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Sample records for americium complexes

  1. Surface complexation modeling of americium sorption onto volcanic tuff.

    PubMed

    Ding, M; Kelkar, S; Meijer, A

    2014-10-01

    Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways. PMID:24963803

  2. Americium

    NASA Astrophysics Data System (ADS)

    Runde, Wolfgang H.; Schulz, Wallace W.

    Americium, element 95, was discovered in 1944-45 by Seaborg et al. (1950) at the Metallurgical Laboratory of the University of Chicago as a product of the irradiation of plutonium with neutrons: 239{Pu}( n,γ )^{240} Put( n,γ )^{241} Pu → - β ^-}^{241}{Am} This reaction is still the best method for the production of pure 241Am. In post-World War II work at the University of Chicago, Cunningham isolated Am(OH)3 and measured the first absorption spectrum of the Am3+ aquo ion (Cunningham, 1948). By the 1950s, the major center for americium chemistry research in the world was at Los Alamos. Since the 1970s, the majority of publications on americium have come from researchers in the former USSR and West Germany. Extensive reviews of americium chemistry can be found in Freeman and Keller (1985), Gmelin (1979), Penneman and Asprey (1955), and Schulz (1976).

  3. Americium

    SciTech Connect

    Smith, James L

    2012-06-01

    The element americium marks the end of interesting behavior in the periodic table. I will talk about how this was predicted by Johansson and Rosengren and demonstrated by me. I will talk about other questions of localization.

  4. EXAFS studies of americium (III)-benzimidazole complex in ethanol.

    PubMed

    Yaita, T; Tachimori, S; Edelstein, N M; Bucher, J J; Rao, L; Shuh, D K; Allen, P G

    2001-03-01

    The local structures of Am, Nd and Er-Benzimidazole (Biz) in solution were determined by EXAFS. The BIZ molecule coordinated to Am and Nd through two nitrogen atoms in a bidentate fashion. Two nitrogen atoms of BIZ ligated to Am and Nd with the bond distances R(Am-n) N=2.63A and R(Nd-N) = 2.65 A, respectively. The total coordination number of the Am BIZ complexes (at a molar ratio of metal ion to ligand of 1:20) was approximately 10 but that of Nd BIZ complex was approximately 9. PMID:11512888

  5. Aqueous complexes for efficient size-based separation of americium from curium.

    PubMed

    Jensen, Mark P; Chiarizia, Renato; Shkrob, Ilya A; Ulicki, Joseph S; Spindler, Brian D; Murphy, Daniel J; Hossain, Mahmun; Roca-Sabio, Adrián; Platas-Iglesias, Carlos; de Blas, Andrés; Rodríguez-Blas, Teresa

    2014-06-16

    Complexation of the adjacent actinide ions americium(III) and curium(III) by the ligand N,N'-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H2bp18c6) in aqueous solution was studied to quantify and characterize its americium/curium selectivity. Liquid-liquid extraction and spectrophotometric titration indicated the presence of both fully deprotonated and monoprotonated complexes, An(bp18c6)(+) and An(Hbp18c6)(2+) (An = Am or Cm), at the acidities that would be encountered when treating nuclear wastes. The stability constants of the complexes in 1 M NaNO3 determined using competitive complexation were log β101 = 15.49 ± 0.06 for Am and 14.88 ± 0.03 for Cm, indicating a reversal of the usual order of complex stability, where ligands bind the smaller Cm(III) ion more tightly than Am(III). The Am/Cm selectivity of bp18c6(2-) that is defined by the ratio of the Am and Cm stability constants (β101 Am/β101 Cm = 4.1) is the largest reported so far for binary An(III)-ligand complexes. Theoretical density functional theory calculations using the B3LYP functional suggest that the ligand's size-selectivity for larger 4f- and 5f-element cations arises from steric constraints in the crown ether ring. Enhanced 5f character in molecular orbitals involving actinide-nitrogen interactions is predicted to favor actinide(III) complexation by bp18c6(2-) over the complexation of similarly sized lanthanide(III) cations. PMID:24890863

  6. Thermodynamic Features of the Complexation of Neodymium(III) and Americium(III) by Lactate in Trifluoromethanesulfonate Media.

    SciTech Connect

    Peter R. Zalupski; Leigh R. Martin; Kenneth L. Nash

    2010-10-01

    The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct medium influence imposed on the thermochemistry of the investigated equilibrium. The thermochemistry of lactate protonation, when studied directly in 1.0 M sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process – a solvent extraction method for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts – may be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte. Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium, log ß1 = 2.60 ± 0.01, log ß2 = 4.66 ± 0.02 and log ß3 = 5.6 ± 0.1, and for americium, log ß1 = 2.60 ± 0.06, log ß2 = 4.7 ± 0.1 and log ß3 = 6.2 ± 0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently, the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background electrolytes such as NaClO4 and NaNO3, do not significantly impact the speciation in solution.

  7. Americium thermodynamic data for the EQ3/6 database

    SciTech Connect

    Kerrisk, J.F.

    1984-07-01

    Existing thermodynamic data for aqueous and solid species of americium have been reviewed and collected in a form that can be used with the EQ3/6 database. Data that are important in solubility calculations for americium at a proposed Yucca Mountain nuclear waste repository were emphasized. Conflicting data exist for americium complexes with carbonates. Essentially no data are available for americium solids or complexes at temperatures greater than 25{sup 0}C. 17 references, 4 figures.

  8. RECOVERY OF AMERICIUM

    DOEpatents

    Ader, M.; Hyman, H.H.

    1960-04-26

    A process is given for separating americium and plutonium and recovering the americium. Plutonium is extracted from a solution containing plutonium and americium with a water-insoluble solvent, and americium is precipitated from the aqueous phase by adding a ferric salt and an alkali metal hydroxide thereto. The precipitate may then be dissolved in hydrochloric acid and the ferric salt extracted from the americium with an organlc solvent.

  9. The structures of CyMe4-BTBP complexes of americium(iii) and europium(iii) in solvents used in solvent extraction, explaining their separation properties.

    PubMed

    Ekberg, Christian; Löfström-Engdahl, Elin; Aneheim, Emma; Foreman, Mark R StJ; Geist, Andreas; Lundberg, Daniel; Denecke, Melissa; Persson, Ingmar

    2015-11-14

    Separation of trivalent actinoid (An(iii)) and lanthanoid (Ln(iii)) ions is extremely challenging due to their similar ionic radii and chemical properties. Poly-aromatic nitrogen compounds acting as tetradentate chelating ligands to the metal ions in the extraction, have the ability to sufficiently separate An(iii) from Ln(iii). One of these compounds, 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol[1,2,4]triazin-3-yl)[2,2]bipyridine, CyMe4-BTBP, has proven to be resistant towards acidic environments and strong radiation from radioactive decomposition. EXAFS studies of the dicomplexes of CyMe4-BTBP with americium(iii) and europium(iii) in nitrobenzene, cyclohexanone, 1-hexanol, 1-octanol and malonamide (DMDOHEMA) in 1-octanol have been carried out to get a deeper understanding of the parameters responsible for the separation. The predominating complexes independent of solvent used are [Am(CyMe4-BTBP)2(NO3)](2+) and [Eu(CyMe4-BTBP)2](3+), respectively, which are present as outer-sphere ion-pairs with nitrate ions in the studied solvents with low relative permittivity. The presence of a nitrate ion in the first coordination sphere of the americium(iii) complex compensates the charge density of the complex considerably in comparison when only outer-sphere ion-pairs are formed as for the [Eu(CyMe4-BTBP)2](3+) complex. The stability and solubility of a complex in a solvent with low relative permittivity increase with decreasing charge density. The [Am(CyMe4-BTBP)2(NO3)](2+) complex will therefore be increasingly soluble and stabilized over the [Eu(CyMe4-BTBP)2](3+) complex in solvents with decreasing relative permittivity of the solvent. The separation of americium(iii) from europium(iii) with CyMe4-BTBP as extraction agent will increase with decreasing relative permittivity of the solvent, and thereby also with decreasing solubility of CyMe4-BTBP. The choice of solvent is therefore a balance of a high separation factor and sufficient solubility of the CyMe4-BTBP

  10. Americium recovery from reduction residues

    DOEpatents

    Conner, W.V.; Proctor, S.G.

    1973-12-25

    A process for separation and recovery of americium values from container or bomb'' reduction residues comprising dissolving the residues in a suitable acid, adjusting the hydrogen ion concentration to a desired level by adding a base, precipitating the americium as americium oxalate by adding oxalic acid, digesting the solution, separating the precipitate, and thereafter calcining the americium oxalate precipitate to form americium oxide. (Official Gazette)

  11. Americium separations from high salt solutions

    SciTech Connect

    Mary E. Barr; Gordon D. Jarvinen; Louis D. Schulte; Peter C. Stark; Rebecca M. Chamberlin; Kent D. Abney; Thomas E. Ricketts; Yvette E. Valdez; Richard A. Bartsch

    2000-03-01

    Americium (III) exhibits an unexpectedly high affinity for anion-exchange material from the high-salt evaporator bottoms solutions--an effect which has not been duplicated using simple salt solutions. Similar behavior is observed for its lanthanide homologue, Nd(III), in complex evaporator bottoms surrogate solutions. There appears to be no single controlling factor--acid concentration, total nitrate concentration or solution ionic strength--which accounts for the approximately 2-fold increase in retention of the trivalent ions from complex solutions relative to simple solutions. Calculation of species activities (i.e., water, proton and nitrate) in such concentrated mixed salt solutions is difficult and of questionable accuracy, but it is likely that the answer to forcing formation of anionic nitrate complexes of americium lies in the relative activities of water and nitrate. From a practical viewpoint, the modest americium removal needs (ca. 50--75%) from nitric acid evaporator bottoms allow sufficient latitude for the use of non-optimized conditions such as running existing columns filled with older, well-used Reillex HPQ. Newer materials, such as HPQ-100 and the experimental bifunctional resins, which exhibit higher distribution coefficients, would allow for either increased Am removal or the use of smaller columns. It is also of interest that one of the experimental neutral-donor solid-support extractants, DHDECMP, exhibits a similarly high level of americium (total alpha) removal from EV bottoms and is much less sensitive to total acid content than commercially-available material.

  12. Complexation of trivalent americium and lanthanides with terdentate 'N' donor ligands: the role of rigidity in the ligand structure.

    PubMed

    Bhattacharyya, Arunasis; Gadly, Trilochan; Pathak, Priyanath; Ghosh, Sunil K; Mohapatra, Manoj; Ghanty, Tapan K; Mohapatra, Prasanta K

    2014-08-28

    A systematic study on the Ln(3+) complexation behaviour with two terdentate 'N' donor ligands of varying structural rigidity, viz. 5,6-dimethyl-(1,2,4)-triazinylbipyridine (Me2TBipy) and 5,6-dimethyl-(1,2,4)-triazinylphenanthroline (Me2TPhen), is performed in the present work by UV-Vis spectrophotometry, time resolved fluorescence spectroscopy (TRFS) and electrospray ionization mass spectrometric (ESI-MS) studies. These studies indicate the formation of a 1 : 1 complex of La(3+), 1 : 2 complexes of Eu(3+) and Er(3+) with both the ligands. Density functional theoretical (DFT) study is carried out to determine the solution phase structure of the Eu(3+) complex considering the species (from UV-Vis spectrophotometry) and C2v site symmetry around the Eu(3+) ion (from TRFS study). Me2TPhen is found to be a stronger complexing ligand as compared to Me2TBipy irrespective of the Ln(3+) ions. The solid state crystal structure of the La(3+) complex of Me2TPhen is determined using the single crystal X-ray diffraction (SCXRD) technique. The complexation of the trivalent Am(3+) ion is also studied with both these ligands using UV-Vis spectrophotometric titrations which show the formation of 1 : 2 complexes with higher complexation constant values as compared to all the Ln(3+) ions studied, indicating the selectivity of these ligands for the trivalent actinides over the lanthanides. PMID:25001925

  13. Extraction of americium in different oxidation states in a two-phase aqueous system based on poly(ethylene glycol)

    SciTech Connect

    Molochnikova, N.P.; Frenkel', B.F.; Myasoedov, B.F.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.

    1987-09-01

    The extraction of americium in different states of oxidation was studied in a two-phase aqueous system based on poly(ethylene glycol). Conditions were found for the quantitative extraction of americium (III) and americium (V) from solutions of ammonium sulfate in the pH range of 3-5 and in the presence of arsenazo III. The composition of the complexes of americium with the reagent was determined; americium (III) reacts with arsenazo III in solutions of ammonium sulfate to form complexes with the composition of MeR and Me/sub 2/R. Characteristics of the absorption spectra of complexes of americium (III) and (V) with arsenazo III in ammonium sulfate solutions and in extracts based on aqueous solutions of poly(ethylene glycol) were found. The molar extinction coefficients of complexes of americium with arsenazo III were determined in these solutions.

  14. SEPARATION OF AMERICIUM FROM PROMETHIUM

    DOEpatents

    Pressly, R.E.

    1959-07-01

    Promethium-147 is separated from americium in acidic aqueous solution by adding fluosilicic acid to the solution, heating the solution to form a promethium precipitate and separating the precipitate from solution. The precipitate is then re-dissolved by ihe addition of boric acid and nitric acid, and re-precipitated by the addition of fluosilicic acid. This procedure is repeated six or more times to obtain a relatively americium-free promeihium precipitate. Americium may be separately recovered from the supernatant liquids. This process is applicable to the recovery of promethium from fission-product solutions which have been allowed to decay for a period of two to four years.

  15. SEPARATION OF CURIUM AND AMERICIUM

    DOEpatents

    Fields, P.R.; Isaac, N.M.

    1962-02-20

    Curium and americium are contained in an anhydrous molten salt medium having a low melting point. Curium is preferentially extracted from the molten salt by a hot organic solvent containing preferably less than 10% alkyl phosphate. (AEC)

  16. Selectivity of bis-triazinyl bipyridine ligands for americium(III) in Am/Eu separation by solvent extraction. Part 1. Quantum mechanical study on the structures of BTBP complexes and on the energy of the separation.

    PubMed

    Narbutt, Jerzy; Oziminski, Wojciech P

    2012-12-21

    Theoretical studies were carried out on two pairs of americium and europium complexes formed by tetra-N-dentate lipophilic BTBP ligands, neutral [ML(NO(3))(3)] and cationic [ML(2)](3+) where M = Am(III) or Eu(III), and L = 6,6'-bis-(5,6-diethyl-1,2,4-triazin-3-yl)-2,2'-bipyridine (C2-BTBP). Molecular structures of the complexes have been optimized at the B3LYP/6-31G(d) level and total energies of the complexes in various media were estimated using single point calculations performed at the B3LYP/6-311G(d,p) and MP2/6-311G(d,p) levels of theory. In the calculations americium and europium ions were treated using pseudo-relativistic Stuttgart-Dresden effective core potentials and the accompanying basis sets. Selectivity in solvent extraction separation of two metal ions is a co-operative function of contributions from all extractable metal complexes, which depend on physico-chemical properties of each individual complex and on its relative amount in the system. Semi-quantitative analysis of BTBP selectivity in the Am/Eu separation process, based on the contributions from the two pairs of Am(III) and Eu(III) complexes, has been carried out. To calculate the energy of Am/Eu separation, a model of the extraction process was used, consisting of complex formation in water and transfer of the formed complex to the organic phase. Under the assumptions discussed in the paper, this simple two-step model results in reliable values of the calculated differences in the energy changes for each pair of the Am/Eu complexes in both steps of the process. The greater thermodynamic stability (in water) of the Am-BTBP complexes, as compared with the analogous Eu species, caused by greater covalency of the Am-N than Eu-N bonds, is most likely the main reason for BTBP selectivity in the separation of the two metal ions. The other potential reason, i.e. differences in lipophilic properties of the analogous complexes of Am and Eu, is less important with regard to this selectivity. PMID

  17. Plutonium and americium separation from salts

    DOEpatents

    Hagan, Paul G.; Miner, Frend J.

    1976-01-01

    Salts or materials containing plutonium and americium are dissolved in hydrochloric acid, heated, and contacted with an alkali metal carbonate solution to precipitate plutonium and americium carbonates which are thereafter readily separable from the solution.

  18. The New Element Americium (Atomic Number 95)

    DOE R&D Accomplishments Database

    Seaborg, G.T.; James, R.A.; Morgan, L.O.

    1948-01-01

    Several isotopes of the new element 95 have been produced and their radiations characterized. The chemical properties of this tripositive element are similar to those of the typical tripositive lanthanide rare-earth elements. Element 95 is different from the latter in the degree and rate of formation of certain compounds of the complex ion type, which makes possible the separation of element 95 from the lanthanide rare-earths. The name americium (after the Americas) and the symbol Am are suggested for the element on the basis of its position as the sixth member of the actinide rare-earth series, analogous to europium, Eu, of the lanthanide series.

  19. A TRUEX-based separation of americium from the lanthanides

    SciTech Connect

    Bruce J. Mincher; Nicholas C. Schmitt; Mary E. Case

    2011-03-01

    Abstract: The inextractability of the actinide AnO2+ ions in the TRUEX process suggests the possibility of a separation of americium from the lanthanides using oxidation to Am(V). The only current method for the direct oxidation of americium to Am(V) in strongly acidic media is with sodium bismuthate. We prepared Am(V) over a wide range of nitric acid concentrations and investigated its solvent extraction behavior for comparison to europium. While a separation is achievable in principal, the presence of macro amounts of cerium competes for the sparingly soluble oxidant and the oxidant itself competes for CMPO complexation. These factors conspire to reduce the Eu/Am separation factor from ~40 using tracer solutions to ~5 for extractions from first cycle raffinate simulant solution. To separate pentavalent americium directly from the lanthanides using the TRUEX process, an alternative oxidizing agent will be necessary.

  20. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, R.V.; Mincher, B.J.

    2002-05-23

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65 C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% {+-} 6.0 extraction of americium and 69% {+-} 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% {+-} 3.0 extraction of americium and 83% {+-} 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95 C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  1. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    SciTech Connect

    Grimes, Travis Shane; Mincher, Bruce Jay; Schmitt, Nicholas C

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  2. Aqueous complexation of citrate with neodymium(III) and americium(III): a study by potentiometry, absorption spectrophotometry, microcalorimetry, and XAFS.

    PubMed

    Brown, M Alex; Kropf, A Jeremy; Paulenova, Alena; Gelis, Artem V

    2014-05-01

    The aqueous complexation of Nd(III) and Am(III) with anions of citrate was studied by potentiometry, absorption spectrophotometry, microcalorimetry, and X-ray absorption fine structure (XAFS). Using potentiometric titration data fitting the metal-ligand (L) complexes that were identified for Nd(III) were NdHL, NdL, NdHL2, and NdL2; a review of trivalent metal-citrate complexes is also included. Stability constants for these complexes were calculated from potentiometric and spectrophotometric titrations. Microcalorimetric results concluded that the entropy term of complex formation is much more dominant than the enthalpy. XAFS results showed a dependence in the Debye-Waller factor that indicated Nd(iii)-citrate complexation over the pH range of 1.56-6.12. PMID:24619154

  3. Phonon dynamics of americium telluride

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Ahirwar, Ashok K.; Sanyal, S. P.

    2013-06-01

    We report for the first time the complete phonon dispersion curves for Americium telluride (AmTe) using a breathing shell models (BSM) to establish their predominant ionic nature. The results obtained in the present study show the general features of the phonon spectrum. We could not compare our results with the experimental measurements as they are not available so far. We emphasize the need of neutron scattering measurements to compare our results. We also report, for the first time specific heat for this compound.

  4. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, Robert Vincent; Mincher, Bruce Jay

    2002-08-01

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65°C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% ± 6.0 extraction of americium and 69% ± 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% ± 3.0 extraction of americium and 83% ± 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95°C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  5. The Most Useful Actinide Isotope: Americium-241.

    ERIC Educational Resources Information Center

    Navratil, James D.; And Others

    1990-01-01

    Reviewed is the discovery, nuclear and chemical properties, and uses of an isotope of Americium (Am-241). Production and separation techniques used in industry are emphasized. Processes are illustrated in flow sheets. (CW)

  6. Neutron production in several americium compounds

    SciTech Connect

    Shores, E. F.

    2004-01-01

    Americium, like other alpha emitting actinides, may indirectly produce neutrons when combined with light target materials. These (alpha,n) reaction neutrons, along with well known photon lines, have been an advantage of the {sup 241}Am isotope for diverse applications such as radiography, thickness gauges, neutron sources, and even common household smoke detectors. To characterize these sources, the SOURCES code was used to calculate neutron yields and spectra from {sup 241}Am metal, americium oxide, and americium aluminum alloys. Such information may be used as source terms for future transport problems (e.g. shielding calculations). Table 1 contains neutron yields for six americium configurations. The metal, oxides, and alloys were run as homogeneous problems while the interface case was run in both two- and three-region interface modes.

  7. MODELING AND FISSION CROSS SECTIONS FOR AMERICIUM.

    SciTech Connect

    ROCHMAN, D.; HERMAN, M.; OBLOZINSKY, P.

    2005-05-01

    This is the final report of the work performed under the LANL contract on the modeling and fission cross section for americium isotopes (May 2004-June 2005). The purpose of the contract was to provide fission cross sections for americium isotopes with the nuclear reaction model code EMPIRE 2.19. The following work was performed: (1) Fission calculations capability suitable for americium was implemented to the EMPIRE-2.19 code. (2) Calculations of neutron-induced fission cross sections for {sup 239}Am to {sup 244g}Am were performed with EMPIRE-2.19 for energies up to 20 MeV. For the neutron-induced reaction of {sup 240}Am, fission cross sections were predicted and uncertainties were assessed. (3) Set of fission barrier heights for each americium isotopes was chosen so that the new calculations fit the experimental data and follow the systematics found in the literature.

  8. Separation and determination of americium in low-level alkaline waste of NPP origin

    NASA Astrophysics Data System (ADS)

    Todorov, B.; Djingova, R.; Nikiforova, A.

    2006-01-01

    The aim of this work is to develop a short and cost-saving procedure for the determination of 241Am in sludge sample of the alkaline low-level radioactive waste (LL LRAW) collected from Nuclear Power Plant “Kozloduy”. The determination of americium was a part of a complex analytical approach, where group actinide separation was achieved. An anion exchange was used for separation of americium from uranium, plutonium and iron. For the separation of americium extraction with diethylhexyl phosphoric acid (DEHPA) was studied. The final radioactive samples were prepared by micro co-precipitation with NdF3, counted by alpha and gamma spectrometry. The procedure takes 2 hours. The recovery yield of the procedure amounts to (95 ± 1.5)% and the detection limit is 53 mBq/kg 241Am (t=150 000 s). The analytical procedure was applied for actual liquid wastes and results were compared to standard procedure.

  9. New Fecal Method for Plutonium and Americium

    SciTech Connect

    Maxwell, S.L. III

    2000-06-27

    A new fecal analysis method that dissolves plutonium oxide was developed at the Westinghouse Savannah River Site. Diphonix Resin (Eichrom Industries), is used to pre-concentrate the actinides from digested fecal samples. A rapid microwave digestion technique is used to remove the actinides from the Diphonix Resin, which effectively extracts plutonium and americium from acidic solutions containing hydrofluoric acid. After resin digestion, the plutonium and americium are recovered in a small volume of nitric acid that is loaded onto small extraction chromatography columns, TEVA Resin and TRU Resin (Eichrom Industries). The method enables complete dissolution of plutonium oxide and provides high recovery of plutonium and americium with good removal of thorium isotopes such as thorium-228.

  10. Status of Americium-241 recovery at Rocky Flats Plant

    SciTech Connect

    Knighton, J.B.; Hagan, P.G.; Navratil, J.D.; Thompson, G.H.

    1981-01-01

    This paper is presented in two parts: Part I, Molten Salt Extraction of Americium from Molten Plutonium Metal, and Part II, Aqueous Recovery of Americium from Extraction Salts. The Rocky Flats recovery process used for waste salts includes (1) dilute hydrochloric acid dissolution of residues; (2) cation exchange to convert from the chloride to the nitrate system and to remove gross amounts of monovalent impurities; (3) anion exchange separation of plutonium; (4) oxalate precipitation of americium; and (5) calcination of the oxalate at 600/sup 0/C to yield americium oxide. The aqueous process portion describes attempts to improve the recovery of americium. The first part deals with modifications to the cation exchange step; the second describes development of a solvent extractions process that will recovery americium from residues containing aluminium as well as other common impurities. Results of laboratory work are described. 3 figures, 6 tables. (DP)

  11. oxidation of americium(iii) and the stability of americium(iv) and americium(vi) in solutions of sulfuric and perchloric acids

    SciTech Connect

    Milyukova, M.S.; Litvina, M.N.; Myasoedov, B.F.

    1986-07-01

    The oxidation of weighable amounts of americium in solutionsof sulfuric and perchloric acids was investigated by a spectrophotometric method. The stability of americium(IV) and (VI) in mineral acids was studied. A method was developed for the production of tetravalent americium in solutions of 0.1-3 M H/sub 2/SO/sub 4/ and 0.1-1 M HClO/sub 4/, containing potassium phosphotungstate K/sub 10/P/sub 2/W/sub 17/O/sub 61/ an an oxidizing mixture - a silver salt and ammonium persulfate.

  12. Electron heat capacity and lattice properties of Americium

    NASA Astrophysics Data System (ADS)

    Povzner, A. A.; Filanovich, A. N.; Os'kina, V. A.; Volkov, A. G.

    2013-12-01

    The temperature dependence of the electron heat capacity of americium is calculated using the concepts on the electronic structure and magnetic properties of this element. The Debye temperature, the thermal expansion coefficient, and the bulk modulus of americium are determined on the basis of the results of calculations and experimental data on heat capacity.

  13. Removal of plutonium and americium from alkaline waste solutions

    DOEpatents

    Schulz, Wallace W.

    1979-01-01

    High salt content, alkaline waste solutions containing plutonium and americium are contacted with a sodium titanate compound to effect removal of the plutonium and americium from the alkaline waste solution onto the sodium titanate and provide an effluent having a radiation level of less than 10 nCi per gram alpha emitters.

  14. Self-irradiation and oxidation effects on americium sesquioxide and Raman spectroscopy studies of americium oxides

    SciTech Connect

    Horlait, Denis; Delahaye, Thibaud

    2014-09-15

    Americium oxides samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, with an emphasis on their structural behavior under oxidation and self-irradiation. Raman spectra of americium dioxide (AmO{sub 2}) and sesquioxide (Am{sub 2}O{sub 3}) were obtained for the first time. With the help of literature data on isostructural oxides, Raman signatures of Ia-3 C-type Am{sub 2}O{sub 3} and P-3m1 A-type Am{sub 2}O{sub 3} are identified. For AmO{sub 2,} a clear band is noted at 390 cm{sup −1}. Its nature is compared to that of the other actinide dioxides. Am{sub 2}O{sub 3} evolution under ambient conditions and against {sup 241}Am α self-irradiation was monitored by powder XRD. The sample, initially composed of A-type Am{sub 2}O{sub 3} as major phase as well as C2/m B-type and C-type structures as minor phases, progressively oxidizes to Fm-3m AmO{sub 2−δ} over a few months. On the basis of diffractogram refinements, evolutions of unit cell volumes caused by self-irradiation are also determined and discussed. - Graphical abstract: The evolution of americium oxide under ambient conditions was monitored using XRD (X-ray diffraction) and Raman spectroscopy. After a thermal treatment under reducing conditions, a polyphasic sample mainly composed of A- and C-type americium sesquioxides is evidenced by XRD and Raman spectroscopy. The sample then evolves through two processes: oxidation and self-irradiation. The first one provokes the progressive appearance of F-type americium dioxide while the initial phases disappear, whereas the main effect of the second is a structural swelling with time. - Highlights: • The first Raman spectroscopy measurements on americium oxides were performed. • Observed Am{sub 2}O{sub 3} Raman bands were identified thanks to data on analogue compounds. • AmO{sub 2} assumed T{sub 2g} band presents a shift compared to the actinide dioxide series. • Am{sub 2}O{sub 3} evolution under self-irradiation and oxidation was also

  15. Higher Americium Oxidation State Research Roadmap

    SciTech Connect

    Mincher, Bruce J.; Law, Jack D.; Goff, George S.; Moyer, Bruce A.; Burns, Jon D.; Lumetta, Gregg J.; Sinkov, Sergey I.; Shehee, Thomas C.; Hobbs, David T.

    2015-12-18

    The partitioning of hexavalent Am from dissolved nuclear fuel requires the ability to efficiently oxidize Am(III) to Am(VI) and to maintain that oxidation state for a length of time sufficient to perform the separation. Several oxidants have been, or are being developed. Chemical oxidants include Ag-catalyzed ozone, Ag-catalyzed peroxydisulfate, Cu(III) periodate, and sodium bismuthate. Hexavalent americium has also now successfully been prepared by electrolysis, using functionalized electrodes. So-called auto-reduction rates of Am(VI) are sufficiently slow to allow for separations. However, for separations based on solvent extraction or ion exchange using organic resins, the high valence state must be maintained under the reducing conditions of the organic phase contact, and a holding oxidant is probably necessary. Until now, only Cu(III) periodate and sodium bismuthate oxidation have been successfully combined with solvent extraction separations. Bismuthate oxidation provided the higher DAm, since it acts as its own holding oxidant, and a successful hot test using centrifugal contactors was performed. For the other oxidants, Ag-catalyzed peroxydisulfate will not oxidize americium in nitric acid concentrations above 0.3 M, and it is not being further investigated. Peroxydisulfate in the absence of Ag catalysis is being used to prepare Am(V) in ion exchange work, discussed below. Preliminary work with Ag-catalyzed ozone has been unsuccessful for extractions of Am(VI) from 6.5 M HNO3, and only one attempt at extraction, also from 6.5 M HNO3, using the electrolytic oxidation has been attempted. However, this high acid concentration was based on the highest Am extraction efficiency using the bismuthate oxidant; which is only sparingly soluble, and thus the oxidation yield is based on bismuthate solubility. Lower acid concentrations may be sufficient with alternative oxidants and work with Ag-ozone, Cu(III) and electrolysis is on-going. Two non

  16. Frontiers of Chemistry for Americium and Curium

    DOE R&D Accomplishments Database

    Keller, O. L. Jr.

    1984-01-01

    The discoveries of americium and curium were made only after Seaborg had formulated his actinide concept in order to design the chemistry needed to separate them from irradiated /sup 239/Pu targets. Their discoveries thus furnished the first clear-cut evidence that the series exists and justified Seaborg`s bold assumption that even though Th and Pa appeared to presage a following 6d series, the pattern established by the periodic table after Cs and Ba would be repeated exactly after Fr and Ra. That is to say, a new 5f element rare earth series (the actinides) would follow Ac in the same way the 4f rare earth series (the lanthanides) follows La. The consequences of the resulting half-filled 5f/sup 7/ shell at Cm were originally presented by Seaborg as a test of his hypothesis. Recent research is outlined that substantiates Seaborg`s predictions in new and definitive ways.

  17. Frontiers of chemistry for americium and curium

    SciTech Connect

    Keller, O.L. Jr.

    1984-01-01

    The discoveries of americium and curium were made only after Seaborg had formulated his actinide concept in order to design the chemistry needed to separate them from irradiated /sup 239/Pu targets. Their discoveries thus furnished the first clear-cut evidence that the series exists and justified Seaborg's bold assumption that even though Th and Pa appeared to presage a following 6d series, the pattern established by the periodic table after Cs and Ba would be repeated exactly after Fr and Ra. That is to say, a new 5f element rare earth series (the actinides) would follow Ac in the same way the 4f rare earth series (the lanthanides) follows La. The consequences of the resulting half-filled 5f/sup 7/ shell at Cm were originally presented by Seaborg as a test of his hypothesis. Recent research is outlined that substantiates Seaborg's predictions in new and definitive ways. 15 references, 4 figures.

  18. Structure of a single model to describe plutonium and americium decorporation by DTPA treatments.

    PubMed

    Fritsch, P; Sérandour, A L; Grémy, O; Phan, G; Tsapis, N; Fattal, E; Benech, H; Deverre, J R; Poncy, J L

    2010-10-01

    The aim of this study is to propose a single modeling structure to describe both plutonium and americium decorporation by DTPA, which is based on hypotheses mostly validated by experimental data. Decorporation efficacy of extracellular retention depends on the concentration ratio of DTPA vs. actinides and varies in each compartment according to the amount of biological ligands and their affinity for actinides. By contrast, because the relatively long residence time of DTPA after its cell internalization and the stability of actinide-DTPA complexes, intracellular decorporation efficacy is mainly controlled by a DTPA/actinide ratio, which is specific to each retention compartment. Although the affinity of DTPA is much lower for americium than for plutonium, a larger decorporation of americium can be obtained, which is explained by different biological ligands and/or their affinity for the actinide. Altogether, these results show that the relative contribution of intra vs. extracellular decorporation varies depending on the actinide, the chemical form of radionuclides, the galenic formulation of DTPA, and the treatment schedule. PMID:20838098

  19. PROCESS FOR SEPARATING AMERICIUM AND CURIUM FROM RARE EARTH ELEMENTS

    DOEpatents

    Baybarz, R.D.; Lloyd, M.H.

    1963-02-26

    This invention relates to methods of separating americium and curium values from rare earth values. In accordance with the invention americium, curium, and rare earth values are sorbed on an anion exchange resin. A major portion of the rare earth values are selectively stripped from the resin with a concentrated aqueous solution of lithium chloride, and americium, curium, and a minor portion of rare earth values are then stripped from the resin with a dilute aqueous solution of lithium chloride. The americium and curium values are further purified by increasing the concentration of lithium chloride in the solution to at least 8 molar and selectively extracting rare earth values from the resulting solution with a monoalkylphosphoric acid. (AEC)

  20. Plutonium and Americium Geochemistry at Hanford: A Site Wide Review

    SciTech Connect

    Cantrell, Kirk J.; Felmy, Andrew R.

    2012-08-23

    This report was produced to provide a systematic review of the state-of-knowledge of plutonium and americium geochemistry at the Hanford Site. The report integrates existing knowledge of the subsurface migration behavior of plutonium and americium at the Hanford Site with available information in the scientific literature regarding the geochemistry of plutonium and americium in systems that are environmentally relevant to the Hanford Site. As a part of the report, key research needs are identified and prioritized, with the ultimate goal of developing a science-based capability to quantitatively assess risk at sites contaminated with plutonium and americium at the Hanford Site and the impact of remediation technologies and closure strategies.

  1. Americium/Curium Disposition Life Cycle Planning Study

    SciTech Connect

    Jackson, W.N.; Krupa, J.; Stutts, P.; Nester, S.; Raimesch, R.

    1998-04-30

    At the request of the Department of Energy Savannah River Office (DOE- SR), Westinghouse Savannah River Company (WSRC) evaluated concepts to complete disposition of Americium and Curium (Am/Cm) bearing materials currently located at the Savannah River Site (SRS).

  2. Tributylphosphate Extraction Behavior of Bismuthate-Oxidized Americium

    SciTech Connect

    Mincher; Leigh R. Martin; Nicholas C. Schmitt

    2008-08-01

    Higher oxidation states of americium have long been known; however, options for their preparation in acidic solution are limited. The conventional choice, silver-catalyzed peroxydisulfate, is not useful at nitric acid concentrations above about 0.3 M. We investigated the use of sodium bismuthate as an oxidant for Am3+ in acidic solution. Room-temperature oxidation produced AmO2 2+ quantitatively, whereas oxidation at 80 °C produced AmO2+ quantitatively. The efficacy of the method for the production of oxidized americium was verified by fluoride precipitation and by spectroscopic absorbance measurements. We performed absorbance measurements using a conventional 1 cm cell for high americium concentrations and a 100 cm liquid waveguide capillary cell for low americium concentrations. Extinction coefficients for the absorbance of Am3+ at 503 nm, AmO2+ at 514 nm, and AmO2 2+ at 666 nm in 0.1 M nitric acid are reported. We also performed solvent extraction experiments with the hexavalent americium using the common actinide extraction ligand tributyl phosphate (TBP) for comparison to the other hexavalent actinides. Contact with 30% tributyl phosphate in dodecane reduced americium; it was nevertheless extracted using short contact times. The TBP extraction of AmO2 2+ over a range of nitric acid concentrations is shown for the first time and was found to be analogous to that of uranyl, neptunyl, and plutonyl ions.

  3. Speciation of americium in seawater and accumulation in the marine sponge Aplysina cavernicola.

    PubMed

    Maloubier, Melody; Michel, Hervé; Solari, Pier Lorenzo; Moisy, Philippe; Tribalat, Marie-Aude; Oberhaensli, François R; Dechraoui Bottein, Marie Yasmine; Thomas, Olivier P; Monfort, Marguerite; Moulin, Christophe; Den Auwer, Christophe

    2015-12-21

    The fate of radionuclides in the environment is a cause of great concern for modern society, seen especially in 2011 after the Fukushima accident. Among the environmental compartments, seawater covers most of the earth's surface and may be directly or indirectly impacted. The interaction between radionuclides and the marine compartment is therefore essential for better understanding the transfer mechanisms from the hydrosphere to the biosphere. This information allows for the evaluation of the impact on humans via our interaction with the biotope that has been largely undocumented up to now. In this report, we attempt to make a link between the speciation of heavy elements in natural seawater and their uptake by a model marine organism. More specifically, because the interaction of actinides with marine invertebrates has been poorly studied, the accumulation in a representative member of the Mediterranean coralligenous habitat, the sponge Aplysina cavernicola, was investigated and its uptake curve exposed to a radiotracer (241)Am was estimated using a high-purity Ge gamma spectrometer. But in order to go beyond the phenomenological accumulation rate, the speciation of americium(III) in seawater must be assessed. The speciation of (241)Am (and natural europium as its chemically stable surrogate) in seawater was determined using a combination of different techniques: Time-Resolved Laser-Induced Fluorescence (TRLIF), Extended X-ray Absorption Fine Structure (EXAFS) at the LIII edge, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and the resulting data were compared with the speciation modeling. In seawater, the americium(III) complex (as well as the corresponding europium complex, although with conformational differences) was identified as a ternary sodium biscarbonato complex, whose formula can be tentatively written as NaAm(CO3)2·nH2O. It is therefore this chemical form of americium that is

  4. Self-irradiation and oxidation effects on americium sesquioxide and Raman spectroscopy studies of americium oxides

    NASA Astrophysics Data System (ADS)

    Horlait, Denis; Caraballo, Richard; Lebreton, Florent; Jégou, Christophe; Roussel, Pascal; Delahaye, Thibaud

    2014-09-01

    Americium oxides samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, with an emphasis on their structural behavior under oxidation and self-irradiation. Raman spectra of americium dioxide (AmO2) and sesquioxide (Am2O3) were obtained for the first time. With the help of literature data on isostructural oxides, Raman signatures of Ia-3 C-type Am2O3 and P-3m1 A-type Am2O3 are identified. For AmO2, a clear band is noted at 390 cm-1. Its nature is compared to that of the other actinide dioxides. Am2O3 evolution under ambient conditions and against 241Am α self-irradiation was monitored by powder XRD. The sample, initially composed of A-type Am2O3 as major phase as well as C2/m B-type and C-type structures as minor phases, progressively oxidizes to Fm-3m AmO2-δ over a few months. On the basis of diffractogram refinements, evolutions of unit cell volumes caused by self-irradiation are also determined and discussed.

  5. Comparison of acid leachate and fusion methods to determine plutonium and americium in environmental samples

    SciTech Connect

    Smith, L.L.; Markun, F.; TenKate, T.

    1992-06-01

    The Analytical Chemistry Laboratory at Argonne National Laboratory performs radiochemical analyses for a wide variety of sites within the Department of Energy complex. Since the chemical history of the samples may vary drastically from site to site, the effectiveness of any analytical technique may also vary. This study compares a potassium fluoride-pyrosulfate fusion technique with an acid leachate method. Both normal and high-fired soils and vegetation samples were analyzed for both americium and plutonium. Results show both methods work well, except for plutonium in high-fired soils. Here the fusion method provides higher accuracy.

  6. The solvent extraction of americium(III) in HCl solutions by 2,6-bis[(diphenylphospino)methyl]pyridine N,P,P{prime}-trioxide

    SciTech Connect

    Bond, E.M.; Engelhardt, U.; Deere, T.P.; Rapko, B.M.; Paine, R.T.; FitzPatrick, J.R.

    1998-07-01

    The liquid/liquid extraction of Am(III) from hydrochloric acid solutions with chloroform solutions of 2,6-bis[(diphenylphosphino)methyl]pyridine N,P,P{prime}-trioxide (ENOPOPO) is described. ENOPOPO exhibits modest extraction ability for americium(III) (D{sub Am} = 2.2 at 5 M HCl) and can be efficiently back extracted from the organic phase at 0.1 M HCl. The ligand dependency data suggest that three ligand molecules are coordinated to the americium in the extraction complex. Additional aspects of the extraction mechanism are described.

  7. RCRA designation of discarded americium/beryllium sealed sources

    SciTech Connect

    Kirner, N.P.

    1994-09-01

    Many sealed sources containing americium and beryllium are used throughout construction, industry, and research, and will eventually require disposal. For planning purposes it is necessary to determine whether these sources, when disposed, constitute a mixed waste, i.e., a waste containing hazardous constituents regulated under the Resource Conservation and Recovery Act and radioactive constituents regulated under the Atomic Energy Act. Waste designation criteria contained in 40 CFR 261 are evaluated in detail in this report. It is determined that discarded americium/beryllium sealed sources do not contain any wastes listed in Subpart D of 40 CFR 261, nor do the discarded sources exhibit any hazardous characteristics. Therefore, it is concluded that discarded americium/beryllium sealed sources are not a mixed waste under regulations established by the US Environmental Protection Agency. Hazardous waste regulatory programs delegated to States, however, may have regulations that differ from those of the Federal government.

  8. PLUTONIUM-239 AND AMERICIUM-241 UPTAKE BY PLANTS FROM SOIL

    EPA Science Inventory

    Alfalfa was grown in soil contaminated with plutonium-239 dioxide (239PuO2) at a concentration of 29.7 nanocuries per gram (nCi/g). In addition to alfalfa, radishes, wheat, rye, and tomatoes were grown in soils contaminated with americium-241 nitrate (241Am(NO3)3) at a concentrat...

  9. SIMULTANEOUS DETERMINATION OF AMERICIUM AND CURIUM IN SOIL

    EPA Science Inventory

    A method is presented for the routine determination of americium and curium in 10 g of soil. The soil is dissolved with a mixture of nitric acid and hydrofluoric acid. Insoluble sulfates and phosphates are metathesized with boiling sodium hydroxide solutions. Plutonium and iron a...

  10. Ingestion Pathway Transfer Factors for Plutonium and Americium

    SciTech Connect

    Blanchard, A.

    1999-07-28

    Overall transfer factors for major ingestion pathways are derived for plutonium and americium. These transfer factors relate the radionuclide concentration in a given foodstuff to deposition on the soil. Equations describing basic relationships consistent with Regulatory Guide 1.109 are followed. Updated values and coefficients from IAEA Technical Reports Series No. 364 are used when a available. Preference is given to using factors specific to the Savannah River Site.

  11. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, John R.; Dunn, Jerry G.; Avens, Larry R.

    1987-01-01

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF.sub.4 is not further oxidized to AmF.sub.6 by the application of O.sub.2 F at room temperature, while plutonium compounds present in the americium sample are fluorinated to volatile PuF.sub.6, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride.

  12. Method for removal of plutonium impurity from americium oxides and fluorides

    DOEpatents

    FitzPatrick, J.R.; Dunn, J.G.; Avens, L.R.

    1987-02-13

    Method for removal of plutonium impurity from americium oxides and fluorides. AmF/sub 4/ is not further oxidized to AmF/sub 6/ by the application of O/sub 2/F at room temperature thereto, while plutonium compounds present in the americium sample are fluorinated to volatile PuF/sub 6/, which can readily be separated therefrom, leaving the purified americium oxides and/or fluorides as the solid tetrafluoride thereof.

  13. AMERICIUM SEPARATIONS FROM NITRIC ACID PROCESS EFFLUENT STREAMS

    SciTech Connect

    M. BARR; G. JARVINEN; ET AL

    2000-08-01

    The aging of the US nuclear stockpile presents a number of challenges, including the ever-increasing radioactivity of plutonium residues from {sup 241}Am. Minimization of this weak gamma-emitter in process and waste solutions is desirable to reduce both worker exposure and the effects of radiolysis on the final waste product. Removal of americium from plutonium nitric acid processing effluents, however, is complicated by the presence of large.quantities of competing metals, particularly Fe and Al, and-strongly oxidizing acidic solutions. The reprocessing operation offers several points at which americium removal maybe attempted, and we are evaluating two classes of materials targeted at different steps in the process. Extraction chromatography resin materials loaded with three different alkylcarbamoyl phosphinates and phosphine oxides were accessed for Am removal efficiency and Am/Fe selectivity from 1-7 molar nitric acid solutions. Commercial and experimental mono- and bifunctional anion-exchange resins were evaluated for total alpha-activity removal from post-evaporator solutions whose composition, relative to the original nitric acid effluent, is reduced in acid and greatly increased in total salt content. With both classes of materials, americium/total alpha emission removal is sufficient to meet regulatory requirements even under sub-optimal conditions. Batch distribution coefficients, column performance data, and the effects of Fe-masking agents will be presented.

  14. EFFECT OF COMPOSITION OF SELECTED GROUNDWATERS FROM THE BASIN AND RANGE PROVINCE ON PLUTONIUM, NEPTUNIUM, AND AMERICIUM SPECIATION.

    USGS Publications Warehouse

    Rees, Terry F.; Cleveland, Jess M.; Nash, Kenneth L.

    1984-01-01

    The speciation of plutonium, neptunium, and americium was determined in groundwaters from four sources in the Basin and Range Province: the lower carbonate aquifer, Nevada Test Site (NTS) (Crystal Pool); alluvial fill, Frenchman Flat, NTS (well 5C); Hualapai Valley, Arizona (Red Lake south well); and Tularosa Basin, New Mexico (Rentfrow well). The results were interpreted to indicate that plutonium and, to a lesser extent, neptunium are least soluble in reducing groundwaters containing a large concentration of sulfate ion and a small concentration of strongly complexing anions. The results further emphasize the desirability of including studies such as this among the other site-selection criteria for nuclear waste repositories.

  15. Neptunium and americium speciation in selected basalt, granite, shale, and tuff ground waters

    USGS Publications Warehouse

    Cleveland, J.M.; Rees, T.F.; Nash, K.L.

    1983-01-01

    Neptunium and americium are relatively insoluble in ground waters containing high sulfate concentrations, particularly at 90??C. The insoluble neptunium species is Np(IV); hence reducing waters should enhance its formation. Americium can exist only in the trivalent state under these conditions, and its solubility also should be representative of that of curium.

  16. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...

  17. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  18. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  19. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...

  20. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...

  1. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Americium-241 and radium-226 in the form of calibration or... BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a..., americium-241 or radium-226 in the form of calibration or reference sources: (1) Any person in a...

  2. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...

  3. 10 CFR 32.57 - Calibration or reference sources containing americium-241 or radium-226: Requirements for license...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Calibration or reference sources containing americium-241... americium-241 or radium-226: Requirements for license to manufacture or initially transfer. An application... containing americium-241 or radium-226, for distribution to persons generally licensed under § 31.8 of...

  4. 10 CFR 32.102 - Schedule C-prototype tests for calibration or reference sources containing americium-241 or...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... sources containing americium-241 or radium-226. 32.102 Section 32.102 Energy NUCLEAR REGULATORY COMMISSION... americium-241 or radium-226. An applicant for a license under § 32.57 shall, for any type of source which is designed to contain more than 0.185 kilobecquerel (0.005 microcurie) of americium-241 or...

  5. High pressure phase transition and elastic properties of americium telluride

    NASA Astrophysics Data System (ADS)

    Aynyas, Mahendra; Rukmangad, Aditi; Arya, B. S.; Sanyal, S. P.

    2013-06-01

    The structural and elastic properties of Americium Telluride (AmTe) have been investigated by using a modified inter-ionic potential theory (MIPT). This theory is capable of explaining first order phase transition with a crystallographic change NaCl to CsCl structure for this compound. The values of optimized lattice constant, phase transition pressure, zero pressure bulk modulus and second order elastic constants (C11, C44) agree well with their corresponding experimental data. Debye temperature (θD) is also calculated for this compound for the first time.

  6. Passive field monitoring of plutonium and americium in soil

    SciTech Connect

    Gammage, R.B.; Meyer, K.E.; Dudney, C.S.

    1994-12-31

    The authors` progress is described in applying passive alpha track detectors (ATDS) and electret ion chambers (EICS) to in-situ field monitoring of soils contaminated with particulate plutonium and americium at a desert site. By varying the exposure times, from a few minutes to about one day, they quantitatively measured alpha activity varying between {approximately} 100 pCi/g and {approximately} 100 nCi/g. Suggested applications are definition of the boundaries of contamination zones and verification that post-remediated soils are below release limits.

  7. A Density Functional Study of the Americium (001) Surface

    NASA Astrophysics Data System (ADS)

    Gao, Da; Ray, Asok Kumar

    2006-03-01

    Electronic structure properties of the fcc americium (001) surface, modeled by periodically repeated fcc Am (001) surface slabs, have been studied with the full-potential linearized augmented plane wave (FP-LAPW) method. The alternative basis set APW+lo is used inside the atomic spheres for chemically important orbitals that are difficult to converge, whereas LAPW is used for others. The core states are treated fully relativistically and for valence states, two levels of treatments are implemented: (1) a scalar relativistic scheme including the mass-velocity correction and the Darwin s-shift and (2) a fully relativistic scheme with spin-orbit coupling included in a second variational treatment using the scalar-relativistic eigenfunctions as basis. Our results indicate that the ground state of Am (001) surface is anti-ferromagnetic. The quantum size effects in the surface energies and the work functions of the (001) fcc americium ultra thin films (UTF) have been examined up to seven layers. In addition, the Am (001) surface properties are compared with our earlier study of the Am (111) surface.

  8. Lifetime followup of the 1976 americium accident victim: (Final report)

    SciTech Connect

    Breitenstein, B.D. Jr.; Palmer, H.E.

    1988-05-01

    This report describes the 11 year medical course of Harold R. McCluskey, a Hanford nuclear chemical operator, who, at age 64, was involved in an accident in an americium recovery facility in August 1976. As a result of the accident, he was heavily contaminated with americium (Am-241), sustained a substantial internal deposition of this isotope, and was burned with concentrated nitric acid and injured by flying debris about the face and neck. The immediate and long-term medical care is summarized, including decontamination procedures, chelation therapy, and routine and special clinical laboratories studies. The estimates of the operator's Am-241 deposition, post accident and during the remainder of his life and the special techniques and equipment used to make the estimates, are reported. Post-accident, the total amount of Am-241 excreted in his urine and feces was 41 MBq (1.1 mCi). He died of complications of chronic coronary artery disease on August 17, 1987. 20 refs., 2 figs.

  9. Americium Transmutation Feasibility When Used as Burnable Absorbers - 12392

    SciTech Connect

    Barbaras, Sean A.; Knight, Travis W.

    2012-07-01

    The use of plutonium in Mixed Oxide (MOX) fuel in traditional Pressurized Water Reactor (PWR) assemblies leads to greater americium production which is not addressed in MOX recycling. The transuranic nuclides (TRU) contribute the most to the radiotoxicity of nuclear waste and a reduction of the TRU stockpile would greatly reduce the overall radiotoxicity of what must be managed. Am-241 is a TRU of particular concern because it is the dominant contributor of total radiotoxicity for the first 1000 years in a repository. This research explored the feasibility of transmuting Am-241 by using varying amounts in MOX rods being used in place of burnable absorbers and evaluated with respect to the impact on incineration and transmutation of transuranics in MOX fuel as well as the impact on safety. This research concludes that the addition of americium to a non-uniform fuel assembly is a viable method of transmuting Am-241, holding down excess reactivity in the core while serving as a burnable poison, as well as reducing the radiotoxicity of high level waste that must be managed. The use of Am/MOX hybrid fuel assemblies to transmute americium was researched using multiple computer codes. Am-241 was shown in this study to be able to hold down excess reactivity at the beginning of cycle and shape the power distribution in the core with assemblies of varying americium content loaded in a pattern similar to the traditional use of assemblies with varying amounts of burnable absorbers. The feasibility, safety, and utility of using americium to create an Am/MOX hybrid non-uniform core were also evaluated. The core remained critical to a burnup of 22,000 MWD/MTM. The power coefficient of reactivity as well as the temperature and power defects were sufficiently negative to provide a prompt feedback mechanism in case of a transient and prevent a power excursion, thus ensuring inherent safety and protection of the core. As shown here as well as many other studies, this non

  10. The 1976 Hanford Americium Accident: Then and Now

    SciTech Connect

    Carbaugh, Eugene H.

    2013-10-02

    The 1976 chemical explosion of an 241Am ion exchange column at a Hanford Site waste management facility resulted in the extreme contamination of a worker with 241Am, nitric acid and debris. The worker underwent medical treatment for acid burns, as well as wound debridement, extensive personal skin decontamination and long-term DTPA chelation therapy for decorporation of americium-241. Because of the contamination levels and prolonged decontamination efforts, care was provided for the first three months at the unique Emergency Decontamination Facility with gradual transition to the patient’s home occurring over another two months. The medical treatment, management, and dosimetry of the patient have been well documented in numerous reports and journal articles. The lessons learned with regard to patient treatment and effectiveness of therapy still form the underlying philosophy of treatment for contaminated injuries. Changes in infrastructure and facilities as well as societal expectations make for interesting speculation as to how responses might differ today.

  11. Separation of americium from curium by oxidation and ion exchange.

    PubMed

    Burns, Jonathan D; Shehee, Thomas C; Clearfield, Abraham; Hobbs, David T

    2012-08-21

    Nuclear energy has the potential to be a clean alternative to fossil fuels, but in order for it to play a major role in the US, many questions about the back end of the fuel cycle must be addressed. One of these questions is the difficult separation of americium from curium. Here, we report the oxidation of Am in two systems, perchloric acid and nitric acid and the affect of changing the acid has on the oxidation. K(d) values were observed and a direct separation factor was calculated and was seen to be as high as 20 for four metal(IV) pillared phosphate phosphonate inorganic organic hybrid ion exchange materials. These ion exchangers are characterized by very low selectivity for cations with low charge but extremely high uptake of ions of high charge. PMID:22827724

  12. Monte Carlo modeling of spallation targets containing uranium and americium

    NASA Astrophysics Data System (ADS)

    Malyshkin, Yury; Pshenichnov, Igor; Mishustin, Igor; Greiner, Walter

    2014-09-01

    Neutron production and transport in spallation targets made of uranium and americium are studied with a Geant4-based code MCADS (Monte Carlo model for Accelerator Driven Systems). A good agreement of MCADS results with experimental data on neutron- and proton-induced reactions on 241Am and 243Am nuclei allows to use this model for simulations with extended Am targets. It was demonstrated that MCADS model can be used for calculating the values of critical mass for 233,235U, 237Np, 239Pu and 241Am. Several geometry options and material compositions (U, U + Am, Am, Am2O3) are considered for spallation targets to be used in Accelerator Driven Systems. All considered options operate as deep subcritical targets having neutron multiplication factor of k∼0.5. It is found that more than 4 kg of Am can be burned in one spallation target during the first year of operation.

  13. Plutonium, americium, and neptunium speciation in selected groundwaters

    USGS Publications Warehouse

    Cleveland, J.M.; Rees, T.F.; Nash, K.L.

    1985-01-01

    Speciation was determined at 25 and 90 degree C in four groundwaters from diverse sources: the Sparta aquifer in Louisiana, near the Vacherie salt dome; Mansfield No. 2 well in the Palo Duro Basin, Texas; the Stripa mine in Sweden; and the Waste Isolation Pilot Plant in New Mexico. Neptunium generally was soluble in all waters and was present exclusively as Np(V) and Np(VI), regardless of initial oxidation state. The results indicated that plutonium and neptunium solubilities were determined by the oxidation-reduction properties of the waters, i. e. , their abilities to convert these elements to soluble oxidation states. This was not the case for americium, however; Am(IV) was not detected, and the solubility of this element was determined entirely by the chemical properties of Am(III).

  14. 1976 Hanford americium exposure incident: in vivo measurements

    SciTech Connect

    Palmer, H.E.; Rieksts, G.A.; Icayan, E.E.

    1982-01-01

    Detailed external measurement were made of internally deposited /sup 241/Am in a nuclear chemical operator involved in an americium exposure accident at the Hanford plant. Despite some interference from high-level external contamination, quantitative measurements of the /sup 241/Am content in the lung, liver, and bones were made starting on the third day after the accident. The rate of excretion of /sup 241/Am from these organs was determined. The /sup 241/Am embedded in the skin of the face and head was carefully mapped. The distribution over the total length of the body was also determined. Linear and rectilinear scanners, gamma cameras, large and small scintillation detectors, proportional counters, and Si(Li) and intrinsic germanium detectors were used to evaluate the internal deposition. Methods of calibration for quantitative measurement included simulation of the /sup 241/Am activity in both phantom and cadaver parts.

  15. Relativistic density functional theory modeling of plutonium and americium higher oxide molecules.

    PubMed

    Zaitsevskii, Andréi; Mosyagin, Nikolai S; Titov, Anatoly V; Kiselev, Yuri M

    2013-07-21

    The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6-8, are determined. In all cases, molecular geometries of americium and mixed plutonium-americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable. PMID:23883027

  16. Relativistic density functional theory modeling of plutonium and americium higher oxide molecules

    NASA Astrophysics Data System (ADS)

    Zaitsevskii, Andréi; Mosyagin, Nikolai S.; Titov, Anatoly V.; Kiselev, Yuri M.

    2013-07-01

    The results of electronic structure modeling of plutonium and americium higher oxide molecules (actinide oxidation states VI through VIII) by two-component relativistic density functional theory are presented. Ground-state equilibrium molecular structures, main features of charge distributions, and energetics of AnO3, AnO4, An2On (An=Pu, Am), and PuAmOn, n = 6-8, are determined. In all cases, molecular geometries of americium and mixed plutonium-americium oxides are similar to those of the corresponding plutonium compounds, though chemical bonding in americium oxides is markedly weaker. Relatively high stability of the mixed heptoxide PuAmO7 is noticed; the Pu(VIII) and especially Am(VIII) oxides are expected to be unstable.

  17. Oxidative Alkaline leaching of Americium from simulated high-level nuclear waste sludges

    SciTech Connect

    Reed, Wendy A.; Garnov, Alexander Yu.; Rao, Linfeng; Nash, Kenneth L.; Bond, Andrew H.

    2004-01-23

    Oxidative alkaline leaching has been proposed to pre-treat the high-level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or non-radioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO{sub 4}, BiPO{sub 4 modified}, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO{sub 4} sludge < Redox sludge < PUREX sludge. The data are most consistent with oxidation of Am{sup 3+} in the sludge to either AmO{sub 2}{sup +} or AmO{sub 2}{sup 2+} in solution. Though neither of these species is expected to exhibit long-term stability in solution, the potential for mobilization of americium from sludge samples would have to be accommodated in the design of any oxidative leaching process for real sludge samples.

  18. Plutonium and americium recovery from spent molten-salt-extraction salts with aluminum-magnesium alloys

    SciTech Connect

    Cusick, M.J.; Sherwood, W.G.; Fitzpatrick, R.F.

    1984-04-23

    Development work was performed to determine the feasibility of removing plutonium and americium from spent molten-salt-extraction (MSE) salts using Al-Mg alloys. If the product buttons from this process are compatible with subsequent aqueous processing, the complex chloride-to-nitrate aqueous conversion step which is presently required for these salts may be eliminated. The optimum alloy composition used to treat spent 8 wt % MSE salts in the past yielded poor phase-disengagement characteristics when applied to 30 mol % salts. After a limited investigation of other alloy compositions in the Al-Mg-Pu-Am system, it was determined that the Al-Pu-Am system could yield a compatible alloy. In this system, experiments were performed to investigate the effects of plutonium loading in the alloy, excess magnesium, age of the spent salt on actinide recovery, phase disengagement, and button homogeneity. Experimental results indicate that 95 percent plutonium recoveries can be attained for fresh salts. Further development is required for backlog salts generated prior to 1981. A homogeneous product alloy, as required for aqueous processing, could not be produced.

  19. Density of simulated americium/curium melter feed solution

    SciTech Connect

    Rudisill, T.S.

    1997-09-22

    Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to Oak Ridge National Laboratory and use in heavy isotope production programs. Prior to vitrification, a series of in-tank oxalate precipitation and nitric/oxalic acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Following nitric acid dissolution and oxalate destruction, the solution will be denitrated and evaporated to a dissolved solids concentration of approximately 100 g/l (on an oxide basis). During the Am/Cm vitrification, an airlift will be used to supply the concentrated feed solution to a constant head tank which drains through a filter and an in-line orifice to the melter. Since the delivery system is sensitive to the physical properties of the feed, a simulated solution was prepared and used to measure the density as a function of temperature between 20 to 70{degrees} C. The measured density decreased linearly at a rate of 0.0007 g/cm3/{degree} C from an average value of 1.2326 g/cm{sup 3} at 20{degrees} C to an average value of 1.1973g/cm{sup 3} at 70{degrees} C.

  20. Electronic, mechanical, and thermodynamic properties of americium dioxide

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Yang, Yu; Zheng, Fawei; Wang, Bao-Tian; Zhang, Ping

    2013-10-01

    By performing density functional theory (DFT) +U calculations, we systematically study the electronic, mechanical, tensile, and thermodynamic properties of AmO2. It is found that the chemical bonding character in AmO2 is similar to that in PuO2, with smaller charge transfer and stronger covalent interactions between americium and oxygen atoms. The stress-strain relationship of AmO2 is examined along the three low-index directions, showing that the [1 0 0] and [1 1 1] directions are the strongest and weakest tensile directions, respectively, but the theoretical tensile strengths of AmO2 are smaller than those of PuO2. The phonon dispersion curves of AmO2 are calculated and the heat capacities as well as lattice expansion curve are subsequently determined. The lattice thermal conductivity of AmO2 is further evaluated and compared with attainable experiments. Our present work integrally reveals various physical properties of AmO2 and can be referenced for technological applications of AmO2 based materials.

  1. Environmental impact of a teratogenic actinide: a case study of americium-241

    SciTech Connect

    Wang, J.; Yang, J.Y.

    1985-10-16

    Americium-241 is widely used as a radiation source, but it also has some potential risk if taken into the body. Although the radiotoxicity of americium-241 is small compared to other transuranic actinides, its effects on the reproductive system and on development of the placenta are more damaging than the effects of plutonium-239. A previous report based on a worst-case scenario involving a hypothetical fire accident in a contaminated facility indicated that there could have been a significant impact on nearby residents from a unit release of americium-241 via atmospheric dispersion. However, because the facility is located in a rural region where most drinking water supplies are drawn from private wells, it is believed that deposition of americium-241 from the atmosphere might also have impacts via the groundwater pathway by infiltration of rainwater. In this analysis, a three-dimensional analytical mathematical model is used to assess several aspects of americium-241 contamination of groundwater, including radioactive transformation, advection, dispersion, and soil sorption. Simulation results indicate that no significant radiological impacts would occur to the nearby residents via the groundwater pathway. 15 refs., 2 figs., 2 tabs.

  2. Oxidation of trivalent americium, curium, and terbium in solutions of sodium paratungstate

    SciTech Connect

    Fedoseev, A.M.; Krot, N.N.; Spitsyn, V.I.

    1986-09-01

    In the further study of the behavior of the actinides and lanthanides in solutions of heteropoly-compounds, the authors succeed in finding conditions under which the formation of americium (IV), curium (IV), and terbium (IV) decatungstates is observed. The results of experiments along this line are brieflyoutlined. It is shown that trivalent americium, curium, and terbium are oxidzed by heating with persulfate not only in solutions ofunsaturated heteropolytungstates but also in solutions of isopoly-compounds of tungsten. However, the degree of oxidation of curium and terbium (III) in the latter case is appreciably lover. In addition to persulfate ions, ozone can be used for the oxidation of americium (III) in solutions of sodium paratungstate.

  3. Americium purification by a combined anion exchange and bidentate organophosphorus solvent extraction process. [Patent application

    SciTech Connect

    Navratil, J.D.; Martella, L.L.

    1981-04-10

    Americium is separated from mixtures containing plutonium, other actinides, and other non-lanthamide impurities, by a combined process of anion exchange resin sorption to remove plutonium, and a bidentate organophosphorus solvent extraction of americium of the anion exchange resin effluent. Dihexyl-N,N-diethylcarbamylmethylenephosphonate is a preferred solvent. The initial mixture may be subjected to a cation exchange operation to remove monovalent impurities. The process is especially effective when aluminum, zinc, lead, and copper are present in significant quantities in the original mixture.

  4. Synthesis of functionalised BTPhen derivatives - effects on solubility and americium extraction.

    PubMed

    Higginson, Matthew A; Kyle, Nichola D; Marsden, Olivia J; Thompson, Paul; Livens, Francis R; Heath, Sarah L

    2015-10-01

    Separation of the minor actinides (Am/Cm) from spent nuclear fuel post-PUREX process is expected to play a key part in new reprocessing methodologies. To date, a number of selective americium extractants from the BTPhen ligand family have been identified. In this investigation, we synthesise 24 novel BTPhens with additional functionality to determine the effects on solubilities and americium extraction capabilities. The data obtained will allow for tuning of steric/electronic properties of BTPhens in order to assist future extractant design. PMID:26331995

  5. Americium biokinetics in benthic organisms as a function of feeding mode

    SciTech Connect

    Fowler, S.W.; Carvalho, F.P.

    1985-12-01

    Transuranic radionuclides in the environment have arisen from nuclear weapons testing, release from nuclear waste reprocessing plants and accidents with nuclear devices. Although at present the plutonium inventory is greater than that of any other transuranium element, the americium inventory will continue to increase due to the in situ decay of SU Pu. Furthermore some studies have demonstrated that americium is more bioavailable than plutonium in aquatic environments. The authors therefore undertook to delineate, experimentally, the biokinetics of SU Am in some marine benthic species with very different feeding-digestion strategies, which hitherto have not been studied in any detail in a radioecological context.

  6. Intramolecular sensitization of americium luminescence in solution: Shining light on short-lived forbidden 5f transitions

    SciTech Connect

    Sturzbecher-Hoehne, M.; Yang, P.; D'Aleo, A.; Abergel, R. J.

    2016-01-01

    In this study, the photophysical properties and solution thermodynamics of water soluble trivalent americium (AmIII) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for AmIII, generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10–3 to 10–2%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of AmIII assigned to the 5D17F1 f–f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these AmIII complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.

  7. Intramolecular sensitization of americium luminescence in solution: Shining light on short-lived forbidden 5f transitions

    DOE PAGESBeta

    Sturzbecher-Hoehne, M.; Yang, P.; D'Aleo, A.; Abergel, R. J.

    2016-01-01

    In this study, the photophysical properties and solution thermodynamics of water soluble trivalent americium (AmIII) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for AmIII, generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10–3 to 10–2%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of AmIII assigned to the 5D1 → 7F1 f–f transition was exploited to characterize the high proton-independent stability of the complex formedmore » with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these AmIII complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.« less

  8. Intramolecular sensitization of americium luminescence in solution: shining light on short-lived forbidden 5f transitions.

    PubMed

    Sturzbecher-Hoehne, M; Yang, P; D'Aléo, A; Abergel, R J

    2016-06-14

    The photophysical properties and solution thermodynamics of water soluble trivalent americium (Am(III)) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for Am(III), generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10(-3) to 10(-2)%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of Am(III) assigned to the (5)D1 → (7)F1 f-f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these Am(III) complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects. PMID:26961598

  9. National low-level waste management program radionuclide report series, Volume 14: Americium-241

    SciTech Connect

    Winberg, M.R.; Garcia, R.S.

    1995-09-01

    This report, Volume 14 of the National Low-Level Waste Management Program Radionuclide Report Series, discusses the radiological and chemical characteristics of americium-241 ({sup 241}Am). This report also includes discussions about waste types and forms in which {sup 241}Am can be found and {sup 241}Am behavior in the environment and in the human body.

  10. Separation of Americium in High Oxidation States from Curium Utilizing Sodium Bismuthate.

    PubMed

    Richards, Jason M; Sudowe, Ralf

    2016-05-01

    A simple separation of americium from curium would support closure of the nuclear fuel cycle, assist in nuclear forensic analysis, and allow for more accurate measurement of neutron capture properties of (241)Am. Methods for the separation of americium from curium are however complicated and time-consuming due to the similar chemical properties of these elements. In this work a novel method for the separation of americium from curium in nitric acid media was developed using sodium bismuthate to perform both the oxidation and separation. Sodium bismuthate is shown to be a promising material for performing a simple and rapid separation. Curium is more strongly retained than americium on the undissolved sodium bismuthate at nitric acid concentrations below 1.0 M. A separation factor of ∼90 was obtained in 0.1 M nitric acid. This separation factor is achieved within the first minute of contact and is maintained for at least 2 h of contact. Separations using sodium bismuthate were performed using solid-liquid extraction as well as column chromatography. PMID:27079565

  11. Understanding the Chemistry of Uncommon Americium Oxidation States for Application to Actinide/Lanthanide Separations

    SciTech Connect

    Leigh Martin; Bruce J. Mincher; Nicholas C. Schmitt

    2007-09-01

    A spectroscopic study of the stability of Am(V) and Am(VI) produced by oxidizing Am(III) with sodium bismuthate is presented, varying the initial americium concentration, temperature and length of the oxidation was seen to have profound effects on the resultant solutions.

  12. Apparatus for fabrication of americium- beryllium neutron sources prevents capsule contamination

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Van Loom, J. A.

    1967-01-01

    Modified gloved enclosure is used to fill a capsule with a mixture of americium and beryllium radioactive powders to seal weld the opening, and to test it for leaks. It contains a horizontal partition, vortex mixer, mounting press, welder, test vessel, and radiation shielding to prevent surface contamination.

  13. Environmental impacts of the release of a transuranic actinide, americium-241, from a contaminated facility

    SciTech Connect

    Want, J.; Merry-Libby, P.

    1985-10-29

    Americium-241 is widely used as a radiation source, but it also has some potential risk if taken into the body because of its high dose conversion factor. Although the radiotoxicity of americium-241 is small compared to other transuranic actinides, its effects on the reproductive system and on development of the placenta are more damaging than the effects of plutonium-239. In Ohio, a gemologist's laboratory was contaminated with americium-241. Prior to decontamination of the laboratory, potential radiological impacts to the surrounding environment were assessed. A hypothetical fire accident resulting in a unit release (1 curie) was assumed. Potential radiological impacts were simulated using an atmospheric dispersion and dosimetry model with local meteorological data, population census data, and detailed information regarding the neighborhood. The results indicate that there could have been a significant impact on nearby residents from americium-241 via atmospheric dispersion if a major catastrophic release had occurred prior to contamination and decommissioning of the laboratory. 14 refs., 3 figs., 2 tabs.

  14. Chemical Speciation of Strontium, Americium, and Curium in High Level Waste: Predictive Modeling of Phase Partitioning During Tank Processing

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.; Campbell, James A.

    1999-06-01

    In this research program, Pacific Northwest National Laboratory (PNNL) and Florida State University (FSU) are investigating the speciation of strontium and americium/curium in the presence of selected organic chelating agents (ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl) aethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), and iminodiacetic acid (IDA)) over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high-level waste tanks. The project is composed of integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metal-chelate systems. This fundamental information is then used to develop thermodynamic models, which allow the prediction of changes in chemical speciation and solubility that can occur in response to changes in tank processing conditions. In this way, we can develop new approaches that address fundamental problems in aqueous speciation and at the same time provide useful and practical information needed for tank processing.

  15. The 5f localization/delocalization in square and hexagonal americium monolayers: a FP-LAPW electronic structure study

    NASA Astrophysics Data System (ADS)

    Gao, D.; Ray, A. K.

    2006-04-01

    The electronic and geometrical properties of bulk americium and square and hexagonal americium monolayers have been studied with the full-potential linearized augmented plane wave (FP-LAPW) method. The effects of several common approximations are examined: (1) non-spin polarization (NSP) vs. spin polarization (SP); (2) scalar-relativity (no spin-orbit coupling (NSO)) vs. full-relativity (i.e., with spin-orbit (SO) coupling included); (3) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that both spin polarization and spin orbit coupling play important roles in determining the geometrical and electronic properties of americium bulk and monolayers. A compression of both americium square and hexagonal monolayers compared to the americium bulk is also observed. In general, the LDA is found to underestimate the equilibrium lattice constant and give a larger total energy compared to the GGA calculations. While spin orbit coupling shows a similar effect on both square and hexagonal monolayer calculations regardless of the model, GGA versus LDA, an unusual spin polarization effect on both square and hexagonal monolayers is found in the LDA results as compared with the GGA results. The 5f delocalization transition of americium is employed to explain our observed unusual spin polarization effect. In addition, our results at the LDA level of theory indicate a possible 5f delocalization could happen in the americium surface within the same Am II (fcc crystal structure) phase, unlike the usually reported americium 5f delocalization which is associated with crystal structure change. The similarities and dissimilarities between the properties of an Am monolayer and a Pu monolayer are discussed in detail.

  16. 10 CFR 31.8 - Americium-241 and radium-226 in the form of calibration or reference sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Americium-241 and radium-226 in the form of calibration or reference sources. 31.8 Section 31.8 Energy NUCLEAR REGULATORY COMMISSION GENERAL DOMESTIC LICENSES FOR BYPRODUCT MATERIAL § 31.8 Americium-241 and radium-226 in the form of calibration or reference sources. (a) A general license is issued to...

  17. Final Radiological Assessment of External Exposure for CLEAR-Line Americium Recovery Operations

    SciTech Connect

    Davis, Adam C.; Belooussova, Olga N.; Hetrick, Lucas Duane

    2014-11-12

    Los Alamos National Laboratory is currently planning to implement an americium recovery program. The americium, ordinarily isotopically pure 241Am, would be extracted from existing Pu materials, converted to an oxide and shipped to support fabrication of americium oxide-beryllium neutron sources. These operations would occur in the currently proposed Chloride Extraction and Actinide Recovery (CLEAR) line of glove boxes. This glove box line would be collocated with the currently-operational Experimental Chloride Extraction Line (EXCEL). The focus of this document is to provide an in-depth assessment of the currently planned radiation protection measures and to determine whether or not further design work is required to satisfy design-goal and ALARA requirements. Further, this document presents a history of americium recovery operations in the Department of Energy and high-level descriptions of the CLEAR line operations to provide a basis of comparison. Under the working assumptions adopted by this study, it was found that the evaluated design appears to mitigate doses to a level that satisfies the ALARA-in-design requirements of 10 CFR 835 as implemented by the Los Alamos National Laboratory procedure P121. The analyses indicate that extremity doses would also meet design requirements. Dose-rate calculations were performed using the radiation transport code MCNP5 and doses were estimated using a time-motion study developed in consort with the subject matter expert. A copy of this report and all supporting documentation are located on the Radiological Engineering server at Y:\\Rad Engineering\\2013 PROJECTS\\TA-55 Clear Line.

  18. Solid-liquid separation of oxidized americium from fission product lanthanides

    NASA Astrophysics Data System (ADS)

    Shehee, T. C.; Martin, L. R.; Nash, K. L.

    2010-03-01

    The separation of americium from the lanthanides and curium is a requirement if transmutation of americium is to be performed in advanced nuclear fuel cycles. Oxidation of Am3+ to AmO2+ or AmO22+ may allow separation of Am from Ln and Cm in one step, since the lanthanides and curium do not have higher oxidation states as accessible. Two possible solid-liquid separation methods have been developed to address this difficult separation. Under acidic conditions using oxone or persulfate, the oxidation and retention of tracer Am in the aqueous phase has been observed with a separation factor of 11 ± 1. Most of these studies have been conducted using 237NpO2(NO3), 233UO2(NO3)2, 238Pu(NO3)4 and 241Am(NO3)3 at radiotracer concentrations. Lanthanides precipitate as the sodium or potassium europium double sulfate salt. Under basic conditions, ozone oxidation of Am(CO3)OH(s) solubilizes Am from a lanthanide carbonate hydroxide solid phase to the aqueous phase as the AmO2(CO3)34-or AmO2(CO3)35- species. For the ozone oxidation of the americium tracer a separation factor of 1.6 ± 0.8 and 47 ± 2 for the oxidation/separation in Na2CO3 and NaHCO3 respectively.

  19. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    SciTech Connect

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22/sup 0/C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90/sup 0/C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22/sup 0/C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables.

  20. Fabrication of uranium-americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    NASA Astrophysics Data System (ADS)

    Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Lebreton, F.; Horlait, D.; Bisel, I.; Blanchart, P.; Ayral, A.

    2014-10-01

    Mixed uranium-americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U0.9Am0.1O2±δ is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U0.9Am0.1O2±δ. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.

  1. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    SciTech Connect

    Degueldre, Claude Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O₂ lattice in an irradiated (60 MW d kg⁻¹) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (~0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am³⁺ species within an [AmO₈]¹³⁻ coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix. - Graphical abstract: Americium LIII XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 μm×300 μm beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO₂ matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: • Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. • The americium redox state as determined from XAS data of irradiated fuel material was Am(III). • In the sample, the Am³⁺ face an AmO₈¹³⁻coordination environment in the (Pu,U)O₂ matrix. • The americium dioxide is reduced by the uranium dioxide matrix.

  2. LIBS Spectral Data for a Mixed Actinide Fuel Pellet Containing Uranium, Plutonium, Neptunium and Americium

    SciTech Connect

    Judge, Elizabeth J.; Berg, John M.; Le, Loan A.; Lopez, Leon N.; Barefield, James E.

    2012-06-18

    Laser-induced breakdown spectroscopy (LIBS) was used to analyze a mixed actinide fuel pellet containing 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2}. The preliminary data shown here is the first report of LIBS analysis of a mixed actinide fuel pellet, to the authors knowledge. The LIBS spectral data was acquired in a plutonium facility at Los Alamos National Laboratory where the sample was contained within a glove box. The initial installation of the glove box was not intended for complete ultraviolet (UV), visible (VIS) and near infrared (NIR) transmission, therefore the LIBS spectrum is truncated in the UV and NIR regions due to the optical transmission of the window port and filters that were installed. The optical collection of the emission from the LIBS plasma will be optimized in the future. However, the preliminary LIBS data acquired is worth reporting due to the uniqueness of the sample and spectral data. The analysis of several actinides in the presence of each other is an important feature of this analysis since traditional methods must chemically separate uranium, plutonium, neptunium, and americium prior to analysis. Due to the historic nature of the sample fuel pellet analyzed, the provided sample composition of 75% UO{sub 2}/20% PuO{sub 2}/3% AmO{sub 2}/2% NpO{sub 2} cannot be confirm without further analytical processing. Uranium, plutonium, and americium emission lines were abundant and easily assigned while neptunium was more difficult to identify. There may be several reasons for this observation, other than knowing the exact sample composition of the fuel pellet. First, the atomic emission wavelength resources for neptunium are limited and such techniques as hollow cathode discharge lamp have different dynamics than the plasma used in LIBS which results in different emission spectra. Secondly, due to the complex sample of four actinide elements, which all have very dense electronic energy levels, there may be reactions and

  3. Production of films of uranium and americium compounds by thermal decomposition of volatile β-diketonates

    NASA Astrophysics Data System (ADS)

    Danilin, I. D.; Kartushin, V. D.; Pilipenko, N. V.; Abramycheva, I. D.; Vesnovskii, S. P.

    2002-03-01

    The production of films containing uranium and americium through thermal decomposition of diketonates and their adducts is described. It is demonstrated that for substrate temperatures in the range 300-400°C and at a residual reactor pressure of 1.3 Pa, stable uranium-containing layers up to several milligrams per square centimetre can be produced, with yields of up to 90%. A variety of metal backings were investigated, including aluminium and its alloys, stainless steel and titanium. Similar results were obtained for americium, but with a strong influence of backing material on the yield. X-ray diffraction identified the chemical form of the uranium deposits as dioxide, with crystal lattice parameters varying from 5.4338 to 5.4871 Å, while the density determined by X-rays lies within the range from 10920 to 11255 kg/m 3. In the case of Am (Cm) hexafluoroacetyl acetonate decomposition, the deposit is most probably AmF 3 (CmF 3). The gases released from the pyrolytic uranium dioxide layers heated in vacuum to 470°C were studied. The volume of gas released varied between 10 and 40 cm 3 per gram of UO 2 depending on the initial β-diketonate preparation and reagent purity. The released gases were mainly hydrogen, carbon monoxide, carbon dioxide, water and a small amount of methane. The films of uranium and americium obtained by thermal decomposition show good adhesion to backings and are suitable for use in a number of fields, for example in nuclear physics research and instrument engineering.

  4. Americium separation from nuclear fuel dissolution using higher oxidation states.

    SciTech Connect

    Bruce J. Mincher

    2009-09-01

    Much of the complexity in current AFCI proposals is driven by the need to separate the minor actinides from the lanthanides. Partitioning and recycling Am, but not Cm, would allow for significant simplification because Am has redox chemistry that may be exploited while Cm does not. Here, we have explored methods based on higher oxidation states of Am (AmV and AmVI) to partition Am from the lanthanides. In a separate but related approach we have also initiated an investigation of the utility of TRUEX Am extraction from thiocyanate solution. The stripping of loaded TRUEX by Am oxidation or SCN- has not yet proved successful; however, the partitioning of inextractable AmV by TRUEX shows promise.

  5. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids.

    PubMed

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-10-01

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because

  6. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    DOE PAGESBeta

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. Themore » colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long

  7. Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

    SciTech Connect

    Dittrich, Timothy Mark; Boukhalfa, Hakim; Ware, Stuart Douglas; Reimus, Paul William

    2015-07-13

    Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater–bentonite–fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L–1) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10–10 M241Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (kf) of 0.01–0.02 h–1. Am recoveries in each column were 55–60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h–1 in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. As a result, our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill

  8. Magnetic Polarization of the Americium J =0 Ground State in AmFe2

    NASA Astrophysics Data System (ADS)

    Magnani, N.; Caciuffo, R.; Wilhelm, F.; Colineau, E.; Eloirdi, R.; Griveau, J.-C.; Rusz, J.; Oppeneer, P. M.; Rogalev, A.; Lander, G. H.

    2015-03-01

    Trivalent americium has a nonmagnetic (J =0 ) ground state arising from the cancellation of the orbital and spin moments. However, magnetism can be induced by a large molecular field if Am3 + is embedded in a ferromagnetic matrix. Using the technique of x-ray magnetic circular dichroism, we show that this is the case in AmFe2 . Since ⟨Jz⟩=0 , the spin component is exactly twice as large as the orbital one, the total Am moment is opposite to that of Fe, and the magnetic dipole operator ⟨Tz⟩ can be determined directly; we discuss the progression of the latter across the actinide series.

  9. Americium/europium separation by synergistic extraction mixtures of bis-tetrazolyl pyridines with chlorinated cobalt dicarbollide

    SciTech Connect

    Smirnov, I.V.; Babain, V.A.; Chirkov, A.V.

    2008-07-01

    Americium and europium extraction by synergistic mixtures of 2,6-bis(1-aryl-1 H-tetrazol-5-yl)pyridines (ATP) with chlorinated cobalt dicarbollide (CCD) in polar diluents from acidic media was studied. The effect of diluent, composition of aqueous phase, and substituent nature in the aryl ring of ATPs on the extraction efficiency and selectivity of americium and europium separation was investigated. The Am-Eu separation factor was close to 100 at the optimal ratio of ATPs:CCD {approx}1:1 in the synergistic mixture. High resistance of 2,6-bis-aryl-tetrazolyl pyridines to the action of acids and radiolysis was demonstrated. (authors)

  10. Decorporation of systemically distributed americium by a novel orally administered diethylenetriaminepentaacetic acid (DTPA) formulation in beagle dogs.

    PubMed

    Wilson, James P; Cobb, Ronald R; Dungan, Nathanael W; Matthews, Laura L; Eppler, Bärbel; Aiello, Kenneth V; Curtis, Shiro; Boger, Teannetta; Guilmette, Raymond A; Weber, Waylon; Doyle-Eisele, Melanie; Talton, James D

    2015-03-01

    Novel decorporation agents are being developed to protect against radiological accidents and terrorists attacks. Radioactive americium is a significant component of nuclear fallout. Removal of large radioactive materials, such as 241Am, from exposed persons is a subject of significant interest due to the hazards they pose. The objective of this study was to evaluate the dose-related efficacy of daily doses of NanoDTPA™ Capsules for decorporating Am administered intravenously as a soluble citrate complex to male and female beagle dogs. In addition, the efficacy of the NanoDTPA™ Capsules for decorporating 241Am was directly compared to intravenously administered saline and DTPA. Animals received a single IV administration of 241Am(III)-citrate on Day 0. One day after radionuclide administration, one of four different doses of NanoDTPA™ Capsules [1, 2, or 6 capsules d(-1) (30 mg, 60 mg, or 180 mg DTPA) or 2 capsules BID], IV Zn-DTPA (5 mg kg(-1) pentetate zinc trisodium) as a positive control, or IV saline as a placebo were administered. NanoDTPA™ Capsules, IV Zn-DTPA, or IV saline was administered on study days 1-14. Animals were euthanized on day 21. A full necropsy was conducted, and liver, spleen, kidneys, lungs and trachea, tracheobronchial lymph nodes (TBLN), muscle samples (right and left quadriceps), gastrointestinal (GI) tract (stomach plus esophagus, upper and lower intestine), gonads, two femurs, lumbar vertebrae (L1-L4), and all other soft tissue remains were collected. Urinary and fecal excretion profiles were increased approximately 10-fold compared to those for untreated animals. Tissue contents were decreased compared to untreated controls. In particular, liver content was decreased by approximately eightfold compared to untreated animals. The results from this study further demonstrate that oral NanoDTPA™ Capsules are equally efficient compared to IV Zn-DTPA in decorporation of actinides. PMID:25627942

  11. Comparative skeletal distribution of americium and plutonium in man, monkey and baboon

    SciTech Connect

    Lynch, T.P.; Dagle, G.E.; Kathren, R.L.; McInroy, J.F.

    1988-10-01

    The skeletal distributions of americium and plutonium in four humans were compared with the skeletal distributions of these radioelements in baboons and monkeys. With respect to the skeletal distribution of these elements, excellent agreement was noted among the four human cases; americium data was available for all four cases and plutonium for three. The human case database was thus adequate for comparison with those of other primates. A statistically significant correlation was found between the /sup 241/Am and /sup 239/Pu + /sup 240/Pu skeletal distributions in the humans and those in non-human primates. Trabecular bone had the highest concentrations of /sup 241/Am and /sup 239 +240/Pu in man, baboon, and monkey. Scaling factors are proposed to convert the percentages of skeletal activity in animal bones to the corresponding percentages in the bones of the human skeleton. However, considerable variation was found between the humans and animals in the percentages of the skeletal activity found in the same bone. 12 refs., 7 tabs.

  12. RAPID METHOD FOR PLUTONIUM, AMERICIUM AND CURIUM IN VERY LARGE SOIL SAMPLES

    SciTech Connect

    Maxwell, S

    2007-01-08

    The analysis of actinides in environmental soil and sediment samples is very important for environmental monitoring. There is a need to measure actinide isotopes with very low detection limits. A new, rapid actinide separation method has been developed and implemented that allows the measurement of plutonium, americium and curium isotopes in very large soil samples (100-200 g) with high chemical recoveries and effective removal of matrix interferences. This method uses stacked TEVA Resin{reg_sign}, TRU Resin{reg_sign} and DGA-Resin{reg_sign} cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), americium (Am), and curium (Cm) using a single multistage column combined with alpha spectrometry. The method combines an acid leach step and innovative matrix removal using cerium fluoride precipitation to remove the difficult soil matrix. This method is unique in that it provides high tracer recoveries and effective removal of interferences with small extraction chromatography columns instead of large ion exchange resin columns that generate large amounts of acid waste. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.

  13. Evaluation of americium-241 toxicity influence on the microbial growth of organic wastes

    SciTech Connect

    Takehiro Marumo, Julio; Padua Ferreira, Rafael Vicente de; Keiko Isiki, Vera Lucia; Miyamoto, Hissae; Sayuri Takara, Aline; Kazumi Sakata, Solange; Bellini, Maria Helena; Cardoso Pedroso de Lima, Luis Filipe

    2007-07-01

    Available in abstract form only. Full text of publication follows: Since the licenses for using radioactive sources in radioactive lightning rods were lifted by the Brazilian national nuclear authority, in 1989, the radioactive devices have been replaced by Franklin type and collected as radioactive waste. However, only 20 percent of the estimated total number of installed rods was delivered to Brazilian Nuclear Commission. This situation causes concern, due to, first, the possibility of the rods being disposed as domestic waste, and second, the americium, the most commonly employed radionuclide, is classified as a high-toxicity element. In the present study, Am-241 migration experiments were performed by a lysimeter system, in order to evaluate the risk of contamination caused by radioactive lightning rods disposed as a common solid waste. Besides the risk evaluation, it is important to know the mechanism of the Am-241 release or retention in waste as well as its influence in the waste decomposition processes. Many factors are involved, but microorganisms present in the waste play an important role in its degradation, which control the physical and chemical processes. The objective of this work was to evaluate the Am-241 influence on the microbial population by counting number of cells in lysimeters leachate. Preliminary results suggest that americium may influence significantly the bacteria growth in organic waste, evidenced by culture under aerobiosis and an-aerobiosis and the antimicrobial resistance test. (authors)

  14. An economic analysis of a light and heavy water moderated reactor synergy: burning americium using recycled uranium

    SciTech Connect

    Wojtaszek, D.; Edwards, G.

    2013-07-01

    An economic analysis is presented for a proposed synergistic system between 2 nuclear utilities, one operating light water reactors (LWR) and another running a fleet of heavy water moderated reactors (HWR). Americium is partitioned from LWR spent nuclear fuel (SNF) to be transmuted in HWRs, with a consequent averted disposal cost to the LWR operator. In return, reprocessed uranium (RU) is supplied to the HWRs in sufficient quantities to support their operation both as power generators and americium burners. Two simplifying assumptions have been made. First, the economic value of RU is a linear function of the cost of fresh natural uranium (NU), and secondly, plutonium recycling for a third utility running a mixed oxide (MOX) fuelled reactor fleet has been already taking place, so that the extra cost of americium recycling is manageable. We conclude that, in order for this scenario to be economically attractive to the LWR operator, the averted disposal cost due to partitioning americium from LWR spent fuel must exceed 214 dollars per kg, comparable to estimates of the permanent disposal cost of the high level waste (HLW) from reprocessing spent LWR fuel. (authors)

  15. Ditopic CMPO-pillar[5]arenes as unique receptors for efficient separation of americium(III) and europium(III).

    PubMed

    Fang, Yuyu; Yuan, Xiangyang; Wu, Lei; Peng, Zhiyong; Feng, Wen; Liu, Ning; Xu, Dingguo; Li, Shoujian; Sengupta, Arijit; Mohapatra, Prasanta K; Yuan, Lihua

    2015-03-11

    A unique host-guest recognition process involving a new class of homoditopic CMPO-pillar[5]arenes and lanthanides was revealed to proceed in a stepwise manner, and correlated with the efficient separation of americium(III) and europium(III) under acidic feed conditions. PMID:25671799

  16. XRD monitoring of α self-irradiation in uranium-americium mixed oxides.

    PubMed

    Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

    2013-12-16

    The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±δ) transmutation fuels (with x ≤ 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) α-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±δ) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ≤ 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±δ) and U0.5Am0.5O(2±δ), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am α self-irradiation caused a structural swelling up to ∼0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample α-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, α self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with

  17. Transportability Class of Americium in K Basin Sludge under Ambient and Hydrothermal Processing Conditions

    SciTech Connect

    Delegard, Calvin H.; Schmitt, Bruce E.; Schmidt, Andrew J.

    2006-08-01

    This report establishes the technical bases for using a ''slow uptake'' instead of a ''moderate uptake'' transportability class for americium-241 (241Am) for the K Basin Sludge Treatment Project (STP) dose consequence analysis. Slow uptake classes are used for most uranium and plutonium oxides. A moderate uptake class has been used in prior STP analyses for 241Am based on the properties of separated 241Am and its associated oxide. However, when 241Am exists as an ingrown progeny (and as a small mass fraction) within plutonium mixtures, it is appropriate to assign transportability factors of the predominant plutonium mixtures (typically slow) to the Am241. It is argued that the transportability factor for 241Am in sludge likewise should be slow because it exists as a small mass fraction as the ingrown progeny within the uranium oxide in sludge. In this report, the transportability class assignment for 241Am is underpinned with radiochemical characterization data on K Basin sludge and with studies conducted with other irradiated fuel exposed to elevated temperatures and conditions similar to the STP. Key findings and conclusions from evaluation of the characterization data and published literature are summarized here. Plutonium and 241Am make up very small fractions of the uranium within the K Basin sludge matrix. Plutonium is present at about 1 atom per 500 atoms of uranium and 241Am at about 1 atom per 19000 of uranium. Plutonium and americium are found to remain with uranium in the solid phase in all of the {approx}60 samples taken and analyzed from various sources of K Basin sludge. The uranium-specific concentrations of plutonium and americium also remain approximately constant over a uranium concentration range (in the dry sludge solids) from 0.2 to 94 wt%, a factor of {approx}460. This invariability demonstrates that 241Am does not partition from the uranium or plutonium fraction for any characterized sludge matrix. Most of the K Basin sludge characterization

  18. The Role of Colloids in the Transport of Plutonium and Americium: Implications for

    SciTech Connect

    Kersting, A B

    2003-09-17

    Colloids are small particulates (ranging in size from 1 to 0.001 micron) composed of inorganic and organic material and found in all natural water. Due to their small size, they have the ability to remain suspended in water and transported. Small amounts of plutonium (Pu) and americium (Am) can adsorb (attach) to colloids, and/or form colloidal-sized polymers and migrate in water. At Rocky Flats Environmental Technology Site (RFETS) sedimentation and resuspension of particulates and colloids in surface waters represent the dominant process for Pu and Am migration. The amount of Pu and Am that can be transported at RFETS has been quantified in the Pathway Analysis Report. The Pathway Analysis Report shows that the two dominant pathways for Pu and Am transport at RFETS are air and surface water. Shallow groundwater and biological pathways are minor.

  19. Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium

    SciTech Connect

    Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

    2009-11-01

    Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

  20. Imitators of plutonium and americium in a mixed uranium- plutonium nitride fuel

    NASA Astrophysics Data System (ADS)

    Nikitin, S. N.; Shornikov, D. P.; Tarasov, B. A.; Baranov, V. G.; Burlakova, M. A.

    2016-04-01

    Uranium nitride and mix uranium nitride (U-Pu)N is most popular nuclear fuel for Russian Fast Breeder Reactor. The works in hot cells associated with the radiation exposure of personnel and methodological difficulties. To know the main physical-chemical properties of uranium-plutonium nitride it necessary research to hot cells. In this paper, based on an assessment of physicochemical and thermodynamic properties of selected simulators Pu and Am. Analogues of Pu is are Ce and Y, and analogues Am - Dy. The technique of obtaining a model nitride fuel based on lanthanides nitrides and UN. Hydrogenation-dehydrogenation- nitration method of derived powders nitrides uranium, cerium, yttrium and dysprosium, held their mixing, pressing and sintering, the samples obtained model nitride fuel with plutonium and americium imitation. According to the results of structural studies have shown that all the samples are solid solution nitrides rare earth (REE) elements in UN.

  1. Magnetic polarization of the americium J=0 ground state in AmFe(2).

    PubMed

    Magnani, N; Caciuffo, R; Wilhelm, F; Colineau, E; Eloirdi, R; Griveau, J-C; Rusz, J; Oppeneer, P M; Rogalev, A; Lander, G H

    2015-03-01

    Trivalent americium has a nonmagnetic (J=0) ground state arising from the cancellation of the orbital and spin moments. However, magnetism can be induced by a large molecular field if Am^{3+} is embedded in a ferromagnetic matrix. Using the technique of x-ray magnetic circular dichroism, we show that this is the case in AmFe_{2}. Since ⟨J_{z}⟩=0, the spin component is exactly twice as large as the orbital one, the total Am moment is opposite to that of Fe, and the magnetic dipole operator ⟨T_{z}⟩ can be determined directly; we discuss the progression of the latter across the actinide series. PMID:25793847

  2. High Purity Americium-241 for Fuel Cycle R&D Program

    SciTech Connect

    Dr. Paul A. Lessing

    2011-07-01

    Previously the U.S. Department of Energy released Am-241 for various applications such as smoke detectors and Am-Be neutron sources for oil wells. At this date there is a shortage of usable, higher purity Am-241 in metal and oxide form available in the United States. Recently, the limited source of Am-241 has been from Russia with production being contracted to existing customers. The shortage has resulted in the price per gram rising dramatically over the last few years. DOE-NE currently has need for high purity Am-241 metal and oxide to fabricate fuel pellets for reactor testing in the Fuel Cycle R&D program. All the available high purity americium has been gathered from within the DOE system of laboratories. However, this is only a fraction of the projected needs of FCRD over the next 10 years. Therefore, FCR&D has proposed extraction and purification concepts to extract Am-241 from a mixed AmO2-PuO2 feedstock stored at the Savannah River Site. The most simple extraction system is based upon high temperature reduction using lanthanum metal with concurrent evaporation and condensation to produce high purity Am metal. Metallic americium has over a four order of magnitude higher vapor pressure than plutonium. Results from small-scale reduction experiments are presented. These results confirm thermodynamic predictions that at 1000 deg C metallic lanthanum reduces both PuO2 and AmO2. Faster kinetics are expected for temperatures up to about 1500 deg C.

  3. Thermodynamic properties for rare earths and americium in pyropartitioning process solvents

    SciTech Connect

    Fusselman, S.P.; Roy, J.J.; Grimmett, D.L.

    1999-07-01

    The design of a molten metal-molten salt based chemical and electrochemical process for separation of actinides from plutonium-uranium extraction waste requires a consistent set of thermodynamic properties for the actinides and rare earths present in nuclear waste. Standard potential data for Y, La, Ce, Pr, and Gd in molten LiCl-KCl were obtained. Americium data obtained were standard potentials in molten LiCl-KCl and activity coefficients for Cd and Bi. Data were obtained between 400 and 500 C. Results for the rare earth chlorides using an improved experimental technique were consistent with theory, with standard free energy of formation values somewhat more negative than those found in the literature. Special attention was given to Am in the LiCl-KCl/Cd system because it can exist as the +2 and/or +3 ion in this system. Americium ions existed only as the +3 ion in LiCl-KCl/Bi. Standard electrochemical potentials for Am/Am{sup +2} in LiCl-KCl eutectic at 400, 450, and 500 C were {minus}2.893, {minus}2.853, and {minus}2.838 V, respectively, relative to Cl{sup 2}/Cl{sup {minus}}. Standard electrochemical potentials vs. Cl{sub 2}/Cl{sup {minus}} for Am/Am{sup +3} in LiCl-KCl eutectic were {minus}2.83 V at 450 C and {minus}2.78 V at 500 C. Activity coefficients for Am in molten Cd were 1 {times} 10{sup {minus}5} and 8 {times} 10{sup {minus}5} at 450 and 500 C.

  4. The solvent extraction of Americium(III) by 2,6-bis[(diphenylphosphino)-methyl]pyridine N,P,P` trioxide from nitric acid and hydrochloric acid solutions

    SciTech Connect

    Bond, E.M.; Engelhardt, U.; Deere, T.P.; Rapko, B.M.; Paine, R.T.

    1997-12-31

    The liquid/liquid extractions of Am(III) from nitric acid and hydrochloric acid solutions with chloroform solutions of 2,6-bis[(diphenylphosphino)methyl]pyridine N,P,P{prime} trioxide will be described. Americium(III) extracts well from high concentration nitric acid solutions (D>3000 at 6M nitric acid) and can be back extracted from the organic phase at 0.01M Nitric Acid. Americium(III) exhibits modest extraction from hydrochloric acid solutions (D=2.2 at 5M hydrochloric acid) and can be back extracted from the organic phase at 0.1M hydrochloric acid. The ligand dependency data suggest that two ligand molecules are coordinated to americium in the nitric acid system and three ligand molecules are coordinated to the americium in the hydrochloric acid system.

  5. Extraction and recovery of plutonium and americium from nitric acid waste solutions by the TRUEX process - continuing development studies

    SciTech Connect

    Leonard, R.A.; Vandegrift, G.F.; Kalina, D.G.; Fischer, D.F.; Bane, R.W.; Burris, L.; Horwitz, E.P.; Chiarisia, R.; Diamond, H.

    1985-09-01

    This report summarizes the work done to date on the application of the TRUEX solvent extraction process for removing and separately recovering plutonium and americium from a nitric acid waste solution containing these elements, uranium, and a complement of inert metal ions. This simulated waste stream is typical of a raffinate from a tributyl phosphate (TBP)-based solvent extraction process for removing uranium and plutonium from dissolved plutonium-containing metallurgical scrap. The TRUEX process solvent in these experiments was a solution of TBP and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in carbon tetrachloride. A flowsheet was designed on the basis of measured batch distribution ratios to reduce the TRU content of the solidified raffinate to less than or equal to 10 nCi/g and was tested in a countercurrent experiment performed in a 14-stage Argonne-model centrifugal contractor. The process solvent was recycled without cleanup. An unexpectedly high evaporative loss of CCl/sub 4/ resulted in concentration of the active extractant, CMPO, to nearly 0.30M in the solvent. Results are consistent with this higher CMPO concentration. The raffinate contained only 2 nCi/g of TRU, but the higher CMPO concentration resulted in reduced effectiveness in the stripping of americium from the solvent. Conditions can be easily adjusted to give high yields and good separation of americium and plutonium. Experimental studies of the hydrolytic and gamma-radiolytic degradation of the TRUEX-CCl/sub 4/ showed that solvent degradation would be (1) minimal for a year of processing this typical feed, which contained no fission products, and (2) could be explained almost entirely by hydrolytic and radiolytic damage to TBP. Even for gross amounts of solvent damage, scrubbing with aqueous sodium carbonate solution restored the original americium extraction and stripping capability of the solvent. 43 refs., 5 figs., 36 tabs.

  6. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)

    NASA Astrophysics Data System (ADS)

    D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.

    2015-10-01

    Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to "produce" helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.

  7. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)

    NASA Astrophysics Data System (ADS)

    D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.

    2015-10-01

    Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to "produce" helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.

  8. Americium and plutonium in water, biota, and sediment from the central Oregon coast

    SciTech Connect

    Nielsen, R. D.

    1982-06-01

    Plutonium-239, 240 and americium-241 were measured in the mussel Mytilus californianus from the region of Coos Bay, OR. The flesh of this species has a plutonium concentration of about 90 fCi/kg, and an Am-241/Pu-239, 240 ratio that is high relative to mixed fallout, ranging between two and three. Transuranic concentrations in sediment, unfiltered water, and filterable particulates were also measured; none of these materials has an Am/Pu ratio as greatly elevated as the mussels, and there is no apparent difference in the Am/Pu ratio of terrestrial runoff and coastal water. Sediment core profiles do not allow accumulation rates or depositional histories to be identified, but it does not appear that material characterized by a high Am/Pu ratio has ever been introduced to this estuary. Other bivalves (Tresus capax and Macoma nasuta) and a polychaete (Abarenicola sp.) do not have an elevated Am/Pu ratio, although the absolute activity of plutonium in the infaunal bivalves is roughly four times that in the mussels.

  9. Quantitative NDA measurements of advanced reprocessing product materials containing uranium, neptunium, plutonium, and americium

    NASA Astrophysics Data System (ADS)

    Goddard, Braden

    The ability of inspection agencies and facility operators to measure powders containing several actinides is increasingly necessary as new reprocessing techniques and fuel forms are being developed. These powders are difficult to measure with nondestructive assay (NDA) techniques because neutrons emitted from induced and spontaneous fission of different nuclides are very similar. A neutron multiplicity technique based on first principle methods was developed to measure these powders by exploiting isotope-specific nuclear properties, such as the energy-dependent fission cross sections and the neutron induced fission neutron multiplicity. This technique was tested through extensive simulations using the Monte Carlo N-Particle eXtended (MCNPX) code and by one measurement campaign using the Active Well Coincidence Counter (AWCC) and two measurement campaigns using the Epithermal Neutron Multiplicity Counter (ENMC) with various (alpha,n) sources and actinide materials. Four potential applications of this first principle technique have been identified: (1) quantitative measurement of uranium, neptunium, plutonium, and americium materials; (2) quantitative measurement of mixed oxide (MOX) materials; (3) quantitative measurement of uranium materials; and (4) weapons verification in arms control agreements. This technique still has several challenges which need to be overcome, the largest of these being the challenge of having high-precision active and passive measurements to produce results with acceptably small uncertainties.

  10. Removal of plutonium and Americium from hydrochloric acid waste streams using extraction chromatography

    SciTech Connect

    Schulte, L.D.; FitzPatrick, J.R.; Salazar, R.R.; Schake, B.S.; Martinez, B.T.

    1995-01-01

    Extraction chromatography is under development as a method to lower actinide activity levels in hydrochloric acid (HCl) effluent streams. Successful application of this technique for radioactive liquid waste treatment would provide a low activity feedstream for HCl recycle, reduce the loss of radioactivity to the environment in aqueous effluents, and lower the quantity and improve the form of solid waste generated. The extraction of plutonium and americium from HCl solutions was examined for several commercial and laboratory-produced sorbed resin materials. Polymer beads were coated with n-octyl(phenyl)-N,N-diisobutylcarbamoyl- methylphosphine oxide (CMPO) and either tributyl phosphate (TBP), or diamyl amylphosphonate (DAAP). Distribution coefficients for Pu and Am were measured by contact studies in 1-10 M HCl, while varying REDOX conditions, actinide loading levels, and resin formulations. Flow experiments were run to evaluate actinide loading and elution under varied conditions. Significant differences in the actinide distribution coefficients in contact experiments, and in actinide retention in flow experiments were observed as a function of resin formulation.

  11. Preparation of curium-americium oxide microspheres by resin-bead loading

    SciTech Connect

    Chattin, F.R.; Benker, D.E.; Lloyd, M.H.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1980-01-01

    Resin-bead loading and calcination techniques have been used to produce all curium and americium oxide feed material (about 2.2 kg) for HFIR targets since 1971. The process based on Dowex 50W resin has progressed from a series of test runs, through special production runs, into routine production in permanent equipment beginning in 1975. Key attributes of this process are its reliability, high yields, and ease of operation. The process is suited for remote operation in hot cells. Yields approaching 95% are routinely obtained and only one unacceptable product has been generated during routine production operations. There have been no problems in fabricating targets from this oxide or in the subsequent irradiation of these targets. The present scale of production of 150 to 250 g/y supplies the present need and is comparable with the level of other chemical process operations at TRU. Since the annual production is accomplished in two 8 to 12 day periods, there has been no reason to consider further scale-up. However, the rate of production could easily be doubled by simply adding a second set of calcination equipment.

  12. Plutonium process control using an advanced on-line gamma monitor for uranium, plutonium, and americium

    SciTech Connect

    Marsh, S.F.; Miller, M.C.

    1987-05-01

    An on-line gamma monitor has been developed to profile uranium, plutonium, and americium in waste and product streams of the anion exchange process used to recover and purify plutonium at the Los Alamos Plutonium Facility. The gamma monitor employs passive gamma spectrometry to measure /sup 241/Am and /sup 239/Pu, based on their 59.5-keV and 129-keV gamma rays, respectively. Because natural and depleted uranium present in typical process streams have no gamma rays suitable for measurement by such passive methods, uranium measurement requires a novel and less direct technique. Plutonium-241, which is always present in plutonium processed at Los Alamos, decays primarily by beta emission to form /sup 241/Am. However, a small fraction of /sup 241/Pu decays by alpha emission to 6.8-day /sup 237/U. The short half-life and 208-keV gamma energy of /sup 237/U make it an ideal radiotracer to mark the position of macro amounts of uranium impurity in the separation process. The real-time data obtained from an operating process allow operators to optimize many process parameters. The gamma monitor also provides a permanent record of the daily performance of each ion exchange system. 2 refs., 12 figs.

  13. Development and Testing of an Americium/Lanthanide Separation Flowsheet Using Sodium Bismuthate

    SciTech Connect

    Jack Law; Bruce Mincher; Troy Garn; Mitchell Greenhalgh; Nicholas Schmitt; Veronica Rutledge

    2014-04-01

    The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term heat load of material interred in a future high-level waste repository. A separation process amenable to process scale-up remains elusive. Given only subtle chemistry differences within and between the ions of the trivalent actinide and lanthanide series this separation is challenging ; however, higher oxidation states of americium can be prepared using sodium bismuthate and separated via solvent extraction using diamylamylphosphonate (DAAP) extraction. Among the other trivalent metals only Ce is also oxidized and extracted. Due to the long-term instability of Am(VI) , the loaded organic phase is readily selectively stripped to partition the actinide to a new acidic aqueous phase. Batch extraction distribution ratio measurements were used to design a flowsheet to accomplish this separation. Additionally, crossflow filtration was investigated as a method to filter the bismuthate solids from the feed solution prior to extraction. Results of the filtration studies, flowsheet development work and flowsheet performance testing using a centrifugal contactor are detailed.

  14. Americium-based oxides: Dense pellet fabrication from co-converted oxalates

    NASA Astrophysics Data System (ADS)

    Horlait, Denis; Lebreton, Florent; Gauthé, Aurélie; Caisso, Marie; Arab-Chapelet, Bénédicte; Picart, Sébastien; Delahaye, Thibaud

    2014-01-01

    Mixed oxides are used as nuclear fuels and are notably envisaged for future fuel cycles including plutonium and minor actinide recycling. In this context, processes are being developed for the fabrication of uranium-americium mixed-oxide compounds for transmutation. The purpose of these processes is not only the compliance with fuel specifications in terms of density and homogeneity, but also the simplification of the process for its industrialization as well as lowering dust generation. In this paper, the use of a U0.85Am0.15O2±δ powder synthesized by oxalate co-conversion as a precursor for dense fuel fabrications is assessed. This study notably focuses on sintering, which yielded pellets up to 96% of the theoretical density, taking advantage of the high reactivity and homogeneity of the powder. As-obtained pellets were further characterized to be compared to those obtained via processes based on the UMACS (Uranium Minor Actinide Conventional Sintering) process. This comparison highlights several advantages of co-converted powder as a precursor for simplified processes that generate little dust.

  15. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site.

    PubMed

    Ikeda-Ohno, Atsushi; Harrison, Jennifer J; Thiruvoth, Sangeeth; Wilsher, Kerry; Wong, Henri K Y; Johansen, Mathew P; Waite, T David; Payne, Timothy E

    2014-09-01

    During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed. PMID:25126837

  16. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    NASA Astrophysics Data System (ADS)

    Degueldre, Claude; Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg-1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (˜0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13- coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix.

  17. Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

    NASA Astrophysics Data System (ADS)

    Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

    2015-05-01

    Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

  18. Osteosarcoma development following single inhalation exposure to americium-241 in beagle dogs

    SciTech Connect

    Gillett, N.A.; Hahn, F.F.; Mewhinney, J.A.; Muggenberg, B.A.

    1985-10-01

    Young, mature Beagle dogs underwent single inhalation exposure to respirable aerosols of SU AmO2 to determine the radiation dose distribution to tissues. The dogs were serially sacrificed to assess the clearance of SU Am from the lung, the rate of translocation to internal organs, the pattern of retention in the organs, and the rates and modes of excretion. Americium dioxide was relatively soluble in the lung, leading to the translocation of significant quantities of SU Am to bone and liver, thus delivering radiation doses to these tissues nearly equal to that received by the lung. Osteoblastic osteosarcomas developed in four dogs surviving more than 1000 days after exposure. Histologically, all of the osteosarcomas were associated with areas of radiation osteodystrophy characterized by bone infarction, peritrabecular new bone formation, marrow fibrosis, and microresorptive cavities. The retention and translocation of inhaled SU Am in dogs is similar to that of man, indicating that 241Am inhaled by humans may potentially result in significant risk of bone tumor development.

  19. Comparative biokinetics of trivalent radionuclides with similar ionic dimensions: promethium-147, curium-242 and americium-241.

    PubMed

    Priest, N D

    2007-09-01

    Data on the distribution and redistribution patterns in the laboratory rat of three trivalent elements with a similar ionic radius have been compared. This showed that these distributions for the two ions with the same ionic radius (111 pm), i.e., those of promethium (a lanthanoid) and curium (an actinoid), were indistinguishable and that americium, with a slightly larger ion size (111.5 pm), behaved similarly. The results are consistent with the suggestion that ion size is the only important factor controlling the deposition and redistribution patterns of trivalent lanthanoids and actinoids in rats. The result is important because it suggests that the same radiological protection dosimetry models should be used for trivalent actinoids and lanthanoids, that human volunteer data generated for lanthanoid isotopes can be used to predict the behavior of actinoids with the same ion size, and that appropriate pairs of beta-particle-emitting lanthanoid and alpha-particle-emitting actinoids could be used to study the relative toxicity of alpha and beta particles in experimental animals. PMID:17705633

  20. Assessment of radiation doses from residential smoke detectors that contain americium-241

    SciTech Connect

    O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.; Travis, C.C.

    1981-10-01

    External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).

  1. Cesium, americium and plutonium isotopes in ground level air of vilnius

    NASA Astrophysics Data System (ADS)

    Lujaniene, G.; Šapolaite, J.; Remeikis, V.; Lujanas, V.; Jermolajev, A.; Aninkevičius, V.

    2006-01-01

    Systematic observations of radionuclide composition and concentration in the atmosphere have been carried out at the Institute of Physics in Vilnius since 1963. Increases in activity concentration of radionuclides in the atmosphere were observed after nuclear weapon tests and the Chernobyl NPP accident. At present the radiation situation in Lithuania is determined by two main sources of radionuclides, forest fire and resuspension products transferred from highly polluted region of the Ukraine and Belarus. The activity concentrations of 137Cs were measured in two to three days samples while plutonium and americium in monthly samples. The extremely high activity concentrations of 238Pu, 239,240Pu, 241Am determined in the atmosphere during the Chernobyl accident can be explained by transport of “hot particles” of different composition. Activity concentration in 1995 2003 of 241Am and 239,240Pu isotopes ranged from 0.3 to 500 and from 1 to 500 nBq/m3, respectively. 238Pu/239,240Pu activity ratio in measured samples differs from 0.03 to 0.45. A decrease in 240Pu/239Pu atomic ratio from 0.30 to 0.19 was observed in 1995 2003.

  2. In Vitro Dissolution Tests of Plutonium and Americium Containing Contamination Originating From ZPPR Fuel Plates

    SciTech Connect

    William F. Bauer; Brian K. Schuetz; Gary M. Huestis; Thomas B. Lints; Brian K. Harris; R. Duane Ball; Gracy Elias

    2012-09-01

    Assessing the extent of internal dose is of concern whenever workers are exposed to airborne radionuclides or other contaminants. Internal dose determinations depend upon a reasonable estimate of the expected biological half-life of the contaminants in the respiratory tract. One issue with refractory elements is determining the dissolution rate of the element. Actinides such as plutonium (Pu) and Americium (Am) tend to be very refractory and can have biological half-lives of tens of years. In the event of an exposure, the dissolution rates of the radionuclides of interest needs to be assessed in order to assign the proper internal dose estimates. During the November 2011 incident at the Idaho National Laboratory (INL) involving a ZPPR fuel plate, air filters in a constant air monitor (CAM) and a giraffe filter apparatus captured airborne particulate matter. These filters were used in dissolution rate experiments to determine the apparent dissolution half-life of Pu and Am in simulated biological fluids. This report describes these experiments and the results. The dissolution rates were found to follow a three term exponential decay equation. Differences were noted depending upon the nature of the biological fluid simulant. Overall, greater than 95% of the Pu and 93% of the Am were in a very slow dissolving component with dissolution half-lives of over 10 years.

  3. Use of EIChroM TRU RESIN in the determination of Americium, Plutonium and Uranium in air filter and water samples

    SciTech Connect

    Berne, Anna

    1995-03-01

    TRU Resin, an extraction chromatographic material ((octyl (phenyl)-N,Ndiisobutylcarbamoylmethylphosphene oxide (CMPO) dissolved in tributyl phosphate (TBP)) manufactured by EIChroM Industries, was tested for its actinide sorption and desorption characteristics. A study was initiated to demonstrate the effectiveness of extracting plutonium, americium and uranium from water and air filter samples from the Environmental Measurements Laboratory’s Quality Assessment Program (QAP), and the effectiveness of subsequent desorption of one chemical species at a time in order to prepare each of them for spectrometry. Crossover of plutonium into the americium fraction with the TRU Resin was observed and could not be eliminated while using TRU Resin only. However, prior extraction of plutonium using an anion exchange resin can overcome this problem. A method for the determination of americium is proposed which combines the extraction of plutonium onto Bio-Rad AG 1-X8 anion exchange resin with the extraction of americium using the TRU Resin. This method was tested on three triplicate sets of QAP air filters and two triplicate sets of QAP water samples. The recoveries ranged from 70 to 90 percent, and the results were identical to those obtained by the existing methods. The time required to perform the analysis for americium was shortened from 5 weeks to 1 week.

  4. Use of EIChroM`s TRU resin in the determination of americium, plutonium and uranium in air filter and water samples

    SciTech Connect

    Berne, A.

    1995-12-01

    TRU Resin, an extraction chromatographic material (octyl (phenyl)-N,Ndiisobutylcarbamoyl-methylphosphene oxide (CMPO) dissolved in tributyl phosphate (TBP)) manufactured by EIChroM Industries, was tested for its actinide sorption and desorption characteristics. A study was initiated to demonstrate the effectiveness of extracting plutonium, americium and uranium from water and air filter samples from the Environmental Measurements Laboratory`s Quality Assessment Program (QAP), and the effectiveness of subsequent desorption of one chemical species at a time in order to prepare each of them for a spectrometry. Crossover of plutonium into the americium fraction with the TRU Resin was observed and could not be eliminated while using TRU Resin only. However, prior extraction of plutonium using an anion exchange resin can overcome this problem. A method for the determination of americium is proposed which combines the extraction of plutonium onto Bio-Rad AG 1-X8 anion exchange resin with the extraction of americium using the TRU Resin. This method was tested on three triplicate sets of QAP air filters and two triplicate sets of QAP water samples. The recoveries ranged from 70 to 90 percent, and the results were identical to those obtained by the existing methods. The time required to perform the analysis for americium was shortened from 5 weeks to 1 week.

  5. Adsorption and dissociation of molecular hydrogen on the (0001) surface of double hexagonal close packed americium

    NASA Astrophysics Data System (ADS)

    Dholabhai, P. P.; Ray, A. K.

    2009-01-01

    Hydrogen molecule adsorption on the (0001) surface of double hexagonal packed americium has been studied in detail within the framework of density functional theory using a full-potential all-electron linearized augmented plane wave plus local orbitals method (FP-L/APW+lo). Weak molecular hydrogen adsorptions were observed. Adsorption energies were optimized with respect to the distance of the adsorbates from the surface for three approach positions at three adsorption sites, namely t1 (one-fold top), b2 (two-fold bridge), and h3 (three-fold hollow) sites. Adsorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The most stable configuration corresponds to a horizontal adsorption with the molecular approach being perpendicular to a lattice vector. The surface coverage is equivalent to one-fourth of a monolayer (ML), with the adsorption energies at the NSOC and SOC theoretical levels being 0.0997 eV and 0.1022 eV, respectively. The respective distance of the hydrogen molecule from the surface and hydrogen-hydrogen distance was found to be 2.645 Å and 0.789 Å, respectively. The work functions decreased and the net magnetic moments remained almost unchanged in all cases compared with the corresponding quantities of bare dhcp Am (0001) surface. The adsorbate-substrate interactions have been analyzed in detail using the partial charges inside the muffin-tin spheres, difference charge density distributions, and the local density of states. The effects of adsorption on the Am 5f electron localization-delocalization characteristics have been discussed. Reaction barrier for the dissociation of hydrogen molecule has been presented.

  6. Investigation of the neutron spectrum of americium-beryllium sources by Bonner sphere spectrometry

    NASA Astrophysics Data System (ADS)

    Bedogni, R.; Domingo, C.; Roberts, N.; Thomas, D. J.; Chiti, M.; Esposito, A.; Garcia, M. J.; Gentile, A.; Liu, Z. Z.; de-San-Pedro, M.

    2014-11-01

    Americium-beryllium neutron sources are certainly the most widely used in neutron dosimetry laboratories, basically due to their long half-life and their energy distribution, which covers the energy domain of interest for many applications in ambient and personal dosimetry. Nevertheless, the spectrum of this source depends on the materials and dimension of the capsule and on the amount and physical-chemical properties of the active material, thus affecting relevant quantities such as the spectrum-averaged fluence-to-dose equivalent conversion coefficient. A EURAMET (European Association of National Metrology Institutes) project (n. 1104) was initiated to experimentally investigate how the neutron spectrum changes for different source sizes and encapsulations with a view to providing improved data for a planned revision of the ISO 8529 Standard Series. The experimental campaign was carried out in the low scatter facility at NPL. Here three different Bonner sphere spectrometers, BSSs, were exposed to the neutron fields produced by three different neutron sources formats: one X3 capsule (1 Ci) and two X14 capsules (10 Ci and 15 Ci). The specific advantage of the BSS is the large sensitivity to low-energy neutrons (E<0.1 MeV) which is the component expected to be most affected by the capsule-to-capsule variations and the component which is least well known. This paper summarises the results of the campaign with emphasis on (1) estimating the low-energy component of the Am-Be neutron spectrum, according to the encapsulation type; (2) evaluating the coherence between the Bonner spheres data and the previous studies performed with high-resolution spectrometers but limited in energy to E>0.1 MeV; (3) understanding whether the ISO-recommended Am-Be spectrum needs to be amended, and for which source formats.

  7. Americium and plutonium association with magnesium hydroxide colloids in alkaline nuclear industry process environments

    NASA Astrophysics Data System (ADS)

    Maher, Zoe; Ivanov, Peter; O'Brien, Luke; Sims, Howard; Taylor, Robin J.; Heath, Sarah L.; Livens, Francis R.; Goddard, David; Kellet, Simon; Rand, Peter; Bryan, Nick D.

    2016-01-01

    The behaviours of Pu, Am and colloids in feed solutions to the Site Ion-exchange Effluent Plant (SIXEP) at the Sellafield nuclear reprocessing site in the U.K. have been studied. For both Pu and Am, fractions were found to be associated with material in the colloidal size range, with ˜50% of the Pu in the range 1-200 nm. The concentration of soluble Pu (<1 nm) was ˜1 nM, which is very similar to the solubility limit for Pu(V). The soluble Am concentration was of the order of 10-11 M, which was below the solubility limit of americium hydroxide. The size, morphology and elemental composition of the particulates and colloids in the feed solutions were investigated. Magnesium is homogeneously distributed throughout the particles, whereas U, Si, Fe, and Ca were present in localised areas only. Amongst some heterogeneous material, particles were identified that were consistent with hydrotalcite. The distribution of 241Am(III) on brucite (magnesium hydroxide) colloids of different sizes was studied under alkaline conditions representative of nuclear fuel storage pond and effluent feed solution conditions. The morphology of the brucite particles in the bulk material observed by ESEM was predominantly hexagonal, while that of the carbonated brucite consisted of hexagonal species mixed with platelets. The association of 241Am(III) with the brucite colloids was studied by ultrafiltration coupled with gamma ray-spectrometry. For carbonate concentrations up to 10-3 M, the 241Am(III) was mainly associated with larger colloids (>300 kDa), and there was a shift from the smaller size fractions to the larger over a period of 6 months. At higher carbonate concentrations (10-2 M), the Am was predominantly detected in the true solution fraction (<3 kDa) and in smaller size colloidal fractions, in the range 3-100 kDa.

  8. Americium/Lanthanide Separations in Alkaline Solutions for Advanced Nuclear Fuel Cycles

    SciTech Connect

    Goff, George S.; Long, Kristy Marie; Reilly, Sean D.; Jarvinen, Gordon D.; Runde, Wolfgang H.

    2012-06-11

    Project goals: Can used nuclear fuel be partitioned by dissolution in alkaline aqueous solution to give a solution of uranium, neptunium, plutonium, americium and curium and a filterable solid containing nearly all of the lanthanide fission products and certain other fission products? What is the chemistry of Am/Cm/Ln in oxidative carbonate solutions? Can higher oxidation states of Am be stabilized and exploited? Conclusions: Am(VI) is kinetically stable in 0.5-2.0 M carbonate solutions for hours. Aliquat 336 in toluene has been successfully shown to extract U(VI) and Pu(VI) from carbonate solutions. (Stepanov et al 2011). Higher carbonate concentration gives lower D, SF{sub U/Eu} for = 4 in 1 M K{sub 2}CO{sub 3}. Experiments with Am(VI) were unsuccessful due to reduction by the organics. Multiple sources of reducing organics...more optimization. Reduction experiments of Am(VI) in dodecane/octanol/Aliquat 336 show that after 5 minutes of contact, only 30-40% of the Am(VI) has been reduced. Long enough to perform an extraction. Shorter contact times, lower T, and lower Aliquat 336 concentration still did not result in any significant extraction of Am. Anion exchange experiments using a strong base anion exchanger show uptake of U(VI) with minimal uptake of Nd(III). Experiments with Am(VI) indicate Am sorption with a Kd of 9 (10 minute contact) but sorption mechanism is not yet understood. SF{sub U/Nd} for = 7 and SF{sub U/Eu} for = 19 after 24 hours in 1 M K{sub 2}CO{sub 3}.

  9. Rapid, quantitative analysis of americium, curium and plutonium isotopes in Hanford samples using extraction chromatography and precipitation plating

    SciTech Connect

    Kaye, J.H.; Strebin, R.S.; Orr, R.D.

    1994-04-01

    Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated with neodymium fluoride, and counted. Examples of alpha spectra are given, and results obtained for Hanford sludge samples are presented.

  10. Swelling under irradiation of MgO pellets containing americium oxide: The ECRIX-H irradiation experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Béjaoui, S.; Hanifi, K.; Valot, Ch.; Loubet, L.

    2011-06-01

    The ECRIX-H irradiation experiment studied the behaviour of pellets containing americium dispersed in MgO. The purpose of the irradiation was to demonstrate the capacity of magnesia to provide an efficient support matrix. After fabrication, the sintered pellets contained 16.65 wt.% of Am microdispersed in the inert matrix. The ECRIX-H pellets were irradiated under a locally moderated neutron flux in the Phénix sodium-cooled fast reactor (SFR) for 318 Effective Full Power Days (EFPD). Post-test calculations indicated that the fission and transmutation rates of americium at the maximum flux plane reached 33.9% and 92.6% respectively at the end of the irradiation phase. The results of the post-irradiation examinations - both non-destructive and destructive - are discussed in this paper. These results indicate a satisfactory behaviour of the MgO matrix. Particularly, a moderate swelling occurs in the pellets under irradiation even with significant quantities of helium generated and at high transmutation rate.

  11. Temperature and concentration dependences of the electrical resistivity for alloys of plutonium with americium under normal conditions

    SciTech Connect

    Tsiovkin, Yu. Yu. Povzner, A. A.; Tsiovkina, L. Yu.; Dremov, V. V.; Kabirova, L. R.; Dyachenko, A. A.; Bystrushkin, V. B.; Ryabukhina, M. V.; Lukoyanov, A. V.; Shorikov, A. O.

    2010-01-15

    The temperature and concentration dependences of the electrical resistivity for alloys of americium with plutonium are analyzed in terms of the multiband conductivity model for binary disordered substitution-type alloys. For the case of high temperatures (T > {Theta}{sub D}, {Theta}{sub D} is the Debye temperature), a system of self-consistent equations of the coherent potential approximation has been derived for the scattering of conduction electrons by impurities and phonons without any constraints on the interaction intensity. The definitions of the shift and broadening operator for a single-electron level are used to show qualitatively and quantitatively that the pattern of the temperature dependence of the electrical resistivity for alloys is determined by the balance between the coherent and incoherent contributions to the electron-phonon scattering and that the interference conduction electron scattering mechanism can be the main cause of the negative temperature coefficient of resistivity observed in some alloys involving actinides. It is shown that the great values of the observed resistivity may be attributable to interband transitions of charge carriers and renormalization of their effective mass through strong s-d band hybridization. The concentration and temperature dependences of the resistivity for alloys of plutonium and americium calculated in terms of the derived conductivity model are compared with the available experimental data.

  12. Preconcentration of low levels of americium and plutonium from waste waters by synthetic water-soluble metal-binding polymers with ultrafiltration

    SciTech Connect

    Smith, B.F.; Gibson, R.R.; Jarvinen, G.D.; Robison, T.W.; Schroeder, N.C.; Stalnaker, N.D.

    1997-12-31

    A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method has been optimized to give over 90% recovery and accountability from actual waste water.

  13. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD. PMID:25742991

  14. Peculiar Behavior of (U,Am)O(2-δ) Compounds for High Americium Contents Evidenced by XRD, XAS, and Raman Spectroscopy.

    PubMed

    Lebreton, Florent; Horlait, Denis; Caraballo, Richard; Martin, Philippe M; Scheinost, Andreas C; Rossberg, Andre; Jégou, Christophe; Delahaye, Thibaud

    2015-10-19

    In U(1-x)Am(x)O(2±δ) compounds with low americium content (x ≤ 20 atom %) and oxygen-to-metal (O/M) ratios close to 2.0, Am(III+) cations are charge-balanced by an equivalent amount of U(V+) cations while the fluorite structure of pure U(IV+)O2 is maintained. Up to now, it is unknown whether this observation also holds for higher americium contents. In this study, we combined X-ray diffraction with Raman and X-ray absorption spectroscopies to investigate a U(0.5)Am(0.5)O(2±δ) compound. Our results indicate that americium is again only present as Am(III+), while U(V+) remains below the amount required for charge balance. Unlike lower americium contents, this leads to an overall oxygen hypostoichiometry with an average O/M ratio of 1.92(2). The cationic sublattice is only slightly affected by the coexistence of large amounts of reduced (Am(III+)) and oxidized (U(V+)) cations, whereas significant deviations from the fluorite structure are evidenced by both extended X-ray absorption fine structure and Raman spectroscopies in the oxygen sublattice, with the observation of both vacancies and interstitials, the latter being apparently consistent with the insertion of U6O12 cuboctahedral-type clusters (as observed in the U4O9 or U3O7 phases). These results thus highlight the specificities of uranium-americium mixed oxides, which behave more like trivalent lanthanide-doped UO2 than U(1-x)Pu(x)O(2±δ) MOX fuels. PMID:26407031

  15. Novel Americium Treatment Process for Surface Water and Dust Suppression Water

    SciTech Connect

    Tiepel, E.W.; Pigeon, P.; Nesta, S.; Anderson, J.

    2006-07-01

    The Rocky Flats Environmental Technology Site (RFETS), a former nuclear weapons production plant, has been remediated under CERCLA and decommissioned to become a National Wildlife Refuge. The site conducted this cleanup effort under the Rocky Flats Cleanup Agreement (RFCA) that established limits for the discharge of surface and process waters from the site. At the end of 2004, while a number of process buildings were undergoing decommissioning, routine monitoring of a discharge pond (Pond A-4) containing approximately 28 million gallons of water was discovered to have been contaminated with a trace amount of Americium-241 (Am-241). While the amount of Am-241 in the pond waters was very low (0.5 - 0.7 pCi/l), it was above the established Colorado stream standard of 0.15 pCi/l for release to off site drainage waters. The rapid successful treatment of these waters to the regulatory limit was important to the site for two reasons. The first was that the pond was approaching its hold-up limit. Without rapid treatment and release of the Pond A-4 water, typical spring run-off would require water management actions to other drainages onsite or a mass shuttling of water for disposal. The second reason was that this type of contaminated water had not been treated to the stringent stream standard at Rocky Flats before. Technical challenges in treatment could translate to impacts on water and secondary waste management, and ultimately, cost impacts. All of the technical challenges and specific site criteria led to the conclusion that a different approach to the treatment of this problem was necessary and a crash treatability program to identify applicable treatment techniques was undertaken. The goal of this program was to develop treatment options that could be implemented very quickly and would result in the generation of no high volume secondary waste that would be costly to dispose. A novel chemical treatment system was developed and implemented at the RFETS to treat Am

  16. Thermodynamic study of the complexation of trivalent actinide and lanthanide cations by ADPTZ, a tridentate N-donor ligand.

    PubMed

    Miguirditchian, Manuel; Guillaneux, Denis; Guillaumont, Dominique; Moisy, Philippe; Madic, Charles; Jensen, Mark P; Nash, Kenneth L

    2005-03-01

    To better understand the bonding in complexes of f-elements by polydentate N-donor ligands, the complexation of americium(III) and lanthanide(III) cations by 2-amino-4,6-di-(pyridin-2-yl)-1,3,5-triazine (ADPTZ) was studied using a thermodynamic approach. The stability constants of the 1:1 complexes in a methanol/water mixture (75/25 vol %) were determined by UV-visible spectrophotometry for every lanthanide(III) ion (except promethium), and yttrium(III) and americium(III) cations. The thermodynamic parameters (DeltaH degrees , DeltaS degrees) of complexation were determined from the temperature dependence of the stability constants and by microcalorimetry. The trends of the variations of DeltaG degrees , DeltaH degrees , and DeltaS degrees across the lanthanide series are compared with published results for other tridentate ligands and confirm strongly ionic bonding in the lanthanide-ADPTZ complexes. Comparison of the thermodynamic properties between the Am- and Ln-ADPTZ complexes highlights an increase in stability of the complexes by a factor of 20 in favor of the americium cation. This difference arises from a more exothermic reaction enthalpy in the case of Am, which is correlated with a greater degree of covalency in the americium-nitrogen bonds. Quantum chemistry calculations performed on a series of trivalent actinide and lanthanide-ADPTZ complexes support the experimental results, showing a slightly greater covalence in the actinide-ligand bonds that originates from a charge transfer from the ligand sigma orbitals to the 5f and 6d orbitals of the actinide ion. PMID:15732980

  17. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium-americium mixed oxides

    NASA Astrophysics Data System (ADS)

    Prieur, D.; Lebreton, F.; Martin, P. M.; Caisso, M.; Butzbach, R.; Somers, J.; Delahaye, T.

    2015-10-01

    Uranium-americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U1-xAmxO2±δ samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U1-xAmxO2±δ leads to the formation of similar fluorite solid solution indicating the presence of Am+III and U+V in equimolar proportions.

  18. Chemical Speciation of Americium, Curium and Selected Tetravalent Actinides in High Level Waste

    SciTech Connect

    Felmy, Andrew R.

    2005-06-01

    Large volumes of high-level waste (HLW) currently stored in tanks at DOE sites contain both sludges and supernatants. The sludges are composed of insoluble precipitates of actinides, radioactive fission products, and nonradioactive components. The supernatants are alkaline carbonate solutions, which can contain soluble actinides, fission products, metal ions, and high concentrations of major electrolytes including sodium hydroxide, nitrate, nitrite, phosphate, carbonate, aluminate, sulfate, and organic complexants. The organic complexants include several compounds that can form strong aqueous complexes with actinide species and fission products including ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), citrate, glycolate, gluconate, and degradation products, formate and oxalate.

  19. Chemical Speciation of Americium, Curium and Selected Tetravalent Actinides in High Level Waste

    SciTech Connect

    Felmy, Andrew R.

    2006-06-01

    Large volumes of high-level waste (HLW) currently stored in tanks at DOE sites contain both sludges and supernatants. The sludges are composed of insoluble precipitates of actinides, radioactive fission products, and nonradioactive components. The supernatants are alkaline carbonate solutions, which can contain soluble actinides, fission products, metal ions, and high concentrations of major electrolytes including sodium hydroxide, nitrate, nitrite, phosphate, carbonate, aluminate, sulfate, and organic complexants. The organic complexants include several compounds that can form strong aqueous complexes with actinide species and fission products including ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), citrate, glycolate, gluconate, and degradation products, formate and oxalate.

  20. Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

    SciTech Connect

    Prieur, D.; Lebreton, F.; Somers, J.; Delahaye, T.

    2015-10-15

    Uranium–americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U{sub 1−x}Am{sub x}O{sub 2±δ} samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U{sub 1−x}Am{sub x}O{sub 2±δ} leads to the formation of similar fluorite solid solution indicating the presence of Am{sup +III} and U{sup +V} in equimolar proportions. - Graphical abstract: Formation of (U{sup IV/V},Am{sup III})O{sup 2} solid solution by sol–gel and by powder metallurgy. - Highlights: • Uranium–americium mixed oxides were synthesized by sol–gel and powder metallurgy. • Fluorite solid solutions with similar local environment have been obtained. • U{sup V} and Am{sup III} are formed in equimolar proportions.

  1. Evaluation of synthetic water-soluble metal-binding polymers with ultrafiltration for selective concentration of americium and plutonium

    SciTech Connect

    Smith, B.F.; Gibson, R.R.; Jarvinen, G.D.; Jones, M.M.; Lu, M.T.; Robison, T.W.; Schroeder, N.C.; Stalnaker, N.

    1997-12-31

    Routine counting methods and ICP-MS are unable to directly measure the new US Department of Energy (DOE) regulatory level for discharge waters containing alpha-emitting radionuclides of 30 pCi/L total alpha or the 0.05 pCi/L regulatory level for Pu or Am activity required for surface waters at the Rocky Flats site by the State of Colorado. This inability indicates the need to develop rapid, reliable, and robust analytical techniques for measuring actinide metal ions, particularly americium and plutonium. Selective separation or preconcentration techniques would aid in this effort. Water-soluble metal-binding polymers in combination with ultrafiltration are shown to be an effective method for selectively removing dilute actinide ions from acidic solutions of high ionic strength. The actinide-binding properties of commercially available water-soluble polymers and several polymers which have been reported in the literature were evaluated. The functional groups incorporated in the polymers were pyrrolidone, amine, oxime, and carboxylic, phosphonic, or sulfonic acid. The polymer containing phosphonic acid groups gave the best results with high distribution coefficients and concentration factors for {sup 241}Am(III) and {sup 238}Pu(III)/(IV) at pH 4 to 6 and ionic strengths of 0.1 to 4.

  2. EURADOS INTERCOMPARISON ON MEASUREMENTS AND MONTE CARLO MODELLING FOR THE ASSESSMENT OF AMERICIUM IN A USTUR LEG PHANTOM

    SciTech Connect

    Lopez, M. A.; Broggio, D.; Capello, K.; Cardenas-Mendez, E.; El-Faramawy, N.; Franck, D.; James, Anthony C.; Kramer, Gary H.; Lacerenza, G.; Lynch, Timothy P.; Navarro, J. F.; Navarro, T.; Perez, B.; Ruhm, W.; Tolmachev, Sergei Y.; Weitzenegger, E.

    2011-03-01

    United States Transuranium and Uranium Registries (USTUR) Case 0102 was the first whole-body donation to the USTUR (1979), of a worker affected by a substantial accidental 241Am intake(1). Half of this man’s skeleton, encased in tissue-quivalent plastic, provides a unique human ‘phantom’ for calibrating in vivo counting systems. In this case, the 241Am skeletal activity was measured 25 y after the intake. Approximately 82 % of the 241Am remaining in the body was found in the bones and teeth. The241Am activity concentration throughout the skeleton (in all types of bone) was fairly uniform(2). A protocol has been proposed by a group of in vivo laboratories from Europe [CIEMAT-Spain, IRSN-France and Helmholtz Zentrum Mu¨nchen (HMGU)-Germany] and Canada (HML) participating in this DOS/USTUR intercomparison. The focus areas for the study included: (1) the efficiency pattern along the leg phantom using Germanium detectors (experimental and computational), (2) the comparison of Monte Carlo (MC) results with experimental values in counting efficiency data and (3) the inflence of americium distribution in the bone material (volume or surface).

  3. Theoretical investigation of pressure-induced structural transitions in americium using GGA+U and hybrid density functional theory methods

    NASA Astrophysics Data System (ADS)

    Verma, Ashok K.; Modak, P.; Sharma, Surinder M.; Svane, A.; Christensen, N. E.; Sikka, S. K.

    2013-07-01

    First-principles calculations have been performed for americium (Am) metal using the generalized gradient approximation + orbital-dependent onsite Coulomb repulsion via Hubbard interaction (GGA+U) and hybrid density functional theory (HYB-DFT) methods to investigate various ground state properties and pressure-induced structural transitions. Both methods yield equilibrium volume and bulk modulus in good agreement with the experimental results. The GGA+spin orbit coupling+U method reproduced all structural transitions under pressure correctly, but the HYB-DFT method failed to reproduce the observed Am-I to Am-II transition. Good agreement was found between calculated and experimental equations of states for all phases, but the first three phases need larger U (α) parameters (where α represents the fraction of Hartree-Fock exchange energy replacing the DFT exchange energy) than the fourth phase in order to match the experimental data. Thus, neither the GGA+U nor the HYB-DFT methods are able to describe the energetics of Am metal properly in the entire pressure range from 0 GPa to 50 GPa with a single choice of their respective U and α parameters. Low binding-energy peaks in the experimental photoemission spectrum at ambient pressure relate, for some parameter choices, well to peak positions in the calculated density of states function of Am-I.

  4. Characterization of a Sealed Americium-Beryllium (AmBe) Source by Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    James Sommers; Marcos Jimenez; Mary Adamic; Jeffrey Giglio; Kevin Carney

    2009-12-01

    Two Americium-Beryllium neutron sources were dismantled, sampled (sub-sampled) and analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Characteristics such as “age” since purification, actinide content, trace metal content and inter and intra source composition were determined. The “age” since purification of the two sources was determined to be 25.0 and 25.4 years, respectively. The systematic errors in the “age” determination were ± 4 % 2s. The amount and isotopic composition of U and Pu varied substantially between the sub-samples of Source 2 (n=8). This may be due to the physical means of sub-sampling or the way the source was manufactured. Source 1 was much more consistent in terms of content and isotopic composition (n=3 sub-samples). The Be-Am ratio varied greatly between the two sources. Source 1 had an Am-Be ratio of 6.3 ± 52 % (1s). Source 2 had an Am-Be ratio of 9.81 ± 3.5 % (1s). In addition, the trace element content between the samples varied greatly. Significant differences were determined between Source 1 and 2 for Sc, Sr, Y, Zr, Mo, Ba and W.

  5. Nano-cerium vanadate: a novel inorganic ion exchanger for removal of americium and uranium from simulated aqueous nuclear waste.

    PubMed

    Banerjee, Chayan; Dudwadkar, Nilesh; Tripathi, Subhash Chandra; Gandhi, Pritam Maniklal; Grover, Vinita; Kaushik, Chetan Prakash; Tyagi, Avesh Kumar

    2014-09-15

    Cerium vanadate nanopowders were synthesized by a facile low temperature co-precipitation method. The product was characterized by X-ray diffraction and transmission electron microscopy and found to consist of ∼25 nm spherical nanoparticles. The efficiency of these nanopowders for uptake of alpha-emitting radionuclides (233)U (4.82 MeV α) and (241)Am (5.49 MeV α, 60 keV γ) has been investigated. Thermodynamically and kinetically favorable uptake of these radionuclides resulted in their complete removal within 3h from aqueous acidic feed solutions. The uptake capacity was observed to increase with increase in pH as the zeta potential value decreased with the increase in pH but effect of ionic strength was insignificant. Little influence of the ions like Sr(2+), Ru(3+), Fe(3+), etc., in the uptake process indicated CeVO4 nanopowders to be amenable for practical applications. The isotherms indicated predominant uptake of the radioactive metal ions in the solid phase of the exchanger at lower feed concentrations and linear Kielland plots with positive slopes indicated favorable exchange of the metal ions with the nanopowder. Performance comparison with the other sorbents reported indicated excellent potential of nano-cerium vanadate for removing americium and uranium from large volumes of aqueous acidic solutions. PMID:25128895

  6. Chemical Speciation of Americium, Curium and Selected Tetravalent Actinides in High Level Waste

    SciTech Connect

    Felmy, Andrew R.

    2004-06-01

    Large volumes of high-level waste (HLW) currently stored in tanks at DOE sites contain both sludges and supernatants. The sludges are composed of insoluble precipitates of actinides, radioactive fission products, and nonradioactive components. The supernatants are alkaline carbonate solutions, which can contain soluble actinides, fission products, metal ions, and high concentrations of major electrolytes including sodium hydroxide, nitrate, nitrite, phosphate, carbonate, aluminate, sulfate, and organic complexants. The organic complexants include several compounds that can form strong aqueous complexes with actinide species and fission products including ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), citrate, glycolate, gluconate, and degradation products, formate and oxalate. The goal of this project is to determine the effects of hydrolysis, carbonate complexation, and metal ion displacement on trivalent and selected tetravalent actinide speciation in the presence of organic chelates present in tank waste and to use these data to develop accurate predictive thermodynamic models for use in chemical engineering applications at Hanford and other DOE sites.

  7. Separation of americium from europium by solvent extraction from aqueous phosphonate media

    SciTech Connect

    Ensor, D.D.; Nash, K.L.

    1994-12-31

    Complexes between Am{sup 3+} or Eu{sup 3+} and phosphonoacetic acid differ in relative stability in accord with the electrostatic model of cation binding. The smaller Eu{sup 3+} cation forms stronger complexes with PAA than the larger Am{sup 3+} cation. The observed metal complexes in the acid range from 0.005 M to 0.02 M (at I= 0.5 M) are Eu(HL){sup +}, Eu(H{sub 3}L){sub 2}{sup +}, Eu(HL){sub 2}{sup {minus}} and Am(H{sub 2}L){sup 2+}, Am(HL){sup +}, Am(H{sub 2}L){sub 2}{sup +}. When used as a holdback reagent, PAA slightly enhances the separation of Am/Eu when used with sulfonic acids or CMPO/nitrate, but reduces separation efficiency with HDEHP. In a CMPO/SCN{sup {minus}} extraction system which favors extraction of Am over Eu, addition of PAA increases the separation efficiency by a factor of 2-3 at 0.3 M PAA/0.5 M SCN{sup {minus}}. The calculated stability constants can be used to explain the separation factors, but do not always accurately predict metal distribution ratios in the CMPO systems, implying that there are details of this system which have not been fully elucidated.

  8. Efficient Separation of Europium Over Americium Using Cucurbit-[5]-uril Supramolecule: A Relativistic DFT Based Investigation.

    PubMed

    Sadhu, Biswajit; Sundararajan, Mahesh; Bandyopadhyay, Tusar

    2016-01-19

    Achieving an efficient separation of chemically similar Am(3+)/Eu(3+) pair in high level liquid waste treatment is crucial for managing the long-term nuclear waste disposal issues. The use of sophisticated supramolecules in a rigid framework could be the next step toward solving the long-standing problem. Here, we have investigated the possibility of separating Am(3+)/Eu(3+) pair with cucurbit-[5]-uril (CB[5]), a macrocycle from the cucurbit-[n]-uril family, using relativistic density functional theory (DFT) based calculations. We have explored the structures, binding, and energetics of metal-CB[5] complexation processes with and without the presence of counterions. Our study reveals an excellent selectivity of Eu(3+) over Am(3+) with CB[5] (ion exchange free energy, ΔΔGAm/Eu > 10 kcal mol(-1)). Both metals bind with the carbonyl portals via μ(5) coordination arrangement with the further involvement of three external water molecules. The presence of counterions, particularly nitrate, inside the hydrophobic cavity of CB[5], induces a cooperative cation-anion binding, resulting in enhancement of metal binding at the host. The overall binding process is found to be entropy driven resembling the recent experimental observations (Rawat et al. Dalton Trans. 2015, 44, 4246-4258). The optimized structural parameters for Eu(3+)-CB[5] complexes are found to be in excellent agreement with the available experimental information. To rationalize the computed selectivity trend, electronic structures are further scrutinized using energy decomposition analysis (EDA), quantum theory of atom in molecules (QTAIM), Mülliken population analysis (MPA), Nalewajski-Mrojek (NM) bond order, and molecular orbital analyses. Strong electrostatic ion-dipole interaction along with efficient charge transfer between CB[5] and Eu(3+) outweighs the better degree of covalency between CB[5] and Am(3+) leading to superior selectivity of Eu(3+) over Am(3+). PMID:26741954

  9. Measurement of total alpha activity of neptunium, plutonium, and americium in highly radioactive Hanford waste by iron hydroxide precipitation and 2-heptanone solvent extraction

    SciTech Connect

    Maiti, T.C.; Kaye, J.H.

    1992-06-01

    An improved method has been developed to concentrate the major alpha-emitting actinide elements neptunium, plutonium, and americium from samples with high salt content such as those resulting from efforts to characterize Hanford storage tank waste. Actinide elements are concentrated by coprecipitation of their hydroxides using iron carrier. The iron is removed by extraction from 8M HCI with 2-heptanone. The actinide elements remain in the aqueous phase free from salts, iron, and long-lived fission products. Recoveries averaged 98 percent.

  10. Fabrication and characterization of U1-xAmxO2±δ compounds with high americium contents (x = 0.3, 0.4 and 0.5)

    NASA Astrophysics Data System (ADS)

    Lebreton, Florent; Horlait, Denis; Delahaye, Thibaud; Blanchart, Philippe

    2013-08-01

    Mixed uranium-americium oxides are considered promising compounds for americium transmutation in fast neutron reactors. A better understanding of these materials and of the U-Am-O phase diagram is, however, needed. Though many results in the literature describe U1-xAmxO2±δ (x ⩽ 0.2) compounds, very few studies concern higher Am contents. In this context, this article reports the fabrication method of U1-xAmxO2±δ (0.3 ⩽ x ⩽ 0.5) and their preliminary characterization, notably by X-ray diffraction.

  11. Effect of solvent on in vitro dissolution: Summary of results for uranium, americium, and cobalt aerosols

    SciTech Connect

    Guilmette, R.A.; Hoover, M.D.

    1995-12-01

    The revised 10 CFR Part 20 has adopted the ICRP Publication 30 method for calculating the committed effective dose equivalent from intakes of radionuclides. This dosimetry scheme requires knowledge or assumptions about the chemical form of the radionuclide, its particle size, and its known or assumed solubility. The solubility is classified as being either D (relatively soluble), W, or Y (relatively insoluble), depending on whether the material dissolves over periods of days, weeks, or years. Although Nuclear Regulatory Commission licensees may wish to take advantage of material-specific knowledge in order to adjust annual limits on intake and derived air concentrations, relatively few radioactive materials to which workers and the general population may be exposed have been adequately characterized either in terms of physicochemical form or solubility. Experimental measurement of solubility using some type of in vitro dissolution measurement system is therefore needed. However, there is currently no clear consensus regarding the appropriate design of in vitro dissolution systems, particularly when considering the range of different radionuclides to be studied, and the complexity of the biological mechanisms involved in the retention and clearance of inhaled deposited radioactive particles. The purpose of this study was to evaluate the effect of the several solvents on the dissolution of four test aerosols ({sup 57}Co{sub 3}O{sub 4}, {sup 241}AmO{sub 2}, ammonium diuranate [ADU], and U{sub 3}O{sub 8}) selected to encompass a variety of chemical and biochemical properties in vivo. The results of this study provide some guidance on the usefulness of in vitro dissolution tests for estimating the solubility of unknown radionuclide particles within the context of a simple model such as the class D, W, and Y formulation of ICRP 30.

  12. Functional sorbents for selective capture of plutonium, americium, uranium, and thorium in blood.

    PubMed

    Yantasee, Wassana; Sangvanich, Thanapon; Creim, Jeffery A; Pattamakomsan, Kanda; Wiacek, Robert J; Fryxell, Glen E; Addleman, R Shane; Timchalk, Charles

    2010-09-01

    Self-assembled monolayer on mesoporous supports (SAMMS) are hybrid materials created from attachment of organic moieties onto very high surface area mesoporous silica. SAMMS with surface chemistries including three isomers of hydroxypyridinone, diphosphonic acid, acetamide phosphonic acid, glycinyl urea, and diethylenetriamine pentaacetate (DTPA) analog were evaluated for chelation of actinides ((239)Pu, (241)Am, uranium, thorium) from blood. Direct blood decorporation using sorbents does not have the toxicity or renal challenges associated with traditional chelation therapy and may have potential applications for critical exposure cases, reduction of nonspecific dose during actinide radiotherapy, and for sorbent hemoperfusion in renal insufficient patients, whose kidneys clear radionuclides at a very slow rate. Sorption affinity (K(d)), sorption rate, selectivity, and stability of SAMMS were measured in batch contact experiments. An isomer of hydroxypyridinone (3,4-HOPO) on SAMMS demonstrated the highest affinity for all four actinides from blood and plasma and greatly outperformed the DTPA analog on SAMMS and commercial resins. In batch contact, a fifty percent reduction of actinides in blood was achieved within minutes, and there was no evidence of protein fouling or material leaching in blood after 24 h. The engineered form of SAMMS (bead format) was further evaluated in a 100-fold scaled-down hemoperfusion device and showed no blood clotting after 2 h. A 0.2 g quantity of SAMMS could reduce 50 wt.% of 100 ppb uranium in 50 mL of plasma in 18 min and that of 500 dpm mL(-1) in 24 min. 3,4-HOPO-SAMMS has a long shelf-life in air and at room temperature for at least 8 y, indicating its feasibility for stockpiling in preparedness for an emergency. The excellent efficacy and stability of SAMMS materials in complex biological matrices suggest that SAMMS can also be used as orally administered drugs and for wound decontamination. By changing the organic groups of

  13. Functional Sorbents for Selective Capture of Plutonium, Americium, Uranium, and Thorium in Blood

    PubMed Central

    Yantasee, Wassana; Sangvanich, Thanapon; Creim, Jeffery A; Pattamakomsan, Kanda; Wiacek, Robert J; Fryxell, Glen E; Addleman, R Shane; Timchalk, Charles

    2010-01-01

    Self-assembled monolayer on mesoporous supports (SAMMS™) are hybrid materials created from attachment of organic moieties onto very high surface area mesoporous silica. SAMMS with surface chemistries including three isomers of hydroxypyridinone, diphosphonic acid, acetamide phosphonic acid, glycinyl urea, and diethylenetriamine pentaacetate (DTPA) analog were evaluated for chelation of actinides (239Pu, 241Am, uranium, thorium) from blood. Direct blood decorporation using sorbents does not have toxicity or renal challenges associated with traditional chelation therapy and may have potential applications for critical exposure cases, reduction of nonspecific dose during actinide radiotherapy, and for sorbent hemoperfusion in renal insufficient patients, whose kidney clear radionuclides at very slow rate. Sorption affinity (Kd), sorption rate, selectivity, and stability of SAMMS were measured in batch contact experiments. An isomer of hydroxypyridinone (3,4-HOPO) on SAMMS demonstrated the highest affinity for all four actinides from blood and plasma and greatly outperformed the DTPA analog on SAMMS and commercial resins. In batch contact, a fifty percent reduction of actinides in blood was achieved within minutes, and there was no evidence of protein fouling or material leaching in blood after 24 hr. The engineered form of SAMMS (bead format) was further evaluated in a 100-fold scaled-down hemoperfusion device and showed no blood clotting after 2 hr. A 0.2 g quantity of SAMMS could reduce 50 wt.% of 100 ppb uranium in 50 mL of plasma in 18 min and that of 500 dpm mL−1 in 24 min. 3,4-HOPO-SAMMS has a long shelf-life in air and at room temperature for at least 8 years, indicating its feasibility for stockpiling in preparedness for an emergency. The excellent efficacy and stability of SAMMS materials in complex biological matrices suggest that SAMMS can also be used as orally administered drugs and for wound decontamination. By changing the organic groups of SAMMS

  14. New Synthetic Methods and Structure-Property Relationships in Neptunium, Plutonium, and Americium Borates. Final report

    SciTech Connect

    Albrecht-Schmitt, Thomas Edward

    2013-09-14

    The past three years of support by the Heavy Elements Chemistry Program have been highly productive in terms of advanced degrees awarded, currently supported graduate students, peer-reviewed publications, and presentations made at universities, national laboratories, and at international conferences. Ph.D. degrees were granted to Shuao Wang and Juan Diwu, who both went on to post-doctoral appointments at the Glenn T. Seaborg Center at Lawrence Berkeley National Laboratory with Jeff Long and Ken Raymond, respectively. Pius Adelani completed his Ph.D. with me and is now a post-doc with Peter C. Burns. Andrea Alsobrook finished her Ph.D. and is now a post-doc at Savannah River with Dave Hobbs. Anna Nelson completed her Ph.D. and is now a post-doc with Rod Ewing at the University of Michigan. As can be gleaned from this list, students supported by the Heavy Elements Chemistry grant have remained interested in actinide science after leaving my program. This follows in line with previous graduates in this program such as Richard E. Sykora, who did his post-doctoral work at Oak Ridge National Laboratory with R. G. Haire, and Amanda C. Bean, who is a staff scientist at Los Alamos National Laboratory, and Philip M. Almond and Thomas C. Shehee, who are both staff scientists at Savannah River National Laboratory, Gengbang Jin who is a staff scientist at Argonne National Lab, and Travis Bray who has been a post-doc at both LBNL and ANL. Clearly this program is serving as a pipe-line for students to enter into careers in the national laboratories. About half of my students depart the DOE complex for academia or industry. My undergraduate researchers also remain active in actinide chemistry after leaving my group. Dan Wells was a productive undergraduate of mine, and went on to pursue a Ph.D. on uranium and neptunium chalcogenides with Jim Ibers at Northwestern. After earning his Ph.D., he went directly into the nuclear industry.

  15. Synthesis of zirconia sol stabilized by trivalent cations (yttrium and neodymium or americium): a precursor for Am-bearing cubic stabilized zirconia.

    PubMed

    Lemonnier, Stephane; Grandjean, Stephane; Robisson, Anne-Charlotte; Jolivet, Jean-Pierre

    2010-03-01

    Recent concepts for nuclear fuel and targets for transmuting long-lived radionuclides (minor actinides) and for the development of innovative Gen-IV nuclear fuel cycles imply fabricating host phases for actinide or mixed actinide compounds. Cubic stabilized zirconia (Zr, Y, Am)O(2-x) is one of the mixed phases tested in transmutation experiments. Wet chemical routes as an alternative to the powder metallurgy are being investigated to obtain the required phases while minimizing the handling of contaminating radioactive powder. Hydrolysis of zirconium, neodymium (a typical surrogate for americium) and yttrium in aqueous media in the presence of acetylacetone was firstly investigated. Progressive hydrolysis of zirconium acetylacetonate and sorption of trivalent cations and acacH on the zirconia particles led to a stable dispersion of nanoparticles (5-7 nm) in the 6-7 pH range. This sol gels with time or with temperature. The application to americium-containing solutions was then successfully tested: a stable sol was synthesized, characterized and used to prepare cubic stabilized zirconia (Zr, Y, Am)O(2-x). PMID:20162199

  16. Determination of Atto- to Femtogram Levels of Americium and Curium Isotopes in Large-Volume Urine Samples by Compact Accelerator Mass Spectrometry.

    PubMed

    Dai, Xiongxin; Christl, Marcus; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2016-03-01

    Ultralow level analysis of actinides in urine samples may be required for dose assessment in the event of internal exposures to these radionuclides at nuclear facilities and nuclear power plants. A new bioassay method for analysis of sub-femtogram levels of Am and Cm in large-volume urine samples was developed. Americium and curium were co-precipitated with hydrous titanium oxide from the urine matrix and purified by column chromatography separation. After target preparation using mixed titanium/iron oxides, the final sample was measured by compact accelerator mass spectrometry. Urine samples spiked with known quantities of Am and Cm isotopes in the range of attogram to femtogram levels were measured for method evaluation. The results are in good agreement with the expected values, demonstrating the feasibility of compact accelerator mass spectrometry (AMS) for the determination of minor actinides at the levels of attogram/liter in urine samples to meet stringent sensitivity requirements for internal dosimetry assessment. PMID:26822907

  17. Toward understanding the thermodynamics of TALSPEAK process. Medium effects on actinide complexation

    SciTech Connect

    Peter R Zalupski; Leigh R Martin; Ken Nash; Yoshinobu Nakamura; Masahiko Yamamoto

    2009-07-01

    The ingenious combination of lactate and diethylenetriamine-N,N,N’,N”,N”-pentaacetic acid (DTPA) as an aqueous actinide-complexing medium forms the basis of the successful separation of americium and curium from lanthanides known as the TALSPEAK process. While numerous reports in the prior literature have focused on the optimization of this solvent extraction system, considerably less attention has been devoted to the understanding of the basic thermodynamic features of the complex fluids responsible for the separation. The available thermochemical information of both lactate and DTPA protonation and metal complexation reactions are representative of the behavior of these ions under idealized conditions. Our previous studies of medium effects on lactate protonation suggest that significant departures from the speciation predicted based on reported thermodynamic values should be expected in the TALSPEAK aqueous environment. Thermodynamic parameters describing the separation chemistry of this process thus require further examination at conditions significantly removed from conventional ideal systems commonly employed in fundamental solution chemistry. Such thermodynamic characterization is the key to predictive modelling of TALSPEAK. Improved understanding will, in principle, allow process technologists to more efficiently respond to off-normal conditions during large scale process operation. In this report, the results of calorimetric and potentiometric investigations of the effects of aqueous electrolytes on the thermodynamic parameters for lactate protonation and lactate complexation of americium and neodymium will be presented. Studies on the lactate protonation equilibrium will clearly illustrate distinct thermodynamic variations between strong electrolyte aqueous systems and buffered lactate environment.

  18. Redox reactions and complex formation of transplutonium elements in solutions

    SciTech Connect

    Krot, N.N.; Myasoedov, B.F.

    1986-01-01

    This paper gives a brief analysis of the kinetics and mechanism of a number of redox processes and the complex formation of transplutonium elements in unusual oxidation states. The composition and strength of complexes of TPE with various addends have been determined. The new experimental data on the oxidation potentials of americium and berkelium ions in solutions are cited in abbreviated form. It follows from the data that in phosphoric acid solutions, when the H/sub 3/PO/sub 4/ concentration is increased from 10 to 15 M, the oxidation potential of the couple Am(IV)-Am(III) decreases. The oxidation potentials of the couples Am(VI)-Am(V), Cm(V)-Cm(IV), and Bk(IV)Bk(III) are also presented.

  19. Actinide Oxidation State and O/M Ratio in Hypostoichiometric Uranium-Plutonium-Americium U0.750Pu0.246Am0.004O2-x Mixed Oxides.

    PubMed

    Vauchy, Romain; Belin, Renaud C; Robisson, Anne-Charlotte; Lebreton, Florent; Aufore, Laurence; Scheinost, Andreas C; Martin, Philippe M

    2016-03-01

    Innovative americium-bearing uranium-plutonium mixed oxides U1-yPuyO2-x are envisioned as nuclear fuel for sodium-cooled fast neutron reactors (SFRs). The oxygen-to-metal (O/M) ratio, directly related to the oxidation state of cations, affects many of the fuel properties. Thus, a thorough knowledge of its variation with the sintering conditions is essential. The aim of this work is to follow the oxidation state of uranium, plutonium, and americium, and so the O/M ratio, in U0.750Pu0.246Am0.004O2-x samples sintered for 4 h at 2023 K in various Ar + 5% H2 + z vpm H2O (z = ∼ 15, ∼ 90, and ∼ 200) gas mixtures. The O/M ratios were determined by gravimetry, XAS, and XRD and evidenced a partial oxidation of the samples at room temperature. Finally, by comparing XANES and EXAFS results to that of a previous study, we demonstrate that the presence of uranium does not influence the interactions between americium and plutonium and that the differences in the O/M ratio between the investigated conditions is controlled by the reduction of plutonium. We also discuss the role of the homogeneity of cation distribution, as determined by EPMA, on the mechanisms involved in the reduction process. PMID:26907589

  20. Americium, plutonium and uranium contamination and speciation in well waters, streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site, Kazakhstan.

    PubMed

    León Vintró, L; Mitchell, P I; Omarova, A; Burkitbayev, M; Jiménez Nápoles, H; Priest, N D

    2009-04-01

    New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel'kem 1 and Tel'kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that (241)Am, (239,240)Pu and (238)U concentrations in well waters within the study area are in the range 0.04-87mBq dm(-3), 0.7-99mBq dm(-3), and 74-213mBq dm(-3), respectively, and for (241)Am and (239,240)Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01mBq dm(-3), 0.08mBq dm(-3) and 0.32mBq dm(-3) for (241)Am, (239,240)Pu and (238)U, respectively. The (235)U/(238)U isotopic ratio in almost all well and stream waters is slightly elevated above the 'best estimate' value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53-85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11-42microSv (mean 21microSv). Presently, the ground water feeding these wells would not appear to be contaminated with

  1. Determination of solubility products of complex compounds of certain lanthanide and actinide diiodies with 18-crown-6 in tetrahydrofuran

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Kulyukhin, S.A.

    1988-09-01

    The existence of divalent americium in a tetrahydrofuran (THF) solution was proved for the first time. The values of the solubility products (SP) of the complex compounds with the composition of MeI{sub 2}{centered dot}18-crown-6 (Me = Sm, Eu, Yb, Am, Cf, Es, Fm) in the THF solutions were determined by the cocrystallization method. The SP values obtained are within (5.9-7.9){centered dot}10{sup {minus}12} and are close to the SP value for SrI{sub 2}{centered dot}10{sup {minus}12}, which indicates a similarity in the properties of these elements.

  2. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution

    SciTech Connect

    Mincher, Bruce J.; Schmitt, Nicholas C.; Schuetz, Brian K.; Shehee, Thomas C.; Hobbs, David T.

    2015-03-11

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent has not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. Furthermore, the utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.

  3. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution.

    SciTech Connect

    Bruce J. Mincher; Nicholas C. Schmitt

    2015-03-01

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent has not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. The utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.

  4. Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution

    DOE PAGESBeta

    Mincher, Bruce J.; Schmitt, Nicholas C.; Schuetz, Brian K.; Shehee, Thomas C.; Hobbs, David T.

    2015-03-11

    The peroxydisulfate anion has long been used for the preparation of hexavalent americium (AmVI) from the normally stable AmIII valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (AmV) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of AmVI. Incomplete oxidation would be expected to leave residual AmIII, or to produce AmV in treated solutions. However, until recently, the use of peroxydisulfate as an AmV reagent hasmore » not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative AmV was prepared in an acidic solution and the UV/Vis extinction coefficients of the AmV 513 nm peak were measured over a range of nitric acid concentrations. Furthermore, the utility of AmV for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.« less

  5. Determining the americium transmutation rate and fission rate by post-irradiation examination within the scope of the ECRIX-H experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Pontillon, Y.; Esbelin, E.; Béjaoui, S.; Pasquet, B.; Bourdot, P.; Bonnerot, J. M.

    2013-09-01

    The ECRIX-H experiment aims to assess the feasibility of transmuting americium micro-dispersed in an inert magnesia matrix under a locally moderated neutron flux in the Phénix reactor. A first set of examinations demonstrated that pellet behaviour was satisfactory with moderate swelling at the end of the irradiation. Additional post-irradiation examinations needed to be conducted to confirm the high transmutation rate so as to definitively conclude on the success of the ECRIX-H experiment. This article presents and discusses the results of these new examinations. They confirm the satisfactory behaviour of the MgO matrix not only during the basic irradiation but also during post-irradiation thermal transients. These examinations also provide additional information on the behaviour of fission products both in the americium-based particles and in the MgO matrix. These results particularly validate the transmutation rate predicted by the calculation codes using several different analytical techniques. The fission rate is also determined. Moderate pellet swelling under irradiation (6.7 vol.%), while only 23% of the produced He and 4% of the fission gases were released from the fuel. No interaction between the pellets and the cladding. Formation of bubbles due to the precipitation of fission gases and He mainly in bubbles located inside the americium-based particles. These bubbles are the main cause of macroscopic swelling in the pellets. Well-crystallised structure of the MgO matrix which shows no amorphisation after irradiation despite the presence of fission products. The absence of any reaction of MgO with the americium-based phase, Formation of a PuO2-type crystalline phase from AmO1.62 particles following the Am transmutation process. A shielded electron probe micro-analyser (EPMA) 'CAMECA' Camebax equipped to collect and exploit the measurements using the 'SAMx' system. A Philips XL30 scanning electron microscope (SEM). Field acquisitions were performed thanks to

  6. Thermodynamic and Spectroscopic Studies of Trivalent f -element Complexation with Ethylenediamine- N,N '-di(acetylglycine)- N,N '-diacetic Acid

    DOE PAGESBeta

    Heathman, Colt R.; Grimes, Travis S.; Zalupski, Peter R.

    2016-03-21

    In this study, the coordination behavior and thermodynamic features of complexation of trivalent lanthanides and americium by ethylenediamine-N,N'-di(acetylglycine)-N,N'-diacetic acid (EDDAG-DA) (bisamide-substituted-EDTA) were investigated by potentiometric and spectroscopic techniques. Acid dissociation constants (Ka) and complexation constants (β) of lanthanides (except Pm) were determined by potentiometric analysis. Absorption spectroscopy was used to determine stability constants for the binding of trivalent americium and neodymium by EDDAG-DA under similar conditions. The potentiometry revealed 5 discernible protonation constants and 3 distinct metal–ligand complexes (identified as ML–, MHL, and MH2L+). Time-resolved fluorescence studies of Eu-(EDDAG-DA) solutions (at varying pH) identified a constant inner-sphere hydration number ofmore » 3, suggesting that glycine functionalities contained in the amide pendant arms are not involved in metal complexation and are protonated under more acidic conditions. The thermodynamic studies identified that f-element coordination by EDDAG-DA is similar to that observed for ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA). However, coordination via two amidic oxygens of EDDAG-DA lowers its trivalent f-element complex stability by roughly 3 orders of magnitude relative to EDTA.« less

  7. Thermodynamic and Spectroscopic Studies of Trivalent f-element Complexation with Ethylenediamine-N,N'-di(acetylglycine)-N,N'-diacetic Acid.

    PubMed

    Heathman, Colt R; Grimes, Travis S; Zalupski, Peter R

    2016-03-21

    The coordination behavior and thermodynamic features of complexation of trivalent lanthanides and americium by ethylenediamine-N,N'-di(acetylglycine)-N,N'-diacetic acid (EDDAG-DA) (bisamide-substituted-EDTA) were investigated by potentiometric and spectroscopic techniques. Acid dissociation constants (K(a)) and complexation constants (β) of lanthanides (except Pm) were determined by potentiometric analysis. Absorption spectroscopy was used to determine stability constants for the binding of trivalent americium and neodymium by EDDAG-DA under similar conditions. The potentiometry revealed 5 discernible protonation constants and 3 distinct metal-ligand complexes (identified as ML(-), MHL, and MH2L(+)). Time-resolved fluorescence studies of Eu-(EDDAG-DA) solutions (at varying pH) identified a constant inner-sphere hydration number of 3, suggesting that glycine functionalities contained in the amide pendant arms are not involved in metal complexation and are protonated under more acidic conditions. The thermodynamic studies identified that f-element coordination by EDDAG-DA is similar to that observed for ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA). However, coordination via two amidic oxygens of EDDAG-DA lowers its trivalent f-element complex stability by roughly 3 orders of magnitude relative to EDTA. PMID:26930023

  8. Selective Extraction of Americium(III) over Europium(III) with the Pyridylpyrazole Based Tetradentate Ligands: Experimental and Theoretical Study.

    PubMed

    Wang, Jieru; Su, Dongping; Wang, Dongqi; Ding, Songdong; Huang, Chao; Huang, Huang; Hu, Xiaoyang; Wang, Zhipeng; Li, Shimeng

    2015-11-16

    1,3-Bis[3-(2-pyridyl)pyrazol-1-yl]propane (Bippp) and 1,2-bis[3-(2-pyridyl)pyrazyl-1-methyl]benzene (Dbnpp), the pyridylpyrazole based tetradentate ligands, were synthesized and characterized by MS, NMR, and FT-IR. The solvent extraction and complexation behaviors of Am(III) and Eu(III) with the ligands were investigated experimentally and theoretically. In the presence of 2-bromohexanoic acid, the two ligands can effectively extract Am(III) over Eu(III) and other rare earth(III) metals (RE(III)) in HNO3 solution with the separation factors (SFAm/RE) ranging from 15 to 60. Slope analyses showed that both Am(III) and Eu(III) were extracted as monosolvated species, which agrees well with the results observed from X-ray crystallography and MS analyses. The stability constants (log K) obtained from UV-vis titration for Eu(III) complexes with Bippp and Dbnpp are 4.75 ± 0.03 and 4.45 ± 0.04, respectively. Both UV-vis titration and solvent extraction studies indicated that Bippp had stronger affinity for Eu(III) than Dbnpp, which is confirmed by density functional theory (DFT) calculations. DFT calculations revealed that the AmL(NO3)3 (L = Bippp and Dbnpp) complexes are thermodynamically more stable in water than their Eu(III) analogues, which is caused by greater covalency of the Am-N than Eu-N bonds. Theoretical studies gave an insight into the nature of the M(III)-ligand bonding interactions. PMID:26517736

  9. The Partitioning of Americium and the Lanthanides Using Tetrabutyldiglycolamide (TBDGA) in Octanol and in Ionic Liquid Solution

    SciTech Connect

    M.E. Mincher; D.L. Quach; Y.J. Liao; B.J. Mincher; C.M. Wai

    2012-11-01

    Separations among the lanthanides and the separation of Am from the lanthanides remain challenging, and research in this area continues to expand. The separation of adjacent lanthanides is of interest to high-tech industries because individual lanthanides have specialized uses and are in short supply. In nuclear fuel cycle applications Am would be incorporated into fast reactor fuels, yet the lanthanides are not desired. In this work the diamide N,N,N',N'-tetrabutyldiglycolamide (TBDGA) was investigated as a ligand for lanthanide and Am solvent extraction in both molecular and room temperature ionic liquid (RTIL) diluents. The RTIL [C4MIM][Tf2N-] showed very high extraction efficiency for these trivalent metals from low nitric acid concentrations, while the molecular diluent 1-octanol showed high extraction efficiency at high acid concentrations. This was attributed to the extraction of ionic nitrate complexes by the RTIL, whereas 1-octanol extracted neutral nitrate complexes. TBDGA in RTIL did not provide adequate separation factors for Am/lanthanide partitioning, but 1-octanol did show reasonable separation possibilities. Lanthanide intergroup separations appeared to be feasible in both diluents, but with higher separation factors from 1-octanol.

  10. New insight into self-irradiation effects on local and long-range structure of uranium-americium mixed oxides (through XAS and XRD).

    PubMed

    Lebreton, Florent; Martin, Philippe M; Horlait, Denis; Bès, René; Scheinost, Andreas C; Rossberg, Andre; Delahaye, Thibaud; Blanchart, Philippe

    2014-09-15

    Uranium-americium mixed oxides could be used as transmutation targets to lower Am inventory in spent nuclear fuels. Due to (241)Am activity, these materials are subjected to α-self-irradiation which provokes crystallographic disorder. Previous studies on U-Am mixed oxides gave first insight into α-radiation tolerance of these compounds, but have never been carried out for more than a year, whereas these compounds might be stored up to a few years between fabrication and irradiation. In this work, we study effects of self-irradiation on the structure of U(1-x)Am(x)O(2±δ) solid solutions (x = 0.15 and 0.20) aged 3 to 4 years. Especially, X-ray diffraction and X-ray absorption spectroscopy are combined to observe these effects from both long-range and local perspectives. Results show that the fluorite-type structure of U-Am mixed oxides withstands (241)Am α-irradiation without major damage. Despite the increase of interatomic distances and crystallographic disorder observed during the first months of storage, the present results show that a steady state is then reached. Thus, no detrimental factors have been identified in this study in terms of structural damage for several-year storage of U(1-x)Am(x)O(2±δ) pellets before irradiation. Furthermore, comparison between long-range and local evolution suggests that α-self-irradiation-induced defects are mainly located in low-ordered domains. Based on literature data and present results, the steady state appears related to the equilibrium between radioinduced defect formation and material self-healing. PMID:25162209

  11. A spectrophotometric study of Am(III) complexation with nitrate in aqueous solution at elevated temperatures.

    PubMed

    Tian, Guoxin; Shuh, David K

    2014-10-21

    The complexation of americium(iii) with nitrate was studied at temperatures from 10 to 85 °C in 1 M HNO3-HClO4 by spectrophotometry. The 1 : 1 complex species, AmNO3(2+), was identified and the stability constants were calculated from the absorption spectra recorded for titrations at several temperatures. Specific ion interaction theory (SIT) was used for ionic strength corrections to obtain the stability constants of AmNO3(2+) at infinite dilution and variable temperatures. The absorption spectra of Am(iii) in diluted HClO4 were also reviewed, and the molar absorptivity of Am(iii) at around 503 nm and 813 nm was re-calibrated by titrations with standardized DTPA solutions to determine the concentration of Am(iii). PMID:24999760

  12. LITERATURE REVIEW ON THE SORPTION OF PLUTONIUM, URANIUM, NEPTUNIUM, AMERICIUM AND TECHNETIUM TO CORROSION PRODUCTS ON WASTE TANK LINERS

    SciTech Connect

    Li, D.; Kaplan, D.

    2012-02-29

    The Savannah River Site (SRS) has conducted performance assessment (PA) calculations to determine the risk associated with closing liquid waste tanks. The PA estimates the risk associated with a number of scenarios, making various assumptions. Throughout all of these scenarios, it is assumed that the carbon-steel tank liners holding the liquid waste do not sorb the radionuclides. Tank liners have been shown to form corrosion products, such as Fe-oxyhydroxides (Wiersma and Subramanian 2002). Many corrosion products, including Fe-oxyhydroxides, at the high pH values of tank effluent, take on a very strong negative charge. Given that many radionuclides may have net positive charges, either as free ions or complexed species, it is expected that many radionuclides will sorb to corrosion products associated with tank liners. The objective of this report was to conduct a literature review to investigate whether Pu, U, Np, Am and Tc would sorb to corrosion products on tank liners after they were filled with reducing grout (cementitious material containing slag to promote reducing conditions). The approach was to evaluate radionuclides sorption literature with iron oxyhydroxide phases, such as hematite ({alpha}-Fe{sub 2}O{sub 3}), magnetite (Fe{sub 3}O{sub 4}), goethite ({alpha}-FeOOH) and ferrihydrite (Fe{sub 2}O{sub 3} {center_dot} 0.5H{sub 2}O). The primary interest was the sorption behavior under tank closure conditions where the tanks will be filled with reducing cementitious materials. Because there were no laboratory studies conducted using site specific experimental conditions, (e.g., high pH and HLW tank aqueous and solid phase chemical conditions), it was necessary to extend the literature review to lower pH studies and noncementitious conditions. Consequently, this report relied on existing lower pH trends, existing geochemical modeling, and experimental spectroscopic evidence conducted at lower pH levels. The scope did not include evaluating the appropriateness

  13. Impact of the cation distribution homogeneity on the americium oxidation state in the U0.54Pu0.45Am0.01O2-x mixed oxide

    NASA Astrophysics Data System (ADS)

    Vauchy, Romain; Robisson, Anne-Charlotte; Martin, Philippe M.; Belin, Renaud C.; Aufore, Laurence; Scheinost, Andreas C.; Hodaj, Fiqiri

    2015-01-01

    The impact of the cation distribution homogeneity of the U0.54Pu0.45Am0.01O2-x mixed oxide on the americium oxidation state was studied by coupling X-ray diffraction (XRD), electron probe micro analysis (EPMA) and X-ray absorption spectroscopy (XAS). Oxygen-hypostoichiometric Am-bearing uranium-plutonium mixed oxide pellets were fabricated by two different co-milling based processes in order to obtain different cation distribution homogeneities. The americium was generated from β- decay of 241Pu. The XRD analysis of the obtained compounds did not reveal any structural difference between the samples. EPMA, however, revealed a high homogeneity in the cation distribution for one sample, and substantial heterogeneity of the U-Pu (so Am) distribution for the other. The difference in cation distribution was linked to a difference in Am chemistry as investigated by XAS, with Am being present at mixed +III/+IV oxidation state in the heterogeneous compound, whereas only Am(IV) was observed in the homogeneous compound. Previously reported discrepancies on Am oxidation states can hence be explained by cation distribution homogeneity effects.

  14. An ab initio study of the adsorption and dissociation of molecular oxygen on the (0 0 0 1) surface of double hexagonal close-packed americium

    NASA Astrophysics Data System (ADS)

    Dholabhai, Pratik P.; Atta-Fynn, Raymond; Ray, Asok K.

    2008-12-01

    In our continuing attempts to understand theoretically various surface properties such as corrosion and potential catalytic activity of actinide surfaces in the presence of environmental gases, we report here the first ab initio study of molecular adsorption on the double hexagonal close-packed (dhcp) americium (Am) (0 0 0 1) surface. Specifically, molecular oxygen adsorption on the (0 0 0 1) surface of dhcp Am has been studied in detail within the framework of density functional theory using a full-potential all-electron linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method. Dissociative adsorption is found to be energetically more favorable compared to molecular adsorption. Chemisorption energies were optimized with respect to the distance of adsorbates from the surface for three approach positions at three adsorption sites, namely t1 (one-fold top), b2 (two-fold bridge), and h3 (three-fold hollow) sites. Chemisorption energies were computed at the scalar-relativistic-no-spin-orbit-coupling (SR-NSOC) and at the fully relativistic-with-spin-orbit-coupling (FR-SOC) levels of theory. The most stable configuration corresponds to a horizontal approach molecular dissociation with the oxygen atoms occupying neighboring h3 sites, with chemisorption energies at the NSOC and SOC theoretical levels being 9.395 and 9.886 eV, respectively. The corresponding distances of the oxygen molecule from the surface and oxygen-oxygen distance were found to be 0.953 and 3.731 Å, respectively. Overall our calculations indicate that chemisorption energies in cases with SOC are slightly more stable than those with NSOC in the 0.089-0.493 eV range. The work functions and net magnetic moments, respectively, increased and decreased in all cases compared to corresponding quantities of the bare dhcp-Am (0 0 0 1) surface. Adsorbate-substrate interactions have been analyzed in detail using partial charges inside muffin-tin spheres, difference charge density distributions, and

  15. Determining the americium transmutation rate and fission rate by post-irradiation examination within the scope of the ECRIX-H experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Pontillon, Y.; Esbelin, E.; Béjaoui, S.; Pasquet, B.; Bourdot, P.; Bonnerot, J. M.

    2013-09-01

    The ECRIX-H experiment aims to assess the feasibility of transmuting americium micro-dispersed in an inert magnesia matrix under a locally moderated neutron flux in the Phénix reactor. A first set of examinations demonstrated that pellet behaviour was satisfactory with moderate swelling at the end of the irradiation. Additional post-irradiation examinations needed to be conducted to confirm the high transmutation rate so as to definitively conclude on the success of the ECRIX-H experiment. This article presents and discusses the results of these new examinations. They confirm the satisfactory behaviour of the MgO matrix not only during the basic irradiation but also during post-irradiation thermal transients. These examinations also provide additional information on the behaviour of fission products both in the americium-based particles and in the MgO matrix. These results particularly validate the transmutation rate predicted by the calculation codes using several different analytical techniques. The fission rate is also determined. Moderate pellet swelling under irradiation (6.7 vol.%), while only 23% of the produced He and 4% of the fission gases were released from the fuel. No interaction between the pellets and the cladding. Formation of bubbles due to the precipitation of fission gases and He mainly in bubbles located inside the americium-based particles. These bubbles are the main cause of macroscopic swelling in the pellets. Well-crystallised structure of the MgO matrix which shows no amorphisation after irradiation despite the presence of fission products. The absence of any reaction of MgO with the americium-based phase, Formation of a PuO2-type crystalline phase from AmO1.62 particles following the Am transmutation process. A shielded electron probe micro-analyser (EPMA) 'CAMECA' Camebax equipped to collect and exploit the measurements using the 'SAMx' system. A Philips XL30 scanning electron microscope (SEM). Field acquisitions were performed thanks to

  16. Recovering Americium and Curium from Mark-42 Target Materials- New Processing Approaches to Enhance Separations and Integrate Waste Stream Disposition - 12228

    SciTech Connect

    Patton, Brad D.; Benker, Dennis; Collins, Emory D.; Mattus, Catherine H.; Robinson, Sharon M.; Wham, Robert M.

    2012-07-01

    Oak Ridge National Laboratory (ORNL) is investigating flowsheets to enhance processing efficiencies and to address waste streams associated with recovery of americium (Am) and curium (Cm) from Mark-42 (Mk-42) target materials stored at ORNL. The objective of this work was to identify the most effective flowsheet with which to process the 104 Mk-42 oxide capsules holding a total of 80 g of plutonium (Pu), 190 g of Cm, 480 g of Am, and 5 kg of lanthanide (Ln) oxides for the recovery and purification of the Am/Cm for future use as feedstock for heavy actinide production. Studies were also conducted to solidify the process flowsheet waste streams for disposal. ORNL is investigating flowsheets to enhance processing efficiencies and address waste streams associated with recovery of Am and Cm from Mk-42 target materials stored at ORNL. A series of small-scale runs are being performed to demonstrate an improved process to recover Am/Cm and to optimize the separations of Ln fission products from the Am/Cm constituents. The first of these runs has been completed using one of the Am/Cm/Ln oxide capsules stored at ORNL. The demonstration run showed promising results with a Ln DF of 40 for the Am/Cm product and an Am/Cm DF of 75 for the Ln product. In addition, the total losses of Am, Cm, and Ln to the waste solvents and raffinates were very low at <0.2%, 0.02%, and 0.04%, respectively. However, the Ln-actinide separation was less than desired. For future Reverse TALSPEAK demonstration runs, several parameters will be adjusted (flow rates, the ratio of scrub to strip stages, etc.) to improve the removal of Ln from the actinides. The next step will also include scale-up of the processing flowsheet to use more concentrated solutions (15 g/L Ln versus 5 g/L) and larger volumes and to recycle the HDEHP solvent. This should improve the overall processing efficiency and further reduce losses to waste streams. Studies have been performed with simulated wastes to develop solidification

  17. Actinide-specific complexing agents: their structural and solution chemistry

    SciTech Connect

    Raymond, K.N.; Freeman, G.E.; Kappel, M.J.

    1983-07-01

    The synthesis of a series of tetracatecholate ligands designed to be specific for Pu(IV) and other actinide(IV) ions has been achieved. Although these compounds are very effective as in vivo plutonium removal agents, potentiometric and voltammetric data indicate that at neutral pH full complexation of the Pu(IV) ion by all four catecholate groups does not occur. Spectroscopic results indicate that the tetracatecholates, 3,4,3-LICAMS and 3,4,3-LICAMC, complex Am(III). The Am(IV)/(III)-catecholate couple (where catecholate = 3,4,3-LICAMS or 3,4,3-LICAMC) is not observed, but may not be observable due to the large currents associated with ligand oxidation. However, within the potential range where ligand oxidation does not occur, these experiments indicate that the reduction potential of free Am(IV)/(III) is probably greater than or equal to + 2.6 V vs NHE or higher. Proof of the complexation of americium in the trivalent oxidation state by 3,4,3-LICAMS and 3,4,3-LICAMC elimates the possibility of tetracatholates stabilizing Am(IV) in vivo.

  18. Complexity Survey.

    ERIC Educational Resources Information Center

    Gordon, Sandra L.; Anderson, Beth C.

    To determine whether consensus existed among teachers about the complexity of common classroom materials, a survey was administered to 66 pre-service and in-service kindergarten and prekindergarten teachers. Participants were asked to rate 14 common classroom materials as simple, complex, or super-complex. Simple materials have one obvious part,…

  19. Communication complexity and information complexity

    NASA Astrophysics Data System (ADS)

    Pankratov, Denis

    Information complexity enables the use of information-theoretic tools in communication complexity theory. Prior to the results presented in this thesis, information complexity was mainly used for proving lower bounds and direct-sum theorems in the setting of communication complexity. We present three results that demonstrate new connections between information complexity and communication complexity. In the first contribution we thoroughly study the information complexity of the smallest nontrivial two-party function: the AND function. While computing the communication complexity of AND is trivial, computing its exact information complexity presents a major technical challenge. In overcoming this challenge, we reveal that information complexity gives rise to rich geometrical structures. Our analysis of information complexity relies on new analytic techniques and new characterizations of communication protocols. We also uncover a connection of information complexity to the theory of elliptic partial differential equations. Once we compute the exact information complexity of AND, we can compute exact communication complexity of several related functions on n-bit inputs with some additional technical work. Previous combinatorial and algebraic techniques could only prove bounds of the form theta( n). Interestingly, this level of precision is typical in the area of information theory, so our result demonstrates that this meta-property of precise bounds carries over to information complexity and in certain cases even to communication complexity. Our result does not only strengthen the lower bound on communication complexity of disjointness by making it more exact, but it also shows that information complexity provides the exact upper bound on communication complexity. In fact, this result is more general and applies to a whole class of communication problems. In the second contribution, we use self-reduction methods to prove strong lower bounds on the information

  20. Updated Evaluations for Americium Isotopes

    SciTech Connect

    Brown, D A; Pruet, J

    2005-09-22

    Here we describe evaluations for Am isotopes that will be included in the next release of ENDL. Current ENDL99 evaluations for these isotopes are quite outdated and almost entirely undocumented. Because Am is important for several DNT applications, and because quality evaluations are either readily available or easily calculated, the effort to update ENDL seems warranted. Results from good existing evaluations are adopted whenever possible. To this end we devote the next section of this report to a consideration of the availability of evaluations The quality of different evaluations as well as comparisons against experiments are also presented and used to motivate our choice of adopted data sets. Plans for modifying and improving adopted evaluations are also discussed. For {sup 240}Am there are no existing evaluations. To fill this gap, we are providing a new Am evaluation based on calculations with the statistical model reaction codes TALYS and EMPIRE. This evaluation is described below. The ENDF/B-VI formatted file containing this evaluation is given in the appendix.

  1. Phonon properties of americium phosphide

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-01

    Phonon properties of AmP have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmP are presented follow the same trend as observed in uranium phosphide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  2. Complex derivatives

    NASA Astrophysics Data System (ADS)

    Battiston, Stefano; Caldarelli, Guido; Georg, Co-Pierre; May, Robert; Stiglitz, Joseph

    2013-03-01

    The intrinsic complexity of the financial derivatives market has emerged as both an incentive to engage in it, and a key source of its inherent instability. Regulators now faced with the challenge of taming this beast may find inspiration in the budding science of complex systems.

  3. Designing Complexity

    ERIC Educational Resources Information Center

    Glanville, Ranulph

    2007-01-01

    This article considers the nature of complexity and design, as well as relationships between the two, and suggests that design may have much potential as an approach to improving human performance in situations seen as complex. It is developed against two backgrounds. The first is a world view that derives from second order cybernetics and radical…

  4. Carney Complex

    MedlinePlus

    ... Screening guidelines may change over time as new technologies are developed and more is learned about Carney complex. It is important to talk with your doctor about appropriate screening tests. Learn more about what to expect when having ...

  5. Complex networks: Patterns of complexity

    NASA Astrophysics Data System (ADS)

    Pastor-Satorras, Romualdo; Vespignani, Alessandro

    2010-07-01

    The Turing mechanism provides a paradigm for the spontaneous generation of patterns in reaction-diffusion systems. A framework that describes Turing-pattern formation in the context of complex networks should provide a new basis for studying the phenomenon.

  6. Complexation of N4-Tetradentate Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Meier, G. Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2012-12-06

    To improve understanding of aza-complexants in trivalent actinide–lanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV–visible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N0-bis(2-methylpyridyl)-1,2-diaminoethane, N,N0-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N’-bis(2-pyridylmethyl)piperazine, N,N’-bis-[pyridin-2-ylmethylene]ethane-1,2-diamine, and trans-N,Nbis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)– lanthanide(III) separation system.

  7. Researching Complexity.

    ERIC Educational Resources Information Center

    Sumara, Dennis J.

    2000-01-01

    Discusses what Complexity Theory (presented as a rubric that collects theoretical understandings from a number of domains such as ecology, biology, neurology, and education) suggests about mind, selfhood, intelligence, and practices of reading, and the import of these reconceptualizations to reader-response researchers. Concludes that developing…

  8. Complex Clouds

    Atmospheric Science Data Center

    2013-04-16

    ...     View Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired ... Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe ...

  9. Amorphic complexity

    NASA Astrophysics Data System (ADS)

    Fuhrmann, G.; Gröger, M.; Jäger, T.

    2016-02-01

    We introduce amorphic complexity as a new topological invariant that measures the complexity of dynamical systems in the regime of zero entropy. Its main purpose is to detect the very onset of disorder in the asymptotic behaviour. For instance, it gives positive value to Denjoy examples on the circle and Sturmian subshifts, while being zero for all isometries and Morse-Smale systems. After discussing basic properties and examples, we show that amorphic complexity and the underlying asymptotic separation numbers can be used to distinguish almost automorphic minimal systems from equicontinuous ones. For symbolic systems, amorphic complexity equals the box dimension of the associated Besicovitch space. In this context, we concentrate on regular Toeplitz flows and give a detailed description of the relation to the scaling behaviour of the densities of the p-skeletons. Finally, we take a look at strange non-chaotic attractors appearing in so-called pinched skew product systems. Continuous-time systems, more general group actions and the application to cut and project quasicrystals will be treated in subsequent work.

  10. Complex interactions

    NASA Astrophysics Data System (ADS)

    de Régules, Sergio

    2016-04-01

    Complexity science – which describes phenomena such as collective and emergent behaviour – is the focus of a new centre where researchers are examining everything from the spread of influenza to what a healthy heartbeat looks like. Sergio de Régules reports.

  11. Managing Complexity

    SciTech Connect

    Chassin, David P.; Posse, Christian; Malard, Joel M.

    2004-08-01

    Physical analogs have shown considerable promise for understanding the behavior of complex adaptive systems, including macroeconomics, biological systems, social networks, and electric power markets. Many of today’s most challenging technical and policy questions can be reduced to a distributed economic control problem. Indeed, economically-based control of large-scale systems is founded on the conjecture that the price-based regulation (e.g., auctions, markets) results in an optimal allocation of resources and emergent optimal system control. This paper explores the state of the art in the use physical analogs for understanding the behavior of some econophysical systems and to deriving stable and robust control strategies for them. In particular we review and discussion applications of some analytic methods based on the thermodynamic metaphor according to which the interplay between system entropy and conservation laws gives rise to intuitive and governing global properties of complex systems that cannot be otherwise understood.

  12. Measured solubilities and speciations from oversaturation experiments of neptunium, plutonium, and americium in UE-25p No. 1 well water from the Yucca Mountain region: Milestone report 3329-WBS1.2.3.4.1.3.1

    SciTech Connect

    Nitsche, H.; Roberts, K.; Prussin, T.; Mueller, A.; Becraft, K.; Keeney, D.; Carpenter, S.A.; Gatti, R.C.

    1994-04-01

    Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are a part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p No. 1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at two different temperatures (25{degree} and 60{degree}C) and three pH values (6.0, 7.0, 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations significantly decreased with increasing temperature at pH 6 and 7. The concentration at pH 8.5 hardly decreased at all with increasing temperature. At both temperatures the concentrations were highest at pH 8.5, lowest at pH 7, and in between at pH 6. For the americium/neodymium solutions, the solubility decreased significantly with increasing temperature and increased somewhat with increasing pH.

  13. Measured solubilities and speciations of neptunium, plutonium, and americium in a typical groundwater (J-13) from the Yucca Mountain region; Milestone report 3010-WBS 1.2.3.4.1.3.1

    SciTech Connect

    Nitsche, H.; Gatti, R.C.; Standifer, E.M.

    1993-07-01

    Solubility and speciation data are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, {sup 241}Am{sup 3+}/Nd{sup 3+}, and {sup 243}Am{sup 3+} in J-13 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at three different temperatures (25{degree}, 60{degree}, and 90{degree}C) and pH values (5.9, 7.0, and 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations decreased with increasing temperature and showed no trend with pH. The americium solutions showed no clear solubility trend with increasing temperature and increasing pH.

  14. Complex Systems

    PubMed Central

    Goldberger, Ary L.

    2006-01-01

    Physiologic systems in health and disease display an extraordinary range of temporal behaviors and structural patterns that defy understanding based on linear constructs, reductionist strategies, and classical homeostasis. Application of concepts and computational tools derived from the contemporary study of complex systems, including nonlinear dynamics, fractals and “chaos theory,” is having an increasing impact on biology and medicine. This presentation provides a brief overview of an emerging area of biomedical research, including recent applications to cardiopulmonary medicine and chronic obstructive lung disease. PMID:16921107

  15. [Carney complex].

    PubMed

    Kacerovská, D; Michal, M; Síma, R; Grossmann, P; Kazakov, D V

    2011-10-01

    Carney complex is a clinically and genetically heterogeneous disease, with at least two genetic loci including the PRKAR1A gene located on chromosome 17 and the CNC2 locus mapped to chromosome 2. Clinically this syndrome is characterized by multiple myxomas occurring in different anatomic sites, mucocutaneous pigmentary lesions, and a variety of non-endocrine and endocrine tumors, often causing endocrine abnormalities, involving various organs. Knowledge of morphological findings in CNC patients with their typical locations is necessary to raise suspicion of this syndrome by pathologists. Confirmation of the diagnosis allows regular clinical check-ups and early treatment of these patients. PMID:22145222

  16. Complex formation of Am(III) and Am(IV) with phosphate ions in acetonitrile solutions

    SciTech Connect

    Perevalov, S.A.; Lebedev, I.A.; Myasoedov, B.F.

    1988-05-01

    The first dissociation constant of H/sub 3/PO/sub 4/ in acetonitrile solution (K/sub 1//sup 0/ = 1.75/centered dot/10/sup /minus/13/) and the constant of formation of H(H/sub 2/PO/sub 4/)/sub 2//sup /minus// dimers (K/sub d//sup 0/ = 8/centered dot/10/sup 2/) were determined by the method of pH-potentiometry. The complex formation of Am(III) in acetonitrile solutions containing 0.05-2.0 M H/sub 3/PO/sub 4/ was investigated by a spectrophotometric method; the stability constants of the complexes AmH/sub 2/PO/sub 4//sup 2+/ (/beta//sub 1//sup III/ = 1.0/centered dot/10/sup 12/) and Am(H/sub 2/PO/sub 4/)/sub 2//sup +/ (/beta//sub 2//sup III/ = 4.3/centered dot/10/sup 24/) were determined. The formal potentials of the couple Am/sup (IV)//Am/sup (III)/ in 0.3-1.9 M solutions of H/sub 3/PO/sub 4/ in acetonitrile were measured, and the stability constant of the phosphate complex of tetravalent americium Am(H/sub 2/PO/sub 4/)/sub 3//sup +/ (/beta//sub 3//sup IV/ = 2.5/centered dot/10/sup 46/) was calculated according to the value of the shift of the potential relative to the standard.

  17. Carney complex.

    PubMed

    Espiard, Stéphanie; Bertherat, Jérôme

    2013-01-01

    Carney complex is a rare, dominantly inherited multiple endocrine neoplasia syndrome, affecting endocrine glands as the adrenal cortex (causing Cushing's syndrome), the pituitary and the thyroid. It is associated with many other nonendocrine tumors, including cardiac myxomas, testicular tumors, melanotic schwannoma, breast myxomatosis, and abnormal pigmentation (lentiginosis) or myxomas of the skin. The gene located on the CNC1 locus was identified 12 years ago as the regulatory subunit 1A (R1A) of the protein kinase A (PRKAR1A) located at 17q22-24. Inactivating heterozygous germline mutations of PRKAR1A are observed in about two thirds of Carney complex patients with some genotype-phenotype correlation useful for follow-up and prognosis. More rarely, mutations of phosphodiesterase genes have been reported in patients presenting mainly with Cushing's syndrome. In vitro and in vivo studies help to understand how R1A inactivation leads to tumorigenesis. PRKAR1A appears to be a relatively weak tumorigenic signal which can cooperate with other signaling pathways and tumor suppressors. PMID:23652670

  18. Cosmic Complexity

    NASA Technical Reports Server (NTRS)

    Mather, John C.

    2012-01-01

    What explains the extraordinary complexity of the observed universe, on all scales from quarks to the accelerating universe? My favorite explanation (which I certainty did not invent) ls that the fundamental laws of physics produce natural instability, energy flows, and chaos. Some call the result the Life Force, some note that the Earth is a living system itself (Gaia, a "tough bitch" according to Margulis), and some conclude that the observed complexity requires a supernatural explanation (of which we have many). But my dad was a statistician (of dairy cows) and he told me about cells and genes and evolution and chance when I was very small. So a scientist must look for me explanation of how nature's laws and statistics brought us into conscious existence. And how is that seemll"!gly Improbable events are actually happening a!1 the time? Well, the physicists have countless examples of natural instability, in which energy is released to power change from simplicity to complexity. One of the most common to see is that cooling water vapor below the freezing point produces snowflakes, no two alike, and all complex and beautiful. We see it often so we are not amazed. But physlc!sts have observed so many kinds of these changes from one structure to another (we call them phase transitions) that the Nobel Prize in 1992 could be awarded for understanding the mathematics of their common features. Now for a few examples of how the laws of nature produce the instabilities that lead to our own existence. First, the Big Bang (what an insufficient name!) apparently came from an instability, in which the "false vacuum" eventually decayed into the ordinary vacuum we have today, plus the most fundamental particles we know, the quarks and leptons. So the universe as a whole started with an instability. Then, a great expansion and cooling happened, and the loose quarks, finding themselves unstable too, bound themselves together into today's less elementary particles like protons and

  19. Cosmic Complexity

    NASA Technical Reports Server (NTRS)

    Mather, John C.

    2012-01-01

    What explains the extraordinary complexity of the observed universe, on all scales from quarks to the accelerating universe? My favorite explanation (which I certainty did not invent) ls that the fundamental laws of physics produce natural instability, energy flows, and chaos. Some call the result the Life Force, some note that the Earth is a living system itself (Gaia, a "tough bitch" according to Margulis), and some conclude that the observed complexity requires a supernatural explanation (of which we have many). But my dad was a statistician (of dairy cows) and he told me about cells and genes and evolution and chance when I was very small. So a scientist must look for me explanation of how nature's laws and statistics brought us into conscious existence. And how is that seemll"!gly Improbable events are actually happening a!1 the time? Well, the physicists have countless examples of natural instability, in which energy is released to power change from simplicity to complexity. One of the most common to see is that cooling water vapor below the freezing point produces snowflakes, no two alike, and all complex and beautiful. We see it often so we are not amazed. But physlc!sts have observed so many kinds of these changes from one structure to another (we call them phase transitions) that the Nobel Prize in 1992 could be awarded for understanding the mathematics of their common features. Now for a few examples of how the laws of nature produce the instabilities that lead to our own existence. First, the Big Bang (what an insufficient name!) apparently came from an instability, in which the "false vacuum" eventually decayed into the ordinary vacuum we have today, plus the most fundamental particles we know, the quarks and leptons. So the universe as a whole started with an instability. Then, a great expansion and cooling happened, and the loose quarks, finding themselves unstable too, bound themselves together into today's less elementary particles like protons and

  20. Actinide halide complexes

    DOEpatents

    Avens, L.R.; Zwick, B.D.; Sattelberger, A.P.; Clark, D.L.; Watkin, J.G.

    1992-11-24

    A compound is described of the formula MX[sub n]L[sub m] wherein M is a metal atom selected from the group consisting of thorium, plutonium, neptunium or americium, X is a halide atom, n is an integer selected from the group of three or four, L is a coordinating ligand selected from the group consisting of aprotic Lewis bases having an oxygen-, nitrogen-, sulfur-, or phosphorus-donor, and m is an integer selected from the group of three or four for monodentate ligands or is the integer two for bidentate ligands, where the sum of n+m equals seven or eight for monodentate ligands or five or six for bidentate ligands. A compound of the formula MX[sub n] wherein M, X, and n are as previously defined, and a process of preparing such actinide metal compounds are described including admixing the actinide metal in an aprotic Lewis base as a coordinating solvent in the presence of a halogen-containing oxidant.

  1. Actinide halide complexes

    DOEpatents

    Avens, Larry R.; Zwick, Bill D.; Sattelberger, Alfred P.; Clark, David L.; Watkin, John G.

    1992-01-01

    A compound of the formula MX.sub.n L.sub.m wherein M is a metal atom selected from the group consisting of thorium, plutonium, neptunium or americium, X is a halide atom, n is an integer selected from the group of three or four, L is a coordinating ligand selected from the group consisting of aprotic Lewis bases having an oxygen-, nitrogen-, sulfur-, or phosphorus-donor, and m is an integer selected from the group of three or four for monodentate ligands or is the integer two for bidentate ligands, where the sum of n+m equals seven or eight for monodentate ligands or five or six for bidentate ligands, a compound of the formula MX.sub.n wherein M, X, and n are as previously defined, and a process of preparing such actinide metal compounds including admixing the actinide metal in an aprotic Lewis base as a coordinating solvent in the presence of a halogen-containing oxidant, are provided.

  2. Effects of soluble organic complexants and their degradation products on the removal of selected radionuclides from high-level waste. Part II: Distributions of Sr, Cs, Tc, and Am onto 32 absorbers from four variations of Hanford tank 101-SY simulant solution

    SciTech Connect

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1995-04-01

    Many of the radioactive waste storage tanks at U.S. Department of Energy facilities contain organic compounds that have been degraded by radiolysis and chemical reactions during decades of storage. In this second part of our three-part investigation of the effects of soluble organic complexants and their degradation products, we measured the sorption of strontium, cesium, technetium, and americium onto 32 absorbers that offer high sorption of these elements in the absence of organic complexants. The four solutions tested were (1) a simulant for a 3:1 dilution of Hanford Tank 101-SY contents that initially contained ethylenediaminetetraacetic acid (EDTA), (2) this simulant after gamma-irradiation to 34 Mrads, (3) the unirradiated simulant after treatment with a hydrothermal organic-destruction process, and (4) the irradiated simulant after hydrothermal processing. For each of 512 element/absorber/solution combinations, we measured distribution coefficients (Kds) twice for each period for dynamic contact periods of 30 min, 2 h, and 6 h to obtain information about sorption kinetics. On the basis of our 3,072 measured Kd values, the sorption of strontium and americium is significantly decreased by the organic components of the simulant solutions, whereas the sorption of cesium and technetium appears unaffected by the organic components of the simulant solutions.

  3. Chemical speciation of strontium, americium, and curium in high level waste: Predictive modeling of phase partitioning during tank processing. Annual progress report, October 1996--September 1997

    SciTech Connect

    Felmy, A.R.; Choppin, G.

    1997-12-31

    'The program at Florida State University was funded to collaborate with Dr. A. Felmy (PNNL) on speciation in high level wastes and with Dr. D. Rai (PNNL) on redox of Pu under high level waste conditions. The funding provided support for 3 research associates (postdoctoral researchers) under Professor G. R. Choppin as P.I. Dr. Kath Morris from U. Manchester (Great Britain), Dr. Dean Peterman and Dr. Amy Irwin (both from U. Cincinnati) joined the laboratory in the latter part of 1996. After an initial training period to become familiar with basic actinide chemistry and radiochemical techniques, they began their research. Dr. Peterman was assigned the task of measuring Th-EDTA complexation prior to measuring Pu(IV)-EDTA complexation. These studies are associated with the speciation program with Dr. Felmy. Drs. Morris and Irwin initiated research on redox of plutonium with agents present in the Hanford Tanks as a result of radiolysis or from use in separations. The preliminary results obtained thus far are described in this report. It is expected that the rate of progress will continue to increase significantly as the researchers gain more experience with plutonium chemistry.'

  4. Development of Fundamental Data on Chemical Speciation and Solubility for Strontium and Americium in High Level Waste: Predictive Modeling of Phase Partitioning During Tank Processing

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.; Campbell, James A.

    2000-06-01

    In this research program, Pacific Northwest National Laboratory (PNNL) and Florida State University (FSU) are investigating the speciation of Sr and Am/Cm in the presence of selected organic chelating agents (ethylenediaminetetraacetic acid (EDTA), N-(2- hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), and iminodiacetic acid (IDA)) over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high level waste tanks. The project is comprised of integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metal-chelate systems. This fundamental information is then used to develop thermodynamic models which allows the prediction of changes in chemical speciation and solubility which can occur in response to changes in tank processing conditions. In this way we can both develop new approaches that address fundamental problems in aqueous speciation and at the same time provide useful and practical information needed for tank processing.

  5. Development of Fundamental Data on Chemical Speciation and Solubility for Strontium and Americium in High- Level Waste: Predictive Modeling of Phase Partitioning During Tank Processing

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.

    2001-06-01

    In this research program, Pacific Northwest National Laboratory and Florida State University are investigating the speciation of Sr and Am/Cm in the presence of selected organic chelating agents (ethylenediaminetetraacetic acid [EDTA], N-(2-hydroxyethyl)ethylenediaminetriacetic acid [HEDTA], nitrilotriacetic acid [NTA], iminodiacetic acid [IDA], citrate, and oxalate) over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high-level waste stored in tanks at Hanford and other U.S. Department of Energy (DOE) sites. The project comprises integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metalchelate systems. This fundamental information then is used to develop thermodynamic models designed to predict changes in chemical speciation and solubility resulting from various tank processing conditions. In this way we can develop new approaches that address fundamental problems in aqueous speciation and, at the same time, provide useful and practical information needed for tank waste processing.

  6. [Carney complex].

    PubMed

    Losada Grande, Eladio José; Al Kassam Martínez, Daniel; González Boillos, Margarita

    2011-01-01

    Carney complex (CNC) is an autosomal dominantly inherited syndrome characterized by spotty skin pigmentation, cardiac and cutaneous myxoma, and endocrine overactivity. Skin pigmentation includes lentigines and blue nevi. Myxomas may occur in breast, skin and heart. Cardiac myxomas may be multiple and occur in any cardiac chamber, and are more prone to recurrence. The most common endocrine gland manifestation is an ACTH-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD). PPNAD may occur isolated, with no other signs of CNC. Pituitary and thyroid glands and gonads are also involved. The PRKAR1A gene, located in 17 q22-24, encodes type 1A regulatory subunit of protein kinase A. Inactivating germline mutations of this gene are found in 70% of patients with CNC. PRKAR1A is a key component of the c-AMP signaling pathway that has been implicated in endocrine tumorigenesis. Many different mutations have been reported in the PRKAR1A gene. In almost all cases the sequence change was predicted to lead to a premature stop codon and the resultant mutant mRNA was subject to nonsense-mediated mRNA decay. There is no clear genotype-phenotype correlation in patients with CNC. Genetic analysis should be performed in all CNC index cases. All affected patients should be monitored for clinical signs of CNC at least once a year. Genetic diagnosis allows for more effective preparation of more appropriate and effective therapeutic strategies and genetic counseling for patients and gene carriers, and to avoid unnecessary tests to relatives not carrying the gene. PMID:21536508

  7. Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

    SciTech Connect

    Clark, D.L.; Hobart, D.E.; Palmer, P.D.; Sullivan, J.C.; Stout, B.E.

    1992-07-01

    The uranyl(VI) carbonate system has been re-examined using {sup 13}C NMR of 99.9% {sup 13}C-enriched U{sup VI}O{sub 2} ({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} and Am{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR line-broadening techniques {sup 13}C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of {Delta}G{sup {double_dagger}}{sub 295} = 56 kJ/M, {Delta}H{sup {double_dagger}} = 38 kJ/M, and {Delta}S{sup {double_dagger}} = {minus}60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress.

  8. A calorimetric study of the hydrolysis and peroxide complex formation of the uranyl(VI) ion.

    PubMed

    Zanonato, Pier Luigi; Di Bernardo, Plinio; Grenthe, Ingmar

    2014-02-14

    The enthalpies of reaction for the formation of uranyl(vi) hydroxide {[(UO2)2(OH)2](2+), [(UO2)3(OH)4](2+), [(UO2)3(OH)5](+), [(UO2)3(OH)6](aq), [(UO2)3(OH)7](-), [(UO2)3(OH)8](2-), [(UO2)(OH)3](-), [(UO2)(OH)4](2-)} and peroxide complexes {[UO2(O2)(OH)](-) and [(UO2)2(O2)2(OH)](-)} have been determined from calorimetric titrations at 25 °C in a 0.100 M tetramethyl ammonium nitrate ionic medium. The hydroxide data have been used to test the consistency of the extensive thermodynamic database published by the Nuclear Energy Agency (I. Grenthe, J. Fuger, R. J. M. Konings, R. J. Lemire, A. B. Mueller, C. Nguyen-Trung and H. Wanner, Chemical Thermodynamics of Uranium, North-Holland, Amsterdam, 1992 and R. Guillaumont, T. Fanghänel, J. Fuger, I. Grenthe, V. Neck, D. J. Palmer and M. R. Rand, Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, Elsevier, Amsterdam, 2003). A brief discussion is given about a possible structural relationship between the trinuclear complexes [(UO2)3(OH)n](6-n), n = 4-8. PMID:24301256

  9. Development of Fundamental Data on Chemical Speciation and Solubility for Strontium and Americium in High-Level Waste: Predictive Modeling of Phase Partitioning During Tank Processing

    SciTech Connect

    Felmy, Andrew R.; Choppin, Gregory; Dixon, David A.

    2002-06-01

    In this project, Pacific Northwest National Laboratory (PNNL) and Florida State University (FSU) are investigating the speciation of Sr and Am/Cm in the presence of selected organic chelating agents over ranges of hydroxide, carbonate, ionic strength, and competing metal ion concentrations present in high-level waste (HLW) stored in tanks at Hanford and other U.S. Department of Energy (DOE) sites. The chelating agents that are being studied are EDTA (ethylenediaminetetraacetic acid), HEDTA (N-(2-hydroxyethyl)ethylenediaminetriacetic acid), NTA (nitrilotriacetic acid), IDA (iminodiacetic acid), citrate, and oxalate. The project comprises integrated research tasks that approach the problem of chemical speciation using macroscopic thermodynamic measurements of metal-ligand competition reactions, molecular modeling studies to identify structures or complexes of unusual stability, and mass spectrometry measurements of complex charge/mass ratio that can be applied to mixed metalchelate systems. This fundamental information then is used to develop thermodynamic models designed to predict changes in chemical speciation and solubility resulting from various tank processing conditions. In this way we can develop new approaches that address fundamental problems in aqueous speciation and, at the same time, provide useful and practical information needed for tank waste processing. Current strategies for reducing the total volume of radioactive tank waste requiring disposal at Hanford and other DOE sites call for the development of methods that can be used to selectively dissolve and remove non-radioactive elements, such as Al, P, and Cr, while retaining or precipitating the radioactive elements, including Sr and the actinide elements, in the tank sludge. This partitioning between solids and precipitates is fundamentally dependent on the chemical speciation of the elements present in the tank processing solutions. Of particular importance is separation of the radioactive and

  10. Coordination Modes of Americium in the Am2(C2O4)3(H2O)6·4H2O Oxalate: Synthesis, Crystal Structure, Spectroscopic Characterizations and Comparison in the M2(C2O4)3(H2O)6·nH2O (M = Ln, An) Series.

    PubMed

    Tamain, C; Arab-Chapelet, B; Rivenet, M; Legoff, X F; Loubert, G; Grandjean, S; Abraham, F

    2016-01-01

    Americium oxalate single crystals, Am2(C2O4)3(H2O)6·4H2O, were prepared by in situ oxalic acid generation by slow hydrolysis of the diester. Their structure was determined by single-crystal X-ray diffraction and was solved by the direct methods and Fourier difference techniques. The structure (space group P21/c, a = 11.184(4) Å, b = 9.489(4) Å, c = 10.234(4) Å, β = 114.308(8)°, Z = 2) consists of layers formed by six-membered rings of actinide metals connected through oxalate ions. The americium atoms are nine-coordinated by six oxygen atoms from three bidentate oxalate ligands and three water molecules. The distances within the coordination sphere as well as infrared and Raman spectra of several isostructural lanthanide (Ce(III), Pr(III), Nd(III), Sm(III), Gd(III)) and actinide (Pu(III), Am(III)) oxalates were compared to evaluate the similarities and the differences between the two series. PMID:26675037

  11. Complexation Studies of Bidentate Heterocyclic N-Donor Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark; Hoch, Courtney L.; Sinkov, Sergey I.; Meier, Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2011-11-28

    A new bidentate nitrogen donor complexing agent that combines pyridine and triazole functional groups, 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (PTMP), has been synthesized. The strength of its complexes with trivalent americium (Am3+) and neodymium (Nd3+) in anhydrous methanol has been evaluated using spectrophotometric techniques. The purpose of this investigation is to assess this ligand (as representative of a class of similarly structured species) as a possible model compound for the challenging separation of trivalent actinides from lanthanides. This separation, important in the development of advanced nuclear fuel cycles, is best achieved through the agency of multidentate chelating agents containing some number of nitrogen or sulfur donor groups. To evaluate the relative strength of the bidentate complexes, the derived constants are compared to those of the same metal ions with 2,2*-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2-pyridin-2-yl-1H-benzimidazole (PBIm). At issue is the relative affinity of the triazole moiety for trivalent f element ions. For all ligands, the derived stability constants are higher for Am3+ than Nd3+. In the case of Am3+ complexes with phen and PBIm, the presence of 1:2 (AmL2) species is indicated. Possible separations are suggested based on the relative stability and stoichiometry of the Am3+ and Nd3+ complexes. It can be noted that the 1,2,3-triazolyl group imparts a potentially useful selectivity for trivalent actinides (An(III)) over trivalent lanthanides (Ln(III)), though the attainment of higher complex stoichiometries in actinide compared with lanthanide complexes may be an important driver for developing successful separations.

  12. On State Complexes and Special Cube Complexes

    ERIC Educational Resources Information Center

    Peterson, Valerie J.

    2009-01-01

    This thesis presents the first steps toward a classification of non-positively curved cube complexes called state complexes. A "state complex" is a configuration space for a "reconfigurable system," i.e., an abstract system in which local movements occur in some discrete manner. Reconfigurable systems can be used to describe, for example,…

  13. Lattice vibrational properties of americium selenide

    NASA Astrophysics Data System (ADS)

    Arya, B. S.; Aynyas, Mahendra; Sanyal, S. P.

    2016-05-01

    Lattice vibrational properties of AmSe have been studied by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, specific heat calculated from present model. The calculated phonon dispersion curves of AmSe are presented follow the same trend as observed in uranium selenide. We discuss the significance of this approach in predicting the phonon dispersion curves of these compounds and examine the role of electron-phonon interaction.

  14. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  15. Delocalization and new phase in Americium: theory

    SciTech Connect

    Soderlind, P

    1999-04-23

    Density-functional electronic structure calculations have been used to investigate the high pressure behavior of Am. At about 80 kbar (8 GPa) calculations reveal a monoclinic phase similar to the ground state structure of plutonium ({alpha}-Pu). The experimentally suggested {alpha}-U structure is found to be substantially higher in energy. The phase transition from fcc to the low symmetry structure is shown to originate from a drastic change in the nature of the electronic structure induced by the elevated pressure. A calculated volume collapse of about 25% is associated with the transition. For the low density phase, an orbital polarization correction to the local spin density (LSD) theory was applied. Gradient terms of the electron density were included in the calculation of the exchange/correlation energy and potential, according to the generalized gradient approximation (GGA). The results are consistent with a Mott transition; the 5f electrons are delocalized and bonding on the high density side of the transition and chemically inert and non-bonding (localized) on the other. Theory compares rather well with recent experimental data which implies that electron correlation effects are reasonably modeled in our orbital polarization scheme.

  16. Analysis procedure for americium in environmental samples

    SciTech Connect

    Holloway, R.W.; Hayes, D.W.

    1982-01-01

    Several methods for the analysis of /sup 241/Am in environmental samples were evaluated and a preferred method was selected. This method was modified and used to determine the /sup 241/Am content in sediments, biota, and water. The advantages and limitations of the method are discussed. The method is also suitable for /sup 244/Cm analysis.

  17. Cyanobacterial NADPH dehydrogenase complexes

    SciTech Connect

    Ogawa, Teruo; Mi, Hualing

    2007-07-01

    Cyanobacteria possess functionally distinct multiple NADPH dehydrogenase (NDH-1) complexes that are essential to CO2 uptake, photosystem-1 cyclic electron transport and respiration. The unique nature of cyanobacterial NDH-1 complexes is the presence of subunits involved in CO2 uptake. Other than CO2 uptake, chloroplastic NDH-1 complex has similar role as cyanobacterial NDH-1 complexes in photosystem-1 cyclic electron transport and respiration (chlororespiration). In this mini-review we focus on the structure and function of cyanobacterial NDH-1 complexes and their phylogeny. The function of chloroplastic NDH-1 complex and characteristics of plants defective in NDH-1 are also described forcomparison.

  18. Doxorubicin Lipid Complex Injection

    MedlinePlus

    Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma ( ...

  19. Daunorubicin Lipid Complex Injection

    MedlinePlus

    Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to ... body) related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called ...

  20. Vincristine Lipid Complex Injection

    MedlinePlus

    Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer ... least two different treatments with other medications. Vincristine lipid complex is in a class of medications called ...

  1. Daunorubicin Lipid Complex Injection

    MedlinePlus

    Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to grow on ... related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called anthracyclines. ...

  2. Cytarabine Lipid Complex Injection

    MedlinePlus

    Cytarabine lipid complex is used to treat lymphomatous meningitis (a type of cancer in the covering of the spinal cord and brain). Cytarabine lipid complex is in a class of medications called antimetabolites. ...

  3. Irinotecan Lipid Complex Injection

    MedlinePlus

    Irinotecan lipid complex is used in combination with other medications to treat pancreatic cancer that has spread to other parts of ... after treatment with other chemotherapy medications. Irinotecan lipid complex is in a class of antineoplastic medications called ...

  4. Complex regional pain syndrome

    MedlinePlus

    Complex regional pain syndrome (CRPS) is a chronic pain condition that can affect any area of the ... Bailey A, Audette JF. Complex regional pain syndrome. In: Frontera ... of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, ...

  5. Doxorubicin Lipid Complex Injection

    MedlinePlus

    Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma (a ...

  6. Vincristine Lipid Complex Injection

    MedlinePlus

    Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer of the ... two different treatments with other medications. Vincristine lipid complex is in a class of medications called vinca ...

  7. Irinotecan Lipid Complex Injection

    MedlinePlus

    Irinotecan lipid complex is used in combination with other medications to treat pancreatic cancer that has spread ... has worsened after treatment with other chemotherapy medications. Irinotecan lipid complex is in a class of antineoplastic ...

  8. Oligocyclopentadienyl transition metal complexes

    SciTech Connect

    de Azevedo, Cristina G.; Vollhardt, K. Peter C.

    2002-01-18

    Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

  9. Complex-I-ty in aging

    PubMed Central

    Stork, Devon A.

    2016-01-01

    The role of mitochondrial complex I in aging has been studied in both C. elegans and Drosophila, where RNAi knock down of specific complex I subunits has been shown to extend lifespan. More recently, studies in Drosophila have shown that an increase in mitochondrial activity, including complex I-like activity, can also slow aging. In this review, we discuss this apparent paradox. Improved maintenance of mitochondrial activity, mitochondrial homeostasis, may be responsible for lifespan extension in both cases. Decreased electron transport chain activity caused by reducing complex I subunit expression prompts an increase in stress response signaling that leads to enhanced mitochondrial homeostasis during aging. Increased complex I activity, as well as mitochondrial biogenesis, is expected to both directly counteract the decline in mitochondrial health that occurs during aging and may also increase cellular NAD+ levels, which have been linked to mitochondrial homeostatic mechanisms through activation of sirtuins. We suggest that manipulations that increase or decrease complex I activity both converge on improved mitochondrial homeostasis during aging, resulting in prolonged lifespan. PMID:24961226

  10. Management of Heavy Isotope in the DOE Complex

    SciTech Connect

    Canon, R.; Croff, A.; Boyd, L.

    2002-02-27

    cost to the user of obtaining newly produced material. The HIMG has also prepared issue papers on neptunium and americium/curium that identify the resources, potential uses, and disposal pathways for the materials across the DOE Complex. In the future the HIMG expects to comprehensively identify the status of the U.S. heavy isotope inventory, prepare additional issue papers and plans charting the future of this inventory, and to facilitate execution of the plan.

  11. Palladium (II) Hydrazopyrazolone Complexes

    NASA Astrophysics Data System (ADS)

    El-Maraghy, Salah B.; Salib, K. A.; Stefan, Shaker L.

    1989-12-01

    Palladium (II) complexes with 1-pheny1-3-methy1-4-(arylhydrazo)-5- pyrazolone dyes were studied spectrophotometrically. Pd (II) forms 1:1 and 1:2 complexes with the ligands by the replacement of their phenolic and hydrazo protons. The ligands behave as tridentate in the 1:1 complex and as bidentate in the 1:2 complex. The sability constants of these complexes are dependent on the type of substituents in the benzene ring of the arylazo moiety.

  12. Heuristic dynamic complexity coding

    NASA Astrophysics Data System (ADS)

    Škorupa, Jozef; Slowack, Jürgen; Mys, Stefaan; Lambert, Peter; Van de Walle, Rik

    2008-04-01

    Distributed video coding is a new video coding paradigm that shifts the computational intensive motion estimation from encoder to decoder. This results in a lightweight encoder and a complex decoder, as opposed to the predictive video coding scheme (e.g., MPEG-X and H.26X) with a complex encoder and a lightweight decoder. Both schemas, however, do not have the ability to adapt to varying complexity constraints imposed by encoder and decoder, which is an essential ability for applications targeting a wide range of devices with different complexity constraints or applications with temporary variable complexity constraints. Moreover, the effect of complexity adaptation on the overall compression performance is of great importance and has not yet been investigated. To address this need, we have developed a video coding system with the possibility to adapt itself to complexity constraints by dynamically sharing the motion estimation computations between both components. On this system we have studied the effect of the complexity distribution on the compression performance. This paper describes how motion estimation can be shared using heuristic dynamic complexity and how distribution of complexity affects the overall compression performance of the system. The results show that the complexity can indeed be shared between encoder and decoder in an efficient way at acceptable rate-distortion performance.

  13. Assessing physiological complexity.

    PubMed

    Burggren, W W; Monticino, M G

    2005-09-01

    Physiologists both admire and fear complexity, but we have made relatively few attempts to understand it. Inherently complex systems are more difficult to study and less predictable. However, a deeper understanding of physiological systems can be achieved by modifying experimental design and analysis to account for complexity. We begin this essay with a tour of some mathematical views of complexity. After briefly exploring chaotic systems, information theory and emergent behavior, we reluctantly conclude that, while a mathematical view of complexity provides useful perspectives and some narrowly focused tools, there are too few generally practical take-home messages for physiologists studying complex systems. Consequently, we attempt to provide guidelines as to how complex systems might be best approached by physiologists. After describing complexity based on the sum of a physiological system's structures and processes, we highlight increasingly refined approaches based on the pattern of interactions between structures and processes. We then provide a series of examples illustrating how appreciating physiological complexity can improve physiological research, including choosing experimental models, guiding data collection, improving data interpretations and constructing more rigorous system models. Finally, we conclude with an invitation for physiologists, applied mathematicians and physicists to collaborate on describing, studying and learning from studies of physiological complexity. PMID:16109885

  14. Two giant stellar complexes

    NASA Astrophysics Data System (ADS)

    Efremov, Yu. N.; Efremov, E. Yu.

    Common star complexes are huge (0.3-1 kpc in diameter) groups of relatively young stars, associations and clusters. The complexes usually form regular chains along spiral arms of grand design galaxies, being evidently formed and supported by magneto- gravitational instability developing along an arm. Special attention is given to a few large complexes which have signatures of gravitational boundness, such as round shape and high central density. Concentrations of stars and clusters in such a complex in M51 galaxy were found in this paper; we concluded it is possible to suggest that the complex is gravitationally bound. It is also stressed that some properties of the giant complex in NGC 6946 (such as its semicircular and sharp Western edge) are still enigmatic.

  15. Hypergraph coloring complexes.

    PubMed

    Breuer, Felix; Dall, Aaron; Kubitzke, Martina

    2012-08-28

    The aim of this paper is to generalize the notion of the coloring complex of a graph to hypergraphs. We present three different interpretations of those complexes-a purely combinatorial one and two geometric ones. It is shown, that most of the properties, which are known to be true for coloring complexes of graphs, break down in this more general setting, e.g., Cohen-Macaulayness and partitionability. Nevertheless, we are able to provide bounds for the [Formula: see text]- and [Formula: see text]-vectors of those complexes which yield new bounds on chromatic polynomials of hypergraphs. Moreover, though it is proven that the coloring complex of a hypergraph has a wedge decomposition, we provide an example showing that in general this decomposition is not homotopy equivalent to a wedge of spheres. In addition, we can completely characterize those hypergraphs whose coloring complex is connected. PMID:23483700

  16. Artistic forms and complexity.

    PubMed

    Boon, J-P; Casti, J; Taylor, R P

    2011-04-01

    We discuss the inter-relationship between various concepts of complexity by introducing a complexity 'triangle' featuring objective complexity, subjective complexity and social complexity. Their connections are explored using visual and musical compositions of art. As examples, we quantify the complexity embedded within the paintings of the Jackson Pollock and the musical works of Johann Sebastian Bach. We discuss the challenges inherent in comparisons of the spatial patterns created by Pollock and the sonic patterns created by Bach, including the differing roles that time plays in these investigations. Our results draw attention to some common intriguing characteristics suggesting 'universality' and conjecturing that the fractal nature of art might have an intrinsic value of more general significance. PMID:21382264

  17. Complexation of Optoelectronic Systems

    NASA Astrophysics Data System (ADS)

    Boreisho, A. S.; Il‧in, M. Yu.; Konyaev, M. A.; Mikhailenko, A. S.; Morozov, A. V.; Strakhov, S. Yu.

    2016-06-01

    Problems of increasing the efficiency and the functionality of complex optoelectronic systems for monitoring real atmospheric conditions and of their use are discussed. It is shown by the example of a meteorological complex comprising an infrared wind-sensing lidar and an X-range Doppler radar that the complexation of probing systems working in different electromagnetic-radiation ranges opens up new opportunities for determining the meteorological parameters of a turbulent atmosphere and investigating the interaction of radiation with it.

  18. Complexity and schizophrenia.

    PubMed

    Fernández, Alberto; Gómez, Carlos; Hornero, Roberto; López-Ibor, Juan José

    2013-08-01

    Complexity estimators have been broadly utilized in schizophrenia investigation. Early studies reported increased complexity in schizophrenia patients, associated with a higher variability or "irregularity" of their brain signals. However, further investigations showed reduced complexities, thus introducing a clear divergence. Nowadays, both increased and reduced complexity values are reported. The explanation of such divergence is a critical issue to understand the role of complexity measures in schizophrenia research. Considering previous arguments a complementary hypothesis is advanced: if the increased irregularity of schizophrenia patients' neurophysiological activity is assumed, a "natural" tendency to increased complexity in EEG and MEG scans should be expected, probably reflecting an abnormal neuronal firing pattern in some critical regions such as the frontal lobes. This "natural" tendency to increased complexity might be modulated by the interaction of three main factors: medication effects, symptomatology, and age effects. Therefore, young, medication-naïve, and highly symptomatic (positive symptoms) patients are expected to exhibit increased complexities. More importantly, the investigation of these interacting factors by means of complexity estimators might help to elucidate some of the neuropathological processes involved in schizophrenia. PMID:22507763

  19. Performance Improvement Assuming Complexity

    ERIC Educational Resources Information Center

    Rowland, Gordon

    2007-01-01

    Individual performers, work teams, and organizations may be considered complex adaptive systems, while most current human performance technologies appear to assume simple determinism. This article explores the apparent mismatch and speculates on future efforts to enhance performance if complexity rather than simplicity is assumed. Included are…

  20. U1A Complex

    SciTech Connect

    2014-10-28

    Some of the most sophisticated experiments in the stockpile stewardship program are conducted in an environmentally safe manner, nearly 1000 feet below the ground at the site. The U1a complex a sprawling underground laboratory and tunnel complex is home to a number of unique capabilities.

  1. Complexity and Relations

    ERIC Educational Resources Information Center

    Lancaster, Jeanette Elizabeth

    2013-01-01

    A central feature of complexity is that it is based on non-linear, recursive relations. However, in most current accounts of complexity such relations, while non-linear, are based on the reductive relations of a Newtonian onto-epistemological framework. This means that the systems that are emergent from the workings of such relations are a…

  2. The Tom Core Complex

    PubMed Central

    Ahting, Uwe; Thun, Clemens; Hegerl, Reiner; Typke, Dieter; Nargang, Frank E.; Neupert, Walter; Nussberger, Stephan

    1999-01-01

    Translocation of nuclear-encoded preproteins across the outer membrane of mitochondria is mediated by the multicomponent transmembrane TOM complex. We have isolated the TOM core complex of Neurospora crassa by removing the receptors Tom70 and Tom20 from the isolated TOM holo complex by treatment with the detergent dodecyl maltoside. It consists of Tom40, Tom22, and the small Tom components, Tom6 and Tom7. This core complex was also purified directly from mitochondria after solubilization with dodecyl maltoside. The TOM core complex has the characteristics of the general insertion pore; it contains high-conductance channels and binds preprotein in a targeting sequence-dependent manner. It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles. Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of ∼2.1 nm and a height of ∼7 nm. Tom40 is the key structural element of the TOM core complex. PMID:10579717

  3. Gold trifluoromethyl complexes.

    PubMed

    Gil-Rubio, Juan; Vicente, José

    2015-12-01

    This article reviews the synthesis, reactivity and applications of gold trifluoromethyl complexes, which are the only isolated perfluoroalkyl complexes of gold. The most reported examples are neutral Au(i) complexes of the type [Au(CF3)L], whereas only two Au(ii) trifluoromethyl complexes have been reported, both being diamagnetic and containing a strong Au-Au bond. A number of Au(iii) trifluoromethyl complexes have been prepared by oxidative addition of halogens or iodotrifluoromethane to Au(i) complexes or, in a few cases, by transmetallation reactions. Owing to the limitations of the available synthetic methods, a lower number of examples is known, particularly for the oxidation states (ii) and (iii). Gold trifluoromethyl complexes present singular characteristics, such as thermal stability, strong Au-C bonds and, in some cases, reactive α-C-F bonds. Some of the Au(iii) complexes reported, show unusually easy reductive elimination reactions of trifluoromethylated products which could be applied in the development of gold-catalyzed processes for the trifluoromethylation of organic compounds. PMID:26169553

  4. Freestanding Complex Optical Scanners.

    ERIC Educational Resources Information Center

    Frisbie, David A.

    A complex freestanding optical mark recognition (OMR) scanner is one which is not on-line to an external processor; it has intelligence stemming from an internal processor located within the unit or system. The advantages and disadvantages of a complex OMR can best be assessed after identifying the scanning needs and constraints of the potential…

  5. COMPLEXITY IN ECOLOGICAL SYSTEMS

    EPA Science Inventory

    The enormous complexity of ecosystems is generally obvious under even the most cursory examination. In the modern world, this complexity is further augmented by the linkage of ecosystems to economic and social systems through the human use of the environment for technological pu...

  6. Bacterial formate hydrogenlyase complex

    PubMed Central

    McDowall, Jennifer S.; Murphy, Bonnie J.; Haumann, Michael; Palmer, Tracy; Armstrong, Fraser A.; Sargent, Frank

    2014-01-01

    Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics, maturation, and some biochemistry of FHL are understood, the protein complex has never been isolated in an intact form to allow biochemical analysis. In this work, genetic tools are reported that allow the facile isolation of FHL in a single chromatographic step. The core complex is shown to comprise HycE (a [NiFe] hydrogenase component termed Hyd-3), FdhF (the molybdenum-dependent formate dehydrogenase-H), and three iron-sulfur proteins: HycB, HycF, and HycG. A proportion of this core complex remains associated with HycC and HycD, which are polytopic integral membrane proteins believed to anchor the core complex to the cytoplasmic side of the membrane. As isolated, the FHL complex retains formate hydrogenlyase activity in vitro. Protein film electrochemistry experiments on Hyd-3 demonstrate that it has a unique ability among [NiFe] hydrogenases to catalyze production of H2 even at high partial pressures of H2. Understanding and harnessing the activity of the FHL complex is critical to advancing future biohydrogen research efforts. PMID:25157147

  7. U1A Complex

    ScienceCinema

    None

    2015-01-09

    Some of the most sophisticated experiments in the stockpile stewardship program are conducted in an environmentally safe manner, nearly 1000 feet below the ground at the site. The U1a complex a sprawling underground laboratory and tunnel complex is home to a number of unique capabilities.

  8. Visual Complexity: A Review

    ERIC Educational Resources Information Center

    Donderi, Don C.

    2006-01-01

    The idea of visual complexity, the history of its measurement, and its implications for behavior are reviewed, starting with structuralism and Gestalt psychology at the beginning of the 20th century and ending with visual complexity theory, perceptual learning theory, and neural circuit theory at the beginning of the 21st. Evidence is drawn from…

  9. Complexity in Picture Books

    ERIC Educational Resources Information Center

    Sierschynski, Jarek; Louie, Belinda; Pughe, Bronwyn

    2015-01-01

    One of the key requirements of Common Core State Standards (CCSS) in English Language Arts is that students are able to read and access complex texts across all grade levels. The CCSS authors emphasize both the limitations and lack of accuracy in the current CCSS model of text complexity, calling for the development of new frameworks. In response…

  10. Leading healthcare in complexity.

    PubMed

    Cohn, Jeffrey

    2014-12-01

    Healthcare institutions and providers are in complexity. Networks of interconnections from relationships and technology create conditions in which interdependencies and non-linear dynamics lead to surprising, unpredictable outcomes. Previous effective approaches to leadership, focusing on top-down bureaucratic methods, are no longer effective. Leading in complexity requires leaders to accept the complexity, create an adaptive space in which innovation and creativity can flourish and then integrate the successful practices that emerge into the formal organizational structure. Several methods for doing adaptive space work will be discussed. Readers will be able to contrast traditional leadership approaches with leading in complexity. They will learn new behaviours that are required of complexity leaders, along with challenges they will face, often from other leaders within the organization. PMID:25815410

  11. Nickel Hydride Complexes.

    PubMed

    Eberhardt, Nathan A; Guan, Hairong

    2016-08-10

    Nickel hydride complexes, defined herein as any molecules bearing a nickel hydrogen bond, are crucial intermediates in numerous nickel-catalyzed reactions. Some of them are also synthetic models of nickel-containing enzymes such as [NiFe]-hydrogenase. The overall objective of this review is to provide a comprehensive overview of this specific type of hydride complexes, which has been studied extensively in recent years. This review begins with the significance and a very brief history of nickel hydride complexes, followed by various methods and spectroscopic or crystallographic tools used to synthesize and characterize these complexes. Also discussed are stoichiometric reactions involving nickel hydride complexes and how some of these reactions are developed into catalytic processes. PMID:27437790

  12. [Complexity: an introduction].

    PubMed

    Gómez, Carlos Alberto Palacio; Jaramillo, Francisco Luis Ochoa

    2011-01-01

    Complexity appears in the twentieth century as a way to understand many phenomena that are perceived as chaotic and complex from classical thought, which still persist in our way of explaining the world. Its purpose is to study the complex and adaptive systems that are sensitive to initial conditions. Some of the characteristics of complex thought are systemic perspective, autopoiesis, self-organization, emergent properties, unpredictability of the systems, analogic thought, and the complementarity of the phenomena, among others. Living systems respond to a complex logic, and in that sense, our vision of human populations and patients, and how we try to solve problems and human diseases, should be open to the possibilities that arise from this form of understand the world. PMID:21503430

  13. Profil'-1 measuring complex

    SciTech Connect

    Andrianov, V.R.; Petrov, A.P.

    1985-04-01

    This paper describes the Profil'-1 hydroacoustic measuring complex. The complex provides documentary information on the bottom profile of reservoirs, the configuration and geometric dimensions of underwater trenches, the spatial position of pipes in uncovered or washedout trenches, the thickness of a layer covering underwater pipes, etc. The complex can also be used to solve other industrial problems such as hydraulic exploration and searching for sunken objects. The Profil'-1 complex is designed for use on board small craft under field conditions with periodic transportation from storage bases to the operating location and back. The complex uses an echo-pulse method for determining the distance and coordinates of objects with the aid of an ultrasonic transceiver in an aqueous medium. Structurally, the complex consists of four main units: a BA-1 vertical sounding antenna unit; a BAS-1 antenna scanning unit; a BFOS-1 signal shaping and processing unit, and a BR-1 recording unit. Use of the complex in pipeline construction and the oil and gas industry will provide a considerable economic gain by reducing the number of diver inspections of underwater pipelines.

  14. Selenophene transition metal complexes

    SciTech Connect

    White, C.J.

    1994-07-27

    This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the {eta}{sup 5}- and the {eta}{sup 1}(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The {sup 77}Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of {eta}{sup 1}(S)-bound thiophenes, {eta}{sup 1}(S)-benzothiophene and {eta}{sup 1}(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the {eta}{sup 1}(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh{sub 3})Re(2-benzothioenylcarbene)]O{sub 3}SCF{sub 3} was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the {eta}{sup 1}(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

  15. Afterglow Complex Plasma

    SciTech Connect

    Samarian, A. A.; Boufendi, L.; Mikikian, M.

    2008-09-07

    The review of the first detailed experimental and theoretical studies of complex plasma in RF discharge afterglow is presented. The studies have been done in a frame of FAST collaborative research project between Complex Plasma Laboratory of the University of Sydney and the GREMI laboratory of Universite d'Orleans. We examined the existing models of plasma decay, presents experimental observations of dust dynamics under different afterglow complex plasma conditions, presents the experimental data obtained (in particular the presence of positively charged particles in discharge afterglow), discusses the use of dust particles as a probe to study the diffusion losses in afterglow plasmas.

  16. Complexity and robustness

    PubMed Central

    Carlson, J. M.; Doyle, John

    2002-01-01

    Highly optimized tolerance (HOT) was recently introduced as a conceptual framework to study fundamental aspects of complexity. HOT is motivated primarily by systems from biology and engineering and emphasizes, (i) highly structured, nongeneric, self-dissimilar internal configurations, and (ii) robust yet fragile external behavior. HOT claims these are the most important features of complexity and not accidents of evolution or artifices of engineering design but are inevitably intertwined and mutually reinforcing. In the spirit of this collection, our paper contrasts HOT with alternative perspectives on complexity, drawing on real-world examples and also model systems, particularly those from self-organized criticality. PMID:11875207

  17. Controllability of Complex Systems

    NASA Astrophysics Data System (ADS)

    Slotine, Jean-Jacques

    2013-03-01

    We review recent work on controllability of complex systems. We also discuss the interplay of our results with questions of synchronization, and point out key directions of future research. Work done in collaboration with Yang-Yu Liu, Center for Complex Network Research and Departments of Physics, Computer Science and Biology, Northeastern University and Center for Cancer Systems Biology, Dana-Farber Cancer Institute; and Albert-László Barabási, Center for Complex Network Research and Departments of Physics, Computer Science and Biology, Northeastern University; Center for Cancer Systems Biology, Dana-Farber Cancer Institute; and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School.

  18. Complexity and forensic pathology.

    PubMed

    Jones, Richard Martin

    2015-12-01

    It has become increasingly apparent that nonlinearity and complexity are the norm in human physiological systems, the relevance of which is informing an enhanced understanding of basic pathological processes such as inflammation, the host response to severe trauma, and critical illness. This article will explore how an understanding of nonlinear systems and complexity might inform the study of the pathophysiology of deaths of medicolegal interest, and how 'complexity thinking' might usefully be incorporated into modern forensic medicine and forensic pathology research, education and practice. PMID:26372537

  19. Complex intuitionistic fuzzy sets

    NASA Astrophysics Data System (ADS)

    Alkouri, Abdulazeez (Moh'd. Jumah) S.; Salleh, Abdul Razak

    2012-09-01

    This paper presents a new concept of complex intuitionistic fuzzy set (CIFS) which is generalized from the innovative concept of a complex fuzzy set (CFS) by adding the non-membership term to the definition of CFS. The novelty of CIFS lies in its ability for membership and non-membership functions to achieve more range of values. The ranges of values are extended to the unit circle in complex plane for both membership and non-membership functions instead of [0, 1] as in the conventional intuitionistic fuzzy functions. We define basic operations namely complement, union, and intersection on CIFSs. Properties of these operations are derived.

  20. Complex equiangular tight frames

    NASA Astrophysics Data System (ADS)

    Tropp, Joel A.

    2005-08-01

    A complex equiangular tight frame (ETF) is a tight frame consisting of N unit vectors in Cd whose absolute inner products are identical. One may view complex ETFs as a natural geometric generalization of an orthonormal basis. Numerical evidence suggests that these objects do not arise for most pairs (d, N). The goal of this paper is to develop conditions on (d, N) under which complex ETFs can exist. In particular, this work concentrates on the class of harmonic ETFs, in which the components of the frame vectors are roots of unity. In this case, it is possible to leverage field theory to obtain stringent restrictions on the possible values for (d, N).

  1. A complex legacy

    NASA Astrophysics Data System (ADS)

    Moore, Cristopher

    2011-11-01

    In his tragically short life, Alan Turing helped define what computing machines are capable of, and where they reach inherent limits. His legacy is still felt every day, in areas ranging from computational complexity theory to cryptography and quantum computing.

  2. Specialist complex care.

    PubMed

    Oliver, Susan

    2016-08-01

    I agree with your editorial on how NHS England and the Department of Health (DH) have failed to realise that specialist care for complex diseases requires experienced and knowledgeable support. PMID:27484551

  3. Complexity at mesoscopic lengthscale.

    PubMed

    Egami, T

    2015-09-01

    Modern materials are often complex in the structure at mesoscale. The method of pair-density function (PDF) is a powerful tool to characterize mesoscopic structure, bridging short- and long-range structures. PMID:26306189

  4. Pigment-protein complexes

    SciTech Connect

    Siegelman, H W

    1980-01-01

    The photosynthetically-active pigment protein complexes of procaryotes and eucaryotes include chlorophyll proteins, carotenochlorophyll proteins, and biliproteins. They are either integral components or attached to photosynthetic membranes. Detergents are frequently required to solubilize the pigment-protein complexes. The membrane localization and detergent solubilization strongly suggest that the pigment-protein complexes are bound to the membranes by hydrophobic interactions. Hydrophobic interactions of proteins are characterized by an increase in entropy. Their bonding energy is directly related to temperature and ionic strength. Hydrophobic-interaction chromatography, a relatively new separation procedure, can furnish an important method for the purification of pigment-protein complexes. Phycobilisome purification and properties provide an example of the need to maintain hydrophobic interactions to preserve structure and function.

  5. Complex Flow Workshop Report

    SciTech Connect

    none,

    2012-05-01

    This report documents findings from a workshop on the impacts of complex wind flows in and out of wind turbine environments, the research needs, and the challenges of meteorological and engineering modeling at regional, wind plant, and wind turbine scales.

  6. Complex Regional Pain Syndrome

    MedlinePlus

    Complex regional pain syndrome (CRPS) is a chronic pain condition. It causes intense pain, usually in the arms, hands, legs, or feet. ... in skin temperature, color, or texture Intense burning pain Extreme skin sensitivity Swelling and stiffness in affected ...

  7. Complex coacervate core micelles.

    PubMed

    Voets, Ilja K; de Keizer, Arie; Cohen Stuart, Martien A

    2009-01-01

    In this review we present an overview of the literature on the co-assembly of neutral-ionic block, graft, and random copolymers with oppositely charged species in aqueous solution. Oppositely charged species include synthetic (co)polymers of various architectures, biopolymers - such as proteins, enzymes and DNA - multivalent ions, metallic nanoparticles, low molecular weight surfactants, polyelectrolyte block copolymer micelles, metallo-supramolecular polymers, equilibrium polymers, etcetera. The resultant structures are termed complex coacervate core/polyion complex/block ionomer complex/interpolyelectrolyte complex micelles (or vesicles); i.e., in short C3Ms (or C3Vs) and PIC, BIC or IPEC micelles (and vesicles). Formation, structure, dynamics, properties, and function will be discussed. We focus on experimental work; theory and modelling will not be discussed. Recent developments in applications and micelles with heterogeneous coronas are emphasized. PMID:19038373

  8. Reconstruction Using Witness Complexes

    PubMed Central

    Oudot, Steve Y.

    2010-01-01

    We present a novel reconstruction algorithm that, given an input point set sampled from an object S, builds a one-parameter family of complexes that approximate S at different scales. At a high level, our method is very similar in spirit to Chew’s surface meshing algorithm, with one notable difference though: the restricted Delaunay triangulation is replaced by the witness complex, which makes our algorithm applicable in any metric space. To prove its correctness on curves and surfaces, we highlight the relationship between the witness complex and the restricted Delaunay triangulation in 2d and in 3d. Specifically, we prove that both complexes are equal in 2d and closely related in 3d, under some mild sampling assumptions. PMID:21643440

  9. Reconstruction Using Witness Complexes.

    PubMed

    Guibas, Leonidas J; Oudot, Steve Y

    2008-10-01

    We present a novel reconstruction algorithm that, given an input point set sampled from an object S, builds a one-parameter family of complexes that approximate S at different scales. At a high level, our method is very similar in spirit to Chew's surface meshing algorithm, with one notable difference though: the restricted Delaunay triangulation is replaced by the witness complex, which makes our algorithm applicable in any metric space. To prove its correctness on curves and surfaces, we highlight the relationship between the witness complex and the restricted Delaunay triangulation in 2d and in 3d. Specifically, we prove that both complexes are equal in 2d and closely related in 3d, under some mild sampling assumptions. PMID:21643440

  10. Cytarabine Lipid Complex Injection

    MedlinePlus

    Cytarabine lipid complex is used to treat lymphomatous meningitis (a type of cancer in the covering of ... to take.tell your doctor if you have meningitis. Your doctor will probably not want you to ...

  11. Inside the complexity labyrinth

    NASA Astrophysics Data System (ADS)

    Fraser, Gordon

    2010-02-01

    Although the world we live in is complex, complexity as a science does not have a long history. For generations, most physicists tried to understand everything in terms of interactions between pairs of idealized "test particles". Then, about a 100 years ago, Henri Poincaré pointed out that a fully interacting three-body system was not just the sum of its three component pairs. The famous "three-body problem" was born.

  12. Complex/Symplectic Mirrors

    SciTech Connect

    Chuang, Wu-yen; Kachru, Shamit; Tomasiello, Alessandro; /Stanford U., ITP

    2005-10-28

    We construct a class of symplectic non-Kaehler and complex non-Kaehler string theory vacua, extending and providing evidence for an earlier suggestion by Polchinski and Strominger. The class admits a mirror pairing by construction. Comparing hints from a variety of sources, including ten-dimensional supergravity and KK reduction on SU(3)-structure manifolds, suggests a picture in which string theory extends Reid's fantasy to connect classes of both complex non-Kaehler and symplectic non-Kaehler manifolds.

  13. Interglacial complex and solcomplex

    NASA Astrophysics Data System (ADS)

    Schirmer, Wolfgang

    2010-03-01

    All younger Pleistocene interglacials form interglacial complexes. The term interglacial complex is a short term for a tight complex of interglacials, interstadials and breviglacials, separating a complex of warm periods from the long glacial periods (euglacials). In the terrestric environment the interglacial complexes are represented by soil clusters (solcomplexes). Therein which occur interglacial and interstadial soils of different types in the loess environment separated by thin beds of loess or loess derivates (breviglacials). This article considers the mutilation and simulation of solcomplexes. Frequently, fossil solcomplexes present themselves as diminished to a few soils or to one single soil. This mutilation of solcomplexes can be due to soil convergence (soils of different warm periods — interglacials, interstadials — merge to form optically one soil), syn-solcomplex erosion or post-solcomplex erosion and sometimes to soil disguise. Conversely solcomplexes may be simulated by narrowing of soils which belong to different interglacial complexes and moreover by soil divergence (splitting of a soil of one single warm period by an interlayer of rock) or by reworked soil sediment.

  14. Synchronization in complex dynamical networks coupled with complex chaotic system

    NASA Astrophysics Data System (ADS)

    Wei, Qiang; Xie, Cheng-Jun; Wang, Bo

    2015-11-01

    This paper investigates synchronization in complex dynamical networks with time delay and perturbation. The node of complex dynamical networks is composed of complex chaotic system. A complex feedback controller is designed to realize different component of complex state variable synchronize up to different scaling complex function when complex dynamical networks realize synchronization. The synchronization scaling function is changed from real field to complex field. Synchronization in complex dynamical networks with constant delay and time-varying coupling delay are investigated, respectively. Numerical simulations show the effectiveness of the proposed method.

  15. Cell complexes through time

    NASA Astrophysics Data System (ADS)

    Klette, Reinhard

    2000-10-01

    The history of cell complexes is closely related to the birth and development of topology in general. Johann Benedict Listing (1802 - 1882) introduced the term 'topology' into mathematics in a paper published in 1847, and he also defined cell complexes for the first time in a paper published in 1862. Carl Friedrich Gauss (1777 - 1855) is often cited as the one who initiated these ideas, but he did not publish either on topology or on cell complexes. The pioneering work of Leonhard Euler (1707 - 1783) on graphs is also often cited as the birth of topology, and Euler's work was cited by Listing in 1862 as a stimulus for his research on cell complexes. There are different branches in topology which have little in common: point set topology, algebraic topology, differential topology etc. Confusion may arise if just 'topology' is specified, without clarifying the used concept. Topological subjects in mathematics are often related to continuous models, and therefore quite irrelevant to computer based solutions in image analysis. Compared to this, only a minority of topology publications in mathematics addresses discrete spaces which are appropriate for computer-based image analysis. In these cases, often the notion of a cell complex plays a crucial role. This paper briefly reports on a few of these publications. This paper is not intended to cover the very lively progress in cell complex studies within the context of image analysis during the last two decades. Basically it stops its historic review at the time when this subject in image analysis research gained speed in 1980 - 1990. As a general point of view, the paper indicates that image analysis contributes to a fusion of topological concepts, the geometric and the abstract cell structure approach and point set topology, which may lead towards new problems for the study of topologies defined on geometric or abstract cell complexes.

  16. Complexes and imagination.

    PubMed

    Kast, Verena

    2014-11-01

    Fantasies as imaginative activities are seen by Jung as expressions of psychic energy. In the various descriptions of active imagination the observation of the inner image and the dialogue with inner figures, if possible, are important. The model of symbol formation, as Jung describes it, can be experienced in doing active imagination. There is a correspondence between Jung's understanding of complexes and our imaginations: complexes develop a fantasy life. Complex episodes are narratives of difficult dysfunctional relationship episodes that have occurred repeatedly and are internalized with episodic memory. This means that the whole complex episode (the image for the child and the image for the aggressor, connected with emotions) is internalized and can get constellated in everyday relationship. Therefore inner dialogues do not necessarily qualify as active imaginations, often they are the expression of complex-episodes, very similar to fruitless soliloquies. If imaginations of this kind are repeated, new symbols and new possibilities of behaviour are not found. On the contrary, old patterns of behaviour and fantasies are perpetuated and become cemented. Imaginations of this kind need an intervention by the analyst. In clinical examples different kinds of imaginations are discussed. PMID:25331506

  17. Hydridomethyl iridium complex

    DOEpatents

    Bergman, Robert G.; Buchanan, J. Michael; Stryker, Jeffrey M.; Wax, Michael J.

    1989-01-01

    A process for functionalizing methane comprising: (a) reacting methane with a hydridoalkyl metal complex of the formula: CpIr[P(R.sub.1).sub.3 ]H(R.sub.2) wherein Cp represents a cyclopentadienyl or alkylcyclopentadienyl radical having from 1 to 5 carbon atoms; Ir represents an iridium atom; P represents a phosphorus atom; R.sub.1 represents an alkyl group; R.sub.2 represents an alkyl group having at least two carbon atoms; and H represents a hydrogen atom, in the presence of a liquid alkane R.sub.3 H having at least three carbon atoms to form a hydridomethyl complex of the formula: CpIr[P(R.sub.1).sub.3 ]HMe where Me represents a methyl radical. (b) reacting said hydridomethyl complex with an organic halogenating agent such as a tetrahalomethane or a haloform of the formulas: CX'X"X'"X"" or CHX'X"X'"; wherein X', X", X"', and X"" represent halogens selected from bromine, iodine and chlorine, to halomethyl complex of step (a) having the formula: CpIr[P(R.sub.1).sub.3 ]MeX: (c) reacting said halomethyl complex with a mercuric halide of the formula HgX.sub.2 to form a methyl mercuric halide of the formula HgMeX; and (d) reacting said methyl mercuric halide with a molecular halogen of the formula X.sub.2 to form methyl halide.

  18. Controllability of Complex Networks

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Slotine, Jean-Jacques; Barabasi, Albert-Laszlo

    2011-03-01

    The ultimate proof of our understanding of natural or technological systems is reflected in our ability to control them. While control theory offers mathematical tools to steer engineered systems towards a desired state, we lack a general framework to control complex self-organized systems, like the regulatory network of a cell or the Internet. Here we develop analytical tools to study the controllability of an arbitrary complex directed network, identifying the set of driver nodes whose time-dependent control can guide the system's dynamics. We apply these tools to real and model networks, finding that sparse inhomogeneous networks, which emerge in many real complex systems, are the most difficult to control. In contrast, dense and homogeneous networks can be controlled via a few driver nodes. Counterintuitively, we find that in both model and real systems the driver nodes tend to avoid the hubs. We show that the robustness of control to link failure is determined by a core percolation problem, helping us understand why many complex systems are relatively insensitive to link deletion. The developed approach offers a framework to address the controllability of an arbitrary network, representing a key step towards the eventual control of complex systems.

  19. Quantum Complexity in Graphene

    NASA Astrophysics Data System (ADS)

    Baskaran, G.

    Carbon has a unique position among elements in the periodic table. It produces an allotrope, graphene, a mechanically robust two dimensional semimetal. The multifarious properties that graphene exhibits has few parallels among elemental metals. From simplicity, namely carbon atoms connected by pure sp2 bonds, a wealth of novel quantum properties emerge. In classical complex systems such as a spin glass or a finance market, several competing agents or elements are responsible for unanticipated and difficult to predict emergent properties. The complex (sic) structure of quantum mechanics is responsbile for an unanticipated set of emergent properties in graphene. We call this quantum complexity. In fact, most quantum systems, phenomena and modern quantum field theory could be viewed as examples of quantum complexity. After giving a brief introduction to the quantum complexity we focus on our own work, which indicates the breadth in the type of quantum phenomena that graphene could support. We review our theoretical suggestions of, (i) spin-1 collective mode in netural graphene, (ii) relativistic type of phenomena in crossed electric and magnetic fields, (iii) room temperature superconductivity in doped graphene and (iv) composite Fermi sea in neutral graphene in uniform magnetic field and (v) two-channel Kondo effect. Except for the relativistic type of phenomena, the rest depend in a fundamental way on a weak electron correlation that exists in the broad two-dimensional band of graphene.

  20. Nonergodic complexity management

    NASA Astrophysics Data System (ADS)

    Piccinini, Nicola; Lambert, David; West, Bruce J.; Bologna, Mauro; Grigolini, Paolo

    2016-06-01

    Linear response theory, the backbone of nonequilibrium statistical physics, has recently been extended to explain how and why nonergodic renewal processes are insensitive to simple perturbations, such as in habituation. It was established that a permanent correlation results between an external stimulus and the response of a complex system generating nonergodic renewal processes, when the stimulus is a similar nonergodic process. This is the principle of complexity management, whose proof relies on ensemble distribution functions. Herein we extend the proof to the nonergodic case using time averages and a single time series, hence making it usable in real life situations where ensemble averages cannot be performed because of the very nature of the complex systems being studied.

  1. Synchronization in complex networks

    SciTech Connect

    Arenas, A.; Diaz-Guilera, A.; Moreno, Y.; Zhou, C.; Kurths, J.

    2007-12-12

    Synchronization processes in populations of locally interacting elements are in the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understand synchronization phenomena in natural systems take now advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also overview the new emergent features coming out from the interplay between the structure and the function of the underlying pattern of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.

  2. Viral quasispecies complexity measures.

    PubMed

    Gregori, Josep; Perales, Celia; Rodriguez-Frias, Francisco; Esteban, Juan I; Quer, Josep; Domingo, Esteban

    2016-06-01

    Mutant spectrum dynamics (changes in the related mutants that compose viral populations) has a decisive impact on virus behavior. The several platforms of next generation sequencing (NGS) to study viral quasispecies offer a magnifying glass to study viral quasispecies complexity. Several parameters are available to quantify the complexity of mutant spectra, but they have limitations. Here we critically evaluate the information provided by several population diversity indices, and we propose the introduction of some new ones used in ecology. In particular we make a distinction between incidence, abundance and function measures of viral quasispecies composition. We suggest a multidimensional approach (complementary information contributed by adequately chosen indices), propose some guidelines, and illustrate the use of indices with a simple example. We apply the indices to three clinical samples of hepatitis C virus that display different population heterogeneity. Areas of virus biology in which population complexity plays a role are discussed. PMID:27060566

  3. Synchronization in complex networks

    NASA Astrophysics Data System (ADS)

    Arenas, Alex; Díaz-Guilera, Albert; Kurths, Jurgen; Moreno, Yamir; Zhou, Changsong

    2008-12-01

    Synchronization processes in populations of locally interacting elements are the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understanding synchronization phenomena in natural systems now take advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also take an overview of the new emergent features coming out from the interplay between the structure and the function of the underlying patterns of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.

  4. Planning Complex Projects Automatically

    NASA Technical Reports Server (NTRS)

    Henke, Andrea L.; Stottler, Richard H.; Maher, Timothy P.

    1995-01-01

    Automated Manifest Planner (AMP) computer program applies combination of artificial-intelligence techniques to assist both expert and novice planners, reducing planning time by orders of magnitude. Gives planners flexibility to modify plans and constraints easily, without need for programming expertise. Developed specifically for planning space shuttle missions 5 to 10 years ahead, with modifications, applicable in general to planning other complex projects requiring scheduling of activities depending on other activities and/or timely allocation of resources. Adaptable to variety of complex scheduling problems in manufacturing, transportation, business, architecture, and construction.

  5. Complexity and Fly Swarms

    NASA Astrophysics Data System (ADS)

    Cates, Grant; Murray, Joelle

    Complexity is the study of phenomena that emerge from a collection of interacting objects and arises in many systems throughout physics, biology, finance, economics and more. Certain kinds of complex systems can be described by self-organized criticality (SOC). An SOC system is one that is internally driven towards some critical state. Recent experimental work suggests scaling behavior of fly swarms-one of the hallmarks of an SOC system. Our goal is to look for SOC behavior in computational models of fly swarms.

  6. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Corneillie, Todd M; Xu, Jide

    2014-05-20

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  7. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N.; Corneillie, Todd M.; Xu, Jide

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  8. Complex matrix model duality

    SciTech Connect

    Brown, T. W.

    2011-04-15

    The same complex matrix model calculates both tachyon scattering for the c=1 noncritical string at the self-dual radius and certain correlation functions of operators which preserve half the supersymmetry in N=4 super-Yang-Mills theory. It is dual to another complex matrix model where the couplings of the first model are encoded in the Kontsevich-like variables of the second. The duality between the theories is mirrored by the duality of their Feynman diagrams. Analogously to the Hermitian Kontsevich-Penner model, the correlation functions of the second model can be written as sums over discrete points in subspaces of the moduli space of punctured Riemann surfaces.

  9. Salen complexes with dianionic counterions

    DOEpatents

    Job, Gabriel E.; Farmer, Jay J.; Cherian, Anna E.

    2016-08-02

    The present invention describes metal salen complexes having dianionic counterions. Such complexes can be readily precipitated and provide an economical method for the purification and isolation of the complexes, and are useful to prepare novel polymer compositions.

  10. Six Questions on Complex Systems

    NASA Astrophysics Data System (ADS)

    Symons, John F.; Sanayei, Ali

    2011-09-01

    This paper includes an interview with John F. Symons regarding some important questions in "complex systems" and "complexity". In addition, he has stated some important open problems concerning complex systems in his research area from a philosophical point of view.

  11. Coordination Complexes of Cobalt.

    ERIC Educational Resources Information Center

    Williams, Gregory M.; And Others

    1989-01-01

    Described is an experiment involving the synthesis and spectral studies of cobalt complexes that not only give general chemistry students an introduction to inorganic synthesis but allows them to conduct a systematic study on the effect of different ligands on absorption spectra. Background information, procedures, and experimental results are…

  12. Complex carbohydrates (image)

    MedlinePlus

    ... foods such as peas, beans, whole grains, and vegetables. Both simple and complex carbohydrates are turned to glucose (blood sugar) in the body and are used as energy. Glucose is used in the cells of the body and in the brain. Any ...

  13. Nature, computation and complexity

    NASA Astrophysics Data System (ADS)

    Binder, P.-M.; Ellis, G. F. R.

    2016-06-01

    The issue of whether the unfolding of events in the world can be considered a computation is explored in this paper. We come to different conclusions for inert and for living systems (‘no’ and ‘qualified yes’, respectively). We suggest that physical computation as we know it exists only as a tool of complex biological systems: us.

  14. Launching Complex Tasks

    ERIC Educational Resources Information Center

    Jackson, Kara J.; Shahan, Emily C.; Gibbons, Lynsey K.; Cobb, Paul A.

    2012-01-01

    Mathematics lessons can take a variety of formats. In this article, the authors discuss lessons organized around complex mathematical tasks. These lessons usually unfold in three phases. First, the task is introduced to students. Second, students work on solving the task. Third, the teacher "orchestrates" a concluding whole-class discussion in…

  15. Complex Characters Made Simple

    ERIC Educational Resources Information Center

    Kettle, Sidney F. A.

    2009-01-01

    The physical significance of complex characters is explored with particular reference to the C[subscript 4] point group. While a diagrammatic representation of these characters in this group is possible, the extension to higher groups C[subscript n], n greater than 4 is left as a problem for discussion. (Contains 3 tables, 8 figures, and 1 note.)

  16. Dynamic and topological complexity

    NASA Astrophysics Data System (ADS)

    Turalska, Malgorzata; Geneston, Elvis; Grigolini, Paolo

    2010-03-01

    Cooperative phenomena in complex networks are expected to display unusual characteristics, associated with the peculiar topology of these systems. In this context we study networks of interacting stochastic two-state units as a model of cooperative decision making. Each unit in isolation generates a Poisson process with rate g. We show that when the cooperation is introduced, the decision-making process becomes intermittent. The decision-time distribution density characterized by inverse power-law behavior is defined as a dynamic complexity. Further, the onset of intermittency, expressed in terms of the coupling parameter K, is used as a measure of dynamic efficiency of investigated topologies. We find that the dynamic complexity emerges from regular and small-world topologies. In contrast, both random and scale-free networks correspond to fast transition into exponential decision-time distribution. This property is accompanied by high dynamic efficiency of the decision-making process. Our results indicate that complex dynamical processes occurring on networks could be related to relatively simple topologies.

  17. Unifying Complexity and Information

    NASA Astrophysics Data System (ADS)

    Ke, Da-Guan

    2013-04-01

    Complex systems, arising in many contexts in the computer, life, social, and physical sciences, have not shared a generally-accepted complexity measure playing a fundamental role as the Shannon entropy H in statistical mechanics. Superficially-conflicting criteria of complexity measurement, i.e. complexity-randomness (C-R) relations, have given rise to a special measure intrinsically adaptable to more than one criterion. However, deep causes of the conflict and the adaptability are not much clear. Here I trace the root of each representative or adaptable measure to its particular universal data-generating or -regenerating model (UDGM or UDRM). A representative measure for deterministic dynamical systems is found as a counterpart of the H for random process, clearly redefining the boundary of different criteria. And a specific UDRM achieving the intrinsic adaptability enables a general information measure that ultimately solves all major disputes. This work encourages a single framework coving deterministic systems, statistical mechanics and real-world living organisms.

  18. Surface complexation modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adsorption-desorption reactions are important processes that affect the transport of contaminants in the environment. Surface complexation models are chemical models that can account for the effects of variable chemical conditions, such as pH, on adsorption reactions. These models define specific ...

  19. Complex Event Recognition Architecture

    NASA Technical Reports Server (NTRS)

    Fitzgerald, William A.; Firby, R. James

    2009-01-01

    Complex Event Recognition Architecture (CERA) is the name of a computational architecture, and software that implements the architecture, for recognizing complex event patterns that may be spread across multiple streams of input data. One of the main components of CERA is an intuitive event pattern language that simplifies what would otherwise be the complex, difficult tasks of creating logical descriptions of combinations of temporal events and defining rules for combining information from different sources over time. In this language, recognition patterns are defined in simple, declarative statements that combine point events from given input streams with those from other streams, using conjunction, disjunction, and negation. Patterns can be built on one another recursively to describe very rich, temporally extended combinations of events. Thereafter, a run-time matching algorithm in CERA efficiently matches these patterns against input data and signals when patterns are recognized. CERA can be used to monitor complex systems and to signal operators or initiate corrective actions when anomalous conditions are recognized. CERA can be run as a stand-alone monitoring system, or it can be integrated into a larger system to automatically trigger responses to changing environments or problematic situations.

  20. E Complex groundbreaking

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Representatives from NASA, Orbital Sciences Corp. and Aerojet participate in a ribbon-cutting ceremony for construction of a flame deflector trench at Stennis Space Center's E Test Complex. Participants included Orbital CEO J.R. Thompson (center, left) and Stennis Space Center Director Gene Goldman (center, right).

  1. The Complexity of Care

    ERIC Educational Resources Information Center

    Collins, Steve; Ting, Hermia

    2014-01-01

    The profession of teaching is unique because of the extent to which a teacher becomes involved in the lives of their "clients". The level of care required to support students well can be intense, confusing, and overwhelming. Relationships co-evolve within an ever-changing process and care is considered an essential aspect of complex relationships…

  2. Complex Digital Visual Systems

    ERIC Educational Resources Information Center

    Sweeny, Robert W.

    2013-01-01

    This article identifies possibilities for data visualization as art educational research practice. The author presents an analysis of the relationship between works of art and digital visual culture, employing aspects of network analysis drawn from the work of Barabási, Newman, and Watts (2006) and Castells (1994). Describing complex network…

  3. Managing Complex Dynamical Systems

    ERIC Educational Resources Information Center

    Cox, John C.; Webster, Robert L.; Curry, Jeanie A.; Hammond, Kevin L.

    2011-01-01

    Management commonly engages in a variety of research designed to provide insight into the motivation and relationships of individuals, departments, organizations, etc. This paper demonstrates how the application of concepts associated with the analysis of complex systems applied to such data sets can yield enhanced insights for managerial action.

  4. Complexity in Cultural Identity

    ERIC Educational Resources Information Center

    Holliday, Adrian

    2010-01-01

    Despite their diverse national backgrounds, 28 interviewees speak similarly about the complexity of the cultural realities with which they live, and refuse to be pinned down to specific cultural types. While nation is of great importance, unless personally inspiring, it tends to be an external force which is in conflict with a wide variety of…

  5. On the use of X-ray absorption spectroscopy to elucidate the structure of lutetium adenosine mono- and triphosphate complexes.

    PubMed

    Mostapha, S; Berthon, C; Fontaine-Vive, F; Gaysinski, M; Guérin, L; Guillaumont, D; Massi, L; Monfardini, I; Solari, P L; Thomas, O P; Charbonnel, M C; Den Auwer, C

    2014-02-01

    Although the physiological impact of the actinide elements as nuclear toxicants has been widely investigated for half a century, a description of their interactions with biological molecules remains limited. It is however of primary importance to better assess the determinants of actinide speciation in cells and more generally in living organisms to unravel the molecular processes underlying actinide transport and deposition in tissues. The biological pathways of this family of elements in case of accidental contamination or chronic natural exposure (in the case of uranium rich soils for instance) are therefore a crucial issue of public health and of societal impact. Because of the high chemical affinity of those actinide elements for phosphate groups and the ubiquity of such chemical functions in biochemistry, phosphate derivatives are considered as probable targets of these cations. Among them, nucleotides and in particular adenosine mono- (AMP) and triphosphate (ATP) nucleotides occur in more chemical reactions than any other compounds on the earth's surface, except water, and are therefore critical target molecules. In the present study, we are interested in trans-plutonium actinide elements, in particular americium and curium that are more rarely considered in environmental and bioaccumulation studies than early actinides like uranium, neptunium and plutonium. A first step in this strategy is to work with chemical analogues like lanthanides that are not radioactive and therefore allow extended physical chemical characterization to be conducted that are difficult to perform with radioactive materials. We describe herein the interaction of lutetium(III) with adenosine AMP and ATP. With AMP and ATP, insoluble amorphous compounds have been obtained with molar ratios of 1:2 and 1:1, respectively. With an excess of ATP, with 1:2 molar ratio, a soluble complex has been obtained. A combination of spectroscopic techniques (IR, NMR, ESI-MS, EXAFS) together with quantum

  6. Putting Grammatical Complexity in Context

    ERIC Educational Resources Information Center

    Rimmer, Wayne

    2008-01-01

    Effective writing is to some degree characterised by the ability to use complex grammatical structures. However, grammatical complexity is poorly defined in linguistics and related disciplines such as literacy. This empirical study examined the notion of grammatical complexity and its relevance to literacy. Complexity is multifaceted, so for…

  7. Statistical Factors in Complexation Reactions.

    ERIC Educational Resources Information Center

    Chung, Chung-Sun

    1985-01-01

    Four cases which illustrate statistical factors in complexation reactions (where two of the reactants are monodentate ligands) are presented. Included are tables showing statistical factors for the reactions of: (1) square-planar complexes; (2) tetrahedral complexes; and (3) octahedral complexes. (JN)

  8. Oscillations of complex networks

    NASA Astrophysics Data System (ADS)

    Wang, Xingang; Lai, Ying-Cheng; Lai, Choy Heng

    2006-12-01

    A complex network processing information or physical flows is usually characterized by a number of macroscopic quantities such as the diameter and the betweenness centrality. An issue of significant theoretical and practical interest is how such quantities respond to sudden changes caused by attacks or disturbances in recoverable networks, i.e., functions of the affected nodes are only temporarily disabled or partially limited. By introducing a model to address this issue, we find that, for a finite-capacity network, perturbations can cause the network to oscillate persistently in the sense that the characterizing quantities vary periodically or randomly with time. We provide a theoretical estimate of the critical capacity-parameter value for the onset of the network oscillation. The finding is expected to have broad implications as it suggests that complex networks may be structurally highly dynamic.

  9. Debating complexity in modeling

    USGS Publications Warehouse

    Hunt, Randall J.; Zheng, Chunmiao

    1999-01-01

    As scientists trying to understand the natural world, how should our effort be apportioned? We know that the natural world is characterized by complex and interrelated processes. Yet do we need to explicitly incorporate these intricacies to perform the tasks we are charged with? In this era of expanding computer power and development of sophisticated preprocessors and postprocessors, are bigger machines making better models? Put another way, do we understand the natural world better now with all these advancements in our simulation ability? Today the public's patience for long-term projects producing indeterminate results is wearing thin. This increases pressure on the investigator to use the appropriate technology efficiently. On the other hand, bringing scientific results into the legal arena opens up a new dimension to the issue: to the layperson, a tool that includes more of the complexity known to exist in the real world is expected to provide the more scientifically valid answer.

  10. Compressively sensed complex networks.

    SciTech Connect

    Dunlavy, Daniel M.; Ray, Jaideep; Pinar, Ali

    2010-07-01

    The aim of this project is to develop low dimension parametric (deterministic) models of complex networks, to use compressive sensing (CS) and multiscale analysis to do so and to exploit the structure of complex networks (some are self-similar under coarsening). CS provides a new way of sampling and reconstructing networks. The approach is based on multiresolution decomposition of the adjacency matrix and its efficient sampling. It requires preprocessing of the adjacency matrix to make it 'blocky' which is the biggest (combinatorial) algorithm challenge. Current CS reconstruction algorithm makes no use of the structure of a graph, its very general (and so not very efficient/customized). Other model-based CS techniques exist, but not yet adapted to networks. Obvious starting point for future work is to increase the efficiency of reconstruction.

  11. Immunization of complex networks

    NASA Astrophysics Data System (ADS)

    Pastor-Satorras, Romualdo; Vespignani, Alessandro

    2002-03-01

    Complex networks such as the sexual partnership web or the Internet often show a high degree of redundancy and heterogeneity in their connectivity properties. This peculiar connectivity provides an ideal environment for the spreading of infective agents. Here we show that the random uniform immunization of individuals does not lead to the eradication of infections in all complex networks. Namely, networks with scale-free properties do not acquire global immunity from major epidemic outbreaks even in the presence of unrealistically high densities of randomly immunized individuals. The absence of any critical immunization threshold is due to the unbounded connectivity fluctuations of scale-free networks. Successful immunization strategies can be developed only by taking into account the inhomogeneous connectivity properties of scale-free networks. In particular, targeted immunization schemes, based on the nodes' connectivity hierarchy, sharply lower the network's vulnerability to epidemic attacks.

  12. The vault complex.

    PubMed

    van Zon, A; Mossink, M H; Scheper, R J; Sonneveld, P; Wiemer, E A C

    2003-09-01

    Vaults are large ribonucleoprotein particles found in eukaryotic cells. They are composed of multiple copies of a Mr 100,000 major vault protein and two minor vault proteins of Mr 193,000 and 240,000, as well as small untranslated RNAs of 86-141 bases. The vault components are arranged into a highly characteristic hollow barrel-like structure of 35 x 65 nm in size. Vaults are predominantly localized in the cytoplasm where they may associate with cytoskeletal elements. A small fraction of vaults are found to be associated with the nucleus. As of yet, the precise cellular function of the vault complex is unknown. However, their distinct morphology and intracellular distribution suggest a role in intracellular transport processes. Here we review the current knowledge on the vault complex, its structure, components and possible functions. PMID:14523546

  13. Carney Complex: an update

    PubMed Central

    Correa, Ricardo; Salpea, Paraskevi; Stratakis, Constantine

    2015-01-01

    Carney Complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas, and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22–24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment, and molecular etiology including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing’s syndrome. PMID:26130139

  14. Carney complex: an update.

    PubMed

    Correa, Ricardo; Salpea, Paraskevi; Stratakis, Constantine A

    2015-10-01

    Carney complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22-24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment and molecular etiology, including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing's syndrome. PMID:26130139

  15. NDT for Complex Projects

    NASA Astrophysics Data System (ADS)

    Carnevale, Mario

    2013-04-01

    Non-destructive testing of structures composed of various types of materials is performed using a variety of methods. Most commonly, electromagnetic and acoustic methods are used to perform this task. Advances in computer software and electro-mechanical hardware have resulted in semi-automated systems for performing simple low-cost in-situ concrete testing. These systems are designed to be operated by anyone who can read a manual and push the right buttons. Although useful in many circumstances, we ask: "What happens when concrete structures are not simple and are too complex to be analyzed by these semi-automated systems and, most importantly, by minimally trained operators?" Many infrastructure projects are boldly pushing the limit of traditional engineering design. As structures become more complex, the methods and techniques used to evaluate these structures must also evolve. A first step towards adapting geophysical methods to evaluate complex structures is to develop pre-investigation conceptual models of possible responses that structures will have to available geophysical methods. This approach is important for designing the geometry and data acquisition parameters necessary for achieving the desired results. Examples of case by case assessments of the application of GPR to concrete investigations are examined. These include complex concrete wall structures, soil tunnel structures, and airport runways. HGI's adaption of ground penetrating radar (GPR) and seismic methods for assessing the substrate of a heavily reinforced concrete structure up to seven feet thick is reviewed. A range of GPR antenna frequencies were used to image the concrete and the underlying material. Time and frequency domain GPR analyses where used in the assessment. A multi-channel seismic survey using a roll-along data collection technique was used to assess the resonant frequency of the concrete structure, the nature of the underlying medium, and behavior of the structural system.

  16. Complex Flows by Nanohydrodynamics

    SciTech Connect

    Alley, E; Covello, P; Alder, B

    2004-03-01

    The study of complex flows by particle simulations is speeded up over molecular dynamics (MD) by more than two orders of magnitude by employing a stochastic collision dynamics method (DSMC) extended to high density (CBA). As a consequence, a picture generated on a single processor shows the typical features of the Rayleigh-Taylor instability and is in quantitative agreement with the experimentally found long time behavior.

  17. Complex posterior urethral injury

    PubMed Central

    Kulkarni, Sanjay B.; Joshi, Pankaj M.; Hunter, Craig; Surana, Sandesh; Shahrour, Walid; Alhajeri, Faisal

    2015-01-01

    Objective To assess treatment strategies for seven different scenarios for treating complex pelvic fracture urethral injury (PFUI), categorised as repeat surgery for PFUI, ischaemic bulbar urethral necrosis (BUN), repair in boys and girls aged ⩽12 years, in patients with a recto-urethral fistula, or bladder neck incontinence, or with a double block at the bulbomembranous urethra and bladder neck/prostate region. Patients and methods We retrospectively reviewed the success rates and surgical procedures of these seven complex scenarios in the repair of PFUI at our institution from 2000 to 2013. Results In all, >550 PFUI procedures were performed at our centre, and 308 of these patients were classified as having a complex PFUI, with 225 patients available for follow-up. The overall success rates were 81% and 77% for primary and repeat procedures respectively. The overall success rate of those with BUN was 76%, using various methods of novel surgical techniques. Boys aged ⩽12 years with PFUI required a transpubic/abdominal approach 31% of the time, compared to 9% in adults. Young girls with PFUI also required a transpubic/abdominal urethroplasty, with a success rate of 66%. In patients with a recto-urethral fistula the success rate was 90% with attention to proper surgical principles, including a three-stage procedure and appropriate interposition. The treatment of bladder neck incontinence associated with the tear-drop deformity gave a continence rate of 66%. Children with a double block at the bulbomembranous urethra and at the bladder neck-prostate junction were all continent after a one-stage transpubic/abdominal procedure. Conclusion An understanding of complex pelvic fractures and their appropriate management can provide successful outcomes. PMID:26019978

  18. Modeling Complex Calorimeters

    NASA Technical Reports Server (NTRS)

    Figueroa-Feliciano, Enectali

    2004-01-01

    We have developed a software suite that models complex calorimeters in the time and frequency domain. These models can reproduce all measurements that we currently do in a lab setting, like IV curves, impedance measurements, noise measurements, and pulse generation. Since all these measurements are modeled from one set of parameters, we can fully describe a detector and characterize its behavior. This leads to a model than can be used effectively for engineering and design of detectors for particular applications.

  19. Engineering Complex Tissues

    PubMed Central

    MIKOS, ANTONIOS G.; HERRING, SUSAN W.; OCHAREON, PANNEE; ELISSEEFF, JENNIFER; LU, HELEN H.; KANDEL, RITA; SCHOEN, FREDERICK J.; TONER, MEHMET; MOONEY, DAVID; ATALA, ANTHONY; VAN DYKE, MARK E.; KAPLAN, DAVID; VUNJAK-NOVAKOVIC, GORDANA

    2010-01-01

    This article summarizes the views expressed at the third session of the workshop “Tissue Engineering—The Next Generation,” which was devoted to the engineering of complex tissue structures. Antonios Mikos described the engineering of complex oral and craniofacial tissues as a “guided interplay” between biomaterial scaffolds, growth factors, and local cell populations toward the restoration of the original architecture and function of complex tissues. Susan Herring, reviewing osteogenesis and vasculogenesis, explained that the vascular arrangement precedes and dictates the architecture of the new bone, and proposed that engineering of osseous tissues might benefit from preconstruction of an appropriate vasculature. Jennifer Elisseeff explored the formation of complex tissue structures based on the example of stratified cartilage engineered using stem cells and hydrogels. Helen Lu discussed engineering of tissue interfaces, a problem critical for biological fixation of tendons and ligaments, and the development of a new generation of fixation devices. Rita Kandel discussed the challenges related to the re-creation of the cartilage-bone interface, in the context of tissue engineered joint repair. Frederick Schoen emphasized, in the context of heart valve engineering, the need for including the requirements derived from “adult biology” of tissue remodeling and establishing reliable early predictors of success or failure of tissue engineered implants. Mehmet Toner presented a review of biopreservation techniques and stressed that a new breakthrough in this field may be necessary to meet all the needs of tissue engineering. David Mooney described systems providing temporal and spatial regulation of growth factor availability, which may find utility in virtually all tissue engineering and regeneration applications, including directed in vitro and in vivo vascularization of tissues. Anthony Atala offered a clinician’s perspective for functional tissue

  20. [Complex posttraumatic stress disorder].

    PubMed

    Green, Tamar; Kotler, Moshe

    2007-11-01

    The characteristic symptoms resulting from exposure to an extreme trauma include three clusters of symptoms: persistent experience of the traumatic event, persistent avoidance of stimuli associated with the trauma and persistent symptoms of increased arousal. Beyond the accepted clusters of symptoms for posttraumatic stress disorder exists a formation of symptoms related to exposure to extreme or prolonged stress e.g. childhood abuse, physical violence, rape, and confinement within a concentration camp. With accumulated evidence of the existence of these symptoms began a trail to classify a more complex syndrome, which included, but was not confined to the symptoms of posttraumatic stress disorder. This review addresses several subjects for study in complex posttraumatic stress disorder, which is a complicated and controversial topic. Firstly, the concept of complex posttraumatic stress disorder is presented. Secondly, the professional literature relevant to this disturbance is reviewed and finally, the authors present the polemic being conducted between the researchers of posttraumatic disturbances regarding validity, reliability and the need for separate diagnosis for these symptoms. PMID:18087837

  1. Manufacturing complexity analysis

    NASA Technical Reports Server (NTRS)

    Delionback, L. M.

    1977-01-01

    The analysis of the complexity of a typical system is presented. Starting with the subsystems of an example system, the step-by-step procedure for analysis of the complexity of an overall system is given. The learning curves for the various subsystems are determined as well as the concurrent numbers of relevant design parameters. Then trend curves are plotted for the learning curve slopes versus the various design-oriented parameters, e.g. number of parts versus slope of learning curve, or number of fasteners versus slope of learning curve, etc. Representative cuts are taken from each trend curve, and a figure-of-merit analysis is made for each of the subsystems. Based on these values, a characteristic curve is plotted which is indicative of the complexity of the particular subsystem. Each such characteristic curve is based on a universe of trend curve data taken from data points observed for the subsystem in question. Thus, a characteristic curve is developed for each of the subsystems in the overall system.

  2. Emergent Complex Network Geometry

    NASA Astrophysics Data System (ADS)

    Wu, Zhihao; Menichetti, Giulia; Rahmede, Christoph; Bianconi, Ginestra

    2015-05-01

    Networks are mathematical structures that are universally used to describe a large variety of complex systems such as the brain or the Internet. Characterizing the geometrical properties of these networks has become increasingly relevant for routing problems, inference and data mining. In real growing networks, topological, structural and geometrical properties emerge spontaneously from their dynamical rules. Nevertheless we still miss a model in which networks develop an emergent complex geometry. Here we show that a single two parameter network model, the growing geometrical network, can generate complex network geometries with non-trivial distribution of curvatures, combining exponential growth and small-world properties with finite spectral dimensionality. In one limit, the non-equilibrium dynamical rules of these networks can generate scale-free networks with clustering and communities, in another limit planar random geometries with non-trivial modularity. Finally we find that these properties of the geometrical growing networks are present in a large set of real networks describing biological, social and technological systems.

  3. Complex regional pain syndrome.

    PubMed

    Bruehl, Stephen

    2015-01-01

    Complex regional pain syndrome is a chronic pain condition characterized by autonomic and inflammatory features. It occurs acutely in about 7% of patients who have limb fractures, limb surgery, or other injuries. Many cases resolve within the first year, with a smaller subset progressing to the chronic form. This transition is often paralleled by a change from "warm complex regional pain syndrome," with inflammatory characteristics dominant, to "cold complex regional pain syndrome" in which autonomic features dominate. Multiple peripheral and central mechanisms seem to be involved, the relative contributions of which may differ between individuals and over time. Possible contributors include peripheral and central sensitization, autonomic changes and sympatho-afferent coupling, inflammatory and immune alterations, brain changes, and genetic and psychological factors. The syndrome is diagnosed purely on the basis of clinical signs and symptoms. Effective management of the chronic form of the syndrome is often challenging. Few high quality randomized controlled trials are available to support the efficacy of the most commonly used interventions. Reviews of available randomized trials suggest that physical and occupational therapy (including graded motor imagery and mirror therapy), bisphosphonates, calcitonin, subanesthetic intravenous ketamine, free radical scavengers, oral corticosteroids, and spinal cord stimulation may be effective treatments. Multidisciplinary clinical care, which centers around functionally focused therapies is recommended. Other interventions are used to facilitate engagement in functional therapies and to improve quality of life. PMID:26224572

  4. First pentahaptofullerene metal complexes

    SciTech Connect

    Masaya, Sawamura; Iikura, Hitoshi; Nakamura, Eiichi

    1996-12-18

    Cyclopentadienyl metal complexes have played important roles in chemistry owing to their unique structures and functional activities. Here we report the synthesis and characterization of an entirely new class of cyclopentadienyl (Cp) metal complexes ({eta}{sup 5}-C{sub 60}Ph{sub 5})MLn (MLn = Li, K, Tl, and Cu.PEt{sub 3}). In these molecules, the five Cp carbons represent one pentagon of C{sub 60}, isolated from the remaining 50 sp{sup 2} carbon atoms by five surrounding sp{sup 3} carbon atoms each bearing a phenyl group. The X-ray crystal structure analysis of the thallium complex Tl({eta}{sup 5}-C{sub 60}Ph{sub 5}).2.5THF revealed its unique and esthetically pleasing C{sub 5} symmetrical molecular structure with the phenyl groups forming a chiral propeller array. The thallium atom is deeply buried in the cavity created by the phenyl groups, bonding to the five Cp carbons ({eta}{sup 5}-coordination) with an averaged Tl-C distance of 2.87 A. The key finding that we made in this research was a remarkable 5-fold addition of an organocopper reagent to C{sub 60}, which stands in contrast to the monoaddition reaction of Grignard or organolithium reagents. 10 refs., 1 fig.

  5. Emergent Complex Network Geometry

    PubMed Central

    Wu, Zhihao; Menichetti, Giulia; Rahmede, Christoph; Bianconi, Ginestra

    2015-01-01

    Networks are mathematical structures that are universally used to describe a large variety of complex systems such as the brain or the Internet. Characterizing the geometrical properties of these networks has become increasingly relevant for routing problems, inference and data mining. In real growing networks, topological, structural and geometrical properties emerge spontaneously from their dynamical rules. Nevertheless we still miss a model in which networks develop an emergent complex geometry. Here we show that a single two parameter network model, the growing geometrical network, can generate complex network geometries with non-trivial distribution of curvatures, combining exponential growth and small-world properties with finite spectral dimensionality. In one limit, the non-equilibrium dynamical rules of these networks can generate scale-free networks with clustering and communities, in another limit planar random geometries with non-trivial modularity. Finally we find that these properties of the geometrical growing networks are present in a large set of real networks describing biological, social and technological systems. PMID:25985280

  6. Keynes, Hayek and Complexity

    NASA Astrophysics Data System (ADS)

    Ormerod, Paul

    In the spirit of the overall topic of the conference, in this paper I consider the extent to which economic theory includes elements of the complex systems approach. I am setting to one side here the developments over the past decade in applying complex systems analysis to economic problems. This is not because this recent work is not important. It most certainly is. But I want to argue that there is a very distinct tradition of what we would now describe as a complex systems approach in the works of two of the greatest economists of the 20th century. There is of course a dominant intellectual paradigm within economics, that known as `neo-classical'economics. This paradigm is by no means an empty box, and is undoubtedly useful in helping to understand how some aspects of the social and economic worlds work. But even in its heyday, neo-classical economics never succeeded by its empirical success in driving out completely other theoretical approaches, for its success was simply not sufficient to do so. Much more importantly, economics over the past twenty or thirty years has become in an increasing state of flux.

  7. The selectivity of diglycolamide (TODGA) and bis-triazine-bipyridine (BTBP) ligands in actinide/lanthanide complexation and solvent extraction separation - a theoretical approach.

    PubMed

    Narbutt, Jerzy; Wodyński, Artur; Pecul, Magdalena

    2015-02-14

    Theoretical calculations (density functional theory with the scalar relativistic ZORA Hamiltonian) have been performed to obtain the energy and Gibbs free energy of formation of cationic 1 : 3 complexes of americium(iii) and europium(iii) with a tri-O-dentate diglycolamide ligand TEDGA (a model of TODGA extractant), as well as the free energy of their partition between water and an organic diluent. The distribution of electron density over the atoms, bonds, and molecular orbitals was analyzed by means of Mulliken population analysis, the localization procedure of natural bond orbitals, and the Quantum Theory of Atoms-in-Molecules. The stabilities of both [M(TEDGA)(3)](3+) complexes are similar to each other. On the other hand, our recent data for a similar pair of cationic Am/Eu complexes with a softer (HSAB) tetra-N-dentate ligand C2-BTBP show that the [Am(C2-BTBP)(2)](3+) complex is significantly more stable in aqueous solution than its Eu counterpart. The decisive factor stabilizing the Am(3+) complexes over their Eu(3+) analogues is the charge transfer from the ligands, somewhat greater on the 6d(Am(III)) than on 5d(Eu(III)) orbitals. The covalency of M-N bonds in the [M(C2-BTBP)(2)](3+) complexes is greater than that of M-O bonds in [M(TEDGA)(3)](3+), but the latter is not negligible, in particular in the bonds with the oxygen atoms of the amide groups in TEDGA. The analysis of charge distribution over the whole molecules of the complexes shows that the TEDGA molecule is not hard as expected, but a relatively soft Lewis base, only slightly harder than BTBP. This conclusion has been confirmed by the calculation of the chemical hardness of the ligands. Moreover, the comparison of the results of bonding analysis with the calculated energies of complex formation in water and in the gas phase allows us to conclude that the population analysis, QTAIM topological parameters, and SOPT stabilization energy, as well as Wiberg and overlap-weighted NAO indices are the

  8. The Stigma Complex

    PubMed Central

    Pescosolido, Bernice A.; Martin, Jack K.

    2016-01-01

    Since the beginning of the twenty-first century, research on stigma has continued. Building on conceptual and empirical work, the recent period clarifies new types of stigmas, expansion of measures, identification of new directions, and increasingly complex levels. Standard beliefs have been challenged, the relationship between stigma research and public debates reconsidered, and new scientific foundations for policy and programs suggested. We begin with a summary of the most recent Annual Review articles on stigma, which reminded sociologists of conceptual tools, informed them of developments from academic neighbors, and claimed findings from the early period of “resurgence.” Continued (even accelerated) progress has also revealed a central problem. Terms and measures are often used interchangeably, leading to confusion and decreasing accumulated knowledge. Drawing from this work but focusing on the past 14 years of stigma research (including mental illness, sexual orientation, HIV/AIDS, and race/ethnicity), we provide a theoretical architecture of concepts (e.g., prejudice, experienced/received discrimination), drawn together through a stigma process (i.e., stigmatization), based on four theoretical premises. Many characteristics of the mark (e.g., discredited, concealable) and variants (i.e., stigma types and targets) become the focus of increasingly specific and multidimensional definitions. Drawing from complex and systems science, we propose a stigma complex, a system of interrelated, heterogeneous parts bringing together insights across disciplines to provide a more realistic and complicated sense of the challenge facing research and change efforts. The Framework Integrating Normative Influences on Stigma (FINIS) offers a multilevel approach that can be tailored to stigmatized statuses. Finally, we outline challenges for the next phase of stigma research, with the goal of continuing scientific activity that enhances our understanding of stigma and builds

  9. Complex-Valued Autoencoders

    PubMed Central

    Baldi, Pierre; Lu, Zhiqin

    2012-01-01

    Autoencoders are unsupervised machine learning circuits, with typically one hidden layer, whose learning goal is to minimize an average distortion measure between inputs and outputs. Linear autoencoders correspond to the special case where only linear transformations between visible and hidden variables are used. While linear autoencoders can be defined over any field, only real-valued linear autoencoders have been studied so far. Here we study complex-valued linear autoencoders where the components of the training vectors and adjustable matrices are defined over the complex field with the L2 norm. We provide simpler and more general proofs that unify the real-valued and complex-valued cases, showing that in both cases the landscape of the error function is invariant under certain groups of transformations. The landscape has no local minima, a family of global minima associated with Principal Component Analysis, and many families of saddle points associated with orthogonal projections onto sub-space spanned by sub-optimal subsets of eigenvectors of the covariance matrix. The theory yields several iterative, convergent, learning algorithms, a clear understanding of the generalization properties of the trained autoencoders, and can equally be applied to the hetero-associative case when external targets are provided. Partial results on deep architecture as well as the differential geometry of autoencoders are also presented. The general framework described here is useful to classify autoencoders and identify general properties that ought to be investigated for each class, illuminating some of the connections between autoencoders, unsupervised learning, clustering, Hebbian learning, and information theory. PMID:22622264

  10. Quasicrystals: diversity and complexity

    NASA Astrophysics Data System (ADS)

    Dubois, Jean-Marie; Lifshitz, Ron

    2011-07-01

    Scientific presentations at ICQ11 - the 11th International Conference on Quasicrystals, which took place in Sapporo, Japan, in June 2010 - offered a variety of stimulating new experimental data and novel theoretical results. New aperiodic crystals were presented; new theoretical ideas were described; exciting experimental results were revealed; and potential applications of quasicrystals were reviewed, showing an unprecedented level of development. ICQ11 was a great success thanks to the high standard of its scientific content and to the efficiency of its organization. ICQ11 proved that quasicrystal research is sure to continue offering diverse challenges and profound insights into the complexity of matter.

  11. Emergent complex neural dynamics

    NASA Astrophysics Data System (ADS)

    Chialvo, Dante R.

    2010-10-01

    A large repertoire of spatiotemporal activity patterns in the brain is the basis for adaptive behaviour. Understanding the mechanism by which the brain's hundred billion neurons and hundred trillion synapses manage to produce such a range of cortical configurations in a flexible manner remains a fundamental problem in neuroscience. One plausible solution is the involvement of universal mechanisms of emergent complex phenomena evident in dynamical systems poised near a critical point of a second-order phase transition. We review recent theoretical and empirical results supporting the notion that the brain is naturally poised near criticality, as well as its implications for better understanding of the brain.

  12. Macroevolution of complex retroviruses.

    PubMed

    Katzourakis, Aris; Gifford, Robert J; Tristem, Michael; Gilbert, M Thomas P; Pybus, Oliver G

    2009-09-18

    Retroviruses can leave a "fossil record" in their hosts' genomes in the form of endogenous retroviruses. Foamy viruses, complex retroviruses that infect mammals, have been notably absent from this record. We have found an endogenous foamy virus within the genomes of sloths and show that foamy viruses were infecting mammals more than 100 million years ago and codiverged with their hosts across an entire geological era. Our analysis highlights the role of evolutionary constraint in maintaining viral genome structure and indicates that accessory genes and mammalian mechanisms of innate immunity are the products of macroevolutionary conflict played out over a geological time scale. PMID:19762636

  13. Complex regional pain syndrome.

    PubMed

    Sebastin, Sandeep J

    2011-05-01

    Complex regional pain syndrome (CRPS) previously known as reflex sympathetic dystrophy is a chronic neurological disorder involving the limbs characterized by disabling pain, swelling, vasomotor instability, sudomotor abnormality, and impairment of motor function. CRPS is not uncommon after hand surgery and may complicate post-operative care. There is no specific diagnostic test for CRPS and the diagnosis is based on history, clinical examination, and supportive laboratory findings. Recent modifications to diagnostic criteria have enabled clinicians to diagnose this disease more consistently. This review gives a synopsis of CRPS and discusses the diagnosis, pathophysiology, and treatment options based on the limited evidence in the literature. PMID:22022040

  14. Complex regional pain syndrome

    PubMed Central

    Sebastin, Sandeep J

    2011-01-01

    Complex regional pain syndrome (CRPS) previously known as reflex sympathetic dystrophy is a chronic neurological disorder involving the limbs characterized by disabling pain, swelling, vasomotor instability, sudomotor abnormality, and impairment of motor function. CRPS is not uncommon after hand surgery and may complicate post-operative care. There is no specific diagnostic test for CRPS and the diagnosis is based on history, clinical examination, and supportive laboratory findings. Recent modifications to diagnostic criteria have enabled clinicians to diagnose this disease more consistently. This review gives a synopsis of CRPS and discusses the diagnosis, pathophysiology, and treatment options based on the limited evidence in the literature. PMID:22022040

  15. Physics and complexity

    PubMed Central

    Sherrington, David

    2010-01-01

    This paper is concerned with complex macroscopic behaviour arising in many-body systems through the combinations of competitive interactions and disorder, even with simple ingredients at the microscopic level. It attempts to indicate and illustrate the richness that has arisen, in conceptual understanding, in methodology and in application, across a large range of scientific disciplines, together with a hint of some of the further opportunities that remain to be tapped. In doing so, it takes the perspective of physics and tries to show, albeit rather briefly, how physics has contributed and been stimulated. PMID:20123753

  16. Organization of complex networks

    NASA Astrophysics Data System (ADS)

    Kitsak, Maksim

    Many large complex systems can be successfully analyzed using the language of graphs and networks. Interactions between the objects in a network are treated as links connecting nodes. This approach to understanding the structure of networks is an important step toward understanding the way corresponding complex systems function. Using the tools of statistical physics, we analyze the structure of networks as they are found in complex systems such as the Internet, the World Wide Web, and numerous industrial and social networks. In the first chapter we apply the concept of self-similarity to the study of transport properties in complex networks. Self-similar or fractal networks, unlike non-fractal networks, exhibit similarity on a range of scales. We find that these fractal networks have transport properties that differ from those of non-fractal networks. In non-fractal networks, transport flows primarily through the hubs. In fractal networks, the self-similar structure requires any transport to also flow through nodes that have only a few connections. We also study, in models and in real networks, the crossover from fractal to non-fractal networks that occurs when a small number of random interactions are added by means of scaling techniques. In the second chapter we use k-core techniques to study dynamic processes in networks. The k-core of a network is the network's largest component that, within itself, exhibits all nodes with at least k connections. We use this k-core analysis to estimate the relative leadership positions of firms in the Life Science (LS) and Information and Communication Technology (ICT) sectors of industry. We study the differences in the k-core structure between the LS and the ICT sectors. We find that the lead segment (highest k-core) of the LS sector, unlike that of the ICT sector, is remarkably stable over time: once a particular firm enters the lead segment, it is likely to remain there for many years. In the third chapter we study how

  17. Linking social complexity and vocal complexity: a parid perspective

    PubMed Central

    Krams, Indrikis; Krama, Tatjana; Freeberg, Todd M.; Kullberg, Cecilia; Lucas, Jeffrey R.

    2012-01-01

    The Paridae family (chickadees, tits and titmice) is an interesting avian group in that species vary in important aspects of their social structure and many species have large and complex vocal repertoires. For this reason, parids represent an important set of species for testing the social complexity hypothesis for vocal communication—the notion that as groups increase in social complexity, there is a need for increased vocal complexity. Here, we describe the hypothesis and some of the early evidence that supported the hypothesis. Next, we review literature on social complexity and on vocal complexity in parids, and describe some of the studies that have made explicit tests of the social complexity hypothesis in one parid—Carolina chickadees, Poecile carolinensis. We conclude with a discussion, primarily from a parid perspective, of the benefits and costs of grouping and of physiological factors that might mediate the relationship between social complexity and changes in signalling behaviour. PMID:22641826

  18. Synthesis of crystalline americium hydroxide, Am(OH){sub 3}, and determination of its enthalpy of formation; estimation of the solubility-product constants of actinide(III) hydroxides

    SciTech Connect

    Morss, L.R.; Williams, C.W.

    1993-12-31

    This paper reports a new synthesis of pure, microcrystalline Am(OH){sub 3}, its characterization by x-ray powder diffraction and infrared spectroscopy, and the calorimetric determination of its enthalpy of solution in dilute hydrochloric acid. From the enthalpy of solution the enthalpy of formation of Am(OH){sub 3} has been calculated to be {minus}1371.2{plus_minus}7.9 kj{center_dot}mol{sup {minus}1}, which represents the first experimental determination of an enthalpy of formation of any actinide hydroxide. The free energy of formation and solubility product constant of Am(OH){sub 3} (K{sub sp} = 7 {times} 10{sup {minus}31}) have been calculated from our enthalpy of formation and entropy estimates and are compared with literature measurements under near-equilibrium conditions. Since many properties of the tripositive lanthanide and actinide ions (e.g., hydrolysis, complex-ion formation, and thermochemistry) change in a regular manner, these properties can be interpreted systematically in terms of ionic size. This paper compares the thermochemistry of Am(OH){sub 3} with thermochemical studies of lanthanide hydroxides. A combined structural and acid-base model is used to explain the systematic differences in enthalpies of solution between the oxides and hydroxides of the 4f{sup n} and 5f{sup n} subgroups and to predict solubility-product constants for the actinide(III) hydroxides of Pu through Cf.

  19. Method for preparing radiopharmaceutical complexes

    DOEpatents

    Jones, Alun G.; Davison, Alan; Abrams, Michael J.

    1989-05-02

    A method for preparing radiopharmaceutical complexes that are substantially free of the reaction materials used to produce the radiopharmaceutical complex is disclosed. The method involves admixing in a suitable first solvent in a container a target seeking ligand or salt or metal adduct thereof, a radionuclide label, and a reducing agent for said radionuclide, thereby forming said radiopharmaceutical complex; coating the interior walls of the container with said pharmaceutical complex; discarding the solvent containing by-products and unreacted starting reaction materials; and removing the radiopharmaceutical complex from said walls by dissolving it in a second solvent, thereby obtaining said radiopharmaceutical complex substantially free of by-products and unreacted starting materials.

  20. Polyhydride complexes for hydrogen storage

    SciTech Connect

    Jensen, C.M.

    1995-09-01

    Polyhydride metal complexes are being developed for application in hydrogen storage. Efforts have focused on developing complexes with improved available hydrogen weight percentages. We have explored the possibility that complexes containing aromatic hydrocarbon ligands could store hydrogen at both the metal center and in the ligands. We have synthesized novel indenyl hydride complexes and explored their reactivity with hydrogen. The reversible hydrogenation of [IrH{sub 3}(PPh{sub 3})({eta}{sup 5}-C{sub 10}H{sub 7})]{sup +} has been achieved. While attempting to prepare {eta}{sup 6}-tetrahydronaphthalene complexes, we discovered that certain polyhydride complexes catalyze both the hydrogenation and dehydrogenation of tetrahydronaphthalene.

  1. Shapes of Interacting RNA Complexes

    PubMed Central

    Fu, Benjamin M.M.

    2014-01-01

    Abstract Shapes of interacting RNA complexes are studied using a filtration via their topological genus. A shape of an RNA complex is obtained by (iteratively) collapsing stacks and eliminating hairpin loops. This shape projection preserves the topological core of the RNA complex, and for fixed topological genus there are only finitely many such shapes. Our main result is a new bijection that relates the shapes of RNA complexes with shapes of RNA structures. This allows for computing the shape polynomial of RNA complexes via the shape polynomial of RNA structures. We furthermore present a linear time uniform sampling algorithm for shapes of RNA complexes of fixed topological genus. PMID:25075750

  2. The authority of complexity.

    PubMed

    Stehr, N; Grundmann, R

    2001-06-01

    The assertion about the unique 'complexity' or the peculiarly intricate character of social phenomena has, at least within sociology, a long, venerable and virtually uncontested tradition. At the turn of the last century, classical social theorists, for example, Georg Simmel and Emile Durkheim, made prominent and repeated reference to this attribute of the subject matter of sociology and the degree to which it complicates, even inhibits the develop and application of social scientific knowledge. Our paper explores the origins, the basis and the consequences of this assertion and asks in particular whether the classic complexity assertion still deserves to be invoked in analyses that ask about the production and the utilization of social scientific knowledge in modern society. We present John Maynard Keynes' economic theory and its practical applications as an illustration. We conclude that the practical value of social scientific knowledge is not dependent on a faithful, in the sense of complete, representation of social reality. Instead, social scientific knowledge that wants to optimize its practicality has to attend and attach itself to elements of social situations that can be altered or are actionable. PMID:11440059

  3. Judging orthodontic treatment complexity

    PubMed Central

    Clijmans, Maïté; Medhat, Aly; Geest, An De; van Gastel, Johannes; Kellens, Annelies; Fieuws, Steffen; Willems, Guy

    2016-01-01

    Objective: The aim of the present study was to investigate possible relations between anticipated overall treatment complexity (AOTC) of an orthodontic case and malocclusion characteristics. Methods: Two groups of orthodontists (groups A and B) were asked to define perceived treatment complexity (PTC) of orthodontic cases based on 16 characteristics of malocclusion by means of a questionnaire. Each question was answered on a six-point ordinal scale, with one "not applicable" option (score 0). Group A was also asked to give the AOTC of the specific case on a five-point ordinal scale. The index of orthodontic treatment need (IOTN) score of the specific cases as well as the malocclusion characteristics were assessed by one author. Results: There is a significant relationship between IOTN and AOTC (p< 0.0001), 22% of variability is explained by differences in IOTN. Adding objective characteristics of malocclusion to explain AOTC does not significantly increase the explained variability (p = 0.086). In judging interobserver agreement, a weighted Kappa of 0.60 for group A and 0.56 for group B was found. The weighted Kappa for agreement in AOTC equals 0.06. Conclusion: The relation between IOTN and AOTC was found to be significant. Moderate agreement on PTC among observers and a low level agreement regarding AOTC were found in the present study. PMID:27007763

  4. [Complex decongestive therapy].

    PubMed

    Heinig, B; Wollina, U

    2015-11-01

    The amount of physical pressure plays an important role in complex decongestive therapy (CDT). As a function of pressure, microcirculation takes place between blood vessels and tissue. As part of the total lymphatic system, lymphatic vessels transport the lymphatic load from the interstitial space to the blood stream. The lymphatic vessel system, characterized by specific anatomical conditions like initial lymphatic vessels, precollectors, collectors, and lymphatic strains, is the therapeutic target of complex decongestive therapy. Components of CDT include manual lymphatic drainage, compression therapy, decongestive kinesitherapy, and good skin care, which increase the transport capacity of the lymphatic vessel system. Currently, CDT is acknowledged as the main conservative treatment of lymphedema of primary and secondary genesis, lipolymphedema, and phlebolymphedema. In clinical practice, we are increasingly confronted with edema of multifactorial genesis requiring a critical discussion and stocktaking of comprehensive clinical findings in terms of the indication for CDT. Therapeutic success depends on a joint application of all CDT components and patient compliance. To an increasing extent, medical research tries to combine successfully CDT with adjunct treatment options. PMID:26315101

  5. Complex master slave interferometry.

    PubMed

    Rivet, Sylvain; Maria, Michael; Bradu, Adrian; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian

    2016-02-01

    A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of channeled spectra at the Master stage equated the number of depths where information was selected from at the Slave stage. The paper demonstrates that two experimental channeled spectra only acquired at Master stage suffice to produce A-scans from any number of resolved depths at the Slave stage. A second improvement is the utilization of complex signal processing. Previous MSI implementations discarded the phase. Complex processing of the electrical signal determined by the channeled spectrum allows phase processing that opens several novel avenues. A first consequence of such signal processing is reduction in the random component of the phase without affecting the axial resolution. In previous MSI implementations, phase instabilities were reduced by an average over the wavenumber that led to reduction in the axial resolution. PMID:26906857

  6. Tuberous sclerosis complex.

    PubMed

    Henske, Elizabeth P; Jóźwiak, Sergiusz; Kingswood, J Christopher; Sampson, Julian R; Thiele, Elizabeth A

    2016-01-01

    Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that affects multiple organ systems and is caused by loss-of-function mutations in one of two genes: TSC1 or TSC2. The disorder can affect both adults and children. First described in depth by Bourneville in 1880, it is now estimated that nearly 2 million people are affected by the disease worldwide. The clinical features of TSC are distinctive and can vary widely between individuals, even within one family. Major features of the disease include tumours of the brain, skin, heart, lungs and kidneys, seizures and TSC-associated neuropsychiatric disorders, which can include autism spectrum disorder and cognitive disability. TSC1 (also known as hamartin) and TSC2 (also known as tuberin) form the TSC protein complex that acts as an inhibitor of the mechanistic target of rapamycin (mTOR) signalling pathway, which in turn plays a pivotal part in regulating cell growth, proliferation, autophagy and protein and lipid synthesis. Remarkable progress in basic and translational research, in addition to several randomized controlled trials worldwide, has led to regulatory approval of the use of mTOR inhibitors for the treatment of renal angiomyolipomas, brain subependymal giant cell astrocytomas and pulmonary lymphangioleiomyomatosis, but further research is needed to establish full indications of therapeutic treatment. In this Primer, we review the state-of-the-art knowledge in the TSC field, including the molecular and cellular basis of the disease, medical management, major knowledge gaps and ongoing research towards a cure. PMID:27226234

  7. BTA copper complexes.

    PubMed

    Friedrich, Manfred; Gálvez-Ruiz, Juan Carlos; Klapötke, Thomas M; Mayer, Peter; Weber, Birgit; Weigand, Jan J

    2005-10-31

    Cupric oxide is one of the most important additives used (a) to catalyze decomposition reactions in gas generators to obtain cooler reaction gases, (b) as burning enhancer for ammonium perchlorate-based composite propellants, and (c) as coloring agent in pyrotechnics. In this context, the reaction of Cu(2+) ions in aqueous ammonia solution with bis(tetrazolyl)amine (H(2)bta) was investigated. Depending on the reaction conditions three complexes were obtained: Cu(bta)(NH(3))(2) (1), Cu(bta)(NH(3))(2).H(2)O (2), and (NH(4))(2)Cu(bta)(2).2.5H(2)O (3). The crystal structures of 1 and 2 are discussed with respect to the coordination mode of the dianion of N,N-bis(1(2)H-tetrazol-5-yl)-amine (bta), which mediates in the case of 1 and 2 weak superexchange interactions between the adjacent magnetic transition-metal Cu(II) cations. These antiferromagnetic interactions result from 1D copper chains over an hidden azide end-to-end bridge. Interestingly, the structural arrangement of 1 completely changes in the presence of crystal-bound water. Moreover, some physicochemical properties (e.g., heat of formation, friction, and impact sensitivity, DSC) of these complexes with respect to high-energetic materials are discussed. PMID:16241154

  8. Not so Complex: Iteration in the Complex Plane

    ERIC Educational Resources Information Center

    O'Dell, Robin S.

    2014-01-01

    The simple process of iteration can produce complex and beautiful figures. In this article, Robin O'Dell presents a set of tasks requiring students to use the geometric interpretation of complex number multiplication to construct linear iteration rules. When the outputs are plotted in the complex plane, the graphs trace pleasing designs…

  9. Syntactic Complexity as an Aspect of Text Complexity

    ERIC Educational Resources Information Center

    Frantz, Roger S.; Starr, Laura E.; Bailey, Alison L.

    2015-01-01

    Students' ability to read complex texts is emphasized in the Common Core State Standards (CCSS) for English Language Arts and Literacy. The standards propose a three-part model for measuring text complexity. Although the model presents a robust means for determining text complexity based on a variety of features inherent to a text as well as…

  10. Nuclear Weapons Complex reconfiguration study

    SciTech Connect

    Not Available

    1991-01-01

    Shortly after assuming duties as Secretary of Energy, I reviewed the Nuclear Weapons Complex Modernization Report'' submitted to the Congress in January 1989 as required by the National Defense Authorization Act of 1988 and 1989. My review showed that several of the report's assumptions needed to be re-evaluated. During this eighteen-month review, dramatic world changes forced further reassessments of the future Nuclear Weapons Complex. These changes are reflected in the new report. The new report presents a plan to achieve a reconfigured complex, called Complex-21. Complex-21 would be smaller, less diverse, and less expensive to operated than the Complex of today. Complex-21 would be able to safely and reliability support nuclear deterrent stockpile objectives set forth by the President and funded by the Congress. It would be consistent with realities of the emerging international security environment and flexible enough to accommodate the likely range of deterrent contingencies. In addition, Complex-21 would be constructed and operated to comply with all applicable federal, state, and local laws, regulations, and orders. Achieving Complex-21 will require significant resources. This report provides and organized approach toward selecting the most appropriate configuration for Complex-21, satisfying environmental requirements, and minimizing costs. The alternative -- to continue to use piecemeal fixes to run an antiquated complex -- will be more expensive and provide a less reliable Nuclear Weapons Complex. As a consequence, implementation of the Complex-21 plan is considered necessary to ensure continued viability of our nuclear deterrent.

  11. Features of the thermodynamics of two-phase distribution reactions of americium(III) and europium(III) nitrates into solutions of 2,6-bis[(bis(2-ethylhexyl)phosphino)methyl]pyridine N,P,P'-trioxide.

    SciTech Connect

    Nash, K. L.; Lavallette, C.; Borkowski, M.; Paine, R. T.; Gan, X.; Chemistry; Univ. of New Mexico

    2002-11-04

    New bifunctional and trifunctional organophosphorus ligands, 2-[(bis(2-ethylhexyl)phosphino)methyl]pyridine N,P-dioxide, DEH(MNOPO), and 2,6-bis[(bis(2-ethylhexyl)phosphino)methyl]pyridine N,P,P'-trioxide, TEH(NOPOPO), have been synthesized. In contrast with previously reported phenyl derivatives, the increased solubility of these ligands in normal paraffinic hydrocarbon solvents make them attractive reagents for actinide partitioning. While the bifunctional reagent DEH(MNOPO) interacts with Eu{sup 3+} and Am{sup 3+} comparatively weakly, the trifunctional TEH(NOPOPO) exhibits moderate to high ability to transfer the trisnitrato complexes of these ions into n-dodecane from acidic aqueous solutions. We report here the details of TEH(NOPOPO) and DEH(MNOPO) preparation and of their ability to extract HNO{sub 3}, Am(NO{sub 3}){sub 3}, and Eu(NO{sub 3}){sub 3} into paraffinic hydrocarbons. The trifunctional TEH(NOPOPO) can extract up to two molecules of HNO{sub 3}. The dominant extracted species for both Am(NO{sub 3}){sub 3} and Eu(NO{sub 3}){sub 3} has two TEH(NOPOPO) ligands associated over the range of temperatures 10-40 C. From the variation in the equilibrium coefficients for the phase transfer reactions as a function of temperature, we have calculated the enthalpies and entropies for extraction of HNO{sub 3}, Am(NO{sub 3}){sub 3}, and Eu(NO{sub 3}){sub 3} into n-dodecane. Each metal nitrate is transferred into the organic phase in an exothermic process but opposed by an unfavorable (negative) entropy. The thermodynamic data are interpreted to indicate that the pyridine N-oxide is apparently a significantly weaker donor group for these metal ions than the phosphine oxides.

  12. Amphotericin B Lipid Complex Injection

    MedlinePlus

    Amphotericin B lipid complex injection is used to treat serious, possibly life-threatening fungal infections in people who did not respond ... to tolerate conventional amphotericin B therapy. Amphotericin B lipid complex injection is in a class of medications ...

  13. Genetics Home Reference: Carney complex

    MedlinePlus

    Skip to main content Your Guide to Understanding Genetic Conditions Enable Javascript for addthis links to activate. ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions Carney complex Carney complex Enable ...

  14. Complexity in scalable computing.

    SciTech Connect

    Rouson, Damian W. I.

    2008-12-01

    The rich history of scalable computing research owes much to a rapid rise in computing platform scale in terms of size and speed. As platforms evolve, so must algorithms and the software expressions of those algorithms. Unbridled growth in scale inevitably leads to complexity. This special issue grapples with two facets of this complexity: scalable execution and scalable development. The former results from efficient programming of novel hardware with increasing numbers of processing units (e.g., cores, processors, threads or processes). The latter results from efficient development of robust, flexible software with increasing numbers of programming units (e.g., procedures, classes, components or developers). The progression in the above two parenthetical lists goes from the lowest levels of abstraction (hardware) to the highest (people). This issue's theme encompasses this entire spectrum. The lead author of each article resides in the Scalable Computing Research and Development Department at Sandia National Laboratories in Livermore, CA. Their co-authors hail from other parts of Sandia, other national laboratories and academia. Their research sponsors include several programs within the Department of Energy's Office of Advanced Scientific Computing Research and its National Nuclear Security Administration, along with Sandia's Laboratory Directed Research and Development program and the Office of Naval Research. The breadth of interests of these authors and their customers reflects in the breadth of applications this issue covers. This article demonstrates how to obtain scalable execution on the increasingly dominant high-performance computing platform: a Linux cluster with multicore chips. The authors describe how deep memory hierarchies necessitate reducing communication overhead by using threads to exploit shared register and cache memory. On a matrix-matrix multiplication problem, they achieve up to 96% parallel efficiency with a three-part strategy: intra

  15. [COMPLEX REGIONAL PAIN SYNDROME].

    PubMed

    Blažeković, Ivan; Bilić, Ervina; Žagar, Marija; Anić, Branimir

    2015-01-01

    Complex regional pain syndrome (CRPS) represents a state of constant and often disabling pain, affecting one region (usually hand) and often occurs after a trauma whose severity does not correlate with the level of pain. The older term for this condition of chronic pain associated with motor and autonomic symptoms is reflex sympathetic dystrophy or causalgia. The aim of this review, based on contemporary literature, is to show the epidemiology and etiology, proposed pathophysiological mechanisms, method of diagnosis and treatment options, prevention and mitigation of this under-recognized disease. CRPS I occurs without known neurological damage, unlike CRPS II, where the history of trauma is present and in some cases damage to the peripheral nervous system can be objectively assessed using electromyoneurography. New diagnostic methods, such as quantitative sensory testing (CST), challenge this division because the CST findings in patients with CRPS I can suggest damage to Adelta peripheral nerve fibers. Except for distinguishing type I and type II disease, it is important to bear in mind the diversity of clinical presentation of CRPS in acute and chronic phase of the disease. This regional pain syndrome typically includes the autonomic and motor signs and thus differs from other peripheral neuropathic pain syndromes. The complexity of the clinical presentation indicates the likely presence of different pathophysiological mechanisms underlying this disease. Previous studies have demonstrated the autonomic dysfunction, neurogenic inflammation and neuroplastic changes. The diagnosis of CRPS is based on anamnesis and clinical examination on the basis of which the disease can be graded according to the Budapest Criteria. A valuable aid in differentiating subtypes of the disease is electromyoneurography. The treatment of CRPS is as complex as the clinical picture and the pathophysiology of the disease and requires interdisciplinary cooperation and individual approach

  16. Transient complex peroxisomal interactions

    PubMed Central

    Bonekamp, Nina A.; Schrader, Michael

    2012-01-01

    Mitochondria and peroxisomes are ubiquitous subcellular organelles that fulfill essential metabolic functions, rendering them indispensable for human development and health. Both are highly dynamic organelles that can undergo remarkable changes in morphology and number to accomplish cellular needs. While mitochondrial dynamics are also regulated by frequent fusion events, the fusion of mature peroxisomes in mammalian cells remained a matter of debate. In our recent study, we clarified systematically that there is no complete fusion of mature peroxisomes analogous to mitochondria. Moreover, in contrast to key division components such as DLP1, Fis1 or Mff, mitochondrial fusion proteins were not localized to peroxisomes. However, we discovered and characterized novel transient, complex interactions between individual peroxisomes which may contribute to the homogenization of the often heterogeneous peroxisomal compartment, e.g., by distribution of metabolites, signals or other “molecular information” via interperoxisomal contact sites. PMID:23336019

  17. Evolution of Biological Complexity

    NASA Astrophysics Data System (ADS)

    Goldstein, Raymond E.

    It is a general rule of nature that larger organisms are more complex, at least as measured by the number of distinct types of cells present. This reflects the fitness advantage conferred by a division of labor among specialized cells over homogeneous totipotency. Yet, increasing size has both costs and benefits, and the search for understanding the driving forces behind the evolution of multicellularity is becoming a very active area of research. This article presents an overview of recent experimental and theoretical work aimed at understanding this biological problem from the perspective of physics. For a class of model organisms, the Volvocine green algae, an emerging hypothesis connects the transition from organisms with totipotent cells to those with terminal germ-soma differentiation to the competition between diffusion and fluid advection created by beating flagella. A number of challenging problems in fluid dynamics, nonlinear dynamics, and control theory emerge when one probes the workings of the simplest multicellular organisms.

  18. Complexity, Metastability and Nonextensivity

    NASA Astrophysics Data System (ADS)

    Beck, C.; Benedek, G.; Rapisarda, A.; Tsallis, C.

    Work and heat fluctuations in systems with deterministic and stochastic forces / E. G. D. Cohen and R. Van Zon -- Is the entropy S[symbol] extensive or nonextensive? / C. Tsallis -- Superstatistics: recent developments and applications / C. Beck -- Two stories outside Boltzmann-Gibbs statistics: Mori's Q-phase transitions and glassy dynamics at the onset of chaos / A. Robledo, F. Baldovin and E. Mayoral -- Time-averages and the heat theorem / A. Carati -- Fundamental formulae and numerical evidences for the central limit theorem in Tsallis statistics / H. Suyari -- Generalizing the Planck distribution / A. M. C. Soma and C. Tsallis -- The physical roots of complexity: renewal or modulation? / P. Grigolini -- Nonequivalent ensembles and metastability / H. Touchette and R. S. Ellis -- Statistical physics for cosmic structures / L. Pietronero and F. Sylos Labini -- Metastability and anomalous behavior in the HMF model: connections to nonextensive thermodynamics and glassy dynamics / A. Pluchino, A. Rapisarda and V. Latora -- Vlasov analysis of relaxation and meta-equilibrium / C. Anteneodo and R. O. Vallejos -- Weak chaos in large conservative systems - infinite-range coupled standard maps / L. G. Moyano, A. P. Majtey and C. Tsallis -- Deterministc aging / E. Barkai -- Edge of chaos of the classical kicked top map: sensitivity to initial conditions / S. M. Duarte Queirós and C. Tsallis -- What entropy at the edge of chaos? / M. Lissia, M. Coraddu and R. Tonelli -- Fractal growth of carbon schwarzites / G. Benedek ... [et al.] -- Clustering and interface propagation in interacting particle dynamics / A. Provata and V. K. Noussiou -- Resonant activation and noise enhanced stability in Josephson junctions / A. L. Pankratov and B. Spagnolo -- Symmetry breaking induced directed motions / C.-H. Chang and T. Y. Tsong -- General theory of Galilean-invariant entropic lattic Boltzmann models / B. M. Boghosian -- Unifying approach to the jamming transition in granular media and

  19. Complex regional pain syndrome

    PubMed Central

    Carr, Emily S.; De La Cerda, Ashley

    2016-01-01

    Complex regional pain syndrome (CRPS) is a neurologic disorder that often results in debilitating chronic pain, but the diagnosis may elude providers as it is one of exclusion. A history of trauma may be elucidated. We report a case of CRPS and review the clinical findings, appropriate workup, and treatment options for the patient. The patient we describe went through an extensive workup before receiving the correct diagnosis. Delay in diagnosis leads to prolonged suffering for the patient and, at times, unnecessary invasive debridement procedures. Raising awareness of this entity may help physicians make the correct diagnosis early, as well as initiate a collaborative effort between neurology, anesthesiology, and dermatology to provide the patient the most favorable outcome. PMID:27365892

  20. Complex pendulum biomass sensor

    DOEpatents

    Hoskinson, Reed L.; Kenney, Kevin L.; Perrenoud, Ben C.

    2007-12-25

    A complex pendulum system biomass sensor having a plurality of pendulums. The plurality of pendulums allow the system to detect a biomass height and density. Each pendulum has an angular deflection sensor and a deflector at a unique height. The pendulums are passed through the biomass and readings from the angular deflection sensors are fed into a control system. The control system determines whether adjustment of machine settings is appropriate and either displays an output to the operator, or adjusts automatically adjusts the machine settings, such as the speed, at which the pendulums are passed through the biomass. In an alternate embodiment, an entanglement sensor is also passed through the biomass to determine the amount of biomass entanglement. This measure of entanglement is also fed into the control system.

  1. Complex Dark Matter

    SciTech Connect

    Lincoln, Don

    2015-04-16

    After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe. In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter. The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature. In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions. While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

  2. Complex Tectonism on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Complex tectonism is evident in these images of Ganymede's surface. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The 80 kilometer (50 mile) wide lens-shaped feature in the center of the image is located at 32 degrees latitude and 188 degrees longitude along the border of a region of ancient dark terrain known as Marius Regio, and is near an area of younger bright terrain named Nippur Sulcus. The tectonism that created the structures in the bright terrain nearby has strongly affected the local dark terrain to form unusual structures such as the one shown here. The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede.

    North is to the top-left of the image, and the sun illuminates the surface from the southeast. The image covers an area about 63 kilometers (39 miles) by 120 kilometers (75 miles) across at a resolution of 188 meters (627 feet) per picture element. The images were taken on September 6, 1996 at a range of 18,522 kilometers (11,576 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  3. Canberra Deep Dish Communications Complex

    NASA Technical Reports Server (NTRS)

    1990-01-01

    View of Canberra 70m (230 ft.) antenna with flags from the three Deep Space Network sites. The Canberra Deep Space Communications Complex, located outside Canberra, Australia, is one of the three complexes which comprise NASA's Deep Space Network. The other complexes are located in Goldstone, California, and Madrid, Spain.

  4. Managing complexity of aerospace systems

    NASA Astrophysics Data System (ADS)

    Tamaskar, Shashank

    Growing complexity of modern aerospace systems has exposed the limits of conventional systems engineering tools and challenged our ability to design them in a timely and cost effective manner. According to the US Government Accountability Office (GAO), in 2009 nearly half of the defense acquisition programs are expecting 25% or more increase in unit acquisition cost. Increase in technical complexity has been identified as one of the primary drivers behind cost-schedule overruns. Thus to assure the affordability of future aerospace systems, it is increasingly important to develop tools and capabilities for managing their complexity. We propose an approach for managing the complexity of aerospace systems to address this pertinent problem. To this end, we develop a measure that improves upon the state-of-the-art metrics and incorporates key aspects of system complexity. We address the problem of system decomposition by presenting an algorithm for module identification that generates modules to minimize integration complexity. We demonstrate the framework on diverse spacecraft and show the impact of design decisions on integration cost. The measure and the algorithm together help the designer track and manage complexity in different phases of system design. We next investigate how complexity can be used as a decision metric in the model-based design (MBD) paradigm. We propose a framework for complexity enabled design space exploration that introduces the idea of using complexity as a non-traditional design objective. We also incorporate complexity with the component based design paradigm (a sub-field of MBD) and demonstrate it on several case studies. The approach for managing complexity is a small but significant contribution to the vast field of complexity management. We envision our approach being used in concert with a suite of complexity metrics to provide an ability to measure and track complexity through different stages of design and development. This will not

  5. A geometric approach to complexity.

    PubMed

    Ay, Nihat; Olbrich, Eckehard; Bertschinger, Nils; Jost, Jürgen

    2011-09-01

    We develop a geometric approach to complexity based on the principle that complexity requires interactions at different scales of description. Complex systems are more than the sum of their parts of any size and not just more than the sum of their elements. Using information geometry, we therefore analyze the decomposition of a system in terms of an interaction hierarchy. In mathematical terms, we present a theory of complexity measures for finite random fields using the geometric framework of hierarchies of exponential families. Within our framework, previously proposed complexity measures find their natural place and gain a new interpretation. PMID:21974666

  6. The Mycobacterium avium complex.

    PubMed Central

    Inderlied, C B; Kemper, C A; Bermudez, L E

    1993-01-01

    Mycobacterium avium complex (MAC) disease emerged early in the epidemic of AIDS as one of the common opportunistic infections afflicting human immunodeficiency virus-infected patients. However, only over the past few years has a consensus developed about its significance to the morbidity and mortality of AIDS. M. avium was well known to mycobacteriologists decades before AIDS, and the MAC was known to cause disease, albeit uncommon, in humans and animals. The early interest in the MAC provided a basis for an explosion of studies over the past 10 years largely in response to the role of the MAC in AIDS opportunistic infection. Molecular techniques have been applied to the epidemiology of MAC disease as well as to a better understanding of the genetics of antimicrobial resistance. The interaction of the MAC with the immune system is complex, and putative MAC virulence factors appear to have a direct effect on the components of cellular immunity, including the regulation of cytokine expression and function. There now is compelling evidence that disseminated MAC disease in humans contributes to both a decrease in the quality of life and survival. Disseminated disease most commonly develops late in the course of AIDS as the CD4 cells are depleted below a critical threshold, but new therapies for prophylaxis and treatment offer considerable promise. These new therapeutic modalities are likely to be useful in the treatment of other forms of MAC disease in patients without AIDS. The laboratory diagnosis of MAC disease has focused on the detection of mycobacteria in the blood and tissues, and although the existing methods are largely adequate, there is need for improvement. Indeed, the successful treatment of MAC disease clearly will require an early and rapid detection of the MAC in clinical specimens long before the establishment of the characteristic overwhelming infection of bone marrow, liver, spleen, and other tissue. Also, a standard method of susceptibility testing

  7. Sociality influences cultural complexity

    PubMed Central

    Muthukrishna, Michael; Shulman, Ben W.; Vasilescu, Vlad; Henrich, Joseph

    2014-01-01

    Archaeological and ethnohistorical evidence suggests a link between a population's size and structure, and the diversity or sophistication of its toolkits or technologies. Addressing these patterns, several evolutionary models predict that both the size and social interconnectedness of populations can contribute to the complexity of its cultural repertoire. Some models also predict that a sudden loss of sociality or of population will result in subsequent losses of useful skills/technologies. Here, we test these predictions with two experiments that permit learners to access either one or five models (teachers). Experiment 1 demonstrates that naive participants who could observe five models, integrate this information and generate increasingly effective skills (using an image editing tool) over 10 laboratory generations, whereas those with access to only one model show no improvement. Experiment 2, which began with a generation of trained experts, shows how learners with access to only one model lose skills (in knot-tying) more rapidly than those with access to five models. In the final generation of both experiments, all participants with access to five models demonstrate superior skills to those with access to only one model. These results support theoretical predictions linking sociality to cumulative cultural evolution. PMID:24225461

  8. Shanghai Delta Complex

    SciTech Connect

    Hart, R.E.; Hoffman, P.F.; Parker, R.W.

    1988-01-01

    The upper Eocene Yegua Formation expands dramatically across a regional system of growth faults into an area generally 12-15 km wide, extending at least from the western edge of the Houston sale dome basin to the San Marcos arch. Within this area, the expanded Yegua trend has yielded, since 1982, at least seven noteworthy discoveries: Toro Grande and Lost Bridge fields in Jackson County, and Black Owl, Shanghai, Shanghai East, El Campo, and Phase Four fields in Wharton County. During each of several postulated Yegua sea level drops, this flexure became a focal point for deltaic deposition of excellent reservoir-quality sands. Shanghai, Shanghai East, and El Campo fields are located within what the writers have labeled the ''Shanghai delta complex.'' Integration of seismic and well data in this vicinity shows a marked increase in the expansion indices of growth faults, and moderately thick progradational sand sequences have accumulated immediately downthrow. This structural-stratigraphic pattern, as well as internal bedding characteristics and other lithologic data observed, is believed typical of deltas deposited along the Yegua shelf margin.

  9. Fact Sheet: Range Complex

    NASA Technical Reports Server (NTRS)

    Cornelson, C.; Fretter, E.

    2004-01-01

    NASA Ames has a long tradition in leadership with the use of ballistic ranges and shock tubes for the purpose of studying the physics and phenomena associated with hypervelocity flight. Cutting-edge areas of research run the gamut from aerodynamics, to impact physics, to flow-field structure and chemistry. This legacy of testing began in the NACA era of the 1940's with the Supersonic Free Flight Tunnel, and evolved dramatically up through the late 1950s with the pioneering work in the Ames Hypersonic Ballistic Range. The tradition continued in the mid-60s with the commissioning of the three newest facilities: the Ames Vertical Gun Range (AVGR) in 1964, the Hypervelocity Free Flight Facility (HFFF) in 1965 and the Electric Arc Shock Tube (EAST) in 1966. Today the Range Complex continues to provide unique and critical testing in support of the Nation's programs for planetary geology and geophysics; exobiology; solar system origins; earth atmospheric entry, planetary entry, and aerobraking vehicles; and various configurations for supersonic and hypersonic aircraft.

  10. Hypernetworks of Complex Systems

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey

    Hypernetworks generalise the concept of a relation between two things to relations between many things. The notion of relational simplex generalises the concept of network edge to relations between many elements. Relational simplices have multi-dimensional connectivity related to hyper-graphs and the Galois lattice of maximally connected sets of elements. This structure acts as a kind of backcloth for the dynamic system traffic represented by numerical mappings, where the topology of the backcloth constrains the dynamics of the traffic. Simplices provide a way of defining multilevel structure. This relates to system time measured by the formation of simplices as system events. Multilevel hypernetworks are classes of sets of relational simplices that represent the system backcloth and the traffic of systems activity it supports. Hypernetworks provide a significant generalisation of network theory, enabling the integration of relational structure, logic, and topological and analytic dynamics. They provide structures that are likely to be necessary if not sufficient for a science of complex multilevel socio-technical systems.

  11. Complex emergencies in Indonesia.

    PubMed

    Bradt, D A; Drummond, C M; Richman, M

    2001-01-01

    Recently, Indonesia has experienced six major provincial, civil, armed conflicts. Underlying causes include the transmigration policy, sectarian disputes, the Asian economic crisis, fall of authoritarian rule, and a backlash against civil and military abuses. The public health impact involves the displacement nationwide of > 1.2 million persons. Violence in the Malukus, Timor, and Kalimantan has sparked the greatest population movements such that five provinces in Indonesia each now harbor > 100,000 internally displaced persons. With a background of government instability, hyperinflation, macroeconomic collapse, and elusive political solutions, these civil armed conflicts are ripe for persistence as complex emergencies. Indonesia has made substantial progress in domestic disaster management with the establishment of central administrative authority, strategic planning, and training programs. Nevertheless, the Indonesian experience reveals recurrent issues in international humanitarian health assistance. Clinical care remains complicated by absences of treatment protocols, inappropriate drug use, high procedural complication rates, and variable referral practices. Epidemiological surveillance remains complicated by unsettled clinical case definitions, non-standardized case management of diseases with epidemic potential, variable outbreak management protocols, and inadequate epidemiological analytic capacity. International donor support has been semi-selective, insufficient, and late. The militia murders of three UN staff in West Timor prompted the withdrawal of UN international staff from West Timor for nearly a year to date. Re-establishing rules of engagement for humanitarian health workers must address security, public health, and clinical threats. PMID:12090212

  12. Information Complexity and Biology

    NASA Astrophysics Data System (ADS)

    Bagnoli, Franco; Bignone, Franco A.; Cecconi, Fabio; Politi, Antonio

    Kolmogorov contributed directly to Biology in essentially three problems: the analysis of population dynamics (Lotka-Volterra equations), the reaction-diffusion formulation of gene spreading (FKPP equation), and some discussions about Mendel's laws. However, the widely recognized importance of his contribution arises from his work on algorithmic complexity. In fact, the limited direct intervention in Biology reflects the generally slow growth of interest of mathematicians towards biological issues. From the early work of Vito Volterra on species competition, to the slow growth of dynamical systems theory, contributions to the study of matter and the physiology of the nervous system, the first 50-60 years have witnessed important contributions, but as scattered pieces apparently uncorrelated, and in branches often far away from Biology. Up to the 40' it is hard to see the initial loose build up of a convergence, for those theories that will become mainstream research by the end of the century, and connected by the study of biological systems per-se.

  13. Nonisostructural complex oxide heteroepitaxy

    SciTech Connect

    Wong, Franklin J. Ramanathan, Shriram

    2014-07-01

    The authors present an overview of the fundamentals and representative examples of the growth of epitaxial complex oxide thin films on structurally dissimilar substrates. The authors will delineate how the details of particular crystal structures and symmetry of different oxide surfaces can be employed for a rational approach to the synthesis of nonisostructural epitaxial heterostructures. The concept of oxygen eutaxy can be widely applied. Materials combinations will be split into three categories, and in all cases the films and substrates occur in different crystal structures: (1) common translational and rotational symmetry between the film and substrate planes; (2) translational symmetry mismatch between the substrates and films that is distinct from a simple mismatch in lattice parameters; and (3) rotational symmetry mismatch. In case (1), in principle single-crystalline thin films can be attained despite the films and substrates possessing different crystal structures. In case (2), antiphase boundaries will be prevalent in the thin films. In case (3), thin-film rotational variants that are joined by tilt boundaries will be present. Diffraction techniques to determine crystallographic alignment and epitaxial variants are discussed, and transmission electron microscopy studies to investigate extended defects in the thin films will also be reviewed. The authors end with open problems in this field regarding the structure of oxide interfaces that can be topics for future research.

  14. What is a complex graph?

    NASA Astrophysics Data System (ADS)

    Kim, Jongkwang; Wilhelm, Thomas

    2008-04-01

    Many papers published in recent years show that real-world graphs G(n,m) ( n nodes, m edges) are more or less “complex” in the sense that different topological features deviate from random graphs. Here we narrow the definition of graph complexity and argue that a complex graph contains many different subgraphs. We present different measures that quantify this complexity, for instance C1e, the relative number of non-isomorphic one-edge-deleted subgraphs (i.e. DECK size). However, because these different subgraph measures are computationally demanding, we also study simpler complexity measures focussing on slightly different aspects of graph complexity. We consider heuristically defined “product measures”, the products of two quantities which are zero in the extreme cases of a path and clique, and “entropy measures” quantifying the diversity of different topological features. The previously defined network/graph complexity measures Medium Articulation and Offdiagonal complexity ( OdC) belong to these two classes. We study OdC measures in some detail and compare it with our new measures. For all measures, the most complex graph G has a medium number of edges, between the edge numbers of the minimum and the maximum connected graph n-1complexity measures are characterized with the help of different example graphs. For all measures the corresponding time complexity is given. Finally, we discuss the complexity of 33 real-world graphs of different biological, social and economic systems with the six computationally most simple measures (including OdC). The complexities of the real graphs are compared with average complexities of two different random graph versions: complete random graphs (just fixed n,m) and rewired graphs with fixed node degrees.

  15. Spatiotemporal imaging of complexity

    PubMed Central

    Robinson, Stephen E.; Mandell, Arnold J.; Coppola, Richard

    2013-01-01

    What are the functional neuroimaging measurements required for more fully characterizing the events and locations of neocortical activity? A prime assumption has been that modulation of cortical activity will inevitably be reflected in changes in energy utilization (for the most part) changes of glucose and oxygen consumption. Are such a measures complete and sufficient? More direct measures of cortical electrophysiological activity show event or task-related modulation of amplitude or band-limited oscillatory power. Using magnetoencephalography (MEG), these measures have been shown to correlate well with energy utilization sensitive BOLD fMRI. In this paper, we explore the existence of state changes in electrophysiological cortical activity that can occur independently of changes in averaged amplitude, source power or indices of metabolic rates. In addition, we demonstrate that such state changes can be described by applying a new measure of complexity, rank vector entropy (RVE), to source waveform estimates from beamformer-processed MEG. RVE is a non-parametric symbolic dynamic informational entropy measure that accommodates the wide dynamic range of measured brain signals while resolving its temporal variations. By representing the measurements by their rank values, RVE overcomes the problem of defining embedding space partitions without resorting to signal compression. This renders RVE-independent of absolute signal amplitude. In addition, this approach is robust, being relatively free of tunable parameters. We present examples of task-free and task-dependent MEG demonstrating that RVE provides new information by uncovering hidden dynamical structure in the apparent turbulent (or chaotic) dynamics of spontaneous cortical activity. PMID:23355820

  16. Complex oxides: Intricate disorder

    DOE PAGESBeta

    Uberuaga, Blas Pedro

    2016-05-01

    In this study, complex oxides such as pyrochlores have a myriad of potential technological applications, including as fast ion conductors and radiation-tolerant nuclear waste forms. They are also of interest for their catalytic and spin ice properties. Many of these functional properties are enabled by the atomic structure of the cation sublattices. Pyrochlores (A2B2O7) contain two different cations (A and B), typically a 3+ rare earth and a 4+ transition metal such as Hf, Zr, or Ti. The large variety of chemistries that can form pyrochlores leads to a rich space in which to search for exotic new materials. Furthermore,more » how cations order or disorder on their respective sublattices for a given chemical composition influences the functional properties of the oxide. For example, oxygen ionic conductivity is directly correlated with the level of cation disorder — the swapping of A and B cations1. Further, the resistance of these materials against amorphization has also been connected with the ability of the cations to disorder2, 3. These correlations between cation structure and functionality have spurred great interest in the structure of the cation sublattice under irradiation, with significant focus on the disordering mechanisms and disordered structure. Previous studies have found that, upon irradiation, pyrochlores often undergo an order-to-disorder transformation, in which the resulting structure is, from a diffraction point of view, indistinguishable from fluorite (AO2) (ref. 3). Shamblin et al. now reveal that the structure of disordered pyrochlore is more complicated than previously thought4.« less

  17. Species complexes in the Simuliidae*

    PubMed Central

    1978-01-01

    The recent discovery that Simulium damnosum in Africa is not a single species but a complex of sibling species has important implications for the epidemiology and control of onchocerciasis. This paper sets out the current situation with regard to classification within the S. damnosum complex and the smaller S. neavei group. The nomenclature of the S. damnosum complex and current morphological and enzyme electrophoretic methods of differentiating among sibling species are discussed. Finally, recommendations are made on priorities for future research. PMID:307447

  18. COMPLEXITY and the QGCW Project

    NASA Astrophysics Data System (ADS)

    Zichichi, Antonino

    2014-06-01

    The following sections are included: * Seven definitions of Complexity * Complexity exists at all scales * AFB phenomena from Beethoven to the Superworld * UEEC events, from Galilei up to SM&B * The two asymptotic limits: History and Science * The basic points on the correlation between Complexity and Predictions * The lesson needed for the future * From Planck to Complexity * Consequences for LHC: the QGCW project * Conclusions * The Platonic Grand Unification * The Platonic Supersymmetry * Examples of UEEC events in the construction of the SM&B * Open Problems in Subnuclear Physics * The ten challenges of Subnuclear Physics * References

  19. Complex Constructivism: A Theoretical Model of Complexity and Cognition

    ERIC Educational Resources Information Center

    Doolittle, Peter E.

    2014-01-01

    Education has long been driven by its metaphors for teaching and learning. These metaphors have influenced both educational research and educational practice. Complexity and constructivism are two theories that provide functional and robust metaphors. Complexity provides a metaphor for the structure of myriad phenomena, while constructivism…

  20. Sustainability, Complexity and Learning: Insights from Complex Systems Approaches

    ERIC Educational Resources Information Center

    Espinosa, A.; Porter, T.

    2011-01-01

    Purpose: The purpose of this research is to explore core contributions from two different approaches to complexity management in organisations aiming to improve their sustainability,: the Viable Systems Model (VSM), and the Complex Adaptive Systems (CAS). It is proposed to perform this by summarising the main insights each approach offers to…

  1. Forecasting in Complex Systems

    NASA Astrophysics Data System (ADS)

    Rundle, J. B.; Holliday, J. R.; Graves, W. R.; Turcotte, D. L.; Donnellan, A.

    2014-12-01

    Complex nonlinear systems are typically characterized by many degrees of freedom, as well as interactions between the elements. Interesting examples can be found in the areas of earthquakes and finance. In these two systems, fat tails play an important role in the statistical dynamics. For earthquake systems, the Gutenberg-Richter magnitude-frequency is applicable, whereas for daily returns for the securities in the financial markets are known to be characterized by leptokurtotic statistics in which the tails are power law. Very large fluctuations are present in both systems. In earthquake systems, one has the example of great earthquakes such as the M9.1, March 11, 2011 Tohoku event. In financial systems, one has the example of the market crash of October 19, 1987. Both were largely unexpected events that severely impacted the earth and financial systems systemically. Other examples include the M9.3 Andaman earthquake of December 26, 2004, and the Great Recession which began with the fall of Lehman Brothers investment bank on September 12, 2013. Forecasting the occurrence of these damaging events has great societal importance. In recent years, national funding agencies in a variety of countries have emphasized the importance of societal relevance in research, and in particular, the goal of improved forecasting technology. Previous work has shown that both earthquakes and financial crashes can be described by a common Landau-Ginzburg-type free energy model. These metastable systems are characterized by fat tail statistics near the classical spinodal. Correlations in these systems can grow and recede, but do not imply causation, a common source of misunderstanding. In both systems, a common set of techniques can be used to compute the probabilities of future earthquakes or crashes. In this talk, we describe the basic phenomenology of these systems and emphasize their similarities and differences. We also consider the problem of forecast validation and verification

  2. The Algebra of Complex Numbers.

    ERIC Educational Resources Information Center

    LePage, Wilbur R.

    This programed text is an introduction to the algebra of complex numbers for engineering students, particularly because of its relevance to important problems of applications in electrical engineering. It is designed for a person who is well experienced with the algebra of real numbers and calculus, but who has no experience with complex number…

  3. Complexity and Education: Vital Simultaneities

    ERIC Educational Resources Information Center

    Davis, Brent

    2008-01-01

    This article explores the place of complexity science within education and educational research. The discussion begins with the suggestion that educational research has a history of adopting interpretive frames from other domains with little adaptation. Complexity science is argued to compel a different sort of positioning, one that requires…

  4. Too Dumb for Complex Texts?

    ERIC Educational Resources Information Center

    Bauerlein, Mark

    2011-01-01

    High school students' lack of experience and practice with reading complex texts is a primary cause of their difficulties with college-level reading. Filling the syllabus with digital texts does little to address this deficiency. Complex texts demand three dispositions from readers: a willingness to probe works characterized by dense meanings, the…

  5. Understanding and Teaching Complex Texts

    ERIC Educational Resources Information Center

    Fisher, Douglas; Frey, Nancy

    2014-01-01

    Teachers in today's classrooms struggle every day to design instructional interventions that would build students' reading skills and strategies in order to ensure their comprehension of complex texts. Text complexity can be determined in both qualitative and quantitative ways. In this article, the authors describe various innovative…

  6. Amphotericin B Lipid Complex Injection

    MedlinePlus

    Amphotericin B lipid complex injection is used to treat serious, possibly life-threatening fungal infections in people who did not respond or are ... tolerate conventional amphotericin B therapy. Amphotericin B lipid complex injection is in a class of medications called ...

  7. Teacher Knowledge: A Complex Tapestry

    ERIC Educational Resources Information Center

    Adoniou, Misty

    2015-01-01

    Teachers need to know a great deal, in many areas and in multiple ways. Teacher knowledge is a complex tapestry, and teachers must successfully weave the multiple threads. In this article, I present a conceptualisation of teacher knowledge that provides a framework for describing the complexity of teacher knowledge. The framework describes three…

  8. Improve Reading with Complex Texts

    ERIC Educational Resources Information Center

    Fisher, Douglas; Frey, Nancy

    2015-01-01

    The Common Core State Standards have cast a renewed light on reading instruction, presenting teachers with the new requirements to teach close reading of complex texts. Teachers and administrators should consider a number of essential features of close reading: They are short, complex texts; rich discussions based on worthy questions; revisiting…

  9. The Complexity of Language Learning

    ERIC Educational Resources Information Center

    Nelson, Charles

    2011-01-01

    This paper takes a complexity theory approach to looking at language learning, an approach that investigates how language learners adapt to and interact with people and their environment. Based on interviews with four graduate students, it shows how complexity theory can help us understand both the situatedness of language learning and also…

  10. Sun-climate complexity linking.

    PubMed

    West, B J; Grigolini, P

    2008-02-29

    It is known that Earth's short-term temperature anomalies share the same complexity index mu as solar flares. We show that this property is not accidental and is a consequence of the phenomenon of information transfer based on the crucial role of non-Poisson renewal events in complex networks. PMID:18352672

  11. Monotone measures of statistical complexity

    NASA Astrophysics Data System (ADS)

    Rudnicki, Łukasz; Toranzo, Irene V.; Sánchez-Moreno, Pablo; Dehesa, Jesús S.

    2016-01-01

    We introduce and discuss the notion of monotonicity for the complexity measures of general probability distributions, patterned after the resource theory of quantum entanglement. Then, we explore whether this property is satisfied by the three main intrinsic measures of complexity (Crámer-Rao, Fisher-Shannon, LMC) and some of their generalizations.

  12. A Simple Explanation of Complexation

    ERIC Educational Resources Information Center

    Elliott, J. Richard

    2010-01-01

    The topics of solution thermodynamics, activity coefficients, and complex formation are introduced through computational exercises and sample applications. The presentation is designed to be accessible to freshmen in a chemical engineering computations course. The MOSCED model is simplified to explain complex formation in terms of hydrogen…

  13. Earthquake cycles in complex geometries

    NASA Astrophysics Data System (ADS)

    Romanet, Pierre; Bhat, Harsha; Madariaga, Raul

    2016-04-01

    Our understanding of earthquake cycles, from a modelling perspective, comes mainly from theoretical, and numerical, work on a single straight fault. However, natural fault systems are geometrically complex. Modelling complex fault geometry (bends, kinks and multiple faults) is in itself a challenge as it is computationally intensive. To overcome this difficulty, we appeal to the Fast Multipole Method which was developed in the context of modelling N-body problems. This method is then used to model the quasi-dynamic response of multiple faults, with complex geometries, that are governed by rate and state friction laws. Our preliminary findings tell us that when stress interaction between faults, due to complex geometry, is accounted then even strongly rate-weakening faults (a-b)<0 show a complex spectrum of slow slip and dynamic ruptures.

  14. The Evolution of Complex Life

    NASA Technical Reports Server (NTRS)

    Billingham, John

    1989-01-01

    In considering the probabilities that intelligent life might exist elsewhere in the Universe, it is important to ask questions about the factors governing the emergence of complex living organisms in the context of evolutionary biology, planetary environments and events in space. Two important problems arise. First, what can be learned about the general laws governing the evolution of complex life anywhere in space by studying its history on the Earth? Second, how is the evolution of complex life affected by events in space? To address these problems, a series of Science Workshops on the Evolution of Complex Life was held at the Ames Research Center. Included in this paper are highlights of those workshops, with particular emphasis on the first question, namely the evolution of complex extraterrestrial life.

  15. Complex-extended Bohmian mechanics.

    PubMed

    Chou, Chia-Chun; Wyatt, Robert E

    2010-04-01

    Complex-extended Bohmian mechanics is investigated by analytically continuing the wave function in polar form into the complex plane. We derive the complex-extended version of the quantum Hamilton-Jacobi equation and the continuity equation in Bohmian mechanics. Complex-extended Bohmian mechanics recovers the standard real-valued Bohmian mechanics on the real axis. The trajectories on the real axis are in accord with the standard real-valued Bohmian trajectories. The trajectories launched away from the real axis never intersect the real axis, and they display symmetry with respect to the real axis. Trajectories display hyperbolic deflection around nodes of the wave function in the complex plane. PMID:20387916

  16. Ternary complexes in analytical chemistry.

    PubMed

    Babko, A K

    1968-08-01

    Reactions between a complex AB and a third component C do not always proceed by a displacement mechanism governed by the energy difference of the chemical bonds A-B and A-C. The third component often becomes part of the complex, forming a mixed co-ordination sphere or ternary complex. The properties of this ternary complex ABC are not additive functions of the properties of AB and AC. Such reactions are important in many methods in analytical chemistry, particularly in photometric analysis, extractive separation, masking, etc. The general properties of the four basic types of ternary complex are reviewed and examples given. The four types comprise the systems (a) metal ion, electronegative ligand, organic base, (b) one metal ion, two different electronegative ligands, (c) ternary heteropoly acids, and (d) two different metal ions, one ligand. PMID:18960358

  17. Modelling of Complex Plasmas

    NASA Astrophysics Data System (ADS)

    Akdim, Mohamed Reda

    2003-09-01

    Nowadays plasmas are used for various applications such as the fabrication of silicon solar cells, integrated circuits, coatings and dental cleaning. In the case of a processing plasma, e.g. for the fabrication of amorphous silicon solar cells, a mixture of silane and hydrogen gas is injected in a reactor. These gases are decomposed by making a plasma. A plasma with a low degree of ionization (typically 10_5) is usually made in a reactor containing two electrodes driven by a radio-frequency (RF) power source in the megahertz range. Under the right circumstances the radicals, neutrals and ions can react further to produce nanometer sized dust particles. The particles can stick to the surface and thereby contribute to a higher deposition rate. Another possibility is that the nanometer sized particles coagulate and form larger micron sized particles. These particles obtain a high negative charge, due to their large radius and are usually trapped in a radiofrequency plasma. The electric field present in the discharge sheaths causes the entrapment. Such plasmas are called dusty or complex plasmas. In this thesis numerical models are presented which describe dusty plasmas in reactive and nonreactive plasmas. We started first with the development of a simple one-dimensional silane fluid model where a dusty radio-frequency silane/hydrogen discharge is simulated. In the model, discharge quantities like the fluxes, densities and electric field are calculated self-consistently. A radius and an initial density profile for the spherical dust particles are given and the charge and the density of the dust are calculated with an iterative method. During the transport of the dust, its charge is kept constant in time. The dust influences the electric field distribution through its charge and the density of the plasma through recombination of positive ions and electrons at its surface. In the model this process gives an extra production of silane radicals, since the growth of dust is

  18. Thermal diffusivity of Americium mononitride from 373 to 1473 K

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Takano, Masahide; Itoh, Akinori; Akabori, Mitsuo; Minato, Kazuo; Kizaki, Minoru

    2006-09-01

    The thermal diffusivity of AmN was measured from 373 to 1473 K by a laser flash method. The AmN sample was prepared from AmO 2 by the carbothermic reduction. The obtained AmN product was grinded and pressed at about 400 MPa to form a disk. The disk was sintered at 1823 K for 10 h in flowing N 2 + 4%H 2 gas. The thermal diffusivity slightly decreased from 3.4 × 10 -6 to 2.8 × 10 -6 m 2/s with increasing temperature. As the specific heat capacity of AmN was not available in literature, the thermal conductivity of AmN was tentatively estimated from the measured thermal diffusivity, bulk density and the specific heat capacity of PuN. It was found that the thermal conductivity of AmN slightly increased with temperature. The thermal conductivity of AmN corrected to 100%TD was found to be smaller than those of UN, NpN and PuN, whereas that of AmN was larger than those of UO 2 and (U 0.8Pu 0.2)O 2.

  19. Americium Oxide Surrogates for European Radioisotope Power Systems.

    NASA Astrophysics Data System (ADS)

    Watkinson, E. J.; Ambrosi, R. M.; Williams, H. R.; Sarsfield, M. J.; Tinsley, T. P.; Stephenson, K.

    2014-07-01

    The European space nuclear power programme comprises two main research areas: fuel source development and the development of conversion technologies, which are thermoelectric or dynamic, for electricity production. This abstract addresses the former.

  20. Comparative behavior of plutonium and americium in the equatorial Pacific

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Jokela, T.A.; Brunk, J.L.; Eagle, R.J.

    1983-01-01

    Inventories of /sup 239 +240/Pu and /sup 241/Am greatly in excess of global fallout levels persist in the benthic environments of Bikini and Enewetak Atolls. The amount of /sup 239 +240/Pu mobilized to solution at the atolls can be predicted from a distribution coefficient K/sub d/ of 2.3 x 10/sup 5/ and the mean sediment concentrations. The mobilized /sup 239 +240/Pu has solute-like characteristics and different valence states coexist in solution - the largest fraction of the soluble plutonium is in an oxidized form (+V,VI). The adsorption of plutonium to sediments is not completely reversible because of changes that occur in the relative amounts of the mixed oxidation states in solution with time. Characteristics of /sup 239 +240/Pu described at one location may not necessarily describe its behavior elsewhere. The relative amounts of /sup 241/Am to /sup 239 +240/Pu may be altered in future years because of mobilization and radiological decay.

  1. Plutonium and americium behavior in coral atoll environments

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Jokela, T.A.; Brunk, J.L.; Eagle, R.J.

    1984-02-01

    Inventories of /sup 239 +240/Pu and /sup 241/Am greatly in excess of global fallout levels persist in the benthic environments of Bikini and Enewetak Atolls. Quantities of /sup 239 +240/Pu and lesser amounts of /sup 241/Am are continuously mobilizing from these sedimentary reservoirs. The amount of /sup 239 +240/Pu mobilized to solution at any time represents 0.08 to 0.09% of the sediment inventories to a depth of 16 cm. The mobilized /sup 239 +240/Pu has solute-like characteristics and different valence states coexist in solution - the largest fraction of the soluble plutonium is in an oxidized form (+V,VI). The adsorption of plutonium to sediments is not completely reversible because of changes that occur in the relative amounts of the mixed oxidation states in solution with time. Further, any characteristics of /sup 239 +240/Pu described at one location may not necessarily be relevant in describing its behavior elsewhere following mobilization and migration. The relative amounts of /sup 241/Am to /sup 239 +240/Pu in the sedimentary deposits at Enewetak and Bikini may be altered in future years because of mobilization and radiological decay. Mobilization of /sup 239 +240/Pu is not a process unique to these atolls, and quantities in solution derived from sedimentary deposits can be found at other global sites. These studies in the equatorial Pacific have significance in assessing the long-term behavior of the transuranics in any marine environment. 22 references, 1 figure, 13 tables.

  2. Property Data for Simulated Americium/Curium Glasses

    SciTech Connect

    Riley, B.J.; Smith, D.E.; Peeler, D.K.; Reamer, I.A.; Vienna, J.D.; Schweiger, M.J.

    1999-10-20

    The authors studied the properties of mixed lanthanide-alumino-borosilicate glasses. Fifty-five glasses were designed to augment a previous, Phase I, study by systematically varying the composition of Ln{sub 2}O{sub 3} and the concentrations of Ln{sub 2}O{sub 3}, SiO{sub 2}, B{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, and SrO in glass. These glasses were designed and fabricated at the Savannah River Technology Center and tested at the Pacific Northwest National Laboratory. The properties measured include the high-temperature viscosity ({eta}) as a function of temperature (T) and the liquidus temperature (T{sub L}) of Phase II test glasses.

  3. Americium As A Potential Power Source For Space Missions

    NASA Astrophysics Data System (ADS)

    Cordingley, Leon; Rice, Tom; Sarsfield, Mark J.; Stephenson, Keith; Tinsley, Tim

    2011-10-01

    Electrical power sources used in outer planet missions are a key enabling technology for data acquisition and communications. Power sources generate electricity from the thermal energy from alpha decay of the radioisotope 238Pu via thermoelectric conversion. Production of 238Pu requires specialist facilities including a nuclear reactor and reprocessing plants that are expensive to build and operate, so naturally, a more economical alternative is attractive to the industry. Within Europe 241Am is a feasible alternative to 238Pu that can provide a heat source for radioisotope thermoelectric generators (RTGs) and radioisotope heating units (RHUs). Whilst there are implications associated with the differences between 238Pu and 241Am, these technological challenges are surmountable.

  4. Cancer complexity and radiation protection.

    PubMed

    Mossman, Kenneth L

    2014-07-01

    Management of radiological risks typically encountered in environmental and occupational settings is challenging because of uncertainties in the magnitude of the risks and the benefits of risk reduction. In practice, radiation dose instead of risk is measured. However, the relationship between dose and risk is not straightforward because cancer (the major health effect of concern at low doses) is a disease of complexity. Risks at small doses (defined as less than 100 mSv) can never be known exactly because of the inherent uncertainties in cancer as a complex disease. Tumors are complex because of the nonlinear interactions that occur among tumor cells and between the tumor and its local tissue environment. This commentary reviews evidence for cancer complexity and what complexity means for radiation protection. A complexity view of cancer does not mean we must abandon our current system of protection. What it does mean is that complexity requires new ways of thinking about control of cancer-the ideas that cancers can occur without cause, cancers behave unpredictably, and calculated cancer risks following small doses of radiation are highly uncertain. PMID:24849905

  5. Kinetics of actinide complexation reactions

    SciTech Connect

    Nash, K.L.; Sullivan, J.C.

    1997-09-01

    Though the literature records extensive compilations of the thermodynamics of actinide complexation reactions, the kinetics of complex formation and dissociation reactions of actinide ions in aqueous solutions have not been extensively investigated. In light of the central role played by such reactions in actinide process and environmental chemistry, this situation is somewhat surprising. The authors report herein a summary of what is known about actinide complexation kinetics. The systems include actinide ions in the four principal oxidation states (III, IV, V, and VI) and complex formation and dissociation rates with both simple and complex ligands. Most of the work reported was conducted in acidic media, but a few address reactions in neutral and alkaline solutions. Complex formation reactions tend in general to be rapid, accessible only to rapid-scan and equilibrium perturbation techniques. Complex dissociation reactions exhibit a wider range of rates and are generally more accessible using standard analytical methods. Literature results are described and correlated with the known properties of the individual ions.

  6. The complexity of anatomical systems

    PubMed Central

    Grizzi, Fabio; Chiriva-Internati, Maurizio

    2005-01-01

    Background The conception of anatomical entities as a hierarchy of infinitely graduated forms and the increase in the number of observed anatomical sub-entities and structural variables has generated a growing complexity, thus highlighting new properties of organised biological matter. Results (1) Complexity is so pervasive in the anatomical world that it has come to be considered as a primary characteristic of anatomical systems. (2) Anatomical entities, when viewed at microscopic as well as macroscopic level of observation, show a different degree of complexity. (3) Complexity can reside in the structure of the anatomical system (having many diverse parts with varying interactions or an intricate architecture) or in its behaviour. Often complexity in structure and behaviour go together. (4) Complex systems admit many descriptions (ways of looking at the system) each of which is only partially true. Each way of looking at a complex system requires its own description, its own mode of analysis and its own breaking down of the system in different parts; (5) Almost all the anatomical entities display hierarchical forms: their component structures at different spatial scales or their process at different time scales are related to each other. Conclusion The need to find a new way of observing and measuring anatomical entities, and objectively quantifying their different structural changes, prompted us to investigate the non-Euclidean geometries and the theories of complexity, and to apply their concepts to human anatomy. This attempt has led us to reflect upon the complex significance of the shape of an observed anatomical entity. Its changes have been defined in relation to variations in its status: from a normal (i.e. natural) to a pathological or altered state introducing the concepts of kinematics and dynamics of anatomical forms, speed of their changes, and that of scale of their observation. PMID:16029490

  7. Actinide cation-cation complexes

    SciTech Connect

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO{sub 2}{sup +}) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO{sub 2}{sup +}; therefore, cation-cation complexes indicate something unique about AnO{sub 2}{sup +} cations compared to actinide cations in general. The first cation-cation complex, NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO{sub 2}{sup +} species, the cation-cation complexes of NpO{sub 2}{sup +} have been studied most extensively while the other actinides have not. The only PuO{sub 2}{sup +} cation-cation complexes that have been studied are with Fe{sup 3+} and Cr{sup 3+} and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, NpO{sub 2}{sup +}{center_dot}Th{sup 4+}, PuO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, and PuO{sub 2}{sup +}{center_dot}Th{sup 4+} at an ionic strength of 6 M using LIPAS are 2.4 {plus_minus} 0.2, 1.8 {plus_minus} 0.9, 2.2 {plus_minus} 1.5, and {approx}0.8 M{sup {minus}1}.

  8. SDO: Complex Mass of Plasma

    NASA Video Gallery

    A small, but complex mass of solar material gyrated and spun about over the course of 40 hours above the surface of the sun on Sept. 1-3, 2015. It was stretched and pulled back and forth by powerfu...

  9. Complex Hydrides for Hydrogen Storage

    SciTech Connect

    Slattery, Darlene; Hampton, Michael

    2003-03-10

    This report describes research into the use of complex hydrides for hydrogen storage. The synthesis of a number of alanates, (AIH4) compounds, was investigated. Both wet chemical and mechano-chemical methods were studied.

  10. The future of complexity engineering

    NASA Astrophysics Data System (ADS)

    Frei, Regina; Di Marzo Serugendo, Giovanna

    2012-06-01

    Complexity Engineering encompasses a set of approaches to engineering systems which are typically composed of various interacting entities often exhibiting self-* behaviours and emergence. The engineer or designer uses methods that benefit from the findings of complexity science and often considerably differ from the classical engineering approach of "divide and conquer". This article provides an overview on some very interdisciplinary and innovative research areas and projects in the field of Complexity Engineering, including synthetic biology, chemistry, artificial life, self-healing materials and others. It then classifies the presented work according to five types of nature-inspired technology, namely: (1) using technology to understand nature, (2) nature-inspiration for technology, (3) using technology on natural systems, (4) using biotechnology methods in software engineering, and (5) using technology to model nature. Finally, future trends in Complexity Engineering are indicated and related risks are discussed.

  11. Making the Tent Function Complex

    ERIC Educational Resources Information Center

    Sprows, David J.

    2010-01-01

    This note can be used to illustrate to the student such concepts as periodicity in the complex plane. The basic construction makes use of the Tent function which requires only that the student have some working knowledge of binary arithmetic.

  12. Volatile hexafluoroacetylacetonate complexes of einsteinium

    SciTech Connect

    Fedoseev, E.V.; Aizenberg, M.I.; Travnikov, S.S.; Davydov, A.V.; Myasoedov, B.F.

    1988-07-01

    Volatile hexafluoroacetylacetonate complexes of einsteinium have been synthesized. Their sublimation and thermochromatographic behavior in the presence of free ..beta..-diketone were studied. The reaction of einsteinium di- and tri-chlorides with hexafluoroacetylacetone vapor is discussed.

  13. Differential Complexes in Continuum Mechanics

    NASA Astrophysics Data System (ADS)

    Angoshtari, Arzhang; Yavari, Arash

    2015-04-01

    We study some differential complexes in continuum mechanics that involve both symmetric and non-symmetric second-order tensors. In particular, we show that the tensorial analogue of the standard grad-curl-div complex can simultaneously describe the kinematics and the kinetics of motion of a continuum. The relation between this complex and the de Rham complex allows one to readily derive the necessary and sufficient conditions for the compatibility of displacement gradient and the existence of stress functions on non-contractible bodies.We also derive the local compatibility equations in terms of the Green deformation tensor for motions of 2D and 3D bodies, and shells in curved ambient spaces with constant curvatures.

  14. Algorithmic complexity of a protein

    NASA Astrophysics Data System (ADS)

    Dewey, T. Gregory

    1996-07-01

    The information contained in a protein's amino acid sequence dictates its three-dimensional structure. To quantitate the transfer of information that occurs in the protein folding process, the Kolmogorov information entropy or algorithmic complexity of the protein structure is investigated. The algorithmic complexity of an object provides a means of quantitating its information content. Recent results have indicated that the algorithmic complexity of microstates of certain statistical mechanical systems can be estimated from the thermodynamic entropy. In the present work, it is shown that the algorithmic complexity of a protein is given by its configurational entropy. Using this result, a quantitative estimate of the information content of a protein's structure is made and is compared to the information content of the sequence. Additionally, the mutual information between sequence and structure is determined. It is seen that virtually all the information contained in the protein structure is shared with the sequence.

  15. Mathematicians, Attributional Complexity, and Gender

    NASA Astrophysics Data System (ADS)

    Stalder, Daniel R.

    Given indirect indications in sex role and soda! psychology research that mathematical-deductive reasoning may negatively relate to social acuity, Study 1 investigated whether mathematicians were less attributionally complex than nonmathematicians. Study 1 administered the Attributional Complexity Scale, a measure of social acuity, to female and male faculty members and graduate students in four Midwestern schools. Atlrihutional complexity (AC) is the ability and motivation to give complex explanations for behavior. Study 1 found a significant interaction between field and gender. Only among women did mathematicians score lower on AC. In addition, an established gender difference in AC (that women score higher than men) was present only among nonmathematicians. Studies 2 and 3 offered some preliminary support for the possibility that it is generally female students who score tow on AC who aspire to he mathematicians and for the underlying view that female students' perceived similarity to mathematicians can influence their vocational choices.

  16. Complex Topographic Feature Ontology Patterns

    USGS Publications Warehouse

    Varanka, Dalia E.; Jerris, Thomas J.

    2015-01-01

    Semantic ontologies are examined as effective data models for the representation of complex topographic feature types. Complex feature types are viewed as integrated relations between basic features for a basic purpose. In the context of topographic science, such component assemblages are supported by resource systems and found on the local landscape. Ontologies are organized within six thematic modules of a domain ontology called Topography that includes within its sphere basic feature types, resource systems, and landscape types. Context is constructed not only as a spatial and temporal setting, but a setting also based on environmental processes. Types of spatial relations that exist between components include location, generative processes, and description. An example is offered in a complex feature type ‘mine.’ The identification and extraction of complex feature types are an area for future research.

  17. Recent developments in complex scaling

    SciTech Connect

    Rescigno, T.N.

    1980-12-15

    Some recent developments in the use of complex basis function techniques to study resonance as well as certain types of non-resonant, scattering phenomena are discussed. Complex scaling techniques and other closely related methods have continued to attract the attention of computational physicists and chemists and have now reached a point of development where meaningful calculations on many-electron atoms and molecules are beginning to appear feasible.

  18. Supramolecular complexations of natural products.

    PubMed

    Schneider, Hans-Jörg; Agrawal, Pawan; Yatsimirsky, Anatoly K

    2013-08-21

    Complexations of natural products with synthetic receptors as well as the use of natural products as host compounds are reviewed, with an emphasis on possible practical uses or on biomedical significance. Applications such as separation, sensing, enzyme monitoring, and protection of natural drugs are first outlined. We then discuss examples of complexes with all important classes of natural compounds, such as amino acids, peptides, nucleosides/nucleotides, carbohydrates, catecholamines, flavonoids, terpenoids/steroids, alkaloids, antibiotics and toxins. PMID:23703643

  19. Complexity, action, and black holes

    DOE PAGESBeta

    Brown, Adam R.; Roberts, Daniel A.; Susskind, Leonard; Swingle, Brian; Zhao, Ying

    2016-04-18

    In an earlier paper "Complexity Equals Action" we conjectured that the quantum computational complexity of a holographic state is given by the classical action of a region in the bulk (the `Wheeler-DeWitt' patch). We provide calculations for the results quoted in that paper, explain how it fits into a broader (tensor) network of ideas, and elaborate on the hypothesis that black holes are the fastest computers in nature.

  20. Tuberous Sclerosis Complex Renal Disease

    PubMed Central

    Dixon, Bradley P.; Hulbert, John C.; Bissler, John J.

    2010-01-01

    Although not as common as other genetic renal diseases such as autosomal dominant polycystic kidney disease, patients with tuberous sclerosis complex frequently have significant renal involvement. Recent revelations in the cell biology of these renal disease manifestations as well as effective therapies for tuberous sclerosis complex-related renal issues have heralded hope of improved renal survival and improved quality of life for the TSC patient. This review specifically addresses some of the major renal manifestations of this disease. PMID:21071977

  1. Evolving Complexity, Cognition, and Consciousness

    NASA Astrophysics Data System (ADS)

    Liljenström, H.

    2012-12-01

    All through the history of the universe there is an apparent tendency for increasing complexity, with the organization of matter in evermore elaborate and interactive systems. The living world in general, and the human brain in particular, provides the highest complexity known. It seems obvious that all of this complexity must be the result of physical, chemical and biological evolution, but it was only with Darwin that we began to get a scientific understanding of biological evolution. Darwinian principles are guiding in our understanding of such complex systems as the nervous system, but also for the evolution of human society and technology. Living organisms have to survive in a complex and changing environment. This implies response and adaption to environmental events and changes at several time scales. The interaction with the environment depends on the present state of the organism, as well as on previous experiences stored in its molecular and cellular structures. At a longer time scale, organisms can adapt to slow environmental changes, by storing information in the genetic material carried over from generation to generation. This phylogenetic learning is complemented by ontogenetic learning, which is adaptation at a shorter time scale, occuring in non-genetic structures. The evolution of a nervous system is a major transition in biological evolution and allows for an increasing capacity for information storage and processing, increasing chances of survival. Such neural knowledge processing, cognition, shows the same principal features as nonneural adaptive processes. Similarly, consciousness might appear, to different degrees, at different stages in evolution. Both cognition and consciousness depends critically on the organization and complexity of the organism. In this presentation, I will briefly discuss general principles for evolution of complexity, focussing on the evolution of the nervous system, which provides organisms with ever increasing

  2. Complexity, action, and black holes

    NASA Astrophysics Data System (ADS)

    Brown, Adam R.; Roberts, Daniel A.; Susskind, Leonard; Swingle, Brian; Zhao, Ying

    2016-04-01

    Our earlier paper "Complexity Equals Action" conjectured that the quantum computational complexity of a holographic state is given by the classical action of a region in the bulk (the "Wheeler-DeWitt" patch). We provide calculations for the results quoted in that paper, explain how it fits into a broader (tensor) network of ideas, and elaborate on the hypothesis that black holes are the fastest computers in nature.

  3. Goldstone Deep Space Communication Complex

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Three 34m (110 ft.) diameter Beam Waveguide antennas located at the Goldstone Deep Space Communications Complex, situated in the Mojave Desert in California. This is one of three complexes which comprise NASA's Deep Space Network (DSN). The DSN provides radio communications for all of NASA's interplanetary spacecraft and is also utilized for radio astronomy and radar observations of the solar system and the universe.

  4. Complex Hybrid Inflation and Baryogenesis

    SciTech Connect

    Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo

    2007-04-20

    We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated with the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vacuum expectation value of the waterfall field, which is well constrained by diverse cosmological observations.

  5. Computerized measures of visual complexity.

    PubMed

    Machado, Penousal; Romero, Juan; Nadal, Marcos; Santos, Antonino; Correia, João; Carballal, Adrián

    2015-09-01

    Visual complexity influences people's perception of, preference for, and behaviour toward many classes of objects, from artworks to web pages. The ability to predict people's impression of the complexity of different kinds of visual stimuli holds, therefore, great potential for many domains, basic and applied. Here we use edge detection operations and several image metrics based on image compression error and Zipf's law to estimate the visual complexity of images. The experiments involved 800 images, each previously rated by thirty participants on perceived complexity. In a first set of experiments we analysed the correlation of individual features with the average human response, obtaining correlations up to rs = .771. In a second set of experiments we employed Machine Learning techniques to predict the average visual complexity score attributed by humans to each stimuli. The best configurations obtained a correlation of rs = .832. The average prediction error of the Machine Learning system over the set of all stimuli was .096 in a normalized 0 to 1 interval, showing that it is possible to predict, with high accuracy human responses. Overall, edge density and compression error were the strongest predictors of human complexity ratings. PMID:26164647

  6. Conforming Morse-Smale Complexes

    SciTech Connect

    Gyulassy, Attila; Gunther, David; Levine, Joshua A.; Tierny, Julien; Pascucci, Valerio

    2014-08-11

    Morse-Smale (MS) complexes have been gaining popularity as a tool for feature-driven data analysis and visualization. However, the quality of their geometric embedding and the sole dependence on the input scalar field data can limit their applicability when expressing application-dependent features. In this paper we introduce a new combinatorial technique to compute an MS complex that conforms to both an input scalar field and an additional, prior segmentation of the domain. The segmentation constrains the MS complex computation guaranteeing that boundaries in the segmentation are captured as separatrices of the MS complex. We demonstrate the utility and versatility of our approach with two applications. First, we use streamline integration to determine numerically computed basins/mountains and use the resulting segmentation as an input to our algorithm. This strategy enables the incorporation of prior flow path knowledge, effectively resulting in an MS complex that is as geometrically accurate as the employed numerical integration. Our second use case is motivated by the observation that often the data itself does not explicitly contain features known to be present by a domain expert. We introduce edit operations for MS complexes so that a user can directly modify their features while maintaining all the advantages of a robust topology-based representation.

  7. "Computational Modeling of Actinide Complexes"

    SciTech Connect

    Balasubramanian, K

    2007-03-07

    We will present our recent studies on computational actinide chemistry of complexes which are not only interesting from the standpoint of actinide coordination chemistry but also of relevance to environmental management of high-level nuclear wastes. We will be discussing our recent collaborative efforts with Professor Heino Nitsche of LBNL whose research group has been actively carrying out experimental studies on these species. Computations of actinide complexes are also quintessential to our understanding of the complexes found in geochemical, biochemical environments and actinide chemistry relevant to advanced nuclear systems. In particular we have been studying uranyl, plutonyl, and Cm(III) complexes are in aqueous solution. These studies are made with a variety of relativistic methods such as coupled cluster methods, DFT, and complete active space multi-configuration self-consistent-field (CASSCF) followed by large-scale CI computations and relativistic CI (RCI) computations up to 60 million configurations. Our computational studies on actinide complexes were motivated by ongoing EXAFS studies of speciated complexes in geo and biochemical environments carried out by Prof Heino Nitsche's group at Berkeley, Dr. David Clark at Los Alamos and Dr. Gibson's work on small actinide molecules at ORNL. The hydrolysis reactions of urnayl, neputyl and plutonyl complexes have received considerable attention due to their geochemical and biochemical importance but the results of free energies in solution and the mechanism of deprotonation have been topic of considerable uncertainty. We have computed deprotonating and migration of one water molecule from the first solvation shell to the second shell in UO{sub 2}(H{sub 2}O){sub 5}{sup 2+}, UO{sub 2}(H{sub 2}O){sub 5}{sup 2+}NpO{sub 2}(H{sub 2}O){sub 6}{sup +}, and PuO{sub 2}(H{sub 2}O){sub 5}{sup 2+} complexes. Our computed Gibbs free energy(7.27 kcal/m) in solution for the first time agrees with the experiment (7.1 kcal

  8. Restricted Complexity Framework for Nonlinear Adaptive Control in Complex Systems

    SciTech Connect

    Williams, Rube B.

    2004-02-04

    Control law adaptation that includes implicit or explicit adaptive state estimation, can be a fundamental underpinning for the success of intelligent control in complex systems, particularly during subsystem failures, where vital system states and parameters can be impractical or impossible to measure directly. A practical algorithm is proposed for adaptive state filtering and control in nonlinear dynamic systems when the state equations are unknown or are too complex to model analytically. The state equations and inverse plant model are approximated by using neural networks. A framework for a neural network based nonlinear dynamic inversion control law is proposed, as an extrapolation of prior developed restricted complexity methodology used to formulate the adaptive state filter. Examples of adaptive filter performance are presented for an SSME simulation with high pressure turbine failure to support extrapolations to adaptive control problems.

  9. Restricted Complexity Framework for Nonlinear Adaptive Control in Complex Systems

    NASA Astrophysics Data System (ADS)

    Williams, Rube B.

    2004-02-01

    Control law adaptation that includes implicit or explicit adaptive state estimation, can be a fundamental underpinning for the success of intelligent control in complex systems, particularly during subsystem failures, where vital system states and parameters can be impractical or impossible to measure directly. A practical algorithm is proposed for adaptive state filtering and control in nonlinear dynamic systems when the state equations are unknown or are too complex to model analytically. The state equations and inverse plant model are approximated by using neural networks. A framework for a neural network based nonlinear dynamic inversion control law is proposed, as an extrapolation of prior developed restricted complexity methodology used to formulate the adaptive state filter. Examples of adaptive filter performance are presented for an SSME simulation with high pressure turbine failure to support extrapolations to adaptive control problems.

  10. Diversity of parasite complex II.

    PubMed

    Harada, Shigeharu; Inaoka, Daniel Ken; Ohmori, Junko; Kita, Kiyoshi

    2013-05-01

    Parasites have developed a variety of physiological functions necessary for completing at least part of their life cycles in the specialized environments of surrounding the parasites in the host. Regarding energy metabolism, which is essential for survival, parasites adapt to the low oxygen environment in mammalian hosts by using metabolic systems that are very different from those of the hosts. In many cases, the parasite employs aerobic metabolism during the free-living stage outside the host but undergoes major changes in developmental control and environmental adaptation to switch to anaerobic energy metabolism. Parasite mitochondria play diverse roles in their energy metabolism, and in recent studies of the parasitic nematode, Ascaris suum, the mitochondrial complex II plays an important role in anaerobic energy metabolism of parasites inhabiting hosts by acting as a quinol-fumarate reductase. In Trypanosomes, parasite complex II has been found to have a novel function and structure. Complex II of Trypanosoma cruzi is an unusual supramolecular complex with a heterodimeric iron-sulfur subunit and seven additional non-catalytic subunits. The enzyme shows reduced binding affinities for both substrates and inhibitors. Interestingly, this structural organization is conserved in all trypanosomatids. Since the properties of complex II differ across a wide range of parasites, this complex is a potential target for the development of new chemotherapeutic agents. In this regard, structural information on the target enzyme is essential for the molecular design of drugs. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease. PMID:23333273

  11. Complexity matching in neural networks

    NASA Astrophysics Data System (ADS)

    Usefie Mafahim, Javad; Lambert, David; Zare, Marzieh; Grigolini, Paolo

    2015-01-01

    In the wide literature on the brain and neural network dynamics the notion of criticality is being adopted by an increasing number of researchers, with no general agreement on its theoretical definition, but with consensus that criticality makes the brain very sensitive to external stimuli. We adopt the complexity matching principle that the maximal efficiency of communication between two complex networks is realized when both of them are at criticality. We use this principle to establish the value of the neuronal interaction strength at which criticality occurs, yielding a perfect agreement with the adoption of temporal complexity as criticality indicator. The emergence of a scale-free distribution of avalanche size is proved to occur in a supercritical regime. We use an integrate-and-fire model where the randomness of each neuron is only due to the random choice of a new initial condition after firing. The new model shares with that proposed by Izikevich the property of generating excessive periodicity, and with it the annihilation of temporal complexity at supercritical values of the interaction strength. We find that the concentration of inhibitory links can be used as a control parameter and that for a sufficiently large concentration of inhibitory links criticality is recovered again. Finally, we show that the response of a neural network at criticality to a harmonic stimulus is very weak, in accordance with the complexity matching principle.

  12. Chemical complexity in galactic nuclei

    NASA Astrophysics Data System (ADS)

    Martin-Pintado, Jesus

    2007-12-01

    In recent years our knowledge of the chemical complexity in the nuclei of galaxies has dramatically changed. Recent observations of the nucleus of the Milky Way, of the starburst galaxy NGC253 and of the ultraluminous infrared galaxy (ULIRG) Arp220 have shown large abundance of complex organic molecules believed to be formed on grains. The Galactic center appears to be the largest repository of complex organic molecule like aldehydes and alcohols in the galaxy. We also measure large abundance of methanol in starburst galaxies and in ULIRGs suggesting that complex organic molecules are also efficiently produced in the central region of galaxies with strong star formation activity. From the systematic observational studies of molecular abundance in regions dominated by different heating processes like shocks, UV radiation, X-rays and cosmic rays in the center of the Milky Way, we are opening the possibility of using chemistry as a diagnostic tool to study the highly obscured regions of galactic centers. The templates found in the nucleus of the Milky Way will be used to establish the main mechanisms driving the heating and the chemistry of the molecular clouds in galaxies with different type of activity. The role of grain chemistry in the chemical complexity observed in the center of galaxies will be also briefly discussed.

  13. Metal complex interactions with DNA.

    PubMed

    Pages, Benjamin J; Ang, Dale L; Wright, Elisé P; Aldrich-Wright, Janice R

    2015-02-28

    Increasing numbers of DNA structures are being revealed using biophysical, spectroscopic and genomic methods. The diversity of transition metal complexes is also growing, as the unique contributions that transition metals bring to the overall structure of metal complexes depend on the various coordination numbers, geometries, physiologically relevant redox potentials, as well as kinetic and thermodynamic characteristics. The vast range of ligands that can be utilised must also be considered. Given this diversity, a variety of biological interactions is not unexpected. Specifically, interactions with negatively-charged DNA can arise due to covalent/coordinate or subtle non-coordinate interactions such as electrostatic attraction, groove binding and intercalation as well as combinations of all of these modes. The potential of metal complexes as therapeutic agents is but one aspect of their utility. Complexes, both new and old, are currently being utilised in conjunction with spectroscopic and biological techniques to probe the interactions of DNA and its many structural forms. Here we present a review of metal complex-DNA interactions in which several binding modes and DNA structural forms are explored. PMID:25427534

  14. Multi-stage complex contagions.

    PubMed

    Melnik, Sergey; Ward, Jonathan A; Gleeson, James P; Porter, Mason A

    2013-03-01

    The spread of ideas across a social network can be studied using complex contagion models, in which agents are activated by contact with multiple activated neighbors. The investigation of complex contagions can provide crucial insights into social influence and behavior-adoption cascades on networks. In this paper, we introduce a model of a multi-stage complex contagion on networks. Agents at different stages-which could, for example, represent differing levels of support for a social movement or differing levels of commitment to a certain product or idea-exert different amounts of influence on their neighbors. We demonstrate that the presence of even one additional stage introduces novel dynamical behavior, including interplay between multiple cascades, which cannot occur in single-stage contagion models. We find that cascades-and hence collective action-can be driven not only by high-stage influencers but also by low-stage influencers. PMID:23556961

  15. Manipulating Complex Light with Metamaterials

    PubMed Central

    Zeng, Jinwei; Wang, Xi; Sun, Jingbo; Pandey, Apra; Cartwright, Alexander N.; Litchinitser, Natalia M.

    2013-01-01

    Recent developments in the field of metamaterials have revealed unparalleled opportunities for “engineering” space for light propagation; opening a new paradigm in spin- and quantum-related phenomena in optical physics. Here we show that unique optical properties of metamaterials (MMs) open unlimited prospects to “engineer” light itself. We propose and demonstrate for the first time a novel way of complex light manipulation in few-mode optical fibers using optical MMs. Most importantly, these studies highlight how unique properties of MMs, namely the ability to manipulate both electric and magnetic field components of electromagnetic (EM) waves, open new degrees of freedom in engineering complex polarization states of light at will, while preserving its orbital angular momentum (OAM) state. These results lay the first steps in manipulating complex light in optical fibers, likely providing new opportunities for high capacity communication systems, quantum information, and on-chip signal processing. PMID:24084836

  16. Attack vulnerability of complex networks

    NASA Astrophysics Data System (ADS)

    Holme, Petter; Kim, Beom Jun; Yoon, Chang No; Han, Seung Kee

    2002-05-01

    We study the response of complex networks subject to attacks on vertices and edges. Several existing complex network models as well as real-world networks of scientific collaborations and Internet traffic are numerically investigated, and the network performance is quantitatively measured by the average inverse geodesic length and the size of the largest connected subgraph. For each case of attacks on vertices and edges, four different attacking strategies are used: removals by the descending order of the degree and the betweenness centrality, calculated for either the initial network or the current network during the removal procedure. It is found that the removals by the recalculated degrees and betweenness centralities are often more harmful than the attack strategies based on the initial network, suggesting that the network structure changes as important vertices or edges are removed. Furthermore, the correlation between the betweenness centrality and the degree in complex networks is studied.

  17. Ofloxacin/beta-cyclodextrin complexation.

    PubMed

    Koester, L S; Guterres, S S; Le Roch, M; Eifler-Lima, V L; Zuanazzi, J A; Bassani, V L

    2001-07-01

    Ofloxacin (OFX) is a fluorquinolone characterized by photochemical instability. With the goal to improve its photostability in aqueous solutions, the complexation of ofloxacin with beta-cyclodextrin was investigated. The complexes showed a water solubility enhancement of approximately 2.6 times; nevertheless, the photodegradation of ofloxacin was not reduced. The complexes obtained were characterized by thermal and 1H nuclear magnetic resonance (NMR) analysis, which revealed an interaction between ofloxacin and beta-cyclodextrin. The last analysis indicated that only partial inclusion of the N-methylpiperazinyl moiety occurred, which can explain the fact that photostabilization was not improved. This partial inclusion phenomenon could be explained also by computer-aided molecular modeling. PMID:11548860

  18. Multi-stage complex contagions

    NASA Astrophysics Data System (ADS)

    Melnik, Sergey; Ward, Jonathan A.; Gleeson, James P.; Porter, Mason A.

    2013-03-01

    The spread of ideas across a social network can be studied using complex contagion models, in which agents are activated by contact with multiple activated neighbors. The investigation of complex contagions can provide crucial insights into social influence and behavior-adoption cascades on networks. In this paper, we introduce a model of a multi-stage complex contagion on networks. Agents at different stages—which could, for example, represent differing levels of support for a social movement or differing levels of commitment to a certain product or idea—exert different amounts of influence on their neighbors. We demonstrate that the presence of even one additional stage introduces novel dynamical behavior, including interplay between multiple cascades, which cannot occur in single-stage contagion models. We find that cascades—and hence collective action—can be driven not only by high-stage influencers but also by low-stage influencers.

  19. Characterising Complex Enzyme Reaction Data.

    PubMed

    Dönertaş, Handan Melike; Martínez Cuesta, Sergio; Rahman, Syed Asad; Thornton, Janet M

    2016-01-01

    The relationship between enzyme-catalysed reactions and the Enzyme Commission (EC) number, the widely accepted classification scheme used to characterise enzyme activity, is complex and with the rapid increase in our knowledge of the reactions catalysed by enzymes needs revisiting. We present a manual and computational analysis to investigate this complexity and found that almost one-third of all known EC numbers are linked to more than one reaction in the secondary reaction databases (e.g., KEGG). Although this complexity is often resolved by defining generic, alternative and partial reactions, we have also found individual EC numbers with more than one reaction catalysing different types of bond changes. This analysis adds a new dimension to our understanding of enzyme function and might be useful for the accurate annotation of the function of enzymes and to study the changes in enzyme function during evolution. PMID:26840640

  20. Interdisciplinary research with complex plasmas

    SciTech Connect

    Morfill, G. E.; Ivlev, A. V.; Brandt, P.; Loewen, H.

    2010-06-16

    In this topical review we combine results of research from the field of complex plasmas and colloidal dispersions. This research has opened the way to study strong coupling phenomena in real space and time at the most fundamental kinetic level. The physics of complex plasmas is dominated by the dynamics of slow moving and individually visible microparticles. In contrast to colloidal suspensions, where the fluid background medium results in huge overdamping, the neutral gas background medium in complex plasmas introduces only very little damping so that processes at all relevant time scales can be studied. This is of particular importance for some of the most outstanding questions in the self-organization of matter and critical phenomena.

  1. Complex Fluids and Hydraulic Fracturing.

    PubMed

    Barbati, Alexander C; Desroches, Jean; Robisson, Agathe; McKinley, Gareth H

    2016-06-01

    Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process. PMID:27070765

  2. Characterising Complex Enzyme Reaction Data

    PubMed Central

    Rahman, Syed Asad; Thornton, Janet M.

    2016-01-01

    The relationship between enzyme-catalysed reactions and the Enzyme Commission (EC) number, the widely accepted classification scheme used to characterise enzyme activity, is complex and with the rapid increase in our knowledge of the reactions catalysed by enzymes needs revisiting. We present a manual and computational analysis to investigate this complexity and found that almost one-third of all known EC numbers are linked to more than one reaction in the secondary reaction databases (e.g., KEGG). Although this complexity is often resolved by defining generic, alternative and partial reactions, we have also found individual EC numbers with more than one reaction catalysing different types of bond changes. This analysis adds a new dimension to our understanding of enzyme function and might be useful for the accurate annotation of the function of enzymes and to study the changes in enzyme function during evolution. PMID:26840640

  3. Complex Educational Design: A Course Design Model Based on Complexity

    ERIC Educational Resources Information Center

    Freire, Maximina Maria

    2013-01-01

    Purpose: This article aims at presenting a conceptual framework which, theoretically grounded on complexity, provides the basis to conceive of online language courses that intend to respond to the needs of students and society. Design/methodology/approach: This paper is introduced by reflections on distance education and on the paradigmatic view…

  4. The Ontologies of Complexity and Learning about Complex Systems

    ERIC Educational Resources Information Center

    Jacobson, Michael J.; Kapur, Manu; So, Hyo-Jeong; Lee, June

    2011-01-01

    This paper discusses a study of students learning core conceptual perspectives from recent scientific research on complexity using a hypermedia learning environment in which different types of scaffolding were provided. Three comparison groups used a hypermedia system with agent-based models and scaffolds for problem-based learning activities that…

  5. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  6. Holographic Complexity Equals Bulk Action?

    NASA Astrophysics Data System (ADS)

    Brown, Adam R.; Roberts, Daniel A.; Susskind, Leonard; Swingle, Brian; Zhao, Ying

    2016-05-01

    We conjecture that the quantum complexity of a holographic state is dual to the action of a certain spacetime region that we call a Wheeler-DeWitt patch. We illustrate and test the conjecture in the context of neutral, charged, and rotating black holes in anti-de Sitter spacetime, as well as black holes perturbed with static shells and with shock waves. This conjecture evolved from a previous conjecture that complexity is dual to spatial volume, but appears to be a major improvement over the original. In light of our results, we discuss the hypothesis that black holes are the fastest computers in nature.

  7. Accessing complexity from genome information

    NASA Astrophysics Data System (ADS)

    Tenreiro Machado, J. A.

    2012-06-01

    This paper studies the information content of the chromosomes of 24 species. In a first phase, a scheme inspired in dynamical system state space representation is developed. For each chromosome the state space dynamical evolution is shed into a two dimensional chart. The plots are then analyzed and characterized in the perspective of fractal dimension. This information is integrated in two measures of the species' complexity addressing its average and variability. The results are in close accordance with phylogenetics pointing quantitative aspects of the species' genomic complexity.

  8. 1998 Complex Systems Summer School

    SciTech Connect

    1998-12-15

    For the past eleven years a group of institutes, centers, and universities throughout the country have sponsored a summer school in Santa Fe, New Mexico as part of an interdisciplinary effort to promote the understanding of complex systems. The goal of these summer schools is to provide graduate students, postdoctoral fellows and active research scientists with an introduction to the study of complex behavior in mathematical, physical, and living systems. The Center for Nonlinear Studies supported the eleventh in this series of highly successful schools in Santa Fe in June, 1998.

  9. Correlation dimension of complex networks.

    PubMed

    Lacasa, Lucas; Gómez-Gardeñes, Jesús

    2013-04-19

    We propose a new measure to characterize the dimension of complex networks based on the ergodic theory of dynamical systems. This measure is derived from the correlation sum of a trajectory generated by a random walker navigating the network, and extends the classical Grassberger-Procaccia algorithm to the context of complex networks. The method is validated with reliable results for both synthetic networks and real-world networks such as the world air-transportation network or urban networks, and provides a computationally fast way for estimating the dimensionality of networks which only relies on the local information provided by the walkers. PMID:23679650

  10. Thermolysis of lanthanide dithiocarbamate complexes

    SciTech Connect

    Boncher, William L.; Regulacio, Michelle D.; Stoll, Sarah L.

    2010-01-15

    Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex. The synthesis temperatures are generally lower than standard solid state preparations, avoid toxic sulfurizing gases and provide a convenient route to prepare lanthanide chalcogenide nanoparticles. Depending on the reaction conditions and oxophilicity of the lanthanide, the sulfide material was formed with oxidized products including oxysulfides, oxysulfates and the oxide. - Graphical abstract: Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex.

  11. Holographic Complexity Equals Bulk Action?

    PubMed

    Brown, Adam R; Roberts, Daniel A; Susskind, Leonard; Swingle, Brian; Zhao, Ying

    2016-05-13

    We conjecture that the quantum complexity of a holographic state is dual to the action of a certain spacetime region that we call a Wheeler-DeWitt patch. We illustrate and test the conjecture in the context of neutral, charged, and rotating black holes in anti-de Sitter spacetime, as well as black holes perturbed with static shells and with shock waves. This conjecture evolved from a previous conjecture that complexity is dual to spatial volume, but appears to be a major improvement over the original. In light of our results, we discuss the hypothesis that black holes are the fastest computers in nature. PMID:27232013

  12. Cascade dynamics of complex propagation

    NASA Astrophysics Data System (ADS)

    Centola, Damon; Eguíluz, Víctor M.; Macy, Michael W.

    2007-01-01

    Random links between otherwise distant nodes can greatly facilitate the propagation of disease or information, provided contagion can be transmitted by a single active node. However, we show that when the propagation requires simultaneous exposure to multiple sources of activation, called complex propagation, the effect of random links can be just the opposite; it can make the propagation more difficult to achieve. We numerically calculate critical points for a threshold model using several classes of complex networks, including an empirical social network. We also provide an estimation of the critical values in terms of vulnerable nodes.

  13. Assessing the complexity of topographic mass in complex terrains

    NASA Astrophysics Data System (ADS)

    Kurmankozhayev, Azimkhan; Nemec, Vaclav; Sarybaev, Edil

    2014-05-01

    To assess the structure of terrain more objectively it is necessary to supplement and clarify the available characteristics with a number of numerical statistical indicators and formulas that reflect the actual links between separate features of terrain. Results from analysis of traditional variability assessment methods for characteristics of georesources allow concluding that a characteristic's variability usually has oscillatory and wavelike geometric image in the form of broken, polygonal, zigzagging, polyhedral and, less frequently, regular geometric shapes, defined by deviation amplitude and period of irregularities. It is established that variability cannot be evaluated with one universal indicator since variability consists of a random and a regular component, thus it is considered reasonable to assess the characteristic's variability depending on current mining and geometrical tasks and by stages of georesources development. The recommended topographic terrain mass complexity assessment method is based on the leading concept of using properties of specific anti-entropy that, unlike regular entropy, allows accounting for changes in total number of component elements in stable populations for the topographic terrain mass. Concept of utilizing value of specific anti-entropy, widely used in information theory, is taken as an assessment criterion for integral complexity of topographic terrain mass. Modification of specific anti-entropy formula, as applied to substance of formation of the georesource development target's topographic mass integral complexity, is based on qualimetric model of its assessment. Essence of the model comes down to determining the topographic mass complexity using the topographic mass structure uncertainty measure, assessed using the quantity of heterogeneous morphometric elements contained in the topographic surface of terrain. The main basic reference value in qualimetric model of the topographic terrain mass complexity is the

  14. Language Networks as Complex Systems

    ERIC Educational Resources Information Center

    Lee, Max Kueiming; Ou, Sheue-Jen

    2008-01-01

    Starting in the late eighties, with a growing discontent with analytical methods in science and the growing power of computers, researchers began to study complex systems such as living organisms, evolution of genes, biological systems, brain neural networks, epidemics, ecology, economy, social networks, etc. In the early nineties, the research…

  15. Capturing Complexity through Maturity Modelling

    ERIC Educational Resources Information Center

    Underwood, Jean; Dillon, Gayle

    2004-01-01

    The impact of information and communication technologies (ICT) on the process and products of education is difficult to assess for a number of reasons. In brief, education is a complex system of interrelationships, of checks and balances. This context is not a neutral backdrop on which teaching and learning are played out. Rather, it may help, or…

  16. Aromatic triamide-lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Petoud, Stephane; Xu, Jide

    2013-10-08

    The present invention provides luminescent lanthanide metal chelates comprising a metal ion of the lanthanide series and a complexing agent comprising at least one phthalamidyl moiety. Also provided are probes incorporating the phthalamidyl ligands of the invention and methods utilizing the ligands of the invention and probes comprising the ligands of the invention.

  17. Complex Landscape Terms in Seri

    ERIC Educational Resources Information Center

    O'Meara, Carolyn; Bohnemeyer, Jurgen

    2008-01-01

    The nominal lexicon of Seri is characterized by a prevalence of analytical descriptive terms. We explore the consequences of this typological trait in the landscape domain. The complex landscape terms of Seri classify geographic entities in terms of their material make-up and spatial properties such as shape, orientation, and merological…

  18. Tracking simple and complex sequences.

    PubMed

    Large, Edward W; Fink, Philip; Kelso, J A Scott

    2002-02-01

    We address issues of synchronization to rhythms of musical complexity. In two experiments, synchronization to simple and more complex rhythmic sequences was investigated. Experiment 1 examined responses to phase and tempo perturbations within simple, structurally isochronous sequences, presented at different base rates. Experiment 2 investigated responses to similar perturbations embedded within more complex, metrically structured sequences; participants were explicitly instructed to synchronize at different metrical levels (i.e., tap at different rates to the same rhythmic patterns) on different trials. We found evidence that (1) the intrinsic tapping frequency adapts in response to temporal perturbations in both simple (isochronous) and complex (metrically structured) rhythms, (2) people can synchronize with unpredictable, metrically structured rhythms at different metrical levels, with qualitatively different patterns of synchronization seen at higher versus lower levels of metrical structure, and (3) synchronization at each tapping level reflects information from other metrical levels. The latter finding provides evidence for a dynamic and flexible internal representation of the sequence's metrical structure. PMID:11963276

  19. Design Patterns for Complex Learning

    ERIC Educational Resources Information Center

    Rohse, Shanta; Anderson, Terry

    2006-01-01

    A complex view of learning recognises that learning cannot be pre-determined by teaching, but is as much defined by circumstances and context as pre-defined learning objectives. Learning designs that accept uncertainty help us to envision classrooms and curricula that are open, dynamic and innovative. Architect Christopher Alexander's patterns and…

  20. Hydrogen storage via polyhydride complexes

    SciTech Connect

    Jensen, C.M.

    1996-10-01

    Polyhydride metal complexes are being developed for application to hydrogen storage. Complexes have been found which catalyze the reversible hydrogenation of unsaturated hydrocarbons. This catalytic reaction could be the basis for a low temperature, hydrogen storage system with a available hydrogen density greater than 7 weight percent. The P-C-P pincer complexes, RhH{sub 2}(C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}) and IrH{sub 2}(C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}) have unprecedented, long term stability at elevated temperatures. The novel iridium complex catalyzes the transfer dehydrogenation of cycloctane to cyclooctene at the rate of 716 turnovers/h which is 2 orders of magnitude greater than that found for previously reported catalytic systems which do not require the sacrificial hydrogenation of a large excess of hydrogen acceptor.

  1. The Complexities of Domestic Violence

    ERIC Educational Resources Information Center

    Dutton, Donald G.

    2007-01-01

    Comments on the article by Robert Bornstein, "The complex relationship between dependency and domestic violence: Converging psychological factors and social forces." Although a more focused examination of the psychological factors involved in domestic violence is welcome, there are some factual errors in Bornstein's article that need attention and…

  2. Complex disease, gender and epigenetics.

    PubMed

    Kaminsky, Zachary; Wang, Sun-Chong; Petronis, Arturas

    2006-01-01

    Gender differences in susceptibility to complex disease such as asthma, diabetes, lupus, autism and major depression, among numerous other disorders, represent one of the hallmarks of non-Mendelian biology. It has been generally accepted that endocrinological differences are involved in the sexual dimorphism of complex disease; however, specific molecular mechanisms of such hormonal effects have not been elucidated yet. This paper will review evidence that sex hormone action may be mediated via gene-specific epigenetic modifications of DNA and histones. The epigenetic modifications can explain sex effects at DNA sequence polymorphisms and haplotypes identified in gender-stratified genetic linkage and association studies. Hormone-induced DNA methylation and histone modification changes at specific gene regulatory regions may increase or reduce the risk of a disease. The epigenetic interpretation of sexual dimorphism fits well into the epigenetic theory of complex disease, which argues for the primary pathogenic role of inherited and/or acquired epigenetic misregulation rather than DNA sequence variation. The new experimental strategies, especially the high throughput microarray-based epigenetic profiling, can be used for testing the epigenetic hypothesis of gender effects in complex diseases. PMID:17438668

  3. Teaching the Prison Industrial Complex

    ERIC Educational Resources Information Center

    Lakshmi, Aparna

    2012-01-01

    The author teaches in an alternative school in Boston Public Schools and works with students who had dropped out, transferred, or been expelled from their previous schools. Many of her students struggled with reading complex texts and had never learned how to make and defend an argument through their writing. She was determined that they would…

  4. Complex Knowledge Mastery: Some Propositions.

    ERIC Educational Resources Information Center

    Keller, Joyce A.; Schallert, Diane L.

    The proposition that the mastery of complex tasks embodies several components was studied for 236 students in an undergraduate introductory financial accounting course. A new curriculum was developed for the course that included in-depth exposure to the actual financial statements of a company and the understanding of the structural relationships…

  5. Porous Soil as Complex Network

    NASA Astrophysics Data System (ADS)

    Benito, R. M.; Santiago, A.; Cárdenas, J. P.; Tarquis, A. M.; Borondo, F.; Losada, J. C.

    2009-04-01

    We present a complex network model based on a heterogeneous preferential attachment scheme [1,2] to quantify the structure of porous soils [3]. Under this perspective pores are represented by nodes and the space for the flow of fluids between them are represented by links. Pore properties such as position and size are described by fixed states in a metric space, while an affinity function is introduced to bias the attachment probabilities of links according to these properties. We perform an analytical and numerical study of the degree distributions in the soil model and show that under reasonable conditions all the model variants yield a multiscaling behavior in the connectivity degrees, leaving a empirically testable signature of heterogeneity in the topology of pore networks. References [1] A. Santiago and R. M. Benito, "Emergence of multiscaling in heterogeneous complex networks". Int. J. Mod. Phys. C 18, 1591 (2007). [2] A. Santiago and R. M. Benito, "An extended formalism for preferential attachment in heterogeneous complex networks". Europhys. Lett. 82, 58004 (2008). [3] A. Santiago, R. M. Benito, J. P. Cárdenas, J. C. Losada, A. M. Tarquis and F. Borondo, "Multiscaling of porous soils as heterogeneous complex networks". Nonl. Proc. Geophys. 15, 1-10 (2008).

  6. Women's Health and Complexity Science.

    ERIC Educational Resources Information Center

    Hoffman, Eileen

    2000-01-01

    Explores how changes in conceptual frameworks in science, from reductionism to complexity; an outgrowth of the chaos theory that views parts in relation to one another, the entity they form, and the environment, must inform the development of an academic discipline in women's health. (SLD)

  7. Leadership Learning for Complex Organizations

    ERIC Educational Resources Information Center

    Ng, F. S. David

    2015-01-01

    Many school leadership programs are set and delivered in specific modules or workshops in order to achieve a pre-determined set of competencies, knowledge, and skills. In addition, these programs are driven by the faculty member and the prescribed content. As Singapore schools become more complex in the roles and responsibilities to educate the…

  8. Biologically Inspired Phosphino Platinum Complexes

    SciTech Connect

    Jain, Avijita; Helm, Monte L.; Linehan, John C.; DuBois, Daniel L.; Shaw, Wendy J.

    2012-08-01

    Platinum complexes containing phosphino amino acid and amino acid ester ligands, built upon the PPhNR’2 platform, have been synthesized and characterized (PPhNR’2= [1,3-diaza]-5-phenyl phosphacyclohexane, R’=glycine or glycine ester). These complexes were characterized by 31P, 13C, 1H, 195Pt NMR spectroscopy and mass spectrometry. The X-ray crystal structure of one of the complexes, [PtCl2(PPhNGlyester 2)2], is also reported. These biologically inspired ligands have potential use in homogeneous catalysis, with special applications in chiral chemistry and water soluble chemistry. These complexes also provide a foundation upon which larger peptides can be attached, to allow the introduction of enzyme-like features onto small molecule catalysts. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  9. Mass spectrometry of large complexes.

    PubMed

    Bich, Claudia; Zenobi, Renato

    2009-10-01

    Mass spectrometry is becoming a more and more powerful tool for investigating protein complexes. Recent developments, based on different ionization techniques, electrospray, desorption/ionization and others are contributing to the usefulness of MS to describe the organization and structure of large non-covalent assemblies. PMID:19782560

  10. Challenges in complex systems science

    NASA Astrophysics Data System (ADS)

    San Miguel, M.; Johnson, J. H.; Kertesz, J.; Kaski, K.; Díaz-Guilera, A.; MacKay, R. S.; Loreto, V.; Érdi, P.; Helbing, D.

    2012-11-01

    FuturICT foundations are social science, complex systems science, and ICT. The main concerns and challenges in the science of complex systems in the context of FuturICT are laid out in this paper with special emphasis on the Complex Systems route to Social Sciences. This include complex systems having: many heterogeneous interacting parts; multiple scales; complicated transition laws; unexpected or unpredicted emergence; sensitive dependence on initial conditions; path-dependent dynamics; networked hierarchical connectivities; interaction of autonomous agents; self-organisation; non-equilibrium dynamics; combinatorial explosion; adaptivity to changing environments; co-evolving subsystems; ill-defined boundaries; and multilevel dynamics. In this context, science is seen as the process of abstracting the dynamics of systems from data. This presents many challenges including: data gathering by large-scale experiment, participatory sensing and social computation, managing huge distributed dynamic and heterogeneous databases; moving from data to dynamical models, going beyond correlations to cause-effect relationships, understanding the relationship between simple and comprehensive models with appropriate choices of variables, ensemble modeling and data assimilation, modeling systems of systems of systems with many levels between micro and macro; and formulating new approaches to prediction, forecasting, and risk, especially in systems that can reflect on and change their behaviour in response to predictions, and systems whose apparently predictable behaviour is disrupted by apparently unpredictable rare or extreme events. These challenges are part of the FuturICT agenda.

  11. DNA/chitosan electrostatic complex.

    PubMed

    Bravo-Anaya, Lourdes Mónica; Soltero, J F Armando; Rinaudo, Marguerite

    2016-07-01

    Up to now, chitosan and DNA have been investigated for gene delivery due to chitosan advantages. It is recognized that chitosan is a biocompatible and biodegradable non-viral vector that does not produce immunological reactions, contrary to viral vectors. Chitosan has also been used and studied for its ability to protect DNA against nuclease degradation and to transfect DNA into several kinds of cells. In this work, high molecular weight DNA is compacted with chitosan. DNA-chitosan complex stoichiometry, net charge, dimensions, conformation and thermal stability are determined and discussed. The influence of external salt and chitosan molecular weight on the stoichiometry is also discussed. The isoelectric point of the complexes was found to be directly related to the protonation degree of chitosan. It is clearly demonstrated that the net charge of DNA-chitosan complex can be expressed in terms of the ratio [NH3(+)]/[P(-)], showing that the electrostatic interactions between DNA and chitosan are the main phenomena taking place in the solution. Compaction of DNA long chain complexed with low molar mass chitosan gives nanoparticles with an average radius around 150nm. Stable nanoparticles are obtained for a partial neutralization of phosphate ionic sites (i.e.: [NH3(+)]/[P(-)] fraction between 0.35 and 0.80). PMID:27050113

  12. Libraries Serving the CSIR Complex.

    ERIC Educational Resources Information Center

    Rajagopalan, T. S.; Ramaswami, K.

    A survey of the resources and services of the Council of Scientific and Industrial Research (CSIR) libraries was made so that the libraries in the complex could share the benefit of the experiences of each other. The report is based on questionnaire replies received from 31 CSIR Institutions and eight Co-operative Research Associations and relates…

  13. Reading, Complexity and the Brain

    ERIC Educational Resources Information Center

    Goswami, Usha

    2008-01-01

    Brain imaging offers a new technology for understanding the acquisition of reading by children. It can contribute novel evidence concerning the key mechanisms supporting reading, and the brain systems that are involved. The extensive neural architecture that develops to support efficient reading testifies to the complex developmental processes…

  14. Learning To Live with Complexity.

    ERIC Educational Resources Information Center

    Dosa, Marta

    Neither the design of information systems and networks nor the delivery of library services can claim true user centricity without an understanding of the multifaceted psychological environment of users and potential users. The complexity of the political process, social problems, challenges to scientific inquiry, entrepreneurship, and…

  15. Copper complexes as anticancer agents.

    PubMed

    Marzano, Cristina; Pellei, Maura; Tisato, Francesco; Santini, Carlo

    2009-02-01

    Metal-based antitumor drugs play a relevant role in antiblastic chemotherapy. Cisplatin is regarded as one of the most effective drugs, even if severe toxicities and drug resistance phenomena limit its clinical use. Therefore, in recent years there has been a rapid expansion in research and development of novel metal-based anticancer drugs to improve clinical effectiveness, to reduce general toxicity and to broaden the spectrum of activity. The variety of metal ion functions in biology has stimulated the development of new metallodrugs other than Pt drugs with the aim to obtain compounds acting via alternative mechanisms of action. Among non-Pt compounds, copper complexes are potentially attractive as anticancer agents. Actually, since many years a lot of researches have actively investigated copper compounds based on the assumption proposal that endogenous metals may be less toxic. It has been established that the properties of copper-coordinated compounds are largely determined by the nature of ligands and donor atoms bound to the metal ion. In this review, the most remarkable achievements in the design and development of copper(I, II) complexes as antitumor agents are discussed. Special emphasis has been focused on the identification of structure-activity relationships for the different classes of copper(I,II) complexes. This work was motivated by the observation that no comprehensive surveys of copper complexes as anticancer agents were available in the literature. Moreover, up to now, despite the enormous efforts in synthesizing different classes of copper complexes, very few data concerning the molecular basis of the mechanisms underlying their antitumor activity are available. This overview, collecting the most significant strategies adopted in the last ten years to design promising anticancer copper(I,II) compounds, would be a help to the researchers working in this field. PMID:19199864

  16. Statistical mechanics of macromolecular complexation

    NASA Astrophysics Data System (ADS)

    Nakamura, Issei

    The self-assembly of macromolecules through molecular association has attracted long-standing attention in soft-condensed matter physics. The hierarchical formation from small-scale building blocks into larger-scale complex structures often leads to very rich phase behavior controlled by various ambient conditions. The understanding and control of the phase behavior of self-assembling systems require detailed knowledge about the entropy and enthalpy contributions to the free energy of the system. However, this knowledge is limited at the present time because a comprehensive theoretical description of molecular association is still lacking. In this thesis, four tales of achievements in developing theories of macromolecular complexation are presented. (1) We begin with an analytically solvable model of the self-assembly of rigid macromolecules with surface adsorption. A generic understanding of the driving force and the role of entropy is obtained from the exact solutions. (2) We move on to further development of the theory in order to study the complexation between polymers and ionic molecules. The extension of the first model to chain-like molecules is performed using a well-established method in polymer physics, the self-consistent field theory (SCFT) of polymers. We also discuss gelation in this system within the scope of mean-filed approximations. (3) Then, a ladder-like polymer-polymer complexation is studied. Unconventional phase diagrams are predicted from the modified SCFT, indicating a large effect of variations in entropy due to the complexation on bulk properties. (4) Finally, the kinetic aspect of macromolecular binding reactions is discussed.

  17. Hierarchy Measure for Complex Networks

    PubMed Central

    Mones, Enys; Vicsek, Lilla; Vicsek, Tamás

    2012-01-01

    Nature, technology and society are full of complexity arising from the intricate web of the interactions among the units of the related systems (e.g., proteins, computers, people). Consequently, one of the most successful recent approaches to capturing the fundamental features of the structure and dynamics of complex systems has been the investigation of the networks associated with the above units (nodes) together with their relations (edges). Most complex systems have an inherently hierarchical organization and, correspondingly, the networks behind them also exhibit hierarchical features. Indeed, several papers have been devoted to describing this essential aspect of networks, however, without resulting in a widely accepted, converging concept concerning the quantitative characterization of the level of their hierarchy. Here we develop an approach and propose a quantity (measure) which is simple enough to be widely applicable, reveals a number of universal features of the organization of real-world networks and, as we demonstrate, is capable of capturing the essential features of the structure and the degree of hierarchy in a complex network. The measure we introduce is based on a generalization of the m-reach centrality, which we first extend to directed/partially directed graphs. Then, we define the global reaching centrality (GRC), which is the difference between the maximum and the average value of the generalized reach centralities over the network. We investigate the behavior of the GRC considering both a synthetic model with an adjustable level of hierarchy and real networks. Results for real networks show that our hierarchy measure is related to the controllability of the given system. We also propose a visualization procedure for large complex networks that can be used to obtain an overall qualitative picture about the nature of their hierarchical structure. PMID:22470477

  18. Neural Mechanisms Underlying Breathing Complexity

    PubMed Central

    Hess, Agathe; Yu, Lianchun; Klein, Isabelle; De Mazancourt, Marine; Jebrak, Gilles; Mal, Hervé; Brugière, Olivier; Fournier, Michel; Courbage, Maurice; Dauriat, Gaelle; Schouman-Clayes, Elisabeth; Clerici, Christine; Mangin, Laurence

    2013-01-01

    Breathing is maintained and controlled by a network of automatic neurons in the brainstem that generate respiratory rhythm and receive regulatory inputs. Breathing complexity therefore arises from respiratory central pattern generators modulated by peripheral and supra-spinal inputs. Very little is known on the brainstem neural substrates underlying breathing complexity in humans. We used both experimental and theoretical approaches to decipher these mechanisms in healthy humans and patients with chronic obstructive pulmonary disease (COPD). COPD is the most frequent chronic lung disease in the general population mainly due to tobacco smoke. In patients, airflow obstruction associated with hyperinflation and respiratory muscles weakness are key factors contributing to load-capacity imbalance and hence increased respiratory drive. Unexpectedly, we found that the patients breathed with a higher level of complexity during inspiration and expiration than controls. Using functional magnetic resonance imaging (fMRI), we scanned the brain of the participants to analyze the activity of two small regions involved in respiratory rhythmogenesis, the rostral ventro-lateral (VL) medulla (pre-Bötzinger complex) and the caudal VL pons (parafacial group). fMRI revealed in controls higher activity of the VL medulla suggesting active inspiration, while in patients higher activity of the VL pons suggesting active expiration. COPD patients reactivate the parafacial to sustain ventilation. These findings may be involved in the onset of respiratory failure when the neural network becomes overwhelmed by respiratory overload We show that central neural activity correlates with airflow complexity in healthy subjects and COPD patients, at rest and during inspiratory loading. We finally used a theoretical approach of respiratory rhythmogenesis that reproduces the kernel activity of neurons involved in the automatic breathing. The model reveals how a chaotic activity in neurons can

  19. Complex DNA structures and structures of DNA complexes

    SciTech Connect

    Chazin, W.J.; Carlstroem, G.; Shiow-Meei Chen; Miick, S.; Gomez-Paloma, L.; Smith, J.; Rydzewski, J.

    1994-12-01

    Complex DNA structures (for example, triplexes, quadruplexes, junctions) and DNA-ligand complexes are more difficult to study by NMR than standard DNA duplexes are because they have high molecular weights, show nonstandard or distorted local conformations, and exhibit large resonance linewidths and severe {sup 1}H spectral overlap. These systems also tend to have limited solubility and may require specialized solution conditions to maintain favorable spectral characteristics, which adds to the spectroscopic difficulties. Furthermore, with more atoms in the system, both assignment and structure calculation become more challenging. In this article, we focus on demonstrating the current status of NMR studies of such systems and the limitations to further progress; we also indicate in what ways isotopic enrichment can be useful.

  20. 1: Redox chemistry of bimetallic fulvalene complexes; 2: Oligocyclopentadienyl complexes

    SciTech Connect

    Brown, D. S.

    1993-11-01

    The electrochemistry of the heterobimetallic complexes (fulvalene)WFe(CO){sub 5} (30) and (fulvalene)WRu(CO){sub 5} (31) has been investigated. Compound 30 is reduced in two one-electron processes, and this behavior was exploited synthetically to prepare a tetranuclear dimer by selective metal reduction. Complex 31 displayed a distinction between the metals upon reoxidation of the dianion, allowing the formation of a dimer by selective metal anion oxidation. The redox behavior of 30 led to an investigation of the use of electrocatalysis to effect metal-specific ligand substitution. It was found that reduction of 30 with a catalytic amount of CpFe(C{sub 6}Me{sub 6}) (97) in the presence of excess P(OMe){sub 3} or PMe{sub 3} led to the formation of the zwitterions (fulvalene)[W(CO){sub 3}{sup {minus}}][Fe(CO)PR{sub 3}{sup +}] (107, R = P(OMe){sub 3}; 108, R = PMe{sub 3}). Compound 31 also displayed unique behavior with different reducing agents, as the monosubstituted zwitterion (fulvalene)[W(CO){sub 3}{sup {minus}}][Ru(CO){sub 2}(PMe{sub 3}){sup +}] was obtained when 97 was used while the disubstituted complex (fulvalene) [W(CO){sub 3}{sup {minus}}] [Ru(CO)(PMe{sub 3}){sub 2}{sup +}] was produced when Cp*Fe(C{sub 6}Me{sub 6}) was the catalyst. Potential synthetic routes to quatercyclopentadienyl complexes were also explored. Various attempts to couple heterobimetallic fulvalene compounds proved to be unsuccessful. 138 refs.