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Sample records for fgup po mayak

  1. Radiation Monitoring at FGUP Atomflot and the Polyarninski Shipyard

    SciTech Connect

    Pomerville, J.; Griffith, A. G.; Moskowitz, P. D.; BNL; Endregard, M.; Sidhu, R. S.; Sundling, C-V.; Walderhaug, T.; Egorkin, A.; Kisselev, V.; Yanovskaya, N.; Tchernaenko, L.

    2003-02-26

    The Arctic Military Environmental Cooperation (AMEC) Program is a cooperative effort between military establishments of the Russian Federation, United States and Norway to reduce potential environmental threats from military installations and activities in the Arctic and enhancing the environmental security of all three countries. The goal of this project is to enhance the ability to effectively and safely perform radiological monitoring of objects at selected facilities for dismantlement of nuclear submarines and handling and disposition of spent nuclear fuel. Radiological monitoring is needed to protect workers at the sites engaged in dismantlement of nuclear submarines, the local public and the environment. This is to be accomplished by supply of radiation monitoring equipment and the installation of centralized radiological surveillance, the PICASSO Environmental Monitoring system developed by Institute for Energy Technology, Halden, Norway. The first site selected for th e installation of PICASSO will be at the FGUP Atomflot spent nuclear fuel pad site and liquid radioactive waste treatment facility. This will be followed by an installation of PICASSO at the Mobile Processing Facility at Polyarninski Shipyard. The implementation of the PICASSO system will be integrated with the other AMEC projects at both sites. Plans are being developed to implement the use of this system at most Russian Navy sites handling spent nuclear fuel. Dosimeters have been supplied by the US and with funds from Norway. This equipment will be used at the Polyarninski Shipyard.

  2. Technology for Treatment of Liquid Radioactive Waste Generated during Uranium and Plutonium Chemical and Metallurgical Manufacturing in FSUE PO Mayak - 13616

    SciTech Connect

    Adamovich, D.

    2013-07-01

    facility. Solid concentrate produced is sent for long controlled storage. Complex of the procedures carried out makes it possible to solve problems on treatment of LRW generated while uranium and plutonium chemical and metallurgical manufacturing in Federal State Unitary Enterprise (FSUE) Mayak and cease its discharge into open water reservoirs. (authors)

  3. Uncertainties of Mayak urine data

    SciTech Connect

    Miller, Guthrie; Vostrotin, Vadim; Vvdensky, Vladimir

    2008-01-01

    For internal dose calculations for the Mayak worker epidemiological study, quantitative estimates of uncertainty of the urine measurements are necessary. Some of the data consist of measurements of 24h urine excretion on successive days (e.g. 3 or 4 days). In a recent publication, dose calculations were done where the uncertainty of the urine measurements was estimated starting from the statistical standard deviation of these replicate mesurements. This approach is straightforward and accurate when the number of replicate measurements is large, however, a Monte Carlo study showed it to be problematic for the actual number of replicate measurements (median from 3 to 4). Also, it is sometimes important to characterize the uncertainty of a single urine measurement. Therefore this alternate method has been developed. A method of parameterizing the uncertainty of Mayak urine bioassay measmements is described. The Poisson lognormal model is assumed and data from 63 cases (1099 urine measurements in all) are used to empirically determine the lognormal normalization uncertainty, given the measurement uncertainties obtained from count quantities. The natural logarithm of the geometric standard deviation of the normalization uncertainty is found to be in the range 0.31 to 0.35 including a measurement component estimated to be 0.2.

  4. Mayak worker dosimetry study: An overview

    SciTech Connect

    Vasilenko, E. K.; Khokhryakov, V. F.; Miller, S C.; Fix, Jack J.; Eckerman, Keith F.; Choe, Dong Ok; Gorelov, Mikhail; Khokhryakov, Victor V.; Knyazev, V.; Krahenbuhl, Melinda P.; Scherpelz, Robert I.; Smetanin, Mikhail; Suslova, K. G.; Vostrotin, V.

    2007-09-01

    The Mayak Production Association (MPA) was the first plutonium production plant in the former Soviet Union. Workers at the MPA were exposed to relatively large internal radiation intakes and external radiation exposures, particularly in the early years of plant operations. This paper describes the updated dosimetry database, Doses-2005. Doses-2005 represents a significant improvement in the determination of absorbed organ dose from external radiation and plutonium intake for the original cohort of 18,831 Mayak workers. The methods of dose reconstruction of absorbed organ doses from external radiation uses: 1) archive records of measured dose and worker exposure history, 2) measured energy and directional response characteristics of historical Mayak film dosimeters, and 3) calculated dose conversion factors for Mayak Study-defined exposure scenarios using Monte Carlo techniques. The methods of dose reconstruction for plutonium intake uses two revised models developed from empirical data derived from bioassay and autopsy cases and/or updates from prevailing or emerging International Commission on Radiological Protection models. Other sources of potential significant exposure to workers such as medical diagnostic x-rays, ambient onsite external radiation, neutron radiation, intake of airborne effluent, and intake of nuclides other than plutonium were evaluated to determine their impact on the dose estimates.

  5. Plutonium contamination in soils and sediments at Mayak PA, Russia.

    PubMed

    Skipperud, Lindis; Salbu, Brit; Oughton, Deborah H; Drozcho, Eugeny; Mokrov, Yuri; Strand, Per

    2005-09-01

    The Mayak Production Association (Mayak PA) was established in the late 1940's to produce plutonium for the Soviet Nuclear Weapons Programme. In total, seven reactors and two reprocessing plants have been in operation. Today, the area comprises both military and civilian reactors as well as reprocessing and metallurgical plants. Authorized and accidental releases of radioactive waste have caused severe contamination to the surrounding areas. In the present study, [alpha]-spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS) have been used to determine plutonium activities and isotope ratios in soil and sediment samples collected from reservoirs of the Techa River at the Mayak area and downstream Techa River. The objective of the study was to determine the total inventory of plutonium in the reservoirs and to identify the different sources contributing to the plutonium contamination. Results based on [alpha]-spectrometry and ICP-MS measurements show the presence of different sources and confirmed recent reports of civilian reprocessing at Mayak. Determination of activity levels and isotope ratios in soil and sediment samples from the Techa River support the hypothesis that most of the plutonium, like other radionuclides in the Techa River, originated from the very early waste discharges to the Techa River between 1949 and 1951. Analysis of reservoir sediment samples suggest that about 75% of the plutonium isotopes could have been released to Reservoir 10 during the early weapons production operation of the plant, and that the majority of plutonium in Reservoir 10 originates from discharges from power production or reprocessing. Enhanced 240Pu/239Pu atom ratios in river sediment upper layers (0-2 cm) between 50 and 250 km downstream from the plant indicate a contribution from other, non-fallout sources.

  6. Risks of circulatory diseases among Mayak PA workers with radiation doses estimated using the improved Mayak Worker Dosimetry System 2008.

    PubMed

    Moseeva, Maria B; Azizova, Tamara V; Grigoryeva, Evgenia S; Haylock, Richard

    2014-05-01

    The new Mayak Worker Dosimetry System 2008 (MWDS-2008) was published in 2013 and supersedes the Doses-2005 dosimetry system for Mayak Production Association (PA) workers. It provides revised external and internal dose estimates based on the updated occupational history data. Using MWDS-2008, a cohort of 18,856 workers first employed at one of the main Mayak PA plants during 1948-1972 and followed up to 2005 was identified. Incidence and mortality risks from ischemic heart disease (IHD) (International Classification of Diseases (ICD)-9 codes 410-414) and from cerebrovascular diseases (CVD) (ICD-9 codes 430-438) were examined in this cohort and compared with previously published risk estimates in the same cohort based on the Doses-2005 dosimetry system. Significant associations were observed between doses from external gamma-rays and IHD and CVD incidence and also between internal doses from alpha-radiation and IHD mortality and CVD incidence. The estimates of excess relative risk (ERR)/Gy were consistent with those estimates from the previous studies based on Doses-2005 system apart from the relationship between CVD incidence and internal liver dose where the ERR/Gy based on MWDS-2008 was just over three times higher than the corresponding estimate based on Doses-2005 system. Adjustment for smoking status did not show any effect on the estimates of risk from internal alpha-particle exposure.

  7. Analysis Approach and Data Package for Mayak Public Doses

    SciTech Connect

    Eslinger, Paul W.; Napier, Bruce A.

    2013-09-18

    Historical activities at facilities producing nuclear materials for weapons released radioactivity into the air and water. Past studies in the United States have evaluated the release, atmospheric transport and environmental accumulation of 131I from the nuclear facilities at Hanford in Washington State and the resulting dose to members of the public (Farris et al. 1994). A multi-year dose reconstruction effort (Mokrov et al. 2004) is also being conducted to produce representative dose estimates for members of the public living near Mayak, Russia, from atmospheric releases of 131I at the facilities of the Mayak Production Association. The approach to calculating individual doses to members of the public from historical releases of airborne 131I has the following general steps: • Construct estimates of releases 131I to the air from production facilities. • Model the transport of 131I in the air and subsequent deposition on the ground and vegetation. • Model the accumulation of 131I in soil, water and food products (environmental media). • Calculate the dose for an individual by matching the appropriate lifestyle and consumption data for the individual to the concentrations of 131I in environmental media at their residence location. A number of computer codes were developed to facilitate the study of airborne 131I emissions at Hanford. Of particular interest is DESCARTES code that modeled accumulation of 131I in environmental media (Miley et al. 1994). In addition, the CIDER computer code estimated annual doses to individuals (Eslinger et al. 1994) using the equations and parameters specific to Hanford (Snyder et al. 1994). Several of the computer codes developed to model 131I releases from Hanford are general enough to be used for other facilities. Additional codes have been developed, including the new individual dose code CiderF (Eslinger and Napier 2013), and applied to historical releases of 131I from Mayak. This document provides a data package that

  8. The Mayak Worker Dosimetry System (MWDS-2013): Internal Dosimetry Results.

    PubMed

    Vostrotin, Vadim; Birchall, Alan; Zhdanov, Alexey; Puncher, Matthew; Efimov, Alexander; Napier, Bruce; Sokolova, Alexandra; Miller, Scott; Suslova, Klara

    2016-09-24

    The distribution of calculated internal doses has been determined for 8043 Mayak Production Associate (Mayak PA) workers. This is a subset of the entire cohort of 25 757 workers, for whom monitoring data are available. Statistical characteristics of point estimates of accumulated doses to 17 different tissues and organs and the uncertainty ranges were calculated. Under the MWDS-2013 dosimetry system, the mean accumulated lung dose was 185 ± 594 mGy (geometric mean = 28 mGy; geometric standard deviation = 9.32; median value = 31 mGy; maximum value = 8980 mGy). The ranges of relative standard uncertainty were from 40 to 2200% for accumulated lung dose, from 25-90% to 2600-3000% for accumulated dose to different regions of respiratory tract, from 13-22% to 2300-2500% for systemic organs and tissues. The Mayak PA workers accumulated internal plutonium lung dose is shown to be close to log normal. The accumulated internal plutonium dose to systemic organs was close to a log triangle. The dependency of uncertainty of accumulated absorbed lung and liver doses on the dose estimates itself is also shown. The accumulated absorbed doses to lung, alveolar-interstitial region, liver, bone surface cells and red bone marrow calculated both with MWDS-2013 and MWDS-2008 have been compared. In general, the accumulated lung doses increased by a factor of 1.8 in median value, while the accumulated doses to systemic organs decreased by factor of 1.3-1.4 in median value. For the cases with identical initial data, accumulated lung doses increased by a factor of 2.1 in median value, while accumulated doses to systemic organs decreased by 8-13% in median value. For the cases with both identical initial data and all of plutonium activity in urine measurements above the decision threshold, accumulated lung doses increased by a factor of 2.7 in median value, while accumulated doses to systemic organs increased by 6-12% in median value.

  9. Molecular Markers of Lung Cancer in MAYAK Workers

    SciTech Connect

    Steven A. Belinsky, PhD

    2007-02-15

    The molecular mechanisms that result in the elevated risk for lung cancer associated with exposure to radiation have not been well characterized. Workers from the MAYAK nuclear enterprise are an ideal cohort in which to study the molecular epidemiology of cancer associated with radiation exposure and to identify the genes targeted for inactivation that in turn affect individual risk for radiation-induced lung cancer. Epidemiology studies of the MAYAK cohort indicate a significantly higher frequency for adenocarcinoma and squamous cell carcinoma (SCC) in workers than in a control population and a strong correlation between these tumor types and plutonium exposure. Two hypotheses will be evaluated through the proposed studies. First, radiation exposure targets specific genes for inactivation by promoter methylation. This hypothesis is supported by our recent studies with the MAYAK population that demonstrated the targeting of the p16 gene for inactivation by promoter methylation in adenocarcinomas from workers (1). Second, genes inactivated in tumors can serve as biomarkers for lung cancer risk in a cancer-free population of workers exposed to plutonium. Support for this hypothesis is based on exciting preliminary results of our nested, case-control study of persons from the Colorado cohort. In that study, a panel of methylation markers for predicting lung cancer risk is being evaluated in sputum samples from incident lung cancer cases and controls. The first hypothesis will be tested by determining the prevalence for promoter hypermethylation of a panel of genes shown to play a critical role in the development of either adenocarcinoma and/or SCC associated with tobacco. Our initial studies on adenocarcinoma in MAYAK workers will be extended to evaluate methylation of the PAX5 {alpha}, PAX5 {beta}, H-cadherin, GATA5, and bone morphogenesis 3B (BMP3B) genes in the original sample set described under Preliminary studies. In addition, studies will be initiated in SCC

  10. Lung, liver and bone cancer mortality in Mayak workers

    PubMed Central

    Sokolnikov, Mikhail E.; Gilbert, Ethel S.; Preston, Dale L.; Ron, Elaine; Shilnikova, Natalia S.; Khokhryakov, Victor V.; Vasilenko, Evgeny K.; Koshurnikova, Nina A.

    2014-01-01

    Workers at the Mayak nuclear facility in the Russian Federation offer the only adequate human data for evaluating cancer risks from exposure to plutonium. Risks of mortality from cancers of the lung, liver and bone, the organs receiving the largest doses from plutonium, were evaluated in a cohort of 17,740 workers initially hired 1948–1972 using, for the first time, recently improved individual organ dose estimates. Excess relative risk (ERR) models were used to evaluate risks as functions of internal (plutonium) dose, external (primarily gamma) dose, gender, attained age and smoking. By December 31, 2003, 681 lung cancer deaths, 75 liver cancer deaths and 30 bone cancer deaths had occurred. Of these 786 deaths, 239 (30%) were attributed to plutonium exposure. Significant plutonium dose-response relationships (p < 0.001) were observed for all 3 endpoints, with lung and liver cancer risks reasonably described by linear functions. At attained age 60, the ERRs per Gy for lung cancer were 7.1 for males and 15 for females; the averaged-attained age ERRs for liver cancer were 2.6 and 29 for males and females, respectively; those for bone cancer were 0.76 and 3.4. This study is the first to present and compare dose-response analyses for cancers of all 3 organs. The unique Mayak cohort with its high exposures and well characterized doses has allowed quantification of the plutonium dose-response for lung, liver and bone cancer risks based on direct human data. These results will play an important role in plutonium risk assessment. PMID:18528867

  11. TID Environmental Performance Testing In Support of the Mayak Fissile Material Storage Facility

    SciTech Connect

    Tanner, Jennifer E.; Undem, Halvor A.; Roberts, Bruce A.; Griggs, James R.; Pratt, Sharon L.; Smith, Matthew H.

    2002-03-01

    The purpose of the test and evaluation of tamper indicating devices (TIDs) described in this report is to assure that the recommended TID technologies are acceptable for use at the Mayak FMSF. TID acceptance is based on TID performance with respect to mutually agreed functional, operational, and security requirements for the FMSF, taking into account both the United States and the Russian Federation views. Although some Russian views have been documented, very little information at the level required for formal test planning had been received prior to the start of the testing campaign. Consequently, this report currently represents US recommendations for an arms control and/or safeguards and security application. Acceptance of these test results and recommendations by those Russian Federation entities responsible for the Mayak FMSF will be required before implementing any TID regime at Mayak FMSF.

  12. The Mayak Worker Dosimetry System-2013: Treatment of Organ Masses in the Calculation of Organ Doses.

    PubMed

    Birchall, A; Sokolova, A B

    2017-01-10

    Previous Mayak worker epidemiological studies designed to quantify the risk of cancer following exposure to airborne plutonium have calculated organ doses by dividing the organ-absorbed energy by the individual's estimated organ mass. For living workers, this was done by using a relationship between organ mass and total mass and height. For autopsy cases, this was measured directly. In the Mayak Worker Dosimetry System-2013 study, organ doses are calculated by dividing this energy by a population average organ mass. The reasons for departing from previous methodologies are described in this note. The average organ masses that were used in the final analysis are tabulated for males and females.

  13. Mayak Worker Dosimetry System (MWDS-2013): Phase I-Quality Assurance of Organ Doses and Excretion Rates From Internal Exposures of Plutonium-239 for the Mayak Worker Cohort.

    PubMed

    Dorrian, M-D; Birchall, A; Vostrotin, V

    2016-06-20

    The calculation of reliable and realistic doses for use in epidemiological studies for the quantification of risk from internal exposure to radioactive material is fundamental to the development of advice, guidance and regulations for the control and use of radioactive material. Thus, any programme of work carried out which requires the calculation of doses for use by epidemiologists ideally should contain a rigorous program of quality assurance (QA). This paper describes the initial QA (Phase I) implemented by Public Health England (PHE) and the Southern Urals Biophysics Institute (SUBI) as part of the work programme on internal dosimetry in the Joint Coordinating Committee for Radiation Effects Research Project 2.4 for the 2013 Mayak Worker Dosimetry System. SUBI designed and implemented new software (PANDORA) to include the latest Mayak Worker Dosimetry System and to calculate organ burdens, urinary excretion rates, intakes and absorbed doses, while PHE modified their commercially available IMBA Professional Plus software package. Comparisons of output from the two codes for the Mayak Worker Dosimetry System 2013 showed calculated values of absorbed doses, intakes, organ burdens and urinary excretion agreed to within 1%. The 1% discrepancy can be explained by the approximation used in IMBA to speed up dose calculations.

  14. Mortality among personnel who worked at the Mayak complex in the first years of its operation

    SciTech Connect

    Koshurnikova, N.A.; Bysogolov, G.D.; Bolotnikova, M.G.; Khokhryakov, V.F.

    1996-07-01

    Epidemiological studies revealed increased cancer mortality among persons who began working at the Mayak complex curing the period 1948-1958. Estimation of cancer risk was carried out for the sites of cancer that showed increased mortality and dependence on dose of external gamma- or internal alpha-irradiation. 5 refs., 8 tabs.

  15. Retrospective estimation of Plutonium-239 doses from transfer to the fetus for Mayak PA workers.

    PubMed

    Vostrotin, Vadim V; Fell, Tim P; Smith, Tracy J; Romanov, Sergey А

    2014-11-01

    The estimation of plutonium fetal transfer and the calculation of individual in utero and postnatal doses for the Mayak Production Association (PA) offspring cohort. The model developed by the International Commission on Radiological Protection (ICRP) for the transfer of plutonium to the fetus following maternal intakes before and during pregnancy has been adjusted for application to analysis of the fetal transfer of (239)Pu for Mayak workers. Improved estimates of fetal to maternal concentration ratios (CF:CM) have been obtained based on a correlation observed between adult offsprings' measured daily urine (239)Pu activity and estimates of their mothers' systemic activity at conception. Data on (239)Pu activity in daily urine samples were collected from 13 selected adults whose mothers worked at the Mayak PA facility during the period from 1948-1953, before and/or during pregnancy. A comparison of measured and modeled excretion data enabled a mean value of 0.18 ± 0.02 (n = 21) to be inferred for the Pu CF:CM ratio, with a coefficient of variation of 60%. Point estimates of the individual in utero and postnatal absorbed doses for the red bone marrow and liver were in the range 2…13 mGy in 95% of the cases for the cohort of 1936 offspring.

  16. The Mayak Worker Dosimetry System (MWDS-2013): Uncertainty in the Measurement of Pu Activity in a 24-Hour Urine Sample of a Typical Mayak PA Worker.

    PubMed

    Vostrotin, Vadim; Birchall, Alan; Zhdanov, Alexey; Gregoratto, Demetrio; Suslova, Klara; Marsh, James; Efimov, Alexander

    2016-09-21

    In the Mayak Worker Dosimetry System (MWDS-2013), intakes of plutonium and organ doses are assessed on the basis of measurements made on the plutonium content of 56 400 urine samples. Altogether, there were urine bioassays for 7591 (29%) of the 25 757 cohort members who were employed any time at Mayak between 1948 and 1982. These measurements are subject to uncertainty due to many factors (e.g. whether or not creatinine is measured, the volume of the sample, whether diethylenetriaminepentaacetic acid was administered, etc.) and this uncertainty will affect not only the uncertainty in the estimated doses, but also the values of the doses themselves. Therefore, it is important for the estimated uncertainty to be as accurate as possible. The input to the dose calculation requires an estimate of the plutonium activity in a true 24-hour sample. The uncertainty in this activity is approximated by a lognormal distribution. The aim of this paper is to describe and justify how the parameters of this lognormal distribution are derived from the raw data. Histograms of the distribution of sample volumes are given for both sexes. The method of calculation of the decision threshold and relative standard uncertainty (RSU) of a measurement result for Pu activity in a worker's urine sample is shown. Diagrams of correlation between Pu activity in collected urine and its RSU are given. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Mayak Worker Dosimetry System 2008 (MWDS-2008): assessment of internal dose from measurement results of plutonium activity in urine.

    PubMed

    Khokhryakov, Victor V; Khokhryakov, Valentin F; Suslova, Klara G; Vostrotin, Vadim V; Vvedensky, Vladimir E; Sokolova, Alexandra B; Krahenbuhl, Melinda P; Birchall, Alan; Miller, Scott C; Schadilov, Anatoly E; Ephimov, Alexander V

    2013-04-01

    A new modification of the prior human lung compartment plutonium model, Doses-2005, has been described. The modified model was named "Mayak Worker Dosimetry System-2008" (MWDS-2008). In contrast to earlier models developed for workers at the Mayak Production Association (Mayak PA), the new model more correctly describes plutonium biokinetics and metabolism in pulmonary lymph nodes. The MWDS-2008 also provides two sets of doses estimates: one based on bioassay data and the other based on autopsy data, where available. The algorithm of internal dose calculation from autopsy data will be described in a separate paper. Results of comparative analyses of Doses-2005 and MWDS-2008 are provided. Perspectives on the further development of plutonium dosimetry are discussed.

  18. Characterization of biocenoses in the storage reservoirs of liquid radioactive wastes of Mayak PA. Initial descriptive report.

    PubMed

    Pryakhin, E A; Mokrov, Yu G; Tryapitsina, G A; Ivanov, I A; Osipov, D I; Atamanyuk, N I; Deryabina, L V; Shaposhnikova, I A; Shishkina, E A; Obvintseva, N A; Egoreichenkov, E A; Styazhkina, E V; Osipova, O F; Mogilnikova, N I; Andreev, S S; Tarasov, O V; Geras'kin, S A; Trapeznikov, A V; Akleyev, A V

    2016-01-01

    As a result of operation of the Mayak Production Association (Mayak PA), Chelyabinsk Oblast, Russia, an enterprise for production and separation of weapon-grade plutonium in the Soviet Union, ecosystems of a number of water bodies have been radioactively contaminated. The article presents information about the current state of ecosystems of 6 special industrial storage reservoirs of liquid radioactive waste from Mayak PA: reservoirs R-3, R-4, R-9, R-10, R-11 and R-17. At present the excess of the radionuclide content in the water of the studied reservoirs and comparison reservoirs (Shershnyovskoye and Beloyarskoye reservoirs) is 9 orders of magnitude for (90)Sr and (137)Cs, and 6 orders of magnitude for alpha-emitting radionuclides. According to the level of radioactive contamination, the reservoirs of the Mayak PA could be arranged in the ascending order as follows: R-11, R-10, R-4, R-3, R-17 and R-9. In 2007-2012 research of the status of the biocenoses of these reservoirs in terms of phytoplankton, zooplankton, bacterioplankton, zoobenthos, aquatic plants, ichthyofauna, avifauna parameters was performed. The conducted studies revealed decrease in species diversity in reservoirs with the highest levels of radioactive and chemical contamination. This article is an initial descriptive report on the status of the biocenoses of radioactively contaminated reservoirs of the Mayak PA, and is the first article in a series of publications devoted to the studies of the reaction of biocenoses of the fresh-water reservoirs of the Mayak PA to a combination of natural and man-made factors, including chronic radiation exposure.

  19. Risk of mortality from circulatory diseases in Mayak workers cohort following occupational radiation exposure.

    PubMed

    Azizova, T V; Grigorieva, E S; Hunter, N; Pikulina, M V; Moseeva, M B

    2015-09-01

    Mortality from circulatory diseases (CD) (ICD-9 codes 390-459) was studied in an extended Mayak worker cohort, which included 22,377 workers first employed at the Mayak Production Association in 1948-1982 and followed up to the end of 2008. The enlarged cohort and extended follow-up as compared to the previous analyses provided an increased number of deaths from CD and improved statistical power of this mortality study. The analyses were based on dose estimates provided by a new Mayak Worker Dosimetry System 2008 (MWDS-2008). For the first time in the study of non-cancer effects in this cohort quantitative smoking data (smoking index) were taken into account. A significant increasing trend for CD mortality with increasing dose from external gamma-rays was found after having adjusted for non-radiation factors; the excess relative risk per unit dose (ERR/Gy) was 0.05 (95% confidence interval (CI):  >0, 0.11). Inclusion of an additional adjustment for dose from internal alpha-radiation to the liver resulted in a two-fold increase of ERR/Gy = 0.10 (95% CI: 0.02, 0.21). A significant increasing trend in CD mortality with increasing dose from internal alpha-radiation to the liver was observed (ERR/Gy = 0.27, 95% CI: 0.12, 0.48). However the ERR/Gy decreased and lost its significance after adjusting for dose from external gamma-rays. Results of the current study are in good agreement with risk estimates obtained for the Japanese LSS cohort as well as other studies of cohorts of nuclear workers.

  20. 238Pu: accumulation, tissue distribution, and excretion in Mayak workers after exposure to plutonium aerosols.

    PubMed

    Suslova, Klara G; Sokolova, Alexandra B; Khokhryakov, Viktor V; Miller, Scott C

    2012-03-01

    The alpha spectrometry measurements of specific activity of 238Pu and 239Pu in urine from bioassay examinations of 1,013 workers employed at the radiochemical and plutonium production facilities of the Mayak Production Association and in autopsy specimens of lung, liver, and skeleton from 85 former nuclear workers who died between 1974-2009, are summarized.The accumulation fraction of 238Pu in the body and excreta has not changed with time in workers involved in production of weapons-grade plutonium production (e.g., the plutonium production facility and the former radiochemical facility). The accumulation fraction of 238Pu in individuals exposed to plutonium isotopes at the newer Spent Nuclear Fuel Reprocessing Plant ranged from 0.13% up to 27.5% based on the autopsy data. No statistically significant differences between 238Pu and 239Pu in distribution by the main organs of plutonium deposition were found in the Mayak workers. Based on the bioassay data,the fraction of 238Pu activity in urine is on average 38-69% of the total activity of 238Pu and 239Pu, which correlates with the isotopic composition in workplace air sampled at the Spent Nuclear Fuel Reprocessing Plant. In view of the higher specific activity of 238Pu, the contribution of 238Pu to the total internal dose, particularly in the skeleton and liver, might be expected to continue to increase, and continued surveillance is recommended.

  1. Risk of Cataract Incidence in a Cohort of Mayak PA Workers following Chronic Occupational Radiation Exposure

    PubMed Central

    Azizova, Tamara V.; Bragin, Evgeny V.; Hamada, Nobuyuki; Bannikova, Maria V.

    2016-01-01

    This is the first study of cataract incidence in a cohort of Mayak Production Association workers first employed at one of the main facilities in 1948–1982 and followed up till the end of 2008 (22,377 workers). Principal advantages of the study are the large size of the cohort, long-term follow-up and sufficient statistical power, available results of annual eye examinations over the entire follow-up period and detailed information on non-radiation confounders. Individual measured doses from external γ-rays and neutrons used in the analyses were provided by the Mayak Worker Dosimetry System 2008 (MWDS-2008). Relative risk (RR) and excess relative risk (ERR) per unit dose (Gy) were calculated based on maximum likelihood using the AMFIT module of the EPICURE software. The RR of cataract incidence was found to be the highest in workers exposed at doses above 2.0 Gy. A significant linear association of cataract incidence with cumulative dose from external γ-rays was found with ERR/Gy equal to 0.28 (95% confidence intervals: 0.20, 0.37). The results obtained varied slightly with inclusion of additional adjustments for non-radiation factors (smoking index, hypertension, glaucoma and body mass index). Adjusting for the dose from neutrons gave a considerable increase in ERR/Gy for cataract incidence. PMID:27723789

  2. The Mayak Worker Dosimetry System (MWDS-2013): Implementation of the Dose Calculations.

    PubMed

    Zhdanov, А; Vostrotin, V; Efimov, А; Birchall, A; Puncher, M

    2016-07-15

    The calculation of internal doses for the Mayak Worker Dosimetry System (MWDS-2013) involved extensive computational resources due to the complexity and sheer number of calculations required. The required output consisted of a set of 1000 hyper-realizations: each hyper-realization consists of a set (1 for each worker) of probability distributions of organ doses. This report describes the hardware components and computational approaches required to make the calculation tractable. Together with the software, this system is referred to here as the 'PANDORA system'. It is based on a commercial SQL server database in a series of six work stations. A complete run of the entire Mayak worker cohort entailed a huge amount of calculations in PANDORA and due to the relatively slow speed of writing the data into the SQL server, each run took about 47 days. Quality control was monitored by comparing doses calculated in PANDORA with those in a specially modified version of the commercial software 'IMBA Professional Plus'. Suggestions are also made for increasing calculation and storage efficiency for future dosimetry calculations using PANDORA. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Implementation of tank volume measurement equipment at the Mayak Production Association

    SciTech Connect

    Darenskikh, O.; Suda, S.C.; Valente, J.U.; Zuhoski, P.B.; Salwen, C.A.

    1997-12-31

    One goal of the United States Russia Cooperative program to improve nuclear material protection, control, and accounting (MPC and A) in Russian facilities is to computerize material accounting techniques for bulk materials. Such materials include liquid solutions at radiochemical plants: dissolver, intermediate product, and waste. Material accounting techniques for tank volume measurements (TVM) are needed to determine the nuclear material content of these solutions (chemical and isotopic analysis are also required). The content is required to close the material balance in a radiochemical plant. Computerization of these techniques can provide unattended measurements of material flows, improved precision and accuracy, reduced operator effort, and lower radiation exposure of operators--with equipment that is predominantly remote from high radiation areas. This paper describes the technical activities that contributed to the successful integration of the TVM system, developed by Brookhaven National Laboratory (BNL), into the Mayak Production Association radiochemical plant conducted under the US/Russian cooperative MPC and A Program. US assistance with installation and adjustment of the instrumentation was completed in May 1997. After that, Mayak experts on measurement and metrology continued mastering and testing the equipment.

  4. Consequences of the radiation accident at the Mayak production association in 1957 (the 'Kyshtym Accident').

    PubMed

    Akleyev, A V; Krestinina, L Yu; Degteva, M O; Tolstykh, E I

    2017-09-01

    This paper presents an overview of the nuclear accident that occurred at the Mayak Production Association (PA) in the Russian Federation on 29 September 1957, often referred to as 'Kyshtym Accident', when 20 MCi (740 PBq) of radionuclides were released by a chemical explosion in a radioactive waste storage tank. 2 MCi (74 PBq) spread beyond the Mayak PA site to form the East Urals Radioactive Trace (EURT). The paper describes the accident and gives brief characteristics of the efficacy of the implemented protective measures that made it possible to considerably reduce doses to the exposed population. The paper also provides retrospective dosimetry estimates for the members of the EURT Cohort (EURTC) which comprises approximately 21 400 people. During the first two years after the accident a decrease in the group average leukocyte (mainly due to neutrophils and lymphocytes) and thrombocyte count was observed in the population. At later dates an increased excess relative risk of solid cancer incidence and mortality was found in the EURTC.

  5. Lung cancer risks from plutonium: an updated analysis of data from the Mayak worker cohort.

    PubMed

    Gilbert, E S; Sokolnikov, M E; Preston, D L; Schonfeld, S J; Schadilov, A E; Vasilenko, E K; Koshurnikova, N A

    2013-03-01

    Workers at the Mayak nuclear facility in the Russian Federation offer a unique opportunity to evaluate health risks from exposure to inhaled plutonium. Risks of mortality from lung cancer, the most serious carcinogenic effect of plutonium, were evaluated in 14,621 Mayak workers who were hired in the period from 1948-1982, followed for at least 5 years, and either monitored for plutonium or never worked with plutonium. Over the follow-up period from 1953-2008, there were 486 deaths from lung cancer, 446 of them in men. In analyses that were adjusted for external radiation dose and smoking, the plutonium excess relative risk (ERR) per Gy declined with attained age and was higher for females than for males. The ERR per Gy for males at age 60 was 7.4 (95% CI: 5.0-11) while that for females was 24 (95% CI: 11-56). When analyses were restricted to plutonium doses <0.2 Gy, the ERR per Gy for males at age 60 was similar: 7.0 (95% CI: 2.5-13). Of the 486 lung cancer deaths, 105 (22%) were attributed to plutonium exposure and 29 (6%) to external exposure. Analyses of the 12,708 workers with information on smoking indicated that the relationship of plutonium exposure and smoking was likely sub-multiplicative (P = 0.011) and strongly indicated that it was super-additive (P < 0.001). Although extensive efforts have been made to improve plutonium dose estimates in this cohort, they are nevertheless subject to large uncertainties. Large bioassay measurement errors alone are likely to have resulted in serious underestimation of risks, whereas other sources of uncertainty may have biased results in ways that are difficult to predict.

  6. Radiation Risks of Leukemia, Lymphoma and Multiple Myeloma Incidence in the Mayak Cohort: 1948–2004

    PubMed Central

    Kuznetsova, Irina S.; Labutina, Elena V.; Hunter, Nezahat

    2016-01-01

    Incidence of all types of lymphatic and hematopoietic cancers, including Hodgkin’s lymphoma, non-Hodgkin's lymphoma, multiple myeloma, acute and chronic myeloid leukemia (AML and CML respectively), chronic lymphocytic leukemia (CLL) and other forms of leukemia have been studied in a cohort of 22,373 workers employed at the Mayak Production Association (PA) main facilities during 536,126 person-years of follow-up from the start of employment between 1948 and 1982 to the end of 2004. Risk assessment was performed for both external gamma-radiation and internal alpha-exposure of red bone marrow due to incorporated Pu-239 using Mayak Workers Dosimetry System 2008 taking into account non-radiation factors. The incidence of leukemia excluding CLL showed a non-linear dose response relationship for external gamma exposure with exponential effect modifiers based on time since exposure and age at exposure. Among the major subtypes of leukemia, the excess risk of AML was the highest within the first 2–5 years of external exposure (ERR per Gy: 38.40; 90% CI: 13.92–121.4) and decreased substantially thereafter, but the risks remained statistically significant (ERR per Gy: 2.63; 90% CI: 0.07–12.55). In comparison, excess CML first occurred 5 years after exposure and decreased about 10 years after exposure, although the association was not statistically significant (ERR per Gy: 1.39; 90% CI: -0.22–7.32). The study found no evidence of an association between leukemia and occupational exposure to internal plutonium ERR per Gy 2.13; 90% CI: <0–9.45). There was also no indication of any relationship with either external gamma or internal plutonium radiation exposure for either incidence of Hodgkin or non-Hodgkin lymphoma or multiple myeloma. PMID:27631102

  7. Lung Cancer Risks from Plutonium: An Updated Analysis of Data from the Mayak Worker Cohort

    PubMed Central

    Gilbert, E. S.; Sokolnikov, M. E.; Preston, D. L.; Schonfeld, S. J.; Schadilov, A. E.; Vasilenko, E. K.; Koshurnikova, N. A.

    2013-01-01

    Workers at the Mayak nuclear facility in the Russian Federation offer a unique opportunity to evaluate health risks from exposure to inhaled plutonium. Risks of mortality from lung cancer, the most serious carcinogenic effect of plutonium, were evaluated in 14,621 Mayak workers who were hired in the period from 1948–1982, followed for at least 5 years, and either monitored for plutonium or never worked with plutonium. Over the follow-up period from 1953–2008, there were 486 deaths from lung cancer, 446 of them in men. In analyses that were adjusted for external radiation dose and smoking, the plutonium excess relative risk (ERR) per Gy declined with attained age and was higher for females than for males. The ERR per Gy for males at age 60 was 7.4 (95% CI: 5.0–11) while that for females was 24 (95% CI: 11–56). When analyses were restricted to plutonium doses <0.2 Gy, the ERR per Gy for males at age 60 was similar: 7.0 (95% CI: 2.5–13). Of the 486 lung cancer deaths, 105 (22%) were attributed to plutonium exposure and 29 (6%) to external exposure. Analyses of the 12,708 workers with information on smoking indicated that the relationship of plutonium exposure and smoking was likely sub-multiplicative (P = 0.011) and strongly indicated that it was super-additive (P < 0.001). Although extensive efforts have been made to improve plutonium dose estimates in this cohort, they are nevertheless subject to large uncertainties. Large bioassay measurement errors alone are likely to have resulted in serious underestimation of risks, whereas other sources of uncertainty may have biased results in ways that are difficult to predict. PMID:23391147

  8. Environmental Radiation Dose Reconstruction for U.S. and Russian Weapons Production Facilities: Hanford and Mayak

    SciTech Connect

    Ansbaugh, Lynn R.; Degteva, M. O.; Kozheurov, V. P.; Napier, Bruce A.; Tolstykh, E. I.; Vorobiova, M. I.

    2003-05-01

    Another way to look at Cold War legacies is to examine the major environmental releases that resulted from past operation of Cold War-related facilities for the manufacture of nuclear weapons. Examining these historical releases and the resultant radiation dose to individuals living near these facilities is called environmental dose reconstruction. Dose reconstructions have been performed or are underway at most large Cold War installations in the United States, such as the Hanford facility; several are also underway in other countries, such as at the Mayak facility in Russia. The efforts in the United States are mostly based on historical operating records and current conditions, which are used to estimate environmental releases, transport, and human exposure. The Russian efforts are largely based on environmental measurements and measurements of human subjects; environmental transport modelling, when conducted, is used to organize and validate the measurements. Past operation of Cold War-related facilities for the manufacture of nuclear weapons has resulted in major releases of radionuclides into the environment. Reconstruction of the historical releases and the resultant radiation dose to individuals in the public living near these facilities is called environmental dose reconstruction. Dose reconstructions have been performed or are underway at most large Cold War installations in the United States; several are also underway in other countries. The types of activity performed, the operating histories, and the radionuclide releases vary widely across the different facilities. The U.S. Hanford Site and the Russian Mayak Production Association are used here to illustrate the nature of the assessed problems and the range of approaches developed to solve them.

  9. Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948–2004

    PubMed Central

    Hunter, N; Kuznetsova, I S; Labutina, E V; Harrison, J D

    2013-01-01

    Background: Cancer incidence in the Mayak Production Association (PA) cohort was analysed to investigate for the first time whether external gamma-ray and internal plutonium exposure are associated with raised incidence of solid cancers other than lung, liver and bone (other solid cancers). Methods: The cohort includes 22 366 workers of both sexes who were first employed between 1948 and 1982. A total of 1447 cases of other solid cancers were registered in the follow-up period until 2004. The Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to plutonium and external gamma-ray. Results: A weak association was found between cumulative exposure to external gamma-ray and the incidence of other solid cancers (ERR/Gy=0.07; 95% confidence intervals (CIs): 0.01–0.15), but this association lost its significance after adjusting for internal plutonium exposure. There was no indication of any association with plutonium exposure for other solid cancers. Among 16 individual cancer sites, there was a statistically significant association with external exposure for lip cancer (ERR/Gy=1.74; 95% CI: 0.37; 6.71) and with plutonium exposure for pancreatic cancer (ERR/Gy=1.58; 95% CI; 0.17; 4.77). Conclusion: This study of Mayak workers does not provide evidence of an increased risk of other solid cancers. The observed increase in the risk of cancer of the lip and pancreas should be treated with caution because of the limited amount of relevant data and because the observations may be simply due to chance. PMID:24022197

  10. Estimates of Radiation Effects on Cancer Risks in the Mayak Worker, Techa River and Atomic Bomb Survivor Studies.

    PubMed

    Preston, Dale L; Sokolnikov, Mikhail E; Krestinina, Lyudmila Yu; Stram, Daniel O

    2017-04-01

    For almost 50 y, the Life Span Study cohort of atomic bomb survivor studies has been the primary source of the quantitative estimates of cancer and non-cancer risks that form the basis of international radiation protection standards. However, the long-term follow-up and extensive individual dose reconstruction for the Russian Mayak worker cohort (MWC) and Techa River cohort (TRC) are providing quantitative information about radiation effects on cancer risks that complement the atomic bomb survivor-based risk estimates. The MWC, which includes ~26 000 men and women who began working at Mayak between 1948 and 1982, is the primary source for estimates of the effects of plutonium on cancer risks and also provides information on the effects of low-dose rate external gamma exposures. The TRC consists of ~30 000 men and women of all ages who received low-dose-rate, low-dose exposures as a consequence of Mayak's release of radioactive material into the Techa River. The TRC data are of interest because the exposures are broadly similar to those experienced by populations exposed as a consequence of nuclear accidents such as Chernobyl. In this presentation, it is described the strengths and limitations of these three cohorts, outline and compare recent solid cancer and leukemia risk estimates and discussed why information from the Mayak and Techa River studies might play a role in the development and refinement of the radiation risk estimates that form the basis for radiation protection standards. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. In vitro dissolution study of plutonium in aerosol particles from the Mayak PA: a tool for individualised dose estimates.

    PubMed

    Aladova, E E; Romanov, S A; Guilmette, R A; Khokhryakov, V F; Suslova, K G

    2007-01-01

    Chronic inhalation of Pu particles during Mayak processing is a potential concern for workers. Of the many particle properties that affect individualised dose estimates, particle solubility in lung fluids can be most important. This study compares in vitro dissolution rates of several plutonium industrial compounds present at different stages of the Mayak processing cycle using three different solvents. The results are then used to develop values of absorption parameters for individual dose assessments. In this study, the dissolution rates of nitrate, oxide and mixed plutonium aerosols were determined using a serum ultrafiltrate stimulant (SUF), phagolysosomal simulant fluid and Ringer's solution, all using a static system. According to the results obtained with SUF, Pu nitrate is absorbed into the blood to a larger extent than predicted using model parameters currently applied for Mayak workers. Absorption into the blood of 21.5 vs. 3% of deposited nuclide as current model predicts results in underestimation of systemic burden and overestimation of the lung dose. These data are being used to provide improved retrospective dose assessments for inhaled plutonium aerosols.

  12. An Opportunity to Immobilize 1.6 MT or More of Weapons-Grade Plutonium at the Mayak and Krasnoyarsk-26 Sites

    SciTech Connect

    Jardine, L J; Borisov, G B; Rovny, S I; Kudinov, K G; Shvedov, A A

    2001-06-29

    The Mayak Production Association (PA Mayak), an industrial site in Russia, will be assigned multiple new plutonium disposition missions in order to implement the ''Agreement Between The Government Of The United States Of America And The Government Of Russian Federation Concerning The Management And Disposition Of Plutonium Designated As No Longer Required For Defense Purposes And Related Cooperation'' signed September 1, 2000, by Gore and Kasyanov, In addition, the mission of industrial-scale mixed-oxide (MOX) fabrication will be assigned to either the Mining Chemical Combine (MCC) industrial site at Krasnoyarsk-26 (K-26) or PA Mayak. Over the next decades, these new missions will generate radioactive wastes containing weapons-grade plutonium. The existing Mayak and K-26 onsite facilities and infrastructures cannot currently treat and immobilize these Pu-containing wastes for storage and disposal. However, the wastes generated under the Agreement must be properly immobilized, treated, and managed. New waste treatment and immobilization missions at Mayak may include operating facilities for plutonium metal-to-oxide conversion processes, industrial-scale MOX fuel fabrication, BN-600 PAKET hybrid core MOX fuel fabrication, and a plutonium conversion demonstration process. The MCC K-26 site, if assigned the industrial-scale MOX fuel fabrication mission, would also need to add facilities to treat and immobilize the Pu-containing wastes. This paper explores the approach and cost of treatment and immobilization facilities at both Mayak and K-26. The current work to date at Mayak and MCC K-26 indicates that the direct immobilization of 1.6 MT of weapons-grade plutonium is a viable and cost-effective alternative.

  13. A Validated High-Let Radiation Specific Biomarker in the Mayak Worker Cohort

    SciTech Connect

    David J. Brenner, Ph.D., D.Sc.; Tamara Azizova, M.D.

    2006-12-11

    Our goal (see Project Objectives) is to deliver a dosimetry system which will enable both a Pu body burden of 0.3 kBq, and a 30 cGy {gamma} ray dose, to be separately estimated with a confidence limit of {+-}30%. In terms of the numbers analyzed and the data we have accrued, we have direct quantitative evidence that we are on track to providing such a comprehensive independent dosimetry system for Mayak workers. We had previously demonstrated that intra-chromosomal aberrations measured in peripheral blood lymphocytes can be used as a sensitive long-lived low-background quantitative biomarker of densely-ionizing radiation dose in individuals exposed many years ago. We propose to calibrate the system such that it can be used to estimate both the densely-ionizing internal plutonium exposure and the sparsely-ionizing external exposure in Mayak workers exposed to different combinations of these over a prolonged period, mostly many years ago. Our objective is to deliver a dosimetry system (set of calibration parameters) which will enable both a comparatively low Pu body burden of 0.3 kBq, and a comparatively low 30 cGy {gamma} ray dose (one of these or both of these) to be estimated with a confidence limit of {+-}30% (higher doses will of course be estimated with smaller confidence intervals and still lower doses with larger confidence intervals). (1) Draw blood, make metaphase slides and measure numbers of intra- and inter-chromosome aberrations (using the mBAND and mFISH techniques) in - (A) 255 healthy former Mayak workers who were exposed various combinations of internal and external exposures. The individuals were chosen from the data base of healthy former workers through computer simulation to optimize estimates of the dosimetry parameters. The individuals have both internal and external dose estimates from the SUBI Doses-99 system. (B) 85 healthy non-exposed controls with ages, gender, and smoking status, chosen based on computer simulation to optimize estimates

  14. Beyond two-stage models for lung carcinogenesis in the Mayak workers: implications for plutonium risk.

    PubMed

    Zöllner, Sascha; Sokolnikov, Mikhail E; Eidemüller, Markus

    2015-01-01

    Mechanistic multi-stage models are used to analyze lung-cancer mortality after Plutonium exposure in the Mayak-workers cohort, with follow-up until 2008. Besides the established two-stage model with clonal expansion, models with three mutation stages as well as a model with two distinct pathways to cancer are studied. The results suggest that three-stage models offer an improved description of the data. The best-fitting models point to a mechanism where radiation increases the rate of clonal expansion. This is interpreted in terms of changes in cell-cycle control mediated by bystander signaling or repopulation following cell killing. No statistical evidence for a two-pathway model is found. To elucidate the implications of the different models for radiation risk, several exposure scenarios are studied. Models with a radiation effect at an early stage show a delayed response and a pronounced drop-off with older ages at exposure. Moreover, the dose-response relationship is strongly nonlinear for all three-stage models, revealing a marked increase above a critical dose.

  15. Quantitative plutonium microdistribution in bone tissue of vertebra from a Mayak worker.

    PubMed

    Lyovkina, Yekaterina V; Miller, Scott C; Romanov, Sergey A; Krahenbuhl, Melinda P; Belosokhov, Maxim V

    2010-10-01

    The purpose of this study was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, the quantitative relationships of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in humans as well as other cases with different exposure patterns and types of plutonium.

  16. Beyond Two-Stage Models for Lung Carcinogenesis in the Mayak Workers: Implications for Plutonium Risk

    PubMed Central

    Zöllner, Sascha; Sokolnikov, Mikhail E.; Eidemüller, Markus

    2015-01-01

    Mechanistic multi-stage models are used to analyze lung-cancer mortality after Plutonium exposure in the Mayak-workers cohort, with follow-up until 2008. Besides the established two-stage model with clonal expansion, models with three mutation stages as well as a model with two distinct pathways to cancer are studied. The results suggest that three-stage models offer an improved description of the data. The best-fitting models point to a mechanism where radiation increases the rate of clonal expansion. This is interpreted in terms of changes in cell-cycle control mediated by bystander signaling or repopulation following cell killing. No statistical evidence for a two-pathway model is found. To elucidate the implications of the different models for radiation risk, several exposure scenarios are studied. Models with a radiation effect at an early stage show a delayed response and a pronounced drop-off with older ages at exposure. Moreover, the dose-response relationship is strongly nonlinear for all three-stage models, revealing a marked increase above a critical dose. PMID:26000637

  17. Cerebrovascular Diseases in Workers at Mayak PA: The Difference in Radiation Risk between Incidence and Mortality

    PubMed Central

    Simonetto, Cristoforo; Schöllnberger, Helmut; Azizova, Tamara V.; Grigoryeva, Evgenia S.; Pikulina, Maria V.; Eidemüller, Markus

    2015-01-01

    A detailed analysis of cerebrovascular diseases (CeVD) for the cohort of workers at Mayak Production Association (PA) is presented. This cohort is especially suitable for the analysis of radiation induced circulatory diseases, due to the detailed medical surveillance and information on several risk factors. The risk after external, typically protracted, gamma exposure is analysed, accounting for potential additional internal alpha exposure. Three different endpoints have been investigated: incidence and mortality from all cerebrovascular diseases and incidence of stroke. Particular emphasis was given to the form of the dose-response relationship and the time dependence of the radiation induced risk. Young attained age was observed to be an important, aggravating modifier of radiation risk for incidence of CeVD and stroke. For incidence of CeVD, our analysis supports a dose response sub-linear for low doses. Finally, the excess relative risk per dose was confirmed to be significantly higher for incidence of CeVD compared to CeVD mortality and incidence of stroke. Arguments are presented for this difference to be based on a true biological effect. PMID:25933038

  18. Ischemic Heart Disease in Workers at Mayak PA: Latency of Incidence Risk after Radiation Exposure

    PubMed Central

    Simonetto, Cristoforo; Azizova, Tamara V.; Grigoryeva, Evgenia S.; Kaiser, Jan C.; Schöllnberger, Helmut; Eidemüller, Markus

    2014-01-01

    We present an updated analysis of incidence and mortality from atherosclerotic induced ischemic heart diseases in the cohort of workers at the Mayak Production Association (PA). This cohort constitutes one of the most important sources for the assessment of radiation risk. It is exceptional because it comprises information on several other risk factors. While most of the workers have been exposed to external gamma radiation, a large proportion has additionally been exposed to internal radiation from inhaled plutonium. Compared to a previous study by Azizova et al. 2012, the updated dosimetry system MWDS-2008 has been applied and methods of analysis have been revised. We extend the analysis of the significant incidence risk and observe that main detrimental effects of external radiation exposure occur after more than about 30 years. For mortality, significant risk was found in males with an excess relative risk per dose of 0.09 (95% CI: 0.02; 0.16) while risk was insignificant for females. With respect to internal radiation exposure no association to risk could be established. PMID:24828606

  19. QUANTITATIVE PLUTONIUM MICRODISTRIBUTION IN BONE TISSUE OF VERTEBRA FROM A MAYAK WORKER

    PubMed Central

    Lyovkina, Yekaterina V.; Miller, Scott C.; Romanov, Sergey A.; Krahenbuhl, Melinda P.; Belosokhov, Maxim V.

    2010-01-01

    The purpose was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, quantitative relationship of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in human as well as other cases with different exposure patterns and types of plutonium. PMID:20838087

  20. Ischemic heart disease in workers at Mayak PA: latency of incidence risk after radiation exposure.

    PubMed

    Simonetto, Cristoforo; Azizova, Tamara V; Grigoryeva, Evgenia S; Kaiser, Jan C; Schöllnberger, Helmut; Eidemüller, Markus

    2014-01-01

    We present an updated analysis of incidence and mortality from atherosclerotic induced ischemic heart diseases in the cohort of workers at the Mayak Production Association (PA). This cohort constitutes one of the most important sources for the assessment of radiation risk. It is exceptional because it comprises information on several other risk factors. While most of the workers have been exposed to external gamma radiation, a large proportion has additionally been exposed to internal radiation from inhaled plutonium. Compared to a previous study by Azizova et al. 2012, the updated dosimetry system MWDS-2008 has been applied and methods of analysis have been revised. We extend the analysis of the significant incidence risk and observe that main detrimental effects of external radiation exposure occur after more than about 30 years. For mortality, significant risk was found in males with an excess relative risk per dose of 0.09 (95% CI: 0.02; 0.16) [Formula: see text] while risk was insignificant for females. With respect to internal radiation exposure no association to risk could be established.

  1. Status of ecosystems in radioactive waste reservoirs of the Mayak Production Association in 2009.

    PubMed

    Pryakhin, Evgeny A; Tryapitsina, Galina A; Deryabina, Larisa V; Atamanyuk, Natalia I; Stukalov, Pavel M; Ivanov, Ivan A; Kostyuchenko, Vladimir A; Akleyev, Alexander V

    2012-07-01

    Liquid radioactive waste from the Mayak Production Association (Chelyabinsk Region, Russia) is contained in industrial reservoirs (R-11, R-10, R-4, R-17, and R-9) that have different levels of radioactive contamination, increased from R-11 to R-17. A study of the ecosystems in these reservoirs was performed in 2009 to determine if there was any association with the level of contamination. No significant change in the status of biota was found in the reservoir with the lowest radionuclide concentrations (R-11) in comparison to other reservoirs in the region with a similar geography that are unaffected by radioactive contamination. In reservoir R-10, changes in the zoobenthos indices were registered. In reservoir R-4, changes in the zoobenthos and zooplankton communities were registered. In reservoir R-17, there was no ichthyofauna, but strong changes in the phytoplankton, zooplankton, and zoobenthos communities were registered. In reservoir R-9, under the conditions of the heaviest radioactive contamination of water ecosystems in the biosphere, there was no ichthyofauna, and phytoplankton and zooplankton consisted of almost a monoculture of cyanobacteriae and rotifers.

  2. Use of in vivo counting measurements to estimate internal doses from (241)Am in workers from the Mayak production association.

    PubMed

    Sokolova, Alexandra B; Suslova, Klara G; Efimov, Alexander V; Miller, Scott C

    2014-08-01

    Comparisons between results of in vivo counting measurements of americium burden and results from radiochemical analyses of organ samples taken at autopsy of 11 cases of former Mayak workers were made. The in vivo counting measurements were performed 3-8 y before death. The best agreement between in vivo counting measurements for americium and autopsy data was observed for the skull. For lungs and liver, the ratios of burden measured by in vivo counting to those obtained from radiochemical analyses data ranged from 0.7-3.8, while those for the skull were from 1.0-1.1. There was a good correlation between the estimates of americium burden in the entire skeleton obtained from in vivo counting with those obtained from autopsy data. Specifically, the skeletal burden ratio, in vivo counting/autopsy, averaged 0.9 ± 0.1. The prior human americium model, D-Am2010, used in vivo counting measurements for americium in the skeleton to estimate the contents of americium and plutonium at death. The results using this model indicate that in vivo counting measurements of the skull can be used to estimate internal doses from americium in the Mayak workers. Additionally, these measurements may also be used to provide a qualitative assessment of internal doses from plutonium.

  3. Accumulation, organ distribution, and excretion kinetics of ²⁴¹Am in Mayak Production Association workers.

    PubMed

    Suslova, Klara G; Sokolova, Alexandra B; Efimov, Alexander V; Miller, Scott C

    2013-03-01

    Americium-241 (²⁴¹Am) is the second most significant radiation hazard after ²³⁹Pu at some of the Mayak Production Association facilities. This study summarizes current data on the accumulation, distribution, and excretion of americium compared with plutonium in different organs from former Mayak PA workers. Americium and plutonium were measured in autopsy and bioassay samples and correlated with the presence or absence of chronic disease and with biological transportability of the aerosols encountered at different workplaces. The relative accumulation of ²⁴¹Am was found to be increasing in the workers over time. This is likely from ²⁴¹Pu that increases with time in reprocessed fuel and from the increased concentrations of ²⁴¹Am and ²⁴¹Pu in inhaled alpha-active aerosols. While differences were observed in lung retention with exposures to different industrial compounds with different transportabilities (i.e., dioxide and nitrates), there were no significant differences in lung retention between americium and plutonium within each transportability group. In the non-pulmonary organs, the highest ratios of ²⁴¹Am/²⁴¹Am + SPu were observed in the skeleton. The relative ratios of americium in the skeleton versus liver were significantly greater than for plutonium. The relative amounts of americium and plutonium found in the skeleton compared with the liver were even greater in workers with documented chronic liver diseases. Excretion rates of ²⁴¹Am in ‘‘healthy’’ workers were estimated using bioassay and autopsy data. The data suggest that impaired liver function leads to reduced hepatic ²⁴¹Am retention, leading to increased ²⁴¹Am excretion.

  4. Ischaemic heart disease incidence and mortality in an extended cohort of Mayak workers first employed in 1948–1982

    PubMed Central

    Grigoryeva, Evgeniya S; Haylock, Richard G E; Pikulina, Maria V; Moseeva, Maria B

    2015-01-01

    Objective: Incidence and mortality from ischaemic heart disease (IHD) was studied in an extended cohort of 22,377 workers first employed at the Mayak Production Association during 1948–82 and followed up to the end of 2008. Methods: Relative risks and excess relative risks per unit dose (ERR/Gy) were calculated based on the maximum likelihood using Epicure software (Hirosoft International Corporation, Seattle, WA). Dose estimates used in analyses were provided by an updated “Mayak Worker Dosimetry System—2008”. Results: A significant increasing linear trend in IHD incidence with total dose from external γ-rays was observed after having adjusted for non-radiation factors and dose from internal radiation {ERR/Gy = 0.10 [95% confidence interval (CI): 0.04 to 0.17]}. The pure quadratic model provided a better fit of the data than did the linear one. No significant association of IHD mortality with total dose from external γ-rays after having adjusted for non-radiation factors and dose from internal alpha radiation was observed in the study cohort [ERR/Gy = 0.06 (95% CI: <0 to 0.15)]. A significant increasing linear trend was observed in IHD mortality with total absorbed dose from internal alpha radiation to the liver after having adjusted for non-radiation factors and dose from external γ-rays in both the whole cohort [ERR/Gy = 0.21 (95% CI: 0.01 to 0.58)] and the subcohort of workers exposed at alpha dose <1.00 Gy [ERR/Gy = 1.08 (95% CI: 0.34 to 2.15)]. No association of IHD incidence with total dose from internal alpha radiation to the liver was found in the whole cohort after having adjusted for non-radiation factors and external gamma dose [ERR/Gy = 0.02 (95% CI: not available to 0.10)]. Statistically significant dose effect was revealed in the subcohort of workers exposed to internal alpha radiation at dose to the liver <1.00 Gy [ERR/Gy = 0.44 (95% CI: 0.09 to 0.85)]. Conclusion: This study provides strong evidence of IHD

  5. The cascade of reservoirs of the ``Mayak`` Plant: Case history and the first version of a computer simulator

    SciTech Connect

    Mironenko, M.V.; Spasennykh, M.Yu.; Polyakov, V.B.

    1994-07-01

    The improvement of the ecological conditions at waste storing reservoirs is an important task of the restoration activity at Production Association (PA) ``Mayak`` (South Urals). The radionuclides mostly {sup 90}Sr, {sup 137}Cs, and chemical pollutants deposited in the reservoir water and in the bottom sediment are very dangerous sources for the contamination of Techa River below the reservoirs and the contamination of groundwater in the surrounding formations. The spreading of radioactive contaminants has both hydrogeological and the chemical features. The thermodynamic approach used to account for physical-chemical interactions between water and the bed rocks based on Gibbs free energy minimization of multicomponent system (H-O-Ca-Mg-K-Na-S-Cl-C-Sr) permitted the authors to calculate the corresponding ionic and complex species existing in the solutions, and to characterize the processes of precipitation and dissolution. The model takes into account the input and output surface and underground water fluxes, mass exchange of the reservoir with the atmosphere, radioactive decay and water-sediment interaction including processes of the {sup 90}Sr and {sup 137}Cs sorption on the grains of the sediment and the radionuclide diffusion in the pore water. This model was used in the retrospective and prognosis calculations of radiation and hydrochemical regime of these reservoirs.

  6. The effects of smoking and lung health on the organ retention of different plutonium compounds in the Mayak PA workers.

    PubMed

    Suslova, K G; Sokolova, A B; Krahenbuhl, M P; Miller, S C

    2009-03-01

    The purpose of this study was to determine the effects of smoking and lung health on the pulmonary and extrapulmonary retention after inhalation of different chemical forms of plutonium with different solubilities in workers from the Mayak Production Association (Ozersk, Russia). Samples of lung, pulmonary lymph nodes, liver and skeleton were obtained from 800 workers who died between 1962-2000. The chemical form of plutonium aerosols, smoking history and presence of lung disease were determined. In workers with normal lung status, all plutonium chemical classes were about equally distributed between the lung parenchyma and pulmonary lymph nodes. The more insoluble chemical forms of plutonium had a greater retention in pulmonary than systemic tissues regardless of smoking history or lung health status. A history of smoking did, however, result in a significantly greater retention of less soluble chemical forms of plutonium in pulmonary tissues of workers with no lung disease. In workers with lung disease, smoking did not significantly influence the terminal organ retention of the different chemical forms of plutonium. These initial data can be used to modify dosimetry and biokinetics models used for estimating radiation risks from plutonium in humans.

  7. A joint Russian-American field test at the Chelyabinsk-65 (Mayak) Site: Test description and preliminary results

    SciTech Connect

    Wollenberg, H.; Tsang, C.F.; Frangos, W.

    1995-05-01

    In September 1994, a Russian-American team conducted hydrogeological, geochemical, geophysical, and radiometric measurements in the territory of the Mayak Production Association. The primary purpose of these operations was to examine the groundwater plume moving from Lake Karachai toward the river. Activities encompassed isolation of hydrologic intervals in two wells and production of water from these intervals, to compare isolated versus open-well sampling methods; surface and soil-water sampling, accompanying radiometric measurements and subsequent chemical analyses; and electrical resistivity profiling in areas of expected contrasting resistivity. Preliminary results indicate that (1) {sup 60}Co and {sup 137}Cs are present in small concentrations in water of the Mishelyak River, (2) analyses of water samples collected by a downhole sampler and of water produced from packed-off intervals agree within limits of laboratory accuracy, attesting to the efficacy of the sampling methods presently used by the Russian workers; and (3) strong contrasts occur between the electrical resistivities of soil and bedrock. Further collaborative work is strongly recommended, and should include more detailed isolation of intervals in wells by multi-packer installations, to better determine the geochemical and hydrological characteristics of the Karachai-Mishelyak system; deployment of a broader soil-water and soil sampling array; a more detailed examination of the distribution and concentration of radionuclides by high-resolution field gamma spectrometry; and a detailing of the area`s electrical resistivity setting, using a mobile electromagnetic measurement system.

  8. Radiation risk of malignant neoplasms in organs of main deposition for plutonium in the cohort of Mayak workers with regard to histological types.

    PubMed

    Labutina, E V; Kuznetsova, I S; Hunter, N; Harrison, J; Koshurnikova, N A

    2013-08-01

    This paper presents the results of analyses of the incidence of malignant neoplasms in lung, liver, and bone and associated connective tissues among Mayak nuclear workers exposed to both internally incorporated plutonium and to external gamma radiation. The study cohort included 22,373 individuals employed at the reactors and radiochemical and plutonium production facilities of the Mayak nuclear complex during 1948-1982 and followed up to the end of 2004. All analyses were carried out by Poisson regression, and the doses used were derived using a recently available update of organ doses, Mayak doses-2008. There was clear evidence for the linear association between internal plutonium dose and the risk of lung cancer. For males, there was evidence of a significant internal plutonium dose response for all histological types of lung cancer evaluated (adenocarcinoma, squamous-cell, and other epithelial); the estimated excess relative risk (ERR)/Gy for adenocarcinoma was the largest (ERR/Gy = 32.5; 95% CI: 16.3; 71.9), about 11-fold higher than that for squamous-cell lung cancer (ERR/Gy = 3.1; 95% CI: 0.3; 9.1). The relationship between liver cancer risk and plutonium exposure was best described by a linear-quadratic (LQ) function, but the LQ effect was diminished after restricting internal doses <2 Gy. Hepatocellular cancer was the most frequently observed type of liver cancer associated with internal plutonium exposure, and hemangiosarcomas were exclusively observed only at high internal plutonium doses (>4 Gy). For malignant neoplasms of bone and associated connective tissues, the trend was not statistically significant in relation to internal plutonium dose, but a statistically significantly higher risk (RR=13.7; 95% CI= 3.0; 58.5) was found among unmonitored female plutonium workers who were employed in the most hazardous plutonium production facility commissioned prior to 1950.

  9. Radiation Effects on Mortality from Solid Cancers Other than Lung, Liver, and Bone Cancer in the Mayak Worker Cohort: 1948–2008

    PubMed Central

    Sokolnikov, Mikhail; Preston, Dale; Gilbert, Ethel; Schonfeld, Sara; Koshurnikova, Nina

    2015-01-01

    Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948–2008. The cohort of Mayak Production Association (PA) workers in Russia offers a unique opportunity to study the effects of prolonged low dose rate external gamma exposures and exposure to plutonium in a working age population. We examined radiation effects on the risk of mortality from solid cancers excluding sites of primary plutonium deposition (lung, liver, and bone surface) among 25,757 workers who were first employed in 1948–1982. During the period 1948–2008, there were 1,825 deaths from cancers other than lung, liver and bone. Using colon dose as a representative external dose, a linear dose response model described the data well. The excess relative risk per Gray for external gamma exposure was 0.16 (95% CI: 0.07 – 0.26) when unadjusted for plutonium exposure and 0.12 (95% CI 0.03 – 0.21) when adjusted for plutonium dose and monitoring status. There was no significant effect modification by sex or attained age. Plutonium exposure was not significantly associated with the group of cancers analyzed after adjusting for monitoring status. Site-specific risks were uncertainly estimated but positive for 13 of the 15 sites evaluated with a statistically significant estimate only for esophageal cancer. Comparison with estimates based on the acute exposures in atomic bomb survivors suggests that the excess relative risk per Gray for prolonged external exposure in Mayak workers may be lower than that for acute exposure but, given the uncertainties, the possibility of equal effects cannot be dismissed. PMID:25719381

  10. Mortality from solid cancers other than lung, liver, and bone in relation to external dose among plutonium and non-plutonium workers in the Mayak Worker Cohort.

    PubMed

    Sokolnikov, Mikhail; Preston, Dale; Stram, Daniel O

    2017-03-01

    Exposure to ionizing radiation has well-documented long-term effects on cancer rates and other health outcomes in humans. While in vitro experimental studies had demonstrated that the nature of some radiation effects depend on both total dose of the radiation and the dose rate (i.e., the pattern of dose distribution over time), the question of whether or not the carcinogenic effect of radiation exposure depends on the dose rate remains unanswered. Another issue of interest concerns whether or not concomitant exposure to external gamma rays and inhaled plutonium aerosols has any effect on the external exposure effects. The analyses of the present paper focus on the risk of solid cancers at sites other than lung, liver, and bone in Mayak workers. Recent findings are reviewed indicating that there is no evidence of plutonium dose response for these cancers in the Mayak worker cohort. Then the evidence for differences in the external dose effects among workers with and without the potential for exposure to alpha particles from inhaled plutonium is examined. It is found that there is no evidence that exposure to plutonium aerosols significantly affects the risk associated with external exposure. While the Mayak external dose risk estimate of an excess relative risk of 0.16 per Gy is somewhat lower than an appropriately normalized risk estimate from the Life Span Study of Japanese atomic bomb survivors, the uncertainties in these estimates preclude concluding that the external dose excess relative risks of this group of solid cancers differ in the two cohorts.

  11. Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948-2008.

    PubMed

    Sokolnikov, Mikhail; Preston, Dale; Gilbert, Ethel; Schonfeld, Sara; Koshurnikova, Nina

    2015-01-01

    Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948-2008. The cohort of Mayak Production Association (PA) workers in Russia offers a unique opportunity to study the effects of prolonged low dose rate external gamma exposures and exposure to plutonium in a working age population. We examined radiation effects on the risk of mortality from solid cancers excluding sites of primary plutonium deposition (lung, liver, and bone surface) among 25,757 workers who were first employed in 1948-1982. During the period 1948-2008, there were 1,825 deaths from cancers other than lung, liver and bone. Using colon dose as a representative external dose, a linear dose response model described the data well. The excess relative risk per Gray for external gamma exposure was 0.16 (95% CI: 0.07 - 0.26) when unadjusted for plutonium exposure and 0.12 (95% CI 0.03 - 0.21) when adjusted for plutonium dose and monitoring status. There was no significant effect modification by sex or attained age. Plutonium exposure was not significantly associated with the group of cancers analyzed after adjusting for monitoring status. Site-specific risks were uncertainly estimated but positive for 13 of the 15 sites evaluated with a statistically significant estimate only for esophageal cancer. Comparison with estimates based on the acute exposures in atomic bomb survivors suggests that the excess relative risk per Gray for prolonged external exposure in Mayak workers may be lower than that for acute exposure but, given the uncertainties, the possibility of equal effects cannot be dismissed.

  12. Mortality coefficients among personnel of radiochemical plants of {open_quotes}Mayak{close_quotes}-Combine for 40-year period of observation

    SciTech Connect

    Koshurnikova, N.A.; Komleva, N.S.; Baisogolov, G.D.

    1993-12-31

    The results of the epidemiological research, conducted among the personnel of the radiochemical plants of {open_quotes}Mayak{close_quotes}. Combine are as follows: during the 40-year-period of observation the mortality rate from all and separate causes, except age, is lower, than the expected one, which is calculated on the basis of the National Statistics. Oncological mortality rate is reliably higher, than the expected one, which is conditioned by the high frequency of lung cancer and leucaemia. Internal {alpha}-irradiation plays the leading role in the induction of lung cancer, and the increase of mortality rate from leukemia is closely connected with external {gamma}-irradiation.

  13. Point Intercept (PO)

    Treesearch

    John F. Caratti

    2006-01-01

    The FIREMON Point Intercept (PO) method is used to assess changes in plant species cover or ground cover for a macroplot. This method uses a narrow diameter sampling pole or sampling pins, placed at systematic intervals along line transects to sample within plot variation and quantify statistically valid changes in plant species cover and height over time. Plant...

  14. The development of the plutonium lung clearance model for exposure estimation of the Mayak production association, nuclear plant workers.

    PubMed

    Khokhryakov, Valentin F; Suslova, Klara G; Vostrotin, Vadim V; Romanov, Sergey A; Menshikh, Zoya S; Kudryavtseva, Tamara I; Filipy, Ronald E; Miller, Scott C; Krahenbuhl, Melinda P

    2002-04-01

    The purpose of this study was to develop a biokinetic model that uses urinary plutonium excretion rate data to estimate the plutonium accumulation in the human respiratory tract after occupational exposure. The model is based on autopsy and urinalysis data, specifically the plutonium distribution between the respiratory tract and the remainder of the body, taken from 543 former workers of a radiochemical facility at the Mayak Production Association (MPA) plant. The metabolism of plutonium was represented with a compartmental model, which considers individual exposure histories and the inherent solubility properties of industrial plutonium aerosols. The transport properties of plutonium-containing aerosols were estimated by experimentally defining their in vitro solubility. The in vitro solubilities were found by dialysis in a Ringer's solution. Analysis of the autopsy data indicated that a considerable fraction of the inhaled plutonium is systemically redistributed rapidly after inhalation. After the initial dynamic period, a three-compartment model describes the retention in the respiratory tract. One compartment describes the nuclide retained in the lungs, the second compartment describes a plutonium lung concentration that exponentially decreases with time, and the third compartment describes the concentration in the pulmonary lymph nodes. The model parameters were estimated by minimizing sum squared of the error between the tissue and bioassay data and the model results. The parameters reflect the inverse relationship between plutonium retention in lungs and the experimentally derived aerosol transportability. The model was validated by comparing the autopsy results with in vivo data for 347 cases. The validation indicates that the model parameters are unbiased. This model is being used to estimate individual levels of nuclide accumulation and to compute radiation doses based upon the urinary excretion rates.

  15. REEVALUATION OF WATERBORNE RELEASES OF RADIOACTIVE MATERIALS FROM THE MAYAK PRODUCTION ASSOCIATION INTO THE TECHA RIVER IN 1949-1951

    SciTech Connect

    Degteva, M. O.; Shagina, N. B.; Vorobiova, M. I.; Anspaugh, L. R.; Napier, Bruce A.

    2012-01-01

    The Mayak Production Association was the first site for the production of weapon-grade plutonium in Russia. Early operations led to the waterborne release of large amounts of radioactive materials into the small Techa River. Residents living downstream used river water for drinking and other purposes. The releases and subsequent flooding resulted in the deposition of sediments along the shoreline and on floodplain soil. Primary routes of exposure were external dose from the deposited sediments and the ingestion of 90Sr and other radionuclides. Study of the Techa River Cohort has revealed an increased incidence of leukemia and solid cancers. These epidemiologic studies are supported by extensive dose-reconstruction activities that have led to the creation of various versions of a Techa River Dosimetry System (TRDS). The correctness of the TRDS has been challenged by the allegation that releases of short-lived radionuclides were much larger than those used in the TRDS. Although the dosimetry system depends more upon the measurements of 90Sr in humans and additional measurements of radionuclides and of exposure rates in the environment, a major activity has been undertaken to define more precisely the time-dependent rates of release and radionuclide composition of the releases. The major releases occurred during 1950-1951. In addition to routine releases major accidental releases occurred. The re-evaluated amount of total release is 114 PBq, about half of which was from accidents that occurred in late 1951. The composition of the radionuclides released has also been re-evaluated; this composition changed with time.

  16. Multiscale Speciation of U and Pu at Chernobyl, Hanford, Los Alamos, McGuire AFB, Mayak, and Rocky Flats.

    PubMed

    Batuk, Olga N; Conradson, Steven D; Aleksandrova, Olga N; Boukhalfa, Hakim; Burakov, Boris E; Clark, David L; Czerwinski, Ken R; Felmy, Andrew R; Lezama-Pacheco, Juan S; Kalmykov, Stepan N; Moore, Dean A; Myasoedov, Boris F; Reed, Donald T; Reilly, Dallas D; Roback, Robert C; Vlasova, Irina E; Webb, Samuel M; Wilkerson, Marianne P

    2015-06-02

    The speciation of U and Pu in soil and concrete from Rocky Flats and in particles from soils from Chernobyl, Hanford, Los Alamos, and McGuire Air Force Base and bottom sediments from Mayak was determined by a combination of X-ray absorption fine structure (XAFS) spectroscopy and X-ray fluorescence (XRF) element maps. These experiments identify four types of speciation that sometimes may and other times do not exhibit an association with the source terms and histories of these samples: relatively well ordered PuO2+x and UO2+x that had equilibrated with O2 and H2O under both ambient conditions and in fires or explosions; instances of small, isolated particles of U as UO2+x, U3O8, and U(VI) species coexisting in close proximity after decades in the environment; alteration phases of uranyl with other elements including ones that would not have come from soils; and mononuclear Pu-O species and novel PuO2+x-type compounds incorporating additional elements that may have occurred because the Pu was exposed to extreme chemical conditions such as acidic solutions released directly into soil or concrete. Our results therefore directly demonstrate instances of novel complexity in the Å and μm-scale chemical speciation and reactivity of U and Pu in their initial formation and after environmental exposure as well as occasions of unexpected behavior in the reaction pathways over short geological but significant sociological times. They also show that incorporating the actual disposal and site conditions and resultant novel materials such as those reported here may be necessary to develop the most accurate predictive models for Pu and U in the environment.

  17. Methods For Calculating Thyroid Doses to The Residents Of Ozersk Due to 131I Releases From The Stacks of The Mayak Production Association

    SciTech Connect

    Rovny, Sergey I.; Mokrov, Y.; Stukalov, Pavel M.; Beregich, D. A.; Teplyakov, I. I.; Anspaugh, L. R.; Napier, Bruce A.

    2009-10-23

    The Mayak Production Association (MPA) was established in the late 1940s in accordance with a special Decree of the USSR Government for the production of nuclear weapons. In early years of MPA operation, due to the lack of experience and absence of effective methods of RW management, the enterprise had extensive routine (designed) and non-routine (accidental) releases of gaseous radioactive wastes to the atmosphere. These practices resulted in additional technogenic radiation exposure of residents inhabiting populated areas near the MPA. The primary objective of ongoing studies under JCCRER Project 1.4 is to estimate doses to the residents of Ozersk due to releases of radioactive substances from the stacks of MPA. Preliminary scoping studies have demonstrated that releases of radioactive iodine (131I) from the stacks of the Mayak Radiochemical Plant represented the major contribution to the dose to residents of Ozersk and of other nearby populated areas. The behavior of 131I in the environment and of 131I migration through biological food chains (vegetation-cows-milk-humans) indicated a need for use of special mathematical models to perform the estimation of radiation doses to the population. The goal of this work is to select an appropriate model of the iodine migration in biological food chains and to justify numerical values of the model parameters.

  18. The Strategy of Elaborating a Common Approach to Solve the Problems of Surface and Ground Waters Contamination at the PA "Mayak" Territory Based on the International Co-operation Experience

    NASA Astrophysics Data System (ADS)

    Glinsky, M.; Hutter, A.; Drozhko, E. G.

    2001-12-01

    In the early 90's international organizations showed great interest concerning the contamination problems at the PA "Mayak" territory, where liquid radioactive wastes have been stored on the surface, including Lake Karachay, reservoir "Staroye Boloto" and the Techa River cascade reservoirs. As a result of this interest, international contracts funded by DOE (USA), NRRA, EC and DGXL were instituted to study the experience of radioactive waste management accumulated at the PA "Mayak" territory, including proposed rehabilitation of the contaminated territories. However, at the initial stage of international research, the works were not coordinated and often duplicated each other, which was taken by the public and mass media as a serious divergence of opinion between the scientists on the risk assessment for the population. Many years of research resulted in elaboration of a common scientific approach to the solution of the problems of water resources contamination at the PA "Mayak" territory. A successful experience of coordinating the international projects to study radionuclide migration with surface and ground waters at the PA "Mayak" territory is demonstrated, as well as the risk assessment for the population. Substantiation for rehabilitation measures can be based on long-term predictions and modeling research that are continuing under these international projects.

  19. A dose-dependent perturbation in cardiac energy metabolism is linked to radiation-induced ischemic heart disease in Mayak nuclear workers.

    PubMed

    Azimzadeh, Omid; Azizova, Tamara; Merl-Pham, Juliane; Subramanian, Vikram; Bakshi, Mayur V; Moseeva, Maria; Zubkova, Olga; Hauck, Stefanie M; Anastasov, Nataša; Atkinson, Michael J; Tapio, Soile

    2017-02-07

    Epidemiological studies show a significant increase in ischemic heart disease (IHD) incidence associated with total external gamma-ray dose among Mayak plutonium enrichment plant workers. Our previous studies using mouse models suggest that persistent alteration of heart metabolism due to the inhibition of peroxisome proliferator-activated receptor (PPAR) alpha accompanies cardiac damage after high doses of ionising radiation. The aim of the present study was to elucidate the mechanism of radiation-induced IHD in humans. The cardiac proteome response to irradiation was analysed in Mayak workers who were exposed only to external doses of gamma rays. All participants were diagnosed during their lifetime with IHD that also was the cause of death. Label-free quantitative proteomics analysis was performed on tissue samples from the cardiac left ventricles of individuals stratified into four radiation dose groups (0 Gy, < 100 mGy, 100-500 mGy, and > 500 mGy). The groups could be separated using principal component analysis based on all proteomics features. Proteome profiling showed a dose-dependent increase in the number of downregulated mitochondrial and structural proteins. Both proteomics and immunoblotting showed decreased expression of several oxidative stress responsive proteins in the irradiated hearts. The phosphorylation of transcription factor PPAR alpha was increased in a dose-dependent manner, which is indicative of a reduction in transcriptional activity with increased radiation dose. These data suggest that chronic external radiation enhances the risk for IHD by inhibiting PPAR alpha and altering the expression of mitochondrial, structural, and antioxidant components of the heart.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  1. Stochastic effects of environmental radiation exposure in populations living near the Mayak Industrial Association: preliminary report on study of cancer morbidity.

    PubMed

    Kossenko, M M; Hoffman, D A; Thomas, T L

    2000-07-01

    The Mayak Industrial Association, located in the South Ural Mountains, began operation in 1948 and was the first Russian site for the production and separation of plutonium. During the early days of operation, technological failures resulted in the release of large amounts of radioactive waste into the Techa River. Residents who lived in villages on the banks of the Techa and Iset Rivers were exposed to varying levels of radioactivity. The objective of this study is to assess stochastic (carcinogenic) effects in populations exposed to offsite releases of radioactive materials from the Mayak nuclear facility in Russia. Subjects of the present study are those individuals who lived during the period January 1950 through December 1960 in any of the exposed villages along the Techa River in Chelyabinsk Oblast. Death certificates and cancer incidence data have been routinely collected in the past from a five-rayon catchment area of Chelyabinsk Oblast. The registry of exposed residents along the Techa River assembled and maintained by the Urals Research Center for Radiation Medicine for the past 40 y is the basis for identifying study subjects for this project. Specific study objectives are to evaluate the incidence of cancer among current and former residents of Chelyabinsk Oblast who are in the exposed Techa River cohort; integrate results from the dose-reconstruction study to estimate doses for risk assessment; and develop a structure for maintaining continued follow-up of the cohort for cancer incidence. In the earlier part of our collaborative effort, the focus has been to enhance the cancer morbidity registry by updating it with cancer cases diagnosed through 1997, to conduct a series of validation procedures to ensure completeness and accuracy of the registry, and to reduce the numbers of subjects lost to follow-up. A feasibility study to determine cancer morbidity in migrants from the catchment area has been proposed. Our preliminary analyses of cancer morbidity

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

    NASA Astrophysics Data System (ADS)

    Andel, B.

    2015-10-01

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

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

    PubMed

    Zeng, Yuewu

    2015-06-01

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

  4. Representative Doses to Members of the Public from Atmospheric Releases of 131I at the Mayak Production Association Facilities from 1948 through 1972

    SciTech Connect

    Eslinger, Paul W.; Napier, Bruce A.; Anspaugh, Lynn R.

    2014-04-03

    Scoping epidemiologic studies performed by researchers from the Southern Urals Biophysics Institute revealed an excess prevalence of thyroid nodules and an increased incidence of thyroid cancer among residents of Ozersk, Russia, who were born in the early 1950s. Ozersk is located about 5 km from the facilities where the Mayak Production Association produced nuclear materials for the Russian weapons program. Reactor operations began in June 1948 and chemical separation of plutonium from irradiated fuel began in February 1949. The U.S.–Russia Joint Coordinating Committee on Radiation Effects Research conducted a series of projects over a 10-year period to assess the radiation risks in the Southern Urals. This paper uses data collected under Committee projects to reconstruct individual time-dependent thyroid doses to reference individuals living in Ozersk from 131I released to the atmosphere. Between 3.22×1016 and 4.31×1016 Bq of 131I released may have been released during the 1948–1972 time period, and a best estimate is 3.76×1016 Bq. A child born in 1947 is estimated to have received a cumulative thyroid dose of 2.3 Gy for 1948–1972, with a 95% confidence interval of 0.51–7.3 Gy. Annual doses were the highest in 1949 and a child who was 5 years old in 1949 is estimated to have a received an annual thyroid dose of 0.93 Gy with a 95% confidence interval of 0.19–3.5 Gy.

  5. Reconstruction of the contamination of the Techa River in 1949-1951 as a result of releases from the "Mayak" Production Association.

    PubMed

    Shagina, N B; Vorobiova, M I; Degteva, M O; Peremyslova, L M; Shishkina, E A; Anspaugh, L R; Napier, B A

    2012-11-01

    More accurate reconstruction of the radioactive contamination of the Techa River system in 1949-1951 has been made on the basis of refined data on the amounts and the rate of discharge of radionuclides into the Techa River from the Mayak Production Association; this has led to the development of a modified Techa River model that describes the transport of radionuclides through the up-river ponds and along the Techa River and deposition of radionuclides in the river-bottom sediments and flooded areas. The refined Techa River source-term data define more precisely the time-dependent rates of release and radionuclide composition of the releases that occurred during 1949-1951. The Techa River model takes into account the time-dependent characteristics of the releases and considers (a) the transport of radionuclides adsorbed on solid particles originally contained in the discharges or originating in the up-river ponds as a result of stirring up of contaminated bottom sediments and (b) the transport of radionuclides in soluble form. The output of the Techa River model provides concentrations of all source-term radionuclides in the river water, bottom sediments, and floodplain soils at different distances from the site of radioactive releases for the period of major contamination in 1950-1951. The outputs of the model show good agreement with historical measurements of water and sediment contamination. In addition, the river-model output for (90)Sr concentration in the river water is harmonized with retrospective estimates derived from the measurements of (90)Sr in the residents of the Techa Riverside villages. Modeled contamination of the floodplain soils by (137)Cs is shown to be in agreement with the values reconstructed from late measurements of this radionuclide. Reconstructed estimates of the Techa River contamination are being used for the quantification of internal and external doses received by residents of the Techa Riverside communities.

  6. Risk of solid cancer in the offspring of female workers of the Mayak nuclear facility in the Southern Urals, Russian Federation.

    PubMed

    Tsareva, Y; Deltour, I; Sokolnikov, M; Okatenko, P; Vostrotin, V V; Schonfeld, S J; Schüz, J

    2016-08-01

    Studies of cancer risk following in utero exposure to ionizing radiation are limited in number, particularly for adult-onset cancers, and the evidence is unclear. In the present study, the risk of solid cancer incidence following in utero radiation exposure is examined among 8466 offspring of female nuclear workers at one of the largest nuclear facilities (Mayak Production Association) in the Russian Federation. Poisson regression methods were used to estimate excess relative risks (ERRs) per Gray (Gy). Mother's uterine gamma dose served as a surrogate for fetal gamma dose. During 277,002 person-years of follow-up (1948-2009), there were 177 first primary solid cancers excluding non-melanoma skin cancers. Estimated in utero gamma and plutonium doses exceeded zero for 41 and 23 % of offspring, respectively. Of the 177 solid cancers, 66 occurred among individuals with some in utero exposure to gamma radiation and 53 among those with estimated plutonium exposures. There was no indication of a statistically significantly increased risk of solid cancer incidence from in utero gamma exposure (linear ERR/Gy -1.0; upper 95 % confidence limit 0.5). This result was unchanged after accounting for subsequent occupational exposure. Plutonium doses were estimated but were too low to obtain meaningful risk estimates. Thus, in this cohort in utero radiation exposure was not associated with solid cancer risk. This is consistent with an earlier report of mortality in the cohort, but is based on twice as many cases and less susceptible to biases inherent in mortality analyses. Given the relatively young age of the cohort with respect to cancer, continued follow-up should be done as the number of cancer cases increases.

  7. Kinetics of neutralization of Po-218

    SciTech Connect

    Chu, K.D.

    1987-01-01

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

  8. Ultraviolet luminescence of ScPO4, AlPO4 and GaPO4 crystals.

    PubMed

    Trukhin, Anatoly N; Shmits, Krishjanis; Jansons, Janis L; Boatner, Lynn A

    2013-09-25

    The luminescence of self-trapped excitons (STEs) was previously observed and described for the case of tetragonal-symmetry ScPO4 single crystals. The subject band in this material is situated in the UV spectral range of ∼210 nm or ∼5.8 eV. In the present work, we are both expanding this earlier luminescence study and seeking to identify similar luminescence phenomena in other orthophosphate crystals, i.e., AlPO4 and GaPO4. These efforts have proven to be successful--in spite of the structural differences between these materials and ScPO4. Specifically we have found that for AlPO4 and GaPO4, in addition to an α-quartz-like STE, there is a UV luminescence band that is similar in position and decay properties to that of ScPO4 crystals. Potentially this represents an STE in AlPO4 and GaPO4 crystals that is analogous to the STE of ScPO4 and other orthophosphates. The decay kinetics of the UV luminescence of ScPO4 was studied over a wide temperature range from 8 to 300 K, and they exhibited some unusual decay characteristics when subjected to pulses from an F2 excimer laser (157 nm). These features could be ascribed to a triplet state of the STE that is split in a zero magnetic field. A fast decay of the STE was detected as well, and therefore, we conclude that, in addition to the slow luminescence corresponding to a transition from the triplet state, there are singlet-singlet transitions of the STE. Time-resolved spectra of the slow and fast decay exhibit a small shift (∼0.15 eV) indicating that the singlet-triplet splitting is small and the corresponding wavefunction of the STE is widely distributed over the atoms of the ScPO4 crystal where the STE is created.

  9. Aspects on the analysis of 210Po.

    PubMed

    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

  10. (210)Po secretion from sweat glands.

    PubMed

    Romańczyk, Grzegorz; Boryło, Alicja

    2017-02-01

    The results of the research indicated that the (210)Po activity concentration in sweat samples was between 0.22 ± 0.03 to 2.10 ± 0.15 mBq·g(-1) d.w. The obtained results of the studies showed that smoking and eating fish led to higher activity concentrations of (210)Po in sweat in comparison to the control group. Statistical analysis of (210)Po activity concentrations in sweat samples showed significant differences between control, smoking, fish eating and age groups, while no significant differences was found for (210)Po between volunteers as far as gender is concerned. Copyright © 2016. Published by Elsevier Ltd.

  11. Investigation of water assisted phase transformation process from AlPO4-5 to AlPO4-tridymite

    SciTech Connect

    Xu, Suochang; Zhao, Zhenchao; Hu, Mary Y.; Han, Xiuwen; Hu, Jian Zhi; Bao, Xinhe

    2016-03-01

    Water assisted phase transformation process from crystalized AlPO4-5 to AlPO4-tridymite was studied by the combination of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and in situ multinuclear MAS NMR. It is found that water first activates the residue amorphous aluminophosphate in crystalized AlPO4-5 sample through hydrolysis and condensation reactions. Then the activated aluminophosphate species reassemble into AlPO4-tridymite crystalline. Meanwhile, AlPO4-5 transforms into orthorhombic phase during heating process. With further crystallization of AlPO4-tridymite, the amorphous phase is gradually consumed, and mass transportation between AlPO4-5 and AlPO4-tridymite is established through gradually amorphization of AlPO4-5. Finally, most of the AlPO4-5 transforms into the thermodynamically stable dense phase AlPO4-tridymite.

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

    PubMed

    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.

  13. LiDy(PO3)4

    PubMed Central

    Chehimi-Moumen, Fathia; Férid, Mokhtar

    2008-01-01

    Single crystals of lithium dysprosium polyphosphate, LiDy(PO3)4, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains extending along the b axis. Dy3+ and Li+ cations alternate in the middle of four such chains, with Dy⋯Li distances of 3.54 (1) and 3.48 (1) Å. The DyO8 dodeca­hedra and LiO4 tetra­hedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2). PMID:21202729

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

    NASA Astrophysics Data System (ADS)

    Mohaghegh, N.; Rahimi, E.

    2016-06-01

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

  15. The atmospheric chemistry of Po-218

    SciTech Connect

    Hopke, P.K.

    1990-09-30

    The chemical and physical properties of {sup 218}Po immediately following its formation from {sup 222}Rn decay are important in determining its behavior in indoor atmospheres and plays a major part in determining its potential health effects. In 88% of the decays, a singly charged positive ion of {sup 218}Po is obtained at the end of its recoil path. The neutralization rates for Po-218 by the small ion recombination, electron transfer or electron scavenging mechanisms were previously reported. We have measured the small ion recombination rate in high purity gases to determine the negative small ion production rate as a function of the ionization potential of the gas. Our previous studies have also shown that radiolysis of water vapor by the recoiling Po ion produces high local concentrations of hydroxyl ({center dot}OH) radicals. These radicals can lead to oxidation of reactive trace gases and the neutral polonium molecule can become incorporated in ultrafine particles formed by the nucleation of low vapor pressure compounds produced by this radical oxidation process. The hydroxyl radical production rate and the production of particles are currently being studied. 12 refs., 1 fig.

  16. Shape coexistence in neutron deficient Po nuclei

    SciTech Connect

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

    1999-11-16

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

  17. Shape Coexistence in Neutron Deficient Po Nuclei

    SciTech Connect

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

    1999-12-31

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

  18. Recombination luminescence of LaPO4-Eu and LaPO4-Pr nanoparticles

    NASA Astrophysics Data System (ADS)

    Malyy, T. S.; Vistovskyy, V. V.; Khapko, Z. A.; Pushak, A. S.; Mitina, N. E.; Zaichenko, A. S.; Gektin, A. V.; Voloshinovskii, A. S.

    2013-06-01

    The study of the spectral-luminescence parameters of LaPO4-Eu and LaPO4-Pr nanoparticles upon excitation by the synchrotron radiation with photon energies 4-40 eV was performed. The differences of the luminescence intensity dependence on the size for LaPO4-Eu and LaPO4-Pr nanoparticles excited at the range of matrix transparency, the range of band-to-band transitions, and the range of electronic excitation multiplication were revealed. The observed regularities are explained in terms of the electron-phonon and electron-electron scattering, surface losses, and exciton diffusion. The ratio between the length of thermalization and electron mean free path and the size of nanoparticle is determinative for the luminescence intensity upon excitation in the range of fundamental absorption of matrix and X-ray excitation.

  19. 210Po microsphere radiological design for tumor vascular disruption

    PubMed Central

    2015-01-01

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

  20. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

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

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  2. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

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

  3. 49 CFR 604.36 - Powers of a PO.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  4. Half-life of /sup 218/Po

    SciTech Connect

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

    1986-10-01

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

  5. LiHo(PO3)4

    PubMed Central

    Ben Zarkouna, Emna; Driss, Ahmed; Férid, Mokhtar

    2009-01-01

    Lithium holmium(III) polyphosphate(V), LiHo(PO3)4, belongs to the type I of polyphosphates with general formula ALn(PO3)4, 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. PMID:21581738

  6. The BiPo-3 detector.

    PubMed

    Loaiza, P; Barabash, A S; Basharina-Freshville, A; Birdsall, E; Blondel, S; Blot, S; Bongrand, M; Boursette, D; Brudanin, V; Busto, J; Caffrey, A J; Calvez, S; Cascella, M; Cerna, C; Chauveau, E; Chopra, A; Capua, S De; Duchesneau, D; Durand, D; Egorov, V; Eurin, G; Evans, J J; Fajt, L; Filosofov, D; Flack, R; Garrido, X; Gómez, H; Guillon, B; Guzowski, P; Holý, K; Hodák, R; Huber, A; Hugon, C; Jeremie, A; Jullian, S; Kauer, M; Klimenko, A; Kochetov, O; Konovalov, S I; Kovalenko, V; Lang, K; Lemière, Y; Noblet, T Le; Liptak, Z; Liu, X R; Lutter, G; Macko, M; Mamedov, F; Marquet, C; Mauger, F; Morgan, B; Mott, J; Nemchenok, I; Nomachi, M; Nova, F; Ohsumi, H; Oliviéro, G; Pahlka, R B; Pater, J; Perrot, F; Piquemal, F; Povinec, P; Přidal, P; Ramachers, Y A; Remoto, A; Richards, B; Riddle, C L; Rukhadze, E; Saakyan, R; Sarazin, X; Shitov, Yu; Simard, L; Šimkovic, F; Smetana, A; Smolek, K; Smolnikov, A; Söldner-Rembold, S; Soulé, B; Štekl, I; Thomas, J; Timkin, V; Torre, S; Tretyak, Vl I; Tretyak, V I; Umatov, V I; Vilela, C; Vorobel, V; Waters, D; Žukauskas, A

    2017-05-01

    The BiPo-3 detector is a low radioactive detector dedicated to measuring ultra-low natural contaminations of (208)Tl and (214)Bi in thin materials, initially developed to measure the radiopurity of the double β decay source foils of the SuperNEMO experiment at the μBq/kg level. The BiPo-3 technique consists in installing the foil of interest between two thin ultra-radiopure scintillators coupled to low radioactive photomultipliers. The design and performances of the detector are presented. In this paper, the final results of the (208)Tl and (214)Bi activity measurements of the first enriched (82)Se foils are reported for the first time, showing the capability of the detector to reach sensitivities in the range of some μBq/kg. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. PoET: Polarimeters for Energetic Transients

    NASA Technical Reports Server (NTRS)

    McConnell, Mark; Barthelmy, Scott; Hill, Joanne

    2008-01-01

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

  8. Population and Decay of Superdeformed ^198Po

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Cizewski, J. A.; Smith, M. B.; Thomas, J. S.; Becker, J. A.; Bernstein, L. A.; McNabb, D. P.; Schiller, A.; Fallon, P.; Macchiavelli, A. O.; Ward, D.

    2002-10-01

    The population and decay of superdeformed (SD) nuclei remains an area of current interest. Little is known about the entry distribution associated with the population of SD excitations, especially in more fissile systems where fission dominates at high angular momentum. The study of the quasicontinuous (QC) spectrum associated with SD excitations provides a probe of the feeding and decay of the SD band as well as information on the excitation energy and spin of SD states. To study the population and decay of SD states, the ^174Yb(^29Si,5n) reaction was used to populate excitations in ^198Po, the most fissile nucleus for which an SD band has been identified at high spin (D.P. McNabb et al.), Phys. Rev. C 53 R541 (1996). The measurements were performed at the 88-Inch Cyclotron facility at LBNL using the Gammasphere array with 101 Compton-suppressed Ge detectors. The present results for the entry distribution and QC spectrum for the SD band in ^198Po will be contrasted to the spectra associated with the ND excitations in ^198Po, as well as the results for ^195Pb and ^192,194Pb footnote D.P. McNabb et al., Phys. Rev. C 61, 031304(R) (2000) for which similar analyses have been reported.

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

    SciTech Connect

    Chen, Guoying; Richardson, Thomas J.

    2009-04-07

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

  10. Synthesis and luminescence of CePO4:Tb/LaPO4 core/sheath nanowires

    SciTech Connect

    Li, Yuebin; Sun, Zhong; Ma, Lun; Zhang, Xing; Yao, Mingzhen; Joly, Alan G.; Liu, Zuli; Chen, Wei

    2010-03-26

    CePO4:Tb/LaPO4 core/sheath architectured nanowires have been successful synthesized by a facile aqueous chemical method mediated by original CePO4:Tb aggregation seeds. The seed crystals serve as both a luminescence center and nucleation site for epitaxial growth. The seed nanocrystals have irregular sphere-like shape with an average size of around 6.8 nm and a narrow size distribution. When the seed crystals are coated with LaPO4, the resulting CePO4:Tb/LaPO4 core/sheath architectured nanowires have mean diameters of about 7.6 nm and lengths up to 331 nm. Both the photo- and X-ray luminescence demonstrate that the LaPO4 coating increases the luminescence efficiency. These core-sheath structured nanowires may find potential applications in solid state lighting, medical imaging and radiation detection.

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

    SciTech Connect

    Andel, B.

    2015-10-15

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

  12. Nanocomposite Electrodes for Advanced Lithium Batteries: The LiFePO4 Cathode

    DTIC Science & Technology

    2001-11-01

    C at C /I current density. We demonstrated the possibility of synthesizing LiFePO4 ...material C . Table 1. Rietveld refinements for LiFePO4 materials A, B, C and FePO 4. LiFePO 4 (A) LiFePO4 (B) LiFePO4 ( C ) FePO4 a (A) 10.381 10.351 10.333...arrows show the FePO4 phase in material A. Material C was converted to FePO4 easily and no LiFePO4 was observed in the XRD, but for material A,

  13. KPr(PO3)4

    PubMed Central

    Oudahmane, Abdelghani; Daoud, Mohamed; Tanouti, Boumediene; Avignant, Daniel; Zambon, Daniel

    2010-01-01

    Single crystals of the title compound, potassium praseodymium(III) polyphosphate, were obtained by solid-state reaction. The monoclinic non-centrosymmetric structure is isotypic with all other KLn(PO3)4 analogues from Ln = La to Er, inclusive. The crystal structure of these long-chain polyphosphates is built up from infinite crenelated polyphosphate chains of corner-sharing PO4 tetra­hedra with a repeating unit of four tetra­hedra. These chains, running along [100], are arranged in a pseudo-tetra­gonal rod packing and are further linked by isolated PrO8 square anti­prisms [Pr—O = 2.3787 (9)–2.5091 (8) Å], forming a three-dimensional framework. The K+ ions reside in channels parallel to [010] and exhibit a highly distorted coordination sphere by eight O atoms at distances ranging from 2.7908 (9) to 3.1924 (11) Å. PMID:21588081

  14. A new polymorph of Lu(PO(3))(3).

    PubMed

    Bejaoui, Anis; Horchani-Naifer, Karima; Férid, Mokhtar

    2008-07-19

    A new polymorph of lutetium polyphosphate, Lu(PO(3))(3), was found to be isotypic with the trigonal form of Yb(PO(3))(3). Two of the three Lu atoms occupy special positions (Wyckoff positions 3a and 3b, site symmetry ). The atomic arrangement consists of infinite helical polyphosphate chains running along the c axis, with a repeat period of 12 PO(4) tetra-hedra, joined with LuO(6) octa-hedra.

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

    SciTech Connect

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

    2009-07-15

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

  16. Effect of Ag+ and PO43- ratios on the microstructure and photocatalytic activity of Ag3PO4

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  17. Ultraviolet luninescence of ScPO4, AlPO4, and GaPO4 crystals

    SciTech Connect

    Trukhin, Anatoly N.; Shmits, Krishjanis; Jansons, Janis L.; Boatner, Lynn A.

    2013-08-29

    The luminescence of self-trapped excitons (STE) was previously observed and described for the case of tetragonal-symmetry ScPO4 single crystals in 1996 by Trukhin and Boatner. The subject band in this material is situated in the UV spectral range of ~210 nm or ~5.8 eV. In the present work, we are both expanding this earlier luminescence study and seeking to identify similar luminescence phenomena in other orthophosphate crystals i.e., AlPO4 and GaPO4. These efforts have proven to be successful - in spite of the structural differences between these materials and ScPO4. Specifically we have found that for AlPO4 and GaPO4, in addition to an -quartz-like STE, there is a UV luminescence that is similar in position and decay properties to that of ScPO4 crystals. Potentially this represents an STE in AlPO4, and GaPO4 crystals that is analogous to the STE of ScPO4 and other orthophosphates. The decay kinetics of the UV luminescence of ScPO4 were studied over a wide temperature range from 8 to 300 K, and they exhibited some unusual decay characteristics when subjected to pulses from an F2 excimer laser (157 nm). These features could be ascribed to a triplet state of the STE that is split in a zero magnetic field. A fast decay of the STE was detected as well, and therefore, we conclude that, in addition to the slow luminescence corresponding to a transition from the triplet state, there are singlet-singlet transitions of the STE. Furthermore, time-resolved spectra of the slow and fast decay exhibit a small shift (~0.15 eV) indicating that the singlet triplet splitting is small and the corresponding wave function of the STE is widely distributed over the atoms of the ScPO4 crystal where the STE is created.

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

    SciTech Connect

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

    1995-08-01

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

  19. The onset of collectivity in sup 196 Po

    SciTech Connect

    Bernstein, L.A.; Cizewski, J.A.; Jin, H.Q.; Henry, R.G.; Farris, L.P. ); Khoo, T.L.; Carpenter, M.P.; Janssens, R.V.F.; Lauritsen, T. ); Bearden, I.G. Purdue Univ., Lafayette, IN ); Ye, D. )

    1992-01-01

    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.

  20. The onset of collectivity in {sup 196}Po

    SciTech Connect

    Bernstein, L.A.; Cizewski, J.A.; Jin, H.Q.; Henry, R.G.; Farris, L.P.; Khoo, T.L.; Carpenter, M.P.; Janssens, R.V.F.; Lauritsen, T.; Bearden, I.G. |; Ye, D.

    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.

  1. Anisotropic lithium ion migration in LiFePO4

    NASA Astrophysics Data System (ADS)

    Park, S. B.; Park, C. K.; Hwang, J. T.; Cho, W. I.; Jang, H.

    2011-12-01

    An anisotropic behavior of lithium ion migration in LiFePO4 is investigated using the cathode particles after chemical delithiation. A phase contrast of a LiFePO4 particle validating the directional property is also found. It suggests that the lithium ion migration path is limited to the [010] direction and the phase boundary between LiFePO4 and FePO4 is perpendicular [010]. The symmetric phase boundary inside the LiFePO4 particle is contrary to the non-directional core-shell model reported by others. The molecular dynamics simulation confirms the crystallographic direction with the lowest energy for lithium ion migration.

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

    PubMed Central

    Kruse, K; Kracht, U; Göpfert, G

    1982-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

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

    DTIC Science & Technology

    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...not return it to the originator. ARL-TR-7573 ● JAN 2016 US Army Research Laboratory Prediction of Wind Energy Resources (PoWER...2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) 09/2015–11/2015 4. TITLE AND SUBTITLE Prediction of Wind Energy Resources (PoWER) User’s

  6. A new polymorph of Lu(PO3)3

    PubMed Central

    Bejaoui, Anis; Horchani-Naifer, Karima; Férid, Mokhtar

    2008-01-01

    A new polymorph of lutetium polyphosphate, Lu(PO3)3, was found to be isotypic with the trigonal form of Yb(PO3)3. Two of the three Lu atoms occupy special positions (Wyckoff positions 3a and 3b, site symmetry ). The atomic arrangement consists of infinite helical polyphosphate chains running along the c axis, with a repeat period of 12 PO4 tetra­hedra, joined with LuO6 octa­hedra. PMID:21202991

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    PubMed

    Clayden, Nigel J; Cottrell, Stephen P

    2006-07-14

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

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

    PubMed

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

    2003-04-01

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

  10. A monoclinic polymorph of KY(PO(3))(4).

    PubMed

    Horchani-Naifer, Karima; Jouini, Anis; Férid, Mokhtar

    2008-05-17

    The title compound, potassium yttrium polyphosphate, KY(PO(3))(4), was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Chains, with a period of four PO(4) tetra-hedra, run along the a-axis direction. Two other polymorphs of this phosphate are known, in space groups P21/n and C2/c.

  11. A monoclinic polymorph of KY(PO3)4

    PubMed Central

    Horchani-Naifer, Karima; Jouini, Anis; Férid, Mokhtar

    2008-01-01

    The title compound, potassium yttrium polyphosphate, KY(PO3)4, was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Chains, with a period of four PO4 tetra­hedra, run along the a-axis direction. Two other polymorphs of this phosphate are known, in space groups P21/n and C2/c. PMID:21202436

  12. Assessment of ²¹⁰Po in Italian diet.

    PubMed

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

    2014-07-15

    This research was dedicated to the study, in the Italian daily diet, of the background activity concentration of (210)Po, a radionuclide with a high radiotoxicity. (210)Po was determined by alpha spectrometry. For food products of vegetable origin, the (210)Po activity concentration follows the trend: leafy vegetable>flour>rice>fruits>pasta>other vegetables>fruit vegetable; for those of animal origin: eggs>cheese>milk. The (210)Po activity concentration was also compared with that found by the same authors in meat, sea food, water and beverages in a previous study. The committed effective doses to individuals of three population groups (infants, children and adults) were 379, 222 and 151 μSv y(-1), respectively. The intake of foods of marine origin contributed about 67% of the total dose due to (210)Po ingestion. The effective dose, from (210)Po ingested by total diet, accounts for only 5-12% of the natural radiation exposure in Italy. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    PubMed Central

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

    2012-01-01

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

  14. Synthesis, Structure, and Magnetism of BaVO(PO 4)(H 2PO 4) · H 2O, a New Layered Barium Vanadium(IV) Phosphate Hydrate

    NASA Astrophysics Data System (ADS)

    Harrison, William T. A.; Lim, Shiao C.; Dussack, Laurie L.; Jacobson, Allan J.; Goshorn, David P.; Johnson, Jack W.

    1995-09-01

    The hydrothermal synthesis, X-ray single crystal structure, and some properties of BaVO(PO4)(H2PO4) · H2O are described. BaVO(PO4)(H2PO4) · H2O is built up from VO6 and (H2)PO4 groups, linked via V-O-P bonds, into anionic VO(PO4)(H2PO4) layers. The 9-coordinate Ba2+ cations and water molecules provide the interlayer packing between the V/P/O/H sheets. Magnetic susceptibility measurements on BaVO(PO4)(H2PO4) · H2O show perfect Curie-Weiss paramagnetism down to 4 K. Powder X-ray, TGA, and IR data for BaVO(PO4)(H2PO4) · H2O are also presented. Crystal data: BaVO(PO4)(H2PO4) · H2O, M = 414.24, monoclinic, space group P21/n (No. 14), a = 10.848 (3) Å, b = 6.408(3) Å, c = 11.376(2) Å, β = 102.32(2)°, V = 773(2) Å3, Z = 4, R(F) = 2.24%, Rw(F) = 2.42% [141 parameters; 2103 reflections with I > 3 σ (I)].

  15. 49 CFR 604.34 - Chief Counsel decisions and appointment of a PO.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Chief Counsel decisions and appointment of a PO... Presiding Official (PO) § 604.34 Chief Counsel decisions and appointment of a PO. (a) After receiving a... decision based on the pleadings filed to date; (2) Appoint a PO to review the matter; or (3) Dismiss...

  16. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  17. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  18. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design vapor pressure (Po) of a cargo tank must be equal to or greater than the MARVS. (b) The Po of a...

  19. The December, 1931 absorption experiments by Irene and Fredrick Joliot-Curie using Po Be, PoB and PoLi sources to study penetrating radiation

    NASA Astrophysics Data System (ADS)

    Shafroth, Stephen

    2005-03-01

    The December, 1931 absorption experiments by Irene and Fredrick Joliot-Curie using Po Be, PoB and PoLi sources to study penetrating radiation S.M. Shafroth, Physics and Astronomy Department, University of North Carolina at Chapel Hill 27599-3255, mailto:shafroth@physics.unc.edushafroth@physics.unc.edu The experimental arrangement including the Hoffman electroscope radiation detector and samples of the raw data are shown.^1 The emitted neutrons were interpreted as very high energy penetrating gammas. The exponential decay of detected radiation with thicknesses of Pb from 1.5- 5 cm are shown. I. Curie concludes, based on current knowledge of absorption coefficients vs gamma energy, that the gamma energy from PoBe was 15-20 MeV. However cloud chamber experiments had shown that the ``penetrating radiation'' could eject protons from paraffin with energies of 4.5 and 2 MeV in the case of Be and B respectively. If the ejection mechanism were the Compton effect, the gamma energies had to be 50 and 35 MeV respectively. Finally they conclude that the discrepancy in gamma energies could be ``due to the uncertainties.'' 1. Comptes Rendus de l'Academie des Sciences, S'eance du 28 Decembre 1931

  20. Scatterometry Products Distributed by JPL PO.DAAC

    NASA Astrophysics Data System (ADS)

    Chen, R. L.; Lungu, T.; Benada, J. R.

    2001-12-01

    The Physical Oceanography Distributed Active Archive Center (PO.DAAC) at the Jet Propulsion Laboratory (JPL) archives and distributes physical oceanography data, including data from spacebased scatterometers. PO.DAAC's current archive contains more than six terabytes of scatterometry data, and PO.DAAC has distributed over 40 terabytes of that data to users worldwide. Those numbers increase steadily with the continuation of the QuikSCAT satellite, and that increase should effectively double with the pending launch of SeaWinds on ADEOS-II. The SeaWinds on QuikSCAT instrument provides the largest component of PO.DAAC's scatterometry data. Every day, the instrument makes 400,000 measurements and covers 90% of the ice-free oceans for wind data, with additional useful information over land and ice. PO.DAAC publicly distributes two QuikSCAT products: - Level 3 Daily, Gridded Ocean Wind Vectors (JPL SeaWinds Project) - Level 2B Ocean Wind Vectors in 25 Km Swath Grid (JPL SeaWinds Project) Scheduled to launch in February 2002, the SeaWinds on ADEOS-II instrument will provide a similar amount of data as QuikSCAT. PO.DAAC will again publicly distribute the level 2B and the level 3 products. Other scatterometry data currently available from PO.DAAC include: - BYU Daily Browse Images of QuikSCAT Sigma-0 Measurements (D. Long) - NSCAT Scatterometer ocean wind products - NSCAT Scatterometer Science Product, Levels 1.7, 2, 3 - NSCAT scatterometer global 25km sigma-0 and ocean winds (Dunbar) Samples of some of these datasets are presented.

  1. RAPID DETERMINATION OF {sup 210} PO IN WATER SAMPLES

    SciTech Connect

    Maxwell, S.

    2013-05-22

    A new rapid method for the determination of {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that can be used for emergency response or routine water analyses. If a radiological dispersive device (RDD) event or a radiological attack associated with drinking water supplies occurs, there will be an urgent need for rapid analyses of water samples, including drinking water, ground water and other water effluents. Current analytical methods for the assay of {sup 210}Po in water samples have typically involved spontaneous auto-deposition of {sup 210}Po onto silver or other metal disks followed by counting by alpha spectrometry. The auto-deposition times range from 90 minutes to 24 hours or more, at times with yields that may be less than desirable. If sample interferences are present, decreased yields and degraded alpha spectrums can occur due to unpredictable thickening in the deposited layer. Separation methods have focused on the use of Sr Resin, often in combination with 210Pb analysis. A new rapid method for {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that utilizes a rapid calcium phosphate co-precipitation method, separation using DGA Resin (N,N,N,N-tetraoctyldiglycolamide extractant-coated resin, Eichrom Technologies or Triskem-International), followed by rapid microprecipitation of {sup 210}Po using bismuth phosphate for counting by alpha spectrometry. This new method can be performed quickly with excellent removal of interferences, high chemical yields and very good alpha peak resolution, eliminating any potential problems with the alpha source preparation for emergency or routine samples. A rapid sequential separation method to separate {sup 210} Po and actinide isotopes was also developed. This new approach, rapid separation with DGA Resin plus microprecipitation for alpha source preparation, is a significant advance in radiochemistry for the rapid

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    PubMed

    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.

  4. PoSSUM: Polar Suborbital Science in the Upper Mesosphere

    NASA Astrophysics Data System (ADS)

    Reimuller, J. D.; Fritts, D. C.; Thomas, G. E.; Taylor, M. J.; Mitchell, S.; Lehmacher, G. A.; Watchorn, S. R.; Baumgarten, G.; Plane, J. M.

    2013-12-01

    Project PoSSUM (www.projectpossum.org) is a suborbital research project leveraging imaging and remote sensing techniques from Reusable Suborbital Launch Vehicles (rSLVs) to gather critical climate data through use of the PoSSUM Observatory and the PoSSUM Aeronomy Laboratory. An acronym for Polar Suborbital Science in the Upper Mesosphere, PoSSUM grew from the opportunity created by the Noctilucent Cloud Imagery and Tomography Experiment, selected by the NASA Flight Opportunities Program as Experiment 46-S in March 2012. This experiment will employ an rSLV (e.g. the XCOR Lynx Mark II) launched from a high-latitude spaceport (e.g. Eielson AFB, Alaska or Kiruna, Sweden) during a week-long deployment scheduled for July 2015 to address critical questions concerning noctilucent clouds (NLCs) through flights that transition the cloud layer where the clouds will be under direct illumination from the sun. The 2015 Project PoSSUM NLC campaign will use the unique capability of rSLVs to address key under-answered questions pertaining to NLCs. Specifically, PoSSUM will answer: 1) What are the small-scale dynamics of NLCs and what does this tell us about the energy and momentum deposition from the lower atmosphere? 2) What is the seasonal variability of NLCs, mesospheric dynamics, and temperatures? 3) Are structures observed in the OH layer coupled with NLC structures? 4) How do NLCs nucleate? and 5) What is the geometry of NLC particles and how do they stratify? Instrumentation will include video and still-frame visible cameras (PoSSUMCam), infrared cameras, a mesospheric temperatures experiment, a depolarization LiDAR, a mesospheric density and temperatures experiment (MCAT), a mesospheric winds experiment, and a meteoric smoke detector (MASS). The instrument suite used on PoSSUM will mature through subsequent campaigns to develop an integrated, modular laboratory (the ';PoSSUM Observatory') that will provide repeatable, low cost, in-situ NLC and aeronomy observations as well

  5. Behavior of Po-210 in molten Pb-17Li

    NASA Astrophysics Data System (ADS)

    Feuerstein, H.; Oschinski, J.; Horn, S.

    1992-09-01

    The behavior of Po-210 in molten Pb-17Li was investigated in evaporation experiments. It was found that polonium evaporates in form of an intermetallic compound PbPo. Because of the low vapor pressure of this polonide, evaporation rates are small. The activity coefficient for Po in Pb-17Li is given by ln γ = -4.77-(1329/T). Under conditions of a fusion reactor blanket with helium as cover gas, the evaporating fraction will be 10 6 times smaller than that estimated assuming ideal solution and vacuum. In agreement with observations at a Bi-inpile loop, only a very small fraction of the total polonium will be found in cover gas spaces.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Optimization of carbon coatings on LiFePO 4

    NASA Astrophysics Data System (ADS)

    Doeff, Marca M.; Wilcox, James D.; Kostecki, Robert; Lau, Grace

    The electrochemical performance of LiFePO 4 in lithium cells is strongly dependent on the structure (disordered/graphene or D/G ratio) of the in situ carbon produced during synthesis from carbon-containing precursors. Addition of pyromellitic acid (PA) prior to final calcination results in lower D/G ratios, yielding a higher-rate material. Further, improvements in electrochemical performance are realized when graphitization catalysts such as ferrocene are also added during LiFePO 4 preparation, although overall carbon content is still less than 2 wt.%.

  8. Optimization of Carbon Coatings on LiFePO4

    SciTech Connect

    Doeff, Marca M.; Wilcox, James D.; Kostecki, Robert; Lau, Grace

    2005-07-14

    The electrochemical performance of LiFePO{sub 4} in lithium cells is strongly dependent on the structure (disordered/graphene or D/G ratio) of the in situ carbon produced during synthesis from carbon-containing precursors. Addition of pyromellitic acid (PA) prior to final calcination results in lower D/G ratios, yielding a higher-rate material. Further, improvements in electrochemical performance are realized when graphitization catalysts such as ferrocene are also added during LiFePO{sub 4} preparation, although overall carbon content is still less than 2 wt.%.

  9. The Imagine the Universe! E/PO Program

    NASA Technical Reports Server (NTRS)

    Lochner, James C.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Since 1996, the Imagine the Universe! E/PO program has brought information and curriculum support materials to upper middle school, high school, and lower undergraduate students and their teachers on topics in the Structure and Evolution of the Universe (SEU) theme. The Imagine E/PO program consists of a web site, a series of posters and information/activity booklets, and a repertoire of educator workshops. We involve both scientists and educators in the development and testing of the materials. We describe here the various aspects of this program.

  10. A novel route for FePO4 olivine synthesis from sarcopside oxidation

    NASA Astrophysics Data System (ADS)

    Crouzet, Camille; Recham, Nadir; Brunet, Fabrice; Findling, Nathaniel; David, Rénald; Sougrati, Moulay-Tahar

    2016-12-01

    Heterosite FePO4 is synthesized for the first time by direct thermal oxidation of sarcopside Fe3(PO4)2. Both FePO4 and Fe3(PO4)2 have a pseudo olivine structure. Complete isostructural conversion of sarcopside into FePO4 is achieved at a temperature of 450 °C within 3 days according to the reaction Fe3(PO4)2 + ¾ O2 → 2 FePO4 + ½ Fe2O3 which leads to the extraction of iron from the sarcopside structure. Appropriate heating ramp must be applied in order to avoid the crystallization of Fe7(PO4)6. Electrochemical performances of the oxidation product are consistent with those of olivine FePO4.

  11. Novel method for the quantification of inorganic polyphosphate (iPoP) in Saccharomyces cerevisiae shows dependence of iPoP content on the growth phase.

    PubMed

    Werner, Thomas P; Amrhein, Nikolaus; Freimoser, Florian M

    2005-11-01

    Inorganic polyphosphate (iPoP)-linear chains of up to hundreds of phosphate residues-is ubiquitous in nature and appears to be involved in many different cellular processes. In Saccharomyces cerevisiae, iPoP has been detected in high concentrations, especially after transfer of phosphate-deprived cells to a high-phosphate medium. Here, the dynamics of iPoP synthesis in yeast as a function of the growth phase as well as glucose and phosphate availability have been investigated. To address this question, a simple, fast and novel method for the quantification of iPoP from yeast was developed. Both the iPoP content during growth and the iPoP "overplus" were highest towards the end of the exponential phase, when glucose became limiting. Accumulation of iPoP during growth required excess of free phosphate, while the iPoP "overplus" was only observed after the shift from low- to high-phosphate medium. The newly developed iPoP quantification method and the knowledge about the dynamics of iPoP content during growth made it possible to define specific growth conditions for the analysis of iPoP levels. These experimental procedures will be essential for the large-scale analysis of various mutant strains or the comparison of different growth conditions.

  12. Structural and Electrochemical Characterization of Pure LiFePO 4 and Nanocomposite C- LiFePO 4 Cathodes for Lithium Ion Rechargeable Batteries

    DOE PAGES

    Kumar, Arun; Thomas, R.; Karan, N. K.; ...

    2009-01-01

    Pure limore » thium iron phosphate ( LiFePO 4 ) and carbon-coated LiFePO 4 (C- LiFePO 4 ) cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on LiFePO 4 particles. Ex situ Raman spectrum of C- LiFePO 4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of LiFePO 4 and C- LiFePO 4 showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively for LiFePO 4 where as in case of C- LiFePO 4 that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO 4 was 69% after 25 cycles where as that of C- LiFePO 4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.« less

  13. Size-dependent magnetic ordering and spin-dynamics in DyPO4 and GdPO4 nanoparticles

    SciTech Connect

    Evangelisti, Marco; Sorop, Tibi G; Bakharev, Oleg N; Visser, Dirk; Hillier, Adrian D.; Alonso, Juan; Haase, Markus; Boatner, Lynn A; De Jongh, L. Jos

    2011-01-01

    Low-temperature magnetic susceptibility and heat capacity measurements on nanoparticles (d 2.6 nm) of the antiferromagnetic compounds DyPO4 (TN = 3:4 K) and GdPO4 (TN = 0:77 K) provide clear demonstrations of finite-size effects, which limit the divergence of the magnetic correlation lengths, thereby suppressing the bulk long-range magnetic ordering transitions. Instead, the incomplete antiferromagnetic order inside the particles leads to the formation of net magnetic moments on the particles. For the nanoparticles of Ising-type DyPO4 superparamagnetic blocking is found in the ac-susceptibility at 1 K, those of the XY-type GdPO4 analogue show a dipolar spin-glass transition at 0:2 K. Monte Carlo simulations for the magnetic heat capacities of both bulk and nanoparticle samples are in agreement with the experimental data. Strong size effects are also apparent in the Dy3+ and Gd3+ spin-dynamics, which were studied by zero-field SR relaxation and high-field 31P-NMR nuclear relaxation measurements. The freezing transitions observed in the ac-susceptibility of the nanoparticles also appear as peaks in the temperature dependence of the zero-field SR rates, but at slightly higher temperatures - as to be expected from the higher frequency of the muon probe. For both bulk and nanoparticles of GdPO4, the muon and 31P-NMR rates are for T 5 K dominated by exchange-narrowed hyperfine broadening arising from the electron spin-spin interactions inside the particles. The dipolar hyperfine interactions acting on the muons and the 31P are, however, much reduced in the nanoparticles. For the DyPO4 analogues the high-temperature rates appear to be fully determined by electron spin-lattice relaxation processes.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. Dominant-negative effect on adhesion by myelin Po protein truncated in its cytoplasmic domain

    PubMed Central

    1996-01-01

    The myelin Po protein is believed to hold myelin together via interactions of both its extracellular and cytoplasmic domains. We have already shown that the extracellular domains of Po can interact in a homophilic manner (Filbin, M.T., F.S. Walsh, B.D. Trapp, J.A. Pizzey, and G.I. Tennekoon. 1990. Nature (Lond.). 344:871-872). In addition, we have shown that for this homophilic adhesion to take place, the cytoplasmic domain of Po must be intact and most likely interacting with the cytoskeleton; Po proteins truncated in their cytoplasmic domains are not adhesive (Wong, M.H., and M.T. Filbin, 1994. J. Cell Biol. 126:1089-1097). To determine if the presence of these truncated forms of Po could have an effect on the functioning of the full-length Po, we coexpressed both molecules in CHO cells. The adhesiveness of CHO cells expressing both full-length Po and truncated Po was then compared to cells expressing only full-length Po. In these coexpressors, both the full-length and the truncated Po proteins were glycosylated. They reached the surface of the cell in approximately equal amounts as shown by an ELISA and surface labeling, followed by immunoprecipitation. Furthermore, the amount of full-length Po at the cell surface was equivalent to other cell lines expressing only full-length Po that we had already shown to be adhesive. Therefore, there should be sufficient levels of full-length Po at the surface of these coexpressors to measure adhesion of Po. However, as assessed by an aggregation assay, the coexpressors were not adhesive. By 60 min they had not formed large aggregates and were indistinguishable from the control transfected cells not expressing Po. In contrast, in the same time, the cells expressing only the full-length Po had formed large aggregates. This indicates that the truncated forms of Po have a dominant-negative effect on the adhesiveness of the full-length Po. Furthermore, from cross-linking studies, full-length Po, when expressed alone but not when

  16. Recoil-deposited Po-210 in radon dwellings

    SciTech Connect

    Samuelsson, C.

    1990-12-31

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

  17. America's Earliest Revolutionary Voice: Po-Pay--Not Patrick Henry.

    ERIC Educational Resources Information Center

    Owen, Gordon R.

    A full century before Patrick Henry's persuasive battle for the rights of oppressed people, a San Juan Pueblo Indian medicine man known only as Po-Pay was the masterful communicator and agitator who orchestrated the first American revolution to drive the Spanish back into Mexico. Seeking mineral wealth, cheap labor, and the maximum number of…

  18. [K(2)CsYb(PO(4))(2)].

    PubMed

    Rghioui, Lotfi; el-Ammari, Lahcen; Benarafa, Larbi; Wignacourt, Jean Pierre

    2002-07-01

    The crystal structure of dipotassium caesium ytterbium bis(phosphate) is built up from regular independent PO(4) tetrahedra and YbO(6) octahedra sharing corners and arranged in layers. The structure is, in many respects, similar to that of glaserite.

  19. Structure for Storing Properties of Particles (PoP)

    SciTech Connect

    Patel, N. R.; Mattoon, C. M.; Beck, B. R.; Summers, N. C.; Brown, D. A.

    2014-06-01

    Some evaluated nuclear databases are critical for applications such as nuclear energy, nuclear medicine, homeland security, and stockpile stewardship. Particle masses, nuclear excitation levels, and other “Properties of Particles” are essential for making evaluated nuclear databases. Currently, these properties are obtained from various databases that are stored in outdated formats. Moreover, the “Properties of Particles” (PoP) structure is being designed that will allow storing all information for one or more particles in a single place, so that each evaluation, simulation, model calculation, etc. can link to the same data. Information provided in PoP will include properties of nuclei, gammas and electrons (along with other particles such as pions, as evaluations extend to higher energies). Presently, PoP includes masses from the Atomic Mass Evaluation version 2003 (AME2003), and level schemes and gamma decays from the Reference Input Parameter Library (RIPL-3). The data are stored in a hierarchical structure. An example of how PoP stores nuclear masses and energy levels will be presented here.

  20. Structure for Storing Properties of Particles (PoP)

    SciTech Connect

    Patel, N.R.; Mattoon, C.M.; Beck, B.R.; Summers, N.C.; Brown, D.A.

    2014-06-15

    Evaluated nuclear databases are critical for applications such as nuclear energy, nuclear medicine, homeland security, and stockpile stewardship. Particle masses, nuclear excitation levels, and other “Properties of Particles” are essential for making evaluated nuclear databases. Currently, these properties are obtained from various databases that are stored in outdated formats. A “Properties of Particles” (PoP) structure is being designed that will allow storing all information for one or more particles in a single place, so that each evaluation, simulation, model calculation, etc. can link to the same data. Information provided in PoP will include properties of nuclei, gammas and electrons (along with other particles such as pions, as evaluations extend to higher energies). Presently, PoP includes masses from the Atomic Mass Evaluation version 2003 (AME2003), and level schemes and gamma decays from the Reference Input Parameter Library (RIPL-3). The data are stored in a hierarchical structure. An example of how PoP stores nuclear masses and energy levels will be presented here.

  1. Structure for Storing Properties of Particles (PoP)

    NASA Astrophysics Data System (ADS)

    Patel, N. R.; Mattoon, C. M.; Beck, B. R.; Summers, N. C.; Brown, D. A.

    2014-06-01

    Evaluated nuclear databases are critical for applications such as nuclear energy, nuclear medicine, homeland security, and stockpile stewardship. Particle masses, nuclear excitation levels, and other "Properties of Particles" are essential for making evaluated nuclear databases. Currently, these properties are obtained from various databases that are stored in outdated formats. A "Properties of Particles" (PoP) structure is being designed that will allow storing all information for one or more particles in a single place, so that each evaluation, simulation, model calculation, etc. can link to the same data. Information provided in PoP will include properties of nuclei, gammas and electrons (along with other particles such as pions, as evaluations extend to higher energies). Presently, PoP includes masses from the Atomic Mass Evaluation version 2003 (AME2003), and level schemes and gamma decays from the Reference Input Parameter Library (RIPL-3). The data are stored in a hierarchical structure. An example of how PoP stores nuclear masses and energy levels will be presented here.

  2. Measurement of airborne {sup 218}Po - A Bayesian approach

    SciTech Connect

    Groer, P.G.; Lo, Y.

    1996-12-01

    The standard mathematical treatment of the buildup and decay of airborne radionuclides on a filter paper uses the solutions of the so-called bateman equations adapted to the sampling process. The equations can be interpreted as differential equations for the expectation of an underlying stochastic process, which describes the random fluctuations in the accumulation and decay of the sampled radioactive atoms. The process for the buildup and decay of airborne {sup 218}Po can be characterized as an {open_quotes}immigration-death process{close_quotes} in the widely adopted, biologically based jargon. The probability distribution for the number of {sup 218}Po atoms, accumulated after sampling time t, is Poisson. We show that the distribution of the number of counts, registered by a detector with efficiency {epsilon} during a counting period T after the end of sampling, it also Poisson, with mean dependent on {epsilon},t,T, the flowrate and N{sub o}, the number of airborne {sup 218}Po atoms per unit volume. This Poisson distribution was used to construct the likelihood given the observed number of counts. After inversion with Bayes` Theorem we obtained the posterior density for N{sub o}. This density characterizes the remaining uncertainty about the measured under of {sup 218}Po atoms per unit volume of air. 6 refs., 3 figs., 1 tab.

  3. Bioaccumulation of polonium 210Po in marine birds.

    PubMed

    Skwarzec, B; Fabisiak, J

    2007-01-01

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

  4. PoGOLite measurement of Crab polarisation and future plans

    NASA Astrophysics Data System (ADS)

    Pearce, Mark

    2016-07-01

    (For the PoGOLite Collaboration) The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter designed for the observation of bright, ~1 Crab, sources. Polarisation is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an BGO anticoincidence well. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013 resulting in a near-circumpolar flight of two weeks duration. The linear polarisation of hard X-ray emissions from the Crab was measured in a previously unexplored energy interval, 20-120 keV. The polarimetric response was characterised prior to flight using both polarised and unpolarised calibration sources. Systematic effects were addressed through observations of a background field. An upgraded polarimeter, PoGO+, is scheduled to fly in summer 2016 from Esrange. Results from the 2013 Pathfinder flight and prospects for the 2016 flight will be discussed.

  5. Polonium 210Po in cigarettes produced in Poland.

    PubMed

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

    2001-01-01

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

  6. America's Earliest Revolutionary Voice: Po-Pay--Not Patrick Henry.

    ERIC Educational Resources Information Center

    Owen, Gordon R.

    A full century before Patrick Henry's persuasive battle for the rights of oppressed people, a San Juan Pueblo Indian medicine man known only as Po-Pay was the masterful communicator and agitator who orchestrated the first American revolution to drive the Spanish back into Mexico. Seeking mineral wealth, cheap labor, and the maximum number of…

  7. Pinunuuchi Po'og'ani: Southern Ute Indian Academy.

    ERIC Educational Resources Information Center

    Oberly, Stacey Inez (Wachimamachi [Antelope Woman])

    2002-01-01

    Describes the Pinunuuchi Po'og'ani, the Southern Ute Indian Academy, providing Montessori education for Southern Ute tribal members ages 6 weeks through 10 years and reviving the use of the Southern Ute language and culture among young students and their families. Describes how the program supports families, students, and staff, and incorporates…

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

    PubMed

    Takiyama, Ken; Shinya, Masahiro

    2016-01-01

    Most motor learning experiments have been conducted in a laboratory setting. In this type of setting, a huge and expensive manipulandum is frequently used, requiring a large budget and wide open space. Subjects also need to travel to the laboratory, which is a burden for them. This burden is particularly severe for patients with neurological disorders. Here, we describe the development of a novel application based on Unity3D and smart devices, e.g., smartphones or tablet devices, that can be used to conduct motor learning experiments at any time and in any place, without requiring a large budget and wide open space and without the burden of travel on subjects. We refer to our application as POrtable Motor learning LABoratory, or PoMLab. PoMLab is a multiplatform application that is available and sharable for free. We investigated whether PoMLab could be an alternative to the laboratory setting using a visuomotor rotation paradigm that causes sensory prediction error, enabling the investigation of how subjects minimize the error. In the first experiment, subjects could adapt to a constant visuomotor rotation that was abruptly applied at a specific trial. The learning curve for the first experiment could be modeled well using a state space model, a mathematical model that describes the motor leaning process. In the second experiment, subjects could adapt to a visuomotor rotation that gradually increased each trial. The subjects adapted to the gradually increasing visuomotor rotation without being aware of the visuomotor rotation. These experimental results have been reported for conventional experiments conducted in a laboratory setting, and our PoMLab application could reproduce these results. PoMLab can thus be considered an alternative to the laboratory setting. We also conducted follow-up experiments in university physical education classes. A state space model that was fit to the data obtained in the laboratory experiments could predict the learning curves

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

    PubMed Central

    Shinya, Masahiro

    2016-01-01

    Most motor learning experiments have been conducted in a laboratory setting. In this type of setting, a huge and expensive manipulandum is frequently used, requiring a large budget and wide open space. Subjects also need to travel to the laboratory, which is a burden for them. This burden is particularly severe for patients with neurological disorders. Here, we describe the development of a novel application based on Unity3D and smart devices, e.g., smartphones or tablet devices, that can be used to conduct motor learning experiments at any time and in any place, without requiring a large budget and wide open space and without the burden of travel on subjects. We refer to our application as POrtable Motor learning LABoratory, or PoMLab. PoMLab is a multiplatform application that is available and sharable for free. We investigated whether PoMLab could be an alternative to the laboratory setting using a visuomotor rotation paradigm that causes sensory prediction error, enabling the investigation of how subjects minimize the error. In the first experiment, subjects could adapt to a constant visuomotor rotation that was abruptly applied at a specific trial. The learning curve for the first experiment could be modeled well using a state space model, a mathematical model that describes the motor leaning process. In the second experiment, subjects could adapt to a visuomotor rotation that gradually increased each trial. The subjects adapted to the gradually increasing visuomotor rotation without being aware of the visuomotor rotation. These experimental results have been reported for conventional experiments conducted in a laboratory setting, and our PoMLab application could reproduce these results. PoMLab can thus be considered an alternative to the laboratory setting. We also conducted follow-up experiments in university physical education classes. A state space model that was fit to the data obtained in the laboratory experiments could predict the learning curves

  10. NASA's Planetary Science E/PO Forum: Reflections on Five Years of Effort to Support an E/PO Community

    NASA Astrophysics Data System (ADS)

    Shipp, S. S.; Shebby, S.; Buxner, S.; Boonstra, D.; Cobabe-Ammann, E. A.; Cobb, W. H.; Dalton, H.; Grier, J.; Klug Boonstra, S. L.; LaConte, K.; Ristvey, J.; Shupla, C. B.; Weeks, S.; Wessen, A. S.; Zimmerman-Brachman, R.

    2014-12-01

    Over the past decade, NASA's Science Mission Directorate (SMD) has funded four education and public outreach (E/PO) forums, aligned with each of its science divisions, including Astrophysics, Earth Science, Heliophysics, and Planetary Science. Together, these forums help organize individual division E/PO programs into a coordinated, effective, efficient, nationwide effort that shares the scientific discoveries of NASA across a broad array of audiences. In the past four-and-a-half years, the Planetary Science Division's Forum - in collaboration with the other three Forums - has worked to support its community of education professionals and scientists involved in E/PO to communicate, collaborate, and strengthen their efforts. The Forum's work encompasses identification of best practices based on educational research, increasing understanding of needs through audience-based working groups, the development of strategic collaborations and partnerships to increase programmatic reach, and the creation of strategic resources to support community members in their E/PO work (e.g., an online workspace for the community to communicate, collaborate, and share practices; recommendations to scientists for increasing impact in educational settings; a one-stop shop for NASA SMD classroom and informal education products, http://nasawavelength.org). Drawing on evaluation data, the presentation will explore what resources and support mechanisms are valued by the community, ways the community uses the available resources, and the outcomes of the effort to date.

  11. A synthesis of LiFePO{sub 4} starting from FePO{sub 4} under reducing atmosphere

    SciTech Connect

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

    2014-06-19

    A fast and easy way to produce LiFePO{sub 4} starting from FePO{sub 4}, used as iron and phosphorus source, is proposed. 5% hydrogen is employed as a reducing agent and various compounds containing lithium as lithiation agents. The selected lithiation agents included: LiCl, CH{sub 3}COOLi, LiOH, Li{sub 2}S, LiH, and Li{sub 2}CO{sub 3}. Solid state synthesis is used for the LiFePO{sub 4} preparation and the so obtained materials are structurally characterized by XRD. The materials are used to fabricate composite electrode and their specific capacity is evaluated by low rate galvanostatic charge/discharge cycles (C/10 rate). Among the various lithium salts, the acetate give rise to the LiFePO{sub 4} with the best electrochemical performance. The morphology of this material is further investigated by SEM microscopy and the specific capacity is evaluated as a function of the discharge rate and the cycle number.

  12. Influence of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses

    SciTech Connect

    El Moudane, M.; El Maniani, M.; Sabbar, A.; Ghanimi, A.; Tabyaoui, M.; Bellaouchou, A.; Guenbour, A.

    2015-12-15

    Highlights: • Results of ionic conductivities of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. • Determination of glass transition temperature using DSC method. • Study of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. - Abstract: Lithium–Lead–Bismuth phosphates glasses having, a composition 30Li{sub 3}PO{sub 4}–(70 − x)Pb{sub 3}(PO{sub 4}){sub 2}–xBiPO{sub 4} (45 ≤ x ≤ 60 mol%) were prepared by using the melt quenching method 1000 °C. The thermal stability of theses glasses increases with the substitution of Bi{sub 2}O{sub 3} with PbO. The ionic conductivity of all compositions have been measured over a wide temperature (200–500 °C) and frequency range (1–106 Hz). The ionic conductivity data below and above T{sub g} follows Arrhenius and Vogel–Tamman–Fulcher (VTF) relationship, respectively. The activation energies are estimated and discussed. The dependence in frequency of AC conductivity is found to obey Jonscher’s relation.

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

    PubMed

    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.

  14. Cd2Cu(PO4)2.

    PubMed

    Stojanović, Jovica; Dordvić, Tamara; Karanović, Ljiljana

    2008-11-01

    During an investigation of the insufficiently known system M1O-M2O-X(2)O(5)-H(2)O (M1 = Cd(2+), Sr(2+) and Ba(2+); M2 = Cu(2+), Ni(2+), Co(2+), Zn(2+) and Mg(2+); X = P(5+), As(5+) and V(5+)), single crystals of the novel compound dicadmium copper(II) bis[phosphate(V)], Cd(2)Cu(PO(4))(2), were obtained. This compound belongs to a small group of compounds adopting a Cu(3)(PO(4))(2)-type structure and having the general formula M1(2)M2(XO(4))(2) (M1/M2 = Cd(2+), Cu(2+), Mg(2+) and Zn(2+); X = As(5+), P(5+) and V(5+)). The crystal structure is characterized by the interconnection of infinite [Cu(PO(4))(2)](n) chains and [Cd(2)O(10)](n) double chains, both extending along the a axis. Exceptional characteristics of this structure are its novel chemical composition and the occurrence of double chains of CdO(6) polyhedra that were not found in related structures. In contrast to the isomorphous compounds, where the M1 cations are coordinated by five O atoms, the Cd atom is coordinated by six. The dissimilarity in the geometry of M1 coordination between Cd(2)Cu(PO(4))(2) and the isomorphous compounds is mostly due to the larger ionic radius of the Cd cation in comparison with the Cu, Mg and Zn cations. Sharing a common edge, two CdO(6) polyhedra form Cd(2)O(10) dimers. Each such dimer is bonded to another dimer sharing common vertices, forming [Cd(2)O(10)](n) double chains in the [100] direction. The Cu atoms, located on an inversion centre (site symmetry \\overline{1}), form isolated CuO(4) squares interconnected by PO(4) tetrahedra, forming [Cu(PO(4))(2)](n) chains similar to those found in related structures. Conversely, the [Cd(2)O(10)](n) double chains, which were not found in related structures, are an exclusive feature of this structure.

  15. Pressure-induced zircon-type to scheelite-type phase transitions in YbPO{sub 4} and LuPO{sub 4}

    SciTech Connect

    Zhang, F.X. Lang, M.; Ewing, R.C. Lian, J.; Wang, Z.W.; Hu, J.; Boatner, L.A.

    2008-10-15

    The tetragonal orthophosphates, YbPO{sub 4} and LuPO{sub 4}, were studied by in situ X-ray diffraction (XRD) at pressures up to 52 and 43 GPa, respectively. A reversible phase transition from the zircon structure-type to the scheelite structure-type was found at {approx}22 GPa for YbPO{sub 4} and 19 GPa for LuPO{sub 4}. Coinciding with the transition from the zircon structure-type to the scheelite structure-type, there is a {approx}10% reduction in volume and a significant increase in the bulk modulus for both compounds. - Graphical abstract: The tetragonal orthophosphates, YbPO{sub 4} and LuPO{sub 4}, show reversible phase transitions from the zircon structure-type to the scheelite structure-type at {approx}22 and 19 Gpa, respectively. Coinciding with the phase transition, there is a {approx}10% reduction in unit cell volume.

  16. High pressure structural phase transitions of PbPo

    NASA Astrophysics Data System (ADS)

    Bencherif, Y.; Boukra, A.; Zaoui, A.; Ferhat, M.

    2012-09-01

    First-principles calculations have been performed to investigate the high pressure phase transitions and dynamical properties of the less known lead polonium compound. The calculated ground state parameters for the NaCl phase show good agreement with the experimental data. The obtained results show that the intermediate phase transition for this compound is the orthorhombic Pnma phase. The PbPo undergoes from the rocksalt to Pnma phase at 4.20 GPa. Further structural phase transition from intermediate to CsCl phase has been found at 8.5 GPa. In addition, phonon dispersion spectra were derived from linear-response to density functional theory. In particular, we show that the dynamical properties of PbPo exhibit some peculiar features compared to other III-V compounds. Finally, thermodynamics properties have been also addressed from quasiharmonic approximation.

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

    PubMed

    Khan, M Feroz; Wesley, S Godwin

    2016-06-15

    Several species of tuna fish were analyzed for (210)Po content in their edible muscle tissues. This study was carried out as a part of baseline data generation around a large nuclear power plant situated at Kudankulam, southeast coast of India. The concentration of (210)Po in the muscle tissue ranged from 40.9±5.2 to 92.5±7.9Bq/kg of fresh fish, and the highest activity was recorded for the tuna Euthynnus affinis and the lowest for Auxis thazard. The committed effective dose to the local residents was calculated to be 62.7-141.8μSvyear(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. The BiPo detector for ultralow radioactivity measurements

    SciTech Connect

    Bongrand, M.

    2007-03-28

    The BiPo project is dedicated to the measurement of extremely low radioactivity contamination of SuperNEMO source foils (208Tl < 2 {mu}Bq/kg and 214Bi < 10 {mu}Bq/kg). The R and D phase is started : a modular BiPo prototype with its shielding test facility is under construction. The goal of this prototype is to study the background and particularly the surface contamination of scintillators. The first capsule has been installed in the Canfranc Underground Laboratory in October, 17th and is now taking data. After 10.7 days of measurements, a preliminary upper limit on the surface radiopurity of the scintillators of A(208Tl) < 60 {mu}Bq/m2 (90% C. L.) has been obtained.

  19. Pressure-Induced Zircon-Type to Scheelite-Type Phase Transition in Orthophosphates YbPO4 and LuPO4

    SciTech Connect

    Zhang, F.; Maik, L; Ewing, R; Lian, J; Wang, Z; Hu, J; Boatner, L

    2008-01-01

    The tetragonal orthophosphates, YbPO4 and LuPO4, were studied by in situ X-ray diffraction (XRD) at pressures up to 52 and 43 GPa, respectively. A reversible phase transition from the zircon structure-type to the scheelite structure-type was found at not, vert, similar22 GPa for YbPO4 and 19 GPa for LuPO4. Coinciding with the transition from the zircon structure-type to the scheelite structure-type, there is a not, vert, similar 10% reduction in volume and a significant increase in the bulk modulus for both compounds.

  20. HST Cycle 11 E/PO Grant Program

    NASA Astrophysics Data System (ADS)

    Eisenhamer, B.; Bradbury, Heather

    2001-12-01

    Space Science Enterprise education and public outreach goals center on sharing the results of our missions and research programs with wide audiences and using space science discoveries as vehicles to improve teaching and learning at all levels. - the space science enterprise strategic plan In support of the OSS education and public outreach mission, STScI is announcing the opportunity for current Hubble Fellows and accepted HST Cycle 11 GO/AR/SNAP researchers to submit proposals for an E/PO extension to their "parent" research proposal. The spirit of the HST Cycle 11 E/PO Grant Program is to encourage collaborative efforts between professional astronomers/space scientists and professional educators that would broaden the knowledge and understanding of the latest discoveries of the Hubble Space Telescope. The proposed E/PO program should have some degree of intellectual linkage to the objectives of the "parent" research proposal and/or the science expertise of its Principal Investigator (PI). The goal is to provide K-12 and community college education institutions, pre-service and in-service educators, and museums, science centers and planetariums with current astronomy/space science content. Up to \\10,000 per year may be proposed for an E/PO program, with a possible teamed effort of \\50,000. The Call for Proposals will be released the first week of February. The deadline for submitting a proposal is Friday, 22 March 2002 at 5:00 p.m. EST. This poster will provide potential proposers an opportunity to find out more about the grant program.

  1. Frequency budget for the PoP cavity

    SciTech Connect

    Ratti, Alessandro

    1995-07-01

    The computer code superfish has been used in conjunction with measurements, to obtain a frequency budget for the PoP cavity. The goal of the exercise is to have a valid prediction of the natural resonant frequency of the final accelerating cavity to be built for RHIC. An estimation of the frequency shift due to the power coupling window is also included and compared with measurements.

  2. Evidence of 210Po on Martian dust at Meridiani Planum

    NASA Astrophysics Data System (ADS)

    Meslin, Pierre-Yves; Sabroux, Jean-Christophe; Berger, Lionel; Pineau, Jean-François; Chassefière, Eric

    2006-09-01

    Since the Surveyor and Apollo missions and up to the recent Lunar Prospector mission, 222Rn and 210Po have been key isotopes for understanding gas release events and their spatial and temporal variations on the Moon. Comparatively, these isotopes have drawn much less attention on Mars, if any, despite the wealth of information it could bring on the uppermost meters of the regolith, the exchange of volatiles at the surface, and the atmospheric aerosol cycle. Here we present a statistical analysis of the high-energy end of alpha spectra obtained by the alpha particle X-ray spectrometer onboard Mars Exploration Rover Opportunity and report evidence of 210Po, a decay product of 222Rn, attached to atmospheric dust. The 210Po surface activity on rocks and soils at the landing site is lower than 3.1 × 10-4 Bq cm-2, but analysis of spectra obtained on the dust capture magnet reveals a 210Po activity of (4.6 +/- 2.4) × 10-3 Bq cm-2 (+/-2σ). This difference is due to the very low dust cover index at the landing site. Owing to frequent dust devils, regional and global dust storms that mobilize substantial amounts of dust and homogenize the dust surface layer, we infer that the global average 222Rn exhalation rate is significantly greater on Mars than on the Moon. This comparison supports the hypothesis that on Mars, radon emanation could be comparatively enhanced by the presence of water in the surficial soil. Analysis of atmospheric spectra yields a radon activity upper limit of 16 +/- 5 Bq m-3 during nighttime at the landing site.

  3. Graphs for Isotopes of 84-Po(Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides a graphic representation of nucleon separation energies and residual interaction parameters for isotopes of the chemical element 84-Po (Polonium, atomic number Z = 84).

  4. Stoichiometry, spin fluctuations, and superconductivity in LaNiPO

    SciTech Connect

    McQueen, Tyrel M.; Klimczuk, Tomasz; Williams, Anthony J.; Huang, Qiang; Cava, Robert J.

    2009-05-18

    Superconductivity in LaNiPO is disrupted by small ({approx}5%) amounts of non-stoichiometry on the lanthanum site, even though the electronic contribution to the heat capacity increases with increasing non-stoichiometry. All samples also exhibit specific heat anomalies consistent with the presence of ferromagnetic spin fluctuations (T{sub sf}{approx} 14K). Comparison of layered nickel phosphide and nickel borocarbide superconductors reveals different structure-property correlations in the two families.

  5. Lattice dynamics of LuPO{sub 4}

    SciTech Connect

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

    1996-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  7. Origin of the charge gap in LaMnPO

    DOE PAGES

    McNally, D. E.; Simonson, Jack W.; Post, K. W.; ...

    2014-11-18

    In this paper, we present high temperature inelastic neutron scattering and magnetic susceptibility measurements of the antiferromagnetic insulator LaMnPO that are consistent with the presence of two-dimensional magnetic correlations up to a temperature Tmax≈700K»TN=375 K, the Néel temperature. Optical transmission measurements show the T=300 K direct charge gap Δ=1 eV has decreased only marginally by 500 K and suggest it decreases by only 10% at Tmax. Density functional theory and dynamical mean-field theory calculations reproduce a direct charge gap in paramagnetic LaMnPO only when a strong Hund's coupling JH=0.9 eV is included, as well as on-site Hubbard U=8 eV. Inmore » conclusion, our results show that LaMnPO is a Mott-Hund's insulator, in which the charge gap is rather insensitive to antiferromagnetic exchange coupling.« less

  8. Magnetic and Diffusive Nature of LiFePO4

    NASA Astrophysics Data System (ADS)

    Sugiyama, Jun; Nozaki, Hiroshi; Kamazawa, Kazuya; Ofer, Oren; Månsson, Martin; Ansaldo, Eduardo J.; Brewer, Jess H.; Chow, Kim H.; Watanabe, Isao; Ikedo, Yutaka; Miyake, Yasuhiro; Kobayashi, Genki; Kanno, Ryoji

    In order to elucidate the magnetism and Li diffusion in LiFePO4, we have measured muon-spin rotation and relaxation (μ+SR) spectra for a polycrystalline LiFePO4 sample in the temperature range between 1.8 and 500 K. Below TN ∼ 52 K, two oscillatory signals together with onefast relaxation signal were clearly found in the zero-field (ZF) μ+SR spectrum. The three signals are reasonably explained using an antiferromagnetic (AF) spin structure proposedby neutron measurements, because electrostatic potential calculations suggests multiple different muon sites in the LiFePO4 lattice. However, the AF ordered moment estimated from μ+SR was about 3/4 of that reported by neutron, probably due to a different time window between the two techniques. In the paramagnetic state, ZF-and longitudinal-field (LF-) μ+SR spectraexhibiteda dynamic nuclear field relaxation. From the temperature dependence of the field fluctuation rate, a diffusion coeffcient of Li+ ions (DLi) at300K was estimated about 3.6×10-10 cm2/s, assuming that diffusing Li+ ions jump between the regular site and interstitial sites.

  9. Origin of the charge gap in LaMnPO

    SciTech Connect

    McNally, D. E.; Simonson, Jack W.; Post, K. W.; Yin, Zhiping P.; Pezzoli, M.; Smith, G. J.; Leyva, V.; Marques, C.; Debeer-Schmitt, Lisa M.; Kolesnikov, Alexander I.; Zhao, Yang; Lynn, J. W.; Basov, D. N.; Kotliar, G.; Aronson, Meigan C.

    2014-11-18

    In this paper, we present high temperature inelastic neutron scattering and magnetic susceptibility measurements of the antiferromagnetic insulator LaMnPO that are consistent with the presence of two-dimensional magnetic correlations up to a temperature Tmax≈700K»TN=375 K, the Néel temperature. Optical transmission measurements show the T=300 K direct charge gap Δ=1 eV has decreased only marginally by 500 K and suggest it decreases by only 10% at Tmax. Density functional theory and dynamical mean-field theory calculations reproduce a direct charge gap in paramagnetic LaMnPO only when a strong Hund's coupling JH=0.9 eV is included, as well as on-site Hubbard U=8 eV. In conclusion, our results show that LaMnPO is a Mott-Hund's insulator, in which the charge gap is rather insensitive to antiferromagnetic exchange coupling.

  10. 210Po in Human Saliva of Smokeless Tobacco Users.

    PubMed

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

    2017-01-01

    The occurrence and mobility of Po in oral smokeless tobacco products (STPs) were determined because its effects on human health must be taken into account. This research was subdivided into two parts: determination by alpha spectrometry of the Po activity concentration in 16 oral smokeless tobacco products of different brands purchased in local specialty stores in Europe and evaluation of its percent extraction into an artificial salivary gland during sucking or chewing operations. Polonium-210 was detected in all samples, and its concentrations ranged from 3.46 to 14.8 Bq kg (mean value of 7.45 ± 3.82 Bq kg). The highest concentration was found in chewing tobacco. The samples showed no significant difference in the content of Po level. The data obtained in this study show that the polonium, although poorly extracted (12.8 ± 8.96%) by artificial saliva, is not totally retained within the smokeless tobacco products, with a consequent potential health hazard associated with oral use of these products.

  11. A biokinetic study of 209Po in man.

    PubMed

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

    2012-10-15

    Five adult volunteers participated in a biokinetic study of radioactive polonium. Portions of about 10 Bq of (209)Po were orally administrated to four of the volunteers in a single ingestion. The fifth volunteer ingested a daily amount of 53 mBq of 209Po for 243 d to study the time to achieve equilibrium between intake and excretion for protracted intakes. For the subjects ingesting single intakes of (209)Po complete sampling of urine and feces was subsequently collected the first few days upon the ingestion. The samples were processed with radiochemical extraction and analyzed with alpha spectrometry. In the study, the maximum daily excretion rates in feces were 18-50% of the ingested activity, observed within 3 d after intake. Regarding the urine excretion, the daily excretion peaked, on average, at 0.15-1% of the ingested activity within two days upon intake. These results indicate an average gastro-intestinal uptake fraction of 0.46±0.08, which agrees well with earlier biokinetic studies of polonium in man. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Can Vanadium Be Substituted into LiFePO4

    SciTech Connect

    Omenya F.; Nam K.; Chernova N.A.; Upreti S.; Zavalij P.Y.; Nam K.-W.; Yang X.-Q.; Whittingham M.S.

    2011-11-08

    Vanadium is shown to substitute for iron in the olivine LiFePO{sub 4} up to at least 10 mol %, when the synthesis is carried out at 550 C. In the solid solution LiFe{sub 1-3y/2}V{sub y}PO{sub 4}, the a and b lattice parameters and cell volume decrease with increasing vanadium content, while the c lattice parameter increases slightly. However, when the synthesis is performed at 650 C, a NASICON phase, Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}, is also formed, showing that solid solution is a function of the synthesis temperature. X-ray absorption near-edge structure indicates vanadium is in the 3+ oxidation state and in an octahedral environment. Magnetic studies reveal a shift of the antiferromagnetic ordering transition toward lower temperatures with increasing vanadium substitution, confirming solid solution formation. The addition of vanadium enhances the electrochemical performance of the materials especially at high current densities.

  13. Effect of Li3PO4 coating of layered lithium-rich oxide on electrochemical performance

    NASA Astrophysics Data System (ADS)

    Chen, Dongrui; Zheng, Feng; Li, Liu; Chen, Min; Zhong, Xiaoxin; Li, Weishan; Lu, Li

    2017-02-01

    A novel composite of layered lithium-rich oxide, Li-Rich@Li3PO4, coated with Li3PO4 is synthesized through polydopamine template method. Physical characterizations reveal that Li-Rich@Li3PO4 is composed of nanoparticles of 100-200 nm that are coated with a uniform Li3PO4 layer of about 5 nm in thickness. Galvanostatic charge/discharge tests demonstrate enhanced cycling stability and largely increased rate capability of the material after Li3PO4 coating.

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

    PubMed

    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.

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

    PubMed

    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.

  16. Visible light assisted degradation of organic dye using Ag3PO4

    NASA Astrophysics Data System (ADS)

    Dhanabal, R.; Velmathi, S.; Bose, A. Chandra

    2015-06-01

    The study of visible light photodegradation of organic dye Methylene Blue (MB) have been investigated using silver phosphate (Ag3PO4) as a photocatalyst which is good efficient material for photocatalytic reaction. The simple ion-exchange method is used to prepare Ag3PO4. The structure of the material have been confirmed using X-ray diffraction which shows cubic structure of Ag3PO4. The functional group of the Ag3PO4 has been verified by Fourier transform infrared spectroscopy. The bandgap of Ag3PO4 is calculated using kubelka-munk function from the ultra violet-visible diffuse reflectance spectroscopy, the absorption of Ag3PO4 starts from 470 nm. Under simulated visible light irradiation, Ag3PO4 catalyst exhibits good catalytic ability for degrading MB dye.

  17. Application of Polymeric Agents for Improved Soil Decontamination

    SciTech Connect

    Heiser, John

    2008-09-30

    The objectives of the Thrust II project include optimization of the technology for PO Mayak soils, identification of clean up requirements, design and construction of a mobile production-scale process system, installation and deployment of the soil washing technology.

  18. Coupling between the protons and PO4 tetrahedra in H+-ion-irradiated TlH2PO4

    NASA Astrophysics Data System (ADS)

    Han, Doug Young; Han, J. H.; Lee, Cheol Eui; Lee, Kwang-Sei; Kim, Se-Hun

    2012-11-01

    We studied hydrogen-bonded TlH2PO4 (TDP) ferroelectrics treated with proton-beam bombardment. The TDP material was irradiated with a 1-MeV proton beam at a dose of 1015/cm2. To analyze the local microscopic structure of TDP, we conducted 1H combined rotation and multiple pulse spectroscopy (CRAMPS), nuclear magnetic resonance (NMR), and high-resolution 31P NMR measurements. The isotropic chemical shifts of hydrogen and phosphor nuclei exhibited displacive features throughout the antiferroelectric, ferroelastic, and paraelastic phases that were attributed to the interplay of PO4 lattice deformation and the microscopic hydrogen bond network. The temperature dependence of the isotropic chemical shift σ iso in 1H and high resolution 31P NMR revealed that the electronic charge redistribution was induced by proton-beam irradiation and the material's elastic properties. We examined the proton-lattice relationship in terms of the proton's location in a local double minimum well and the displacive character of the PO4 lattice.

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

    PubMed Central

    Wiemels, Joseph L.

    2012-01-01

    Background: Polonium-210 (210Po) concentrations that exceed 1 Bq/L in drinking-water supplies have been reported from four widely separated U.S. states where exposure to it went unnoticed for decades. The radionuclide grandparents of 210Po are common in sediments, and segments of the public may be chronically exposed to low levels of 210Po in drinking water or in food products from animals raised in contaminated areas. Objectives: We summarized information on the environmental behavior, biokinetics, and toxicology of 210Po and identified the need for future research. Methods: Potential linkages between environmental exposure to 210Po and human health effects were identified in a literature review. Discussion: 210Po accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate 210Po, the ovary may be the critical organ in determining the lowest injurious dose for 210Po. 210Po also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to 210Po may have subtle, long-term biological effects because of its tropism towards reproductive and embryonic and fetal tissues where exposure to a single alpha particle may kill or damage critical cells. 210Po is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of 210Po. Conclusions: Much of the important biological and toxicological research on 210Po is more than four decades old. New research is needed to evaluate environmental exposure to 210Po and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary. PMID:22538346

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

    NASA Astrophysics Data System (ADS)

    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.

  1. 210Po concentration analysis on tobacco and cigarettes in Malaysia

    NASA Astrophysics Data System (ADS)

    Azman, Muhammad Azfar; Rahman, Irman Abdul; Yasir, Muhammad Samudi

    2013-05-01

    Tobacco or better known as the cigarette was smoked since ages. Although many efforts had been made by the Ministry of Health to prevent or reduce the cigarette problem, the smokers still consider that cigarette are not harmful to health. This work is conducted to study the concentration of radionuclides alpha in tobacco and tobacco products in Malaysia. The radionuclide sought in this study is 210Po which is an alpha emitter. The sample used are tobacco and cigarettes, the tobacco samples were taken from tobacco farms in Malaysia while the sample branded cigarettes Marlboro and Gudang Garam were bought in the supermarket. The objectives of this study are to determine the concentration of radionuclides 210Po in tobacco and tobacco products as well as to estimate the radioactivity doses contributing to the smokers in Malaysia. The results for Marlboro cigarettes and Gudang Garam were found to be on the average radionuclide concentration of 210Po is 13.3 mBq/g (Marlboro cigarettes) and 11.9 mBq/g (Gudang Garam). From the total concentration of the cigarette, the estimated annual contribution dose to smokers for every 20 cigarettes smoked per day are 111.9 ± 14.7 μSv/year for Marlboro cigarettes and 100.2 ± 3.3 μSv/year for Gudang Garam cigarettes. The average concentration of radionuclides for tobacco leaf tobacco for each area taken is 3.6 mBq / g for Bachok, 2.4 mBq / g for Tumpat and 3.1 mBq / g for Semerak district.

  2. Contribution of in vivo microvascular PO2 in the cat carotid body chemotransduction.

    PubMed

    Lahiri, S; Rumsey, W L; Wilson, D F; Iturriaga, R

    1993-09-01

    To understand the interplay between microcirculatory control and carotid body (CB) function, we simultaneously measured carotid body microvascular PO2 (CBM PO2) and chemosensory activity in the cat in vivo under several experimental conditions. Cats were anesthetized with pentobarbital sodium, paralyzed, and artificially ventilated. CBs were exposed, and steady-state CBM PO2 was measured by the O2-dependent quenching of the phosphorescence of Pd-meso-tetra-(4-carboxyphenyl)porphine, which was administered intravenously. A few fibers of the carotid sinus nerve were used to record chemosensory discharges. At arterial PO2 (PaO2) of 103.4 +/- 4.1 Torr, CBM PO2 was 52.5 +/- 3.6 Torr (n = 9). Graded lowering of PaO2 from 160 to 50 Torr resulted in nearly proportional decreases in CBM PO2, but at lower PaO2 the decrease in CBM PO2 became more substantial. As PaO2 decreased, chemosensory discharge increased in parallel with CBM PO2. Hypercapnia and hypocapnia did not significantly change the relationship between PaO2 and CBM PO2, although the chemosensory discharge responded significantly. CBM PO2 and chemosensory discharge were not affected by hemorrhagic hypotension until arterial blood pressure fell below approximately 50 Torr and then CBM PO2 decreased and chemosensory discharge increased. The lack of a significant effect of hemorrhagic hypotension indicated that O2 delivery to CB was almost independent of the systemic blood pressure. Taken together, the observations suggest that CB microcirculation and PO2 are subject to control by intrinsic mechanisms and that CBM PO2 is compatible with oxidative metabolism playing a role in O2 chemoreception during hypoxia.

  3. 210Po in Nevada groundwater and its relation to gross alpha radioactivity

    USGS Publications Warehouse

    Seiler, R.L.

    2011-01-01

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

  4. 210Po in nevada groundwater and its relation to gross alpha radioactivity.

    PubMed

    Seiler, Ralph L

    2011-01-01

    Polonium-210 ((210) Po) is a highly toxic alpha emitter that is rarely found in groundwater at activities exceeding 1 pCi/L. (210) Po 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 (210) Po 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 (210) Po is unsupported by (210) Pb, indicating that the (210) Po is mobilized from aquifer sediments. The only significant contributors to alpha particle activity in Lahontan Valley groundwater are (234/238) U, (222) Rn, and (210) Po. Radon-222 activities were below 1000 pCi/L and were uncorrelated with (210) Po activity. The only applicable drinking water standard for (210) Po in the United States is the adjusted gross alpha radioactivity (GAR) standard of 15 pCi/L. (210) Po was not volatile in a Nevada well, but volatile (210) Po has been reported in a Florida well. Additional information on the volatility of (210) Po is needed because GAR is an inappropriate method to screen for volatile radionuclides. About 25% of the samples had (210) Po 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 (210) Po may be justified to protect human health even though the maximum contaminant level for adjusted GAR is not exceeded.

  5. Atomic Mass and Nuclear Binding Energy for Po-280 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-280 (Polonium, atomic number Z = 84, mass number A = 280).

  6. Atomic Mass and Nuclear Binding Energy for Po-282 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-282 (Polonium, atomic number Z = 84, mass number A = 282).

  7. Atomic Mass and Nuclear Binding Energy for Po-274 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-274 (Polonium, atomic number Z = 84, mass number A = 274).

  8. Atomic Mass and Nuclear Binding Energy for Po-275 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-275 (Polonium, atomic number Z = 84, mass number A = 275).

  9. Atomic Mass and Nuclear Binding Energy for Po-276 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-276 (Polonium, atomic number Z = 84, mass number A = 276).

  10. Atomic Mass and Nuclear Binding Energy for Po-278 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-278 (Polonium, atomic number Z = 84, mass number A = 278).

  11. Atomic Mass and Nuclear Binding Energy for Po-270 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-270 (Polonium, atomic number Z = 84, mass number A = 270).

  12. Atomic Mass and Nuclear Binding Energy for Po-269 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-269 (Polonium, atomic number Z = 84, mass number A = 269).

  13. Atomic Mass and Nuclear Binding Energy for Po-284 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-284 (Polonium, atomic number Z = 84, mass number A = 284).

  14. Atomic Mass and Nuclear Binding Energy for Po-273 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-273 (Polonium, atomic number Z = 84, mass number A = 273).

  15. Atomic Mass and Nuclear Binding Energy for Po-283 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-283 (Polonium, atomic number Z = 84, mass number A = 283).

  16. Atomic Mass and Nuclear Binding Energy for Po-271 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-271 (Polonium, atomic number Z = 84, mass number A = 271).

  17. Atomic Mass and Nuclear Binding Energy for Po-272 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-272 (Polonium, atomic number Z = 84, mass number A = 272).

  18. Atomic Mass and Nuclear Binding Energy for Po-277 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-277 (Polonium, atomic number Z = 84, mass number A = 277).

  19. Atomic Mass and Nuclear Binding Energy for Po-279 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-279 (Polonium, atomic number Z = 84, mass number A = 279).

  20. Atomic Mass and Nuclear Binding Energy for Po-281 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-281 (Polonium, atomic number Z = 84, mass number A = 281).

  1. Superionicity in Na3 PO4 : A molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Yin, Wei-Guo; Liu, Jianjun; Duan, Chun-Gang; Mei, W. N.; Smith, R. W.; Hardy, J. R.

    2004-08-01

    Fast ionic conduction in solid Na3PO4 is studied by use of molecular dynamics simulation based on the modified Lu -Hardy approach. We obtain reasonable agreement with experiment for the structural transition and diffusion of the sodium ions. All the sodium ions are found to contribute comparably to the high ionic conductivity. The results of the simulation are discussed in terms of the relative magnitude of the two proposed transport mechanisms: percolation and paddle-wheel. It appears to us that the percolation mechanism dominates the sodium diffusion.

  2. The Growth of Berlinite (AlPO4) Single Crystals.

    DTIC Science & Technology

    1980-03-01

    0 u a) 00 1 4-) r4 - 0 xE x x oo " o 0 . 4 n 22 Figure 7. AIPO4 Seed Crystal - 23 - 2.8 Growth System 2.8.1 Tem-Pres Runs For small autoclave ...was about 300-3151C. For reasons of autoclave operation, the possibility of high quality, and - 37 - Figure 18 Close up of AlPO 4 Crystals -38- method...nutrient (#2) which was transported and recrystallized in the autoclaves , did not detect any sodium. As expected, the process of crystallization

  3. AgCo3PO4(HPO4)2.

    PubMed

    Guesmi, Abderrahmen; Driss, Ahmed

    2002-01-01

    The structure of the hydrothermally synthesized compound AgCo3PO4(HPO4)2, silver tricobalt phosphate bis(hydrogen phosphate), consists of edge-sharing CoO6 chains linked together by the phosphate groups and hydrogen bonds. The three-dimensional framework delimits two types of tunnels which accommodate Ag+ cations and OH groups. The title compound is isostructural with the compounds AM3H2(XO4)3 (A = Na or Ag, M = Co or Mn, and X = P or As) of the alluaudite structure type.

  4. Atomic Mass and Nuclear Binding Energy for Po-210 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-210 (Polonium, atomic number Z = 84, mass number A = 210).

  5. An emergency bioassay method for (210)Po in urine.

    PubMed

    Guérin, Nicolas; Dai, Xiongxin

    2015-09-01

    A rapid method was developed to efficiently measure (210)Po in urine samples in an emergency situation. Polonium-210 in small urine samples (10 mL) was spontaneously deposited on a stainless steel disc in 1 M HCl at room temperature for 4 h in a polyethylene bottle. The metallic disc was then counted for 4 h by alpha spectrometry. The developed method allowed the preparation of large sample batch in a short time. The method meets the requirements for an emergency bioassay procedure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Atomic Mass and Nuclear Binding Energy for Po-211 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-211 (Polonium, atomic number Z = 84, mass number A = 211).

  7. Atomic Mass and Nuclear Binding Energy for Po-268 (Polonium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Po-268 (Polonium, atomic number Z = 84, mass number A = 268).

  8. Climatology of atmospheric PM10 concentration in the Po Valley

    NASA Astrophysics Data System (ADS)

    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

  9. Energetics of phosphate frameworks containing zinc and cobalt: NaZnPO{sub 4}, NaH(ZnPO{sub 4}){sub 2}, NaZnPO{sub 4}.H{sub 2}O, NaZnPO{sub 4}.4/3 H{sub 2}O, and NaCo{sub x}Zn{sub 1-x}PO{sub 4}.4/3 H{sub 2}O

    SciTech Connect

    Le, So-Nhu; Navrotsky, Alexandra

    2007-09-15

    Differential scanning calorimetry and high temperature oxide melt solution calorimetry were used to study the enthalpy of the {alpha}-{beta} phase transformation of NaZnPO{sub 4} and enthalpies of formation of {alpha}-NaZnPO{sub 4}, NaH(ZnPO{sub 4}){sub 2}, NaZnPO{sub 4}.H{sub 2}O, and NaCo{sub x}Zn{sub 1-x}PO{sub 4}.4/3 H{sub 2}O (x=0, 0.1, 0.2, 0.3). The enthalpies of formation from the oxides of cobalt substituted in NaZnPO{sub 4}.4/3 H{sub 2}O do not depend on cobalt content, confirming similar acid-base interactions for Zn-PO{sub 4} and Co-PO{sub 4}. While water molecules stabilize zinc phosphate frameworks through solvating a cation or forming extra hydrogen bonds, the partial substitution of water for sodium oxide to form NaH(ZnPO{sub 4}){sub 2} represents the formation of an acidic compound with weaker acid-base interactions and less exothermic enthalpy of formation from oxides than Na{sub 2}(ZnPO{sub 4}){sub 2}. - Graphical abstract: Relative stability of NaZnPO{sub 4} dense phases, open frameworks, and hydrated frameworks. Enthalpy of interaction between water and NaZnPO{sub 4} frameworks is presented by reaction: NaZnPO{sub 4} (cr, open framework) + nH{sub 2}O (l) {yields} NaZnPO{sub 4}.nH{sub 2}O (cr, hydrated framework)

  10. Micro-Raman observation on the H2PO4(-) association structures in a supersaturated droplet of potassium dihydrogen phosphate (KH2PO4).

    PubMed

    Syed, Kamran Ajmal; Pang, Shu-Feng; Zhang, Yun; Zhang, Yun-Hong

    2013-01-14

    The efflorescence of an individual KH(2)PO(4) droplet on Teflon substrate was investigated by micro-Raman spectroscopy. With the decrease of relative humidity (RH) from 98.0% to 73.0%, the KH(2)PO(4) droplet lost water gradually and entered into supersaturated state, which was reflected by the area ratio between the water stretching band to the sum of ν(s)-PO(2) and ν(s)-P(OH)(2) bands of the H(2)PO(4)(-) (A(H(2)O)/(A((ν(s)-PO(2))+A(ν(s)-P(OH)(2))))). In 1.0 mol l(-1) KH(2)PO(4) solution, the ν(s)-P(OH)(2) and ν(s)-PO(2) bands appeared at 877 and 1077 cm(-1). In the KH(2)PO(4) droplet, the two bands shifted to 894 and 1039 cm(-1) at 98.0% RH, to 899 and 1031 cm(-1) at 89.6% RH, and then to 904 and 997 cm(-1) at 73.0% RH. Moreover, the aggregation process between the H(2)PO(4)(-) ions was observed from the spectral characteristic of the ν(s)-P(OH)(2) band in the concentration process, including the transitions of the H(2)PO(4)(-) ions from monomer in bulk solutions (0.5-1.0 mol l(-1)) to possible dimers at 98.0% RH and then further to oligomers in the droplet with the RH decrease, which were indicated by the blueshift of the ν(s)-P(OH)(2) band and its full width at half-height as a function of the RH. When the RH reached at 72.0%, the anhydrous crystal was obtained. A strong peak appeared at 928 cm(-1), implying that the four oxygen atoms of the H(2)PO(4 (-) were all hydrogen bonding through the bridge hydrogen atoms to get the extensive hydrogen-bonded network structure of the H(2)PO(4)(-) association, leading to the symmetric increase of the H(2)PO(4)(-) ion from C(2v) in dilute solution to quasi-T(d) in the anhydrous crystal.

  11. Micro-Raman observation on the H2PO4- association structures in a supersaturated droplet of potassium dihydrogen phosphate (KH2PO4)

    NASA Astrophysics Data System (ADS)

    Syed, Kamran Ajmal; Pang, Shu-Feng; Zhang, Yun; Zhang, Yun-Hong

    2013-01-01

    The efflorescence of an individual KH2PO4 droplet on Teflon substrate was investigated by micro-Raman spectroscopy. With the decrease of relative humidity (RH) from 98.0% to 73.0%, the KH2PO4 droplet lost water gradually and entered into supersaturated state, which was reflected by the area ratio between the water stretching band to the sum of νs-PO2 and νs-P(OH)2 bands of the H2PO4- (A_{H_2 O} /(A_{(ν _s -PO_2 } {+ A}_{ν _s -P(OH)_2 {)}} {)}). In 1.0 mol l-1 KH2PO4 solution, the νs-P(OH)2 and νs-PO2 bands appeared at 877 and 1077 cm-1. In the KH2PO4 droplet, the two bands shifted to 894 and 1039 cm-1 at 98.0% RH, to 899 and 1031 cm-1 at 89.6% RH, and then to 904 and 997 cm-1 at 73.0% RH. Moreover, the aggregation process between the H2PO4- ions was observed from the spectral characteristic of the νs-P(OH)2 band in the concentration process, including the transitions of the H2PO4- ions from monomer in bulk solutions (0.5-1.0 mol l-1) to possible dimers at 98.0% RH and then further to oligomers in the droplet with the RH decrease, which were indicated by the blueshift of the νs-P(OH)2 band and its full width at half-height as a function of the RH. When the RH reached at 72.0%, the anhydrous crystal was obtained. A strong peak appeared at 928 cm-1, implying that the four oxygen atoms of the H2PO4- were all hydrogen bonding through the bridge hydrogen atoms to get the extensive hydrogen-bonded network structure of the H2PO4- association, leading to the symmetric increase of the H2PO4- ion from C2v in dilute solution to quasi-Td in the anhydrous crystal.

  12. Energy transfer from PO excited states to alkali metal atoms in the phosphorus chemiluminescence flame

    PubMed Central

    Khan, Ahsan U.

    1980-01-01

    Phosphorus chemiluminescence under ambient conditions of a phosphorus oxidation flame is found to offer an efficient electronic energy transferring system to alkali metal atoms. The lowest resonance lines, 2P3 / 2,½→2S½, of potassium and sodium are excited by energy transfer when an argon stream at 80°C carrying potassium or sodium atoms intersects a phosphorus vapor stream, either at the flame or in the postflame region. The lowest electronically excited metastable 4IIi state of PO or the (PO[unk]PO)* excimer is considered to be the probable energy donor. The (PO[unk]PO)* excimer results from the interaction of the 4IIi state of one PO molecule with the ground 2IIr state of another. Metastability of the donor state is strongly indicated by the observation of intense sensitized alkali atom fluorescence in the postflame region. PMID:16592925

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  14. NEO hazards : NEOShield and PoDET perspectives

    NASA Astrophysics Data System (ADS)

    Eggl, S.; Hestroffer, D.; Thuillot, W.; Bancelin, D.

    2014-04-01

    The Chelyabinsk event in 2013 has shown that asteroids - even of moderate size - must be considered as natural disasters that do present a non negligible risk to people and property. At an international level, several actions have been undertaken for developing awareness and warning strategies. The PoDET hub at IMCCE, for instance, encompasses research activities for orbit propagation and ephemerides of space debris, meteorite streams, and NEOs (asteroids, comets, meteoroids). For objects with diameters larger than approximately 100m the potential damage caused by an impact may warrant additional emergency measures, such as the implementation of a mitigation plan. Investigating such a scenario is the aim of the NEOShield FP7 project. In this contribution we present NEO related aspects of the PoDET and NEOShield programs. More specifically, we will discuss issues related to the target selection for an asteroid deflection demonstration mission as well as the post-mitigation orbit propagation for estimating possible changes in the impact risk of such target asteroids.

  15. Irradiation-induced amorphization of AlPO 4

    NASA Astrophysics Data System (ADS)

    Sreeram, A. N.; Hobbs, L. W.; Bordes, N.; Ewing, R. C.

    1996-08-01

    AlPO 4, in the mineral form berlinite, is isostructural with α-quartz. We have investigated the irradiation-induced amorphization of hydrothermally-grown berlinite and found that — like quartz and other silicas but unlike most other phosphates — it undergoes solid-state radiolyis, with an efficiency fifty times that of quartz at room temperature, and amorphizes at an absorbed ionization dose of about 1 GGy. High-resolution TEM revealed that — unlike quartz in which small amorphous inclusions nucleate — electron-irradiated AlPO 4 proceeds uniformly to an aperiodic state, much as do cristobalite and tridymite, and 20 times faster. It was found also to amorphize under 1.5 MeV Kr + ion irradiation at a collisional energy density (10 eV/atom) similar to that for quartz and in keeping with the degree of structural freedom afforded by its tetrahedral network structure. The critical ion fluence for amorphization was found to increase by a factor of 5 between 300 and 600 K. Radial distribution functions derived from energy-filtered electron diffraction patterns from regions amorphized by electrons resemble those of electron-amorphized quartz with some additional features.

  16. PoPSat: The Polar Precipitation Satellite Mission

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

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

    2014-11-01

    Due to increasing application of (210)Po/(210)Pb in studying particle dynamics, a consistent procedure and calculation to derive accurate and precise result of (210)Po and (210)Pb in seawater should be proposed in the framework of intercalibration by GEOTRACES. The associated uncertainty of radioactivity, which is a significant component of data report, plays a vital role in intercomparison and should be well evaluated. Although measurement uncertainty of laboratory result was well defined in ISO standards and IAEA technical documents, the decay/ingrowth uncertainty correction from laboratory result to in-situ result was less studied. It was demonstrated that the relative uncertainty of in-situ (210)Pb activity was independent of elapsed time and equal to relative uncertainty of laboratory measuring (210)Po activity at second spontaneous deposition date. The relative uncertainty of in-situ (210)Po activity decreases with in-situ activity ratio of (210)Po to (210)Pb and increases with elapsed time between sampling date and separation date, relative uncertainty of laboratory measuring (210)Po activity at first spontaneous deposition date and relative uncertainty of in-situ (210)Pb activity. It was more important to improve precision of (210)Po at first spontaneous deposition date than that of (210)Po at second spontaneous deposition date. To obtain a desirable relative uncertainty of in-situ (210)Po activity, the maximum allowing elapsed time for (210)Po, which was important for sampling strategy making and quality assurance, was calculated by in-situ activity ratio of (210)Po to (210)Pb and precision of analytical method for (210)Po. The methodology of decay/ingrowth uncertainty correction could also be applied for other radionuclide pairs ((234)Th/(238)U, (90)Y/(90)Sr, (210)Bi/(210)Pb), sample matrixes (aerosols), and disciplines. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Utilizing 210Po deficit to constrain particle dynamics in mesopelagic water, western South China Sea

    NASA Astrophysics Data System (ADS)

    Ma, Haoyang; Yang, Weifeng; Zhang, Lihao; Zhang, Run; Chen, Min; Qiu, Yusheng; Zheng, Minfang

    2017-04-01

    The 210Po-210Pb pair is increasingly used as a proxy of quantifying organic carbon export from the euphotic zone. However, disequilibria between 210Po and 210Pb in mesopelagic water have been poorly studied. Here we present unusual deficiencies of 210Po with respect to 210Pb in mesopelagic water (200-1000 m) in the South China Sea (SCS). The total particulate matter (TPM) increased by up to 32% in the mesopelagic layer comparing with the euphotic zone. The total 210Po/210Pb ratio varied from 0.41 to 0.98 with an average of 0.72 ± 0.19, showing an enhanced removal of 210Po in mesopelagic water. On average, particulate 210Po and 210Pb increased by 23% and 32% at the slope stations, respectively. These results indicated that the 210Po deficits result from lateral transport, probably via benthic nepheloid layer. Based on the deficiency of 210Po, the residence times of particulate 210Po were estimated to range from 0.11 to 0.25 year (avg. 0.17 ± 0.07 year), allowing resuspended sediment to disperse over a long range. The export fluxes of 210Po varied from 68 to 121 dpm m-2 d-1 with an average of 96 ± 27 dpm m-2 d-1, which was 6 times that out of the euphotic zone. Using the 210Po deficits, the export fluxes of TPM out of the mesopelagic layer were quantified to vary from 4.19 to 10.20 g m-2 d-1, revealing a large amount of particles from the shelf to the SCS basin. This study suggests that 210Po-210Pb could be an effective tracer of tracking particle cycling in mesopelagic water.

  19. {sup 210}Po and {sup 210}Pb intake by the Portuguese population: The contribution of seafood in the dietary intake of {sup 210}Po and {sup 210}Pb

    SciTech Connect

    Carvalho, F.P.

    1995-10-01

    Through analysis of {sup 210}Po and {sup 210}Pb in the diet, the average ingestion rate for the Portuguese population is estimated at 1.2 and 0.47 Bq d{sup -1} per capita for {sup 210}Po and {sup 210}Pb, respectively. Detailed analysis of foods indicate that seafood alone contributes up to 70% of the {sup 210}Po ingestion rate, whereas cerals, vegetables, and meat altogether contribute 79% of the {sup 210}Pb ingestion rate. Consumption of seafood, both in terms of quantities (kg d{sup -1} per person) and preferential consumption of certain marine species, is the cause of the relatively high intake of {sup 210}Po and high {sup 210}Po:{sup 210}Pb ratio in the diet in comparison with other countries. Other {sup 210}Po and {sup 210}Pb sources, namely inhalation of surface air and cigarette smoke, contribute only a small percentage of the adsorption of these radionuclides in the blood. Estimated total body burdens of {sup 210}Po and {sup 210}Pb in adult men, 70 Bq, are 3.5 times higher than estimates for humans living in normal radioactivity regions and consuming a reference diet. Average whole body effective doses for the adult from the Portuguese population are estimated at about 85 {mu}Sv y{sup -1} from {sup 210}Po and 170 {mu}Sv y{sup -1} from {sup 210}Pb adsorbed with the diet. Effective dose from {sup 210}Po in the diet may vary from 25 {mu}Sv y{sup -1} in an heavy consumer of sardines, to 1,000 {mu}Sv y{sup -1} in an hypothetical heavy consumer of molluscs. 46 refs., 2 figs., 4 tabs.

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

    SciTech Connect

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

    2008-08-07

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

  1. Facile synthesis of porous Ag3PO4 nanotubes for enhanced photocatalytic activity under visible light

    NASA Astrophysics Data System (ADS)

    Wan, Jun; Sun, Lin; Fan, Jun; Liu, Enzhou; Hu, Xiaoyun; Tang, Chunni; Yin, Yunchao

    2015-11-01

    Porous Ag3PO4 nanotubes (PNTs) were synthesized via a surface anion exchange reaction from the pregrown Ag2CO3 nanorods (NRs) templates in the aqueous solution. The rationally release rate of H+ and PO43- from Na2HPO4 are proved to be the key factors for the formation of Ag3PO4 PNTs. SEM analysis indicated that Ag3PO4 PNTs have a nearly homogeneous size with about 350 nm diameter, 2.1 μm length and 74 nm wall thickness. Nanoholes with diameters in range of 40-200 nm were existed on the side wall of the tubular structure. Compared with irregular Ag3PO4, Ag3PO4 PNTs exhibit an apparently enhancement of visible-light absorption and a significant decrease of PL intensities, indicating a better light absorption and a lower charge recombination rate. The photocatalytic performance studies for the degradation of RhB indicate that Ag3PO4 PNTs not only exhibit the highest adsorption ability towards dye molecules, but also possess superior photocatalytic activity than that of Ag2CO3 NRs and irregular Ag3PO4. The origin of the higher photocatalytic activity is primarily ascribed to the peculiar porous tubular nanostructure. h+ and •O2- are investigated to be the major reactive species for the Ag3PO4 PNTs photocatalytic system.

  2. Sequential microfluidic flow synthesis of CePO4 nanorods decorated with emission tunable quantum dots.

    PubMed

    Fang, Jie; Evans, Cameron W; Willis, Glen J; Sherwood, David; Guo, Yanglong; Lu, Guanzhong; Raston, Colin L; Iyer, K Swaminathan

    2010-10-07

    CePO(4) nanorods decorated with QDs (QDs@CePO(4)) can be prepared in a sequential, aqueous procedure under continuous flow using a rotating tube processor and a narrow channel reactor. The emission from the QD@CePO(4) is tunable from green to red by simply adjusting the feeding rate, which in turn regulates the particle size of the QDs. The Ce(3+) ions in the QDs@CePO(4) serve as an efficient fluorescence resonance energy transfer (FRET) donor, effectively enlarging the Stokes shift of the QDs.

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

    PubMed Central

    Dong, Pengyu; Hou, Guihua; Liu, Chao; Zhang, Xinjiang; Tian, Hao; Xu, Fenghua; Xi, Xinguo; Shao, Rong

    2016-01-01

    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. PMID:28774088

  4. 210Po and 210Pb in Forest Soil and in Wild Berries in Finland

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  5. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism

    PubMed Central

    Seifitokaldani, Ali; Gheribi, Aïmen E.; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-01-01

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures. PMID:27604551

  6. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism.

    PubMed

    Seifitokaldani, Ali; Gheribi, Aïmen E; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-09-08

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures.

  7. Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism

    NASA Astrophysics Data System (ADS)

    Seifitokaldani, Ali; Gheribi, Aïmen E.; Phan, Anh Thu; Chartrand, Patrice; Dollé, Mickaël

    2016-09-01

    A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures.

  8. Structure Characterization and Magnetic Behavior of NaNi 4(PO 4) 3and KMn 4(PO 4) 3

    NASA Astrophysics Data System (ADS)

    Daidouh, Abdelaali; Martinez, J. L.; Pico, C.; Veiga, M. L.

    1999-04-01

    New sodium nickel and potassium manganese orthophosphates NaNi4(PO4)3(abbreviated asNNP) and KMn4(PO4)3(KMP) with tunnel structures have been synthesized. They crystallizes in the orthorhombic space group Pnmm witha=6.148(6) Å,b=16.210(1) Å,c=9.479(4) Å for (NNP), anda=6.554(8) Å,b=16.04(9) Å,c=9.977(2) Å for (KMP). The structure is built up from trinuclear groups of edge-sharingMO6octahedra, giving rise to the [M3O11]∞chains running along the [100] direction. Both materials show antiferromagnetic interactions and exhibit spontaneous magnetization at low temperatures, which can be explained by a canting of spin arrangement, giving rise to a weak ferromagnetic component. This behavior can be interpreted on the basis of structural features and the characteristics of single-ion intercalations.

  9. Scintillation properties of rare-earth doped NaPO3-Al(PO3)3 glasses

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    We systematically investigated photoluminescence (PL), scintillation and dosimeter properties of rare-earth (RE) doped NaPO3-Al(PO3)3 (NAP) glasses. The NAP glasses doped with a series of RE ions (La-Yb, except Pm) with a consistent concentration (0.3 wt%) were prepared by the conventional melt-quenching method. The PL and scintillation decay time profiles showed fast (ns) and slow (μs or ms) components: the fast components from 15 to 100 ns were due to the host or 5d-4f transition emission, and the slow components from 15 μs to 5 ms were due to the 4f-4f transitions of RE. The thermally stimulated luminescence (TSL) was evaluated as a dosimeter property, and glow peaks appeared around 400 °C in all the samples. The TSL dose response function was examined in the dose range from 10 mGy to 10 Gy. Among the samples tested, Nd and Tb doped glasses showed higher signal by at least one order of magnitude than those of non-doped and other RE-doped samples. Over the dose range tested, the TSL signals are linearly related with the incident X-ray dose, showing a potential for practical applications.

  10. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-09-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using a Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM : OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  11. Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Saarikoski, S.; Carbone, S.; Decesari, S.; Giulianelli, L.; Angelini, F.; Teinilä, K.; Canagaratna, M.; Ng, N. L.; Trimborn, A.; Facchini, M. C.; Fuzzi, S.; Hillamo, R.; Worsnop, D.

    2012-03-01

    The chemistry of submicron particles was investigated at San Pietro Capofiume (SPC) measurement station in the Po Valley, Italy, in spring 2008. The measurements were performed by using both off-line and on-line instruments. Organic carbon (OC) and elemental carbon, organic acids and biomass burning tracers were measured off-line by using a 24-h PM1 filter sampling. More detailed particle chemistry was achieved by using an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and analyzing the data by positive matrix factorization (PMF). Oxalic acid had the highest concentrations of organic acids (campaign-average 97.4 ng m-3) followed by methane sulfonic, formic, malonic, and malic acids. Samples were also analyzed for glyoxylic, succinic, azelaic and maleic acids. In total, the nine acids composed 1.9 and 3.8% of OC and water-soluble OC, respectively (average), in terms of carbon atoms. Levoglucosan concentration varied from 17.7 to 495 ng m-3 with the concentration decreasing in the course of the campaign most likely due to the reduced use of domestic heating with wood. Six factors were found for organic aerosol (OA) at SPC by PMF: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), nitrogen-containing OA (N-OA) and three different oxygenated OAs (OOA-a, OOA-b and OOA-c). Most of the OA mass was composed of OOA-a, HOA and OOA-c (26, 24 and 22%, respectively) followed by OOA-b (13%), BBOA (8%) and N-OA (7%). As expected, OOAs were the most oxygenated factors with organic matter:organic carbon (OM:OC) ratios ranging from 1.9 to 2.2. The diurnal variability of the aerosol chemical composition was greatly affected by the boundary layer meteorology. Specifically, the effect of the nocturnal layer break-up in morning hours was most evident for nitrate and N-OA indicating that these compounds originated mainly from the local sources in the Po Valley. For sulfate and OOA-a the concentration did not change during the break-up suggesting their

  12. Sulphur budget at Poàs volcano

    NASA Astrophysics Data System (ADS)

    Fournier, N.; Williams-Jones, G.; Rymer, H.

    2001-12-01

    Poàs volcano has been extensively studied over the last 15 years. Both geochemical and geophysical data have been integrated in order to develop a better understanding of the volcanic processes occurring there. A major feature at Poàs is the presence of a well-developed hydrothermal system and an acidic crater lake. Between 1995 and 2001, the consistency of parameters such as lake level, temperature and composition, ground deformation, micro-gravity, river and gas flux and composition, can help to estimate the total sulphur budget of the magmatic system. Sulphur from the magma enters a brine which feeds the Rio Agrio on the west flank of the volcanic edifice. The extreme acidity of the hydrothermal system (pH ~ 0-0.5) enhances the permeability of the summit area (loss of 1650 m3.y-1 in this zone; Rowe et al., 1992). The lack of ground deformation suggests that most of the voids are filled by mineral deposition in order to maintain the yield strength of the volcanic deposits. Previous studies show that the calculated precipitation of liquid sulphur at equilibrium, largely exceeds the deposition amount required to maintain a lower porosity. Based on the constant lake level, temperature and chemistry, as well as the calculated sulphur input and output in the lake between 1995 and 2001, an annual budget of approximately 11x103 tonnes of magmatic S entering the lake is required. COSPEC measurements for March 2001give minimum SO2 flux of ~ 40 t/d. This flux is of the same magnitude as the flux measured by Andres et al. in 1991. Assuming that this flux was relatively constant during the last 6 years (consistent with visual observations), it implies a mean annual S output of 7200 tonnes as SO2(g). As it is extremely difficult to remove SO2 from a hydrothermal system (Symonds et al., 2001), the total SO2 budget must come from the magma. The corresponding volume of degassed magma is ~3.9x10-3 km3 per year. The negligible volume of degassed magma, required to insure a

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    SciTech Connect

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

    2015-06-15

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

  15. [Immobilization technology and mechanism of fly ash using H3PO4].

    PubMed

    Wang, Jun; Jiang, Jian-Guo; Sui, Ji-Chao; Yang, Shi-Jian

    2006-08-01

    Chemical composition and toxicity leaching characteristics of fly ash was analyzed. The experiment results show that many heavy metals were contained; leaching concentration of Pb is 67.03 mg/L, which exceeds the limit of identification standard for hazardous wastes. Effect of input mass of H3PO4 on immobilization of heavy metals and its long-term environmental stability was studied. The results show that when input 8% - 14% (H3PO4 mass/ fly ash mass) of H3PO4 sound immobilization effect can be achieved; 8% and 12% of H3PO4 will bring a satisfactory environmental stability of heavy metals, while more H3PO4 led to less buffer capacity to acid conditions. In fly ash treated by 12% H3PO4, a small quantity of crystal Cr2P2O7, ZnP2, Pb3P4O13, Pb3P2O7, NaZnPO4, NaPbP3O9, Ca2ZnSi2O7 can be detected by XRD; many independent fly ash particles and bar-shaped Pb5 (PO4)3Cl with a diameter of 0.3 - 0.5 microm were observed by SEM; concentrated heavy metal materials were not obtained by CHBr3 floatation. Conclusions can be drawn that, through neutralization reaction of H3PO4 with strongly alkaline fly ash, stabilization reaction conditions were improved, entrapped heavy metals were chemically activated and PO4(3-) needed in stabilization was produced. Activated heavy metals combined with PO4(3-) on surface of fly ash,generated phosphates existing as forms of solid solution in SiO2, CaCO3, CaSO4, KCl, NaCl.

  16. Crystal and magnetic structures of electrochemically delithiated Li 1- xCoPO 4 phases

    NASA Astrophysics Data System (ADS)

    Ehrenberg, Helmut; Bramnik, Natalia N.; Senyshyn, Anatoliy; Fuess, Hartmut

    2009-01-01

    Precise structural data have been determined from a combined Rietveld refinement, based on neutron and X-ray powder diffraction data simultaneously, for the three phases LiCoPO 4, Li zCoPO 4 with a specific intermediate Li-content z = 0.60(10) and CoPO 4, which are obtained by electrochemical Li-extraction from LiCoPO 4. All three phases are isopointal. Therefore, the transitions between these phases are necessarily of first order, in agreement with their observed coexistence. The same collinear antiferromagnetic structures with magnetic moments nearly parallel to the [010] direction are observed for LiCoPO 4 and Li zCoPO 4, but with a significantly higher Néel temperature of 76 K for the latter compound in comparison with 23 K for LiCoPO 4. Olivine-type CoPO 4 can only be prepared from LiCoPO 4 by delithiation and its physical properties were investigated for the first time. An antiferromagnetic arrangement along the [100] direction is observed for CoPO 4 with an additional weak ferromagnetic component along the [001] direction (magnetic space group Pn' m' a and TC = 45 K). The magnetic moment of 3.1(2) μ B per Co-ion indicates a mainly high-spin state for Co 3+ in the octahedral coordination of CoPO 4, which is exceptional and probably the first example in a phosphate. The easy axes and the magnetic exchange interactions between Co-ions change dramatically with the Co 2+ ↔ Co 3+ transition. A continuous change of the formal oxidation state of a transition element by electrochemical Li-extraction and a quasi-continuous in situ observation of the resulting magnetic structure by neutron diffraction appear feasible.

  17. Magnetic phase diagram of magnetoelectric LiMnPO4

    SciTech Connect

    Toft-Petersen, Rasmus; Andersen, Niels H.; Li, Haifeng; Li, Jiying; Tian, Wei; Budko, Serguei L.; Jensen, Thomas B.S.; Niedermayer, Christof; Laver, Mark; Zaharko, Oksana; Lynn, Jeffrey W.; Vaknin, David

    2012-06-14

    The nature of the spin-flop (SF) transition in the magnetoelectric quasi-2D Heisenberg system LiMnPO4 is studied in fields applied along the a axis. A refinement of the magnetic structure using neutron diffraction data in the SF phase reveals that the spins reorient from being parallel to the a axis to be nearly along the c axis at magnetic fields between 4 and 4.7 T, depending on temperature. The low-field antiferromagnetic phase boundary is shown to join the spin-flop line tangentially at the so-called bicritical point, where there is a suppression of the ordering temperature. At the bicritical field, we observe an increased intensity of the Lorentz broadened elastic scattering at magnetic Bragg peaks above TN as compared to zero field and 10 T, without an increase in peak width. This suggests an increased density of fluctuations at the bicritical field as compared to zero field.

  18. PO*WW*ER mobile treatment unit process hazards analysis

    SciTech Connect

    Richardson, R.B.

    1996-06-01

    The objective of this report is to demonstrate that a thorough assessment of the risks associated with the operation of the Rust Geotech patented PO*WW*ER mobile treatment unit (MTU) has been performed and documented. The MTU was developed to treat aqueous mixed wastes at the US Department of Energy (DOE) Albuquerque Operations Office sites. The MTU uses evaporation to separate organics and water from radionuclides and solids, and catalytic oxidation to convert the hazardous into byproducts. This process hazards analysis evaluated a number of accident scenarios not directly related to the operation of the MTU, such as natural phenomena damage and mishandling of chemical containers. Worst case accident scenarios were further evaluated to determine the risk potential to the MTU and to workers, the public, and the environment. The overall risk to any group from operation of the MTU was determined to be very low; the MTU is classified as a Radiological Facility with low hazards.

  19. Impact: Education/Public Outreach (E/PO)

    NASA Astrophysics Data System (ADS)

    Eisenhamer, B.

    2000-12-01

    What happens when professional astronomers/space scientists and professional educators work on an education and public outreach program together? With the IDEAS Grant Program, the outcomes are as plentiful as stars in the Milky Way. However, one sure thing is that real science is reaching more widespread audiences through small education and public outreach grants. The programs funded by IDEAS have allowed teams of scientists and educators to explore innovative methods of bringing astronomy and space science out of the research arena and into classrooms and the general public. Over the past years, the IDEAS Grant Program has amassed a wide array of E/PO products. This poster will look at some examples of the products and discuss how they have impacted their target audiences.

  20. Spectroscopy of {sup 193,195,197}Po

    SciTech Connect

    Fotiades, N.; Cizewski, J.A.; McNabb, D.P.; Ding, K.Y.; Davids, C.N.; Janssens, R.V.; Seweryniak, D.; Carpenter, M.P.; Amro, H.; Decrock, P.; Reiter, P.; Nisius, D.; Brown, L.T.; Fischer, S.; Lauritsen, T.; Wauters, J.; Bingham, C.R.; Huyse, M.; Andreyev, A.; Seweryniak, D.; Conticchio, L.F.; Brown, L.T.

    1997-08-01

    Excited states built on the 13/2{sup +} isomers of the odd-mass {sup 193,195,197}Po isotopes have been observed via in-beam {gamma}-ray spectroscopy. The {alpha} radioactivity of these isotopes has been used to tag {gamma}-ray transitions following the {sup A}Er+164 MeV {sup 32}S reactions, where A=164, 166, 167, 168, and 170. Prompt {gamma} radiation was measured by ten Compton-suppressed Ge detectors at the target position and the Fragment Mass Analyzer was used to select evaporation residues. The results are compared with the first excited states of the heavier odd-mass polonium isotopes and of the even-mass cores. {copyright} {ital 1997} {ital The American Physical Society}

  1. Modelling the behaviour of 210Po in high temperature processes.

    PubMed

    Mora, J C; Robles, B; Corbacho, J A; Gascó, Catalina; Gázquez, M J

    2011-05-01

    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. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Po River plume pattern variability investigated from model data

    NASA Astrophysics Data System (ADS)

    Falcieri, Francesco Marcello; Benetazzo, Alvise; Sclavo, Mauro; Russo, Aniello; Carniel, Sandro

    2014-09-01

    The Adriatic Sea is a semi-enclosed basin located in the NE part of the Mediterranean Sea and it is strongly influenced by riverine inputs. In its northern sub-basin the freshwater plume of the Po River, together with those of numerous smaller rivers, plays a fundamental role in driving the physical and biogeochemical processes of the whole basin. In this paper we characterize the surface plume structure and identify its patterns and temporal variability on seasonal and inter-annual scales relating it to its major forcings (i.e., river discharges and winds). To perform this analysis, a 3D hydrodynamic numerical model was implemented over the whole Adriatic for the period 2003-2010 and the resulting outputs were analyzed through a series of statistical tools. The inter-annual and seasonal averages of Sea Surface Salinity (SSS) fields show that the average patterns are composed of a coastal plume, wider or narrower depending on the season, that flows southward of the Po River mouths. The first two modes of the Empirical Orthogonal Functions (EOF) analysis show a similar distribution with a cumulative explained variance up to 60%; the third mode, instead, presents a plume shape that extends well into the basin. To obtain a more detailed representation of the plume, a 2×3 Self-Organizing Map (SOM) analysis was performed over the surface salinity fields. Two antithetic patterns were depicted: (i) a small plume confined to coastal areas, typical of low discharges and/or Bora wind events and (ii) a wider plume that extends into the basin, typical of high river discharges and/or Sirocco winds. The comparison between wind regimes, riverine inputs and the time series of the SOM's Best Matching Units (BMU) suggested that, on long time scales, river discharges represent the dominant forcing in defining the plume size and surface pattern, while on time scales of few days the plume dynamics are modulated mostly by the wind structure.

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

    PubMed

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

    2012-04-01

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

  4. Rate-dependent, Li-ion insertion/deinsertion behavior of LiFePO4 cathodes in commercial 18650 LiFePO4 cells.

    PubMed

    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.

  5. Designing of luminescent GdPO4:Eu@LaPO4@SiO2 core/shell nanorods: Synthesis, structural and luminescence properties

    NASA Astrophysics Data System (ADS)

    Ansari, Anees A.; Labis, Joselito P.; Aslam Manthrammel, M.

    2017-09-01

    GdPO4:Eu3+ (core) and GdPO4:Eu@LaPO4 (core/shell) nanorods (NRs) were successfully prepared by urea based co-precipitation process at ambient conditions which was followed by coating with amorphous silica shell via the sol-gel chemical route. The role of surface coating on the crystal structure, crystallinity, morphology, solubility, surface chemistry and luminescence properties were well investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Fourier Transform Infrared (FTIR), UV-Vis, and photoluminescence spectroscopy. XRD pattern revealed highly purified, well-crystalline, single phase-hexagonal-rhabdophane structure of GdPO4 crystal. The TEM micrographs exhibited highly crystalline and narrow size distributed rod-shaped GdPO4:Eu3+ nanostructures with average width 14-16 nm and typical length 190-220 nm. FTIR spectra revealed characteristic infrared absorption bands of amorphous silica. High absorbance in a visible region of silica modified core/shell/Si NRs in aqueous environment suggests the high solubility along with colloidal stability. The photoluminescence properties were remarkably enhanced after growth of undoped LaPO4 layers due to the reduction of nonradiative transition rate. The advantages of presented high emission intensity and high solubility of core/shell and core/shell/Si NRs indicated the potential applications in monitoring biological events.

  6. Canted antiferromagnetism in KNi3[PO3(F,OH)]2[PO2(OH)2]F2 with a stair-case Kagomé lattice

    NASA Astrophysics Data System (ADS)

    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.

  7. Electrochemical performance of NiO-doped LiFePO4/C cathode materials prepared from amorphous FePO4 · xH2O

    NASA Astrophysics Data System (ADS)

    Mahmud, Iqbal; Kim, Dong-Seob; Ur, Soon-Chul

    2016-05-01

    LiFePO4/C composites are prepared from amorphous FePO4 · xH2O and are modified with NiO (0.0, 0.01, 0.02, 0.03, and 0.04 mol) by using a solid-state reaction process with a spex milling system. The crystalline structure and the morphology of synthesized powders have been characterized by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD patterns indicate a complete solid solution for all the NiO-doped LiFePO4/C composites. The SEM images show that the sizes of the particles produced are distributed in the range of 200 - 300 nm. The electrochemical performances have been evaluated by using an impedance measurement and a galvanostatic charge/discharge test. The initial properties and impedance measurement reveal different improvements for different amounts of NiO doping in LiFePO4/C. A maximum capacity of 158.8 mAh/g at 0.1 C has been achieved LiFePO4/C doped with NiO at 0.01 mol. The present work reveals that the newly processed composite of LiFePO4/C doped with a small amount of NiO may be a promising material for using in a lithium-ion battery.

  8. Draft Genome Sequence of Biocontrol Agent Pythium oligandrum Strain Po37, an Oomycota

    PubMed Central

    Berger, Harald; Yacoub, Amira; Gerbore, Jonathan; Grizard, Damien; Rey, Patrice; Sessitsch, Angela

    2016-01-01

    The oomycota Pythium oligandrum Po37 is used as a biocontrol agent of plant diseases. Here, we present the first draft of the P. oligandrum Po37 genome sequence, which comprises 725 scaffolds with a total length of 35.9 Mb and 11,695 predicted protein-coding genes. PMID:27081125

  9. Amphiphilic carbonaceous material-intervened solvothermal synthesis of LiFePO4

    NASA Astrophysics Data System (ADS)

    Chen, Ming-ming; Ma, Qian-qian; Wang, Cheng-yang; Sun, Xin; Wang, Li-qun; Zhang, Cui

    2014-10-01

    LiFePO4 samples with preferred facets on the ac plane were prepared by the solvothermal method with or without well-dispersed amphiphilic carbonaceous material (ACM). The effects of ACM on the particle morphology, crystal orientation and electrochemical reactivity of the prepared LiFePO4 nanoparticles were investigated in detail. ACM serves a dual purpose. One purpose is facilitating the plate-like morphologies of LiFePO4 nanoparticles parallel to the bPnma axis by decreasing the surface energy of (010) facets of newly created LiFePO4 nuclei. The other purpose is suppressing crystal growth along the [010] direction by adhering onto the (010) surface of LiFePO4 nanoplates. Furthermore, ACM coating was performed and optimized using a carbon coating precursor. The electrochemical properties of the prepared LiFePO4 particles were characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge cycling tests. After the optimized coating of ACM, the ACM-intervened LiFePO4 composite was observed to deliver discharge capacities of 151.3 mAh g-1 at 1C and 132.2 mAh g-1 at 10C. Even after 1000 cycles at a high rate of 10C, the LiFePO4 cathode could maintain 80% of its initial capacity.

  10. Synthesis, structure, and optical properties of CsU2(PO4)3

    NASA Astrophysics Data System (ADS)

    Oh, George N.; Ringe, Emilie; Van Duyne, Richard P.; Ibers, James A.

    2012-01-01

    CsU2(PO4)3 was synthesized in highest yield by the reaction in a fused-silica tube of U, P, and Se in a CsCl flux at 1273 K. It crystallizes with four formula units in space group P21/n of the monoclinic system in a new structure type. The structure of CsU2(PO4)3 is composed of U and Cs atoms coordinated by PO43- units in distorted octahedral arrangements. Each U atom corner shares with six PO43- units. Each Cs atom face shares with one, edge shares with two, and corner shares with three PO43- units. The structure shares some features with the sodium zirconium phosphate structure type. X-ray powder diffraction results demonstrate that the present CsU2(PO4)3 compound crystallizes in a structure different from the previously reported β‧- and γ-CsU2(PO4)3 compounds. CsU2(PO4)3 is highly pleochroic, as demonstrated by single-crystal optical absorption measurements.

  11. 40 CFR 721.9675 - Titanate [Ti6O13 (2-)], di-po-tas-sium.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Titanate , di-po-tas-sium. 721.9675 Section 721.9675 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.9675 Titanate , di-po-tas-sium. (a) Chemical substance and significant new uses subject...

  12. Biocarbon-coated LiFePO4 nucleus nanoparticles enhancing electrochemical performances.

    PubMed

    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.

  13. Study on feed forward neural network convex optimization for LiFePO4 battery parameters

    NASA Astrophysics Data System (ADS)

    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.

  14. [Theoretical and experimental vibrational spectroscopy study of K3Ln(PO4)2 phosphates].

    PubMed

    Benarafa, L; Rghioui, L; Nejjar, R; Saidi Idrissi, M; Knidiri, M; Lorriaux, A; Wallart, F

    2005-01-14

    The monoclinic phosphates with K3Ln(PO4)2 (Ln=rare earth) formula were synthesized. Their infrared and Raman spectra have been reported and analysed. The results of a force field calculation for K3Nd(PO4)2 are presented.

  15. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po) of a cargo tank. (a) The design... cargo tank has no temperature control for the cargo; and (2) The vapor pressure of the cargo results... 46 Shipping 5 2012-10-01 2012-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405...

  16. Eruption of basalt and andesite lava degasses Rn-222 and Po-210

    NASA Astrophysics Data System (ADS)

    Gill, J.; Williams, R.; Bruland, K.

    1985-01-01

    Activities of Rn-222 and Po-210 were measured in a September, 1983, basic andesite lava from Arenal and a November, 1983, basalt from Kilauea, starting three and one days after eruption, respectively. In both cases, in-growth patterns show that all Rn volatalized during eruption. Po degassing also was complete at Kilauea, but only 84 + or - 10 percent at Arenal.

  17. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  18. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  19. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  20. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2010 CFR

    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...

  1. 21 CFR 868.1200 - Indwelling blood oxygen partial pressure (PO2) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  2. Complete genome sequence of the plant pathogen Ralstonia solanacearum strain Po82.

    PubMed

    Xu, Jin; Zheng, Hua-jun; Liu, Lei; Pan, Zhe-chao; Prior, Philippe; Tang, Biao; Xu, Jing-sheng; Zhang, Hao; Tian, Qian; Zhang, Li-qing; Feng, Jie

    2011-08-01

    Ralstonia solanacearum strain Po82, a phylotype IIB/sequevar 4 strain, was found to be pathogenic to both solanaceous plants and banana. Here, we report the complete genome sequence of Po82 and its comparison with seven published R. solanacearum genomes.

  3. Journal of Environmental Radioactivity special issue: international topical conference on Po and radioactive Pb isotopes.

    PubMed

    Holm, Elis; Garcia-Tenorio, Rafael

    2011-05-01

    An international conference on polonium (Po) and radioactive isotopes was held in Seville Spain, 26-28 October 2009 at the Centro Nacional de Aceleradores. It was attended by 138 participants from 38 different countries. The sessions covered all aspects on Po and lead (Pb) such as radiochemistry, terrestrial and marine radioecology, kinetics, sedimentation rates, atmospheric tracers, NORM industries and dose assessment.

  4. Synthesis, characterization and electrical properties of carbon coated LiCoPO4 nanoparticles.

    PubMed

    Kumar, P Ramesh; Venkateswarlu, M; Misra, Manjusri; Mohanty, Amar K; Satyanayana, N

    2011-04-01

    Lithium cobalt phosphate (LiCoPO4) nanoparticles were synthesized using modified polyol process. Shape and size of LiCoPO4 nanoparticles were controlled by using poly (vinylpyrrolidone) (PVP) stabilizer. Coating of carbon over the LiCoPO4 nanoparticles was done using the resin coating process to enhance its conductivity. XRD and FTIR results respectively confirm the crystalline phase and structure of pure and carbon coated LiCoPO4 nanoparticles. SEM-EDX results confirm size and shape and also the presence of carbon over LiCoPO4 nanoparticles. Electrical conductivity of pure and carbon coated LiCoPO4 nanoparticles were evaluated by analyzing the measured impedance data using the win fit software. More than three orders of conductivity enhancement was observed in carbon coated LiCoPO4 nanoparticles when compared to pure ones. Further, transport properties like temperature dependence conductivity, AC conductivity, dielectric constant and electric modulus studies were made to find out the bulk and relaxation properties of LiCoPO4 nanoparticles.

  5. Hexamethylenetetramine assisted hydrothermal synthesis of BiPO4 and its electrochemical properties for supercapacitors

    NASA Astrophysics Data System (ADS)

    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.

  6. Ultrathin carbon nanopainting of LiFePO4 by oxidative surface polymerization of dopamine

    NASA Astrophysics Data System (ADS)

    Ding, Bo; Tang, Wei Chin; Ji, Ge; Ma, Yue; Xiao, Pengfei; Lu, Li; Lee, Jim Yang

    2014-11-01

    The common strategy to address the low electronic conductivity of LiFePO4 is to downsize LiFePO4 and to coat the nanocrystal with conductive carbon film. The major issues with existing carbon coating techniques are thickness and quality control. This paper reports a facile carbon coating method which can provide ultrathin, uniform and fully encapsulating carbon coating on LiFePO4. This coating method capitalizes on the redox chemistry of surface Fe3+ on solvothermally synthesized LiFePO4 nanocrystal, to deposit uniform thin films of polydopamine films. The polymer film is easily carbonized into ultrathin carbon film. The carbon coated LiFePO4 exhibits very high rate performance (143 mAh g-1 at current density of 1700 mA g-1) with excellent capacity retention.

  7. Columnar order in jammed LiFePO4 cathodes: ion transport catastrophe and its mitigation.

    PubMed

    Smith, Kyle C; Mukherjee, Partha P; Fisher, Timothy S

    2012-05-21

    The high-rate, high-capacity potential of LiFePO4-based lithium-ion battery cathodes has motivated numerous experimental and theoretical studies aiming to realize such performance through nano-sizing, tailoring of particle shape through synthesis conditions, and doping. Here, a granular mechanics study of microstructures formed by dense jammed packings of experimentally and theoretically inspired LiFePO4 particle shapes is presented. A strong dependence of the resultant packing structures on particle shapes is observed, in which columnar structures aligned with the [010] direction inhibit diffusion along [010] in anisotropic LiFePO4. Transport limitations are induced by [010] columnar order and lead to catastrophic performance degradation in anisotropic LiFePO4 electrodes. Further, judicious mixing of nanoplatelets with additive nanoparticles can frustrate columnar ordering and thereby enhance the rate capability of LiFePO4 electrodes by nearly an order of magnitude.

  8. First-principles study of Li ion diffusion in LiFePO4

    NASA Astrophysics Data System (ADS)

    Ouyang, Chuying; Shi, Siqi; Wang, Zhaoxiang; Huang, Xuejie; Chen, Liquan

    2004-03-01

    The diffusion mechanism of Li ions in the olivine LiFePO4 is investigated from first-principles calculations. The energy barriers for possible spatial hopping pathways are calculated with the adiabatic trajectory method. The calculations show that the energy barriers running along the c axis are about 0.6, 1.2, and 1.5 eV for LiFePO4, FePO4, and Li0.5FePO4, respectively. However, the other migration pathways have much higher energy barriers resulting in very low probability of Li-ion migration. This means that the diffusion in LiFePO4 is one dimensional. The one-dimensional diffusion behavior has also been shown with full ab initio molecular dynamics simulation, through which the diffusion behavior is directly observed.

  9. Structure and mobility of water confined in AlPO4-54 nanotubes

    NASA Astrophysics Data System (ADS)

    Gavazzoni, Cristina; Giovambattista, Nicolas; Netz, Paulo A.; Barbosa, Marcia C.

    2017-06-01

    We performed molecular dynamics simulations of water confined within AlPO4-54 nanotubes. AlPO4-54 is an artificial material made of AlO4 and of PO4 in tetrahedra arranged in a periodic structure forming pores of approximately 1.3 nm in diameter. This makes AlPO4-54 an excellent candidate for practical applications, such as for water filtration and desalination. In this work, the structural and dynamical properties of the confined water are analyzed for various temperatures and water loadings. We find that the water structure is controlled by the heterogeneity of the nanopore surface with the water molecules located preferentially next to the surface of oxygens of AlPO4-54; consequently, at very low densities, water forms helicoidal structures in string-like arrangements.

  10. Vertical distribution of (226)Ra and (210)Po in agricultural soils in Buyuk Menderes Basin, Turkey.

    PubMed

    Akyil, S; Gurboga, G; Aslani, M A A; Aytas, S

    2008-09-15

    The vertical distribution of (226)Ra and (210)Po was investigated in the cultivated soils of the Buyuk Menderes Basin in Turkey. Five soil cores down to a depth of about 50 cm were taken from each site and divided into strata of 2-3 cm intervals. The samples were analyzed for their (226)Ra and (210)Po activity concentrations using radioanalytical methods. Down-core concentration profiles of (226)Ra and (210)Po in the soil cores from five sites are obtained. The activity concentrations of soil cores range from 80 to 1170 Bq kg(-1) for (226)Ra and from 10 to 870 Bq kg(-1) for (210)Po with the depth. Analysis of the vertical soil profiles indicate that the activity concentrations of (226)Ra and (210)Po for soil strata at all the sites have not extremely changed with depth.

  11. 210Po Log-normal distribution in human urines: Survey from Central Italy people

    PubMed Central

    Sisti, D.; Rocchi, M. B. L.; Meli, M. A.; Desideri, D.

    2009-01-01

    The death in London of the former secret service agent Alexander Livtinenko on 23 November 2006 generally attracted the attention of the public to the rather unknown radionuclide 210Po. This paper presents the results of a monitoring programme of 210Po background levels in the urines of noncontaminated people living in Central Italy (near the Republic of S. Marino). The relationship between age, sex, years of smoking, number of cigarettes per day, and 210Po concentration was also studied. The results indicated that the urinary 210Po concentration follows a surprisingly perfect Log-normal distribution. Log 210Po concentrations were positively correlated to age (p < 0.0001), number of daily smoked cigarettes (p = 0.006), and years of smoking (p = 0.021), and associated to sex (p = 0.019). Consequently, this study provides upper reference limits for each sub-group identified by significantly predictive variables. PMID:19750019

  12. Vapour phase oxidation of toluene over CeAlPO-5 molecular sieves.

    PubMed

    Devika, S; Sundaravel, B; Palanichamy, M; Murugesan, V

    2014-04-01

    Single-site CeAlPO-5 with Al/Ce ratios 25, 50, 75, 100 and 125 were synthesized hydrothermally in fluoride medium. The XRD patterns of CeAlPO-5 exhibited characteristic reflections of AlPO-5. 27Al MAS-NMR of CeAIPO-5(25) showed two unusual peaks at -20.78 and -71.35 ppm due to delocalization of cerium unpaired electron. However, 31P MAS-NMR exhibited the usual characteristic peak similar to that of AlPO-5. Vapour phase oxidation of toluene in air over CeAlPO-5 yielded benzaldehyde with high toluene conversion. The time on stream study established the stability of the catalyst. This catalyst can also be used for the selective oxidation of other alkyl aromatics.

  13. Pnicogen bonded complexes of PO2X (X = F, Cl) with nitrogen bases.

    PubMed

    Alkorta, Ibon; Elguero, José; Del Bene, Janet E

    2013-10-10

    An ab initio MP2/aug'-cc-pVTZ study has been carried out on complexes formed between PO2X (X = F and Cl) as the Lewis acids and a series of nitrogen bases ZN, including NH3, H2C═NH, NH2F, NP, NCH, NCF, NF3, and N2. Binding energies of these complexes vary from -10 to -150 kJ/mol, and P-N distances from 1.88 to 2.72 Å. Complexes ZN:PO2F have stronger P(...)N bonds and shorter P-N distances than the corresponding complexes ZN:PO2Cl. Charge transfer from the N lone pair through the π-hole to the P-X and P-O σ* orbitals leads to stabilization of these complexes, although charge-transfer energies can be evaluated only for complexes with binding energies less than -71 kJ/mol. Complexation of PO2X with the strongest bases leads to P···N bonds with a significant degree of covalency, and P-N distances that approach the P-N distances in the molecules PO2NC and PO2NH2. In these complexes, the PO2X molecules distort from planarity. Changes in (31)P absolute chemical shieldings upon complexation do not correlate with changes in charges on P, although they do correlate with the binding energies of the complexes. EOM-CCSD spin-spin coupling constants (1p)J(P-N) are dominated by the Fermi-contact term, which is an excellent approximation to total J. (1p)J(P-N) values are small at long distances, increase as the distance decreases, but then decrease at short P-N distances. At the shortest distances, values of (1p)J(P-N) approach (1)J(P-N) for the molecules PO2NC and PO2NH2.

  14. Processes controlling the distributions of Cd and PO4 in the ocean

    NASA Astrophysics Data System (ADS)

    Quay, Paul; Cullen, Jay; Landing, William; Morton, Peter

    2015-06-01

    Depth profiles of dissolved Cd and PO4 from a global data compilation were used to derive the Cd/P of particles exported from the surface layer, and the results indicate lowest values in the North Atlantic (0.17 ± 0.05), highest in the Southern (0.56 ± 0.24), and intermediate in the South Indian (0.31 ± 0.14) and North Pacific (0.36 ± 0.08) Ocean basins. The Cd/P of exported particles in high nutrient-low chlorophyll (HNLC) regions is twice that for particles exported in non-HNLC regions as is the fractionation effect during biological uptake of Cd and PO4, and these trends primarily determine the spatial trends of dissolved Cd/PO4 observed in the surface ocean. In deep waters the lowest dissolved Cd/PO4 of 0.23 ± 0.07 is found in the North Atlantic Ocean and the result primarily of low Cd/PO4 of North Atlantic Deep Water (0.23). In contrast, deep waters in the Southern Ocean have significantly higher dissolved Cd/PO4 (0.30 ± 0.06), which is a result of the Cd/PO4 of upwelled deep water from the South Pacific and South Indian (0.28) and the high Cd/P of degrading particles. A multibox model that accounts for the impacts of particle degradation and thermohaline circulation in the deep sea yields dissolved Cd and PO4 interbasin trends close to observations. Model experiments illustrate the dependence of the dissolved Cd/PO4 of the deep sea on the extent of HNLC conditions in the Southern Ocean and the impact on reconstructing paleo PO4 concentrations from a Cd proxy.

  15. Solvothermal synthesis of Ag hybrid BiPO4 heterostructures with enhanced photodegradation activity and stability.

    PubMed

    Huang, Chang-Wei; Wu, Mei-Yao; Lin, Yang-Wei

    2017-03-15

    In this study, Ag hybrid BiPO4 (Ag/BiPO4) heterostructures were synthesized using a solvothermal method. The morphologies and optical properties of the Ag/BiPO4 heterostructures were drastically different from those of BiPO4 and were highly dependent on the AgNO3:BiPO4 weight percent during the synthesis. The three formulated heterostructures were evaluated for their photocatalytic degradation of methylene blue (MB) under UV light illumination; the 0.5%Ag/BiPO4 heterostructure was observed to result in 99% degradation of MB within 60min, a remarkably higher level of photodegradation activity than the levels caused by TiO2 and BiPO4. Furthermore, even after use for five cycles of MB degradation, the 0.5%Ag/BiPO4 heterostructure showed no observable loss in photodegradation activity and no change in XRD patterns, demonstrating its chemical and structural stability. According to the results of a systematic experimental investigation, the enhanced photodegradation activity of this Ag/BiPO4 heterostructure could be ascribed to the high position of its valence band and the highly efficient separation of photogenerated electrons and holes. Moreover, hydroxyl radicals and holes were found to be the major reactive species. Successful photodegradation of standard dye solutions, including acid blue 1, methyl orange, fast green, rhodamine B, rhodamine 6G, and MB, in real water samples was demonstrated with the 0.5%Ag/BiPO4 heterostructure, providing clear evidence of its utility for treating waste water containing organic dyes.

  16. Exploring the connection between 210Po and organic matter in the northwestern Mediterranean

    NASA Astrophysics Data System (ADS)

    Stewart, Gillian; Kirk Cochran, J.; Xue, Jianhong; Lee, Cindy; Wakeham, Stuart G.; Armstrong, Robert A.; Masqué, Pere; Carlos Miquel, Juan

    2007-03-01

    The disequilibrium between 210Po and its grandparent 210Pb has been proposed as a tracer of the vertical flux of sinking particulate organic matter in the ocean. The mechanism of association between 210Po and organic matter is, however, still unclear. To investigate this association we measured trace metals, minerals, organic carbon, nitrogen, and the natural radioisotopes 234Th, 228Th, 210Po, and 210Pb in sinking particles collected in sediment traps at 200 m in the northwestern Mediterranean. Pigments, fatty acids, and amino acids were used to identify the types and sources of particulate organic matter. Multivariate analyses were used to determine which components of sinking particulate matter are traced by 210Po and/or by the 210Po/ 210Pb ratio. Statistical analysis of the results indicates that the distribution of polonium in sinking marine particles is influenced by fresh phytoplankton-derived, nitrogen-rich organic matter as well as sulfur-containing amino acids. These findings are consistent with previous laboratory observations that the distribution of 210Po in biota parallels the distributions of both sulfur and protein, and indicate that these associations persist as material sinks through the water column. While this research generally supports the use of 210Po as a specific tracer of the flux of organic matter, the signals traced by 210Po/ 210Pb and 234Th/ 238U are not as distinct in the field as in laboratory experiments. Further work is needed to determine more precisely what 210Po/ 210Pb traces in order to increase the correspondence of 210Po/ 210Pb measurements to biogeochemically important rates and quantities.

  17. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions.

  18. Microwave spectroscopic detection of a transient phosphorus-bearing molecule, H3PO

    NASA Astrophysics Data System (ADS)

    Ahmad, Imtiaz K.; Ozeki, Hiroyuki; Saito, Shuji

    1999-01-01

    The microwave spectrum of the transient phosphine oxide, H3PO, was detected in the gas phase for the first time using a source-modulated spectrometer. The H3PO molecule was generated in a free space cell by a dc glow discharge of a mixture of PH3, CO2, and H2 gases and the corresponding spectral lines for each rotational transition of H3PO formed a pattern clearly indicative of a symmetric top molecule. Isotopomers of H3PO, i.e., H3P18O and D3PO were also produced; H3P18O in the same fashion as for H3PO, and D3PO, in a mixture of D2 and CO2 gases passing over red phosphorus grains. In total, 54 spectral lines of H3PO, 55 lines of H3P18O, and 61 lines of D3PO were measured for the fine structure of rotational transitions, J=2-1 to 12-11. The rotational constant, B0, and centrifugal constants, DJ, DJK, and HKJ were ascertained by a least squares analysis of the measured frequencies for each of the species. Using the rotational constants of the three isotopic species, the following r0 structure was determined: r0 (PO)=1.4763 Å, r0(PH)=1.4406 Å, and ∠HPO=114.26°. The value of each structural parameter deviates significantly from the most recent results predicted by ab initio calculations.

  19. 78 FR 49470 - Adrian Jesus Reyna, Inmate Number #80629-280, FCI Bastrop, Federal Correctional Institution, P.O...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-14

    ... Correctional Institution, P.O. Box 1010, Bastrop, TX 78602; Order Denying Export Privileges On January 27, 2012... Institution, P.O. Box 1010, Bastrop, TX 78602, and when acting for or on behalf of Reyna, his...

  20. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    PubMed

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

  1. Implementing DOIs for Oceanographic Satellite Data at PO.DAAC

    NASA Astrophysics Data System (ADS)

    Hausman, J.; Tauer, E.; Chung, N.; Chen, C.; Moroni, D. F.

    2013-12-01

    The Physical Oceanographic Distributed Active Archive Center (PO.DAAC) is NASA's archive for physical oceanographic satellite data. It distributes over 500 datasets from gravity, ocean wind, sea surface topography, sea ice, ocean currents, salinity, and sea surface temperature satellite missions. A dataset is a collection of granules/files that share the same mission/project, versioning, processing level, spatial, and temporal characteristics. The large number of datasets is partially due to the number of satellite missions, but mostly because a single satellite mission typically has multiple versions or even temporal and spatial resolutions of data. As a result, a user might mistake one dataset for a different dataset from the same satellite mission. Due to the PO.DAAC'S vast variety and volume of data and growing requirements to report dataset usage, it has begun implementing DOIs for the datasets it archives and distributes. However, this was not as simple as registering a name for a DOI and providing a URL. Before implementing DOIs multiple questions needed to be answered. What are the sponsor and end-user expectations regarding DOIs? At what level does a DOI get assigned (dataset, file/granule)? Do all data get a DOI, or only selected data? How do we create a DOI? How do we create landing pages and manage them? What changes need to be made to the data archive, life cycle policy and web portal to accommodate DOIs? What if the data also exists at another archive and a DOI already exists? How is a DOI included if the data were obtained via a subsetting tool? How does a researcher or author provide a unique, definitive reference (standard citation) for a given dataset? This presentation will discuss how these questions were answered through changes in policy, process, and system design. Implementing DOIs is not a trivial undertaking, but as DOIs are rapidly becoming the de facto approach, it is worth the effort. Researchers have historically referenced the source

  2. Catalytic effect of a second H3PO2 in the mechanism of stabilisation of the unstable pyramidal tautomer of H3PO2 coordinated at [Mo3S4M'] clusters (M' = Ni, Pd).

    PubMed

    Algarra, Andrés G; Basallote, Manuel G; Fernández-Trujillo, María J; Hernández-Molina, Rita; Safont, Vicent S

    2007-08-07

    Kinetic and DFT studies indicate that the stabilization of a single pyramidal H(3)PO(2) molecule at the M' site of [Mo(3)S(4)M'] clusters requires the participation of two tetrahedral H(3)PO(2) molecules, the role of the second one being assisting tautomerization of a previously coordinated tetrahedral H(3)PO(2).

  3. Unlocking the energy capabilities of micron-sized LiFePO4

    NASA Astrophysics Data System (ADS)

    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

    2015-08-01

    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.

  4. On a framework for generating PoD curves assisted by numerical simulations

    NASA Astrophysics Data System (ADS)

    Subair, S. Mohamed; Agrawal, Shweta; Balasubramaniam, Krishnan; Rajagopal, Prabhu; Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar

    2015-03-01

    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.

  5. Ag3PO4 nanoparticle-decorated Ni/C nanocapsules with tunable electromagnetic absorption properties

    NASA Astrophysics Data System (ADS)

    Cui, Caiyun; Zhou, Pingping; Liu, Xianguo; Or, Siu Wing; Ho, S. L.

    2017-05-01

    Core/shell-structured nickel/carbon (Ni/C) nanocapsules with Ag3PO4 nanoparticle decoration (Ag3PO4@Ni/C) are prepared by an arc-discharge process and an ion-exchange process. The Ag3PO4@Ni/C nanocapsules show a clear decoration of Ag3PO4 nanoparticles of 4-20 nm diameter on the C shell of the Ni/C nanocapsules of ˜60 nm diameter. The amount of Ag3PO4 nanoparticles that can be decorated on the Ni/C nanocapsules depends on the volume of Na2HPO4 reactant used in the ion-exchange process. The Ag3PO4@Ni/C nanocapsules demonstrate interestingly high and tunable electromagnetic absorption properties with different amounts of Ag3PO4 nanoparticle decoration in the paraffin-bonded composites over the 2-18 GHz microwave range. The nanocapsules prepared with 100 ml Na2HPO4 exhibit much enhanced dielectric and magnetic losses for an improved electromagnetic impedance match. These result in a large reflection loss (RL) of -31.4 dB at 12.3 GHz for a small absorber thickness of 2.6 mm in conjunction with a very wide effective absorption bandwidth (for RL<-10 dB) of 14 GHz (4-18 GHz) at a wide absorber thickness range of 1.4-5.0 mm.

  6. Ultralong Lifespan and Ultrafast Li Storage: Single-Crystal LiFePO4 Nanomeshes.

    PubMed

    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.

  7. Unlocking the energy capabilities of micron-sized LiFePO4.

    PubMed

    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.

  8. Shape controlled hydrothermal synthesis and characterization of LiFePO4 for lithium ion batteries.

    PubMed

    Yu, Yang; Li, Qianwen; Ma, Yanmei; Zhang, Xing; Zhu, Yongchun; Qian, Yitai

    2013-02-01

    Various LiFePO4 microstructures were synthesized via hydrothermal or solvothermal routes using different additives. In an aqueous solution, LiFePO4 spindles whose length was about 2 microm were obtained with the assistance of polyvinyl pyrrolidone (PVP). As PVP and P2O7(4-) added in water, ellipsoidal LiFePO4 particles which composed of nanoparticles around 100 nm in diameter were obtained. If the additive was cetyltrimethyl ammonium bromide (CTAB), sheet-like LiFePO4 crystals with the width of 100 nm were prepared. In the mixed solvents of water together with ethanol or acetylacetone, when adding CTAB or polyethylene glycol (20000), LiFePO4 plates or nanoparticles were obtained. The ellipsoidal LiFePO4 had the best electrochemical properties among all these products. It is found that the annealed samples were significantly better than the corresponding unannealed ones. Take the ellipsoidal LiFePO4 for example, the initial discharge capacity of annealed (161 mAh/g) was much higher than the unannealed ones (85 mAh/g) at 0.1 C and the former cell still could deliver a capacity of 143 mAh/g after 30 cycles.

  9. Unlocking the energy capabilities of micron-sized LiFePO4

    PubMed Central

    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

    2015-01-01

    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. PMID:26235395

  10. Electrochemical performance of Sol-Gel synthesized LiFePO{sub 4} in lithium batteries

    SciTech Connect

    Hu, Yaoqin; Doeff, Marca M.; Kostecki, Robert; Finones, Rita

    2003-06-16

    LiFePO{sub 4}, Li{sub 0.98}Mg{sub 0.01}FePO{sub 4}, and Li{sub 0.96}Ti{sub 0.01}FePO{sub 4} were synthesized via a sol-gel method, using a variety of processing conditions. For comparison, LiFePO{sub 4} was also synthesized from iron acetate by a solid state method. The electrochemical performance of these materials in lithium cells was evaluated and correlated to mean primary particle size and residual carbon structure in the LiFePO{sub 4} samples, as determined by Raman microprobe spectroscopy. For materials with mean agglomerate sizes below 20 {micro}m, an association between structure and crystallinity of the residual carbon and improved utilization was observed. Addition of small amounts of organic compounds or polymers during processing results in carbon coatings with higher graphitization ratios and better electronic properties on the LiFePO{sub 4} samples and improves cell performance in some cases, even though total carbon contents remain very low (<2%). In contrast, no performance enhancement was seen for samples doped with Mg or Ti. These results suggest that it should be possible to design high power LiFePO{sub 4} electrodes without unduly compromising energy density by optimizing the carbon coating on the particles.

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

    PubMed

    Lee, Hsiu-wei; Wang, Jeng-Jong

    2013-03-01

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

  12. Visible light assisted degradation of organic dye using Ag{sub 3}PO{sub 4}

    SciTech Connect

    Dhanabal, R.; Bose, A. Chandra; Velmathi, S.

    2015-06-24

    The study of visible light photodegradation of organic dye Methylene Blue (MB) have been investigated using silver phosphate (Ag{sub 3}PO{sub 4}) as a photocatalyst which is good efficient material for photocatalytic reaction. The simple ion-exchange method is used to prepare Ag{sub 3}PO{sub 4}. The structure of the material have been confirmed using X-ray diffraction which shows cubic structure of Ag{sub 3}PO{sub 4}. The functional group of the Ag{sub 3}PO{sub 4} has been verified by Fourier transform infrared spectroscopy. The bandgap of Ag{sub 3}PO{sub 4} is calculated using kubelka-munk function from the ultra violet-visible diffuse reflectance spectroscopy, the absorption of Ag{sub 3}PO{sub 4} starts from 470 nm. Under simulated visible light irradiation, Ag{sub 3}PO{sub 4} catalyst exhibits good catalytic ability for degrading MB dye.

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

    PubMed

    Długosz-Lisiecka, Magdalena; Wróbel, Justyna

    2014-12-01

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

  14. On a framework for generating PoD curves assisted by numerical simulations

    SciTech Connect

    Subair, S. Mohamed Agrawal, Shweta Balasubramaniam, Krishnan Rajagopal, Prabhu; Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar

    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.

  15. Hollow GdPO4:Eu3+ microspheres: Luminescent properties and applications as drug carrier

    NASA Astrophysics Data System (ADS)

    Tang, Yanxia; Mei, Rui; Yang, Shaokun; Tang, Hongxia; Yin, Wenzhong; Xu, Yongchun; Gao, Yaping

    2016-04-01

    GdPO4:Eu3+ samples were synthesized by a hydrothermal process using melamine formaldehyde (MF) as template. The X-ray diffraction (XRD) patterns and the Fourier Transform Infrared (FTIR) spectrum suggested that GdPO4:Eu3+ has a hexagonal phase. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that the obtained GdPO4:Eu3+ are hollow microspheres with diameters in the range of 1-1.5 μm. Under the excitation at 245 nm, hexagonal GdPO4:Eu3+ hollow microspheres showed emission bands originating from the 5D0 → 7FJ (J = 1, 2, 3 and 4) transitions of Eu3+. The drug release properties of hexagonal GdPO4:Eu3+ hollow microspheres were exhibited by the doxorubicin hydrochloride (DOX) release test. The biocompatibility of hexagonal GdPO4:Eu3+ hollow microsphere was tested by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicated that hollow GdPO4:Eu3+ microspheres have potential applications in biomedicine fields.

  16. Kinetic behavior of LiFeMgPO 4 cathode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Hong, Jian; Wang, Chunsheng; Kasavajjula, Uday

    LiFe 0.9Mg 0.1PO 4 material was prepared by mechanical milling method, followed by heat treatment. The equilibrium potential-composition isotherm of LiFe 0.9Mg 0.1PO 4 and charge-discharge kinetics of LiFe 0.9Mg 0.1PO 4 were measured using galvanostatic intermittent titration technique (GITT), potential-step chronoamperometry (PSCA), and electrochemical impedance spectroscopy (EIS). The rate performance of the cathode is controlled by the charge-transfer kinetics, electronic conductivity, Li-ion diffusion capability, and phase transformation rate. Since LiFe 0.9Mg 0.1PO 4 has a fast charge-transfer reaction and high electronic and ionic diffusivity, the phase transformation between LiFe 0.9Mg 0.1PO 4 and Li 0.1Fe 0.9Mg 0.1PO 4 begins to play a more important role in the charge-discharge process, as is evident by an inductive loop induced by the phase transformation in the low frequency region of EIS. The phase purity and morphology of LiFe 0.9Mg 0.1PO 4 were also observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  17. New Media E/PO: Building a Digital Astronomy Community

    NASA Astrophysics Data System (ADS)

    Gay, Pamela L.

    2008-05-01

    Today's communications landscape is rich with new technologies. Cell phones and laptops are the constant companions of content consumers, and as we plan tomorrow's Education and Public Outreach programs, we need to consider how to most effectively utilize these technologies with their new, dynamic content possibilities - We need to use New Media. The field of New Media includes dynamic content sites such as: blogs, pod/vodcasts, Flickr, Facebook, Ustream, Twitter, and Second Life. The first part of this talk will summarize what New Media is available in the field of astronomy. All new media technologies have one thing in common: Users can easily create and input their own content and/or comments. These new media users and content contributors can just as easily be professional researchers, E/PO professionals, amateur astronomers, stay-at-home parents, and school kids. All are welcome in the online community, and today, all voices are digitally joined in the cacophony of astronomy new media content. This rich diversity supports many opportunities for learning, mentoring, content distribution, and discussion of ideas (including the debunking of bad ideas). In the second half of this talk, ways to use new media to build a community that shares, promotes, and comments on content is discussed, and techniques for dealing with the high flux of content are outlined. Also covered are the considerations that need to be made to make content as broadly accessible as possible.

  18. EduBites: Cliffs Notes for E/PO

    NASA Astrophysics Data System (ADS)

    Brinkworth, Carolyn; Bartolone, L.; Wenger, M.; Martin, A.; Nichols-Yehling, M.; Hurt, R. L.; Squires, G. K.

    2013-01-01

    We present a new resource for the astronomy education community, with the goal of improving our community’s knowledge and understanding of the educational research papers relevant to our work. EduBites is a searchable database of summaries of peer-reviewed education papers, written by astronomy educators and posted for the entire community to use. While we are all aware that we should be basing our E/PO work on a solid research foundation, many people in the community are pushed for time when it comes to staying on top of the educational literature. EduBites aims to reduce that workload for the benefit of the entire community. Our database is small, but growing, and will ultimately tackle papers across the whole of the astronomy education spectrum, including formal and informal education, outreach, grades K-16, pedagogy, evaluation, and many other topics. We are keen to hear from anyone on the community who would be interested in joining our review team, and welcome feedback on the EduBites user experience.

  19. Midwives in China: 'jie sheng po' to 'zhu chan shi'.

    PubMed

    Harris, Amanda; Belton, Suzanne; Barclay, Lesley; Fenwick, Jenny

    2009-04-01

    We explore the position of midwifery in contemporary China, and draw on fieldwork conducted in Shanxi and Sichuan Provinces during 2005 and 2006, the available literature in English and to a lesser extent in Mandarin. We also explore the historical antecedents to the present-day professional status, practices and position within the health-care system of midwifery in China. We consider the effect on midwifery of the place of biomedicine in the modernising project of the post-reform State, the shift of birth from the private to the public domain, the rise of the medical profession, the medicalisation of birth and the increasing use of technology, and trace changes in the nature of relations between midwives, doctors and the State from Imperial China to the present day. In particular, we examine the changes that have occurred as midwifery has moved from the arena of the lay practitioner ('jie sheng po') to the professional ('zhu chan shi'). We draw out and critique some ways that midwives act to differentiate themselves and lay claim to a variant body of practice-based knowledge, yet question the capacity of midwifery in China today to assert, in any substantial way, a professional identity that distinguishes it from medical obstetric practice.

  20. Magnetic structure and magnetocalorics of GdPO4

    DOE PAGES

    Palacios, E.; Rodriguez-Velamazsn, J. A.; Evangelisti, Marco; ...

    2014-12-12

    The magnetic ordering structure of GdPO4 is determined at T = 60 mK by diffraction of hot neutrons with wavelength = 0.4696 Å. It corresponds to a non-collinear antiferromagnetic arrangement of the Gd moments with propagation vector k = (1/2, 0, 1/2). This arrangement is found to minimize the dipole-dipole interaction and the crystal field anisotropy energy, the magnetic superexchange being much smaller. The intensity of the magnetic reflections decreases with increasing temperature and vanishes at T ≈ 0.8 K, in agreement with the magnetic ordering temperature TN = 0.77 K, as reported in previous works based on heat capacitymore » and magnetic susceptibility measurements. The magnetocaloric parameters have been determined from heat capacity data at constant applied fields up to 7 T, as well as from isothermal magnetization data. Lastly, the magnetocaloric effect, for a field change ΔB = 0 – 7T, reaches –ΔST = 375.8mJ / cm3K–1 at T = 2.1 K, largely exceeding the maximum values reported to date for Gd-based magnetic refrigerants.« less

  1. Genetic structure of the human population in the Po delta

    PubMed Central

    Beretta, M.; Mazzetti, P.; Mamolini, E.; Gavina, R.; Barale, R.; Vullo, C.; Ravani, A.; Franze, A.; Sapigni, T.; Soracco, E.; Davi, D.; Ricci, N.; Cappello, N.; Rendine, S.; Piazza, A.; Barrai, I.

    1989-01-01

    The genetic structure of the population of Ferrara Province in the Po delta in Italy was investigated using χ2 analysis, kinship analysis, analysis of correspondences, and geographical mapping of principal components of gene frequencies, χ2 Analysis tests for Hardy-Weinberg equilibrium and for heterogeneity of gene and phenotype frequencies; kinship analysis tests for association between indicators of genetic and geographic proximity; analysis of correspondences relates localities and genetic systems in an eigenvectorial space; and geographic mapping displays the principal components of gene frequencies in the real space. In 1,364 adults in 26 residential units, seven presumably neutral isoenzyme systems were typed; ACP1 ESD, GLO I, GPT, PGD, PGM1 and PGP. It was found that average kinship for these neutral systems is correlated with geographic distance in this small area, but not as strongly as kinship for beta-thalassemia. A north-south gradient was observed for ESD. Analysis of correspondences indicated GPT, PGM1, and GLO I as the systems contributing most to differentiation within the province. The maps obtained from principal components of gene frequencies were consistent with the migrational history of the area. ImagesFigure 4Figure 5Figure 6Figure 7Figure 8 PMID:2741951

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

    PubMed

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

    2011-10-01

    Recent researches revealed the exciting application of (210)Po in tracing carbon and nitrogen cycling in the coral reef system. In order to quantify the recycling of particulate organic nitrogen (PON), both (210)Po and (210)Pb were examined at both high and low tides in the Zhubi Coral Reef lagoon, the South China Sea. Unusually, much higher (210)Po activities and (210)Po/(210)Pb ratios, in comparison with those found in the open seawater and the lagoon subsurface water, showed additional input of (210)Po besides production from in situ(210)Pb in the lagoon surface water. Statistical analysis identified that the reef flat seawater was the additional (210)Po source. Based on a mass balance model, the input rates of (210)Po varied from 0.04 Bq m(-3)year(-1) to 8.41 Bq m(-3)year(-1). On average, the additional (210)Po contributed more than 60% of the total (210)Po. The particulate (210)Po significantly correlated with the concentrations of PON, indicating that diffusion of (210)Po from sediment could be used to quantify the recycling of nitrogen. The average input rate of nitrogen was 16 mmol m(-3)year(-1), which can support up to 11% of the primary production rate. These results suggested that the unusual behavior of (210)Po could provide new insight into the nitrogen recycling in the coral reef system. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. LiFePO4 nanoparticles encapsulated in graphene nanoshells for high-performance lithium-ion battery cathodes.

    PubMed

    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.

  4. Identifying the Structure of the Intermediate, Li2/3CoPO4, Formed during Electrochemical Cycling of LiCoPO4

    DOE PAGES

    Strobridge, Fiona C.; Clément, Raphaële J.; Leskes, Michal; ...

    2014-11-03

    In situ synchrotron diffraction measurements and subsequent Rietveld refinements are used to show that the high energy density cathode material LiCoPO4 (space group Pnma) undergoes two distinct two-phase reactions upon charge and discharge, both occurring via an intermediate Li2/3(Co2+)2/3(Co3+)1/3PO4 phase. Two resonances are observed for Li2/3CoPO4 with intensity ratios of 2:1 and 1:1 in the 31P and 7Li NMR spectra, respectively. An ordering of Co2+/Co3+ oxidation states is proposed within a (a × 3b × c) supercell, and Li+/vacancy ordering is investigated using experimental NMR data in combination with first-principles solid-state DFT calculations. In the lowest energy configuration, both themore » Co3+ ions and Li vacancies are found to order along the b-axis. Two other low energy Li+/vacancy ordering schemes are found only 5 meV per formula unit higher in energy. All three configurations lie below the LiCoPO4–CoPO4 convex hull and they may be readily interconverted by Li+ hops along the b-direction.« less

  5. Identifying the Structure of the Intermediate, Li2/3CoPO4, Formed during Electrochemical Cycling of LiCoPO4

    PubMed Central

    2014-01-01

    In situ synchrotron diffraction measurements and subsequent Rietveld refinements are used to show that the high energy density cathode material LiCoPO4 (space group Pnma) undergoes two distinct two-phase reactions upon charge and discharge, both occurring via an intermediate Li2/3(Co2+)2/3(Co3+)1/3PO4 phase. Two resonances are observed for Li2/3CoPO4 with intensity ratios of 2:1 and 1:1 in the 31P and 7Li NMR spectra, respectively. An ordering of Co2+/Co3+ oxidation states is proposed within a (a × 3b × c) supercell, and Li+/vacancy ordering is investigated using experimental NMR data in combination with first-principles solid-state DFT calculations. In the lowest energy configuration, both the Co3+ ions and Li vacancies are found to order along the b-axis. Two other low energy Li+/vacancy ordering schemes are found only 5 meV per formula unit higher in energy. All three configurations lie below the LiCoPO4–CoPO4 convex hull and they may be readily interconverted by Li+ hops along the b-direction. PMID:25960604

  6. Variation of local magnetic environments in olivine-type compounds: Na0.7FePO4 and FePO4

    NASA Astrophysics Data System (ADS)

    Sugiyama, Jun; Nozaki, Hiroshi; Harada, Masashi; Higuchi, Yuki; Brewer, Jess H.; Ansaldo, Eduardo J.; Kobayashi, Genki; Kanno, Ryoji

    2014-07-01

    To investigate the microscopic magnetic nature of phospho-olivines, we have measured positive muon-spin rotation and relaxation (μ+SR) spectra for NaxFePO4 and FePO4, using powder samples in the temperature range between 2 and 200 K. For Na0.7FePO4, μ+SR measurements under zero external field (ZF) showed the appearance of static magnetic order below TN˜61 K, at which the susceptibility χ (T) exhibits a sharp maximum due to an antiferromagnetic (AF) transition. The wide distribution found for the internal magnetic field (Hint) was reasonably explained by the formation of AF order with the spread in Hint due to a random distribution of Na vacancies. On the other hand, the ZF spectra for FePO4 suggested the formation of the canted AF order below TN=113 K, as proposed by neutron diffraction (ND), but the ratio between the y and x components of the ordered moment (My/Mx) was determined as 0.6 by μ+SR, whereas 0.22 was measured by ND, probably indicating anisotropic spin fluctuations in FePO4.

  7. Radiation resistance of LaPO4 (monazite structure) and YbPO4 (zircon structure) from data of computer simulation

    NASA Astrophysics Data System (ADS)

    Grechanovsky, A. E.; Eremin, N. N.; Urusov, V. S.

    2013-09-01

    The radiation resistance of the monazite LaPO4 and the compound YbPO4 (zircon structure type) has been investigated using the computer simulation. The number of Frenkel pairs, which are formed in the structure of these minerals after the passage of a primary knock-on thorium atom with an energy of 30 keV, has been calculated by the molecular dynamics method. The formation of Frenkel pairs and their recombination in the motion of recoil nuclei in the structure of the studied minerals have been discussed. It has been shown that the probability of the "survival" of Frenkel pairs in the LaPO4 monazite is significantly lower than in the YbPO4 compound. The tendency of these minerals toward amorphization under radiation damage has been described numerically. The obtained results have demonstrated that one of the main factors determining the radiation resistance of orthophosphates LnPO4 is the type of crystal structure, and the compounds with the monazite structure are more radiation resistant than the compounds with the zircon structure.

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

    SciTech Connect

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

    2013-09-01

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

  9. Kinetics of non-equilibrium lithium incorporation in LiFePO4

    NASA Astrophysics Data System (ADS)

    Malik, Rahul; Zhou, Fei; Ceder, G.

    2011-08-01

    Lithium-ion batteries are a key technology for multiple clean energy applications. Their energy and power density is largely determined by the cathode materials, which store Li by incorporation into their crystal structure. Most commercialized cathode materials, such as LiCoO2 (ref. ), LiMn2O4 (ref. ), Li(Ni,Co,Al)O2 or Li(Ni,Co,Mn)O2 (ref. ), form solid solutions over a large concentration range, with occasional weak first-order transitions as a result of ordering of Li or electronic effects. An exception is LiFePO4, which stores Li through a two-phase transformation between FePO4 and LiFePO4 (refs , , , ). Notwithstanding having to overcome extra kinetic barriers, such as nucleation of the second phase and growth through interface motion, the observed rate capability of LiFePO4 has become remarkably high. In particular, once transport limitations at the electrode level are removed through carbon addition and particle size reduction, the innate rate capability of LiFePO4 is revealed to be very high. We demonstrate that the reason LiFePO4 functions as a cathode at reasonable rate is the availability of a single-phase transformation path at very low overpotential, allowing the system to bypass nucleation and growth of a second phase. The LixFePO4 system is an example where the kinetic transformation path between LiFePO4 and FePO4 is fundamentally different from the path deduced from its equilibrium phase diagram.

  10. Morphology and conductivity study of solid electrolyte Li{sub 3}PO{sub 4}

    SciTech Connect

    Prayogi, Lugas Dwi Faisal, Muhamad; Kartini, Evvy Honggowiranto, Wagiyo; Supardi

    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.

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

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hoon; Kim, Guebuem

    2014-12-01

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

  12. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    SciTech Connect

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; Serafin, Alessandro; Carrington, Antony; 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.

  13. [100]-Oriented LiFePO4 Nanoflakes toward High Rate Li-Ion Battery Cathode.

    PubMed

    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.

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

    PubMed

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

    2013-09-01

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

  15. Study of phase relationships in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system. Phase diagram and thermal characteristics of phases

    SciTech Connect

    Matraszek, Aleksandra

    2013-07-15

    A diagram representing phase relationships in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} phosphate system has been developed on the basis of results obtained by thermal analysis (DTA/DSC/TGA) and X-ray diffraction (XRD) methods. One intermediate compound with the formula Sr{sub 3}Ce(PO{sub 4}){sub 3} occurs in the Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system at temperatures exceeding 1045 °C. The compound has a eulytite structure with the following structural parameters: a=b=c=10.1655(8) Å, α=β=γ=90.00°, V=1050.46(6) Å{sup 3}. It's melting point exceeds 1950 °C. A limited solid solution exists in the system, which possesses the structure of a low-temperature form of Sr{sub 3}(PO{sub 4}){sub 2}. At 1000 °C the maximal concentration of CePO{sub 4} in the solid solution is below 20 mol%. The solid solution phase field narrows with increased temperature. There is a eutectic point in the (Sr{sub 3}(PO{sub 4}){sub 2}+Sr{sub 3}Ce(PO{sub 4}){sub 3}) phase field at 1765 °C and 15 mol% of CePO{sub 4}. The melting temperature of Sr{sub 3}(PO{sub 4}){sub 2} is 1882±15 °C. - Graphical abstract: The phase diagram of Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system showing the stability ranges of limited solid solution and Sr{sub 3}Ce(PO{sub 4}){sub 3} phases. - Highlights: • Sr{sub 3}(PO{sub 4}){sub 2} melts at 1882 °C. • Phase diagram of Sr{sub 3}(PO{sub 4}){sub 2}–CePO{sub 4} system has been proposed. • Limited solid solution of CePO{sub 4} in Sr{sub 3}(PO{sub 4}){sub 2} forms in the system. • The Sr{sub 3}Ce(PO{sub 4}){sub 2} phosphate is stable at temperatures above 1045 °C.

  16. Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO{sub 4}/FePO{sub 4} electrode

    SciTech Connect

    Tokuda, Kazuya; Kawaguchi, Tomoya; Ichitsubo, Tetsu; Matsubara, Eiichiro; Fukuda, Katsutoshi

    2014-07-01

    LiFePO{sub 4} 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 LiFePO{sub 4} phase to the FePO{sub 4} phase during delithiation by simultaneous in situ XRD and XANES measurements in an LiFePO{sub 4}/FePO{sub 4} electrode. The ratio of structure change to valence change clearly indicates that the phase separation from LiFePO{sub 4} to FePO{sub 4} 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.

  17. Quantifying the Bioporosity of Recent Po Delta Sediments

    NASA Astrophysics Data System (ADS)

    Locat, J.; Levesque, M.; Lee, H.; Leroueil, S.

    2004-12-01

    As part of project EuroSTRATAFORM, a series of shallow box-core samples were collected near the Po Delta in Italy. They reveal the presence of intense biogenic structures that are believed to have a strong influence on the physical properties of the sediments as they introduce another class of porosity: bioporosity (volume of biopores/total volume of the sample). Therefore, it required that they be evaluated and quantified. Two of these cores were selected for a detailed analysis. This was done primarily using 3D CATSCAN imagery (tomographic intensity) and direct physico-chemical measurements. The tomographic intensity is a complex value controlled by many factors such as the grain size, mineralogy, consolidation, water content and porosity. Two methods were used to quantify the bioporosity: an absolute and a relative bioporosity measurements both based on the use of the tomographic intensity. The relative method takes into account the variability of the sediment densities along the core, whereas the absolute method fixes the tomographic intensity based on the mean density of sediment for the whole core. Because of the evolution of the geometry of the biogenic structures, it became clear that the relative method was much better. Results have shown that the bioporosity could reach values as high a 40% and could account for more than half of the total porosity. These results suggest that significant bias on water content measurement of the matrix thus influencing estimation of physical properties like plastic and liquid limits and the liquidity index via the bias on the matrix water content measurement.

  18. Characteristics of brown carbon in the urban Po Valley atmosphere

    NASA Astrophysics Data System (ADS)

    Costabile, Francesca; Gilardoni, Stefania; Barnaba, Francesca; Di Ianni, Antonio; Di Liberto, Luca; Dionisi, Davide; Manigrasso, Maurizio; Paglione, Marco; Poluzzi, Vanes; Rinaldi, Matteo; Facchini, Maria Cristina; Gobbi, Gian Paolo

    2017-01-01

    We investigate optical-microphysical-chemical properties of brown carbon (BrC) in the urban ambient atmosphere of the Po Valley. In situ ground measurements of aerosol spectral optical properties, PM1 chemical composition (HR-ToF-AMS), and particle size distributions were carried out in Bologna. BrC was identified through its wavelength dependence of light absorption at visible wavelengths, as indicated by the absorption Ångström exponent (AAE). We found that BrC occurs in particles with a narrow monomodal size distribution peaking in the droplet mode, enriched in ammonium nitrate and poor in black carbon (BC), with a strong dependance on OA-to-BC ratios, and SSA530 of 0.98 ± 0.01. We demonstrate that specific complex refractive index values (k530 = 0.017 ± 0.001) are necessary in addition to a proper particle size range to match the large AAEs measured for this BrC (AAE467 - 660 = 3.2 ± 0.9 with values up to 5.3). In terms of consistency of these findings with literature, this study i. provides experimental evidence of the size distribution of BrC associated with the formation of secondary aerosol;ii. shows that in the lower troposphere AAE increases with increasing OA-to-BC ratios rather than with increasing OA - contributing to sky radiometer retrieval techniques (e.g., AERONET);iii. extends the dependence of AAE on BC-to-OA ratios previously observed in chamber experiments to ambient aerosol dominated by wood-burning emissions. These findings are expected to bear important implications for atmospheric modeling studies and remote sensing observations as regards the parametrization and identification of BrC in the atmosphere.

  19. Changing hydrological conditions in the Po basin under global warming.

    PubMed

    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.

  20. Eudragit RS PO nanoparticles for sustained release of pyridostigmine bromide

    NASA Astrophysics Data System (ADS)

    Hoobakht, Fatemeh; Ganji, Fariba; Vasheghani-Farahani, Ebrahim; Mousavi, Seyyed Mohammad

    2013-09-01

    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.

  1. Letrozole in advanced breast cancer: the PO25 trial

    PubMed Central

    2007-01-01

    Tamoxifen has been a standard first-line endocrine therapy for post-menopausal women with hormone-responsive advanced breast cancer, but more than half of patients fail to respond and time to progression is less than 12 months in responders. The third-generation aromatase inhibitors were developed to provide more effective alternatives to tamoxifen. In the Femara Study PO25, post-menopausal women with advanced breast cancer were randomized to receive letrozole 2.5 mg (n = 453) or tamoxifen 20 mg (n = 454) given orally daily until progressive disease occurred. Patients were permitted to cross over to the other treatment at progression. In the primary efficacy analysis, median time to progression (TTP) was significantly longer with letrozole than with tamoxifen (9.4 months vs. 6.0 months, respectively; P < 0.0001). The objective response rate (ORR) was significantly higher for letrozole than for tamoxifen (32% vs. 21%; P = 0.0002). Prospectively planned analyses of the intent-to-treat population showed that letrozole significantly improved overall survival (OS) compared with tamoxifen over the first 24 months of the trial. An exploratory analysis of patients, who did not cross over, indicated a median OS benefit of 14 months for letrozole compared with tamoxifen. Letrozole is the only third-generation aromatase inhibitor that has demonstrated significant improvements in ORR, TTP, and early OS. PMID:17333340

  2. Carbon coatings with olive oil, soybean oil and butter on nano-LiFePO 4

    NASA Astrophysics Data System (ADS)

    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%.

  3. Anode property of carbon coated LiFePO4 nanocrystals

    NASA Astrophysics Data System (ADS)

    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.

  4. Dispersion, agglomeration, and gelation of LiFePO4 in water-based slurry

    NASA Astrophysics Data System (ADS)

    Tsai, Feng-Yen; Jhang, Jia-Hao; Hsieh, Han-Wei; Li, Chia-Chen

    2016-04-01

    The gelation of commercially available lithium iron phosphate (LiFePO4) in water-based slurry and its corresponding mechanism are studied. Based on surface chemistry analyses using zeta potential measurements and Fourier transform infrared spectroscopy, it is found that the key factor that causes LiFePO4 gelation in the aqueous slurry is the quality of the surface carbon coating on powder. When the surface carbon exhibits functional derivatives, such as carboxyl, hydroxyl, and carbonyl polar functional groups, LiFePO4 tends to form a three-dimensional, gel-like structure via hydrogen bonding. Moreover, the presence of the derivatives reduces the amount of conduction-favorable sp2-bonded carbon to LiFePO4, resulting in an electric resistance increase of the as-prepared electrode and the deterioration of the specific capacity of the as-constructed cell.

  5. Seasonal variations of Pb-210 and Po-210 concentrations in an oligotrophic lake

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Andren, A. W.

    1984-01-01

    In order to examine spatial and temporal variability during the seasonal cycle of the oligotrophic Crystal Lake, Wisconsin, vertical distribution measurements of Pb-210 and Po-210 in both the dissolved and particulate phases were conducted. Mass balance considerations indicate that the removal rates of the two isotopes from the water column to the sediment vary temporally by nearly an order of magnitude. The mean removal residence time was estimated to be 0.095 yr for Pb-210 and 0.26 yr for Po-210, suggesting a difference in the extent of water column recycling. Calculations indicate a cyclic response of the water column Po-210 inventory which corresponds to successive time periods when there were net losses or gains; this response may be due to rapid biological removal and subsequent release from the sediment of freshly deposited Po-210.

  6. Occurrence of (210)Po in marine macroalgae inhabiting a coastal nuclear zone, southeast coast of India.

    PubMed

    Praveen Pole, R P; Feroz Khan, M; Godwin Wesley, S

    2017-04-01

    The activity concentration of (210)Po in 26 species of marine macroalgae found along coast near to a nuclear installation in southeast coast of India was studied. Phaeophytes were found to accumulate the maximum (210)Po concentration and chlorophytes the minimum. The average (210)Po activity concentration values in the three groups were 6.2 ± 2.5 Bq kg(-1) (Chlorophyta), 14.4 ± 5.2 Bq kg(-1) (Phaeophyta) and 11.3 ± 3.9 Bq kg(-1) (Rhodophyta). A statistically significant variation in accumulation was found between groups (p < 0.05). The un-weighted dose rate to these algae due to (210)Po was calculated to be well below the benchmark dose limit of 10 μGy h(-1).

  7. Cell permeable fluorescent receptor for detection of H2PO4(-) in aqueous solvent.

    PubMed

    Sen, Supriti; Mukherjee, Manjira; Chakrabarty, Kuheli; Hauli, Ipsit; Mukhopadhyay, Subhra Kanti; Chattopadhyay, Pabitra

    2013-03-07

    A new colorimetric fluorescent receptor for H(2)PO(4)(-) is reported in this communication. The receptor can detect dihydrogen phosphates optically by developing a color change from yellow to green. Acute spectral responses to H(2)PO(4)(-) in HEPES buffer (DMSO-HEPES 1:9) have been observed. The selectivity zone in terms of pH of the receptor for H(2)PO(4)(-) is attributed to the fitness in the acidity (pK(a)) of receptor with H(2)PO(4)(-). Hydrogen bonding plays the key role here which is confirmed by (1)H NMR titration. The receptor also has good potential for bio-imaging. The mode of interaction has also been established by ab initio calculation.

  8. Quantitative evaluation of 218Po behaviour in air in an artificial environment.

    PubMed

    Yajima, K; Hirao, S; Moriizumi, J; Yamazawa, H

    2015-11-01

    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. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Searching for “LiCr{sup II}PO{sub 4}”

    SciTech Connect

    Mosymow, E.; Glaum, R.; Kremer, R.K.

    2014-10-15

    The two new phosphates LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} and Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} are discovered as equilibrium phases (ϑ=800 °C) in the quarternary system Li/Cr/P/O. Their crystal structures have been determined from single-crystal X-ray diffraction data (LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}: violet-blue, Pnma (no. 62), Z=4, a=6.175(1) Å, b=14.316(3) Å, c=10.277(2) Å, 100 parameters, R{sub 1}=0.028, wR{sub 2}=0.08, 2060 unique reflections with F{sub o}>4σ(F{sub o}); Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4}: greyish-green, P1{sup ¯} (no. 2), Z=1, a=4.9379(7) Å, b=7.917(2) Å, c=8.426(2) Å, α=109.98(2)°, β=90.71(1)°, γ=104.91(1)°, 131 parameters, R{sub 1}=0.022, wR{sub 2}=0.067, 1594 unique reflections with F{sub o}>4σ(F{sub o})). Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4} adopts an hitherto unknown structure type. The crystal structure of LiCr{sup II}{sub 4}(PO{sub 4}){sub 3} is isotypic to that of NaCd{sup II}{sub 4}(PO{sub 4}){sub 3} and related to that of the mineral silicocarnotite Ca{sub 5}(PO{sub 4}){sub 2}(SiO{sub 4}). Significant disorder between Li{sup +} and Cr{sup 2+} is observed for both crystal structures. The oxidation states assigned to chromium in these two phosphates are in agreement with UV/vis/NIR absorption spectra and magnetic susceptibility data recorded for both compounds. Instead of “LiCr{sup II}PO{sub 4}” mixtures of LiCr{sup II}{sub 4}(PO{sub 4}){sub 3}, Li{sub 5}Cr{sup II}{sub 2}Cr{sup III}(PO{sub 4}){sub 4}, Cr{sub 2}O{sub 3}, and CrP are observed at equilibrium. Instead of “Li{sub 2}Cr{sup II}P{sub 2}O{sub 7}” four-phase mixtures consisting of Li{sub 9}Cr{sup III}{sub 3}(P{sub 2}O{sub 7}){sub 3}(PO{sub 4}){sub 2}, Li{sub 3}Cr{sup III}{sub 2}(PO{sub 4}){sub 3}, LiCrP{sub 2}O{sub 7}, and CrP were obtained. - Graphical abstract: Investigations on the equilibrium relations in the system Li/Cr/P/O revealed the two hitherto unknown phosphates Li{sub 5

  10. Additional of polyethylene glycol on the preparation of LaPO4:Eu3+ phosphor

    NASA Astrophysics Data System (ADS)

    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.

  11. Sol-precipitation-hydrothermal synthesis and luminescence of GdPO4:Tb3+ submicron cubes

    NASA Astrophysics Data System (ADS)

    Cao, Yanyan; Sun, Peng; Liang, Yingmin; Wang, Rongrong; Zhang, Xiao

    2016-05-01

    GdPO4:Tb3+ submicron cubes were synthesized by a sol-precipitation-hydrothermal process. The XRD result indicated that GdPO4:Tb3+ submicron cubes have pure hexagonal phase. The SEM and TEM images confirmed the formation of cubic morphology. Under the excitation at 273 nm, GdPO4:Tb3+ submicron cubes show emission bands corresponding to Gd3+ and Tb3+. With the increasing Tb3+ concentration, the emission intensities originating from Gd3+ and 5D3 → 7Fj transition of Tb3+ decrease, but the emission intensities originating from 5D4 → 7Fj transition of Tb3+ increase. These results suggested energy transfer from Gd3+ to Tb3+ and the occurrence of cross-relaxation processes in GdPO4:Tb3+ submicron cubes.

  12. Seasonal variations of Pb-210 and Po-210 concentrations in an oligotrophic lake

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Andren, A. W.

    1984-01-01

    In order to examine spatial and temporal variability during the seasonal cycle of the oligotrophic Crystal Lake, Wisconsin, vertical distribution measurements of Pb-210 and Po-210 in both the dissolved and particulate phases were conducted. Mass balance considerations indicate that the removal rates of the two isotopes from the water column to the sediment vary temporally by nearly an order of magnitude. The mean removal residence time was estimated to be 0.095 yr for Pb-210 and 0.26 yr for Po-210, suggesting a difference in the extent of water column recycling. Calculations indicate a cyclic response of the water column Po-210 inventory which corresponds to successive time periods when there were net losses or gains; this response may be due to rapid biological removal and subsequent release from the sediment of freshly deposited Po-210.

  13. Decay and In-Beam Studies of Neutron-Deficient Po and Ra Isotopes at JYFL

    NASA Astrophysics Data System (ADS)

    Leino, M.; Allatt, R. G.; Andreyev, A. N.; Cocks, J. F. C.; Dorvaux, O.; Enqvist, T.; Eskola, K.; Helariutta, K.; Huyse, M.; Jones, P. M.; Julin, R.; Juutinen, S.; Kankaanpaeae, H.; Keenan, A.; Kettunen, H.; Kuusiniemi, P.; Muikku, M.; Rahkila, P.; Savelius, A.; Trzaska, W. H.; Uusitalo, J.; van Duppen, P.

    1999-05-01

    An extensive program to study the production, decay properties, and nuclear structure of very neutron-deficient polonium and radium nuclei is underway at the Department of Physics, University of Jyvaeskylae, Finland (JYFL). The main tools used in these studies are the gas-filled recoil separator RITU and various germanium gamma-ray arrays. In the course of these studies, among others the following new isotopes have been produced: 204Ra, 203Ra, and 202Ra. Isomeric alpha decaying states have been discovered in 203Ra and 191Po. Fine structure in the decay of 192Po to the oblate and prolate band heads in 188Pb has been observed. In-beam gamma-ray spectra have been, for the first time, measured for 192Po, 206Ra, 208Ra, and 210Ra. Development of collectivity in nuclei in the Po-Ra region and the systematics of reduced alpha widths will be discussed.

  14. Hybrid potential model of the {alpha}-cluster structure of {sup 212}Po

    SciTech Connect

    Ibrahim, T. T.; Perez, S. M.; Wyngaardt, S. M.

    2010-09-15

    Cluster-core potentials derived microscopically or phenomenologically each have some desirable features. We combine these features in an analysis of the properties of {sup 212}Po treated as an {alpha}-{sup 208}Pb system.

  15. 210Po in the diet at Seville (Spain) and its contribution to the dose by ingestion

    PubMed Central

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

    2016-01-01

    The activity concentrations of 210Po have been determined in a total of 24 representative diet samples from Seville (south of Spain), inferring from the obtained values the annual intakes of 210Po by ingestion of the affected population and the corresponding committed effective doses. The annual intakes of 210Po and, consequently, the corresponding doses of this radionuclide show a high variability in correspondence with the variability in the composition of the analysed samples over time, and their magnitude is comparable with the estimated ones in other regions/countries of the world with similar diet habits (countries where the marine products have a considerable weight in the diets). Committed effective doses by ingestion higher than 0.1 mSv y−1 have been estimated exclusively for 210Po, reflecting the importance of this radionuclide and this route of incorporation in the magnitude of the total doses received by the affected population from natural sources. PMID:25802464

  16. Graphene Modified LiFePO4 Cathode Materials for High Power Lithium ion Batteries

    SciTech Connect

    Zhou, X.; Wang, F.; Zhu, Y.; Liu, Z.

    2011-01-24

    Graphene-modified LiFePO{sub 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{sub 4} nanoparticles and graphene oxide nanosheets by spray-drying and annealing processes. The LiFePO{sub 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{sub 4} nanoparticles and graphene sheets was beneficial for Li{sup +} diffusion. The composite cathode material could deliver a capacity of 70 mAh g{sup -1} at 60C discharge rate and showed a capacity decay rate of <15% when cycled under 10C charging and 20C discharging for 1000 times.

  17. Determination of Po-210 content in cigarette smoke using a smoking machine: A case study of Iranian cigarettes.

    PubMed

    Horváth, Mária; Shahrokhi, Amin; Bátor, Péter; Tóth-Bodrogi, Edit; Kovács, Tibor

    2017-08-01

    The Po-210 content of tobacco has been known for a long time, however, different results can be found about the estimated amount of Po-210 that is inhaled by humans as a result of smoking cigarettes. Because of the unique properties of Po-210, the smoking machines available on the market are not suitable because of their failure to quantitatively collect Po-210 for measurement. Therefore, to estimate precisely the amount of Po-210 entering the lungs as a result of smoking, a smoking machine and sampling protocol based on relevant ISO standards - ISO-3308, ISO-3402 and ISO-4387 - was developed. A 5% HCl solution was found to be the best absorber of Po-210 from smoke. Seventeen different brands of cigarettes distributed in Iran were used to validate the new machine and sampling protocol. The Po-210 concentration was determined by alpha spectrometry; the cigarette smoke solution underwent combined acid treatment after adding a Po-209 tracer. The Po-210 activity concentration of cigarettes sold in Iran was between 9.7 ± 1.2 and 26.5 ± 4.6 mBq/cigarette and it was determined that there was no relationship between the Po-210 and nicotine contents of cigarette smoke. Additionally, it was found that 15 ± 10% of the cigarette Po-210 was transferred to the mainstream smoke. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Aging and exercise training reduce testes microvascular Po2 and alter vasoconstrictor responsiveness in testicular arterioles

    PubMed Central

    Dominguez, James M.; Davis, Robert T.; McCullough, Danielle J.; Stabley, John N.

    2011-01-01

    Testicular function and associated testosterone concentration decline with advancing age, and an impaired O2 supply may contribute, in part, to this reduction. We hypothesized that there would be a reduced microvascular Po2 (Po2m) in the testes from aged rats, and this reduced Po2m would be associated with impaired vasomotor control in isolated resistance arterioles. In addition, given the positive effect of exercise on microvascular Po2 and arteriolar function, we further hypothesized that there would be an enhanced Po2m in the testes from aged animals after aerobic exercise training. Testicular Po2m was measured in vivo via phosphorescence quenching in young and aged sedentary (SED) and exercise-trained (ET; 15 m/min treadmill walking, 15-degree incline, 5 days/wk for 10 wk) male Fischer-344 rats. Vasoconstriction to α-adrenergic [norepinephrine (NE) and phenylephrine (PE)] and myogenic stimuli in testicular arterioles was assessed in vitro. In the SED animals, testicular Po2m was reduced by ∼50% with old age (aged SED 11.8 ± 1.9 vs. young SED 22.1 ± 1.1 mmHg; P = 0.0001). Contrary to our hypothesis, exercise training did not alter Po2m in the aged group and reduced testicular Po2m in the young animals, abolishing age-related differences (young ET, 10.0 ± 0.8 vs. aged ET, 10.7 ± 0.9 mmHg; P = 0.37). Vasoconstrictor responsiveness to NE and PE was diminished in aged compared with young (NE: young SED, 58 ± 2 vs. aged SED, 47 ± 2%; P = 0.001) (PE: young SED, 51 ± 3 vs. aged SED, 36 ± 5%; P = 0.008). Exercise training did not alter maximal vasoconstriction to NE in young or aged groups. In summary, advancing age is associated with a reduced testis Po2m and impaired adrenergic vasoconstriction. The diminished testicular microvascular driving pressure of O2 and associated vascular dysfunction provides mechanistic insight into the old age-related decrease in testicular function, and a reduced Po2m may contribute, in part, to reduced fertility markers after

  19. Nanocomposite of LiFePO4 and mesoporous carbon for high power cathode of lithium rechargeable batteries.

    PubMed

    Kim, Jun-Il; Roh, Kwang Chul; Lee, Jae-Won

    2012-11-01

    A composite of LiFePO4 and MgO-templated disordered mesoporous carbon was prepared through infiltrating a LiFePO4 precursor solution into the mesoporous carbon and growing LiFePO4 nanocrystals in the pore of the carbon. Transmission electron microscope (TEM) and scanning electron microscope (SEM) analysis showed that LiFePO4 nanoparticles are embedded homogeneously in the mesoporous carbon without formation of big LiFePO4 particles out of the pores. The pores of the carbon are believed to suppress crystal growth of LiFePO4. The 3-dimensional conducting carbon network between the LiFePO4 nanoparticles led to excellent cycling stability and rate capability. The composite showed no fade of discharge capacity up to 100 cycles and 85% of the reversible capacity at 0.1 C was retained at 30 C.

  20. Synthesis and characterization of Carbon Nano Fiber/LiFePO 4 composites for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bhuvaneswari, M. S.; Bramnik, N. N.; Ensling, D.; Ehrenberg, H.; Jaegermann, W.

    Carbon Nano Fibers (CNFs) coated with LiFePO 4 particles have been prepared by a non-aqueous sol-gel technique. The functionalization of the CNFs by HNO 3 acid treatment has been confirmed by Raman and XPS analyses. The samples pure LiFePO 4 and LiFePO 4-CNF have been characterized by XRD, SEM, RAMAN, XPS and electrochemical analysis. The LiFePO 4-CNF sample shows better electrochemical performance compared to as-prepared LiFePO 4. LiFePO 4-CNF (10 wt.%) delivers a higher specific capacity (∼140 mAh g -1) than LiFePO 4 with carbon black (25 wt.%) added after synthesis (∼120 mAh g -1) at 0.1C.

  1. Highly efficient photocatalytic degradation of methylene blue by PoPD/TiO2 nanocomposite.

    PubMed

    Yang, Chuanxi; Zhang, Ming; Dong, Wenping; Cui, Guanwei; Ren, Zongming; Wang, Weiliang

    2017-01-01

    The poly-o-phenylenediamine (PoPD)/TiO2 nanocomposite was successfully synthesized via 'in situ' oxidative polymerization method. The modified photocatalysts were characterized by BET, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrarad spectra (FT-IR), thermogravimrtic analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible diffuse reflectance spectrum (UV-Vis DRS) and Photocurrent Test. The results showed that the PoPD exists on the surface of TiO2, the presence of PoPD does not impact on the lattice structure and grain size of TiO2, and the presence of PoPD enhances the visible response and photoelectric property. The photocatalytic degradation of methylene blue (MB) was chosen as a model reaction to evaluate the photocatalytic activities of TiO2 and PoPD/TiO2. The optimal preparation condition was the molar ratio of oPD to TiO2 = 3:1, HCl concentration = 1.2 mol/L, the molar ratio of APS to oPD = 1:1. The apparent first-order rate constant kapp of PoPD/TiO2 nanocomposite was 0.0098 min-1, which is 6 times higher than TiO2 (0.0016 min-1). Meanwhile, the PoPD/TiO2 nanocomposites showed excellent photocatalytic stability, and the photocatalytic stability was depended on the stability of structure. At last, the photocatalytic mechanism of POPD/TiO2 nanocomposites was also proposed based on the synergetic effect between TiO2 and PoPD.

  2. A facile way to rejuvenate Ag3PO4 as a recyclable highly efficient photocatalyst.

    PubMed

    Wang, Hua; Bai, Yusong; Yang, Jutong; Lang, Xiufeng; Li, Jinghong; Guo, Lin

    2012-04-27

    Recycling awarded the silver: Ag(3)PO(4), a highly efficient photocatalyst, decomposes to the weak photocatalyst Ag during consecutive photocatalytic cycles. A facile and very mild wet chemical oxidation method was proposed, which involves the cooperation of H(2)O(2) with Na(2)HPO(4), to rejuvenate Ag(3)PO(4) from Ag as a recyclable highly efficient photocatalyst. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Highly efficient photocatalytic degradation of methylene blue by PoPD/TiO2 nanocomposite

    PubMed Central

    Dong, Wenping; Cui, Guanwei; Ren, Zongming

    2017-01-01

    The poly-o-phenylenediamine (PoPD)/TiO2 nanocomposite was successfully synthesized via ‘in situ’ oxidative polymerization method. The modified photocatalysts were characterized by BET, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrarad spectra (FT-IR), thermogravimrtic analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible diffuse reflectance spectrum (UV-Vis DRS) and Photocurrent Test. The results showed that the PoPD exists on the surface of TiO2, the presence of PoPD does not impact on the lattice structure and grain size of TiO2, and the presence of PoPD enhances the visible response and photoelectric property. The photocatalytic degradation of methylene blue (MB) was chosen as a model reaction to evaluate the photocatalytic activities of TiO2 and PoPD/TiO2. The optimal preparation condition was the molar ratio of oPD to TiO2 = 3:1, HCl concentration = 1.2 mol/L, the molar ratio of APS to oPD = 1:1. The apparent first-order rate constant kapp of PoPD/TiO2 nanocomposite was 0.0098 min-1, which is 6 times higher than TiO2 (0.0016 min-1). Meanwhile, the PoPD/TiO2 nanocomposites showed excellent photocatalytic stability, and the photocatalytic stability was depended on the stability of structure. At last, the photocatalytic mechanism of POPD/TiO2 nanocomposites was also proposed based on the synergetic effect between TiO2 and PoPD. PMID:28329007

  4. [A novel red phosphor (La3PO7:Eu3+) prepared by solid state method].

    PubMed

    Jin, Ye; Qin, Wei-ping; Zhang, Ji-sen; Wang, Yan; Cao, Chun-yan; Zhang, Ji-shuang; Ren, Xin-guang

    2008-12-01

    Novel red phosphor, Eu3+ -doped oxyphosphate (La3 PO7:Eu3+), was synthesized by a solid state method under high temperature. All the starting materials were analytical grade. La2O3, EuO3 and (NH4)2HPO4 weighed in appropriated molar ratios and ground in an agate mortar. Then the powder was treated under 1000 degrees C. The crystal phase of La3PO7:Eu3+ was investigated by X-ray diffraction (XRD) using a Cu target radiation resource (lamda = 1.54078 ?) and exhibited prominent peaks accordant with JCPDS standard card (33-0720) of La3PO7 in monoclinic phase. Emission and excitation spectra of La3PO7:Eu3+ were recorded at room temperature using a fluorescence spectrometer (Hitachi F-4500). Under 254 nm excitation, intense red fluorescence was observed from La3PO7:Eu3+, which was assigned to the (5)D0-->(7)F2 transition of Eu3+ ions. The intensity of the (5)D0-->(7)F2 transition is stronger than that of the (5)D0-->(7)F1 transition, showing that the Eu3+ ions were in the non-centrosym-metric sites in La3PO7. The CommissionIn-ternational DeL" Eclairage (CIE) coordinate of La3PO7:Eu3+ is (0.63,0.37) in the red area of CIE1931 XY chromaticity coordinate graph and close to that of Y2o3:Eu3+, but the cost of La3PO7 host is lower. This novel material may have potential applications in plasma display panels and Hg-free fluorescent lamps in the future.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Nanocubic KTi2(PO4)3 electrodes for potassium-ion batteries.

    PubMed

    Han, Jin; Niu, Yubin; Bao, Shu-Juan; Yu, Ya-Nan; Lu, Shi-Yu; Xu, Maowen

    2016-09-22

    Novel nanocubic KTi2(PO4)3 was successfully fabricated via a facile hydrothermal method combined with a subsequent annealing treatment and further evaluated as an electrode material for potassium-ion batteries for the first time. For comparison, carbon-coated KTi2(PO4)3 obtained by a normal cane sugar-assisted method reveals improved electrochemical performances in potassium-ion batteries. This work may give a new insight into developing electrode materials for potassium-ion batteries.

  7. Persistent luminescence properties of SrMg2(PO4)2:Eu2+,Tb3+

    NASA Astrophysics Data System (ADS)

    Ju, Guifang; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Hung, Lihua

    2014-03-01

    We investigate the persistent luminescence in europium-doped SrMg2(PO4)2 upon codoping with auxiliary terbium. Luminescence properties of the phosphors, including photoluminescence, luminescence decay and thermoluminescence, are systematically studied. SrMg2(PO4)2:Eu2+ shows only a weak persistent luminescence, and codoping with Tb3+ is necessary to obtain considerable persistent luminescence. An energy level scheme is constructed to convey reasonable trapping and detrapping processes in the material.

  8. Combustion Synthesis of Ca3(PO4)2 Net-Shape Surgical Implants

    NASA Technical Reports Server (NTRS)

    Ayers, Reed A.; Castillo, Martin; Gottoli, Guglielmo; Moore, John J.; Simske, Steven J.

    2006-01-01

    Self-propagating high-temperature combustion synthesis (SHS) is the basis of a method of making components of porous tricalcium phosphate [Ca3(PO4)2] and related compounds in net sizes and shapes for use as surgical implants that are compatible with bone. The SHS method offers advantages over prior methods of manufacturing Ca3(PO4)2-based surgical implants.

  9. Improvement of electrochemical activity of LiMnPO4-based cathode by surface iron enrichment

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyue; Wang, Tao; Bi, Yujing; Liu, Meng; Yang, Wenchao; Peng, Zhe; Wang, Deyu

    2017-02-01

    LiMnPO4 has attracted massive interests due to its appropriate redox potential and the success of its iron comparative in the lithium ion batteries. The bulk substitution has been widely used to address the poor electrochemical activity of LiMnPO4, which is much lower than that of LiFePO4. In this work, we compare the performance of the core-shell structure and the homogeneous substitution with the same Mn/Fe molar ratio of LiMn0.8Fe0.2PO4. The core-shell phosphate material after carbon coating is composed of a core part of quasi-single LiMnPO4 phase, and a 3-4 nm shell layer of quasi-single LiFePO4-phase, separated by the phase boundary with 1-2 nm thickness. It is interesting to reveal that the core-shell samples exhibit capacities of 156.4, 144.5, 128.2 mAh g-1 under 0.1C, 1C and 5C respectively, which are 5-10% higher than that of the homogenous substituted LiMn0.8Fe0.2PO4 at the corresponding rates, while both of these samples present excellent cyclic stability, still retaining ∼95% of the initial capacities after 1000 cycles under 1C discharging rate. Our results demonstrate that the main reason for LiMnPO4's poor electrochemical activity should be emphasized on the surface polarization, whereas the tardiness on bulk transportation is not as serious as it was presumed.

  10. High-G Verification of Lithium-Polymer (Li-Po) Pouch Cells

    DTIC Science & Technology

    2016-05-19

    UNCLASSIFIED UNCLASSIFIED AD-E403 766 Technical Report ARMET-TR-15067 HIGH-G VERIFICATION OF LITHIUM- POLYMER (LI-PO) POUCH...TITLE AND SUBTITLE HIGH-G VERIFICATION OF LITHIUM- POLYMER (LI-PO) POUCH CELLS 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...causing re-evaluation of power sources. This report evaluates two types of lithium- polymer cells for use in high acceleration environments for

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

    PubMed

    Strumińska-Parulska, Dagmara I

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  13. LiFePO4/C nanocomposites for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    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.

  14. Correlation of regional disease and in vivo PO2 in rat mammary adenocarcinoma.

    PubMed Central

    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 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. Images Figure 1 Figure 4 Figure 5 PMID:6859229

  15. Vanadium doping of LiMnPO4: Vibrational spectroscopy and first-principle studies

    NASA Astrophysics Data System (ADS)

    Kellerman, D.; Medvedeva, N.; Mukhina, N.; Semenova, A.; Baklanova, I.; Perelyaeva, L.; Gorshkov, V.

    2014-01-01

    The samples of pure and 10% vanadium-doped LiMnPO4 have been synthesized by the solid-state reaction technique. The results of Raman and infrared absorption spectroscopy show that the vanadium atoms replace phosphorus giving rise to LiMn(PO4)1-x(VO4)x solid solutions. This conclusion is confirmed by the first-principle studies.

  16. Transport Properties of xAgI-(1-x)LiPO3 Composite Electrolytes

    NASA Astrophysics Data System (ADS)

    Singh, D. P.; Shahi, K.; Kar, K. K.

    2011-07-01

    xAgI-(1-x) LiPO3 composite glasses were made by quenching of molten mixture. XRD confirms that γ-AgI is stabilized in LiPO3 glass matrix. A room temperature conductivity of ˜10-3 S/cm is achieved in the composite glass. The ac conductivity follows Jonscher power law (JPL). Higher composition samples also obey time temperature superposition scaling.

  17. Occurrence of ²¹⁰Po and biological effects of low-level exposure: the need for research.

    PubMed

    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.

  18. Levels and transfer of 210Po and 210Pb in Nordic terrestrial ecosystems.

    PubMed

    Brown, J E; Gjelsvik, R; Roos, P; Kålås, J A; Outola, I; Holm, E

    2011-05-01

    Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides (210)Po and (210)Pb 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 (210)Pb activity concentrations from elevated levels in humus/surface soils to "supported" levels at depth. Activity concentrations of (210)Po 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 (210)Po and (210)Pb and that fauna in close contact with this media may also exhibit elevated levels of (210)Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of (210)Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of (210)Po in this system.

  19. 210Po and major ions in drainage water from soil treated with various types of fertilizers.

    PubMed

    Jiménez, Fernando; López, Raúl; Debán, Luis; Pardo, Rafael; García-Talavera, Marta

    2007-07-01

    The levels of (210)Po, nutrients (NH(4)(+), NO(3)(-), PO(4)(3 -)) and major ions (Na(+), K(+), Mg(2 +), Ca(2 +), F(-), NO(2 -), Br(-), Cl(-), SO(4)(2 -)) were determined, by means of lysimeter experiences, in drainage waters for agricultural soils untreated and treated with different types of fertilizers (animal manure, sewage sludge and NPK synthetic fertilizer) applied at several rates. Analytical determinations were performed by using alpha -spectrometry in the case of (210)Po, or Ion Exchange liquid chromatography for the other ionic species. Statistical uni and multivariate analysis of the results shown significant differences among lixiviates according to the different fertilizer treatments. Sewage sludge and manure applications resulted in similar compositions of lixiviates with low (210)Po levels, whereas synthetic fertilizers produced higher (210)Po concentrations and different concentration patterns of ionic species when applied at or above the recommended rates. All (210)Po levels were well below the limits proposed by the 2001/928/ Euratom Recommendation. The concentrations of the rest of the ionic species, exception made from NH(4)(+) and NO(3)(-), were also below the limits proposed by Spanish regulations.

  20. Design of LaPO4:Nd3+ materials by using ionic liquids

    NASA Astrophysics Data System (ADS)

    Cybinska, J.; Guzik, M.; Lorbeer, C.; Zych, E.; Guyot, Y.; Boulon, G.; Mudring, A.-V.

    2017-01-01

    Monoclinic monazite-type Nd3+-doped lanthanum orthophosphate (LaPO4:Nd3+) nanoparticles were prepared by microwave treatment of simple lanthanide precursors such as Nd(OAc)3•xH2O, OAc = acetate) with task-specific dihydrogen phosphate ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium dihydrogenphosphate- BmPyrH2PO4 (IL1) and 2-hydroxyethyl-N,N,N-trimethylammonium, [choline][H2PO4] (IL2) as the reaction medium, reactant and in-situ nanoparticle stabilizer. This synthesis route possesses many advantages as it is a fast and facile preparation method of the desired phosphate nanomaterials without the necessity for post-reaction heat treatment to obtain the anhydrous high temperature monazite phosphate phase. The nano-sized phosphors Nd3+:LaPO4 were carefully analyzed by the powder X-ray diffraction, electron microscopy and spectroscopic techniques taking advantage of the Nd3+ spectroscopic probe to analyze in detail the structural properties. Applied high resolution low temperature absorption and emission techniques allowed to complete the structural information unavailable from the XRD powder patterns. A clear influence of the used task-specific dihydrogen phosphate ILs on the structure, morphology, luminescence intensity and lifetimes of the obtained Nd3+:LaPO4 was found. It is worth noting that the Nd3+ luminescence in LaPO4 has never been reported up to now.

  1. Structural basis for single-stranded RNA recognition and cleavage by C3PO

    PubMed Central

    Zhang, Jing; Liu, Hehua; Yao, Qingqing; Yu, Xiang; Chen, Yiqing; Cui, Ruixue; Wu, Baixing; Zheng, Lina; Zuo, Junjun; Huang, Zhen; Ma, Jinbiao; Gan, Jianhua

    2016-01-01

    Translin and translin-associated factor-x are highly conserved in eukaroytes; they can form heteromeric complexes (known as C3POs) and participate in various nucleic acid metabolism pathways. In humans and Drosophila, C3POs cleave the fragmented siRNA passenger strands and facilitate the activation of RNA-induced silencing complex, the effector complex of RNA interference (RNAi). Here, we report three crystal structures of Nanoarchaeum equitans (Ne) C3PO. The apo-NeC3PO structure adopts an open form and unravels a potential substrates entryway for the first time. The NeC3PO:ssRNA and NeC3PO:ssDNA complexes fold like closed football with the substrates captured at the inner cavities. The NeC3PO:ssRNA structure represents the only catalytic form C3PO complex available to date; with mutagenesis and in vitro cleavage assays, the structure provides critical insights into the substrate binding and the two-cation-assisted catalytic mechanisms that are shared by eukaryotic C3POs. The work presented here further advances our understanding on the RNAi pathway. PMID:27596600

  2. Phase dependent structural and electronic properties of lanthanum orthophosphate (LaPO4).

    PubMed

    Neupane, M R; Garrett, G A; Rudin, S; Andzelm, J W

    2016-05-25

    We study the phase-dependent structural and electronic properties of bulk LaPO4, using density functional theory (DFT). The applicability of conventional semi-local and hybrid functionals in predicting structural and electronic properties of monoclinic and hexagonal LaPO4 is evaluated by comparing results to available experimental data. The monoclinic LaPO4 was found to be more stable than the hexagonal phase in ambient conditions with a small energy difference, suggesting a possibility of a phase transition. Both the phases in the bulk form are found to be diamagnetic with indirect energy gaps. These results are consistent with available experimental results. In the monoclinic phase, the hybrid functionals predict indirect band gap at about 8 eV. Furthermore, the calculated indirect-direct transition energy offset (ΔE) in the hexagonal phase was three times lower than the monoclinic phase. Our calculations based on hybrid functionals also reveal that the states near the conduction band edge in the hexagonal LaPO4 are strongly hybridized between La and PO4 states. By analyzing the band dispersion around the band edges, we show that the hexagonal phase has lighter electron effective mass, as compared to the monoclinic phase. With a larger energy gap, smaller ΔE, and smaller electron effective mass, the hexagonal LaPO4 might be a promising candidate material as an n-type transparent oxide.

  3. Phase dependent structural and electronic properties of lanthanum orthophosphate (LaPO4)

    NASA Astrophysics Data System (ADS)

    Neupane, M. R.; Garrett, G. A.; Rudin, S.; Andzelm, J. W.

    2016-05-01

    We study the phase-dependent structural and electronic properties of bulk LaPO4, using density functional theory (DFT). The applicability of conventional semi-local and hybrid functionals in predicting structural and electronic properties of monoclinic and hexagonal LaPO4 is evaluated by comparing results to available experimental data. The monoclinic LaPO4 was found to be more stable than the hexagonal phase in ambient conditions with a small energy difference, suggesting a possibility of a phase transition. Both the phases in the bulk form are found to be diamagnetic with indirect energy gaps. These results are consistent with available experimental results. In the monoclinic phase, the hybrid functionals predict indirect band gap at about 8 eV. Furthermore, the calculated indirect-direct transition energy offset (ΔE) in the hexagonal phase was three times lower than the monoclinic phase. Our calculations based on hybrid functionals also reveal that the states near the conduction band edge in the hexagonal LaPO4 are strongly hybridized between La and PO4 states. By analyzing the band dispersion around the band edges, we show that the hexagonal phase has lighter electron effective mass, as compared to the monoclinic phase. With a larger energy gap, smaller ΔE, and smaller electron effective mass, the hexagonal LaPO4 might be a promising candidate material as an n-type transparent oxide.

  4. Low-temperature synthesis of LiFePO4 nanocrystals by solvothermal route.

    PubMed

    Lim, Jinsub; Kang, Sung-Won; Moon, Jieh; Kim, Sungjin; Park, Hyosun; Baboo, Joseph Paul; Kim, Jaekook

    2012-01-05

    LiFePO4 nanocrystals were synthesized at a very low temperature of 170°C using carbon nanoparticles by a solvothermal process in a polyol medium, namely diethylene glycol without any heat treatment as a post procedure. The powder X-ray diffraction pattern of the LiFePO4 was indexed well to a pure orthorhombic system of olivine structure (space group: Pnma) with no undesirable impurities. The LiFePO4 nanocrystals synthesized at low temperature exhibited mono-dispersed and carbon-mixed plate-type LiFePO4 nanoparticles with average length, width, and thickness of approximately 100 to 300 nm, 100 to 200 nm, and 50 nm, respectively. It also appeared to reveal considerably enhanced electrochemical properties when compared to those of pristine LiFePO4. These observed results clearly indicate the effect of carbon in improving the reactivity and synthesis of LiFePO4 nanoparticles at a significantly lower temperature.

  5. Hydrothermal growth and morphology evolution of CePO{sub 4} aggregates by a complexing method

    SciTech Connect

    Ma Lin; Chen Weixiang Zheng Yifan; Xu Zhude

    2008-11-03

    A facile hydrothermal route assisted by Na{sub 2}H{sub 2}EDTA (ethylenediaminetetraacetic acid disodium) has been successfully developed to prepare uniform cerium phosphate (CePO{sub 4}) aggregates with different morphologies, such as peanut-like and spindle-like. It was found that the as-prepared uniform CePO{sub 4} aggregates were constructed with many nearly parallel aligned nanorods. The molar ratio of EDTA/Ce{sup 3+}, solution pH and reaction time had great influences on the morphologies and sizes of the CePO{sub 4} samples. In our process of synthesis, Na{sub 2}H{sub 2}EDTA played important roles as complexing reagent and inducing agent on the formation of CePO{sub 4} aggregates. The possible growth mechanism for CePO{sub 4} aggregates was presented. Ce{sub 0.9}Tb{sub 0.1}PO{sub 4} aggregates with different morphologies were also prepared and their photoluminescence properties were characterized.

  6. Li 3V 2(PO 4) 3 cathode material synthesized by chemical reduction and lithiation method

    NASA Astrophysics Data System (ADS)

    Zheng, Jun-Chao; Li, Xin-Hai; Wang, Zhi-Xing; Guo, Hua-Jun; Hu, Qi-Yang; Peng, Wen-Jie

    The monoclinic-type Li 3V 2(PO 4) 3 cathode material was synthesized via calcining amorphous Li 3V 2(PO 4) 3 obtained by chemical reduction and lithiation of V 2O 5 using oxalic acid as reducer and lithium carbonate as lithium source in alcohol solution. The amorphous Li 3V 2(PO 4) 3 precursor was characterized by using TG-DSC and XPS. The results showed that the V 5+ was reduced to V 3+ by oxalic acid at ambient temperature and pressure. The prepared Li 3V 2(PO 4) 3 was characterized by XRD and SEM. The results indicated the Li 3V 2(PO 4) 3 powder had good crystallinity and mesoporous morphology with an average diameter of about 30 nm. The pure Li 3V 2(PO 4) 3 exhibits a stable discharge capacity of 130.08 mAh g -1 at 0.1 C (14 mA g -1).

  7. Giant anisotropic interactions in frustrated quantum magnet BiCu2PO6

    NASA Astrophysics Data System (ADS)

    Plumb, Kemp

    2015-03-01

    I will discuss a series of comprehensive inelastic neutron scattering measurements which uncover the full magnetic excitation spectrum in the valence bond ordered compound BiCu2PO6. Owing to its frustrated geometry and potential to realize unique quantum phase transitions in high magnetic fields, BiCu2PO6 has received significant attention in recent literature. However, the true nature of the magnetic Hamiltonian responsible for the high field phenomena has not been known until now. I will present measurements of the spin excitation spectrum in BiCu2PO6 from which the magnetic Hamiltonian is elucidated. The spectrum is unique to the frustrated two-leg ladder geometry in BiCu2PO6 and we have been able to correctly describe the lowest energy excitations within the framework of a bond-operator theory, incorporating anisotropic magnetic exchange interactions which are comparable to the Heisenberg exchange terms. The anisotropic exchange interactions originate from spin orbit coupling and are of an unexpectedly large magnitude for a Cu based magnetic compound, potentially indicating the relevance of Bismuth in the superexchange pathway. BiCu2PO6 is a complex and unique quantum magnet combining frustration and anisotropic exchange; the discovery of such large anisotropic interactions in BiCu2PO6 hints at new routes for incorporating spin anisotropies in 3d transition metal based magnets.

  8. Concentration of 210Po, 226Ra and 228Ac in non-siliceous environmental materials

    NASA Astrophysics Data System (ADS)

    Houmani, Zidan Mohamed M.; Bradley, D. A.; Maah, Mohd. Jamil; Ahmed, Zaharuddin

    2001-06-01

    The present interest concerns the possible anthropomorphic enhancement of naturally occurring radioactive material (NORM) in non-siliceous media, in particular, sediment from a river running alongside a crude oil facility and alluvial samples from the site of a now defunct minerals benefication plant. We use gamma spectrometry for 226Ra and 228Ac, and for 210Po we use alpha spectrometry in association with a hydrochloric acid based radiochemical method for the extraction of 210Po. Using 209Po to monitor polonium extraction from samples we find the concentrations of 210Po, 226Ra and 228Ac in river sediments to be in accord with typical background values (˜0.04 Bq g -1 dry), while for sub-surface soils located nearby we find the respective activity concentrations to accord with low background values (˜0.02 Bq g -1dry). For alluvial material from the site of a defunct minerals benefications plant we have found 210Po concentrations of ˜11 Bq g -1 (dry) in two of three samples and 30 Bq g -1 (dry) in the remaining sample; 226Ra and 228Ac were some several times these concentrations. In support of the methods we have adopted in present evaluations we find IAEA-300 Baltic Sea sediment reference material to contain 210Po concentrations that are within the IAEA confidence interval for this material.

  9. Removal of (210)Po from aqueous media and its thermodynamics and kinetics.

    PubMed

    Erenturk, S Akyil; Kaygun, A Kilincarslan

    2017-08-01

    In this study, the composite adsorbent as granule was prepared by mixing of polyacrylonitrile (PAN) and a natural zeolite (clinoptilolite) in specific conditions. The prepared composite adsorbent was used for investigating the adsorption behaviour of (210)Po. Adsorption of (210)Po was studied in a column system. The effective parameters such as initial activity concentration of (210)Po, pH of the aqueous solution, contact time and temperature of solution for adsorption behaviour of (210)Po were studied. Adsorption yield of (210)Po on composite adsorbent from aqueous solution in optimum conditions were determined as 75.00 ± 0.15%. The adsorption equilibrium data was examined using various well-known isotherm models such as Freundlich, Langmuir, Dubinin and Radushkevish and Tempkin, and it was observed that the experimental equilibrium data well fitted and found to be in good agreement with the Tempkin model. Adsorption thermodynamics and kinetics of the polonium were studied. It was found that the processes for (210)Po were exothermic and spontaneous. The kinetic data conformed better to the pseudo-second order equation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Controlled synthesis and photocatalytic properties of rhombic dodecahedral Ag3PO4 with high surface energy

    NASA Astrophysics Data System (ADS)

    Xie, Yao; Huang, Zhaohui; Zhang, Zhijie; Zhang, Xiaoguang; Wen, Ruilong; Liu, Yangai; Fang, Minghao; Wu, Xiaowen

    2016-12-01

    In this study, a series of Ag3PO4 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 Ag3PO4 photocatalysts were discussed. The photocatalytic activity of the Ag3PO4 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 Ag3PO4 particles with a high exposure of the {110} facets and high surface energy. The surface energy of the {110} facets was 1.31 J/m2, greater than that of the {100} facet (1.12 J/m2). However, with 1% EG in the reaction solvent, although the Ag3PO4 photocatalysts were composed of a majority of rhombic dodecahedral Ag3PO4 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.

  11. IR near-field spectroscopy and imaging of single Li(x)FePO4 microcrystals.

    PubMed

    Lucas, I T; McLeod, A S; Syzdek, J S; Middlemiss, D S; Grey, C P; Basov, D N; Kostecki, R

    2015-01-14

    This study demonstrates the unique capability of infrared near-field nanoscopy combined with Fourier transform infrared spectroscopy to map phase distributions in microcrystals of Li(x)FePO4, a positive electrode material for Li-ion batteries. Ex situ nanoscale IR imaging provides direct evidence for the coexistence of LiFePO4 and FePO4 phases in partially delithiated single-crystal microparticles. A quantitative three-dimensional tomographic reconstruction of the phase distribution within a single microcrystal provides new insights into the phase transformation and/or relaxation mechanism, revealing a FePO4 shell surrounding a diamond-shaped LiFePO4 inner core, gradually shrinking in size and vanishing upon delithiation of the crystal. The observed phase propagation pattern supports recent functional models of LiFePO4 operation relating electrochemical performance to material design. This work demonstrates the remarkable potential of near-field optical techniques for the characterization of electrochemical materials and interfaces.

  12. Fabrication and luminescence of BiPO4:Tb3+/Ce3+ nanofibers by electrospinning

    NASA Astrophysics Data System (ADS)

    Yang, Yuguo; Liu, Bing; Zhang, Yuanyuan; Lv, Xianshun; Wei, Lei; Wang, Xuping

    2016-02-01

    BiPO4:Tb3+/Ce3+ nanofibers are synthesized by a simple electrospinning process and followed by a calcination treatment. The nanofibers are characterized by TG-DSC, XRD, FT-IR, SEM, TEM, and spectrophotometer. The calcined BiPO4:Tb3+/Ce3+ nanofibers have a monoclinic phase and the diameters are in the range of 80-200 nm. The SEM and TEM images show that the nanofibers are mesoporous and composed of lots of linked nanoparticles. Under an excitation at 369 nm, BiPO4:Tb3+ and BiPO4:Tb3+/Ce3+ nanofibers show characteristic emission bands originating from the 5D4 → 7Fj (j = 6, 5, 4, and 3) transitions of Tb3+ ions. The luminescent properties of BiPO4:Tb3+ indicate that the quenching concentration for Tb3+ ions in BiPO4 host is about 15 mol%. The co-doped Ce3+ ions can improve the emission intensity through the energy transfer from Ce3+ to Tb3+ ions.

  13. The Electronic Spectrum of H_2PO, the Prototypical Phosphoryl Free Radical

    NASA Astrophysics Data System (ADS)

    Gharaibeh, Mohammed A.; Clouthier, Dennis J.

    2011-06-01

    The electronic spectrum of the H_2PO radical has been identified by laser-induced fluorescence (LIF) and single vibronic level (SVL) emission techniques. The radical was produced in a pulsed electric discharge jet using a precursor mixture of phosphine (PH_3) and carbon dioxide in high-pressure argon and the tilde{B}^2A' - tilde{X}^2A' electronic transition was detected in the 410-338 nm region. Low resolution LIF and SVL emission spectra of H_2PO and D_2PO have been recorded and the A' vibrational frequencies have been determined in both states. High-resolution spectra of the 0_0^0 bands of H_2PO and D_2PO, which consist of strong a-type and weaker c-type components, were recorded. The spectra have been rotationally analyzed and the excited state molecular structure determined. The spectrum of H_2PO will be discussed in comparison with the spectra of other phosphoryl and arsenyl radicals that have been recently studied in our laboratory.

  14. Pressure induced phase transformation in U{sub 2}O(PO{sub 4}){sub 2}

    SciTech Connect

    Mishra, A.K. Murli, Chitra; Singhal, A.; Sharma, Surinder M.

    2008-05-15

    The high pressure behavior of U{sub 2}O(PO{sub 4}){sub 2} has been investigated with the help of Raman scattering and X-ray diffraction measurements up to {approx}14 and 6.5 GPa, respectively. The observed changes in the Raman spectra as well as the X-ray diffraction patterns suggest that U{sub 2}O(PO{sub 4}){sub 2} undergoes a phase transition at {approx}6 GPa to a mixture of a disordered ambient pressure phase and a new high pressure phase. The new phase resembles the triclinic mixed-valence phase of uranium orthophosphate (U(UO{sub 2})(PO{sub 4}){sub 2}). On release of pressure the initial phase is not retrieved. - Graphical abstract: The high pressure behavior of U{sub 2}O(PO{sub 4}){sub 2} has been investigated with the help of Raman scattering and X-ray diffraction measurements up to {approx}14 and 6.5 GPa, respectively. The observed changes in the Raman spectra as well as the X-ray diffraction patterns suggest that U{sub 2}O(PO{sub 4}){sub 2} undergoes a phase transition at {approx}6 GPa to a mixture of a disordered ambient pressure phase and a new high pressure phase. The new phase resembles the triclinic mixed-valence phase of uranium orthophosphate (U(UO{sub 2})(PO{sub 4}){sub 2}). On release of pressure the initial phase is not retrieved.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  16. Improved electrochemical performances of 9LiFePO 4·Li 3V 2(PO 4)/C composite prepared by a simple solid-state method

    NASA Astrophysics Data System (ADS)

    Xiang, J. Y.; Tu, J. P.; Zhang, L.; Wang, X. L.; Zhou, Y.; Qiao, Y. Q.; Lu, Y.

    9LiFePO 4·Li 3V 2(PO 4) 3/C is synthesized via a carbon thermal reaction using petroleum coke as both reduction agent and carbon source. The as-prepared material is not a simple mixture of LiFePO 4 (LFP) and Li 3V 2(PO 4) 3 (LVP), but a composite possessing two phases: one is V-doped LFP and the other is Fe-doped LVP. The typical structure enhances the electrical conductivity of the composite and improves the electrochemical performances. The first discharge capacity of 9LFP·LVP/C in 18650 type cells is 168 mAh g -1 at 1 C (1 C 9LFP·LVP/C = 166 mA g -1), and exhibits high reversible discharge capacity of 125 mAh g -1 at 10 C even after 150 cycles. At the temperature of -20 °C, the reversible capacity of 9LFP·LVP/C can maintain 75% of that at room temperature.

  17. Silica-modified luminescent LaPO4 :Eu@LaPO4 @SiO2 core/shell nanorods: Synthesis, structural and luminescent properties.

    PubMed

    Ansari, Anees A

    2017-08-17

    Monoclinic-type tetragonal LaPO4 :Eu (core) and LaPO4 :Eu@LaPO4 (core/shell) nanorods (NRs) were successfully prepared using a urea-based co-precipitation process under ambient conditions. An amorphous silica layer was coated around the luminescent core/shell NRs via the sol-gel process to improve their solubility and colloidal stability in aqueous and non-aqueous media. The prepared nano-products were systematically characterized by X-ray diffraction pattern, transmission electron microscopy, energy dispersive X-ray analysis, and FTIR, UV/Vis, and photoluminescence spectroscopy to examine their phase purity, crystal phase, surface chemistry, solubility and luminescence characteristics. The length and diameter of the nano-products were in the range 80-120 nm and 10-15 nm, respectively. High solubility of the silica-modified core/shell/Si NRs was found for the aqueous medium. The luminescent core NRs exhibited characteristic excitation and emission transitions in the visible region that were greatly affected by surface growth of insulating LaPO4 and silica layers due to the multiphonon relaxation rate. Our luminescence spectral results clearly show a distinct difference in intensities for core, core/shell, and core/shell/Si NRs. Highly luminescent NRs with good solubility could be useful candidates for a variety of photonic-based biomedical applications. Copyright © 2017 John Wiley & Sons, Ltd.

  18. Saproxylic beetles of the Po plain woodlands, Italy

    PubMed Central

    Bogliani, Giuseppe

    2014-01-01

    Abstract Forest ecosystems play an important role for the conservation of biodiversity, and for the protection of ecological processes. The Po plain woodlands which once covered the whole Plain, today are reduced in isolated highly threatened remnants by modern intensive agriculture. These close to natural floodplain forests are one of the most scarce and endangered ecosystems in Europe. Saproxylic species represent a major part of biodiversity of woodlands. The saproxylic insects are considered one of the most reliable bio-indicators of high-quality mature woodlands and have a very important role in regard to the protection and monitoring of forest biodiversity due to their highly specific living environments. As a result of the dramatic reduction of mature forests and the decreased availability of deadwood most of the saproxylic communities are greatly diminishing. The study was conducted in the Ticino Valley Regional Park and the aim is to contribute to the expansion of knowledge on the saproxylic beetles of Lombardy. We investigated 6 sampling sites belonging to alluvial and riparian mixed forests. For each forest we selected 12 trees. For beetles’ collection we used two different traps: Eclector Traps and Trunk Window Traps (total of 72 traps and 864 samples collected). We determined 4.387 beetles from 87 saproxylic species belonging to 21 families. Of these species 51 were not included in the previous checklist of the Park. By comparing the two different techniques used for catching saproxylic beetles, we found a significantly high difference in species richness between Window Traps (WT) and Eclector Traps (ET) with a higher number of species captured in the Window Traps. However, the combined use of two different types of traps significantly expanded the spectrum of insects captured Among the species reported as Least Concern in the IUCN Red List, we found interesting species such as the Elateridae Calambus bipustulats, the Eucnemidae Melasis buprestoides

  19. Energetics of cobalt phosphate frameworks: {alpha}, {beta}, and red NaCoPO{sub 4}

    SciTech Connect

    Le, So-Nhu; Eng, Hank W.; Navrotsky, Alexandra . E-mail: anavrotsky@ucdavis.edu

    2006-12-15

    Thermal behavior, relative stability, and enthalpy of formation of {alpha} (pink phase), {beta} (blue phase), and red NaCoPO{sub 4} are studied by differential scanning calorimetry, X-ray diffraction, and high-temperature oxide melt drop solution calorimetry. Red NaCoPO{sub 4} with cobalt in trigonal bipyramidal coordination is metastable, irreversibly changing to {alpha} NaCoPO{sub 4} at 827 K with an enthalpy of phase transition of -17.4{+-}6.9 kJ mol{sup -1}. {alpha} NaCoPO{sub 4} with cobalt in octahedral coordination is the most stable phase at room temperature. It undergoes a reversible phase transition to the {beta} phase (cobalt in tetrahedra) at 1006 K with an enthalpy of phase transition of 17.6{+-}1.3 kJ mol{sup -1}. Enthalpy of formation from oxides of {alpha}, {beta}, and red NaCoPO{sub 4} are -349.7{+-}2.3, -332.1{+-}2.5, and -332.3{+-}7.2 kJ mol{sup -1}; standard enthalpy of formation of {alpha}, {beta}, and red NaCoPO{sub 4} are -1547.5{+-}2.7, -1529.9{+-}2.8, and -1530.0{+-}7.3 kJ mol{sup -1}, respectively. The more exothermic enthalpy of formation from oxides of {beta} NaCoPO{sub 4} compared to a structurally related aluminosilicate, NaAlSiO{sub 4} nepheline, results from the stronger acid-base interaction of oxides in {beta} NaCoPO{sub 4} (Na{sub 2}O, CoO, P{sub 2}O{sub 5}) than in NaAlSiO{sub 4} nepheline (Na{sub 2}O, Al{sub 2}O{sub 3}, SiO{sub 2}). - Graphical abstract: Relative stability of NaCoPO{sub 4} polymorphs compared to the most stable phase, {alpha} NaCoPO{sub 4}.

  20. Synthesis of BiPO4/Bi2S3 Heterojunction with Enhanced Photocatalytic Activity under Visible-Light Irradiation

    NASA Astrophysics Data System (ADS)

    Lu, Mengna; Yuan, Guotao; Wang, Zuoshan; Wang, Yuyuan; Guo, Jun

    2015-10-01

    BiPO4/Bi2S3 photocatalysts were successfully synthesized by a simple two-step hydrothermal process, which involved the initial formation of BiPO4 rod and then the attachment of Bi2S3 through ion exchange. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (UV-vis DRS). It was found that BiPO4 was regular rods with smooth surfaces. However, BiPO4/Bi2S3 heterojunction had a rough surface, which could be attributed to the attachment of Bi2S3 on the surface of BiPO4 rods. The BiPO4/Bi2S3 composite exhibited better photocatalytic performance than that of pure BiPO4 and Bi2S3 for the degradation of methylene blue (MB) and Rhodamine B (RhB) under visible light. The enhanced photocatalytic performance could be ascribed to synergistic effect of BiPO4/Bi2S3 heterojunction, in which the attached Bi2S3 nanoparticles could improve visible-light absorption and the BiPO4/Bi2S3 heterojunction suppressed the recombination of photogenerated electron-hole pairs. Our work suggested that BiPO4/Bi2S3 heterojunction could be a potential photocatalyst under visible light.

  1. Enhancement of electrochemical behavior of nanostructured LiFePO4/Carbon cathode material with excess Li

    NASA Astrophysics Data System (ADS)

    Bazzi, K.; Nazri, M.; Naik, V. M.; Garg, V. K.; Oliveira, A. C.; Vaishnava, P. P.; Nazri, G. A.; Naik, R.

    2016-02-01

    We have synthesized carbon coated LiFePO4 (C-LiFePO4) and C-Li1.05FePO4 with 5 mol% excess Li via sol-gel method using oleic acid as a source of carbon for enhancing electronic conductivity and reducing the average particle size. Although the phase purity of the crystalline samples was confirmed by x-ray diffraction (XRD), the 57Fe Mössbauer spectroscopy analyses show the presence of ferric impurity phases in both stoichiometric and non-stoichiometric C-LiFePO4 samples. Transmission electron microscopy measurements show nanosized C-LiFePO4 particles uniformly covered with carbon, with average particle size reduced from ∼100 nm to ∼50 nm when excess lithium is used. Electrochemical measurements indicate a lower charge transfer resistance and better electrochemical performance for C-Li1.05FePO4 compared to that of C-LiFePO4. The aim of this work is to systematically analyze the nature of impurities formed during synthesis of LiFePO4 cathode material, and their impact on electrochemical performance. The correlation between the morphology, charge transfer resistance, diffusion coefficient and electrochemical performance of C-LiFePO4 and C- Li1.05FePO4 cathode materials are discussed.

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

    PubMed

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

    2013-09-21

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

  3. Modified solid-state reaction synthesized cathode lithium iron phosphate (LiFePO4) from different phosphate sources.

    PubMed

    Ding, Keqiang; Li, Wenjuan; Wang, Qingfei; Wei, Suying; Guo, Zhanhu

    2012-05-01

    A modified solid-state method was used to prepare LiFePO4. With the aid of deionized water, a mixture containing Fe2O3, NH4H2PO4 (or (NH4)2HPO4), LiOH, glucose and oxalic acid was prepared into fluffy powders, which were heated in a carbon-coated crucible at 700 degrees C for 3 hours to synthesize LiFePO4 without any inert gas flow. For the first time, the roles of NH4H2PO4 and (NH4)2HPO4 on the preparation of LiFePO4 were systematically investigated. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), revealing that the crystallinity of the LiFePO4 sample prepared from NH4H2PO4 is superior to that prepared from (NH4)2HPO4 and the particle size of the sample prepared from NH4H2PO4 is smaller than that prepared from (NH4)2HPO4. The specific capacity, cycle property and rate capabilities were also compared between the as-prepared LiFePO4 samples. A better electrochemical performance was observed in the sample prepared from NH4H2PO4.

  4. Solvothermal synthesis and photoluminescence properties of BiPO{sub 4} nano-cocoons and nanorods with different phases

    SciTech Connect

    Xue Fei; Li Haibo; Zhu Yongchun; Xiong Shenglin; Zhang Xianwen; Wang Tingting; Liang Xin; Qian Yitai

    2009-06-15

    Hexagonal phase BiPO{sub 4} nano-cocoons and monoclinic phase BiPO{sub 4} nanorods have been synthesized in the mixed solvents of glycerol and distilled water with the volume ratio of 2:1 at 200 deg. C. The solvothermal evolution process from hexagonal phase BiPO{sub 4} nano-cocoons to monoclinic phase BiPO{sub 4} nanorods was observed by varying the reaction time from 1 to 3 h. In the hydrothermal condition at 160 deg. C, the similar phase transformation from hexagonal phase BiPO{sub 4} to monoclinic phase BiPO{sub 4} was also observed, accompanying with a morphology transformation from nanorods to octahedron-like microcrystals. It was found that the volume ratio of glycerol to water in the solvothermal condition had a great impact on the shapes of products, while it had no influence on the formation of different phases. The fluorescence spectra of hexagonal phase BiPO{sub 4} nano-cocoons and monoclinic phase BiPO{sub 4} nanorods were also studied. - Graphical abstract: Hexagonal phase BiPO{sub 4} nano-cocoons were fabricated by solvothermal method at 200 deg. C for 1 h. When the reaction time was increased to 3 h, monoclinic phase BiPO{sub 4} nanorods were formed.

  5. Synthesis and structure of Ce1-xEuxPO4 solid solutions for minor actinides immobilization

    NASA Astrophysics Data System (ADS)

    Wang, Xiaohuan; Teng, Yuancheng; Huang, Yi; Wu, Lang; Zeng, Pan

    2014-08-01

    Ce1-xEuxPO4 (x = 0-1) solid solutions were synthesized by the solid state reaction process using europium (Eu) as the surrogate for trivalent minor actinide americium (Am). The effects of calcination temperature, holding time and Eu content on the crystalline phase, microstructure and morphology of Ce1-xEuxPO4 (x = 0-1) were investigated. The monazite-type EuPO4 and CePO4 coexisted after being calcined at 1000 °C for 4 h, suggesting the CePO4 and EuPO4 phases would form initially separately. Pure and single-phase monazite-type Ce1-xEuxPO4 (x = 0-1) powders were obtained at 1300 °C for 4 h. The results of the XRD patterns Rietveld refinement and μ-Raman analysis confirmed the formation of a Ce1-xEuxPO4 (x = 0-1) continuous solid solution. The grain size of Ce0.5Eu0.5PO4 increased obviously as the holding time extended. The Ce, Eu, P and O elements were almost distributed homogeneously in the Ce0.5Eu0.5PO4 solid solution.

  6. Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li4Co(PO4)2

    NASA Astrophysics Data System (ADS)

    Glaum, R.; Gerber, K.; Schulz-Dobrick, M.; Herklotz, M.; Scheiba, F.; Ehrenberg, H.

    2012-04-01

    α-Li4Co(PO4)2 has been synthesized and crystallized by solid-state reactions. The new phosphate crystallizes in the monoclinic system (P21/a, Z=4, a=8.117(3) Å, b=10.303(8) Å, c=8.118(8) Å, β=104.36(8) Å) and is isotypic to α-Li4Zn(PO4)2. The structure of α-Li4Co(PO4)2 has been determined from single-crystal X-ray diffraction data {R1=0.040, wR2=0.135, 2278 unique reflections with Fo>4σ(Fo)}. The crystal structure, which might be regarded as a superstructure of the wurtzite structure type, is build of layers of regular CoO4, PO4 and Li1O4 tetrahedra. Lithium atoms Li2, Li3 and Li4 are located between these layers. Thermal investigations by in-situ XRPD, DTA/TG and quenching experiments suggest decomposition followed by formation and phase transformation of Li4Co(PO4)2: α-Li4Co(PO4)2⟹442 °Cβ-Li3PO4+LiCoPO4⇌773 °Cβ-Li4Co(PO4)2⟹quenching to 25 °Cα-Li4Co(PO4)2 According to HT-XRPD at ϑ=850 °Cβ-Li4Co(PO4)2 (Pnma, Z=2, 10.3341(8) Å, b=6.5829(5) Å, c=5.0428(3) Å) is isostructural to γ-Li3PO4. The powder reflectance spectrum of α-Li4Co(PO4)2 shows the typical absorption bands for the tetrahedral chromophore [CoIIO4].

  7. Structure determination and optical properties of CsSm(PO{sub 3}){sub 4}

    SciTech Connect

    Ben Hassen, N.; Ferhi, M. Horchani-Naifer, K.; Férid, M.

    2015-03-15

    Graphical abstract: Projection of the CsSm(PO{sub 3}){sub 4} structure viewing along the a axis. - Highlights: • Single crystal of a new polyphosphate CsSm(PO{sub 3}){sub 4} has been synthesized. • The obtained compound has been characterized by several techniques. • The crystal structure of CsSm(PO{sub 3}){sub 4} has been resolved. • Spectroscopic properties of Sm{sup 3+} in CsSm(PO{sub 3}){sub 4} have been performed. - Abstract: A new alkali metal-rare earth polyphosphate CsSm(PO{sub 3}){sub 4} has been synthesized by flux method. The obtained compound has been characterized by means of single crystal X-ray diffraction, Fourier transform infrared (FTIR) and Raman scattering spectroscopies. It crystallizes in the monoclinic space group P2{sub 1}/n with the following unit-cell parameters: a = 10.382(2), b = 8.978(6), c = 11.205(4) Å, β = 106.398(3)° and Z = 4. The structure of CsSm(PO{sub 3}){sub 4} is an infinite three-dimensional framework made up of double spiral (PO{sub 3}){sub n} chains linked with neighboring SmO{sub 8} and CsO{sub 11} polyhedra. Spectroscopic properties of Sm{sup 3+} in this new compound including excitation, emission, and kinetic measurement have been performed. The emission spectrum shows four transitions characteristics of Sm{sup 3+} in the orange–red region by excitation wavelength at 400 nm. The decay time curve of {sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} transition has been also registered and fitted to a single exponential function.

  8. Dynamic PROOF clusters with PoD: architecture and user experience

    NASA Astrophysics Data System (ADS)

    Manafov, Anar

    2011-12-01

    PROOF on Demand (PoD) is a tool-set, which sets up a PROOF cluster on any resource management system. PoD is a user oriented product with an easy to use GUI and a command-line interface. It is fully automated. No administrative privileges or special knowledge is required to use it. PoD utilizes a plug-in system, to use different job submission front-ends. The current PoD distribution is shipped with LSF, Torque (PBS), Grid Engine, Condor, gLite, and SSH plug-ins. The product is to be extended. We therefore plan to implement a plug-in for AliEn Grid as well. Recently developed algorithms made it possible to efficiently maintain two types of connections: packet-forwarding and native PROOF connections. This helps to properly handle most kinds of workers, with and without firewalls. PoD maintains the PROOF environment automatically and, for example, prevents resource misusage in case when workers idle for too long. As PoD matures as a product and provides more plug-ins, it's used as a standard for setting up dynamic PROOF clusters in many different institutions. The GSI Analysis Facility (GSIAF) is in production since 2007. The static PROOF cluster has been phased out end of 2009. GSIAF is now completely based on PoD. Users create private dynamic PROOF clusters on the general purpose batch farm. This provides an easier resource sharing between interactive local batch and Grid usage. The main user communities are FAIR and ALICE.

  9. GaPO4 sensors for gravimetric monitoring during atomic layer deposition at high temperatures.

    PubMed

    Elam, J W; Pellin, M J

    2005-06-01

    The quartz crystal microbalance is extremely useful for in situ monitoring of thin-film growth by atomic layer deposition (ALD) in a viscous flow environment. Unfortunately, conventional AT-quartz sensors are limited to growth temperatures below approximately 300 degrees C. Gallium orthophosphate (GaPO4) is an alternative piezoelectric material offering much greater high-temperature frequency stability than AT-quartz (SiO2). Our measurements reveal that the temperature coefficient for Y-11 degrees GaPO4 decreases linearly with temperature reaching 3 Hz/ degrees C at 450 degrees C. In contrast, the temperature coefficient for the SiO2 sensor increases as the cube of the sensor temperature to 650 Hz/ degrees C at 390 degrees C. To examine the effect of temperature fluctuations on the sensor frequency, we exposed the SiO2 and GaPO4 sensors to helium pulses at 400 degrees C. The resulting frequency change measured for the SiO2 sensor was approximately 40 times greater than that of the GaPO4 sensor. Next, we performed Al2O3 ALD using alternating tri-methylaluminum/water exposures at 400 degrees C and monitored the growth using the SiO2 and GaPO4 sensors. The GaPO4 sensor yielded well-defined pulse shapes in agreement with predictions, while the SiO2 pulses were severely distorted. Measurements during TiO2 ALD using alternating titanium tetrachloride/water exposures at 450 degrees C with the GaPO4 sensor also showed well-defined ALD mass steps.

  10. Control of the effective P/O ratio of oxidative phosphorylation in liver mitochondria and hepatocytes.

    PubMed

    Brand, M D; Harper, M E; Taylor, H C

    1993-05-01

    The control exerted by substrate oxidation reactions, by ATP turnover and by the proton leak over the oxygen consumption rate, the phosphorylation rate, the proton leak rate and the protonmotive force (delta p) in isolated rat liver mitochondria under a range of conditions between non-phosphorylating (State 4) and maximum phosphorylation (State 3) was investigated by using the top-down approach of metabolic control analysis. The experiments were carried out with saturating concentrations of the substrates succinate, glutamate with malate, or pyruvate with malate. The distribution of control was very similar with each of the three substrates. The effective P/O ratio (i.e. not corrected for leak reactions) was also measured; it varied from zero in State 4 to 80-90% of the maximum theoretical P/O ratio in State 3. Under most conditions control over the effective P/O ratio was shared between proton leak (which had negative control) and the phosphorylating subsystem (which had roughly equal positive control); near State 4, substrate oxidation reactions also acquired some control over this ratio. In resting hepatocytes the effective P/O ratio was only 50% of its maximum theoretical value, corresponding to an effective P/O ratio of only 1.3 for complete oxidation of glucose. The effective P/O ratio for intracellular mitochondrial oxygen consumption was 64% of the maximum value. The control coefficient of the mitochondrial proton leak over the effective P/O ratio in cells was -0.34; the control coefficient of phosphorylation reactions over this ratio was 0.31 and the control coefficient of substrate oxidation reactions over the ratio was 0.03, showing how the coupling efficiency in cells can respond sensitively to agents that change the proton leak or the ATP demand, but not to those that change substrate oxidation.

  11. Influence of submarine groundwater discharge on (210)Po and (210)Pb bioaccumulation in fish tissues.

    PubMed

    Garcia-Orellana, J; López-Castillo, E; Casacuberta, N; Rodellas, V; Masqué, P; Carmona-Catot, G; Vilarrasa, M; García-Berthou, E

    2016-05-01

    This study presents the results of the accumulation of (210)Po and (210)Pb in fish tissues and organs in a brackish-water marshland that is characterized by high concentrations of (222)Rn and (226)Ra supplied by submarine groundwater discharge (SGD). Tissues and organs from Cyprinus carpio, Chelon labrosus and Carassius auratus in the wetland were significantly enriched by both (210)Pb and (210)Po (up to 55 and 66 times, respectively) compared to blanks. The major input route of (210)Pb and (210)Po into the fish body seems to be through ingestion, due to the high levels of (210)Pb and (210)Po found in the gut content as well as in organs involved in digestion and metabolism (i.e. gut, kidney and hepatopancreas). Results showed that (210)Po was more accumulated in all fish tissues and organs except for the spine, which showed a higher affinity for (210)Pb, due to its capacity to replace Ca from apatite in bones. Over all the variables analyzed, fish tissues/organs and, secondarily, fish species were the most important factors explaining the concentration of radionuclides, whereas fish length and the sampling location played a minor role. The relationship of the two radionuclides varied markedly among tissues and their concentration levels were only correlated in gills, gut and, marginally, in spines. In general, the highest values of (210)Pb and (210)Po concentrations in tissues were found on C. labrosus tissues rather C. auratus and C. carpio. This study demonstrates that inputs of natural radionuclides supplied by SGD to coastal semi-enclosed areas (such as marshlands, lagoons or ponds) may significantly increase the contents of (210)Pb and (210)Po in fish tissues/organs. Thus, this study represents one of the first evidences of direct ecological effects derived from SGD.

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

    PubMed Central

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

    2015-01-01

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

  13. Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

    PubMed

    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 < 0.001) as well as enhanced force generation compared with controls during reperfusion (n = 7; P < 0.05). We also used inhibitors for signaling molecules or membrane channels such as 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.

  14. Hygroscopic and chemical characterisation of Po Valley aerosol

    NASA Astrophysics Data System (ADS)

    Bialek, J.; Dall'Osto, M.; Vaattovaara, P.; Ovadnevaite, J.; Decesari, S.; Laaksonen, A.; O'Dowd, C.

    2013-02-01

    Continental summer-time aerosol in the Italian Po Valley was characterized in terms of hygroscopic properties and the influence of chemical composition therein. The campaign-average minima in hygroscopic growth factors (HGFs) occurred just before and during sunrise from 03:00-06:00, but more generally, the whole night shows very low hygroscopicity, particularly in the smaller particle sizes. The average HGFs increased from 1.18 for the smallest sized particles (35 nm) to 1.38 for the largest sizes (165 nm) for the lowest HGF period while during the day, the HGF gradually increased to achieve maximum values in the early afternoon hours from 12:00-15:00, reaching 1.32 for 35 nm particles and 1.46 for 165 nm particles. Two contrasting case scenarios were encountered during the measurement period: Case 1 was associated with westerly air flow moving at a moderate pace and Case 2 was associated with more stagnant, slower moving air from the north-easterly sector. Case 1 exhibited low diurnal temporal patterns and was associated with moderate non-refractory aerosol mass concentrations (for 50% size cut at 1 μm) of the order of 4.5 μg m-3. For Case 1, organics contributed typically to 50% of the mass. Case 2 was characterized by > 9.5 μg m-3 total mass (< 1 μm) in the early morning hours (04:00), decreasing to ∼ 3 μg m-3 by late morning (10:00) and exhibited strong diurnal changes in chemical composition, particularly in nitrate mass but also in total organic mass concentrations. Organic growth factors (OGFs) exhibited a minimum around 15:00, 1-2 h after the peak in HGF. Particles sized 165 nm exhibited moderate diurnal variability in HGF, ranging from 80% at night to 95% of "more hygroscopic" growth factors (i.e. GF = 1.35-1.9) around noon. The diurnal changes in HGF progressively became enhanced with decreasing particle size, decreasing from 95% "more hygroscopic" growth factor fraction at noon to 10% fraction at midnight, while the "less hygroscopic" growth

  15. Hygroscopic and chemical characterisation of Po Valley aerosol

    NASA Astrophysics Data System (ADS)

    Bialek, J.; Dall Osto, M.; Vaattovaara, P.; Decesari, S.; Ovadnevaite, J.; Laaksonen, A.; O'Dowd, C.

    2014-02-01

    Continental summer-time aerosol in the Italian Po Valley was characterised in terms of hygroscopic properties and the influence of chemical composition therein. Additionally, the ethanol affinity of particles was analysed. The campaign-average minima in hygroscopic growth factors (HGFs, at 90% relative humidity) occurred just before and during sunrise from 03:00 to 06:00 LT (all data are reported in the local time), but, more generally, the hygroscopicity during the whole night is very low, particularly in the smaller particle sizes. The average HGFs recorded during the low HGF period were in a range from 1.18 (for the smallest, 35nm particles) to 1.38 (for the largest, 165 nm particles). During the day, the HGF gradually increased to achieve maximum values in the early afternoon hours 12:00-15:00, reaching 1.32 for 35 nm particles and 1.46 for 165 nm particles. Two contrasting case scenarios were encountered during the measurement period: Case 1 was associated with westerly air flow moving at a moderate pace and Case 2 was associated with more stagnant, slower moving air from the north-easterly sector. Case 1 exhibited weak diurnal temporal patterns, with no distinct maximum or minimum in HGF or chemical composition, and was associated with moderate non-refractory aerosol mass concentrations (for 50% size cut at 1 μ) of the order of 4.5 μg m-3. For Case 1, organics contributed typically 50% of the mass. Case 2 was characterised by >9.5 μg m-3 total non-refractory mass (<1 μ) in the early morning hours (04:00), decreasing to ~3 μg m-3 by late morning (10:00) and exhibited strong diurnal changes in chemical composition, particularly in nitrate mass but also in total organic mass concentrations. Specifically, the concentrations of nitrate peaked at night-time, along with the concentrations of hydrocarbon-like organic aerosol (HOA) and of semi-volatile oxygenated organic aerosol (SV-OOA). In general, organic growth factors (OGFs) followed a trend which was

  16. Synthesis of superior fast charging-discharging nano-LiFePO4/C from nano-FePO4 generated using a confined area impinging jet reactor approach.

    PubMed

    Liu, Xiao-min; Yan, Pen; Xie, Yin-Yin; Yang, Hui; Shen, Xiao-dong; Ma, Zi-Feng

    2013-06-14

    LiFePO4/C nanocomposites with excellent electrochemical performance is synthesized from nano-FePO4, generated by a novel method using a confined area impinging jet reactor (CIJR). When discharged at 80 C (13.6 Ag(-1)), the LiFePO4/C delivers a discharge capacity of 95 mA h g(-1), an energy density of 227 W h kg(-1) and a power density of 34 kW kg(-1).

  17. Preparation and characterization of SnO2 and Carbon Co-coated LiFePO4 cathode materials.

    PubMed

    Wang, Haibin; Liu, Shuxin; Huang, Yongmao

    2014-04-01

    The SnO2 and carbon co-coated LiFePO4 cathode materials were successfully synthesized by solid state method. The microstructure and morphology of LiFePO4 composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscope. The results showed that the SnO2 and carbon co-coated LiFePO4 cathode materials exhibited more uniform particle size distribution. Compared with the uncoated LiFePO4/C, the structure of LiFePO4 with SnO2 and carbon coating had no change. The existence of SnO2 and carbon coating layer effectively enhanced the initial discharge capacity. Among the investigated samples, the one with DBTDL:LiFePO4 molar ratios of 7:100 exhibited the best electrochemical performance.

  18. 210Po and 210Pb disequilibrium in the hydrothermal vent fluids and chimney deposits from Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Hussain, N.; Church, T. M.; Luther, G. W., III; Moore, W. S.

    Significantly deficient 210Po/210Pb activity ratios (0.14±0.14) are measured in the hydrothermal vent fluids collected from Juan de Fuca Ridge. Chimney deposits generally showed <5 dpm of excess 210Po. However, one sample from the outermost layer of a sealed spire yielded >1200 dpm g-1 of excess 210Po.If the observed 210Po-210Pb disequilibrium in vent fluids is a result of 210Po removal by the precipitates, residence time of polonium with respect to its irreversible removal from hot fluids is estimated to be of the order of a few minutes. Alternatively, if the disequilibrium is a result of an insufficient growth of 210Po from in-situ 210Pb following heating, the residence time of hot fluids within the hydrothermal system can be shown to be less than 30 days, which is considerably lower than previously reported values.

  19. Nanosized LiFePO4 cathode materials for lithium ion batteries.

    PubMed

    Gu, Hal-Bon; Jun, Dae-Kyoo; Park, Gye-Choon; Jin, Bo; Jin, En Mei

    2007-11-01

    In this study, we prepared nano-particles of LiFePO4 as cathode material for lithium ion batteries by the solid-state reaction. A simple one-step heat treatment has been employed with control of heating temperature and heated LiFePO4 at 650 degrees C exhibited higher 125 mA h/g of the discharge capacity than 600 degrees C, 700 degrees C. To improve conductivity of the inter-particle, carbon coating was carried out by raw carbon or pyrene as carbon sources and their morphological properties of particles on the carbon coating was compared with by FE-SEM, TEM. From the FE-SEM results, the particles of carbon added LiFePO4 have much smaller size than LiFePO4 as below 300 nm. When adding pyrene (10 wt%), the carbon surrounded non-uniformly with surface of the particles compared with adding raw carbon which wrapped uniformly with carbon web and it was exhibited 152 mA h/g of the discharge capacity on LiFePO4/C composite cells at 10th cycle.

  20. Advanced carbon materials/olivine LiFePO4 composites cathode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gong, Chunli; Xue, Zhigang; Wen, Sheng; Ye, Yunsheng; Xie, Xiaolin

    2016-06-01

    In the past two decades, LiFePO4 has undoubtly become a competitive candidate for the cathode material of the next-generation LIBs due to its abundant resources, low toxicity and excellent thermal stability, etc. However, the poor electronic conductivity as well as low lithium ion diffusion rate are the two major drawbacks for the commercial applications of LiFePO4 especially in the power energy field. The introduction of highly graphitized advanced carbon materials, which also possess high electronic conductivity, superior specific surface area and excellent structural stability, into LiFePO4 offers a better way to resolve the issue of limited rate performance caused by the two obstacles when compared with traditional carbon materials. In this review, we focus on advanced carbon materials such as one-dimensional (1D) carbon (carbon nanotubes and carbon fibers), two-dimensional (2D) carbon (graphene, graphene oxide and reduced graphene oxide) and three-dimensional (3D) carbon (carbon nanotubes array and 3D graphene skeleton), modified LiFePO4 for high power lithium ion batteries. The preparation strategies, structure, and electrochemical performance of advanced carbon/LiFePO4 composite are summarized and discussed in detail. The problems encountered in its application and the future development of this composite are also discussed.

  1. Microwave synthesis of molybdenum doped LiFePO4/C and its electrochemical studies.

    PubMed

    Naik, Amol; P, Sajan C

    2016-05-10

    A Mo-doped LiFePO4 composite was prepared successfully from an iron carbonyl complex by adopting a facile and rapid microwave assisted solid state method. The evolution of gases from the iron precursor produces a highly porous product. The formation and substitution of Mo in LiFePO4 were confirmed by X-ray diffraction; surface analysis was carried out by scanning electron microscopy, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the substituted LiFePO4 were examined by cyclic voltammetry, electrochemical impedance spectroscopy and by recording charge-discharge cycles. It was observed that the as prepared composites consisted of a single phase orthorhombic olivine-type structure, where Mo(6+) was successfully introduced into the M2(Fe) sites. Incorporation of supervalent Mo(6+) introduced Li(+) ion vacancies in LiFePO4. The synthesized material facilitated lithium ion diffusion during charging/discharging due to the charge compensation effect and porosity. The battery performance studies showed that LiMo0.05Fe0.095PO4 exhibited a maximum capacity of 169.7 mA h g(-1) at 0.1 C current density, with admirable stability retention. Even at higher current densities, the retention of the specific capacity was exceptional.

  2. A sequential determination of (90)Sr and (210)Po in food samples.

    PubMed

    Hurtado-Bermudez, S; Mas, J L; Villa-Alfageme, M

    2017-08-15

    The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including (210)Po and (90)Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of (90)Sr and (210)Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For (90)Sr analysis, the method makes use of stable strontium as yield tracer, and (210)Po is determined through self-deposition using (209)Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg(-1) for (90)Sr and (210)Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  4. Experimental and theoretical investigations on the polymorphism and metastability of BiPO4.

    PubMed

    Achary, S N; Errandonea, D; Muñoz, A; Rodríguez-Hernández, P; Manjón, F J; Krishna, P S R; Patwe, S J; Grover, V; Tyagi, A K

    2013-11-14

    In this work we report the metastability and the energetics of the phase transitions of three different polymorphs of BiPO4, namely trigonal (Phase-I, space group P3(1)21), monoclinic monazite-type (Phase-II, space group P2(1)/n) and SbPO4-type monoclinic (Phase-III, space group P2(1)/m) from ambient and non-ambient temperature powder XRD and neutron diffraction studies as well as ab initio density functional theory (DFT) calculations. The symmetry ambiguity between P2(1) and P2(1)/m of the high temperature polymorph of BiPO4 has been resolved by a neutron diffraction study. The structure and vibrational properties of these polymorphs of the three polymorphs have also been reported in detail. Total energy calculations have been used to understand the experimentally observed metastable behavior of trigonal and monazite-type BiPO4. Interestingly, all of the three phases were found to coexist after heating a single phasic trigonal BiPO4 to 773 K. The irreversible nature of these phase transitions has been explained by the concepts of the interplay of the structural distortion, molar volume and total energy.

  5. Controlled synthesis, characterization and photocatalytic activity of BiPO4 nanostructures with different morphologies

    NASA Astrophysics Data System (ADS)

    Cheng, Lang-Wei; Tsai, Jui-Chien; Huang, Tzu-Yun; Huang, Chang-Wei; Unnikrishnan, Binesh; Lin, Yang-Wei

    2014-04-01

    The synthesis of bismuth phosphate (BiPO4) nanostructures with various morphologies and phases was explored under ultrasound irradiation and hydrothermal process. Powder x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (DRS) were used to characterize the BiPO4 samples. The effects of ultrasound irradiation and hydrothermal conditions on the phases and morphologies of the BiPO4 samples were studied, and the growth mechanisms of the 1D structure were investigated. The different BiPO4 samples exhibited different optical properties and photocatalytic activities for the degradation of methyl blue (MB) under UV light irradiation. The experimental results suggest that the high photocatalytic activity of the sample prepared under hydrothermal conditions is due to a low electron and hole recombination rate and the high potential of the photogenerated holes in the valence band. The practicality of this BiPO4 photocatalyst was validated for the degradation of MB in environmental and industrial wastewater samples, which demonstrated the advantages of its high photocatalytic activity.

  6. Ferroelectric instability and topological crystalline insulating nature in PbPo

    NASA Astrophysics Data System (ADS)

    Kang, Chang-Jong; Min, B. I.

    2016-01-01

    We have investigated the lattice instability and the topological property of the electronic structure in PbPo in comparison with other IV-VI semiconductors, SnTe and PbTe. In the conventional exchange-correlation schemes of the density functional theory, the fcc structure of PbPo tends to be unstable in the presence of spin-orbit coupling (SOC) under [111] distortion so as to have a ferroelectric instability. This feature is revealed in the calculated phonon dispersion of PbPo by the phonon softening instability at k =Γ . But, in the modified Becke-Johnson (mBJ) potential scheme, we have shown that the tendency for SOC-driven ferroelectric instability is suppressed, and the fcc structure becomes stabilized. We have demonstrated that PbPo is a semiconductor having a band inversion at k =L , which leads to a topological crystalline insulator (TCI) phase of PbPo, and the TCI and the ferroelectric states coexist for moderate [111] distortions.

  7. Regulation of the activity of the promoter of RNA-induced silencing, C3PO.

    PubMed

    Sahu, Shriya; Williams, Leo; Perez, Alberto; Philip, Finly; Caso, Giuseppe; Zurawsky, Walter; Scarlata, Suzanne

    2017-09-01

    RNA-induced silencing is a process which allows cells to regulate the synthesis of specific proteins. RNA silencing is promoted by the protein C3PO (component 3 of RISC). We have previously found that phospholipase Cβ, which increases intracellular calcium levels in response to specific G protein signals, inhibits C3PO activity towards certain genes. Understanding the parameters that control C3PO activity and which genes are impacted by G protein activation would help predict which genes are more vulnerable to downregulation. Here, using a library of 10(18) oligonucleotides, we show that C3PO binds oligonucleotides with structural specificity but little sequence specificity. Alternately, C3PO hydrolyzes oligonucleotides with a rate that is sensitive to substrate stability. Importantly, we find that oligonucleotides with higher Tm values are inhibited by bound PLCβ. This finding is supported by microarray analysis in cells over-expressing PLCβ1. Taken together, this study allows predictions of the genes whose post-transcriptional regulation is responsive to the G protein/phospholipase Cβ/calcium signaling pathway. © 2017 The Protein Society.

  8. Coating the Conductivity Materials to Improving the Electrochemical Properties of LiFePO4

    NASA Astrophysics Data System (ADS)

    Wang, Wan Lin; Jin, En Mei; Gu, Hal-Bon

    2013-03-01

    LiFePO4 cathode materials were prepared by a solid-state method followed by one-step heat treatment. To improve the electrochemical properties of the LiFePO4, acetylene black (AB), citric acid (CA), and pyrene are added as carbon source, respectively. The cyclic voltammetry (CV), AC impedance and galvanostatic charge/discharge testing results showed that using the LiFePO4-C composite such as the AB carbon source exhibits higher discharge capacity and stability than the other composite. Synthesized LiFePO4-C/Li cells (with AB) showed that initial discharge capacity was 140.65 mA h g-1 and at the 2nd cycle were 145.87 mA h g-1, respectively. Morphology and electrochemical performance of the LiFePO4 cathode materials were investigated. Furthermore, the cell was subjected to current density studies (0.1 mA cm-2) that suggested excellent capacity retention of the cell at 25°C.

  9. PoGOLite - a circumpolar balloon-borne mission for hard X-ray polarimetry

    NASA Astrophysics Data System (ADS)

    Pearce, Mark

    Mark Pearce For the PoGOLite Collaboration. KTH Royal Institute of Technology, Dept. of Physics, Stockholm, Sweden. pearce@kth.se Abstract Emission processes in astrophysical systems can yield polarised hard X-rays. The orientation of the polarisation plane is a powerful probe of the physical environment around compact astrophysical sources. Despite the wealth of sources accessible to polarisation measurements, and the importance of these measurements, it is 40 years since the last dedicated mission for X-ray polarimetry of point sources. PoGOLite is a balloon-borne hard X-ray polarimeter operating in the 25-100 keV energy band. Polarisation is determined using coincident Compton scattering and photo-absorption in a segmented array of plastic scintillators surrounded by a BGO anticoincidence system and a polyethylene neutron shield. PoGOLite was launched from the Esrange Space Center on July 12th 2013 with the Crab nebula and pulsar as primary observation targets. The mission was terminated on July 25th after an almost complete circumpolar flight. The PoGOLite mission was conducted as a collaboration between Swedish, Japanese, Russian and US scientific teams. The PoGOLite circumpolar mission will be reviewed and the outcome of the 2013 flight discussed.

  10. 210Pb and 210Po determination in environmental samples using liquid scintillation counting and alpha spectrometry

    NASA Astrophysics Data System (ADS)

    Pérez Sánchez, D.; Martin Sánchez, A.; Jurado Vargas, M.

    2003-01-01

    A simple radiochemical procedure has been developed to determine 210Pb and 210Po in environmental samples from the same matrix. Sediment samples are decomposed by leaching with mineral acids or by microwave digestion, while water samples are pre-concentrated. One part of the resulting solution, spiked with 209Po, is used for 210Po determination by spontaneous deposition onto nickel disks (α-spectrometry). The other part is assayed for 210Pb, separating the Pb either by anion-exchange (sediment samples), or by solvent extraction (water samples). The 210Pb source is finally prepared by precipitation as oxalate and the chemical recovery determined by gravimetry. The 210Pb activity concentration is determined by liquid scintillation. A standard sediment sample supplied by IAEA and spiked water samples were analysed to check the procedure. The 210Pb and 210Po measurements agreed well with the certifications, deviations being less than 10%. The mean recoveries for Pb and Po were (70±12)% and (77±8%) for sediments, and (70±10)% and (81±7)% for waters, respectively.

  11. Diurnal variations of (218)Po, (214)Pb, and (214)Po and their effect on atmospheric electrical conductivity in the lower atmosphere at Mysore city, Karnataka State, India.

    PubMed

    Pruthvi Rani, K S; Paramesh, L; Chandrashekara, M S

    2014-12-01

    The short-lived radon daughters ((218)Po, (214)Pb, (214)Bi and (214)Po) are natural tracers in the troposphere, in particular near the ground surface. They are electrically charged particles and are chemically reactive. As soon as they are formed they get attached to the aerosol particles of the atmosphere. The behavior of radon daughters is similar to that of aerosols with respect to their growth, transport and removal processes in the atmosphere. The electrical conductivity of the atmosphere is mainly due to the presence of highly mobile ions. Galactic cosmic rays are the main source of ionization in the planetary boundary layer; however, near the surface of the earth, ions are produced mainly by decays of natural radioactive gases emanating from the soil surface and by radiations emitted directly from the surface. Hence the electrical conductivity of air near the surface of the earth is mainly due to radiations emitted by (222)Rn, (218)Po, (214)Pb, (214)Bi and (214)Po, and depends on aerosol concentrations and meteorological parameters. In the present work the diurnal and seasonal variations of radon and its progeny concentrations are studied using Low Level Radon Detection System and Airflow Meter respectively. Atmospheric electrical conductivity of both positive and negative polarities is measured using a Gerdien Condenser. All the measurements were carried out simultaneously at one location in Mysore city (12°N, 76°E), India. The diurnal variation of atmospheric electrical conductivity was found to be similar to that of ion pair production rate estimated from radon and its progeny concentrations with a maximum in the early morning hours and minimum during day time. The annual average concentrations of (222)Rn, (218)Po, (214)Pb, and (214)Po at the study location were found to be 21.46, 10.88, 1.78 and 1.80 Bq m(-3) respectively. The annual average values of positive and negative atmospheric electrical conductivity were found to be 18.1 and 16.6 f S m(-1

  12. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

    SciTech Connect

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

    2016-06-15

    The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.

  13. Synthesis of LiFePO4/Pani/C composite as a cathode material for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Rahayu, Iman; Hidayat, Sahrul; Aryadi, Lutfi

    2016-02-01

    In recent years, LiFePO4 studied intensively as a cathode material for Li-ion batteries because of high theoretical capacity, stability, and environmental friendly. However, its low intrinsic electronic conductivity. One way to improve its conductivity is addition of conductive material. Polyaniline (PANI) is one of the conductive polymer materials that widely studied because its unique physical and chemical properties which can be an insulator and conductor by doping-dedoping processes and has large potential application. The purpose of this research is to improve the conductivity of LiFePO4 with conductive polymer PANI. The method is performed by the addition of LiFePO4 during the polymerization process to form LiFePO4 polyaniline then added to the C-PANI with the addition of mass percent variation of 5%, 10%, 15%, 20% form-LiFePO4 composite PANI-C. In LiFePO4 added during polymerization PANI provide a smooth surface profile after composited with the carbon to LiFePO4-PANI-C compared to LiFePO4-C. LiFePO4-PANI-C composite provided higher conductivity is 18.45×10-4 S/cm compared to LiFePO4-C is 10.48×10-4 S/cm at 20% addition of carbon. This is due to PANI in LiFePO4 is added to the polyaniline polymerization process can act as a conductive adhesive to glue between carbon and LiFePO4.

  14. AgI/Ag3PO4 heterojunction composites with enhanced photocatalytic activity under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Yan, Jia; Wang, Cheng; Xu, Hui; Xu, Yuanguo; She, Xiaojie; Chen, Jiajia; Song, Yanhua; Li, Huaming; Zhang, Qi

    2013-12-01

    AgI/Ag3PO4 hybrids were synthesized via an ion-exchange method. The structures and morphologies of the samples were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL). The results showed that AgI nanoparticles were uniformly distributed on the surface of Ag3PO4 and the heterostructure was formed. DRS of the AgI/Ag3PO4 composites exhibited strong absorbance in Ultraviolet (UV) and visible regions. PL analysis indicated a more efficient separation of electron-hole pairs in the AgI/Ag3PO4 nanocomposites. Under visible light (λ > 400 nm), the photocatalytic activity of the AgI/Ag3PO4 composites for photodegradation of rhodamine B were efficient and much higher than that of the pure Ag3PO4 crystals. The enhancing photocatalytic activity of AgI/Ag3PO4 was attributed to the efficient separation of electron-hole pairs derived from the matching band potentials between AgI and Ag3PO4. A photocatalytic mechanism and the photocatalytic reaction kinetics over AgI/Ag3PO4 hybrid materials were also proposed.

  15. Heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Wan-Sheng; Du, Hong; Wang, Rui-Xia; Wen, Tao; Xu, An-Wu

    2013-03-01

    A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high efficiencies of the photocatalytic activity and the improved stability. With the assistance of Ag3PO4/AgBr/Ag heterostructures, only 8 min and 12 min are taken to completely decompose MO and MB molecules under visible-light irradiation, respectively. Furthermore, the photodegradation rate does not show an obvious decrease during ten successive cycles, indicating that our heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts are extremely stable under visible-light irradiation.A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high

  16. Linear-to-λ-Shape P-O-P Bond Transmutation in Polyphosphates with Infinite (PO3)∞ Chain.

    PubMed

    Wang, Ying; Li, Lin; Han, Shujuan; Lei, Bing-Hua; Abudoureheman, Maierhaba; Yang, Zhihua; Pan, Shilie

    2017-09-05

    A new metal polyphosphate, α-CsBa2(PO3)5, exhibiting the first example of a linear P-O-P bond angle in a one-dimensional (PO3)∞ chain has been reported. Interestingly, α → β phase transition occurs in CsBa2(PO3)5 along with the P-O-P bonds varying from linear to λ-shape, suggesting that α-CsBa2(PO3)5 with unfavorable linear P-O-P bonds is more stable at ambient temperature.

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

    PubMed

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

    2015-06-01

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

  18. Strain accommodation and potential hysteresis of LiFePO 4 cathodes during lithium ion insertion/extraction

    NASA Astrophysics Data System (ADS)

    Zhu, Yujie; Wang, Chunsheng

    Equilibrium potential hysteresis of electrode materials refers to the phenomenon that discharge equilibrium potential is lower than charge equilibrium potential. It is induced by the strain accommodation energy of phase transformation. Taking LiFePO 4 as an example, the equilibrium potential hysteresis and accommodation energy of two LiFePO 4 with different particle sizes were characterized using galvanostatic intermittent titration technique (GITT), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) methods. The LiFePO 4 sample with 40 nm particle size has lower accommodation energy than that of 100 nm LiFePO 4, which is due to a narrower miscibility gap and smaller potential hysteresis of 40 nm LiFePO 4 comparing to 100 nm LiFePO 4. The phase transformation of LiFePO 4 occurs only at potential levels above delithiation (charge) equilibrium potential and below lithiation (discharge) equilibrium potential. No phase transformation occurs when charge/discharge is limited in the potential hysteresis range, i.e. LiFePO 4 behaves like a solid solution in the potential hysteresis range. A reliable EIS can only be obtained when it is performed at the center of potential hysteresis and the potential amplitude does not exceed the range of equilibrium potential hysteresis. The analysis on strain accommodation and potential hysteresis of LiFePO 4 cathodes during Li ion insertion/extraction is also suitable for other phase transformation electrodes.

  19. High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4 and TmPO4

    NASA Astrophysics Data System (ADS)

    Gomis, O.; Lavina, B.; Rodríguez-Hernández, P.; Muñoz, A.; Errandonea, R.; Errandonea, D.; Bettinelli, M.

    2017-03-01

    Zircon-type holmium phosphate (HoPO4) and thulium phosphate (TmPO4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculations indicate that the possible causes that make the zircon structure unstable are mechanical instabilities and the softening of a silent B 1u mode.

  20. High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4 and TmPO4.

    PubMed

    Gomis, O; Lavina, B; Rodríguez-Hernández, P; Muñoz, A; Errandonea, R; Errandonea, D; Bettinelli, M

    2017-03-08

    Zircon-type holmium phosphate (HoPO4) and thulium phosphate (TmPO4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculations indicate that the possible causes that make the zircon structure unstable are mechanical instabilities and the softening of a silent B 1u mode.

  1. In situ carbon coated LiFePO4/C microrods with improved lithium intercalation behavior.

    PubMed

    Bhuvaneswari, D; Kalaiselvi, N

    2014-01-28

    LiFePO4/C microrods consisting of building blocks of interconnected nanoparticles surrounded by a thin and amorphous coating of carbon have been prepared by a customized hydrothermal method. Appreciable discharge capacity values of 168 mA h g(-1) at 0.1 C and 130 mA h g(-1) at 5 C rates have been exhibited by the currently synthesized LiFePO4/C cathode. The study enumerates the feasibility of exploiting the hydrothermal method to prepare an in situ carbon coated LiFePO4/C compound with tunable morphological properties and desirable electrochemical properties observed for up to 100 cycles at a 5 C rate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  3. LiFePO 4/gel/natural graphite cells for the BATT program

    NASA Astrophysics Data System (ADS)

    Striebel, K.; Guerfi, A.; Shim, J.; Armand, M.; Gauthier, M.; Zaghib, K.

    LiFePO 4/gel/natural graphite (NG) cells have been prepared and cycled under a fixed protocol for cycle and calendar life determination. Cell compression of 68 kPa was found to represent an optimal balance between cell impedance and the first cycle losses on the individual electrodes with the gel electrolyte. Cells with a Li anode showed capacities of 160 and 78 mAh/g LiFePO 4 for C/25 and 2 C discharge rates, respectively. Rapid capacity and power fade were observed in the LiFePO 4/gel/NG cells during cycling and calendar life studies. Diagnostic evaluations point to the consumption of cycleable Li though a side reaction as the reason for performance fade with minimal degradation of the individual electrodes.

  4. Ab initio study of pressure induced structural and electronic properties in TmPo

    SciTech Connect

    Makode, Chandrabhan Pataiya, Jagdish; Sanyal, Sankar P.; Panwar, Y. S.; Aynyas, Mahendra

    2015-06-24

    We report an ab initio calculation of pressure induced structural phase transition and electronic properties of Thulium Polonide (TmPo).The total energy as a function of volume is obtained by means of self-consistent tight binding linear muffin-tin-orbital (TB-LMTO) method within the local density approximation (LDA). It is found that TmPo is stable in NaCl-type (B{sub 1}-phase) structure to CsCl-type (B{sub 2}-phase) structure of this compound in the pressure range of 7.0 GPa. We also calculate the lattice parameter (a{sub 0}), bulk modulus (B{sub 0}), band structure and density of states. From energy diagram it is observed that TmPo exhibit metallic behavior. The calculated values of equilibrium lattice parameter and bulk modulus are in general good agreement.

  5. Direct regeneration of recycled cathode material mixture from scrapped LiFePO4 batteries

    NASA Astrophysics Data System (ADS)

    Li, Xuelei; Zhang, Jin; Song, Dawei; Song, Jishun; Zhang, Lianqi

    2017-03-01

    A new green recycling process (named as direct regeneration process) of cathode material mixture from scrapped LiFePO4 batteries is designed for the first time. Through this direct regeneration process, high purity cathode material mixture (LiFePO4 + acetylene black), anode material mixture (graphite + acetylene black) and other by-products (shell, Al foil, Cu foil and electrolyte solvent, etc.) are recycled from scrapped LiFePO4 batteries with high yield. Subsequently, recycled cathode material mixture without acid leaching is further directly regenerated with Li2CO3. Direct regeneration procedure of recycled cathode material mixture from 600 to 800 °C is investigated in detail. Cathode material mixture regenerated at 650 °C display excellent physical, chemical and electrochemical performances, which meet the reuse requirement for middle-end Li-ion batteries. The results indicate the green direct regeneration process with low-cost and high added-value is feasible.

  6. Chemotransduction in the Carotid Body: K+ Current Modulated by Po2 in Type I Chemoreceptor Cells

    NASA Astrophysics Data System (ADS)

    Lopez-Barneo, Jose; Lopez-Lopez, Jose R.; Urena, Juan; Gonzalez, Constancio

    1988-07-01

    The ionic currents of carotid body type I cells and their possible involvement in the detection of oxygen tension (Po2) in arterial blood are unknown. The electrical properties of these cells were studied with the whole-cell patch clamp technique, and the hypothesis that ionic conductances can be altered by changes in Po2 was tested. The results show that type I cells have voltage-dependent sodium, calcium, and potassium channels. Sodium and calcium currents were unaffected by a decrease in Po2 from 150 to 10 millimeters of mercury, whereas, with the same experimental protocol, potassium currents were reversibly reduced by 25 to 50 percent. The effect of hypoxia was independent of internal adenosine triphosphate and calcium. Thus, ionic conductances, and particularly the O2-sensitive potassium current, play a key role in the transduction mechanism of arterial chemoreceptors.

  7. Na7Cr4(P2O7)4PO4

    PubMed Central

    Bourguiba Fakhar, Noura; Zid, Mohamed Faouzi; Driss, Ahmed

    2013-01-01

    The title compound, hepta­sodium tetra­chromium(III) tetra­kis­(diphosphate) orthophosphate, was synthesized by solid-state reaction. Its structure is isotypic with that of Na7 M 4(P2O7)4PO4 (M = In, Al) compounds and is made up from a three-dimensional [(CrP2O7)4PO4]7− framework with channels running along [001]. The three Na+ cations are located in the voids of the framework. One of the cations is situated on a general position, one is equally disordered around a twofold rotation axis and one is on a fourfold rotoinversion axis. The isolated PO4 tetra­hedron of the anionic framework is also situated on the -4 axis. Structural relationships between the title compound and different diphosphates containing MP2O11 units (M = Mo, V) are discussed. PMID:23723751

  8. Mixed-solvent thermal synthesis of porous LiFePO4.

    PubMed

    Pei, Zhenzhao; Zhang, Xia; Gao, Xiang

    2013-04-01

    Porous structure LiFePO4 with pore size from 2 to 15 nm was successfully synthesized in mixed solvents system of glycol and water. By changing stirring time from 5 to 60 min, LiFePO4 morphologies were adjusted and percentage of porous LiFePO4 was higher and higher in sequence. Stirring time is the key cause of controlling morphologies of final products for its influence on diffusion rate of the initial formed particles of final products. Through adjusting this factor, products with specific morphologies and functions can be obtained. The morphologies and microstructures were observed by transmission electron microscopy (TEM), and the phase composition was verified by X-ray diffraction (XRD). This synthetic method provides a new route to obtain porous structure materials.

  9. The microstructure and electrochemical characteristics of LiFePO4/carbon-network composite.

    PubMed

    Cao, Y X; Lu, Z L; Mi, C H

    2012-08-01

    LiFePO4/carbon-network composite was synthesized by a high temperature solid-state method using the natural sawdust as carbon precursor. The microstructure of the as-synthesized sample was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), respectively. The results revealed that the LiFePO4 particles with diameters ranging from 30 to 150 nm were well connected by carbon networks. The electrochemical performance of the composite was characterized using galvanostatic charge-discharge technique. The initial discharge capacity of LiFePO4/carbon-network cathode reached 126 mAh x g(-1) with 0.2 C rate.

  10. Molecular dynamics study on ion diffusion in LiFePO4 olivine materials.

    PubMed

    Zhang, Peixin; Wu, Yanpeng; Zhang, Dongyun; Xu, Qiming; Liu, Jianhong; Ren, Xiangzhong; Luo, Zhongkuan; Wang, Mingliang; Hong, Weiliang

    2008-06-19

    Molecular dynamics (MD) simulations have been employed to investigate the ionic diffusion and the structure of LiFePO 4 cathode material. The results correspond well with the published experimental observations. The simulation results indicated that the diffusion of lithium ions was thermally activated and more significant than those of other ions. Compared with other cathode materials, the shifts of ions were less significant in LiFePO 4. This suggested that LiFePO 4 was more thermally stable. The snapshots of the positions of lithium atoms over a range of the steps provided a microscopic picture and the picture showed the lithium ions migrated through one-dimension channels.

  11. Study on SOC wavelet analysis for LiFePO4 battery

    NASA Astrophysics Data System (ADS)

    Liu, Xuepeng; Zhao, Dongmei

    2017-08-01

    Improving the prediction accuracy of SOC can reduce the complexity of the conservative and control strategy of the strategy such as the scheduling, optimization and planning of LiFePO4 battery system. Based on the analysis of the relationship between the SOC historical data and the external stress factors, the SOC Estimation-Correction Prediction Model based on wavelet analysis is established. Using wavelet neural network prediction model is of high precision to achieve forecast link, external stress measured data is used to update parameters estimation in the model, implement correction link, makes the forecast model can adapt to the LiFePO4 battery under rated condition of charge and discharge the operating point of the variable operation area. The test results show that the method can obtain higher precision prediction model when the input and output of LiFePO4 battery are changed frequently.

  12. Hydrothermal synthesis and luminescent properties of novel ordered sphere CePO(4) hierarchical architectures.

    PubMed

    Yang, Mei; You, Hongpeng; Zheng, Yuhua; Liu, Kai; Jia, Guang; Song, Yanhua; Huang, Yeju; Zhang, Lihui; Zhang, Hongjie

    2009-12-21

    The ordered-sphere CePO(4) hierarchical architectures have been successfully synthesized by a simple hydrothermal method through the controlled growth of the CePO(4) nanorods and self-assemble hierarchical structure under various reaction conditions. The evolution of the morphology of the samples has been investigated in detail. It was found that the coexistence of citric acid and cetaltrimethylammonium bromide in the reaction system plays an important role in the formation of the spherical CePO(4) hierarchical architectures. A possible mechanism of the formation and growth of the hierarchical structure was suggested according to the experimental results and analysis. The effects of the reaction time as well as the variation of the morphologies on the luminescent properties of the products were also studied.

  13. Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

    PubMed

    Uddin, S; Bebhehani, M

    2014-06-01

    This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4). Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Determination of (210)Pb and (210)Po in water using the extractive scintillation cocktail Polex™.

    PubMed

    Landstetter, Claudia; Hiegesberger, Bernd; Sinojmeri, Merita; Katzlberger, Christian

    2014-11-01

    Method validation was performed to achieve the accreditation for our determination method of (210)Pb and (210)Po in water. A Pb(NO3)2 carrier is added to the sample and lead is precipitated with Na2SxH2O. (210)Po is co-precipitated and the extractive scintillation cocktail Polex(™) is used to determine (210)Po and (210)Pb. Uranium is also extracted by Polex(™). It can be removed by washing the precipitate with 1% HNO3. The ingrowth of (210)Pb from (222)Rn during transportation time must be calculated. It has to be subtracted from the original (210)Pb in the sample and taken into account for the calculation of the lower limit of detection.

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

    PubMed

    Chandrashekara, K; Somashekarappa, H M

    2016-08-01

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

  16. Determination of 210Pb and 210Po in seawater and marine particulate matter

    NASA Astrophysics Data System (ADS)

    Fleer, A. P.; Bacon, M. P.

    1984-06-01

    Natural 210Pb and 210Po are determined in seawater and suspended particulate matter by alpha spectrometry with silicon surface-barrier detectors. Procedures used at WHOI include a pre-concentration, based on co-precipitation with cobalt-APDC, which can be carried out at sea. Source preparation is by spontaneous deposition of polonium on silver, with 210Pb being determined by measurement of 210Po ingrowth. Yields are monitored by the addition of 208Po and stable lead tracers. A desk-top computer is programmed to process the alpha spectra and make radioactive growth and decay computations. The accuracy of oceanic 210Pb data is estimated to be ±10%, somewhat worse than the attainable precision.

  17. Ultra-high power capabilities in amorphous FePO4 thin films

    NASA Astrophysics Data System (ADS)

    Gandrud, Knut B.; Nilsen, Ola; Fjellvåg, Helmer

    2016-02-01

    Record breaking electrochemical properties of FePO4 have been found through investigation of the thickness dependent electrochemical properties of amorphous thin film electrodes. Atomic layer deposition was used for production of thin films of amorphous FePO4 with highly accurate thickness and topography. Electrochemical characterization of these thin film electrodes revealed that the thinner electrodes behave in a pseudocapacitive manner even at high rates of Li+ de/intercalation, which enabled specific powers above 1 MW kg-1 FePO4 to be obtained with minimal capacity loss. In addition, a self-enhancing kinetic effect was observed during cycling enabling more than 10,000 cycles at current rates approaching that of a supercapacitor (11s charge/discharge). The current findings may open for construction of ultra-high power battery electrodes that combines the energy density of batteries with the power capabilities of supercapacitors.

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

    PubMed

    Skwarzec, Bogdan; Prucnal, Malgorzata

    2007-01-01

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

  19. Rubidium-cation conductivity of Rb3-2 x Pb x PO4 solid solutions

    NASA Astrophysics Data System (ADS)

    Shekhtman, G. Sh.; Burmakin, E. I.

    2017-07-01

    New Rb3PO4-based ceramic materials with high rubidium-cation conductivity in the Rb3-2 x Pb x PO4 system have been synthesized and studied. Introduction of Pb2+ cations leads to a sharp increase in the conductivity of rubidium orthophosphate due to formation of cation vacancies and, at temperatures 350-550°C, also due to the stabilization of high-temperature cubic modification Rb3PO4. At high temperatures, the electrolytes prepared have very high ion conductivity higher than 10-1 S cm-1 at 700°C, which is higher than the values previously obtained in similar systems with additions of tin and cadmium ions. The factors influencing the transport properties of the materials under study are discussed.

  20. Structural basis for duplex RNA recognition and cleavage by Archaeoglobus fulgidus C3PO

    PubMed Central

    Parizotto, Eneida A; Lowe, Edward D; Parker, James S

    2013-01-01

    Oligomeric complexes of Trax and Translin proteins, known as C3POs, participate in a variety of eukaryotic nucleic acid metabolism pathways including RNAi and tRNA processing. In RNAi in humans and Drosophila, C3PO activates pre-RISC by removing the passenger strand of the siRNA precursor duplex using nuclease activity present in Trax. It is not known how C3POs engage with nucleic acid substrates. Here we identify a single protein from Archaeoglobus fulgidus that assembles into an octamer with striking similarity to human C3PO. The structure in complex with duplex RNA reveals that the octamer entirely encapsulates a single thirteen base-pair RNA duplex inside a large inner cavity. Trax-like subunit catalytic sites target opposite strands of the duplex for cleavage, separated by seven base pairs. The structure provides insight into the mechanism of RNA recognition and cleavage by an archaeal C3PO-like complex. PMID:23353787

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  2. Observation by EPR of trivalent hafnium in LuPO/sub 4/, YPO/sub 4/, and ScPO/sub 4/

    SciTech Connect

    Abraham, M.M.; Boatner, L.A.; Ramey, J.O.

    1985-09-15

    Recent EPR studies of the 4d/sup 1/ configuration ion Zr/sup 3 +/ in the tetragonal-symmetry orthophosphate hosts LuPO/sub 4/, YPO/sub 4/, and ScPO/sub 4/, have led to additional investigations of d/sup 1/ configuration ions associated with unusual valence states of other elements. Single crystals of LuPO/sub 4/, YPO/sub 4/, and ScPO/sub 4/ doped with hafnium were grown and the electron paramagnetic resonance (EPR) spectrum of the 5d/sup 1/ ion Hf /sup 3 +/ was observed in all three cases. EPR signals due to trivalent hafnium were only observed, however, when the doped samples were gamma irradiated at 77 K and maintained at 77 K during the EPR observations. Since there are two odd isotopes of hafnium with different nuclear spins and different natural abundances, identification of the spectrum of Hf /sup 3 +/ was straightforward. Since Hf /sup 3 +/ represents such an unusual valence for hafnium in the solid state, however, this identification was unequivocally verified by preparing crystals doped with isotopically enriched /sup 179/Hf. The spectroscopic splitting factors, g/sub parallel/ and g/sub perpendicular/, and the parallel magnetic hyperfine constants A/sub parallel/ of /sup 177/Hf and /sup 179/Hf were obtained for Hf /sup 3 +/ in all three hosts. A determination of the hyperfine parameters with the applied magnetic field oriented in the perpendicular direction was not carried out due to quadrupole effects. As in the case of Zr/sup 3 +/, the observed electronic g values for Hf /sup 3 +/ could not be accounted for by the standard second-order equations which included the spin-orbit-induced admixture of some other excited orbital levels of the d/sup 1/ configuration into the ground orbital level.

  3. PoLi: A Virtual Screening Pipeline Based On Template Pocket And Ligand Similarity

    PubMed Central

    Roy, Ambrish; Srinivasan, Bharath; Skolnick, Jeffrey

    2015-01-01

    Often in pharmaceutical research, the goal is to identify small molecules that can interact with and appropriately modify the biological behavior of a new protein target. Unfortunately, most proteins lack both known structures and small molecule binders, prerequisites of many virtual screening, VS, approaches. For such proteins, ligand homology modeling, LHM, that copies ligands from homologous and perhaps evolutionarily distant template proteins, has been shown to be a powerful VS approach to identify possible binding ligands. However, if we want to target a specific pocket for which there is no homologous holo template protein structure, then LHM will not work. To address this issue, in a new pocket based approach, PoLi, we generalize LHM by exploiting the fact that the number of distinct small molecule ligand binding pockets in proteins is small. PoLi identifies similar ligand binding pockets in a holo-template protein library, selectively copies relevant parts of template ligands and uses them for VS. In practice, PoLi is a hybrid structure and ligand based VS algorithm that integrates 2D fingerprint-based and 3D shape-based similarity metrics for improved virtual screening performance. On standard DUD and DUD-E benchmark databases, using modeled receptor structures, PoLi achieves an average enrichment factor of 13.4 and 9.6 respectively, in the top 1% of the screened library. In contrast, traditional docking based VS using AutoDock Vina and homology-based VS using FINDSITEfilt have an average enrichment of 1.6 (3.0) and 9.0 (7.9) on the DUD (DUD-E) sets respectively. Experimental validation of PoLi predictions on dihydrofolate reductase, DHFR, using differential scanning fluorimetry, DSF, identifies multiple ligands with diverse molecular scaffolds, thus demonstrating the advantage of PoLi over current state-of-the-art VS methods. PMID:26225536

  4. Evaluation of Cuprimine and Syprine for decorporation of (60)Co and (210)Po.

    PubMed

    Levitskaia, Tatiana G; Creim, Jeffrey A; Curry, Terry L; Luders, Teresa; Morris, James E; Woodstock, Angela D; Levinson, Barry; Thrall, Karla D

    2010-03-01

    The acknowledged risk of deliberate release of radionuclides into local environments by terrorist activities has prompted a drive to improve novel materials and methods for removing internally deposited radionuclides. These decorporation treatments will also benefit workers in the nuclear industry, should an exposure occur. Cuprimine and Syprine are oral therapeutics based on the active ingredients D-penicillamine and N,N'-bis-(2-aminoethyl)-1,2-ethanediamine dihydrochloride, respectively. These therapeutic drugs have been used for several decades to treat Wilson's disease, a genetic defect leading to copper overload, by chelation and accelerated excretion of internally deposited copper. Studies were undertaken to evaluate these FDA-approved drugs for the in vivo decorporation of radioactive cobalt (Co) and polonium (Po) using male Wistar-Han rats. In these studies, Co or Po was administered to animals by IV injection, followed by oral gavage doses of either Cuprimine or Syprine. Control animals received the radionuclide alone. For Co studies, animals received a single dose of Cuprimine or Syprine, while for Po studies animals were repeatedly dosed at 24-h intervals for a total of 5 doses. Results show that Syprine significantly increased urinary elimination and skeletal concentrations of Co compared to controls. While Cuprimine had little effect on total excretion of Co, the skeletal, kidney, liver, muscle, and stomach tissues had significantly lower radioactivity compared to control animals. The low overall excretion of Po made it difficult to reliably measure urinary or fecal radioactivity and draw a definitive conclusion on the effect of Cuprimine or Syprine treatment on excretion. However, Cuprimine treatment was effective at reducing spleen levels of Po compared to controls. Similarly, Syprine treatment produced statistically significant reductions of Po in the spleen and skeletal tissues compared to control animals. Based on these promising findings, further

  5. Research on high rate capabilities B-substituted LiFePO4.

    PubMed

    Wang, Fu; Zhang, Yun; Chen, Chao

    2013-02-01

    LiFePO4 is currently recognized as one of the most promising electrode materials for large-scale application of lithium ion batteries. However, the limitation of rate capability is believed to be intrinsic to this family of compounds due to the existence of larger tetrahedral (PO4)3- unit and quasi-hexagonal close-packed oxygen array. This paper report here a systematic investigation of the enhancement of rate performance by partly substitution of light small triangle oxyanion, (BO3)3-, for the larger tetrahedral (PO4)3- units in LiFePO4. Cathode electrode materials LiFeB(x)P(1_x)O(4-delta), in which X = 0, 3, 6 and 9, mol%, were synthesized by solid-state method. The as-synthesized products were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Electrochemical Measurements. The results showed that 6 mol% of boron substitution had no effect on the structure of LiFePO4 material, but significantly improved its rate performance. The initial discharge capacity of the LiFeB0.06P0.94O(4-delta) sample was 145.62 mAh/g at 0.1 C, and the capacity retention ratios of 81% at 2 C and 76% at 5 C were obtained, demonstrating that a proper amount of boron substitution (lower than 6 mol%) could significantly improve the rate performance of LiFePO4 cathode material.

  6. Speciation of 210Po and 210Pb in air particulates determined by sequential extraction.

    PubMed

    Al-Masri, M S; Al-Karfan, K; Khalili, H; Hassan, M

    2006-01-01

    Speciation of (210)Po and (210)Pb in air particulates of two Syrian phosphate sites with different climate conditions has been studied. The sites are the mines and Tartous port at the Mediterranean Sea. Air filters were collected during September 2000 until February 2002 and extracted chemically using different selective fluids in an attempt to identify the different forms of these two radionuclides. The results have shown that the inorganic and insoluble (210)Po and (210)Pb (attached to silica and soluble in mineral acids) portion was found to be high in both sites and reached a maximum value of 94% and 77% in the mine site and Tartous port site, respectively. In addition, only 24% of (210)Pb in air particulates was found to be associated with organic materials probably produced from the incomplete burning of fuel vehicle and similar activities. Moreover, the (210)Po/(210)Pb activity ratio in air particulates was higher than that in all samples at both sites and varied between 3.85 in November 2000 at Tartous port site and 20 in April 2001 at the mine area. These activity ratios were also higher than the natural levels. The (210)Po/(210)Pb activity ratio was also determined in each portion resulting from the selective extraction and found to be higher than that in most samples. The sources of (210)Po excess in these portions are discussed. Soil suspension, which is common in the dry climate dominant in the area, sea water spray and heating of phosphate ores were considered; polonium is more volatile than the lead compounds at even moderate temperature. Furthermore, variations in the chemical forms of (210)Po and (210)Pb during the year were also investigated. However, the results of this study can also be utilized for dose assessment to phosphate industry workers.

  7. Study of LiFePO 4 cathode materials coated with high surface area carbon

    NASA Astrophysics Data System (ADS)

    Lu, Cheng-Zhang; Fey, George Ting-Kuo; Kao, Hsien-Ming

    LiFePO 4 is a potential cathode material for 4 V lithium-ion batteries. Carbon-coated lithium iron phosphates were prepared using a high surface area carbon to react precursors through a solid-state process, during which LiFePO 4 particles were embedded in amorphous carbon. The carbonaceous materials were synthesized by the pyrolysis of peanut shells under argon, where they were carbonized in a two-step process that occurred between 573 and 873 K. The shells were also treated with a proprietary porogenic agent with the goal of altering the pore structure and surface area of the pyrolysis products. The electrochemical properties of the as-prepared LiFePO 4/C composite cathode materials were systematically characterized by X-ray diffraction, scanning electron microscope, element mapping, energy dispersive spectroscopy, Raman spectroscopy, and total organic carbon (TOC) analysis. In LiFePO 4/C composites, the carbon not only increases rate capability, but also stabilizes capacity. In fact, the capacity of the composites increased with the specific surface area of carbon. The best result was observed with a composite made of 8.0 wt.% with a specific surface area of 2099 m 2 g -1. When high surface area carbon was used as a carbon source to produce LiFePO 4, overall conductivity increased from 10 -8 to 10 -4 S cm -1, because the inhibition of particle growth during the final sintering process led to greater specific capacity, improved cycling properties and better rate capability compared to a pure olivine LiFePO 4 material.

  8. On the variation of the 210Po half-life at low temperature.

    PubMed

    Pierre, S; Cassette, P; Loidl, M; Branger, T; Lacour, D; Le Garrérès, I; Morelli, S

    2010-01-01

    Experiments were performed to verify the possible influence of the temperature and source matrix on the half-life of (210)Po. Since the precise measurement of the activity of an alpha-emitting source at cryogenic temperature is far from trivial, a simpler approach was used: the activity of a (210)Po source was measured at ambient temperature, but in between the measurements, the source was cooled down during a few weeks in a liquid helium Dewar. A (210)Po solid source was prepared by electro-deposition on a silver plate. The activity of this source was first measured at room temperature, using the defined solid angle alpha measurement method. The source was then placed in a specific gastight container inside a liquid helium bath at 4 K during 28 days. Then the source was heated up and measured again using the same instrument in the same geometric conditions. The same experiment was repeated with the source coated with a thin layer of silver, in order to be sure that the radioactive material was fully embedded inside the metallic matrix. Our experiments showed no evidence of (210)Po half-life change at low temperature. A reduction of the half-life of (210)Po by 6.3% at low temperature, as claimed by Raiola et al. (2007), would have lead to a decay-corrected activity reduction of about 1% after 29 days, which would have been easily detectable. The paper describes the steps of this experiment and gives a detailed uncertainty budget for the measurements. The half-life of (210)Po obtained in each measurement is compared with the evaluated value of (138.3763+/-0.0017) d.

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

    PubMed

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

    2007-05-01

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

  10. Rapid determination of (210)Pb and (210)Po in water and application to marine samples.

    PubMed

    Villa-Alfageme, M; Mas, J L; Hurtado-Bermudez, S; Masqué, P

    2016-11-01

    Measurement of radionuclides in marine samples, specifically radioactive pairs disequilibrium, has gained interest lately due to their ability to trace cutting edge biogeochemical processes. In this context, we developed a fast, direct method for determining (210)Pb and (210)Po water through the use of ultra low-level liquid scintillation counting and alpha-particle spectrometry respectively and through Eichrom Sr resins for the Po-Pb separation. For (210)Pb analysis, the method uses stable lead as a yield tracer measured by a robust ICP-MS technique, and (210)Po is determined through self-deposition using the conventional (209)Po yield tracer. The improvements of the method over other techniques are: a) the analysis can be completed within 6 days, simplifying other methods, b) very low limits of detection have been achieved -0.12 and 0.005mBqL(-1) for (210)Pb and (210)Po, respectively - and c) most of the method could be carried out in on-board analysis. We applied the method to different aqueous samples and specifically to marine samples. We determined (210)Pb and (210)Po in the dissolved fraction of Mediterranean Sea water and an estuary at the South-West of Spain. We found that it can be successfully employed to marine samples but we recommend to i) use a minimum of 20L water to measure the (210)Pb in the dissolved phase by LSC and lower volumes to measure total concentrations; ii) wait for (210)Pb and (210)Bi in secular equilibrium and measure the total spectrum to minimise the limit of detection and improve accuracy.

  11. Synthesis and magnetic properties of LiFePO4 substitution magnesium

    NASA Astrophysics Data System (ADS)

    Choi, Hyunkyung; Kim, Min Ji; Hahn, Eun Joo; Kim, Sam Jin; Kim, Chul Sung

    2017-06-01

    LiFe0.9Mg0.1PO4 sample was prepared by using a solid-state reaction method, and the temperature-dependent magnetic properties of the sample were studied. The X-ray diffraction (XRD) pattern showed an olivine-type orthorhombic structure with space group Pnma based on Rietveld refinement method. The effect of Mg substitution in antiferromagnetic LiFe0.9Mg0.1PO4 was investigated using a vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. The temperature-dependence of the magnetization curves of LiFe0.9Mg0.1PO4 shows abnormal antiferromagnetic behavior with ordering temperature. Sudden changes in both the magnetic hyperfine field (Hhf) and its slope below 15 K suggest that magnetic phase transition associated to the abrupt occurrence of spin-reorientation. The Néel temperature (TN) and spin-reorientation temperature (TS) of LiFe0.9Mg0.1PO4 are lower than those of pure LiFePO4 (TN = 51 K, TS = 23 K). This is due to the Fe-O-Fe superexchange interaction being larger than that of the Fe-O-Mg link. Also, we have confirmed a change in the electric quadrupole splitting (ΔEQ) by the spin-orbit coupling effect and the shape of Mössbauer spectrum has provided the evidence for TS and a strong crystalline field. We have found that Mg ions in LiFe0.9Mg0.1PO4 induce an asymmetric charge density due to the presence of Mg2+ ions at the FeO6 octahedral sites.

  12. 210Po and 210Pb distributions and residence times in the nearshore region of Lake Superior

    NASA Astrophysics Data System (ADS)

    Chai, Yingtao; Urban, Noel R.

    2004-10-01

    The naturally occurring radionuclide, 210Pb, and its decay daughter, 210Po, were measured in the Keweenaw Peninsula region of Lake Superior. Water, suspended particles, sediment trap material (settling particles), and sediment cores and grab samples were collected along three transects that stretched from 1 to 20 km from shore. Departures from secular equilibrium (activity ratio of 210Po:210Pb = 1) were observed for most samples. 210Po-deficiency was observed in both suspended particles (TSP) with a ratio of 0.43 ± 0.05 (±95% confidence interval (CI)) and settling particles with a ratio of 0.57 ± 0.04; higher ratios in the settling particles resulted from an admixture of resuspended sediments. Ratios in the dissolved phase were 0.45 ± 0.12. Approximately 83% and 85% of total 210Po and 210Pb in the water column was in the particulate phase. No evidence of biological uptake of Po was found. Seasonal and spatial variability in activities and ratios was small. Using steady state solutions to the mass balance equations for both isotopes, similar residence times in the water column were calculated for 210Po and 210Pb (55 ˜ 75 days in a 150-m-deep water column). It was possible to calibrate a one-box model for the paired isotopes so that the model output closely matched rates of sediment and isotope resuspension estimated from sediment traps. However, this calibration required a fractionation of the isotopes during resuspension. The particle settling velocity was estimated to be 2.3 m d-1, which also is in agreement with the estimate (2.4 ± 2.2 m d-1) from sediment traps. These results indicate rapid fluxes of radioisotopes and sediments through the water column largely driven by resuspension of sediments in nearshore areas.

  13. Thermochronology of the PoSen complex, northern Vietnam: Implications for tectonic evolution in SE Asia

    NASA Astrophysics Data System (ADS)

    Wang, Pei-Ling; Lo, Ching-Hua; Lan, Ching-Ying; Chung, Sun-Lin; Lee, Tung-Yi; Nam, Tran Ngoc; Sano, Yuji

    2011-03-01

    The PoSen complex, located closely adjacent to the southwestern margin of the Red River shear zone represents the uplifted basement of north Vietnam and may record the motion of the shear zone. However, its thermochronological history has not been fully examined yet. Here we applied U-Pb and 40Ar/ 39Ar dating methods to reveal its thermochronological history. U-Pb analysis of composite zircon grains by TIMS yielded an average age of 760 ± 25 Ma, clustering on the concordia line. Twelve SHRIMP U-Pb analyses also yielded a consistent result of 751 ± 7 Ma. Along with the geochemical features, the U-Pb dating results suggest the PoSen complex was a late Proterozoic magmatic complex, which could correspond to the Chengjiang orogeny, a widespread thermal event in southwest China. Results of 40Ar/ 39Ar dating of micas and K-feldspars were in the range of 36-30 Ma, revealing a rapid cooling and exhumation history of the PoSen complex during the late Paleogene. The time span of cooling and exhumation of the PoSen complex is slightly older than the main cooling phases of the Ailao Shan-Red River (ASRR) metamorphic massifs (28-17 Ma), but is synchronous with the early igneous activity stage in the eastern Indo-Asian collision zone of southeast China and north Vietnam. Owing to the ongoing debate about the initiation and offset of the ASRR shear zone, the tectonic force for the late Paleogene cooling of the PoSen complex is still inconclusive. The rapid exhumation of the PoSen complex could be in response to either the detachment of the Neo-Tethyan slab or a transpressional phase of continental subduction along the ASRR shear system in the eastern Indo-Asian collision zone.

  14. (H3O)Ca2Zn3.5(PO4)4 and Ba2Cd3(PO4)2(HPO4)2: Syntheses, crystal structures and characterizations of two mixed metal phosphates

    NASA Astrophysics Data System (ADS)

    Chang, Tong-Ying; Hu, Chun-Li; Yan, Dong; Mao, Jiang-Gao

    2017-07-01

    Two new phosphates, non-centrosymmetric (NCS) (H3O)Ca2Zn3.5(PO4)4 and centrosymmetric (CS) Ba2Cd3(PO4)2(HPO4)2 have been prepared by hydrothermal reactions. The single-crystal X-ray structural analyses have shown that they crystallized in space group P-421c and P21/c, respectively·(H3O)Ca2Zn3.5(PO4)4 features a three-dimensional (3D) network structure composed of ZnO4 and PO4 tetrahedra that are interconnected via corner-sharing, forming 1D channels of 6-MRs and 8-MRs which are filled by Ca2+ and H3O+ cations, respectively. Ba2Cd3(PO4)2(HPO4)2 features a layered [Cd3(PO4)2(HPO4)2]4- composed of 1D chain of edge-sharing CdO6 octahedra that are further bridged by PO4 tetrahedra with Ba2+ cations filling the interlayer spaces. Luminescent studies suggest that (H3O)Ca2Zn3.5(PO4)4 emits blue light. Optical diffuse reflectance spectra show the experimental band gaps for (H3O)Ca2Zn3.5(PO4)4 and Ba2Cd3(PO4)2(HPO4)2 are 5.67 eV and 5.68 eV, respectively. The UV cut-off edge of title compounds are around at 218 nm·(H3O)Ca2Zn3.5(PO4)4 exhibits a very weak SHG response.

  15. Determination of the Lamb-Moessbauer factors of LiFePO{sub 4} and FePO{sub 4} for electrochemical in situ and operando measurements in Li-ion batteries

    SciTech Connect

    Aldon, L.

    2010-01-15

    {sup 57}Fe Moessbauer spectroscopy is a powerful tool to investigate redox reactions during in electrochemical lithium insertion/extraction processes. Electrochemical oxidation of LiFe{sup II}PO{sub 4} (triphylite) in Li-ion batteries results in Fe{sup III}PO{sub 4} (heterosite). LiFePO{sub 4} was synthesized by solid state reaction at 800 deg. C under Ar flow from Li{sub 2}CO{sub 3}, FeC{sub 2}O{sub 4}.2H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} precursors in stoichiometric composition. FePO{sub 4} was prepared from chemical oxidation of LiFePO{sub 4} using bromine as oxidative agent. For both materials a complete {sup 57}Fe Moessbauer study as a function of the temperature has been carried out. The Debye temperatures are found to be theta{sub M}=336 K for LiFePO{sub 4} and theta{sub M}=359 K for FePO{sub 4}, leading to Lamb-Moessbauer factors f{sub 300K}=0.73 and 0.77, respectively. These data will be useful for a precise estimation of the relative amounts of each species in a mixture. - Graphical abstract: Relative amount of FePO{sub 4} obtained by Moessbauer and electrochemical data. We have corrected Moessbauer spectral intensities with our f factor of both LiFePO{sub 4} and FePO{sub 4}. Open (filled) squares correspond to values obtained during charging (discharging) process. The dashed line, given as a guideline for the eye, corresponds to the ideal case were amounts deduced from different experimental measurements are equal.

  16. Using Eu(3+) as an atomic probe to investigate the local environment in LaPO4-GdPO4 monazite end-members.

    PubMed

    Huittinen, Nina; Arinicheva, Yulia; Schmidt, Moritz; Neumeier, Stefan; Stumpf, Thorsten

    2016-12-01

    In the present study, we have investigated the luminescent properties of Eu(3+) as a dopant in a series of synthetic lanthanide phosphates from the monazite group. Systematic trends in the spectroscopic properties of Eu(3+) depending on the size of the host cation and the dopant to ligand distance have been observed. Our results show that the increasing match between host and dopant radii when going from Eu(3+)-doped LaPO4 toward the smaller GdPO4 monazite decreases both the full width at half maximum of the Eu(3+) excitation peak, as well as the (7)F2/(7)F1 emission band intensity ratio. The decreasing Ln⋯O bond distance within the LnPO4 series causes a systematic bathochromic shift of the Eu(3+) excitation peak, showing a linear dependence of both the host cation size and the Ln⋯O distance. The linear relationship can be used to predict the energy band gap for Eu(3+)-doped monazites for which no Eu(3+) luminescent data is available. Finally, mechanisms for metal-metal energy transfer between host and dopant lanthanides have been explored based on recorded luminescence lifetime data. Luminescence lifetime data for Eu(3+) incorporated in the various monazite hosts clearly indicated that the energy band gap between the guest ion emission transition and the host ion absorption transition can be correlated to the degree of quenching observed in these materials with otherwise identical geometries and chemistries.

  17. Synthesis of Microspherical LiFePO4-Carbon Composites for Lithium-Ion Batteries

    PubMed Central

    Yu, Linghui; Cai, Dandan; Wang, Haihui; Titirici, Maria-Magdalena

    2013-01-01

    This paper reports an “all in one” procedure to produce mesoporous, micro-spherical LiFePO4 composed of agglomerated crystalline nanoparticles. Each nanoparticle is individually coated with a thin glucose-derived carbon layer. The main advantage of the as-synthesized materials is their good performance at high charge-discharge rates. The nanoparticles and the mesoporosity guarantee a short bulk diffusion distance for both lithium ions and electrons, as well as additional active sites for the charge transfer reactions. At the same time, the thin interconnected carbon coating provides a conductive framework capable of delivering electrons to the nanostructured LiFePO4. PMID:28348343

  18. Nanocomposites with Ca and PO4 release: Effects of reinforcement, dicalcium phosphate particle size and silanization

    PubMed Central

    Xu, Hockin H. K.; Weir, Michael D.; Sun, Limin

    2009-01-01

    Objectives Nano-particles of dicalcium phosphate anhydrous (DCPA) were synthesized in our laboratory for the first time and incorporated into a dental resin. Our goal was to develop a mechanically strong dental composite that has Ca and PO4 ion release to combat tooth caries, and to investigate the effects of whisker reinforcement, DCPA particle size and silanization. Methods DCPA nano-particles and two larger DCPA particles were used with nano-silica-fused whiskers as fillers in a resin matrix. Composite mechanical properties were measured via three-point flexure, and the release of Ca and PO4 ions were measured vs. time. Results Using DCPA nano-particles with a diameter of 112 nm, the composite at a DCPA:whisker mass ratio of 1:1 had a flexural strength (mean ± sd; n = 5) of (112 ± 17) MPa, not significantly different from (112 ± 14) MPa of a commercial non-releasing composite; both were higher than (29 ± 7) MPa for the composite at DCPA:whisker of 1:0 (p < 0.05). The composite with DCPA particle size of 112 nm released Ca to a concentration of 0.85 mmol/L and PO4 of 3.48 mmol/L, higher than Ca of 0.67 mmol/L and PO4 of 1.11 mmol/L using DCPA with 12 μm particle size (p < 0.05). Silanization of DCPA increased the composite strength at DCPA:whisker of 1:0 compared to that without silanization, but decreased the Ca and PO4 release (p < 0.05). Increasing the DCPA particle surface area increased the Ca and PO4 release. Significance Decreasing the DCPA particle size increased the Ca and PO4 release; whisker reinforcement increased the composite strength by 2 to 3 fold. The nano DCPA-whisker composites, with high strength and Ca and PO4 release, may provide the needed, unique combination of stress-bearing and caries-inhibiting capabilities. PMID:17339048

  19. TL-OSL study of Li{sub 3}PO{sub 4}: Mg, Cu phosphor

    SciTech Connect

    Rahangdale, S. R. Wankhede, S. P.; Dhabekar, B. S.; Palikundwar, U. A.; Moharil, S. V.

    2015-08-28

    In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li{sub 3}PO{sub 4} phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li{sub 3}PO{sub 4} shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  1. Rising from the Dead: the Revival of the EUVE E/PO

    NASA Astrophysics Data System (ADS)

    Cullison, J. L.; Craig, N.; Stroozas, B. A.; Malina, R. F.

    2000-05-01

    NASA's Extreme Ultraviolet Explorer (EUVE) is dedicated to gathering data on our sky via instrumentation sensitive to the region of light between 76 and 760 angstroms. Since the all-sky survey was completed in 1993, astronomers have made studies of selected objects with EUVE to determine their physical properties and chemical compositions. Also, they have learned about the conditions that prevail and the processes at work in stars, planets, and other sources of EUV radiation. In its pre-launch and early prime mission, EUVE had a thriving education and public outreach (E/PO) program formed expressly to spread the word on recent EUVE findings, but due to budgetary restraints in its extended mission, the project has been unable in recent years to support extensive E/PO efforts. Now in it's eighth year of operation, the EUVE Project has revived its E/PO efforts without significantly impacting its shoe-string budget. Web sites are being reconstructed, including sophisticated interactive learning environments where elementary through college level students, teachers, and the general public can select from lesson plans including, for example, an introductory astronomical module on the relationship between spectra and object classification, download three-dimensional cutouts of the EUVE skymap, view a slide show on the history and instrumentation of the satellite, take a virtual tour of the EUVE observatory, find where EUVE is in its orbit, and catch up on EUVE's most recent news and events. EUVE's revived internet E/PO presence is supplemented with staff and technical support (up to 10% of each staff person's time) of hands-on elementary and community projects coordinated by the UC Berkeley Center for Science Education (the now independent offshoot of the original EUVE E/PO). All elements of the EUVE E/PO are supported without impacting the efficient and highly productive science goals of the small-staffed mission. Additional EUVE E/PO efforts in the works include

  2. The influence of intruder states in even-even Po isotopes

    SciTech Connect

    García-Ramos, J. E.; Heyde, K.

    2015-10-15

    We study the role of intruder states and shape coexistence in the even-even {sup 190–206}Po isotopes, through an interacting boson model with configuration mixing calculation. We analyzed the results in the light of known systematics on various observable in the Pb region, paying special attention to the unperturbed energy systematics and quadrupole deformation. We find that shape coexistence in the Po isotopes behaves in very much the same way as in the Pt isotopes, i.e., it is somehow hidden, contrary to the situation in the Pb and the Hg isotopes.

  3. Indentation recovery in GdPO4 and observation of deformation twinning

    DOE PAGES

    Wilkinson, Taylor M.; Musselman, Matthew A.; Boatner, Lynn A.; ...

    2016-09-30

    A series of nanoindentation tests on both single and polycrystalline specimens of a monazite rare-earth orthophosphate, GdPO4, revealed frequent observation of anomalous unloading behavior with a large degree of recovery, where previously this behavior had only been observed in xenotime-structure rare-earth orthophosphates. An indentation site in the polycrystalline sample was examined using TEM to identify the deformation mechanism responsible for recovery. Finally, the presence of a twin along the (100) orientation, along with a series of stacking faults contained within the deformation site, provide evidence that the mechanism of recovery in GdPO4 is the collapse of deformation twins during unloading.

  4. Optical characterization of the new nanocomposite SBMA/Eu(TTA)3(Ph3PO)2

    NASA Astrophysics Data System (ADS)

    Bordian, Olga; Verlan, Victor; Culeac, Ion; Iovu, Mihail; Zubareva, Vera; Nistor, Iurie

    2015-02-01

    We describe a new nanocomposite material based on the copolymer of styrene with butyl methacrylate (1:1) (SBMA), and coordinating compound of Europium(III) Eu(TTA)3(Ph3PO)2. The SBMA/Eu(TTA)3(Ph3PO)2 nanocomposite was prepared by a simple technology and can be obtained in the form of optical fibers, thin films and planar waveguides on various substrates with large area. Experimental results on optical transmission and photoluminescence spectroscopy are presented. The nanocomposite exhibits a strong photoluminescence emission in the range 560-750 nm, with the main photoluminescence band at 613 nm.

  5. PoGOLite - a Balloon-Borne X-Ray Polarimeter

    NASA Astrophysics Data System (ADS)

    Pearce, M.

    2012-08-01

    PoGOLite is a balloon-borne soft gamma-ray (X-ray) polarimeter operating in the 25-80 keV energy band. The polarisation of incoming photons is determined using Compton scattering and photo-absorption events reconstructed in an array of plastic scintillator detector cells surrounded by a BGO side anticoincidence shield and a polyethylene neutron shield. Observations take place from a stratospheric balloon operating at an altitude of ˜40 km. A custom attitude control system keeps the polarimeter field-of-view aligned to targets of interest. The maiden `pathfinder' flight of PoGOLite took place from the Esrange Space Centre in July 2011.

  6. UV-light driven photocatalytic performance of hydrothermally-synthesized hexagonal CePO4 nanorods

    NASA Astrophysics Data System (ADS)

    Zhu, Zhongqi; Zhang, Ke; Zhao, Heyun; Zhu, Jing

    2017-10-01

    Hexagonal CePO4 nanorods were synthesized via a simple hydrothermal method without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectroscopy. UV-light driven photocatalytic activities of hexagonal CePO4 nanorods were detailedly demonstrated via degrading different organic dyes such as congo red (CR), organic rhodamine B (RB), methyl orange (MO) and methylene blue (MB) since these nanorods exhibit strong UV absorption with the cutoff edge of about 420 nm.

  7. Carbon Surface Layers on a High-Rate LiFePO4

    SciTech Connect

    Gabrisch, Heike; Wilcox, James D.; Doeff, Marca M.

    2005-09-06

    Transmission electron microscopy (TEM) was used to image particles of a high-rate LiFePO4 sample containing a small amount of in situ carbon. The particle morphology is highly irregular, with a wide size distribution. Nevertheless, coatings, varying from about 5-10 nm in thickness, could readily be detected on surfaces of particles as well as on edges of agglomerates. Elemental mapping using Energy Filtered TEM (EFTEM) indicates that these very thin surface layers are composed of carbon. These observations have important implications for the design of high-rate LiFePO4 materials in which, ideally, a minimal amount of carbon coating is used.

  8. TEM Studies of Carbon Coated LiFePO4 after Charge DischargeCycling

    SciTech Connect

    Gabrisch, H.; Wilcox, J.; Doeff, M.

    2006-11-30

    Carbon coating has proven to be a successful approach toimprove the rate capability of LiFePO4 used in rechargeable Li-ionbatteries. Investigations of the microstructure of carbon coated LiFePO4after charge discharge cycling shows that the carbon surface layerremains intact over 100 cycles. We find micro cracks in the cycledmaterial that extend parallel to low indexed lattice planes. Ourobservations differ from observations made by other authors. However thedifferences between the orientations of crack surfaces in both studiescan be reconciled considering the location of weak bonds in the unit celland specimen geometry as well as elastic stress fields ofdislocation.

  9. Electrical conductivity studies of graphene wrapped nanocrystalline LiMnPO{sub 4} composite

    SciTech Connect

    Cheruku, Rajesh; D, Surya Bhaskaram; Govindaraj, G.; Vijayan, Lakshmi

    2015-06-24

    Nanocrystalline LiMnPO{sub 4} material was synthesized by template free sucrose assisted hydrothermal method. The material possesses the orthorhombic crystal structure with Pnma, space group having four formula units. The GO was prepared by the hummer’s method and it was reduced graphene oxide (rGO) with hydrazine hydrate in the presence of nitrogen atmosphere. LiMnPO{sub 4} material was wrapped by the rGO to increase its conductivity. The structural characterization was accomplished through X-ray diffraction, FT-IR and Raman spectroscopy. Morphology was identified by the SEM, Electrical characterization was done through impedance spectroscopy and the results were reported.

  10. Passive detector for measurement of the implanted (sup 210)Po activity in glass

    NASA Astrophysics Data System (ADS)

    Meesen, G.; Uyttenhove, J.; Poffijn, A.; van Laere, K.; Buysse, J.

    1994-08-01

    It is a well known fact that radon is the most important factor in the natural radiation background. For complete dose calculations we need information about the radon concentration up to 25 years ago. As suggested by C. Samuelsson et al. in 1988, the activity of the implanted radon daughter (sup 210)Po can be used to reconstruct the radon activity over the past decades. For large scale surveys in dwellings a passive detector based on polycarbonate foils has been investigated. This system has a sufficient sensitivity to detect (sup 210)Po levels down to 1 Bq/m(sup 2) with a 6 month measuring period.

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

    PubMed

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

    2014-02-01

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

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

    PubMed

    Planinšek, P; Benedik, L; Smodiš, B

    2013-11-01

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

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

    PubMed

    Skwarzec, Bogdan; Jahnz, Anna

    2007-12-01

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

  14. Fission barriers for Po nuclei produced in complete fusion reactions with heavy ions

    SciTech Connect

    Sagaidak, R. N.; Andreyev, A. N.

    2009-05-15

    Evaporation residues and fission excitation functions obtained in complete fusion reactions leading to Po compound nuclei have been analyzed in the framework of the standard statistical model. Macroscopic fission barriers deduced from the cross-section data analysis are compared with the predictions of various theoretical models and available data. A drop in the Po barriers with the decrease in a neutron number was found, which is stronger than predicted by any theory. The presence of entrance channel effects and collective excitations in the compound nucleus decay is considered as a possible reason for the barrier reduction.

  15. Measurement of the {sup 214}Po half-life by the DEVIS track setup

    SciTech Connect

    Belov, V. A.; Brakhman, E. V.; Zeldovich, O. Ya.; Karelin, A. K.; Kirichenko, V. V.; Kobyakin, A. S. Kozodaeva, O. M.; Kuchenkov, A. V.; Tsvetkova, T. N.

    2013-04-15

    Measurement of the {sup 214}Po half-life with the DEVIS track setup at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) by means of a procedure based on determining lifetimes of individual nuclei is described. The value obtained for the {sup 214}Po half-life is 163.8 {+-} 3.0 Micro-Sign s. The possibility of reaching the accuracy of the measurements that is required for testing the statement that the decay of some nuclei has a nonexponential character and the source intensity necessary for this are discussed.

  16. {alpha} transitions to coexisting 0{sup +} states in Pb and Po isotopes

    SciTech Connect

    Xu Chang; Ren Zhongzhou

    2007-04-15

    The {alpha}-transitions ({delta}l=0) to ground and first excited 0{sup +} states in neutron deficient Pb and Po isotopes are systematically analyzed by the density-dependent cluster model. The magnitude of nuclear deformation of the coexisting 0{sub 1}{sup +} and 0{sub 2}{sup +} states is extracted directly from the experimental {alpha}-decay energies and half-lives. The phenomenon of shape coexistence around the Z=82 shell closure is clearly demonstrated in our present analysis. The obtained deformation values from Rn {yields} Po {yields} Pb decay chains are generally consistent with both the available experimental and theoretical studies.

  17. The Digital Universe Coalition: Building a Prototype NVO E/PO Portal

    NASA Astrophysics Data System (ADS)

    Mendez, B.; Craig, N.; Haisch, B.; Lindblom, J.; Hanisch, R.; Summers, F.; Abbott, B.

    2004-05-01

    The National Virtual Observatory (NVO) holds tremendous potential for Education and Public Outreach (E/PO) opportunities. The possibilities for E/PO with the NVO, which promises to make widely available the great majority of the world's astronomical data, are too numerous for any one E/PO effort to ever hope to develop. Therefore, it is critical that the NVO E/PO program develop an infrastructure and tools flexible enough that any E/PO program can make use of it. In response to the recommendations of the NVO science definition team, UC Berkeley's SEGway program conducted needs assessment surveys of potential non-traditional (i.e. non-scientist) NVO user communities. The SEGway team wished to use the results of these surveys to design a demonstration website that could show some of the potential capabilities of NVO E/PO. SEGway established an informal partnership with STScI, AMNH/Hayden Planetarium, and ManyOne Network to explore how to assemble the infrastructure and tools for NVO E/PO and to construct a demonstration portal that makes use of NVO resources. We called this partnership The Digital Universe Coalition. This prototype displays AMNH/Hayden's Digital Universe star catalog of approximately 100,000 stars, based largely on HIPPARCOS parallaxes, in a virtual three-dimensional space. Three types of user-interactive data display and/or navigation are possible: an Earth-based view of the sky with the option of displaying constellations; a spaceship-based view moving through space; and a "god's-eye" view of the local neighborhood from an external vantage point. One key feature of this demo is the linking of user-selectable locations in the sky to the online Digitized Sky Survey data sets. A second feature is a set of links for educational content on a handful of selected objects. Both of these capabilities will be extended further as we plan to begin development of a much more robust and complete E/PO portal for the NVO.

  18. Delithiation kinetics study of carbon coated and carbon free LiFePO4

    NASA Astrophysics Data System (ADS)

    Lepage, D.; Sobh, F.; Kuss, C.; Liang, G.; Schougaard, S. B.

    2014-06-01

    A chemical oxidation method was employed to measure the kinetics of lithium release from LiFePO4 during oxidation. Similar to potential step measurements, the chemical method simplifies quantification compared to the common electrochemical techniques (PITT, GITT etc.). It was found that the overall release of lithium fits one dimensional diffusion kinetics, however, it is also shown that the mechanism must be more complex as the derived activation energy led to an unusually low attack rate of ∼108 Hz. A comparison of carbon coated/carbon free LiFePO4 samples indicated that the carbon coating has only a marginal effect on the delithiation kinetics.

  19. Electrical conductivity studies of graphene wrapped nanocrystalline LiMnPO4 composite

    NASA Astrophysics Data System (ADS)

    Cheruku, Rajesh; D, Surya Bhaskaram; Govindaraj, G.; Vijayan, Lakshmi

    2015-06-01

    Nanocrystalline LiMnPO4 material was synthesized by template free sucrose assisted hydrothermal method. The material possesses the orthorhombic crystal structure with Pnma, space group having four formula units. The GO was prepared by the hummer's method and it was reduced graphene oxide (rGO) with hydrazine hydrate in the presence of nitrogen atmosphere. LiMnPO4 material was wrapped by the rGO to increase its conductivity. The structural characterization was accomplished through X-ray diffraction, FT-IR and Raman spectroscopy. Morphology was identified by the SEM, Electrical characterization was done through impedance spectroscopy and the results were reported.

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

    NASA Technical Reports Server (NTRS)

    1994-01-01

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

  1. Structural and Conductivity Studies on Lanthanum Doped LiNiPO4 Prepared by Polyol Method

    NASA Astrophysics Data System (ADS)

    Karthickprabhu, S.; Hirankumar, G.; Maheswaran, A.; Bella, R. S. Daries; Sanjeeviraja, C.

    2013-07-01

    Pure and Lanthanum doped LiNiPO4 (with different Molar concentrations) have been prepared by polyol method using 1,2 propanediol as a polyol medium. XRD analysis reveal that sample calcined at 650°C for 6 hrs shows good crystalline nature with orthorhombic structure and this result is consistent with TG/DTA result. It is found that the conductivity enhances upon doping of Lanthanum while backhoprate decreases compared with pure LiNiPO4. Dielectric studies have also been discussed.

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

    SciTech Connect

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

    2015-03-15

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

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

    PubMed

    Seiler, Ralph

    2016-10-15

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

  4. Synthesis, structure, and optical properties of CsU{sub 2}(PO{sub 4}){sub 3}

    SciTech Connect

    Oh, George N.; Ringe, Emilie; Van Duyne, Richard P.; Ibers, James A.

    2012-01-15

    CsU{sub 2}(PO{sub 4}){sub 3} was synthesized in highest yield by the reaction in a fused-silica tube of U, P, and Se in a CsCl flux at 1273 K. It crystallizes with four formula units in space group P2{sub 1}/n of the monoclinic system in a new structure type. The structure of CsU{sub 2}(PO{sub 4}){sub 3} is composed of U and Cs atoms coordinated by PO{sub 4}{sup 3-} units in distorted octahedral arrangements. Each U atom corner shares with six PO{sub 4}{sup 3-} units. Each Cs atom face shares with one, edge shares with two, and corner shares with three PO{sub 4}{sup 3-} units. The structure shares some features with the sodium zirconium phosphate structure type. X-ray powder diffraction results demonstrate that the present CsU{sub 2}(PO{sub 4}){sub 3} compound crystallizes in a structure different from the previously reported {beta} Prime - and {gamma}-CsU{sub 2}(PO{sub 4}){sub 3} compounds. CsU{sub 2}(PO{sub 4}){sub 3} is highly pleochroic, as demonstrated by single-crystal optical absorption measurements. - Graphical abstract: Stacking of the layers in CsU{sub 2}(PO{sub 4}){sub 3}, viewed along [100]. Highlights: Black-Right-Pointing-Pointer Compound CsU{sub 2}(PO{sub 4}){sub 3} crystallizes in a new structure type. Black-Right-Pointing-Pointer Structure shares some features with the sodium zirconium phosphate structure type. Black-Right-Pointing-Pointer CsU{sub 2}(PO{sub 4}){sub 3} is highly pleochroic, as demonstrated by single-crystal optical absorption measurements.

  5. Variations of 210Po activity in mussel (Perna viridis) of Samut Sakhon and its contribution to dose assessment

    NASA Astrophysics Data System (ADS)

    Porntepkasemsan, B.; Srisuksawad, K.; Kulsawat, W.

    2015-05-01

    The activities of 210Po and its effective dose in green mussel (Perna viridis) collected from a mussel farming area in Samut Sakhon province during the period of 20122013 are presented. Several parameters including maximum shell length and the physiological performance of mussels using condition index and physical properties of seawater (pH, salinity, conductivity, TDS, DO and cation-anion elements) were measured. Each individual mussel was measured for its maximum shell length which was adopted as size class. The activity concentration of 210Po was determined spectroscopically through its 5.30 MeV alpha particle emission, using 209Po as an internal tracer. The 210Po activity concentration in mussels was found to vary between 1.044 and 6.951 Bq/kg wet weight. The 210Po concentration was higher in smaller-sized (≤35 mm) and lower in larger ones (40-70 mm). This confirmed that larger mussels have lower 210Po activities on a weight basis. The 210Po body burden (activity per mussel) ranged from 1.035 to 17.183 mBq. Contrary to the 210Po concentrations, results of the body burden revealed the lower activities in smaller-sized mussels (≤35 mm) and the higher in larger-sized ones (40-70 mm). The type of fluctuations observed with 210Po concentrations were interpreted as a seasonal effect. Total annual effective 210Po dose due to mussel consumption was calculated to be in the range of 3.081 to 16.401 pSv. Based on the international guideline, the average dose calculated due to 210Po in mussels of Samut Sakhon would not pose any significant radiological impact on human health and the mussels are considered to be safe for consumption.

  6. Optical Properties and Electrochemical Performance of LiFePO4 Thin Films Deposited on Transparent Current Collectors.

    PubMed

    Lee, HyunSeok; Yim, Haena; Kim, Kwang-Bum; Choi, Ji-Won

    2015-11-01

    LiFePO4 thin film cathodes are deposited on various transparent conducting oxide thin films on glass, which are used as cathode current collectors. The XRD patterns show that the thin films have the phase of LiFePO4 with an ordered olivine structure indexed to the orthorhombic Pmna space group. LiFePO4 thin film deposited on various TCO glass substrates exhibits transmittance of about 53%. The initial specific discharge capacities of LiFePO4 thin films are 25.0 μAh/cm2 x μm on FTO, 33.0 μAh/cm2 x μm on ITO, and 13.0 μAh/cm2 x μm on AZO coated glass substrates. Interestingly, the retention capacities of LiFePO4 thin films are 76.0% on FTO, 31.2% on ITO, and 37.7% on AZO coated glass substrates at 20th cycle. The initial specific discharge capacity of the LiFePO4/FTO electrode is slightly lower, but the discharge capacities of the LiFePO4/FTO electrode relatively decrease less than those of the others such as LiFePO4/ITO and LiFePO4/AZO with cycling. The results reported here provide the high transparency of LiFePO4 thin films cathode materials and the good candidate as FTO current collector of the LiFePO4 thin film cathode of transparent thin film rechargeable batteries due to its high transparency and cyclic retention.

  7. Mechanism for the phosphaturia of NH4Cl: dependence on acidemia but not on diet PO4 or PTH.

    PubMed

    Guntupalli, J; Eby, B; Lau, K

    1982-05-01

    The effects of metabolic acidosis on renal PO4 handling are controversial. Clearance experiments, therefore, were performed in fasted parathyroidectomized rats 1) to test the thesis that NH4Cl per se alters PO4 reabsorption, 2) to characterize the mechanisms responsible for these changes, and 3) to define the interaction of NH4Cl with parathyroid hormone (PTH) in PO4 deprivation. NH4Cl increased the clearance and fractional excretion of PO4 (FEPO4) without altering plasma PO4. Lactic acid and HCl, but not saline loading. NH4HCO3, or glutamine, produced similar effects. At steady-state phosphaturic effects of NH4Cl, neutralization of the acidemia by NaHCO3 abolished the increment. PTH (3.3 U.kg-1.h-1), superimposed on the maximal effective dose of NH4Cl (5.7 mmol.kg-1.h-1), further augmented FEPO4 (from 24.3 to 46.9%). The effects of NH4Cl (delta FEPO4 = 23 vs. 21%) and the synergism with PTH were not affected by PO4 deprivation. In both PO4 repletion and deprivation, NH4Cl increased basal and PTH-stimulated cAMP excretion, but the changes were poorly correlated with FEPO4. We conclude that NH4Cl inhibits PO4 reabsorption independent of PTH, extracellular fluid volume, natriuresis, NH4+ ion, plasma PO4, or the status of PO4 balance. The effects are mediated by mechanisms dependent on acidemia but are quite distinct from those of PTH. Our findings on cAMP are most compatible with the hypothesis that biochemical events beyond cAMP generation mediate both the phosphaturia of NH4Cl and its ability to restore PTH sensitivity in PO4 deprivation.

  8. Continuous flame aerosol synthesis of carbon-coated nano-LiFePO4 for Li-ion batteries

    PubMed Central

    Waser, Oliver; Büchel, Robert; Hintennach, Andreas; Novák, Petr; Pratsinis, Sotiris E.

    2013-01-01

    Core-shell, nanosized LiFePO4-carbon particles were made in one step by scalable flame aerosol technology at 7 g/h. Core LiFePO4 particles were made in an enclosed flame spray pyrolysis (FSP) unit and were coated in-situ downstream by auto thermal carbonization (pyrolysis) of swirl-fed C2H2 in an O2-controlled atmosphere. The formation of acetylene carbon black (ACB) shell was investigated as a function of the process fuel-oxidant equivalence ratio (EQR). The core-shell morphology was obtained at slightly fuel-rich conditions (1.0 < EQR < 1.07) whereas segregated ACB and LiFePO4 particles were formed at fuel-lean conditions (0.8 < EQR < 1). Post-annealing of core-shell particles in reducing environment (5 vol% H2 in argon) at 700 °C for up to 4 hours established phase pure, monocrystalline LiFePO4 with a crystal size of 65 nm and 30 wt% ACB content. Uncoated LiFePO4 or segregated LiFePO4-ACB grew to 250 nm at these conditions. Annealing at 800 °C induced carbothermal reduction of LiFePO4 to Fe2P by ACB shell consumption that resulted in cavities between carbon shell and core LiFePO4 and even slight LiFePO4 crystal growth but better electrochemical performance. The present carbon-coated LiFePO4 showed superior cycle stability and higher rate capability than the benchmark, commercially available LiFePO4. PMID:23407817

  9. Continuous flame aerosol synthesis of carbon-coated nano-LiFePO(4) for Li-ion batteries.

    PubMed

    Waser, Oliver; Büchel, Robert; Hintennach, Andreas; Novák, Petr; Pratsinis, Sotiris E

    2011-10-01

    Core-shell, nano-sized LiFePO(4)-carbon particles were made in one step by scalable flame aerosol technology at 7 g/h. Core LiFePO(4) particles were made in an enclosed flame spray pyrolysis (FSP) unit and were coated in-situ downstream by auto thermal carbonization (pyrolysis) of swirl-fed C(2)H(2) in an O(2)-controlled atmosphere. The formation of acetylene carbon black (ACB) shell was investigated as a function of the process fuel-oxidant equivalence ratio (EQR). The core-shell morphology was obtained at slightly fuel-rich conditions (1.0PO(4) particles were formed at fuel-lean conditions (0.8PO(4) with a crystal size of 65 nm and 30 wt% ACB content. Uncoated LiFePO(4) or segregated LiFePO(4)-ACB grew to 250 nm at these conditions. Annealing at 800 °C induced carbothermal reduction of LiFePO(4) to Fe(2)P by ACB shell consumption that resulted in cavities between carbon shell and core LiFePO(4) and even slight LiFePO(4) crystal growth but better electrochemical performance. The present carbon-coated LiFePO(4) showed superior cycle stability and higher rate capability than the benchmark, commercially available LiFePO(4).

  10. Topotactic insertion of lithium in the layered structure Li{sub 4}VO(PO{sub 4}){sub 2}: The tunnel structure Li{sub 5}VO(PO{sub 4}){sub 2}

    SciTech Connect

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

    2008-04-15

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

  11. Comparison of Helzel and OxyLite Systems in the Measurements of Tumor Partial Oxygen Pressure (pO2)

    PubMed Central

    Wen, Bixiu; Urano, Muneyasu; Humm, John L.; Seshan, Venkatraman E.; Li, Gloria C.; Ling, C. Clifton

    2009-01-01

    It has been demonstrated in both experimental and human malignancies that hypoxic tumor cells are linked with aggressive disease phenotype. One of the methods to identify these cells is by direct physical measurement of tumor pO2. This study compared pO2 values measured with two systems, the Helzel Hypoximeter (successor of the polarographic Eppen-dorf electrode) and the Oxford-Optronix OxyLite (fiber-optic probe), in R3327-AT and R3327-AT/tkeGFP tumors. Partial oxygen pressure was measured in individual tumors with either system or in the same tumor with both systems. The similarities and discrepancies in pO2 measurements between the two systems were also investigated when tumor-bearing animals were breathing pure oxygen. Our data showed a considerable heterogeneity in pO2 values in each tumor using both the Helzel and OxyLite systems. Similar results were obtained with both systems for the mean and median pO2 values, and the distributions of pO2 values within the interval 0 < pO2 < 40 mmHg (the range important for defining tumor hypoxia) were found to be statistically equivalent However, the frequencies of high pO2 values (>40 mmHg) and zero values measured by the two systems were statistically significantly different. PMID:18159950

  12. Double Carbon Nano Coating of LiFePO4 Cathode Material for High Performance of Lithium Ion Batteries.

    PubMed

    Ding, Yan-Hong; Huang, Guo-Long; Li, Huan-Huan; Xie, Hai-Ming; Sun, Hai-Zhu; Zhang, Jing-Ping

    2015-12-01

    Double carbon-coated LiFePO4 (D-LiFePO4/C) composite with sphere-like structure was synthesized through combination of co-precipitation and solid-state methods. Cetyl-trimethyl-ammonium bromide (CTAB) and citric acid served as two kinds of carbon sources in sequence. SEM images demonstrated that double carbon coating had certain influence on the morphology. The thickness of carbon coating on D-LiFePO4/C was about 1.7 nm and the content of carbon was 2.48 wt%, according to HRTEM and TG analysis. The electrochemical impedance spectroscopy analysis indicated that the D-LiFePO4/C composite presented the charge-transfer resistance of 68 Ω and Li ion diffusion coefficient of 2.68 x 10(-13) cm2 S(-1), while the single carbon-coated LiFePO4 (S-LiFePO4/C) exhibited 135.5Ω and 4.03 x 10(-14) cm2 S(-1). Especially, the prepared D-LiFePO4/C electrode showed discharge capacities of 102.9 (10C) and 87.1 (20C) mA h g(-1), respectively, with almost no capacity lost after 400 cycles at 10C, which were much better than those of S-LiFePO4/C composite.

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

    SciTech Connect

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

    1994-06-01

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

  14. Ab initio calculation of excess properties of La1-x(Ln,An)xPO4 solid solutions

    NASA Astrophysics Data System (ADS)

    Li, Yan; Kowalski, Piotr M.; Blanca-Romero, Ariadna; Vinograd, Victor; Bosbach, Dirk

    2014-12-01

    We used ab initio computational approach to predict the excess enthalpy of mixing and the corresponding regular/subregular model parameters for La1-xLnxPO4 (Ln=Ce,…, Tb) and La1-xAnxPO4 (An=Pu, Am and Cm) monazite-type solid solutions. We found that the regular model interaction parameter W computed for La1-xLnxPO4 solid solutions matches the few existing experimental data. Within the lanthanide series W increases quadratically with the volume mismatch between LaPO4 and LnPO4 endmembers (ΔV=VLaPO4-VLnPO4), so that W(kJ/mol)=0.618(. We demonstrate that this relationship also fits the interaction parameters computed for La1-xAnxPO4 solid solutions. This shows that lanthanides can be used as surrogates for investigation of the thermodynamic mixing properties of actinide-bearing solid solutions.

  15. DEMONSTRATION BULLETIN: PO*WW*ER™ WASTEWATER TREATMENT SYSTEMS - LAKES CHARLES TREATMENT CENTER - CHEMICAL WASTE MANAGEMENT, INC.

    EPA Science Inventory

    The PO*WW*ER™ system developed by Chemical Waste Management, Inc. (CWM), reduces the volume of aqueous waste and catalytically oxidizes volatile contaminants. The PO*WW*ER™ system consists primarily of (1) an evaporator that reduces influent wastewater volume, (2) a catalytic o...

  16. The Polysemy of an "Empty" Prefix: A Corpus-Based Cognitive Semantic Analysis of the Russian Verbal Prefix po-

    ERIC Educational Resources Information Center

    LeBlanc, Nicholas Lance

    2010-01-01

    This dissertation proposes a structured semantic account of the polysemous Russian verbal prefix "po-" within the theoretical framework of cognitive linguistics and using corpus linguistic methods. While scholarly consensus identifies five meanings for "po-" and an additional meaning in conjunction with the suffix--"yva"--, the relationships among…

  17. Synthesis of few-layer MoS2 nanosheet-loaded Ag3PO4 for enhanced photocatalytic activity.

    PubMed

    Song, Yanhua; Lei, Yucheng; Xu, Hui; Wang, Cheng; Yan, Jia; Zhao, Haozhu; Xu, Yuanguo; Xia, Jiexiang; Yin, Sheng; Li, Huaming

    2015-02-21

    Novel few-layer MoS2/Ag3PO4 composites were fabricated. The results indicated that Ag3PO4 nanoparticles were directly formed on the surface of few-layer MoS2. The physical and chemical properties of the few-layer MoS2/Ag3PO4 composite photocatalysts were tested in order to investigate the effects of few-layer MoS2 on the photocatalytic activity of Ag3PO4. The photocatalytic activity of the few-layer MoS2/Ag3PO4 composites was evaluated by the photocatalytic degradation of Rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. The photocatalytic activity of the few-layer MoS2/Ag3PO4 composites was higher than that of pure Ag3PO4. The optimal few-layer MoS2 content for the organic pollutant degradation of the heterojunction structures was determined. The synergic effect between few-layer MoS2 and Ag3PO4 was found to lead to an improved photogenerated carrier separation. The stability and the possible photocatalytic mechanism of the composites were also discussed.

  18. Rare earth precipitation and coprecipitation behavior: The limiting role of PO[sub 4][sup 3[minus

    SciTech Connect

    Byrne, R.H.; Kihyun Kim )

    1993-02-01

    Formation of rare earth phosphate coprecipitates, ([Sigma]M[sub i])PO[sub 4](s), may set limits on the maximum REE concentrations observed in seawater. Examination of rare earth phosphate solubility products, as well as oceanic [l brace]M[sup 3+][r brace] [l brace]PO[sub 4][sup 3[minus

  19. The γ-polymorph of AgZnPO4 with an ABW zeolite-type framework topology

    PubMed Central

    Assani, Abderrazzak; Saadi, Mohamed; El Ammari, Lahcen

    2010-01-01

    The γ-polymorph of the title compound, silver zinc orthophos­phate, was synthesized under hydro­thermal conditions. The structure consists of ZnO4, PO4 and AgO4 units. The coord­ination spheres of ZnII and PV are tetra­hedral, whereas the AgI atom is considerably distorted from a tetra­hedral coordination. Each O atom is linked to each of the three cations. An elliptic eight-membered ring system is formed by corner-sharing of alternating PO4 and ZnO4 tetra­hedra, leading to a framework with an ABW-type zeolite structure. The framework encloses channels running parallel to [100] in which the Ag cations are located, with Ag⋯Ag contacts of 3.099 (3) Å. This short distance results from d 10⋯d 10 inter­actions, which play a substantial role in the crystal packing. The structure of γ-AgZnPO4 is distinct from the two other polymorphs α-AgZnPO4 and β-AgZnPO4, but is isotypic with NaZnPO4-ABW, NaCoPO4-ABW and NH4CoPO4-ABW. PMID:21588789

  20. The γ-polymorph of AgZnPO(4) with an ABW zeolite-type framework topology.

    PubMed

    Assani, Abderrazzak; Saadi, Mohamed; El Ammari, Lahcen

    2010-10-02

    The γ-polymorph of the title compound, silver zinc orthophos-phate, was synthesized under hydro-thermal conditions. The structure consists of ZnO(4), PO(4) and AgO(4) units. The coord-ination spheres of Zn(II) and P(V) are tetra-hedral, whereas the Ag(I) atom is considerably distorted from a tetra-hedral coordination. Each O atom is linked to each of the three cations. An elliptic eight-membered ring system is formed by corner-sharing of alternating PO(4) and ZnO(4) tetra-hedra, leading to a framework with an ABW-type zeolite structure. The framework encloses channels running parallel to [100] in which the Ag cations are located, with Ag⋯Ag contacts of 3.099 (3) Å. This short distance results from d(10)⋯d(10) inter-actions, which play a substantial role in the crystal packing. The structure of γ-AgZnPO(4) is distinct from the two other polymorphs α-AgZnPO(4) and β-AgZnPO(4), but is isotypic with NaZnPO(4)-ABW, NaCoPO(4)-ABW and NH(4)CoPO(4)-ABW.