Role of PO4 tetrahedron in LiFePO4 and FePO4 system.

Science.gov (United States)

Zeng, Yuewu

2015-06-01

Using high resolution transmission electron microscopy with image simulation and Fourier analysis, the Li1- x FePO4 (x < 0.01), Li1- x FePO4 (x ∼ 0.5), and FePO4 particles, prepared by charging or discharging the 053048 electrochemical cells (thickness: 5 mm, width: 30 mm, height: 48 mm) and dismantled inside an Ar-filled dry box, were investigated. The high resolution images reveal: (1) the solid solution of Li1- x FePO4 (x < 0.01) contains some missing Li ions leading PO4 group distorted around M1 tunnel of the unit cell; (2) the texture of the particles of Li1- x FePO4 (x ∼0.5) has homogeneously distributed compositional domains of LiFePO4 and FePO4 resulting from spinodal decomposition which promote Li ion easily getting into the particle due to uphill diffusion, (3) the particles of FePO4 formed in charging have heavily distorted lattice and contain some isolated LiFePO4 , (4) interface between LiFePO4 and FePO4 and between amorphous and crystal region provides the lattice distortion of small polarons. © 2015 Wiley Periodicals, Inc.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

pO2 measurements in arteriolar networks.

Science.gov (United States)

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

1996-03-01

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

Dose estimates to the public from 210Po ingestion via dietary sources at Kalpakkam (India)

International Nuclear Information System (INIS)

Kannan, V.; Iyengar, M.A.R.; Ramesh, R.

2001-01-01

Distribution of one of the natural radionuclides 210 Po activity in food of plant origin such as cereals, pulses, vegetables and food of animal origin such fish, crab, prawn, chicken, egg etc. were determined in and around Kalpakkam up to a distance of 32 km radius. The general range of 210 Po activity levels in all the dietary components (excluding milk and drinking water which are reported in mBq l -1 ) ranged widely from ≤10 to 122,641 mBq kg -1 fresh, the minimum being in vegetables and maximum being in the edible portions (muscle) of crab samples. 210 Po levels in drinking water and milk samples ranged between 0.6-2.6 and 8-12 mBq l -1 respectively. 210 Po content in cereals ranged from ≤32 to 745 mBq kg -1 and in pulses it was found to vary between ≤32 and 294 mBq kg -1 . The range of 210 Po activity in different types of vegetables was found to be ≤10-653 mBq kg -1 . Among the different varieties of vegetables, 210 Po was significantly higher in leafy vegetables (28-653 mBq kg -1 ) as compared to rooty and other types of vegetables which ranged from ≤10-180 mBq kg -1 . In food of animal origin, the observed minimum activity of 210 Po was 8 mBq l -1 in milk and the maximum observed was 122,641 mBq kg -1 in the muscles of crab. It was also observed that 210 Po activity was found to be in higher levels in the food of aquatic animal origin (1414-122,641 mBq kg -1 ) than in the food of terrestrial animal origin (other than milk) which varied from 41 to 963 mBq kg -1 . It is evident from the present study that the foods of animal origin especially crab, fish and prawn deliver significantly greater dose (93-3364 μSv yr -1 ) to the public compared to foods of plant origin whose mean dose ranged 0.08-128 μSv yr -1 . The study showed evidence to suggest that the total ingestion dose due to 210 Po received by the Kalpakkam public through dietary sources is significantly higher than the ingestion dose received due to fallout sources such as 137 Cs and 90 Sr

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

Directory of Open Access Journals (Sweden)

Ruseska G.

2006-01-01

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

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

International Nuclear Information System (INIS)

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

1977-01-01

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

Synthesis of g-C3N4/Ag3PO4 heterojunction with enhanced photocatalytic performance

International Nuclear Information System (INIS)

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

2014-01-01

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

Luminescent properties of LuPO4-Pr and LuPO4-Eu nanoparticles

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Science.gov (United States)

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

2012-12-01

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

Polonium-210 ( 210 Po) concentration was quantified in the muscle tissue and organs of two predatory marine fishes (Genypterus brasiliensis and Cynoscion microlepidotus) from Cabo Frio, Rio de Janeiro, Brazil. The species C. microlepidotus, a benthic carnivore, registered higher 210 Po in its tissue. The organs associated with digestion displayed the maximum radionuclide compared with other organs. The average activity was 2 mBq kg −1 for G. brasiliensis and it was 6 mBq kg −1 for C. microlepidotus. The activity concentrations varied significantly between the species and among organs. -- Highlights: • We analyzed the distribution of 210 Po in two species of predator marine fish. • 210 Po tends to accumulate in some organs, which make this radionuclide radiotoxic. • The consumption of small quantities of fish can represent high potential of 210 Po exposure. • Data about 210 Po bioaccumulation in tropical predator marine fish are limited

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

International Nuclear Information System (INIS)

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

2011-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1982-06-01

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

Assessment of 210Po in foodstuffs consumed in Korea

International Nuclear Information System (INIS)

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

2009-01-01

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

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

Science.gov (United States)

Cai, Li; Jiang, Hui; Wang, Luxi

2017-10-01

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

Transfer of 226Ra, 228Ra, 210Pb and 210Po in aquatic organisms and food chain

International Nuclear Information System (INIS)

Yang Xiaotong; Weng Detong; Chen Wenyin; Chen Xiuyun; Chen Jixi; Zhao Shimin

1998-01-01

Objective: To find out the transfer regularities of 226 Ra, 228 Ra, 210 Pb and 210 Po, which are natural radionuclides in the aquatic organisms and food chain. Methods: Large amount of breed of representative aquatic products and their living waters and sediments were collected and treated according to routine experimental procedures. The contents of 226 Ra, 228 Ra, 210 Pb and 210 Po were detected in each sample. Measured data were analyzed statistically and pairwise comparisons were made to determine the differences between groups. Results: 226 Ra, 228 Ra and 210 Pb were mainly deposited in the bones (or shells), their concentration factors (CF) ranged from 10 2 to 10 3 ; the CF ranged only from 10 0 to 10 2 in the flesh. 210 Po was mainly deposited in the soft tissues, CF ranged from 10 2 to 10 4 ; especially in the stomachs and intestines of fishes, the value reached 10 4 . The cooking process did not impinge significantly on the transfer of 226 Ra, 228 Ra and 210 Pb in the food chain (P>0.05), but did significantly influence the transfer of 210 Po, especially in the freshwater fishes and shrimps. Paired comparison test of the activities between raw flesh and cooked flesh showed very significant difference (P 226 Ra, 228 Ra, 210 Pb and 210 Po. Even though the bones (or shells) of aquatic organisms contained relatively higher levels of 226 Ra, 228 Ra and 210 Pb, the cooking process does not significantly increase the radioactive contents in the foodstuffs. However, the cooking process does significantly influence the transfer of 210 Po. It does significantly increase the content of 210 Po in foodstuffs

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

International Nuclear Information System (INIS)

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

1977-01-01

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

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

Science.gov (United States)

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

2013-01-21

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

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

Directory of Open Access Journals (Sweden)

El-Bakatoushi R.

2016-01-01

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

In-beam spectroscopy of 198Po and 200Po nuclei

International Nuclear Information System (INIS)

Maj, A.

1988-01-01

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

Variationas of 210Po Activity in Mussels (Perna viridis) of Samut Sakhon and Its Contribution to Dose Assessment

International Nuclear Information System (INIS)

Porntepkasemsan, B; Srisuksawad, K.; Permnamtip, V.

2014-01-01

Levels of 210 Po and its effective dose in green mussel (Perna viridis) collected from mussel farming area at the Samut Sakhon province during the period of 2012-2013 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 on 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 209 Po as an internal tracer. The 210 Po activity concentration in mussels was found to vary between 1.044 and 6.951 Bq.kg-1 wet weight. The 210 Po concentration was higher in smaller sized classes (>35 mm) and lowest in larger ones (40-70 mm). This confirms that larger mussels have lower 210Po levels on a weight basis. The 210 Po body burden (activity per mussel) ranged from 1.035 to 17.183 mBq. Contrary to the 210 Po 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 210 Po concentrations are interpreted as a seasonal effect. Total annual effective 210 Po dose due to mussel consumption was calculated to be in the range of 3.081 to 16.401 μSv. Based on the international guideline, the average dose calculated due to 210 Po in mussels of Samut Sakhon would not pose any significant radiological impact on human health and the mussels are considered to be safe for intake.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Studies of {sup 194,195,197}Po

Energy Technology Data Exchange (ETDEWEB)

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

1995-08-01

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

pO2 and pCO2 increment in post-dialyzer blood: the role of dialysate.

Science.gov (United States)

Sombolos, Kostas I; Bamichas, Gerasimos I; Christidou, Fotini N; Gionanlis, Lazaros D; Karagianni, Anna C; Anagnostopoulos, Theodoros C; Natse, Taïsir A

2005-11-01

Blood returning from a dialyzer during hemodialysis has a higher pO2 and pCO2 content than blood entering the dialyzer, and this has been attributed to the dialysate. The present study investigates this phenomenon. Acid-base and blood-gas parameters (pH, pO2, pCO2 and HCO3) were measured in three groups of stable chronic hemodialysis patients (A, B, and C) undergoing high-flux hemodialysis. In group A (n = 15), "arterial" (a) and "venous" (v) samples were withdrawn simultaneously before dialysis (samples A0), 5 min after circulation of the blood with the dialysate in the by-pass mode (samples A5), and 5 min after high-flux hemodialysis at a zero ultrafiltration rate (samples A10). In group B (n = 11) (a) and (v) samples were withdrawn simultaneously before dialysis (samples B0), 5 min after isolated-ultrafiltration with closed dialysate ports ("isolated-closed" ultrafiltration) (samples B5), and 5 min after high-flux hemodialysis at a zero ultrafiltration rate (samples B10). In group C (n = 14), after an initial arterial blood sample withdrawal before hemodialysis (sample C0), high-flux hemodialysis at a zero ultrafiltration rate was initiated. Five minutes later, blood and dialysate samples were withdrawn simultaneously from the hemodialysis lines (samples C5). In all cases blood and dialysate (bicarbonate) flow rates were set at 0.300 and 0.700 L/min, respectively. FLX-18 hemodialyzers (membrane PEPA 1.8 m2) were used in this study. Analysis of variance revealed significant changes only in venous samples. A comparison of arterial and venous samples revealed no differences between groups A and B before the initiation of dialysis (A0a vs. A0v and B0a vs. B0v, P = NS). The pO2 content was higher in A5v samples than in A5a samples (83.5 +/- 11.2 vs. 88.8 +/- 14.0 mm Hg, P pO2, pCO2, and HCO3 in comparison to A10v samples (P pO2 and pCO2 values in A5v and A10v samples increased by 6.3% and 12.1% and by 1.29% and 52% in comparison to corresponding values of A5a and A10

Pt/AlPO{sub 4} nanocomposite thin-film electrodes for ethanol electrooxidation

Energy Technology Data Exchange (ETDEWEB)

Oh, Yuhong; Kang, Joonhyeon; Nam, Seunghoon; Byun, Sujin [WCU Hybrid Materials Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Park, Byungwoo, E-mail: byungwoo@snu.ac.kr [WCU Hybrid Materials Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of)

2012-07-16

The enhanced catalytic properties toward ethanol electrooxidation on Pt/AlPO{sub 4} nanocomposite thin-film electrodes were investigated. The Pt/AlPO{sub 4} nanocomposites with various Al/Pt ratios (0.27, 0.57, and 0.96) were fabricated by a co-sputtering method. All of the Pt/AlPO{sub 4} nanocomposites showed a negative shift in the onset potential and a higher current density than those of pure Pt electrode for the electrooxidation of ethanol. Among the various Pt/AlPO{sub 4} nanocomposite thin-film electrodes, the electrode with an atomic ratio of Al to Pt of 0.57 showed the highest electrocatalytic activity for ethanol electrooxidation. The activation enthalpy for the optimum Pt/AlPO{sub 4} nanocomposite was approximately 0.05 eV lower than that of pure Pt. It is believed that the enhancement in catalytic activity is due to the electron-rich Pt resulting from the Fermi-energy difference between Pt and AlPO{sub 4}. - Highlights: Black-Right-Pointing-Pointer The enhanced ethanol electrooxidation on Pt/AlPO{sub 4} nanocomposites is investigated. Black-Right-Pointing-Pointer The Pt/AlPO{sub 4} exhibits higher current density and lower onset potential than pure Pt. Black-Right-Pointing-Pointer The activation enthalpy for optimum Pt/AlPO{sub 4} electrode is {approx}0.05 eV lower than pure Pt. Black-Right-Pointing-Pointer XPS shows electron-rich Pt due to Fermi-energy difference between Pt and AlPO{sub 4}.

Electroweak Higgs production with HiggsPO at NLO QCD

Science.gov (United States)

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

2017-12-01

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

Levels of 210 Pb and 210 Po in Brazilian cigarettes

International Nuclear Information System (INIS)

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

1996-01-01

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

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

International Nuclear Information System (INIS)

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

2007-01-01

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

FePO4 nanoparticles embedded in a large mesoporous carbon matrix as a high-capacity and high-rate cathode for lithium-ion batteries

International Nuclear Information System (INIS)

Chen, Lian; Wu, Ping; Xie, Kongwei; Li, Jianping; Xu, Bin; Cao, Gaoping; Chen, Yu; Tang, Yawen; Zhou, Yiming; Lu, Tianhong; Yang, Yusheng

2013-01-01

Highlights: ► Self-made nano-CaCO 3 templated LMC as a novel supporting matrix for FePO 4 cathode. ► The 3D porous structure of LMC is well retained in LMC–FePO 4 nanohybrid. ► Its reaction kinetics of lithium insertion/extraction is significantly improved. ► Markedly higher capacities and rate capability by virtue of its structure superiority. -- Abstract: By using large mesoporous carbon (LMC) as a novel host matrix, LMC–FePO 4 nanohybrid has been synthesized through a facile homogeneous precipitation process and subsequent annealing approach. When evaluated as a cathode for lithium-ion batteries (LIBs), the LMC–FePO 4 nanohybrid exhibits higher specific capacities, improved rate capability, and better cycling performance by virtue of its unique structural characteristics

On thermal expansion of RbD2PO4, CsH2PO4 and CsDrPO4 crystals

International Nuclear Information System (INIS)

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

1994-01-01

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

Electroweak Higgs production with HiggsPO at NLO QCD

International Nuclear Information System (INIS)

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

2017-01-01

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

Electroweak Higgs production with HiggsPO at NLO QCD

Energy Technology Data Exchange (ETDEWEB)

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

2017-12-15

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

Anode property of carbon coated LiFePO4 nanocrystals

Science.gov (United States)

Ni, Jiangfeng; Jiang, Jiaxing; Savilov, S. V.; Aldoshin, S. M.

2016-10-01

Nanostructured LiFePO4 is appealing cathode material for rechargeable lithium batteries. Herein, however, we report the intriguing anode properties of carbon coated LiFePO4 nanocrystals. In the potential range of 0-3.0 V, the LiFePO4 nanocrystal electrodes afford high reversible capacity of 373 mAhg-1 at a current rate of 0.05 Ag-1 and retains 239 mAhg-1 at a much higher rate of 1.25 Ag-1. In addition, it is capable of sustaining 1000 cycles at 1.25 Ag-1 without any capacity fading. Such superior properties indicate that nanostructured LiFePO4 could also be promising anode for rechargeable battery applications.

Effect of VO43− substitution for PO43− on electrochemical properties of the Li3Fe2(PO4)3 cathode materials

International Nuclear Information System (INIS)

Yang, Yonggang; Zhang, Yongguang; Hua, Zhengshen; Wang, Xin; Peng, Huifen; Bakenov, Zhumabay

2016-01-01

Graphical abstract: VO 4 3− –substituted Li 3 Fe 2 (PO 4 ) 3 samples were prepared by sol-gel method. The VO 4 3− substitution remarkably improves the rate capability and cycling performance of the Li 3 Fe 2 (PO 4 ) 3 due to improved conductivity and enhanced lithium ion diffusion. - Highlights: • Mixed anion effect was used to improve electrochemical properties of Li 3 Fe 2 (PO 4 ) 3 . • The VO 4 3− substitution improved rate capability and cyclability of Li 3 Fe 2 (PO 4 ) 3 . • The Li 3 Fe 2 (PO 4 ) 2.55 (VO 4 ) 0.45 material shows the excellent electrochemical performance. - Abstract: In this research, VO 4 3− substitution was used to improve electrochemical properties of the Nasicon Li 3 Fe 2 (PO 4 ) 3 cathode material. The VO 4 3− substitution resulted in formation of a homogeneous compound Li 3 Fe 2 (PO 4 ) 3-x (VO 4 ) x in a composition range of x ≤ 0.45; further introduction of VO 4 3− led to precipitation of some other phases. It was shown that the VO 4 3− substituted samples presented discharging capacity higher than that of bare non-substituted Nasicon and the reported Ti 4+ and Mn 2+ doped ones. The Li 3 Fe 2 (PO 4 ) 2.55 (VO 4 ) 0.45 material exhibited excellent cycling stability and rate capability, and retained a capacity of 91.8 mAh g −1 after 60 cycles at 2C charge-discharge rate. This value is one of the highest reported to date for the Li 3 Fe 2 (PO 4 ) 3 compound, and was about 48% higher than that of the latter. The electrochemical performance enhancements for the VO 4 3− substituted samples were attributed to the reduction of charge transfer resistance, increase of electrical conductivity, and fast lithium ion diffusion behavior. Hence, the obtained results proved that the VO 4 3− anion substitution for PO 4 3− is a powerful technique to improve the electrochemical performance of the studied Nasicon compound.

Measurements of partial oxygen pressure pO2 using the OxyLite system in R3327-AT tumors under isoflurane anesthesia.

Science.gov (United States)

Wen, Bixiu; Urano, Muneyasu; O'Donoghue, Joseph A; Ling, C Clifton

2006-09-01

The presence of oxygen-deficient tumor cells is a critical issue in cancer therapy. To identify tumor hypoxia, tissue partial oxygen pressure (pO2) can be measured directly. The OxyLite system allows determination of pO2 in tumors and permits continuous measurements of pO2 at a fixed point. In this study, this system was used to continuously measure pO2 in R3327-AT tumors in animals anesthetized with isoflurane. In addition, continuous pO2 measurement was performed in the muscle in non-tumor-bearing animals. In animals breathing isoflurane balanced by air, tumor pO2 at fixed positions decreased rapidly within 1-2 min of probe positioning but remained stable thereafter. In animals breathing isoflurane balanced by pure oxygen, tumor pO2 was higher and remained high. We also measured pO2 values at multiple positions in R3327-AT tumors of various sizes, with anesthetized animals breathing either air or pure oxygen. Our data showed that the frequency of pO2 measurements below 2.5 or 5.0 mmHg was significantly higher in animals breathing air than in animals breathing pure oxygen. Measurements in different-sized tumors showed that the mean pO2 value decreased as tumor volume increased, with the largest change occurring between tumor volumes of 100 and 200 mm3. Our data demonstrate that the OxyLite system, when used with isoflurane anesthesia, is a valuable tool in the study of tumor hypoxia.

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

International Nuclear Information System (INIS)

Jungowska, W.; Znamierowska, T.

1993-01-01

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

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

Directory of Open Access Journals (Sweden)

Arun Kumar

2009-01-01

Full Text Available Pure lithium iron phosphate (LiFePO4 and carbon-coated LiFePO4 (C-LiFePO4 cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on LiFePO4 particles. Ex situ Raman spectrum of C-LiFePO4 at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of LiFePO4 and C-LiFePO4 showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively for LiFePO4 where as in case of C-LiFePO4 that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure LiFePO4 was 69% after 25 cycles where as that of C-LiFePO4 was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.

Determination and distribution of 210Po in tobacco plants from Poland

International Nuclear Information System (INIS)

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

2001-01-01

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

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

Science.gov (United States)

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

2003-10-01

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

PO2 cycling reduces diaphragm fatigue by attenuating ROS formation.

Science.gov (United States)

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

2014-01-01

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

PO2 cycling reduces diaphragm fatigue by attenuating ROS formation.

Directory of Open Access Journals (Sweden)

Li Zuo

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

A high-temperature Raman scattering study of the phase transitions in GaPO{sub 4} and in the AlPO{sub 4}-GaPO{sub 4} system

Energy Technology Data Exchange (ETDEWEB)

Angot, E [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Parc, R Le [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Levelut, C [Laboratoire des Colloides, des Verres et des Nanomateriaux, UMR CNRS 5587, Universite Montpellier II, cc026, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Beaurain, M [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Armand, P [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Cambon, O [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France); Haines, J [Laboratoire de Physicochimie de la Matiere Condensee, UMR CNRS 5617, Universite Montpellier II, cc003, Place E Bataillon, F-34095 Montpellier Cedex 5 (France)

2006-05-03

Al{sub 1-x}Ga{sub x}PO{sub 4} solid solutions (x = 0.2, 0.3, 0.38, 0.7) and the pure AlPO{sub 4} (x = 0) and GaPO{sub 4} (x = 1) end members with the {alpha}-quartz-type structure were studied by Raman scattering. An investigation as a function of composition enabled the various modes to be assigned, in particular coupled and decoupled vibrations. The tetrahedral tilting modes, which have been linked to high-temperature phase transitions to {beta}-quartz-type forms, were found to be decoupled. In addition, it is shown that Raman spectroscopy is a powerful technique for determining the gallium content of these solid solutions. Single crystals with x = 0.2, 0.38, and 1.0 (GaPO{sub 4}) were investigated at high temperature. The composition Al{sub 0.8}Ga{sub 0.2}PO{sub 4} was found to exhibit sequential transitions upon heating to the {beta}-quartz and {beta}-cristobalite forms at close to 993 K and 1073 K, respectively. Direct {alpha}-quartz-{beta}-cristobalite transitions were observed for the two other compositions at close to 1083 K and 1253 K, respectively, upon heating. The spectra of the {beta}-quartz and {beta}-cristobalite forms indicate the presence of significant disorder. Back transformation to the {alpha}-quartz-type form occurred readily with a hysteresis of less than 100 K for the composition x = 0.38 and for pure GaPO{sub 4}. Rapid cooling was necessary to obtain the metastable {alpha}-cristobalite form. In contrast, for Al{sub 0.80}Ga{sub 0.20}PO{sub 4}, the {alpha}-cristobalite form was obtained even upon slow cooling.

Unlocking the energy capabilities of micron-sized LiFePO4.

Science.gov (United States)

Guo, Limin; Zhang, Yelong; Wang, Jiawei; Ma, Lipo; Ma, Shunchao; Zhang, Yantao; Wang, Erkang; Bi, Yujing; Wang, Deyu; McKee, William C; Xu, Ye; Chen, Jitao; Zhang, Qinghua; Nan, Cewen; Gu, Lin; Bruce, Peter G; Peng, Zhangquan

2015-08-03

Utilization of LiFePO4 as a cathode material for Li-ion batteries often requires size nanonization coupled with calcination-based carbon coating to improve its electrochemical performance, which, however, is usually at the expense of tap density and may be environmentally problematic. Here we report the utilization of micron-sized LiFePO4, which has a higher tap density than its nano-sized siblings, by forming a conducting polymer coating on its surface with a greener diazonium chemistry. Specifically, micron-sized LiFePO4 particles have been uniformly coated with a thin polyphenylene film via the spontaneous reaction between LiFePO4 and an aromatic diazonium salt of benzenediazonium tetrafluoroborate. The coated micron-sized LiFePO4, compared with its pristine counterpart, has shown improved electrical conductivity, high rate capability and excellent cyclability when used as a 'carbon additive free' cathode material for rechargeable Li-ion batteries. The bonding mechanism of polyphenylene to LiFePO4/FePO4 has been understood with density functional theory calculations.

Mixed phosphates of the Na3PO4 - LnPO4 systems

International Nuclear Information System (INIS)

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

2002-01-01

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

The determination of 210Po in urine

International Nuclear Information System (INIS)

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

1975-01-01

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

Po-210 distribution in uranium-mill circuits

International Nuclear Information System (INIS)

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

1983-01-01

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

"2"1"0Po and "2"1"0Pb in medicinal plants in the region of Karnataka, Southern India

International Nuclear Information System (INIS)

Chandrashekara, K.; Somashekarappa, H.M.

2016-01-01

The activity concentrations of naturally occurring radionuclides "2"1"0Po and "2"1"0Pb were estimated in some selected medicinal plants and soil samples of coastal Karnataka in India. The mean activity concentrations of "2"1"0Po and "2"1"0Pb 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 "2"1"0Po and "2"1"0Pb than other species sampled. In spite of disequilibrium between them, these two radionuclides were well correlated in both soil and medicinal plants. - Highlights: • "2"1"0Po and "2"1"0Pb concentrations in medicinal plants were estimated. • Concentrations are higher in leaves than in rhizome or bark. • "2"1"0Po and "2"1"0Pb were in disequilibrium, but correlated very well. • Study helps to form database of radionuclides in medicinal plants.

210Po behaviour in terrestrial environment: a review

International Nuclear Information System (INIS)

Coppin, F.; Roussel-Debet, S.

2004-01-01

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

Electric quadruple moments of high-spin isomers in 209Po

International Nuclear Information System (INIS)

Ivanov, E.A.; Nicolescu, G.; Plostinaru, D.

1998-01-01

The electric quadrupole interaction of the 209 Po (17/2) - and (13/2) - isomers in a Bi single-crystal was measured. The results for the quadrupole moments are connected with studies of isomers in Po isotopes. A two level analysis procedure was employed for the combined data of (17/2) - and (13/2) - isomers. The quadrupole moments of the Po isotopes are of special interest for testing nuclear models because of supposed simple nuclear structure with two protons outside a closed magic number shell. While the g-factors are significant for the predominant few-particle structures often present at high spins, the quadrupole moments are sensitive to additional contributions arising from core deformation effects. A systematic study of quadrupole moments of 12 + isomers in Pb isotopes has indeed demonstrated that the valence neutron effective charge increases as more particle pairs are removed from the 208 Pb core. In the present work, quadrupole coupling constants were measured for the isomers by the time-differential perturbed angular distribution (TDPAD) technique, in the presence of quadrupole interactions from the internal electric field gradient (EFG) in Bi crystal. The experiments were performed using a pulsed deuteron-beam of 13 MeV. The (17/2) - isomer state (T 1/2 = 88 ns) and the (13/2) - isomer state (T 1/2 = 24 ns) were populated and aligned by the 209 Bi(d,2n) reaction. The repetition time of the pulse was 10 μs and the width was around 5 ns (FWHM). The rather low bombardment energy was chosen to reduce population of higher spin isomers and to optimize the population of 209 Po((17/2) - ) and 209 Po((13/2) - ). The 209 Po single crystal target was held at a temperature of 470 K in order to reduce possible radiation damage effects. The experiments have been performed with the c axis of the single crystal at 45 angle and 90 angle to the beam direction. We chose to use a calibration based on isomers with well-understood nuclear structure allowing a reliable

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

International Nuclear Information System (INIS)

Ishimoto, A.; Momoshima, N.

2006-01-01

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

Enhanced electrochemical performance of LiMnPO4 by Li+-conductive Li3VO4 surface coatings

International Nuclear Information System (INIS)

Dong, Youzhong; Zhao, Yanming; Duan, He; Liang, Zhiyong

2014-01-01

By a simple wet ball-milling method, Li 3 VO 4 -coated LiMnPO 4 samples were prepared successfully for the first time. The thin Li 3 VO 4 coating layer with a three-dimensional Li + -ion transport path and high mobility of Li + -ion strongly adhered to the LiMnPO 4 material reduces Mn dissolution and increases the Li + flux through the surface of the LiMnPO 4 itself by preventing formation of phases on the surface that would normally block Li + as well as Li + -ion permeation into the surface of the LiMnPO 4 electrode and therefore improve the rate capability as well as the cycling stability of LiMnPO 4 materials. The electrochemical testing shows that the 5% Li 3 VO 4 -coated LiMnPO 4 sample shows a clear voltage plateau in the charge curves and a much higher reversible capacity at different discharge rates compared with the pristine LiMnPO 4 . EIS results also show that the surface charge transfer resistance and Warburg impedance of the Li 3 VO 4 -coated LiMnPO 4 samples significantly decreased. The surface charge transfer resistance and Warburg impedance for the pristine LiMnPO 4 are 955.1 Ω and 400.3 Ω, respectively. While, for the 5% Li 3 VO 4 -coated LiMnPO 4 , the value are only 400.2 Ω and 283.6 Ω, respectively. The surface charge transfer resistance decreases more than half. All of the improved performance will be favorable for application of the LiMnPO 4 in high-power lithium ion batteries

Cation mobility in NASICON compounds Li1-xZr2-xNbx(PO4)3 and Li1+xZr2-xScx(PO4)3

International Nuclear Information System (INIS)

Stenina, I.A.; Yaroslavtsev, A.B.; Aliev, A.D.; Antipov, E.V.; Velikodnyj, Yu.A.; Rebrov, A.I.

2002-01-01

Compounds featuring NASICON structure of the composition Li 1-x Zr 2-x Nb x (PO 4 ) 3 and Li 1+x Zr 2-x Sc x (PO 4 ) 3 were studied by the method of X-ray phase analysis and 7 Li and 31 P NMR. Structure of Li 0.8 Zr 1.8 Nb 0.2 (PO 4 ) 3 was refined on the basis of X-ray powder pattern. It is shown that cationic disordering in LiZr 2 (PO 4 ) 3 is stimulated both by cationic vacancies and interstitial atoms formation. The cationic vacancies are characterized by a higher mobility. The level of intrinsic disordering was estimated and the Frenkel constant for the compound was calculated [ru

The influence of sampling site and time upon umbilical cord blood acid-base status and PO2 in the newborn infant

DEFF Research Database (Denmark)

Paerregaard, A; Nickelsen, C N; Brandi, L

1987-01-01

Measurement of umbilical cord blood acid-base status is routinely carried out in many obstetric centers. Umbilical cord blood pH, PO2, PCO2 and SBE (standard base excess) may change between clamping of the cord and analysis due to diffusion and metabolism. It was the aim of this study to evaluate...... partum and pH, PO2 and PCO2 were measured and SBE calculated. As demonstrated in table I, the vein blood pH and PO2 values were higher and PCO2 values lower than in the artery blood. The changes over time are given in figure 1 with the 1 min values as points of reference. Changes within the first 15...... minutes were modest. A significant fall in vein pH, vein SBE and artery PO2 and a significant rise in artery PCO2 was found. Greater variation in the changes over time was found in artery than in vein blood, being most evident for the 30 min values. Although significant changes in the umbilical cord acid...

Distribution of 210Pb and 210Po concentrations in wild berries and mushrooms in boreal forest ecosystems

International Nuclear Information System (INIS)

Vaaramaa, Kaisa; Solatie, Dina; Aro, Lasse

2009-01-01

The activity concentrations and distribution of 210 Pb and 210 Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of 210 Pb and 210 Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems > leaves > berries (i.e. fruits). The activity ratios of 210 Po/ 210 Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of 210 Pb and especially 210 Po were higher than in fruits of the wild berries. The highest activity concentration of 210 Pb was detected in Cortinarius armillatus L. (16.2 Bq kg -1 d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg -1 d.w.). The 210 Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg -1 d.w. (Russula paludosa L.) to 1174 Bq kg -1 d.w. (L. vulpinum L.). In general, the highest activity concentrations of 210 Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of 210 Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of 210 Po were higher than those of 210 Pb. 210 Po and 210 Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by 137 Cs from the Chernobyl fallout.

Inhalation of 210Po and 210Pb from cigarette smoking in Poland

International Nuclear Information System (INIS)

Skwarzec, B.; Ulatowski, J.; Struminska, D.I.; Borylo, A.

2001-01-01

The carcinogenic effect of 210 Po and 210 Pb with respect to lung cancer is an important problem in many countries with very high cigarette consumption. Poland has one of the highest consumptions of cigarettes in the world. The results of 210 Po determination on the 14 most frequently smoked brands of cigarettes which constitute over 70% of the total cigarette consumption in Poland are presented and discussed. Moreover, the polonium content in cigarette smoke was estimated on the basis of its activity in fresh tobaccos, ash, fresh filters and post-smoking filters. The annual effective doses were calculated on the basis of 210 Po and 210 Pb inhalation with the cigarette smoke. The results of this work indicate that Polish smokers who smoke one pack (20 cigarettes) per day inhale from 20 to 215 mBq of 210 Po and 210 Pb each. The mean values of the annual effective dose for smokers were estimated to be 35 and 70 μSv from 210 Po and 210 Pb, respectively. For persons who smoke two packs of cigarettes with higher radionuclide concentrations, the effective dose is much higher (471 μSv yr -1 ) in comparison with the intake in diet. Therefore, cigarettes and the absorption through the respiratory system are the main sources and the principal pathway of 210 Po and 210 Pb intake of smokers in Poland

Structural studies of the high-temperature modifications of sodium and silver orthophosphates, II-Na3PO4 and II-Ag3PO4, and of the low-temperature form I-Ag3PO4

International Nuclear Information System (INIS)

Newsam, J.M.; Cheetham, A.K.; Tofield, B.C.

1980-01-01

The crystal structures of the high-temperature modifications of sodium and silver orthophosphates have been determined using powder neutron diffraction (PND) data. II-Na 3 PO 4 adopts the space group Fm3m with a = 7.512(3) A at 400 0 C. The PO 4 3- group is centred around the origin, but it shows high orientational disorder. The sodium ions occupy the (1/4, 1/4, 1/4) and (1/2, 1/2, 1/2) sites. II-Ag 3 PO 4 , at 650 0 C, is similar with a = 7.722 (5) A. The structure of I-Ag 3 PO 4 at room temperature (P4 - 3n, a = 6.0095 (6) A) has been re-examined by single-crystal X-ray diffraction. The derived model, with R = 0.019 for 116 independent reflections, is in agreement with the latest work reported in the literature. The structure of I-Ag 3 PO 4 at 375 0 C, as determined by PND, has a = 6.061(1) A, and displays no gross modifications from that observed at 25 0 C, although the anisotropic nature of the silver sites is markedly more pronounced at this higher temperature. The cation mobility is discussed in relation to the high-temperature structures. (Auth.)

An assessment of 210Pb and 210Po in terrestrial foodstuffs from regions of England and Wales

International Nuclear Information System (INIS)

McDonald, P.; Jackson, D.; Leonard, D.R.P.; McKay, K.

1999-01-01

Based on data for nationally available foodstuffs, naturally occurring 210 Pb and 210 Po contribute significantly to the UK radiation dose from dietary intake. To provide a more complete overview of radiological implications to the public, samples of offal, cereal, fruit, root and green vegetables were collected from 11 sites, including regions of potential 210 Pb and 210 Po enhancement. Considerable variability was evident in levels of 210 Pb and 210 Po from all sites and in all food types investigated. Higher concentrations were typically found in offal and cereals. Lowest concentrations were generally found in root vegetables. Between sites, the only evidence of elevated concentrations of 210 Po occurred at Helston ( 210 Po 3.0 Bq kg -1 in bovine liver, no other offal sample exceeding 0.8 Bq kg -1 ), and Holyhead 210 Po 0.4 Bq kg -1 in blackberries, no other fruit sample exceeding 0.1 Bq kg -1 ). Other foodstuffs from these sites did not show similar enhanced levels of 210 Po. The maximum dose arising from consumption of 210 Pb and 210 Po in foods surveyed in this study is estimated to be around 120 μSv year -1 to adults. This compares with an estimated UK average consumption dose from all nuclides and foodstuffs of 300 μSv year -1 (broad range 100-1000 μSv year -1 ). (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

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

Science.gov (United States)

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

2014-12-01

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

Fast-Rate Capable Electrode Material with Higher Energy Density than LiFePO4: 4.2V LiVPO4F Synthesized by Scalable Single-Step Solid-State Reaction.

Science.gov (United States)

Kim, Minkyung; Lee, Seongsu; Kang, Byoungwoo

2016-03-01

Use of compounds that contain fluorine (F) as electrode materials in lithium ion batteries has been considered, but synthesizing single-phase samples of these compounds is a difficult task. Here, it is demonstrated that a simple scalable single-step solid-state process with additional fluorine source can obtain highly pure LiVPO 4 F. The resulting material with submicron particles achieves very high rate capability ≈100 mAh g -1 at 60 C-rate (1-min discharge) and even at 200 C-rate (18 s discharge). It retains superior capacity, ≈120 mAh g -1 at 10 C charge/10 C discharge rate (6-min) for 500 cycles with >95% retention efficiency. Furthermore, LiVPO 4 F shows low polarization even at high rates leading to higher operating potential >3.45 V (≈3.6 V at 60 C-rate), so it achieves high energy density. It is demonstrated for the first time that highly pure LiVPO 4 F can achieve high power capability comparable to LiFePO 4 and much higher energy density (≈521 Wh g -1 at 20 C-rate) than LiFePO 4 even without nanostructured particles. LiVPO 4 F can be a real substitute of LiFePO 4.

Electronic Properties of LiFePO4 and Li doped LiFePO4

International Nuclear Information System (INIS)

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

2005-01-01

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

Le corps poétique ou la poétique du corps

Directory of Open Access Journals (Sweden)

Yvonne Goga

2007-05-01

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

Skeletal muscle microvascular and interstitial PO2 from rest to contractions.

Science.gov (United States)

Hirai, Daniel M; Craig, Jesse C; Colburn, Trenton D; Eshima, Hiroaki; Kano, Yutaka; Sexton, William L; Musch, Timothy I; Poole, David C

2018-03-01

Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O 2 transport, thereby supporting oxidative metabolism. The greatest resistance to O 2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O 2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is   were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5

Inelastic neutron scattering and lattice dynamics studies of AlPO4 and GaPO4

International Nuclear Information System (INIS)

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

2006-01-01

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

Determination of "2"1"0Po in calcium supplements and the possible related dose assessment to the consumers

International Nuclear Information System (INIS)

Strumińska-Parulska, Dagmara I.

2015-01-01

The aim of this pioneer study was to investigate the most popular calcium supplements as a potential additional source of polonium "2"1"0Po 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 "2"1"0Po activity concentrations in calcium supplements, find the correlations between "2"1"0Po concentration in medicament and calcium chemical form, and calculate the effective radiation dose connected to analyzed calcium supplement consumption. As results showed, "2"1"0Po concentrations in natural origin calcium supplements (especially sedimentary rocks) were higher than the other analyzed. Also the results of "2"1"0Po analysis obtained for inorganic forms of calcium supplements were higher. The highest "2"1"0Po 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 "2"1"0Po 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 "2"1"0Po taken with 1 g of pure calcium per day was connected to dolomite – 12.7 ± 0.70 μSv year"−"1. - Highlights: • "2"1"0Po in the most popular calcium supplements in Poland was investigated. • "2"1"0Po is present in calcium supplements and could be an additional source of "2"1"0Po for human. • Inorganic samples were richer in "2"1"0Po in comparison to organic. • Additives from sedimentary rocks, were richer in polonium in comparison to

Levels of {sup 210} Pb and {sup 210} Po in Brazilian cigarettes

Energy Technology Data Exchange (ETDEWEB)

Santos, Pedro Lopes dos; Kelecom, Alphonse; Gouvea, Rita de Cassia dos Santos; Dutra, Iedo Ramos [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Biologia Geral

1996-12-01

{sup 210} Po and {sup 210} Pb concentrations have been determined in 18 Brazilian cigarette samples and compared with known data on U content. U is respectively 3-fold less and 4-fold less abundant than {sup 210} Po or {sup 210} Pb. No correlation could be observed between U concentration and those of Po or Pb. The mean concentration of {sup 210} Pb is higher than that of {sup 210} Pb observed in many other plants, even in plants frown in high background areas. (author) 19 refs., 1 fig., 1 tab.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Science.gov (United States)

Lee, Hsiu-wei; Wang, Jeng-Jong

2013-03-01

Oysters around the coast of Taiwan were collected, dried, spiked with a (209)Po tracer for yield, digested with concentrated HNO(3) and H(2)O(2), and finally dissolved in 0.5 N HCl. The polonium was then spontaneously deposited onto a silver disc, and the activity of (210)Po was measured using an alpha spectrum analyzer equipped with a silicon barrier detector. Meanwhile, the internal effective dose of (210)Po coming from the intake of oysters by Taiwanese was evaluated. The results of the present study indicate that (210)Po average activity concentrations ranged from 23.4 ± 0.4 to 126 ± 94 Bq kg(-1) of fresh oysters. The oysters coming from Penghu island and Kinmen island regions contain higher concentrations of (210)Po in comparison with oysters from other regions of Taiwan. The value of (210)Po weighted average activity concentrations for all oyster samples studied is 25.9 Bq kg(-1). The annual effective dose of Taiwanese due to the ingestion of (210)Po in oysters was estimated to be 4.1 × 10(-2) mSv y(-1). Copyright © 2013. Published by Elsevier Ltd.

210Pb and 210Po activities in French foodstuffs

International Nuclear Information System (INIS)

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

2015-01-01

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

/sup 210/Po in the western Indian Ocean: Distributions, disequilibria and partitioning between the dissolved and particulate phases

Energy Technology Data Exchange (ETDEWEB)

Chung, Y.; Finkel, R.

1988-05-01

Seven GEOSECS stations in the western Indian Ocean were measured for dissolved /sup 210/Po, and five of these were also measured for particulate /sup 210/Po. Dissolved phase /sup 210/Po is lower than /sup 210/Pb in the deep water north of Madagascar, with values in the Arabian Sea being lower by about 4 dpm/100 kg (approx. = 30%) for almost the entire water column. South of Madagascar, /sup 210/Po is essentially in equilibrium with /sup 210/Pb in the deep water, but with /sup 210/Po excess in subsurface water south of the Crozet basin. In the benthic boundary layer, /sup 210/Po is consistently lower than /sup 210/Pb for all the stations. In the particulate phase /sup 210/Po shows a general increase with depth and is highest in the benthic boundary layer. In general, /sup 210/Po is lower than /sup 210/Pb in the particulate phase, but at the one Somali basin station where data are available, deep water /sup 210/Po is systematically higher than /sup 210/Pb. A mid-depth maximum of particulate /sup 210/Pb is generally associated with that of dissolved /sup 210/Pb. The partition of /sup 210/Po between the particulate and dissolved phases is not significantly different from that of /sup 210/Pb. The activities of the two nuclides in the particulate phase are generally less than 10% of those in the dissolved phase. The range is from 1% to 60%. High particulate and low dissolved activities are observed in the deep water, especially in the benthic boundary layer.

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

Science.gov (United States)

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

2015-03-01

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

Multi-year Surface Deposition of {sup 210}Pb and {sup 210}Po at Lisbon - Atmospheric Depositions of {sup 210}Pb and {sup 210}Po in Lisbon, Portugal

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Fernando P.; Oliveira, Joao M.; Alberto, G. [Instituto Superior Tecnico/ Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, E.N. 10, 2686-953 Sacavem (Portugal)

2014-07-01

The long lived radon daughters {sup 210}Pb and {sup 210}Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual {sup 210}Pb flux was 66±12 Bq m{sup -2}, and the average annual {sup 210}Po flux was 8±3 Bq m{sup -2}, with an overall {sup 210}Po/{sup 210}Pb activity ratio of 0.15±0.06. Direct determination of the {sup 210}Pb atmospheric flux was compared with the {sup 210}Pb excess determined in soil surface layers along with atmospheric depositions of {sup 137}Cs. The deposition of atmospheric {sup 210}Pb was positively correlated with seasonal rainfall, while {sup 210}Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high {sup 210}Po/{sup 210}Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of {sup 210}Pb and {sup 210}Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)

Preventing structural degradation from Na3V2(PO4)3 to V2(PO4)3: F-doped Na3V2(PO4)3/C cathode composite with stable lifetime for sodium ion batteries

Science.gov (United States)

Chen, Yanjun; Xu, Youlong; Sun, Xiaofei; Zhang, Baofeng; He, Shengnan; Li, Long; Wang, Chao

2018-02-01

A prospective NASICON-type F-doped Na3V2(PO4)2.93F0.07/C (F-0.07-NVP/C) composite is synthesized by a solid-state reaction method. F-doping can restrain the structural degradation from Na3V2(PO4)3 to V2(PO4)3 and enhance the structural stability. Meanwhile, it can decrease the particle size to diminish the pathway of Na+ diffusion, which can increase ionic conductivity efficiently. The kinetic behavior is significantly improved and it is beneficial to reinforcing the electrochemical performance of F-doping composites. Compared with Undoped-NVP/C sample, F-0.07-NVP/C composite delivers a 113 mAh g-1 discharge capacity at 10 mA g-1, which is very close to the theoretical capacity (117 mAh g-1). As for cycle performance, a reversible capacity of 97.8 mAh g-1 can be obtained and it retains 86% capacity after 1000 cycles at 200 mA g-1. F-0.07-NVP/C composite presents the highest DNa+ (2.62 × 10-15 cm2s-1), two orders of magnitude higher than the undoped sample (4.8 × 10-17 cm2s-1). This outstanding electrochemical performance is ascribed to the synergetic effect from improved kinetic behavior and enhanced structural stability due to F-doping. Hence, the F-doped composite would be a promising cathode material in SIB for energy storage and conversion.

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

Science.gov (United States)

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

2008-06-01

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

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Hair and feathers as indicator of internal contamination of 210Po and 210Pb

Energy Technology Data Exchange (ETDEWEB)

Holm, E. (ed.); Gwynn, J.; Zaborska, A.; Gaefvert, T. (Norwegian Radiation Protection Authority (Norway)); Roos, P. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Henricsson, F. (Lund Univ., Lund (Sweden))

2010-03-15

The activities of the NKS-B HAIRPOL project is summarised in this report. The objective was to investigate if hair and feathers were suitable matrices for the estimation of the intake of 210Po. Human hair from people of different sex and age was analysed for 210Po showing concentrations between 0.4 to 11 Bq/kg dry weight. Samples from horses, mane, fur and tail showed concentration from 6 to 17 Bq/kg with no significant difference between the different sample types. Musk ox from Greenland showed much higher concentrations since the animal has to graze a large surface. In fur the concentration was 260 Bq/kg. A considerable fraction of the total 210Po in this animal is contained in the hair. Also different organs were analysed and the highest concentration was found in kidney, 2 700 Bq/kg. The 210Pb concentration in hair was estimated to about 20 Bq/kg. Three different seabirds from Svalbard were analysed. Feathers from all three seabird species show increasing activity concentrations of 210Po and 210Pb from the base to the tip of the feather, but it was difficult to relate feather concentrations to muscle concentrations due to a number of complicating factors. (author)

Hair and feathers as indicator of internal contamination of 210Po and 210Pb

International Nuclear Information System (INIS)

Holm, E.; Roos, P.; Henricsson, F.

2010-03-01

The activities of the NKS-B HAIRPOL project is summarised in this report. The objective was to investigate if hair and feathers were suitable matrices for the estimation of the intake of 210 Po. Human hair from people of different sex and age was analysed for 210 Po showing concentrations between 0.4 to 11 Bq/kg dry weight. Samples from horses, mane, fur and tail showed concentration from 6 to 17 Bq/kg with no significant difference between the different sample types. Musk ox from Greenland showed much higher concentrations since the animal has to graze a large surface. In fur the concentration was 260 Bq/kg. A considerable fraction of the total 210 Po in this animal is contained in the hair. Also different organs were analysed and the highest concentration was found in kidney, 2 700 Bq/kg. The 210 Pb concentration in hair was estimated to about 20 Bq/kg. Three different seabirds from Svalbard were analysed. Feathers from all three seabird species show increasing activity concentrations of 210 Po and 210 Pb from the base to the tip of the feather, but it was difficult to relate feather concentrations to muscle concentrations due to a number of complicating factors. (author)

210Po and 210Pb activity concentration in the coral bands of Pulau Tuba, Langkawi

International Nuclear Information System (INIS)

Lee Jen Nie; Che Abdul Rahim Mohamed; Zaharuddin Ahmad

2007-01-01

We examined the concentrations of 210 Po and 210 Pb in each layers of coral banding of coral skeletons. Concentrations of 210 Po and 210 Pb in massive corals (i.e. Porites, Favites, Platygyra and Goniostrea) from Pulau Tuba, Langkawi were measured using the Alpha-Spectrometry. The concentrations of 210 Po were higher than the concentrations of 210 Pb. This may due to continuing source of 210 Po from 210 Pb. Highest concentration on 210 Po in coral banding was 48.30 ± 28.53 Bq/ kg, meanwhile for 210 Pb was 12.86 ± 5.80 Bq/ kg. The ratios of 210 Po/ 210 Pb were in the range of 2.21 to 5.49. The variation activity concentrations of 210 Po and 210 Pb in the coral bands are important to consider in using coral as retrospective study of environmental changes. The coral can represent the total of 210 Po and 210 Pb in the surrounding water for the past few years. (author)

Structural and electrochemical studies of PPy/PEG-LiFePO4 cathode material for Li-ion batteries

International Nuclear Information System (INIS)

Fedorkova, Andrea; Nacher-Alejos, Ana; Gomez-Romero, Pedro; Orinakova, Renata; Kaniansky, Dusan

2010-01-01

A simple chemical oxidative polymerization of pyrrole (Py) directly onto the surface of LiFePO 4 particles was applied to the synthesis of polypyrrole-LiFePO 4 (PPy-LiFePO 4 ) powder. The LiFePO 4 sample without carbon coating was synthesized by a solvothermal method. The polyethylene glycol (PEG) was used as additive during Py polymerization for increasing the PPy-LiFePO 4 conductivity. Properties of resulting LiFePO 4 , PPy-LiFePO 4 and PPy/PEG-LiFePO 4 samples were characterized by XRD, SEM, TGA and galvanostatic charge-discharge measurements. These methods confirmed the presence of polypyrrole on LiFePO 4 particles and its homogeneous distribution in the resulting powder material. The PPy/PEG-LiFePO 4 composites show higher discharge capacity than pure LiFePO 4 , as PPy/PEG network improves the electron conductivity. It presents specific discharge capacity of 153 mAh/g at C/5 rate.

Structural and dielectric studies of LiNiPO4 and LiNi0.5Co0.5PO4 cathode materials for lithium-ion batteries

Directory of Open Access Journals (Sweden)

K. Vijaya Babu

2016-09-01

Full Text Available Olivine-type LiNiPO4 has been considered as a most competitive positive electrode active material for lithium-ion batteries. In the present paper, the LiNiPO4 and Co-doped LiNi0.5Co0.5PO4 are synthesized by solid-state reaction method under air atmosphere. All the X-ray diffraction peaks of both the compounds are indexed and it is found that the samples are well crystallized in orthorhombic olivine structure belonging to the space group Pnma. The crystallite size is calculated from the Scherrer formula and it is found to be 6.918 and 4.818 nm for pure and doped samples, respectively. The surface morphology and grain sizes of the materials are investigated through scanning electron microscope. Presence of preferred local cation environment is understood from Fourier transform infrared spectroscopy (FTIR studies. The conductivity and dielectric analysis of the samples are carried out at different temperatures and frequencies using the complex impedance spectroscopy technique. The electrical conductivity of LiNi0.5Co0.5PO4 is higher than that of pure LiNiPO4.

Stratigraphically significant conodonts from the Lochkovian of the Požáry section (Barrandian area, Czechia)

Czech Academy of Sciences Publication Activity Database

Slavík, Ladislav; Carls, P.; Valenzuela-Ríos, J. I.

2003-2004, 33-34 (2006), s. 81-82. ISBN 80-210-4097-1. ISSN 1211-281X. [Paleontological Conference /7./. Brno, 19.10.2006-20.10.2006] R&D Projects: GA AV ČR(CZ) KJB300130613 Institutional research plan: CEZ:AV0Z30130516 Keywords : Lochkovian * Conodonts * Barrandian * Požáry section * biostratigraphy Subject RIV: EG - Zoology

Dosimetry of 210Po in humans, caribou, and wolves in northern Canada

International Nuclear Information System (INIS)

Thomas, P.A.

1994-01-01

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

Radiochemical determination of 210Po

International Nuclear Information System (INIS)

Clarence, J.

1961-04-01

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

210Po radiation dose due to cigarette smoking

International Nuclear Information System (INIS)

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

2010-01-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Distribution of {sup 210}Pb and {sup 210}Po concentrations in wild berries and mushrooms in boreal forest ecosystems

Energy Technology Data Exchange (ETDEWEB)

Vaaramaa, Kaisa, E-mail: Kaisa.Vaaramaa@Helsinki.fi [Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, FI-00014 University of Helsinki (Finland); Solatie, Dina [STUK-Radiation and Nuclear Safety Authority, Regional Laboratory in Northern Finland, FI-96500 Rovaniemi (Finland); Aro, Lasse [Finnish Forest Research Institute (METLA), Parkano Research Unit, FI-39700 Parkano (Finland)

2009-12-15

The activity concentrations and distribution of {sup 210}Pb and {sup 210}Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of {sup 210}Pb and {sup 210}Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems > leaves > berries (i.e. fruits). The activity ratios of {sup 210}Po/{sup 210}Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of {sup 210}Pb and especially {sup 210}Po were higher than in fruits of the wild berries. The highest activity concentration of {sup 210}Pb was detected in Cortinarius armillatus L. (16.2 Bq kg{sup -1} d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg{sup -1} d.w.). The {sup 210}Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg{sup -1} d.w. (Russula paludosa L.) to 1174 Bq kg{sup -1} d.w. (L. vulpinum L.). In general, the highest activity concentrations of {sup 210}Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of {sup 210}Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of {sup 210}Po were higher than those of {sup 210}Pb. {sup 210}Po and {sup 210}Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by {sup 137}Cs from the Chernobyl fallout.

Enhanced electrochemical performance of different morphological C/LiMnPO4 nanoparticles from hollow-sphere Li3PO4 precursor via a delicate polyol-assisted hydrothermal method

Science.gov (United States)

Cui, Yu-Ting; Xu, Ning; Kou, Li-Qin; Wu, Meng-Tao; Chen, Li

2014-03-01

With the hollow-sphere Li3PO4 as precursor, a delicate polyol-assisted hydrothermal method is devised to synthesize high-performance LiMnPO4. Orthorhombic shaped, irregular flaky shaped and sphere-like LiMnPO4 are sequentially prepared by decreasing the water-diethylene glycol (DEG) ratio. The capacity, cycling stability and rate performance of all samples prepared by the new synthesis method are improved significantly. And the C/LiMnPO4 with irregular flaky shape exhibits a capacity of 154.1 mA h g-1 at C/20, 147.4 mA h g-1 at C/10 and 102.5 mA h g-1 at 2 C, which is the best performance ever reported for LiMnPO4 active material with similar carbon additives.

PoET: Polarimeters for Energetic Transients

Science.gov (United States)

McConnell, Mark; Barthelmy, Scott; Hill, Joanne

2008-01-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Natural Radioisotopes of Pb, Bi and Po in the Atmosphere of Coal Burning Area

Directory of Open Access Journals (Sweden)

Asnor Azrin Sabuti

2011-07-01

Full Text Available This paper is discussing the changes of natural radionuclides 210Pb, 210Bi and 210Po in atmospheric samples (rainwater and solid fallout caused by Sultan Salahuddin Abdul Aziz coal-fired Power Plant (SSAAPP operation. We also describe the seasonal changes of 210Pb, 210Bi and 210Po to the monsoon seasons in Peninsular Malaysia. Bulk atmospheric trap was used to collect atmospheric samples for five months (7 Feb 2007 to 27 July 2007 and placed within the SSAAPP area. The natural radionuclide activity levels in the atmosphere were affected by local meteorological conditions to impact their variance over time. As a result, the natural radionulides were increased from the ambient value in atmospheric particles (solid fallout, which related to coal combustion by-product releases into atmosphere. In contrast, this was giving relatively lower or in the same magnitude from most places of radionuclides in rainwater samples. Degree of changes between 210Pb, 210Bi and 210Po affected by high temperature combustions were found to be different for each nuclide due to their respective volatility. 210Po in rainwater and solid fallout were considerably low during early inter-monsoon period which mainly controlled by the rainfall pattern. On the other hand, 210Pb and 210Bi in solid fallout were recorded higher concentrations which associated to drier conditions and more particulate content in air column during southwest monsoon. The mean activity ratio of 210BiRW/210PbRW and 210PoRW/210PbRW are 0.47 ± 0.04 and 0.52 ± 0.17, respectively. Whereas for 210BiSF/210PbSF and 210PoSF/210PbSF are 0.52 ± 0.05 and 0.71 ± 0.13, respectively. Some results showed high activity ratios, reaching to 1.87 ± 0.08 for 210Bi/210Pb and 4.58 ± 0.55 for 210Po/210Pb, of which due to additional of 210Bi and 210Po excess. These ratios also indicating that 210Pb and 210Bi could potentially come from the same source, compared to 210Po which varied differently, showing evidence it came

Intake of 226Ra, 210Pb and 210Po with food in Poland

International Nuclear Information System (INIS)

Pietrzak-Flis, Z.; Chrzanowski, E.; Dembinska, S.

1997-01-01

Intake with food and water of 226 Ra, 210 Pb and 210 Po was determined for an adult population in regions of central, northern and northeastern Poland. The content of radionuclides was determined in the daily diet and, in the central region, also in foodstuffs and drinking water. The annual intake with foodstuffs was estimated on the basis of their average annual consumption. The 226 Ra intake in northeastern Poland was approximately 17% higher than the overall average, correlating well with the higher concentration of this radionuclide in the soil. The 210 Po/ 210 Pb ratio was close to unity in the continental regions, whereas at the Baltic Sea coast it was approximately 1.5. The latter value can be ascribed to a larger consumption of fish for which the 210 Po/ 210 Pb ratio was found to be approximately 10. In central Poland the largest intake of 226 Ra was with flour and vegetables (contribution approx. 60%), the largest intake of 210 Pb was with flour and meat (approx. 50%) and the largest intake of 210 Po was with fish (approx. 34%). From the intake and dose coefficient, annual effective doses were calculated. The dose from 210 Pb and 210 Po was approx. 54 μSv year -1 , and the dose from 226 Ra was approx. 4 μSv year -1

Impact of incorporation of chromium on electrochemical properties of LiFePO4/C for Li-ion batteries

Directory of Open Access Journals (Sweden)

Naik Amol

2015-12-01

Full Text Available LiFe0.95Cr0.05PO4/C was successfully synthesized by one-step solid-state reaction using a single mode microwave reactor. The effect of incorporation of chromium on LiFePO4 lattice parameters was systematically investigated by X-ray diffraction. Surface analysis was done by scanning electron microscopy and transmission electron microscopy. The ratio of amorphous to graphitic carbon was determined from Raman spectroscopic data. The influence of chromium incorporation on electrochemical properties was studied by recording charge/discharge cycles combined with electrochemical impedance spectroscopy (EIS and cyclic voltammetry. It was found that Cr incorporation significantly enhanced the electrochemical performance of LiFePO4 at all current densities up to 10 C. LiFe0.95Cr0.05PO4/C prepared exhibited the best performance with an initial specific discharge capacity of 157.7, 144.8, 138.3, 131.0, 124.1 and 111.1 mAh·g−1 at 0.1 C, 0.5 C, 1.0 C, 2.0 C, 5 C and 10 C, respectively. The doped sample displayed excellent capacity retention, which was substantially superior than that of pristine LiFePO4/C at a higher current rate.

Intermediate Temperature Fuel Cell Using CsH₂PO₄/ZrO₂-Based Composite Electrolytes

DEFF Research Database (Denmark)

Jensen, Annemette Hindhede; Li, Qingfeng; Christensen, Erik

2014-01-01

Proton conductors operating at intermediate temperatures are receiving significant attention due to their advantages over conventionally used materials in proton exchange membrane fuel cells. CsH2PO4 has proven to be proton conducting above 230°C, however within a narrow temperature range of the ...... to 280°C under low atmospheric humidification. Higher open circuit voltage and stability in the extended temperature range were achieved with composite electrolytes with a CsH2PO4 to ZrO2 molar ratio of 2....

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-15

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

Speciation of 210Po and 210Pb in air particulates determined by sequential extraction

International Nuclear Information System (INIS)

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 21 Po and 21 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 21 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/ 21- 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

Speciation of 210Po and 210Pb in air particulates determined by sequential extraction.

Science.gov (United States)

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.

Inhalation of {sup 210}Po and {sup 210}Pb from cigarette smoking in Poland

Energy Technology Data Exchange (ETDEWEB)

Skwarzec, B. E-mail: bosk@chemik.chem.univ.gda.pl; Ulatowski, J.; Struminska, D.I.; Borylo, A

2001-07-01

The carcinogenic effect of {sup 210}Po and {sup 210}Pb with respect to lung cancer is an important problem in many countries with very high cigarette consumption. Poland has one of the highest consumptions of cigarettes in the world. The results of {sup 210}Po determination on the 14 most frequently smoked brands of cigarettes which constitute over 70% of the total cigarette consumption in Poland are presented and discussed. Moreover, the polonium content in cigarette smoke was estimated on the basis of its activity in fresh tobaccos, ash, fresh filters and post-smoking filters. The annual effective doses were calculated on the basis of {sup 210}Po and {sup 210}Pb inhalation with the cigarette smoke. The results of this work indicate that Polish smokers who smoke one pack (20 cigarettes) per day inhale from 20 to 215 mBq of {sup 210}Po and {sup 210}Pb each. The mean values of the annual effective dose for smokers were estimated to be 35 and 70 {mu}Sv from {sup 210}Po and {sup 210}Pb, respectively. For persons who smoke two packs of cigarettes with higher radionuclide concentrations, the effective dose is much higher (471 {mu}Sv yr{sup -1}) in comparison with the intake in diet. Therefore, cigarettes and the absorption through the respiratory system are the main sources and the principal pathway of {sup 210}Po and {sup 210}Pb intake of smokers in Poland.

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}

Energy Technology Data Exchange (ETDEWEB)

Yahia, H. Ben [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Essehli, R., E-mail: ressehli@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar); Avdeev, M. [Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights NSW 2234 (Australia); Park, J-B.; Sun, Y-K. [Department of Energy Engineering Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Al-Maadeed, M.A. [Center for Advanced Materials (CAM), Qatar University, 2713 Doha (Qatar); Belharouak, I., E-mail: ibelharouak@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825 Doha (Qatar)

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.

Novel Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterojunction with enhanced photocatalytic activity and stability under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Teng, Wei, E-mail: tengw@just.edu.cn [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Tan, Xiangjun [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Li, Xinyong [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian, 116024 (China); Tang, Yubin [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China)

2017-07-01

Graphical abstract: Excellent photocatalytic activity and stability are achieved over Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterostructure nanocatalyst, which was increased the charge separation efficiencies. - Highlights: • The Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterostructure nanocatalyst was synthesized successfully. • The composite nanocatalyst possesses excellent photocatalytic activity and stability. • The effective separation of electron-hole pairs were mainly depend on the inner electric field of p-n heterojunction. - Abstract: Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterojunction have been successfully fabricated by using a simple in situ solvent method. SEM, TEM, XRD, XPS and electrochemical techniques were used to study the structural and electrochemical characteristics of the resulting materials. The photocatalytic activity of the obtained composite was tested by the degradation of organic dye (methylene blue) under visible-light irradiation. The photocatalytic activity of Ag{sub 3}PO{sub 4}/MoO{sub 3} remained 92.5% after four recycling runs, which was much higher than that of the pure Ag{sub 3}PO{sub 4} (54%). The obtained results confirm that the novel Ag{sub 3}PO{sub 4}/MoO{sub 3} heterostructure exhibited significantly higher photocatalytic activities and improved stability compared with bare Ag{sub 3}PO{sub 4}. The excellent photocatalytic activity came from the effective separation of the electron-hole pairs under the effect of built-in electric field in the interfacial the of the p-n heterojunction, and then made the holes more available for dyes oxidation.

Improving the electrochemical properties of nanosized LiFePO4-based electrode by boron doping

International Nuclear Information System (INIS)

Trócoli, Rafael; Franger, Sylvain; Cruz, Manuel; Morales, Julián; Santos-Peña, Jesús

2014-01-01

Highlights: • Thermal treatment of boron phosphate with LiFePO 4 provides electrode materials with high performance in lithium half-cells: 160 mAh·g -1 (90% of theoretical capacity) under C/5 rate • The products are composites containing boron-modified LiFePO 4 , FePO 4 and an amorphous phase with ionic diffusion properties • The boron treatment affects textural, conductive and lithium diffusivity of the electrode material leading to higher performance • A limited boron-doping of the phospholivine structure is observed - Abstract: Electrode materials with homogeneous distribution of boron were obtained by heating mixtures of nanosized carbon-coated lithium iron phosphate and BPO 4 in 3-9% weight at 700 °C. The materials can be described as nanocomposites containing i) LiFePO 4 , possibly doped with a low amount of boron, ii) FePO 4 and iii) an amorphous layer based on Li 4 P 2 O 7 -derived material that surrounds the phosphate particles. The thermal treatment with BPO 4 also triggered changes in the carbon coating graphitic order. Galvanostatic and voltammetric studies in lithium half-cells showed smaller polarisation, higher capacity and better cycle life for the boron-doped composites. For instance, one of the solids, called B 6 -LiFePO 4 , provided close to 150 and 140 mAhg -1 (87% and 81% of theoretical capacity, respectively) under C/2.5 and C regimes after several cycles. Improved specific surface area, carbon graphitization, conductivity and lithium ion diffusivity in the boron-doped phospholivine network account for this excellent rate performance. The properties of an amorphous layer surrounding the phosphate particles also account for such higher performance

Model analysis of the relationship between intracellular Po2 and energy demand in skeletal muscle

OpenAIRE

Spires, Jessica; Gladden, L. Bruce; Grassi, Bruno; Saidel, Gerald M.; Lai, Nicola

2012-01-01

On the basis of experimental studies, the intracellular O2 (iPo2)-work rate (WR) relationship in skeletal muscle is not unique. One study found that iPo2 reached a plateau at 60% of maximal WR, while another found that iPo2 decreased linearly at higher WR, inferring capillary permeability-surface area (PS) and blood-tissue O2 gradient, respectively, as alternative dominant factors for determining O2 diffusion changes during exercise. This relationship is affected by several factors, including...

Kinetics of neutralization of Po-218

International Nuclear Information System (INIS)

Chu, K.D.

1987-01-01

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

Po-210 and other radionuclides in terrestrial and freshwater environments

Energy Technology Data Exchange (ETDEWEB)

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

2009-01-15

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

Po-210 and other radionuclides in terrestrial and freshwater environments

International Nuclear Information System (INIS)

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

2009-01-01

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

Increased intraretinal PO2 in short-term diabetic rats.

Science.gov (United States)

Lau, Jennifer C M; Linsenmeier, Robert A

2014-12-01

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

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

International Nuclear Information System (INIS)

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

1997-01-01

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

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

Science.gov (United States)

Seiler, R.L.

2011-01-01

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

Bottom-up substitution assembly of AuF4-n0,-+nPO3 (n = 1-4): a theoretical study of novel oxyfluoride hyperhalogen molecules and anions AuF4-n(PO3)n0,-

Science.gov (United States)

Yang, Yi-fan; Cui, Zhong-hua; Ding, Yi-hong

2014-06-01

Compounds with high electron affinity, i.e. superhalogens, have continued to attract chemists' attention, due to their potential importance in fundamental chemistry and materials science. It has now proven very effective to build up novel superhalogens with multi-positively charged centres, which are usually called 'hyperhalogens'. Herein, using AuF4- and PO3 as the model building blocks, we made the first attempt to design the Au,P-based hyperhalogen anions AuF4-n(PO3)n- (n = 1-4) at the B3LYP/6-311+G(d)&SDD and CCSD(T)/6-311+G(d)&SDD (single-point) levels (6-311+G(d) for O, F, P and SDD for Au). Notably, for all the considered Au,P systems, the ground state bears a dioxo-bonded structure with n ≤ 3, which is significantly more stable than the usually presumed mono-oxo-bonded one. Moreover, the clustering of the -PO3 moieties becomes energetically favoured for n ≥ 3. The ground states of AuP4O120,- are the first reported cage-like oxide hyperhalogens. Thus, the -PO3 moiety cannot be retained during the 'bottom-up' assembly. The vertical detachment energy (VDE) value of the most stable AuF4-n(PO3)n- (n = 1-4) ranges from 7.16 to 8.20 eV, higher than the VDE values of the corresponding building blocks AuF4- (7.08 eV) and PO3- (4.69 eV). The adiabatic detachment energy values of these four hyperhalogens exceed 6.00 eV. Possible generation routes for AuF4-n(PO3)n- (n = 1-4) were discussed. The presently designed oxyfluorides not only enriches the family of hyperhalogens, but also demonstrates the great importance of considering the structural transformation during the superhalogen → hyperhalogen design such as for the present Au-P based systems.

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

International Nuclear Information System (INIS)

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

1995-01-01

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

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

Science.gov (United States)

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

2001-11-05

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

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

International Nuclear Information System (INIS)

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

2012-01-01

An easy and accurate method for the determination of 210 Pb and 210 Po in water using 210 Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of 210 Pb, 210 Bi and 210 Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of 210 Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between 210 Pb and 210 Bi and the second after a sufficient time for the ingrowth of 210 Po from 210 Pb to be significant. As shown, for a recommended time interval of seven months between 210 Po measurements, the applicability of the proposed method is limited to water samples with a 226 Ra to 210 Pb activity ratio C Ra /C Pb ≤4, as usual in natural waters. Using sample and background counting times of 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L sample typically varies between 0.7 and 16 mBq L −1 for 210 Pb in water samples with an initial activity of 210 Po in the range 0–200 mBq L −1 , and between 0.6 and 8.5 mBq L −1 for 210 Po in water samples with an initial activity of 210 Pb in the same range. - Highlights: ► 210 Pb and 210 Po measurement in water by 210 Po spontaneous deposition onto silver disks. ► 210 Pb and 210 Po determination based on 210 Po measurement in two different aliquots. ► Evaluation of characteristic limits in radioactivity measurements using ISO 11929-7. ► 10 Pb - 210 Po detection limits decrease with time elapsed between 210 Po measurements.

Po2 temperature blood factor for blood gas apparatus.

Science.gov (United States)

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

1984-01-01

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

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

International Nuclear Information System (INIS)

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

2001-01-01

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

[Effect of KH2PO4 on the odonto- and osteogenic differentiation potential of human stem cells from apical papillae].

Science.gov (United States)

Wang, Yan-ping; Wu, Jin-tao; Wang, Zi-lu; Zheng, Yang-yu; Zhang, Guang-dong; Yu, Jin-hua

2013-01-01

To determine the effects of KH2PO4 on the odonto- and osteogenic differentiation potential of human stem cells from apical papillae (SCAP) in vitro. SCAP were isolated and cultured respectively in alpha minimum essential medium (α-MEM) or α-MEM containing 1.8 mmol/L KH2PO4. Alkaline phosphatase (ALP) activity, alizarin red staining, real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were used to examine the odonto and osteogenic potential of SCAP in the two media. SCAP cultured in α-MEM containing 1.8 mmol/L KH2PO4 exhibited a higher ALP activity [(0.370 ± 0.013) Sigma unit×min(-1)×mg(-1)] at day 3 than control group [(0.285 ± 0.008) Sigma unit×min(-1)×mg(-1)] and KH2PO4-treated SCAP formed more calcified nodules at day 5 [(0.539 ± 0.007) µg/g] and day 7 [(1.617 ± 0.042) µg/g] than those in normal medium [(0.138 ± 0.037) µg/g, P odonto- and osteogenic markers were significantly up-regulated after the stimulation of KH2PO4 at day 3 and 7 respectively, as compared with control group. 1.8 mmol/L KH2PO4 can promote the odonto and osteogenic differentiation potential of human SCAP.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

LiFePO4/C nanocomposites for lithium-ion batteries

Science.gov (United States)

Eftekhari, Ali

2017-03-01

LiFePO4, as the most famous member of the family of olivine-type lithium transition metal phosphates, is one of the promising candidates for the cathodes of lithium-ion batteries. However, its battery performance is limited by its low electrical conductivity and slow Li solid-state diffusion. Various methods have been attempted to improve the battery performance of lithium iron phosphate. Among them, compositing the LiFePO4 with carbon nanomaterials seems to be the most promising, as it is facile and efficient. Carbon nanomaterials usually serve as a conductive agent to improve the electrical conductivity while increasing the material porosity in which the solid-state diffusion distances are significantly shortened. Owing to the popularity of various carbonaceous nanomaterials, there is no straightforward line of research for comparing the LiFePO4/C nanocomposites. This review aims to provide a general perspective based on the research achievements reported in the literature. While surveying the research findings reported in the literature, controversial issues are also discussed. The possible contribution of pseudocapacitance as a result of functionalized carbon or LiFePO4 lattice defects is described, since from a practical perspective, a LiFePO4/C electrode can be considered as a supercapacitor at high C rates (with a specific capacitance as large as 200 F g-1). The Li diffusion in LiFePO4 has not been well understood yet; while the Li diffusion within the LiFePO4 lattice seems to be quite fast, the peculiar interfacial electrochemistry of LiFePO4 slows down the diffusion within the entire electrode by a few orders of magnitude.

Po-210 excretion and radon exposure

International Nuclear Information System (INIS)

Breuer, F.; Clemente, G.F.

1979-01-01

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

Synthesis and electrochemical properties of Ti4+ doped Li3-xFe2-xTix(PO4)3/C cathode materials

International Nuclear Information System (INIS)

Liu Zhanqiang; Huang Fuqiang; Sun Junkang

2011-01-01

Highlights: → Li 3-x Fe 2-x Ti x (PO 4 ) 3 /C composite cathodes were prepared by ball-milling method. Ti-doping can improve the electrochemical property of Li 3 Fe 2 (PO 4 ) 3 . → The optimized doping level was found to be x = 0.2. → The second phase of LiTi 2 (PO 4 ) 3 will emerge if the doping level higher than 0.2. - Abstract: Li 3-x Fe 2-x Ti x (PO 4 ) 3 /C (x = 0-0.4) cathodes designed with Fe doped by Ti was studied. Both Li 3 Fe 2 (PO 4 ) 3 /C (x = 0) and Li 2.8 Fe 1.8 Ti 0.2 (PO 4 ) 3 /C (x = 0.2) possess two plateau potentials of Fe 3+ /Fe 2+ couple (around 2.8 V and 2.7 V vs. Li + /Li) upon discharge observed from galvanostatic charge/discharge and cyclic voltammetry. Li 2.8 Fe 1.8 Ti 0.2 (PO 4 ) 3 /C has higher reversibility and better capacity retention than that of the undoped Li 3 Fe 2 (PO 4 ) 3 /C. A much higher specific capacity of 122.3 mAh/g was obtained at C/20 in the first cycle, approaching the theoretical capacity of 128 mAh/g, and a capacity of 100.1 mAh/g was held at C/2 after the 20th cycle.

Preparation and photocatalytic degradation performance of Ag_3PO_4 with a two-step approach

International Nuclear Information System (INIS)

Li, Jiwen; Ji, Xiaojing; Li, Xian; Hu, Xianghua; Sun, Yanfang; Ma, Jingjun; Qiao, Gaowei

2016-01-01

Highlights: • Ag_3PO_4 photocatalysts were synthesized via one-step and two-step ion-exchange reaction. • Photocatalytic properties of Ag_3PO_4 photocatalysts was investigated, the result indicated the Ag_3PO_4 (2) was higher than that of Ag_3PO_4 (1) under the same experimental condition. • Ag_3PO_4 (2) particles were larger than Ag_3PO_4 (1) particles and many polygonal-shaped surfaces could be clearly observed in the Ag_3PO_4 (2) particles. - Abstract: Ag_3PO_4 photocatalysts were prepared via two and one-step through a facile ion-exchange route. The photocatalysts were then characterized through powder X-ray diffraction, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated on the basis of the photocatalytic degradation of methyl orange (MO) and methylene blue (MB) under solar irradiation. The MO degradation rate of the Photocatalyst synthesized by the two-step ion-exchange route was 89.18% in 60 min. This value was four times that of the Photocatalyst synthesized by the one-step approach.The MB degradation rate was 97% in 40 min. After six cycling runs were completed, the MO degradation rate was 73%

Concentration of 210Po in cigars

International Nuclear Information System (INIS)

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

2000-01-01

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

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

International Nuclear Information System (INIS)

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

1982-01-01

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

AgI/Ag3PO4 hybrids with highly efficient visible-light driven photocatalytic activity

International Nuclear Information System (INIS)

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

2015-01-01

Highlights: • AgI/Ag 3 PO 4 hybrid was prepared via an in situ anion-exchange method. • AgI/Ag 3 PO 4 displays the excellent photocatalytic activity under visible light. • AgI/Ag 3 PO 4 readily transforms to be Ag@AgI/Ag 3 PO 4 system. • h + and O 2 ·− play the major role in the AO 7 decolorization over AgI/Ag 3 PO 4 . • The activity enhancement is ascribed to a Z-scheme system composed of Ag 3 PO 4 , Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag 3 PO 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 3 PO 4 photocatalysts displayed the higher photocatalytic activity than pure Ag 3 PO 4 and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag 3 PO 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 3 PO 4 readily transformed to be Ag@AgI/Ag 3 PO 4 system while the photocatalytic activity of AgI/Ag 3 PO 4 remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h + and O 2 ·− play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag 3 PO 4 hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag 3 PO 4 , Ag and AgI, in which Ag nanoparticles act as the charge separation center

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Studies on the distribution of 210Po and 210Pb in the ecosystem of Point Calimere Coast (Palk Strait), India

International Nuclear Information System (INIS)

Suriyanarayanan, S.; Brahmanandhan, G.M.; Malathi, J.; Ravi Kumar, S.; Masilamani, V.; Shahul Hameed, P.; Selvasekarapandian, S.

2008-01-01

A systematic study on the natural radionuclides such as 210 Po and 210 Pb in the environmental matrices of Point Calimere ecosystem has been undertaken to establish a baseline data on the radiation profile of Point Calimere environment. The environmental samples such as water, sediment and biota (seaweeds, crustaceans, molluscs and fish) have been subjected to analyses. It has been observed that the concentration of 210 Po and 210 Pb in the water samples of Point Calimere to be 0.5 mBq/l and 1.3 mBq/l, respectively. The soft tissues of the organisms accumulated higher 210 Po content while shells and bones contained more 210 Pb. The bivalve molluscs Meretrix casta have been identified to accumulate higher concentration of 210 Po suggesting that they could serve as bio-indicator of radionuclides like 210 Po in the Point Calimere ecosystem. The concentration factor of 210 Po for the biotic components ranged from ∼10 3 to 10 6 while for 210 Pb it ranged from ∼10 3 to 10 5

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

Science.gov (United States)

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

2004-06-01

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

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

International Nuclear Information System (INIS)

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

1982-01-01

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

/sup 210/Po in marine organisms: a wide range of natural radiation dose domains

Energy Technology Data Exchange (ETDEWEB)

Carvalho, F P

1988-01-01

Marine biota is able to concentrate /sup 210/Po to high levels, as 10/sup 3/-10/sup 5/ relative to sea water concentration. /sup 210/Po concentrations in mixed zooplankton reaches 34-51 Bq.kg/sup -1/ (fresh wt), special groups such as copepods reaching even higher concentrations /similar to/ 90 Bq.kg/sup -1/, whereas gelatinous zooplankton display /similar to/ 1 Bq.kg/sup -1/. Epipelagic teleosts feeding on plankton displayed the highest concentrations found in fish muscle, 2-21 Bq.kg/sup -1/. Contrasting with this, demersal teleosts and elasmobranchs display lower /sup 210/Po concentrations, in the ranges 0.5-7 Bq.kg/sup -1/ and 0.2-1.7 Bq.kg/sup -1/, respectively. Much higher concentrations can, however, be measured in fish liver, gonad, bone and piloric caecca, and small mesopelagic fish can reach /similar to/ 800 Bq.kg/sup -1/ on a whole-body basis. Due to these /sup 210/Po activity concentrations, dose equivalent rates delivered to biological tissues in marine organisms can vary widely, from 0.4 mSv.y/sup -1/ in gelatinous plankton up to 5.6 x 10/sup 3/ mSv.y/sup -1/ in the gut wall of sardines. It is concluded that in organisms living in the same ocean layer a wide range of internal radiation doses exists and it is essentially sustained by /sup 210/Po food-chain transfer. (author).

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Gamma oscillations and spontaneous network activity in the hippocampus are highly sensitive to decreases in pO2 and concomitant changes in mitochondrial redox state.

Science.gov (United States)

Huchzermeyer, Christine; Albus, Klaus; Gabriel, Hans-Jürgen; Otáhal, Jakub; Taubenberger, Nando; Heinemann, Uwe; Kovács, Richard; Kann, Oliver

2008-01-30

Gamma oscillations have been implicated in higher cognitive processes and might critically depend on proper mitochondrial function. Using electrophysiology, oxygen sensor microelectrode, and imaging techniques, we investigated the interactions of neuronal activity, interstitial pO2, and mitochondrial redox state [NAD(P)H and FAD (flavin adenine dinucleotide) fluorescence] in the CA3 subfield of organotypic hippocampal slice cultures. We find that gamma oscillations and spontaneous network activity decrease significantly at pO2 levels that do not affect neuronal population responses as elicited by moderate electrical stimuli. Moreover, pO2 and mitochondrial redox states are tightly coupled, and electrical stimuli reveal transient alterations of redox responses when pO2 decreases within the normoxic range. Finally, evoked redox responses are distinct in somatic and synaptic neuronal compartments and show different sensitivity to changes in pO2. We conclude that the threshold of interstitial pO2 for robust CA3 network activities and required mitochondrial function is clearly above the "critical" value, which causes spreading depression as a result of generalized energy failure. Our study highlights the importance of a functional understanding of mitochondria and their implications on activities of individual neurons and neuronal networks.

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

Science.gov (United States)

Panatarani, Camellia; Joni, I. Made

2013-09-01

Solution phase method was used to synthesis nanocrystal LaPO4:Eu3+. Polyethylene glycol with vary molecular weight (MW) was added to allow an exothermic reaction to get a high crystalinity of LaPO4:Eu3+. The x-ray pattern of as prepared LaPO4 was obtained by using an X'pert PANalytical diffractometer with CuKα radiation (λ = 1.5406 Å) and the photoluminescent measurement spectra is obtained by using Fluorescence Spectrometer LS55, Perkin Elmer. The additional of various MW of polyethylene glycol into the precursor solution of LaPO4:Eu3+ affected the crystal structure and luminescent properties. Higher MW of PEG depressing the luminescent spectra. The emission origin from 5D0-7F4 transition vanished by additional 500,000 and 2,000,000 MW of PEG.

Spontaneous Fluctuations of PO2 in the Rabbit Somatosensory Cortex.

Science.gov (United States)

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

2016-01-01

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

Aberrant PO2 values in proficiency testing.

Science.gov (United States)

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

1993-03-01

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

Application of an in vitro digestion model for 210Po bioaccessibility assessment in seafood.

Science.gov (United States)

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

2017-12-01

This study aims to investigate the bioaccessibility of 210 Po in seafood and the impact of food preparation on this radionuclide. Polonium bioaccessibility is the fraction of 210 Po mobilised from food matrices into digestive extractants when applying an in vitro digestion model. The degree of bioaccessibility of 210 Po in food has important implications for estimating ingestion doses from this radionuclide. The simulation of gastrointestinal digestion was divided into three stages through the use of synthetic saliva, gastric and bile-pancreas solutions. Following pre-treatment with a saliva solution, raw and cooked seafood samples underwent one of the following treatments: (a) simulated gastric digestion only or (b) simulated complete gastrointestinal digestion (gastric digestion followed by bile-pancreas digestion). No significant difference (P > 0.05) in 210 Po mobility was found between samples that underwent gastric digestion compared to those that only underwent gastro-intestinal digestion. However, a significant difference (P 210 Po bioaccessibility was found between raw and cooked seafood undergoing both gastric and gastro-intestinal digestion.

Preparation of V-Doped LiFePO4/C as the Optimized Cathode Material for Lithium Ion Batteries.

Science.gov (United States)

Sun, Pingping; Zhang, Haiyang; Shen, Kai; Fan, Qi; Xu, Qingyu

2015-04-01

LiFe1-x,Vx,PO4/C composites were synthesized by solid state reaction. The effect of carbon coating and V doping on the performance of LiFePO4 has been systematically investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), charge/discharge and cyclic voltammetry (CV) measurement. The results show that carbon coating and proper amount of V incorporation do not significantly change the host crystal structure of LiFePO4, while the electrochemical performance of LiFePO4 can be significantly improved. Particularly, the LiFe0.96V0.04PO4/C exhibits the best performance with a specific discharge capacity of 105.5 mA h/g at 5.0 C, 90.3 mA h/g at 10 C and 66.7 mA h/g at 30 C with stable cycle performance, which is significantly improved compared with the pure LiFePO4/C. The cyclic voltammograms result reveals that V doping could decrease the resistance of LiFePO4/C composite electrode drastically and improve its reversibility.

The low temperature electrochemical performances of LiFePO4/C/graphene nanofiber with 3D-bridge network structure

International Nuclear Information System (INIS)

Xie, Dong; Cai, Guanglan; Liu, Zhichao; Guo, Ruisong; Sun, Dandan; Zhang, Chao; Wan, Yizao; Peng, Jianhong; Jiang, Hong

2016-01-01

Highlights: • Highly conductive graphene nanofibers were introduced into the LiFePO 4 /C matrix. • Graphene nanofiber modification improved the discharge capacity at low temperatures. • Graphene nanofiber reduced the polarization of the electrodes at low temperatures. • Modified electrodes exhibited decreased charge-transfer resistance. • Graphene nanofiber modified samples exhibited higher diffusion coefficient of lithium ions. - Abstract: Three-dimensionally assembled LiFePO 4 /C/graphene nanofiber composites were successfully prepared via a suspension mixing method followed by heat-treatment at 400 °C. A faster electron transfer, lower electrochemical polarization as well as higher diffusion coefficient of Li + are obtained with the assistance of graphene nanofibers. The 5 wt% graphene nanofibers modified electrode (G-5) delivers the best electrochemical kinetics including the lowest charge transfer resistance and highest diffusion coefficient of Li + at 0 °C and −20 °C, respectively. Likewise, the G-5 exhibits the highest charge-discharge capability and the most stable cycling performance at low operation temperatures compared with those of LiFePO 4 /C, 3 wt% and 7 wt% graphene nanofibers modified LiFePO 4 /C (G-3 and G-7) composites. The G-5 electrode shows a capacity of 92.8 mAh g −1 with 92.0% capacity retention after 200 cycles at 1C at −20 °C. The reasons for the significant improvement of the low operation temperatures electrochemical performances can be ascribed to the enhanced conductivity and reduced agglomeration of pristine particles due to the introduction of graphene nanofibers. These excellent low temperature performances show that graphene nanofibers modified LiFePO 4 /C electrodes are promising cathode candidates for lithium-ion batteries applications at low temperatures.

Study on SOC wavelet analysis for LiFePO4 battery

Science.gov (United States)

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.

Preparation and Characterisation of LiFePO4/CNT Material for Li-Ion Batteries

Directory of Open Access Journals (Sweden)

Rushanah Mohamed

2011-01-01

Full Text Available Li-ion battery cathode materials were synthesised via a mechanical activation and thermal treatment process and systematically studied. LiFePO4/CNT composite cathode materials were successfully prepared from LiFePO4 material. The synthesis technique involved growth of carbon nanotubes onto the LiFePO4 using a novel spray pyrolysis-modified CVD technique. The technique yielded LiFePO4/CNT composite cathode material displaying good electrochemical activity. The composite cathode exhibited excellent electrochemical performances with 163 mAh/g discharge capacity with 94% cycle efficiency at a 0.1 C discharge rate in the first cycle, with a capacity fade of approximately 10% after 30 cycles. The results indicate that carbon nanotube addition can enable LiFePO4 to display a higher discharge capacity at a fast rate with high efficiency. The research is of potential interest for the application of carbon nanotubes as a new conducting additive in cathode preparation and for the development of high-power Li-ion batteries for hybrid electric vehicles.

Regulation of the activity of the promoter of RNA-induced silencing, C3PO.

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

Xin Liu

2017-11-01

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

Continuous flame aerosol synthesis of carbon-coated nano-LiFePO4 for Li-ion batteries

Science.gov (United States)

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

Structural and electrochemical characterization of 0.7LiFePO4·0.3Li3V2(PO4)3/C cathode materials using PEG and glucose as carbon sources

International Nuclear Information System (INIS)

Ma, Pingping; Hu, Pu; Liu, Zhijian; Xia, Jianhua; Xia, Dingguo; Chen, Yu; Liu, Zhengang; Lu, Zhichao

2013-01-01

0.7LiFePO 4 ·0.3Li 3 V 2 (PO 4 ) 3 /C composites (LFVP/C) were synthesized via spray-drying technique followed by solid-state reaction approach using polyethylene glycol (PEG) and glucose as carbon sources. The samples were characterized by X-ray diffraction (XRD), X-ray absorption fine-structure spectroscopy (XAFS) and Raman spectroscopy. The results show that the bi-phase composite structure of LFVP/C contains olivine LiFePO 4 (LFP) and monoclinic Li 3 V 2 (PO 4 ) 3 (LVP). The lower intensity ratio of the I D /I G and A sp 3 /A sp 2 for PEG-200 indicates the formation of higher degree of graphitized carbon during the process, which would enhance the electronic conductivity. The composite obtained using PEG-200 as carbon source show excellent rate performance, delivering the discharge capacity of 120 mAh/g at the current density of 1.5 A/g

Influence of submarine groundwater discharge on "2"1"0Po and "2"1"0Pb bioaccumulation in fish tissues

International Nuclear Information System (INIS)

Garcia-Orellana, J.; López-Castillo, E.; Casacuberta, N.; Rodellas, V.; Masqué, P.; Carmona-Catot, G.

2016-01-01

This study presents the results of the accumulation of "2"1"0Po and "2"1"0Pb in fish tissues and organs in a brackish-water marshland that is characterized by high concentrations of "2"2"2Rn and "2"2"6Ra 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 "2"1"0Pb and "2"1"0Po (up to 55 and 66 times, respectively) compared to blanks. The major input route of "2"1"0Pb and "2"1"0Po into the fish body seems to be through ingestion, due to the high levels of "2"1"0Pb and "2"1"0Po found in the gut content as well as in organs involved in digestion and metabolism (i.e. gut, kidney and hepatopancreas). Results showed that "2"1"0Po was more accumulated in all fish tissues and organs except for the spine, which showed a higher affinity for "2"1"0Pb, 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 "2"1"0Pb and "2"1"0Po 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 "2"1"0Pb and "2"1"0Po in fish tissues/organs. Thus, this study represents one of the first evidences of direct ecological effects derived from SGD. - Highlights: • Fish tissues showed high concentrations of "2"1"0Pb and "2"1"0Po. • Ingestion pointed to be the major input route of "2"1"0Pb and "2"1"0Po into the fish. �

Single-crystalline LiFePO4 nanosheets for high-rate Li-ion batteries.

Science.gov (United States)

Zhao, Yu; Peng, Lele; Liu, Borui; Yu, Guihua

2014-05-14

The lithiation/delithiation in LiFePO4 is highly anisotropic with lithium-ion diffusion being mainly confined to channels along the b-axis. Controlling the orientation of LiFePO4 crystals therefore plays an important role for efficient mass transport within this material. We report here the preparation of single crystalline LiFePO4 nanosheets with a large percentage of highly oriented {010} facets, which provide the highest pore density for lithium-ion insertion/extraction. The LiFePO4 nanosheets show a high specific capacity at low charge/discharge rates and retain significant capacities at high C-rates, which may benefit the development of lithium batteries with both favorable energy and power density.

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

Science.gov (United States)

Kim, Ketack; Jeong, Ji Hwa; Kim, Ick-Jun; Kim, Hyun-Soo

Kitchen oils (olive, soybean and butter) are selected for carbon coatings on LiFePO 4. The surface properties of LiFePO 4 are unknown or vary depending on synthetic methods. The multi-functional groups of fatty acids in the oils can orient properly to cope with the variable surface properties of LiFePO 4, which can lead to dense carbon coatings. The low price and low toxicity of kitchen oils are other advantages of the coating process. LiFePO 4 (D 50 = 121 nm)combined with the carbon coating enhances the rate capability. Capacities at the 2 C rate reach 150 mAh g -1 or higher. The charge retention values of 2.0 C/0.2 C are between 94.4 and 98.9%.

Ag3PO4/ZnO: An efficient visible-light-sensitized composite with its application in photocatalytic degradation of Rhodamine B

International Nuclear Information System (INIS)

Liu, Wei; Wang, Mingliang; Xu, Chunxiang; Chen, Shifu; Fu, Xianliang

2013-01-01

Graphical abstract: The free OH radicals generated in the VB of ZnO play the primary role in the visible-light photocatalytic degradation of RhB in Ag 3 PO 4 /ZnO system. The accumulated electrons in the CB of Ag 3 PO 4 can be transferred to O 2 adsorbed on the surface of the composite semiconductors and H 2 O 2 yields. H 2 O 2 reacts with electrons in succession to produce active ·OH to some extent. Display Omitted Highlights: ► Efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites were successfully prepared. ► Effect of Ag 3 PO 4 content on the catalytic activity of Ag 3 PO 4 /ZnO is studied in detail. ► Rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of Ag 3 PO 4 . ► The active species in RhB degradation are examined by adding a series of scavengers. ► Visible light degradation mechanism of RhB over Ag 3 PO 4 /ZnO is systematically studied. -- Abstract: The efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites with various weight percents of Ag 3 PO 4 were prepared by a facile ball milling method. The photocatalysts were characterized by XRD, DRS, SEM, EDS, XPS, and BET specific area. The ·OH radicals produced during the photocatalytic reaction was detected by the TA–PL technique. The photocatalytic property of Ag 3 PO 4 /ZnO was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. Significantly, the results revealed that the photocatalytic activity of the composites was much higher than that of pure Ag 3 PO 4 and ZnO. The rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of single-phase Ag 3 PO 4 . The optimal percentage of Ag 3 PO 4 in the composite is 3.0 wt.%. It is proposed that the ·OH radicals produced in the valence band of ZnO play the leading role in the photocatalytic degradation of Rhodamine B by Ag 3 PO 4 /ZnO systems under visible light irradiation.

Raman and NMR studies of aged LiFePO4 cathode

International Nuclear Information System (INIS)

Nagpure, Shrikant C.; Bhushan, Bharat; Babu, S.S.

2012-01-01

Highlights: ► Raman spectroscopy used to characterize the quality of carbon coating in LiFePO 4 commercial cells aged with C-rate. ► Structural change in the carbon coating leading to low electrical conductivity is observed for the cells aged at higher C-rate. ► Nuclear magnetic spectroscopy used to characterize LiFePO 4 nanoparticles for the presence of Li. ► 7 Li peak is observed in an unaged cell, while the similar peak is absent in the aged cells. - Abstract: The carbon coated LiFePO 4 nanoparticles are used in advanced lithium-ion batteries due to low cost, high energy and power density. In this paper Raman spectroscopy is used to analyze the degradation of carbon coating around these nanoparticles in several commercial cells aged with different C-rate. Magic angle spinning 7 Li Nuclear magnetic resonance (NMR) spectroscopy is used to characterize these nanoparticles for the presence of Li. In Raman spectroscopy data, structural change in the carbon leading to low electrical conductivity is observed for the cells aged at higher C-rate. In NMR spectroscopy data, isotropic 7 Li peak is observed in an unaged cell, while the similar peak is absent in the aged cells.

Unusual {sup 210}Po/{sup 210}Pb ratios in the surface water of the Gulf of Lions; Rapports {sup 210}Po/{sup 210}Pb inhabituels dans l`eau superficielle du golfe du Lion

Energy Technology Data Exchange (ETDEWEB)

Radakovitch, O.; Heussner, S. [Universite de Perpignan, 66 (France). Laboratoire de Sedimentologie et Geochimie Marines]|[Cerege, Europole de l`Arbois, 13 - Aix-en-Provence (France); Cherry, R.D.; Heyraud, M. [Cape Town Univ. (South Africa). Dept. of Physics

1998-05-01

Concentrations of {sup 210}Po and {sup 210}Pb have been measured in sea water collected in the Grand Rhone Canyon. Concentrations of {sup 210}Pb are at similar levels to those found in other Mediterranean sea water samples, and are at the levels which would be expected in comparison with global sea water data. The same applies to the {sup 210}Po concentrations in samples from below 100 m depth. Surface samples from above 100 m have {sup 210}Po at levels rather higher than expected, and their {sup 210}Po/{sup 210}Pb ratios are about 1 or more as compared with the usual open ocean ratio 0.5. These data can be interpreted as indicating another source of supply of {sup 210}Po to the surface layer in addition to the normal atmospheric input. We suggest that an episodic advective particulate input, probably originating in the output of the Rhone river and perhaps involving resuspension of fine particulates from the bottom sediments as a result of storm conditions, is he most likely candidate for this additional source. (authors) 47 refs.

Simultaneous measurement of pO2 and perfusion in the rabbit kidney in vivo.

Science.gov (United States)

O'Connor, Paul M; Anderson, Warwick P; Kett, Michelle M; Evans, Roger G

2007-01-01

Recently, a combined probe has been developed capable of simultaneous measurement of local tissue pO2 (fluorescence oximetry) and microvascular perfusion (laser Doppler flux) within the same local region. The aim of the current study was to test the utility of these combined probes to measure pO2 and perfusion in the kidney. Studies were performed in anesthetized, artificially ventilated rabbits (n=7). Baseline measurements of renal medullary perfusion and pO2 obtained using combined probes (537 +/- 110 units & 28.7 +/- 6.l mmHg, respectively) were indistinguishable from those obtained using independent probes (435 +/- 102 units & 26.9 +/- 6.4 mmHg). Baseline measurements of renal cortical pO2 were also similar between combined (9.7 +/- 1.6 mmHg) and independent probes (9.5 +/- 2.3 mmHg). Baseline levels of cortical perfusion however, were significantly greater when measured using independent probes (1130 +/- 114 units) compared to combined probes (622 +/- 59 units; P pO2 resulting from graded stimulation of the renal nerves were not significantly different when measured using combined probes to those obtained using independent probes. We conclude that combined probes are equally suitable to independent probes for tissue pO2 and microvascular perfusion measurement in the kidney. Our results raise some concerns regarding the accuracy of these OxyLite fluorescence probes for pO2 measurement in the kidney, particularly within the renal cortex.

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

International Nuclear Information System (INIS)

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

2015-01-01

Experiments were carried out in a small enclosed booth for the purpose of understanding and modelling 218 Po behaviour. The experiment was conducted under two kinds of conditions without and with injection of incense smoke. A working model of 218 Po behaviour was applied to analyse the measured data. Under the condition without incense smoke, temporal changes in aerosol-attached and unattached 218 Po concentrations were successfully reproduced by the model. The deposition rate of unattached fraction and the rate of attachment were determined by the working model. Under the condition with incense smoke, temporal changes in 218 Po concentration were poorly simulated by the model. This can be attributed to the significantly increased aerosol concentration in small size ranges which is not properly considered in the attachment rate calculation in the model. (authors)

PO2 measurements in the microcirculation using phosphorescence quenching microscopy at high magnification.

Science.gov (United States)

Golub, Aleksander S; Pittman, Roland N

2008-06-01

In phosphorescence quenching microscopy (PQM), the multiple excitation of a reference volume produces the integration of oxygen consumption artifacts caused by individual flashes. We analyzed the performance of two types of PQM instruments to explain reported data on Po2 in the microcirculation. The combination of a large excitation area (LEA) and high flash rate produces a large oxygen photoconsumption artifact manifested differently in stationary and flowing fluids. A LEA instrument strongly depresses Po2 in a motionless tissue, but less in flowing blood, creating an apparent transmural Po2 drop in arterioles. The proposed model explains the mechanisms responsible for producing apparent transmural and longitudinal Po2 gradients in arterioles, a Po2 rise in venules, a hypothetical high respiration rate in the arteriolar wall and mesenteric tissue, a low Po2 in lymphatic microvessels, and both low and uniform tissue Po2. This alternative explanation for reported paradoxical results of Po2 distribution in the microcirculation obviates the need to revise the dominant role of capillaries in oxygen transport to tissue. Finding a way to eliminate the photoconsumption artifact is crucial for accurate microscopic oxygen measurements in microvascular networks and tissue. The PQM technique that employs a small excitation area (SEA) together with a low flash rate was specially designed to avoid accumulated oxygen photoconsumption in flowing blood and lymph. The related scanning SEA instrument provides artifact-free Po2 measurements in stationary tissue and motionless fluids. Thus the SEA technique significantly improves the accuracy of microscopic Po2 measurements in the microcirculation using the PQM.

Radioactive 210Po in magnesium supplements

International Nuclear Information System (INIS)

Struminska-Parulska, Dagmara Ida

2016-01-01

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

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

International Nuclear Information System (INIS)

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

2013-01-01

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

The phase transition of the incommensurate phases β-Ln(PO3)3(Ln=Y,Tb…Yb), crystal structures of α-Ln(PO3)3(Ln=Y,Tb…Yb) and Sc(PO3)3

Science.gov (United States)

Höppe, Hennig A.

2009-07-01

The incommensurately modulated room-temperature phases β-Ln(PO3)3(Ln=Y,Tb…Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to α-Ln(PO3)3(Ln=Y,Dy…Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (α-Dy(PO3)3, P21/c, Z=12,a=14.1422(6), b=20.0793(9),c=10.1018(4) A˚, β=127.532(3)∘). α-Tb(PO3)3 is isotypic with Gd(PO3)3(α-Tb(PO3)3, I2/a,Z=16,a=25.875(6), b=13.460(3), c=10.044(2) A˚, β=119.13(3)∘). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO3)3 is isotypic with that of Lu(PO3)3 and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO4 tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed.

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Higher-Order Hierarchies

DEFF Research Database (Denmark)

Ernst, Erik

2003-01-01

This paper introduces the notion of higher-order inheritance hierarchies. They are useful because they provide well-known benefits of object-orientation at the level of entire hierarchies-benefits which are not available with current approaches. Three facets must be adressed: First, it must be po...

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

International Nuclear Information System (INIS)

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

1991-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1991-01-01

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

Concentrations and temporal variations of /sup 210/Po, /sup 210/Pb, and Al in the surf zone ecosystem of Copalis Beach, Washington

Energy Technology Data Exchange (ETDEWEB)

Bennett, J T; Carpenter, R

1979-01-01

Surf diatoms monitored during a 21-month period at Copalis Beach, Washington, contained elevated concentrations of Al, /sup 210/Pb, and supported /sup 210/Po compared to net phytoplankton from Washington coastal waters and Puget Sound. Aluminum concentrations of several percent dry weight found in the surf diatoms were not a reflection of contamination by discrete inorganic particulate matter but were the result of a natural coating of clay-sized particles on Chaetoceros armatum, the predominant diatom in the surfblooms. A high correlation between Al and /sup 210/Pb in the surf diatoms suggests /sup 210/Pb and supported /sup 210/Po were also associated with the clay-sized particles. During fall through spring, the unsupported /sup 210/Po concentrations in the surf diatoms were correlated with the input of /sup 210/Po by precipitation. A summer maximum in unsupported /sup 210/Po concentrations in the surf diatoms may reflect upwelling that causes higher dissolved /sup 210/Po concentrations in the summer surf relative to those of late spring and early fall. The consumers of the surf diatoms exhibited larger /sup 210/Po-activity-to-/sup 210/Pb-activity ratios than their food, indicating /sup 210/Po was preferentially accumulated in the higher trophic level.

Origin of Activity and Stability Enhancement for Ag3PO4 Photocatalyst after Calcination

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Pengyu Dong

2016-11-01

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

The phase transition of the incommensurate phases β-Ln(PO3)3(Ln=Y,Tb...Yb), crystal structures of α-Ln(PO3)3(Ln=Y,Tb...Yb) and Sc(PO3)3

International Nuclear Information System (INIS)

Hoeppe, Hennig A.

2009-01-01

The incommensurately modulated room-temperature phases β-Ln(PO 3 ) 3 (Ln=Y,Tb...Yb) undergo a topotactic phase transition monitored by vibrational spectroscopy below 180 K leading to α-Ln(PO 3 ) 3 (Ln=Y,Dy...Yb), above 200 K the incommensurate phases are reobtained. The low-temperature phases exhibit a new structure type (α-Dy(PO 3 ) 3 ,P2 1 /c,Z=12,a=14.1422(6),b=20.0793(9),c=10.1018(4)A, β=127.532(3) 0 ). α-Tb(PO 3 ) 3 is isotypic with Gd(PO 3 ) 3 (α-Tb(PO 3 ) 3 ,I2/a,Z=16,a=25.875(6),b=13.460(3),c=10.044(2)A, β=119.13(3) 0 ). The symmetry relations between the involved phases of the phase transition are discussed. The crystal structure of Sc(PO 3 ) 3 is isotypic with that of Lu(PO 3 ) 3 and C-type phosphates. The polyphosphates consist of infinite zig-zag chains of corner-sharing PO 4 tetrahedra, the cations are coordinated sixfold in an almost octahedral arrangement. To confirm the quality of the determined crystal structures the deviation of the phosphate tetrahedra from ideal symmetry was determined and discussed. - Abstract: Basic structure from which all crystal structures of the late lanthanoids' polyphosphates at room temperature and below can be derived.

Interplay of tumor vascular oxygenation and tumor pO2 observed using near-infrared spectroscopy, an oxygen needle electrode, and 19F MR pO2 mapping.

Science.gov (United States)

Kim, Jae G; Zhao, Dawen; Song, Yulin; Constantinescu, Anca; Mason, Ralph P; Liu, Hanli

2003-01-01

This study investigates the correlation of tumor blood oxygenation and tumor pO(2) with respect to carbogen inhalation. After having refined and validated the algorithms for calculating hemoglobin concentrations, we used near-infrared spectroscopy (NIRS) to measure changes of oxygenated hemoglobin concentration (delta[HbO(2)]) and used an oxygen needle electrode and (19)F MRI for pO(2) measurements in tumors. The measurements were taken from Dunning prostate R3327 tumors implanted in rats, while the anesthetized rats breathed air or carbogen. The NIRS results from tumor measurements showed significant changes in tumor vascular oxygenation in response to carbogen inhalation, while the pO(2) electrode results showed an apparent heterogeneity for tumor pO(2) response to carbogen inhalation, which was also confirmed by (19)F MR pO(2) mapping. Furthermore, we developed algorithms to estimate hemoglobin oxygen saturation, sO(2), during gas intervention based on the measured values of delta[HbO(2)] and pO(2). The algorithms have been validated through a tissue-simulating phantom and used to estimate the values of sO(2) in the animal tumor measurement based on the NIRS and global mean pO(2) values. This study demonstrates that the NIRS technology can provide an efficient, real-time, noninvasive approach to monitoring tumor physiology and is complementary to other techniques, while it also demonstrates the need for an NIR imaging technique to study spatial heterogeneity of tumor vasculature under therapeutic interventions. Copyright 2003 Society of Photo-Optical Instrumentation Engineers

Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

Energy Technology Data Exchange (ETDEWEB)

Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika; Shah, Mohd Syed; Sheikh, H.N., E-mail: hnsheikh@rediffmail.com

2016-08-15

Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.

Una poética del pliegue

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Ana Porrúa

2000-11-01

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

Una poética del pliegue

Directory of Open Access Journals (Sweden)

Ana Porrúa

2001-11-01

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

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Unusual 210Po/210Pb ratios in the surface water of the Gulf of Lions

International Nuclear Information System (INIS)

Radakovitch, O.; Heussner, S.; Cherry, R.D.; Heyraud, M.

1998-01-01

Concentrations of 210 Po and 210 Pb have been measured in sea water collected in the Grand Rhone Canyon. Concentrations of 210 Pb are at similar levels to those found in other Mediterranean sea water samples, and are at the levels which would be expected in comparison with global sea water data. The same applies to the 210 Po concentrations in samples from below 100 m depth. Surface samples from above 100 m have 210 Po at levels rather higher than expected, and their 210 Po/ 210 Pb ratios are about 1 or more as compared with the usual open ocean ratio 0.5. These data can be interpreted as indicating another source of supply of 210 Po to the surface layer in addition to the normal atmospheric input. We suggest that an episodic advective particulate input, probably originating in the output of the Rhone river and perhaps involving resuspension of fine particulates from the bottom sediments as a result of storm conditions, is he most likely candidate for this additional source. (authors)

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

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Laurent Robert

2012-04-01

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

Measurement of 210Po in vegetables of Gudalore

International Nuclear Information System (INIS)

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

1999-01-01

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

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

International Nuclear Information System (INIS)

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

2015-01-01

Graphical abstract: - Highlights: • Highly efficient visible-light-driven Ag 3 PO 4 /SBA-15 nanocomposite. • Application in the photo-degradation of RhB. • Synthesis from a facile and simple colloidal method. • 20%-Ag 3 PO 4 /SBA-15 shows 8 times faster degradation rate than Ag 3 PO 4 . • Super stability and recycling ability. - Abstract: A novel visible light-driven environmental-benign Ag 3 PO 4 /SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag 3 PO 4 /SBA-15 nanocomposite increases by 3 times compared with that of the Ag 3 PO 4 particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag 3 PO 4 nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag 3 PO 4 loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag 3 PO 4 /SBA-15. Compared to pure Ag 3 PO 4 nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag 3 PO 4 /SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and N 2 -adsorption–desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag 3 PO 4 /SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag 3 PO 4 loading on the SBA-15 catalyst will not result in the extra environment and health problems and reduce the cost of wastewater treatment

Synergistic combination of hyperoxygenation and radiotherapy by repeated assessments of tumor pO2 with EPR oximetry

Science.gov (United States)

HOU, Huagang; DONG, Ruhong; LARIVIERE, Jean P.; MUPPARAJU, Sriram P.; SWARTZ, Harold M.; KHAN, Nadeem

2013-01-01

The effect of hyperoxygenation with carbogen (95% O2 + 5% CO2) inhalation on RIF-1 tumor pO2 and its consequence on growth inhibition with fractionated radiotherapy is reported. The temporal changes in the tumor pO2 were assessed by in vivo Electron Paramagnetic Resonance (EPR) oximetry in mice breathing 30% O2 or carbogen and the tumors were irradiated with 4 Gy/day for 5 consecutive days; a protocol that emulates the clinical application of carbogen. The RIF-1 tumors were hypoxic with a tissue pO2 of 5 – 9 mm Hg. Carbogen (CB) breathing significantly increased tumor pO2, with a maximum increase at 22.9 – 31.2 min on days 1 – 5, however, the magnitude of increase in pO2 declined on day 5. Radiotherapy during carbogen inhalation (CB/RT) resulted in a significant tumor growth inhibition from day 3 to day 6 as compared to 30%O2/RT and carbogen (CB/Sham RT) groups. The results provide unambiguous quantitative information on the effect of carbogen inhalation on tumor pO2 over the course of 5 days. Tumor growth inhibition in the CB/RT group confirms that the tumor oxygenation with carbogen was radiobiologically significant. Repeated tumor pO2 measurements by EPR oximetry can provide temporal information that could be used to improve therapeutic outcomes by scheduling doses at times of improved tumor oxygenation. PMID:21799293

Synergistic combination of hyperoxygenation and radiotherapy by repeated assessments of tumor pO2 with EPR oximetry

International Nuclear Information System (INIS)

Hou, H.; Dong, R.; Lariviere, J.P.; Mupparaju, S.P.; Swartz, H.M.; Khan, N.

2011-01-01

The effect of hyperoxygenation with carbogen (95% O 2 +5% CO 2 ) inhalation on radiation-induced fibrosarcoma (RIF-1) tumor pO 2 and its consequence on growth inhibition with fractionated radiotherapy is reported. The temporal changes in the tumor pO 2 were assessed by in vivo Electron Paramagnetic Resonance (EPR) oximetry in mice breathing 30% O 2 or carbogen and the tumors were irradiated with 4 Gy/day for 5 consecutive days; a protocol that emulates the clinical application of carbogen. The RIF-1 tumors were hypoxic with a tissue pO 2 of 5-9 mmHg. Carbogen (CB) breathing significantly increased tumor pO 2 , with a maximum increase at 22.9-31.2 min on days 1-5, however, the magnitude of increase in pO 2 declined on day 5. Radiotherapy during carbogen inhalation (CB/RT) resulted in a significant tumor growth inhibition from day 3 to day 6 as compared to 30%O 2 /RT and carbogen (CB/Sham RT) groups. The results provide unambiguous quantitative information on the effect of carbogen inhalation on tumor pO 2 over the course of 5 days. Tumor growth inhibition in the CB/RT group confirms that the tumor oxygenation with carbogen was radiobiologically significant. Repeated tumor pO 2 measurements by EPR oximetry can provide temporal information that could be used to improve therapeutic outcomes by scheduling doses at times of improved tumor oxygenation. (author)

(Solid + liquid) phase equilibria of (Ca(H2PO2)2 + CaCl2 + H2O) and (Ca(H2PO2)2 + NaH2PO2 + H2O) ternary systems at T = 323.15 K

International Nuclear Information System (INIS)

Cao, Hong-yu; Zhou, Huan; Bai, Xiao-qin; Ma, Ruo-xin; Tan, Li-na; Wang, Jun-min

2016-01-01

Graphical abstract: Solubility diagram of the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system at T = (323.15 and 298.15) K. - Highlights: • Phase diagrams of Ca 2+ -H 2 PO 2 − -Cl − -H 2 O, Ca 2+ -Na + -H 2 PO 2 − -H 2 O at 323.15 K were obtained. • Incompatible double salt of NaCa(H 2 PO 2 ) 3 in Ca 2+ -Na + -H 2 PO 2 − -H 2 O system was determined. • Density diagram of the corresponding liquid were simultaneously measured. - Abstract: Calcium hypophosphite has been widely used as an anti-corrosive agent, flame retardant, fertilizer, assistant for Ni electroless plating, and animal nutritional supplement. High purity calcium hypophosphite can be synthesized via the replacement reaction of sodium hypophosphite and calcium chloride. In this work, the (solid + liquid) phase equilibria of (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) and (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) ternary systems at T = 323.15 K were studied experimentally via the classical isothermal solubility equilibrium method, and the phase diagrams for these two systems were obtained. It was found that two solid salts of CaCl 2 ·2H 2 O and Ca(H 2 PO 2 ) 2 exist in the (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) system, and three salts of Ca(H 2 PO 2 ) 2 , NaH 2 PO 2 ·H 2 O and one incompatible double salt, NaCa(H 2 PO 2 ) 3 occur in the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system.

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

Science.gov (United States)

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

2016-12-01

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

Ingestion of polonium ((210)Po) via dietary sources in high background radiation areas of south India.

Science.gov (United States)

Arunachalam, Kantha Deivi; Baskaran, Kamesh Viswanathan; Rao, D D; Sathyapriya, R; Annamalai, Sathesh Kumar; Kuruva, Jaya Krishna; Hari, Shanmugamsundaram

2014-10-01

To study the distribution of Polonium ((210)Po) activity in dietary sources in the high background radiation zone of Puttetti in southern Tamil Nadu. (210)Po was analyzed in the food materials consumed by the male and female individual representatives living in the high background areas by 24-h Duplicate Diet Study (DDS) and Market Basket Study (MBS). The MBS was performed by collecting the food samples such as, cereals, fruits, leafy vegetables, roots and tubers, other vegetables, fish, meat and milk grown in the high background radiation zone of southern Tamil Nadu as a part of baseline study in this region. The DDS was done by collecting the food materials consumed including the beverages in 24 h from different age groups of male and female individuals living in the village of Puttetti. The intake and ingestion dose of the radionuclide (210)Po was estimated. The average concentration of (210)Po in DDS (n = 33) was found to be 74 mBq.kg(- 1) of fresh weight. The MBS was collected based on food consumption representing more than 85-95% of annual supply, and were divided into eight food groups. The average concentration of (210)Po in the eight food groups namely leafy vegetables was 2176 mBq.kg(- 1) (n = 3), vegetables 55 mBq.kg(- 1) (n = 10), roots and tubers 251 mBq.kg(- 1) (n = 4), fruits 65 mBq.kg(- 1) (n = 5), fish 345 mBq.kg(- 1) (n = 2), meat food 117 mBq.kg(- 1) (n = 3), milk 20 mBq.kg(- 1) (n = 1) and cereal 290 (n = 1) mBq.kg(- 1) of fresh weight, respectively. The annual intake and ingestion dose due to (210)Po was estimated by DDS and MBS in adults, adolescents and children. The overall results showed that the MBS was moderately higher than the DDS in all age groups. Moreover, a DDS approach may even be more realistic, as cooked foodstuffs are used for dietary exposure assessment. The study confirms that the current levels of (210)Po do not pose a significant radiological risk to the local inhabitants.

A cell wall-bound anionic peroxidase, PtrPO21, is involved in lignin polymerization in Populus trichocarpa

Energy Technology Data Exchange (ETDEWEB)

Lin, Chien-Yuan; Li, Quanzi; Tunlaya-Anukit, Sermsawat; Shi, Rui; Sun, Ying-Hsuan; Wang, Jack P.; Liu, Jie; Loziuk, Philip; Edmunds, Charles W.; Miller, Zachary D.; Peszlen, Ilona; Muddiman, David C.; Sederoff, Ronald R.; Chiang, Vincent L.

2016-03-11

Class III peroxidases are members of a large plant-specific sequence-heterogeneous protein family. Several sequence-conserved homologs have been associated with lignin polymerization in Arabidopsis thaliana, Oryza sativa, Nicotiana tabacum, Zinnia elegans, Picea abies, and Pinus sylvestris. In Populus trichocarpa, a model species for studies of wood formation, the peroxidases involved in lignin biosynthesis have not yet been identified. To do this, we retrieved sequences of all PtrPOs from Peroxibase and conducted RNA-seq to identify candidates. Transcripts from 42 PtrPOs were detected in stem differentiating xylem (SDX) and four of them are the most xylem-abundant (PtrPO12, PtrPO21, PtrPO42, and PtrPO64). PtrPO21 shows xylem-specific expression similar to that of genes encoding the monolignol biosynthetic enzymes. Using protein cleavage-isotope dilution mass spectrometry, PtrPO21 is detected only in the cell wall fraction and not in the soluble fraction. Downregulated transgenics of PtrPO21 have a lignin reduction of ~20% with subunit composition (S/G ratio) similar to wild type. The transgenics show a growth reduction and reddish color of stem wood. The modulus of elasticity (MOE) of the stems of the downregulated PtrPO21-line 8 can be reduced to ~60% of wild type. Differentially expressed gene (DEG) analysis of PtrPO21 downregulated transgenics identified a significant overexpression of PtPrx35, suggesting a compensatory effect within the peroxidase family. No significant changes in the expression of the 49 P. trichocarpa laccases (PtrLACs) were observed.

Carbon coatings with olive oil, soybean oil and butter on nano-LiFePO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Kim, Ketack; Jeong, Ji Hwa; Kim, Ick-Jun; Kim, Hyun-Soo [Battery Research Group, Korea Electrotechnology Research Institute, Changwon, 641-600 (Korea)

2007-05-15

Kitchen oils (olive, soybean and butter) are selected for carbon coatings on LiFePO{sub 4}. The surface properties of LiFePO{sub 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{sub 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{sub 4} (D{sub 50} = 121 nm)combined with the carbon coating enhances the rate capability. Capacities at the 2C rate reach 150 mAh g{sup -1} or higher. The charge retention values of 2.0C/0.2C are between 94.4 and 98.9%. (author)

Vibrational modes of deuterium in KD2PO4

International Nuclear Information System (INIS)

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

1993-01-01

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

Real-time monitoring of ischemic and contralateral brain pO2 during stroke by variable length multisite resonators.

Science.gov (United States)

Hou, Huagang; Li, Hongbin; Dong, Ruhong; Khan, Nadeem; Swartz, Harold

2014-06-01

Electron paramagnetic resonance (EPR) oximetry using variable length multi-probe implantable resonator (IR), was used to investigate the temporal changes in the ischemic and contralateral brain pO2 during stroke in rats. The EPR signal to noise ratio (S/N) of the IR with four sensor loops at a depth of up to 11 mm were compared with direct implantation of lithium phthalocyanine (LiPc, oximetry probe) deposits in vitro. These IRs were used to follow the temporal changes in pO2 at two sites in each hemisphere during ischemia induced by left middle cerebral artery occlusion (MCAO) in rats breathing 30% O2 or 100% O2. The S/N ratios of the IRs were significantly greater than the LiPc deposits. A similar pO2 at two sites in each hemisphere prior to the onset of ischemia was observed in rats breathing 30% O2. However, a significant decline in the pO2 of the left cortex and striatum occurred during ischemia, but no change in the pO2 of the contralateral brain was observed. A significant increase in the pO2 of only the contralateral non-ischemic brain was observed in the rats breathing 100% O2. No significant difference in the infarct volume was evident between the animals breathing 30% O2 or 100% O2 during ischemia. EPR oximetry with IRs can repeatedly assess temporal changes in the brain pO2 at four sites simultaneously during stroke. This oximetry approach can be used to test and develop interventions to rescue ischemic tissue by modulating cerebral pO2 during stroke. Copyright © 2014 Elsevier Inc. All rights reserved.

PoPSat: The Polar Precipitation Satellite Mission

Science.gov (United States)

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

2017-04-01

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

Evaluation of the amount of 210Po ingested by the Spanish population and its relation to their diet habit

International Nuclear Information System (INIS)

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

2013-01-01

In this work, the contribution of 210 Po to the committed effective dose via ingestion received by the Spanish population have been evaluated, by determining the 210 Po activity concentrations in an ample set of samples which can be considered representatives of the diet consumed in Spain. The obtained results show a quit high variability, preventing the possibility to fix a representative value for the 210 Po contribution to the ingestion doses received by the Spanish population, but in general these values, due exclusively to 210 Po, are higher than the average value assigned by UNSCEAR to the annual committed effective dose received by the worldwide population due to the ingestion of natural and anthropogenic radionuclides. Knowing the diet habits of the Spanish population and the 210 Po bioaccumulative behavior in the marine trophic chain, which implies enhanced concentration of 210 Po in the sea food in comparison with the obtained ones in other components of the diet, the variable and generally higher ingestion doses due to 210 Po received by the Spanish population can be associated to the variable and rich consumption of marine products. The Spanish population has the seafood as an essential component of his diet. Although the 210 Po levels in the edible parts of a great variety of marine organisms can be found in the literature in general the great majority of these determinations corresponds to raw edible products. But little is known about the effects of cooking on the 210 Po content of seafood which are normally cooked for human consumption. Then it is important to check if cooking can alter the 210 Po content in the seafood in order to refine the dose estimates to human consumers. Trying to cover this gap, and at the same time trying to confirm the key role of the seafood in the 210 Po ingestion doses received by the Spanish population, we have also analyzed the 210 Po content in the edible parts of several seafood products bought in commercial markets

Temporal changes of 210Po in temperate coastal waters

International Nuclear Information System (INIS)

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

1998-01-01

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

Temporal changes of 210Po in temperate coastal waters.

Science.gov (United States)

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

1998-06-18

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

RbCuFe(PO42

Directory of Open Access Journals (Sweden)

Mongi Ben Amara

2013-08-01

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

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

NARCIS (Netherlands)

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

2013-01-01

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

Aspects on the analysis of 210Po.

Science.gov (United States)

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

2011-05-01

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

Oxygen delivery to the fish eye: root effect as crucial factor for elevated retinal PO2.

Science.gov (United States)

Waser, W; Heisler, N

2005-11-01

successively with standardized red blood cell (RBC) suspensions in Ringer, using trout (with Root) and human (lacking any Root effect) RBC suspension. To optimize perfusate conditions for maximal Root effect, the Root effect of trout RBCs was determined in vitro via graded acidification of individual samples equilibrated with standardized gas mixtures. During perfusion with trout RBC, PO2 at the outer retinal limit was 99 mmHg (13.2 kPa), but fell by a factor of 3.3 upon perfusion with human RBC in spite of higher total oxygen content (TO2 2.8 for trout vs 3.9 mmol l-1 for human RBC). Upon reperfusion with trout RBC, PO2 was restored immediately to the original value. This regularly observed pattern indicated a highly significant difference (P=0.003) between perfusion with trout (with Root effect; high retinal PO2) and perfusion with human (no Root effect; low retinal PO2) RBC suspension, thus clearly demonstrating that the Root effect is directly involved and a crucial prerequisite for the enhancement of PO2 in the retina of the teleost eye.

Effect of carbon source on the morphology and electrochemical performances of LiFePO4/C nanocomposites.

Science.gov (United States)

Liu, Shuxin; Wang, Haibin; Yin, Hengbo; Wang, Hong; He, Jichuan

2014-03-01

The carbon coated LiFePO4 (LiFePO4/C) nanocomposites materials were successfully synthesized by sol-gel method. The microstructure and morphology of LiFePO4/C nanocomposites were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The results showed that the carbon layers decomposed by different dispersant and carbon source had different graphitization degree, and the sugar could decompose to form more graphite-like structure carbon. The carbon source and heat-treatment temperature had some effect on the particle size and morphology, the sample LFP-S700 synthesized by adding sugar as carbon source at 700 degrees C had smaller particle size, uniform size distribution and spherical shape. The electrochemical behavior of LiFePO4/C nanocomposites was analyzed using galvanostatic measurements and cyclic voltammetry (CV). The results showed that the sample LFP-S700 had higher discharge specific capacities, higher apparent lithium ion diffusion coefficient and lower charge transfer resistance. The excellent electrochemical performance of sample LFP-S700 could be attributed to its high graphitization degree of carbon, smaller particle size and uniform size distribution.

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

Science.gov (United States)

Liu, Qi; He, Hao; Li, Zhe-Fei; Liu, Yadong; Ren, Yang; Lu, Wenquan; Lu, Jun; Stach, Eric A; Xie, Jian

2014-03-12

We have performed operando synchrotron high-energy X-ray diffraction (XRD) to obtain nonintrusive, real-time monitoring of the dynamic chemical and structural changes in commercial 18650 LiFePO4/C cells under realistic cycling conditions. The results indicate a nonequilibrium lithium insertion and extraction in the LiFePO4 cathode, with neither the LiFePO4 phase nor the FePO4 phase maintaining a static composition during lithium insertion/extraction. On the basis of our observations, we propose that the LiFePO4 cathode simultaneously experiences both a two-phase reaction mechanism and a dual-phase solid-solution reaction mechanism over the entire range of the flat voltage plateau, with this dual-phase solid-solution behavior being strongly dependent on charge/discharge rates. The proposed dual-phase solid-solution mechanism may explain the remarkable rate capability of LiFePO4 in commercial cells.

DNA@Mn3(PO4)2 Nanoparticles Supported with Graphene Oxide as Photoelectrodes for Photoeletrocatalysis

Science.gov (United States)

Gao, Lixia; Xie, Jiale; Ma, Xiaoqing; Li, Man; Yu, Ling

2017-01-01

A novel deoxyribose nucleic acid (DNA)-based photoelectrode consisting of DNA@Mn3(PO4)2 nanoparticles on graphene oxide (GO) sheets was successfully fabricated for photoelectrocatalysis. DNA served as a soft template to guide the nucleation and growth of Mn3(PO4)2 nanoparticles in the synthesis of Mn3(PO4)2 nanoparticles. More importantly, the DNA also serves as semiconductor materials to adjust charge transport. Under UV light irradiation (180-420 nm, 15 mW/cm2), the photocurrent density of DNA@ Mn3(PO4)2/GO electrodes reached 9 μA/cm2 at 0.7 V bias (vs. SCE). An applied bias photon-to-current efficiency (ABPE) of 0.18% can be achieved, which was much higher than that of other control electrodes (<0.04%). In this DNA-based photoelectrode, well-matched energy levels can efficiently improve charge transfer and reduce the recombination of photogenerated electron-hole pairs.

Synthesis and characterization of LiFePO4/C cathode materials by sol-gel method.

Science.gov (United States)

Liu, Shuxin; Yin, Hengbo; Wang, Haibin; Wang, Hong

2014-09-01

The carbon coated LiFePO4 cathode materials (LiFePO4/C) were successfully synthesized by sol-gel method with glucose, citric acid and PEG-4000 as dispersant and carbon source, respectively. The microstructure and grain size of LiFePO4/C composite were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy. The results showed that the carbon source and calcination temperature had important effect on the graphitization degree of carbon; the carbon decomposed by citric acid had higher graphitization degree; with calcination temperature rising, the graphitization degree of carbon increased and the particles size increased. The graphitization degree and grain size were very important for improving the electrochemical performance of LiFePO4 cathode materials, according to the experimental results, the sample LFP-700 (LFP-C) which was synthesized with citric acid as dispersant at 700 degree C had lower polarization and larger discharge capacity.

Preparation, characterization and enhanced visible-light photocatalytic activities of BiPO4/BiVO4 composites

International Nuclear Information System (INIS)

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

2013-01-01

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

Microwave synthesis of molybdenum doped LiFePO4/C and its electrochemical studies.

Science.gov (United States)

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.

Une poétique du vœu : inspiration poétique et mystique impériale dans le poème XIX (et quelques autres d’Optatianus Porfyrius

Directory of Open Access Journals (Sweden)

Marie-Odile Bruhat

2010-11-01

Full Text Available La majorité des poèmes d’Optatianus Porfyrius qui nous sont parvenus est dédiée à l’empereur Constantin et consacrée à son éloge. Mais dans cette poésie visuelle d’un nouveau genre, la célébration de l’art poétique tient une place aussi importante que la célébration impériale. Comment considérer le discours proprement poétique d’Optatianus ? Est-il simplement juxtaposé au discours politique ? Relève-t-il d’une pure convention ornementale ? Ces questions sont d’autant plus pertinentes que, loin de présenter le procédé visuel dont il est l’inventeur comme un art technicien, Optatianus revendique le double titre de poiètès et de uates et convoque les divinités de l’inspiration, Phébus et les Muses, alors même que ses poèmes se font l’écho de la nouvelle théologie chrétienne du pouvoir. La réponse apparaît double. D’une part, la poésie d’Optatianus peut être définie comme votive. Ses poèmes s’inscrivent dans la liturgie du pouvoir, c’est-à-dire dans le cadre d’une théologie impériale qui repose sur l’affirmation de l’éternité de la victoire et sur le renouvellement du charisme victorieux à travers le rituel des voeux. Par son discours sur Phébus et les Muses, Optatianus met en place une véritable poétique du voeu, qui consiste à couler la mystique de l’inspiration dans le moule de la mystique impériale. D’autre part, ce projet poétique répond à bien des égards à l’attente impériale. Il rencontre la volonté de Constantin de développer une politique culturelle, et se plie à quelques traits caractéristiques de sa religiosité : conviction de la nécessité du secours divin dans les actions humaines, d’une inspiration divine dont Constantin a fait lui-même l’expérience, attention aux signes et aux visions, attachement à un charisme solaire qui coexiste sous une forme « neutralisée » avec sa foi chrétienne. Le poème XIX, composé à l�

210Po in the marine environment with emphasis on its behaviour within the biosphere.

Science.gov (United States)

Fowler, Scott W

2011-05-01

The distribution and behaviour of the natural-series alpha-emitter polonium-210 in the marine environment has been under study for many years primarily due to its enhanced bioaccumulation, its strong affinity for binding with certain internal tissues, and its importance as a contributor to the natural radiation dose received by marine biota as well as humans consuming seafoods. Results from studies spanning nearly 5 decades show that (210)Po concentrations in organisms vary widely among the different phylogenic groups as well as between the different tissues of a given species. Such variation results in (210)Po concentration factors ranging from approximately 10(3) to over 10(6) depending upon the organism or tissue considered. (210)Po/(210)Pb ratios in marine species are generally greater than unity and tend to increase up the food chain indicating that (210)Po is preferentially taken up by organisms compared to its progenitor (210)Pb. The effective transfer of (210)Po up the food chain is primarily due to the high degree of assimilation of the radionuclide from ingested food and its subsequent strong retention in the organisms. In some cases this mechanism may lead to an apparent biomagnification of (210)Po at the higher trophic level. Various pelagic species release (210)Po and (210)Pb packaged in organic biodetrital particles that sink and remove these radionuclides from the upper water column, a biogeochemical process which, coupled with scavenging rates of this radionuclide pair, is being examined as a possible proxy for estimating downward organic carbon fluxes in the sea. Data related to preferential bioaccumulation in various organisms, their tissues, resultant radiation doses to these species, and the processes by which (210)Po is transferred and recycled through the food web are discussed. In addition, the main gaps in our present knowledge and proposed areas for future studies on the biogeochemical behaviour of (210)Po and its use as a tracer of

210Po in the marine environment with emphasis on its behaviour within the biosphere

International Nuclear Information System (INIS)

Fowler, Scott W.

2011-01-01

The distribution and behaviour of the natural-series alpha-emitter polonium-210 in the marine environment has been under study for many years primarily due to its enhanced bioaccumulation, its strong affinity for binding with certain internal tissues, and its importance as a contributor to the natural radiation dose received by marine biota as well as humans consuming seafoods. Results from studies spanning nearly 5 decades show that 210 Po concentrations in organisms vary widely among the different phylogenic groups as well as between the different tissues of a given species. Such variation results in 210 Po concentration factors ranging from approximately 10 3 to over 10 6 depending upon the organism or tissue considered. 210 Po/ 210 Pb ratios in marine species are generally greater than unity and tend to increase up the food chain indicating that 210 Po is preferentially taken up by organisms compared to its progenitor 210 Pb. The effective transfer of 210 Po up the food chain is primarily due to the high degree of assimilation of the radionuclide from ingested food and its subsequent strong retention in the organisms. In some cases this mechanism may lead to an apparent biomagnification of 210 Po at the higher trophic level. Various pelagic species release 210 Po and 210 Pb packaged in organic biodetrital particles that sink and remove these radionuclides from the upper water column, a biogeochemical process which, coupled with scavenging rates of this radionuclide pair, is being examined as a possible proxy for estimating downward organic carbon fluxes in the sea. Data related to preferential bioaccumulation in various organisms, their tissues, resultant radiation doses to these species, and the processes by which 210 Po is transferred and recycled through the food web are discussed. In addition, the main gaps in our present knowledge and proposed areas for future studies on the biogeochemical behaviour of 210 Po and its use as a tracer of oceanographic

Environmental radioactivity of radon daughter's radionuclides 210Pb-210Bi-210Po

International Nuclear Information System (INIS)

Momoshima, N.

2003-01-01

Radionuclide, 210 Pb(22.3 y)- 210 Bi(5.013 d)- 210 Po(138.4 d) belongs to the uranium decay chain and widely distributed in the environment. 222 Rn escaped from the earth surface is a major source of atmospheric 210 Pb. These nuclides attach with atmospheric aerosols and are removed to the ground as wet and dry depositions. The residence time of the atmospheric aerosol, thus, was obtained by activity ratios of 210 Bi/ 210 Pb and 210 Po/ 210 Pb, showing different values. The discrepancy on the residence times are explained with inputs of 210 Po to the atmosphere other than 222 Rn emanated from the earth surface. The removal of aerosol as wet deposition occupies a significant fraction, which reaches 72% on 210 Pb and 89% on 7 Be. In the ocean, the radionuclides are used as tracer to examine dynamic processes occurring in the ocean, such as removal of particulate matter from seawater column to bottom. The 210 Pb and 210 Po concentrations in the ocean water collected off continent decreased from surface toward bottom, and the shortage on 210 Po content relative to that of 210 Po was observed at shallow ocean layers, however, the 210 Po/ 210 Pb activity ratio closed to the radioactive equilibrium at deeper layers. The 210 Pb is a very good tracer to evaluate an accumulation rate of bottom sediment in ocean, lake and river. This is called as 210 Pb dating and is successfully applicable to accumulation circumstances that bottom sediment deposits at constant rate. Most of the actual cases, simultaneous 137 Cs dating is carried out, which uses 137 Cs peak in the core as originated from radioactive fallout of nuclear tests, showing the maximum in 1963. Recently new findings on source of atmospheric 210 Po are report by laboratory experiments and environmental measurements, which proves biologically supported emission of volatile Po compounds to the atmosphere. (author)

Climatology of atmospheric PM10 concentration in the Po Valley

Science.gov (United States)

Bigi, A.; Ghermandi, G.

2014-01-01

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

Competitive Intelligence: Significance in Higher Education

Science.gov (United States)

Barrett, Susan E.

2010-01-01

Historically noncompetitive, the higher education sector is now having to adjust dramatically to new and increasing demands on numerous levels. To remain successfully operational within the higher educational market universities today must consider all relevant forces which can impact present and future planning. Those institutions that were…

CdZnTe background measurements at balloon altitudes with PoRTIA

International Nuclear Information System (INIS)

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

2004-01-01

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

Luminescent properties of Pr3+-sensitized LaPO4:Gd3+ ultraviolet-B phosphor under vacuum-ultraviolet light excitation

International Nuclear Information System (INIS)

Okamoto, Shinji; Uchino, Rika; Kobayashi, Keisuke; Yamamoto, Hajime

2009-01-01

Luminescent properties of Pr 3+ -sensitized LaPO 4 :Gd 3+ under vacuum-ultraviolet (vuv) light excitation have been investigated. The energy transfer probably occurs from the 5d levels in Pr 3+ ions to Gd 3+ ions under 172 nm light excitation. LaPO 4 :Gd 3+ ,Pr 3+ shows efficient ultraviolet-B (uv-B) emission at 312 nm, whose peak intensity reaches its maximum at Gd=35 mol % and Pr=5 mol %. (La 0.65 Gd 0.35 ) 0.95 Pr 0.05 PO 4 is about 1.6 times higher than a typical uv-B phosphor for vuv lamp, Y 0.75 Gd 0.25 Al 3 (BO 3 ) 4 , in Gd 3+ -emission intensity under 172 nm light excitation. This result implies that the Pr 3+ -sensitized LaPO 4 :Gd 3+ is a candidate of uv-B phosphors for xenon-excimer discharge vuv lamps. In order to evaluate the effect of the narrow-band uv-B emission by LaPO 4 :Gd 3+ ,Pr 3+ phosphor, irradiation test on DNA was performed. The irradiation damage of pUC 18 DNA by the narrow-band uv-B light from the LaPO 4 :Gd 3+ ,Pr 3+ phosphor is in the same magnitude as that by uv-A light from a filtered Hg lamp, even though the uv-B lamp is higher than the uv-A lamp in power density and photon energy.

{sup 210}Po in marine organisms consumed by the population of Seville; {sup 210}PO en organismos marinos consumidos por la poblacion sevillana

Energy Technology Data Exchange (ETDEWEB)

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

2011-07-01

The natural radionuclide {sup 210}Po is one belonging to the series of uranium, which is ubiquitously present in trace quantities in the various environmental compartments (water, soil, air) and through its route along the food chain may end incorporated into the human body via food or water intake. This radionuclide is highly radio toxic, presenting the highest value for the ingestion dose coefficient for adults. The Spanish population is an important component of their diet to marine products. found higher values of ingestion dose in the Spanish population compared to other European populations where the culture of introducing fish into your diet is not so entered. The study detailed here estimates the contribution of {sup 2}10Po to the ingestion dose received by the Sevillian population due to consumption of fish, mollusks and crustaceans. The results obtained in this study will be presented and discussed in this paper. (Author)

Emulsion drying synthesis of olivine LiFePO4/C composite and its electrochemical properties as lithium intercalation material

International Nuclear Information System (INIS)

Myung, Seung-Taek; Komaba, Shinichi; Hirosaki, Norimitsu; Yashiro, Hitoshi; Kumagai, Naoaki

2004-01-01

The electroactive LiFePO 4 /C nano-composite has been synthesized by an emulsion drying method. During burning-out the oily emulsion precipitates in an air-limited atmosphere at 300 deg. C, amorphous or low crystalline carbon was generated along with releasing carbon oxide gases, and trivalent iron as a cheap starting material was immediately reduced to the divalent one at this stage as confirmed by X-ray photoelectron spectroscopy, leading to a low crystalline LiFePO 4 /C composite. Heat-treatment of the low crystalline LiFePO 4 /C in an Ar atmosphere resulted in a well-ordered olivine structure, as refined by Rietveld refinement of the X-ray diffraction pattern. From secondary electron microscopic and scanning transmission electron microscopic observations with the corresponding elemental mapping images of iron and phosphorous, it was found that the LiFePO 4 powders are modified by fine carbon. The in situ formation of the nano-sized carbon during crystallization of LiFePO 4 brought about two advantages: (i) an optimized particle size of LiFePO 4 , and (ii) a uniform distribution of fine carbon in the product. These effects of the fine carbon on LiFePO 4 /C composite led to high capacity retention upon cycling at 25 and 50 deg. C and high rate capability, resulting from a great enhancement of electric conductivity as high as 10 -4 S cm -1 . That is, the obtained capacity was higher than 90 mAh (g-phosphate) -1 by applying a higher current density of about 1000 mA g -1 (11 C) at 50 deg. C

Radioactive {sup 210}Po in magnesium supplements

Energy Technology Data Exchange (ETDEWEB)

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

2016-08-01

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

Deuteron momentum distribution in KD2PO4

International Nuclear Information System (INIS)

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

2008-01-01

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

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

OpenAIRE

-, Khairil; Koesoemanegara, Eddy

2011-01-01

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

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

International Nuclear Information System (INIS)

Hoeppe, Henning A.; Daub, Michi

2012-01-01

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

The Aalborg University PO-PBL Model from a Socio-cultural Learning Perspective

DEFF Research Database (Denmark)

Hernández, Carola Hernández; Ravn, Ole; Valero, Paola

2015-01-01

Since the 1970’s, Aalborg University has been developing a new pedagogical model in higher education: The Project Oriented – Problem Based Learning (PO-PBL). In particular, the Faculty of Engineering and Science has developed a pedagogical proposal that introduces students to a different type...

Discharge of 210Po and 210Pb in coastal groundwater to the ocean

International Nuclear Information System (INIS)

Kim, Intae; Kim, Tae-hoon; Kim, Guebuem

2013-01-01

The activities of 210 Po and 210 Pb were measured for the truly dissolved (<10 kDa) and colloidal (10 kDa - 0.45 ìm) phases in coastal ground water in 2010 and 2011. The sampling sites include the coast of a large tidal flat (Hampyeong Bay) and a volcanic island, Jeju, Korea, where submarine groundwater discharge (SGD) were reported to be higher than typical continental margins. The total dissolved fraction was separated into the colloidal and truly dissolved fractions using a tangential flow filtration (TFF) system (PLCGC Pellicon). The total 210 Po and 210 Pb activities in ground water were 1.0 - 18.2 dpm/100L (9.7±7.6 dpm/100L) an 2.9 - 29.1 dpm/100L (16.8±10.7 dpm/100L) in the Hampyeong Bay and Jeju Island samples, respectively. The total 210 Po and 210 Pb activities in groundwater were similar to or even slightly lower than those in the typical seawater. These lower activities seem to be due to the rapid adsorption of Po and Pb on to particles in the subterranean estuary. The proportions of the truly dissolved and colloidal phases were, respectively, 73±5% and 27±5% for 210 Po, and 60±5% and 40±5% for 210 Pb. This result is consistent with the earlier study that more than half of the some dissolved trace metals in coastal ground water are in the colloidal form. Thus, our result implies that the colloidal forms are important in controlling the behaviour of Po, Pb, and other trace metals in the subterranean estuary and SGD-associated fluxes to the ocean. (author)

Sol–gel synthesis and electrochemical properties of 9LiFePO4·Li3V2(PO4)3/C composite cathode material for lithium ion batteries

International Nuclear Information System (INIS)

Zhong Shengkui; Wu Ling; Liu Jiequn

2012-01-01

Highlights: ► Nano-sized 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C powders are prepared by a sol–gel method. ► Mutual doping in 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C can improve its electronic conductivity. ► The addition of Li 3 V 2 (PO 4 ) 3 can improve the ionic diffusivity of LiFePO 4 . ► LiFePO 4 , Li 3 V 2 (PO 4 ) 3 and LiFePO 4 –Li 3 V 2 (PO 4 ) 3 unit cells coexist in the composite. - Abstract: 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C composite cathode material is prepared by a sol–gel method, using ferric citrate, V 2 O 5 , Li 2 CO 3 , NH 4 H 2 PO 4 and citric acid as raw materials. The composite material is composed of the olivine LiFePO 4 and monoclinic Li 3 V 2 (PO 4 ) 3 phases. XRD results indicate that most of the iron and vanadium in the raw materials tend to form the LiFePO 4 and Li 3 V 2 (PO 4 ) 3 phases, and only small amounts of Fe and V as the dopants enter into the lattice of Li 3 V 2 (PO 4 ) 3 and LiFePO 4 , respectively. The electronic conductivity and Li + diffusion coefficient of 9LiFePO 4 ·Li 3 V 2 (PO 4 ) 3 /C are 6.615 × 10 −3 S cm −1 and ∼10 −10 cm 2 s −1 , which are three orders of magnitude and one order of magnitude larger than those of the LiFePO 4 /C, respectively. The composite material shows a first discharge specific capacity of 131.3 mAh g −1 and capacity retention of 95.1% after 200 cycles at 10 C rate. Compared with the LiFePO 4 /C, its rate capability and cycle performance are both remarkably improved.

Forenzika elektronske pošte

Directory of Open Access Journals (Sweden)

Milorad S. Markagić

2013-10-01

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

Ultrasound guided pO2 measurement of breast cancer reoxygenation after neoadjuvant chemotherapy and hyperthermia treatment.

Science.gov (United States)

Vujaskovic, Z; Rosen, E L; Blackwell, K L; Jones, E L; Brizel, D M; Prosnitz, L R; Samulski, T V; Dewhirst, M W

2003-01-01

The objective of this study was to determine whether neoadjuvant chemotherapy in combination with hyperthermia (HT) would improve oxygenation in locally advanced breast tumours. The study describes a new optimized ultrasound guided technique of pO2 measurement using Eppendorf polarographic oxygen probes in 18 stage IIB-III breast cancer patients. Prior to treatment, tumour hypoxia (median pO2pO2=3.2 mmHg). Seven patients had well oxygenated tumours (median pO2 of 48.3 mmHg). Eight patients with hypoxic tumours prior to treatment had a significant improvement (p=0.0008) in tumour pO2 after treatment (pO2 increased to 19.2 mmHg). In three patients, tumours remained hypoxic (average median pO2=4.5 mmHg). The advantages of the ultrasound guided pO2 probe are in the accuracy of the Eppendorf electrode placement in tumour tissue, the ability to monitor electrode movement through the tumour tissue during the measurement and the ability to avoid electrode placement near or in large blood vessels by using colour Doppler imaging. The results of this preliminary study suggest that the combination of neoadjuvant chemotherapy and hyperthermia improves oxygenation in locally advanced breast tumours that are initially hypoxic.

Mesoporous LiMnPO4/C nanoparticles as high performance cathode material for lithium ion batteries

International Nuclear Information System (INIS)

Wen, Fang; Shu, Hongbo; Zhang, Yuanyuan; Wan, Jiajia; Huang, Weihua; Yang, Xiukang; Yu, Ruizhi; Liu, Li; Wang, Xianyou

2016-01-01

LiMnPO 4 has been considered as one of the most promising high voltage cathode materials for next-generation lithium ion batteries. However, LiMnPO 4 suffers from intrinsic drawbacks of extremely low electronic conductivity and ionic diffusivity between LiMnPO 4 /MnPO 4 . In this paper, mesoporous LiMnPO 4 nanoparticles are synthesized successfully via a facile glycine-assisted solvothermal rout. The as-prepared mesoporous LiMnPO 4 /C nanoparticles present well-defined abundant mesoporous structure (diameter of 3 ∼ 10 nm), uniform carbon layer (thickness of 3 ∼ 4 nm), high specific surface area (90.1 m 2 /g). As a result, the mesoporous LiMnPO 4 /C nanoparticles achieve excellent electrochemical performance as cathode materials for lithium ion batteries. It demonstrates a high discharge capacity of 167.7, 161.6, 156.4, 148.4 and 128.7 mAh/g at 0.1, 0.5, 1, 2 and 5C, and maintains a discharge capacity of 130.0 mAh/g after 100 cycles at 1C. The good electrochemical performance is attributed to its special interpenetrating mesoporous structure in LiMnPO 4 nanoparticles, which significantly enhances the ionic and electronic transport and additional capacitive behavior to compensate the sluggish kinetics.

Ingestion dose from 210Po due to the consumption of packaged drinking water

International Nuclear Information System (INIS)

Nair, Madhu G.; Rao, D.D.; Sreejith, Sathyapriya R.; Sarka, P.K.

2013-01-01

Humans are chronically exposed to naturally occurring radionuclides from uranium and thorium series via inhalation and ingestion. With increased interest in radiological assessment a study was taken up for assessing natural radioactivity in drinking water. Drinking water is an important route of intake of naturally occurring 210 Po. 210 Po being a very important radionuclide from Uranium series with high specific activity causes significant internal dose. In our study 210 Po in PDW was concentrated with calcium phosphate and spontaneously deposited onto silver planchette and subsequently measured by alpha spectrometry. The concentration of 210 Po in the bottled water ranged from 0.11 mBq.l -1 to 2.9 mBq.l -1 . The highest concentration was observed in that sample that was reportedly sourced from mountain regions. Based on the concentration of 210 Po in each water sample, the annual intake rate (1.68L/d), and the Dose Coefficient (1.2 X 10 -6 Vs./Bq) recommended by the International Commission on Radiological Protection (ICRP, 1996), the annual committed effective doses to the adult population was estimated. The annual effective doses ranged between 0.10-2.16 μSv/yr. (author)

Quantitative determination of 210Po in geochemical samples

International Nuclear Information System (INIS)

Dyck, W.; Bristow, Q.

1984-01-01

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

High 210Po atmospheric deposition flux in the subtropical coastal area of Japan

International Nuclear Information System (INIS)

Tateda, Yutaka; Iwao, Kenji

2008-01-01

Bulk atmospheric deposition fluxes of 210 Po and 210 Pb were measured at three coastal regions of Japan, the Pacific Ocean coastal area of the Japanese mainland (Odawa Bay), the Chinese continental side of Japanese coastal area (Tsuyazaki), and an isolated island near Okinawa (Akajima). Wet and dry fallout collectors were continuously deployed from September 1997 through August 1998 for periods of 3 to 31 days depending on the frequency of precipitation events. Annual 210 Pb deposition fluxes at Odawa Bay (35 o N 139 o E), Tsuyazaki (33 o N 130 o E) and Akajima (26 o N 127 o E) were 73.3 ± 8.0, 197 ± 35 and 78.5 ± 8.0 Bq m -2 y -1 , respectively. Higher 210 Pb deposition was observed at the Chinese continental side of Japanese coast than at the Pacific Ocean coastal site. The high 210 Pb atmospheric flux at the Chinese continental side coast was thought to be attributable to 222 Rn-rich air-mass transport from the Chinese continent during the winter monsoon. In contrast, the annual 210 Po deposition fluxes at the three study sites were 13.0 ± 2.3 (Odawa Bay), 21.9 ± 4.4 (Tsuyazaki) and 58.4 ± 7.7 (Akajima) Bq m -2 y -1 , respectively, indicating unusual high 210 Po deposition at Akajima during winter. Anomalous unsupported 210 Po input was observed during summer 1997, suggesting unknown source of 210 Po at this area

Urea-assisted synthesis of AlPO4:Ce,Tb nanorods as a redox luminescence switch

International Nuclear Information System (INIS)

Yang, Wei; Hu, Juncheng

2013-01-01

AlPO 4 :Ce,Tb nanorods were synthesized by a facile hydrothermal method. The morphology of rod-like AlPO 4 was tuned by varying urea concentrations, AlPO 4 gradually changed from nanosheets to nanorods, and urea provided hydroxyl anion (OH − ) in the aqueous solution to prepare the dispersed nanorods under the hydrothermal conditions. The emission intensity of nanorods increased significantly compared to that of nanosheets. AlPO 4 :Ce,Tb nanorods provided a novel redox luminescence switch on the basis of the reversible switching of the Ce 3+ /Ce 4+ redox couple. The luminescence is quenched (off) when the system is in the oxidized form while it is restored (on) in the reduced form. The mechanism of the energy transfer and electronic transition between Ce 3+ and Tb 3+ in the AlPO 4 nanorods was also discussed. This switch has biocompatibility and low toxicity, and may have a potential application in biomedical diagnostics and analysis

Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures

Science.gov (United States)

Liu, Ruoyu; Hu, Peiguang; Chen, Shaowei

2012-10-01

Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.

210Po/210Pb dynamics in relation to zooplankton biomass and trophic conditions during an annual cycle in northwestern Mediterranean coastal waters

International Nuclear Information System (INIS)

Färber Lorda, Jaime; Fowler, Scott W.; Miquel, Juan-Carlos; Rodriguez y Baena, Alessia; Jeffree, Ross A.

2013-01-01

Monthly sampling in northwestern Mediterranean coastal waters was undertaken to better understand the relationship between zooplankton biomass and the cycling of the natural radionuclide 210 Po/ 210 Pb pair during a one-year period (October 1995–November 1996). In conjunction with mesozooplankton collections and 210 Po/ 210 Pb measurements in seawater, zooplankton and their fecal pellets, the biochemical composition of particulate organic matter (POM) was also examined at three depths (0, 20 and 50 m) as an indicator of trophic conditions. During May 1996, a strong zooplankton “bloom” was observed which was preceded by a prolonged increase in POM (protein + carbohydrates + lipids) starting at the end of March, and further demonstrated by a concomitant increase in the concentration of smaller particles, two features that are typical of mesotrophic waters. Simultaneous measurements of 210 Po in sea water and zooplankton showed an inverse trend between these two parameters during the sampling period, with the two lowest 210 Po concentrations in the dissolved phase of seawater coincident with the highest radionuclide concentrations in the zooplankton; however, this apparent relationship was not statistically significant over the entire year. Freshly excreted mesozooplankton and salp fecal pellets, which have been strongly implicated in the removal and downward transport of these radionuclides from the upper water column, contained 210 Po and 210 Pb levels ranging from 175 to 878 and 7.5–486 Bq kg −1 dry weight, respectively. Salp pellets contained 5 and 10 times more 210 Po and 210 Pb than in fecal pellets produced by mixed zooplankton, a finding most likely related to their different feeding strategies. During the zooplankton biomass peak observed in May, the 210 Po concentration in zooplankton was at a minimum; however, in contrast to what has been reported to occur in some open sea oligotrophic waters, over the year no statistically significant inverse

Li3V2(PO4)3/LiFePO4 composite hollow microspheres for wide voltage lithium ion batteries

International Nuclear Information System (INIS)

He, Wen; Wei, Chuanliang; Zhang, Xudong; Wang, Yaoyao; Liu, Qinze; Shen, Jianxing; Wang, Lianzhou; Yue, Yuanzheng

2016-01-01

Highlights: • Using yeast cells to control the in-situ growth of crystal particle. • Heterogeneous isomorphism nanocomposite hollow microspheres are synthesized. • The cathode exhibits a higher discharge capacity and energy density. - Abstract: Li 3 V 2 (PO 4 ) 3 (LVP)/LiFePO 4 (LVP) composite hollow microspheres (LVP/LFP-CHMs) for lithium-ion batteries have been synthesized by a combination method, using yeast cells as both structure templates and biocarbon source. The stable heterogeneous isomorphism solid solution with superlattice structure is formed in the joint of LVP and LFP particles. A detailed analysis of the formation mechanism of solid solution with superlattice structure and the influences of different Fe:V mole ratios on the structure and electrochemical properties of composites are presented. When the LVP/LFP-CHMs with a Fe:V mole ratio of 1:3 were used as cathode material in coin cells with metallic Li as anode, the cell exhibits a discharge capacity of 221.5 mAh g −1 for 5 cycles and discharge specific energy of 682 Wh kg −1 at 0.1C in a wide voltage range (1.5–4.3 V). Its capacity is far higher than the capacity of unsubstituted LFP and LVP in the same wide voltage range. The energy density of this cell is about 4 times higher than that of modern commercial lithium-ion batteries (157 Wh kg −1 ). The wide voltage range not only increases the discharge capacity and energy density of cathode materials, but also could expand the range of its applications in electronic equipment.

Bioaccumulation of polonium ({sup 210}Po) and uranium ({sup 234}U, {sup 238}U) in plants around phosphogypsum waste heap in Wislinka (northern Poland)

Energy Technology Data Exchange (ETDEWEB)

Borylo, A.; Skwarzec, B. [Gdansk Univ. (Poland). Faculty of Chemistry

2011-07-01

In the study the activities of polonium {sup 210}Po and uranium {sup 234}U, {sup 238}U in plants, collected near phosphogypsum waste heap in Wis'linka (northern Poland), were determined by using the alpha spectrometry. The obtained results revealed that the concentrations of {sup 210}Po, {sup 234}U, and {sup 238}U in the analyzed plants were differentiated. In the analyzed flora organisms the highest amounts of polonium and uranium were found in ruderal plant samples as well as willow samples (Salix viminalis) from protection zone of phosphogypsum waste heap. The concentrations of {sup 210}Po, {sup 234}U and {sup 238}U in the analyzed plants were higher in roots than in green parts of plants. The higher concentrations of {sup 210}Po and {sup 238}U radionuclides were estimated for hydrophyte (common sedge Carex nigra Reichard), the favourite habitat of which is particularly wet meadow and for plants collected in the vicinity of phosphogypsum waste heap. The major source of polonium and uranium in analyzed plants is root system. The values of {sup 234}U/ {sup 238}U activity ratio in all analyzed plants are closed to one, what indicated that source of uranium in analyzed plants is phosphogypsum. The highest uranium and polonium concentrations were characterized for plants, which are covered with tomentose. The comparability polonium and uranium contents were confirmed in edible plants, but higher accumulation was determined in ripe species than immature species of vegetables. The higher polonium and uranium concentrations were noticed in green parts of plant, the lower in roots. Polonium concentration in cultivated plants samples was not species diverse. Therefore, the significant source of polonium and uranium in analyzed plants is wet and dry atmospheric falls gathering the soil and air dust from phosphogypsum waste dump. The maximum {sup 210}Po and {sup 238}U radionuclides concentrations were found in green parts of red beet (Beta vulgaris esculenta), the

Levels of 210Po and 210Pb in cigars

International Nuclear Information System (INIS)

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

2002-01-01

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

Transfer analysis of 210Po and 210Pb in the terrestrial environment

International Nuclear Information System (INIS)

Persson, B.R.R.

2013-01-01

The transfer of 210 Po and 210 Pb between various compartments in the terrestrial environment has been analysed by using published data. The average activity concentration of 210 Po in dry soil is 61 ± 14 Bq.kg -1 (median 44 Bq.kg -1 ). Ground water concentrations of 210 Po in drilled wells might be as high as 6.5 Bq/l. But in regular drinking water it is just about 3-5 mBq/l. The uptake of radionuclides from soil to plant is usually given as the ratio of dry matter radionuclide-activity concentrations of plant (AC plant ) and soil (AC soil ) respectively. This ratio is called the soil transfer factor: STF = AC plant /AC soil . The soil transfer factor varies widely between various types of crops with an average of about 0.056±0.003. The activity concentrations in leafy plants are, however highly affected by the atmospheric deposition of 210 Pb and 210 Po. By comparing the activity concentrations in plants grown on an open field with those grown on a field sheltered by a polyethylene tent, it has been possible to estimate a deposition transfer factor: DTF = Difference of the dry matter activity concentration (Bq.kg -1 ) of plant grown in open field and plants grown in tent shelter, divided by the atmospheric deposition during the vegetation period (Bq.m -2 ). The deposition transfer factor for 210 Pb thus estimated is in the order of 0.5-1.0 (m 2 .kg -1 dry matter) for leafy plants like grass and 0.1-0.5 for less leafy plant and straw. For various grains it is < 0.2 and for root fruits it is < 0.003 (m 2 .kg -1 dry matter). Corresponding values for 210 Po are about a factor 3 times higher. The world average activity concentration of 210 Po in fresh leafy vegetable is estimated to 320±190 mBq.kg -1 , and in cereals and grain products 240±80 mBq.kg -1 . The average activity concentration in milk products is 59 ± 13 mBq.kg -1 and in meat products about 70 ± 39 mBq.kg -1 . The dietary intake of milk and meat products is 170 kg.a - which is the highest of all food

Synthesis and characterization of highly efficient and stable Pr6O11/Ag3PO4/Pt ternary hybrid structure

International Nuclear Information System (INIS)

Deng, Jiatao; Liu, Lin; Niu, Tongjun; Sun, Xiaosong

2017-01-01

Highlights: • Visible-light-driven Pr 6 O 11 /Ag 3 PO 4 /Pt photocatalysts were prepared. • Pr 6 O 11 /Ag 3 PO 4 /Pt showed highly efficient and stable photocatalystic activity. • The photocatalytic mechanism of Pr 6 O 11 /Ag 3 PO 4 /Pt composite was given. - Abstract: Ag 3 PO 4 is an excellent photocatalyst with high efficiency and quantum yield, but suffers from the fast recombination of photogenerated electron-hole pairs and photo-corrosion. Hereby, the highly efficient and stable visible-light-driven Pr 6 O 11 /Ag 3 PO 4 /Pt photocatalyst were prepared via a three-step wet chemical approach. The as-prepared Pr 6 O 11 /Ag 3 PO 4 /Pt composite was characterized by X-ray diffraction, US-vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra and transient photocurrent as well. Comparing with single Pr 6 O 11 or Ag 3 PO 4 , the prepared Pr 6 O 11 /Ag 3 PO 4 /Pt composite exhibited much higher photocatalytic activity and stability for the degradation of Rhodamine B under visible light irradiation (>420 nm). The enhanced photocatalytic performance of Pr 6 O 11 /Ag 3 PO 4 /Pt composite has been attributed to the efficient separation of photo-generated electron-hole pairs through a scheme system composed of Pr 6 O 11, Ag 3 PO 4 and Pt.

Uptake and kinetics of 226Ra, 210Pb and 210Po in big sage brush

International Nuclear Information System (INIS)

Simon, S.L.

1985-01-01

Root uptake of 226 Pb and 210 Po by mature sage brush was studied using a soil injection method for spiking the soil with minimal root disturbance. The main objective was to measure vegetation concentrations and determine concentration ratios (CR's) due to root uptake as a function of time in mature big sage brush. Concentration ratios obtained in mature vegetation and in steady-state situations may be valuable in assessing the impact of uranium mining and milling. The vegetation was sampled approximately every 3 mo for A 2 y period. Significant levels of activity were detected in the vegetation beginning at the first sampling (81 d after soil injection for 226 Ra, 28 d for 210 Pb and 210 Po). There was an exponential decrease in concentration to an apparent steady state value. Mean values (geometric) of the data pooled over the second year period indicated that steady-state Cr's for 226 Ra, 210 Pb and 210 Po, as determined in mature sage brush, were 0.04, 0.009, and 0.08, respectively. Investigations were also carried out to verify the suitability of soil injection for uptake studies and to evaluate the time dependence of 226 Ra leaching from sage brush leaves. The soil injection method was determined to produce, on the average, uptake equivalent to that produce by a uniform soil distribution, however, the variety of uptake for plants growing in injected soil was higher than for plants growing in uniformly contaminated soil. A three compartment mathematical model was formulated to help understand mechanisms of plant uptake and to predict, if possible, the concentration of 226 Ra, 210 Po in vegetation as a function of time after soil spiking

.i.Asteriacites./i. and other trace fossils from the Po Formation (Visean–Serpukhovian), Ganmachidam Hill, Spiti Valley (Himalaya) and its paleoenvironmental significance

Czech Academy of Sciences Publication Activity Database

Singh, B. P.; Bhargava, O. N.; Mikuláš, Radek; Prasad, S. K.; Singla, G.; Kaur, R.

2017-01-01

Roč. 68, č. 5 (2017), s. 464-478 ISSN 1335-0552 Institutional support: RVO:67985831 Keywords : Po Formation * Visean–Serpukhovian * Spiti * trace fossils * Cruziana ichnofacies Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Paleontology Impact factor: 1.358, year: 2016

Tailored surface structure of LiFePO4/C nanofibers by phosphidation and their electrochemical superiority for lithium rechargeable batteries.

Science.gov (United States)

Lee, Yoon Cheol; Han, Dong-Wook; Park, Mihui; Jo, Mi Ru; Kang, Seung Ho; Lee, Ju Kyung; Kang, Yong-Mook

2014-06-25

We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO4/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO4/C nanofibers composed of 1-dimensional (1D) LiFePO4 nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO4 nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO4/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO4 nanofibers. As a result, the phosphidated LiFePO4/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO4/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials.

Equilibrium diagram of KPO3-Y(PO3)3 system, chemical preparation and characterization of KY(PO3)4

International Nuclear Information System (INIS)

Jouini, Anis; Ferid, Mokhtar; Trabelsi-Ayadi, Malika

2003-01-01

Microdifferential thermal analysis (μ-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO 3 -Y(PO 3 ) 3 system. The only compound observed within the system was KY(PO 3 ) 4 melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO 3 ) 3 at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO 3 was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO 3 ) 4 polyphosphate has the P2 1 space group with lattice parameters: a=7.183(4) A, b=8.351(6) A, c=7.983(3) A, β=91.75(3) deg. and Z=2 is isostructural with KNd(PO 3 ) 4 . The second allotropic form of KY(PO 3 ) 4 belongs to the P2 1 /n space group with lattice parameters: a=10.835(3) A, b=9.003(2) A, c=10.314(1) A, β=106.09(7) deg. and Z=4 and is isostructural with TlNd(PO 3 ) 4 . The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP 4 O 12 crystallizes in the C2/c space group with lattice parameters: a=7.825(3) A, b=12.537(4) A, c=10.584(2) A, β=110.22(7) deg. and Z=4 is isostructural with RbNdP 4 O 12 and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported

Assessment of 210Po exposure for the Italian population

International Nuclear Information System (INIS)

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

1980-01-01

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

Crystal structure of CsTb(PO3)4 compound

International Nuclear Information System (INIS)

Palkina, K.K.; Maksimova, S.I.; Kuznetsov, V.G.; Chibiskova, N.T.

1978-01-01

The X-ray structural study of compounds of the CsLn(PO 3 ) 4 series has been made. Found is the presence of two structural types for CsPr(PO 3 ) 4 (cubic and monoclinic modifications), one type for CsNd(PO 3 ) 4 (cubic modification) and for CsTb(PO 3 ) 4 (monoclinic modification). For the CsTb(PO 3 ) 4 monocrystal the lattice parameters are determined: a=7.032 +- 0.001; b=8.705 +- 0.001; c=9.051 +- 0.001 A; α=90 deg, β=90 deg, γ=100 deg, Z=2, V=545.68 A 3 , dsub(exp)=3.70 g/cm 3 . The structure character is presented as infinite chains of (PO 4 ) tetrahedrons, stretched along the ''C'' period. Tb and Cs atoms are rounded by 8 atoms of oxygen. Tb polyhedron are irregular octaapexes or strongly deformed tetragonal antiprisms. Tb-Tb shortest distance is 6.59 A

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

Directory of Open Access Journals (Sweden)

Kazuya Tokuda

2014-07-01

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

226Ra, 210Pb and 210Po disequilibria in the western North Pacific

International Nuclear Information System (INIS)

Nozaki, Y.; Isunogai, S.

1976-01-01

226 Ra, 210 Pb and 210 Po were measured in oceanic profiles at two stations near the Bonin and Kurile trenches. 210 Po is depleted by 50% on average relative to 210 Pb in the surface water. In the deep water, 210 Pb is about 25% deficient relative to 226 Ra. Based on the deficiency, 210 Pb residence time with respect to removal by particulate matter was estimated to be less than 96 years in the deep water. 210 Pb deficiency in the bottom water was significantly greater than that of the adjacent deep water, indicating more effective removal near or at the bottom interface. 210 Pb, 210 Po and Th appear to have similar overall rate constants of particulate removal throughout the water column. (Auth.)

Synthesis and luminescence of CePO4 and CePO4:Tb hollow and core-shell microspheres composed of single-crystal nanorods

International Nuclear Information System (INIS)

Guan Mingyun; Sun Jianhua; Han Min; Xu Zheng; Tao Feifei; Yin Gui; Wei Xianwen; Zhu Jianmin; Jiang Xiqun

2007-01-01

Lanthanide phosphate microspheres composed of single-crystal CePO 4 and CePO 4 :Tb nanorods were successfully synthesized, respectively, using the functionalized composite aggregate as a template, which is composed of P123, H 6 P 4 O 13 and Ce 3+ , and also as a resource of reaction species with high chemical potential. The shape and the phase structure of the CePO 4 nanocrystal can be easily controlled via adjusting reaction temperature, monomer concentration and annealing temperature. SEM images show the spherical superstructure composed of nanorods. HRTEM and SAED images reveal the single-crystalline nature of nanorod and TEM images show the hollow interiors of the superstructure. XRD patterns indicate that the crystal structure of the nanorods is hexagonal before and monoclinic after annealing. The formation mechanism was proposed. Strong UV and green luminescence were observed for the CePO 4 and CePO 4 :Tb microspheres, respectively. The synthesis method can be extended to the fabrication of NRHS and core-shell microspheres of other rare-earth or doped LnPO 4 materials for wide applications

Biogeochemical factors affecting the presence of 210Po in groundwater

International Nuclear Information System (INIS)

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

2011-01-01

Research highlights: → 210 Po activities in numerous domestic wells in Fallon NV exceed 500 mBq/L. → 210 Po levels in sediment are not the primary determinant on levels in groundwater. → δ 34 S measurements indicate SO 4 reduction occurred in all 210 Po contaminated wells. → 210 Po contaminated wells are anoxic, have high pH and low Ca. → Po mobilization probably involves an anaerobic S cycle in which H 2 S dissolves MnO 2 . - Abstract: The discovery of natural 210 Po enrichment at levels exceeding 500 mBq/L in numerous domestic wells in northern Nevada, USA, led to a geochemical investigation of the processes responsible for its mobilization. 210 Po activities in 63 domestic and public-supply wells ranged from below 1 mBq/L to 6590 ± 590 mBq/L, among the highest reported levels in the USA. There is little spatial or depth variability in 210 Pb activity in study-area sediments and mobilization of a few percent of the 210 Po in the sediments would account for all of the 210 Po in water. Stable-isotope measurements indicate SO 4 reduction has occurred in all 210 Po contaminated wells. Sulfide species are not accumulating in the groundwater in much of Lahontan Valley, probably because of S cycling involving microbial SO 4 reduction, abiotic oxidation of H 2 S to S 0 by Mn(IV), followed by microbial disproportionation of S 0 to H 2 S and SO 4 . The high pH, Ca depletion, MnCO 3 saturation, and presence of S 0 in Lahontan Valley groundwater may be consequences of the anaerobic S cycling. Consistent with data from naturally-enriched wells in Florida, 210 Po activities begin to decrease when aqueous sulfide species begin to accumulate. This may be due to formation and precipitation of PoS, however, Eh-pH diagrams suggest PoS would not be stable in study-area groundwater. An alternative explanation for the study area is that H 2 S accumulation begins when anaerobic S cycling stops because Mn oxides are depleted and their reduction is no longer releasing 210 Po

Determination of 210 Po in cigarettes

International Nuclear Information System (INIS)

Peres, Ana Claudia; Hiromoto, Goro

1999-01-01

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

Continuous arterial PO2 profiles in unrestrained, undisturbed aquatic turtles during routine behaviors

Science.gov (United States)

Hicks, James W.

2016-01-01

ABSTRACT Mammals and birds maintain high arterial partial pressure of oxygen (PO2) values in order to preserve near-complete hemoglobin (Hb) oxygen (O2) saturation. In diving mammals and birds, arterial O2 follows a primarily monotonic decline and then recovers quickly after dives. In laboratory studies of submerged freshwater turtles, arterial O2 depletion typically follows a similar pattern. However, in these studies, turtles were disturbed, frequently tethered to external equipment and confined either to small tanks or breathing holes. Aquatic turtles can alter cardiac shunting patterns, which will affect arterial PO2 values. Consequently, little is known about arterial O2 regulation and use in undisturbed turtles. We conducted the first study to continuously measure arterial PO2 using implanted microelectrodes and a backpack logger in undisturbed red-eared sliders during routine activities. Arterial PO2 profiles during submergences varied dramatically, with no consistent patterns. Arterial PO2 was also lower than previously reported during all activities, with values rarely above 50 mmHg (85% Hb saturation). There was no difference in mean PO2 between five different activities: submerged resting, swimming, basking, resting at the surface and when a person was present. These results suggest significant cardiac shunting occurs during routine activities as well as submergences. However, the lack of relationship between PO2 and any activity suggests that cardiac shunts are not regulated to maintain high arterial PO2 values. These data support the idea that cardiac shunting is the passive by-product of regulation of vascular resistances by the autonomic nervous system. PMID:27618860

A novel visible light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite: Preparation and application in the photo-degradation of pollutants

Energy Technology Data Exchange (ETDEWEB)

Chai, Yuanyuan; Wang, Li; Ren, Jia; Dai, Wei-Lin, E-mail: wldai@fudan.edu.cn

2015-01-01

Graphical abstract: - Highlights: • Highly efficient visible-light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. • Application in the photo-degradation of RhB. • Synthesis from a facile and simple colloidal method. • 20%-Ag{sub 3}PO{sub 4}/SBA-15 shows 8 times faster degradation rate than Ag{sub 3}PO{sub 4}. • Super stability and recycling ability. - Abstract: A novel visible light-driven environmental-benign Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite increases by 3 times compared with that of the Ag{sub 3}PO{sub 4} particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag{sub 3}PO{sub 4} nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag{sub 3}PO{sub 4} loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag{sub 3}PO{sub 4}/SBA-15. Compared to pure Ag{sub 3}PO{sub 4} nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag{sub 3}PO{sub 4}/SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and N{sub 2}-adsorption–desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag{sub 3}PO{sub 4} loading on the SBA-15 catalyst will not result in the extra environment and health

High-Capacity and Long-Cycle Life Aqueous Rechargeable Lithium-Ion Battery with the FePO4 Anode.

Science.gov (United States)

Wang, Yuesheng; Yang, Shi-Ze; You, Ya; Feng, Zimin; Zhu, Wen; Gariépy, Vincent; Xia, Jiexiang; Commarieu, Basile; Darwiche, Ali; Guerfi, Abdelbast; Zaghib, Karim

2018-02-28

Aqueous lithium-ion batteries are emerging as strong candidates for a great variety of energy storage applications because of their low cost, high-rate capability, and high safety. Exciting progress has been made in the search for anode materials with high capacity, low toxicity, and high conductivity; yet, most of the anode materials, because of their low equilibrium voltages, facilitate hydrogen evolution. Here, we show the application of olivine FePO 4 and amorphous FePO 4 ·2H 2 O as anode materials for aqueous lithium-ion batteries. Their capacities reached 163 and 82 mA h/g at a current rate of 0.2 C, respectively. The full cell with an amorphous FePO 4 ·2H 2 O anode maintained 92% capacity after 500 cycles at a current rate of 0.2 C. The acidic aqueous electrolyte in the full cells prevented cathodic oxygen evolution, while the higher equilibrium voltage of FePO 4 avoided hydrogen evolution as well, making them highly stable. A combination of in situ X-ray diffraction analyses and computational studies revealed that olivine FePO 4 still has the biphase reaction in the aqueous electrolyte and that the intercalation pathways in FePO 4 ·2H 2 O form a 2-D mesh. The low cost, high safety, and outstanding electrochemical performance make the full cells with olivine or amorphous hydrated FePO 4 anodes commercially viable configurations for aqueous lithium-ion batteries.

Organophosphonic acid as precursor to prepare LiFePO4/carbon nanocomposites for high-power lithium ion batteries

International Nuclear Information System (INIS)

Chen, Ming; Shao, Leng-Leng; Yang, Hua-Bin; Zhao, Qian-Yong; Yuan, Zhong-Yong

2015-01-01

Graphical abstract: LiFePO4/C nanocomposites were prepared by a quasi-sol–gel method with the use of organophosphonic acid, exhibiting improved electrochemical performance with excellent cycle stability. Display Omitted -- Highlights: •Amino tris(methylene phosphonic acid) is served as a novel precursor for LiFePO 4 /C. •Nano-sized and high-purity LiFePO 4 /C composites are obtained by a quasi-sol–gel route. •Core-shell structured LiFePO 4 /C nanocomposites are fabricated by further introducing sucrose. •Superior electrochemical performance is observed in the organophosphorus-synthesized LiFePO 4 /C. -- Abstract: Amino tris(methylene phosphonic acid) (ATMP) is selected as phosphorus and carbon co-source for the synthesis of uniformly nano-sized LiFePO 4 /C by a quasi-sol–gel method. This strategy using ATMP instead of conventional NH 4 H 2 PO 4 supplies two advantages: firstly, ATMP in situ chelates Li + onto its framework and subsequently binds with FeC 2 O 4 in aqueous solution, forming a molecule-scale homogeneous precursor which can obviously improve the purity of LiFePO 4 . Secondly, the organic carbon contained in ATMP can form uniformly distributed conductive carbon networks among LiFePO 4 particles after calcination, which improves the electrical conductivity. The resultant LiFePO 4 /C with 1.1 wt.% carbon achieves a higher discharge capacity than those of LiFePO 4 and LiFePO 4 /C prepared with inorganic NH 4 H 2 PO 4 . Moreover, core-shell structured LiFePO 4 /C nanocomposites are also fabricated by further introducing sucrose into the synthesis system. The high-quality carbon shell effectively hinders the LiFePO 4 particle growth and aggregation under high-temperature treatment, which further enhances the electrical conductivity and lithium-ion diffusion, resulting in the improved electrochemical performance with excellent cycle stability (the optimum discharge capacity of 158.6 mAh g −1 at 0.1 C and 138.4 mAh g −1 at 2 C). The high

Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

Science.gov (United States)

Zuo, Li; Pannell, Benjamin K; Re, Anthony T; Best, Thomas M; Wagner, Peter D

2015-12-01

Po2 cycling, often referred to as intermittent hypoxia, involves exposing tissues to brief cycles of low oxygen environments immediately followed by hyperoxic conditions. After experiencing long-term hypoxia, muscle can be damaged during the subsequent reintroduction of oxygen, which leads to muscle dysfunction via reperfusion injury. The protective effect and mechanism behind Po2 cycling in skeletal muscle during reoxygenation have yet to be fully elucidated. We hypothesize that Po2 cycling effectively increases muscle fatigue resistance through reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and certain mitochondrial channels during reoxygenation. Using a dihydrofluorescein fluorescent probe, we detected the production of ROS in mouse diaphragmatic skeletal muscle in real time under confocal microscopy. Muscles treated with Po2 cycling displayed significantly attenuated ROS levels (n = 5; P ROS, Akt, ERK, as well as chemical stimulators to close mitochondrial ATP-sensitive potassium channel (KATP) or open mitochondrial permeability transition pore (mPTP). All these blockers or stimulators abolished improved muscle function with Po2 cycling treatment. This current investigation has discovered a correlation between KATP and mPTP and the Po2 cycling pathway in diaphragmatic skeletal muscle. Thus we have identified a unique signaling pathway that may involve ROS, Akt, ERK, and mitochondrial channels responsible for Po2 cycling protection during reoxygenation conditions in the diaphragm. Copyright © 2015 the American Physiological Society.

A research on shape-controllable synthesis of Ag3PO4/AgBr and its degradation of ciprofloxacin.

Science.gov (United States)

Chen, Jingran; Yang, Xingyu; Zhu, Chenyu; Xie, Xin; Lin, Cuiping; Zhao, Yalei; Yan, Qishe

2018-03-01

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag 3 PO 4 /AgBr composite photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of cetyltrimethyl ammonium bromide (CTAB). CTAB was served as surfactant and the source of bromide ions. The as-prepared Ag 3 PO 4 /AgBr microspheres were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that the Ag 3 PO 4 /AgBr sample (synthesized with CTAB, 0.8 g) exhibited the highest photocatalytic activity to the photodegradation rate of 96.36%. Moreover, mechanism detection experiment indicated that h + was the major active species in the degradation process. So the enhanced photocatalytic activity of Ag 3 PO 4 /AgBr composites is attributed to its excellent separation of photogenerated electron-hole pairs through Ag 3 PO 4 /AgBr heterojunction. Also, Ag 3 PO 4 /AgBr heterojunction has a lower band gap compared to pure Ag 3 PO 4 and pure AgBr, so higher efficiency of light harvesting is equipped.

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

International Nuclear Information System (INIS)

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

1983-01-01

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

BaO-Nd2O3-CuOx subsolidus equilibria under carbonate-free conditions at pO2=100 Pa and at pO2=21 kPa

International Nuclear Information System (INIS)

Wong-Ng, W.; Cook, L.P.; Suh, J.; Coutts, R.; Stalick, J.K.; Levin, I.; Huang, Q.

2003-01-01

Subsolidus phase equilibria of the BaO-Nd 2 O 3 -CuO x system at pO 2 =100 Pa (0.1% O 2 volume fraction, 810 deg. C) and at pO 2 =21 kPa (21% O 2 volume fraction, 930 deg. C) have been investigated by applying controlled-atmosphere methods to minimize the presence of carbonate and CO 2 and H 2 O contamination. Under carbonate-free conditions, the BaO-Nd 2 O 3 -CuO x phase diagrams at pO 2 =100 Pa and at pO 2 =21 kPa are similar to one another except for differences in the extent of the solid solutions. Apart from the limiting binary phases, the ternary system consists of three solid solutions and one stoichiometric ternary compound. The first solid solution is the high T c series, Ba 2-x Nd 1+x Cu 3 O 6+z (0.3≥x≥0 at pO 2 =100 Pa; 0.95≥x≥ 0 at pO 2 =21 kPa). At pO 2 =21 kPa, a compositionally dependent phase change was detected, from tetragonal (0.7>x≥0) to orthorhombic (0.95≥x≥0.7). The second solid solution series, the 'brown-phase' Ba 1+x Nd 2-x CuO z , has a narrow homogeneity region (0.10>x≥0 at pO 2 =100 Pa; 0.15>x≥0 at pO 2 =21 kPa). In the high BaO part of the phase diagram, a third solid solution (Ba 2-x Nd x )CuO 3+z (x=0 to ∼ 0.3 at pO 2 =100 Pa; x=0-0.45 at pO 2 =21 kPa) was confirmed, as well as a nominally stoichiometric phase, Ba 4 Nd 2 Cu 2 O z . The latter phase is an insulator, with a structure comprised of unusual CuO 5 linear chains. A significant difference in tie line distribution involving the Ba 2-x Nd 1+x Cu 3 O 6+z superconductor was found under carbonate-free conditions relative to literature studies completed in air. Instead of the BaCuO 2+x -Ba 2+x Nd 4-x Cu 2 O z tie line normally encountered in air, a Ba 2-x Nd 1+x Cu 3 O 6+z -(Ba,Nd) 2 CuO 3+x tie line was established. This tie line substantially expands the field of stability of the Ba 2-x Nd 1+x Cu 3 O 6+z superconductor phase into the BaO-rich region of the phase diagram. Implications for the processing of materials based on the Ba 2-x Nd 1+x Cu 3 O 6+z

Radiochemical determination of 210 Po in tobacco and farm food

International Nuclear Information System (INIS)

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

2002-01-01

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

Volatilization of Po by microorganisms at laboratory culture experiments

International Nuclear Information System (INIS)

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

2005-01-01

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

Metabolic balances of 210Pb and 210Po at natural levels

International Nuclear Information System (INIS)

Spencer, H.; Holtzman, R.B.; Kramer, L.; Ilcewicz, F.H.

1977-01-01

Metabolic balances of 210 Po and 210 Pb were determined under strictly controlled dietary conditions in adult males. The intakes of the two nuclides were due to the dietary contents of these radioisotopes, inhalation from the atmosphere, and smoking of cigarettes. No additional radioisotope was given. The mean dietary intake of 210 Pb was 1.25 pCi/day and of 210 Po, 1.63 pCi/day. The major pathway of excretion of both nuclides is via the gastrointestinal tract and the urinary excretion is much lower. The total excretions of 210 Pb and 210 Po were greater than the dietary intake and the overall balances were -0.28 and -0.16 pCi/day for the two nuclides, respectively, during a low calcium intake. The 210 Pb balances did not change significantly when the calcium intake was increased 7- to 10-fold except for one patient in whom the balance became more negative. The 210 Po balance was more negative during calcium intakes of 800 and 2200 mg than during a low calcium intake of 200 mg/day. The urinary and fecal excretions of the two radionuclides were not affected by the intake of sodium fluoride, while the diuretic compound Hydrodiuril appeared to decrease the fecal 210 Pb excretion

Metabolic balances of 210Pb and 210Po at natural levels

International Nuclear Information System (INIS)

Spencer, H.; Holtzman, R.B.; Kramer, L.; Ilcewicz, F.H.

1977-01-01

Metabolic balances of 210 Po and 210 Pb were determined under strictly controlled dietary conditions in adult males. The intakes of the two nuclides were due to the dietary contents of these radioisotopes, inhalation from the atmosphere, and smoking of cigarettes. No additional radioisotope was given. The mean dietary intake of 210 Pb was 1.25 pCi/day and of 210 Po, 1.63 pCi/day. The major pathway of excretion of both nuclides is via the gastrointestinal tract; the urinary excretion is much lower. The total excretions of 210 Pb and 210 Po were greater than the dietary intake and the overall balances were -0.28 and -0.16 pCi/day for the two nuclides, respectively, during a low calcium intake. The 210 Pb balances did not change significantly when the calcium intake was increased 7- to 10-fold except for one patient in whom the balance became more negative. The 210 Po balance was more negative during calcium intakes of 800 and 2200 mg than during a low calcium intake of 200 mg/day. The urinary and fecal excretions of the two radionuclides were not affected by the intake of sodium fluoride, while the diuretic compound, Hydrodiuril, appeared to decrease the fecal 210 Pb excretion

A Comparative pO2 Probe and [18F]-Fluoro-Azomycinarabino-Furanoside ([18F]FAZA) PET Study Reveals Anesthesia-Induced Impairment of Oxygenation and Perfusion in Tumor and Muscle.

Science.gov (United States)

Mahling, Moritz; Fuchs, Kerstin; Thaiss, Wolfgang M; Maier, Florian C; Feger, Martina; Bukala, Daniel; Harant, Maren; Eichner, Martin; Reutershan, Jörg; Lang, Florian; Reischl, Gerald; Pichler, Bernd J; Kneilling, Manfred

2015-01-01

CT26 colon carcinoma-bearing mice were anesthetized with isoflurane (IF) or ketamine/xylazine (KX) while breathing air or oxygen (O2). We performed 10 min static PET scans 1 h, 2 h and 3 h after [18F]FAZA injection and calculated the [18F]FAZA-uptake and tumor-to-muscle ratios (T/M). In another experimental group, we placed a pO2 probe in the tumor as well as in the gastrocnemius muscle to measure the pO2 and perfusion. Ketamine/xylazine-anesthetized mice yielded up to 3.5-fold higher T/M-ratios compared to their isoflurane-anesthetized littermates 1 h, 2 h and 3 h after [18F]FAZA injection regardless of whether the mice breathed air or oxygen (3 h, KX-air: 7.1 vs. IF-air: 1.8, p = 0.0001, KX-O2: 4.4 vs. IF-O2: 1.4, p pO2 probe measurements yielded enhanced intra-tumoral pO2 values in air- and oxygen-breathing ketamine/xylazine-anesthetized mice compared to isoflurane-anesthetized mice (KX-air: 1.01 mmHg, IF-air: 0.45 mmHg; KX-O2 9.73 mmHg, IF-O2: 6.25 mmHg). Muscle oxygenation was significantly higher in air-breathing isoflurane-anesthetized (56.9 mmHg) than in ketamine/xylazine-anesthetized mice (33.8 mmHg, p = 0.0003). [18F]FAZA tumor uptake was highest in ketamine/xylazine-anesthetized mice regardless of whether the mice breathed air or oxygen. The generally lower [18F]FAZA whole-body uptake in isoflurane-anesthetized mice could be due to the higher muscle pO2-values in these mice compared to ketamine/xylazine-anesthetized mice. When performing preclinical in vivo hypoxia PET studies, oxygen should be avoided, and ketamine/xylazine-anesthesia might alleviate the identification of tumor hypoxia areals.

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

International Nuclear Information System (INIS)

Rahkonen, Vesa.

1980-08-01

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

H2O2 rejuvenation-mediated synthesis of stable mixed-morphology Ag3PO4 photocatalysts

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Henry Agbe

2018-04-01

Full Text Available Ag3PO4 photocatalyst has attracted interest of the scientific community in recent times due to its reported high efficiency for water oxidation and dye degradation. However, Ag3PO4 photo-corrodes if electron accepter such as AgNO3 is not used as scavenger. Synthesis of efficient Ag3PO4 followed by a simple protocol for regeneration of the photocatalyst is therefore a prerequisite for practical application. Herein, we present a facile method for the synthesis of a highly efficient Ag3PO4, whose photocatalytic efficiency was demonstrated using 3 different organic dyes: Methylene Blue (MB, Methyl orange (MO and Rhodamine B (RhB organic dyes for degradation tests. Approximately, 19 % of Ag3PO4 is converted to Ag0 after 4.30 hours of continuous UV-Vis irradiation in presence of MB organic dye. We have shown that the Ag/Ag3PO4 composite can be rejuvenated by a simple chemical oxidation step after several cycles of photocatalysis tests. At an optimal pH of 6.5, a mixture of cubic, rhombic dodecahedron, nanosphere and nanocrystals morphologies of the photocatalyst was formed. H2O2 served as the chemical oxidant to re-insert the surface metallic Ag into the Ag3PO4 photocatalyst but also as the agent that can control morphology of the regenerated as-prepared photocatalyst without the need for any other morphology controlling Agent (MCA. Surprisingly, the as- regenerated Ag3PO4 was found to have higher photocatalytic reactivity than the freshly made material and superior at least 17 times in comparison with the conventional Degussa TiO2, and some of TiO2 composites tested in this work. Keywords: Materials chemistry, Materials science, Engineering

Les poèmes ragusains de Dejan Despic

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Stefanović Ana

2005-01-01

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

Room temperature H{sub 2}S gas sensing characteristics of platinum (Pt) coated porous alumina (PoAl) thick films

Energy Technology Data Exchange (ETDEWEB)

More, P.S., E-mail: p_smore@yahoo.co.in [Department of Physics, Institute of Science, Mumbai 400 032 (India); Raut, R.W. [Department of Botany, Institute of Science, Mumbai 400 032 (India); Ghuge, C.S. [Department of Physics, Institute of Science, Mumbai 400 032 (India)

2014-02-14

The study reports H{sub 2}S gas sensing characteristics of platinum (Pt) coated porous alumina (PoAl) films. The porous alumina (PoAl) thick layers were formed in the dark on aluminum substrates using an electrochemical anodization method. Thin semitransparent platinum (Pt) films were deposited on PoAl samples using chemical bath deposition (CBD) method. The films were characterized using energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM). The thicknesses of coated and bare films were measured using ellipsometry. The sensing properties such as sensitivity factor (S.F.), response time, recovery time and repeatability were measured using a static gas sensing system for H{sub 2}S gas. The EDAX studies confirmed the purity of Pt–PoAl film and indicated the formation of pure platinum (Pt) phase. The ellipsometry studies revealed the thickness of PoAl layer of about 15–17 μm on aluminum substrates. The SEM studies demonstrated uniform distribution of spherical pores with a size between 0.250 and 0.500 μm for PoAl film and nearly spherical platinum particles with average particle size ∼100 nm for Pt–PoAl film. The gas-sensing properties of these samples were studied in a home-built static gas characterization system. The H{sub 2}S gas sensing properties of Pt–PoAl at 1000 ppm of H{sub 2}S gave maximum sensitivity factor (S.F.) = 1200. The response time and recovery time were found to be 2–3 min and ∼1 min respectively. Further, the measurement of H{sub 2}S gas sensing properties clearly indicated the repeatability of gas sensing response of Pt–PoAl film. The present study indicated the significant potential of Pt coated PoAl films for H{sub 2}S gas sensing applications in diverse areas. - Highlights: • Electrochemical anodization, cheap and effective method for fabrication of PoAl. • Chemical bath deposition, a simple and effective method for deposition of Pt on PoAl. • A nano-composite film sensor with high sensitivity

210Pb and 210Po Determination in Bottled Water Available on the Croatian Market

International Nuclear Information System (INIS)

Rogic, M.; Rozmaric Macefat, M.; Benedik, Lj.; Strok, M.

2011-01-01

An alpha emitting radionuclide 210Po and beta emitting radionuclide 210Pb are decay products of 238U. Due to their nuclear properties they are considered as radionuclides with the highest radiotoxicity and contribute significantly to the internal dose to the population received by drinking water. For radiological impact assessment 210Pb and 210Po must be measured routinely and accurately, with low detection limits. The aim of our study was determination of activity concentrations of 210Pb and 210Po in bottled drinking and mineral waters available on Croatian market. For their determination a procedure for their simultaneous separation from the water samples was used. After addition of 209Po tracer and lead carrier, radionuclides were preconcentrated from large volume by MnO 2 and their separation from interfering elements by Sr resin was done. 210Po source for alpha-particle spectrometric measurement was prepared by selfdeposition on silver disc, while lead was precipitated as lead sulphate and the beta activity of its daughter 210Bi was counted on a beta proportional counter. The results obtained show that values for activity concentrations of 210Pb and 210Po in all examined waters are in accordance with allowed activity concentration according to the European Commission Recommendation 2001/928/Euratom and Guidelines for Drinking Water Quality, published by WHO in 2006. (author)

LiHo(PO34

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Mokhtar Férid

2009-02-01

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

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

Science.gov (United States)

Saji, Viswanathan S; Song, Hyun-Kon

2015-01-01

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

Estimation of 210Po activity in mussel sample and its contribution in radiation dose to the public around Kanyakumari Coast, India

International Nuclear Information System (INIS)

Macklin Rani, L.; Govindaraju, M.; Jeevanram, R.K.; Muthukumaran, V.R.

2013-01-01

Polonium-210 ( 210 Po), a naturally occurring á-emitting radionuclide exists in the environment as a result of Uranium- 238 ( 238 U) decay chain. It is therefore ubiquitously distributed in the rocks, soils, making up Earths crust, in the atmosphere and in natural waters. 210 Po enters in marine organisms via adsorption, absorption and ingestion and is transferred through seafood consumption. The concentration of 210 Po in the edible portions of marine organisms may be many folds higher than that in the seawater because of biological re-concentration processes. In the present study, sampling sites were chosen to determine the difference of 210 Po concentration in bivalve mussel, an appropriate bio-indicator for radioactive contamination. The concentration of radionuclide Polonium-210 ( 210 Po) in brown mussel (Perna perna), obtained from different locations of Kanyakumari coastal area were estimated, which ranged between 76.0 ± 5.1 Bq/kg and 310.20 ± 18.4 Bq/kg. The highest activity was observed at Kalluvilai. The daily and annual intake of 210 Po from ingestion via mussel was estimated in these areas. To evaluate the internal exposure, annual committed effective dose to the adult population of this coastal area was determined and compared with the Indian and worldwide values to assess the risk status of the study area. It was observed that the average annual committed effective dose of 210 Po through ingestion is higher than the recommended dose of ICRP, 1990 (1 mSv/year) for general public due to the contribution of seafood, mussel species (3.09 mSv/year) in daily diet. (author)

LiFePO4 mesocrystals for lithium-ion batteries.

Science.gov (United States)

Popovic, Jelena; Demir-Cakan, Rezan; Tornow, Julian; Morcrette, Mathieu; Su, Dang Sheng; Schlögl, Robert; Antonietti, Markus; Titirici, Maria-Magdalena

2011-04-18

Olivine LiFePO(4) is considered one of the most promising cathode materials for Li-ion batteries. A simple one-step, template-free, low-temperature solvothermal method is developed for the synthesis of urchinlike hierarchical mesocrystals of pristine LiFePO(4) as well as carbon-coated LiFePO(4) composites. Each urchinlike mesocrystal consists of LiFePO(4) sheets self-assembled via a dipolar field in spheres during a solvothermal process under the influence of Cl(-) anions. The obtained primary sheets of LiFePO(4) are single crystalline in nature and can be coated in situ with an amorphous nitrogen-doped carbonaceous layer several nanometers in thickness. To increase the conductivity of the carbon coating, the materials are subjected to further temperature treatment (700 °C) under an inert atmosphere. The lithium storage performance of the pure LiFePO(4) is compared with that of its carbon-coated counterparts. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hypoxic Prostate/Muscle PO2 Ratio Predicts for Outcome in Patients With Localized Prostate Cancer: Long-Term Results

International Nuclear Information System (INIS)

Turaka, Aruna; Buyyounouski, Mark K.; Hanlon, Alexandra L.; Horwitz, Eric M.; Greenberg, Richard E.; Movsas, Benjamin

2012-01-01

Purpose: To correlate tumor oxygenation status with long-term biochemical outcome after prostate brachytherapy. Methods and Materials: Custom-made Eppendorf PO 2 microelectrodes were used to obtain PO 2 measurements from the prostate (P), focused on positive biopsy locations, and normal muscle tissue (M), as a control. A total of 11,516 measurements were obtained in 57 men with localized prostate cancer immediately before prostate brachytherapy was given. The Eppendorf histograms provided the median PO 2 , mean PO 2 , and % 2 ratio on BF. Results: With a median follow-up time of 8 years, 12 men had ASTRO BF and 8 had Phoenix BF. On multivariate analysis, P/M PO 2 ratio 2 ratio 2 ratio) significantly predicts for poor long-term biochemical outcome, suggesting that novel hypoxic strategies should be investigated.

210Pb and 210Po concentrations in the Venice lagoon ecosystem (Italy) and the potential radiological impact to the local public and environment

International Nuclear Information System (INIS)

Guogang Jia; Belli, M.; Sansone, U.; Rosamilia, S.; Blasi, M.

2003-01-01

In order to evaluate the possible radiological impact to the local public and environment from a phosphogypsum stockpile, 210 Po and 210 Pb concentrations in river water, lagoon water, suspended matter, superficial sediment, algae and bivalves samples collected in Venice lagoon area have been investigated. The results show that the mean 210 Po and 210 Pb concentrations in river water are 1.42 ± 0.36 mBq x l -1 and 1.46 ± 0.39 mBq x l -1 with a mean 210 Po/ 210 Pb ratio of 0.98 ± 0.17 and about 60% of them are associated with the particulate; 210 Po and 210 Pb contribution from the phosphogypsum stockpile to the river water is negligible. Higher 210 Po (2.61-5.67 mBq x l -1 ) and 210 Pb (1.31-3.62 mBq x l -1 ) concentrations in the lagoon waters have been observed if compared with the literature values. About 60% of 210 Po and 210 Pb are found in the soluble form with a mean 210 Po/ 210 Pb ratio of 1.79 ± 1.47. 210 Po and 210 Pb concentrations in 28 out 37 sediment samples ranged from 26 to 45 Bq x kg -1 (dry weight), only 9 sediments with 210 Po and 210 Pb concentrations greater than 45 Bq x kg -1 are found and most of them are located 1-4 km near the phosphogypsum stockpile. The elevated 210 Po and 210 Pb concentrations in the sediments may be due to the contamination from the phosphogypsum stockpile. The mean 210 Po/ 210 Pb ratio (0.986 ± 0.049) in the sediments shows that 210 Po and 210 Pb exist in nearly secular equilibrium. 210 Po and 210 Pb concentrations in algae vary with different species. The mean 210 Po and 210 Pb concentrations in Gracilaria compress and Ulva laetevirens which show a similar behavior, are 3.18 ± 1.23 Bq x kg -1 and 2.42 ± 1.26 Bq x kg -1 (fresh weight), respectively, with a mean 210 Po/ 210 Pb ratio of 1.45 ± 0.34. The mean concentration factors with respect to the filtered water are 1096 ± 424 for 210 Po and 1299 ± 680 for 210 Pb. The mean 210 Po and 210 Pb concentrations in the soft part of Mytilus edulis are 23.2 ± 9.7 Bq

Effects of titanium incorporation on phase and electrochemical performance in LiFePO4 cathode material

International Nuclear Information System (INIS)

Wang Zhaohui; Pang Quanquan; Deng Kejian; Yuan Lixia; Huang Fei; Peng Yunlong; Huang Yunhui

2012-01-01

Highlights: ► Nominal LiFe 1−x Ti x PO 4 cathode materials were synthesized via solid-state reaction. ► A clear feature of Ti-doped LiFePO 4 has been clarified. ► The formation of impurity phases strongly depends on Ti doping level. ► Appropriate amount of Ti in LiFePO 4 can enhance the electrochemical performance. - Abstract: Ti-incorporated LiFe 1−x Ti x PO 4 (0 ≤ x ≤ 0.2) samples have been prepared via a two-step solid-state reaction route. The samples have systematically been investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge/discharge measurements. The incorporation of Ti in LiFePO 4 significantly enhances the electrochemical performance; the carbon-coated LiFe 0.9 Ti 0.1 PO 4 sample shows the best performance. It is confirmed that LiFe 1−x Ti x PO 4 with x ≤ 0.05 are of single phase while those with 0.07 ≤ x ≤ 0.2 contain impurity phases: LiTi 2 (PO 4 ) 3 and TiP 2 O 7 . The impurities influence not only the electronic conductivity, but also the total specific capacity. Appropriate amount of titanium incorporation is favorable for the improvement in electrochemical performance.

Radiotherapy in conjunction with 7-hydroxystaurosporine: a multimodal approach with tumor pO2 as a potential marker of therapeutic response.

Science.gov (United States)

Khan, Nadeem; Mupparaju, Sriram P; Hou, Huagang; Lariviere, Jean P; Demidenko, Eugene; Swartz, Harold M; Eastman, Alan

2009-11-01

Checkpoint inhibitors potentially could be used to enhance cell killing by DNA-targeted therapeutic modalities such as radiotherapy. UCN-01 (7-hydroxystaurosporine) inhibits S and G2 checkpoint arrest in the cells of various malignant cell lines and has been investigated in combination with chemotherapy. However, little is known about its potential use in combination with radiotherapy. We report the effect of 20 Gy radiation given in conjunction with UCN-01 on the pO2 and growth of subcutaneous RIF-1 tumors. Multisite EPR oximetry was used for repeated, non-invasive tumor pO2 measurements. The effect of UCN-01 and/or 20 Gy on tumor pO2 and tumor volume was investigated to determine therapeutic outcomes. Untreated RIF-1 tumors were hypoxic with a tissue pO2 of 5-7 mmHg. Treatment with 20 Gy or UCN-01 significantly reduced tumor growth, and a modest increase in tumor pO2 was observed in tumors treated with 20 Gy. However, irradiation with 20 Gy 12 h after UCN-01 treatment resulted in a significant inhibition of tumor growth and a significant increase in tumor pO2 to 16-28 mmHg from day 1 onward compared to the control, UCN-01 or 20-Gy groups. Treatment with UCN-01 12 h after 20 Gy also led to a similar growth inhibition of the tumors and a similar increase in tumor pO2. The changes in tumor pO2 observed after the treatment correlated inversely with the tumor volume in the groups receiving UCN-01 with 20 Gy. This multimodal approach could be used to enhance the outcome of radiotherapy. Furthermore, tumor pO2 could be a potential marker of therapeutic response.

Moderní počítačové viry

OpenAIRE

Malina, Lukáš

2008-01-01

Bakalářská práce Moderní počítačové viry se skládá ze dvou hlavních cílů (Analýza počítačových virů a návrh zabezpečení střední počítačové sítě) rozdělených na tři části: Analýza počítačových virů, Vlastní návrh zabezpečení osobního počítače koncového uživatele (Terminálu) a Vlastní návrh zabezpečení střední počítačové sítě. V první části jsou analyzovány metody šíření a infekce, specifické vlastnosti a dopady počítačových virů na osobní počítače. V druhé části je uvedeno řešení zabezpečení o...

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

Science.gov (United States)

Liu, Li-Chen; Ren, Wei-Jian; Huang, Ya-Xi; Pan, Yuanming; Mi, Jin-Xiao

2017-10-01

A new nickel phosphate KNi3[PO3(F,OH)]2[PO2(OH)2]F2 has been synthesized using a modified hydrothermal method. Structural characterizations show that it adopts a 3D framework structure with 2D layers of Ni octahedra in a stair-case Kagomé lattice. The Ni2 octahedron at the inversion center shares two trans-faces with Ni1 octahedra to form a linear trimer (Ni3O8F6) as the basic structural unit. The Ni-trimers are linked between themselves by sharing F-corners and to [PO3(F,OH)] tetrahedral groups by sharing O-corners to form 2D stair-case Kagomé layers, which are parallel to the (100) plane and are stacked along the a-axis. Successive Kagomé layers are combined together by [PO2(OH)2] tetrahedral groups and interstice cations K+. Magnetic measurements reveal that KNi3[PO3(F,OH)]2[PO2(OH)2]F2 exhibits a canted antiferromagnetic ordering with a ferromagnetic component at low temperatures.

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

International Nuclear Information System (INIS)

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

1990-01-01

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

Lifetime measurement in {sup 195}Po

Energy Technology Data Exchange (ETDEWEB)

Grahn, T.; Page, R.D. [University of Liverpool, Department of Physics, Oliver Lodge Laboratory, Liverpool (United Kingdom); Dewald, A.; Jolie, J.; Melon, B.; Pissulla, T. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Greenlees, P.T.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Peura, P.; Rahkila, P.; Saren, J.; Scholey, C.; Sorri, J.; Uusitalo, J. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, Jyvaeskylae (Finland); Kroell, T.; Kruecken, R.; Maierbeck, P. [TU Muenchen, Physik-Department E12, Garching (Germany)

2009-03-15

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

Three-dimensional graphene/LiFePO4 nanostructures as cathode materials for flexible lithium-ion batteries

International Nuclear Information System (INIS)

Ding, Y.H.; Ren, H.M.; Huang, Y.Y.; Chang, F.H.; Zhang, P.

2013-01-01

Graphical abstract: Graphene/LiFePO 4 composites as a high-performance cathode material for flexible lithium-ion batteries have been prepared by using a co-precipitation method to synthesize graphene/LiFePO4 powders as precursors and then followed by a solvent evaporation process. - Highlights: • Flexible LiFePO 4 /graphene films were prepared first time by a solvent evaporation process. • The flexible electrode exhibited a high discharge capacity without conductive additives. • Graphene network offers the electrode adequate strength to withstand repeated flexing. - Abstract: Three-dimensional graphene/LiFePO 4 nanostructures for flexible lithium-ion batteries were successfully prepared by solvent evaporation method. Structural characteristics of flexible electrodes were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrochemical performance of graphene/LiFePO 4 was examined by a variety of electrochemical testing techniques. The graphene/LiFePO 4 nanostructures showed high electrochemical properties and significant flexibility. The composites with low graphene content exhibited a high capacity of 163.7 mAh g −1 at 0.1 C and 114 mAh g −1 at 5 C without further incorporation of conductive agents

Leaching of 210Po in human saliva from smokeless tobacco

International Nuclear Information System (INIS)

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

2009-01-01

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

Local structure of vanadium in doped LiFePO4

International Nuclear Information System (INIS)

Zhao, Ting; Xu, Wei; Ye, Qing; Cheng, Jie; Zhao, Haifeng; Chu, Wangsheng; Wu, Ziyu; Univ. of Science and Technology of China, Hefei; Xia, Dingguo

2010-01-01

LiFePO 4 composites with 5 at.% vanadium doping are prepared by solid state reactions. X-ray absorption fine-structure spectroscopy is used as a novel technique to identify vanadium sites. Both experimental analyses and theoretical simulations show that vanadium does not enter into the LiFePO 4 crystal lattice. When the vanadium concentration is lower then 1 at.%, the dopant remains insoluble. Thus, a single-phase vanadium-doped LiFePO4 cannot be formed and the improved electrochemical properties of vanadium doped LiFePO 4 previously reported cannot be associated with crystal structure changes of the LiFePO 4 via vanadium doping. (orig.)

Synthesis of xLiMnPO4·yLi3V2(PO43/C Nanocomposites for Lithium Ion Batteries Using Tributyl Phosphate as Phosphor Source

Directory of Open Access Journals (Sweden)

Yanming Wang

2017-01-01

Full Text Available The xLiMnPO4·yLi3V2(PO43/C (x/y = 1 : 0, 12 : 1, 8 : 1, 6 : 1, 4 : 1, 0 : 1 composite cathode materials are synthesized using tributyl phosphate as a novel organic phosphor source via a solid-state reaction process. All obtained xLiMnPO4·yLi3V2(PO43/C composites present similar particles morphology with an average size of ca. 100 nm and low extent agglomeration. The electrochemical performance of pristine LiMnPO4/C can be effectively improved by adding small amounts of Li3V2(PO43 additives. The 4LiMnPO4·Li3V2(PO43/C has a high discharge capacity of 143 mAh g−1 at 0.1 C and keeps its 94% at the end of 100 cycles.

Improvement of the mechanical properties and corrosion resistance of biodegradable β-Ca3(PO4)2/Mg-Zn composites prepared by powder metallurgy: the adding β-Ca3(PO4)2, hot extrusion and aging treatment.

Science.gov (United States)

Yan, Yang; Kang, Yijun; Li, Ding; Yu, Kun; Xiao, Tao; Deng, Youwen; Dai, Han; Dai, Yilong; Xiong, Hanqing; Fang, Hongjie

2017-05-01

In this study, 10%β-Ca 3 (PO 4 ) 2 /Mg-6%Zn (wt.%) composites with Mg-6%Zn alloy as control were prepared by powder metallurgy. After hot extrusion, the as-extruded composites were aged for 72h at 150°C. The effects of the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment on their microstructure, mechanical properties and corrosion resistance were investigated. The XRD results identified α-Mg, MgZn phase and β-Ca 3 (PO 4 ) 2 phase in these composites. After hot extrusion, grains were significantly refined, and the larger-sized β-Ca 3 (PO 4 ) 2 particles and coarse MgZn phases were broken into linear-distributed β-Ca 3 (PO 4 ) 2 and MgZn phases along the extrusion direction. After aging treatment, the elements of Zn, Ca, P and O presented a more homogeneous distribution. The compressive strengths of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites were approximately double those of natural bone, and their densities and elastic moduli matched those of natural bone. The immersion tests and electrochemical tests revealed that the adding β-Ca 3 (PO 4 ) 2 , hot extrusion and aging treatment could promote the formation of protective corrosion product layer on the sample surface in Ringer's solution, which improved corrosion resistance of the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites. The XRD results indicated that the corrosion product layer contained Mg(OH) 2 , β-Ca 3 (PO 4 ) 2 and hydroxyapatite (HA). The cytotoxicity assessments showed the as-extruded β-Ca 3 (PO 4 ) 2 /Mg-Zn composite aged for 72h was harmless to L-929 cells. These results suggested that the β-Ca 3 (PO 4 ) 2 /Mg-Zn composites prepared by powder metallurgy were promising to be used for bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

In situ high-resolution transmission electron microscopy synthesis observation of nanostructured carbon coated LiFePO 4

Science.gov (United States)

Trudeau, M. L.; Laul, D.; Veillette, R.; Serventi, A. M.; Mauger, A.; Julien, C. M.; Zaghib, K.

In situ high-resolution transmission electron microscopy (HRTEM) studies of the structural transformations that occur during the synthesis of carbon-coated LiFePO 4 (C-LiFePO 4) and heat treatment to elevated temperatures were conducted in two different electron microscopes. Both microscopes have sample holders that are capable of heating up to 1500 °C, with one working under high vacuum and the other capable of operating with the sample surrounded by a low gaseous environment. The C-LiFePO 4 samples were prepared using three different compositions of precursor materials with Fe(0), Fe(II) or Fe(III), a Li-containing salt and a polyethylene- block-poly(ethylene glycol)-50% ethylene oxide or lactose. The in situ TEM studies suggest that low-cost Fe(0) and a low-cost carbon-containing compound such as lactose are very attractive precursors for mass production of C-LiFePO 4, and that 700 °C is the optimum synthesis temperature. At temperatures higher than 800 °C, LiFePO 4 has a tendency to decompose. The same in situ measurements have been made on particles without carbon coat. The results show that the homogeneous deposit of the carbon deposit at 700 °C is the result of the annealing that cures the disorder of the surface layer of bare LiFePO 4. Electrochemical tests supported the conclusion that the C-LiFePO 4 derived from Fe(0) is the most attractive for mass production.

International intercomparison on glass implanted 210Po in Yugoslavian houses

International Nuclear Information System (INIS)

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

2000-01-01

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

Tunable morphology synthesis of LiFePO4 nanoparticles as cathode materials for lithium ion batteries.

Science.gov (United States)

Ma, Zhipeng; Shao, Guangjie; Fan, Yuqian; Wang, Guiling; Song, Jianjun; Liu, Tingting

2014-06-25

Olivine LiFePO4 with nanoplate, rectangular prism nanorod and hexagonal prism nanorod morphologies with a short b-axis were successfully synthesized by a solvothermal in glycerol and water system. The influences of solvent composition on the morphological transformation and electrochemical performances of olivine LiFePO4 are systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and galvanostatic charge-discharge tests. It is found that with increasing water content in solvent, the LiFePO4 nanoplates gradually transform into hexagonal prism nanorods that are similar to the thermodynamic equilibrium shape of the LiFePO4 crystal. This indicates that water plays an important role in the morphology transformation of the olivine LiFePO4. The electrochemical performances vary significantly with the particle morphology. The LiFePO4 rectangular prism nanorods (formed in a glycerol-to-water ratio of 1:1) exhibit superior electrochemical properties compared with the other morphological particles because of their moderate size and shorter Li(+) ion diffusion length along the [010] direction. The initial discharge capacity of the LiFePO4@C with a rectangular prism nanorod morphology reaches to 163.8 mAh g(-1) at 0.2 C and over 75 mAh g(-1) at the high discharging rate of 20 C, maintaining good stability at each discharging rate.

Natural levels of {sup 210}Po in human urine

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-01

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

The hydrogen dynamics of CsH5(PO4)2 studied by means of nuclear magnetic resonance

International Nuclear Information System (INIS)

Gradisek, A; Dimnik, B; Vrtnik, S; Dolinsek, J; Wencka, M; Zdanowska Fraczek, M; Lavrova, G V

2011-01-01

We have investigated the hydrogen dynamics of cesium pentahydrogen diphosphate, CsH 5 (PO 4 ) 2 , by means of nuclear magnetic resonance (NMR) spectroscopy, in order to address the question of why there is no superprotonic phase transition in this compound, in contrast to other structurally similar hydrogen-bonded ionic salts, where a superprotonic transition is frequently found to be present. The analysis of the NMR spectrum and the spin-lattice relaxation rate revealed that the temperature-dependent hydrogen dynamics of CsH 5 (PO 4 ) 2 involves motional processes (the intra-H-bond jumps and the inter-H-bond jumps at elevated temperatures, as a mechanism of the ionic conductivity) identical to those for the other H-bonded superprotonic salts. The considerably stronger H-bond network in CsH 5 (PO 4 ) 2 prompts the search for a higher superprotonic transition temperature. However, due to the relatively weak bonding between the {[H 2 PO 4 ]} ∞ planes in the [100] direction of the CsH 5 (PO 4 ) 2 structure by means of the ionic bonding via the cesium atoms and the small number of H bonds in that direction (where out of five H bonds in the unit cell, four are directed within the {[H 2 PO 4 ]} ∞ planes and only one is between the planes), the bonds between the planes become thermally broken and the crystal melts before the H-bond network rearranges via water release into an open structure typical of the superprotonic phase. Were the coupling between the {[H 2 PO 4 ]} ∞ planes in the CsH 5 (PO 4 ) 2 somewhat stronger, the superprotonic transition would occur in the same manner as it does in other structurally related hydrogen-bonded ionic salts.

Sup(210)Pb and 210Po distributions and disequilibrium in the coastal and shelf waters of the southern North Sea

International Nuclear Information System (INIS)

Zhizheng, Zuo; Eisma, Doeke

1993-01-01

Concentration profiles of 210 Pb and 210 Po were measured at 10 stations in the coastal and shelf areas of the southern North Sea. Scavenging processes in this study area are revealed by 210 Po/ 210 Pb disequilibrium and their distributions in the water column. Results for 210 Po show strong excess, relative to 210 Pb, in both dissolved and particulate forms, indicating an additional flux of 210 Po from the coastal and shelf sediment. A significant maximum of the dissolved 210 Po and 210 Pb over the fine grained depositional area (Oyster Ground) was observed to correspond with resuspension of the underlying muddy sediments. A comparison of the data between the water and sediment columns shows that the excess of 210 Po found in the water body could be balanced by only a small amount of deficit of 210 Po in the sediment, due to the characteristics of this continental shelf area. (author)

Significant visible-light photocatalytic enhancement in Rhodamine B degradation of silver orthophosphate via the hybridization of N-doped graphene and poly(3-hexylthiophene)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yanlin, E-mail: zhangyl@scnu.edu.cn; Xie, Churu; Gu, Feng Long, E-mail: Gu@scnu.edu.cn; Wu, Honghai; Guo, Qiang

2016-09-05

Highlights: • The Ag{sub 3}PO{sub 4}/NG/P3HT composites were synthesized via a facile method. • The Ag{sub 3}PO{sub 4}/NG/P3HT composites exhibit excellent photocatalytic activity for RhB degradation. • The kinetic constant of Ag{sub 3}PO{sub 4}/NG/P3HT is more than 6 times of pristine Ag{sub 3}PO{sub 4}. • The composites show better recyclability and stability than pristine Ag{sub 3}PO{sub 4}. - Abstract: Organic pollutants as typical water contaminants are potentially harmful to human health. In this study, we suggested that the novel Ag{sub 3}PO{sub 4}/N-doped graphene (NG)/Poly(3-hexylthiophene) (P3HT) composites can remove the organic dye Rhodamine B (RhB) from water. This Ag{sub 3}PO{sub 4}-based photocatalyst was synthesized via a facile method and subsequently characterized by XRD, SEM, TEM, XPS, Raman spectroscopy, PL spectroscopy, and UV–vis DRS. The photocatalytic activity of Ag{sub 3}PO{sub 4}/NG/P3HT composites is significantly higher than that of pristine Ag{sub 3}PO{sub 4}, Ag{sub 3}PO{sub 4}/NG, and Ag{sub 3}PO{sub 4}/P3HT for RhB degradation under visible light irradiation, especially the kinetic constant of Ag{sub 3}PO{sub 4}/NG/P3HT is more than 6 times of pristine Ag{sub 3}PO{sub 4}. The reactive oxygen species trapping experiments indicate that the degradation of RhB over the Ag{sub 3}PO{sub 4}/NG/P3HT composites mainly results from the holes oxidation and superoxide radical reduction. Besides, Ag{sub 3}PO{sub 4}/NG/P3HT composites exhibit better recyclability and stability than pristine Ag{sub 3}PO{sub 4}. Furthermore, the photocatalytic mechanism of Ag{sub 3}PO{sub 4}/NG/P3HT composites for RhB degradation under visible light was proposed as the synergistic effect of irradiated Ag{sub 3}PO{sub 4}, P3HT and NG sheets on the effective separation of photogenerated electron-hole pairs, and the enhancement of visible light absorbance.

Investigation of the Na2(H2PO2)2 - Ba(H2PO2)2 - H2O Water-Salt Ternary System at Room Temperature

OpenAIRE

Erge, Hasan; Turan, Hakan; Kul, Ali Riza

2016-01-01

Objective: In this study, the solubility, density, conductivity and phase equilibria of the Na2(H2PO2)2-Ba(H2PO2)2-H2O ternary system located in the structure of the Na+, Ba2+, (H2PO2)-//H2O quaternary reciprocal water-salt system were investigated using physicochemical analysis methods. Material and Methods: Riedel-de Haen and Merck salts were used to investigate the solubility and phase equilibria of the Na2(H2PO2)2 -Ba(H2PO2)2-H2O ternary water–salt system at room temperature Res...

PoSSUM: Polar Suborbital Science in the Upper Mesosphere

Science.gov (United States)

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

2013-12-01

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

/sup 210/Pb and /sup 210/Po in liver and kidneys of cattle. 1. Animals from an area with little traffic or industry

Energy Technology Data Exchange (ETDEWEB)

Bunzl, K; Kracke, W [Gesellschaft fuer Strahlen- und Umweltforschung m.b.H., Neuherberg (Germany, F.R.). Inst. fuer Strahlenschutz; Kreuzer, W

1979-09-01

The concentrations of /sup 210/Pb, /sup 210/Po and stable lead were determined in liver and kidneys of 40 animals from a mainly agricultural region with little traffic or industry. Median liver concentrations of 18.0 pCi /sup 210/Pb and 33.3 pCi /sup 210/Po per wet tissue, and median kidney concentrations of 44.0 pCi /sup 210/Pb and 178.5 pCi /sup 210/Po/kg wet tissue were observed. The specific activity of /sup 210/Pb was 161 and 132 nCi /sup 210/Pb/g Pb in liver and kidneys, respectively. On the average, the kidneys contained 2.37 more /sup 210/Pb, 5.05 more /sup 210/Po and 2.89 more Pb than the livers. The ratio /sup 210/Po//sup 210/Pb was 2.18 in the liver and 3.95 in the kidneys. Correlation analysis revealed significant correlations between /sup 210/Po in liver and kidneys, Pb in liver and kidneys, /sup 210/Po and /sup 210/Pb in kidneys, /sup 210/Pb and Pb in liver, /sup 210/Pb and Pb in kidneys, /sup 210/Po and Pb in liver, as well as /sup 210/Po and Pb in kidneys. No significant correlation was observed between the concentrations of either /sup 210/Po or /sup 210/Pb in liver or kidneys and the age of the animals.

Relaxation-Induced Memory Effect of LiFePO4 Electrodes in Li-Ion Batteries.

Science.gov (United States)

Jia, Jianfeng; Tan, Chuhao; Liu, Mengchuang; Li, De; Chen, Yong

2017-07-26

In Li-ion batteries, memory effect has been found in several commercial two-phase materials as a voltage bump and a step in the (dis)charging plateau, which delays the two-phase transition and influences the estimation of the state of charge. Although memory effect has been first discovered in olivine LiFePO 4 , the origination and dependence are still not clear and are critical for regulating the memory effect of LiFePO 4 . Herein, LiFePO 4 has been synthesized by a home-built spray drying instrument, of which the memory effect has been investigated in Li-ion batteries. For as-synthesized LiFePO 4 , the memory effect is significantly dependent on the relaxation time after phase transition. Besides, the voltage bump of memory effect is actually a delayed voltage overshooting that is overlaid at the edge of stepped (dis)charging plateau. Furthermore, we studied the kinetics of LiFePO 4 electrode with electrochemical impedance spectroscopy (EIS), which shows that the memory effect is related to the electrochemical kinetics. Thereby, the underlying mechanism has been revealed in memory effect, which would guide us to optimize two-phase electrode materials and improve Li-ion battery management systems.

Removal of FePO4 and Fe3(PO4)2 crystals on the surface of passive fillers in Fe0/GAC reactor using the acclimated bacteria

International Nuclear Information System (INIS)

Lai, Bo; Zhou, Yuexi; Yang, Ping; Wang, Juling; Yang, Jinghui; Li, Huiqiang

2012-01-01

Highlights: ► Fe 3 (PO 4 ) 2 and FePO 4 crystals would weaken treatment efficiency of Fe 0 /GAC reactor. ► Fe 3 (PO 4 ) 2 and FePO 4 crystals could be removed by the acclimated bacteria. ► FeS and sulfur in the passive film would be removed by the sulfur-oxidizing bacteria. ► Develop a cost-effective bio-regeneration technology for the passive fillers. - Abstract: As past studies presented, there is obvious defect that the fillers in the Fe 0 /GAC reactor begin to be passive after about 60 d continuous running, although the complicated, toxic and refractory ABS resin wastewater can be pretreated efficiently by the Fe 0 /GAC reactor. During the process, the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film are formed by the reaction between PO 4 3− and Fe 2+ /Fe 3+ . Meanwhile, they obstruct the formation of macroscopic galvanic cells between Fe 0 and GAC, which will lower the wastewater treatment efficiency of Fe 0 /GAC reactor. In this study, in order to remove the Fe 3 (PO 4 ) 2 and FePO 4 crystals on the surface of the passive fillers, the bacteria were acclimated in the passive Fe 0 /GAC reactor. According to the results, it can be concluded that the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film could be decomposed or removed by the joint action between the typical propionic acid type fermentation bacteria and sulfate reducing bacteria (SRB), whereas the PO 4 3− ions from the decomposition of the Fe 3 (PO 4 ) 2 and FePO 4 crystals were released into aqueous solution which would be discharged from the passive Fe 0 /GAC reactor. Furthermore, the remained FeS and sulfur (S) in the passive film also can be decomposed or removed easily by the oxidation of the sulfur-oxidizing bacteria. This study provides some theoretical references for the further study of a cost-effective bio-regeneration technology to solve the passive problems of the fillers in the zero-valent iron (ZVI) or Fe 0 /GAC reactor.

Effect of Hyperoxygenation on Tissue pO2 and Its Effect on Radiotherapeutic Efficacy of Orthotopic F98 Gliomas

International Nuclear Information System (INIS)

Khan, Nadeem; Mupparaju, Sriram M.S.; Hekmatyar, Shahryar K.; Hou Huagang; Lariviere, Jean P.; Demidenko, Eugene; Gladstone, David J.; Kauppinen, Risto A.; Swartz, Harold M.

2010-01-01

Purpose: Lack of methods for repeated assessment of tumor pO 2 limits the ability to test and optimize hypoxia-modifying procedures being developed for clinical applications. We report repeated measurements of orthotopic F98 tumor pO 2 and relate this to the effect of carbogen inhalation on tumor growth when combined with hypofractionated radiotherapy. Methods and Materials: Electron paramagnetic resonance (EPR) oximetry was used for repeated measurements of tumor and contralateral brain pO 2 in rats during 30% O 2 and carbogen inhalation for 5 consecutive days. The T 1 -enhanced volumes and diffusion coefficients of the tumors were assessed by magnetic resonance imaging (MRI). The tumors were irradiated with 9.3 Gy x 4 fractions in rats breathing 30% O 2 or carbogen to determine the effect on tumor growth. Results: The pretreatment F98 tumor pO 2 varied between 8 and 16 mmHg, while the contralateral brain had 41 to 45 mmHg pO 2 during repeated measurements. Carbogen breathing led to a significant increase in tumor and contralateral brain pO 2 ; however, this effect declined over days. Irradiation of the tumors in rats breathing carbogen resulted in a significant decrease in tumor growth and an increase in the diffusion coefficient measured by MRI. Conclusions: The results provide quantitative measurements of the effect of carbogen inhalation on intracerebral tumor pO 2 and its effect on therapeutic outcome. Such direct repeated pO 2 measurements by EPR oximetry can provide temporal information that could be used to improve therapeutic outcome by scheduling doses at times of improved tumor oxygenation. EPR oximetry is currently being tested for clinical applications.

Clinical significance of orthostatic dizziness in the diagnosis of benign paroxysmal positional vertigo and orthostatic intolerance.

Science.gov (United States)

Jeon, Eun-Ju; Park, Yong-Soo; Park, Shi-Nae; Park, Kyoung-Ho; Kim, Dong-Hyun; Nam, In-Chul; Chang, Ki-Hong

2013-01-01

Orthostatic dizziness (OD) and positional dizziness (PD) are considerably common conditions in dizziness clinic, whereas those two conditions are not clearly separated. We aimed to evaluate the clinical significance of simple OD and OD combined with PD for the diagnosis of benign paroxysmal positional vertigo (BPPV) and orthostatic intolerance (OI). Patients presenting with OD (n=102) were divided into two groups according to their symptoms: group PO, presenting with PD as well as OD; group O, presenting with OD. A thorough medical history, physical examination, and vestibular function tests were performed to identify the etiology of the dizziness. Orthostatic vital sign measurement (OVSM) was used to diagnose OI. The majority of patients were in group PO (87.3%). BPPV was the most common cause of OD for entire patients (36.3%) and group PO (37.1%), while OI was most common etiology for group O (38.5%). Total of 17 (16.7%) OI patients were identified by OVSM test. Orthostatic hypotension (n=10) was most frequently found, followed by orthostatic hypertension (n=5), and orthostatic tachycardia (n=2). Group O showed significantly higher percentage (38.5%) of OI than group PO (13.5%) (P=0.039). It is suggested that orthostatic testing such as OVSM or head-up tilt table test should be performed as an initial work up for the patients with simple OD. Positional tests for BPPV should be considered as an essential diagnostic test for patients with OD, even though their dizziness is not associated with PD. Copyright © 2013 Elsevier Inc. All rights reserved.

Synthesis of flower-like LiMnPO4/C with precipitated NH4MnPO4·H2O as precursor

International Nuclear Information System (INIS)

Liu Jiali; Hu Dongge; Huang Tao; Yu Aishui

2012-01-01

Highlights: ► Flower-like NH 4 MnPO 4 ·H 2 O is obtained by novel precipitating method. ► It is used as the precursor to synthesize LiMnPO 4 /C. ► Subsequent heat treatment would not destroy the precursor morphology. ► As-prepared LiMnPO 4 /C showed discharge capacity of 85 mAh/g at 0.05 C. - Abstract: Ammonium magnesium phosphate monohydrate (NH 4 MnPO 4 ·H 2 O) precursor was prepared by a novel precipitating process with manganese citrate complexes as intermediate. The morphology of the precursor observed by Scanning Electron Microscope (SEM) was flower-like which was self-assembled by plate-like particles. Further analysis by X-ray diffraction (XRD) revealed that the lattice of the plate crystal was orientated along (0 1 0) plane. By solid-state reaction of the precursor, with lithium acetate and glucose as carbon source, pure olivine structured LiMnPO 4 /C composite was obtained and meanwhile, the original flower-like morphology could be retained.

poCAMon personal online continuous airmonitor; poCAMon online Personen Aerosolmonitor

Energy Technology Data Exchange (ETDEWEB)

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

2015-07-01

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

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

International Nuclear Information System (INIS)

Maier, K.H.

1985-01-01

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

Assessment of Po-210 exposure for the Italian population

International Nuclear Information System (INIS)

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

1980-01-01

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

Improving cylinder-type LiFePO4 battery performance via control of internal resistance

Science.gov (United States)

Purwanto, Agus; Jumari, Arif; Nizam, Muhammad; Widiyandari, Hendri; Sudaryanto; Deswita; Azmin Mohamad, Ahmad

2018-04-01

Strategies for controlling the internal resistance to improve battery performance were systematically investigated. Electrode densification of LiFePO4 cathodes significantly reduced the internal resistance of the prepared batteries. Densification by reduction to 31.25% of initial thickness resulted in optimal electrochemical performance of the prepared LiFePO4 batteries. The addition of KS 6 graphite material improved the conductivity of the cathodes, which was indicated by a lowering of the internal resistance. The internal resistance was decreased from 73 to 54 when the KS6/AB ratio was varied from 3 to 1. Another factor in controlling the internal resistance was the location of a welded aluminum tab in the cathode. The welding of an aluminum tab in a small gap in the cathode significantly reduced the internal resistance. Thus, three main factors can be performed during fabrication to reduce the internal resistance of a LiFePO4 battery: cathode densification, KS-6 graphite addition, and the arrangement of an aluminum tab welded to the cathode. By optimizing these factors, high-performance LFP batteries were produced.

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

Science.gov (United States)

Pimpalshende, D M; Dhoble, S J

2015-03-01

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

Towards a construction grammar account of the distributive PO in Polish

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Adam Przepiórkowski

2015-11-01

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

Hot and cold pressing of (La,Ce)PO4-based nuclear waste forms

International Nuclear Information System (INIS)

Floran, R.J.; Rappaz, M.; Abraham, M.M.; Boatner, L.A.

1981-01-01

Synthetic analogs of the mineral monazite [(Ce,La,Ca,Th,U)(P,Si)O 4 ] are promising host phases for the isolation of actinide wastes. In the present investigation, the optimal conditions necessary to form high-density, simulated waste pellets from calcined LaPO 4 and CePO 4 powders have been examined. Pellets that are close to the theoretical density are necessary in order to minimize porosity and hence potential avenues along which fluid/waste interactions can take place. Calcined powders prepared by a urea precipitation process were cold pressed and hot pressed under a range of controlled conditions to form coherent, cylindrical pellets. Changes in density were examined as a function of pressure, temperature and duration of sintering. For cold-pressed pellets, a significant increase in density occurs during sintering between 1000 0 C and 1100 0 C. This increase is correlated with substantial grain coarsening of the pellet microstructure. A comparison of cold and hot pressing techniques suggests that, only after sintering, does the density of cold-pressed pellets approach (but not equal) that of the hot-pressed pellets. Densities >90% of the theoretical value of 5.11 g/cm 3 are easily attainable by hot pressing without sintering. The significance of density differences on pellet stability will be investigated in future leaching studies. The apparent advantages of the higher densities achieved by hot pressing must be weighed against the increased technological/engineering complexities involved when working at sustained high temperatures in a remote environment. Thus the cold pressing technique may ultimately prove more practical for large-scale commercial operations

The onset collectivity in {sup 196}Po

Energy Technology Data Exchange (ETDEWEB)

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

1992-08-01

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

First-principles investigation of the electronic and Li-ion diffusion properties of LiFePO4 by sulfur surface modification

International Nuclear Information System (INIS)

Xu, Guigui; Zhong, Kehua; Zhang, Jian-Min; Huang, Zhigao

2014-01-01

We present a first-principles calculation for the electronic and Li-ion diffusion properties of the LiFePO 4 (010) surface modified by sulfur. The calculated formation energy indicates that the sulfur adsorption on the (010) surface of the LiFePO 4 is energetically favored. Sulfur is found to form Fe-S bond with iron. A much narrower band gap (0.67 eV) of the sulfur surface-modified LiFePO 4 [S-LiFePO 4 (010)] is obtained, indicating the better electronic conductive properties. By the nudged elastic band method, our calculations show that the activation energy of Li ions diffusion along the one-dimensional channel on the surface can be effectively reduced by sulfur surface modification. In addition, the surface diffusion coefficient of S-LiFePO 4 (010) is estimated to be about 10 −11 (cm 2 /s) at room temperature, which implies that sulfur modification will give rise to a higher Li ion carrier mobility and enhanced electrochemical performance

Synthesis and characterization of the novel rare earth orthophosphates Y0.5Er0.5PO4 and Y0.5Yb0.5PO4

International Nuclear Information System (INIS)

Schildhammer, Daniel; Petschnig, Lucas L.; Fuhrmann, Gerda; Heymann, Gunter; Schottenberger, Herwig; Huppertz, Hubert; Tribus, Martina

2016-01-01

The new mixed rare earth (RE) orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 were synthesized by a classical solid state reaction in an electrical furnace at 1200 C. As starting materials, the corresponding rare earth oxides and diammonium hydrogen phosphate were used. The powder diffraction analyses revealed that the new compounds Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in a zircon-type structure being isostructural with the rare earth orthophosphate YPO 4 . Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in the tetragonal space group I4 1 /amd (no. 141) with four formula units in the unit cell. The structural parameters based on Rietveld refinements are a = 687.27(2), c = 601.50(2) pm, V = 0.28412(1) nm 3 , R p = 0.0143, and R wp = 0.0186 (all data) for Y 0.5 Er 0.5 PO 4 and a = 684.61(2), c = 599.31(2) pm, V = 0.28089(2) nm 3 , R p = 0.0242, and R wp = 0.0313 (all data) for Y 0.5 Yb 0.5 PO 4 . Furthermore, the structure of Y 0.5 Er 0.5 PO 4 was refined from single-crystal X-ray diffraction data: a = 687.78(5), c = 601.85(4) pm, V = 0.28470(5) nm 3 , R 1 = 0.0165, and wR 2 = 0.0385 (all data). In both compounds, the rare earth metal ions are eightfold coordinated by oxygen atoms, forming two unique interlocking tetrahedra with two individual RE-O distances. The tetrahedral phosphate groups [PO 4 ] 3- are slightly distorted in both compounds. The individual rare earth ions share a common position (Wyckoff site 4a). The presence of two rare earth ions in the structures of the new orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 was additionally confirmed by single-crystal EDX spectroscopy revealing a ratio of 1:1.

Tissue pO2 of Orthotopic 9L and C6 Gliomas and Tumor-Specific Response to Radiotherapy and Hyperoxygenation

International Nuclear Information System (INIS)

Khan, Nadeem; Li Hongbin; Hou, Huagang; Lariviere, Jean P.; Gladstone, David J.; Demidenko, Eugene; Swartz, Harold M.

2009-01-01

Purpose: Tumor hypoxia is a well-known therapeutic problem; however, a lack of methods for repeated measurements of glioma partial pressure of oxygen (pO 2 ) limits the ability to optimize the therapeutic approaches. We report the effects of 9.3 Gy of radiation and carbogen inhalation on orthotopic 9L and C6 gliomas and on the contralateral brain pO 2 in rats using a new and potentially widely useful method, multisite in vivo electron paramagnetic resonance oximetry. Methods and Materials: Intracerebral 9L and C6 tumors were established in the left hemisphere of syngeneic rats, and electron paramagnetic resonance oximetry was successfully used for repeated tissue pO 2 measurements after 9.3 Gy of radiation and during carbogen breathing for 5 consecutive days. Results: Intracerebral 9L gliomas had a pO 2 of 30-32 mm Hg and C6 gliomas were relatively hypoxic, with a pO 2 of 12-14 mm Hg (p 2 of the contralateral brain was 40-45 mm Hg in rats with either 9L or C6 gliomas. Irradiation resulted in a significant increase in pO 2 of the 9L gliomas only. A significant increase in the pO 2 of the 9L and C6 gliomas was observed in rats breathing carbogen, but this effect decreased during 5 days of repeated experiments in the 9L gliomas. Conclusion: These results highlight the tumor-specific effect of radiation (9.3.Gy) on tissue pO 2 and the different responses to carbogen inhalation. The ability of electron paramagnetic resonance oximetry to provide direct repeated measurements of tissue pO 2 could have a vital role in understanding the dynamics of hypoxia during therapy that could then be optimized by scheduling doses at times of improved tumor oxygenation

Identification of longitudinal tissue pO2 gradients as one cause for vascular hypoxia in window chamber tumors

International Nuclear Information System (INIS)

Dewhirst, Mark W.; Ong, Edgardo T.; Braun, Rod D.; Evans, Sydney M.; Wilson, David

1997-01-01

resonance microangiography verified this orientation. PQI of the tumor surface indicated greater hypoxia with blue vs green light excitation (p<0.03 for 10th and 25th %tiles and for %pixels<10mmHg). Since green light penetrates more deeply than blue light, this suggests that the surface pO2 is lower than the pO2 within the tumor. In contrast, illumination of the fascial surface with blue light indicated less hypoxia compared with illumination of the tumor surface (p<0.05 for 10th and 25th %tiles and for %pixels<10mmHg). There was no significant difference between pO2 distribution data for blue and green light excitation from the fascial surface and there were no significant differences in pO2 distribution data for green light excitation when viewed from either surface. Conclusions: The PQI data suggest that the upper surface of the tumor is more hypoxic, since blue light excitation yields lower pO2 distributions than green light excitation. This is further verified in the subset of chambers where blue light excitation of the fascial surface showed higher pO2 distributions vs. the tumor surface. These results indicate that there are longitudinal gradients in vascular pO2 in this tumor model that are created by the orientation of the arteriolar input being constrained to one surface of the tumor. Arteriolar supply is often limited in other tumors as well, suggesting that this may be a common phenomenon. This is a contributing cause of tumor hypoxia that has not been previously reported

Les poèmes ragusains de Dejan Despic

OpenAIRE

Stefanović Ana

2005-01-01

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

Effect of carbon coating on cycle performance of LiFePO4/C composite cathodes using Tween80 as carbon source

International Nuclear Information System (INIS)

Huang, You-Guo; Zheng, Feng-Hua; Zhang, Xiao-Hui; Li, Qing-Yu; Wang, Hong-Qiang

2014-01-01

Highlights: • The Tween80 addition could enhance cycle stability of LiFePO 4 material. • The FTIR spectrum confirms Tween80 surfactant can bond with LiFePO 4 particles. • Some chemical bonds between material and carbon layer still exist after sintering. - Abstract: The influence of carbon coating on the cycle performance of LiFePO 4 /C composite cathodes using polyoxyethylenesorbitan monooleate (Tween80) as carbon source against lithium metal foil anode for Li-ion batteries was investigated in this paper. According to Infrared spectrum analysis (FTIR), the Tween80 surfactant molecules bond to the surface of LiFePO 4 and form an adsorption layer, which contribute to the formation of a homogeneous carbon layer tightly coating on the surface of LiFePO 4 particles in the process of sintering, due to a strong binding force provided by surface chemical bonds. The transmission electron microscopy (TEM) shows that the carbon layer around LiFePO 4 using Tween80 as carbon source still coating on the surface of LiFePO 4 after 200 cycles at 5 C rate while the carbon layer shed from the surface of LiFePO 4 using glucose as carbon source. As a result, the carbon-coated LiFePO 4 using Tween80 as carbon source exhibits much higher capacity retention than the sample using glucose as carbon source. Electrochemical impedance measurement (EIS) reveals that the carbon-coated LiFePO 4 electrode using Tween80 surfactant has a lower charge transfer resistance than the electrode using glucose as carbon source electrode after 100 and 200 cycles at 5 C rate

One-pot, facile fabrication of a Ag3PO4-based ternary Z-scheme photocatalyst with excellent visible-light photoactivity and anti-photocorrosion performance

Science.gov (United States)

Xie, Mingyuan; Zhang, Tailiang

2018-04-01

Ag3PO4 can-not be widely used as an efficient photocatalyst in practical applications because of its susceptibility to photocorrosion. In this study, a novel, ternary Z-scheme photocatalytic system containing graphene oxide (GO), Ag3PO4 and SnS2 was fabricated by a one-pot, mild, in-situ precipitation method successfully. Using Rhodamine B (RhB) as the target of elimination, GO/Ag3PO4/SnS2 exhibited outstanding photocatalytic and anti-photocorrosion properties compared with those of Ag3PO4, Ag3PO4/SnS2 and GO/Ag3PO4. RhB was thoroughly degraded over the optimized GO/Ag3PO4/SnS2 nanocomposite after only 15 min under visible-light irradiation; this result is approximately 2.14, 3.33 and 5.83 times faster than that of GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. After three reuses, the photocatalytic activity of the ternary composite slightly decreased but remained 2.36, 4.08 and 12.70 times higher than those of the reused GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. In this system, the efficient separation and migration of the photoinduced current carriers in Ag3PO4 was realized through a double Z-scheme electron-transfer mechanism in which the GO nanosheets acted as the photocatalyst and electron mediator, thereby enhancing the photoactivity and stability of Ag3PO4. The present study provides a new perspective for enhancing photocatalytic and anti-photocorrosion performances in perishable photocatalysts for organic sewage and other environmental contamination treatments.

The Normative Effects of Higher Education Policy in France

Science.gov (United States)

Langan, Elise

2012-01-01

This student survey was a response to the French youth unrest in 2005 and 2006. It considers the degree to which French higher and secondary education institutions create social cohesion. Focusing on three distinct higher-education institutions: "L'institut d'etudes politiques de Paris" (Sciences Po), "Ecole Normale…

Supervalent doping of LiFePO4 for enhanced electrochemical performance

Directory of Open Access Journals (Sweden)

N. V. Kosova

2015-12-01

Full Text Available The orthophosphates LiFe0.9M0.1PO4 with the structure of olivine doped with vanadium and titanium were obtained by mechanochemically stimulated solidphase synthesis using high-energy planetary mill AGO-2 and subsequent annealing at 750 °C. It is shown that V- and Ti- ions do not completely substitute for Fe2+ ions in the LiFePO4 structure. The remaining part of these ions involve in the formation of second phase with nashiko-like structure: monoclinic Li3V2(PO43 (space group P21/n and rhombohedral LiTi2(PO43 (space group R-3c. According to TEM, the average size of the particle of nanocomposites is about 100-300 nm. EMF of microanalysis showed that the small particles of secondary phases are segregated at the surface of larger particles of LiFePO4. On the charge-discharge curves of LiFe0.9M0.1PO4 there are plateau corresponding to LiFePO4 and the second phase. The doping with vanadium increases the resistance of the cycling of LiFePO4 and improves its cyclability at high speeds to a greater extent than in the case of doping with titanium.

Hypoxic Prostate/Muscle PO{sub 2} Ratio Predicts for Outcome in Patients With Localized Prostate Cancer: Long-Term Results

Energy Technology Data Exchange (ETDEWEB)

Turaka, Aruna [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Buyyounouski, Mark K., E-mail: mark.buyyounouski@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Hanlon, Alexandra L. [School of Nursing, University of Pennsylvania, Philadelphia, PA (United States); Horwitz, Eric M. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Greenberg, Richard E. [Department of Surgery, Fox Chase Cancer Center, Philadelphia, PA (United States); Movsas, Benjamin [Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI (United States)

2012-03-01

Purpose: To correlate tumor oxygenation status with long-term biochemical outcome after prostate brachytherapy. Methods and Materials: Custom-made Eppendorf PO{sub 2} microelectrodes were used to obtain PO{sub 2} measurements from the prostate (P), focused on positive biopsy locations, and normal muscle tissue (M), as a control. A total of 11,516 measurements were obtained in 57 men with localized prostate cancer immediately before prostate brachytherapy was given. The Eppendorf histograms provided the median PO{sub 2}, mean PO{sub 2}, and % <5 mm Hg or <10 mm Hg. Biochemical failure (BF) was defined using both the former American Society of Therapeutic Radiation Oncology (ASTRO) (three consecutive raises) and the current Phoenix (prostate-specific antigen nadir + 2 ng/mL) definitions. A Cox proportional hazards regression model evaluated the influence of hypoxia using the P/M mean PO{sub 2} ratio on BF. Results: With a median follow-up time of 8 years, 12 men had ASTRO BF and 8 had Phoenix BF. On multivariate analysis, P/M PO{sub 2} ratio <0.10 emerged as the only significant predictor of ASTRO BF (p = 0.043). Hormonal therapy (p = 0.015) and P/M PO{sub 2} ratio <0.10 (p = 0.046) emerged as the only independent predictors of the Phoenix BF. Kaplan-Meier freedom from BF for P/M ratio <0.10 vs. {>=}0.10 at 8 years for ASTRO BF was 46% vs. 78% (p = 0.03) and for the Phoenix BF was 66% vs. 83% (p = 0.02). Conclusions: Hypoxia in prostate cancer (low mean P/M PO{sub 2} ratio) significantly predicts for poor long-term biochemical outcome, suggesting that novel hypoxic strategies should be investigated.

Hydrothermal synthesis of LiFePO4 nanorods composed of ...

Indian Academy of Sciences (India)

Administrator

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

Electrochemical performance of LiFePO4 modified by pressure-pulsed chemical vapor infiltration in lithium-ion batteries

International Nuclear Information System (INIS)

Li Jianling; Suzuki, Tomohiro; Naga, Kazuhisa; Ohzawa, Yoshimi; Nakajima, Tsuyoshi

2007-01-01

Using the pressure-pulsed chemical vapor infiltration (PCVI) technique, pyrolytic carbon (pyrocarbon) films were deposited on the surface of LiFePO 4 particles for cathode material of lithium-ion batteries. The electrochemical performance of the original LiFePO 4 and PCVIed LiFePO 4 materials was evaluated using a three electrodes cell by galvanostatic charging/discharging at 25, 40 and 55 deg. C, respectively. Morphology and structure of LiFePO 4 were analyzed by SEM, XRD and Raman. The resulting carbon contents at 500, 1000, 2000, 3000 and 5000 pulses were 2.7, 4.7, 9.5, 15.1 and 19.4%, respectively and these samples were abbreviated as 500P, 1000P, 2000P, 3000P and 5000P, respectively. All the PCVIed samples exhibited excellent rate performance. The tendency was more and more obvious with the increase of the current densities. The specific capacities of 500P, 1000P and 2000P were maintained at 117, 124 and 132 mAh g -1 , respectively, which were 120.8, 264.7 and 29.47% larger than those of corresponding original LiFePO 4 , respectively, at a 5C rate at 55 deg. C. The EIS measurement showed that electrochemical reaction resistance (R ct ) of PCVIed LiFePO 4 were obviously decreased, indicating a fast kinetics compared to the original LiFePO 4 . The cycle ability of the 2000P sample was tested at 25 deg. C and C/2 rate. The cell was cycled for 150 cycles and no obviously capacity fade was observed. Its specific capacity of 115 mAh g -1 at 150th cycle is 1.7 times higher than that of original LiFePO 4

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

Science.gov (United States)

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

1986-01-01

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

The Contrasting Effects of Alum-Treated Chicken Manures and KH2PO4 on Phosphorus Behavior in Soils.

Science.gov (United States)

Huang, Lidong; Yang, Junming; Xu, Yuting; Lei, Jiayan; Luo, Xiaoshan; Cade-Menun, Barbara J

2018-03-01

Alum [KAl(SO)⋅12HO] is often added to chicken manure to limit P solubility after land application. This is generally ascribed to the formation of Al-PO complexes. However, Al-PO complex formation could be affected by the matrix of chicken manure, which varies with animal diet. Alum was added to KHPO (as a reference material) and two manures from typical chicken farms in China, one from an intensive farm (CMIF) and another from free-ranging chickens (CMFR). These were subsequently incubated with soils for 100 d to investigate P transformations. Alum reduced water-soluble colorimetrically reactive phosphorus (RP) from soils amended with manure more effectively than in soils amended with KHPO. Alum addition lowered Mehlich-3 RP in soils with CMFR but had no influence on Mehlich-3 RP in CMIF- or KHPO-amended soils. A comparison of P in digested Mehlich-3 extracts with RP in undigested samples showed significantly increased P in digests of alum-treated CMFR only. Fractionation data indicated that alum treatment increased P in the NHF-RP (Al-P) fraction only in soils with KHPO, but not in soils with manure treatments. Furthermore, NaOH-extracted nonreactive P was markedly higher in soil with alum-treated CMFR relative to normal CMFR. The CMFR manure was assumed to contain higher concentrations of organic P because these chickens were fed grains only. These results suggest that the formation of alum-organic P complexes may reduce P solubility. By comparing alum-treated KHPO and manures, it appears that organic matter in manure could interfere with the formation of Al-PO complexes. Copyright © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and AgriFood Canada.

Biological effect on removal of Th-234, Po-210 and Pb-210 from surface water in Funka Bay, Japan

Energy Technology Data Exchange (ETDEWEB)

Tanaka, N; Takeda, Y; Tsunogai, S [Hokkaido Univ., Hakodate (Japan). Dept. of Chemistry

1983-10-01

Vertical and temporal variations in the radioactivities of Th-234, Pb-210 and Po-210 were measured at a station in Funka Bay from April 1979 to February 1980. The inventory of Th-234 showed a minimum in early spring, when a spring bloom of phytoplankton was observed, then a steady increase to a maximum value in late summer, just before open sea water invaded the bay and a secondary phytoplankton bloom started. The inventories of Pb-210 and Po-210 also showed minima in early spring. These results suggest that the removal of these nuclides from sea water is accelerated by biological activity. The concentration of Th-234 decreased with depth, but those of Po-210 and Pb-210 were higher in the bottom water in August 1979 when the bay water was strongly stratified. This may be due to the supply of Pb-210 and Po-210 from the bottom. However, if the supply of these nuclides is expected in sediment particles, the concentrations of these nuclides in suspended matter were not sufficient to explain their increments in the bottom water. Residence times of Th, Pb and Po were estimated.

Biological reduction-deposition and luminescent properties of nanostructured CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaoniu [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Research Institute of Green Construction Materials, Southeast University, Nanjing 211189 (China); Qian, Chunxiang, E-mail: cxqian@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Research Institute of Green Construction Materials, Southeast University, Nanjing 211189 (China)

2016-03-01

Nano-sized CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} with hexagonal phase have been prepared by simply varying the reactant P/Ce molar ratio in bacterial liquid. The phase composition of two samples was checked via Fourier transform infrared spectroscopy (FTIR), energy dispersive analysis of X-rays (EDS) and X-ray diffraction (XRD) analyses, displaying the presence of CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} with average crystallite size are 32.34 and 15.61 nm, respectively. The scanning electron microscopy (SEM) images show that nano-clusters and sphere-like in shape with a narrow diameter distribution were observed in two samples. The transmission electron microscopy (TEM) photographs further indicate obtained CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} nanoparticles correspond to nanosheets and nanorods, respectively. The emission spectra of CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} display a broad band of 300–380 nm range with the strongest emission at 342 nm in the violet region. - Highlights: • A new method was found to synthesize CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) and CePO{sub 4} nanoparticles. • CePO{sub 4}@NaCe(SO{sub 4}){sub 2}(H{sub 2}O) nanoparticles have good luminescent properties. • Size and luminescent properties of two samples have been studied and compared.

The CeO{sub 2}/Ag{sub 3}PO{sub 4} photocatalyst with stability and high photocatalytic activity under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Song, Yanhua [School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Zhao, Haozhu; Chen, Zhigang; Huang, Liying; Xu, Hui; Li, Huaming [School of the Environment, Institute for Energy Research, Jiangsu University, Zhenjiang, 212013 (China); Wang, Weiren [Department of Chemistry, Rice University, Houston, Texas, 77005 (United States)

2016-09-15

The CeO{sub 2}/Ag{sub 3}PO{sub 4} composite photocatalysts are synthesized by an in situ precipitation method. The XRD, FT-IR, XPS, TEM, EDS, and DRS are used to characterize the structure of the samples. The photocatalytic performance of the prepared samples is evaluated by the photocatalytic degradation of methylene blue (MB), rhodamine B (RhB), and ciprofloxacin (CIP). The results show that CeO{sub 2}/Ag{sub 3}PO{sub 4} hybrid materials exhibit much higher photocatalytic activity than the Ag{sub 3}PO{sub 4} alone. The optimal CeO{sub 2} content in CeO{sub 2}/Ag{sub 3}PO{sub 4} composites is found to be molar ratio 1 wt%. Photocurrent response of CeO{sub 2}/Ag{sub 3}PO{sub 4} (1 wt%) is about 1.5 times as high as that of the pure Ag{sub 3}PO{sub 4}. The increase of photocatalytic activity of CeO{sub 2}/Ag{sub 3}PO{sub 4} composites could be mainly attributed to the heterojunction between CeO{sub 2} and Ag{sub 3}PO{sub 4}. The trapping experiment has demonstrated that holes serve as the main active species for the degradation of MB under visible light irradiation. A photocatalytic mechanism is also proposed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Hanford 100N Area Apatite Emplacement: Laboratory Results of Ca-Citrate-PO4 Solution Injection and Sr-90 Immobilization in 100N Sediments

Energy Technology Data Exchange (ETDEWEB)

Szecsody, James E.; Burns, Carolyn A.; Moore, Robert C.; Fruchter, Jonathan S.; Vermeul, Vincent R.; Williams, Mark D.; Girvin, Donald C.; McKinley, James P.; Truex, Michael J.; Phillips, Jerry L.

2007-10-01

, and PO4 solutions show greater Sr and Sr-90 incorporation during initial precipitation and less initial mobilization with solutions with low Ca2+ concentration. While all solutions showed nearly the same Sr uptake into apatite (14 to 17% by 2 weeks, 21% to 30% by 5 weeks), the incorporation efficiency (i.e., mM Sr incorporated per mM PO4 injected) was higher for solutions containing citrate. The Sr incorporation rate into apatite during initial precipitation (by 1 month) averaged 4.64 ± 1.9 x 10-4 h-1 (half-life 1500 ± 430 h, 8.85 x 10-7 mg Sr/day/mg apatite). The injection solution used in field injections #3 to #18 (10 mM PO4, 1 mM Ca, 2.5 mM citrate), which is deficient in Ca (a total of 16.7 mM needed to form apatite with 10 mM of PO4), resulted in the initial Sr and Ca peak (24 h) at 4.7x groundwater. By 30 days, the aqueous Sr concentration was 0.28x groundwater and Ca 0.43x groundwater, as both Sr and Ca are used to form initial apatite precipitates. Reactive transport simulation of the complex ion exchange, biodegradation, and precipitation processes showed that the initial Sr groundwater increase mobilized only 1.5% of the Sr mass in sediments. Citrate biodegradation, a necessary step in Ca-citrate-PO4 solutions forming apatite, had an average half-life of 50 h (at aquifer sediment/water ratio and temperature), and decreased an order of magnitude with sediment depth as the microbial biomass decreased five orders of magnitude. The rate of citrate biodegradation was relatively invariant with biomass and water saturation (50% to 100%, for vadose zone infiltration) possibly due to significant microbial injection using river water and subsurface microbial mobilization.

Degradation Studies on LiFePO₄ cathode

DEFF Research Database (Denmark)

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

2015-01-01

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

Doticaj moderne kozmologije i religije: poimanje početka svemira

OpenAIRE

Petković, Tomislav

2007-01-01

Ujedinjenje velikih teorija fizike − teorije relativnosti, kvantne mehanike i fizike svemira i čestica − ostaje snom fizike i filozofije znanosti i na početku 21. stoljeća. Sve se one u pogledu konačnih zakona svemira (teorija svega) slažu da je početak bio, te da su konačni zakoni oni koji su već vladali u početku evolucije svemira. Početak svemira podrazumijeva njegovo stvaranje i nužno upućuje na Stvoritelja−religijskog Boga, na uspostavljanje mosta između moderne kozmologije i religije. U...

Synthesis and electrochemical properties of xLiMn0.9Fe0.1PO4·yLi3V2(PO4)3/C composite cathode materials for lithium–ion batteries

International Nuclear Information System (INIS)

Wu, Ling; Lu, JiaJia; Wei, Gui; Wang, Pengfei; Ding, Hao; Zheng, Junwei; Li, Xiaowei; Zhong, Shengkui

2014-01-01

Highlights: • xLiMn 0.9 Fe 0.1 PO4·yLi 3 V 2 (PO 4 ) 3 /C composites are prepared by a solid-state method. • The addition of Li 3 V 2 (PO 4 ) 3 can improve the properties of LiMn 0.9 Fe 0.1 PO 4 . • Mutual doping occurrs between the LiMn 0.9 Fe 0.1 PO 4 and Li 3 V 2 (PO 4 ) 3 phases. • 5LiMn 0.9 Fe 0.1 PO 4 ·Li 3 V 2 (PO 4 ) 3 /C shows the best electrochemical properties. - Abstract: The xLiMn 0.9 Fe 0.1 PO 4 ·yLi 3 V 2 (PO 4 ) 3 /C (x:y=1:0, 9:1 5:1, 3:1, 1:1 and 0:1) cathode materials are synthesized by a ball–milling and post–calcination method. XRD results reveal that the xLiMn 0.9 Fe 0.1 PO 4 ·yLi 3 V 2 (PO 4 ) 3 /C (x,y≠0) composites are composed of LiMn 0.9 Fe 0.1 PO 4 and Li 3 V 2 (PO 4 ) 3 phases, and no impurities are detected. In LiMn 0.9 Fe 0.1 PO 4 –Li 3 V 2 (PO 4 ) 3 system, most of the manganese, iron and vanadium elements in the raw materials tend to form the two major phases, and only small amounts of V, Mn and Fe as dopants enter into the lattice of LiMn 0.9 Fe 0.1 PO 4 and Li 3 V 2 (PO 4 ) 3 . Electrochemical tests show that the xLiMn 0.9 Fe 0.1 PO 4 ·yLi 3 V 2 (PO 4 ) 3 /C (x,y≠0) composites exhibit much better performance than the single LiMn 0.9 Fe 0.1 PO 4 /C. Among the samples, 5LiMn 0.9 Fe 0.1 PO 4 ·Li 3 V 2 (PO 4 ) 3 /C shows the best electrochemical performance. The sample delivers the specific capacities of 158.1, 140.7 and 100.2 mAh g −1 at 0.05, 1 and 4 C rates in the potential range of 2.5–4.5 V, and exhibits very long and flat discharge plateau around 4.0 V up to 1 C rate. The sample also shows good cycling performance at various C–rates

Visible-light-driven TiO2/Ag3PO4/GO heterostructure photocatalyst with dual-channel for photo-generated charges separation

International Nuclear Information System (INIS)

Lu, Bingqing; Ma, Ni; Wang, Yaping; Qiu, Yiwei; Hu, Haihua; Zhao, Jiahuan; Liang, Dayu; Xu, Sheng; Li, Xiaoyun; Zhu, Zhiyan; Cui, Can

2015-01-01

Highlights: • TiO 2 /Ag 3 PO 4 /GO was synthesized with a facile two-step method. • TiO 2 /Ag 3 PO 4 /GO exhibit superior photocatalytic activity and stability. • TiO 2 /Ag 3 PO 4 /GO has dual-channel for photo-generated charges separation. • TiO 2 /Ag 3 PO 4 /GO composite reduces the consumption of Ag. - Abstract: A novel triple-component TiO 2 /Ag 3 PO 4 /graphene oxide (TiO 2 /Ag 3 PO 4 /GO) photocatalyst with dual channels for photo-generated charges separation has been synthesized to improve the photocatalytic activity and stability of Ag 3 PO 4 under visible light. The synthesis involved in-situ growth of Ag 3 PO 4 nanoparticles on GO sheets to form Ag 3 PO 4 /GO, and then deposited TiO 2 nanocrystals on the surface of Ag 3 PO 4 by hydrolysis of Ti(SO 4 ) 2 at low-temperature hydrothermal condition. The TiO 2 /Ag 3 PO 4 /GO exhibited superior photocatalytic activity and stability to bare Ag 3 PO 4 , TiO 2 /Ag 3 PO 4 and Ag 3 PO 4 /GO in degradation of Rhodamine B and phenol solutions under visible light. It is suggested that the photo-generated electrons in the conduction band of Ag 3 PO 4 can be quickly transferred to GO, while the holes in the valence band of Ag 3 PO 4 can be transferred to the valence band of TiO 2 . The dual transfer channels at the interfaces of TiO 2 /Ag 3 PO 4 /GO result in effective charges separation, leading to enhanced photocatalytic activity and stability. Furthermore, the content of noble metal Ag significantly reduces from 77 wt% in bare Ag 3 PO 4 to 55 wt% in the nanocomposite. The concept of establishing dual channels for charges separation in a triple-component heterostructure provides a promising way to develop photocatalysts with high efficiency

A novel Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} photocatalyst with high photocatalytic activity and enhancement mechanism

Energy Technology Data Exchange (ETDEWEB)

Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Chen, Zewen; Li, Tongtong [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Shujuan, E-mail: zhangshujuan@tust.edu.cn [College of Science, Tianjin University of Science & Technology, Tianjin, 300457 (China)

2017-01-15

Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} (Ni{sup 2+}-Ag{sub 3}PO{sub 4}) photocatalysts with superhigh activity for photodegradation of organic pollutants were prepared by a simple hydrothermal method. The photocatalysts were characterized with X-ray powder diffractometry, transmission electron microscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. The photocatalysts were evaluated by methyl orange (MO) photodegradation experiments under visible light irradiation (λ > 420 nm). Comparative analysis showed the optimal doping dosage was 0.05 mol/L Ni{sup 2+}. The optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} has an MO photodegradation rate constant four times larger than pure Ag{sub 3}PO{sub 4}. The photocatalytic ratio of 40 mg/L MO over the optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} after 10 min is 89%, which indicates excellent photocatalytic ability in high-concentration MO solutions. The Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} can increase the level of band gap, and accelerate the utilization of photons and the separation of photo-generated charges. Therefore, the Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} is responsible for the enhancement of photocatalytic ability. - Highlights: • Ni{sup 2+}-modified with higher photodegradation ability was synthesized. • ·OH radicals were the main active species in the oxidation of MO. • The doping of Ni{sup 2+} in Ag{sub 3}PO{sub 4} is responsible for the enhanced activity.

Antagonistic effects of copper on the electrochemical performance of LiFePO4

International Nuclear Information System (INIS)

Morales, Julian; Santos-Pena, Jesus; Rodriguez-Castellon, Enrique; Franger, Sylvain

2007-01-01

In the last few years, several strategies towards boosting the electrochemical performance of LiFePO 4 cathodes have been envisaged. Copper addition to the phosphate seems to be a simple, inexpensive method for this purpose. However, it has a serious drawback: at voltages slightly higher than that required for lithium extraction from LiFePO 4 , the copper is oxidized to either Cu(I) or Cu(II) with partial decomposition of the electrolyte. XRD patterns are consistent with the disappearance of copper from pristine composites upon charging at up to 4.0 V. Moreover, a copper deposit is formed on the lithium surface in the discharged state that creates a barrier hindering the release of Li ion from the electrode. Therefore, copper electroactivity strongly influences the capacity and cycling life of the cell

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

Energy Technology Data Exchange (ETDEWEB)

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

1991-12-15

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

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

Science.gov (United States)

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

2018-05-01

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

Investigations of the potential bioavailability of 210Po in some foodstuffs

International Nuclear Information System (INIS)

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

1995-01-01

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

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

International Nuclear Information System (INIS)

Godoy, J.M.; Schuettelkopf, H.

1980-07-01

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

Bioaccumulation of "2"1"0Po and "2"1"0Pb in the crustaceans of Pichavaram mangrove ecosystem, Tamil nadu, India

International Nuclear Information System (INIS)

Raja, P.; Shahul Hameed, P.

2017-01-01

It was observed that the concentrations of "2"1"0Po in water and sediment were 1.64mBq/l and 5.92 Bq/kg and "2"1"0Pb in water and sediment samples 3.10 mBq/l and 2.45 Bq/kg respectively. The muscle of crabs registered a higher level of "2"1"0Po (152 Bq/kg) than that of prawns (71.87 Bq/kg) and lobster (49.3Bq/kg). Conversely the exoskeleton of crustacean species analyzed, accumulated a higher level of "2"1"0Pb (range 5.7-9.11 Bq/kg) as compared to level of accumulated "2"1"0Pb in muscle (range 1.62-2.54 Bq/kg). The study reveals the base line data on the levels of naturally occurring radionuclides such as "2"1"0Po and "2"1"0Pb in the prestart environment of Pichavaram Mangrove Ecosystem with special reference to the crustaceans. (author)

Accumulation of 210Po by benthic marine algae

International Nuclear Information System (INIS)

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

1988-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-01

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

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

Science.gov (United States)

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

2012-01-01

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

Unusually large 210Po deficiencies relative to 210Pb in the Kuroshio Current of the East China and Philippine seas

International Nuclear Information System (INIS)

Yoshiyuki Nozaki; Naoko Ikuta; Mayumi Yashima

1990-01-01

Three vertical water profiles of 210 Pb and 210 Po have been measured in the East China and Philippine seas. All the profiles show a large 210 Po deficiency of ∼ 8 dpm/cm 2 relative to 210 Pb in the top ∼ 1,000 m of the water column. Based on the 210 Po deficiency, the steady state flux for 210 Po removal from the surface water is estimated to be 14 dpm cm -2 /yr. The 210 Po/ 210 Pb ratio of sinking particles will be too high unless an additional source of 210 Pb into the surface is accounted for. Thus the large 210 Po deficit is probably caused by the increased atmospheric input of 210 Pb without any significant 210 Po, which is focused in the Kuroshio region by isopycnal transport, and the preferential scavenging of 210 Po relative to 210 Pb by settling particles. The transient model calculations indicate that the model can account for the observed high excess 210 Pb inventory and large 210 Po deficiency in the water column if focusing of atmospherically derived 210 Pb in the Kuroshio water is a factor of 2-3 more than the local input. Such lateral redistribution by the western North Pacific gyre circulation is not inconsistent with the deeper penetration and the high water column inventories of anthropogenic substances observed in this region

Measurements of Po214 at Sao Jose dos Campos and Cachoeira Paulista: correlation with meteorological data

International Nuclear Information System (INIS)

Marinho, E.V.A.; Nordemann, D.J.R.

1985-01-01

PO 214 , a short life daughter product of RN 222 , was measured by alpha-ray spectrometry of a atmospheric particles sampled on Millipore filters (0.8 μm pore) at Sao Jose dos Campos (23 0 12'S, 45 0 51'W) and Cachoeira Paulista (22 0 41'S, 45 0 00'W). The infleunce of rainfall on the atmospheric Po 214 was studied at Sao Jose dos Campos. The mean activity was 98 pCi/m 3 for dry days (without rain during the preceding two days). On the contrary a low mean activity of 35 pCi/m 3 was observed for high pluviometry days from 08/30 to 10/26 for which total rainfall was 365.5 mm. At Cachoeria Paulista the Po 214 activity was correlated with the stability of the air (measured by the Richardson number), showing an accumaltion of natural radioactive aerosols during periods of higher stability of the lower atmosphere. (author) [pt

Insights into highly improved solar-driven photocatalytic oxygen evolution over integrated Ag3PO4/MoS2 heterostructures

Science.gov (United States)

Cui, Xingkai; Yang, Xiaofei; Xian, Xiaozhai; Tian, Lin; Tang, Hua; Liu, Qinqin

2018-04-01

Oxygen evolution has been considered as the rate-determining step in photocatalytic water splitting due to its sluggish four-electron half-reaction rate, the development of oxygen-evolving photocatalysts with well-defined morphologies and superior interfacial contact is highly important for achieving high-performance solar water splitting. Herein, we report the fabrication of Ag3PO4/MoS2 nanocomposites and, for the first time, their use in photocatalytic water splitting into oxygen under LED light illumination. Ag3PO4 nanoparticles were found to be anchored evenly on the surface of MoS2 nanosheets, confirming an efficient hybridization of two semiconductor materials. A maximum oxygen-generating rate of 201.6 mol L-1 g-1 h-1 was determined when 200 mg MoS2 nanosheets were incorporated into Ag3PO4 nanoparticles, which is around 5 times higher than that of bulk Ag3PO4. Obvious enhancements in light-harvesting property, as well as electron-hole separation and charge transportation are revealed by the combination of different characterizations. ESR analysis verified that more active oxygen-containing radicals generate over illuminated Ag3PO4/MoS2 composite photocatalysts rather than irradiated Ag3PO4. The improvement in oxygen evolution performance of Ag3PO4/MoS2 composite photocatalysts is ascribed to wide spectra response in the visible-light region, more efficient charge separation and enhanced oxidation capacity in the valence band (VB). This study provides new insights into the design and development of novel composite photocatalytic materials for solar-to-fuel conversion.

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

International Nuclear Information System (INIS)

Nogaj, A.S.

2002-01-01

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

Electrochemical characterization of LiFePO{sub 4}/poly (sodium 4-styrenesulfonate)-multi walled carbon nanotube composite cathode material for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Van Hiep; Wang, Wan Lin; Jin, En Mei; Gu, Hal-Bon, E-mail: hbgu@chonnam.ac.kr

2013-08-25

Highlights: •LiFePO{sub 4}/PSS–MWCNT successfully prepared by a hydrothermal method. •LiFePO{sub 4}/PSS(2.5%)–MWCNT(2.5%) shows the best electrochemical performances. •PSS stacks and forms a layer about 3–6 nm around the surface of LiFePO{sub 4} particles. •The electronic conductivity of LiFePO{sub 4}/PSS(2.5%)–MWCNT(2.5%) is 6.3 × 10{sup −3} S cm{sup −1}. -- Abstract: LiFePO{sub 4} is a promising cathode material for lithium ion batteries and is prepared by a hydrothermal method. However, its practical application is limited due to its poor conductivity. In order to improve the electronic conductivity, we added poly (sodium 4-styrenesulfonate) (PSS) and multi walled carbon nanotube (MWCNT) in LiFePO{sub 4}. In the results, PSS stacks and forms a layer about 3–6 nm around the surface of LiFePO{sub 4} particles. MWCNT provides pathways for electron transport. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic discharge testing results indicate that LiFePO{sub 4}/PSS–MWCNT composite exhibits higher discharge capacity than pure LiFePO{sub 4}. LiFePO{sub 4}/PSS(2.5%)–MWCNT(2.5%) shows the best discharge capacity of 144 mAh g{sup −1} at 2nd cycle, and high electronic conductivity of 6.3 × 10{sup −3} S cm{sup −1}.

Rate-induced solubility and suppression of the first-order phase transition in olivine LiFePO4.

Science.gov (United States)

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P; Brownrigg, Alex; Wright, Jonathan P; van Dijk, Niels H; Wagemaker, Marnix

2014-05-14

The impact of ultrahigh (dis)charge rates on the phase transition mechanism in LiFePO4 Li-ion electrodes is revealed by in situ synchrotron diffraction. At high rates the solubility limits in both phases increase dramatically, causing a fraction of the electrode to bypass the first-order phase transition. The small transforming fraction demonstrates that nucleation rates are consequently not limiting the transformation rate. In combination with the small fraction of the electrode that transforms at high rates, this indicates that higher performances may be achieved by further optimizing the ionic/electronic transport in LiFePO4 electrodes.

Improvement on high rate performance of LiFePO4 cathodes using graphene as a conductive agent

Science.gov (United States)

Wei, Xufang; Guan, Yibiao; Zheng, Xiaohui; Zhu, Qizhen; Shen, Jinran; Qiao, Ning; Zhou, Shuqin; Xu, Bin

2018-05-01

In this work, the electrochemical properties of the LiFePO4 cathode using graphene as a conductive agent were revealed. Compared to the conventional LiFePO4 electrodes with carbon black as a conductive agent, the graphene sheets can establish a more effective conductive framework due to their layered structure and excellent electronic conductivity, leading to better electrochemical rate performance. Furthermore, the obverse of increasing graphene content is continued gains in high-rate performance of the LiFePO4 electrodes. The electrodes with 30 wt% graphene show high capacities up to 103.1 mA h g-1 and 68 mA h g-1 during discharging with extremely high rates of 30 C and 50 C, respectively. Besides, good cycling performance at high rate is also achieved. The electrodes with 30 wt% graphene display a capacity retention higher than 80% after 1000 cycles at 30 C. These results not only indicate that the graphene could be a promising candidate as a conductive agent, but also provide a new insight for designing LiFePO4 electrodes with brilliant high-rate performance via a simple method.

Synthesis of spherical LiMnPO4/C composite microparticles

International Nuclear Information System (INIS)

Bakenov, Zhumabay; Taniguchi, Izumi

2011-01-01

Highlights: → We could prepare LiMnPO 4 /C composites by a novel preparation method. → The LiMnPO 4 /C composites were spherical particles with a mean diameter of 3.65 μm. → The LiMnPO 4 /C composite cathode exhibited 112 mAh g -1 at 0.05 C. → It also showed a good rate capability up to 5 C at room temperature and 55 o C. -- Abstract: Spherical LiMnPO 4 /C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO 4 /C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was identified as a single phase orthorhombic structure of LiMnPO 4 and spherical powders with a geometric mean diameter of 3.65 μm and a geometric standard deviation of 1.34. The electrochemical cells contained the spherical LiMnPO 4 /C microparticles exhibited first discharge capacities of 112 and 130 mAh g -1 at 0.05 C at room temperature and 55 o C, respectively. These also showed a good rate capability up to 5 C at room temperature and 55 o C.

Infrared-active optical phonons in LiFePO4 single crystals

Science.gov (United States)

Stanislavchuk, T. N.; Middlemiss, D. S.; Syzdek, J. S.; Janssen, Y.; Basistyy, R.; Sirenko, A. A.; Khalifah, P. G.; Grey, C. P.; Kostecki, R.

2017-07-01

Infrared-active optical phonons were studied in olivine LiFePO4 oriented single crystals by means of both rotating analyzer and rotating compensator spectroscopic ellipsometry in the spectral range between 50 and 1400 cm-1. The eigenfrequencies, oscillator strengths, and broadenings of the phonon modes were determined from fits of the anisotropic harmonic oscillator model to the data. Optical phonons in a heterosite FePO4 crystal were measured from the delithiated ab-surface of the LiFePO4 crystal and compared with the phonon modes of the latter. Good agreement was found between experimental data and the results of solid-state hybrid density functional theory calculations for the phonon modes in both LiFePO4 and FePO4.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Interstitial pO2 in ischemic penumbra and core are differentially affected following transient focal cerebral ischemia in rats.

Science.gov (United States)

Liu, Shimin; Shi, Honglian; Liu, Wenlan; Furuichi, Takamitsu; Timmins, Graham S; Liu, Ke Jian

2004-03-01

Stroke causes heterogeneous changes in tissue oxygenation, with a region of decreased blood flow, the penumbra, surrounding a severely damaged ischemic core. Treatment of acute ischemic stroke aims to save this penumbra before its irreversible damage by continued ischemia. However, effective treatment remains elusive due to incomplete understanding of processes leading to penumbral death. While oxygenation is central in ischemic neuronal death, it is unclear exactly what actual changes occur in interstitial oxygen tension (pO2) in ischemic regions during stroke, particularly the penumbra. Using the unique capability of in vivo electron paramagnetic resonance (EPR) oximetry to measure localized interstitial pO2, we measured both absolute values, and temporal changes of pO2 in ischemic penumbra and core during ischemia and reperfusion in a rat model. Ischemia rapidly decreased interstitial pO2 to 32% +/- 7.6% and 4% +/- 0.6% of pre-ischemic values in penumbra and core, respectively 1 hour after ischemia. Importantly, whilst reperfusion restored core pO2 close to its pre-ischemic value, penumbral pO2 only partially recovered. Hyperoxic treatment significantly increased penumbral pO2 during ischemia, but not in the core, and also increased penumbral pO2 during reperfusion. These divergent, important changes in pO2 in penumbra and core were explained by combined differences in cellular oxygen consumption rates and microcirculation conditions. We therefore demonstrate that interstitial pO2 in penumbra and core is differentially affected during ischemia and reperfusion, providing new insights to the pathophysiology of stroke. The results support normobaric hyperoxia as a potential early intervention to save penumbral tissue in acute ischemic stroke.

Electrochemical performance of LiFePO{sub 4} modified by pressure-pulsed chemical vapor infiltration in lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Li Jianling [Department of Physical Chemistry, University of Science and Technology Beijing, No. 30 College Road, Haidian District, Beijing 100083 (China); Department of Applied Chemistry, Aichi Institute of Technology, Yachigusa 1247, Yakusa-cho, Toyota 470-0392 (Japan)], E-mail: lijianling@metall.ustb.edu.cn; Suzuki, Tomohiro; Naga, Kazuhisa; Ohzawa, Yoshimi; Nakajima, Tsuyoshi [Department of Applied Chemistry, Aichi Institute of Technology, Yachigusa 1247, Yakusa-cho, Toyota 470-0392 (Japan)

2007-09-25

Using the pressure-pulsed chemical vapor infiltration (PCVI) technique, pyrolytic carbon (pyrocarbon) films were deposited on the surface of LiFePO{sub 4} particles for cathode material of lithium-ion batteries. The electrochemical performance of the original LiFePO{sub 4} and PCVIed LiFePO{sub 4} materials was evaluated using a three electrodes cell by galvanostatic charging/discharging at 25, 40 and 55 deg. C, respectively. Morphology and structure of LiFePO{sub 4} were analyzed by SEM, XRD and Raman. The resulting carbon contents at 500, 1000, 2000, 3000 and 5000 pulses were 2.7, 4.7, 9.5, 15.1 and 19.4%, respectively and these samples were abbreviated as 500P, 1000P, 2000P, 3000P and 5000P, respectively. All the PCVIed samples exhibited excellent rate performance. The tendency was more and more obvious with the increase of the current densities. The specific capacities of 500P, 1000P and 2000P were maintained at 117, 124 and 132 mAh g{sup -1}, respectively, which were 120.8, 264.7 and 29.47% larger than those of corresponding original LiFePO{sub 4}, respectively, at a 5C rate at 55 deg. C. The EIS measurement showed that electrochemical reaction resistance (R{sub ct}) of PCVIed LiFePO{sub 4} were obviously decreased, indicating a fast kinetics compared to the original LiFePO{sub 4}. The cycle ability of the 2000P sample was tested at 25 deg. C and C/2 rate. The cell was cycled for 150 cycles and no obviously capacity fade was observed. Its specific capacity of 115 mAh g{sup -1} at 150th cycle is 1.7 times higher than that of original LiFePO{sub 4}.

Spirit Pluralisme dalam Klenteng Sam Po Kong Semarang

Directory of Open Access Journals (Sweden)

Edi Nurwahyu Julianto

2015-07-01

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

210Po and 210Pb concentration of cigarettes traded in Hungary and their estimated dose contribution due to smoking

International Nuclear Information System (INIS)

Kovacs, Tibor; Somlai, Janos; Nagy, Katalin; Szeiler, Gabor

2007-01-01

It is known that tobacco leaves may contain 210 Pb and 210 Po in significant concentrations. The cumulative alpha-radiation dose due to the radioactive content of inhaled cigarette smoke and the increasing number of lung cancer cases explain the importance of the investigation. The present study investigated the activity concentrations of these two radionuclides in 29 Hungarian cigarette samples. The relation between 210 Po/ 210 Pb activity and nicotine/tar content of these cigarettes was also examined. 210 Po was determined by alpha spectrometry using a PIPS detector after chemical leaching and spontaneous deposition of 210 Po on a high nickel-content (25%) stainless steel disk. The 210 Pb activity was calculated from the 210 Po originated from the decay of 210 Pb after a waiting period of eight months. The 210 Po activity concentrations of the measured types of cigarettes ranged from 10.0 to 33.5 mBq/cigarette, and the activity of 210 Pb varied from 9.6 to 32.5 mBq/cigarette. The average annual committed effective dose is estimated to be 185.6±70.6μSv/y and 58.7±22.7μSv/y due to cigarette smoking (20 cigarettes/day) for 210 Po and 210 Pb, respectively

Luminescence and scintillation properties of LuPO4-Ce nanoparticles

International Nuclear Information System (INIS)

Vistovskyy, V.; Malyy, T.; Pushak, A.; Vas’kiv, A.; Shapoval, A.; Mitina, N.; Gektin, A.; Zaichenko, A.; Voloshinovskii, A.

2014-01-01

Study of the spectral-luminescence parameters of LuPO 4 -Ce nanoparticles upon the excitation by X-ray quanta and synchrotron radiation with photon energies of 4–25 eV was performed. Nanoparticles with mean size about a=35 nm and nanoparticles with size less than 12 nm reveal the different structures of cerium centers. Luminescence efficiency of LuPO 4 -Ce nanoparticles of a 4 -Ce nanoparticles studied using synchrotron and X-ray excitation. • Different structure of Ce 3+ -centers has been revealed for LuPO 4 -Ce nanoparticles. • Luminescence of LuPO 4 -Ce with size less than 12 nm is strongly quenched upon the X-ray excitation

Noninvasive, near infrared spectroscopic-measured muscle pH and PO2 indicate tissue perfusion for cardiac surgical patients undergoing cardiopulmonary bypass

Science.gov (United States)

Soller, Babs R.; Idwasi, Patrick O.; Balaguer, Jorge; Levin, Steven; Simsir, Sinan A.; Vander Salm, Thomas J.; Collette, Helen; Heard, Stephen O.

2003-01-01

OBJECTIVE: To determine whether near infrared spectroscopic measurement of tissue pH and Po2 has sufficient accuracy to assess variation in tissue perfusion resulting from changes in blood pressure and metabolic demand during cardiopulmonary bypass. DESIGN: Prospective clinical study. SETTING: Academic medical center. SUBJECTS: Eighteen elective cardiac surgical patients. INTERVENTION: Cardiac surgery under cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: A near infrared spectroscopic fiber optic probe was placed over the hypothenar eminence. Reference Po2 and pH sensors were inserted in the abductor digiti minimi (V). Data were collected every 30 secs during surgery and for 6 hrs following cardiopulmonary bypass. Calibration equations developed from one third of the data were used with the remaining data to investigate sensitivity of the near infrared spectroscopic measurement to physiologic changes resulting from cardiopulmonary bypass. Near infrared spectroscopic and reference pH and Po2 measurements were compared for each subject using standard error of prediction. Near infrared spectroscopic pH and Po2 at baseline were compared with values during cardiopulmonary bypass just before rewarming commenced (hypotensive, hypothermic), after rewarming (hypotensive, normothermic) just before discontinuation of cardiopulmonary bypass, and at 6 hrs following cardiopulmonary bypass (normotensive, normothermic) using mixed-model analysis of variance. Near infrared spectroscopic pH and Po2 were well correlated with the invasive measurement of pH (R2 =.84) and Po2 (R 2 =.66) with an average standard error of prediction of 0.022 +/- 0.008 pH units and 6 +/- 3 mm Hg, respectively. The average difference between the invasive and near infrared spectroscopic measurement was near zero for both the pH and Po2 measurements. Near infrared spectroscopic Po2 significantly decreased 50% on initiation of cardiopulmonary bypass and remained depressed throughout the bypass and

Measurement of cortical functional activation in awake mice using two-photon microscopy and a novel pO2-sensitive probe(Conference Presentation)

Science.gov (United States)

Sencan, Ikbal; Esipova, Tatiana V.; Kilic, Kivilcim; Li, Baoqiang; Desjardins, Michèle; Yaseen, Mohammad A.; Wang, Hui; Jaswal, Rajeshwer S.; Kura, Sreekanth; Fu, Buyin; Boas, David A.; Devor, Anna; Sakadžić, Sava; Vinogradov, Sergei A.

2017-02-01

We characterized cortical microvascular PO2 and blood flow changes in response to whisker stimulation in awake mice. The measurements were performed by combining two-photon microscopy imaging of the cortical oxygenation and optical coherence tomography imaging of the cerebral blood flow. In order to perform fast spatio-temporally resolved measurements of PO2, we used a newly-developed oxygen-sensitive probe PtG-2P, which has significantly higher brightness than the established two-photon-enhanced oxygen sensor PtP-C343. We characterized the performance of the new probe in vivo and mapped the amplitudes and shapes (e.g. initial dip, overshoot, and post stimulus undershoot) of the PO2 changes as a function of the vessel type (e.g., arterioles, capillaries, and venules) and a distance from the activation center. The measurements in the awake mice are not affected by the confounding factors of anesthesia on the animal physiology, including the level of cerebral metabolism and the amplitude and speed of neuronal and vascular responses. Our results will help to understand changes in oxygenation and blood flow on the cortical microvascular scale, will lead to improved understanding of the cerebral physiology, pathophysiology and will improve quantitative interpretation of fMRI signals.

Descriptive statistics and risk assessment for the control of seasonal pollutant effects of 210Po and 210Pb in coastal waters (Canakkale, Turkey)

International Nuclear Information System (INIS)

Serpil Akozcan; Fatih Kulahci

2018-01-01

210 Po is absorbed into the human body by seafood intake. Especially, mollusks and mussels are known to have much higher 210 Po concentration than fish among various other types of seafood and are consumed in large quantities in Aegean Sea. 210 Po and 210 Pb radionuclide concentrations are obtained in the Mediterranean mussel (Mytilus galloprovincialis) and in the sediment samples collected from the Canakkale. The activity concentrations of 210 Po and 210 Pb are counted using alpha spectrometry. Activity concentrations of 210 Po and 210 Pb in mussels are in the ranged of 227 ± 11-540 ± 38 and 17 ± 4-48 ± 5 Bq kg -1 dw (dry weight), for sediments the ranges are 23 ± 6-41 ± 3 and 15 ± 3-44 ± 1 Bq kg -1 dw, respectively. Additionally, annual committed effective dose are calculated due to consumption mussel in Canakkale coastal region. The highest effective doses of 210 Po and 210 Po are found as 3187 and 56 μSv, respectively. Finally, risk analysis assessment is recommended to determine the pollutant effects of radionuclides. The risk fractions at the concentrations are easily determined with this evaluation process. This methodology has made a great contribution to risk assessments. (author)

Repeated tumor pO2 measurements by multi-site EPR oximetry as a prognostic marker for enhanced therapeutic efficacy of fractionated radiotherapy

International Nuclear Information System (INIS)

Hou Huagang; Lariviere, Jean P.; Demidenko, Eugene; Gladstone, David; Swartz, Harold; Khan, Nadeem

2009-01-01

Purpose: To investigate the temporal effects of single or fractionated radiotherapy on subcutaneous RIF-1 tumor pO 2 and to determine the therapeutic outcomes when the timing of fractionations is guided by tumor pO 2 . Methods: The time-course of the tumor pO 2 changes was followed by multi-site electron paramagnetic resonance (EPR) oximetry. The tumors were treated with single 10, 20, and 10 Gy x 2 doses, and the tumor pO 2 was measured repeatedly for six consecutive days. In the 10 Gy x 2 group, the second dose of 10 Gy was delivered at a time when the tumors were either relatively oxygenated or hypoxic. The changes in tumor volumes were followed for nine days to determine the therapeutic outcomes. Results: A significant increase in tumor pO 2 was observed at 24 h post 10 Gy, while 20 Gy resulted in a significant increase in tumor pO 2 at 72-120 h post irradiation. The tumors irradiated with a second dose of 10 Gy at 24 h, when the tumors were oxygenated, had a significant increase in tumor doubling times (DTs), as compared to tumors treated at 48 h when they were hypoxic (p 2 repeatedly during fractionated schemes to optimize radiotherapeutic outcome. This technique could also be used to identify responsive and non-responsive tumors, which will facilitate the design of other therapeutic approaches for non-responsive tumors at early time points during the course of therapy.

Do culinary preparations influence 210Po activity concentration in fin fishes?

International Nuclear Information System (INIS)

Praveen Pole, R.P.; Godwin Wesley, S.; Rajan, M.P

2013-01-01

Polonium-210, a member of the 238 U series, is a major source of internal radiation dose to marine organisms and human beings. This naturally occurring radionuclide is responsible for a considerable proportion of radiation exposure of humans, in particular, through consumption of seafood. Considering all these facts, many countries and various international agencies have carried out studies for assessing the levels of 210 Po globally. The volatile nature of 210 Po at high temperatures would significantly reduce its activity concentration in various culinary preparations of seafood. Some studies of fishes have shown no measurable reduction in 210 Po activity in culinary preparations and some authors have reported measurable increase. Based on this scenario, the present study was aimed at estimating 210 Po activity concentrations in different culinary preparations of fishes traditionally prevalent in the coastal region of southern Tamil Nadu. The commonly available fish species (Sardinella sp., Leiognathus sp., Katsuwonus sp., Stolephorus sp. and Chirocentrus sp.) consumed more by the people of this region were collected from nearby fish-landing centre (Kanyakumari and Manakudi). The samples were washed thoroughly with tap water and eviscerated. The fillets were divided into four groups. Fresh fillets analysed as such; A portion of the sample was subjected to oil-frying (with commonly used spices and salt); One portion of the sample was salt-dried; Another portion of the sample was boiled (curry) along with common spices and salt. Ten to twenty grams of each sample was subjected to wet-digestion using 70% conc. HNO 3 followed by the addition of 40% H 2 O 2

Structure determination of AgPO3 and (AgPO3)0.5(AgI)0.5 glasses by neutron diffraction and small angle neutron scattering

International Nuclear Information System (INIS)

Tachez, M.; Mercier, R.; Malugani, J.P.; Chieux, P.

1987-01-01

Neutron diffraction and small angle neutron scattering (SANS) were performed on AgPO 3 and (AgPO 3 ) 0.5 (AgI) 0.5 glasses. AgPO 3 glass is made up of long chains of PO 4 tetrahedra joined together by Ag atoms. When silver iodide is added, the radial distribution function shows a large peak at 2.83 A, due to Ag-I interactions. AgI does not modify the network forming unit. The existence of small clusters is confirmed by analysing the coordination number of Ag-I pairs obtained by subtracting the experimental structure function of the AgPO 3 glass from that of the corresponding AgI-doped glasses. A rough estimation of their size is given by SANS experiments. Not all the AgI pairs are involved in AgI cluster units. The compatibility of the results obtained with recent structural investigations by non diffractometric techniques is examined. 23 refs.; 5 figs.; 3 tabs

Scintillation characteristics of LiPO3:Ce3+ glass scintillators

International Nuclear Information System (INIS)

Shin, S. W.; Hwang, J. H.

2003-01-01

LiPO 3 :Ce 3+ glass scintillators doped with 0.5, 0.75, 1.0, 1.25 and 1.5wt% cerium as an activator were fabricated. For the best transparency of the LiPO 3 glasses, optimum heating conditions were investigated. Optimum heating temperature and time is 950 .deg. C and 90 min with 1wt% sugar add as reductant. The lattice structure of LiPO 3 :Ce 3+ glass scintillator was monoclinic, its lattice constants(a 0 , b 0 , c 0 ) being 16,490λ, 5.427λ and 13.120λ. Photo-refraction index of LiPO 3 :Ce 3 + measured by SE(Spectroscopic ellipsometry) was 1.45 ∼ 1.5 and its bandgap energy was 2.342 eV. The absorption spectral range of LiPO 3 :Ce 3+ measured by UV-VIS spectrophotometry was 350∼ 375nm and the spectral ranges of photoluminescence(PL) were 400∼450nm and 750∼900nm, its maximum PL intensity appeared at 417nm and 791nm. LiPO 3 :Ce 3 + glass scintillator doped with 0.75wt% cerium showed the best PL intensity. The PL intensity increased until cerium content reaches 0.75wt% above which ir decreased

Controllable synthesis of porous LiFePO4 for tunable electrochemical Li-insertion performance

International Nuclear Information System (INIS)

Tian, Xiaohui; Zhou, Yingke; Wu, Guan; Wang, Pengcheng; Chen, Jian

2017-01-01

Highlights: • A templated freeze-drying method is developed to prepare the porous LiFePO 4 . • The pore size and porosity can be controlled by adjusting the conditions. • The effects of the porous properties on the Li-insertion performances are studied. • The optimized composite presents excellent specific capacity and rate capability. - Abstract: A templated freeze-drying method is developed to prepare the porous LiFePO 4 materials with the controlled pore size and porosity, by conveniently adjusting the size and content of the template in the precursor solution. The morphology and structure of the porous LiFePO 4 materials are characterized and the relavant electrochemical lithium-insertion performances are systematically studied. It’s found that the porous characteristics play a critical role in the lithium-ion intercalation processes and significantly affect the power capability of LiFePO 4 . The optimized porous LiFePO 4 material presents remarkable specific capacity (167 mAh g −1 at 0.1 C), rate capability (151 mAh g −1 at 1 C and 110 mAh g −1 at 10 C) and cycling stability (99.3% retention after 300 cycles at 1 C). These findings demonstrate that the electrochemical performance of the electrode material can be purposely tuned and remarkably improved by the rational design and introduction of the suitable pores, which open up new strategies for the synthesis of advanced porous materials for the lithium-ion power battery applications.

Enhanced thermal safety and high power performance of carbon-coated LiFePO4 olivine cathode for Li-ion batteries

Science.gov (United States)

Zaghib, K.; Dubé, J.; Dallaire, A.; Galoustov, K.; Guerfi, A.; Ramanathan, M.; Benmayza, A.; Prakash, J.; Mauger, A.; Julien, C. M.

2012-12-01

The carbon-coated LiFePO4 Li-ion oxide cathode was studied for its electrochemical, thermal, and safety performance. This electrode exhibited a reversible capacity corresponding to more than 89% of the theoretical capacity when cycled between 2.5 and 4.0 V. Cylindrical 18,650 cells with carbon-coated LiFePO4 also showed good capacity retention at higher discharge rates up to 5C rate with 99.3% coulombic efficiency, implying that the carbon coating improves the electronic conductivity. Hybrid Pulse Power Characterization (HPPC) test performed on LiFePO4 18,650 cell indicated the suitability of this carbon-coated LiFePO4 for high power HEV applications. The heat generation during charge and discharge at 0.5C rate, studied using an Isothermal Microcalorimeter (IMC), indicated cell temperature is maintained in near ambient conditions in the absence of external cooling. Thermal studies were also investigated by Differential Scanning Calorimeter (DSC) and Accelerating Rate Calorimeter (ARC), which showed that LiFePO4 is safer, upon thermal and electrochemical abuse, than the commonly used lithium metal oxide cathodes with layered and spinel structures. Safety tests, such as nail penetration and crush test, were performed on LiFePO4 and LiCoO2 cathode based cells, to investigate on the safety hazards of the cells upon severe physical abuse and damage.

In-situ synthesis of monodisperse micro-nanospherical LiFePO4/carbon cathode composites for lithium-ion batteries

Science.gov (United States)

Gong, Hao; Xue, Hairong; Wang, Tao; He, Jianping

2016-06-01

The LiFePO4 is recognized as the promising cathode material, due to its high specific capacity, excellent, structural stability and environmental benignity. However, it is blamed for the low tap density and poor rate performance when served as the cathode materials for a long time. Here, the microspheric LiFePO4/C composites are successfully synthesized through a one-step in-situ solvothermal method combined with carbothermic reduction. These LiFePO4/C microspheres are assembled by LiFePO4 nanoparticles (∼100 nm) and uniformly coated by the carbon, which show a narrow diameter distribution of 4 μm. As a cathode material for lithium ion batteries, the LiFePO4/C composites can deliver an initiate charge capacity of 155 mAh g-1 and retain 90% of initial capacity after 200 cycles at 0.1 C. When cycled at high current densities up to 20 C, it shows a discharge capacity of ∼60 mAh g-1, exhibiting superior rate performance. The significantly improved electrochemical performance of LiFePO4/C composites material can be attributed to its special micro-nano hierarchical structure. Microspheric LiFePO4/C composites exhibit a high tap density about 1.3 g cm-3. What's more, the well-coated carbon insures the high electrical conductivity and the nano-sized LiFePO4/C particles shorten lithium ion transport, thus exhibiting the high specific capacity, high cycling stability and good rate performance.

Synthesis and vibrational spectrum of antimony phosphate, SbPO4.

Science.gov (United States)

Brockner, Wolfgang; Hoyer, Lars P

2002-07-01

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

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

Science.gov (United States)

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

2016-11-01

Novel visible-light-driven heterojunction photocatalyst comprising exfoliated bentonite, g-C3N4 and Ag3PO4 (EB/g-C3N4/Ag3PO4) was synthesized by a facile and green method. The composites EB/g-C3N4/Ag3PO4 were characterized by X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy and the Brunauer, Emmett, and Teller (BET) surface area method. Under visible light irradiation, EB/g-C3N4/Ag3PO4 composites displayed much higher photocatalytic activity than that of either pure g-C3N4 or pure Ag3PO4 in the degradation of Rhodamine B (RhB). Among the hybrid photocatalysts, EB/g-C3N4/Ag3PO4 composite containing 20 wt% Ag3PO4 exhibited the highest photocatalytic activity for the decolorization of RhB. Under the visible-light irradiation, the RhB dye was completely decolorized in less than 60 min. The enhanced photocatalytic performance is attributed to the stable structure, enlarged surface area, strong adsorbability, strong light absorption ability, and high-efficiency separation rate of photoinduced electron-hole pairs. Our finding paves a way to design highly efficient and stable visible-light-induced photocatalysts for practical applications in wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic PROOF clusters with PoD: architecture and user experience

Science.gov (United States)

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.

210Po/210Pb Activity Ratios as a Possible `Dating Tool' of Ice Cores and Ice-rafted Sediments from the Western Arctic Ocean - Preliminary Results

Science.gov (United States)

Krupp, K.; Baskaran, M. M.

2016-02-01

We have collected and analyzed a suite of surface snow samples, ice cores, ice-rafted sediments (IRS) and aerosol samples from the Western Arctic for Po-210 and Pb-210 to examine the extent of disequilibrium between this pair to possibly use 210Po/210Pb activity ratio to date different layers of ice cores and time of incorporation of ice-rafted sediments into the sea ice. We have earlier reported that the activity concentrations of 210Pb in IRS vary over an order of magnitude and it is 1-2 orders of magnitude higher than that of the benthic sediments (1-2 dpm/g in benthic sediments compared to 25 to 300 dpm/g in IRS). In this study, we have measured 210Po/210Pb activity ratios in aerosols from the Arctic Ocean to constrain the initial 210Po/210Pb ratio at the time of deposition during precipitation. The 210Po activity concentration in recent snow is compared to surface ice samples. The `age' of IRS incorporation can be calculated as follows: [210Po]measured = [210Po]initial + [210Pb] (1 - exp(-λt)) (1) where λ is the decay constant of 210Po, 138.4 days, and `t' is the in-growth time period. From this equation, `t' can be calculated as follows: t = (-1/λ) [ln (1- ((210Po/210Pb)measured - (210Po/210Pb)initial)] (2) The assumption involved in this approach are: i) there is no preferential uptake of 210Po (highly biogenic - S group); and iii) both 210Po and 210Pb remain as closed system. The calculated age using equation (2) will be discussed and presented.

Determination of the mean aerosol residence times in the atmosphere and additional 210Po input on the base of simultaneous determination of 7Be, 22Na, 210Pb, 210Bi and 210Po in urban air

International Nuclear Information System (INIS)

Magdalena Dlugosz-Lisiecka; Henryk Bem

2012-01-01

The significant differences in the activities of 210 Pb, 210 Bi, 210 Po and cosmogenic 7 Be and 22 Na radionuclides in the urban aerosol samples collected in the summers 2010 and 2011 in the Lodz city of Poland were observed. Simultaneous measurement of these radionuclides, after a simple modification of the one compartment model, allows us to calculate both: the corrected aerosol residence times in the troposphere (1 / 25 days) and in the lower stratosphere (103 / 205 days). The relative input of the additional sources (beside of the 222 Rn decay in the air) to the total activity concentrations of 210 Pb, 210 Bi and 210 Po radionuclides in the urban air, plays a substantial role (up to 97% of the total activity) only in the case of 210 Po. (author)

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

International Nuclear Information System (INIS)

Znamierowska, T.; Mizer, D.

2002-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Skwarzec, B

1988-01-01

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

PO2 Cycling Reduces Diaphragm Fatigue by Attenuating ROS Formation

OpenAIRE

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

2014-01-01

Prolonged muscle exposure to low PO2 conditions may cause oxidative stress resulting in severe muscular injuries. We hypothesize that PO2 cycling preconditioning, which involves brief cycles of diaphragmatic muscle exposure to a low oxygen level (40 Torr) followed by a high oxygen level (550 Torr), can reduce intracellular reactive oxygen species (ROS) as well as attenuate muscle fatigue in mouse diaphragm under low PO2. Accordingly, dihydrofluorescein (a fluorescent probe) was used to monito...

Rigid'' skeleton dynamics of Li sub 3 In sub 2 (PO sub 4 ) sub 3 superionic conductor

Energy Technology Data Exchange (ETDEWEB)

Naganovsky, Y K; Sigaryov, S E [Inst. of Crystallography, Academy of Sciences, Moscow (USSR)

1992-01-01

The effect studied is made by the thermal prehistory of the Li{sub 3}In{sub 2}(PO{sub 4}){sub 3} ceramics on their structural and electrophysical characteristics. Annealing at T>1290 K is shown to result in a monoclinic (HT) and at T<1230 K, rhombohedral (LT) modifications of the crystal structure of Li{sub 3}In{sub 2}(PO{sub 4}){sub 3}. At the same temperature the ionic conductivity ({sigma}) of the HT-modification is found to be higher than that of LT-modification. Annealing of LT-ceramics at {proportional to}985 K leads to a decrease of {sigma} by as much as two order of magnitude seems due to Li{sup +}-ions redistribution in the (In{sub 2}P{sub 3}O{sub 12}){sub 3{infinity}}{sup 3-} skeleton cavities. In the 290-650 K temperature range phase transitions both in LT- and HT-Li{sub 3}In{sub 2}(PO{sub 4}){sub 3} are observed. (orig.).

Efficient UV-emitting X-ray phosphors: octahedral Zr(PO4)6 luminescence centers in potassium hafnium-zirconium phosphates K2Hf1-xZrx(PO4)2 and KHf2(1-x)Zr2x(PO4)3

International Nuclear Information System (INIS)

Torardi, C.C.; Miao, C.R.; Li, J.

2003-01-01

Potassium hafnium-zirconium phosphates, K 2 Hf 1-x Zr x (PO 4 ) 2 and KHf 2(1-x) Zr 2x (PO 4 ) 3 , are broad-band UV-emitting phosphors. At room temperature, they have emission peak maxima at approximately 322 and 305 nm, respectively, under 30 kV peak molybdenum X-ray excitation. Both phosphors demonstrate luminescence efficiencies that make them up to ∼60% as bright as commercially available CaWO 4 Hi-Plus. The solid-state and flux synthesis conditions, and X-ray excited UV luminescence of these two phosphors are discussed. Even though the two compounds have different atomic structures, they contain zirconium in the same active luminescence environment as that found in highly efficient UV-emitting BaHf 1-x Zr x (PO 4 ) 2 . All the three materials have hafnium and zirconium in octahedral coordination via oxygen-atom corner sharing with six separate PO 4 tetrahedra. This octahedral Zr(PO 4 ) 6 moiety appears to be an important structural element for efficient X-ray excited luminescence, as are the edge-sharing octahedral TaO 6 chains for tantalate emission

Radiation resistant PIDECα cell using photon intermediate direct energy conversion and a 210Po source.

Science.gov (United States)

Weaver, Charles L; Schott, Robert J; Prelas, Mark A; Wisniewski, Denis A; Rothenberger, Jason B; Lukosi, Eric D; Oh, Kyuhak

2018-02-01

Radiation damage is a significant concern with both alphavoltaic and betavoltaic cells because their performance degrades, especially with high-energy - (>200keV) beta and alpha particles. Indirect excitation methods, such as the Photon Intermediate Direct Energy Conversion (PIDEC) framework, can protect the transducer from radiation. A nuclear battery using a 90 Sr beta source was constructed by the author's research group, which demonstrated the radiation resistance of a PIDEC cell driven by beta particles (PIDECβ cell). Use of alpha sources to drive nuclear batteries would appear to be much more attractive than beta sources due to higher potential power density. However, they are also subject to higher rates of radiation damage. This paper describes the successful incorporation of alpha particles into the PIDEC framework using the alpha emitter 210 Po to form a PIDECα cell. The PIDECα cell transducer was exposed to alpha particles for over one year without experiencing adverse effects from radiation damage. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2016-12-15

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

Outstanding Li-storage performance of LiFePO4@MWCNTs cathode material with 3D network structure for lithium-ion batteries

Science.gov (United States)

Sun, Xiaodong; Zhang, Le

2018-05-01

In this work, the MWCNTs-decorated LiFePO4 microspheres (LiFePO4@MWCNTs) with a 3D network structure have been synthesized by a facile and efficient spray-drying approach followed by solid-state reaction in a reduction atmosphere. In the as-prepared composite, the MWCNTs around LiFePO4 nanoparticles can provide 3D conductive networks which greatly facilitate the transport of Li+-ion and electron during the electrochemical reaction. Compared to the pure LiFePO4 material, the LiFePO4@MWCNTs composite as cathode for lithium-ion batteries exhibits significantly improved Li-storage performance in terms of rate capability and cyclic stability. Therefore, we can speculate that the spray-drying approach is a promising route to prepare the high-performance electrode materials with 3D network structure for electrochemical energy storage.

Bioaccumulation of polonium 210Po in marine birds

International Nuclear Information System (INIS)

Skwarzec, B.; Fabisiak, J.

2007-01-01

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

Assessment of radiation dose from 210Pb and 210Po due to chewing tobacco leaves and smoking cigarettes - an Indian scenario

International Nuclear Information System (INIS)

Manu, Anitha; Thualsi Brindha, J.; Rajaram, S.; Venkataraman, S.; Hegde, A.G.

2011-01-01

The study of 210 Pb and 210 Po content in tobacco and its products is essential because of their elevated concentrations. The cumulative alpha-radiation dose delivered to humans from inhaled 210 Po in cigarette smoke becomes significant. 210 Pb is another element of interest since it is the precursor to 210 Po in the radioactive decay chain of 238 U. Further, in India the ingestion dose due to these radionuclides becomes significant because of chewing tobacco leaves. In the present study, the concentrations of these two radionuclides were determined in dried tobacco leaves and some branded cigarettes. 210 Pb was determined by counting the beta activity of 210 Bi with a low background beta counter after radiochemical separation and precipitation. 210 Po was determined by alpha counter after radiochemical separation and deposition of polonium on silver disc. 210 Pb and 210 Po concentrations in dry tobacco leaves ranged from 6.0 to 30.5 mBq/g (mean 15.8 mBq/g) and 5.6 to 29.3 mBq/g (mean 12.7 mBq/g). The average annual committed effective dose for the tobacco chewers (10 g/day) was estimated to be 95.5 μSv/y (39.9 μSv/y from 210 Pb and 55.6 μSv/y from 210 Po). 210 Pb and 210 Po concentrations in branded cigarettes ranged from 11.0 to 18.4 mBq/cigarette (mean 41.2 mBq/cigarette) and 10.5 to 16.6 mBq/cigarette (mean 13.1 mBq/cigarette). The average annual committed effective dose for the smokers (20 cigarettes per day) was estimated to be 149.8 μSv/y (39.8 μSv/y from 210 Pb and 110.0 μSv/y from 210 Po). (author)

(3)He pO2 mapping is limited by delayed-ventilation and diffusion in chronic obstructive pulmonary disease.

Science.gov (United States)

Marshall, Helen; Parra-Robles, Juan; Deppe, Martin H; Lipson, David A; Lawson, Rod; Wild, Jim M

2014-03-01

Lung pO2 mapping with (3)He MRI assumes that the sources of signal decay with time during a breath-hold are radiofrequency depolarization and oxygen-dependent T1 relaxation, but the method is sensitive to other sources of spatio-temporal signal change such as diffusion. The purpose of this work was to assess the use of (3)He pO2 mapping in patients with chronic obstructive pulmonary disease. Ten patients with moderate to severe chronic obstructive pulmonary disease were scanned with a 3D single breath-hold pO2 mapping sequence. Images showed signal increasing over time in some lung regions due to delayed ventilation during breath-hold. Regions of physically unrealistic negative pO2 values were seen in all patients, and regional mean pO2 values of -0.3 bar were measured in the two patients most affected by delayed ventilation (where mean time to signal onset was 3-4 s). Movement of gas within the lungs during breath-hold causes regional changes in signal over time that are not related to oxygen concentration, leading to erroneous pO2 measurements using the linear oxygen-dependent signal decay model. These spatio-temporal sources of signal change cannot be reliably separated at present, making pO2 mapping using this methodology unreliable in chronic obstructive pulmonary disease patients with significant bullous emphysema or delayed ventilation. Copyright © 2013 Wiley Periodicals, Inc.

Equilibrium diagram of KPO{sub 3}-Y(PO{sub 3}){sub 3} system, chemical preparation and characterization of KY(PO{sub 3}){sub 4}

Energy Technology Data Exchange (ETDEWEB)

Jouini, Anis; Ferid, Mokhtar; Trabelsi-Ayadi, Malika

2003-04-17

Microdifferential thermal analysis ({mu}-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO{sub 3}-Y(PO{sub 3}){sub 3} system. The only compound observed within the system was KY(PO{sub 3}){sub 4} melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO{sub 3}){sub 3} at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO{sub 3} was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO{sub 3}){sub 4} polyphosphate has the P2{sub 1} space group with lattice parameters: a=7.183(4) A, b=8.351(6) A, c=7.983(3) A, {beta}=91.75(3) deg. and Z=2 is isostructural with KNd(PO{sub 3}){sub 4}. The second allotropic form of KY(PO{sub 3}){sub 4} belongs to the P2{sub 1}/n space group with lattice parameters: a=10.835(3) A, b=9.003(2) A, c=10.314(1) A, {beta}=106.09(7) deg. and Z=4 and is isostructural with TlNd(PO{sub 3}){sub 4}. The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP{sub 4}O{sub 12} crystallizes in the C2/c space group with lattice parameters: a=7.825(3) A, b=12.537(4) A, c=10.584(2) A, {beta}=110.22(7) deg. and Z=4 is isostructural with RbNdP{sub 4}O{sub 12} and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported.

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

International Nuclear Information System (INIS)

Schuettelkopf, H.; Kiefer, H.

1981-01-01

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

Synthesis and electrochemical properties of Co-doped Li3V2(PO4)3 cathode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Kuang Quan; Zhao Yanming; An Xiaoning; Liu Jianmin; Dong Youzhong; Chen Ling

2010-01-01

Co-doped Li 3 V 2-x Co x (PO 4 ) 3 /C (x = 0.00, 0.03, 0.05, 0.10, 0.13 or 0.15) compounds were prepared via a solid-state reaction. The Rietveld refinement results indicated that single-phase Li 3 V 2-x Co x (PO 4 ) 3 /C (0 ≤ x ≤ 0.15) with a monoclinic structure was obtained. The X-ray photoelectron spectroscopy (XPS) analysis revealed that the cobalt is present in the +2 oxidation state in Li 3 V 2-x Co x (PO 4 ) 3 . XPS studies also revealed that V 4+ and V 3+ ions were present in the Co 2+ -doped system. The initial specific capacity decreased as the Co-doping content increased, increasing monotonically with Co content for x > 0.10. Differential capacity curves of Li 3 V 2-x Co x (PO 4 ) 3 /C compounds showed that the voltage peaks associated with the extraction of three Li + ions shifted to higher voltages with an increase in Co content, and when the Co 2+ -doping content reached 0.15, the peak positions returned to those of the unsubstituted Li 3 V 2 (PO 4 ) 3 phase. For the Li 3 V 1.85 Co 0.15 (PO 4 ) 3 /C compound, the initial capacity was 163.3 mAh/g (109.4% of the initial capacity of the undoped Li 3 V 2 (PO 4 ) 3 ) and 73.4% capacity retention was observed after 50 cycles at a 0.1 C charge/discharge rate. The doping of Co 2+ into V sites should be favorable for the structural stability of Li 3 V 2-x Co x (PO 4 ) 3 /C compounds and so moderate the volume changes (expansion/contraction) seen during the reversible Li + extraction/insertion, thus resulting in the improvement of cell cycling ability.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Study about excretion of 210 Po in urine

International Nuclear Information System (INIS)

Fonseca Azeredo, A.M.G. da.

1988-01-01

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

Electrochemical performances of LiMnPO4 synthesized from non-stoichiometric Li/Mn ratio.

Science.gov (United States)

Xiao, Jie; Chernova, Natasha A; Upreti, Shailesh; Chen, Xilin; Li, Zheng; Deng, Zhiqun; Choi, Daiwon; Xu, Wu; Nie, Zimin; Graff, Gordon L; Liu, Jun; Whittingham, M Stanley; Zhang, Ji-Guang

2011-10-28

In this paper, the influences of the lithium content in the starting materials on the final performances of as-prepared Li(x)MnPO(4) (x hereafter represents the starting Li content in the synthesis step which does not necessarily mean that Li(x)MnPO(4) is a single phase solid solution in this work.) are systematically investigated. It has been revealed that Mn(2)P(2)O(7) is the main impurity when Li Li(3)PO(4) begins to form once x > 1.0. The interactions between Mn(2)P(2)O(7) or Li(3)PO(4) impurities and LiMnPO(4) are studied in terms of the structural, electrochemical, and magnetic properties. At a slow rate of C/50, the reversible capacity of both Li(0.5)MnPO(4) and Li(0.8)MnPO(4) increases with cycling. This indicates a gradual activation of more sites to accommodate a reversible diffusion of Li(+) ions that may be related to the interaction between Mn(2)P(2)O(7) and LiMnPO(4) nanoparticles. Among all of the different compositions, Li(1.1)MnPO(4) exhibits the most stable cycling ability probably because of the existence of a trace amount of Li(3)PO(4) impurity that functions as a solid-state electrolyte on the surface. The magnetic properties and X-ray absorption spectroscopy (XAS) of the MnPO(4)·H(2)O precursor, pure and carbon-coated Li(x)MnPO(4) are also investigated to identify the key steps involved in preparing a high-performance LiMnPO(4). This journal is © the Owner Societies 2011

PEMODELAN KONDUKTIVITAS ION DALAM STRUKTUR Li2Sc3(PO43 (Modeling Ionic Conductivity in Li2Sc3(PO43 Structure

Directory of Open Access Journals (Sweden)

Akram La Kilo

2011-11-01

Full Text Available ABSTRAK Fasa Li2Sc3(PO43 merupakan material konduktor superionik yang dapat diaplikasikan sebagai baterai yang dapat diisi ulang (rechargeable. Ion Li+ dalam struktur Li2Sc3(PO4 dapat mengalami migrasi dari posisi terisi ke posisi kosong. Penelitian ini telah memodelkan migrasi ion Li+ dalam struktur Li2Sc3(PO4 dengan menggunakan metode bond valence sum (BVS. Metode ini dapat memprediksi bilangan oksidasi suatu atom berdasarkan jarak dengan atom-atom tetangga. Source code berbasis BVS yang digunakan adalah JUMPITER yang mensimulasi efek gaya listrik eksternal yang bertindak pada ion litium sehingga nilai BVS litium dapat dipetakan terhadap jarak. Hasil simulasi menunjukkan bahwa konduksi ion Li+ dapat terjadi pada arah [010], [101], dan [120]. Namun, lintasan konduksi ion Li+ lebih mudah terjadi pada arah [120] atau bidang ab dengan nilai maksimum BVS adalah 0,982. ABSTRACT g-phase of Li2Sc3(PO43 is a lithium super ionic conductor which can be applied as a rechargeable lithium battery. Lithium ions of g-Li2Sc3(PO43 can migrate from occupied site to vacant site. In this research, simulation of Li+ ions migration in the structure of g-Li2Sc3(PO43 carried out using bond valence sum (BVS to predict the oxidation state of Li+ion based on the distance of the ion to neighboring atoms. BVS-based code used JUMPITER to simulate the effect of external electrical force acting on the lithium ions to produce the lithium BVS value which can be mapped to the distance. The simulation results shows that Li+ ion conduction can be occurred on [010], [101], and [120] directions. However, the Li ion conduction pathway occur more easily in the direction of [120] or ab plane with the BVS maximum value is 0.982.