction, if orally administrated polonium-209 was investigated. Black-Right-Pointing-Pointer The biological half-time of polonium in human body was studied.

  14. Notas sobre poética em andamento

    Directory of Open Access Journals (Sweden)

    Mauro Faccioni Filho

    2006-06-01

    Full Text Available 1.1. A aflição poética não desapareceu nem abandonou o cenário da produção, mas é evidente que esse mesmo cenário está invadido por demonstrações artificiais. Tais demonstrações podem ser respostas inconscientes às expectativas de uma historiografia da literatura. Ou respostas a uma estratégia de contextualização da produção organizada pela própria crítica que a sustenta. 1.2. As notas que seguem são reflexões para discutir disparidades e distorções em três diferentes tipos de poética que, para muitos, apontam como sendo caminhos de referência para uma certa continuidade da poesia, hoje, no Brasil. Pode-se representar tais poéticas em três linhas bastante distintas, três tendências gerais. São linhas que podem ser definidas como vetores defasados agindo como forças centrífugas, que serão denominadas aqui de pré-modernismo-contemporâneo, modernismo e pós-modernismo.

  15. 210Po activity concentrations in mussels at Aegean Turkish Coast

    International Nuclear Information System (INIS)

    Sekkin, F.; Tanbay, A.; Vener, V.

    2000-01-01

    In Turkey mussels (Mytilus galloprovincialis) are consumed in relatively large quantities. Therefore, analyses of mussel samples from different sampling sites in Aegean Sea were performed in order to evaluate the ingestion of 210 Po and 210 Pb by the Turkey population. Polonium analyses were performed with a complete dissolution of the sample in mineral acids. Polonium isotopes were plated onto a copper discs in 0.5 M HCl solution in the presence of ascorbic acid using a technique modified from Flynn (1968). The alpha activity measurements of polonium isotopes plated on copper discs were performed with ZnS(Ag) detector. The highest concentrations was found in Karaburun mussels as 254 Bq.kg -1 and the lowest one was at Inciralti as 18 Bq.kg -1 . Based on these 210 Po activity concentrations, annual dose equivalent rates delivered to biological tissues in mussels would vary widely, from 136 to 10 mSv.y -1 . It is concluded that in mussels living in the Aegean Sea a wide range of internal radiation dose exists and it is essentially sustained by 210 Po food-chain transfer. (author)

  16. The system Ba(H2PO4)2-Sr(H2PO4)2-H3PO4(30%)-H2O at 25, 40 and 60 deg C

    International Nuclear Information System (INIS)

    Taranenko, N.P.; Serebrennikova, G.M.; Stepin, B.D.; Oboznenko, Yu.V.

    1982-01-01

    The system Ba(H 2 PO 4 ) 2 -Sr(H 2 PO 4 ) 2 -H 3 PO 4 (30%)-H 2 O (25 deg C) belongs to eutonic type systems. Solubility isotherms of salt components at 40 and 60 deg C are calculated. Polytherms (25-60 deg C) of solubility of monosubstituted barium and strontium phosphates in 30-60% H 3 PO 4 are obtained. The value of cocrystallization coefficient of Sr 2 + and Ba(H 2 PO 4 ) 2 Dsub(Sr)=0.042+-0.005 remains stable in the temperature range of 25-60 deg C and concentrations 30-60% phosphoric acid at initial content [Sr 2 + ]=1x10 - 2 mass%

  17. Experimental Evaluation of the Transport Mechanisms of PoIFN-α in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-11-01

    Full Text Available For the development of an efficient intestinal delivery system for Porcine interferon-α (PoIFN-α, the understanding of transport mechanisms of which in the intestinal cell is essential. In this study, we investigated the absorption mechanisms of PoIFN-α in intestine cells. Caco-2 cells and fluorescein isothiocyanate-labeled (FITC-PoIFN-α were used to explore the whole transport process, including endocytosis, intracellular trafficking, exocytosis, and transcytosis. Via various techniques, the transport pathways of PoIFN-α in Caco-2 cells and the mechanisms were clarified. Firstly, the endocytosis of PoIFN-α by Caco-2 cells was time, concentration and temperature dependence. And the lipid raft/caveolae endocytosis was the most likely endocytic pathway for PoIFN-α. Secondly, both Golgi apparatus and lysosome were involved in the intracellular trafficking of PoIFN-α. Thirdly, the treatment of indomethacin resulted in a significant decrease of exocytosis of PoIFN-α, indicating the participation of cyclooxygenase. Finally, to evaluate the efficiency of PoIFN-α transport, the transepithelial electrical resistance (TEER value was measured to investigate the tight junctional integrity of the cell monolayers. The fluorescence microscope results revealed that the transport of PoIFN-α across the Caco-2 cell monolayers was restricted. In conclusion, this study depicts a probable picture of PoIFN-α transport in Caco-2 cells characterized by non-specificity, partial energy-dependency and low transcytosis.

  18. Synthesis and Electrochemical Properties of LiFePO4/C for Lithium Ion Batteries.

    Science.gov (United States)

    Gao, Hong; Wang, Jiazhao; Yin, Shengyu; Zheng, Hao; Wang, Shengfu; Feng, Chuanqi; Wang, Shiquan

    2015-03-01

    LiFePO4/C was prepared through a facile rheological phase reaction method by using Fe3(PO4)2, Li3PO4 · 8H2O, and glucose as reactants. The LiFePO4/C samples were characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The electrochemical properties of the samples were investigated. The results show that the LiFePO4/C samples have single-phase olivine-type structure, and their particles feature a spherical shape. The carbon coating on the particles of LiFePO4 is about 1.8% of the LiFePO4/C by weight. The particle size was distributed from 0.2 to 1 µm. The initial discharge capacity of LiFePO4/C reached 154 mA h/g at 0.1 C. The retained discharge capacity of LiFePO4/C was 152.9 mA h g(-1) after 50 cycles. The LiFePO4/C also showed better cycling performance than that of the bare LiPeO4 at a higher charge/discharge rate (1 C). The LIFePO4/C prepared in this way could be a promising cathode material for lithium ion battery application.

  19. Spectroscopy and measurement of electromagnetic moments in sup(198,200,210)Po

    International Nuclear Information System (INIS)

    Maier, K.H.

    1985-01-01

    The quadrupole coupling constants for the 210 Po Isup(π)=8 + , 11 - , 13 - isomers in Bi have been measured, and Q(11 - )=82(2) fm 2 and Q(13 - )=90(2) fm 2 normalized to Q( 210 Po8 + )=57 fm 2 are deduced. In beam γ-spectroscopy of sup(198,) 200 Po showed the (πh 2 sub(9/2) 8 + ) π(hsub(9/2)isub(13/2) 11 - ) and (visub(13/2) 12 + ) isomers. The B(E2 8 + ->6 + ) and Q(8 + ) in 198 Po to 210 Po are discussed, a sudden drop is found for the B(E2) in 198 Po. The B(E3, 11 - ->8 + ) rises very steeply in the light Po isotopes. (orig.)

  20. Formation of condensed phosphates when heating CdO with NH4H2PO4

    International Nuclear Information System (INIS)

    Atstinya, L.Zh.; Dindune, A.P.; Konstant, Z.A.

    1987-01-01

    A study was made on process of CdO thermal condensation with NH 4 H 2 PO 4 depending on the ratio of basic substances and temperature synthesis conditions. It was established that reaction between CdO and NH 4 H 2 PO 4 of pure for analysis grade was initiated when basic mixtures were pounded with a pestle. Heating of cadmium-ammonium triphosphate with products of ammonium dihydrophosphate polycondensation in 330-350 deg C range resulted to CdNH 4 (PO 3 ) 3 formation. Exoeffect on DTA curves corresponded at 540 deg C to formation of α-Cd(PO 3 ) 2 . α-Cd(PO 3 ) 2 → β-Cd(PO 3 ) 2 transition took place at 810 deg C with successive melting of β-Cd(PO 3 ) 2 at 850 deg C, which was supported by the DTA curve and sharp change of the relative electric conductivity

  1. Studies of the balance 210Pb - 210Po in glasses; Estudios del equilibrio 210Pb - 210Po en vidrios

    Energy Technology Data Exchange (ETDEWEB)

    Torre Pérez, J. de la; Martín Sánchez, A.; Ruano Sánchez, A.B.

    2014-07-01

    Retrospective dosimetry requires measurement methods allowing the determination of Radon concentration in the past. One of the such methods is based on the direct measurement of 210Po implanted on the surface of objects, whose activity concentration (Bq/m2), is directly related to the cumulative exposure due to the concentration of 222Rn (Bq/m3) for long time. These determinations are possible taking into consideration the equilibrium between 210Po (T1/2 = 138.378 days) and its parent 210Pb (T1/2 = 22.3 years), being both radionuclides from the 222Rn progeny. In previous works about the determination of the conversion factor (ratio between the concentration of 210Po in objects and the retrospective 222Rn concentration in air), Corresponding equilibria between descendants were assumed. In this work, an experimental study about the equilibrium 210Pb - 210Po in glasses, which were previously exposed to some radon concentrations, has been performed. Two scenarios were studied: a place with, and another place without, continuous cumulative 222Rn concentration. Results were compared with those reached by theoretical calculations from the (Bateman) activity evolution equations. [Spanish] La dosimetría retrospectiva requiere métodos de medida que permitan la determinación de la concentración de radón en el pasado. Uno de estos métodos está basado en la medida directa del 210Po implantado sobre la superficie de objetos, cuya concentración de actividad (Bq/m2), está directamente relacionada con la exposición acumulativa debida a la concentración de 222Rn (Bq/m3) durante largos períodos de tiempo. Estas determinaciones son posibles gracias al equilibrio entre el 210Po (T1/2 = 138,378 días) y su progenitor, el 210Pb (T1/2 = 22,3 años), siendo ambos radionúclidos descendientes del 222Rn. En trabajos anteriores sobre la determinación del factor de conversión (relación entre la concentración de 210Po en los objetos y la concentración de 222Rn retrospectivo en

  2. Occurrence of 210Po and Biological Effects of Low-Level Exposure: The Need for Research

    Science.gov (United States)

    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

  3. H-PoP and H-PoPG: heuristic partitioning algorithms for single individual haplotyping of polyploids.

    Science.gov (United States)

    Xie, Minzhu; Wu, Qiong; Wang, Jianxin; Jiang, Tao

    2016-12-15

    Some economically important plants including wheat and cotton have more than two copies of each chromosome. With the decreasing cost and increasing read length of next-generation sequencing technologies, reconstructing the multiple haplotypes of a polyploid genome from its sequence reads becomes practical. However, the computational challenge in polyploid haplotyping is much greater than that in diploid haplotyping, and there are few related methods. This article models the polyploid haplotyping problem as an optimal poly-partition problem of the reads, called the Polyploid Balanced Optimal Partition model. For the reads sequenced from a k-ploid genome, the model tries to divide the reads into k groups such that the difference between the reads of the same group is minimized while the difference between the reads of different groups is maximized. When the genotype information is available, the model is extended to the Polyploid Balanced Optimal Partition with Genotype constraint problem. These models are all NP-hard. We propose two heuristic algorithms, H-PoP and H-PoPG, based on dynamic programming and a strategy of limiting the number of intermediate solutions at each iteration, to solve the two models, respectively. Extensive experimental results on simulated and real data show that our algorithms can solve the models effectively, and are much faster and more accurate than the recent state-of-the-art polyploid haplotyping algorithms. The experiments also show that our algorithms can deal with long reads and deep read coverage effectively and accurately. Furthermore, H-PoP might be applied to help determine the ploidy of an organism. https://github.com/MinzhuXie/H-PoPG CONTACT: xieminzhu@hotmail.comSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  4. Topotactic insertion of lithium in the layered structure Li4VO(PO4)2: The tunnel structure Li5VO(PO4)2

    International Nuclear Information System (INIS)

    Satya Kishore, M.; Pralong, V.; Caignaert, V.; Malo, S.; Hebert, S.; Varadaraju, U.V.; Raveau, B.

    2008-01-01

    A new V(III) lithium phosphate Li 5 VO(PO 4 ) 2 has been synthesized by electrochemical insertion of lithium into Li 4 VO(PO 4 ) 2 . This phase, which crystallizes in the space group I4/mcm, exhibits a tunnel structure closely related to the layered structure of Li 4 VO(PO 4 ) 2 and to the tunnel structure of VO(H 2 PO 4 ) 2 . The topotactic reactions that take place during lithium exchange and intercalation, starting from VO(H 2 PO 4 ) 2 and going to the final phase Li 5 VO(PO 4 ) 2 are explained on the basis of the flexible coordinations of V 4+ and V 3+ species. The electrochemical and magnetic properties of this new phase are also presented and explained on the basis of the structure dimensionality. - Graphical abstract: Electrochemical synthesis of a new 3D V(III) lithium phosphate, Li 5 VO(PO 4 ) 2 . Starting from the 2D Li 4 VO(PO 4 ) 2 , the topotactic reaction that take place during lithium intercalation is explained on the basis of the flexible coordinations of V 4+ and V 3+ species

  5. Heat capacity of Sr10(PO4)6Cl2 and Ca10(PO4)6Cl2 by DSC

    International Nuclear Information System (INIS)

    Venkata Krishnan, R.; Jena, Hrudananda; Govindan Kutty, K.V.; Nagarajan, K.

    2008-01-01

    Strontium and calcium chloroapatites were synthesized by wet chemical method, characterized by X-ray diffraction and are found to be phase pure materials. The measured room temperature lattice parameter of Ca 10 (PO 4 ) 6 Cl 2 is a = 9.523 A, c = 6.855 A and for Sr 10 (PO 4 ) 6 Cl 2 is a = 9.876 A, c = 7.188 A. Heat capacity measurements were carried out on Ca 10 (PO 4 ) 6 Cl 2 and Sr 10 (PO 4 ) 6 Cl 2 by DSC in the temperature range 298-800 K. The heat capacity values of Sr 10 (PO 4 ) 6 Cl 2 is higher at all temperatures than Ca 10 (PO 4 ) 6 Cl 2 . Enthalpy and entropy increments were computed. Heat capacity values of Ca 10 (PO 4 ) 6 Cl 2 and Sr 10 (PO 4 ) 6 Cl 2 at 298 K are 758 and 868 J K -1 mol -1 , respectively

  6. Improved analytical procedure for the determination of 210Pb and 210Po using alpha-spectrometric isotope dilution

    International Nuclear Information System (INIS)

    Urnezis, P.W.; Holtzman, R.B.

    1981-01-01

    An isotope dilution method has been incorporated into the 210 Pb- 210 Po analysis. A known amount of 209 Po is added to the sample before analysis. Then both 209 Po and 210 Po are deposited on a silver planchet which is assayed in an alpha spectrometer to determine the activities of each isotope. The recoveries generally range from 70% to 90%

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    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 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L 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. - Highlights: ► 210 Pb and 210 Po measurement in water by 210 Po spontaneous deposition onto silver disks. ► 210 Pb and 210 Po determination based on 210 Po measurement in two different aliquots. ► Evaluation of characteristic limits in radioactivity measurements using ISO 11929-7. ► 10 Pb - 210 Po detection limits decrease with time elapsed between 210 Po measurements.

  8. Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO4 and LiMnPO4

    Science.gov (United States)

    Shi, Jianjian; Wang, Zhiguo; Qing Fu, Yong

    2016-12-01

    Coating LiMnPO4 with a thin layer of LiFePO4 shows a better electrochemical performance than the pure LiFePO4 and LiMnPO4, thus it is critical to understand Li diffusion at their interfaces to improve the performance of electrode materials. Li diffusion at the (1 0 0)\\text{LiFeP{{\\text{O}}4}} //(1 0 0)\\text{LiMnP{{\\text{O}}4}} , (0 1 0)\\text{LiFeP{{\\text{O}}4}} //(0 1 0)\\text{LiMnP{{\\text{O}}4}} , and (0 0 1)\\text{LiFeP{{\\text{O}}4}} //(0 0 1)\\text{LiMnP{{\\text{O}}4}} interfaces between LiFePO4 and LiMnPO4 was investigated using density functional theory. The calculated diffusion energy barriers are 0.55 eV for Li to diffuse along the (0 0 1) interface, 0.44 and 0.49 eV for the Li diffusion inside the LiMnPO4 and along the (1 0 0) interface, respectively. When Li diffuses from the LiFePO4 to LiMnPO4 by passing through the (0 1 0) interfaces, the diffusion barriers are 0.45 and 0.60 eV for the Li diffusions in both sides. The diffusion barriers for Li to diffuse in LiMnPO4 near the interfaces decrease compared with those in the pure LiMnPO4. The calculated diffusion coefficient of Li along the (1 0 0) interface is in the range of 3.65  ×  10-11-5.28  ×  10-12 cm2 s-1, which is larger than that in the pure LiMnPO4 with a value of 7.5  ×  10-14 cm2 s-1. Therefore, the charging/discharging rate performance of the LiMnPO4 can be improved by surface coating with the LiFePO4.

  9. 210Po in Nevada groundwater and its relation to gross alpha radioactivity

    Science.gov (United States)

    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.

  10. Postępowanie z chorym po zawale serca

    Directory of Open Access Journals (Sweden)

    Kalina Niedolaz

    2011-10-01

    Full Text Available Choroba wieńcowa, czyli choroba niedokrwienna serca na podłożu miażdżycy tętnic wieńcowych, stanowi niezwykle istotny problem kliniczny. Jej bezpośrednim i często nieuchronnym następstwem jest zawał mięśnia serca. Zawał najczęściej jest spowodowany zamknięciem tętnicy wieńcowej w wyniku uszkodzenia blaszki miażdżycowej (jej pęknięcia lub erozji z następowym wytworzeniem dystalnego zakrzepu i powoduje zniszczenie prawidłowo działającego mięśnia sercowego. Chory po przebytym zawale mię- śnia serca należy do grupy pacjentów obciążonych wysokim ryzykiem sercowo-naczyniowym, a więc zagrożony jest wystąpieniem kolejnych incydentów, takich jak zawał, udar mózgu i zgon. Prawidłowe postępowanie po przebytym zawale pozwala na istotną redukcję ryzyka i korzystnie wpływa na rokowanie. Prewencja wtórna po zawale serca obejmuje postępowanie niefarmakologiczne, czyli modyfikację stylu życia, i leczenie farmakologiczne. Największe znaczenie ma wyeliminowanie czynników ryzyka, tj. zaprzestanie palenia papierosów, prawidłowa kontrola ciśnienia tętniczego i normalizacja poziomu cholesterolu, a także redukcja nadwagi i systematyczna aktywność fizyczna. Świadomość pacjentów i zaangażowanie lekarzy są decydujące dla osiągnięcia korzystnych efektów prewencji wtórnej po zawale serca. Artykuł przedstawia zasady, którym powinien podlegać każdy chory po zawale mięśnia serca, uwzględnia zalecenia dotyczące postępowania niefarmakologicznego, wytyczne dotyczące odpowiedniej farmakoterapii według aktualnych standardów. W pracy uwzględniono również zasady postępowania z chorym po zawale w sytuacjach szczególnych, jakimi są choroby współistniejące, takie jak nadciśnienie tętnicze, cukrzyca, dysfunkcja lewej komory i niewydolność serca, przewlekła choroba nerek, przewlekła obturacyjna choroba płuc.

  11. 210Po concentration analysis on tobacco and cigarettes in Malaysia

    Science.gov (United States)

    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. Working with NASA's OSS E/PO Support Network

    Science.gov (United States)

    Miner, E. D.; Lowes, L. L.

    2001-11-01

    With greater and greater emphasis on the inclusion of a public engagement component in all government-supported research funding, many members of the DPS are finding it difficult to find sufficient time and funding to develop a wide-reaching and effective E/PO program. NASA's Office of Space Science, over the last five years, has built a Support Network to assist its funded scientists to establish partnerships with local and/or national science formal or informal education organizations, who are anxious to connect with and use the expertise of space scientists. The OSS Support Network consists of four theme-based 'Forums,' including the Solar System Exploration (SSE) Forum, specifically designed for working with planetary scientists, and seven regional 'Brokers-Facilitators' who are more familiar with partnership and other potential avenues for involvement by scientists. The services provided by the Support Network are free to both the scientists and their potential partners and is not limited to NASA-funded scientists. In addition to its assistance to space scientists, the Support Network is involved in a number of other overarching efforts, including support of a Solar System Ambassador Program, a Solar System Educator Program, Space Place (web and e-mail science products for libraries and small planetariums and museums), an on-line Space Science Resource Directory, annual reports of Space Science E/PO activity, identifying and filling in 'holes' and 'over-populations' in a solar system E/PO product matrix of grade level versus product versus content, research on product effectiveness, and scientific and educational evaluation of space science products. Forum and Broker-Facilitator contact information is available at http://spacescience.nasa.gov/education/resources/ecosystem/index.htm. Handouts with additional information will be available at the meeting.

  13. Climatology of atmospheric PM10 concentration in the Po Valley

    Science.gov (United States)

    Bigi, A.; Ghermandi, G.

    2014-01-01

    The limits to atmospheric pollutant concentration set by the European Commission provide a challenging target for the municipalities in the Po Valley, because of the characteristic climatic conditions and high population density of this region. In order to assess climatology and trends in the concentration of atmospheric particles in the Po Valley, a dataset of PM10 data from 41 sites across the Po Valley have been analysed, including both traffic and background sites (either urban, suburban or rural). Of these 41 sites, 18 with 10 yr or longer record have been analysed for long term trend in de-seasonalized monthly means, in annual quantiles and in monthly frequency distribution. A widespread significant decreasing trend has been observed at most sites, up to few percent per year, by Generalised Least Square and Theil-Sen method. All 41 sites have been tested for significant weekly periodicity by Kruskal-Wallis test for mean anomalies and by Wilcoxon test for weekend effect magnitude. A significant weekly periodicity has been observed for most PM10 series, particularly in summer and ascribed mainly to anthropic particulate emissions. A cluster analysis has been applied in order to highlight stations sharing similar pollution conditions over the reference period. Five clusters have been found, two gathering the metropolitan areas of Torino and Milano and their respective nearby sites and the other three clusters gathering north-east, north-west and central Po Valley sites respectively. Finally the observed trends in atmospheric PM10 have been compared to trends in provincial emissions of particulates and PM precursors, and analysed along with data on vehicular fleet age, composition and fuel sales. Significant basin-wide drop in emissions occurred for gaseous pollutants, contrarily to emissions of PM10 and PM2.5, whose drop resulted low and restricted to few provinces. It is not clear whether the decrease for only gaseous emissions is sufficient to explain the

  14. Perception of Blended Learning Inventory (PoBLi)

    DEFF Research Database (Denmark)

    Lassesen, Berit; Stenalt, Maria Hvid; Rossen, Dorte Sidelmann

    -to-face med online læring (Blended Learning). I et studie fandt Ellis og kolleger (2006), at undervisere, der overvejende havde opfattelsen af, at de studerende lærte ved, at han/hun formidlede viden til dem, havde en simpel, fragmenteret opfattelse af potentialet ved BL. Derimod syntes en mere......) underviseres oplevelse af undervisningsmiljøet Resultater: Spørgeskema og resultaterne af de foreløbige analyser vil blive præsenteret og diskuteret. Perspektiver: PoBLi-projektet vil bidrage til den eksisterende forskning vedrørende rationalet for inddragelse af blended learning-formatet i...

  15. The poços de caldas project

    CERN Document Server

    Chapman, NA; Shea, ME; Smellie, JAT

    1993-01-01

    The safe disposal of radioactive wastes by burial in deep geological formations requires long-term predictions of the future behaviour of the wastes and their engineered repository. Such predictions can be tested by evaluating processes analogous to those which will occur in a repository, which have been long active in the natural geochemical environment. The Poços de Caldas Project is a comprehensive study of two ore deposits in Minas Gerais, Brazil, aimed at looking at uranium and thorium series radionuclide and rare-earth element mobility, the development and movement of redox fronts, and

  16. Mobility of 232Th and 210Po in red mud.

    Science.gov (United States)

    Hegedűs, Miklós; Tóth-Bodrogi, Edit; Jónás, Jácint; Somlai, János; Kovács, Tibor

    2018-04-01

    The valorization of industrial by-products such as red mud became a tempting opportunity, but the understanding of the risks involved is required for the safe utilization of these products. One of the risks involved are the elevated levels of radionuclides (in the 100-1300 Bq/kg range for both the 238 U and 232  Th decay chains, but usually lower than 1000 Bq/kg, which is the recommended limit for excemption or clearance according to the EU BSS released in 2013) in red mud that can affect human health. There is no satisfactory answer for the utilization of red mud; the main current solution is still almost exclusively disposal into a landfill. For the safe utilization and deposition of red mud, it is important to be able to assess the leaching behaviour of radionuclides. Because there is no commonly accepted measurement protocol for testing the leaching of radionuclides in the EU a combined measurement protocol was made and tested based on heavy metal leaching methods. The leaching features of red mud were studied by methods compliant with the MSZ-21470-50 Hungarian standard, the CEN/TS 14429 standard and the Tessier sequential extraction method for 232 Th and 210 Po. The leached solutions were taken to radiochemical separation followed by spontaneous deposition for Po and electrodeposition for Th. The 332 ± 33 Bq/kg 232 Th content was minimally mobile, 1% became available for distilled water 1% and 6% for Lakanen-Erviö solution; the Tessier extraction showed minimal mobility in the first four steps, while more than 85% remained in the residue. The 210 Po measurements had a severe disturbing effect in many cases, probably due to large amounts of iron present in the red mud, from the 310 ± 12 Bq/kg by aqua regia digestion, distilled water mobilized 23%, while Lakanen-Erviö solution mobilized ∼13%. The proposed protocol is suitable for the analysis of Th and Po leaching behaviour. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Pedagogia como Gesto Poético de Linguagem

    OpenAIRE

    Richter,Sandra Regina Simonis; Berle,Simone

    2015-01-01

    Resumo:O ensaio aborda a relação entre experiência de linguagem e imaginação poética a partir das reflexões de Agamben, Merleau-Ponty e Bachelard como estratégia para tensionar o problema da descontinuidade temporal que tece a alteridade linguageira dos encontros entre crianças pequenas e adultos. Reivindica a compreensão pedagógica de que é interagindo poeticamente com o mundo, desencadeando tempos de presença e assumindo tentativas de plasmar sentidos singulares no coletivo, e não dele dist...

  18. Mis primeros Clásicos Poéticos

    OpenAIRE

    Gómez Yebra, Antonio Agustín

    2015-01-01

    A partir de indagar sobre la memoria y los recuerdos, el profesor y escritor Antonio A. Gómez Yebra ofrece un recorrido de situaciones, emociones, anécdotas y experiencias con la lectura y la literatura desde sus primeros años escolares, volviendo la mirada hacia la escuela de antaño de la mano de evocaciones literarias de poemas, cuentos, novelas, ensayos, etc., de los principales autores y autoras que configuraron su poética, destacando también, a modo de homenaje, a las maestras, profes...

  19. Investigations of the potential bioavailability of 210Po in some foodstuffs

    International Nuclear Information System (INIS)

    Bulman, Robert A.; Ewers, Leon W.; Matsumoto, Kiyoshi

    1995-01-01

    Extraction of 210 Po from lamb's liver, pig's kidneys, mussel flesh and brown crabmeat with a series of solvent systems has been used to gain some insight into the uncertainty about the gastrointestinal absorption factor for Po incorporated into foodstuffs. By extracting the tissues with diethyldithiocarbamate dissolved in chloroform, and also in methanol, it has been shown that 210 Po is more effectively extracted from lamb's liver and crabmeat than it is from each of the other tissues. A similar pattern of extractability is also evident for aqueous solutions of citric acid on crabmeat and mussel flesh. Of particular note is the low extractability by dimethylsulphoxide (3%) of 210 Po in mussel flesh as opposed to 24% extractability of 210 Po from crabmeat. 210 Po-binding macromolecules of about 10 kDa have been released from crabmeat and mussel flesh by digestion with pepsin

  20. Nuclear orientation and NMR/ON of sup(205,207)Po

    International Nuclear Information System (INIS)

    Herzog, P.; Walitzki, H.; Freitag, K.; Hildebrand, H.; Schloesser, K.

    1983-01-01

    sup(205,207)Po have been implanted with an isotope separator on-line into cold host matrices of Fe, Ni, Zn and Be. Nuclear magnetic resonance of oriented 207 Po has been observed in Fe and Ni, of 205 Po in Fe. From the dependence of the resonance frequency on external magnetic field the g-factor of 207 Po was derived. Using this value the magnetic hyperfine fields of Po in Fe and Ni were obtained. From the temperature dependence of the anisotropies of #betta#-lines in the decay of sup(205,207)Po the multipole mixing of several transitions was derived. The electric interaction frequencies #betta#sub(Q)=eQVsub(zz)/h in the hosts Zn and Be were measured. (orig./WL)

  1. The subcellular localization of natural 210Po in the hepatopancreas of the rock lobster (Jasus lalandii)

    International Nuclear Information System (INIS)

    Heyraud, M.; Dowdle, E.B.; Cherry, R.D.

    1987-01-01

    The subcellular localization of the naturally occurring nuclide 210 Po in the hepatopancreas of the South African rock lobster, Jasus lalandii, has been studied using centrifugation, ultrafiltration and chromatography. Just over half of the 210 Po was found to be associated with a component in the microsomal pellet. Most of the 210 Po was tightly bound to a component of high molecular mass. Dissociation of the 210 Po from this component required incubation with sulphydryl-reducing reagents, after which the 210 Po appeared to associate with a fraction having a molecular mass of 1500 daltons or less. A search for negatively-charged, hydrophobic, sulphur-containing membrane proteins which bind 210 Po is suggested. (author)

  2. The size distribution of 210Po in the atmosphere around Mt. Sakurajima in Kagoshima prefecture, Japan

    International Nuclear Information System (INIS)

    Ashikawa, N.; Matsuoka, N.; Takashima, Y.; Syojo, N.; Imamura, H.; Fujisaki, M.

    1998-01-01

    The concentration and size distribution of 210 Po in particulate matters in the atmosphere were measured around the active volcano, Mt. Sakurajima in Kagoshima prefecture, Japan. The samples were collected eight times at four sampling points for the period from June 1994 to January 1996. The highest concentration of 210 Po was 2940 μBq/m 3 at Akamizu located 2 km away from the crater of Mt. Sakurajima. The 210 Po concentrations decreased with the increase of distance form Mt. Sakurajima. The size distribution curves of 210 Po in the particulate matters showed that 210 Po is usually condensed to fine particles smaller than 2 μm in diameter. In addition, it was suggested that the 210 Po concentration in particulate matters collected at Akamizu was affected by the wind direction over Mt. Sakurajima. (author)

  3. pO2 and regional blood flow in a rabbit model of limb ischemia.

    Science.gov (United States)

    Grinberg, Oleg Y; Hou, Huagang; Grinberg, Stalina A; Moodie, Karen L; Demidenko, Eugene; Friedman, Bruce J; Post, Mark J; Swartz, Harold M

    2004-06-01

    Oxygen tension (pO2) in muscles and regional blood flow were measured in a rabbit model of limb ischemia. pO2 was measured repetitively by EPR oximetry with EMS char in four different muscle groups in the same animals. Blood flow in the same muscles at several time points was measured using microspheres. A linear mixed effects model was developed to analyze the data on pO2 and blood flow. The results suggest that while under normal conditions pO2 in muscles does not depend significantly on blood flow, immediately after arterial occlusion pO2 correlates linearly with blood flow. Within two weeks of occlusion the pO2 is recovered to 45% of baseline. This study demonstrates, for the first time, the applicability of EPR oximetry in animals larger than rodents.

  4. Low collectivity of the first 2+ states of 212,210Po

    Science.gov (United States)

    Kocheva, D.; Rainovski, G.; Jolie, J.; Pietralla, N.; Blazhev, A.; Astier, A.; Altenkirch, R.; Bast, M.; Beckers, M.; Ansari, S.; Braunroth, Th.; Cappellazzo, M.; Cortés, M. L.; Dewald, A.; Diel, F.; Djongolov, M.; Fransen, C.; Gladnishki, K.; Goldkuhle, A.; Hennig, A.; Karayonchev, V.; Keatings, J. M.; Kluge, E.; Kröll, Th.; Litzinger, J.; Moschner, K.; Müller-Gatermann, C.; Petkov, P.; Rudigier, M.; Scheck, M.; Spagnoletti, P.; Scholz, Ph.; Schmidt, T.; Spieker, M.; Stahl, C.; Stegmann, R.; Stolz, A.; Vogt, A.; Stoyanova, M.; Thöle, P.; Warr, N.; Werner, V.; Witt, W.; Wölk, D.; Zamora, J. C.; Zell, K. O.; Van Isacker, P.; Ponomarev, V. Yu.

    2018-05-01

    The lifetimes of the first 2+ excited states of 212,210Po were measured in two transfer reactions 208Pb(12C,8Be)212Po and 208Pb(12C,10Be)210Po by the Recoil Distance Doppler Shift (RDDS) method and by the Doppler Shift Attenuation method (DSAM), respectively. The derived absolute B(E2) values of 2.6(3) W.u. for 212Po and 1.83(28) W.u. for 210Po indicate low collectivity. It is shown that the properties of the yrast {2}1+, {4}1+, {6}1+ and {8}1+ states in both nuclei cannot be described consistently in the framework of nuclear shell models. It is also demonstrated in the case of 210Po that Quasi-particle Phonon Model (QPM) calculations cannot overcome this problem thus indicating the existence of a peculiarity which is neglected in both theoretical approaches.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. -- Highlights: • We analyzed the distribution of 210 Po in two species of predator marine fish. • 210 Po tends to accumulate in some organs, which make this radionuclide radiotoxic. • The consumption of small quantities of fish can represent high potential of 210 Po exposure. • Data about 210 Po bioaccumulation in tropical predator marine fish are limited

  6. Subcellular localization of natural /sup 210/Po in the hepatopancreas of the rock lobster (Jasus lalandii)

    Energy Technology Data Exchange (ETDEWEB)

    Heyraud, M; Dowdle, E B; Cherry, R D

    1987-01-01

    The subcellular localization of the naturally occurring nuclide /sup 210/Po in the hepatopancreas of the South African rock lobster, Jasus lalandii, has been studied using centrifugation, ultrafiltration and chromatography. Just over half of the /sup 210/Po was found to be associated with a component in the microsomal pellet. Most of the /sup 210/Po was tightly bound to a component of high molecular mass. Dissociation of the /sup 210/Po from this component required incubation with sulphydryl-reducing reagents, after which the /sup 210/Po appeared to associate with a fraction having a molecular mass of 1500 daltons or less. A search for negatively-charged, hydrophobic, sulphur-containing membrane proteins which bind /sup 210/Po is suggested.

  7. Analysis of 210Pb and 210Po concentrations in surface air by an α spectrometric method

    International Nuclear Information System (INIS)

    Winkler, R.; Hoetzl, H.; Chatterjee, B.

    1981-01-01

    A method is presented for determining the concentrations of airborne 210 Pb and 210 Po. The method employs α spectrometry to measure the count rate of 210 Po present on an electrostatic filter sample at two post-sampling times. The individual air concentrations of 210 Po and 210 Pb can be calculated from equations given. Sensitivity of the procedure is about 0.2 fCi 210 Po per m 3 of air. The method was applied to the study of long-term variations and frequency distributions of 210 Po and 210 Pb concentrations in surface air at a nonpolluted location about 10 km outside of Munich, F.R.G., from 1976 through 1979. During this period the average concentration levels were found to be 14.2 fCi 210 Pb per m 3 of air and 0.77 fCi 210 Po per m 3 of air, respectively. (author)

  8. Study of 210Po and 210Pb in the riverine environments of coastal Karnataka

    International Nuclear Information System (INIS)

    Narayana, Y.; Rajashekara, K.M.

    2010-01-01

    Activity of 210 Po and 210 Pb were measured in soil and sediment samples collected from the major rivers Kali, Sharavathi and Netravathi of Coastal Karnataka. The activity of these two radionuclides were determined by radiochemical separation of 210 Po and counting the activity using a ZnS(Ag) Alpha counter. The activity of 210 Pb was higher than that of 210 Po in the riverine environs. The 210 Po and 210 Pb content in sediment was found to increase with silt/clay and organic matter contents. However no significant correlation was found between the activity 210 Po and 210 Pb with pH in sediments. The activity of 210 Po and 210 Pb and influence of physico-chemical parameters on these radionuclides were studied and discussed in this paper.

  9. A radiochemical procedure for the determination of Po-210 in environmental samples

    International Nuclear Information System (INIS)

    Godoy, J.M.; Schuettelkopf, H.

    1980-07-01

    A radiochemical procedure for the determination of Po-210 in environmental samples was developed. Soil, sediments, filter materials, plants, water and food samples can be analyzed for Po-210. Wet ashing is achieved with HNO 3 + H 2 O 2 or HCl + HNO 3 . To separate disturbing substances, a coprecipitation with Te is used for sample materials containing silica. Po-210 deposition from HCl solution on Ag platelets with other sample materials is possible directly. Deposited Po-210 is counted by α-spectrometry. For chemical yield determination Po-208 is added, yields range between 60% and 100%. A lower detection limit of about 0,002 pCi Po-210/sample is achievable. (orig./HP) [de

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. A simulation study on the topotactic transformations from aluminophosphate AlPO(4)-21 to AlPO(4)-25.

    Science.gov (United States)

    Li, J; Yu, J; Wang, K; Zhu, G; Xu, R

    2001-11-05

    Aluminophosphate AlPO(4)-21 (AWO), formulated /(CH(3))(2)NH(2)/[Al(3)P(3)O(12)(OH)], has been synthesized solvothermally by using dimethylamine as the template. Single-crystal X-ray diffraction analysis shows that AlPO(4)-21 crystallizes in the monoclinic space group P2(1)/n with a = 8.687(2) A, b = 17.428(5) A, c = 9.159(2) A, beta = 109.60(2) degrees, V = 1306.3(5) A(3), and Z = 4. XRD analysis shows that AlPO(4)-21 transforms to AlPO(4)-25 (ATV) upon calcination at 500 degrees C. The molecular dynamics simulation approach was used to investigate the topotactic transformations from AlPO(4)-21. The simulation study suggests that AlPO(4)-21 is energetically favored to transform to AlPO(4)-25, as well as other hypothetical forms, by the changing of the UUDD chains to the UDUD chains.

  12. 210Po and 210Pb variations in fish species from the Aegean Sea and the contribution of 210Po to the radiation dose

    International Nuclear Information System (INIS)

    Mat Çatal, Ebru; Uğur, Aysun; Özden, Banu; Filizok, Işık

    2012-01-01

    In recent years, there has been increasing interest in the significance of natural radionuclides, particularly 210 Po, in the marine environment. 210 Po, a naturally occurring alpha emitter, accumulates in marine organisms and reflects differences in their diets. In the literature, there is no data for 210 Po and 210 Pb activity concentrations for fish species on the Turkish coast of Aegean Sea. Therefore, in this study, multiple fish species were collected from six stations seasonally on the Turkish coast of Aegean Sea and were analyzed for their 210 Po and 210 Pb content. The 210 Po and 210 Pb concentrations in the fish samples were found to vary from undetectable levels to 499 ± 44 Bq kg −1 dry weight (dw) and from 1.0 ± 0.3 Bq kg −1 to 35 ± 4.0 Bq kg −1 (dw), respectively. There were no significant differences in the activity concentrations of 210 Po and 210 Pb in fish samples between seasons (ANOVA, P > 0.05). The highest dose contribution of 210 Po to humans was calculated to be 10,530 μSv year −1 .

  13. Diversity in growth and expression pattern of PoHKT1 and PoVHA transporter genes under NaCl stress in Portulaca oleracea taxa

    Directory of Open Access Journals (Sweden)

    El-Bakatoushi R.

    2016-01-01

    Full Text Available Plant growth and the expression of two transporter genes; PoHKT1 and PoVHA transcripts in root and shoot tissues were studied under salt stress of three Portulaca oleracea s.l. taxa. The study showed no significant differences in ratios between root lengths in saline and non-saline treatments of the three taxa, which was correlated with a clear down-regulation of the PoHKT1 transcripts in the root after 150mM NaCl. All measured growth parameters except root length increased in P. oleraceae, decreased in P. granulatostellulata and remain unchanged after 100mM NaCl in P. nitida compared to control under saline conditions. The result was consistent with the type of taxon which had significant effect on the shoot length, number of leaves and dry weight (P< 0.05. All measured growth parameters except root length showed a significant negative correlation with the shoot fold change of PoHKT1 transcripts (r = -0.607, -0.693 and -0.657 respectively. The regulation of PoVHA in root and shoot tissues in the three taxa are significantly different. Under salt stress, both decreased uptake of Na+ into the cytosol by decreasing the expression of PoHKT1 and increased vascular compartmentalization ability of Na+ by inducing the expression of PoVHA seem to work more efficiently in P. oleraceae and P. nitida than in P. granulato-stellulata.

  14. Temporal annual changes of 210Po concentrations in coastal seawater at Kyushu Island

    International Nuclear Information System (INIS)

    Tolmachyov, S.; Maeda, Y.; Momoshima, N.

    2001-01-01

    Polonium-210 ( 210 Po, T 1/2 =138.4 d) arises from the decay of 210 Pb (T 1/2 =22.3 yr) via intermediary 210 Bi (T 1/2 =5.03 d). Virtually, all of 210 Po in seawater is originated by in situ decay of 210 Pb, which in turn originated due to in situ decay of 226 Ra, and decay of 222 Rn in the sea and in the atmosphere followed by deposition. In seawater, 210 Po is considered an insoluble element, therefore the concentration of dissolved 210 Po is very low. The concentration levels of 210 Po in marine environmental samples are well documented, however, scanty information is available about long-scale 210 Po behavior in open oceans and/or coastal seawater. Few studies have quantified temporal variation of 210 Po concentrations with relation to environmental parameters and seasonality. Nevertheless, seasonal detail allows us to make inferences about what geochemical parameters can effected on 210 Po behavior in the marine environment that will obviously improve our present understanding of the rates and mechanisms of 210 Po scavenging from seawater column. This paper presents the results of annual observation of 210 Po concentration in the coastal seawater at Kyushu Island (Japan). Besides the 210 Po concentrations, concentration of Chlorophyll-a (Chl-a), which is generally used as an indicator of plankton activity, fluctuations of loaded suspended particulate matter (SPM) concentration (C p ) and monthly rainfall collected at the place close to the sampling area were examined to confirm if their behavior mirrors that of 210 Po. (author)

  15. Contemporary young users to retrain the wetlands and industrial/port archeology of Boretto Po

    OpenAIRE

    Visentin, Chiara

    2010-01-01

    Repopulate a place means helping the existing inhabitants to stop the slow decline and forgetfulness of his past. The instance of Boretto Po is emblematic. Boretto, along with Brescello, Gualtieri, Guastalla and Luzzara, is part of five urban areas of Reggio Emilia district, at the site of the middle Po river, between the exit of the Enza and the Oglio. The close coexistence of the inhabitants of Boretto with Po has seen a series of crafts and activities now completely abandone...

  16. Crystal structure of Na3Sc2(PO4)3 at 60 deg C

    International Nuclear Information System (INIS)

    Lazoryak, B.I.; Kalinin, V.B.; Stefanovich, S.Yu.; Efremov, V.A.

    1980-01-01

    The structure of the ferroelectric phase of Na 3 Sc 2 (PO 4 ) 3 compound was studied. Na 3 Sc 2 (PO 4 ) 3 monocrystal heated by a jet of warm N 2 was investigated at 60 deg C. The rhombohedron modification was determined: a=8.927(3), c=22.34(4) A, Z=6, space group R anti 3c. Interatomic distances and inner angles of polyhedrons in Na 3 Sc 2 (PO 4 ) 3 structure were determined

  17. Synthesis and vibrational spectrum of antimony phosphate, SbPO4.

    Science.gov (United States)

    Brockner, Wolfgang; Hoyer, Lars P

    2002-07-01

    SbPO4 was synthesized via a new route by reacting antimony metal with meta-phosphoric acid, (HPO3)n at high temperatures. The Raman and IR spectra of the title compound were recorded and the vibrational modes assigned on the basis of a factor group analysis. The internal vibrations are derived from tetrahedral PO4 units (approaching Sb[PO4]) by the correlation method, although the structure is polymeric and not ionic.

  18. Occurrence of 210Po and Biological Effects of Low-Level Exposure: The Need for Research

    OpenAIRE

    Seiler, Ralph L.; 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, bioki...

  19. Spectroscopy of high-spin states of 206Po

    International Nuclear Information System (INIS)

    Baxter, A.M.; Byrne, A.P.; Dracoulis, G.D.; Bark, R.A.; Riess, F.; Stuchbery, A.E.; Kruse, M.C.; Poletti, A.R.

    1990-05-01

    The yrast and near-yrast energy levels of 206 Po have been investigated to over 9 MeV excitation and up to spins with J=24. The measure-ments consisted of γ-γ coincidence data, internal-conversion-electron spectra, time spectra of γ-rays relative to a pulsed beam, excitation functions and γ-ray angular distributions. Two new isomers, with lifetime in the one-nonasecond range,were found. The observed structure is compared with the predictions of empirical shell-model calculations in which 206 Po is regarded as a 208 Pb core with two valence protons and four valence neutron holes. The agreement is generaly satisfactory for the observed odd-parity levels and for even parity levels with J > 12; those with J = 6 to 12 are better accounted for by weak coupling of two valence protons to a 204 Pb core in its 0 + 1, 2 + 1 and 4 + 1 states. 33 refs., 7 tabs., 12 figs

  20. PoPSat: The Polar Precipitation Satellite Mission

    Science.gov (United States)

    Binder, Matthias J.; Agten, Dries; Arago-Higueras, Nadia; Borderies, Mary; Diaz-Schümmer, Carlos; Jamali, Maryam; Jimenez-Lluva, David; Kiefer, Joshua; Larsson, Anna; Lopez-Gilabert, Lola; Mione, Michele; Mould, Toby JD; Pavesi, Sara; Roth, Georg; Tomicic, Maja

    2017-04-01

    The terrestrial water cycle is one of many unique regulatory systems on planet Earth. It is directly responsible for sustaining biological life on land and human populations by ensuring sustained crop yields. However, this delicate balanced system continues to be influenced significantly by a changing climate, which has had drastic impacts particularly on the polar regions. Precipitation is a key process in the weather and climate system, due to its storage, transport and release of latent heat in the atmosphere. It has been extensively investigated in low latitudes, in which detailed models have been established for weather prediction. However, a gap has been left in higher latitudes above 65°, which show the strongest response to climate changes and where increasing precipitations have been foreseen in the future. In order to establish a global perspective of atmospheric processes, space observation of high-latitude areas is crucial to produce globally consistent data. The increasing demand for those data has driven a critical need to devise a mission which fills the gaps in current climate models. The authors propose the Polar Precipitation Satellite (PoPSat), an innovative satellite mission to provide enhanced observation of light and medium precipitation, focusing on snowfall and light rain in high latitudes. PoPSat is the first mission aimed to provide high resolution 3D structural information about snow and light precipitation systems and cloud structure in the covered areas. The satellite is equipped with a dual band (Ka and W band) phased-array radar. These antennas provide a horizontal resolution of 2 km and 4 km respectively which will exceed all other observations made to date at high-latitudes, while providing the additional capability to monitor snowfall. The data gathered will be compatible and complementary with measurements made during previous missions. PoPSat has been designed to fly on a sun-synchronous, dawn-dusk orbit at 460 km. This orbit

  1. Radiation poisoning with Po-210 in London: The medical implications

    International Nuclear Information System (INIS)

    Perkins, A.C.

    2007-01-01

    Full text: The death of Alexander Litvinenko on 23 November 2006 has elevated the prospect of a deliberate radiation poisoning from a theoretical possibility to a reality. This was an unprecedented event in the UK. Poison that was certainly not the work of an amateur assassin was found, and it is possible that there have been previous killings of this nature outside the UK. Po-210 is a highly toxic radioactive heavy metal with a half-life of 138 days that decays, giving off 5.3MeV alpha particles having a range of 40-50mm in tissue. The poison was probably administered in a small volume of liquid or as a solid powder added to food or drink. Dispersal of the material resulted in widespread contamination that was detected across London and on British Airways' flights to the east. Following the event, the main task of the UK Health Protection Agency was of contamination monitoring and reassurance of the general public. With many researchers now investigating the use of targeted alpha therapy, this incident has highlighted the possible effects from the uptake of alpha emitters into the sensitive normal tissues. On reaching the bloodstream, Po- 210 is rapidly deposited in major organs and tissues including the liver, kidneys and bone marrow. The intense alpha radiation within these tissues would result in massive destruction of cells, leading to a rapid decline in health. It has been concluded that ingestion of 1-3 GBq or greater of Po-210 is likely to result in death within a few weeks, assuming there is 10% absorption to blood. Anyone receiving such doses would show symptoms of acute radiation sickness syndrome, with death resulting from multiple organ failure. Remedial medical treatment strategies would be unsuccessful within a few hours of ingestion, once significant amounts of Po-210 had entered the blood stream and deposited in tissues. The surreptitious nature of this act almost escaped detection. The fact that the nature of the poison was not known until the

  2. Annual effective dose of {sup 210}Po from sea food origin (Oysters and Mussels) in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Bo Eum; Hong, Gi Hoon; Kim, Suk Hyun; Lee, Hyun Mi [Korea Institute of Ocean Science and Technology, Ansan (Korea, Republic of)

    2016-09-15

    Ingestion of {sup 210}Po laden seafood accounts for a substantial amount of the effective dose of {sup 210}Po. Among seafood items, mollusks, especially domestically produced oysters and mussels, are highly enriched in {sup 210}Po and are consumed in large quantities in Korea. Oysters and mussels around the Korean coasts were collected from major farm areas in November 2013. Samples were spiked with an aliquot of {sup 210}Po as a yield tracer, and they were digested with 6 mol·L{sup -1} HNO{sub 3} and H{sub 2}O{sub 2}. The {sup 210}Po and {sup 209}Po were spontaneously deposited onto a silver disc in an acidic solution of 0.5 mol·L{sup -1} HCl and measured using an alpha spectrometer. The activity concentrations of {sup 210}Pb and {sup 210}Po were decay corrected to the sampling date, accounting for the possible in-growth and decay of {sup 210}Po. {sup 210}Po activity concentrations in oysters were in a range from 41.3 to 206 Bq·(kg-ww{sup -1} and mussels in a range from 42.9 to 46.7 Bq·(kg-ww){sup -1}. The {sup 210}Po activity concentration of oysters in the turbid Western coast was higher than the Southern coast. The {sup 210}Po activity concentration of the oysters was positively correlated (R2=0.89) with those of the suspended particulate matter in the surface water. The calculated annual effective dose of {sup 210}Po from oysters and mussels consumed by the Korean population was 21-104 and 5.01-5.46 μSv·y{sup -1}. The combined effective dose due to the consumption of oysters and mussels appears to account for about 35±19% of that arising from seafood consumption in the Korean population. The annual effective dose of {sup 210}Po for oysters in the Korean population was found to be higher than other countries. The total annual effective dose of 210Po{sup 210}Po due to consumption of oysters and mussels consumed in Korea was found to be 76±42 μSv·y{sup -1}, accounting for 28±16% of the total effective dose of {sup 210}Po from food in Korea.

  3. Origin of Activity and Stability Enhancement for Ag3PO4 Photocatalyst after Calcination

    Directory of Open Access Journals (Sweden)

    Pengyu Dong

    2016-11-01

    Full Text Available Pristine Ag3PO4 microspheres were synthesized by a co-precipitation method, followed by being calcined at different temperatures to obtain a series of calcined Ag3PO4 photocatalysts. This work aims to investigate the origin of activity and stability enhancement for Ag3PO4 photocatalyst after calcination based on the systematical analyses of the structures, morphologies, chemical states of elements, oxygen defects, optical absorption properties, separation and transfer of photogenerated electron-hole pairs, and active species. The results indicate that oxygen vacancies (VO˙˙ are created and metallic silver nanoparticles (Ag NPs are formed by the reaction of partial Ag+ in Ag3PO4 semiconductor with the thermally excited electrons from Ag3PO4 and then deposited on the surface of Ag3PO4 microspheres during the calcination process. Among the calcined Ag3PO4 samples, the Ag3PO4-200 sample exhibits the best photocatalytic activity and greatly enhanced photocatalytic stability for photodegradation of methylene blue (MB solution under visible light irradiation. Oxygen vacancies play a significantly positive role in the enhancement of photocatalytic activity, while metallic Ag has a very important effect on improving the photocatalytic stability. Overall, the present work provides some powerful evidences and a deep understanding on the origin of activity and stability enhancement for the Ag3PO4 photocatalyst after calcination.

  4. Determination and distribution of 210Po in tobacco plants from Poland

    International Nuclear Information System (INIS)

    Skwarzec, B.; Struminska, D.I.; Ulatowski, J.; Golebiowski, M.

    2001-01-01

    One of the most radiotoxic elements, 210 Po in different parts of tobacco plant from Poland was determined. Investigation revealed that polonium is non-uniformly distributed within tobacco plant. Tobacco leaves constituting about 50% of the wet mass, contain 87.1% of the total burden of 210 Po. Among the analyzed leaves about 66% of polonium is located in the oldest, over-ground part. It was indicated that 210 Po is generally taken up by tobacco from the dry or wet deposition of the radioactive fall-out onto the plant. Moreover, 210 Po concentration in tobacco leaves from Poland are higher than that in the other countries. (author)

  5. Annual effective dose of 210Po from sea food origin (Oysters and Mussels) in Korea

    International Nuclear Information System (INIS)

    Cho, Bo Eum; Hong, Gi Hoon; Kim, Suk Hyun; Lee, Hyun Mi

    2016-01-01

    Ingestion of 210 Po laden seafood accounts for a substantial amount of the effective dose of 210 Po. Among seafood items, mollusks, especially domestically produced oysters and mussels, are highly enriched in 210 Po and are consumed in large quantities in Korea. Oysters and mussels around the Korean coasts were collected from major farm areas in November 2013. Samples were spiked with an aliquot of 210 Po as a yield tracer, and they were digested with 6 mol·L -1 HNO 3 and H 2 O 2 . The 210 Po and 209 Po were spontaneously deposited onto a silver disc in an acidic solution of 0.5 mol·L -1 HCl and measured using an alpha spectrometer. The activity concentrations of 210 Pb and 210 Po were decay corrected to the sampling date, accounting for the possible in-growth and decay of 210 Po. 210 Po activity concentrations in oysters were in a range from 41.3 to 206 Bq·(kg-ww -1 and mussels in a range from 42.9 to 46.7 Bq·(kg-ww) -1 . The 210 Po activity concentration of oysters in the turbid Western coast was higher than the Southern coast. The 210 Po activity concentration of the oysters was positively correlated (R2=0.89) with those of the suspended particulate matter in the surface water. The calculated annual effective dose of 210 Po from oysters and mussels consumed by the Korean population was 21-104 and 5.01-5.46 μSv·y -1 . The combined effective dose due to the consumption of oysters and mussels appears to account for about 35±19% of that arising from seafood consumption in the Korean population. The annual effective dose of 210 Po for oysters in the Korean population was found to be higher than other countries. The total annual effective dose of 210Po 210 Po due to consumption of oysters and mussels consumed in Korea was found to be 76±42 μSv·y -1 , accounting for 28±16% of the total effective dose of 210 Po from food in Korea

  6. 210Po and 210Pb in Forest Soil and in Wild Berries in Finland

    International Nuclear Information System (INIS)

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

    2008-01-01

    The behaviour of 210 Po and 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 210 Po and 210 Pb in soil columns were found in organic layers. According to preliminary results of wild berry samples, the lowest 210 Po concentrations were found in berries. The highest concentration of 210 Po was found in stems of the blueberry (Vaccinium myrtillus) and the lingonberry (Vaccinium vitis-idaea) samples

  7. Phase equilibria in the system Nd(PO3)3 - KPO3

    International Nuclear Information System (INIS)

    Znamierowska, T.; Mizer, D.

    2002-01-01

    The system Nd(PO 3 ) 3 - KPO 3 has been investigated by differential thermal analysis (during heating), thermogravimetric analysis, mass spectrometry, Raman spectroscopy and X-ray powder diffraction and its phase diagram was proposed. It was discovered that initial metaphosphates react at a 1:1 molar ratio forming intermediate compound KNd(PO 3 ) 4 . It was found that it melts incongruently at 854 o C giving Nd(po)3) 3 and a liquid rich in KPO 3 . Phosphate KNd(PO 3 ) 4 is stable down to room temperature and does not show any polymorphic transitions. (author)

  8. Dependence of 210Po activity on organic matter in the reverine environs of coastal Kerala

    International Nuclear Information System (INIS)

    Narayana, Y.; Venunathan, N.

    2011-01-01

    This paper deals with the distribution of 210 Po in the river bank soil samples of three major rivers namely Bharathapuzha, Periyar and Kallada river of Kerala. The dependence of 210 Po activity on organic matter content in the samples was also studied. The soil samples were collected and analyzed for 210 Po radionuclide using standard radiochemical analytical method. Activity of 210 Po increases with increase in organic matter content in samples. Along the Bharathapuzha river bank the 210 Po activity ranges from 2.96 to 12.48 Bq kg -1 with mean 5.62 Bq kg -1 . The organic matter percentage in the samples ranges from 0.4 to 2.8 and a good correlation with correlation coefficient 0.9 was found between activity and organic matter percentage. In the Periyar river environs 210 Po activity ranges from 3.47 to 13.39 Bq kg -1 with mean value 9.27 Bq kg -1 . Organic matter percentage in these samples ranges from 1.20 to 4.10 and the correlation coefficient between 210 Po activity and organic matter percentage was found to be 0.8 In the Kallada river bank soil samples 210 Po activity ranges from 4.46 to 6.45 Bq kg -1 . The organic matter percentage ranges from 1.4 to 3. The correlation coefficient between 210 Po activity and organic matter percentage in the samples was found to be 0.9. (author)

  9. Accumulation of /sup 210/Po in selected species of Baltic fish

    Energy Technology Data Exchange (ETDEWEB)

    Skwarzec, B

    1988-01-01

    Results are presented here for the /sup 210/Po contents of selected species of Baltic fish. It is shown that /sup 210/Po is non-uniformly distributed within these fish, the highest levels being found in the digestive organs, particularly within the intestine. It is found that the proportional contribution by the digestive organs to the total accumulation of /sup 210/Po is correlated with the degree of repletion of the stomach and that this decreases if food is lacking. Moreover, it is observed that fish represent an important source of supply of /sup 210/Po to humans.

  10. Degradation Studies on LiFePO4 cathode

    DEFF Research Database (Denmark)

    Scipioni, Roberto; Jørgensen, Peter Stanley; Hjelm, Johan

    2015-01-01

    In this paper we examine a laboratory LiFePO4 (LFP) cathode and propose a simple model that predicts the electrode capacity as function of C-rate, number of cycles and calendar time. Microcracks were found in Li1-xFePO4 particles in a degraded LFP electrode and low-acceleration voltage (1 kV) FIB....../SEM analysis allowed us to obtain phase contrast between FePO4 and LiFePO4. The evolution of micro-cracks is expected to increase the concentration of LFP particles which are not electronically accessible and thus cause a loss in capacity....

  11. Ion conductivity and phase transitions in the Na3Sc2(PO4)3 - NaGe2(PO4)3 system

    International Nuclear Information System (INIS)

    Nogaj, A.S.

    2002-01-01

    Influence of heteropolyvalent substitution on dipole ordering of sodium-scandium phosphate, as well as on ion conductivity and phase transitions in the system Na 3 Sc 2 (PO 4 ) 3 - NaGe 2 (PO 4 ) 3 , was studied using the methods of solid phase synthesis, X-ray diffraction, laser spectroscopy and measurement of electric conductivity. Boundaries of the dipole-ordered and superionic phases existence ranges in the given system were identified. It is shown that expansion of the dipole-ordered phase existence range with increase in substituent cation concentration is characteristic of the phase on the basis of α-Na 3 Sc 2 (PO 4 ) 3 [ru

  12. Comparative study of scintillation properties of RE doped NaPO3-Al(PO3)3 glasses

    International Nuclear Information System (INIS)

    Kuro, Tomoaki; Yanagida, Takayuki; Okada, Go; Fujimoto, Yutaka; Masai, Hirokazu

    2015-01-01

    We systematically investigated photoluminescence (PL), scintillation and dosimeter properties of rare-earth (RE) doped NaPO 3 -Al(PO 3 ) 3 (NAP) glasses. Ag-doped NAP glass is widely used for individual radiation dosimeter, however, there have been few reports on studies about NAP glasses when RE ions are doped as the luminescence center. The NAP glasses doped with 0.3 wt% RE (La∼Yb) were prepared by the conventional melt-quenching method. PL decay time and scintillation decay time profiles showed fast (ns) and slow (μs or ms) components: the fast components were from several tens to 100 ns due to the host emission or 5d-4f transition emission, and the slow component from few μs to few ms was caused by 4f-4f transition emission of RE 3+ . Thermally stimulated luminescence (TSL) was evaluated as a dosimeter property, and glow peaks appeared around 400degC in all the samples. The TSL dose response function was examined in the dose range from 10 mGy to 10 Gy, and good linearity was observed in RE-doped NAP glasses. (author)

  13. Baseline concentration of {sup 210}Po in Sargassum from the Northern Gulf

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, S.; Bebhehani, M.; Talebi, L. [Kuwait Institute for Scientific Research (Kuwait)

    2014-07-01

    The concentration of the {sup 210}Po is of enormous interest because of its large contribution to the natural radiation dose received by marine organisms and human populations consuming seafood. In fact natural {sup 210}Po is responsible for higher radiation doses to humans consuming marine products than is plutonium and other man-made radionuclides. Many marine organisms are capable of concentrating {sup 210}Po in their tissues. {sup 210}Po is an alpha emitter in the {sup 238}U series, with 138-d half-life, that is supplied to seawater from atmospheric inputs and river runoff, however, the main source of {sup 210}Po in the environment is {sup 222}Rn exhalation from the ground. Assessing the impact of radionuclides in the environment requires the establishment of baseline levels in the environmental compartments. The objective of this study was to establish baseline levels in Sargassum. Two most common species of Sargassum found in the northern Gulf were analysed for {sup 210}Po. These macro-algae were collected from three different locations during January 2013. This study sets the baseline for {sup 210}Po concentration in northern Gulf, {sup 210}Po is absorbed from water and concentrated by Phytoplankton and macro-algae. This concentrated {sup 210}Po can then be passed along to the next trophic level of the marine food web. The {sup 210}Po concentration measured in Sargassum boveanum (4.405 - 4.952 BqKg{sup -1}) was significantly higher (p>0.084) than Sargassum oligocystum (3.838 - 4.358 BqKg{sup -1}). The {sup 210}Po concentration in these seaweeds from the Arabian/Persian Gulf were substantially lower than those found in various Phytoplankton and macro-algae species from other regions; this may be due to the lower background {sup 210}Po concentration in the Kuwait marine waters (0.282 - 0.382 mBq l{sup -1}). The {sup 210}Po concentrations in seawater measured at the 3 stations during January 2013 were less than those reported previously from the same region

  14. 210Po content in human urine of people living in south of Spain

    International Nuclear Information System (INIS)

    Díaz-Francés, I.; García-Tenorio, R.; Mantero, J.; Manjón, G.

    2013-01-01

    The death of the former secret service agent Alexander Livitnenko in 2006 due to a lethal intake of 210 Po, presumably via ingestion, sparked renewed interest in the field of 210 Po toxicity to humans. 210 Po occurs widely in nature and is an important component of man' s natural radiation background. The main route of 210 Po intake by the human body is the ingestion with foodstuffs, although ingestion with drinking water especially of underground origin represents another route of 210 Po intakes. Inhalation of 222 Rn released from the soil also contributes in 210 Po body burden. However, the body burden of 210 Po in normal human body may differ from one person to another depending upon the mode life including diet habits, origin of drinking water, residence place (radon exposure rate) and also smoking habits. Therefore, many factors may affect the 210 Po intake and lead to variations in the body burden in different individuals, and consequently in their urine. To see the influence of the diet habits in the amount of 210 Po excreted by urine, some volunteers in Seville (south of Spain) follow defined diets during approximately one month, with daily urine collection followed by 210 Po determination by alpha-particle spectrometry. Depending on the type of diet ingested by the different volunteers, it was observed differences approaching even an order of magnitude in their levels of 210 Po in urine. This fact difficult enormously the adoption of a predefined value of this nuclide in urine with natural origin with the consequence difficulties for screening through urine the possible anthropogenic intake of this element. (author)

  15. [Experimental branch vein occlusion: the effect of carbogen breathing on preretinal PO2].

    Science.gov (United States)

    Pournaras, J-A C; Poitry, S; Munoz, J-L; Pournaras, C J

    2003-10-01

    To evaluate the variations in preretinal PO2 in normal and in ischemic postexperimental branch vein occlusion (BRVO) retinal areas during normoxia, hyperoxia (100% O2) and carbogen (95% O2, 5% CO2) breathing. Preretinal PO2 measurements were obtained in intervascular retinal areas far from the retinal vessels of 13 anesthetized miniature pigs with oxygen-sensitive microelectrodes (10 microm tip diameter) introduced through the vitreous cavity by a micromanipulator. The microelectrode tip was placed at 50 microm from the vitreoretinal interface in the preretinal vitreous. PO2 was measured continuously for 10 minutes in systemic normoxia, hyperoxia (100% O2 breathing) and carbogen (95% O2, 5% CO2) breathing. A BRVO was induced with an argon green laser, and oxygen measurements were repeated in normoxia, hyperoxia and carbogen breathing. In hyperoxia, preretinal PO2 remained almost constant in both normal retinas (DeltaPO2=1.33 mmHg +/- 3.39; n=13) and ischemic retinas (DeltaPO2=3.73 mmHg +/- 2.84; n=8), although systemic PaO2 significantly increased. Carbogen breathing induced a significant increase in systemic PaO2 and PaCO2. Furthermore, it significantly increased preretinal PO2: DeltaPO2=23.05 mmHg +/- 17.06 (n=12) in normal retinas, and DeltaPO2=22.54 mmHg +/- 5.96 (n=6) in ischemic retinal areas. Systemic hyperoxia does not increase preretinal PO2 significantly in normal and ischemic post-BRVO retinal areas of miniature pigs, as hyperoxia induces a decrease in the retinal blood flow. Carbogen breathing significantly increases preretinal PO2 in normal and in ischemic post-BRVO retinal areas. This effect is probably due to the vasodilatation of the retinal arterioles induced by the intravascular PaCO2 increase.

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

    Science.gov (United States)

    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.

  17. Variation of 210Po and 210Pb Profile in the Sediment Core of Sarawak Coastal Waters

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood; Che Abd Rahim Mohamed; Zaharudin Ahmad; Abdul Kadir Ishak

    2008-01-01

    This study was performed to observe the variation in the distribution of 210 Po and 210 Pb through their activity vertical profile and 210 Po/ 210 Pb activity ratio in the sediment cores that were taken at some sampling stations in the Sarawak coastal waters. It was found that the distribution profile of those radionuclide in the sediment cores varied depending on the sampling location and ANOVA analysis shows significant difference at 95% confidence level for activities of 210 Po (p = 0.000), 210 Pb (p = 0.035) and 210 Po/ 210 Pb (p = 0.000) at all study locations. Generally, the measured activity of 210 Po and 210 Pb ranged from 337 to 2460 Bq/ kg, 11 to 84 Bq/ kg at SR 01; 224 to 2008 Bq/ kg, 6 to 80 Bq/ kg at SR 02; 119 to 1595 Bq/ kg, 6 to 84 Bq/ kg at SR 03; 241 to 2294 Bq/ kg, 5 to 82 Bq/ kg at SR 04 and 175 to 1340 Bq/ kg, 4 to 44 Bq/ kg at SR 05, respectively. In those range it was found that 210 Po activities were higher than 210 Pb with average of 210 Po/ 210 Pb ratios at all stations were from 20 to 35. The variation in the distribution profile for the radionuclides are believed to be influenced by some environmental factors and have strong correlation between the radionuclide distribution and the sediment composition of silt ( 210 Po: r = 0.701 and 210 Pb: r = 0.648), water depth ( 210 Po: r = -0.647) and the distance from the sampling station to the main land ( 210 Po: r = 0.746 and 210 Pb: r = 0.975). Those factors are a major contributions on the variation of 210 Po and 210 Pb in the samples. (author)

  18. Synthesis, crystal structure and optical properties of the catena-metaphosphates Ce(PO3)4 and U(PO3)4

    International Nuclear Information System (INIS)

    Hoeppe, Henning A.; Daub, Michi

    2012-01-01

    The catena-metaphosphates of tetravalent cerium and tetravalent uranium were obtained as phase pure crystalline powders by reaction of the respective dioxides with phosphoric acid at 500 C. Ce(PO 3 ) 4 and U(PO 3 ) 4 crystallise in space group C2/c (Z = 16, a Ce = 13.7696(3) Aa, b Ce = 29.7120(7) Aa, c Ce = 8.9269(2) Aa, β Ce = 90.00(1) Aa 3 and a U = 13.786(3) Aa, b U = 29.843(6) Aa, c U = 8.9720(18) Aa, β U = 90.01(3) Aa 3 ). The vibrational and optical spectra of pale yellow Ce(PO 3 ) 4 and emerald-greenish U(PO 3 ) 4 are also reported. (orig.)

  19. Spatial and depth variation of 210Po and 210Pb in monazite sand along HBRA of coastal Kerala

    International Nuclear Information System (INIS)

    D'Cunha, Primal; Narayana, Y.

    2013-01-01

    The samples collected from high background radiation area were analyzed for 210 Po and 210 Pb activities in order to understand their distribution, enrichment and depth profile in the beach sand. The 210 Po and 210 Pb activities vary from 1.85 to 31.27 Bq kg -1 and 9.77 to 132.30 Bq kg -1 respectively. The 210 Po/ 210 Pb indicate that the radionuclides 210 Po and 210 Pb are not in equilibrium and the accumulation of 210 Pb in sand is greater than for 210 Po. The spatial variations of 210 Po and 210 Pb activities were studied in detail. (author)

  20. High temperature neutron diffraction study of LaPO4

    International Nuclear Information System (INIS)

    Mishra, S.K.; Mittal, R.; Ningthoujam, R.S.; Vatsa, R.K.; Hansen, T.

    2016-01-01

    We report high temperature powder neutron diffractions study in LaPO 4 using high-flux D20 neutron diffractometer in the Institut Laue-Langevin, France. The measurements were carried out in high resolution mode (incident neutron wavelength 1.36 A) at various temperature upto 900°C. CarefuI inspection of temperature dependence of diffraction data showed appearance and disappearance of certain Bragg's reflections above 1273 K. It is a signature of structural phase transition. Rietveld refinement of the powder diffraction data revealed that diffraction patterns at and above 800°C could be indexed using the monoclinic structure with P21/n space group. Detail analysis for identify the water molecules is under investigation. (author)

  1. Hazard Map of the Poás Volcano

    Directory of Open Access Journals (Sweden)

    Gustavo Barrantes Castillo

    2015-07-01

    Full Text Available The Poás volcano presents a series of hazards to the lives and activities of the communities in its surroundings; these hazards include ash fall, volcanic gases, ballistic projection, pyroclastic flows, lahars and lava flows. In the study described in this article, risks were zoned and integrated to form combined hazard maps for later use in territorial planning processes. With respect to methodology, the study was based on a heuristic approximation, which was supported with cartographic, geomorphological, and historical impact criteria to achieve a suitable product in terms of scale and ease of interpretation. These maps present greater detail and integration than other works and cartographies of volcanic hazards in Costa Rica.

  2. Polarization mechanism and ferroelectric instability in KH2PO4

    International Nuclear Information System (INIS)

    Koval, S.; Migoni, R.L.; Kohanoff, J.; Bussmann-Holder, A.

    2000-11-01

    The polarization mechanism and the origin of ferroelectricity in KH 2 PO 4 (KDP) are studied by first-principles electronic structure calculations. In the low-temperature phase, the collective off-center ordering of the protons is accompanied by an electronic charge delocalization from the near and localization at the far oxygen within the O-H...0 bonds. Electrostatic forces, then, push the K + ions towards off-center positions, and induce a macroscopic polarization. The analysis of the correlation between different geometrical and electronic quantities, in connection with experimental data, supports the idea that the role of tunnelling in isotopic effects is irrelevant. Instead, geometrical quantum effects appear to play a central role. (author)

  3. Postępowanie z chorym po zawale serca

    OpenAIRE

    Kalina Niedolaz; Katarzyna Hałas; Anna Kaźmierczak-Dziuk

    2011-01-01

    Choroba wieńcowa, czyli choroba niedokrwienna serca na podłożu miażdżycy tętnic wieńcowych, stanowi niezwykle istotny problem kliniczny. Jej bezpośrednim i często nieuchronnym następstwem jest zawał mięśnia serca. Zawał najczęściej jest spowodowany zamknięciem tętnicy wieńcowej w wyniku uszkodzenia blaszki miażdżycowej (jej pęknięcia lub erozji) z następowym wytworzeniem dystalnego zakrzepu i powoduje zniszczenie prawidłowo działającego mięśnia sercowego. Chory po przebytym zawale...

  4. Un monochrome poétique de Georges Fourest

    OpenAIRE

    Robert, Laurent

    2007-01-01

    Cet article propose une lecture du « Pseudo-sonnet que les amateurs de plaisanterie facile proclameront le plus beau du recueil » extrait de La Négresse blonde (1909) de Georges Fourest. La démarche de Fourest est mise en relation à la fois avec celle des peintures «monochroïdales » d’Alphonse Allais et avec celle du « sonnet en yx » de Stéphane Mallarmé. Elle est finalement perçue dans toute son ambiguïté, entre la mise en cause radicale de la poésie et la facétie fin de siècle. Peer revi...

  5. Bremsstrahlung emission probability in the α decay of 210Po

    International Nuclear Information System (INIS)

    Boie, Hans-Hermann

    2009-01-01

    A high-statistics measurement of bremsstrahlung emitted in the α decay of 210 Po has been performed. The measured differential emission probabilities, which could be followed up to γ-energies of ∝ 500 keV, allow for the first time for a serious test of various model calculations of the bremsstrahlung accompanied α decay. It is shown that corrections to the α-γ angular correlation due to the interference between the electric dipole and quadrupole amplitudes and due to the relativistic character of the process have to be taken into account. With the experimentally derived angular correlation the measured energydifferential bremsstrahlung emission probabilities show excellent agreement with the fully quantum mechanical calculation. (orig.)

  6. CFD modelling of Po River morphodynamics affected by bridge piers

    Science.gov (United States)

    Nones, Michael; Guerrero, Massimo; Ruther, Nils; Baranya, Sandor

    2017-04-01

    The paper presents the numerical modelling of the hydromorphological evolution of a 10-km reach of the Po River close to Ostiglia in Italy, affected by the presence of a railway bridge. The 3D simulation is performed using the freely available code SSIIM, developed at the University of Science and Technology in Trondheim in Norway. The domain consists of an unstructured grid with rectangular meshes having a dimension of 50x50 meters, with a nested detailed grid (5x5 m) around the piers. Preliminary results show the capability of the model in reproducing the behaviour of the reach, both in terms of liquid flow and morphodynamics, if compared with historical data measured along this watercourse. For the future, as a part of the Italian national project INFRASAFE, additional simulations will be performed to calibrate the model, changing the analyzed domain and used grids, and imposing, as boundary conditions, new data measured directly on the field with traditional and innovative techniques.

  7. Sol–gel synthesis and electrochemical properties of 9LiFePO4·Li3V2(PO4)3/C composite cathode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Zhong Shengkui; Wu Ling; Liu Jiequn

    2012-01-01

    Highlights: ► Nano-sized 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C powders are prepared by a sol–gel method. ► Mutual doping in 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C can improve its electronic conductivity. ► The addition of Li 3 V 2 (PO 4 ) 3 can improve the ionic diffusivity of LiFePO 4 . ► LiFePO 4 , Li 3 V 2 (PO 4 ) 3 and LiFePO 4 –Li 3 V 2 (PO 4 ) 3 unit cells coexist in the composite. - Abstract: 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C composite cathode material is prepared by a sol–gel method, using ferric citrate, V 2 O 5 , Li 2 CO 3 , NH 4 H 2 PO 4 and citric acid as raw materials. The composite material is composed of the olivine LiFePO 4 and monoclinic Li 3 V 2 (PO 4 ) 3 phases. XRD results indicate that most of the iron and vanadium in the raw materials tend to form the LiFePO 4 and Li 3 V 2 (PO 4 ) 3 phases, and only small amounts of Fe and V as the dopants enter into the lattice of Li 3 V 2 (PO 4 ) 3 and LiFePO 4 , respectively. The electronic conductivity and Li + diffusion coefficient of 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C are 6.615 × 10 −3 S cm −1 and ∼10 −10 cm 2 s −1 , which are three orders of magnitude and one order of magnitude larger than those of the LiFePO 4 /C, respectively. The composite material shows a first discharge specific capacity of 131.3 mAh g −1 and capacity retention of 95.1% after 200 cycles at 10 C rate. Compared with the LiFePO 4 /C, its rate capability and cycle performance are both remarkably improved.

  8. A high-temperature Raman scattering study of the phase transitions in GaPO{sub 4} and in the AlPO{sub 4}-GaPO{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Angot, E [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Parc, R Le [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Levelut, C [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Beaurain, M [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Armand, P [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Cambon, O [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Haines, J [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France)

    2006-05-03

    Al{sub 1-x}Ga{sub x}PO{sub 4} solid solutions (x = 0.2, 0.3, 0.38, 0.7) and the pure AlPO{sub 4} (x = 0) and GaPO{sub 4} (x = 1) end members with the {alpha}-quartz-type structure were studied by Raman scattering. An investigation as a function of composition enabled the various modes to be assigned, in particular coupled and decoupled vibrations. The tetrahedral tilting modes, which have been linked to high-temperature phase transitions to {beta}-quartz-type forms, were found to be decoupled. In addition, it is shown that Raman spectroscopy is a powerful technique for determining the gallium content of these solid solutions. Single crystals with x = 0.2, 0.38, and 1.0 (GaPO{sub 4}) were investigated at high temperature. The composition Al{sub 0.8}Ga{sub 0.2}PO{sub 4} was found to exhibit sequential transitions upon heating to the {beta}-quartz and {beta}-cristobalite forms at close to 993 K and 1073 K, respectively. Direct {alpha}-quartz-{beta}-cristobalite transitions were observed for the two other compositions at close to 1083 K and 1253 K, respectively, upon heating. The spectra of the {beta}-quartz and {beta}-cristobalite forms indicate the presence of significant disorder. Back transformation to the {alpha}-quartz-type form occurred readily with a hysteresis of less than 100 K for the composition x = 0.38 and for pure GaPO{sub 4}. Rapid cooling was necessary to obtain the metastable {alpha}-cristobalite form. In contrast, for Al{sub 0.80}Ga{sub 0.20}PO{sub 4}, the {alpha}-cristobalite form was obtained even upon slow cooling.

  9. Nucleation and growth of new particles in Po Valley, Italy

    Directory of Open Access Journals (Sweden)

    A. Hamed

    2007-01-01

    Full Text Available Aerosol number distribution measurements are reported at San Pietro Capofiume (SPC station (44°39' N, 11°37' E for the time period 2002–2005. The station is located in Po Valley, the largest industrial, trading and agricultural area in Italy with a high population density. New particle formation was studied based on observations of the particle size distribution, meteorological and gas phase parameters. The nucleation events were classified according to the event clarity based on the particle number concentrations, and the particle formation and growth rates. Out of a total of 769 operational days from 2002 to 2005 clear events were detected on 36% of the days whilst 33% are clearly non-event days. The event frequency was high during spring and summer months with maximum values in May and July, whereas lower frequency was observed in winter and autumn months. The average particle formation and growth rates were estimated as ~6 cm−3 s−1 and ~7 nm h−1, respectively. Such high growth and formation rates are typical for polluted areas. Temperature, wind speed, solar radiation, SO2 and O3 concentrations were on average higher on nucleation days than on non-event days, whereas relative and absolute humidity and NO2 concentration were lower; however, seasonal differences were observed. Backtrajectory analysis suggests that during majority of nucleation event days, the air masses originate from northern to eastern directions. We also study previously developed nucleation event correlations with environmental variables and show that they predict Po Valley nucleation events with variable success.

  10. Modelling the behaviour of 210Po in high temperature processes

    International Nuclear Information System (INIS)

    Mora, J.C.; Robles, B.; Corbacho, J.A.; Gasco, Catalina; Gazquez, M.J.

    2011-01-01

    In several Naturally Occurring Radioactive Material (NORM) industries, relatively high temperatures are used as part of their industrial processes. In coal combustion, as occur in other high temperature processes, an increase of the activity concentration of every natural radioisotope is produced both, in residues and by-products. An additional increase can be observed in the activity concentration of radionuclides of elements with low boiling point. This work is centred in the increase of polonium, more precisely in its radioisotope Po-210, present in the natural chains, and with a half-life long enough to be considered for radiation protection purposes. This additional increase appears mainly in the residual particles that are suspended in the flue gases: the fly-ashes. Besides, scales, with a high concentration of this radioisotope, were observed. These scales are produced on surfaces with a temperature lower than the boiling point of the chemical element. Both, the accumulation in particles and the production of scales are attributed to condensation effects. When effective doses for the public and the workers are evaluated, taking into account these increases in activity concentrations, the use of theoretical models is necessary. In this work a theoretical description of those effects is presented. Moreover, a verification of the predictions of the model was performed by comparing them with measurements carried on in coal-fired power plants. The same description here presented is applicable in general to the behaviour of Po-210 in other NORM industries where high temperature processes involving raw materials are used, as can be ceramic, cement production, tiles production or steel processing.

  11. Canted antiferromagnetism in KNi3[PO3(F,OH)]2[PO2(OH)2]F2 with a stair-case Kagomé lattice

    Science.gov (United States)

    Liu, Li-Chen; Ren, Wei-Jian; Huang, Ya-Xi; Pan, Yuanming; Mi, Jin-Xiao

    2017-10-01

    A new nickel phosphate KNi3[PO3(F,OH)]2[PO2(OH)2]F2 has been synthesized using a modified hydrothermal method. Structural characterizations show that it adopts a 3D framework structure with 2D layers of Ni octahedra in a stair-case Kagomé lattice. The Ni2 octahedron at the inversion center shares two trans-faces with Ni1 octahedra to form a linear trimer (Ni3O8F6) as the basic structural unit. The Ni-trimers are linked between themselves by sharing F-corners and to [PO3(F,OH)] tetrahedral groups by sharing O-corners to form 2D stair-case Kagomé layers, which are parallel to the (100) plane and are stacked along the a-axis. Successive Kagomé layers are combined together by [PO2(OH)2] tetrahedral groups and interstice cations K+. Magnetic measurements reveal that KNi3[PO3(F,OH)]2[PO2(OH)2]F2 exhibits a canted antiferromagnetic ordering with a ferromagnetic component at low temperatures.

  12. Multi-year Surface Deposition of {sup 210}Pb and {sup 210}Po at Lisbon - Atmospheric Depositions of {sup 210}Pb and {sup 210}Po in Lisbon, Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Fernando P.; Oliveira, Joao M.; Alberto, G. [Instituto Superior Tecnico/ Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, E.N. 10, 2686-953 Sacavem (Portugal)

    2014-07-01

    The long lived radon daughters {sup 210}Pb and {sup 210}Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual {sup 210}Pb flux was 66±12 Bq m{sup -2}, and the average annual {sup 210}Po flux was 8±3 Bq m{sup -2}, with an overall {sup 210}Po/{sup 210}Pb activity ratio of 0.15±0.06. Direct determination of the {sup 210}Pb atmospheric flux was compared with the {sup 210}Pb excess determined in soil surface layers along with atmospheric depositions of {sup 137}Cs. The deposition of atmospheric {sup 210}Pb was positively correlated with seasonal rainfall, while {sup 210}Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high {sup 210}Po/{sup 210}Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of {sup 210}Pb and {sup 210}Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)

  13. Synthesis and luminescence of CePO4 and CePO4:Tb hollow and core-shell microspheres composed of single-crystal nanorods

    International Nuclear Information System (INIS)

    Guan Mingyun; Sun Jianhua; Han Min; Xu Zheng; Tao Feifei; Yin Gui; Wei Xianwen; Zhu Jianmin; Jiang Xiqun

    2007-01-01

    Lanthanide phosphate microspheres composed of single-crystal CePO 4 and CePO 4 :Tb nanorods were successfully synthesized, respectively, using the functionalized composite aggregate as a template, which is composed of P123, H 6 P 4 O 13 and Ce 3+ , and also as a resource of reaction species with high chemical potential. The shape and the phase structure of the CePO 4 nanocrystal can be easily controlled via adjusting reaction temperature, monomer concentration and annealing temperature. SEM images show the spherical superstructure composed of nanorods. HRTEM and SAED images reveal the single-crystalline nature of nanorod and TEM images show the hollow interiors of the superstructure. XRD patterns indicate that the crystal structure of the nanorods is hexagonal before and monoclinic after annealing. The formation mechanism was proposed. Strong UV and green luminescence were observed for the CePO 4 and CePO 4 :Tb microspheres, respectively. The synthesis method can be extended to the fabrication of NRHS and core-shell microspheres of other rare-earth or doped LnPO 4 materials for wide applications

  14. Rate-dependent, Li-ion insertion/deinsertion behavior of LiFePO4 cathodes in commercial 18650 LiFePO4 cells.

    Science.gov (United States)

    Liu, Qi; He, Hao; Li, Zhe-Fei; Liu, Yadong; Ren, Yang; Lu, Wenquan; Lu, Jun; Stach, Eric A; Xie, Jian

    2014-03-12

    We have performed operando synchrotron high-energy X-ray diffraction (XRD) to obtain nonintrusive, real-time monitoring of the dynamic chemical and structural changes in commercial 18650 LiFePO4/C cells under realistic cycling conditions. The results indicate a nonequilibrium lithium insertion and extraction in the LiFePO4 cathode, with neither the LiFePO4 phase nor the FePO4 phase maintaining a static composition during lithium insertion/extraction. On the basis of our observations, we propose that the LiFePO4 cathode simultaneously experiences both a two-phase reaction mechanism and a dual-phase solid-solution reaction mechanism over the entire range of the flat voltage plateau, with this dual-phase solid-solution behavior being strongly dependent on charge/discharge rates. The proposed dual-phase solid-solution mechanism may explain the remarkable rate capability of LiFePO4 in commercial cells.

  15. 210Po and 210Pb activity concentration in the coral bands of Pulau Tuba, Langkawi

    International Nuclear Information System (INIS)

    Lee Jen Nie; Che Abdul Rahim Mohamed; Zaharuddin Ahmad

    2007-01-01

    We examined the concentrations of 210 Po and 210 Pb in each layers of coral banding of coral skeletons. Concentrations of 210 Po and 210 Pb in massive corals (i.e. Porites, Favites, Platygyra and Goniostrea) from Pulau Tuba, Langkawi were measured using the Alpha-Spectrometry. The concentrations of 210 Po were higher than the concentrations of 210 Pb. This may due to continuing source of 210 Po from 210 Pb. Highest concentration on 210 Po in coral banding was 48.30 ± 28.53 Bq/ kg, meanwhile for 210 Pb was 12.86 ± 5.80 Bq/ kg. The ratios of 210 Po/ 210 Pb were in the range of 2.21 to 5.49. The variation activity concentrations of 210 Po and 210 Pb in the coral bands are important to consider in using coral as retrospective study of environmental changes. The coral can represent the total of 210 Po and 210 Pb in the surrounding water for the past few years. (author)

  16. Moderní počítačové viry

    OpenAIRE

    Malina, Lukáš

    2008-01-01

    Bakalářská práce Moderní počítačové viry se skládá ze dvou hlavních cílů (Analýza počítačových virů a návrh zabezpečení střední počítačové sítě) rozdělených na tři části: Analýza počítačových virů, Vlastní návrh zabezpečení osobního počítače koncového uživatele (Terminálu) a Vlastní návrh zabezpečení střední počítačové sítě. V první části jsou analyzovány metody šíření a infekce, specifické vlastnosti a dopady počítačových virů na osobní počítače. V druhé části je uvedeno řešení zabezpečení o...

  17. Hexamethylenetetramine assisted hydrothermal synthesis of BiPO4 and its electrochemical properties for supercapacitors

    Science.gov (United States)

    Nithya, V. D.; Kalai Selvan, R.; Vasylechko, Leonid

    2015-11-01

    The well defined microstructures of BiPO4 were successfully synthesized by the facile hexamethylenetetramine (HMT) assisted hydrothermal method. The low temperature monoclinic BiPO4 structure with space group P21/n, were obtained from X-ray diffraction (XRD) for the pristine and HMT-assisted BiPO4 with 1, 3, 5 and 10 mmole concentration. A transformation from low temperature monazite-type phase to the high temperature SbPO4-type phase of BiPO4 was observed at the 10 mmole concentration. There was a variation in the morphology from polyhedron to octahedra-like and finally into cube shape upon an increase in concentration of HMT. The role of reaction time in the morphology of BiPO4 particles was investigated. The selected area electron diffraction (SAED) pattern elucidated the ordered dot pattern and the calculated d-spacing revealed the formation of BiPO4. An increased specific capacitance of HMT assisted materials (202 F/g) compared with pristine BiPO4 (89 F/g) at 5 mA/cm2 was observed upon morphological variation due to HMT addition.

  18. Bioassay of 210Po in human urine and internal contamination of man

    International Nuclear Information System (INIS)

    Carvalho, F.P.; Oliveira, J.M.

    2009-01-01

    The deliberate poisoning of A. Litvinenko in London in late 2006 with 210 Po, attracted attention to the difficulties in identifying internal contamination with alpha emitting radionuclides and to the limited knowledge available on the cycling of many naturally occurring radioisotopes in the body and their baseline concentration values in humans. To cope with the emergency caused by the spread of high 210 Po activity, which contaminated several people and places in London, we were called upon to analyze urine samples in potentially contaminated people. A reference group of adult humans was also selected for determination of baseline 210 Po values to be used for comparative purposes. Concentrations of 210 Po in urine samples from three Portuguese citizens that have been at contaminated places, in London, ranged from 2.3 to 4.1 mBq x L -1 while in the reference group 210 Po concentrations ranged from 0.5 to 4.8 mBq x L -1 . Analytical quality of results was ensured through participation in an international inter laboratory comparison exercise on 210 Po determination in aqueous samples. Results indicated that people potentially exposed to 210 Po in London were not internally contaminated with the radionuclide used as a poisoning agent, and the levels of this radionuclide measured in the urine were similar to the naturally occurring levels in the reference group. Polonium levels in urine and in man are discussed in the light of 210 Po levels in the human diet. (author)

  19. PoD: dynamically create and use remote PROOF clusters. A thin client concept.

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    PoD’s newly developed “pod-remote” command made it possible for users to utilize a thin client concept. In order to create dynamic PROOF clusters, users are now able to select a remote computer, even behind a firewall, to control a PoD server on...

  20. Voyage: espace et poésie dans un calligramme d'Apollinaire

    Directory of Open Access Journals (Sweden)

    Laurent GRISON

    1998-06-01

    Full Text Available L'œuvre de Guillaume Apollinaire offre une approche spécifique de la poésie et de l'espace. L'étude d'un calligramme, Voyage, nous permet de souligner à quel point cet auteur mêle travail poétique et réflexion sur la spatialité.

  1. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood oxygen partial pressure (PO2... Indwelling blood oxygen partial pressure (PO2) analyzer. (a) Identification. An indwelling blood oxygen... electrode) and that is used to measure, in vivo, the partial pressure of oxygen in blood to aid in...

  2. Preparation and photocatalytic degradation performance of Ag_3PO_4 with a two-step approach

    International Nuclear Information System (INIS)

    Li, Jiwen; Ji, Xiaojing; Li, Xian; Hu, Xianghua; Sun, Yanfang; Ma, Jingjun; Qiao, Gaowei

    2016-01-01

    Highlights: • Ag_3PO_4 photocatalysts were synthesized via one-step and two-step ion-exchange reaction. • Photocatalytic properties of Ag_3PO_4 photocatalysts was investigated, the result indicated the Ag_3PO_4 (2) was higher than that of Ag_3PO_4 (1) under the same experimental condition. • Ag_3PO_4 (2) particles were larger than Ag_3PO_4 (1) particles and many polygonal-shaped surfaces could be clearly observed in the Ag_3PO_4 (2) particles. - Abstract: Ag_3PO_4 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%

  3. Biocarbon-coated LiFePO4 nucleus nanoparticles enhancing electrochemical performances.

    Science.gov (United States)

    Zhang, Xueguang; Zhang, Xudong; He, Wen; Yue, Yuanzheng; Liu, Hong; Ma, Jingyun

    2012-10-18

    We report a simple, inexpensive green biomimetic way for developing the high performance LiFePO(4) for high-power lithium-ion batteries. Biocarbon-coated LiFePO(4) nucleus nanoparticles are synthesized by using yeast cells as both a structural template and a biocarbon source.

  4. Investigation of 210Po/210Pb in terrestrial environment of uranium mineralized area of Jaduguda

    International Nuclear Information System (INIS)

    Sethy, N.K.; Jha, V.N.; Singh, S.; Sharma, B.D.; Sahoo, S.K.; Jha, S.K.; Tripathi, R.M.

    2018-01-01

    Soil is the major components for evaluation of migration characteristics and distribution of radionuclides like 210 Po and 210 Pb in a terrestrial ecosystem. In this study spatial profile of 210 Po in to soil and its equilibrium status with 210 Pb in the terrestrial environment have been studied and correlated with basic soil quality parameters

  5. Concentration and distribution of 210Po in rats exposed to radon

    International Nuclear Information System (INIS)

    Pan Peng; Yang Zhanshan; Wang Tianchang; Tong Jian; Zhou Jianwei

    2007-01-01

    Objective: To study the concentration and distribution of 210 Po in rats exposed to radon and its daughters. Methods: Fifteen male wistar rats were randomly divided into three groups, including one control group and two radon exposed groups with the cumulative doses of 100 WLM (low dose) and 200 WLM (high dose), respectively. Tissue samples containing 210 Po were spontaneously deposited onto silvery discs with the diameter of 20 mm by means of wet ashing and electrodeposition. The concentration of 210 Po in tissues were measured by α spectroscopy, and tissue burden were calculated. Results: The concentrations of 210 Po were significantly different among the three dose groups in femur, liver, sex gland and hair (P 210 Po were different between the exposed groups and the control group in lung and soleus muscle (P 210 Po in lung, spleen and hair were higher than that in liver, bone and sex gland, the lowest was in intestine. The tissue burdens of liver, bone and sex gland were significantly different from those in other organs or tissues. Conclusions: 210 Po was mainly distributed in lung, liver, spleen, femur and sex gland. The concentrations of 210 Po in organs or tissues and the tissue burdens were correspondingly increased with the exposure dose of radon and its daughters. The results of this experiment provide a dosimetric basis for further studies on the carcinogenic effect of radon and its daughters. (authors)

  6. Influence of fluid resuscitation on renal microvascular PO2 in a normotensive rat model of endotoxemia

    NARCIS (Netherlands)

    Johannes, Tanja; Mik, Egbert G.; Nohé, Boris; Raat, Nicolaas J. H.; Unertl, Klaus E.; Ince, Can

    2006-01-01

    INTRODUCTION: Septic renal failure is often seen in the intensive care unit but its pathogenesis is only partly understood. This study, performed in a normotensive rat model of endotoxemia, tests the hypotheses that endotoxemia impairs renal microvascular PO2 (microPO2) and oxygen consumption

  7. 210Po and 210Pb in food chains lichen - reindeer - man

    International Nuclear Information System (INIS)

    Solatie, D.; Yunttila, M.; Vesterbakka, P.

    2006-01-01

    Migration of 210 Po and its precursor 210 Pb from radioactive fallout through food chain lichen - reindeer - man is studied. Samples of lichens, leaves, grass, mushrooms, soils, and samples of reindeer tissues are selected; their specific radioactivity and ratio 210 Po/ 210 Pb are determined [ru

  8. Ionothermal synthesis, crystal structure, and magnetic study of Co2PO4OH isostructural with caminite.

    Science.gov (United States)

    Wang, Guangmei; Valldor, Martin; Spielberg, Eike T; Mudring, Anja-Verena

    2014-03-17

    A new framework cobalt(II) hydroxyl phosphate, Co2PO4OH, was prepared by ionothermal synthesis using 1-butyl-4-methyl-pyridinium hexafluorophosphate as the ionic liquid. As the formation of Co2PO4F competes in the synthesis, the synthesis conditions have to be judiciously chosen to obtain well-crystallized, single phase Co2PO4OH. Single-crystal X-ray diffraction analyses reveal Co2PO4OH crystallizes with space group I41/amd (a = b = 5.2713(7) Å, c = 12.907(3) Å, V = 358.63(10) Å(3), and Z = 4). Astonishingly, it does not crystallize isotypically with Co2PO4F but rather isotypically with the hydroxyl minerals caminite Mg1.33[SO4(OH)0.66(H2O)0.33] and lipscombite Fe(2–y)PO4(OH) (0 ≤ y ≤ 2/3). Phosphate tetrahedra groups interconnect four rod-packed face-sharing ∞(1){CoO(6/2)} octahedra chains to form a three-dimensional framework structure. The compound Co2PO4OH was further characterized by powder X-ray diffraction, Fourier transform–infrared, and ultraviolet–visible spectroscopy, confirming the discussed structure. The magnetic measurement reveals that Co2PO4OH undergoes a magnetic transition and presents at low temperatures a canted antiferromagnetic spin order in the ground state.

  9. Correlation of regional disease and in vivo PO2 in rat mammary adenocarcinoma.

    Science.gov (United States)

    Cole, M A; Crawford, D W; Warner, N E; Puffer, H W

    1983-07-01

    A knowledge of the distribution of oxygen tension (PO2) and vascularization in neoplasia has been fundamental to understanding relationships between tumor growth, hypoxia, and therapy. We have combined recessed oxygen microcathode and freeze-substitution techniques to correlate in situ PO2 profiles and morphologic features in 7,12-dimethylbenz(a)anthracene (DMBA) tumors in rats. Overlying connective tissue of transplanted tumor was exposed by a 1-2 mm incision and a cross-stitch pattern demarcated electrode puncture sites for histologic reference. Three buffered salt solutions (BSS) with different PO2 were each allowed to flow through a well over the tumor where electrodes were placed for calibration. Zero electrode oxygen current was recorded from a buffered yeast-agar mixture of zero torr. PO2 was recorded at 5-mu intervals to approximately 1-2 mm. Atmospheric contamination was eliminated by continuous well flow of BSS, 30 torr. Finally, the tumor and surrounding tissues were quick-frozen in vivo with Freon 22 and liquid nitrogen. The tissue block was freeze-substituted and sectioned. PO2 profiles were superimposed onto correspondingly scaled photomicrographs. A viable periphery with a PO2 range of 50-82 torr and a transition to necrotic areas of PO2, 2-13 torr were observed. This transition was characterized by PO2 gradients within distances of 50-300 mu at variable puncture depths. This technique should be useful in further studies of growth, necrosis, and therapy.

  10. Supervalent doping of LiFePO4 for enhanced electrochemical performance

    Directory of Open Access Journals (Sweden)

    N. V. Kosova

    2015-12-01

    Full Text Available The orthophosphates LiFe0.9M0.1PO4 with the structure of olivine doped with vanadium and titanium were obtained by mechanochemically stimulated solidphase synthesis using high-energy planetary mill AGO-2 and subsequent annealing at 750 °C. It is shown that V- and Ti- ions do not completely substitute for Fe2+ ions in the LiFePO4 structure. The remaining part of these ions involve in the formation of second phase with nashiko-like structure: monoclinic Li3V2(PO43 (space group P21/n and rhombohedral LiTi2(PO43 (space group R-3c. According to TEM, the average size of the particle of nanocomposites is about 100-300 nm. EMF of microanalysis showed that the small particles of secondary phases are segregated at the surface of larger particles of LiFePO4. On the charge-discharge curves of LiFe0.9M0.1PO4 there are plateau corresponding to LiFePO4 and the second phase. The doping with vanadium increases the resistance of the cycling of LiFePO4 and improves its cyclability at high speeds to a greater extent than in the case of doping with titanium.

  11. Study on feed forward neural network convex optimization for LiFePO4 battery parameters

    Science.gov (United States)

    Liu, Xuepeng; Zhao, Dongmei

    2017-08-01

    Based on the modern facility agriculture automatic walking equipment LiFePO4 Battery, the parameter identification of LiFePO4 Battery is analyzed. An improved method for the process model of li battery is proposed, and the on-line estimation algorithm is presented. The parameters of the battery are identified using feed forward network neural convex optimization algorithm.

  12. Preservation of intestinal microvascular Po2 during normovolemic hemodilution in a rat model

    NARCIS (Netherlands)

    van Bommel, J.; Siegemund, M.; Henny, C. P.; van den Heuvel, D. A.; Trouwborst, A.; Ince, C.

    2000-01-01

    The effect of hemodilution on the intestinal microcirculatory oxygenation is not clear. The aim of this study was to determine the effect of moderate normovolemic hemodilution on intestinal microvascular partial oxygen pressure (Po2) and its relation to the mesenteric venous Po2 (Pmvo2).

  13. Some redox chemistry of HPO2-. and .PO32- radicals. A pulse radiolysis study

    International Nuclear Information System (INIS)

    Packer, J.E.; Anderson, R.F.

    1990-01-01

    The HO . radical oxidises hypophosphite and phosphite anions to HPO 2 -. and . PO 3 2- respectively, but Br 2 -. and N 3 . do not. The rates of oxidation of HPO 2 -. by a series of oxidising agents of known one electron redox potentials decrease with decreasing potential while the corresponding rates for oxidation of . PO 3 2- remain close to the diffusion controlled limit. . PO 3 2- will oxidise cysteine but HPO 2 -. does not. . PO 3 2- did not oxidise ABTS, ascorbate, or the anion of the vitamin E analogue, trolox. It reduced traces of TMPD +. in TMPD rather than oxidising the substrate. The one electron redox potentials for oxidation and reduction of . PO 3 2- are calculated in light of recently published redox data on penicillamine. (author)

  14. Determination of 210Po in tea, mat and their infusions and its annual intake by Syrians

    International Nuclear Information System (INIS)

    Al-Masri, M.S.; Nashawati, A.; Amin, Y.; Al-Akel, B.

    2004-01-01

    Polonium-210 was determined in 34 kinds of imported tea and 9 kinds of mat collected from the Syrian local market. The 210 Po concentration was found to vary from 5.5 to 39 Bq x kg -1 and 47 to 82 Bq x kg -1 in tea and mat samples, respectively. In addition 210 Po was also determined in tea and mat infusions where different infusion conditions have been examined: amount, temperature and infusion time. The results have shown that the amount of 210 Po transferred from tea and mat leaves to the aqueous extract ranged from 9 to 21% and 3 to 15%, respectively. The annual intake of 210 Po by Syrians due to tea consumption and mat infusions was calculated and found to be 9 Bq and 151 Bq for tea and mat respectively: washing of mat with warm water is recommended before preparation the infusions to decrease the annual intake of 210 Po. (author)

  15. Infrared-active optical phonons in LiFePO4 single crystals

    Science.gov (United States)

    Stanislavchuk, T. N.; Middlemiss, D. S.; Syzdek, J. S.; Janssen, Y.; Basistyy, R.; Sirenko, A. A.; Khalifah, P. G.; Grey, C. P.; Kostecki, R.

    2017-07-01

    Infrared-active optical phonons were studied in olivine LiFePO4 oriented single crystals by means of both rotating analyzer and rotating compensator spectroscopic ellipsometry in the spectral range between 50 and 1400 cm-1. The eigenfrequencies, oscillator strengths, and broadenings of the phonon modes were determined from fits of the anisotropic harmonic oscillator model to the data. Optical phonons in a heterosite FePO4 crystal were measured from the delithiated ab-surface of the LiFePO4 crystal and compared with the phonon modes of the latter. Good agreement was found between experimental data and the results of solid-state hybrid density functional theory calculations for the phonon modes in both LiFePO4 and FePO4.

  16. The effect of heat preservation time on the electrochemical properties of LiFePO4

    Science.gov (United States)

    He, Rui; Zhang, Lihui; Bai, Xue; Liu, Zhenfa

    2017-12-01

    LiFePO4 was prepared via high temperature solid-state method at different heat preservation time. XRD and SEM was used to test the structure and morphology of LiFePO4. Land 2001 was used to test the electrochemical performance of LiFePO4. The results illustrated that well-crystallized LiFePO4 composite with homogeneous small particles was obtained by XRD and SEM. And the optimum heat preservation time was 4 hour. From charge/discharge test, it can be seen that at 0.2C, LiFePO4 has initial discharge capacities of 159.1mAh/g at the heat preservation time 4 hour. From the rate capacity, it can be seen that the discharge capacity was of optimum sample remains above 99% after 200 cycles.

  17. Local structure of vanadium in doped LiFePO4

    International Nuclear Information System (INIS)

    Zhao, Ting; Xu, Wei; Ye, Qing; Cheng, Jie; Zhao, Haifeng; Chu, Wangsheng; Wu, Ziyu; Univ. of Science and Technology of China, Hefei; Xia, Dingguo

    2010-01-01

    LiFePO 4 composites with 5 at.% vanadium doping are prepared by solid state reactions. X-ray absorption fine-structure spectroscopy is used as a novel technique to identify vanadium sites. Both experimental analyses and theoretical simulations show that vanadium does not enter into the LiFePO 4 crystal lattice. When the vanadium concentration is lower then 1 at.%, the dopant remains insoluble. Thus, a single-phase vanadium-doped LiFePO4 cannot be formed and the improved electrochemical properties of vanadium doped LiFePO 4 previously reported cannot be associated with crystal structure changes of the LiFePO 4 via vanadium doping. (orig.)

  18. An evaluation of the exposure to 210Pb-210Po in italian population

    International Nuclear Information System (INIS)

    Clemente, G.F.; Santori, G.; Renzetti, A.

    1979-01-01

    Following an introduction on the behaviour in the environment and in man of 210 Pb- 210 Po, experimental data are reported on 210 Pb- 210 Po exposure of the italian population. The analytical methods used to measure 210 Pb- 210 Po activity in the many biological and environmental samples analyzed are also reported. The data collected refer to the intake, excretion, internal burden and metabolism both in a group of subjects representative of the general population and in other critical groups exposed to high internal contamination of 210 Pb- 210 Po, as the radioactive spa wopkes and the miners. The absorbed dose due to 210 Pb- 210 Po has also been evaluated, on the basis of data referring to the various population groups

  19. Luminescence and energy transfer of Sm3+ and Eu3+ in Ca2PO4Cl

    International Nuclear Information System (INIS)

    Wang, Zhijun; Li, Panlai; Yang, Zhiping; Guo, Qinglin

    2014-01-01

    Sm 3+ , Eu 3+ , and Sm 3+ –Eu 3+ doped Ca 2 PO 4 Cl phosphors are synthesized by a solid-state method. Ca 2 PO 4 Cl:Sm 3+ can produce red emission under the 400 nm radiation excitation, and the emission peak is located at 601 nm, which is assigned to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ . Ca 2 PO 4 Cl:Eu 3+ can create red emission under the 392 nm radiation excitation, and the strongest peak is located at 620 nm, which is attributed to the 5 D 0 → 7 F 2 transition of Eu 3+ . The energy transfer from Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl has been validated and the critical distance (R c ) of Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl is calculated to be 1.14 nm. With increasing Eu 3+ doping concentration, the energy transfer efficiency (Sm 3+ →Eu 3+ ) gradually increases to 53.7%. The luminescence property of Ca 2 PO 4 Cl:Sm 3+ , Eu 3+ can be tuned by properly tuning the relative ratio of Sm 3+ –Eu 3+ , and the emission intensity of Ca 2 PO 4 Cl:Eu 3+ can be greatly enhanced by codoped Sm 3+ . - Highlights: • Ca 2 PO 4 Cl:Sm 3+ , Eu 3+ can produce red emission under the 400 nm radiation excitation. • The energy transfer from Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl has been validated. • The critical distance of Sm 3+ to Eu 3+ in Ca 2 PO 4 Cl is calculated to be 1.14 nm

  20. PO2 measurements in the microcirculation using phosphorescence quenching microscopy at high magnification.

    Science.gov (United States)

    Golub, Aleksander S; Pittman, Roland N

    2008-06-01

    In phosphorescence quenching microscopy (PQM), the multiple excitation of a reference volume produces the integration of oxygen consumption artifacts caused by individual flashes. We analyzed the performance of two types of PQM instruments to explain reported data on Po2 in the microcirculation. The combination of a large excitation area (LEA) and high flash rate produces a large oxygen photoconsumption artifact manifested differently in stationary and flowing fluids. A LEA instrument strongly depresses Po2 in a motionless tissue, but less in flowing blood, creating an apparent transmural Po2 drop in arterioles. The proposed model explains the mechanisms responsible for producing apparent transmural and longitudinal Po2 gradients in arterioles, a Po2 rise in venules, a hypothetical high respiration rate in the arteriolar wall and mesenteric tissue, a low Po2 in lymphatic microvessels, and both low and uniform tissue Po2. This alternative explanation for reported paradoxical results of Po2 distribution in the microcirculation obviates the need to revise the dominant role of capillaries in oxygen transport to tissue. Finding a way to eliminate the photoconsumption artifact is crucial for accurate microscopic oxygen measurements in microvascular networks and tissue. The PQM technique that employs a small excitation area (SEA) together with a low flash rate was specially designed to avoid accumulated oxygen photoconsumption in flowing blood and lymph. The related scanning SEA instrument provides artifact-free Po2 measurements in stationary tissue and motionless fluids. Thus the SEA technique significantly improves the accuracy of microscopic Po2 measurements in the microcirculation using the PQM.

  1. Removal of lead from crude antimony by using NaPo3 as lead elimination reagent

    Directory of Open Access Journals (Sweden)

    Ye L.G.

    2015-01-01

    Full Text Available In order to solve the shortcomings when removing lead from crude antimony in the traditional antimony smelting, a new process was provided using NaPO3 as lead elimination reagent to yield phosphate slag, and it was removed by floating on the surface of the liquid antimony. Reaction mechanism was clarified by using the TG-DTA and XRD techniques and single factor experiments of removal lead from crude antimony were engaged. The results show that PbO and NaPO3 begin endothermic reaction at 863K (590°C, and the reaction mainly form NaPb4(PO43 and NaPbPO4 below 1123K (850°C and above 1123K (850°C, respectively. Sb2O3 and NaPO3 start the reaction at 773K (500°C and generate an antimonic salt compound. The reaction product of the mixture of PbO, Sb2O3 and NaPO3 show that NaPO3 reacted with PbO prior when NaPO3 was insufficient, amorphous antimony glass will be generated only when NaPO3 was adequate. Single factor experiments were taken with NaNO3 as oxidizing agent under argon, effect of reaction time, reaction temperature and dosage of NaPO3 and NaNO3 on smelting results. The average content of lead in refined antimony was 0.05340% and 98.85% of lead were removed under optimal conditions; the content of lead in antimony have meet the requirements of commercial antimony.

  2. Controlled synthesis and photocatalytic properties of rhombic dodecahedral Ag3PO4 with high surface energy

    International Nuclear Information System (INIS)

    Xie, Yao; Huang, Zhaohui; Zhang, Zhijie; Zhang, Xiaoguang; Wen, Ruilong; Liu, Yangai; Fang, Minghao; Wu, Xiaowen

    2016-01-01

    Graphical abstract: The high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy (the surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ).) exhibited excellent photocatalytic activity. - Highlights: • High contents of rhombic dodecahedral Ag 3 PO 4 photocatalysts are prepared. • Excessive EG can destroy the morphology of Ag 3 PO 4 in synthesis process. • The rhombic dodecahedral Ag 3 PO 4 exhibits high surface energy. • High surface energy implies high photocatalytic activity. - Abstract: In this study, a series of Ag 3 PO 4 photocatalysts with different contents of rhombic dodecahedral particles were prepared in one pot by a facile, novel hydrothermal method using ethylene glycol (EG), which served as both a morphology modifier and reducing agent. The effects of EG content on the morphologies of Ag 3 PO 4 photocatalysts were discussed. The photocatalytic activity of the Ag 3 PO 4 photocatalysts was evaluated by the degradation of methylene blue trihydrate under visible-light irradiation. With the use of 0.8% EG in the reaction solvent, the sample exhibited excellent photocatalytic activity, attributed to the high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy. The surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ). However, with 1% EG in the reaction solvent, although the Ag 3 PO 4 photocatalysts were composed of a majority of rhombic dodecahedral Ag 3 PO 4 particles, tiny Ag particles formed from Ag + under the action of EG attached on the surface of the sample decreased the absorption of visible light, resulting in low photocatalytic activity.

  3. Energetics of cobalt phosphate frameworks: α, β, and red NaCoPO4

    International Nuclear Information System (INIS)

    Le, So-Nhu; Eng, Hank W.; Navrotsky, Alexandra

    2006-01-01

    Thermal behavior, relative stability, and enthalpy of formation of α (pink phase), β (blue phase), and red NaCoPO 4 are studied by differential scanning calorimetry, X-ray diffraction, and high-temperature oxide melt drop solution calorimetry. Red NaCoPO 4 with cobalt in trigonal bipyramidal coordination is metastable, irreversibly changing to α NaCoPO 4 at 827 K with an enthalpy of phase transition of -17.4±6.9 kJ mol -1 . α NaCoPO 4 with cobalt in octahedral coordination is the most stable phase at room temperature. It undergoes a reversible phase transition to the β phase (cobalt in tetrahedra) at 1006 K with an enthalpy of phase transition of 17.6±1.3 kJ mol -1 . Enthalpy of formation from oxides of α, β, and red NaCoPO 4 are -349.7±2.3, -332.1±2.5, and -332.3±7.2 kJ mol -1 ; standard enthalpy of formation of α, β, and red NaCoPO 4 are -1547.5±2.7, -1529.9±2.8, and -1530.0±7.3 kJ mol -1 , respectively. The more exothermic enthalpy of formation from oxides of β NaCoPO 4 compared to a structurally related aluminosilicate, NaAlSiO 4 nepheline, results from the stronger acid-base interaction of oxides in β NaCoPO 4 (Na 2 O, CoO, P 2 O 5 ) than in NaAlSiO 4 nepheline (Na 2 O, Al 2 O 3 , SiO 2 ). - Graphical abstract: Relative stability of NaCoPO 4 polymorphs compared to the most stable phase, α NaCoPO 4

  4. Pt/AlPO{sub 4} nanocomposite thin-film electrodes for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Yuhong; Kang, Joonhyeon; Nam, Seunghoon; Byun, Sujin [WCU Hybrid Materials Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Park, Byungwoo, E-mail: byungwoo@snu.ac.kr [WCU Hybrid Materials Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2012-07-16

    The enhanced catalytic properties toward ethanol electrooxidation on Pt/AlPO{sub 4} nanocomposite thin-film electrodes were investigated. The Pt/AlPO{sub 4} nanocomposites with various Al/Pt ratios (0.27, 0.57, and 0.96) were fabricated by a co-sputtering method. All of the Pt/AlPO{sub 4} nanocomposites showed a negative shift in the onset potential and a higher current density than those of pure Pt electrode for the electrooxidation of ethanol. Among the various Pt/AlPO{sub 4} nanocomposite thin-film electrodes, the electrode with an atomic ratio of Al to Pt of 0.57 showed the highest electrocatalytic activity for ethanol electrooxidation. The activation enthalpy for the optimum Pt/AlPO{sub 4} nanocomposite was approximately 0.05 eV lower than that of pure Pt. It is believed that the enhancement in catalytic activity is due to the electron-rich Pt resulting from the Fermi-energy difference between Pt and AlPO{sub 4}. - Highlights: Black-Right-Pointing-Pointer The enhanced ethanol electrooxidation on Pt/AlPO{sub 4} nanocomposites is investigated. Black-Right-Pointing-Pointer The Pt/AlPO{sub 4} exhibits higher current density and lower onset potential than pure Pt. Black-Right-Pointing-Pointer The activation enthalpy for optimum Pt/AlPO{sub 4} electrode is {approx}0.05 eV lower than pure Pt. Black-Right-Pointing-Pointer XPS shows electron-rich Pt due to Fermi-energy difference between Pt and AlPO{sub 4}.

  5. Structural studies of the high-temperature modifications of sodium and silver orthophosphates, II-Na3PO4 and II-Ag3PO4, and of the low-temperature form I-Ag3PO4

    International Nuclear Information System (INIS)

    Newsam, J.M.; Cheetham, A.K.; Tofield, B.C.

    1980-01-01

    The crystal structures of the high-temperature modifications of sodium and silver orthophosphates have been determined using powder neutron diffraction (PND) data. II-Na 3 PO 4 adopts the space group Fm3m with a = 7.512(3) A at 400 0 C. The PO 4 3- group is centred around the origin, but it shows high orientational disorder. The sodium ions occupy the (1/4, 1/4, 1/4) and (1/2, 1/2, 1/2) sites. II-Ag 3 PO 4 , at 650 0 C, is similar with a = 7.722 (5) A. The structure of I-Ag 3 PO 4 at room temperature (P4 - 3n, a = 6.0095 (6) A) has been re-examined by single-crystal X-ray diffraction. The derived model, with R = 0.019 for 116 independent reflections, is in agreement with the latest work reported in the literature. The structure of I-Ag 3 PO 4 at 375 0 C, as determined by PND, has a = 6.061(1) A, and displays no gross modifications from that observed at 25 0 C, although the anisotropic nature of the silver sites is markedly more pronounced at this higher temperature. The cation mobility is discussed in relation to the high-temperature structures. (Auth.)

  6. Effect of VO43− substitution for PO43− on electrochemical properties of the Li3Fe2(PO4)3 cathode materials

    International Nuclear Information System (INIS)

    Yang, Yonggang; Zhang, Yongguang; Hua, Zhengshen; Wang, Xin; Peng, Huifen; Bakenov, Zhumabay

    2016-01-01

    Graphical abstract: VO 4 3− –substituted Li 3 Fe 2 (PO 4 ) 3 samples were prepared by sol-gel method. The VO 4 3− substitution remarkably improves the rate capability and cycling performance of the Li 3 Fe 2 (PO 4 ) 3 due to improved conductivity and enhanced lithium ion diffusion. - Highlights: • Mixed anion effect was used to improve electrochemical properties of Li 3 Fe 2 (PO 4 ) 3 . • The VO 4 3− substitution improved rate capability and cyclability of Li 3 Fe 2 (PO 4 ) 3 . • The Li 3 Fe 2 (PO 4 ) 2.55 (VO 4 ) 0.45 material shows the excellent electrochemical performance. - Abstract: In this research, VO 4 3− substitution was used to improve electrochemical properties of the Nasicon Li 3 Fe 2 (PO 4 ) 3 cathode material. The VO 4 3− substitution resulted in formation of a homogeneous compound Li 3 Fe 2 (PO 4 ) 3-x (VO 4 ) x in a composition range of x ≤ 0.45; further introduction of VO 4 3− led to precipitation of some other phases. It was shown that the VO 4 3− substituted samples presented discharging capacity higher than that of bare non-substituted Nasicon and the reported Ti 4+ and Mn 2+ doped ones. The Li 3 Fe 2 (PO 4 ) 2.55 (VO 4 ) 0.45 material exhibited excellent cycling stability and rate capability, and retained a capacity of 91.8 mAh g −1 after 60 cycles at 2C charge-discharge rate. This value is one of the highest reported to date for the Li 3 Fe 2 (PO 4 ) 3 compound, and was about 48% higher than that of the latter. The electrochemical performance enhancements for the VO 4 3− substituted samples were attributed to the reduction of charge transfer resistance, increase of electrical conductivity, and fast lithium ion diffusion behavior. Hence, the obtained results proved that the VO 4 3− anion substitution for PO 4 3− is a powerful technique to improve the electrochemical performance of the studied Nasicon compound.

  7. Absence of PO2 change in fetal brain despite PO2 increase in placenta in response to maternal oxygen challenge.

    Science.gov (United States)

    Huen, I; Morris, D M; Wright, C; Sibley, C P; Naish, J H; Johnstone, E D

    2014-12-01

    Magnetic resonance imaging allows the noninvasive observation of PO2 changes between air breathing and oxygen breathing through quantification of the magnetic longitudinal relaxation time T1. Changes in PO2 are proportional to changes in the longitudinal relaxation rate ΔR1 (where ΔR1=1/T1oxygen-1/T1air). Knowledge of this response could inform clinical interventions using maternal oxygen administration antenatally to treat fetal growth restriction. We present in vivo measurements of the response of the fetal-placental unit to maternal hyperoxia. Prospective cohort. Large tertiary maternity hospital. Nine women undergoing low-risk pregnancy (21-33 weeks of gestation) and five nonpregnant adults. During imaging the air supply to mothers was changed from medical air (21% oxygen) to medical oxygen (100% oxygen) and T1 was monitored over time in both the placenta and fetal brain using a periodically repeated magnetic resonance imaging sequence. To demonstrate that the method could detect a brain response, brain responses from five normal adult volunteers were measured using a similar imaging protocol. Changes in T1 following oxygen challenge. No significant ΔR1 (P=0.42, paired t-test) was observed in fetal brains. A significant placental ΔR1 (P=0.0002, paired t-test) of 0.02±0.01/s (mean±SD) was simultaneously observed in the same participants. In the brains of the nonpregnant adults, a significant ΔR1 (P=0.01, paired t-test) of 0.005±0.002/s was observed. Short-term maternal oxygen administration does not improve fetal brain oxygenation, in contrast to the response observed in the adult brain. © 2014 Royal College of Obstetricians and Gynaecologists.

  8. Equilibrium diagram of KPO{sub 3}-Y(PO{sub 3}){sub 3} system, chemical preparation and characterization of KY(PO{sub 3}){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Jouini, Anis; Ferid, Mokhtar; Trabelsi-Ayadi, Malika

    2003-04-17

    Microdifferential thermal analysis ({mu}-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO{sub 3}-Y(PO{sub 3}){sub 3} system. The only compound observed within the system was KY(PO{sub 3}){sub 4} melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO{sub 3}){sub 3} at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO{sub 3} was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO{sub 3}){sub 4} polyphosphate has the P2{sub 1} space group with lattice parameters: a=7.183(4) A, b=8.351(6) A, c=7.983(3) A, {beta}=91.75(3) deg. and Z=2 is isostructural with KNd(PO{sub 3}){sub 4}. The second allotropic form of KY(PO{sub 3}){sub 4} belongs to the P2{sub 1}/n space group with lattice parameters: a=10.835(3) A, b=9.003(2) A, c=10.314(1) A, {beta}=106.09(7) deg. and Z=4 and is isostructural with TlNd(PO{sub 3}){sub 4}. The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP{sub 4}O{sub 12} crystallizes in the C2/c space group with lattice parameters: a=7.825(3) A, b=12.537(4) A, c=10.584(2) A, {beta}=110.22(7) deg. and Z=4 is isostructural with RbNdP{sub 4}O{sub 12} and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported.

  9. Equilibrium diagram of KPO3-Y(PO3)3 system, chemical preparation and characterization of KY(PO3)4

    International Nuclear Information System (INIS)

    Jouini, Anis; Ferid, Mokhtar; Trabelsi-Ayadi, Malika

    2003-01-01

    Microdifferential thermal analysis (μ-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO 3 -Y(PO 3 ) 3 system. The only compound observed within the system was KY(PO 3 ) 4 melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO 3 ) 3 at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO 3 was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO 3 ) 4 polyphosphate has the P2 1 space group with lattice parameters: a=7.183(4) A, b=8.351(6) A, c=7.983(3) A, β=91.75(3) deg. and Z=2 is isostructural with KNd(PO 3 ) 4 . The second allotropic form of KY(PO 3 ) 4 belongs to the P2 1 /n space group with lattice parameters: a=10.835(3) A, b=9.003(2) A, c=10.314(1) A, β=106.09(7) deg. and Z=4 and is isostructural with TlNd(PO 3 ) 4 . The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP 4 O 12 crystallizes in the C2/c space group with lattice parameters: a=7.825(3) A, b=12.537(4) A, c=10.584(2) A, β=110.22(7) deg. and Z=4 is isostructural with RbNdP 4 O 12 and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported

  10. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    Science.gov (United States)

    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.

  11. Une poétique du vœu : inspiration poétique et mystique impériale dans le poème XIX (et quelques autres d’Optatianus Porfyrius

    Directory of Open Access Journals (Sweden)

    Marie-Odile Bruhat

    2010-11-01

    Full Text Available La majorité des poèmes d’Optatianus Porfyrius qui nous sont parvenus est dédiée à l’empereur Constantin et consacrée à son éloge. Mais dans cette poésie visuelle d’un nouveau genre, la célébration de l’art poétique tient une place aussi importante que la célébration impériale. Comment considérer le discours proprement poétique d’Optatianus ? Est-il simplement juxtaposé au discours politique ? Relève-t-il d’une pure convention ornementale ? Ces questions sont d’autant plus pertinentes que, loin de présenter le procédé visuel dont il est l’inventeur comme un art technicien, Optatianus revendique le double titre de poiètès et de uates et convoque les divinités de l’inspiration, Phébus et les Muses, alors même que ses poèmes se font l’écho de la nouvelle théologie chrétienne du pouvoir. La réponse apparaît double. D’une part, la poésie d’Optatianus peut être définie comme votive. Ses poèmes s’inscrivent dans la liturgie du pouvoir, c’est-à-dire dans le cadre d’une théologie impériale qui repose sur l’affirmation de l’éternité de la victoire et sur le renouvellement du charisme victorieux à travers le rituel des voeux. Par son discours sur Phébus et les Muses, Optatianus met en place une véritable poétique du voeu, qui consiste à couler la mystique de l’inspiration dans le moule de la mystique impériale. D’autre part, ce projet poétique répond à bien des égards à l’attente impériale. Il rencontre la volonté de Constantin de développer une politique culturelle, et se plie à quelques traits caractéristiques de sa religiosité : conviction de la nécessité du secours divin dans les actions humaines, d’une inspiration divine dont Constantin a fait lui-même l’expérience, attention aux signes et aux visions, attachement à un charisme solaire qui coexiste sous une forme « neutralisée » avec sa foi chrétienne. Le poème XIX, composé à l

  12. LiFePO4 nanoparticles encapsulated in graphene nanoshells for high-performance lithium-ion battery cathodes.

    Science.gov (United States)

    Fei, Huilong; Peng, Zhiwei; Yang, Yang; Li, Lei; Raji, Abdul-Rahman O; Samuel, Errol L G; Tour, James M

    2014-07-11

    LiFePO4 encapsulated in graphene nanoshells (LiFePO4@GNS) nanoparticles were synthesized by solid state reaction between graphene-coated Fe nanoparticles and LiH2PO4. The resulting nanocomposite was demonstrated to be a superior lithium-ion battery cathode with improved cycle and rate performances.

  13. Characterization of Carbon Composite LiMn1-xFexPO4 Cathodes

    International Nuclear Information System (INIS)

    Mishima, Y; Honda, S; Sadamura, H; Nakayama, N; Moriyoshi, C; Kuroiwa, Y

    2011-01-01

    The discharge capacities of 148 mAh/g (87 % theoretical value) at C/10 and 114mAh/g at 5C between 2.0 and 4.5 V at 25 deg. C were achieved for the carbon composite LiMn 0.8 Fe 0.2 PO 4 (C-LiMn 0.8 Fe 0.2 PO 4 ) cathode material of lithium-ion batteries (LIB), synthesized by a hydrothermal and annealing process. To improve the battery properties, we investigated the characteristics of C-LiMn 1-x Fe x PO 4 powders (x = 0.2 and 1) and the delithiated compound. While it was easier to form the homogeneous carbon layer on the surface of LiFePO 4 particles from the pyrolysis of sucrose, there was a tendency to form the particulate carbon on the LiMn 0.8 Fe 0.2 PO 4 particles. The lattice distortion of Mn 0.8 Fe 0.2 PO 4 was revealed by electron charge density study because of the Jahn-Teller active Mn 3+ ion associated with the phosphate ion. The surface and size of C- LiMn 0.8 Fe 0.2 PO 4 had to be modified because of these phenomena.

  14. Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

    Science.gov (United States)

    Zuo, Li; Pannell, Benjamin K; Re, Anthony T; Best, Thomas M; Wagner, Peter D

    2015-12-01

    Po2 cycling, often referred to as intermittent hypoxia, involves exposing tissues to brief cycles of low oxygen environments immediately followed by hyperoxic conditions. After experiencing long-term hypoxia, muscle can be damaged during the subsequent reintroduction of oxygen, which leads to muscle dysfunction via reperfusion injury. The protective effect and mechanism behind Po2 cycling in skeletal muscle during reoxygenation have yet to be fully elucidated. We hypothesize that Po2 cycling effectively increases muscle fatigue resistance through reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and certain mitochondrial channels during reoxygenation. Using a dihydrofluorescein fluorescent probe, we detected the production of ROS in mouse diaphragmatic skeletal muscle in real time under confocal microscopy. Muscles treated with Po2 cycling displayed significantly attenuated ROS levels (n = 5; P ROS, Akt, ERK, as well as chemical stimulators to close mitochondrial ATP-sensitive potassium channel (KATP) or open mitochondrial permeability transition pore (mPTP). All these blockers or stimulators abolished improved muscle function with Po2 cycling treatment. This current investigation has discovered a correlation between KATP and mPTP and the Po2 cycling pathway in diaphragmatic skeletal muscle. Thus we have identified a unique signaling pathway that may involve ROS, Akt, ERK, and mitochondrial channels responsible for Po2 cycling protection during reoxygenation conditions in the diaphragm. Copyright © 2015 the American Physiological Society.

  15. Geochemical behavior of 210Pb and 210Po in the nearshore waters off western Taiwan

    International Nuclear Information System (INIS)

    Wei, Ching-Ling; Lin, Shiao-Yu; Wen, Liang-Saw; Sheu, David D.-D.

    2012-01-01

    Highlights: ► 210 Pb and 210 Po in the nearshore waters were determined off western coast of Taiwan. ► Partitioning of the radionuclides in turbid waters was discussed. ► Removal flux of particulate organic carbon was quantified using 210 Po proxy. - Abstract: Dissolved and particulate 210 Pb and 210 Po were determined at 15 stations along the coastline off western Taiwan in April 2007. The 210 Pb activities in dissolved and particulate phases fell within a relatively small range of 2.4–5.2 dpm 100 L −1 and 1.0–3.2 dpm 100 L −1 , respectively. The dissolved and particulate 210 Po activities also fell within a small range of 0.8–3.4 dpm 100 L −1 and 1.1–2.9 dpm 100 L −1 , respectively. The correlation of the distribution coefficients (K d ) of 210 Pb and 210 Po with particle concentration in turbid waters are not as evident as in the open ocean. The mass balance calculation shows that the residence times of 210 Pb and 210 Po with respect to particle removal from the nearshore waters ranges from 3 to 15 days and from 14 to 125 days, respectively. The flux of particulate organic carbon was estimated by 210 Po proxy and ranged from 4.8 to 33.7 mmol-C m −2 d −1 .

  16. Structural and spectroscopic properties of MITh2(PO4)32 (M = Cu+, Ag+, Na+, K+)

    International Nuclear Information System (INIS)

    Arsalane, S.; Ziyad, M.

    1996-01-01

    Phosphates of general formulae M I Th 2 (PO 4 ) 3 where M = Cu + and Ag + were synthesized using sol-gel type methods and Cu + /Ag + ion exchange. Their structures were investigated by X-ray diffraction, FTIR, and 31 P MAS NMR spectroscopies. AgTh 2 (PO 4 ) 3 and NaTh 2 (PO 4 ) 3 were found to be isostructural. Their 31 P NMR spectra exhibit three resonances agreeing with the noncentrosymmetric space group Cc to which they belong. On the other hand, CuTh 2 (PO 4 ) 3 does not show a real crystallographic resemblance with the other M I Th 2 (PO 4 ) 3 phosphates of this family. Its 31 P NMR spectrum is similar to that of KTh 2 (PO 4 ) 3 and exhibits two sharp resonances in good agreement with the C2/c space group. Nevertheless, the [PO 4 ] groups in this phosphate are highly distorted because of the linear coordination of the Cu + copper ions

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

    Science.gov (United States)

    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). Copyright © 2013. Published by Elsevier Ltd.

  18. On a framework for generating PoD curves assisted by numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Subair, S. Mohamed, E-mail: prajagopal@iitm.ac.in; Agrawal, Shweta, E-mail: prajagopal@iitm.ac.in; Balasubramaniam, Krishnan, E-mail: prajagopal@iitm.ac.in; Rajagopal, Prabhu, E-mail: prajagopal@iitm.ac.in [Indian Institute of Technology Madras, Department of Mechanical Engineering, Chennai, T.N. (India); Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar [Indira Gandhi Centre for Atomic Research, Metallurgy and Materials Group, Kalpakkam, T.N. (India)

    2015-03-31

    The Probability of Detection (PoD) curve method has emerged as an important tool for the assessment of the performance of NDE techniques, a topic of particular interest to the nuclear industry where inspection qualification is very important. The conventional experimental means of generating PoD curves though, can be expensive, requiring large data sets (covering defects and test conditions), and equipment and operator time. Several methods of achieving faster estimates for PoD curves using physics-based modelling have been developed to address this problem. Numerical modelling techniques are also attractive, especially given the ever-increasing computational power available to scientists today. Here we develop procedures for obtaining PoD curves, assisted by numerical simulation and based on Bayesian statistics. Numerical simulations are performed using Finite Element analysis for factors that are assumed to be independent, random and normally distributed. PoD curves so generated are compared with experiments on austenitic stainless steel (SS) plates with artificially created notches. We examine issues affecting the PoD curve generation process including codes, standards, distribution of defect parameters and the choice of the noise threshold. We also study the assumption of normal distribution for signal response parameters and consider strategies for dealing with data that may be more complex or sparse to justify this. These topics are addressed and illustrated through the example case of generation of PoD curves for pulse-echo ultrasonic inspection of vertical surface-breaking cracks in SS plates.

  19. Simultaneous measurement of pO2 and perfusion in the rabbit kidney in vivo.

    Science.gov (United States)

    O'Connor, Paul M; Anderson, Warwick P; Kett, Michelle M; Evans, Roger G

    2007-01-01

    Recently, a combined probe has been developed capable of simultaneous measurement of local tissue pO2 (fluorescence oximetry) and microvascular perfusion (laser Doppler flux) within the same local region. The aim of the current study was to test the utility of these combined probes to measure pO2 and perfusion in the kidney. Studies were performed in anesthetized, artificially ventilated rabbits (n=7). Baseline measurements of renal medullary perfusion and pO2 obtained using combined probes (537 +/- 110 units & 28.7 +/- 6.l mmHg, respectively) were indistinguishable from those obtained using independent probes (435 +/- 102 units & 26.9 +/- 6.4 mmHg). Baseline measurements of renal cortical pO2 were also similar between combined (9.7 +/- 1.6 mmHg) and independent probes (9.5 +/- 2.3 mmHg). Baseline levels of cortical perfusion however, were significantly greater when measured using independent probes (1130 +/- 114 units) compared to combined probes (622 +/- 59 units; P pO2 resulting from graded stimulation of the renal nerves were not significantly different when measured using combined probes to those obtained using independent probes. We conclude that combined probes are equally suitable to independent probes for tissue pO2 and microvascular perfusion measurement in the kidney. Our results raise some concerns regarding the accuracy of these OxyLite fluorescence probes for pO2 measurement in the kidney, particularly within the renal cortex.

  20. One-pot synthesis and electrochemical reactivity of carbon coated LiFePO4 spindles

    International Nuclear Information System (INIS)

    Yu Juanjuan; Hu Juncheng; Li Jinlin

    2012-01-01

    Highlights: ► Carbon coated LiFePO 4 spindles have been successfully synthesized via a novel supercritical method. ► The concentrations of lithium have an effect on the morphology of carbon coated LiFePO 4 . ► Amorphous carbon layer formed on the surface of LiFePO 4 by adding glucose. ► The carbon coating is responsible for the enhanced electrochemical performance. - Abstract: Spindle-like carbon coated LiFePO 4 (LiFePO 4 /C) composites have been successfully synthesized via a novel one-pot supercritical methanol method. The products were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The particle size, morphology and electrochemical reactivity changed with the concentration of lithium and carbon source. A possible morphology evolution process was also proposed. The glucose not only facilitates the formation of single crystalline LiFePO 4 , but also gives an amorphous carbon layer on the surface LiFePO 4 spindles.

  1. $^{206}$ Po sources for production and release studies relevant for high power spallation targets

    CERN Multimedia

    The knowledge of the evaporation behaviour of Po is of essential importance for several scientific and technological applications, like accelerator driven systems (ADS) or the LIEBE project at CERN-ISOLDE. Fundamental investigations on the experimental conditions for the formation of volatile Po species as well as on the chemical composition of the volatile compounds are necessary for a safe operation of such facilities. $^{206}$Po, a mainly $\\gamma$- ray-emitting Po isotope with a half-life of 8.8 d, is best suited for model studies, due to the lower radiation hazard compared to the longer-lived $\\alpha$-emitting isotopes $^{208-210}$Po as well as the easy-to-measure $\\gamma$-ray emission. We propose the production of $^{206}$Po samples in several matrices via the implantation of its precursor $^{210}$Fr into selected metal foils at CERN-ISOLDE. Using these samples, experiments will be carried out at PSI studying the volatilization of Po from different matrices under varying chemical conditions.

  2. The electrical and diffusive properties of unattached 218Po in argon gas

    International Nuclear Information System (INIS)

    Leung, H.M.-Y.; Phillips, C.R.

    1987-01-01

    Electrical and diffusive properties of unattached 218 Po were investigated in argon Parameters determined in electrostatic collection experiments were radon concentration, the fraction of 218 Po having a positive charge at the end of the recoil path, the diffusion coefficient of the neutral 218 Po species, and the ratio of the neutralisation rate constant of charged 218 Po species to the electrical mobility of charged 218 Po species. Independent electrical mobility data were obtained using a pulse width modulated ion mobility analyser. The neutralisation rate constant for charged 218 Po species was then determined from the electrostatic collection data together with the independent mobility data. Relative humidity (RH) and radon concentration were found to affect the neutralisation mechanism. Following recoil of the charged 218 Po species, neutralisation through recombination with small negative ions is important for radon concentrations greater than about 1.0 x 10 5 atoms cm -3 . The neutralisation rate constant is proportional to about the 0.6 power of the radon concentration for all relative humidities. At a radon concentration less than about 1.0 x 10 5 atoms cm -3 , the neutralisation rate constant is independent of radon concentration. (author)

  3. A study on 210Po activity concentration in soil at different depths along coastal Kerala

    International Nuclear Information System (INIS)

    Primal D'Cunha; Sathyanarayana Bhat, P.; Narayana, Y.

    2011-01-01

    The paper presents systematic studies on the vertical profiles of 210 Po, an important decay product of 238 U, in soils along coastal Kerala. Soil samples collected from different depth intervals 0-10, 10-20, 20-30 cm were analyzed for 210 Po activity concentration by radiochemical methods. The activity 210 Po in soil samples were counted using a ZnS(Ag) alpha scintillation counting system. The mean values of activity concentrations of 210 Po in soil of various depths were found to be 8.66, 5.63 and 4.95 Bq kg -1 for depth intervals of 0-10, 10-20 and 20-30 cm, respectively. The overall activity concentration of 210 Po in soil was found to vary from 2.26 ± 0.19 to 14.02 ± 0.12 Bq kg -1 with a mean value of 6.43 Bq kg -1 . Maximum activity concentration was found in soil samples of Kollam region with the mean value of 10.08 ± 0.92 Bq kg -1 . The activity of 210 Po was found to be comparatively high in surface soil. The variation of 210 Po activity concentration with organic matter contents was studied. 210 Polonium activity concentration was found to increase with increasing organic matter content. (author)

  4. Synthesis of spherical LiMnPO4/C composite microparticles

    International Nuclear Information System (INIS)

    Bakenov, Zhumabay; Taniguchi, Izumi

    2011-01-01

    Highlights: → We could prepare LiMnPO 4 /C composites by a novel preparation method. → The LiMnPO 4 /C composites were spherical particles with a mean diameter of 3.65 μm. → The LiMnPO 4 /C composite cathode exhibited 112 mAh g -1 at 0.05 C. → It also showed a good rate capability up to 5 C at room temperature and 55 o C. -- Abstract: Spherical LiMnPO 4 /C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO 4 /C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was identified as a single phase orthorhombic structure of LiMnPO 4 and spherical powders with a geometric mean diameter of 3.65 μm and a geometric standard deviation of 1.34. The electrochemical cells contained the spherical LiMnPO 4 /C microparticles exhibited first discharge capacities of 112 and 130 mAh g -1 at 0.05 C at room temperature and 55 o C, respectively. These also showed a good rate capability up to 5 C at room temperature and 55 o C.

  5. Unlocking the energy capabilities of micron-sized LiFePO4.

    Science.gov (United States)

    Guo, Limin; Zhang, Yelong; Wang, Jiawei; Ma, Lipo; Ma, Shunchao; Zhang, Yantao; Wang, Erkang; Bi, Yujing; Wang, Deyu; McKee, William C; Xu, Ye; Chen, Jitao; Zhang, Qinghua; Nan, Cewen; Gu, Lin; Bruce, Peter G; Peng, Zhangquan

    2015-08-03

    Utilization of LiFePO4 as a cathode material for Li-ion batteries often requires size nanonization coupled with calcination-based carbon coating to improve its electrochemical performance, which, however, is usually at the expense of tap density and may be environmentally problematic. Here we report the utilization of micron-sized LiFePO4, which has a higher tap density than its nano-sized siblings, by forming a conducting polymer coating on its surface with a greener diazonium chemistry. Specifically, micron-sized LiFePO4 particles have been uniformly coated with a thin polyphenylene film via the spontaneous reaction between LiFePO4 and an aromatic diazonium salt of benzenediazonium tetrafluoroborate. The coated micron-sized LiFePO4, compared with its pristine counterpart, has shown improved electrical conductivity, high rate capability and excellent cyclability when used as a 'carbon additive free' cathode material for rechargeable Li-ion batteries. The bonding mechanism of polyphenylene to LiFePO4/FePO4 has been understood with density functional theory calculations.

  6. Ultralong Lifespan and Ultrafast Li Storage: Single-Crystal LiFePO4 Nanomeshes.

    Science.gov (United States)

    Zhang, Yan; Zhang, Hui Juan; Feng, Yang Yang; Fang, Ling; Wang, Yu

    2016-01-27

    A novel LiFePO4 material, in the shape of a nanomesh, has been rationally designed and synthesized based on the low crystal-mismatch strategy. The LiFePO4 nanomesh possesses several advantages in morphology and crystal structure, including a mesoporous structure, its crystal orientation that is along the [010] direction, and a shortened Li-ion diffusion path. These properties are favorable for their application as cathode in Li-ion batteries, as these will accelerate the Li-ion diffusion rate, improve the Li-ion exchange between the LiFePO4 nanomesh and the electrolyte, and reduce the Li-ion capacitive behavior during Li intercalation. So the LiFePO4 nanomesh exhibits a high specific capacity, enhanced rate capability, and strengthened cyclability. The method developed here can also be extended to other similar systems, for instance, LiMnPO4 , LiCoPO4 , and LiNiPO4 , and may find more applications in the designed synthesis of functional materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. (Solid + liquid) phase equilibria of (Ca(H2PO2)2 + CaCl2 + H2O) and (Ca(H2PO2)2 + NaH2PO2 + H2O) ternary systems at T = 323.15 K

    International Nuclear Information System (INIS)

    Cao, Hong-yu; Zhou, Huan; Bai, Xiao-qin; Ma, Ruo-xin; Tan, Li-na; Wang, Jun-min

    2016-01-01

    Graphical abstract: Solubility diagram of the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system at T = (323.15 and 298.15) K. - Highlights: • Phase diagrams of Ca 2+ -H 2 PO 2 − -Cl − -H 2 O, Ca 2+ -Na + -H 2 PO 2 − -H 2 O at 323.15 K were obtained. • Incompatible double salt of NaCa(H 2 PO 2 ) 3 in Ca 2+ -Na + -H 2 PO 2 − -H 2 O system was determined. • Density diagram of the corresponding liquid were simultaneously measured. - Abstract: Calcium hypophosphite has been widely used as an anti-corrosive agent, flame retardant, fertilizer, assistant for Ni electroless plating, and animal nutritional supplement. High purity calcium hypophosphite can be synthesized via the replacement reaction of sodium hypophosphite and calcium chloride. In this work, the (solid + liquid) phase equilibria of (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) and (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) ternary systems at T = 323.15 K were studied experimentally via the classical isothermal solubility equilibrium method, and the phase diagrams for these two systems were obtained. It was found that two solid salts of CaCl 2 ·2H 2 O and Ca(H 2 PO 2 ) 2 exist in the (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) system, and three salts of Ca(H 2 PO 2 ) 2 , NaH 2 PO 2 ·H 2 O and one incompatible double salt, NaCa(H 2 PO 2 ) 3 occur in the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system.

  8. Assessment of 210Po deposition in moss species and soil around coal-fired power plant

    International Nuclear Information System (INIS)

    Nita Salina Abu Bakar; Ahmad Saat

    2013-01-01

    In the present study, the depositions of 210 Po were assessed in the surface soil and some mosses species found in the area around coal fired power plant using radiochemical deposition and alpha spectrometry counting system. The purposes of the study were to determine activity concentrations of 210 Po in mosses and surface soil collected around coal-fired power plant in relation to trace the potential source of 210 Po and to identify most suitable moss species as a bio-indicator for 210 Po deposition. In this study, different species of mosses, Orthodontium imfractum, Campylopus serratus and Leucobryum aduncum were collected in May 2011 at the area around 15 km radius from Tanjung Bin coal-fired power plant located in Pontian, Johor. The 210 Po activity concentrations in mosses and soil varied in the range 102 ± 4 to 174 ± 8 Bq/kg dry wt. and 37 ± 2 to 184 ± 8 Bq/kg dry wt., respectively. Corresponding highest activity concentration of 210 Po observed in L. aduncum, therefore, this finding can be concluded this species was the most suitable as a bio-indicator for 210 Po deposition. On the other hand, it is clear the accumulation of 210 Po in mosses might be supplied from various sources of atmospheric deposition such as coal-fired power plant operation, industrial, plantation, agriculture and fertilizer activities, burned fuel fossil and forest; and other potential sources. Meanwhile, the main source of 210 Po in surface soil is supplied from the in situ deposition of radon decay and its daughters in the soil itself. (author)

  9. Morphology and conductivity study of solid electrolyte Li{sub 3}PO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Prayogi, Lugas Dwi, E-mail: ldprayodi@gmail.com; Faisal, Muhamad [Engineering Physics, Sepuluh Nopember Institute of Technology ITS Campus, Sukolilo, Surabaya 6011 (Indonesia); Kartini, Evvy, E-mail: kartini@batan.go.id; Honggowiranto, Wagiyo; Supardi [Center for Science and Technology of Advanced Materials, National Nuclear Energy Agency Kawasan Puspiptek Serpong, Tangerang Selatan15314, Banten (Indonesia)

    2016-02-08

    The comparison between two different methods of synthesize of solid electrolyte Li{sub 3}PO{sub 4} as precursor material for developing lithium ion battery, has been performed. The first method is to synthesize Li{sub 3}PO{sub 4} prepared by wet chemical reaction from LiOH and H{sub 3}PO{sub 4} which provide facile, abundant available resource, low cost, and low toxicity. The second method is solid state reaction prepared by Li{sub 2}CO{sub 3} and NH{sub 4}H{sub 2}PO{sub 4.} In addition, the possible morphology identification of comparison between two different methods will also be discussed. The composition, morphology, and additional identification phase and another compound of Li{sub 3}PO{sub 4} powder products from two different reaction are characterized by SEM, EDS, and EIS. The Li{sub 3}PO{sub 4} powder produced from wet reaction and solid state reaction have an average diameter of 0.834 – 7.81 µm and 2.15 – 17.3 µm, respectively. The density of Li{sub 3}PO{sub 4} prepared by wet chemical reaction is 2.238 gr/cm{sup 3}, little bit lower than the sample prepared by solid state reaction which density is 2.3560 gr/cm{sup 3}. The EIS measurement result shows that the conductivity of Li{sub 3}PO{sub 4} is 1.7 x 10{sup −9} S.cm{sup −1} for wet chemical reaction and 1.8 x 10{sup −10} S.cm{sup −1} for solid state reaction. The conductivity of Li{sub 3}PO{sub 4} is not quite different between those two samples even though they were prepared by different method of synthesize.

  10. Environmental radioactivity of radon daughter's radionuclides 210Pb-210Bi-210Po

    International Nuclear Information System (INIS)

    Momoshima, N.

    2003-01-01

    Radionuclide, 210 Pb(22.3 y)- 210 Bi(5.013 d)- 210 Po(138.4 d) belongs to the uranium decay chain and widely distributed in the environment. 222 Rn escaped from the earth surface is a major source of atmospheric 210 Pb. These nuclides attach with atmospheric aerosols and are removed to the ground as wet and dry depositions. The residence time of the atmospheric aerosol, thus, was obtained by activity ratios of 210 Bi/ 210 Pb and 210 Po/ 210 Pb, showing different values. The discrepancy on the residence times are explained with inputs of 210 Po to the atmosphere other than 222 Rn emanated from the earth surface. The removal of aerosol as wet deposition occupies a significant fraction, which reaches 72% on 210 Pb and 89% on 7 Be. In the ocean, the radionuclides are used as tracer to examine dynamic processes occurring in the ocean, such as removal of particulate matter from seawater column to bottom. The 210 Pb and 210 Po concentrations in the ocean water collected off continent decreased from surface toward bottom, and the shortage on 210 Po content relative to that of 210 Po was observed at shallow ocean layers, however, the 210 Po/ 210 Pb activity ratio closed to the radioactive equilibrium at deeper layers. The 210 Pb is a very good tracer to evaluate an accumulation rate of bottom sediment in ocean, lake and river. This is called as 210 Pb dating and is successfully applicable to accumulation circumstances that bottom sediment deposits at constant rate. Most of the actual cases, simultaneous 137 Cs dating is carried out, which uses 137 Cs peak in the core as originated from radioactive fallout of nuclear tests, showing the maximum in 1963. Recently new findings on source of atmospheric 210 Po are report by laboratory experiments and environmental measurements, which proves biologically supported emission of volatile Po compounds to the atmosphere. (author)

  11. Baseline concentration of 210Po and 210Pb in Sargassum from the northern Gulf

    International Nuclear Information System (INIS)

    Uddin, S.; Aba, A.; Bebhehani, M.

    2015-01-01

    Highlights: • This is the first baseline for 210 Po and 210 Pb in Sargassum from northern Gulf. • 210 Po concentration in Sargassum boveanum is higher than Sargassum oligocystum. • 210 Pb concentrations in two Sargassum species was not statistically significant. • The concentration factor is microalgae is slightly higher than IAEA recommended value. - Abstract: This baseline study highlights the 210 Po and 210 Pb concentration in two species of the benthic macroalgae Sargassum from northern Gulf, also known as the ROPME Sea Area (RSA). Within the marine environment, 210 Po is initially absorbed from water and concentrated by phytoplankton and macroalgae, and this concentrated 210 Po can then readily be passed along to the higher trophic level of the marine food web. The 210 Po concentration measured in Sargassum boveanum (22.5–25.6 Bq kg −1 ) was higher than that in Sargassum oligocystum (20.2–22.5 Bq kg −1 ), but is not statistically significant (p > 0.064), where as the difference between 210 Pb concentrations in Sargassum boveanum (15.3–16.8 Bq kg −1 ) and Sargassum oligocystum (18.4–22.0 Bq kg −1 ) was statistically significant (p > 0.019). The measured concentration factor for 210 Po in Sargassum in the northern Gulf varied between 0.55 and 1.2 × 10 4 , values higher to the IAEA recommended value of 1 × 10 3 . The 210 Po enrichment is observed in both the species of Sargassum, 210 Po/ 210 Pb ratio was >1 at all the stations for all the samples

  12. 210Po in the marine environment with emphasis on its behaviour within the biosphere

    International Nuclear Information System (INIS)

    Fowler, Scott W.

    2011-01-01

    The distribution and behaviour of the natural-series alpha-emitter polonium-210 in the marine environment has been under study for many years primarily due to its enhanced bioaccumulation, its strong affinity for binding with certain internal tissues, and its importance as a contributor to the natural radiation dose received by marine biota as well as humans consuming seafoods. Results from studies spanning nearly 5 decades show that 210 Po concentrations in organisms vary widely among the different phylogenic groups as well as between the different tissues of a given species. Such variation results in 210 Po concentration factors ranging from approximately 10 3 to over 10 6 depending upon the organism or tissue considered. 210 Po/ 210 Pb ratios in marine species are generally greater than unity and tend to increase up the food chain indicating that 210 Po is preferentially taken up by organisms compared to its progenitor 210 Pb. The effective transfer of 210 Po up the food chain is primarily due to the high degree of assimilation of the radionuclide from ingested food and its subsequent strong retention in the organisms. In some cases this mechanism may lead to an apparent biomagnification of 210 Po at the higher trophic level. Various pelagic species release 210 Po and 210 Pb packaged in organic biodetrital particles that sink and remove these radionuclides from the upper water column, a biogeochemical process which, coupled with scavenging rates of this radionuclide pair, is being examined as a possible proxy for estimating downward organic carbon fluxes in the sea. Data related to preferential bioaccumulation in various organisms, their tissues, resultant radiation doses to these species, and the processes by which 210 Po is transferred and recycled through the food web are discussed. In addition, the main gaps in our present knowledge and proposed areas for future studies on the biogeochemical behaviour of 210 Po and its use as a tracer of oceanographic

  13. Synthesis of flower-like LiMnPO4/C with precipitated NH4MnPO4·H2O as precursor

    International Nuclear Information System (INIS)

    Liu Jiali; Hu Dongge; Huang Tao; Yu Aishui

    2012-01-01

    Highlights: ► Flower-like NH 4 MnPO 4 ·H 2 O is obtained by novel precipitating method. ► It is used as the precursor to synthesize LiMnPO 4 /C. ► Subsequent heat treatment would not destroy the precursor morphology. ► As-prepared LiMnPO 4 /C showed discharge capacity of 85 mAh/g at 0.05 C. - Abstract: Ammonium magnesium phosphate monohydrate (NH 4 MnPO 4 ·H 2 O) precursor was prepared by a novel precipitating process with manganese citrate complexes as intermediate. The morphology of the precursor observed by Scanning Electron Microscope (SEM) was flower-like which was self-assembled by plate-like particles. Further analysis by X-ray diffraction (XRD) revealed that the lattice of the plate crystal was orientated along (0 1 0) plane. By solid-state reaction of the precursor, with lithium acetate and glucose as carbon source, pure olivine structured LiMnPO 4 /C composite was obtained and meanwhile, the original flower-like morphology could be retained.

  14. Investigation of the Na2(H2PO2)2 - Ba(H2PO2)2 - H2O Water-Salt Ternary System at Room Temperature

    OpenAIRE

    Erge, Hasan; Turan, Hakan; Kul, Ali Riza

    2016-01-01

    Objective: In this study, the solubility, density, conductivity and phase equilibria of the Na2(H2PO2)2-Ba(H2PO2)2-H2O ternary system located in the structure of the Na+, Ba2+, (H2PO2)-//H2O quaternary reciprocal water-salt system were investigated using physicochemical analysis methods. Material and Methods: Riedel-de Haen and Merck salts were used to investigate the solubility and phase equilibria of the Na2(H2PO2)2 -Ba(H2PO2)2-H2O ternary water–salt system at room temperature Res...

  15. On the existence of PbBi3PO8

    International Nuclear Information System (INIS)

    Steinfink, H.; Dass, R.I.; Lynch, V.; Harlow, R.L.; Lee, P.L.

    2005-01-01

    The title compound crystallizes in the tetragonal system, a = 11.733(2) A, c = 15.587(3) A, I4 mm, Z = 10. Data were collected at the Argonne National Laboratory synchrotron source at λ = 0.15359 A. Least squares refinement on F 2 converged to R1 = 0.039. The oxygen coordination polyhedra around Bi and Pb display the distortions typical of 6s 2 lone-pair atoms. One Bi is disordered. Bi-O bonds vary from 2.08(2) to 2.96(1) A. One Pb is in cubic coordination to oxygen and the second Pb is bonded to six oxygen atoms that form a rectangular pyramid and a seventh oxygen is off one of the rectangular faces of the pyramid. Pb-O bonds vary from 2.303(6) to 2.804(17) A. Of the two crystallographically independent P one is in a single tetrahedral coordination while the second is at the center of two disordered tetrahedra. Units of OM 4 tetrahedra, M = Bi/Pb, articulate into a three-dimensional framework by corner and edge sharing that is strengthened by corner sharing with PO 4 moieties

  16. Determination of 210Pb and 210Po in water samples

    International Nuclear Information System (INIS)

    Ayranov, M.; Tosheva, Z.; Kies, A.

    2004-01-01

    Lead-210 and Polonium-210 are naturally occurring members of the Uranium-238 decay series. They could be found in various environmental samples, such as groundwater, fish and shellfish, contributing an important component of the human natural radiation background. For this reason the development of a fast, reproducible and sensitive method for determination of 210 Pb and 210 Po is of a great concern. The aims of our study were to adopt procedures for radiochemical separation of these radionuclides and radioanalytical methods for their determination. The combination of electrochemical deposition, co-precipitation and extraction chromatography gives the opportunity for fast and effective radiochemical separation of the analytes. Polonium was spontaneously plated on copper disk from the stock solution. Lead was co-precipitated with Fe(OH) 3 and further purified by extraction chromatography on Sr Spec columns. Alpha spectra of polonium were collected on Canberra PIPS detectors with 900 mm 2 active surface. The activities of lead were determined by LSC (Gardian Wallac Oy). The minimum detectable activities for sample size 1000 mL and chemical yield of 88 % for the polonium and 85 % for the lead are presented. The proposed method proved to be fast, accurate and reproducible for routine determination of lead and polonium in environmental water samples. (authors)

  17. Performing Organization Sebuah Format Pengembangan Organisasional (PO Dalam Era Perubahan

    Directory of Open Access Journals (Sweden)

    Noor Arifin

    2009-08-01

    Full Text Available Ciri utama organisasi masa depan menurut Alfin Tofler adalah fleksibilitas, kreativitas, dan inovasi (enterpreneurship. Apa yang harus dilakukan oleh manajemen agar organisasi yang dipimpinnnya mampu mem¬pertahankan eksistensinya dalam gelombang perubahan tersebut? Perubahan di masa depan akan semakin dahsyat dan radikal, menembus ke segala segi kehidupan. Para anggota dan pimpinan organisasional pada se¬mua jajarannya akan dituntut kerja keras, dibarengi dengan menciptakan metode yang mutakhir, teknologi tinggi yang canggih, prosedur yang ringkas dan jelas, perumusan kebijaksanaan yang transparan dan selalu member¬dayakan karyawan (employee empowerment.Format PO masa depan yang bisa survive terhadap perubahan adalah Performing Organizational yang senantiasa menciptakan strategi kecocokan (fit terhadap gejolak internal dan eksternal.Indonesia dalam menghadapi krisis sekarang perlu mencari solusi terbaik dan menyiapkan untuk menghadapi perdagangan bebas dunia. Untuk jangka pendek Indonesia perlu perubahan transformasi organi¬sasional (yang dilakukan secara radikal dengan benar agar krisis dapat berlalu. Namun untuk jangka panjang perlu mengkombinasikan perubahan internal dan mengantisipasi perubahan eksternal dengan menerapkan kon¬sep Performing Organizational. Konsep ini dapat dilaksanakan jika memang situasi dan kondisi memungkinkan, sehingga pendekatan yang dilakukan adalah contingency atau situasional.

  18. 210Po and 210Pb in a pelagic trophic chain

    International Nuclear Information System (INIS)

    Radakovitch, O.; Strady, E.; Veron, A.; Chiffoleau, J.F.; Tronczynski, J.; Harmelin-Vivien, M.

    2013-01-01

    The ANR-COSTAS program studied the bioaccumulation and biomagnification of organic and inorganic contaminants through the trophic chains of two small pelagic fish, anchovy and sardine, on the continental shelf of the Gulf of Lion (Northwestern Mediterranean Sea). 210 Po and 210 Pb were analysed at various levels of this trophic chain, as well as trace metal elements, lead isotopes and C and N isotopes which provide additional information on both biogeochemical cycles and trophic transfer. To our knowledge, this is the first time that an entire trophic chain is analysed for these two radionuclides. Water, suspended particles, phytoplankton and zooplankton were collected at 7 stations during two contrast seasons. Phyto and zooplankton were separated in 6 classes through size-sieving: 6-60 μm; 60-200; 200-500; 500-1000; 1000-2000 and > 2000 μm. Anchovy and sardine were collected also two times and analyses were performed on muscle and liver independently for both sexes

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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

  20. High efficient multifunctional Ag_3PO_4 loaded hydroxyapatite nanowires for water treatment

    International Nuclear Information System (INIS)

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

    2015-01-01

    Highlights: • The multifunctional Ag_3PO_4 loaded hydroxyapatite (HAP) nanowires were synthesized via a facile in-situ precipitation method. • By optimizing the initial concentration of AgNO_3, the well-distributed Ag_3PO_4/HAP composites could be achieved. • The Ag_3PO_4/HAP composites showed excellent photocatalytic performance for the decomposition of dyes under visible light irradiation. • The maximum absorption capacity of the Ag_3PO_4/HAP composites for Pb(II) was 250 mg/g, approximately three times as that of pure HAP. • The Ag_3PO_4/HAP composites also exhibited excellent antibacterial activities even at relative low concentrations. - Abstract: Organic, inorganic, and biological pollutants are typical water contaminants and they seriously affect water quality. In this study, we suggested that a novel multifunctional Ag_3PO_4 loaded hydroxyapatite (HAP) material can remove the typical pollutants from water. The Ag_3PO_4/HAP composites were synthesized facilely via in-situ precipitation of Ag_3PO_4 on the pre-existing HAP nanowires. By optimizing the composition of Ag_3PO_4 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 Ag_3PO_4/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 Ag_3PO_4 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 Ag_3PO_4/HAP composite might be developed

  1. Model analysis of the relationship between intracellular Po2 and energy demand in skeletal muscle

    OpenAIRE

    Spires, Jessica; Gladden, L. Bruce; Grassi, Bruno; Saidel, Gerald M.; Lai, Nicola

    2012-01-01

    On the basis of experimental studies, the intracellular O2 (iPo2)-work rate (WR) relationship in skeletal muscle is not unique. One study found that iPo2 reached a plateau at 60% of maximal WR, while another found that iPo2 decreased linearly at higher WR, inferring capillary permeability-surface area (PS) and blood-tissue O2 gradient, respectively, as alternative dominant factors for determining O2 diffusion changes during exercise. This relationship is affected by several factors, including...

  2. Additional radiation exposure of the smoker from Pb-210 and Po-210

    International Nuclear Information System (INIS)

    Gloebel, B.

    1985-01-01

    The content in Pb-210 and Po-210 was measured in 100 packs of cigarettes. Both nuclides exist in a radioactive equilibrium. 4 mBq per cigarette were measured on average. With artificially smoked cigarettes 50% of the Pb and 85% of Po are detectable in the smoke. Smoking, therefore, leads to an increased radiation exposure, in particular of the lungs. Owing to a metabolic behaviour the increased radiation exposure of the lungs is caused by Po. Smoking 30 cigarettes a day will lead to an additional load on the lungs of about 20 mrad/a. (orig.) [de

  3. Synthesis and crystal structure of acid indium phosphite In(H3PO3)3

    International Nuclear Information System (INIS)

    Zakharova, B.S.; Chudinova, N.N.; Ilyhkhin, A.B.

    1996-01-01

    A group of isostructural acid phosphites of trivalent metals M(H 2 PO 3 ) 3 , where M 3 =V, Fe, Ga, In, was synthesized. Crystal structure of In(H 2 PO 3 ) 3 was determined. The compound crystallizes in hexagonal syngony, a = 8.414(2), c = 7.069(2) A, V = 433.3(2) A 3 , Z = 2, sp.gr. P6 3 . In (H 2 PO 3 ) 3 structure is of frame type. 9 refs.; 3 tabs

  4. Levels of {sup 210} Pb and {sup 210} Po in Brazilian cigarettes

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Pedro Lopes dos; Kelecom, Alphonse; Gouvea, Rita de Cassia dos Santos; Dutra, Iedo Ramos [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Biologia Geral

    1996-12-01

    {sup 210} Po and {sup 210} Pb concentrations have been determined in 18 Brazilian cigarette samples and compared with known data on U content. U is respectively 3-fold less and 4-fold less abundant than {sup 210} Po or {sup 210} Pb. No correlation could be observed between U concentration and those of Po or Pb. The mean concentration of {sup 210} Pb is higher than that of {sup 210} Pb observed in many other plants, even in plants frown in high background areas. (author) 19 refs., 1 fig., 1 tab.

  5. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    Energy Technology Data Exchange (ETDEWEB)

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro; Carrington, Antony; /Bristol U.; Cox, Catherine; Kauzlarich, Susan M.; Hope, Hakon; /UC, Davis. Dept. Chem.

    2010-02-15

    We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.

  6. 210Po measurement of borehole core and its significance for uranium exploration

    International Nuclear Information System (INIS)

    Chao Xiaolin

    2007-01-01

    210 Po survey is a tradition method in uranium exploration and has been widely applied to ground reconnaissance survey and detailed survey of uranium. However, it is seldom applied to drilling work. 210 Po measurements of borehole core for granite-type uranium deposit in Miaoershan area indicate that there are high and large range anomaly which greatly exceeds uranium orebody in uranium mineralization area. The investigation suggests that 210 Po measurements of borehole core can judge whether or not exist buried uranium orebody under the borehole depth and its surrounding in the final exploration stage. The method may be used to the exploration of granite-type uranium deposit. (authors)

  7. Volatility of 210Po in airborne dusts in an atmosphere of nitrogen

    International Nuclear Information System (INIS)

    Abe, Michiko; Abe, Siro; Ikeda, Nagao.

    1976-01-01

    Volatilization behavior of 210 Po contained in airborne dusts in the temperature range of 200 - 800 0 C was investigated in an atmosphere of nitrogen. It was revealed that the volatilization of 210 Po in airborne dusts in an atmosphere of nitrogen as a function of temperature can be expressed in a stairlike shape with two steps. This tendency is similar to the previous results obtained in air. The previous and present data may suggest that 210 Po in airborne dusts consists of two or more different kinds of chemical species. (auth.)

  8. Content of [sup 210]Pb and [sup 210]Po in main foods of Hunan province

    Energy Technology Data Exchange (ETDEWEB)

    Jiaquan, Yan [Hunan Inst. for Labour Hygiene, Propylaxis and Treatment of Occupational Diseases (China); Radiological Health Group collabrated

    1992-03-01

    Investigation results were reported of content of [sup 210]Pb and [sup 210]Po in main foods of Hunan province from 1988 to early 1989. The content of [sup 210]Pb and [sup 210]Po in 17 kinds of foods investigated ranges from 0.02 to 11.8 Bqkg[sup -1] and from 0.04 to 15.6 Bqkg[sup -1] respectively. The estimated committed dose equivalents of residents were 102.6 [mu]Sv and 29.6 [mu]Sv for [sup 210]Pb and [sup 210]Po taken through foods respectively.

  9. Is ecological food also radioecological? - 210Po and 210Pb studies.

    Science.gov (United States)

    Strumińska-Parulska, Dagmara; Olszewski, Grzegorz

    2018-01-01

    Presented are results of a study on accumulation of naturally occurring 210 Po and 210 Pb in ecological and conventional farming food products in Poland: fruits, vegetables and cereals. The main idea behind this research was to determine the activity concentrations of 210 Po and 210 Pb in ecological and commercial food as well as calculate and compare the effective dose (radiation) connected to different origin of analyzed food products consumption. The studies showed the majority of all compared food samples contained similar 210 Po and 210 Pb activities and statistically, the consumption of organic and commercial food would give similar annual effective dose. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Content of 210Pb and 210Po in main foods of Hunan province

    International Nuclear Information System (INIS)

    Yan Jiaquan

    1992-01-01

    Investigation results were reported of content of 210 Pb and 210 Po in main foods of Hunan province from 1988 to early 1989. The content of 210 Pb and 210 Po in 17 kinds of foods investigated ranges from 0.02 to 11.8 Bqkg -1 and from 0.04 to 15.6 Bqkg -1 respectively. The estimated committed dose equivalents of residents were 102.6 μSv and 29.6 μSv for 210 Pb and 210 Po taken through foods respectively

  11. Connected Lighting Systems Efficiency Study$-$ PoE Cable Energy Losses, Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Tuenge, Jason [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kelly, Karsten [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Poplawski, Michael [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-11-30

    First report in a study of the efficiency of connected lighting systems. The report summarizes the results of an exploratory study investigating power losses in Ethernet cables used between PoE switches and luminaires in PoE connected lighting systems. Testing was conducted at the Pacific Northwest National Laboratory (PNNL) Connected Lighting Test Bed in September 2017. The results were analyzed to explore the impact of cable selection on PoE lighting system energy efficiency, as well as the effectiveness of guidelines recently introduced by the American National Standards Institute (ANSI) C137 Lighting Systems Committee.

  12. [100]-Oriented LiFePO4 Nanoflakes toward High Rate Li-Ion Battery Cathode.

    Science.gov (United States)

    Li, Zhaojin; Peng, Zhenzhen; Zhang, Hui; Hu, Tao; Hu, Minmin; Zhu, Kongjun; Wang, Xiaohui

    2016-01-13

    [100] is believed to be a tough diffusion direction for Li(+) in LiFePO4, leading to the belief that the rate performance of [100]-oriented LiFePO4 is poor. Here we report the fabrication of 12 nm-thick [100]-oriented LiFePO4 nanoflakes by a simple one-pot solvothermal method. The nanoflakes exhibit unexpectedly excellent electrochemical performance, in stark contrast to what was previously believed. Such an exceptional result is attributed to a decreased thermodynamic transformation barrier height (Δμb) associated with increased active population.

  13. Synthesis of g-C3N4/Ag3PO4 heterojunction with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

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

    2014-01-01

    Graphical abstract: g-C 3 N 4 /Ag 3 PO 4 heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The results show that g-C 3 N 4 /Ag 3 PO 4 possesses a much higher activity for the decomposition of RhB than that of the pure Ag 3 PO 4 particles. The most mechanism is that g-C 3 N 4 /Ag 3 PO 4 heterojunction photocatalyst can efficiently separate the photogenerated electron–hole pairs, enhancing the photocatalytic activity of g-C 3 N 4 /Ag 3 PO 4 composites. - Highlights: • g-C 3 N 4 /Ag 3 PO 4 heterojunction showed much higher activity than that of Ag 3 PO 4 . • The high activity could be attributed to g-C 3 N 4 for modifying Ag 3 PO 4 . • More ·OH radicals may be significant reason to improve Ag 3 PO 4 activity. - Abstract: g-C 3 N 4 /Ag 3 PO 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 3 N 4 /Ag 3 PO 4 decomposed RhB more effectively than the pure Ag 3 PO 4 particles did, and 2 wt.% g-C 3 N 4 had the highest activity. Furthermore, 2 wt.% g-C 3 N 4 /Ag 3 PO 4 degraded high-concentration RhB more potently than unmodified Ag 3 PO 4 did, probably because g-C 3 N 4 /Ag 3 PO 4 heterojunction photocatalyst enhanced the photocatalytic activity by efficiently separating the photogenerated electron–hole pairs

  14. High pressure experimental studies on Na3Fe(PO4)(CO3) and Na3Mn(PO4)(CO3): Extensive pressure behaviors of carbonophosphates family

    Science.gov (United States)

    Gao, Jing; Huang, Weifeng; Wu, Xiang; Qin, Shan

    2018-04-01

    Carbon-bearing phases in the Earth's interior have profound implications for the long-term Earth carbon cycle. Here we investigate high-pressure behaviors of carbonophosphates bonshtedtite Na3Fe(PO4)(CO3) and sidorenkite Na3Mn(PO4)(CO3) in diamond anvil cells up to ∼12 GPa at room temperature. Modifications in in situ synchrotron X-ray diffraction patterns and Raman spectra confirm the structural stability of carbonophosphates within the pressure region. Fitting the third-order Birch-Murnaghan equation of state to the volume compression curve, the isothermal bulk modulus parameters are obtained to be K0 = 56(1) GPa, K0' = 3.3(1), V0 = 303.3(3) Å3 for Na3Fe(PO4)(CO3) and K0 = 54(1) GPa, K0' = 3.4(1), V0 = 313.4(2) Å3 for Na3Mn(PO4)(CO3). Crystallographic axes exhibit an elastic anisotropy with a more compressible c-axis relative to the ab-plane. An inverse linear correlation between the K0 value and the ionic radius of M2+ (M = Mg, Fe, Mn) is well determined for carbonophosphates. The pressure-dependence responsiveness of [PO4] and [CO3] in carbonophosphates show a negative relationship to the M2+ radius. We also discussed the effect of [PO4] group on the structural variations and high-pressure behaviors of carbonates. Furthermore, the geochemical properties of carbonophosphates hold implications to diamond genesis.

  15. PEMODELAN KONDUKTIVITAS ION DALAM STRUKTUR Li2Sc3(PO43 (Modeling Ionic Conductivity in Li2Sc3(PO43 Structure

    Directory of Open Access Journals (Sweden)

    Akram La Kilo

    2011-11-01

    Full Text Available ABSTRAK Fasa Li2Sc3(PO43 merupakan material konduktor superionik yang dapat diaplikasikan sebagai baterai yang dapat diisi ulang (rechargeable. Ion Li+ dalam struktur Li2Sc3(PO4 dapat mengalami migrasi dari posisi terisi ke posisi kosong. Penelitian ini telah memodelkan migrasi ion Li+ dalam struktur Li2Sc3(PO4 dengan menggunakan metode bond valence sum (BVS. Metode ini dapat memprediksi bilangan oksidasi suatu atom berdasarkan jarak dengan atom-atom tetangga. Source code berbasis BVS yang digunakan adalah JUMPITER yang mensimulasi efek gaya listrik eksternal yang bertindak pada ion litium sehingga nilai BVS litium dapat dipetakan terhadap jarak. Hasil simulasi menunjukkan bahwa konduksi ion Li+ dapat terjadi pada arah [010], [101], dan [120]. Namun, lintasan konduksi ion Li+ lebih mudah terjadi pada arah [120] atau bidang ab dengan nilai maksimum BVS adalah 0,982. ABSTRACT g-phase of Li2Sc3(PO43 is a lithium super ionic conductor which can be applied as a rechargeable lithium battery. Lithium ions of g-Li2Sc3(PO43 can migrate from occupied site to vacant site. In this research, simulation of Li+ ions migration in the structure of g-Li2Sc3(PO43 carried out using bond valence sum (BVS to predict the oxidation state of Li+ion based on the distance of the ion to neighboring atoms. BVS-based code used JUMPITER to simulate the effect of external electrical force acting on the lithium ions to produce the lithium BVS value which can be mapped to the distance. The simulation results shows that Li+ ion conduction can be occurred on [010], [101], and [120] directions. However, the Li ion conduction pathway occur more easily in the direction of [120] or ab plane with the BVS maximum value is 0.982.

  16. Synthesis and Characterization of New Nickel Phosphates, ANi4(PO4)3 (A=K, Rb)

    International Nuclear Information System (INIS)

    Im, Yoonmi; Kim, Pilsoo; Yun, Hoseop

    2014-01-01

    Quaternary nickel orthophosphates, ANi 4 (PO 4 ) 3 (A=Alkali metals) have been extensively investigated because they show interesting properties such as ionic conductivities, optical, and magnetic behaviors. They are built up from NiO 6 octahedra and PO 4 tetrahedra. These basic building blocks are connected via common oxygen atoms to form the three-dimensional frameworks and the alkali metal ions reside in the empty space. For NaNi 4 (PO 4 ) 3 , two different structures have been reported and this can be caused by the different reaction conditions. While NaNi 4 (PO 4 ) 3 prepared as single crystals with the use of NaCl flux at 1373 K crystallizes in the space group Amam and show a partial disorder of one of the PO 4 tetrahedra, NaNi 4 (PO 4 ) 3 and KNi 4 (PO 4 ) 3 synthesized with alkali metal nitrate at 1073 K as powders adopt an ordered structure with the space group Pnnm. As far as we know, no structural studies of KNi 4 (PO 4 ) 3 from single crystal diffraction data have been reported yet and RbNi 4 (PO 4 ) 3 is a new compound. In this paper we report on the synthesis and structural investigations using single crystals of two nickel orthophosphates, KNi 4 (PO 4 ) 3 and RbNi 4 (PO 4 ) 3

  17. Photoluminescence and thermoluminescence characterization of Eu3+- and Dy3+ -activated Ca3(PO4)2 phosphor

    International Nuclear Information System (INIS)

    Nagpure, I.M.; Saha, Subhajit; Dhoble, S.J.

    2009-01-01

    Rare-earth-doped polycrystalline Ca 3 (PO 4 ) 2 :Eu, Ca 3 (PO 4 ) 2 :Dy and Ca 3 (PO 4 ) 2 :Eu,Dy phosphors prepared by a modified solid-state synthesis has been studied for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) characteristics. The PL emission spectra of the phosphor suggest the presence of Eu 3+ ion in Ca 3 (PO 4 ) 2 :Eu and Dy 3+ ion in Ca 3 (PO 4 ) 2 :Dy lattice sites. The TL glow curve of the Ca 3 (PO 4 ) 2 :Eu compounds has a simple structure with a prominent peak at 228 deg. C, while Ca 3 (PO 4 ) 2 :Dy peaking at 146 and 230 deg. C. TL sensitivity of phosphors are compared with CaSO 4 : Dy and found 1.52 and 1.20 times less in Ca 3 (PO 4 ) 2 :Eu and Ca 3 (PO 4 ) 2 :Dy phosphors, respectively. The Ca 3 (PO 4 ) 2 :Eu,Dy phosphors shows switching behavior under two different excitation wavelengths and enhancement in PL intensity of Dy 3+ ions were reported. The paper discusses the photoluminescence and thermoluminescence behavior of Eu 3+ and Dy 3+ ion in Ca 3 (PO 4 ) 2 hosts, it may be applicable to solid-state lighting as well as thermoluminescence dosimetry applications.

  18. Structural and electrochemical studies of PPy/PEG-LiFePO4 cathode material for Li-ion batteries

    International Nuclear Information System (INIS)

    Fedorkova, Andrea; Nacher-Alejos, Ana; Gomez-Romero, Pedro; Orinakova, Renata; Kaniansky, Dusan

    2010-01-01

    A simple chemical oxidative polymerization of pyrrole (Py) directly onto the surface of LiFePO 4 particles was applied to the synthesis of polypyrrole-LiFePO 4 (PPy-LiFePO 4 ) powder. The LiFePO 4 sample without carbon coating was synthesized by a solvothermal method. The polyethylene glycol (PEG) was used as additive during Py polymerization for increasing the PPy-LiFePO 4 conductivity. Properties of resulting LiFePO 4 , PPy-LiFePO 4 and PPy/PEG-LiFePO 4 samples were characterized by XRD, SEM, TGA and galvanostatic charge-discharge measurements. These methods confirmed the presence of polypyrrole on LiFePO 4 particles and its homogeneous distribution in the resulting powder material. The PPy/PEG-LiFePO 4 composites show higher discharge capacity than pure LiFePO 4 , as PPy/PEG network improves the electron conductivity. It presents specific discharge capacity of 153 mAh/g at C/5 rate.

  19. Optical and crystal chemistry studies of Na3Ln(PO4)2-K3Ln(PO4)2 (Ln=Eu, Gd)

    International Nuclear Information System (INIS)

    Mesnaoui, M.; Maazaz, M.

    1987-01-01

    In these systems, large single phase domains are separated by two phase regions. The structural evolution as a function of composition is analysed both by X-ray diffraction and by using Eu 3+ and Gd 3+ as luminescent local structural probes. Due to layer type structure of the K 3 Ln(PO 4 ) 2 phases an exchange reaction resulting in total substitution of sodium for potassium can be carried out with formation of metastable Na 3 Ln(PO 4 ) 2 phases, the structure of which is close to those of the potassium compounds. 10 refs.; 18 figs [fr

  20. Conductivity of Composite Material Based on System NdPO4·nH2OCsH2PO4

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Bjerrum, Niels J.; Li, Qingfeng

    2013-01-01

    The goal of the present study was to obtain a comprehensive knowledge about synthesis conditions, structure, thermal behavior and conductivity properties of neodymiumorthophosphates in order to analyze of use this material in intermediate temperature fuel cells due to their thermal and chemical...... stability properties.The impedance spectroscopy technique (IS) was used to measure the conductivity. The conductivity of composites observed to be lower than conductivity of pure CsH2PO4 but had improved sufficiently conductivity of pure NdPO4·nH2O...

  1. Vanishing of T sub c and appearance of quantum paraelectricity in KD sub 2 PO sub 4 and KH sub 2 PO sub 4 under high pressure

    CERN Document Server

    Endo, S; Tokunaga, M

    2002-01-01

    The temperature dependences of the dielectric constants of the hydrogen-bond ferroelectrics KH sub 2 PO sub 4 (KDP) and KD sub 2 PO sub 4 (DKDP) were measured under high hydrostatic pressure. Their ferroelectric transition temperatures T sub c monotonically decreased with increasing pressure and the ferroelectric state vanished at p sub c : 1.7 GPa for KDP and 6.1 GPa for DKDP. On the other hand, the Curie constant remained finite at p sub c , which indicates that the ferroelectric phase transition at high pressure is of displacive type. At pressures around p sub c , quantum paraelectricity was observed in KDP and DKDP.

  2. Sup(210)Pb and 210Po distributions and disequilibrium in the coastal and shelf waters of the southern North Sea

    International Nuclear Information System (INIS)

    Zhizheng, Zuo; Eisma, Doeke

    1993-01-01

    Concentration profiles of 210 Pb and 210 Po were measured at 10 stations in the coastal and shelf areas of the southern North Sea. Scavenging processes in this study area are revealed by 210 Po/ 210 Pb disequilibrium and their distributions in the water column. Results for 210 Po show strong excess, relative to 210 Pb, in both dissolved and particulate forms, indicating an additional flux of 210 Po from the coastal and shelf sediment. A significant maximum of the dissolved 210 Po and 210 Pb over the fine grained depositional area (Oyster Ground) was observed to correspond with resuspension of the underlying muddy sediments. A comparison of the data between the water and sediment columns shows that the excess of 210 Po found in the water body could be balanced by only a small amount of deficit of 210 Po in the sediment, due to the characteristics of this continental shelf area. (author)

  3. Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures

    Science.gov (United States)

    Liu, Ruoyu; Hu, Peiguang; Chen, Shaowei

    2012-10-01

    Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.

  4. Inelastic neutron scattering and lattice dynamics of GaPO4

    International Nuclear Information System (INIS)

    Mittal, R.; Chaplot, S.L.; Kolesnikov, A.I.; Loong, C.K.; Jayakumar, O.D.; Kulshreshtha, S.K.

    2004-01-01

    We report here measurements of phonon spectrum and lattice dynamical calculations for GaPO 4 . The measurements in low-cristobalite phase of GaPO 4 are carried out using high-resolution medium-energy chopper spectrometer at ANL, USA in the energy transfer range 0-160 MeV. Semiempirical interatomic potential in GaPO 4 , previously determined using ab-initio calculations have been widely used in studying the phase transitions among various polymorphs. The calculated phonon spectrum using the available potential show fair agreement with the experimental data. However, the agreement between the two is improved by including the polarisability of the oxygen atoms in the framework of the shell model. The lattice dynamical models are also exploited for calculations of various thermodynamic properties of GaPO 4 . (author)

  5. Measuring interstitial pH and pO2 in mouse tumors.

    Science.gov (United States)

    Jain, Rakesh K; Munn, Lance L; Fukumura, Dai

    2013-07-01

    This protocol outlines methods to measure two extravascular parameters, interstitial pH and partial pressure of oxygen (pO2), in mouse tumors. The method for measuring interstitial pH uses fluorescence ratio imaging microscopy (FRIM) of the pH-sensitive fluorescent dye 2',7'-bis-(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). The method for measuring interstitial pO2 is based on the oxygen-dependent quenching of the phosphorescence of albumin-bound palladium meso-tetra(4-carboxyphenyl)porphyrin, and can be used to measure microvascular as well as interstitial pO2. In addition, the two methods can be used sequentially to measure both pH and pO2 in the same tissues.

  6. Intake of 210Po, 234U and 238U radionuclides with beer in Poland

    International Nuclear Information System (INIS)

    Skwarzec, B.; Struminska, D.I.; Borylo, A.; Falandysz, J.

    2004-01-01

    238 U, 234 U and 210 Po activity concentrations were determined in beer in Poland by alpha-spectrometry with low-level activity silicon detectors. The results revealed that the mean concentrations of 238 U, 234 U and 210 Po in the analyzed beer samples were 4.63, 4.11 and 4.94 mBq x dm -3 , respectively, the highest in Tyskie (5.71 for 210 Po, 5.06 for 234 U and 6.11 for 238 U) and the lowest in Lech (2.49 for 210 Po). The effective radiation dose due to uranium and polonium ingestions by beer was calculated and were compared to the effective radiation dose from drinking water. (author)

  7. Po-210 high levels in aquatic plants of the Carapebus sandbank, RJ, Brazil

    International Nuclear Information System (INIS)

    Kelecom, Alphonse; Santos, Pedro Lopes dos; Gouvea, Rita de Cassis S.; Dutra, Iedo Ramos; Fevereiro, Paulo Cesar Ayres

    1999-01-01

    210 Po concentration have been determined in one green alga and in five freshwater plants grown in a pond of the Carapebus restinga (state of Rio de Janeiro). The alga Chara sp showed elevated concentration of 210 Po, similar to that observed in marine algae. All the other plants had the lowest concentration of 210 Po in the stems and the highest in the roots. Intermediate values were observed in the leaves. The unexpected high concentration of 210 Po in the roots, even superior to reported values for roots of plants from high radioactive background areas, must be due to the elevated levels of this radionuclide in associated soils that are known to be rich in humic organic material. There seem to have no translocation of this radionuclide from the roots to the other parts of the plants. (author)

  8. Structural and electrochemical properties of Cl-doped LiFePO{sub 4}/C

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C.S.; Zhang, Y.; Zhang, X.J.; Zhou, Z. [Institute of New Energy Material Chemistry, Nankai University, Tianjin 300071 (China)

    2010-06-01

    Cl-doped LiFePO{sub 4}/C cathode materials were synthesized through a carbothermal reduction route, and the microstructure and electrochemical performances were systematically studied. Cl-doped LiFePO{sub 4}/C cathode materials presented a high discharge capacity of {proportional_to}90 mAh g{sup -1} at the rate of 20 C (3400 mA g{sup -1}) at room temperature. Electrochemical impedance spectroscopy and cyclic voltamperometry indicated the optimized electrochemical reaction and Li{sup +} diffusion in the bulk of LiFePO{sub 4} due to Cl-doping. The improved Li{sup +} diffusion capability is attributed to the microstructure modification of LiFePO{sub 4} via Cl-doping. (author)

  9. Quantitative evaluation of 218Po behaviour in air in an artificial environment

    International Nuclear Information System (INIS)

    Yajima, K.; Hirao, S.; Moriizumi, J.; Yamazawa, H.

    2015-01-01

    Experiments were carried out in a small enclosed booth for the purpose of understanding and modelling 218 Po behaviour. The experiment was conducted under two kinds of conditions without and with injection of incense smoke. A working model of 218 Po behaviour was applied to analyse the measured data. Under the condition without incense smoke, temporal changes in aerosol-attached and unattached 218 Po concentrations were successfully reproduced by the model. The deposition rate of unattached fraction and the rate of attachment were determined by the working model. Under the condition with incense smoke, temporal changes in 218 Po concentration were poorly simulated by the model. This can be attributed to the significantly increased aerosol concentration in small size ranges which is not properly considered in the attachment rate calculation in the model. (authors)

  10. Na3Tb(PO4)2: Synthesis, crystal structure and greenish emitting properties

    Science.gov (United States)

    Zhao, Dan; Ma, Zhao; Liu, Bao-Zhong; Zhang, Rui-Juan; Wu, Zhi-Qiang; Wang, Jian; Duan, Pei-Gao

    2018-03-01

    A anhydrous orthoborate Na3Tb(PO4)2 has been prepared and its crystal structure was determined by X-Ray diffraction of a non-merohedral twinned single crystal. The results show that the compound crystallizes in monoclinic space group C2/c and the structure features a 3D framework containing PO4, NaO6, NaO7, NaO8 and TbO8 polyhedra. Under near-UV excitation (370 nm), Na3Tb(PO4)2 shows intense characteristic emission bands of Tb3+ (490 nm, 543 nm, 585 nm and 620 nm) with the CIE coordinate of (0.3062, 0.5901), corresponding to greenish color. The excitation spectrum covers a wide range from 340 nm to 390 nm, which indicates that phosphor Na3Tb(PO4)2 can be efficiently activated by near-UV LED ship.

  11. Supercapacitors studies on BiPO4 nanoparticles synthesized via a simple microwave approach

    Directory of Open Access Journals (Sweden)

    S. Vadivel

    2017-07-01

    Full Text Available BiPO4 nanomaterial was synthesized using EDTA (ethylene diamine tetra acetic acid as the surfactant via a simple microwave method. The structure and morphology of BiPO4 were systematically characterized by X-ray diffraction (XRD, Fourier-transform infrared spectroscopy (FT-IR, and scanning electron microscopy (FE-SEM studies. The obtained BiPO4 nanoparticles were, on average, 150–300 nm. The electrochemical results showed that the specific capacitance of BiPO4 obtained using the microwave route was up to 104 Fg−1 at a current density of 1 Ag−1 with a large potential window of 1.7 V. The material showed excellent cycling stability (92% capacitance retention after 500 cycles at a current density of 1 Ag−1.

  12. Ekspert po SMI : Nuzhno tshotko ukazõvat na zakaznoi material / Ksenia Repson

    Index Scriptorium Estoniae

    Repson, Ksenia

    2007-01-01

    Telekanalis Pervõi Baltiiskii Kanal näidatud film Keskerakonna esimehest Edgar Savisaarest " Po prozvishtshu Nossorog" oli tehtud Keskerakonna tellimusel. Meediaeksperdi Tarmu Tammerki arvamus reklaamtelesaadete või -filmide nõuete kohta

  13. Probing the failure mechanism of nanoscale LiFePO4 for Li-ion batteries

    International Nuclear Information System (INIS)

    Gu, Meng; Yan, Pengfei; Wang, Chongmin; Shi, Wei; Zheng, Jianming; Zhang, Ji-guang

    2015-01-01

    LiFePO 4 is a high power rate cathode material for lithium ion battery and shows remarkable capacity retention, featuring a 91% capacity retention after 3300 cycles. In this work, we use high-resolution transmission electron microscopy and electron energy loss spectroscopy to study the gradual capacity fading mechanism of LiFePO 4 materials. We found that upon prolonged electrochemical cycling of the battery, the LiFePO 4 cathode shows surface amorphization and loss of oxygen species, which directly contribute to the gradual capacity fading of the battery. The finding can guide the design and improvement of LiFePO 4 cathode for high-energy and high-power rechargeable battery for electric transportation

  14. Levels and transfer of 210Po and 210Pb in Nordic terrestrial ecosystems

    DEFF Research Database (Denmark)

    Brown, J.E.; Gjelsvik, R.; Roos, Per

    2011-01-01

    concentrations of the main dose forming radionuclides 210Po and 210Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell...... exhibited an approximately exponential fall in 210Pb activity concentrations from elevated levels in humus/surface soils to “supported” levels at depth. Activity concentrations of 210Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123 Bq kg−1 d.w. and in plants and lichens between 20...... and 138 Bq kg−1 d.w.. The results showed that soil humus is an important reservoir for 210Po and 210Pb and that fauna in close contact with this media may also exhibit elevated levels of 210Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations...

  15. Luminescence and scintillation properties of LuPO4-Ce nanoparticles

    International Nuclear Information System (INIS)

    Vistovskyy, V.; Malyy, T.; Pushak, A.; Vas’kiv, A.; Shapoval, A.; Mitina, N.; Gektin, A.; Zaichenko, A.; Voloshinovskii, A.

    2014-01-01

    Study of the spectral-luminescence parameters of LuPO 4 -Ce nanoparticles upon the excitation by X-ray quanta and synchrotron radiation with photon energies of 4–25 eV was performed. Nanoparticles with mean size about a=35 nm and nanoparticles with size less than 12 nm reveal the different structures of cerium centers. Luminescence efficiency of LuPO 4 -Ce nanoparticles of a 4 -Ce nanoparticles studied using synchrotron and X-ray excitation. • Different structure of Ce 3+ -centers has been revealed for LuPO 4 -Ce nanoparticles. • Luminescence of LuPO 4 -Ce with size less than 12 nm is strongly quenched upon the X-ray excitation

  16. Electric quadruple moments of high-spin isomers in 209Po

    International Nuclear Information System (INIS)

    Ivanov, E.A.; Nicolescu, G.; Plostinaru, D.

    1998-01-01

    The electric quadrupole interaction of the 209 Po (17/2) - and (13/2) - isomers in a Bi single-crystal was measured. The results for the quadrupole moments are connected with studies of isomers in Po isotopes. A two level analysis procedure was employed for the combined data of (17/2) - and (13/2) - isomers. The quadrupole moments of the Po isotopes are of special interest for testing nuclear models because of supposed simple nuclear structure with two protons outside a closed magic number shell. While the g-factors are significant for the predominant few-particle structures often present at high spins, the quadrupole moments are sensitive to additional contributions arising from core deformation effects. A systematic study of quadrupole moments of 12 + isomers in Pb isotopes has indeed demonstrated that the valence neutron effective charge increases as more particle pairs are removed from the 208 Pb core. In the present work, quadrupole coupling constants were measured for the isomers by the time-differential perturbed angular distribution (TDPAD) technique, in the presence of quadrupole interactions from the internal electric field gradient (EFG) in Bi crystal. The experiments were performed using a pulsed deuteron-beam of 13 MeV. The (17/2) - isomer state (T 1/2 = 88 ns) and the (13/2) - isomer state (T 1/2 = 24 ns) were populated and aligned by the 209 Bi(d,2n) reaction. The repetition time of the pulse was 10 μs and the width was around 5 ns (FWHM). The rather low bombardment energy was chosen to reduce population of higher spin isomers and to optimize the population of 209 Po((17/2) - ) and 209 Po((13/2) - ). The 209 Po single crystal target was held at a temperature of 470 K in order to reduce possible radiation damage effects. The experiments have been performed with the c axis of the single crystal at 45 angle and 90 angle to the beam direction. We chose to use a calibration based on isomers with well-understood nuclear structure allowing a reliable

  17. Graphene Modified LiFePO4 Cathode Materials for High Power Lithium ion Batteries

    International Nuclear Information System (INIS)

    Zhou, X.; Wang, F.; Zhu, Y.; Liu, Z.

    2011-01-01

    Graphene-modified LiFePO 4 composite has been developed as a Li-ion battery cathode material with excellent high-rate capability and cycling stability. The composite was prepared with LiFePO 4 nanoparticles and graphene oxide nanosheets by spray-drying and annealing processes. The LiFePO 4 primary nanoparticles embedded in micro-sized spherical secondary particles were wrapped homogeneously and loosely with a graphene 3D network. Such a special nanostructure facilitated electron migration throughout the secondary particles, while the presence of abundant voids between the LiFePO 4 nanoparticles and graphene sheets was beneficial for Li + diffusion. The composite cathode material could deliver a capacity of 70 mAh g -1 at 60C discharge rate and showed a capacity decay rate of <15% when cycled under 10C charging and 20C discharging for 1000 times.

  18. Determination of 210Po in Slovak mineral waters by sorption on ZnS(Ag)

    International Nuclear Information System (INIS)

    Krivosik, M.

    2009-01-01

    In determining of 210 Po it was followed according to the Czech technical standard CSN 75 7626 Water quality - Determination of polonium-210. The aim of this work was to optimize the conditions for sorption of 210 Po on ZnS (Ag) from acidic environment from the model solutions. The effect of pH of the sample, its volume and the presence of NaCl on the sorption of 210 Po on ZnS (Ag) was studied. Three types of filters for filtering ZnS (Ag), Synpor, paper and glass fiber filters were tested. Bulk activity of 210 Po was determined in the samples of Slovak mineral waters and healing waters as well as in water samples from antimony mine (mine Rufus) near the village Poproc (rural Kosice district). (author)

  19. Carbon coatings with olive oil, soybean oil and butter on nano-LiFePO 4

    Science.gov (United States)

    Kim, Ketack; Jeong, Ji Hwa; Kim, Ick-Jun; Kim, Hyun-Soo

    Kitchen oils (olive, soybean and butter) are selected for carbon coatings on LiFePO 4. The surface properties of LiFePO 4 are unknown or vary depending on synthetic methods. The multi-functional groups of fatty acids in the oils can orient properly to cope with the variable surface properties of LiFePO 4, which can lead to dense carbon coatings. The low price and low toxicity of kitchen oils are other advantages of the coating process. LiFePO 4 (D 50 = 121 nm)combined with the carbon coating enhances the rate capability. Capacities at the 2 C rate reach 150 mAh g -1 or higher. The charge retention values of 2.0 C/0.2 C are between 94.4 and 98.9%.

  20. Doticaj moderne kozmologije i religije: poimanje početka svemira

    OpenAIRE

    Petković, Tomislav

    2007-01-01

    Ujedinjenje velikih teorija fizike − teorije relativnosti, kvantne mehanike i fizike svemira i čestica − ostaje snom fizike i filozofije znanosti i na početku 21. stoljeća. Sve se one u pogledu konačnih zakona svemira (teorija svega) slažu da je početak bio, te da su konačni zakoni oni koji su već vladali u početku evolucije svemira. Početak svemira podrazumijeva njegovo stvaranje i nužno upućuje na Stvoritelja−religijskog Boga, na uspostavljanje mosta između moderne kozmologije i religije. U...

  1. Anode property of carbon coated LiFePO4 nanocrystals

    Science.gov (United States)

    Ni, Jiangfeng; Jiang, Jiaxing; Savilov, S. V.; Aldoshin, S. M.

    2016-10-01

    Nanostructured LiFePO4 is appealing cathode material for rechargeable lithium batteries. Herein, however, we report the intriguing anode properties of carbon coated LiFePO4 nanocrystals. In the potential range of 0-3.0 V, the LiFePO4 nanocrystal electrodes afford high reversible capacity of 373 mAhg-1 at a current rate of 0.05 Ag-1 and retains 239 mAhg-1 at a much higher rate of 1.25 Ag-1. In addition, it is capable of sustaining 1000 cycles at 1.25 Ag-1 without any capacity fading. Such superior properties indicate that nanostructured LiFePO4 could also be promising anode for rechargeable battery applications.

  2. Additional of polyethylene glycol on the preparation of LaPO4:Eu3+ phosphor

    Science.gov (United States)

    Panatarani, Camellia; Joni, I. Made

    2013-09-01

    Solution phase method was used to synthesis nanocrystal LaPO4:Eu3+. Polyethylene glycol with vary molecular weight (MW) was added to allow an exothermic reaction to get a high crystalinity of LaPO4:Eu3+. The x-ray pattern of as prepared LaPO4 was obtained by using an X'pert PANalytical diffractometer with CuKα radiation (λ = 1.5406 Å) and the photoluminescent measurement spectra is obtained by using Fluorescence Spectrometer LS55, Perkin Elmer. The additional of various MW of polyethylene glycol into the precursor solution of LaPO4:Eu3+ affected the crystal structure and luminescent properties. Higher MW of PEG depressing the luminescent spectra. The emission origin from 5D0-7F4 transition vanished by additional 500,000 and 2,000,000 MW of PEG.

  3. La obra poética de Blas de Otero

    Directory of Open Access Journals (Sweden)

    Fernando Carratalá

    2006-12-01

    Full Text Available El escritor vasco Blas de Otero (Bilbao, 15-3-1916; Majadahonda –Madrid–, 29-6- 1979 es, en opinión de amplios sectores de la crítica, uno de los poetas líricos más relevantes en el panorama de la poesía contemporánea española. Fue Premio Boscán de Poesía 1950 (Redoble de conciencia y Premio de la Crítica 1959 y Premio Fastenrath 1961 (An- cia. Otero se mantuvo al margen de grupos literarios siguiendo un camino muy personal, aunque en él aparecen las tendencias en las que crecen y maduran los nuevos poetas de la posguerra: poesía de tono religioso; poesía de intención anticlasicista y antiformalista (poesía «desarraigada», en denominación de Dámaso Alonso, en respuesta al neogarcilasismo de José García Nieto y otros poetas de la llamada «Juventud Creadora» –años 1939–1944 aproximadamente–, e iniciada en 1944 con dos grandes libros: Sombra del paraíso, de Vicente Aleixandre, e Hijos de la ira, de Dámaso Alonso, libros que traen una poesía más humana y auténtica; y la que se ha llamado poesía «social». Blas de Otero que- da inmerso en estas tres tendencias, pero sin dependencia, sin ser en ninguna de ellas un mero seguidor de una moda poética.

  4. Eudragit RS PO nanoparticles for sustained release of pyridostigmine bromide

    International Nuclear Information System (INIS)

    Hoobakht, Fatemeh; Ganji, Fariba; Vasheghani-Farahani, Ebrahim; Mousavi, Seyyed Mohammad

    2013-01-01

    Pyridostigmine bromide (PB) is an inhibitor of cholinesterase, which is used in the treatment of myasthenia gravis and administered for protection against exposure to toxic nerve agents. Tests were done to investigate prolonging the half-life of PB and improving its release behavior. PB was loaded in nanoparticles (NPs) of Eudragit RS PO (Eu-RS) prepared using the technique of quasi emulsion solvent diffusion. Variables of output power of the sonicator, bath temperature and mixing time, were chosen as the optimization factors to obtain the minimum sized NPs. In addition, emulsions were tested at different ratios of drug-to-polymer by dynamic light scattering to determine size and zeta potential of NPs. UV-spectroscopy was used to determine PB content of the NPs. Drug-loaded NPs were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectra. Results determined that mixing time had a significant impact on the size of Eu-RS NPs, but power output of sonicator and bath temperature had no significant effect. The particle size obtained at the optimum condition (power output of 70 W, bath temperature of 33 °C, and mixing time of 7 min) was less than 200 nm (optimum sizes were 138.9 and 179.5 nm for Eu-RS and PB-loaded Eu-RS NPs, respectively). The optimum PB-loaded Eu-RS NPs at the PB to Eu-RS weight ratio of 1–4 and 20 % of loaded PB released from the nanocarriers within 100 h

  5. Eudragit RS PO nanoparticles for sustained release of pyridostigmine bromide

    Energy Technology Data Exchange (ETDEWEB)

    Hoobakht, Fatemeh; Ganji, Fariba, E-mail: fganji@modares.ac.ir; Vasheghani-Farahani, Ebrahim [Tarbiat Modares University, Biomedical Engineering Group, Chemical Engineering Department (Iran, Islamic Republic of); Mousavi, Seyyed Mohammad [Tarbiat Modares University, Biotechnology Group, Chemical Engineering Department (Iran, Islamic Republic of)

    2013-09-15

    Pyridostigmine bromide (PB) is an inhibitor of cholinesterase, which is used in the treatment of myasthenia gravis and administered for protection against exposure to toxic nerve agents. Tests were done to investigate prolonging the half-life of PB and improving its release behavior. PB was loaded in nanoparticles (NPs) of Eudragit RS PO (Eu-RS) prepared using the technique of quasi emulsion solvent diffusion. Variables of output power of the sonicator, bath temperature and mixing time, were chosen as the optimization factors to obtain the minimum sized NPs. In addition, emulsions were tested at different ratios of drug-to-polymer by dynamic light scattering to determine size and zeta potential of NPs. UV-spectroscopy was used to determine PB content of the NPs. Drug-loaded NPs were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectra. Results determined that mixing time had a significant impact on the size of Eu-RS NPs, but power output of sonicator and bath temperature had no significant effect. The particle size obtained at the optimum condition (power output of 70 W, bath temperature of 33 Degree-Sign C, and mixing time of 7 min) was less than 200 nm (optimum sizes were 138.9 and 179.5 nm for Eu-RS and PB-loaded Eu-RS NPs, respectively). The optimum PB-loaded Eu-RS NPs at the PB to Eu-RS weight ratio of 1-4 and 20 % of loaded PB released from the nanocarriers within 100 h.

  6. Changing hydrological conditions in the Po basin under global warming.

    Science.gov (United States)

    Coppola, Erika; Verdecchia, Marco; Giorgi, Filippo; Colaiuda, Valentina; Tomassetti, Barbara; Lombardi, Annalina

    2014-09-15

    The Po River is a crucial resource for the Italian economy, since 40% of the gross domestic product comes from this area. It is thus crucial to quantify the impact of climate change on this water resource in order to plan for future water use. In this paper a mini ensemble of 8 hydrological simulations is completed from 1960 to 2050 under the A1B emission scenario, by using the output of two regional climate models as input (REMO and RegCM) at two different resolutions (25 km-10 km and 25 km-3 km). The river discharge at the outlet point of the basin shows a change in the spring peak of the annual cycle, with a one month shift from May to April. This shift is entirely due to the change in snowmelt timing which drives most of the discharge during this period. Two other important changes are an increase of discharge in the wintertime and a decrease in the fall from September to November. The uncertainty associated with the winter change is larger compared to that in the fall. The spring shift and the fall decrease of discharge imply an extension of the hydrological dry season and thus an increase in water stress over the basin. The spatial distributions of the discharge changes are in agreement with what is observed at the outlet point and the uncertainty associated with these changes is proportional to the amplitude of the signal. The analysis of the changes in the anomaly distribution of discharge shows that both the increases and decreases in seasonal discharge are tied to the changes in the tails of the distribution, i.e. to the increase or decrease of extreme events. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Modeling Li-ion conductivity in LiLa(PO{sub 3}){sub 4} powder

    Energy Technology Data Exchange (ETDEWEB)

    Mounir, Ferhi, E-mail: ferhi.mounir@gmail.com [Laboratoire de Physicochimie des Materiaux Mineraux et leurs Applications, Centre National des Recherches en Sciences des Materiaux, BP No. 73, 8027 Soliman (Tunisia); Karima, Horchani-Naifer [Laboratoire de Physicochimie des Materiaux Mineraux et leurs Applications, Centre National des Recherches en Sciences des Materiaux, BP No. 73, 8027 Soliman (Tunisia); Khaled, Ben Saad [Laboratoire de Photovoltaieque, Centre des Recherches et des Technologies de l' Energie, Technopole Borj Cedria, BP No. 95, 2050 Hammam Lif (Tunisia); Mokhtar, Ferid [Laboratoire de Physicochimie des Materiaux Mineraux et leurs Applications, Centre National des Recherches en Sciences des Materiaux, BP No. 73, 8027 Soliman (Tunisia)

    2012-07-01

    Polycrystalline powder and single-crystal of LiLa(PO{sub 3}){sub 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(PO{sub 3}){sub 4} powder was measured and evaluated over a temperature range from 553 to 913 K. Single crystals of LiLa(PO{sub 3}){sub 4} are characterized by single-crystal X-ray diffraction. The LiLa(PO{sub 3}){sub 4} structure was found to be isotypic with LiNd(PO{sub 3}){sub 4}. It crystallizes in the monoclinic system with space group C2/c and cell parameters: a=16.635(6) A, b=7.130(3) A, c=9.913(3) A, {beta}=126.37(4) Degree-Sign , V=946.72(6) A{sup 3} and Z=4. The LiLa(PO{sub 3}){sub 4} structure was described as an alternation between spiraling chains (PO{sub 3}){sub n} and (La{sup 3+}, Li{sup +}) cations along the b direction. The small Li{sup +} ions, coordinated to four oxygen atoms, were located in the large connected cavities created between the LaO{sub 8} polyhedra and the polyphosphate chains. The jumping of Li{sup +} 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(PO{sub 3}){sub 4} and its crystallographic structure was investigated and the most probably transport pathway model was determined.

  8. Continuous arterial PO2 profiles in unrestrained, undisturbed aquatic turtles during routine behaviors

    Science.gov (United States)

    Hicks, James W.

    2016-01-01

    ABSTRACT Mammals and birds maintain high arterial partial pressure of oxygen (PO2) values in order to preserve near-complete hemoglobin (Hb) oxygen (O2) saturation. In diving mammals and birds, arterial O2 follows a primarily monotonic decline and then recovers quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and confined either to small tanks or breathing holes. Aquatic turtles can alter cardiac shunting patterns, which will affect arterial PO2 values. Consequently, little is known about arterial O2 regulation and use in undisturbed turtles. We conducted the first study to continuously measure arterial PO2 using implanted microelectrodes and a backpack logger in undisturbed red-eared sliders during routine activities. Arterial PO2 profiles during submergences varied dramatically, with no consistent patterns. Arterial PO2 was also lower than previously reported during all activities, with values rarely above 50 mmHg (85% Hb saturation). There was no difference in mean PO2 between five different activities: submerged resting, swimming, basking, resting at the surface and when a person was present. These results suggest significant cardiac shunting occurs during routine activities as well as submergences. However, the lack of relationship between PO2 and any activity suggests that cardiac shunts are not regulated to maintain high arterial PO2 values. These data support the idea that cardiac shunting is the passive by-product of regulation of vascular resistances by the autonomic nervous system. PMID:27618860

  9. Low Po2 conditions induce reactive oxygen species formation during contractions in single skeletal muscle fibers

    OpenAIRE

    Zuo, Li; Shiah, Amy; Roberts, William J.; Chien, Michael T.; Wagner, Peter D.; Hogan, Michael C.

    2013-01-01

    Contractions in whole skeletal muscle during hypoxia are known to generate reactive oxygen species (ROS); however, identification of real-time ROS formation within isolated single skeletal muscle fibers has been challenging. Consequently, there is no convincing evidence showing increased ROS production in intact contracting fibers under low Po2 conditions. Therefore, we hypothesized that intracellular ROS generation in single contracting skeletal myofibers increases during low Po2 compared wi...

  10. Nicotinamide and carbogen: relationship between pO2 and radiosensitivity in three tumour lines

    International Nuclear Information System (INIS)

    Martin, L.M.; Thomas, C.D.; Guichard, M.

    1994-01-01

    The effects of carbogen breathing, nicotinamide injection and their combination on tumour radiosensitivity were correlated with changes in tumour O 2 tension to determine the relationship between radiosensitivity and measured pO 2 . The radiosensitivity (in vivo-in vitro colony assay) and O 2 tension (computerized pO 2 histograph KIMOC 6650) of two human xenografted tumours (HRT18 and NA11 +) and one murine tumour (EMT6) were measured under similar experimental conditions. (author)

  11. Environmentally benign novel green pigments: Pr1–xCaxPO4 (x= 0 ...

    Indian Academy of Sciences (India)

    Rare earth based materials have recently attracted considerable attention as potential eco-friendly colourants for low temperature as well as high temperature applications. In the present study, we have synthesized a series of Ca-doped PrPO4 compounds with the general formula, Pr1–CaPO4 ( = 0–0.4 in steps of 0.1) ...

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

    Science.gov (United States)

    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.

  13. Diagrams about RA reactor operation, Annex 7; Prilog 7 - Rad reaktora RA po godinama - dijagrami

    Energy Technology Data Exchange (ETDEWEB)

    Martinc, R [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

    1976-01-15

    This Annex 7 includes diagrams about RA reactor operation (MWh) from 1960-1975; mean values of reactor power per day and month in 1975, and percent of utilisation of experimental space during 1975. [Serbo-Croat] Ovaj prilog sadrzi dijagrame o radu reaktora (MWh) po godinama (1960-1975); srednje vrednosti dnevne snage reaktora u 1975. godini; rad reakrora (MWh) po mesecima u 1975; procenat iskoriscenja eksperimentalnog prostora u 1975. godini.

  14. A review of the Delta Po evolution (Italy) related to climatic changes and human impacts

    Science.gov (United States)

    Simeoni, Umberto; Corbau, Corinne

    2009-06-01

    Climate changes and sea-level rise are important issues, especially for deltas such as the Po Delta, Italy. The evolution of the Po Delta shows a succession in space and a superposition in time of complex environmental natural processes. During the last few centuries, anthropogenic action has played a major role. The formation of the Po Delta began about 2000 years ago and has undergone many phases of development. Between 1500 AD and 1600 AD, the Venetian technicians diverted the Po river course. With these interventions, the "Renaissance delta" was cut off from the hydraulic network and the "modern delta" began to form. Until the middle of the 20th century, progradation of the delta was noticeable due to the abundant sediment supply. In the following decades coastal erosion occurred, this was caused by the reduction of the solid supply of the Po, due to dam and barrier construction and to river bed excavation. These and other interventions (e.g. reclamation, methane extractions from superficial ground water table) have deeply modified the physical and ecological characteristics of the Po Delta. The morphological characteristics of the Po Delta make the largest Italian wetland particularly unstable and very fragile when subjected to human pressure. Furthermore, the delta evidences multiple threats that will probably be exacerbated in the following decades by the effects of expected climatic changes. Only the application of careful policies concerning coastal defence, flood mitigation, anthropogenic subsidence reduction and salt wedge intrusion control will allow reduction of the present or predicted negative effects. This paper reviews how natural and human factors have controlled the Po Delta through time and discusses management strategies taking into account the importance of the human factor and the potential effects of climatic changes.

  15. pO2 Fluctuation Pattern and Cycling Hypoxia in Human Cervical Carcinoma and Melanoma Xenografts

    International Nuclear Information System (INIS)

    Ellingsen, Christine; Øvrebø, Kirsti Marie; Galappathi, Kanthi; Mathiesen, Berit; Rofstad, Einar K.

    2012-01-01

    Purpose: Blood perfusion in tumors is spatially and temporally heterogeneous, resulting in local fluctuations in tissue oxygen tension (pO 2 ) and tissue regions showing cycling hypoxia. In this study, we investigated whether the pO 2 fluctuation pattern and the extent of cycling hypoxia differ between tumor types showing high (e.g., cervical carcinoma xenograft) and low (e.g., melanoma xenograft) fractions of connective tissue-associated blood vessels. Methods and Materials: Two cervical carcinoma lines (CK-160 and TS-415) and two melanoma lines (A-07 and R-18) transplanted into BALB/c nu/nu mice were included in the study. Tissue pO 2 was measured simultaneously in two positions in each tumor by using a two-channel OxyLite fiber-optic oxygen-sensing device. The extent of acute and chronic hypoxia was assessed by combining a radiobiological and a pimonidazole-based immunohistochemical assay of tumor hypoxia. Results: The proportion of tumor regions showing pO 2 fluctuations, the pO 2 fluctuation frequency in these regions, and the relative amplitude of the pO 2 fluctuations were significantly higher in the melanoma xenografts than in the cervical carcinoma xenografts. Cervical carcinoma and melanoma xenografts did not differ significantly in the fraction of acutely hypoxic cells or the fraction of chronically hypoxic cells. However, the ratio between fraction of acutely hypoxic cells and fraction of chronically hypoxic cells was significantly higher in melanoma than in cervical carcinoma xenografts. Conclusions: Temporal heterogeneity in blood flow and tissue pO 2 in tumors may depend on tumor histology. Connective tissue surrounding microvessels may stabilize blood flow and pO 2 and, thus, protect tumor tissue from cycling hypoxia.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    Polycrystalline powder and single-crystal of LiLa(PO 3 ) 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(PO 3 ) 4 powder was measured and evaluated over a temperature range from 553 to 913 K. Single crystals of LiLa(PO 3 ) 4 are characterized by single-crystal X-ray diffraction. The LiLa(PO 3 ) 4 structure was found to be isotypic with LiNd(PO 3 ) 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) Å 3 and Z=4. The LiLa(PO 3 ) 4 structure was described as an alternation between spiraling chains (PO 3 ) n and (La 3+ , 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 LaO 8 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(PO 3 ) 4 and its crystallographic structure was investigated and the most probably transport pathway model was determined.

  17. Determination of the PO2 temperature blood factor from oxygen dissociation curves.

    Science.gov (United States)

    Hérigault, R A; Soulard, C D; Teisseire, B P; Laurent, D N

    1983-01-01

    The variation with saturation of the temperature coefficient of PO2 in human blood (delta log PO2/delta T) was determined by continuous recording of the oxygen dissociation curve (ODC), at 37 degrees C and 25 degrees C, on the same blood samples. PCO2 and pH were held constant through an ODC run, and PCO2 was reduced at 25 degrees C to the value measured by anaerobic cooling of the same sample. delta log PO2/delta T was calculated from isosaturation points on the 37 and 25 degrees C curves. The temperature coefficient was also computed as an independent check on this method by determination of the effects of temperature (25, 30, 37 and 40 degrees C) on hemoglobin ligand interaction: fixed acid Bohr effect (delta log PO2/delta pH), carbamino-formation (delta log PO2/delta log PCO2) and hemoglobin oxygen affinity. The values of delta log PO2/delta T ratio obtained from the two different approaches were found to be in good agreement. The coefficient decreased when [H+] concentration was increased. A linear relationship between the Bohr factor and the temperature was found: delta log PO2/delta pH = 0.00267 T-0.520 (r = 0.85; n = 40) At 25 degrees C, the carbamino-formation was one order of magnitude lower than at 37 degrees C. Acid-base state and saturation value appeared to be major determinant factors for the temperature correction coefficient to be applied to blood PO2 values measured at standard (37 degrees C) temperature.

  18. Correlation of regional disease and in vivo PO2 in rat mammary adenocarcinoma.

    OpenAIRE

    Cole, M. A.; Crawford, D. W.; Warner, N. E.; Puffer, H. W.

    1983-01-01

    A knowledge of the distribution of oxygen tension (PO2) and vascularization in neoplasia has been fundamental to understanding relationships between tumor growth, hypoxia, and therapy. We have combined recessed oxygen microcathode and freeze-substitution techniques to correlate in situ PO2 profiles and morphologic features in 7,12-dimethylbenz(a)anthracene (DMBA) tumors in rats. Overlying connective tissue of transplanted tumor was exposed by a 1-2 mm incision and a cross-stitch pattern demar...

  19. Biocarbon-coated LiFePO4 nucleus nanoparticles enhancing electrochemical performances

    DEFF Research Database (Denmark)

    Zhang, X.G.; Zhang, X.D.; He, W.

    2012-01-01

    We report a green biomimetic method to synthesize biocarbon-coated LiFePO4 nucleus nanoparticles using yeast cells as both a structural template and a biocarbon source for high-power lithium-ion batteries.......We report a green biomimetic method to synthesize biocarbon-coated LiFePO4 nucleus nanoparticles using yeast cells as both a structural template and a biocarbon source for high-power lithium-ion batteries....

  20. LiFePO4/C nanocomposites for lithium-ion batteries

    Science.gov (United States)

    Eftekhari, Ali

    2017-03-01

    LiFePO4, as the most famous member of the family of olivine-type lithium transition metal phosphates, is one of the promising candidates for the cathodes of lithium-ion batteries. However, its battery performance is limited by its low electrical conductivity and slow Li solid-state diffusion. Various methods have been attempted to improve the battery performance of lithium iron phosphate. Among them, compositing the LiFePO4 with carbon nanomaterials seems to be the most promising, as it is facile and efficient. Carbon nanomaterials usually serve as a conductive agent to improve the electrical conductivity while increasing the material porosity in which the solid-state diffusion distances are significantly shortened. Owing to the popularity of various carbonaceous nanomaterials, there is no straightforward line of research for comparing the LiFePO4/C nanocomposites. This review aims to provide a general perspective based on the research achievements reported in the literature. While surveying the research findings reported in the literature, controversial issues are also discussed. The possible contribution of pseudocapacitance as a result of functionalized carbon or LiFePO4 lattice defects is described, since from a practical perspective, a LiFePO4/C electrode can be considered as a supercapacitor at high C rates (with a specific capacitance as large as 200 F g-1). The Li diffusion in LiFePO4 has not been well understood yet; while the Li diffusion within the LiFePO4 lattice seems to be quite fast, the peculiar interfacial electrochemistry of LiFePO4 slows down the diffusion within the entire electrode by a few orders of magnitude.

  1. Kinetic Monte Carlo Study of Li Intercalation in LiFePO4.

    Science.gov (United States)

    Xiao, Penghao; Henkelman, Graeme

    2018-01-23

    Even as a commercial cathode material, LiFePO 4 remains of tremendous research interest for understanding Li intercalation dynamics. The partially lithiated material spontaneously separates into Li-poor and Li-rich phases at equilibrium. Phase segregation is a surprising property of LiFePO 4 given its high measured rate capability. Previous theoretical studies, aiming to describe Li intercalation in LiFePO 4 , include both atomic-scale density functional theory (DFT) calculations of static Li distributions and entire-particle-scale phase field models, based upon empirical parameters, studying the dynamics of the phase separation. Little effort has been made to bridge the gap between these two scales. In this work, DFT calculations are used to fit a cluster expansion for the basis of kinetic Monte Carlo calculations, which enables long time scale simulations with accurate atomic interactions. This atomistic model shows how the phases evolve in Li x FePO 4 without parameters from experiments. Our simulations reveal that an ordered Li 0.5 FePO4 phase with alternating Li-rich and Li-poor planes along the ac direction forms between the LiFePO 4 and FePO 4 phases, which is consistent with recent X-ray diffraction experiments showing peaks associated with an intermediate-Li phase. The calculations also help to explain a recent puzzling experiment showing that LiFePO 4 particles with high aspect ratios that are narrower along the [100] direction, perpendicular to the [010] Li diffusion channels, actually have better rate capabilities. Our calculations show that lateral surfaces parallel to the Li diffusion channels, as well as other preexisting sites that bind Li weakly, are important for phase nucleation and rapid cycling performance.

  2. Occurrence of ²¹⁰Po and biological effects of low-level exposure: the need for research.

    Science.gov (United States)

    Seiler, Ralph L; Wiemels, Joseph L

    2012-09-01

    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. We summarized information on the environmental behavior, biokinetics, and toxicology of ²¹⁰Po and identified the need for future research. Potential linkages between environmental exposure to ²¹⁰Po and human health effects were identified in a literature review. 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. 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.

  3. The half-life of 207Bi and decays of 211At and 211Po

    International Nuclear Information System (INIS)

    Yanokura, M.; Kudo, H.; Nakahara, H.; Miyano, K.; Ohya, S.; Nitoh, O.

    1978-01-01

    The half-life of 207 Bi was obtained from the genetic relation between 207 Po and 207 Bi, and between 211 At and 207 Bi. The half-life was found to be 33.4 +- 0.8 y. The half-life of 207 Po was determined to be 5.81 +- 0.04 h by following the decay of the characteristic γ-rays from 207 Po. The half-life of 211 At was determined to be 7.23 +- 0.02 h by following the decay of γ-rays and α-particles from 211 At and 211 Po. The half-lives determined in the present work for 207 Po and 211 At agree with the literature although the half-life of 207 Bi differs considerably from the currently accepted value of 38 y. The branching ratio of 211 At decaying through EC and α-decay modes was determined together with the branching ratios of the three α-particles emitted from 211 Po. (Auth.)

  4. The electrical and diffusive properties of unattached 218Po in air systems

    International Nuclear Information System (INIS)

    Leung, H.M.-Y.; Phillips, C.R.

    1988-01-01

    The electrical and diffusive properties of unattached 218 Po were determined in air environments containing traces of other gases. Of particular interest was the neutralisation of charged, unattached 218 Po. An electrostatic collection apparatus and a pulse width modulated ion mobility analyser were used to determine the fraction of the unattached 218 Po having a positive charge at the end of the recoil path (f); the diffusion coefficient of the neutral, unattached 218 Po Dsub(Α): the mobility of the charged, unattached 218 Po (B); and the neutralisation rate constant of charged, unattached 218 Po (K). Average values found for f, Dsub(Α), B and K were similar to those determined earlier for the argon system. Two mechanisms may be responsible for neutralisation, namely, scavenging of electrons from trace gases (charge transfer), and recombination with negative small ions. Which neutralisation mechanism is dominant depends on the amount and type of trace gas or organic vapour present and the degree of gas ionisation. (author)

  5. 210Pb and 210Po Determination in Bottled Water Available on the Croatian Market

    International Nuclear Information System (INIS)

    Rogic, M.; Rozmaric Macefat, M.; Benedik, Lj.; Strok, M.

    2011-01-01

    An alpha emitting radionuclide 210Po and beta emitting radionuclide 210Pb are decay products of 238U. Due to their nuclear properties they are considered as radionuclides with the highest radiotoxicity and contribute significantly to the internal dose to the population received by drinking water. For radiological impact assessment 210Pb and 210Po must be measured routinely and accurately, with low detection limits. The aim of our study was determination of activity concentrations of 210Pb and 210Po in bottled drinking and mineral waters available on Croatian market. For their determination a procedure for their simultaneous separation from the water samples was used. After addition of 209Po tracer and lead carrier, radionuclides were preconcentrated from large volume by MnO 2 and their separation from interfering elements by Sr resin was done. 210Po source for alpha-particle spectrometric measurement was prepared by selfdeposition on silver disc, while lead was precipitated as lead sulphate and the beta activity of its daughter 210Bi was counted on a beta proportional counter. The results obtained show that values for activity concentrations of 210Pb and 210Po in all examined waters are in accordance with allowed activity concentration according to the European Commission Recommendation 2001/928/Euratom and Guidelines for Drinking Water Quality, published