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Sample records for 208pb pri energyiyi

  1. Interaction of 11Li with 208Pb

    NASA Astrophysics Data System (ADS)

    Vinodkumar, A. M.; Loveland, W.; Yanez, R.; Leonard, M.; Yao, L.; Bricault, P.; Dombsky, M.; Kunz, P.; Lassen, J.; Morton, A. C.; Ottewell, D.; Preddy, D.; Trinczek, M.

    2013-04-01

    Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li with 208Pb is the subject of a number of theoretical studies with widely differing predictions, ranging over four orders of magnitude, for the fusion excitation function.Purpose: The purpose was to measure the excitation function for the 11Li + 208Pb reaction.Methods: A stacked foil and degrader assembly of 208Pb targets was irradiated with a 11Li beam producing center-of-target beam energies from above-barrier to near-barrier energies (40-29 MeV). The intensity of the 11Li beam (chopped) was 1250 particles/s and the beam on-target time was 34 h. The α decay of the stopped evaporation residues (EVRs) was detected in an α-detector array at each beam energy in the beam-off period (the beam was on for ≤5 ns and then off for 170 ns).Results: The observed nuclidic yields of 212/215At and 214At are consistent with being produced in the complete fusion of 11Li with 208Pb. The observed yields of 213At appear to be the result of the breakup of 11Li into 9Li+2n, with the 9Li fusing with 208Pb. The magnitudes of the total fusion cross sections are substantially less than most theoretical predictions.Conclusions: It is possible to measure the EVR production cross sections resulting from the interaction of 11Li with 208Pb using current-generation radioactive beam facilities. Both complete fusion and breakup fusion processes occur in the interaction of 11Li with 208Pb. An important breakup process leads to the fusion of the 9Li fragment with 208Pb.

  2. Particle Production in 158.A GeV 208Pb+208Pb Collisions

    SciTech Connect

    Awes, T.C.

    1999-01-09

    The production of neutral pions in 158A GeV {sup 208}Pb+{sup 208}Pb collisions has been studied in the WA98 experiment. The centrality dependence of the neutral pion production is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with more than about 50 participants. The transverse mass spectrum is analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement constrains the extracted freeze-out parameters, and provides information on the freeze-out velocity profile.

  3. Partial Photoneutron Cross Sections for 207,208Pb

    NASA Astrophysics Data System (ADS)

    Kondo, T.; Utsunomiya, H.; Goriely, S.; Iwamoto, C.; Akimune, H.; Yamagata, T.; Toyokawa, H.; Harada, H.; Kitatani, F.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.

    2014-05-01

    Using linearly-polarized laser-Compton scattering γ-rays, partial E1 and M1 photoneutron cross sections along with total cross sections were determined for 207,208Pb at four energies near neutron threshold by measuring anisotropies in photoneutron emission. Separately, total photoneutron cross sections were measured for 207,208Pb with a high-efficiency 4π neutron detector. The partial cross section measurement provides direct evidence for the presence of pygmy dipole resonance (PDR) in 207,208Pb in the vicinity of neutron threshold. The strength of PDR amounts to 0.32%-0.42% of the Thomas-Reiche-Kuhn sum rule. Several μN2 units of B(M1)↑ strength were observed in 207,208Pb just above neutron threshold, which correspond to M1 cross sections less than 10% of the total photoneutron cross sections.

  4. Fusion of {sup 9}Li with {sup 208}Pb

    SciTech Connect

    Vinodkumar, A. M.; Loveland, W.; Sprunger, P. H.; Prisbrey, L.; Trinczek, M.; Dombsky, M.; Machule, P.; Kolata, J. J.; Roberts, A.

    2009-11-15

    We have measured the fusion excitation function for the {sup 9}Li+{sup 208}Pb reaction for near-barrier projectile center-of-mass energies of 23.9 to 43.0 MeV using the ISAC2 facility at TRIUMF. The {alpha}-emitting evaporation residues ({sup 211-214}At) were stopped in the {sup 208}Pb target, and their decay was measured. The isotopic yields at each energy were in good agreement with the predictions of a statistical model code (HIVAP). The measured fusion excitation function shows evidence for substantial sub-barrier fusion enhancement not predicted by current theoretical models. There is a suppression of the above barrier cross sections relative to these model predictions. The implications of this measurement for studying the fusion of {sup 11}Li with {sup 208}Pb are discussed.

  5. Complete Electric Dipole Strength and Neutron Skin in 208Pb

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, P.; Poltoraska, I.; Tamii, A.

    2013-03-01

    Small-angle polarized proton scattering including 0° on 208Pb has been studied at the RCNP cyclotron with high energy resolution of the order 25 -- 30 keV (FWHM). The complete E1 strength distribution from 5 to 20 MeV could be extracted from the data. The total E1 polarizability as well as the properties of the pygmy dipole resonance can be extracted with high precision providing important experimental constraints on the neutron skin thickness in 208Pb and the symmetry energy of neutron matter.

  6. Multinucleon transfer reactions in the 40Ar+208Pb system

    NASA Astrophysics Data System (ADS)

    Mijatović, T.; Szilner, S.; Corradi, L.; Montanari, D.; Pollarolo, G.; Fioretto, E.; Gadea, A.; Goasduff, A.; Malenica, D. Jelavić; Mǎrginean, N.; Milin, M.; Montagnoli, G.; Scarlassara, F.; Soić, N.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.

    2016-12-01

    We measured multinucleon transfer reactions in the 40Ar+208Pb system at an energy close to the Coulomb barrier, by employing the PRISMA magnetic spectrometer. We extracted differential and total cross sections of the different transfer channels, with a careful investigation of the total kinetic energy loss distributions. Comparisons between different systems having the same 208Pb target and with projectiles going from neutron-poor to neutron-rich nuclei, i.e., 40Ca, 58Ni, and 40Ar, as well as between the data and GRAZING calculations have been carried out. The neutron-rich (stable) 40Ar beam allowed us to get access to the channels involving proton pickup, whose behavior in connection with the production of neutron-rich heavy partner has been outlined.

  7. Centrality Dependence of Neutral Pion Production in 158A GeV {sup 208}Pb+{sup 208}Pb Collisions

    SciTech Connect

    Aggarwal, M.M.; Bhatia, V.S.; Agnihotri, A.; Bhalla, K.B.; Gupta, S.K.; Raniwala, R.; Raniwala, S.; Ahammed, Z.; Chattopadhyay, S.; Das, A.C.; Dutta Majumdar, M.R.; Ganti, M.S.; Mukhopadhyay, D.S.; Nayak, T.K.; Sinha, B.C.; Trivedi, M.D.; Viyogi, Y.P.; Angelis, A.L.; Donni, P.; Foka, P.; Kalechofsky, H.; Martin, M.; Naef, H.; Rosselet, L.; Rubio, J.M.; Solomey, N.; Voeroes, S.; Antonenko, V.; Cherbatchev, R.; Doubovik, I.; Fokin, S.; Ippolitov, M.; Karadjev, K.; Koutcheryaev, I.; Lebedev, A.; Manko, V.; Mgebrichvili, G.; Nianine, A.; Sibiriak, I.; Tsvetkov, A.; Vinogradov, A.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Baldine, A.; Barabach, L.; Batiounia, B.; Chalyshev, V.; Djordjadze, V.; Frolov, V.; Gavrishchuk, O.; Guskov, B.; Kosarev, I.; Kuzmin, N.; Maximov, A.; Mehdiyev, R.; Mikhalev, D.; Myalkovski, V.; Nikitine, V.; Nikolaev, S.; Nomokonov, P.; Parfenov, A.; Pavliouk, S.; Roufanov, I.; Shabratova, G.; Slavine, N.; Vodopianov, A.; Awes, T.C.; Kim, H.; Plasil, F.; Stankus, P.; Young, G.R.; Baba, P.V.; Badyal, S.K.; Rao, N.K.; Sambyal, S.S.; Barlag, C.; Bathe, S.; Blume, C.; Bohne, E.; Boeroecz, Z.K.; Bucher, D.; Buesching, H.; Claussen, A.; Glasow, R.; Kampert, K.; Kees, S.; Kruempel, T.; Pietzmann, T.; Reygers, K.; Santo, R.; Schlagheck, H.; Stueken, D.; Bernier, T.; Gutbrod, H.H.; Luquin, L.; Nayak, S.K.; Pinanaud, W.; Retiere, F.; Roy, C.; Bock, R.; Kolb, B.W.; Langbein, I.; Lee, Y.Y.; Neumaier, S.; and others

    1998-11-01

    The production of neutral pions in 158A GeV {sup 208}Pb+ {sup 208}Pb collisions has been studied in the WA98 experiment at the CERN Super Proton Synchrotron (SPS). Transverse momentum spectra are studied for the range 0.3{le}m{sub T}{minus}m{sub 0}{le}4.0 GeV /c . The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30thinspthinspparticipating nucleons. This is most naturally explained by assuming an equilibrated system. {copyright} {ital 1998} {ital The American Physical Society }

  8. Distribution of M1 transitions in /sup 208/Pb

    SciTech Connect

    Laszewski, R.M.; Alarcon, R.; Dale, D.S.; Hoblit, S.D.

    1988-10-10

    The distribution of M1 strength in /sup 208/Pb has been measured between 5.8 and 7.4 MeV with highly polarized tagged photons. ..sigma..GAMMA/sup 2//sub 0/(M/sup 1/)/GAMMA = 14.6 +- /sup +1.5//sub -1.3/ eV corresponding to ..sigma..B(M1up-arrow) = 10.7 +- /sup +1.1//sub -0.9/..mu../sup 2//sub N/ was found, and can fully account for the much discussed ''missing'' M1 in /sup 208/Pb. When the present result is combined with known 1/sup 1/ transitions above neutron threshold, an M1 giant resonance emerges at 7.3 MeV, 1 MeV wide, with ..sigma..B(M1up-arrow)approx. =15.6..mu../sup 2//sub N/. Smaller 1/sup +/ resonances are also seen in both 5.85 and 6.24 MeV. The total M1 strength below 6.4 MeV amounts to ..sigma..B(M) = (1.9/sup +0.7//sub -0.4/)..mu../sup 2//sub N/.

  9. Proton particle-hole states in 208Pb

    NASA Astrophysics Data System (ADS)

    Grabmayr, P.; Mairle, G.; Schmidt-Rohr, U.; Berg, G. P. A.; Meissburger, J.; von Rossen, P.; Tain, J. L.

    1987-07-01

    Differential cross sections for the 209Bi(d, 3He) 208Pb transitions to the proton particle-proton hole states in 208Pb were obtained with the 45 MeV analyzed deuteron beam from the JULIC cyclotron and the high resolution spectrograph BIG KARL. 72 states up to 6.6 MeV were studied with an overall resolution of 12 to 15keV. Spectroscopic factors were extracted relative to the simultaneously measured calibration reaction 208Pb(d, 3He) 207Tl. For 26 states new parity assignments were possible on the basis of the measured angular distributions. The deduced inclusion into one of the four multiplets put limits on the possible spins of the states in question. With the help of sum rule arguments the spins of 12 states were assigned. The comparison with shell model calculations give only rough agreement as they predict the energies of the respective states about 300 keV too high. The magnetic dipole state at 5.846 MeV was observed with a Spectroscopic factor C2S = 0.17. From this, together with the transition probability B(M1↑) = (1.6 ± 0.5) μN2 from a ( overlineγ, γ') experiment we derived size and relative sign of the dominant neutron and proton spin-flip amplitudes. The result gives clear evidence for the isoscalar character of this state in accordance wtih TDA and RPA predictions. The matrix elements of the two-body residual interaction were derived unambiguously for the h{9}/{2} ∗ s{1}/{2}and h{9}/{2} ∗ d{3}/{2} multiplets. For the h{9}/{2}∗ h{11}/{2} and h{9}/{2} ∗ d{5}/{2} multiplets uncertainties are larger because of assumptions of some of the spins for the states of high excitation energy. The four monopole terms are found close to the average of -308 keV. They are dominated by the Coulomb contributions of ≈ - 216 keV. The deduced J-dependence of the matrix elements differs from those found in other systematic investigations indicating more complicated underlying nuclear forces must contribute.

  10. New Neutron Rich Nuclei Near {sup 208}Pb

    SciTech Connect

    Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M.; ISOLDE Collaboration; Jokinen, A.; Karny, M.; Kugler, E.; Kurpeta, J.; Lettry, J.; Nieminen, A.; Plochocki, A.; Ramdhane, M.; Ravn, H.; Rykaczewski, K.; Szerypo, J.; VanDuppen, P.; Walter, G.; Woehr, A.

    1998-11-13

    The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.

  11. Search for the two-phonon octupole vibrational state in {sup 208}Pb

    SciTech Connect

    Blumenthal, D.J.; Henning, W.; Janssens, R.V.F.

    1995-08-01

    We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.

  12. Electric dipole excitation of 208Pb by polarized electron impact

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.; Ponomarev, V. Yu.

    2016-03-01

    The cross sections and spin asymmetries for the excitation of 1- states in 208Pb by transversely polarized electrons with collision energy of 30-180MeV have been examined within the DWBA scattering formalism. As examples, we have considered a low-lying 1- state and also states belonging to the pygmy dipole and giant dipole resonances. The structure of these states and their corresponding transition charge and current densities have been taken from an RPA calculation within the quasiparticle phonon model. The complex-plane rotation method has been applied to achieve the convergence of the radial DWBA integrals for backward scattering. We have studied the behaviour of the cross sections and spin asymmetries as a function of electron energy and scattering angle. The role of the longitudinal and transversal contributions to the excitation has been thoroughly studied. We conclude that the spin asymmetry S, related to unpolarized outgoing electrons, is mostly well below 1% even at the backward scattering angles and its measurement provides a challenge for future experiments with polarized electrons.

  13. The influence of projectile neutron number in the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions

    SciTech Connect

    Dragojevic, Irena; Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Sudowe, R.; Nitsche, H.

    2008-07-11

    Four isotopes of rutherfordium,254-257Rf, were produced by the 208Pb(48Ti, xn)256-xRf and 208Pb(50Ti, xn)258-xRf reactions (x = 1, 2) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Excitation functions were measured for the 1n and 2n exit channels. A maximum likelihood technique, which correctly accounts for the changing cross section at all energies subtended by the targets, was used to fit the 1n data to allow a more direct comparison between excitation functions obtained under different experimental conditions. The maximum 1n crosssections of the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions obtained from fits to the experimental data are 0.38 +/- 0.07 nb and 40 +/-5 nb, respectively. Excitation functions for the 2n exit channel were also measured, with maximum cross sections of nb for the 48Ti induced reaction, and 15.7 +/- 0.2 nb for the 50Ti induced reaction. The impact of the two neutron difference in the projectile on the 1n cross section is discussed. The results are compared to the Fusion by Diffusion model developed by Swiatecki, Wilczynska, and Wilczynski.

  14. Chaos and Regularity in the Doubly Magic Nucleus 208Pb

    NASA Astrophysics Data System (ADS)

    Dietz, B.; Heusler, A.; Maier, K. H.; Richter, A.; Brown, B. A.

    2017-01-01

    High-resolution experiments have recently lead to a complete identification (energy, spin, and parity) of 151 nuclear levels up to an excitation energy of Ex=6.20 MeV in 208Pb [Heusler et al., Phys. Rev. C 93, 054321 (2016), 10.1103/PhysRevC.93.054321]. We present a thorough study of the fluctuation properties in the energy spectra of the unprecedented set of nuclear bound states. In a first approach, we group states with the same spin and parity into 14 subspectra, analyze standard statistical measures for short- and long-range correlations, i.e., the nearest-neighbor spacing distribution, the number variance Σ2, the Dyson-Mehta Δ3 statistics, and the novel distribution of the ratios of consecutive spacings of adjacent energy levels in each energy sequence, and then compute their ensemble average. Their comparison with a random matrix ensemble which interpolates between Poisson statistics expected for regular systems and the Gaussian orthogonal ensemble (GOE) predicted for chaotic systems shows that the data are well described by the GOE. In a second approach, following an idea of Rosenzweig and Porter [Phys. Rev. 120, 1698 (1960), 10.1103/PhysRev.120.1698], we consider the complete spectrum composed of the independent subspectra. We analyze their fluctuation properties using the method of Bayesian inference involving a quantitative measure, called the chaoticity parameter f , which also interpolates between Poisson (f =0 ) and GOE statistics (f =1 ). It turns out to be f ≈0.9 . This is so far the closest agreement with a GOE observed in the spectra of bound states in a nucleus. The same analysis is also performed with spectra computed on the basis of shell model calculations with different interactions (surface-delta interaction, Kuo-Brown, Michigan-three-Yukawa). While the simple surface-delta interaction exhibits features typical for nuclear many-body systems with regular dynamics, the other, more realistic interactions yield chaoticity parameters f close

  15. Measurements of neutron capture cross section for {sup 207,208}Pb

    SciTech Connect

    Segawa, M.; Toh, Y.; Harada, H.; Kitatani, F.; Koizumi, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Oshima, M.; Hatsukawa, Y.; Nagai, Y.; Igashira, M.; Kamada, S.; Tajika, M.

    2014-05-02

    The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The γ-rays cascaded from a capture state to the ground state or low-lying states of {sup 208,209}Pb were observed for the first time, using an anti-Compton Nal(Tl) spectrometer and a TOF method. The observed discrete γ-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish γ-ray of {sup 207,208}Pb(n,γ) reactions from background γ-ray with use of the γ-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

  16. Sensitivity of the electric dipole polarizability to the neutron skin thickness in {sup 208}Pb

    SciTech Connect

    Roca-Maza, X.; Agrawal, B. K.; Colo, G.; Nazarewicz, W.; Paar, N.; Piekarewicz, J.; Reinhard, P.-G.; Vretenar, D.

    2012-10-20

    The static dipole polarizability, {alpha}{sub D}, in {sup 208}Pb has been recently measured with highresolution via proton inelastic scattering at the Research Center for Nuclear Physics (RCNP) [1]. This observable is thought to be intimately connected with the neutron skin thickness, r{sub skin}, of the same nucleus and, more fundamentally, it is believed to be associated with the density dependence of the nuclear symmetry energy. The impact of r{sub skin} on {alpha}{sub D} in {sup 208}Pb is investigated and discussed on the basis of a large and representative set of relativistic and non-relativistic nuclear energy density functionals (EDF) [2].

  17. Two-parameter Fermi function fits to experimental charge and point-proton densities for 208Pb

    NASA Astrophysics Data System (ADS)

    Jones, Adam B.; Brown, B. Alex

    2014-12-01

    We use the model-independent experimental charge density for 208Pb to determine a model-independent point-proton density. An improved two-parameter Fermi function representation for the this point-proton density provides input for the analysis of experiments for the neutron density interpreted in terms of neutron skin and halo properties of 208Pb.

  18. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  19. Enhanced E1 transitions and {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2010-10-15

    We formulate a model for {sup 212}Po, based on the coupled-channels of {alpha}+{sup 208}Pb(0{sup +}) and {alpha}+{sup 208}Pb(3{sup -}) in which the {alpha}-Pb interaction contains scalar, quadrupole, and octupole terms. The model reproduces the recently observed enhanced E1 transitions from the several new negative-parity levels to the yrast states. Because these data are hard to understand in the shell model, this success gives a strong support for a unique role of {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po.

  20. Reanalysis of muonic {sup 90}Zr and {sup 208}Pb atoms

    SciTech Connect

    Haga, Akihiro; Toki, Hiroshi; Horikawa, Yataro

    2007-04-15

    Muonic transition energies in lowlying {mu}{sup -}-{sup 90}Zr and {mu}{sup -}-{sup 208}Pb states are reanalyzed by using nuclear polarization with the full-electromagnetic nuclear response. The possibility of the observed enhancement of the energy-weighted sum rule is also considered in the analysis. The transverse part of the nuclear polarization and the enhancement effect play an important role in improving the fine structure splitting of muonic p-states in both nuclei. Furthermore, introducing a pygmy dipole resonance in the excitation spectrum, the final fit drastically improves in {sup 208}Pb. However, there remains a discrepancy in {sup 90}Zr, for which the structure of the nuclear excitation spectrum is insensitive to the nuclear-polarization energy shift. Therefore, the remaining discrepancy might be caused by effects other than the nuclear polarization.

  1. Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

    SciTech Connect

    Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Gregorich, K.E.; Hoffman, D.C.; Nitsche, H.

    2010-03-19

    The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.

  2. Excitation energy dependence of the level density parameter close to the doubly magic 208Pb

    NASA Astrophysics Data System (ADS)

    Roy, Pratap; Banerjee, K.; Bhattacharya, C.; Pandey, R.; Sen, A.; Manna, S.; Kundu, S.; Rana, T. K.; Ghosh, T. K.; Mukherjee, G.; Roy, T.; Dhal, A.; Dey, A.; Meena, J. K.; Saha, A. K.; Pandit, Deepak; Mukhopadhyay, S.; Bhattacharya, S.

    2016-12-01

    Neutron evaporation spectra have been measured from 4He+208Pb and 4He+209Bi reactions by using 4He-ion beams of several bombarding energies. Excitation-energy dependence of the level density parameter has been studied for the two systems in the excitation energy range of ˜18 -50 MeV. For both the reactions an overall reduction of the asymptotic level density parameter with increasing excitation energy (temperature) is observed. The trend of the data was compared with the Thomas-Fermi model predictions and found to be in reasonable agreement. The value of the shell damping parameter has been extracted from the lowest-energy data in the case of Po,211210 and At,212211 nuclei close to the Z =82 and N =126 shell closure, and it was found to be consistent with the recent measurement in the vicinity of doubly magic 208Pb nucleus.

  3. Isoscalar giant dipole resonance in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb

    SciTech Connect

    Clark, H. L.; Lui, Y.-W.; Youngblood, D. H.

    2001-03-01

    Strength functions for isoscalar dipole excitations in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb have been measured with inelastic scattering of 240 MeV {alpha} particles at small angles. The isoscalar E1 strength distribution in each nucleus is found to consist of a broad component at E{sub x}{approx}114/A{sup 1/3}MeV containing approximately 100% of the E1 EWSR and a narrower one at E{sub x}{approx}72/A{sup 1/3}MeV containing 15--28% of the total isoscalar E1 strength. The higher component is the compression mode E1 strength previously reported only in {sup 208}Pb, whereas the lower component may be a new mode not reported previously, but suggested by recent RPA-HF and relativistic mean field calculations.

  4. Production and identification of new, neutron-rich nuclei in the [sup 208]Pb region

    SciTech Connect

    Rykaczewski, K. ); Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H. ); Kurpeta, J.; Pkochocki, A.; Karny, M.; Szerypo, J. ); Szerypo, J. ); Andreyev, H.; Huyse, M.; Wo uml; hr, A. ); Aystuml, J.; Nieminen, A.; Huhta, M. ); Walter, G. ) Hoff, P. )

    1998-12-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic [sup 208]Pb are briefly described. An identification of new neutron-rich isotopes [sup 215]Pb and [sup 217]Bi, and new decay properties of [sup 216]Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported. [copyright] [ital 1998 American Institute of Physics.

  5. Neutron skin of (208)Pb, nuclear symmetry energy, and the parity radius experiment.

    PubMed

    Roca-Maza, X; Centelles, M; Viñas, X; Warda, M

    2011-06-24

    A precise determination of the neutron skin Δr(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on (208)Pb. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δr(np) of (208)Pb from the parity-violating asymmetry A(PV) probed in the experiment. We demonstrate a high linear correlation between A(PV) and Δr(np) in successful mean field forces as the best means to constrain the neutron skin of (208)Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A(PV) is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.

  6. Precise measurement of near-barrier 8He+208Pb elastic scattering: Comparison with 6He

    NASA Astrophysics Data System (ADS)

    Marquínez-Durán, G.; Martel, I.; Sánchez-Benítez, A. M.; Acosta, L.; Berjillos, R.; Dueñas, J.; Rusek, K.; Keeley, N.; Álvarez, M. A. G.; Borge, M. J. G.; Chbihi, A.; Cruz, C.; Cubero, M.; Fernández-García, J. P.; Fernández-Martínez, B.; Flores, J. L.; Gómez-Camacho, J.; Kemper, K. W.; Labrador, J. A.; Marqués, M.; Moro, A. M.; Mazzocco, M.; Pakou, A.; Parkar, V. V.; Patronis, N.; Pesudo, V.; Pierroutsakou, D.; Raabe, R.; Silvestri, R.; Soic, N.; Standyło, Ł.; Strojek, I.; Tengblad, O.; Wolski, R.; Abou-Haidar, Z.

    2016-12-01

    Dramatic differences in the elastic scattering of the neutron rich nuclei 6He and 8He are found when new high quality data for the 8He+208Pb system are compared with previously published 6He+208Pb data at the same laboratory frame incident energy. The new 8He data are of the same level of detail as for stable beams. When comparing them with those previously obtained for 6He+208Pb at the same energy, it is possible to determine from the data alone that 6He has a much longer range absorption than 8He. However, both nuclei show significant absorption beyond their strong absorption radii. While it has been known for a long time that elastic scattering at energies around the barrier only determines the optical potential over a small distance in radial space, typically ±0.5 fm or so, both the 6He and the 8He imaginary potentials obtained from various optical model fits to these data are the same over a much wider range of ±1.5 fm.

  7. Influence of single-neutron stripping on near-barrier 6He+208Pb and 8He+208Pb elastic scattering

    NASA Astrophysics Data System (ADS)

    Marquínez-Durán, G.; Keeley, N.; Kemper, K. W.; Mackintosh, R. S.; Martel, I.; Rusek, K.; Sánchez-Benítez, A. M.

    2017-02-01

    The influence of single-neutron stripping on the near-barrier elastic scattering angular distributions for the He,86+208Pb systems is investigated through coupled reaction channels (CRC) calculations fitting recently published data to explore the differences in the absorptive potential found in the scattering of these two neutron-rich nuclei. The inclusion of the coupling reduces the elastic cross section in the Coulomb-nuclear interference region for 8He scattering, whereas for 6He its major impact is on the large-angle elastic scattering. The real and imaginary dynamic polarization potentials are obtained by inverting the CRC elastic scattering S -matrix elements. These show that the main absorptive features occur between 11 and 12 fm for both projectiles, while the attractive features are separated by about 1 fm, with their main structures occurring at 10.5 fm for 6He and 11.5 fm for 8He.

  8. Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

    We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

  9. Neutron skins of 208Pb and 48Ca from pionic probes

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2012-12-01

    The neutron skin of 208Pb has received considerable attention in recent years. A variety of strongly-interacting probes depict a rather consistent picture but pionic probes have not been referred to in this context. We present here neutron-skin values from pionic atoms and from total reaction cross sections of π+ between 0.7 and 2 GeV/c which fit well into the picture. In addition we show that a neutron-skin for 48Ca can be obtained from existing data on pionic atoms and the result agrees with pion scattering experiments and with the scattering of α particles.

  10. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    DOE PAGES

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  11. Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering

    DOE PAGES

    Abrahamyan, Sergey; Albataineh, Hisham; Aniol, Konrad; ...

    2012-03-15

    We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV = 0.656 ± 0.060 (stat) ± 0.013 (syst) corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp = 0.33-0.18+0.16 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

  12. The pairing correlation study in the {sup 40}Ar+{sup 208}Pb reaction

    SciTech Connect

    Mijatović, T. Szilner, S.; Malenica, D. Jelavić; Prepolec, L.; Soić, N.; Tokić, V.; Corradi, L.; Fioretto, E.; Goasduff, A.; Stefanini, A. M.; Dobón, J. J. Valiente; Montanari, D.; Courtin, S.; Haas, F.; Montagnoli, G.; Scarlassara, F.; Ur, C. A.; Pollarolo, G.

    2015-10-15

    The multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been measured at E{sub lab} = 260 MeV with the large solid angle magnetic spectrometer PRISMA. Mass and charge yields, differential and total cross sections, total kinetic energy loss distributions of different channels were simultaneously studied. Angular distributions were measured in a wide angular range by matching three different angular settings of the spectrometer. Absolute cross sections were obtained after the response function of the spectrometer was evaluated. These cross sections for different transfer channels allow the discussion of the role played by nucleon-nucleon correlations.

  13. Sub-Barrier Fusion in the HI + 208Pb Systems and Nuclear Potentials for Cluster Decay

    SciTech Connect

    Sagaidak, R.N.; Tretyakova, S.P.; Khlebnikov, S.V.; Ogloblin, A.A.; Rowley, N.

    2005-11-21

    Near-barrier fusion excitation functions for the 12,14C, 16,18O + 208Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th, i.e., for the inverse decay process. The analysis supports the 'alpha-decay-like' scenario for carbon and oxygen emission from these nuclei.

  14. Multinucleon transfer processes in {sup 40}Ca+{sup 208}Pb

    SciTech Connect

    Szilner, S.; Corradi, L.; Behera, B.R.; Fioretto, E.; Gadea, A.; Latina, A.; Stefanini, A.M.; Trotta, M.; Vinodkumar, A.M.; Wu, Y.; Pollarolo, G.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Haas, F.

    2005-04-01

    Multinucleon transfer reactions in {sup 40}Ca+{sup 208}Pb have been studied at bombarding energies close to the Coulomb barrier. Projectilelike fragments have been identified in nuclear mass and charge with a time-of-flight spectrometer. Angular and total kinetic energy loss distributions and inclusive cross sections have been compared with those of semiclassical models. The analysis shows that a successive transfer mechanism of single nucleons does not account for the data, and a direct nucleon pair transfer has to be included in the description. Nucleon evaporation effects are taken into account.

  15. The pygmy dipole strength, the neutron radius of 208Pb and the symmetry energy

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Brenna, M.; Centelles, M.; Colò, G.; Mizuyama, K.; Pozzi, G.; Viñas, X.; Warda, M.

    2012-02-01

    The accurate characterization of the nuclear symmetry energy and its density dependence is one of the outstanding open problems in nuclear physics. A promising nuclear observable in order to constrain the density dependence of the symmetry energy at saturation is the neutron skin thickness of medium and heavy nuclei. Recently, a low-energy peak in the isovector dipole response of neutron-rich nuclei has been discovered that may be correlated with the neutron skin thickness. The existence of this correlation is currently under debate due to our limited experimental knowledge on the microscopic structure of such a peak. We present a detailed analysis of Skyrme Hartree-Fock (HF) plus random phase approximation (RPA) predictions for the dipole response in several neutron-rich nuclei and try to elucidate whether models of common use in nuclear physics confirm or dismiss its possible connection with the neutron skin thickness. Finally, we briefly present theoretical results for parity violating electron scattering on 208Pb at the conditions of the PREx experiment and discuss the implications for the neutron skin thickness of 208Pb and the slope of the symmetry energy.

  16. Diversity of neutron star properties at the fixed neutron-skin thickness of 208Pb

    NASA Astrophysics Data System (ADS)

    Alam, N.; Sulaksono, A.; Agrawal, B. K.

    2015-07-01

    We study the diversities in the properties of the neutron stars arising due to the different choices for the cross coupling between various mesons, which governs the density dependence of the nuclear symmetry energy in the extended relativistic mean-field (RMF) model. For this purpose, we obtain two different families of the extended RMF model corresponding to different nonlinear cross-coupling terms in the isovector part of the effective Lagrangian density. The lowest-order contributions for the δ mesons are also included. The different models within the same family yield wide variation in the value of neutron-skin thickness in the 208Pb nucleus. These models are employed to compute the neutron-star properties such as core-crust transition density, radius and red shift at canonical mass ( 1.4 M⊙) , tidal polarizability parameter, and threshold mass required for the enhanced cooling through the direct Urca process. Most of the neutron-star properties considered are significantly different(10-40%) for the different families of models at a smaller neutron-skin thickness (˜0.15 fm ) in the 208Pb nucleus.

  17. Examination of experimental evidence of chaos in the bound states of 208Pb

    NASA Astrophysics Data System (ADS)

    Muñoz, L.; Molina, R. A.; Gómez, J. M. G.; Heusler, A.

    2017-01-01

    We study the spectral fluctuations of the 208Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.20 MeV recently identified at the Maier-Leibnitz Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of random matrix theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω , which takes the value ω =0 for regular systems and ω ≃1 for chaotic systems. We obtain ω =0.85 which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in 208Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition, our results show that chaotic and nonchaotic nuclear states coexist in the same energy region of the spectrum.

  18. Concerning advantages in using 208Pb as such a FR coolant

    NASA Astrophysics Data System (ADS)

    Khorasanov, G.; Zemskov, E.; Blokhin, A.

    2017-01-01

    In the paper cores of two fast reactors with heavy liquid metal coolant are considered. The first object, RBETS-M, is a project of a medium power, 900 MW, reactor cooled with lead-bismuth. The second object, BRUTS, is a project of an ultra-small power, 0.5 MW, reactor cooled with lead. The results of replacement of their standard coolants with the lead coolant enriched up to 100% with 208Pb are presented. In the RBETS-M core having a large coolant volume share this replacement results in sufficient increasing the share of 238U involved in the fission process and respective decreasing the share of 239Pu and 241Pu burning.

  19. Light charged particles emitted in fission reactions induced by protons on 208Pb

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Paradela, C.; Ayyad, Y.; Casarejos, E.; Alvarez-Pol, H.; Audouin, L.; Bélier, G.; Boutoux, G.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Taïeb, J.; Vargas, J.; Voss, B.

    2016-09-01

    Light charged particles emitted in proton-induced fission reactions on 208Pb have been measured at different kinetic energies: 370 A ,500 A , and 650 A MeV. The experiment was performed by the SOFIA Collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light charged particles in coincidence with fission fragments. This measurement allowed us, for the first time, to obtain correlations between the light charged particles emitted during the fission process and the charge distributions of the fission fragments. These correlations were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.

  20. Search for deeply bound pionic states in 208Pb via radiative atomic capture of negative pions

    NASA Astrophysics Data System (ADS)

    Raywood, K. J.; Lange, J. B.; Jones, G.; Pavan, M.; Sevior, M. E.; Hutcheon, D. A.; Olin, A.; Ottewell, D.; Yen, S.; Lee, S. J.; Sim, K. S.; Altman, A.; Friedman, E.; Trudel, A.

    1997-05-01

    A search for narrow, deeply bound pionic atom states via atomic radiative capture of negative pions in a target of 208Pb was carried out for pion kinetic energies of 20 and 25 MeV. Although no clear signature of any such gamma ray emission could be observed in the data, fits of the gamma ray spectra between the energies of 12 and 42 MeV involving a quadratic background together with a pair of peaks (1s, 2p) whose relative intensity was taken from theory yielded an overall strength for the peaks which are consistent (to a 67% confidence level) with radiative capture whose integrated cross section is 20.0 +/- 10.0 μb/sr at 90° for 20 MeV incident pions. A lower probability (40% confidence level) result was obtained when the fit was carried out without the peaks included, just the continuum background.

  1. Observation of Superheavy Nuclei Produced in the Reaction of 86Kr with 208Pb

    NASA Astrophysics Data System (ADS)

    Ninov, V.; Gregorich, K. E.; Loveland, W.; Ghiorso, A.; Hoffman, D. C.; Lee, D. M.; Nitsche, H.; Swiatecki, W. J.; Kirbach, U. W.; Laue, C. A.; Adams, J. L.; Patin, J. B.; Shaughnessy, D. A.; Strellis, D. A.; Wilk, P. A.

    1999-08-01

    Following a prediction by Smolan´czuk [Phys. Rev. C 59, 2634 (1999)], we searched for superheavy element formation in the bombardment of 208Pb with 449-MeV 86Kr ions. We have observed three decay chains, each consisting of an implanted heavy atom and six subsequent α decays, correlated in time and position. In these decay chains, a rapid (ms) sequence of high energy α particles ( Eα>=10 MeV) indicates the decay of a new high- Z element. The observed chains are consistent with the formation of 293118 and its decay by sequential α-particle emission to 289116, 285114, 281112, 277110, 273Hs ( Z = 108) and 269Sg ( Z = 106). The production cross section is 2.2+2.6-0.8 pb.

  2. Power of two: Assessing the impact of a second measurement of the weak-charge form factor of 208Pb

    NASA Astrophysics Data System (ADS)

    Piekarewicz, J.; Linero, A. R.; Giuliani, P.; Chicken, E.

    2016-09-01

    Background: Besides its intrinsic value as a fundamental nuclear-structure observable, the weak-charge density of 208Pb—a quantity that is closely related to its neutron distribution—is of fundamental importance in constraining the equation of state of neutron-rich matter. Purpose: To assess the impact that a second electroweak measurement of the weak-charge form factor of 208Pb may have on the determination of its overall weak-charge density. Methods: Using the two putative experimental values of the form factor, together with a simple implementation of Bayes' theorem, we calibrate a theoretically sound—yet surprisingly little known—symmetrized Fermi function, that is characterized by a density and form factor that are both known exactly in closed form. Results: Using the charge form factor of 208Pb as a proxy for its weak-charge form factor, we demonstrate that using only two experimental points to calibrate the symmetrized Fermi function is sufficient to accurately reproduce the experimental charge form factor over a significant range of momentum transfers. Conclusions: It is demonstrated that a second measurement of the weak-charge form factor of 208Pb supplemented by a robust theoretical input in the form of the symmetrized Fermi function would place significant constraints on the neutron distribution of 208Pb. In turn, such constraints will become vital in the interpretation of hadronic experiments that will probe the neutron-rich skin of exotic nuclei at future radioactive beam facilities.

  3. Complete dipole response in {sup 208}Pb from high-resolution polarized proton scattering at 0 deg

    SciTech Connect

    Neumann-Cosel, P. von; Kalmykov, Y.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Matsubara, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Bertulani, C. A.; Carter, J.; Fujita, H.; Dozono, M.; Fujita, K.; Hashimoto, H.; Hatanaka, K.

    2009-01-28

    The structure of electric and magnetic dipole modes in {sup 208}Pb is investigated in a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg. First results on the E1 strength in the region of the pygmy dipole resonance are reported.

  4. γ -ray spectroscopy of fission fragments produced in 208Pb(18O ,f )

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Ganguly, S.; Pradhan, M. K.; Moin Shaikh, Md.; Sharma, H. P.; Chakraborty, S.; Palit, R.; Pillay, R. G.; Nanal, V.; Saha, S.; Sethi, J.; Biswas, D. C.

    2015-08-01

    Prompt gamma-ray spectroscopy of fission fragments produced in the heavy-ion induced fusion-fission reaction 208Pb(18O,f ) at E =90 MeV has been performed. The relative isotopic yields of the fission fragments and the fragment mass distribution have been studied. Structures in the mass distribution have been discussed in the light of earlier results. Relative yields of several odd-A isotopes of Mo, Ru, Pd, and Cd and the odd-A isotones with N =62 and 64 have been studied along with the yields of the neighboring even-Z , even-N fragments and correlated to nuclear structural effects. The average total neutron multiplicity during fission has been measured to be 5.48 ±0.59 . The level schemes of the two neutron-rich nuclei 110Pd and 116Cd have been studied from γ -ray triple coincidence data. A large number of transitions, previously reported only from β -decay studies, have been observed in 110Pd for the first time. The yrast band in 116Cd has been extended up to spin (16+). In addition, a rotational sequence built upon an excited 5- state in 116Cd has been observed up to (13-). The level schemes have been discussed in the context of existing results, both experimental and theoretical, in the literature.

  5. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    SciTech Connect

    Broda, R.; Wrzesinski, J.; Pawlat, T.

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  6. Neutron-Rich Isotopes from 208Pb at 86 MeV/u

    NASA Astrophysics Data System (ADS)

    Tarasov, O. B.; Portillo, M.; Amthor, A. M.; Baumann, T.; Bazin, D.; Folden, C.; Ginter, T.; Hausmann, M.; Morrissey, D. J.; Pereira, J.; Sherrill, B. M.; Thoennessen, M.; Nociforo, C.

    2008-10-01

    An experiment to measure production yields from a beam of ^208Pb (86 MeV/u) on Be and Ni-targets has recently been performed. The A1900 fragment-separator [1] was used to analyze products from projectile fragmentation and abrasion-fission [2]. Isotopic identification of nuclides having A˜200 has been achieved, demonstrating that adequate A,Z,Q resolution at this energy region is possible when using silicon detectors. The verification of PID is done via detection of multiple charge state distributions of the primary beam, as well as γ-decay of known isomers with half-lives in the microsecond range. The results demonstrate that experiments with heavy nuclei are possible at the NSCL using beams of A>200. Production cross-sections have been extracted from the data that can help improve the accuracy of production models such as Abrasion-Ablation and Abrasion-Fission used in the LISE++ code [3]. The data reveal the existence of previously unreported isomeric transitions and further analysis is ongoing that may also lead to the observation of new isotopes. References: [1] D.J.Morrissey et al., Nucl. Instrum. Meth. B204 (2003) 90--96. [2] O.B. Tarasov, Tech. Rep. MSUCL1300, NSCL, Michigan St.Univ., 2005. [3] O.B. Tarasov, D. Bazin, Nucl. Phys. A 746 (2004) 411; www.nscl.msu.edu/lise .

  7. Hindrance of complete fusion in the {sup 8}Li+{sup 208}Pb system at above-barrier energies

    SciTech Connect

    Aguilera, E. F.; Martinez-Quiroz, E.; Rosales, P.; Kolata, J. J.; DeYoung, P. A.; Peaslee, G. F.; Mears, P.; Guess, C.; Becchetti, F. D.; Lupton, J. H.; Chen, Yu

    2009-10-15

    The {sup 211,212}At yields resulting from the interaction of the radioactive projectile {sup 8}Li with a {sup 208}Pb target have been measured at energies between 3 and 8.5 MeV above the Coulomb barrier. They are signatures for fusion of the whole charge but not necessarily the whole mass of the projectile, so they are included in a corresponding operational definition of complete fusion. Within this definition, a fusion suppression factor of 0.70{+-}0.02 (stat.) {+-}0.04 (syst.) is deduced from a comparison to a one-dimensional barrier-penetration-model calculation using parameters extrapolated from values for {sup 6,7}Li+{sup 209}Bi and {sup 9}Be+{sup 208}Pb taken from the literature. Possible incomplete fusion processes are discussed and the results are fitted with a phenomenological model assuming breakup prior to fusion followed by capture of a {sup 7}Li fragment.

  8. Complete dipole strength distributions in 208Pb from high-resolution polarized proton scattering at 0°

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, Peter

    2012-02-01

    Small-angle polarized proton scattering including 0° at incident energies of a few 100 MeV/nucleon is established as a new spectrospcopic tool for the study of E1 and M1 strength distributions. Experiments of this type have been realized recently at RCNP, Osaka, Japan with high energy resolution of the order 25 - 30 keV (FWHM). Using 208Pb as an example, the physics potential of such data is discussed. It includes information on the properties of the Pygmy Dipole Resonance but also on complete E1 and M1 strength distributions and thus the gamma strength function. The E1 polarizability can be extracted with a precision of about 4% providing important experimental constraints on the neutron skin thickness in 208Pb.

  9. Measurement of the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg excitation function

    SciTech Connect

    Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nelson, S. L.; Hoffman, D. C.; Nitsche, H.; Duellmann, Ch. E.; Sudowe, R.; Gregorich, K. E.; Eichler, R.

    2009-02-15

    The excitation function for the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of 320{sub -100}{sup +110} pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from {sup 259}Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the {sup 208}Pb({sup 52}Cr,2n){sup 258}Sg reaction was obtained, and an improved {sup 258}Sg half-life of 2.6{sub -0.4}{sup +0.6} ms was calculated by combining all available experimental data.

  10. Isospin character of low-lying pygmy dipole states in 208Pb via inelastic scattering of 17O ions.

    PubMed

    Crespi, F C L; Bracco, A; Nicolini, R; Mengoni, D; Pellegri, L; Lanza, E G; Leoni, S; Maj, A; Kmiecik, M; Avigo, R; Benzoni, G; Blasi, N; Boiano, C; Bottoni, S; Brambilla, S; Camera, F; Ceruti, S; Giaz, A; Million, B; Morales, A I; Vandone, V; Wieland, O; Bednarczyk, P; Ciemała, M; Grebosz, J; Krzysiek, M; Mazurek, K; Zieblinski, M; Bazzacco, D; Bellato, M; Birkenbach, B; Bortolato, D; Calore, E; Cederwall, B; Charles, L; de Angelis, G; Désesquelles, P; Eberth, J; Farnea, E; Gadea, A; Görgen, A; Gottardo, A; Isocrate, R; Jolie, J; Jungclaus, A; Karkour, N; Korten, W; Menegazzo, R; Michelagnoli, C; Molini, P; Napoli, D R; Pullia, A; Recchia, F; Reiter, P; Rosso, D; Sahin, E; Salsac, M D; Siebeck, B; Siem, S; Simpson, J; Söderström, P-A; Stezowski, O; Theisen, Ch; Ur, C; Valiente-Dobón, J J

    2014-07-04

    The properties of pygmy dipole states in 208Pb were investigated using the 208Pb(17O, 17O'γ) reaction at 340 MeV and measuring the γ decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted γ rays and of the scattered particles were measured. The results are compared with (γ, γ') and (p, p') data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2+ and 3- states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1- excited states from 4 to 8 MeV.

  11. Total fission cross section of {sup 181}Ta and {sup 208}Pb induced by protons at relativistic energies

    SciTech Connect

    Ayyad, Y.; Benlliure, J.; Casarejos, E.; Schmidt, K. H.; Jurado, B.; Pol, H. A.; Ricciardi, M. V.; Pleskac, R.; Enqvist, T.; Rejmund, F.; Giot, L.; Henzl, V.; Lukic, S.; Ngoc, S. N.; Boudard, A.; Leray, S.; Kurtukian, T.; Schmitt, C.; Henzlova, D.; Paradela, C.; Bacquias, A.; Loureiro, D. P.; Foehr, V.; Tarrio, D.; Kezzar, K.

    2011-07-01

    Total fission cross section induced by protons in {sup 181}Ta and {sup 208}Pb at energies in the range of 300 to 1000 A MeV have been measured at GSI (Germany) using the inverse kinematics technique. A dedicated setup with high efficiency made it possible to determine these cross sections with high accuracy. The new data seed light in the controversial results obtained so far and contribute to the understanding of the fission process at high excitation energies. (authors)

  12. γ strength function and level density of 208Pb from forward-angle proton scattering at 295 MeV

    NASA Astrophysics Data System (ADS)

    Bassauer, S.; von Neumann-Cosel, P.; Tamii, A.

    2016-11-01

    Background: γ strength functions (GSFs) and level densities (LDs) are essential ingredients of statistical nuclear reaction theory with many applications in astrophysics, reactor design, and waste transmutation. Purpose: The aim of the present work is a test of systematic parametrizations of the GSF recommended by the RIPL-3 database for the case of 208Pb. The upward GSF and LD in 208Pb are compared to γ decay data from an Oslo-type experiment to examine the validity of the Brink-Axel (BA) hypothesis. Methods: The E 1 and M1 parts of the total GSF are determined from high-resolution forward angle inelastic proton scattering data taken at 295 MeV at the Research Center for Nuclear Physics (RCNP), Osaka, Japan. The total LD in 208Pb is derived from the 1- LD extracted with a fluctuation analysis in the energy region of the isovector giant dipole resonance. Results: The E 1 GSF is compared to parametrizations recommended by the RIPL-3 database showing systematic deficiencies of all models in the energy region around neutron threshold. The new data for the poorly known spin-flip M 1 resonance call for a substantial revision of the model suggested in RIPL-3. The total GSF derived from the present data is larger in the PDR energy region than the Oslo data but the strong fluctuations due to the low LD resulting from the double shell closure of 208Pb prevent a conclusion on a possible violation of the BA hypothesis. Using the parameters suggested by RIPL-3 for a description of the LD in 208Pb with the back-shifted Fermi gas model, remarkable agreement between the two experiments spanning a wide excitation energy range is obtained. Conclusions: Systematic parametrizations of the E 1 and M 1 GSF parts need to be reconsidered at low excitation energies. The good agreement of the LD provides an independent confirmation of the approach underlying the decomposition of GSF and LD in Oslo-type experiments.

  13. Weak charge form factor and radius of 208Pb through parity violation in electron scattering

    DOE PAGES

    Horowitz, C. J.; Ahmed, Z.; Jen, C. -M.; ...

    2012-03-26

    We use distorted wave electron scattering calculations to extract the weak charge form factor FW(more » $$\\bar{q}$$), the weak charge radius RW, and the point neutron radius Rn, of 208Pb from the PREX parity violating asymmetry measurement. The form factor is the Fourier transform of the weak charge density at the average momentum transfer $$\\bar{q}$$ = 0.475 fm-1. We find FW($$\\bar{q}$$) = 0.204 ± 0.028(exp) ± 0.001(model). We use the Helm model to infer the weak radius from FW($$\\bar{q}$$). We find RW = 5.826 ± 0.181(exp) ± 0.027(model) fm. Here the exp error includes PREX statistical and systematic errors, while the model error describes the uncertainty in RW from uncertainties in the surface thickness σ of the weak charge density. The weak radius is larger than the charge radius, implying a 'weak charge skin' where the surface region is relatively enriched in weak charges compared to (electromagnetic) charges. We extract the point neutron radius Rn = 5.751 ± 0.175 (exp) ± 0.026(model) ± 0.005(strange) fm, from RW. Here there is only a very small error (strange) from possible strange quark contributions. We find Rn to be slightly smaller than RW because of the nucleon's size. As a result, we find a neutron skin thickness of Rn-Rp = 0.302 ± 0.175 (exp) ± 0.026 (model) ± 0.005 (strange) fm, where Rp is the point proton radius.« less

  14. Dipole response in 208Pb within a self-consistent multiphonon approach

    NASA Astrophysics Data System (ADS)

    Knapp, F.; Lo Iudice, N.; Veselý, P.; Andreozzi, F.; De Gregorio, G.; Porrino, A.

    2015-11-01

    Background: The electric dipole strength detected around the particle threshold and commonly associated with the pygmy dipole resonance offers unique information on neutron skin and symmetry energy, and is of astrophysical interest. The nature of such a resonance is still under debate. Purpose: We intend to describe the giant and pygmy resonances in 208Pb by enhancing their fragmentation with respect to the random-phase approximation. Method: We adopt the equation of motion phonon method to perform a fully self-consistent calculation in a space spanned by one-phonon and two-phonon basis states using an optimized chiral two-body potential. A phenomenological density-dependent term, derived from a contact three-body force, is added to get single-particle spectra more realistic than the ones obtained by using the chiral potential only. The calculation takes into full account the Pauli principle and is free of spurious center-of-mass admixtures. Results: We obtain a fair description of the giant resonance and obtain a dense low-lying spectrum in qualitative agreement with the experimental data. The transition densities as well as the phonon and particle-hole composition of the most strongly excited states support the pygmy nature of the low-lying resonance. Finally, we obtain realistic values for the dipole polarizability and the neutron skin radius. Conclusions: The results emphasize the role of the two-phonon states in enhancing the fragmentation of the strength in the giant resonance region and at low energy, consistently with experiments. For a more detailed agreement with the data, the calculation suggests the inclusion of the three-phonon states as well as a fine tuning of the single-particle spectrum to be obtained by a refinement of the nuclear potential.

  15. Pionic fusion near threshold using the /sup 208/Pb(/sup 3/He,. pi. /sup -/)/sup 211/At reaction

    SciTech Connect

    Ward, T.E.

    1987-12-01

    The coherent production of pions in the /sup 208/Pb(/sup 3/He,..pi../sup -/)/sup 211/At reaction was measured radiochemically using activation techniques near the physical pion threshold at energies of 158--270 MeV. Above threshold, the total cross sections were measured in the 1--10 nb range. A theoretical fit of the summed total cross section into all particle bound states was made using the two-nucleon model of Dillig with appropriate two-body scaling of the momentum transfer.

  16. Study of the γ decay of high-lying states in 208Pb via inelastic scattering of 17O ions

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Kmiecik, M.; Bracco, A.; Leoni, S.; Maj, A.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemala, M.; Grebosz, J.; Krzysiek, M.; Mazurek, K.; Zieblinski, M.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; De Angelis, G.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Isocrate, R.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Recchia, F.; Sahin, E.; Siebeck, B.; Siem, S.; Ur, C.; Valiente Dobon, J. J.

    2014-03-01

    A measurement of the high-lying states in 208Pb has been made using 17O beams at 20 MeV/u. The gamma decay following inelastic excitation was measured with the detector system AGATA Demonstrator based on segmented HPGe detectors, coupled to an array of large volume LaBr3:Ce scintillators and to an array of Si detectors. Preliminary results in comparison with (γ,γ') data, for states in the 5-8 MeV energy interval, are presented.

  17. Response function of the magnetic spectrometer PRISMA for the multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb

    SciTech Connect

    Mijatovic, T.; Szilner, S.; Corradi, L.; Courtin, S.; Farnea, E.; Fioretto, E.; Gadea, A.; Goasduff, A.; Haas, F.; Jelavic-Malenica, D.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Montanari, D.; Pollarolo, G.; Recchia, F.; Sahin, E.; Scarlassara, F.; Soic, N.; Stefanini, A. M.; and others

    2012-10-20

    Multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been investigated with the PRISMA-CLARA experimental setup in LNL, INFN, Italy. The experimental differential cross sections have been obtained for different transfer channels by measuring more than {Delta}{theta}{sub lab} = 20 Degree-Sign covered by three angular settings of PRISMA. Results have been compared with the semiclassical calculation GRAZING. Since the understanding of the reaction mechanism depends strongly on the determination of absolute cross section, effect of transport of ions through PRISMA has been studied via a Monte Carlo simulation code.

  18. Nuclear spectroscopy study of the isotopes populated via multinucleon transfer in the 90Zr + 208Pb reaction

    SciTech Connect

    Ur, C. A.; Corradi, L.; Stefanini, A. M.; Behera, B. R.; Fioretto, E.; Gadea, A.; Latina, A.; Szilner, S.; Beghini, S.; Farnea, E.; Montagnoli, G.; Scarlassara, F.; Haas, F.; Pollarolo, G.

    2006-08-14

    The present work takes advantage of the multinucleon transfer mechanism between heavy reaction partners to study the population pattern of excited nuclear states in near spherical Zirconium isotopes following the 90Zr + 208Pb reaction at an energy closed to the Coulomb barrier. Both the projectile and the target are well known closed shell nuclei offering an optimum situation for clean experimental and theoretical conditions. Total kinetic energy loss (TKEL) distributions were compared with calculations performed with the GRAZING code. The ability to use the TKEL as a selection tool for the states at different excitation energies was shown.

  19. (. pi. sup +- ,. pi. sup +- prime N) reactions on sup 12 C and sup 208 Pb near the giant resonance region

    SciTech Connect

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the {sup 12}C({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p) and {sup 208}Pb({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p or n) reactions near the giant resonance region have been measured at T{sub {pi}} = 180 MeV, and found different between {pi}{sup +} and {pi}{sup {minus}} data. This observation is interpreted as evidence for different excitation mechanisms dominating the {pi}{sup {minus}}-nucleus and {pi}{sup +}-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate ({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} N) data for both targets, the dominance of direct process for ({pi}{sup +}, {pi}{sup {plus}}{prime} p) or ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} n) in contrast to ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) or ({pi}{sup +}, {pi}{sup +}{prime} n). In the ({pi}{sup +}, {pi}{sup +}{prime} p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus.

  20. Multinucleon transfer in O,1816,19F+208Pb reactions at energies near the fusion barrier

    NASA Astrophysics Data System (ADS)

    Rafferty, D. C.; Dasgupta, M.; Hinde, D. J.; Simenel, C.; Simpson, E. C.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; McNeil, S. D.; Ramachandran, K.; Vo-Phuoc, K.; Wakhle, A.

    2016-08-01

    Background: Nuclear reactions are complex, involving collisions between composite systems where many-body dynamics determines outcomes. Successful models have been developed to explain particular reaction outcomes in distinct energy and mass regimes, but a unifying picture remains elusive. The irreversible transfer of kinetic energy from the relative motion of the collision partners to their internal states, as is known to occur in deep inelastic collisions, has yet to be successfully incorporated explicitly into fully quantal reaction models. The influence of these processes on fusion is not yet quantitatively understood. Purpose: To investigate the population of high excitation energies in transfer reactions at sub-barrier energies, which are precursors to deep inelastic processes, and their dependence on the internuclear separation. Methods: Transfer probabilities and excitation energy spectra have been measured in collisions of O,1816,19F+208Pb , at various energies below and around the fusion barrier, by detecting the backscattered projectile-like fragments in a Δ E -E telescope. Results: The relative yields of different transfer outcomes are strongly driven by Q values, but change with the internuclear separation. In 16O+208Pb , single nucleon transfer dominates, with a strong contribution from -2 p transfer close to the Coulomb barrier, though this channel becomes less significant in relation to the -2 p 2 n transfer channel at larger separations. For 18O+208Pb , the -2 p 2 n channel is the dominant charge transfer mode at all separations. In the reactions with 19F,-3 p 2 n transfer is significant close to the barrier, but falls off rapidly with energy. Multinucleon transfer processes are shown to lead to high excitation energies (up to ˜15 MeV), which is distinct from single nucleon transfer modes which predominantly populate states at low excitation energy. Conclusions: Kinetic energy is transferred into internal excitations following transfer, with this

  1. First observation of high-spin states in {sup 214}Po: Probing the valence space beyond {sup 208}Pb

    SciTech Connect

    Astier, Alain; Porquet, Marie-Genevieve

    2011-01-15

    Excited states in {sup 214}Po have been populated using the {sup 18}O + {sup 208}Pb reaction at 85-MeV beam energy and studied with the Euroball IV {gamma}-multidetector array. The level scheme has been built up to {approx}2.7-MeV excitation energy and spin I=12({h_bar}/2{pi}) from the triple-{gamma} coincidence data. Spin and parity values of most of the observed states have been assigned from the {gamma}-angular properties. The configurations of the yrast states are discussed using results of empirical shell-model calculations and by analogy with the neighboring nuclei. The {sup 214}Po level scheme established in this work constitutes an important step for the determination of the effective nucleon-nucleon interactions beyond N=126.

  2. Similarity of nuclear structure in the {sup 132}Sn and {sup 208}Pb regions: Proton-neutron multiplets

    SciTech Connect

    Coraggio, L.; Gargano, A.; Covello, A.; Itaco, N.

    2009-08-15

    Starting from the striking similarity of proton-neutron multiplets in {sup 134}Sb and {sup 210}Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V{sub low-k} approach. The calculated results for {sup 136}Sb, {sup 212}Bi, {sup 136}I, and {sup 212}At are in very good agreement with the available experimental data. The similarity between {sup 132}Sn and {sup 208}Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.

  3. Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements.

    PubMed

    Allmond, J M; Stuchbery, A E; Beene, J R; Galindo-Uribarri, A; Liang, J F; Padilla-Rodal, E; Radford, D C; Varner, R L; Ayres, A; Batchelder, J C; Bey, A; Bingham, C R; Howard, M E; Jones, K L; Manning, B; Mueller, P E; Nesaraja, C D; Pain, S D; Peters, W A; Ratkiewicz, A; Schmitt, K T; Shapira, D; Smith, M S; Stone, N J; Stracener, D W; Yu, C-H

    2014-05-02

    Single-neutron states in (133)Sn and (209)Pb, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the ((9)Be, (8)Be) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence spectroscopy. In addition, the s(1/2) single-neutron hole-state candidate in (131)Sn was populated by ((9)Be, (10)Be). Doubly closed-shell (132)Sn (radioactive) and (208)Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, γ-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared with shell-model expectations. The results include a new transition and precise level energy for the 3p(1/2) candidate in (133)Sn, new absolute cross sections for the 1h(9/2) candidate in (133)Sn and 3s(1/2) candidate in (131)Sn, and new lifetimes for excited states in (133)Sn and (209)Pb. This is the first report on excited-state lifetimes of (133)Sn, which allow for a unique test of the nuclear shell model and (132)Sn double-shell closure.

  4. Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements

    SciTech Connect

    Allmond, James M; Stuchbery, Andrew E; Beene, James R; Galindo-Uribarri, Alfredo {nmn}; Liang, J Felix; Padilla-Rodal, Elizabeth; Radford, David C; Varner Jr, Robert L; Ayres, A.; Batchelder, J. C.; Bey, A.; Bingham, C. R.; Howard, Meredith E; Jones, K. L.; Manning, Brett M; Mueller, Paul Edward; Nesaraja, Caroline D; Pain, Steven D; Peters, William A; Ratkiewicz, Andrew J; Schmitt, Kyle; Shapira, Dan; Smith, Michael Scott; Stone, N. J.; Stracener, Daniel W; Yu, Chang-Hong

    2014-01-01

    Single-neutron states in 133Sn and 209Pb, which are analogous to single electrons outside of closed atomic shells in alkali metals, were populated by the (9Be,8Be) one-neutron transfer reaction in inverse kinematics using particle-gamma coincidence spectroscopy. In addition, the s1/2 single-neutron hole-state candidate in 131Sn was populated by (9Be,10Be). Doubly closed-shell 132Sn (radioactive) and 208Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, gamma-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared to shell-model expectations. The results include a new transition and precise level energy for the 3p1/2 candidate in 133Sn, new absolute cross sections for the 1h9/2 candidate in 133Sn and 3s1/2 candidate in 131Sn, and new lifetimes for excited states in 133Sn and 209Pb. This is the first report on excited-state lifetimes of 133Sn, which provide a unique signature of the single-neutron states and 132Sn double-shell closure.

  5. Structure of /sup 209/Bi deduced from the /sup 208/Pb(t,2n. gamma. ) reaction

    SciTech Connect

    Maier, K.H.; Nail, T.; Sheline, P.K.

    1983-04-01

    States in /sup 209/Bi were populated with the /sup 208/Pb(t,2n) reaction. Incident triton energies between 11 and 16 MeV were used. Gamma-ray excitation functions, angular distributions, and ..gamma..-..gamma..-time coincidence spectra were measured. Approximately 50 newly-observed ..gamma.. rays have been assigned to transitions in /sup 209/Bi. Previously-unresolved doublets at E/sub x/ = 2600, 3135, and 3154 keV have been identified. A new level at 3270 keV is reported, and the 3197-keV level is verified. /sup 209/Bi level energies are reported with an accuracy of 600 eV or less. A level scheme for E/sub x/<4.14 MeV is presented, including spin-parity assignments. A new M1 transition between the (5/2)/sup +/ and (3/2)/sup +/ members of the ..pi..h/sub 9/2/x3/sup -/ septuplet is reported. The 19 levels belonging to the ..nu..g/sub 9/2/p/sub 1/2/ /sup -1/, ..pi..h/sub 9/2/ are identified.

  6. Simultaneous analysis of the elastic scattering and breakup channel for the reaction 11Li+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Cubero, M.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Borge, M. J. G.; Buchmann, L.; Diget, C. A.; Falou, H. A.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gómez-Camacho, J.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Moro, A. M.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Sánchez-Benítez, A. M.; Shotter, A.; Tengblad, O.; Walden, P.

    2015-10-01

    We present a detailed analysis of the elastic scattering and breakup channel for the reaction of 11Li on 208Pb at incident laboratory energies of 24.3 and 29.8 MeV, measured at the radioactive ion beam facility of TRIUMF, in Vancouver, Canada. A large yield of 9Li fragments was detected by four charged particle telescopes in a wide angular range. The experimental angular and energy distributions of these 9Li fragments have been compared to coupled-reaction-channel and continuum-discretized coupled-channel calculations. The large production of 9Li fragments at small angles can be explained by considering a direct breakup mechanism, while at medium-large angles a competition between direct breakup and neutron transfer to the continuum of the 208Pb target was observed.

  7. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  8. In situ U-Pb rutile dating by LA-ICP-MS: 208Pb correction and prospects for geological applications

    NASA Astrophysics Data System (ADS)

    Zack, Thomas; Stockli, Daniel F.; Luvizotto, George L.; Barth, Matthias G.; Belousova, Elena; Wolfe, Melissa R.; Hinton, Richard W.

    2011-09-01

    Rutile is a common accessory mineral that occurs in a wide spectrum of metamorphic rocks, such as in blueschists, eclogites, and granulites and as one of the most stable detrital heavy minerals in sedimentary rocks. The advent of rutile trace element thermometry has generated increased interest in a better understanding of rutile formation. This study documents important analytical advances in in situ LA-ICP-MS U/Pb geochronology of rutile: (1) Matrix matching, necessary for robust in situ dating is fulfilled by calibrating and testing several rutile standards (R10, R19, WH-1), including the presentation of new TIMS ages for the rutile standard R19 (489.5 ± 0.9 Ma; errors always stated as 2 s). (2) Initial common lead correction is routinely applied via 208Pb, which is possible due to extremely low Th/U ratios (usually <0.003) in most rutiles. Employing a 213 nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb concordia ages for the two other rutile standards (493 ± 10 Ma for R19; 2640 ± 50 Ma for WH-1) and four rutile-bearing metamorphic rocks (181 ± 4 Ma for Ivrea metapelitic granulite; 339 ± 7 Ma for Saidenbach coesite eclogite; 386 ± 8 Ma for Fjortoft UHP metapelite; 606 ± 12 Ma for Andrelandia metepelitic granulite) always agree within 2% with the reported TIMS ages and other dating studies from the same localities. The power of in situ U/Pb rutile dating is illustrated by comparing ages of detrital rutile and zircon from a recent sediment from the Christie Domain of the Gawler Craton, Australia. While the U/Pb age spectrum from zircons show several pronounced peaks that are correlated with magmatic episodes, rutile U/Pb ages are marked by only one pronounced peak (at ca 1,675 Ma) interpreted to represent cooling ages of this part of the craton. Rutile thermometry of the same detrital grains indicates former granulite-facies conditions. The methods outlined in this paper should find wide application in studies

  9. Investigation of constraints on few-neutron forces in neutron matter by empirical information on the neutron skin of 48Ca and 208Pb

    NASA Astrophysics Data System (ADS)

    Sammarruca, Francesca

    2016-11-01

    The neutron matter equation of state is calculated from two-neutron forces up to fifth order of the chiral expansion, and the order-by-order convergence of the predictions is investigated. Based on these equations of state, the binding energies and the neutron and proton density distributions in 208Pb and 48Ca are derived, with particular attention paid to the neutron skins, the focal point of this paper. Anticipating future experiments which will provide reliable information on the weak charge density in nuclei, the theoretical uncertainties and the possibility of constraining the size of few-neutron forces in neutron matter are discussed.

  10. Nuclear potentials for sub-barrier fusion and cluster decay in {sup 14}C, {sup 18}O+{sup 208}Pb systems

    SciTech Connect

    Sagaidak, R. N.; Tretyakova, S. P.; Khlebnikov, S. V.; Ogloblin, A. A.; Rowley, N.; Trzaska, W. H.

    2007-09-15

    Near-barrier fusion excitation functions for the {sup 14}C and {sup 18}O+{sup 208}Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th (i.e., for the inverse decay process). The analysis supports the ''{alpha}-decay-like'' scenario for carbon and oxygen emission from these nuclei.

  11. Novel Manifestation of {alpha}-Clustering Structures: New '{alpha}+{sup 208}Pb' States in {sup 212}Po Revealed by Their Enhanced E1 Decays

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Petkov, P.; Delion, D. S.; Schuck, P.

    2010-01-29

    Excited states in {sup 212}Po were populated by {alpha} transfer using the {sup 208}Pb({sup 18}O,{sup 14}C) reaction, and their deexcitation {gamma} rays were studied with the Euroball array. Several levels were found to decay by a unique E1 transition (E{sub {gamma}}<1 MeV) populating the yrast state with the same spin value. Their lifetimes were measured by the Doppler-shift attenuation method. The values, found in the range 0.1-1.4 ps, lead to very enhanced transitions, B(E1)=2x10{sup -2}-1x10{sup -3} W.u. These results are discussed in terms of an {alpha}-cluster structure which gives rise to states with non-natural-parity values, provided that the composite system cannot rotate collectively, as expected in the '{alpha}+{sup 208}Pb' case. Such states due to the oscillatory motion of the {alpha}-core distance are observed for the first time.

  12. PriMux

    SciTech Connect

    2010-08-31

    PriMux is used to compute sets of compatible Polymerase Chain Reaction (PCR)signatures that can be used for detecting the presence of biological species in a small sample of material. Before use, the computed signatures must be empirically tested in a wet lab.

  13. Unusual potential behavior for the weakly bound nucleus 9Be in elastic scattering from 208Pb and 209Bi near the threshold

    NASA Astrophysics Data System (ADS)

    Yu, N.; Zhang, H. Q.; Jia, H. M.; Zhang, S. T.; Ruan, M.; Yang, F.; Wu, Z. D.; Xu, X. X.; Bai, C. L.

    2010-07-01

    The elastic scattering angular distributions of the weakly bound 9Be projectile from 208Pb and 209Bi have been measured for 14 beam energies near the threshold from 37 to 50 MeV. The parameters of the optical potential are extracted by means of phenomenological optical model analysis with PTOLEMY. Both of the systems show unusual potential behavior in the vicinity of the Coulomb barrier that the strength of the imaginary (absorptive) part of the potential is increasing (rather than decreasing) with decreasing energy, which is quite different from the results of some previous reports. This unusual threshold phenomenon indicates that the breakup channel is strongly coupled with the elastic channel and has obvious effects on the optical potential. The analyses also show that high precision elastic scattering angular distributions, especially those below the Coulomb barrier, are very important for extracting correct threshold behavior of the optical potential.

  14. Investigation of the structure of deep hole states in {sup 90}Zr and {sup 208}Pb by means of inelastic proton scattering at 1 GeV

    SciTech Connect

    Vorob`ev, A.A.; Dotsenko, Yu.V.; Lobodenko, A.A.

    1995-11-01

    A missing-mass correlation spectrometer with overall energy resolution FWHM = 3.5 MeV is used to study the reactions (p, 2p) and (p, np) on {sup 90}Zr and {sup 208}Pb nuclei at energy T{sub 0} = 1.0 GeV under experimental conditions permitting complete kinematic reconstruction. Proton- and neutron-separation-energy spectra are obtained in a wide binding-energy range. Empirical regularities observed in the evolution of the principal parameters of deep hole states of protons and neutrons in going from light to heavy nuclei are discussed. Experimental data are analyzed by the Hartree-Fock method with Skyrme forces, as well as with modified Moszkowski {delta} interaction. 26 refs., 7 figs., 8 tabs.

  15. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  16. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    NASA Astrophysics Data System (ADS)

    Quattrocchi, L.; Acosta, L.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Chbihi, A.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martel, I.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.; Vigilante, M.

    2016-05-01

    Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z˜3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  17. The study of neutron-rich nuclei production in the region of the closed shell N=126 in the multi-nucleon transfer reaction 136Xe+208Pb

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Harca, I. M.; Kozulin, E. M.; Dmitriev, S.; Itkis, J.; Knyazheva, G.; Loktev, T.; Corradi, L.; Valiente-Dobon, J.; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Vardaci, E.; Quero, D.; Montagnoli, G.; Scarlassara, F.; Strano, E.; Pollarolo, G.; Piot, J.; Mijatović, T.; Szilner, S.; Ackermann, D.; Chubarian, G.; Trzaska, W. H.

    2016-04-01

    The unexplored area of heavy neutron rich nuclei is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along the neutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis) the low-energy multi-nucleon transfer reaction 136Xe+208Pb at Elab=870MeV was explored. Due to the stabilizing effect of the closed neutron shells in both nuclei, N=82 and N=126, and the rather favorable proton transfer from lead to xenon, the light fragments formed in this process are well bound and the Q-value of the reaction is nearly zero. Measurements were performed with the PRISMA spectrometer in coincidence with an additional time-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy. The PRISMA spectrometer allows identification of the A, Z and velocity of the projectile-like fragments (PLF), while the second arm gives access to the target-like fragments (TLF). Details on the experimental setup and preliminary results are reported.

  18. Excitation function for the production of {sup 262}Bh (Z=107) in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n)

    SciTech Connect

    Folden, C.M. III; Nelson, S.L.; Duellmann, Ch.E.; Schwantes, J.M.; Zielinski, P.M.; Nitsche, H.; Hoffman, D.C.; Sudowe, R.; Gregorich, K.E.

    2006-01-15

    The excitation function for production of {sup 262}Bh in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from {sup 262}Bh and 2 decay chains originating from {sup 261}Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540{sub -150}{sup +180} pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of {sup 262}Bh in the analogous even-Z-projectile reaction {sup 209}Bi({sup 54}Cr, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by SwiaPtecki, Siwek-Wilczynska, and Wilczynski.

  19. Excitation function for the production of 262Bh (Z = 107) in theodd-Z projectile reaction 208Pb(55Mn, n)

    SciTech Connect

    Folden III, C.M.; Nelson, S.L.; Dullmann, Ch.E.; Schwantes, J.M.; Sudowe, R.; Zielinski, P.M.; Gregorich, K.E.; Nitsche, H.; Hoffman, D.C.

    2005-05-16

    The excitation function for production of 262Bh in the odd-Z-projectile reaction 208Pb(55Mn,n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from 262Bh and 2 decay chains originating from 261Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540 +180 - 150 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than fives times larger than that expected based on previously reported results for production of 262Bh in the analogous even-Z-projectile reaction 209Bi(54Cr,n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the ''Optimum Energy Rule'' proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski.

  20. In-situ U/Pb rutile dating by LA-ICP-MS: 208Pb correction and prospects for thermochronological applications

    NASA Astrophysics Data System (ADS)

    Zack, T.; Stockli, D. F.; Luvizotto, G. L.; Barth, M. G.; Wolfe, M. R.; Hinton, R. W.; Berndt-Gerdes, J.; Kooijman, E.

    2009-12-01

    The advent of rutile thermometry brought an increasing interest in understanding rutile formation and its temporal evolution. Here we report progress on several fronts of in situ U-Pb rutile geochronology: (1) Matrix matching, necessary for robust in situ dating is fullfilled by calibrating and testing rutile standards (R10 and R19), including the presentation of new TIMS ages for the rutile standard R19. (2) Common lead correction is routinely applied via 208Pb, which is possible due to extremely low Th/U ratios (usually <0.003) in most rutiles. Employing a 213 nm Nd:YAG laser coupled to a quadrupole ICP-MS and using R10 as a primary standard, rutile U/Pb ages for the other rutile standard and four rutile-bearing metamorphic rocks always agree better than 2% with the reported TIMS ages and other dating studies from the same localities. The methods outlined in this contribution should find wide application in thermochronological studies that require age information of single spots, e.g., single-crystal zoning and texturally-controlled dating. With this information we are able to address the effect of shielding of inclusion phases by robust host minerals.

  1. Mass, total kinetic energy, and neutron multiplicity correlations in the binary fragmentation of +208Pb 50Ti at 294 MeV bombarding energy

    NASA Astrophysics Data System (ADS)

    Appannababu, S.; Cinausero, M.; Marchi, T.; Gramegna, F.; Prete, G.; Bermudez, J.; Fabris, D.; Collazuol, G.; Saxena, A.; Nayak, B. K.; Kailas, S.; Bruno, M.; Morelli, L.; Gelli, N.; Piantelli, S.; Pasquali, G.; Barlini, S.; Valdré, S.; Vardaci, E.; Sajo-Bohus, L.; Degerlier, M.; Jhingan, A.; Behera, B. R.; Kravchuk, V. L.

    2016-10-01

    The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction +208Pb 50Ti at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf (Z =104 ) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of 4.5 ×10-20 s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of 258Rf. The extrapolated value of 4.7 ±1.4 is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with Z =116 and Z =124 .

  2. Comparison of reactions for the production of 258,257Db: 208Pb(51V,xn) and 209Bi(50Ti,xn)

    SciTech Connect

    Gates, Jacklyn M.; Nelson, Sarah L.; Gregorich, Kenneth E.; Dragojevic, Irena; Dullmann, Christoph E.; Ellison, Paul A.; Folden III, Charles M.; Garcia, Mitch A.; Stavsetra, Liv; Sudowe, Ralf; Hoffman, Darleane C.; Nitsche, Heino

    2008-09-29

    Excitation functions for the 1n and 2n exit channels of the 208Pb(51V,xn)259-xDb reaction were measured. A maximum cross section of the 1n exit channel of 2070+1100/-760 pb was measured at an excitation energy of 16.0 +- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660+450/-370 pb was measured at 22.0 +- 1.8 MeV excitation energy. The 1n excitation function for the 209Bi(50Ti,n)258Db reaction was remeasured, resulting in a cross section of 5480+1750/-1370 pb at an excitation energy of 16.0 +- 1.6 MeV, in agreement with previous values [F. P. Hebberger, et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  3. Allanite from the El Muerto Pegmatite, Oaxaca, Mexico: A Potential New Standard for 232Th-208Pb Dating by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Price, J.; Crowley, J. L.; Solari, L.; Prol-Ledesma, R.

    2012-12-01

    Allanite dating may be important to studies addressing tectonomagmatic evolution, provenance of monocyclic sediment, and mineral weathering. Obtaining accurate allanite ages by SIMS has been challenging and time-consuming due to the mineral's extreme chemical variability which often prevents finding adequately matrix-matched standards. Isotopic measurements by LA-ICP-MS minimize the need for standards of nearly identical composition to the unknown allanite being analyzed, and it is done relatively rapidly. Dating by LA-ICP-MS requires high quality standards for isotopic fractionation corrections. However, readily accessible and well characterized allanite standards are scarce. We investigated gemstone allanite from the El Muerto pegmatite, Oaxaca, Mexico, as a potential new geochronology standard for 232Th-208Pb allanite dating by LA-ICP-MS. Compositional homogeneity was thoroughly investigated by scanning and backscatter electron microscopy, cathodoluminescence, quantitative and qualitative energy dispersive x-ray spectroscopy, electron microprobe, and LA-ICP-MS. The possibility of metamictization was investigated by extensive X-ray diffraction analyses. The El Muerto allanite was U-Pb dated by ID-TIMS, with common Pb ratios determined from cogenetic K-feldspar by ID-TIMS and LA-MC-ICP-MS. Future work includes Th-Pb dating by ID-TIMS. The samples investigated are homogeneous with respect to major and trace elements. Major element compositional results are generally in agreement with published values, and no metamictization was identified despite the allanite being nearly 1 Ga. The only limitation of the El Muerto allanite is that it contains small, generally <100 μm, scarce inclusions of quartz, calciothorite, albite, calcite, and biotite. However, these grains are easily recognized and avoided during LA-ICP-MS analyses. Based on these results, the El Muerto allanite has the potential to serve as a standard for LA-ICP-MS dating.

  4. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  5. Doorway-state analysis of the fine structure in the giant quadrupole resonance in 208Pb observed in inelastic electron scattered

    NASA Astrophysics Data System (ADS)

    Winchenbach, J.; Pingel, K.; Holzwarth, G.; Kühner, G.; Richter, A.

    1983-11-01

    The fine structure observed in high resolution inelastic electron scattering data obtained at DALINAC for 208Pb in the excitation energy range of the giant quadrupole resonance (GQR) has been analysed under the assumption that the measured strongly fragmented E2 strength distribution is due to the coupling of one or two doorway states to a large number of more complicated states. The coupling matrix elements derived from the analysis allow the determination of the escape and spreading widths Γ ↑ and Γ ↓, the excitation energies Ed, the energy shifts ΔEd, and their energy dependence, for the underlying doorways.

  6. MISR Browse Images: Puerto Rico Dust Experiment (PRiDE)

    Atmospheric Science Data Center

    2013-04-02

    MISR Browse Images: Puerto Rico Dust Experiment (PRiDE) These MISR Browse images provide ... overview of the region observed during the Puerto Rico Dust Experiment (PRiDE) field campaign. PRiDE was a study of the radiative, ...

  7. Linking Knowledge and Action: PRI's Community Consultant.

    ERIC Educational Resources Information Center

    Spencer, Gregory P.

    Within the Partnership for Rural Improvement (PRI), community consultants operate within three complex sets of relationships: client groups, the organizational structure of PRI, and the local operational base. Community consultants are responsible for developing and facilitating rural development and for providing assistance in community and…

  8. Nuclear level densities in {sup 208}Bi and {sup 209}Po from the neutron spectra in the (p, n) reactions on {sup 208}Pb and {sup 209}Bi nuclei

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A. Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2010-07-15

    The spectra of neutrons from the (p, n) reactions on the {sup 208}Pb and {sup 209}Bi nuclei were measured in the proton-energy range 8-11 MeV. These measurements were performed by using a time-of-flight spectrometer of fast neutrons on the basis of the pulsed tandem accelerator EGP-15 of the Institute of Physics and Power Engineering (Obninsk, Russian Federation). A high resolution and stability of the time-of-flight spectrometermade it possible to identify reliably low-lying discrete levels alongwith the continuum section of the neutron spectra. The measured data were analyzed on the basis of the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations were performed by using the precise formalism of Hauser-Feshbach statistical theory together with the generalized model of a superfluid nucleus and the back-shifted Fermi gas model for the nuclear-level density. The nuclear-level densities in {sup 208}Bi and {sup 209}Po were determined along with their energy dependencies and model parameters. Our results are discussed together with available experimental data and recommendations of model systematics.

  9. Comparison of reactions for the production of {sup 258,257}Db: {sup 208}Pb({sup 51}V,xn) and {sup 209}Bi({sup 50}Ti,xn)

    SciTech Connect

    Gates, J. M.; Nelson, S. L.; Dragojevic, I.; Duellmann, Ch. E.; Ellison, P. A.; Folden III, C. M.; Garcia, M. A.; Hoffman, D. C.; Nitsche, H.; Gregorich, K. E.; Stavsetra, L.; Sudowe, R.

    2008-09-15

    Excitation functions for the 1n and 2n exit channels of the {sup 208}Pb({sup 51}V,xn){sup 259-x}Db reaction were measured. A maximum cross section of the 1n exit channel of 2070{sub -760}{sup +1100} pb was measured at an excitation energy of 16.0 {+-} 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660{sub -370}{sup +450} pb was measured at 22.0 {+-} 1.8 MeV excitation energy. The 1n excitation function for the {sup 209}Bi({sup 50}Ti,n){sup 258}Db reaction was remeasured, resulting in a cross section of 5480{sub -1370}{sup +1730} pb at an excitation energy of 16.0 {+-} 1.6 MeV, in agreement with previous values [F. P. Hessberger et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  10. Stable (206Pb, 207Pb, 208Pb) and radioactive (210Pb) lead isotopes in 1 year of growth of Sphagnum moss from four ombrotrophic bogs in southern Germany: Geochemical significance and environmental implications

    NASA Astrophysics Data System (ADS)

    Shotyk, William; Kempter, Heike; Krachler, Michael; Zaccone, Claudio

    2015-08-01

    The surfaces of Sphagnum carpets were marked with plastic mesh and 1 year later the production of plant matter was harvested in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Radioactive, 210Pb was determined in solid samples using ultralow background gamma spectrometry while total Pb concentrations and stable isotopes (206Pb, 207Pb, 208Pb) were determined in acid digests using ICP-SMS. Up to 12 samples (40 × 40 cm) were collected per site, and 6-10 sites investigated per bog. The greatest variations within a given sampling site were in the range 212-532 Bq kg-1 for 210Pb activity, whereas 206Pb/207Pb and 208Pb/206Pb varied less than 1%. The median values of all parameters for the sites (6-10 per bog) were not significantly different. The median activities of 210Pb (Bq kg-1) in the mosses collected from the bogs in NBF (HO = 372 ± 56, n = 55; WI = 342 ± 58, n = 93) were slightly less from those in OB (GS = 394 ± 50, n = 55; KL = 425 ± 58, n = 24). However, the mosses in the NBF bogs exhibited much greater productivity (187-202 g m-2 a-1) compared to those of OB (71-91 g m-2 a-1), and this has a profound impact on the accumulation rates of 210Pb (Bq m-2 a-1), with the bogs in the NBF yielding fluxes (HO = 73 ± 30; WI = 65 ± 20) which are twice those of OB (GS = 29 ± 11; KL = 40 ± 13). Using the air concentrations of 210Pb measured at Schauinsland (SIL) in the southern Black Forest and average annual precipitation, the atmospheric fluxes of 210Pb at SIL (340 Bq m-2 a-1) exceeds the corresponding values obtained from the mosses by a factor of five, providing the first quantitative estimate of the net retention efficiency of 210Pb by Sphagnum. When the 210Pb activities of all moss samples are combined (n = 227), a significant decrease with increasing plant production rate is observed; in contrast, total Pb concentrations show the opposite trend. The contrasting

  11. Characterization of the ground X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F

    SciTech Connect

    Mawhorter, Richard J.; Murphy, Benjamin S.; Baum, Alexander L.; Sears, Trevor J.; Yang, T.; Rupasinghe, P. M; McRaven, C. P.; Shafer-Ray, N. E.; Alphei, Lukas D.; Grabow, Jens-Uwe

    2011-08-15

    Pure rotational spectra of the ground electronic-vibrational X{sub 1} state of {sup 204}Pb{sup 19}F, {sup 206}Pb{sup 19}F, {sup 207}Pb{sup 19}F, and {sup 208}Pb{sup 19}F are measured with a resonator pulsed supersonic jet Fourier-transform microwave spectrometer. Also reported is a new measurement of the Stark effect on the optical spectra of A(leftarrow)X{sub 1} transitions. These spectra are combined with published high-resolution infrared spectra of X{sub 2}{r_reversible}X{sub 1} transitions in order to create a complete picture of the ground state of lead monofluoride. For the microwave data, molecules are prepared by laser ablation of lead target rods and stabilized in a supersonic jet of neon mixed with sulfur hexafluoride. For the optical Stark spectra, a continuous source of molecules is created in a nozzle heated to 1000 deg. C. The microwave spectra confirm, improve, and extend previously reported constants that describe the rotational, spin-orbit, and hyperfine interactions of the ground electronic state of the PbF molecule. A discrepancy concerning the sign of the hyperfine constant describing the {sup 207}Pb nucleus is discussed. Magnetic-field-dependent microwave spectra are used to characterize the Zeeman interaction in terms of two g factors of the body-fixed electronic wave function. The optical Stark spectra are used to characterize the electric dipole moment of the X{sub 1} and A states.

  12. Synthesis and Biological Activity of Diastereomeric and Geometric Analogs of Calcipotriol, PRI-2202 and PRI-2205, Against Human HL-60 Leukemia and MCF-7 Breast Cancer Cells

    PubMed Central

    Milczarek, Magdalena; Chodyński, Michał; Filip-Psurska, Beata; Martowicz, Agnieszka; Krupa, Małgorzata; Krajewski, Krzysztof; Kutner, Andrzej; Wietrzyk, Joanna

    2013-01-01

    Diastereomeric and geometric analogs of calcipotriol, PRI-2202 and PRI-2205, were synthesized as advanced intermediates from vitamin D C-22 benzothiazoyl sulfones and side-chain aldehydes using our convergent strategy. Calcitriol, calcipotriol (PRI-2201) and tacalcitol (PRI-2191) were used as the reference compounds. Among a series of tested analogs the diastereomeric analog PRI-2202 showed the strongest antiproliferative activity on the human breast cancer cell line MCF-7, whereas the geometric analog PRI-2205 was the weakest. Both analogs were less potent in antiproliferative activity against HL-60 cells compared to the reference compounds. The ability to potentiate antiproliferative effect of cisplatin or doxorubicin against HL-60 cells or that of tamoxifen against the MCF-7 cell line was observed at higher doses of PRI-2202 or PRI-2205 than those of the reference compounds. The proapoptotic activity of tamoxifen, expressed as the diminished mitochondrial membrane potential, as well as the increased phosphatidylserine expression, was partially attenuated by calcitriol, PRI-2191, PRI-2201 and PRI-2205. The treatment of the MCF-7 cells with tamoxifen alone resulted in an increase in VDR expression. Moreover, a further increase in VDR expression was observed when the analogs PRI-2201 or PRI-2205, but not PRI-2191, were used in combination with tamoxifen. This observation could partially explain the potentiation of the antiproliferative effect of tamoxifen by vitamin D analogs. PMID:24202449

  13. Structural mechanisms of PriA-mediated DNA replication restart.

    PubMed

    Bhattacharyya, Basudeb; George, Nicholas P; Thurmes, Tiffany M; Zhou, Ruobo; Jani, Niketa; Wessel, Sarah R; Sandler, Steven J; Ha, Taekjip; Keck, James L

    2014-01-28

    Collisions between cellular DNA replication machinery (replisomes) and damaged DNA or immovable protein complexes can dissociate replisomes before the completion of replication. This potentially lethal problem is resolved by cellular "replication restart" reactions that recognize the structures of prematurely abandoned replication forks and mediate replisomal reloading. In bacteria, this essential activity is orchestrated by the PriA DNA helicase, which identifies replication forks via structure-specific DNA binding and interactions with fork-associated ssDNA-binding proteins (SSBs). However, the mechanisms by which PriA binds replication fork DNA and coordinates subsequent replication restart reactions have remained unclear due to the dearth of high-resolution structural information available for the protein. Here, we describe the crystal structures of full-length PriA and PriA bound to SSB. The structures reveal a modular arrangement for PriA in which several DNA-binding domains surround its helicase core in a manner that appears to be poised for binding to branched replication fork DNA structures while simultaneously allowing complex formation with SSB. PriA interaction with SSB is shown to modulate SSB/DNA complexes in a manner that exposes a potential replication initiation site. From these observations, a model emerges to explain how PriA links recognition of diverse replication forks to replication restart.

  14. Finding the SurPriSe: A Case Study of a Faculty Learning Community

    ERIC Educational Resources Information Center

    Michel, Roberta M.

    2014-01-01

    This article details a faculty learning community (FLC) that started in 2009 on the campus of a Midwestern University and has evolved into an interdisciplinary research, teaching and social community of practice and learning called SurPriSe. SurPriSe is an acronym that reflects the interest area of the FLC; Sur for surveillance, Pri for privacy,…

  15. Canopy Level Chlorophyll Fluorescence and the PRI in a Cornfield

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Cheng, Yen-Ben; Corp, Lawrence A.; Campbell, Petya K. E.; Huemmrich, K. Fred; Zhang, Qingyuan; Kustas, William P.

    2012-01-01

    Two bio-indicators, the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (SIF), were derived from directional hyperspectral observations and studied in a cornfield on two contrasting days in the growing season. Both red and far-red SIF exhibited higher values on the day when the canopy in the early senescent stage, but only the far-red SIF showed sensitivity to viewing geometry. Consequently, the red/far-red SIF ratio varied greatly among azimuth positions while the largest values were obtained for the "hotspot" at both growth stages. This ratio was lower (approx.0.88 +/- 0.4) in early July than in August when the ratio approached equivalence (near approx.1). In concert, the PRI exhibited stronger responses to both zenith and azimuth angles and different values on the two growth stages. The potential of using these indices to monitor photosynthetic activities needs further investigation

  16. The Primitive Material Explorer (PriME) Mission

    NASA Astrophysics Data System (ADS)

    Cochran, Anita L.; Weaver, H. A.; Science, PriME; Engineering Teams

    2010-10-01

    The Primitive Material Explorer (PriME) Mission is a proposed Discovery mission that will rendezvous with comet 46P/Wirtanen in 2021 in order to 1) clarify the roles played by comets in the formation and evolution of the Solar System and the origin of life; 2) ascertain the bulk physical properties, the surface geology, and the sources of activity in a fresh comet nucleus; and 3) investigate the compositional diversity of primitive material in the Solar System. PriME teams an experienced group of comet scientists (led by PI Anita Cochran and by DPI Harold Weaver) with university and industrial partners. The PriME payload accomplishes the mission objectives with only three instruments. MASPEX (MAss Spectrometer for Planetary EXploration) has higher mass resolution and is more sensitive than any mass spectrometer ever flown. MASPEX will measure D/H in H2O, noble gases, isotopes of many species, and complex molecular compounds to test solar nebula models and the role comets played in delivering water and other biologically important materials throughout the Solar System. The VIS (Visible Imaging System), consisting of a Narrow Angle Camera (NAC) and Wide-Angle Camera (WAC), will constrain the conditions under which the building blocks of the outer Solar System were assembled by measuring key physical properties of the nucleus of 46P/Wirtanen. Using the radio antenna and close flybys of the nucleus, PriME will determine the mass of the nucleus to an accuracy of 1% and the bulk density and average porosity of the nucleus to better than 5%. All spacecraft subsystems have significant planetary flight heritage. The spacecraft is a high-heritage derivative of the Kepler and Deep Impact spacecrafts, compatible with the three launch vehicle families specified in the Discovery Announcement of Opportunity.

  17. The Importance of PRI Therapy for the Pastoral Counsellor

    PubMed Central

    2009-01-01

    It is not always easy for pastoral counsellors to help people change. Often people have become stuck in their ways. Recent developments in the field of brain research help explain why change is difficult. This article discusses Past Reality Integration Therapy (PRI), a psychotherapeutic method that integrates recent findings of brain research and offers an important addition to the work of (pastoral) counsellors and psychotherapists. The use of this approach with Dutch students in their pastoral training is presented. Furthermore the importance of this new method for counsellors themselves, their clients and their work is discussed and some overall conclusions about the method and its practical application are presented. PMID:20835380

  18. Diffuse sky radiation influences the relationship between canopy PRI and shadow fraction

    NASA Astrophysics Data System (ADS)

    Mõttus, Matti; Takala, Tuure L. H.; Stenberg, Pauline; Knyazikhin, Yuri; Yang, Bin; Nilson, Tiit

    2015-07-01

    The Photochemical Reflectance Index (PRI) of green leaves is an indicator of photosynthetic downregulation: when the photosynthetic apparatus is close to the saturation limit, PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves under different local irradiance conditions, it should be possible to determine the saturation level of the leaves and obtain information on the light use efficiency (LUE) of a vegetation canopy. The dependence of PRI on the ratio of sunlit to shaded foliage (quantified by the canopy shadow fraction) in the field of view of an instrument has been used to remotely measure canopy LUE on clear days. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature.

  19. Three causes of variation in the photochemical reflectance index (PRI) in evergreen conifers.

    PubMed

    Wong, Christopher Y S; Gamon, John A

    2015-04-01

    The photochemical reflectance index (PRI) reflects diurnal xanthophyll cycle activity and is also influenced by seasonally changing carotenoid : Chl pigment ratios. Both changing pigment pools and xanthophyll cycle activity contribute to photoprotection in evergreen conifers exposed to boreal winters, but they operate over different timescales, and their relative contribution to the PRI signal has often been unclear. To clarify these responses and their contribution to the PRI signal, leaf PRI, pigment composition, temperature and irradiance were monitored over 2 yr for two evergreen conifers (Pinus contorta and Pinus ponderosa) in a boreal climate. PRI was affected by three distinct processes operating over different timescales and exhibiting contrasting spectral responses. Over the 2 yr study period, the greatest change in PRI resulted from seasonally changing carotenoid : Chl pigment ratios, followed by a previously unreported shifting leaf albedo during periods of deep cold. Remarkably, the smallest change was attributable to the xanthophyll cycle. To properly distinguish these three effects, interpretation of PRI must consider temporal context, physiological responses to evolving environmental conditions, and spectral response. Consideration of the separate mechanisms affecting PRI over different timescales could greatly improve efforts to monitor changing photosynthetic activity using optical remote sensing.

  20. PriC-mediated DNA replication restart requires PriC complex formation with the single-stranded DNA-binding protein.

    PubMed

    Wessel, Sarah R; Marceau, Aimee H; Massoni, Shawn C; Zhou, Ruobo; Ha, Taekjip; Sandler, Steven J; Keck, James L

    2013-06-14

    Frequent collisions between cellular DNA replication complexes (replisomes) and obstacles such as damaged DNA or frozen protein complexes make DNA replication fork progression surprisingly sporadic. These collisions can lead to the ejection of replisomes prior to completion of replication, which, if left unrepaired, results in bacterial cell death. As such, bacteria have evolved DNA replication restart mechanisms that function to reload replisomes onto abandoned DNA replication forks. Here, we define a direct interaction between PriC, a key Escherichia coli DNA replication restart protein, and the single-stranded DNA-binding protein (SSB), a protein that is ubiquitously associated with DNA replication forks. PriC/SSB complex formation requires evolutionarily conserved residues from both proteins, including a pair of Arg residues from PriC and the C terminus of SSB. In vitro, disruption of the PriC/SSB interface by sequence changes in either protein blocks the first step of DNA replication restart, reloading of the replicative DnaB helicase onto an abandoned replication fork. Consistent with the critical role of PriC/SSB complex formation in DNA replication restart, PriC variants that cannot bind SSB are non-functional in vivo. Single-molecule experiments demonstrate that PriC binding to SSB alters SSB/DNA complexes, exposing single-stranded DNA and creating a platform for other proteins to bind. These data lead to a model in which PriC interaction with SSB remodels SSB/DNA structures at abandoned DNA replication forks to create a DNA structure that is competent for DnaB loading.

  1. New insights into pri-miRNA processing and accumulation in plants.

    PubMed

    Zhang, Shuxin; Liu, Yuhui; Yu, Bin

    2015-01-01

    MicroRNAs (miRNAs) regulate many biological processes such as development, metabolism, and others. They are processed from their primary transcripts called primary miRNA transcripts (pri-miRNAs) by the processor complex containing the RNAse III enzyme, DICER-LIKE1 (DCL1), in plants. Consequently, miRNA biogenesis is controlled through altering pri-miRNA accumulation and processing, which is crucial for plant development and adaptation to environmental changes. Plant pri-miRNAs are transcribed by DNA-dependent RNA polymerase II (Pol II) and their levels are determined through transcription and degradation, whereas pri-miRNA processing is affected by its structure, splicing, alternative splicing, loading to the processor and the processor activity, which involve in many accessory proteins. Here, we summarize recent progresses related to pri-miRNA transcription, stability, and processing in plants.

  2. Involvement of histidine in complex formation of PriB and single-stranded DNA.

    PubMed

    Fujiyama, Saki; Abe, Yoshito; Takenawa, Taichi; Aramaki, Takahiko; Shioi, Seijiro; Katayama, Tsutomu; Ueda, Tadashi

    2014-02-01

    PriB is a basic 10-kDa protein that acts as a facilitator in PriA-dependent replication restart in Escherichia coli. PriB has an OB-fold dimer structure and exhibits single-stranded DNA (ssDNA)-binding activities similar to single-stranded binding protein (SSB). In this study, we examined PriB's interaction with ssDNA (oligo-dT35, -dT15, and -dT7) using heteronuclear NMR analysis. Interestingly, (1)H or (15)N chemical shift changes of the PriB main-chain showed two distinct modes using oligo-dT35. The chemical shift perturbation sites in the primary mode were consistent with the main contact site in PriB-ssDNA, which was previously determined by crystal structure analysis. The results also suggested that approximately 8nt in ssDNA was the main contact site to PriB. In the secondary mode, residues in the α-helix region (His57-Ser65) and in β4-loop3-β5 were mainly perturbed. On the other hand, we examined the state of ssDNA by FRET using 5'-Cy3- and 3'-Cy5-modified oligo-dT35. As the PriB concentration increased, two-step saturation curves were observed in the FRET assay, suggesting a compact structure of ssDNA. Moreover, we confirmed two-step PriB binding to oligo-dT35 using EMSA. The pH dependence of FRET suggested contribution of the His residues. Therefore, we prepared His mutants of PriB and found that His64 in the α-helix region contributed to the second interaction between PriB and ssDNA using FRET and EMSA. Thus, from a structural standpoint, we suggested the role of His64 on the compactness of the PriB-ssDNA complex and on the positive cooperativity of PriB.

  3. Correcting the relationship between PRI and shadow fraction for the blue sky effect

    NASA Astrophysics Data System (ADS)

    Mõttus, Matti

    2016-04-01

    The Photochemical Reflectance Index (PRI) is defined as the normalized difference ratio of leaf reflectance at two specific wavelengths in the green spectral region. Its value depends on the status of leaf carotenoid content, and especially that of the xanthophyll cycle pigments. Due to the dependence on the xanthophyll cycle, when the photosynthetic apparatus of green leaves is close to the saturation limit, their PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves in the same canopy under different local irradiance conditions on a sunny day, it should be possible to determine the saturation level of the leaves. In turn, this gives information on the light use efficiency (LUE) of the vegetation canopy. The average light conditions of visible foliage elements are often quantified with the shadow fraction -- the fraction of visible foliage not lit by direct sunlight. The dependence of PRI on the shadow fraction has been used to remotely measure canopy LUE on clear days. Variations in shadow fraction have been achieved with multiangular measurement. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature. Next, we propose a new method to assess these PRI variations in structured vegetation. We investiagate this blue sky effect on the PRI -- shadow fraction relationship with high spatial (60 cm) and spectral (9.8 nm) resolution airborne imaging spectroscopy data from Hyytiälä, Finland. We evaluate the spectral irradiance in

  4. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuck, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-07-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use-efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "spectral reflectance sensors" (SRS sensors; recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration - one that considered sky conditions (cloud cover) at midday only, and another that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal timescale, PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different timescales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches for studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  5. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuk, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-02-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "SRS" sensors recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration, one that considered sky conditions (cloud cover) at midday only, and the other that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal time scale PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different time scales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well-suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches to studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  6. Microprocessor dynamics shows co- and post-transcriptional processing of pri-miRNAs.

    PubMed

    Louloupi, Annita; Ntini, Evgenia; Liz, Julia; Ørom, Ulf Andersson

    2017-03-01

    miRNAs are small regulatory RNAs involved in the regulation of translation of target transcripts. miRNA biogenesis is a multi-step process starting with the cleavage of the primary miRNA transcript in the nucleus by the Microprocessor complex. Endogenous processing of pri-miRNAs is challenging to study and the in vivo kinetics of this process is not known. Here, we present a method for determining the processing kinetics of pri-miRNAs within intact cells over time using a pulse-chase approach to label transcribed RNA during 15 minutes and follow the processing within a 1-hour window after labeling with bromouridine. We show, that pri-miRNAs exhibit different processing kinetics ranging from fast over intermediate to slow processing and provide evidence that pri-miRNA processing can occur both co-transcriptionally and post-transcriptionally.

  7. Structure and Function of the PriC DNA Replication Restart Protein.

    PubMed

    Wessel, Sarah R; Cornilescu, Claudia C; Cornilescu, Gabriel; Metz, Alice; Leroux, Maxime; Hu, Kaifeng; Sandler, Steven J; Markley, John L; Keck, James L

    2016-08-26

    Collisions between DNA replication complexes (replisomes) and barriers such as damaged DNA or tightly bound protein complexes can dissociate replisomes from chromosomes prematurely. Replisomes must be reloaded under these circumstances to avoid incomplete replication and cell death. Bacteria have evolved multiple pathways that initiate DNA replication restart by recognizing and remodeling abandoned replication forks and reloading the replicative helicase. In vitro, the simplest of these pathways is mediated by the single-domain PriC protein, which, along with the DnaC helicase loader, can load the DnaB replicative helicase onto DNA bound by the single-stranded DNA (ssDNA)-binding protein (SSB). Previous biochemical studies have identified PriC residues that mediate interactions with ssDNA and SSB. However, the mechanisms by which PriC drives DNA replication restart have remained poorly defined due to the limited structural information available for PriC. Here, we report the NMR structure of full-length PriC from Cronobacter sakazakii PriC forms a compact bundle of α-helices that brings together residues involved in ssDNA and SSB binding at adjacent sites on the protein surface. Disruption of these interaction sites and of other conserved residues leads to decreased DnaB helicase loading onto SSB-bound DNA. We also demonstrate that PriC can directly interact with DnaB and the DnaB·DnaC complex. These data lead to a model in which PriC acts as a scaffold for recruiting DnaB·DnaC to SSB/ssDNA sites present at stalled replication forks.

  8. Effect and evaluation of prying action for top- and seat-angle connections

    NASA Astrophysics Data System (ADS)

    Ahmed, Ali; Hasan, Rafiq

    2015-06-01

    Nonlinear finite element (FE) static analyses of top- and seat-angle connections were performed using ABAQUS standard to investigate the influence of connection parameters and its properties on prying action developed due to the interaction between column flange and top angle's vertical leg. Contact phenomenon between two interfaces with finite sliding and bolt pretension in the initial step of analysis was considered in the FE model. FE analysis results were compared with the experimental ones to examine the applicability of the FE model. Then, the location of plastic hinges in connection assemblages was investigated at the ultimate state of the connection and a parametric study was performed varying connection parameters, material properties of connection assemblages, and magnitude of bolt pretension to visualize their effects on prying force and on the position of prying force on top angle's vertical leg. Current study shows that plastic hinges not only develop at top angle's heel and bolt hole region but also in the bolt shank that differs from some assumptions of power model (Kishi and Chen 1990): (1) top angle thickness and gage distance from angle heel to bolt hole center line have an distinct effect on prying action; and (2) distributed prying force developed near the region of the top edge of tension angle's leg adjacent to column flange can contribute to the failure of the connection. Finally, a mathematical formulation to identify the location of prying force action point is proposed.

  9. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein

    PubMed Central

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M.; Schneiter, Roger; Asojo, Oluwatoyin A.

    2016-01-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg2+ coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg2+-dependent sterol binding by Pry1. PMID:27344972

  10. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein

    NASA Astrophysics Data System (ADS)

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M.; Schneiter, Roger; Asojo, Oluwatoyin A.

    2016-06-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg2+ coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg2+-dependent sterol binding by Pry1.

  11. Diurnal and Directional Responses of Chlorophyll Fluorescence and the PRI in a Cornfield

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth; Cheng, Y. B.; Corp, L.; Campbell, P.; Kustas, W.

    2010-01-01

    Determining the health and vigor of vegetation using high spectral resolution remote sensing is an important goal which has application to monitoring agriculture and ecosystem productivity and carbon exchange. Two spectral indices used to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.) are the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (Fs). Both the PRI and Fs capture the dynamics of photoprotection mechanisms within green foliage: the PRI is based on the association of the reflected radiation in the green spectrum with the xanthophyll cycle, whereas Fs measures the emitted radiation in the red and far-red spectrum. Fs was determined from retrievals in the atmospheric oxygen absorption features centered at 688 and 760 nm using a modified Fraunhofer Line Depth (FLD) method. We previously demonstrated diurnal and seasonal PRI differences for sunlit vs. shaded foliage in a conifer forest canopy, as expressed in the hotspot and darkspot of the Bidirectional Reflectance Function (BRF). In a USDA-ARS experimental field site located in Beltsville, MD, USA, measurements were acquired over a corn crop from a nadir view in 2008 with an ASD FieldSpec Pro (Analytical Spectral Devices, Inc., Boulder, CO, USA) to study the behavior of the PRI for sunlit and shaded foliage as captured in reflectance variations associated with the BRF, in a I m tall canopy in the vegetative growth stage. Those observations were compared to simulations obtained from two radiative transfer models. Measurements were then acquired to examine whether the PRI and Fs were influenced by view zenith and azimuth geometries at different times of day. Those measurements were made in 2010 with the Ocean Optics USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at several times during the day on

  12. Photochemical Reflectance Index (PRI) and remote sensing of plant CO2 uptake

    NASA Astrophysics Data System (ADS)

    Penuelas, J.; Garbulsky, M. F.; Filella, I.

    2011-12-01

    An accurate continuous quantification of the role of terrestrial ecosystems as carbon sinks everywhere constitutes a key issue in the face of ongoing environmental disturbance and climate change. The emerging consistency of the relationship between Photochemical Reflectance Index (PRI) and light use efficiency at the leaf, canopy and ecosystem scales offers promising prospects for continuous global monitoring of plant primary productivity from space. We will present and discuss this consistency. This reflectance index is based on the short term reversible xanthophyll pigment changes accompanying plant stress. It also behaves as an index of the chlorophyll:carotenoid ratios and therefore of the photosynthetic activities associated with their changes with leaf development, aging or stress at longer term. At the leaf and canopy levels, the PRI has been extensively found adequate to estimate LUE and thus photosynthetic performance, i.e. gross primary productivity, and its use has been extended increasingly in the last few years both in natural and semi-natural vegetation and in crops. The results of these studies confirm an exponential relationship between LUE and PRI over a wide range of species and conditions, hence suggesting that the overall photosynthetic system is often sufficiently regulated to maintain consistent relationships between the pigment, morphological and physiological changes linked to PRI and the changes in CO2 fixation. In a further step forward, with the availability of the MODIS sensor on TERRA and AQUA satellites, PRI is now increasingly used also at the ecosystem scale. The results of our study comparing PRI data from MODIS and CO2 exchange data from eddy covariance towers show that there may even be a common exponential relationship for all of forests. The emerging consistency of the relationship between PRI, LUE and ecosystem CO2 uptake increasingly found in these studies suggests a surprising degree of "functional convergence" of biochemical

  13. Gene structures and processing of Arabidopsis thaliana HYL1-dependent pri-miRNAs

    PubMed Central

    Szarzynska, Bogna; Sobkowiak, Lukasz; Pant, Bikram Datt; Balazadeh, Salma; Scheible, Wolf-Rüdiger; Mueller-Roeber, Bernd; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2009-01-01

    Arabidopsis thaliana HYL1 is a nuclear double-stranded RNA-binding protein involved in the maturation of pri-miRNAs. A quantitative real-time PCR platform for parallel quantification of 176 pri-miRNAs was used to reveal strong accumulation of 57 miRNA precursors in the hyl1 mutant that completely lacks HYL1 protein. This approach enabled us for the first time to pinpoint particular members of MIRNA family genes that require HYL1 activity for efficient maturation of their precursors. Moreover, the accumulation of miRNA precursors in the hyl1 mutant gave us the opportunity to carry out 3′ and 5′ RACE experiments which revealed that some of these precursors are of unexpected length. The alignment of HYL1-dependent miRNA precursors to A. thaliana genomic sequences indicated the presence of introns in 12 out of 20 genes studied. Some of the characterized intron-containing pri-miRNAs undergo alternative splicing such as exon skipping or usage of alternative 5′ splice sites suggesting that this process plays a role in the regulation of miRNA biogenesis. In the hyl1 mutant intron-containing pri-miRNAs accumulate alongside spliced pri-miRNAs suggesting the recruitment of HYL1 into the miRNA precursor maturation pathway before their splicing occurs. PMID:19304749

  14. Fluorescence, PRI and canopy temperature for water stress detection in cereal crops

    NASA Astrophysics Data System (ADS)

    Panigada, C.; Rossini, M.; Meroni, M.; Cilia, C.; Busetto, L.; Amaducci, S.; Boschetti, M.; Cogliati, S.; Picchi, V.; Pinto, F.; Marchesi, A.; Colombo, R.

    2014-08-01

    Narrow-band multispectral remote sensing techniques and thermal imagery were investigated for water stress detection in cereal crops. Visible and near infrared AISA Eagle (Specim, Finland) and thermal AHS-160 (Sensytech Inc., USA) imageries were acquired with an airborne survey on a farm-level experimental site where maize (Zea mays L.) and sorghum (Sorghum bicolor L.) were grown with three different irrigation treatments. Vegetation biophysical and eco-physiological measurements were collected concurrently with the airborne campaign. Leaf fluorescence yield (ΔF/Fm‧) resulted to be a good indirect measure of water stress. Therefore, ΔF/Fm‧ measurements were compared against remotely sensed indicators: (i) the Photochemical Reflectance Index (PRI), (ii) the sun-induced chlorophyll fluorescence at 760 nm (F760), retrieved by the Fraunhofer line depth method and (iii) the canopy temperature (TC) calculated decoupling soil and vegetation contributions. TC was related to ΔF/Fm‧ with the highest determination coefficient (R2 = 0.65), followed by PRI586 (reference band at 586 nm) (R2 = 0.51). The relationship with F760 was significant but weaker (R2 = 0.36). The coefficient of determination increased up to 0.54 when pigment concentration was considered by multiplying ΔF/Fm‧ and chlorophyll content, confirming the close relationship between passive fluorescence signal, pigment content and light photosystem efficiency. PRI586, F760 and TC maps were produced in maize and sorghum plots. The differences in the average values of PRI586, F760 and TC extracted from the plots with different water treatments showed that water treatments were well discriminated in maize plots by the three remotely sensed indicators. This was confirmed by the visual observation of the PRI586, F760 and TC maps, while in sorghum plots, F760 and TC appeared more sensitive to water stress compared to PRI586.

  15. Functional interactions between polypyrimidine tract binding protein and PRI peptide ligand containing proteins.

    PubMed

    Coelho, Miguel B; Ascher, David B; Gooding, Clare; Lang, Emma; Maude, Hannah; Turner, David; Llorian, Miriam; Pires, Douglas E V; Attig, Jan; Smith, Christopher W J

    2016-08-15

    Polypyrimidine tract binding protein (PTBP1) is a heterogeneous nuclear ribonucleoprotein (hnRNP) that plays roles in most stages of the life-cycle of pre-mRNA and mRNAs in the nucleus and cytoplasm. PTBP1 has four RNA binding domains of the RNA recognition motif (RRM) family, each of which can bind to pyrimidine motifs. In addition, RRM2 can interact via its dorsal surface with proteins containing short peptide ligands known as PTB RRM2 interacting (PRI) motifs, originally found in the protein Raver1. Here we review our recent progress in understanding the interactions of PTB with RNA and with various proteins containing PRI ligands.

  16. Prion-like Nanofibrils of Small Molecules (PriSM) Selectively Inhibit Cancer Cells by Impeding Cytoskeleton Dynamics*

    PubMed Central

    Kuang, Yi; Long, Marcus J. C.; Zhou, Jie; Shi, Junfeng; Gao, Yuan; Xu, Chen; Hedstrom, Lizbeth; Xu, Bing

    2014-01-01

    Emerging evidence reveals that prion-like structures play important roles to maintain the well-being of cells. Although self-assembly of small molecules also affords prion-like nanofibrils (PriSM), little is known about the functions and mechanisms of PriSM. Previous works demonstrated that PriSM formed by a dipeptide derivative selectively inhibiting the growth of glioblastoma cells over neuronal cells and effectively inhibiting xenograft tumor in animal models. Here we examine the protein targets, the internalization, and the cytotoxicity pathway of the PriSM. The results show that the PriSM selectively accumulate in cancer cells via macropinocytosis to impede the dynamics of cytoskeletal filaments via promiscuous interactions with cytoskeletal proteins, thus inducing apoptosis. Intriguingly, Tau proteins are able to alleviate the effect of the PriSM, thus protecting neuronal cells. This work illustrates PriSM as a new paradigm for developing polypharmacological agents that promiscuously interact with multiple proteins yet result in a primary phenotype, such as cancer inhibition PMID:25157102

  17. Association of a peptoid ligand with the apical loop of pri-miR-21 inhibits cleavage by Drosha

    PubMed Central

    Diaz, Jason P.; Chirayil, Rachel; Chirayil, Sara; Tom, Martin; Head, Katie J.; Luebke, Kevin J.

    2014-01-01

    We have found a small molecule that specifically inhibits cleavage of a precursor to the oncogenic miRNA, miR-21, by the microprocessor complex of Drosha and DGCR8. We identified novel ligands for the apical loop of this precursor from a screen of 14,024 N-substituted oligoglycines (peptoids) in a microarray format. Eight distinct compounds with specific affinity were obtained, three having affinities for the targeted loop in the low micromolar range and greater than 15-fold discrimination against a closely related hairpin. One of these compounds completely inhibits microprocessor cleavage of a miR-21 primary transcript at concentrations at which cleavage of another miRNA primary transcript, pri-miR-16, is little affected. The apical loop of pri-miR-21, placed in the context of pri-miR-16, is sufficient for inhibition of microprocessor cleavage by the peptoid. This compound also inhibits cleavage of pri-miR-21 containing the pri-miR-16 apical loop, suggesting an additional site of association within pri-miR-21. The reported peptoid is the first example of a small molecule that inhibits microprocessor cleavage by binding to the apical loop of a pri-miRNA. PMID:24497550

  18. Prion-like nanofibrils of small molecules (PriSM) selectively inhibit cancer cells by impeding cytoskeleton dynamics.

    PubMed

    Kuang, Yi; Long, Marcus J C; Zhou, Jie; Shi, Junfeng; Gao, Yuan; Xu, Chen; Hedstrom, Lizbeth; Xu, Bing

    2014-10-17

    Emerging evidence reveals that prion-like structures play important roles to maintain the well-being of cells. Although self-assembly of small molecules also affords prion-like nanofibrils (PriSM), little is known about the functions and mechanisms of PriSM. Previous works demonstrated that PriSM formed by a dipeptide derivative selectively inhibiting the growth of glioblastoma cells over neuronal cells and effectively inhibiting xenograft tumor in animal models. Here we examine the protein targets, the internalization, and the cytotoxicity pathway of the PriSM. The results show that the PriSM selectively accumulate in cancer cells via macropinocytosis to impede the dynamics of cytoskeletal filaments via promiscuous interactions with cytoskeletal proteins, thus inducing apoptosis. Intriguingly, Tau proteins are able to alleviate the effect of the PriSM, thus protecting neuronal cells. This work illustrates PriSM as a new paradigm for developing polypharmacological agents that promiscuously interact with multiple proteins yet result in a primary phenotype, such as cancer inhibition.

  19. Dimeric structure of the N-terminal domain of PriB protein from Thermoanaerobacter tengcongensis solved ab initio

    SciTech Connect

    Liebschner, Dorothee; Brzezinski, Krzysztof; Dauter, Miroslawa; Dauter, Zbigniew; Nowak, Marta; Kur, Józef; Olszewski, Marcin

    2012-12-01

    The N-terminal domain of the PriB protein from the thermophilic bacterium T. tengcongensis (TtePriB) was expressed and its crystal structure has been solved at the atomic resolution of 1.09 Å by direct methods. PriB is one of the components of the bacterial primosome, which catalyzes the reactivation of stalled replication forks at sites of DNA damage. The N-terminal domain of the PriB protein from the thermophilic bacterium Thermoanaerobacter tengcongensis (TtePriB) was expressed and its crystal structure was solved at the atomic resolution of 1.09 Å by direct methods. The protein chain, which encompasses the first 104 residues of the full 220-residue protein, adopts the characteristic oligonucleotide/oligosaccharide-binding (OB) structure consisting of a five-stranded β-barrel filled with hydrophobic residues and equipped with four loops extending from the barrel. In the crystal two protomers dimerize, forming a six-stranded antiparallel β-sheet. The structure of the N-terminal OB domain of T. tengcongensis shows significant differences compared with mesophile PriBs. While in all other known structures of PriB a dimer is formed by two identical OB domains in separate chains, TtePriB contains two consecutive OB domains in one chain. However, sequence comparison of both the N-terminal and the C-terminal domains of TtePriB suggests that they have analogous structures and that the natural protein possesses a structure similar to a dimer of two N-terminal domains.

  20. Remote detection of water stress conditions via a diurnal photochemical reflectance index (PRI) improves yield prediction in rainfed wheat

    NASA Astrophysics Data System (ADS)

    Magney, T. S.; Vierling, L. A.; Eitel, J.

    2014-12-01

    Employing remotely sensed techniques to quantify the existence and magnitude of midday photosynthetic downregulation using the photochemical reflectance index (PRI) may reveal new information about plant responses to abiotic stressors in space and time. However, the interpretation and application of the PRI can be confounded because of its sensitivity to several variables changing at the diurnal (e.g., irradiation, shadow fraction) and seasonal (e.g., leaf area, chlorophyll and carotene pigment concentrations, irradiation) time scales. We explored different techniques to correct the PRI for variations in canopy structure and relative chlorophyll content (ChlR) using highly temporally resolved (frequency = five minutes) in-situ radiometric measurements of PRI and the Normalized Difference Vegetation Index (NDVI) over eight soft white spring wheat (Triticum aestivum L.)field plots under varying nitrogen and soil water conditions over two seasons. Our results suggest that the influence of seasonal variation in canopy ChlR and LAI on the diurnally measured PRI (PRIdiurnal) can be minimized using simple correction techniques, therefore improving the strength of PRI as a tool to quantify abiotic stressors such as daily changes in soil volumetric water content (SVWC), and vapor pressure deficit (VPD). PRIdiurnal responded strongly to available nitrogen, and linearly tracked seasonal changes in SVWC, VPD, and stomatal conductance (gc). Utilizing the PRI as an indicator of stress, yield predictions significantly over greenness indices such as the NDVI. This study provides insight towards the future interpretation and scaling of PRI to quantify rapid changes in photosynthesis, and as an indicator of plant stress.

  1. Prion-like nanofibrils of small molecules (PriSM): A new frontier at the intersection of supramolecular chemistry and cell biology.

    PubMed

    Zhou, Jie; Du, Xuewen; Xu, Bing

    2015-01-01

    Formed by non-covalent interactions and not defined at genetic level, the assemblies of small molecules in biology are complicated and less explored. A common morphology of the supramolecular assemblies of small molecules is nanofibrils, which coincidentally resembles the nanofibrils formed by proteins such as prions. So these supramolecular assemblies are termed as prion-like nanofibrils of small molecules (PriSM). Emerging evidence from several unrelated fields over the past decade implies the significance of PriSM in biology and medicine. This perspective aims to highlight some recent advances of the research on PriSM. This paper starts with description of the intriguing similarities between PriSM and prions, discusses the paradoxical features of PriSM, introduces the methods for elucidating the biological functions of PriSM, illustrates several examples of beneficial aspects of PriSM, and finishes with the promises and current challenges in the research of PriSM. We anticipate that the research of PriSM will contribute to the fundamental understanding at the intersection of supramolecular chemistry and cell biology and ultimately lead to a new paradigm of molecular (or supramolecular) therapeutics for biomedicine.

  2. An aromatic-rich loop couples DNA binding and ATP hydrolysis in the PriA DNA helicase.

    PubMed

    Windgassen, Tricia A; Keck, James L

    2016-11-16

    Helicases couple ATP hydrolysis to nucleic acid binding and unwinding via molecular mechanisms that remain poorly defined for most enzyme subfamilies within the superfamily 2 (SF2) helicase group. A crystal structure of the PriA SF2 DNA helicase, which governs restart of prematurely terminated replication processes in bacteria, revealed the presence of an aromatic-rich loop (ARL) on the presumptive DNA-binding surface of the enzyme. The position and sequence of the ARL was similar to loops known to couple ATP hydrolysis with DNA binding in a subset of other SF2 enzymes, however, the roles of the ARL in PriA had not been investigated. Here, we show that changes within the ARL sequence uncouple PriA ATPase activity from DNA binding. In vitro protein-DNA crosslinking experiments define a residue- and nucleotide-specific interaction map for PriA, showing that the ARL binds replication fork junctions whereas other sites bind the leading or lagging strands. We propose that DNA binding to the ARL allosterically triggers ATP hydrolysis in PriA. Additional SF2 helicases with similarly positioned loops may also couple DNA binding to ATP hydrolysis using related mechanisms.

  3. The crystal structure of Neisseria gonorrhoeae PriB reveals mechanistic differences among bacterial DNA replication restart pathways

    SciTech Connect

    Dong, Jinlan; George, Nicholas P.; Duckett, Katrina L.; DeBeer, Madeleine A.P.; Lopper, Matthew E.

    2010-05-25

    Reactivation of repaired DNA replication forks is essential for complete duplication of bacterial genomes. However, not all bacteria encode homologs of the well-studied Escherichia coli DNA replication restart primosome proteins, suggesting that there might be distinct mechanistic differences among DNA replication restart pathways in diverse bacteria. Since reactivation of repaired DNA replication forks requires coordinated DNA and protein binding by DNA replication restart primosome proteins, we determined the crystal structure of Neisseria gonorrhoeae PriB at 2.7 {angstrom} resolution and investigated its ability to physically interact with DNA and PriA helicase. Comparison of the crystal structures of PriB from N. gonorrhoeae and E. coli reveals a well-conserved homodimeric structure consisting of two oligosaccharide/oligonucleotide-binding (OB) folds. In spite of their overall structural similarity, there is significant species variation in the type and distribution of surface amino acid residues. This correlates with striking differences in the affinity with which each PriB homolog binds single-stranded DNA and PriA helicase. These results provide evidence that mechanisms of DNA replication restart are not identical across diverse species and that these pathways have likely become specialized to meet the needs of individual organisms.

  4. An aromatic-rich loop couples DNA binding and ATP hydrolysis in the PriA DNA helicase

    PubMed Central

    Windgassen, Tricia A.; Keck, James L.

    2016-01-01

    Helicases couple ATP hydrolysis to nucleic acid binding and unwinding via molecular mechanisms that remain poorly defined for most enzyme subfamilies within the superfamily 2 (SF2) helicase group. A crystal structure of the PriA SF2 DNA helicase, which governs restart of prematurely terminated replication processes in bacteria, revealed the presence of an aromatic-rich loop (ARL) on the presumptive DNA-binding surface of the enzyme. The position and sequence of the ARL was similar to loops known to couple ATP hydrolysis with DNA binding in a subset of other SF2 enzymes, however, the roles of the ARL in PriA had not been investigated. Here, we show that changes within the ARL sequence uncouple PriA ATPase activity from DNA binding. In vitro protein-DNA crosslinking experiments define a residue- and nucleotide-specific interaction map for PriA, showing that the ARL binds replication fork junctions whereas other sites bind the leading or lagging strands. We propose that DNA binding to the ARL allosterically triggers ATP hydrolysis in PriA. Additional SF2 helicases with similarly positioned loops may also couple DNA binding to ATP hydrolysis using related mechanisms. PMID:27484483

  5. Explaining the variability of Photochemical Reflectance Index (PRI): deconvolution of variability related to Light Use Efficiency and Canopy attributes.

    NASA Astrophysics Data System (ADS)

    Merlier, Elodie; Hmimina, Gabriel; Dufrêne, Eric; Soudani, Kamel

    2014-05-01

    The Photochemical Reflectance Index (PRI) was designed as a proxy of the state of xanthophyll cycle which is used as a response of plants to excess of light (Gamon et al., 1990; 1992). Strong relationships between PRI and LUE were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). However, its use at canopy scale was shown to be significantly hampered by effects of confounding factors such as the PRI sensitivity to leaf pigment content (Gamon et al. 2001; Nakaji et al. 2006) and to canopy structure (Hilker et al. 2008). Several approaches aimed at correcting such effects and recent works focused on the deconvolution of LUE related and LUE unrelated PRI variability (Rahimzadeh-Bajgiran et al. 2012).In this study, the PRI variability at canopy scale is investigated over two years on three species (Fagus sylvatica, Quercus robur and Pinus sylvestris) growing under two water regimes. At daily scale, PRI variability is mainly explained by radiation conditions. As already reported at leaf scale in Hmimina et al. (2014), analysis of PRI responses to incoming photosynthetically active radiation over seasonal scale allowed to separate two sources of variability : a constitutive variability mainly related to canopy structure and leaf chlorophyll content and a facultative variability mainly related to LUE and soil moisture content. These results highlight the composite nature of PRI signal measured at canopy scale and the importance of disentangling its sources of variability in order to accurately assess ecosystem light use efficiency. Gamon JA, Field CB, Bilger W, Björkman O, Fredeen AL, Peñuelas J. 1990. Remote sensing of the xanthophyll cycle and chlorophyll fluorescence in sunflower leaves and canopies. Oecologia 85, 1-7. Gamon JA, Field CB, Fredeen A AL, Thayer S. 2001. Assessing photosynthetic downregulation in sunflower stands with an optically-based model. Photosynthesis Research 67, 113-125. Gamon JA, Peñuelas J, Field CB

  6. Explaining the variability of the photochemical reflectance index (PRI) at the canopy-scale: Disentangling the effects of phenological and physiological changes.

    PubMed

    Merlier, Elodie; Hmimina, Gabriel; Dufrêne, Eric; Soudani, Kamel

    2015-10-01

    Assessing photosynthesis rates at the ecosystem scale and over large regions is important for tracking the global carbon cycle and remote sensing has provided new and useful approaches for performing this assessment. The photochemical reflectance index (PRI) is a good estimator of short-term light-use efficiency (LUE) at the leaf scale; however, confounding factors appear at larger temporal and spatial scales. In this study, canopy-scale PRI variability was investigated for three species (Fagus sylvatica L., Quercus robur L. and Pinus sylvestris L.) growing under contrasting soil moisture conditions. Throughout the growing season, no significant differences in chlorophyll content and in violaxanthin, antheraxanthin and zeaxanthin were found between species or treatments. The daily PRI vs PAR (photosynthetically active radiation) relationships were determined using continuous measurements obtained at high frequency throughout the entire growing season, from early spring budburst to later autumn senescence, and were used to deconvolute the physiological PRI variability related to LUE variations due to phenological variability and related to temporal changes in the biochemical and structural canopy attributes. The PRI vs PAR relationship is used to show that the canopy-scale PRI measured at low radiation depends on the chlorophyll content of the canopy. The range of PRI variations at an intra-daily scale and the dynamics of the xanthophyll pool do not vary between days, which suggests that the PRI responds to a xanthophyll ratio. The PAR values at PRI saturation are mainly related to the canopy chlorophyll content during budburst and senescence and to the soil moisture content when the chlorophyll content is no longer a limiting factor. This parameter is significantly lower in the oak species that experience less stress from variations in soil moisture and is species dependant. These results provide new insights regarding the analysis and the meaning of PRI

  7. Remote sensing of plant emissions of volatile isoprenoids with PRI. Prospects for upscaling (Invited)

    NASA Astrophysics Data System (ADS)

    Penuelas, J.

    2013-12-01

    Josep Peñuelas*1,2, Giovanni Marino1,2,3,4, Joan LLusia1,2, Catherine Morfopoulos1,2,5, Gerard Farre-Armengol1,2, Shawn Kefauver, Alex Guenther6 , Francesca Rapparini7 , Roger Seco1,2,6, Marc Estiarte1,2, Mónica Mejia-Chang1,2, Romà Ogaya1,2, Jordi Sardans1,2 , Andrew Turnipseed6, Peter Harley6, Osvaldo Facini7, Rita Baraldi7, Jim Greenberg6 , Iolanda Filella1,2 1 CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallés 08193, Catalonia, Spain 2 CREAF, Cerdanyola del Vallés 08193, Catalonia, Spain 3 Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche (IS), Italy 4 Institute for Plant Protection, National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy 5 Division of Ecology and Evolution, Imperial College, Silwood Park, Ascot, SL5 7PY, UK 6 Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, USA 7 Biometeorology Institute, IBIMET-CNR, Via P. Gobetti 101, Bologna, Italy Abstract Terrestrial plants re-emit around 1-2% of the carbon they fix as isoprene and monoterpenes. These emissions play major roles in the ecological relationships among living organisms and in atmospheric chemistry and climate, and yet their actual quantification at the ecosystem level in different regions is far from being resolved. Phenomenological models are used to estimate the emission rates, but the limited understanding of the function and regulation of these emissions leads to large uncertainties in such estimations. Many measurements have been made at the foliar but few at the ecosystem level, and those that do exist are limited in space and time. We here provide evidence that a simple remote sensing index, the photochemical reflectance index (PRI), which is indicative of light use efficiency (LUE), is a good indirect estimator of foliar isoprenoid emissions and therefore can be used to sense them remotely. These results open

  8. The N-terminal domain of DnaT, a primosomal DNA replication protein, is crucial for PriB binding and self-trimerization.

    PubMed

    Huang, Yen-Hua; Huang, Cheng-Yang

    2013-12-13

    DnaT and PriB are replication restart primosomal proteins required for re-initiating chromosomal DNA replication in bacteria. Although the interaction of DnaT with PriB has been proposed, which region of DnaT is involved in PriB binding and self-trimerization remains unknown. In this study, we identified the N-terminal domain in DnaT (aa 1-83) that is important in PriB binding and self-trimerization but not in single-stranded DNA (ssDNA) binding. DnaT and the deletion mutant DnaT42-179 protein can bind to PriB according to native polyacrylamide gel electrophoresis, Western blot analysis, and pull-down assay, whereas DnaT84-179 cannot bind to PriB. In contrast to DnaT, DnaT26-179, and DnaT42-179 proteins, which form distinct complexes with ssDNA of different lengths, DnaT84-179 forms only a single complex with ssDNA. Analysis of DnaT84-179 protein by gel filtration chromatography showed a stable monomer in solution rather than a trimer, such as DnaT, DnaT26-179, and DnaT42-179 proteins. These results constitute a pioneering study of the domain definition of DnaT. Further research can directly focus on determining how DnaT binds to the PriA-PriB-DNA tricomplex in replication restart by the hand-off mechanism.

  9. Pri-miR-17-92a transcript folds into a tertiary structure and autoregulates its processing

    PubMed Central

    Chakraborty, Saikat; Mehtab, Shabana; Patwardhan, Anand; Krishnan, Yamuna

    2012-01-01

    MicroRNAs control gene expression either by RNA transcript degradation or translational repression. Expressions of miRNAs are highly regulated in tissues, disruption of which leads to disease. How this regulation is achieved and maintained is still largely unknown. MiRNAs that reside on clustered or polycistronic transcripts represent a more complex case where individual miRNAs from a cluster are processed with different efficiencies despite being cotranscribed. To shed light on the regulatory mechanisms that might be operating in these cases, we considered the long polycistronic primary miRNA transcript pri-miR-17-92a that contains six miRNAs with diverse functions. The six miRNA domains on this cluster are differentially processed to produce varying amounts of resultant mature miRNAs in different tissues. How this is achieved is not known. We show, using various biochemical and biophysical methods coupled with mutational studies, that pri-miR-17-92a adopts a specific three-dimensional architecture that poses a kinetic barrier to its own processing. This tertiary structure could create suboptimal protein recognition sites on the pri-miRNA cluster due to higher-order structure formation. PMID:22450760

  10. mirEX: a platform for comparative exploration of plant pri-miRNA expression data.

    PubMed

    Bielewicz, Dawid; Dolata, Jakub; Zielezinski, Andrzej; Alaba, Sylwia; Szarzynska, Bogna; Szczesniak, Michal W; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia; Karlowski, Wojciech M

    2012-01-01

    mirEX is a comprehensive platform for comparative analysis of primary microRNA expression data. RT-qPCR-based gene expression profiles are stored in a universal and expandable database scheme and wrapped by an intuitive user-friendly interface. A new way of accessing gene expression data in mirEX includes a simple mouse operated querying system and dynamic graphs for data mining analyses. In contrast to other publicly available databases, the mirEX interface allows a simultaneous comparison of expression levels between various microRNA genes in diverse organs and developmental stages. Currently, mirEX integrates information about the expression profile of 190 Arabidopsis thaliana pri-miRNAs in seven different developmental stages: seeds, seedlings and various organs of mature plants. Additionally, by providing RNA structural models, publicly available deep sequencing results, experimental procedure details and careful selection of auxiliary data in the form of web links, mirEX can function as a one-stop solution for Arabidopsis microRNA information. A web-based mirEX interface can be accessed at http://bioinfo.amu.edu.pl/mirex.

  11. Linking chlorophyll fluorescence, hyperspectral reflectance and plant physiological responses to detect stress using the photochemical reflectance index (PRI) (Invited)

    NASA Astrophysics Data System (ADS)

    Naumann, J. C.; Young, D.; Anderson, J.

    2009-12-01

    The concept of using vegetation as sentinels to indicate natural or anthropogenic stress is not new and could potentially provide an ideal mechanism for large-scale detection. Advances in fluorescence spectroscopy and reflectance-derived fluorescence have made possible earlier detection of stress in plants, especially before changes in chlorophyll content are visible. Our studies have been used to fuse leaf fluorescence and reflectance characteristics to remotely sense and rapidly detect vegetation stress and terrain characteristics. Laboratory studies have indicated that light-adapted fluorescence (ΔF/F‧m) measurements have been successful in all experiments at detecting stress from flooding, salinity, drought, herbicide and TNT contamination prior to visible signs of damage. ΔF/F‧m was related to plant physiological status in natural stress conditions, as seen in the relationships with stomatal conductance and photosynthesis The photochemical reflectance index (PRI) and other reflectance ratios were effective at tracking changes in ΔF/F‧m at the leaf and canopy-level scales. At the landscape-level, chlorophyll fluorescence and airborne reflectance imagery were used to evaluate spatial variations in stress in the dominant shrub on a barrier island, Myrica cerifera, during a severe drought and compared to an extremely wet year. Measurements of relative water content and the water band index (WBI970) indicated that water stress did not vary across the island. In contrast, there were significant differences in tissue chlorides across sites. Using PRI we were able to detect salinity stress across the landscape. PRI did not differ between wet and dry years. There was a positive relationship between PRI and ΔF/F‧m for M. cerifera (r2 = 0.79). The normalized difference vegetation index (NDVI), the chlorophyll index (CI) and WBI970 were higher during the wet summer but varied little across the island. PRI was not significantly related to NDVI, suggesting that

  12. Prediction of moment-rotation characteristic of top- and seat-angle bolted connection incorporating prying action

    NASA Astrophysics Data System (ADS)

    Ahmed, Ali

    2017-03-01

    Finite element (FE) analyses were performed to explore the prying influence on moment-rotation behaviour and to locate yielding zones of top- and seat-angle connections in author's past research studies. The results of those FE analyses with experimental failure strategies of the connections were used to develop failure mechanisms of top- and seat-angle connections in the present study. Then a formulation was developed based on three simple failure mechanisms considering bending and shear deformations, effects of prying action on the top angle and stiffness of the tension bolts to estimate rationally the ultimate moment M u of the connection, which is a vital parameter of the proposed four-parameter power model. Applicability of the proposed formulation is assessed by comparing moment-rotation ( M- θ r ) curves and ultimate moment capacities with those measured by experiments and estimated by FE analyses and three-parameter power model. This study shows that proposed formulation and Kishi-Chen's method both achieved close approximation driving M- θ r curves of all given connections except a few cases of Kishi-Chen model, and M u estimated by the proposed formulation is more rational than that predicted by Kishi-Chen's method.

  13. Prediction of moment-rotation characteristic of top- and seat-angle bolted connection incorporating prying action

    NASA Astrophysics Data System (ADS)

    Ahmed, Ali

    2017-02-01

    Finite element (FE) analyses were performed to explore the prying influence on moment-rotation behaviour and to locate yielding zones of top- and seat-angle connections in author's past research studies. The results of those FE analyses with experimental failure strategies of the connections were used to develop failure mechanisms of top- and seat-angle connections in the present study. Then a formulation was developed based on three simple failure mechanisms considering bending and shear deformations, effects of prying action on the top angle and stiffness of the tension bolts to estimate rationally the ultimate moment M u of the connection, which is a vital parameter of the proposed four-parameter power model. Applicability of the proposed formulation is assessed by comparing moment-rotation (M-θ r ) curves and ultimate moment capacities with those measured by experiments and estimated by FE analyses and three-parameter power model. This study shows that proposed formulation and Kishi-Chen's method both achieved close approximation driving M-θ r curves of all given connections except a few cases of Kishi-Chen model, and M u estimated by the proposed formulation is more rational than that predicted by Kishi-Chen's method.

  14. Functional study of one nucleotide mutation in pri-miR-125a coding region which related to recurrent pregnancy loss.

    PubMed

    Hu, Yi; Huo, Zheng-Hao; Liu, Chun-Mei; Liu, Shi-Guo; Zhang, Ning; Yin, Kun-Lun; Qi, Lu; Ma, Xu; Xia, Hong-Fei

    2014-01-01

    MicroRNAs (miRNAs) are short non-coding RNAs which modulate gene expression by binding to complementary segments present in the 3'UTR of the mRNAs of protein coding genes. MiRNAs play very important roles in maintaining normal human body physiology conditions, meanwhile, abnormal miRNA expressions have been found related to many human diseases spanning from psychiatric disorders to malignant cancers. Recently, emerging reports have indicated that disturbed miRNAs expression contributed to the pathogenesis of recurrent pregnancy loss (RPL). In this study, we identified a new mutation site (+29A>G, position relative to pre-miR-125a) by scanning pri-miR-125a coding region in 389 Chinese Han RPL patients. This site was co-existed with two polymorphisms (rs12976445 and rs41275794) in patients heterogeneously and changed the predicted secondary structures of pri-miR-125a. Subsequent in vitro analysis indicated that the A>G mutation reduced mature miR-125a expression, and further led to less efficient inhibition of verified target genes. Functional analysis showed that mutant pri-mir-125a can enhance endometrial stromal cells (ESCs) invasive capacity and increase the sensitivity of ESCs cells to mifepristone. Moreover, we further analyzed the possible molecular mechanism by RIP-chip assay and found that mutant pri-mir-125a disturbed the expression of miR-125a targetome, the functions of which includes embryonic development, cell proliferation, migration and invasion. These data suggest that A>G mutation in pri-miR-125a coding region contributes to the genetic predisposition to RPL by disordering the production of miR-125a, which consequently meddled in gene regulatory network between mir-125a and mRNA.

  15. Dynamic studies of {sup 11}Li and its core {sup 9}Li on {sup 208}Pb near the Coulomb barrier

    SciTech Connect

    Cubero, M.; Borge, M. J. G.; Alcorta, M.; Madurga, M.; Tengblad, O.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alvarez, M. A. G.; Gomez-Camacho, J.; Diget, C.; Galaviz, D.; Fernandez-Garcia, J. P.; Lay, J. A.; Moro, A. M.; Mukha, I.; Shotter, A.; Walden, P.

    2010-04-26

    We measured the scattering of the halo nucleus {sup 11}Li and its core {sup 9}Li on the lead target at TRIUMF at energies below and around to the Coulomb barrier. We report here on our preliminary analysis of the inclusive breakup reaction.

  16. Nuclear structure ''southeast'' of {sup 208}Pb: Isomeric states in {sup 208}Hg and {sup 209}Tl

    SciTech Connect

    Al-Dahan, N.; Podolyak, Zs.; Regan, P. H.; Alkhomashi, N.; Deo, A. Y.; Farrelly, G.; Steer, S. J.; Cullen, I. J.; Gelletly, W.; Swan, T.; Thomas, J. S.; Walker, P. M.; Gorska, M.; Grawe, H.; Gerl, J.; Pietri, S. B.; Wollersheim, H. J.; Boutachkov, P.; Domingo-Pardo, C.; Farinon, F.

    2009-12-15

    The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV {sup 238}U beam. Metastable states in the N=128 isotones {sup 208}Hg and {sup 209}Tl have been identified. Delayed {gamma}-ray transitions are interpreted as arising from the decay of I{sup {pi}}=(8{sup +}) and (17/2{sup +}) isomers, respectively. The data allow for the so far most comprehensive verification of the shell-model approach in the region determined by magic numbers Z<82 and N>126.

  17. pri-miR-34b/c rs4938723 polymorphism is associated with hepatocellular carcinoma risk: a case-control study in a Chinese population

    PubMed Central

    Liu, Chun-Jia; Ma, Xue-Wei; Zhang, Xue-Jun; Shen, Shi-Qiang

    2017-01-01

    Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. miR-34 induces changes of its downstream genes, and plays a key role in altering the apoptotic cycle and pathways of downstream cells, and finally influences the development of cancer. We assessed the relationship of the pri-miR-34b/c rs4938723 polymorphism with hepatocellular carcinoma risk in a Chinese population. During the period of January 2014 and December 2015, a total of 164 HCC patients and 305 healthy controls were recruited from the Inner Mongolia People’s Hospital. Genotyping of the pri-miR-34b/c rs4938723 was determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Using χ2 test, we observed that HCC patients were likely to have a habit of alcohol consumption (χ2 = 10.24, P = 0.001) and infect with HBV or HCV (χ2 = 128.17, P < 0.001). In co-dominant model, the CC genotype of pri-miR-34b/c rs4938723 had a significant higher risk of HCC as compared with the TT genotype, and the corresponding adjusted OR (95% CI) was 4.14 (1.91-9.75). In dominant model, we observed that the TC+CC genotype were associated with an increased risk of HCC in comparison to the TT genotype (OR = 1.67, 95% CI = 1.17-2.55). In recessive model, the CC genotype was correlated with an elevated risk of HCC when compared with the TT+TC genotype (OR = 3.46, 95% CI = 1.62-8.54). The pri-miR-34b/c rs4938723 polymorphism was associated with a higher risk of HCC in the Chinese population examined. Further large-scale and multi-center studies are required to confirm these results. PMID:28337312

  18. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring.

    PubMed

    Fréchette, Emmanuelle; Wong, Christopher Y S; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-12-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI-LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures.

  19. Application of carbon nanosorbent for PRiME pass-through cleanup of 10 selected local anesthetic drugs in human plasma samples.

    PubMed

    Ma, Jian-Bo; Zhao, Li-Ming; Rui, Qiu-Hong; Liao, Yu-Feng; Chen, Yan-Min; Xu, Jin; Zhu, Yan; Zhao, Yong-Gang

    2017-04-01

    A novel PRiME (process, robustness, improvements, matrix effects, ease of use) pass-through cleanup procedure has been developed to improve the existing commercially available designs. Carbon nanosorbents, i.e., magnetic modified carboxyl-graphene (Mag-CG) and magnetic modified carboxyl-carbon nanotubes (Mag-CCNTs), have been synthesised and evaluated in PRiME pass-through cleanup procedure for human plasma prior to analysis of 10 selected local anesthetic drugs by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). The matrix effect, an interesting phenomenon of ion suppression for local anesthetic drugs containing ester group and ion enhancement for other drugs containing acylamino group, has been minimized using carbon nanosorbents PRiME pass-through cleanup procedure. Under the optimal conditions, the obtained results show higher cleanup efficiency of the carbon nanosorbents with recoveries between 70.2% and 126%. Furthermore, the carbon nanosorbents are also evaluated for reuse up to 80-100 times. The limits of quantification (LOQs) for local anesthetic drugs are in the range of 0.024-0.15 μg/L. Validation results on linearity, specificity, accuracy, and precision, as well as the application to the analysis of lidocaine in five patients recruited from the lung cancer demonstrate the applicability to clinical studies.

  20. Transverse resistance in Y1-yPryBa2Cu3O7-δ at large praseodymium concentrations

    NASA Astrophysics Data System (ADS)

    Vovk, Ruslan V.; Khadzhai, Georgij Ya.; Dobrovolskiy, Oleksandr V.

    2014-10-01

    The effect of praseodymium doping on the transverse electrical resistance of Y1-yPryBa2Cu3O7-δ single crystals is investigated by electrical resistance measurements. The resistance curves can be fitted well to an expression accounting for the thermo-activated variable-range hopping charge transfer in conjunction with the fluctuation conductivity in the 3D Aslamazov-Larkin model. Our analysis of the Pr concentration dependence of the fitting parameters shows that in the concentration range 0.34

  1. Magnetic and electric behavior of praseodymium substituted CuPryFe2-yO4 ferrites

    NASA Astrophysics Data System (ADS)

    Farid, Muhammad Tahir; Ahmad, Ishtiaq; Kanwal, Muddassara; Murtaza, Ghulam; Ali, Irshad; Ashiq, Muhammad Naeem; Khan, Sajjad Ahmad

    2017-01-01

    Spinel ferrites with chemical formula CuPryFe2-yO4(y=0.0,0.02,0.04,0.06,0.08,0.10) were synthesized using sol-gel technique. The sintered powder characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and vibrating sample magnetometer (VSM). X-ray Diffraction analysis showed that the samples with concentration (y=0.0-0.06) have single spinel phase and the samples with concentration at y=0.08-0.10 have secondary phase (ortho ferrite phase) along spinel phase. The Lattice constant a increased with the substitution of Praseodymium (Pr) ions. The crystallite size calculated from Scherre's formula is found in the range of 53-37 nm. It is observed that DC resistivity and activation energy enhances with the substitution of Pr. The dc resistivity decreased with the increase in temperature. The conduction below Curie temperature (Tc) is due to hopping of electrons and holes, whereas, above Curie temperature it is due to polaron hopping. The decrease in Tc with increasing Pr constant may be due to the fact that Pr-Fe interactions on the B sites are weaker than Fe-Fe interaction. The saturation magnetization (Ms) and remanence (Mr) decreased where as coercivity (Hc) has been increased with the increase of Pr content. The measured parameters suggest that these materials are potential candidates for high frequency applications.

  2. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring

    PubMed Central

    Fréchette, Emmanuelle; Wong, Christopher Y. S.; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-01-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI–LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. PMID:26386258

  3. Conductivity of single-crystal Y1-yPryBa2Cu3O7-δ over a wide range of temperatures and Pr concentrations

    NASA Astrophysics Data System (ADS)

    Khadzhai, G. Ya.; Vovk, N. R.; Vovk, R. V.

    2014-06-01

    The in-plane electrical resistance of Y1-yPryBa2Cu3O7-δ single crystals with a high degree of perfection is studied for temperatures in the range TC-300 K, where TC ranges from 92 to 52 K, with varying praseodymium content. The experimental data are approximated by an expression that takes electron scattering on phonons and defects into account, as well as fluctuation conductivity in a 3D Aslamazov-Larkin model. According to the approximation data the Debye temperature ranges from 350-370 K, depending on the praseodymium content. The transverse coherence length is ˜1 Å.

  4. Experimental oxygen potentials for U1-yPryO2±x and thermodynamic assessment of the U-Pr-O system

    NASA Astrophysics Data System (ADS)

    McMurray, J. W.; Silva, C. M.

    2016-03-01

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U1-yPryO2±x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. The models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  5. Experimental oxygen potentials of U1-yPryO2± x and thermodynamic assessment of the U-Pr-O system

    DOE PAGES

    McMurray, Jake W.; Silva, Chinthaka M.

    2015-12-09

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U1-yPryO2± x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. Furthermore, the models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  6. Combined analysis of pri-miR-34b/c rs4938723 and TP53 Arg72Pro with cervical cancer risk.

    PubMed

    Yuan, Fang; Sun, Ruifen; Chen, Peng; Liang, Yundan; Ni, Shanshan; Quan, Yi; Huang, Juan; Zhang, Lin; Gao, Linbo

    2016-05-01

    miR-34 family members can form a p53-miR-34 positive feedback loop and induce apoptosis, DNA repair, angiogenesis, and cell cycle arrest. We conducted a case-control study to examine whether two polymorphisms (i.e., rs4938723 in the promoter of pri-miR-34b/c and TP53 Arg72Pro) were linked to the carcinogenesis of cervical cancer among Chinese Han women. Genotypes of the two polymorphisms in 328 cervical cancer patients and 568 control subjects were determined by using a polymerase chain reaction-restriction fragment length polymorphism assay. We found a significantly increased cervical cancer risk in the pri-miR-34b/c rs4938723 under dominant and overdominant model (CT/CC vs. TT: adjusted OR = 1.34, 95 % CI = 1.01-1.77; CT vs. TT/CC: adjusted OR = 1.37, 95 % CI = 1.05-1.80, respectively). Increased cervical cancer risks were also found in the TP53 Arg72Pro under a heterozygous comparison and overdominant model (CG vs. GG: adjusted OR = 1.44, 95 % CI = 1.06-1.95; CG vs. GG/CC: adjusted OR = 1.47, 95 % CI = 1.12-1.94, respectively). Stratification analysis showed that patients carrying the pri-miR-34b/c rs4938723 CT genotype had a significantly increased risk for developing poorly differential status and clinical stage I. Moreover, increased cancer risks were observed for the TP53 Arg72Pro polymorphism in patients with poorly differential status, clinical stage II, and without lymph node metastasis. Combined analysis revealed that the genotypes of rs4938723 CT/CC and TP53 Arg72Pro CG/CC had an increased cervical cancer risk (OR = 2.21, 95 % CI = 1.38-3.53). These findings suggest that the pri-miR-34b/c rs4938723 and TP53 Arg72Pro polymorphisms may contribute to the genesis of cervical cancer.

  7. Pri-Mir-34b/C and Tp-53 Polymorphisms are Associated With The Susceptibility of Papillary Thyroid Carcinoma

    PubMed Central

    Chen, Peng; Sun, Ruifen; Pu, Yan; Bai, Peng; Yuan, Fang; Liang, Yundan; Zhou, Bin; Wang, Yanyun; Sun, Yinghe; Zhu, Jingqiang; Zhang, Lin; Gao, Linbo

    2015-01-01

    Abstract Tumor suppressor p53 directly regulated the abundance of the miR-34b/c. The interaction might contribute to certain cancer. We hypothesized that rs4938723 in the promoter region of pri-miR-34b/c and TP-53 Arg72Pro may be related to the risk of papillary thyroid carcinoma (PTC). A total of 784 patients with PTC and 1006 healthy controls were recruited to participate in this study. The variants were discriminated using a polymerase chain reaction–restriction fragment length polymorphism method (PCR-RFLP). Additionally, the relative expression levels of miR-34b/c and TP-53 in 44 paired samples were revealed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). A significantly increased risk of PTC was observed in the miR-34b/c rs4938723 CT, CC, and CT/CC genotypes compared with the TT genotype (CT vs TT: adjusted odds ratio [OR] = 1.51, 95%confidence interval [CI] = 1.23–1.85; CC vs TT: adjusted OR = 1.89, 95%CI = 1.39–2.63; CT/CC vs TT: adjusted OR = 1.59, 95%CI = 1.30–1.92, respectively). Significantly increased PTC susceptibility was also associated with the TP-53 Arg72Pro CC and CG/CC genotypes compared with the GG genotype (CC vs GG: adjusted OR = 2.04, 95%CI = 1.54–2.70; CG/CC vs GG: adjusted OR = 1.35, 95%CI = 1.11–1.67, respectively). Stratification analysis revealed that patients carrying the TP-53 Arg72Pro C allele and CC genotype had a significantly increased risk for developing N1 (C vs. G: OR = 1.27, 95%CI = 1.03–1.56; CC vs. GG: OR = 1.62, 95%CI = 1.07–2.46, respectively). Combined analysis showed that the genotypes of rs4938723 CT/CC + TP-53CG/CC increased the risk of PTC compared with rs4938723TT + TP-53GG (OR = 2.25, 95%CI = 1.67–3.03). Additionally, level of miR-34b was significantly upregulated in PTC patients. These findings indicate that the miR-34b/c rs4938723 and TP-53 Arg72Pro polymorphisms may contribute to the

  8. Sun-induced Chlorophyll fluorescence and PRI improve remote sensing GPP estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

    NASA Astrophysics Data System (ADS)

    Perez-Priego, O.; Guan, J.; Rossini, M.; Fava, F.; Wutzler, T.; Moreno, G.; Carvalhais, N.; Carrara, A.; Kolle, O.; Julitta, T.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2015-07-01

    This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different Nitrogen (N) and Phosphorous (P) availability. Sun-induced chlorophyll Fluorescence yield computed at 760 nm (Fy760), scaled-photochemical reflectance index (sPRI), MERIS terrestrial-chlorophyll index (MTCI) and Normalized difference vegetation index (NDVI) were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy-chambers on the same locations sampled by the spectrometers. We hypothesized that light-use efficiency (LUE) models driven by remote sensing quantities (RSM) can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM). Particularly, we compared the performances of different RSM formulations - relying on the use of Fy760 or sPRI as proxy for LUE and NDVI or MTCI as fraction of absorbed photosynthetically active radiation (fAPAR) - with those of classical MM. Results showed significantly higher GPP in the N fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was tightly related to plant N content (r2 = 0.86, p < 0.01), it was poorly related to GPP (r2 = 0.45, p < 0.05). On the contrary sPRI and Fy760 correlated well with GPP during the whole measurement period. Results revealed that the relationship between GPP and Fy760 is not unique across treatments but it is affected by N availability. Results from a cross validation analysis showed that MM (AICcv = 127, MEcv = 0.879) outperformed RSM (AICcv = 140, MEcv = 0.8737) when soil moisture was used to constrain the seasonal dynamic of LUE. However, residual analyses

  9. Base-pair opening dynamics of the microRNA precursor pri-miR156a affect temperature-responsive flowering in Arabidopsis.

    PubMed

    Kim, Hee-Eun; Kim, Wanhui; Lee, Ae-Ree; Jin, Suhyun; Jun, A Rim; Kim, Nak-Kyoon; Lee, Joon-Hwa; Ahn, Ji Hoon

    2017-03-18

    Internal and environmental cues, including ambient temperature changes, regulate the timing of flowering in plants. Arabidopsis miR156 represses flowering and plays an important role in the regulation of temperature-responsive flowering. However, the molecular basis of miR156 processing at lower temperatures remains largely unknown. Here, we performed nuclear magnetic resonance studies to investigate the base-pair opening dynamics of model RNAs at 16 °C and investigated the in vivo effects of the mutant RNAs on temperature-responsive flowering. The A9C and A10CG mutations in the B5 bulge of the lower stem of pri-miR156a stabilized the C15∙G98 and U16∙A97 base-pairs at the cleavage site of pri-miR156a at 16 °C. Consistent with this, production of mature miR156 was severely affected in plants overexpressing the A9C and A10CG constructs and these plants exhibited almost no delay in flowering at 16 °C. The A10G and A9AC mutations did not strongly affect C15∙G98 and U16∙A97 base-pairs at 16 °C, and plants overexpressing A10G and A9AC mutants of miR156 produced more mature miR156 than plants overexpressing the A9C and A10CG mutants and showed a strong delay in flowering at 16 °C. Interestingly, the A9AC mutation had distinct effects on the opening dynamics of the C15∙G98 and U16∙A97 base-pairs between 16 °C and 23 °C, and plants expressing the A9AC mutant miR156 showed only a moderate delay in flowering at 16 °C. Based on these results, we propose that fine-tuning of the base-pair stability at the cleavage site is essential for efficient processing of pri-miR156a at a low temperature and for reduced flowering sensitivity to ambient temperature changes.

  10. Conductivity anisotropy in Y1-yPryBa2Cu3O7-δ single crystals in a wide range of praseodymium concentrations

    NASA Astrophysics Data System (ADS)

    Vovk, Ruslan V.; Khadzhai, Georgij Ya.; Dobrovolskiy, Oleksandr V.

    2014-12-01

    Anisotropies of different conductivity mechanisms in Y1-yPryBa2Cu3O7-δ single crystals in a wide range of praseodymium concentrations are reported, assuming a transition from the metallic conductivity to the semiconductor-like regime, in conjunction with the fluctuation conductivity within the 3D Aslamazov-Larkin model. The Tc anisotropy grows with increasing y, with a most drastic rise when approaching the non-superconducting composition. As the praseodymium concentration increases, the ideal resistance anisotropy passes through a maximum at y ≈ 0.19. The temperature dependence of the semiconductor-like resistance anisotropy exhibits a maximum associated with variable-range jumps along the c-axis. The temperature dependence of the fluctuation conductivity anisotropy passes through a maximum due to a significant anisotropy of the coherence length.

  11. A novel marsupial pri-miRNA transcript has a putative role in gamete maintenance and defines a vertebrate miRNA cluster paralogous to the miR-15a/miR-16-1 cluster.

    PubMed

    Au, Phil Chi Khang; Frankenberg, Stephen; Selwood, Lynne; Familari, Mary

    2011-10-01

    Successful maintenance, survival and maturation of gametes rely on bidirectional communication between the gamete and its supporting cells. Before puberty, factors from the gamete and its supporting cells are necessary for spermatogonial stem cell and primordial follicle oocyte maintenance. Following gametogenesis, gametes rely on factors and nutrients secreted by cells of the reproductive tracts, the epididymis and/or oviduct, to complete maturation. Despite extensive studies on female and male reproduction, many of the molecular mechanisms of germ cell maintenance remain relatively unknown, particularly in marsupial species. We present the first study and characterisation of a novel primary miRNA transcript, pri-miR-16c, in the marsupial, the stripe-faced dunnart. Bioinformatic analysis showed that its predicted processed miRNA - miR-16c - is present in a wide range of vertebrates, but not eutherians. In situ hybridisation revealed dunnart pri-miR-16c expression in day 4 (primordial germ cells) and day 7 (oogonia) pouch young, in primary oocytes and follicle cells of primordial follicles but then only in follicle cells of primary, secondary and antral follicles in adult ovaries. In the adult testis, pri-miR-16c transcripts were present in the cytoplasm of spermatogonial cells. The oviduct and the epididymis both showed expression, but not any other somatic tissues examined or conceptuses during early embryonic development. This pattern of expression suggests that pri-miR-16c function may be associated with gamete maintenance, possibly through mechanisms involving RNA transfer, until the zygote enters the uterus at the pronuclear stage.

  12. The N-Terminal Domain of the E. coli PriA Helicase Contains Both the DNA- and the Nucleotide-Binding Sites. Energetics of Domain-DNA Interactions and Allosteric Effect of the Nucleotide Cofactors§

    PubMed Central

    Szymanski, Michal R.; Bujalowski, Paul J.; Jezewska, Maria J.; Gmyrek, Aleksandra M.; Bujalowski, Wlodzimierz

    2011-01-01

    Functional interactions of the E. coli PriA helicase 181N-terminal domain with the DNA and nucleotide cofactors have been quantitatively examined. The isolated 181N-terminal domain forms a stable dimer in solution, most probably reflecting the involvement of the domain in specific cooperative interactions of the intact PriA protein - dsDNA complex. Only one monomer of the domain dimer binds the DNA, i.e., the dimer has one effective DNA-binding site. Although the total site-size of the dimer - ssDNA complex is ~13 nucleotides, the DNA-binding subsite engages in direct interactions ~5 nucleotides. A small number of interacting nucleotides indicates that the DNA-binding subsites of the PriA helicase, i.e., the strong subsite on the helicase domain and the weak subsite on the N-terminal domain, are spatially separated in the intact enzyme. Contrary to current views, the subsite has only a slight preference for the 3′-end OH group of the ssDNA and lacks any significant base specificity, although it has a significant dsDNA affinity. Unlike the intact helicase, the DNA-binding subsite of the isolated domain is in an open conformation, indicating the presence of the direct helicase domain - N-terminal domain interactions. The discovery that the 181N-terminal domain possesses a nucleotide-binding site places the allosteric, weak nucleotide-binding site of the intact PriA on the N-terminal domain. The specific ADP effect on the domain DNA-binding subsite indicates that in the intact helicase, the bound ADP not only opens the DNA-binding subsite but also increases its intrinsic DNA affinity. PMID:21888358

  13. Optimization of growth conditions for (La1-yPry)1-x CaxMnO3 thin films on annealed oxide substrates

    NASA Astrophysics Data System (ADS)

    Schaefer, Brian; Grant, Daniel; Biswas, Amlan

    2014-03-01

    Consistent growth of flat, epitaxial thin films is essential for uncovering the unique transport characteristics of rare-earth manganite systems. We have developed pulsed laser deposition growth conditions for (La1-yPry)1-x CaxMnO3 (LPCMO, y = 0.4, 0.5, 0.6) thin films on annealed NdGaO3 (NGO) and SrTiO3 (STO) substrates. The extra annealing step for NGO and STO produces atomically flat substrates with well-defined terraces of unit cell step height. Films grown on these annealed substrates demonstrate better lattice matching compared to films grown on as-received substrates. Consequently, annealing substrates before film growth leads to higher quality thin films with a more controllable thickness. We demonstrate that these optimized growth parameters yield LPCMO thin films that are also atomically flat, as confirmed by atomic force microscopy. We are using these thin films to restrict phase growth to reduced dimensions and to study the origin of thermodynamic phase competition due to first order transitions in manganites. NSF DMR-0804452

  14. Ground state partial radiative widths of /sup 207/Pb + n resonances and M1 and E2 strengths in /sup 208/Pb

    SciTech Connect

    Weigmann, H.; Koehler, R.; Poortmans, F.; Raman, S.; Wartena, J.A.

    1987-08-01

    Ground state partial radiative widths of neutron resonances in /sup 207/Pb + n have been measured. A resonance analysis has been carried out in a complete manner below 700 keV neutron energy, and for selected strongly radiation resonances up to 1 MeV. The total magnetic dipole strength detected above neutron separation energy is only 6.8 ..mu../sub 0//sup 2/, but the observed appreciable fragmentation of the M1 strength suggests that considerable strength is missed at excitation energies above 8 MeV. The electric quadrupole strength observed between neutron separation energy and 8.2 MeV is distributed rather uniformly, and corresponds to 4.9% of the energy-weighted sum-rule for isoscalar E2 transitions. 10 refs., 2 figs.

  15. Schottky Mass Measurement of the {sup 208}Hg Isotope: Implication for the Proton-Neutron Interaction Strength around Doubly Magic {sup 208}Pb

    SciTech Connect

    Chen, L.; Plass, W. R.; Geissel, H.; Scheidenberger, C.; Litvinov, Yu. A.; Beckert, K.; Beller, P.; Bosch, F.; Caceres, L.; Franzke, B.; Gerl, J.; Gorska, M.; Knoebel, R.; Kozhuharov, C.; Litvinov, S. A.; Mandal, S.; Muenzenberg, G.; Nolden, F.; Saito, N.; Saito, T.

    2009-03-27

    Time-resolved Schottky mass spectrometry has been applied to uranium projectile fragments which yielded the mass value for the {sup 208}Hg (Z=80, N=128) isotope. The mass excess value of ME=-13 265(31) keV has been obtained, which has been used to determine the proton-neutron interaction strength in {sup 210}Pb, as a double difference of atomic masses. The results show a dramatic variation of the strength for lead isotopes when crossing the N=126 neutron shell closure, thus confirming the empirical predictions that this interaction strength is sensitive to the overlap of the wave functions of the last valence neutrons and protons.

  16. A Simple and High-Throughput Analysis of Amatoxins and Phallotoxins in Human Plasma, Serum and Urine Using UPLC-MS/MS Combined with PRiME HLB μElution Platform

    PubMed Central

    Zhang, Shuo; Zhao, Yunfeng; Li, Haijiao; Zhou, Shuang; Chen, Dawei; Zhang, Yizhe; Yao, Qunmei; Sun, Chengye

    2016-01-01

    Amatoxins and phallotoxins are toxic cyclopeptides found in the genus Amanita and are among the predominant causes of fatal food poisoning in China. In the treatment of Amanita mushroom poisoning, an early and definite diagnosis is necessary for a successful outcome, which has prompted the development of protocols for the fast and confirmatory determination of amatoxins and phallotoxins in human biological fluids. For this purpose, a simple, rapid and sensitive multiresidue UPLC-MS/MS method for the simultaneous determination of α-amanitin, β-amanitin, γ-amanitin, phalloidin (PHD) and phallacidin (PCD) in human plasma, serum and urine was developed and validated. The diluted plasma, serum and urine samples were directly purified with a novel PRiME technique on a 96-well μElution plate platform, which allowed high-throughput sample processing and low reagent consumption. After purification, a UPLC-MS/MS analysis was performed using positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode. This method fulfilled the requirements of a validation test, with good results for the limit of detection (LOD), lower limit of quantification (LLOQ), accuracy, intra- and inter-assay precision, recovery and matrix effects. All of the analytes were confirmed and quantified in authentic plasma, serum and urine samples obtained from cases of poisoning using this method. Using the PRiME μElution technique for quantification reduces labor and time costs and represents a suitable method for routine toxicological and clinical emergency analysis. PMID:27153089

  17. A Simple and High-Throughput Analysis of Amatoxins and Phallotoxins in Human Plasma, Serum and Urine Using UPLC-MS/MS Combined with PRiME HLB μElution Platform.

    PubMed

    Zhang, Shuo; Zhao, Yunfeng; Li, Haijiao; Zhou, Shuang; Chen, Dawei; Zhang, Yizhe; Yao, Qunmei; Sun, Chengye

    2016-05-04

    Amatoxins and phallotoxins are toxic cyclopeptides found in the genus Amanita and are among the predominant causes of fatal food poisoning in China. In the treatment of Amanita mushroom poisoning, an early and definite diagnosis is necessary for a successful outcome, which has prompted the development of protocols for the fast and confirmatory determination of amatoxins and phallotoxins in human biological fluids. For this purpose, a simple, rapid and sensitive multiresidue UPLC-MS/MS method for the simultaneous determination of α-amanitin, β-amanitin, γ-amanitin, phalloidin (PHD) and phallacidin (PCD) in human plasma, serum and urine was developed and validated. The diluted plasma, serum and urine samples were directly purified with a novel PRiME technique on a 96-well μElution plate platform, which allowed high-throughput sample processing and low reagent consumption. After purification, a UPLC-MS/MS analysis was performed using positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode. This method fulfilled the requirements of a validation test, with good results for the limit of detection (LOD), lower limit of quantification (LLOQ), accuracy, intra- and inter-assay precision, recovery and matrix effects. All of the analytes were confirmed and quantified in authentic plasma, serum and urine samples obtained from cases of poisoning using this method. Using the PRiME μElution technique for quantification reduces labor and time costs and represents a suitable method for routine toxicological and clinical emergency analysis.

  18. Preliminary evidence for association of genetic variants in pri-miR-34b/c and abnormal miR-34c expression with attention deficit and hyperactivity disorder

    PubMed Central

    Garcia-Martínez, I; Sánchez-Mora, C; Pagerols, M; Richarte, V; Corrales, M; Fadeuilhe, C; Cormand, B; Casas, M; Ramos-Quiroga, J A; Ribasés, M

    2016-01-01

    Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by impairment to sustain attention and inability to control impulses and activity level. The etiology of ADHD is complex, with an estimated heritability of 70–80%. Under the hypothesis that alterations in the processing or target binding of microRNAs (miRNAs) may result in functional alterations predisposing to ADHD, we explored whether common polymorphisms potentially affecting miRNA-mediated regulation are involved in this psychiatric disorder. We performed a comprehensive association study focused on 134 miRNAs in 754 ADHD subjects and 766 controls and found association between the miR-34b/c locus and ADHD. Subsequently, we provided preliminary evidence for overexpression of the miR-34c-3p mature form in peripheral blood mononuclear cells of ADHD subjects. Next, we tested the effect on gene expression of single-nucleotide polymorphisms within the ADHD-associated region and found that rs4938923 in the promoter of the pri-miR-34b/c tags cis expression quantitative trait loci for both miR-34b and miR-34c and has an impact on the expression levels of 681 transcripts in trans, including genes previously associated with ADHD. This gene set was enriched for miR-34b/c binding sites, functional categories related to the central nervous system, such as axon guidance or neuron differentiation, and serotonin biosynthesis and signaling canonical pathways. Our results provide preliminary evidence for the contribution to ADHD of a functional variant in the pri-miR-34b/c promoter, possibly through dysregulation of the expression of mature forms of miR-34b and miR-34c and some target genes. These data highlight the importance of abnormal miRNA function as a potential epigenetic mechanism contributing to ADHD. PMID:27576168

  19. Substrate-dependent post-annealing effects on the strain state and electrical transport of epitaxial La5/8-yPryCa3/8MnO3 films

    NASA Astrophysics Data System (ADS)

    Hu, Sixia; Huang, Haoliang; Yang, Yuanjun; Luo, Zhenlin; Yang, Mengmeng; Wang, Haibo; Dong, Yongqi; Hong, Bing; He, Hao; Bao, Jun; Gao, Chen

    2014-06-01

    Large scale electronic phase separation (EPS) between ferromagnetic metallic and charge-ordered insulating phases in La5/8-yPryCa3/8MnO3 (y = 0.3) (LPCMO) is very sensitive to the structural changes. This work investigates the effects of post-annealing on the strain states and electrical transport properties of LPCMO films epitaxially grown on (001)pc SrTiO3 (tensile strain), LaAlO3 (compressive strain) and NdGaO3 (near-zero strain) substrates. Before annealing, all the films are coherent-epitaxial and insulating through the measured temperature range. Obvious change of film lattice is observed during the post-annealing: the in-plane strain in LPCMO/LAO varies from -1.5% to -0.1% while that in LPCMO/STO changes from 1.6% to 1.3%, and the lattice of LPCMO/NGO keeps constant because of the good lattice-match between LPCMO and NGO. Consequently, the varied film strain leads to the emergence of metal-insulator transitions (MIT) and shift of the critical transition temperature in the electrical transport. These results demonstrate that lattice-mismatch combined with post-annealing is an effective approach to tune strain in epitaxial LPCMO films, and thus to control the EPS and MIT in the films.

  20. Are the SSB-Interacting Proteins RecO, RecG, PriA and the DnaB-Interacting Protein Rep Bound to Progressing Replication Forks in Escherichia coli?

    PubMed Central

    Matelot, Mélody; Allemand, Jean-François; Michel, Bénédicte

    2015-01-01

    In all organisms several enzymes that are needed upon replication impediment are targeted to replication forks by interaction with a replication protein. In most cases these proteins interact with the polymerase clamp or with single-stranded DNA binding proteins (SSB). In Escherichia coli an accessory replicative helicase was also shown to interact with the DnaB replicative helicase. Here we have used cytological observation of Venus fluorescent fusion proteins expressed from their endogenous loci in live E. coli cells to determine whether DNA repair and replication restart proteins that interact with a replication protein travel with replication forks. A custom-made microscope that detects active replisome molecules provided that they are present in at least three copies was used. Neither the recombination proteins RecO and RecG, nor the replication accessory helicase Rep are detected specifically in replicating cells in our assay, indicating that either they are not present at progressing replication forks or they are present in less than three copies. The Venus-PriA fusion protein formed foci even in the absence of replication forks, which prevented us from reaching a conclusion. PMID:26244508

  1. Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8–yPryCa3/8MnO₃ manganites

    DOE PAGES

    Bingham, N. S.; Lampen, P.; Phan, M. H.; ...

    2012-08-16

    Bulk manganites of the form La5/8–yPryCa3/8MnO₃ (LPCMO) exhibit a complex phase diagram due to coexisting charge-ordered antiferromagnetic (CO/AFM), charge-disordered paramagnetic (PM), and ferromagnetic (FM) phases. Because phase separation in LPCMO occurs on the microscale, reducing particle size to below this characteristic length is expected to have a strong impact on the magnetic properties of the system. Through a comparative study of the magnetic and magnetocaloric properties of single-crystalline (bulk) and nanocrystalline LPCMO (y=3/8) we show that the AFM, CO, and FM transitions seen in the single crystal can also be observed in the large particle sizes (400 and 150 nm),more » while only a single PM to FM transition is found for the small particles (55 nm). Magnetic and magnetocaloric measurements reveal that decreasing particle size affects the balance of competing phases in LPCMO and narrows the range of fields over which PM, FM, and CO phases coexist. The FM volume fraction increases with size reduction, until CO is suppressed below some critical size, ~100 nm. With size reduction, the saturation magnetization and field sensitivity first increase as long-range CO is inhibited, then decrease as surface effects become increasingly important. The trend that the FM phase is stabilized on the nanoscale is contrasted with the stabilization of the charge-disordered PM phase occurring on the microscale, demonstrating that in terms of the characteristic phase separation length, a few microns and several hundred nanometers represent very different regimes in LPCMO.« less

  2. Multiple magnetic transitions, dynamical magnetic liquid and magnetic glass in La1-x-yPryCaxMnO3 (x≈0.42, y≈0.40) thin films: A thickness dependent study

    NASA Astrophysics Data System (ADS)

    Agarwal, Vasudha; Kandpal, Lalit M.; Siwach, P. K.; Awana, V. P. S.; Singh, H. K.

    2015-11-01

    The influence of substrate induced strain and its relaxation on the evolution of the multiple magnetic transitions and ensuing modifications in the degree of phase separation, the nature of the dynamical magnetic liquid, the randomly frozen glass and insulator-metal transitions have been investigated in single crystalline La1-x-yPryCaxMnO3 (x≈0.42, y≈0.40) in t~20-140 nm thick films deposited on LaAlO3 (001) substrates. The ferromagnetic (FM) transition temperature (TC) first decreases as the film thickness is increased from t~20 nm to t~60 nm and then increases with increasing film thickness. In contrast the charge ordering (CO), antiferromagnetic (AFM) and glass transition temperatures shift towards higher values with increasing film thickness. The field cooled cooling (FCC) and field cooled warming (FCW) magnetization (M-T) of films having t≥60 nm shows pronounced hysteresis and ΔTC=TCFCW-TCFCC decreases concomitantly from 46 K to 35 K as the thickness increases from ~60 to ~140 nm. The thinnest film shows insulator to metal transitions (IMT) only at magnetic field H>40 kOe. Films with t≥TC show sharp hysteretic IMT, with ΔTIM=TIMW-TIMC decreasing from ~70 K to ~50 K as the thickness increases from ~60 nm to ~140 nm. Such strong hysteresis is a characteristic of first order phase transition and also a signature of magnetic liquid like phase created by the magnetic frustration created by the delicate balance between FM and AFM/CO phases. The H induced AFM/CO to FM transition reduces ΔTIM and at higher fields the phase transition appears akin to the second order. The observed difference in the magnetic and transport properties have been explained in terms of the substrate induced strain at lower film thickness and its relaxation at higher thickness.

  3. Pendant alkyl and aryl groups on tin control complex geometry and reactivity with H2/D2 in Pt(SnR3)2(CNBu(t))2 (R = Bu(t), Pr(i), Ph, mesityl).

    PubMed

    Koppaka, Anjaneyulu; Zhu, Lei; Yempally, Veeranna; Isrow, Derek; Pellechia, Perry J; Captain, Burjor

    2015-01-14

    The complex Pt(SnBu(t)3)2(CNBu(t))2(H)2, 1, was obtained from the reaction of Pt(COD)2 and Bu(t)3SnH, followed by addition of CNBu(t). The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield Pt(SnBu(t)3)2(CNBu(t))2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenerates 1. Complex 2 catalyzes H2-D2 exchange in solution to give HD. The proposed mechanism of exchange involves reductive elimination of Bu(t)3SnH from 1 to afford vacant sites on the Pt center, thus facilitating the exchange process. This is supported by isolation and characterization of Pt(SnMes3)(SnBu(t)3)(CNBu(t))2, 3, when the addition of H2 to 2 was carried out in the presence of free ligand Mes3SnH (Mes = 2,4,6-Me3C6H2). Complex Pt(SnMes3)2(CNBu(t))2, 5, can be prepared from the reaction of Pt(COD)2 with Mes3SnH and CNBu(t). The exchange reaction of 2 with Ph3SnH gave Pt(SnPh3)3(CNBu(t))2(H), 6, wherein both SnBu(t)3 ligands are replaced by SnPh3. Complex 6 decomposes in air to form square planar Pt(SnPh3)2(CNBu(t))2, 7. The complex Pt(SnPr(i)3)2(CNBu(t))2, 8, was also prepared. Out of the four analogous complexes Pt(SnR3)2(CNBu(t))2 (R = Bu(t), Mes, Ph, or Pr(i)), only the Bu(t) analogue does both H2 activation and H2-D2 exchange. This is due to steric effects imparted by the bulky Bu(t) groups that distort the geometry of the complex considerably from planarity. The reaction of Pt(COD)2 with Bu(t)3SnH and CO gas afforded trans-Pt(SnBu(t)3)2(CO)2, 9. Compound 9 can be converted to 2 by replacement of the CO ligands with CNBu(t) via the intermediate Pt(SnBu(t)3)2(CNBu(t))2(CO), 10.

  4. PRI and the Beyond Merida Initiative

    DTIC Science & Technology

    2011-10-28

    candidate, Andres Manuel Lopez , called for the de- militarization of our bilateral agenda while speaking to a U.S. think tank.9 Santiago Creel Miranda, a... manuel -l%C3%B3pez- obrador (accessed October 16, 2011) 10 Elimparcial. “Anti-narco fight will change if president: Creel,” http...Wilson Institute for Scholars: Mexico Institute. http://www.wilsoncenter.org/event/dialogues-mexicodi%C3%A1logos-con-m%C3%A9xico- featuring- andr %C3%A9s

  5. Analysis of the role of neutron transfer in asymmetric fusion reactions at subbarrier energies

    SciTech Connect

    Ogloblin, A. A.; Zhang, H. Q.; Lin, C. J.; Jia, H. M.; Khlebnikov, S. V.; Kuzmin, E. A.; Danilov, A. N.; Demyanova, A. S.; Trzaska, W. H.; Xu, X. X.; Yang, F.; Sargsyan, V. V. Adamian, G. G.; Antonenko, N. V.; Scheid, W.

    2015-12-15

    The excitation functions were measured for the {sup 28}Si + {sup 208}Pb complete-fusion (capture) reaction at deep subbarrier energies. The results were compared with the cross sections predicted within the quantum diffusion approach. The role of neutron transfer in the case of positive Q values in the {sup 28}Si + {sup 124}Sn, {sup 208}Pb; {sup 30}Si + {sup 124}Sn, {sup 208}Pb; {sup 20}Ne + {sup 208}Pb; {sup 40}Ca + {sup 96}Zr; and {sup 134}Te + {sup 40}Ca complete-fusion (capture) reactions is discussed.

  6. Theoretical study on production of heavy neutron-rich isotopes around the N = 126 shell closure in radioactive beam induced transfer reactions

    NASA Astrophysics Data System (ADS)

    Zhu, Long; Su, Jun; Xie, Wen-Jie; Zhang, Feng-Shou

    2017-04-01

    In order to produce more unknown neutron-rich nuclei around N = 126, the transfer reactions 136Xe + 198Pt, 136-144Xe + 208Pb, and 132Sn + 208Pb are investigated within the framework of the dinuclear system (DNS) model. The influence of neutron excess of projectile on production cross sections of target-like products is studied through the reactions 136,144Xe + 208Pb. We find that the radioactive projectile 144Xe with much larger neutron excess is favorable to produce neutron-rich nuclei with charge number less than the target rather than produce transtarget nuclei. The incident energy dependence of yield distributions of fragments in the reaction 132Sn + 208Pb are also studied. The production cross sections of neutron-rich nuclei with Z = 72- 77 are predicted in the reactions 136-144Xe + 208Pb and 132Sn + 208Pb. It is noticed that the production cross sections of unknown neutron-rich nuclei in the reaction 144Xe + 208Pb are at least two orders of magnitude larger than those in the reaction 136Xe + 208Pb. The radioactive beam induced transfer reactions 139,144Xe + 208Pb, considering beam intensities proposed in SPIRAL2 (Production System of Radioactive Ion and Acceleration On-Line) project as well, for production of neutron-rich nuclei around the N = 126 shell closure are investigated for the first time. It is found that, in comparison to the stable beam 136Xe, the radioactive beam 144Xe shows great advantages for producing neutron-rich nuclei with N = 126 and the advantages get more obvious for producing nuclei with less charge number.

  7. The Politics of Parental Involvement: How Opportunity Hoarding and Prying Shape Educational Opportunity

    ERIC Educational Resources Information Center

    Lyken-Segosebe, Dawn; Hinz, Serena E.

    2015-01-01

    As more state legislatures join the debate on school-choice and parent-trigger legislation, their discussions draw attention to an evolving landscape outside school walls where parental action shapes educational opportunity. Parents wield their political, social, economic, and cultural capital to secure the best educational outcomes for their…

  8. Coherent Processing Across Multiple Staggered Pulse Repetition Interval (PRI) Dwells in Radar

    DTIC Science & Technology

    2004-02-01

    method”, Anal. Chem., Vol. 63, pp. 534-536, 1991. [25] P. P. Vaidyanathan, Multirate Systems and Filter Banks , 1993, Prentice-Hall, Englewood Cliffs...an unevenly sampled signal using multirate filter banks , a multi-resolution approach has been taken by Vaidyanathan [25, 26 and 27]. It is possible...NJ. [26] P. P. Vaidyanathan, and V. C. Liu, “Classical sampling theorems in the context of multirate and polyphase digital filter bank structure

  9. Sensor4PRI: a sensor platform for the protection of railway infrastructures.

    PubMed

    Cañete, Eduardo; Chen, Jaime; Díaz, Manuel; Llopis, Luis; Rubio, Bartolomé

    2015-02-27

    Wireless Sensor Networks constitute pervasive and distributed computing systems and are potentially one of the most important technologies of this century. They have been specifically identified as a good candidate to become an integral part of the protection of critical infrastructures. In this paper we focus on railway infrastructure protection and we present the details of a sensor platform designed to be integrated into a slab track system in order to carry out both installation and maintenance monitoring activities. In the installation phase, the platform helps operators to install the slab tracks in the right position. In the maintenance phase, the platform collects information about the structural health and behavior of the infrastructure when a train travels along it and relays the readings to a base station. The base station uses trains as data mules to upload the information to the internet. The use of a train as a data mule is especially suitable for collecting information from remote or inaccessible places which do not have a direct connection to the internet and require less network infrastructure. The overall aim of the system is to deploy a permanent economically viable monitoring system to improve the safety of railway infrastructures.

  10. Introns of plant pri-miRNAs enhance miRNA biogenesis

    PubMed Central

    Bielewicz, Dawid; Kalak, Malgorzata; Kalyna, Maria; Windels, David; Barta, Andrea; Vazquez, Franck; Szweykowska-Kulinska, Zofia; Jarmolowski, Artur

    2013-01-01

    Plant MIR genes are independent transcription units that encode long primary miRNA precursors, which usually contain introns. For two miRNA genes, MIR163 and MIR161, we show that introns are crucial for the accumulation of proper levels of mature miRNA. Removal of the intron in both cases led to a drop-off in the level of mature miRNAs. We demonstrate that the stimulating effects of the intron mostly reside in the 5′ss rather than on a genuine splicing event. Our findings are biologically significant as the presence of functional splice sites in the MIR163 gene appears mandatory for pathogen-triggered accumulation of miR163 and proper regulation of at least one of its targets. PMID:23681439

  11. Autonomic Disorders in Cervical Migraine (O Vegetativnykh Narusheniyakh pri Sheinoi Migreni),

    DTIC Science & Technology

    In cervical migraine the main symptoms are persistent headaches, frequently of the hemicrania type. The pains start in the cerico-occipital region...head: they increase with the slightest movement, and decrease at rest. Some time after the start of the sickness, cervical radicular symptoms are...added which attract the examiner’s attention to the cervical segment of the spine. In recent years, many studies proved that an entire series of cardio

  12. Importance of the Radicular Syndrome in Cervical Migraine (O Znachenii Radikulyarnogo Sindroma pri Sheinoi Migreni),

    DTIC Science & Technology

    The direct causes of cerebral disorders in cervical migraine are compression of the vertebral artery and irritation of the vertebral nerve by... cervical osteophytes, deformed uncinate processes, as well as the pathological afferentation which occurs here. One hundred ten patients suffering from... cervical migraine were observed. The most characteristic symptoms are constant dull, frequently unilateral headaches with typical irradiation from the

  13. Characteristic Headaches with Cervical Migraine (O Kharakteristike Golovnoi Boli pri Sheinoi Migreni),

    DTIC Science & Technology

    Headache is the leading symptom of cervical migraine. The localization and irradiation of pains, the characteristic gesture of the patients, the...characteristics of cervical migraine. It must be assumed that knowledge through further studies of the clinical aspects and diagnosis of this...widespread disease will eventually reach all practicing physicians, and that in time ’ cervical migraine’ will become a common diagnosis at any polyclinic. (Author)

  14. School Internal Investigations of Employees, Open Records Laws, and the Prying Press.

    ERIC Educational Resources Information Center

    Remington, Lee R.

    2002-01-01

    Discusses history and purpose of state open-records laws. Surveys how parties make open-records requests, various causes of action, and sanctions for noncompliance. Examines how open-records requests related to district investigations can implicate the Family Education Rights and Privacy Act. Attempts to find appropriate balance between public's…

  15. Directional hyperspectral observations to detect plant stress with the PRI and SIF in a cornfield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the impact of drought stress and temperature on plant hyperspectral, fluorescence, and photosynthetic responses during the 2012 growing season at an experimental USDA (United States Department of Agriculture) cornfield in Beltsville, MD USA. The manipulations included 4 nitrogen (N) appl...

  16. Prying the Gates Wide Open: Academic Freedom and Gender Equality at Brown University, 1974-1977

    ERIC Educational Resources Information Center

    Porwancher, Andrew

    2013-01-01

    In 1974, Brown University's Department of Anthropology denied tenure to assistant professor Louise Lamphere. Convinced that her dismissal was the product of sex discrimination, Lamphere filed suit against Brown. Lamphere and three other female scholars who joined her suit successfully pressed Brown into an out-of-court settlement in 1977.…

  17. Sensor4PRI: A Sensor Platform for the Protection of Railway Infrastructures

    PubMed Central

    Cañete, Eduardo; Chen, Jaime; Díaz, Manuel; Llopis, Luis; Rubio, Bartolomé

    2015-01-01

    Wireless Sensor Networks constitute pervasive and distributed computing systems and are potentially one of the most important technologies of this century. They have been specifically identified as a good candidate to become an integral part of the protection of critical infrastructures. In this paper we focus on railway infrastructure protection and we present the details of a sensor platform designed to be integrated into a slab track system in order to carry out both installation and maintenance monitoring activities. In the installation phase, the platform helps operators to install the slab tracks in the right position. In the maintenance phase, the platform collects information about the structural health and behavior of the infrastructure when a train travels along it and relays the readings to a base station. The base station uses trains as data mules to upload the information to the internet. The use of a train as a data mule is especially suitable for collecting information from remote or inaccessible places which do not have a direct connection to the internet and require less network infrastructure. The overall aim of the system is to deploy a permanent economically viable monitoring system to improve the safety of railway infrastructures. PMID:25734648

  18. Miniature Electron Sources for Tomorrow’s Vacuum THz Devices (MiPRI)

    DTIC Science & Technology

    2006-07-01

    slotted slow-wave structure show that the circuit could be With H = 2mm, the ohmic Q- factor , depending on the choice driven at 3-4 times the starting...least a factor of 2, which results (SWS) within an open resonator [I). However, typical in the range of nominal current densities of about 130 A/cm 2...length, P3o is the velocity of the electrons normalized to the speed of light, c, Vb is the beam voltage and Qohm is the ohmic quality factor . It

  19. Fearing Prying U.S. Eyes, Canada's Colleges Crack Down On Computing

    ERIC Educational Resources Information Center

    Carnevale, Dan

    2007-01-01

    The USA Patriot Act is having far-reaching effects on the kinds of data that wind up on some academics' computers in Canada. Canadian colleges, responding to provincial laws passed in reaction to the Patriot Act, are preventing professors from entering the United States with students' private data on their laptops and limiting the locations of…

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

    SciTech Connect

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

    2010-09-15

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

  1. Total and partial photoneutron cross sections for Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kondo, T.; Utsunomiya, H.; Goriely, S.; Daoutidis, I.; Iwamoto, C.; Akimune, H.; Okamoto, A.; Yamagata, T.; Kamata, M.; Itoh, O.; Toyokawa, H.; Lui, Y.-W.; Harada, H.; Kitatani, F.; Hilaire, S.; Koning, A. J.

    2012-07-01

    Using quasimonochromatic laser-Compton scattering γ rays, total photoneutron cross sections were measured for 206,207,208Pb near neutron threshold with a high-efficiency 4π neutron detector. Partial E1 and M1 photoneutron cross sections along with total cross sections were determined for 207,208Pb at four energies near threshold by measuring anisotropies in photoneutron emission with linearly polarized γ rays. The E1 strength dominates over the M1 strength in the neutron channel where E1 photoneutron cross sections show extra strength of the pygmy dipole resonance in 207,208Pb near the neutron threshold corresponding to 0.32%-0.42% of the Thomas-Reiche-Kuhn sum rule. Several μN2 units of B(M1)↑ strength were observed in 207,208Pb just above neutron threshold, which correspond to an M1 cross section less than 10% of the total photoneutron cross section.

  2. 7 CFR 14.6 - Criteria for determining the pri- mary purpose of payments with respect to potential exclusion...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the productive capacity of the resource regardless of the level of technology available or applied... the productive capacity of the soil are forms of soil deterioration. (b) Water conservation. (1) Water... this section. (c) Protecting the environment. (1) Payments shall be considered to be made primarily...

  3. 7 CFR 14.6 - Criteria for determining the pri- mary purpose of payments with respect to potential exclusion...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the productive capacity of the resource regardless of the level of technology available or applied.... (3) Habitat includes, but is not limited to, the food supply, water supply, and nesting and escape... habitat are domestic crops raised for the primary purpose of providing food supply or cover for...

  4. Diurnal Patterns of Photosynthesis, Chlorophyll Fluorescence, and PRI to Evaluate Water Stress in the Invasive Species, Elaeagnus umbellata Thunb

    DTIC Science & Technology

    2010-01-01

    Phytol 165:463–472 Morales F, Abadı́a A, Abadı́a J, Montserrat G, Gil-Pelegrı́n E (2002) Trichomes and photosynthetic pigment composition changes...photoprotective mechanism at work for Elaeagnus species under water stress. Elaeagnus umbellata maintains photosynthetic carbon assimilation even...radiation while maximizing photosynthetic carbon gain. These characteristics may contribute to the invasive success of E. umbellata. REPORT DOCUMENTATION

  5. A Multimethod Assessment of Juvenile Psychopathy: Comparing the Predictive Utility of the PCL:YV, YPI, and NEO PRI

    ERIC Educational Resources Information Center

    Cauffman, Elizabeth; Kimonis, Eva R.; Dmitrieva, Julia; Monahan, Kathryn C.

    2009-01-01

    The current study compares 3 distinct approaches for measuring juvenile psychopathy and their utility for predicting short- and long-term recidivism among a sample of 1,170 serious male juvenile offenders. The assessment approaches compared a clinical interview method (the Psychopathy Checklist: Youth Version [PCL:YV]; Forth, Kosson, & Hare,…

  6. A Multimethod Assessment of Juvenile Psychopathy: Comparing the Predictive Utility of the PCL:YV, YPI, and NEO PRI

    PubMed Central

    Cauffman, Elizabeth; Kimonis, Eva R.; Dmitrieva, Julia; Monahan, Kathryn C.

    2009-01-01

    The current study compares 3 distinct approaches for measuring juvenile psychopathy and their utility for predicting short- and long-term recidivism among a sample of 1,170 serious male juvenile offenders. The assessment approaches compared a clinical interview method (the Psychopathy Checklist: Youth Version [PCL:YV]; Forth, Kosson, & Hare, 2003), a new self-report measure (the Youth Psychopathic Traits Inventory; Andershed, Kerr, Stattin, & Levander, 2002), and a personality-based approach (the NEO Psychopathy Resemblance Index; Lynam & Widiger, 2007). Results indicate a modest overlap between the 3 measures (rs = .26–.36); however, youths were often identified as psychopathic by 1 measure but not by others. Measures were weakly correlated with reoffending during subsequent 6- and 12-month periods. Findings suggest that although such scores may be useful indicators of the need for heightened monitoring in the short term, care should be taken when making predictions about long-term recidivism among adolescents. Moreover, the lack of long-term predictive power for the PCL:YV and the inconsistent psychopathy designations obtained with different measures raise serious questions about the use of such measures as the basis for legal or clinical treatment decisions. PMID:19947787

  7. Radiogenic lead as coolant, reflector and moderator in advanced fast reactors

    NASA Astrophysics Data System (ADS)

    Kulikov, E. G.

    2017-01-01

    Main purpose of the study is assessing reasonability for recovery, production and application of radiogenic lead as a coolant, neutron moderator and neutron reflector in advanced fast reactors. When performing the study, thermal, physical and neutron-physical properties of natural and radiogenic lead were analyzed. The following results were obtained: 1. Radiogenic lead with high content of isotope 208Pb can be extracted from thorium or mixed thorium-uranium ores because 208Pb is a final product of 232Th natural decay chain. 2. The use of radiogenic lead with high 208Pb content in advanced fast reactors and accelerator-driven systems (ADS) makes it possible to improve significantly their neutron-physical and thermal-hydraulic parameters. 3. The use of radiogenic lead with high 208Pb content in advanced fast reactors as a coolant opens the possibilities for more intense fuel breeding and for application of well-known oxide fuel instead of the promising but not tested enough nitride fuel under the same safety parameters. 4. The use of radiogenic lead with high 208Pb content in ADS as a coolant can upgrade substantially the level of neutron flux in the ADS blanket, which enables effective transmutation of radioactive wastes with low cross-sections of radiative neutron capture.

  8. Identifying sources of Pb pollution in urban soils by means of MC-ICP-MS and TOF-SIMS.

    PubMed

    Rodríguez-Seijo, Andrés; Arenas-Lago, Daniel; Andrade, María Luisa; Vega, Flora A

    2015-05-01

    Lead pollution was evaluated in 17 urban soils from parks and gardens in the city of Vigo (NW Spain). The Pb isotope ratios ((207)Pb/(206)Pb, (208)Pb/(204)Pb, (206)Pb/(204)Pb and (208)Pb/(206)Pb) were determined after being measured by MC-ICP-MS. The association of the isotopes ((204)Pb, (206)Pb, (207)Pb and (208)Pb) with the different components of the soil was studied using TOF-SIMS. The isotopic ranges obtained for the samples were between 1.116 and 1.203 ((206)Pb/(207)Pb), 2.044-2.143 ((208)Pb/(206)Pb), 37.206-38.608 ((208)Pb/(204)Pb), 15.5482-15.6569 ((207)Pb/(204)Pb) and 17.357-18.826 ((206)Pb/(204)Pb). The application of the three-end-member model indicates that the Pb derived from petrol is the main source of Pb in the soils (43.51% on average), followed by natural or geogenic Pb (39.12%) and industrial emissions (17.37%). The emissions derived from coal combustion do not appear to influence the content of Pb in the soil. TOF-SIMS images show that the Pb mainly interacts with organic matter. This technique contributes to the understanding of the association of anthropogenic Pb with the components of the soil, as well as the particle size of these associations, thus allowing the possible sources of Pb to be identified.

  9. Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui Rivers in China.

    PubMed

    Sun, Guo-Xin; Wang, Xin-Jun; Hu, Qin-Hong

    2011-12-01

    Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.198 and 2.075 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively), indicated a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and high (208)Pb/(206)Pb. The corresponding concentrations of heavy metals (As, Cd, Zn, Mn and Pb) were much higher than natural values, suggesting the contaminations of heavy metals from extensive ore-mining activities in the region.

  10. Analysis of orbital occupancy of valence neutron in {sup 15}C through Coulomb breakup reactions

    SciTech Connect

    Singh, P. E-mail: pardeep.phy@dcrustm.org

    2015-03-15

    The Coulomb breakup reactions {sup 208}Pb({sup 15}C, {sup 14}C + n){sup 208}Pb and {sup 181}Ta({sup 15}C, {sup 14}C + n){sup 181}Ta have been studied at 68 and 85 A MeV beam energies, respectively, within the framework of the eikonal approximation to investigate the orbital occupancy of valence neutron in the {sup 15}C nucleus. The outcomes of the present work favor 0{sup +} ⊗ 2s{sub 1/2} as the core-neutron coupling for the ground-state structure with 0.91 as a spectroscopic factor.

  11. Higher-Order Effects in the Elastic Scattering of Electrons and Positrons from LEAD-208 and CARBON-12

    NASA Astrophysics Data System (ADS)

    Linzey, Andrew Joseph

    Here we report on a precise study of the ratio of elastic scattering cross sections of electrons and positrons from ^{12}C and ^{208}Pb, in an effort to observe and quantify deviations from the predictions of a phase shift calculation of the scattering from a static charge density. Any deviations observed can be attributed to higher-order processes sensitive to the sign of the charge of the scattered particle. The beam energies were ~450 MeV and the angular ranges covered were 26-37^circ for ^{12}C and 26-53^ circ for ^{208}Pb. No deviations were observed within the uncertainties of the measurement.

  12. SHE research at RIKEN/GARIS

    NASA Astrophysics Data System (ADS)

    Morita, Kosuke

    2015-12-01

    In this contribution, heavy-element research at RIKEN, Japan is reviewed. Nuclei of the heaviest elements were produced by the reactions 208Pb(64Ni, n)271Ds, 209Bi(64Ni, n)272Rg, 208Pb(70Zn, n)277Cn, and 209Bi(70Zn, n)278113. Alpha decays of those products and their consecutive alpha/spontaneous fission decays were studied using a gas-filled type recoil separator. New nuclei, 278113, 274Rg, and 270Mt, were observed in the 209Bi + 70Zn reaction.

  13. Nondestructive identification of isotopes using nuclear resonance fluorescence

    SciTech Connect

    Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Ohgaki, Hideaki; Toyokawa, Hiroyuki

    2012-01-15

    Nondestructive identification of heavy isotopes concealed in a thick iron box has been demonstrated by using nuclear resonance fluorescence. A quasi-monochromatic photon beam produced by the collision of laser quanta with high energy electrons was used for resonant excitation of nuclear levels in {sup 206}Pb and {sup 208}Pb. By measuring the resonant {gamma} rays emitted from {sup 206}Pb and {sup 208}Pb, each of these isotopes were clearly identified. The ratio of the effective thickness, i.e., concentration distribution, of these isotopes was deduced from the relative intensities of the measured nuclear resonance fluorescence strengths.

  14. Electroweak Measurements of Neutron Densities in PREX and CREX at JLab, USA

    SciTech Connect

    Michaels, Robert W.

    2016-08-01

    Measurement of the parity-violating electron scattering asymmetry from ${}^{208}$Pb has demonstrated a new opportunity at Jefferson Lab to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively. PREX-I ran in 2010, and CREX and a second run of PREX are currently in preparation.

  15. Structure of ²⁰⁷Pb populated in ²⁰⁸Pb + ²⁰⁸Pb deep-inelastic collisions*

    DOE PAGES

    Shand, C. M.; Wilson, E.; Podolyák, Zs.; ...

    2015-01-01

    The yrast structure of 207Pb above the 13/2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ~ 6 MeV, built using coincidence and γ-ray intensity analyses. In addition, the spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations.

  16. Freeze-Out Parameters in Central 158A GeV P{number_sign}208 b+Pb Collision80s

    SciTech Connect

    Aggarwal, M.M.; Bhatia, V.S.; Agnihotri, A.; Bhalla, K.B.; Gupta, S.K.; Raniwala, R.; Raniwala, S.; Ahammed, Z.; Chattopadhyay, S.; Das, A.C.; Dutta Majumdar, M.R.; Ganti, M.S.; Mukhopadhyay, D.S.; Nayak, T.K.; Sinha, B.C.; Trivedi, M.D.; Viyogi, Y.P.; Angelis, A.L.; Donni, P.; Foka, P.; Kalechofsky, H.; Martin, M.; Naef, H.; Rosselet, L.; Rubio, J.M.; Solomey, N.; Voeroes, S.; Antonenko, V.; Cherbatchev, R.; Doubovik, I.; Fokin, S.; Ippolitov, M.; Karadjev, K.; Koutcheryaev, I.; Lebedev, A.; Manko, V.; Mgebrichvili, G.; Nianine, A.; Sibiriak, I.; Tsvetkov, A.; Vinogradov, A.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Baldine, A.; Barabach, L.; Batiounia, B.; Chalyshev, V.; Djordjadze, V.; Frolov, V.; Gavrishchuk, O.; Guskov, B.; Kosarev, I.; Kuzmin, N.; Maximov, A.; Mehdiyev, R.; Mikhalev, D.; Myalkovski, V.; Nikitine, V.; Nikolaev, S.; Nomokonov, P.; Parfenov, A.; Pavliouk, S.; Roufanov, I.; Shabratova, G.; Slavine, N.; Vodopianov, A.; Awes, T.C.; Kim, H.; Plasil, F.; Stankus, P.; Young, G.R.; Baba, P.V.; Badyal, S.K.; Dutt, S.; Mir, M.F.; Rao, N.K.; Sambyal, S.S.; Shah, T.H.; Barlag, C.; Bathe, S.; Blume, C.; Bohne, E.; Boeroecz, Z.K.; Bucher, D.; Buesching, H.; Claussen, A.; Glasow, R.; Kampert, K.; Kees, S.; Kruempel, T.; Peitzmann, T.; Reygers, K.; Santo, R.; Schlagheck, H.; Stueken, D.; Bernier, T.; Delagrange, H.; Gutbrod, H.H.; Luquin, L.; Martinez, G.; Nayak, S.K.; Pinganaud, W.; Retiere, F.; Roy, C.; Schutz, Y. and others

    1999-08-01

    Neutral pion production in central 158A GeV {sup 208}Pb+ {sup 208} Pb collisions has been studied in the WA98 experiment at the CERN Super Proton Synchrotron. The {pi}{sup 0} transverse mass spectrum has been analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement allow one to limit previously noted ambiguities in the extracted freeze-out parameters. The results are shown to be sensitive to the shape of the velocity distribution at freeze-out. {copyright} {ital 1999} {ital The American Physical Society }

  17. A two-dimensional position sensitive charged-particle detector for the magnetic spectrograph ``Big Karl'' of the Jülich Cyclotron ``Jülich''

    NASA Astrophysics Data System (ADS)

    Köhler, M.; Müller, K. D.; Stoff, H.; Teske, M.; Berg, G. P. A.; Hardt, A.; Martin, S.; Mayer-Böricke, C.; Meißburger, J.

    1980-09-01

    A two-dimensional position sensitive detector with an area of 300 mm × 40 mm and a charged-particle spatial resolution of ΔX = ΔY ⩽ 0.5 mm is described. Some test results point out the detector properties. Results of the experiments 102Ru(d,p) 103Ru and 208Pb(p,p') 208Pb done at 45 MeV incident particle energy using the magnetic spectrograph BIG KARL are shown with sections of the proton spectra.

  18. High Resolution Study of the 222Ra Exotic Decay

    NASA Astrophysics Data System (ADS)

    Hussonnois, M.; Le Du, J. F.; Brillard, L.; Dalmasso, J.; Ardisson, G.

    1991-10-01

    The 14C-decay of 222Ra has been reinvestigated using a strong 230U source and the magnetic superconducting spectrometer SOLENO in view of looking for a possible feeding of the first 208Pb excited state. 210 14C-events were recorded in a single peak of (30.930±0.090) MeV energy; the 14C branching ratio values b=(2.31±0.31)×10-10 and <1×10-12 to the respective 208Pb ground and Iπ=3- octupole state were deduced.

  19. Enhanced E1 transitions and {alpha}-clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2011-05-06

    An {alpha}+{sup 208}Pb(0{sup +},3{sup -}) cluster model explains the recently observed enhanced E1 transitions from the new negative-parity levels to the yrast states in {sup 212}Po. Heavy and light nuclei present good examples of surface clustering and well-localized clustering.

  20. The Isoscalar Giant Dipole Resonance in {sup 20}Pb, {sup 90}Zr and the Nuclear Compressibility

    SciTech Connect

    Yildirim, Serbulent; Koeroglu, Ulas

    2008-11-11

    The isoscalar giant dipol resonance (ISGDR) in finite nuclei is studied within the framework of a relativistic transport approach. The excitation energies of spherical {sup 90}Zr and {sup 208}Pb nuclei are obtained for different quantum hydrodynamical Lagrangian parametrization. The sensitivity of ISGDR excitation energy on the nuclear bulk to surface properties are also investigated.

  1. Collisions of Halo Nuclei within a Dynamical Eikonal Approximation

    SciTech Connect

    Baye, D.; Goldstein, G.

    2005-08-19

    The dynamical eikonal approximation unifies the semiclassical time-dependent and eikonal methods. It allows calculating differential cross sections for elastic scattering and breakup in a quantal way by taking into account interference effects. Good agreement is obtained with experiment for {sup 11}Be breakup on {sup 208}Pb. Dynamical effects are weak for elastic scattering.

  2. Identification of the sources of metal (lead) contamination in drinking waters in north-eastern Tasmania using lead isotopic compositions.

    PubMed

    Harvey, P J; Handley, H K; Taylor, M P

    2015-08-01

    This study utilises a range of scientific approaches, including lead isotopic compositions, to differentiate unknown sources of ongoing lead contamination of a drinking water supply in north-eastern Tasmania, Australia. Drinking water lead concentrations are elevated above the Australian Drinking Water Guideline (10 μg/L), reaching 540 μg/L in the supply network. Water lead isotopic compositions from the town of Pioneer ((208)Pb/(207)Pb 2.406, (206)Pb/(207)Pb 1.144 to (208)Pb/(207)Pb 2.360, (206)Pb/(207)Pb 1.094) and Ringarooma ((208)Pb/(207)Pb 2.398, (206)Pb/(207)Pb 1.117) are markedly different from the local bedrock ((208)Pb/(207)Pb 2.496, (206)Pb/(207)Pb 1.237). The data show that the lead in the local waters is sourced from a combination of dilapidated drinking water infrastructure, including lead jointed pipelines, end-of-life polyvinyl chloride pipes and household plumbing. Drinking water is being inadvertently contaminated by aging infrastructure, and it is an issue that warrants investigation to limit the burden of disease from lead exposure.

  3. Density dependence of the symmetry energy from neutron skin thickness in finite nuclei

    SciTech Connect

    Vinas, X.; Centelles, M.; Roca-Maza, X.; Warda, M.

    2012-10-20

    The density dependence of the symmetry energy, characterized by the parameter L, is studied using information provided by the neutron skin thickness in finite nuclei. An estimate of L is obtained from experimental data of antiprotonic atoms. We also discuss the ability of parity violating electron scatering to obtain information about the neutron skin thickness in {sup 208}Pb.

  4. Exclusive breakup measurements for {sup 9}Be

    SciTech Connect

    Fulton, B.R.; Cowin, R.L.; Woolliscroft, R.J.; Clarke, N.M.; Donadille, L.; Freer, M.; Leask, P.J.; Singer, S.M.; Nicoli, M.P.; Benoit, B.; Hanappe, F.; Ninane, A.; Orr, N.A.; Tillier, J.; Stuttge, L.

    2004-10-01

    The first exclusive breakup measurements for the nucleus {sup 9}Be are presented. Breakup via several discrete states is observed following scattering off {sup 12}C and {sup 208}Pb. The results support the prediction of a recent microscopic cluster calculation for a strong n+{sup 8}Be(2{sup +}) state component in the second excited state.

  5. A new analytical approach to understanding nanoscale lead-iron interactions in drinking water distribution systems.

    PubMed

    Trueman, Benjamin F; Gagnon, Graham A

    2016-07-05

    High levels of iron in distributed drinking water often accompany elevated lead release from lead service lines and other plumbing. Lead-iron interactions in drinking water distribution systems are hypothesized to be the result of adsorption and transport of lead by iron oxide particles. This mechanism was explored using point-of-use drinking water samples characterized by size exclusion chromatography with UV and multi-element (ICP-MS) detection. In separations on two different stationary phases, high apparent molecular weight (>669 kDa) elution profiles for (56)Fe and (208)Pb were strongly correlated (average R(2)=0.96, N=73 samples representing 23 single-unit residences). Moreover, (56)Fe and (208)Pb peak areas exhibited an apparent linear dependence (R(2)=0.82), consistent with mobilization of lead via adsorption to colloidal particles rich in iron. A UV254 absorbance peak, coincident with high molecular weight (56)Fe and (208)Pb, implied that natural organic matter was interacting with the hypothesized colloidal species. High molecular weight UV254 peak areas were correlated with both (56)Fe and (208)Pb peak areas (R(2)=0.87 and 0.58, respectively). On average, 45% (std. dev. 10%) of total lead occurred in the size range 0.05-0.45 μm.

  6. Threshold photoneutron cross sections for {sup 208,207,206}Pb isotopes

    SciTech Connect

    Kondo, T.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Iwamoto, C.; Kamata, M.; Itoh, O.; Toyokawa, H.; Lui, Y.-W.

    2010-06-01

    Photoneutron cross sections for three Pb isotopes ({sup 206}Pb, {sup 207}Pb, {sup 208}Pb) near neutron threshold were measured with the laser inverse-Compton scattering gamma rays at the National Institute of Advanced Industrial Science and Technology. The cross section data are presented.

  7. GSI experiments on the synthesis of superheavy elements

    SciTech Connect

    Hessberger, F. P.; Hofmann, S.; Ninov, V.; Armbruster, P.; Folger, H.; Muenzenberg, G.; Stodel, Ch.; Lavrentev, A.; Popeko, A. G.; Yeremin, A. N.; Leino, M. E.; Saro, S.

    1998-02-15

    Evaporation residue production was investigated at SHIP in cold fusion reactions of Pb- and Bi-target nuclei with projectiles of elements between Ti (Z=22) and Se (Z=34) leading to compound nuclei Z{sub CN}=104-116. The isotopes {sup 269}110, {sup 271}110, {sup 272}111, and {sup 277}112 of the elements Z=110, Z=111 and Z=112 were unambiguously identified for the first time in bombardments of {sup 208}Pb, {sup 209}Bi with {sup 62,64}Ni and {sup 70}Zn. Excitation functions for {sup 50}Ti+{sup 208}Pb and {sup 58}Fe+{sup 208}Pb were measured with high precision, three new spontaneous fission (sf) activities {sup 253}104, {sup 254}104, {sup 258}106 were identified. A small {alpha}-decay branch of the even-even nucleus {sup 256}104 (b{sub {alpha}}{approx_equal}0.003) was confirmed, allowing to estimate mass excesses {delta}mc{sup 2} for N-Z=48 nuclei up to {sup 264}Hs (Z=108). An analysis of the {alpha}-decay chains observed in a bombardment of {sup 209}Bi with {sup 58}Fe projectiles showed evidence for an isomeric state in {sup 266}Mt (Z=109). We further report on an attempt to produce element 116 and a second isotope of element 112 by the reactions {sup 82}Se+{sup 208}Pb and {sup 68}Zn+{sup 208}Pb, respectively.

  8. Pressure induced structural phase transition of PrX, PrY (X = S, Se, Te) chalcogenides and (Y = N, P, As) pnictides

    NASA Astrophysics Data System (ADS)

    Varshney, Dinesh; Shriya, Swarna; Dube, A.; Varshney, Meenu

    2012-06-01

    Pressure induced structural aspects of NaCl-type (B1) to CsCl-type (B2) structure in Praseodymium pnictides and chalcogenides are presented. An effective interionic interaction potential with long range Coulomb, van der Waals interaction and the short-range repulsive interaction upto second-neighbor ions within the Hafemeister and Flygare approach with modified ionic charge is developed. Deduced results on volume discontinuity in pressure volume phase diagram identify the structural phase transition from B1 to B2 structure consistent with the known results.

  9. Association of Polymorphisms in three pri-miRNAs that Target Pepsinogen C with the Risk and Prognosis of Gastric Cancer

    PubMed Central

    Wu, Ye-feng; Xu, Qian; He, Cai-yun; Li, Ying; Liu, Jing-wei; Deng, Na; Sun, Li-ping; Yuan, Yuan

    2017-01-01

    We aimed to explore the associations of polymorphisms in three microRNAs (miRNAs) (let-7e rs8111742, miR-365b rs121224 and miR-4795 rs1002765) that target PGC with the risk and prognosis of gastric cancer/atrophic gastritis. Sequenom’s MassArray was used to genotype the miRNA polymorphisms in 724 gastric cancer cases, 862 atrophic gastritis cases and 862 controls in a Chinese population. We found that let-7e rs8111742 and miR-4795 rs1002765 were associated with the risk of gastric cancer in the H. pylori-positive subgroup. MiR-365b rs121224 was associated with the risk of intestinal-type gastric cancer in the alcohol consumption subgroup. Intestinal-type gastric cancer patients at Borrmann stages III-IV who carry the miR-365b rs121224 GG genotype had better prognosis compared with those who carry the CG or CC genotypes. MiR-365b rs121224 was associated with Lauren typing and TNM staging, in which the distribution of GG genotype carriers in intestinal-type gastric cancer and the TNM stage I-II subgroup was higher than that of CG or CC genotypes, which contrasted with the distribution in diffuse-type gastric cancer or TNM III-IV groups. These findings suggested that the polymorphisms in these miRNAs might be biomarkers for gastric cancer risk and prognosis, especially for populations infected with Helicobacter pylori or who consume alcohol. PMID:28067243

  10. Quasi-Elastic Reactions of SILICON-28 and Chlorine -37 with LEAD-208 at Energies in the Range of 1 TO 3 Times the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Dixit, Sunil

    Measurements have been made for the quasi-elastic scattering of ^{28}Si on ^{208}Pb at 280 and 420 MeV, and of ^{37}Cl on ^{208}Pb at 190, 330 and 433 MeV incident projectile energies. The elastic and inelastic scattering data, along with existing data at 152, 162, 166, 210, and 225 MeV, for the ^ {28}Si + ^{208} Pb system, and existing data at 250 MeV for the ^{37}Cl + ^ {208}Pb system have been analyzed using a collective model CCBA formalism. The data are well reproduced within this model at the higher energies. However, the ^{208}Pb(3_1 ^-) state predictions require an additional rotational quadrupole reorientation term at the lower energies which exhibit a striking energy dependence in the extracted effective quadrupole moment, the nuclear deformations, and the ratio (M_{rm N} /M_{rm P}) of the neutron to proton multipole matrix elements. These results suggest the possibility of threshold anomalies in the reorientation channel, highlighting the inadequacy of the collective model in describing the inelastic excitation process for heavy-ion reactions near the Coulomb barrier, at least for this state. The transfer data show large quasi-elastic yields for the one-neutron pickup channel, contributing between 50%-87% and 55%-71% of the total neutron transfer cross section as a function of decreasing projectile energy for the ^{28}Si,^ {37}Cl + ^{208} Pb reactions, respectively. The one nucleon transfer data has been analyzed using the finite range DWBA with optical-model parameters deduced from CCBA analysis and spectroscopic factors obtained from the literature. These transfer processes display a strong dependence on the ground state reaction Q-value, projectile mass, and charge. At the higher energies there is a strong deep-inelastic component (Q <= -30 MeV). This corresponds to angular distributions that are predominantly exponential for charged particle transfer greater than two. Finally, the recently observed "slope anomaly" between the one- and two

  11. Theoretical study of the similarity between nuclei with four valence nucleons in A = 208, 132 and 68 regions

    SciTech Connect

    Benmicia, N.; Benrachi, F.

    2012-06-27

    One of the most interesting topics in nuclear structure is the study of nuclei near the limits of particle stability. Much attention is currently being focused on nuclei with few valence nucleons around Z= 28, 50 and 82, in particular the 68Ni, 132Sn and 208Pb neighbors. We are interested of the even-even isobars 72Ni, 72Ge and 72Zn in 68Ni region, 136Sn, 136Xe and 136Te in 132Sn region, 212Pb, 212Rn and 212Po in 208Pb region. The calculation of energies spectra using the effective interactions JUN45M, CW{Delta}5082 and KHP shows a good agreement with the available experimental data for the energie levels and their sequences. We have extended the existed similarity between lead and tin regions to the Nickel region.

  12. Fission and quasifission modes in heavy-ion-induced reactions leading to the formation of Hs{sup *}

    SciTech Connect

    Itkis, I. M.; Kozulin, E. M.; Itkis, M. G.; Knyazheva, G. N.; Bogachev, A. A.; Chernysheva, E. V.; Krupa, L.; Oganessian, Yu. Ts.; Zagrebaev, V. I.; Rusanov, A. Ya.; Goennenwein, F.; Dorvaux, O.; Stuttge, L.; Hanappe, F.; Vardaci, E.; Goes Brennand, E. de

    2011-06-15

    Mass and energy distributions of binary reaction products obtained in the reactions {sup 22}Ne+{sup 249}Cf,{sup 26}Mg+{sup 248}Cm, {sup 36}S+{sup 238}U, and {sup 58}Fe+{sup 208}Pb have been measured. All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs{sup *}, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed. In the reaction {sup 36}S+{sup 238}U, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the {sup 58}Fe+{sup 208}Pb reaction the quasifission process dominates at all measured energies.

  13. Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

    SciTech Connect

    Bruce, R.; Bocian, D.; Gilardoni, S.; Jowett, J.M.; /CERN

    2009-08-01

    Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of {sup 208}Pb{sup 82+} ion operation in the LHC, with focus on the alice interaction region, and show that the expected heat load during nominal {sup 208}Pb{sup 82+} operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.

  14. a Survey of Giant Resonance Excitations with 200 Mev Protons

    NASA Astrophysics Data System (ADS)

    Tinsley, James Royce

    The giant resonance region in ('60)Ni, ('90)Zr, ('120)Sn, and ('208)Pb has been studied using inelastic scattering of 200 MeV protons. Angular distributions were obtained for the giant quadrupole resonance, giant octupole resonance, and for the combined giant dipole and giant monopole resonance between 4 and 20 degrees. The 2(H/2PI)(omega) component of the giant hexadecapole resonance has been directly observed for the first time in ('208)Pb. In the other nuclei, upper limits on the amount of hexadecapole strength contained within the giant quadrupole resonance have been obtained. Peaks are observed in ('60)Ni and ('90)Zr that are consistent with recently reported M1 states. Discrepancies between sum rules extracted from this data and from previous work are discussed. Possible explanations include DWBA breakdown or difficulties in estimating the magnitude of the continuum. Systematics obtained for the giant resonances are compared to earlier work.

  15. Analytical potential for the elastic scattering of light halo nuclei below and close to the Coulomb barrier

    SciTech Connect

    Borowska, L.; Terenetsky, K.; Verbitsky, V.; Fritzsche, S.

    2009-04-15

    An analytical expression for the dynamic polarization potential is derived for the elastic scattering of light halo nuclei in the Coulomb field of heavy targets. The derivation is based on the adiabatic motion of the projectile below and close to the Coulomb barrier together with a uniform approximation for the Coulomb functions. Detailed computations have been carried out for the elastic scattering of d+{sup 208}Pb and {sup 6}He+{sup 208}Pb at collision energies of 8 and 17.8 MeV and are compared with measurements as far as available. The obtained expression for the dynamic polarization potential is simple and can be applied for any arbitrary system with a dineutron configuration.

  16. Giant M1 resonance in Pb

    SciTech Connect

    Laszewski, R.M.; Rullhusen, P.; Hoblit, S.D.; LeBrun, S.F.

    1985-02-11

    Highly polarized tagged photons were used to measure the distribution of M1 transition strength in /sup 206/Pb at excitations between 6.7 and 8.1 MeV. The observed B(up-arrowM1) of about 19..mu../sub 0//sup 2/ can account for most of the isovector M1 strength that is expected in the Pb nucleus. This result in /sup 206/Pb is compared with the current experimental situation in /sup 208/Pb. The discrepancy between predicted and observed M1 strengths in /sup 208/Pb can probably be attributed to local fragmentation of the strength into states that are too weak to have yet all been identified.

  17. Gamma Strength Functions and Level Densities from 300 MeV Proton Scatttering at 0°

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, Peter; Bassauer, Sergej; Martin, Dirk

    The gamma strength function (GSF) as well as total level densities (LDs) in 208Pb and 96Mo were extracted from high-resolution forward angle inelastic proton scattering data taken at RCNP, Osaka, Japan, and compared to experimental results obtained with the Oslo method in order to test the validity of the Brink-Axel (BA) hypothesis in the energy region of the pygmy dipole resonance. The case of 208Pb is inconclusive because of strong fluctuations of the GSF due to the small level density in a doubly closed-shell nucleus. In 96Mo the data are consistent with the BA hypothesis. The good agreement of LDs provides an independent confirmation of the approach underlying the decomposition of GSF and LDs in Oslo-type experiments.

  18. How the projectile neutron number influences the evaporation cross section in complete fusion reactions with heavy ions

    SciTech Connect

    Wang Chengbin; Zhang Jinjuan; Ren, Z. Z.; Shen, C. W.

    2010-11-15

    The influence of the projectile neutron number on the evaporation residue cross sections for the reactions {sup 208}Pb({sup 52,54}Cr,n,2n){sup 258-261}Sg and {sup 208}Pb({sup 48,50}Ti,n,2n){sup 254-257}Rf has been studied within the framework of a fusion-fission statistical model. The results obtained with the kewpie2 code are compared with recent experimental data. The excitation functions represent the experimental results well both in the maximum value and the lactation of the peak. The calculations show that the projectile neutron number greatly influences both the capture cross section and the fusion probability.

  19. Capture process in nuclear reactions with a quantum master equation

    SciTech Connect

    Sargsyan, V. V.; Kanokov, Z.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.

    2009-09-15

    Projectile-nucleus capture by a target nucleus at bombarding energies in the vicinity of the Coulomb barrier is treated with the reduced-density-matrix formalism. The effects of dissipation and fluctuations on the capture process are taken self-consistently into account within the quantum model suggested. The excitation functions for the capture in the reactions {sup 16}O, {sup 19}F, {sup 26}Mg, {sup 28}Si, {sup 32,34,36,38}S, {sup 40,48}Ca, {sup 50}Ti, {sup 52}Cr+{sup 208}Pb with spherical nuclei are calculated and compared with the experimental data. At bombarding energies about (15-25) MeV above the Coulomb barrier the maximum of capture cross section is revealed for the {sup 58}Ni+{sup 208}Pb reaction.

  20. Energy dissipation in heavy systems: the transition from quasi-elastic to deep-inelastic scattering

    SciTech Connect

    Rehm, K.E.; van den Berg, A.; Kolata, J.J.; Kovar, D.G.; Kutschera, W.; Rosner, G.; Stephans, G.S.F.; Yntema, J.L.; Lee, L.L.

    1984-01-01

    The interaction of medium mass projectiles (A = 28 - 64) with /sup 208/Pb has been studied using a split-pole spectrograph which allows single mass and charge identification. The reaction process in all systems studied so far is dominated by quasi-elastic neutron transfer reactions, especially at incident energies in the vicinity of the Coulomb barrier. In addition to the quasi-elastic component deep inelastic contributions are present in all reaction channels. The good mass and charge separation allows to generate Wilczynski plots for individual channels; for the system /sup 48/Ti + /sup 208/Pb we observe that the transition between the quasi-elastic and deep-inelastic reactions occurs around Q = -(30 to 35) MeV.

  1. Probing the neutron skin thickness in collective modes of excitation

    NASA Astrophysics Data System (ADS)

    Paar, N.; Horvat, A.

    2014-03-01

    Nuclear collective motion provides valuable constraint on the size of neutron-skin thickness and the properties of nuclear matter symmetry energy. By employing relativistic nuclear energy density functional (RNEDF) and covariance analysis related to χ2 fitting of the model parameters, relevant observables are identified for dipole excitations, which strongly correlate with the neutron-skin thickness (rnp), symmetry energy at saturation density (J) and slope of the symmetry energy (L). Using the RNEDF framework and experimental data on pygmy dipole strength (68Ni, 132Sn, 208Pb) and dipole polarizability (208Pb), it is shown how the values of J, and L, and rnp are constrained. The isotopic dependence of moments associated to dipole excitations in 116-136Sn shows that the low-energy dipole strength and polarizability in neutron-rich nuclei display strong sensitivity to the symmetry energy parameter J, more pronounced than in isotopes with moderate neutron-to-proton number ratios.

  2. Search for a fine structure in the 14C decay of 222Ra

    NASA Astrophysics Data System (ADS)

    Hussonnois, M.; Le Du, J. F.; Brillard, L.; Dalmasso, J.; Ardisson, G.

    1991-06-01

    The 14C decay of 222Ra has been reinvestigated, using an 85 MBq activity 230U source radiochemically separated, a Si barrier detector, and a superconducting magnetic spectrometer. In a 16 days counting run, 210 14C events were recorded. The 14C particles energy value 30.930+/-0.090 MeV was found and an upper limit b<=2×10-12 was estimated for the 14C branching ratio to the 208Pb first excited state; the branching-ratio value to the 208Pb ground state, thus equal to the total branching ratio, was found to be b=λc/λα=(2.31+/-0.31)×10-10.

  3. Fusion-fission and quasifission in the reactions with heavy ions leading to the formation of Hs

    SciTech Connect

    Itkis, I. M.; Itkis, M. G.; Knyazheva, G. N.; Kozulin, E. M.

    2012-10-20

    Mass and energy distributions of binary reaction products obtained in the reactions {sup 22}Ne+{sup 249}Cf,{sup 26}Mg+{sup 248}Cm,{sup 36}S+{sup 238}U and {sup 58}Fe+{sup 208}Pb leading to Hs isotopes have been measured. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed. In the reaction {sup 36}S+{sup 238}U the considerable part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier the symmetric fragments originate mainly from fusion-fission process for both reactions with Mg and S ions. In the case of the {sup 58}Fe+{sup 208}Pb reaction the quasifission process dominates at all measured energies. The pre- and post-scission neutron multiplicities as a function of the fragment mass have been obtained for the reactions studied.

  4. Density dependence of the nuclear symmetry energy from measurements of neutron radii in nuclei

    SciTech Connect

    Viñas, X.; Centelles, M.; Roca-Maza, X.; Warda, M.

    2014-07-23

    We study the density dependence of the nuclear symmetry energy, characterized by its slope parameter L, by means of the information provided by the neutron radius and the neutron skin thickness in finite nuclei. These quantities are extracted from the analysis of data obtained in antiprotonic atoms, from the parity-violating asymmetry at low-momentum transfer in polarized electron scattering in {sup 208}Pb, and from the electric dipole polarizability obtained via polarized proton inelastic scattering at forward angles in {sup 208}Pb. All these experiments provide different constraints on the slope L of the symmetry energy but the corresponding values have a considerable overlap in a range around 50 MeV ≤ L ≤ 70 MeV, in a reasonable agreement with other estimates that use different observables and methods to extract L.

  5. Asymptotic and near-target direct breakup of 6Li and 7Li

    NASA Astrophysics Data System (ADS)

    Kalkal, Sunil; Simpson, E. C.; Luong, D. H.; Cook, K. J.; Dasgupta, M.; Hinde, D. J.; Carter, I. P.; Jeung, D. Y.; Mohanto, G.; Palshetkar, C. S.; Prasad, E.; Rafferty, D. C.; Simenel, C.; Vo-Phuoc, K.; Williams, E.; Gasques, L. R.; Gomes, P. R. S.; Linares, R.

    2016-04-01

    Background: Li,76 and 9Be are weakly bound against breakup into their cluster constituents. Breakup location is important for determining the role of breakup in above-barrier complete fusion suppression. Recent works have pointed out that experimental observables can be used to separate near-target and asymptotic breakup. Purpose: Our purpose is to distinguish near-target and asymptotic direct breakup of Li,76 in reactions with nuclei in different mass regions. Method: Charged particle coincidence measurements are carried out with pulsed Li,76 beams on 58Ni and 64Zn targets at sub-barrier energies and compared with previous measurements using 208Pb and 209Bi targets. A detector array providing a large angular coverage is used, along with time-of-flight information to give definitive particle identification of the direct breakup fragments. Results: In interactions of 6Li with 58Ni and 64Zn, direct breakup occurs only asymptotically far away from the target. However, in interactions with 208Pb and 209Bi, near-target breakup occurs in addition to asymptotic breakup. Direct breakup of 7Li into α -t is not observed in interactions with 58Ni and 64Zn. However, near-target dominated direct breakup was observed in measurements with 208Pb and 209Bi. A modified version of the Monte Carlo classical trajectory model code platypus, which explicitly takes into account lifetimes associated with unbound states, is used to simulate sub-barrier breakup reactions. Conclusions: Near-target breakup in interactions with Li,76 is an important mechanism only for the heavy targets 208Pb and 209Bi. There is insignificant near-target direct breakup of 6Li and no direct breakup of 7Li in reactions with 58Ni and 64Zn. Therefore, direct breakup is unlikely to suppress the above-barrier fusion cross section in reactions of Li,76 with 58Ni and 64Zn nuclei.

  6. Isotopic signatures for natural versus anthropogenic Pb in high-altitude Mt. Everest ice cores during the past 800 years.

    PubMed

    Lee, Khanghyun; Hur, Soon Do; Hou, Shugui; Burn-Nunes, Laurie J; Hong, Sungmin; Barbante, Carlo; Boutron, Claude F; Rosman, Kevin J R

    2011-12-15

    A long-term record, extending back 800 years (1205 to 2002 AD), of the Pb isotopic composition ((206)Pb/(207)Pb and (208)Pb/(207)Pb) as well as Pb concentrations from high altitude Mt. Everest ice cores has the potential to identify sources and source regions affecting natural and anthropogenic Pb deposition in central Asia. The results show that the regional natural background Pb isotope signature (~1.20 for (206)Pb/(207)Pb and ~2.50 for (208)Pb/(207)Pb) in the central Himalayas was dominated by mineral dust over the last ~750 years from 1205 to 1960s, mostly originating from local sources with occasional contributions of long-range transported dust probably from Sahara desert and northwestern India. Since the 1970s, the Pb isotope ratios are characterized by a continuous decline toward less radiogenic ratios with the least mean ratios of 1.178 for (206)Pb/(207)Pb and 2.471 for (208)Pb/(207)Pb in the period 1990-1996. The depression of the (206)Pb/(207)Pb and (208)Pb/(207)Pb values during the corresponding periods is most likely due to an increasing influence of less radiogenic Pb of anthropogenic origin mainly from leaded gasoline used in South Asia (India as well as possibly Bangladesh and Nepal). From 1997 to 2002, isotopic composition tends to show a shift to slightly more radiogenic signature. This is likely attributed to reducing Pb emissions from leaded gasoline in source regions, coinciding with the nationwide reduction of Pb in gasoline and subsequent phase-out of leaded gasoline in South Asia since 1997. An interesting feature is the relatively high levels of Pb concentrations and enrichment factors (EF) between 1997 and 2002. Although the reason for this feature remains uncertain, it would be probably linked with an increasing influence of anthropogenic Pb emitted from other sources such as fossil fuel combustion and non-ferrous metal production.

  7. Can one observe the spin monopole resonance in 208?

    SciTech Connect

    P.M. Boucher; B. Castel

    1989-12-01

    We investigate the feasibility of identifying the spin monopole isovector resonance from the quadrupole contribution occurring at the same energy. In that context, we present the result of a continuum random-phase-approximation calculation which clearly indicates that because of very different momentum transfer patterns for L=0 and L=2 resonances, the spin monopole should be easily identifiable in reactions like 208Pb(n,p) at forward angles or low momentum transfer.

  8. Detecting supernova neutrinos with iron and lead detectors

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Abhijit; Bhattacharjee, Pijushpani; Chakraborty, Sovan; Kar, Kamales; Saha, Satyajit

    2017-03-01

    Supernova (SN) neutrinos can excite the nuclei of various detector materials beyond their neutron emission thresholds through charged current (CC) and neutral current (NC) interactions. The emitted neutrons, if detected, can be a signal for the supernova event. Here we present the results of our study of SN neutrino detection through the neutron channel in 208Pb and 56Fe detectors for realistic neutrino fluxes and energies given by the recent Basel/Darmstadt simulations for an 18 solar mass progenitor SN at a distance of 10 kpc. We find that, in general, the number of neutrons emitted per kiloton (kTon) of detector material for the neutrino luminosities and average energies of the different neutrino species as given by the Basel/Darmstadt simulations are significantly lower than those estimated in previous studies based on the results of earlier SN simulations. At the same time, we highlight the fact that, although the total number of neutrons produced per kTon in a 56Fe detector is more than an order of magnitude lower than that for 208Pb, the dominance of the flavor blind NC events in the case of 56Fe, as opposed to the dominance of νe induced CC events in the case of 208Pb, offers a complementarity between the two detector materials so that simultaneous detection of SN neutrinos in a 208Pb and a sufficiently large 56Fe 56 detector suitably instrumented for neutron detection may allow estimating the fraction of the total μ and τ flavored neutrinos in the SN neutrino flux and thereby probing the emission mechanism as well as flavor oscillation scenarios of the SN neutrinos.

  9. Exotic Orbital Modes in Nuclei

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, P.

    2003-06-01

    Experimental evidence for two types of collective excitations in nuclei generated by orbital motion is discussed, viz. a magnetic quadrupole twist mode observed in 180° electron scattering experiments and a toroidal electric dipole mode. The latter may be a source of low-energy pygmy dipole resonances observed in many nuclei. This is discussed in detail for the example of 208Pb based on the recent finding of a resonance at particle threshold in a high-resolution (γ, γ') experiment.

  10. Realistic simulations of the AGATA Demonstrator+PRISMA Spectrometer

    SciTech Connect

    Ince, E.; Erduran, M. N.; Farnea, E.; Latina, A.

    2008-11-11

    The performance of the AGATA Demonstrator Array coupled to the PRISMA magnetic spectrometer have been evaluated in a consistent way using detailed Monte Carlo simulations of the two devices. Results for the {sup 90}Zr+{sup 208}Pb at 560 MeV reaction are presented and discussed here, proving that the Doppler correction capabilities of the AGATA+PRISMA setup will be very close to the intrinsic energy resolution of the germanium detectors.

  11. Separation of contributions of isovector E2 and E1 giant resonances in direct and inverse reactions with real and virtual photons

    NASA Astrophysics Data System (ADS)

    Dzhilavyan, L. Z.; Lapik, A. M.; Nedorezov, V. G.; Tulupov, B. A.

    2017-01-01

    A brief overview of the methods for separating the contributions of isovector electric quadrupole ( E2) and dominant dipole ( E1) giant resonances in atomic nuclei, which are excited in direct and inverse reactions with photons (real and virtual), is given. The basic parameters of isovector giant resonance E2, which were declared to date by applying some of these methods to the results with 208Pb, are also presented.

  12. Discrimination of the Cigarettes Geographical Origin by DRC-ICP-MS Measurements of Pb Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Guo, W.; Hu, S.; Jin, L.

    2014-12-01

    Trace Pb are taken up with the same isotopic ratios as is present in the source soil, and the isotopic composition of Pb could used to reflect these sources and provide powerful indicators of the geographic origin of agriculture products derived from vegetative matter. We developed a simple and high throughput method, which based on DRC-ICP-MS for determination of Pb isotope ratios for discriminating the geographic origin of cigarettes. After acid digestion procedure, the cigarette digested solutions were directly analyzed by ICP-QMS with a DRC pressurized by the non-reactive gas Ne. In the DRC, Ne molecules collision with Pb ions and improves Pb isotope ratios precision 3-fold, which may be due to the collisional dampling smoothes out the ion beam fluctuations. Under the optimum DRC rejection parameter Q (RPq = 0.45), the main matrix components (K, Na, Ca, Mg, Al, Fe etc.) originating from cigarettes were filtered out. Mass discrimination of 208Pb/206Pb ratio in Ne DRC mode increased 0.3% compared to the standard mode, the mass bias due to the in-cell Ne gas collision can be accurately corrected by NIST 981 Pb isotope standard. This method was verified by a tobacco reference material CTV-OTL-2. Results of 208Pb/206Pb and 207Pb/206Pb were 2.0848 ± 0.0028 (2δ) and 0.8452 ± 0.0011 (2δ) for CTA-VTL-2, which were agreed with the literature values (208Pb/206Pb = 2.0884 ± 0.0090 and 207Pb/206Pb = 0.8442 ± 0.0032). The precision of Pb isotope ratios (208Pb/206Pb and 207Pb/206Pb) for the cigarette samples are ranged from 0.01 to 0.08% (N = 5). It has sufficient precision to discriminate 91 different brand cigarettes originated from four different geographic regions (Shown in Fig).

  13. Nuclear Targets for a Precision Measurement of the Neutral Pion Radiative Width

    SciTech Connect

    Martel, Philippe; Clinton, Eric; McWilliams, R.; Lawrence, Dave; Miskimen, Rory; Ahmidouch, Abdellah; Ambrozewicz, Pawel; Asaturyan, Arshak; Baker, O.; Benton, LaRay; Bernstein, Aron; Cole, Philip; Collins, Patrick; Dale, Daniel; Danagoulian, Samuel; Davidenko, G.; Demirchyan, Raphael; Deur, Alexandre; DOLGOLENKO, A.; Dzyubenko, Georgiy; Evdokimov, Anatoly; Feng, JIng; Gabrielyan, Marianna; Gan, Liping; Gasparian, Ashot; Glamazdin, Oleksandr; Goryachev, Vladimir; Gyurjyan, Vardan; Hardy, K.; Ito, Mark; Khandaker, Mahbubul; Kingsberry, Paul; Kolarkar, Ameya; Konchatnyi, Mykhailo; Korchin, O.; Korsch, Wolfgang; Kowalski, Stanley; Kubantsev, Mikhail; Kubarovsky, Valery; LARIN, Ilya; MATVEEV, V.; McNulty, Dustin; Milbrath, Brian; Minehart, Ralph; Mochalov, Vasiliy; Mtingwa, Sekazi; Nakagawa, Itaru; Overby, Steven; Pasyuk, Evgueni; Payen, Marvin; Pedroni, Ronald; Prok, Yelena; Ritchie, Barry; Salgado, Carlos; Sitnikov, Anatoly; Sober, Daniel; Stephens, W.; Teymurazyan, Aram; Underwood, Jarreas; VASILIEV, A.; VEREBRYUSOV, V.; Vishnyakov, Vladimir; Wood, Michael

    2009-12-01

    A technique is presented for precision measurements of the area densities, density * T, of approximately 5% radiation length carbon and 208Pb targets used in an experiment at Jefferson Laboratory to measure the neutral pion radiative width. The precision obtained in the area density for the carbon target is +/- 0.050%, and that obtained for the lead target through an x-ray attenuation technique is +/- 0.43%.

  14. Production and Beta Half Lives of Nuclei Close TI the Nucleosynthesis R-Process Path at N=126

    SciTech Connect

    Benlliure, J.; Caamano, M.; Casarejos, E.; Cortina, D.; Kurtukian, T.; Ordonez, M. F.; Pereira, J.; Becker, F.; Henzlova, D.; Jurado, B.; Schmidt, K. H.; Yordanov, O.; Audouin, L.; Rejmund, F.

    2007-05-22

    Cold-fragmentation reactions of 208Pb projectiles impinging a beryllium target at 1 A GeV have been used to produce more than 190 nuclei ''south'' of lead, 25 of them for the first time. The beta half lives or upper limits of 13 of these new nuclei have been determined using position and time correlations between the nuclei and the betas in an active stopper. The measured half lives can only be described when first forbidden transitions are considered.

  15. Two-Dimensional Isotope Imaging of Radiation Shielded Materials Using Nuclear Resonance Fluorescence

    NASA Astrophysics Data System (ADS)

    Toyokawa, Hiroyuki; Ohgaki, Hideaki; Hayakawa, Takehito; Kii, Toshiteru; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Masuda, Kai; Kitatani, Fumito; Harada, Hideo

    2011-10-01

    A novel method for two-dimensional (2D) imaging of a specific isotope in a material, which is hidden by a thick radiation shield is presented. Nuclear resonance fluorescence and the laser Compton scattering are used in the present method. We measured γ-rays of 5512 keV from the nuclear resonance fluorescence of 208Pb at several points, and obtained a 2D image of isotope distribution.

  16. Properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei

    SciTech Connect

    Gorelik, M. L. Shlomo, Sh. Tulupov, B. A. Urin, M. H.

    2015-07-15

    The recently developed particle-hole dispersive optical model is applied to describe properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. In particular, the double transition density averaged over the energy of the isoscalar monopole excitations is considered for {sup 208}Pb in a wide energy interval, which includes the isoscalar giant monopole resonance and its overtone. The energy-averaged strength functions of these resonances are also analyzed.

  17. Study of the charge radii of the stable lead isotopes

    SciTech Connect

    Borchert, G.L.; Schult, O.W.B.; Speth, J.; Hansen, P.G.; Jonson, B.; Ravn, H.; McGrory, J.B.

    1982-01-01

    Isotope shifts have been measured of the K/sub ..cap alpha..l/ x-ray lines emitted after photo ionization of /sup 204/Pb, /sup 206/Pb, /sup 207/Pb and /sup 208/Pb samples. The results are compared with theoretical values for delta < r/sup 2/> calculated with a microscopic model. The x-ray shift data are also compared with optical data and the nuclear parameters lambda derived from electron scattering results.

  18. Synthesis and evaluation of geometric analogs of 1α,25-dihydroxyvitamin D2 as potential therapeutics.

    PubMed

    Bolla, Narasimha Rao; Corcoran, Aoife; Yasuda, Kaori; Chodyński, Michał; Krajewski, Krzysztof; Cmoch, Piotr; Marcinkowska, Ewa; Brown, Geoffrey; Sakaki, Toshiyuki; Kutner, Andrzej

    2016-11-01

    An improved convergent strategy was developed for the synthesis of the previously obtained side-chain extended and rigidified analogs of 1α,25-dihydroxyvitamin D2, PRI-1906 and PRI-1907. New (24Z) geometric isomers of the analogs, PRI-1916 and PRI-1917, were also obtained and identified. These side-chain isomers were separable by flash chromatography, as C-25 alcohols, from the synthetic precursors of PRI-1906 and PRI-1907, respectively. The structures of new analogs were determined by advanced techniques of (1)H and (13)C NMR, including COSY, HSQC and HMBC sequences. Binding affinities of the geometric analogs PRI-1906 and PRI-1916 and their respective C-26, C-27 homologs PRI-1907 and PRI-1917 for the full-length human vitamin D receptor were determined by a fluorescence polarization competition assay. The binding affinity of (24Z) methyl analog PRI-1906 was much higher than that of (24E) analog PRI-1906, while the affinity of (24Z) ethyl analog PRI-1917 was lower than that of the respective PRI-1907. Investigation of the metabolism of these compounds by human CYP24A1 revealed they are much more resistant to CYP24A1 than 1α,25-dihydroxyvitamin D2, indicating they could have longer-term biological effects on target tissues.

  19. Crystal ball studies of giant resonance gamma decay

    NASA Astrophysics Data System (ADS)

    Beene, J. R.; Bertrand, F. E.; Halbert, M. L.

    1985-01-01

    We have carried out coincidence experiments to investigate the photon and neutron emission from the giant resonance region in 208Pb and 90Zr using the ORNL Spin Spectrometer, a 72-segment NaI detector system. States in 208Pb and 90Zr were excited by inelastic scattering of 380-MeV 17O. We have determined the total gamma-decay probability, the ground-state gamma branching ratio, and the branching ratios to a number of low-lying stats as a function of excitation energy in 208Pb to ˜15 MeV. Especially interesting observations include the absence of a significant branch from the giant quadrupole resonance to the 3- state at 2.6 MeV, a strong branch from this resonance to a 3- state at 4.9 MeV, and the dominance of decays to various 1- states at 5-7 MeV from the region around 14 MeV of excitation (E0 resonances). Comparable but less complete data were also obtained on 90Zr.

  20. First Charge-Exchange Measurements with SHARAQ

    SciTech Connect

    Miki, K.; Sakai, H.

    2011-10-28

    The isovector spin monopole resonances (IVSMR) of the {beta}{sup +} type were observed for the first time in the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions were obtained at the excitation energy of 0{<=}E{sub x}{<=}70 MeV and the scattering angles of 0 deg. {<=}{theta}{<=}3 deg. The monopole component was identified by making a difference between the zero-degree and backward-angle spectra. The signatures of the IVSMR are observed at an excitation energy of 12 MeV(20 MeV) in {sup 208}Pb({sup 90}Zr)(t,{sup 3}He) reaction, which agrees fairly well with the theoretical predictions.

  1. Prenatal metal exposure in the Middle East: imprint of war in deciduous teeth of children.

    PubMed

    Savabieasfahani, M; Ali, S Sadik; Bacho, R; Savabi, O; Alsabbak, M

    2016-09-01

    In war zones, the explosion of bombs, bullets, and other ammunition releases multiple neurotoxicants into the environment. The Middle East is currently the site of heavy environmental disruption by massive bombardments. A very large number of US military bases, which release highly toxic environmental contaminants, have also been erected since 2003. Current knowledge supports the hypothesis that war-created pollution is a major cause of rising birth defects and cancers in Iraq. We created elemental bio-imaging of trace elements in deciduous teeth of children with birth defects from Iraq. Healthy and naturally shed teeth from Lebanon and Iran were also analyzed for trace elements. Lead (Pb) was highest in teeth from children with birth defects who donated their teeth from Basra, Iraq (mean 0.73-16.74 (208)Pb/(43)Ca ppm, n = 3). Pb in healthy Lebanese and Iranian teeth were 0.038-0.382 (208)Pb/(43)Ca ppm (n = 4) and 0.041-0.31 (208)Pb/(43)Ca ppm (n = 2), respectively. Our hypothesis that increased war activity coincides with increased metal levels in deciduous teeth is confirmed by this research. Lead levels were similar in Lebanese and Iranian deciduous teeth. Deciduous teeth from Iraqi children with birth defects had remarkably higher levels of Pb. Two Iraqi teeth had four times more Pb, and one tooth had as much as 50 times more Pb than samples from Lebanon and Iran.

  2. The temperature dependence of the width of the giant dipole resonance

    SciTech Connect

    Ormand, W.E. |; Bortignon, P.F. |; Broglia, R.A. ||

    1995-12-31

    A systematic study of the full-width-at-half-maximum (FWHM) of the giant-dipole resonance (GDR) as a function of temperature for the nuclei {sup 120}Sn and {sup 208}Pb confirms the overall theoretical picture of the GDR in hot nuclei; in particular, the role played by large-amplitude thermal fluctuations of the nuclear shape. This is confirmed by the good agreement between theory and experiment achieved over a range of temperatures from 1.25--32 MeV and by the differences in the behavior of the FWHM for {sup 120}Sn and {sup 208}Pb, which can be attributed to the presence of strong shell corrections favoring spherical shapes in {sup 208}Pb that are absent in {sup 120}Sn. Finally, the increase in the FWHM over that expected from thermal averaging at temperatures of the order 3.0 MeV is in accordance with the increase expected from the particle evaporation of the compound system.

  3. Monazite Th-Pb age depth profiling

    SciTech Connect

    Grove, M.; Harrison, T.M.

    1999-06-01

    The significant capabilities of the ion microprobe for thermochronometric investigations of geologic materials remain largely unexploited. Whereas {sup 208}Pb/{sup 232}Th spot analysis allows {approximately} 10-mm-scale imaging of Pb loss profiles or overgrowths in sectioned monazite grains, the spatial resolution offered by depth profiling into the surface region of natural crystals is more than two orders of magnitude higher. The authors document here the ability of the high-resolution ion microprobe to detect {sup 208}Pb/{sup 232}Th age differences of < 1 m.y. with better than 0.05 {micro}m depth resolution in the outer micron of Tertiary monazites from the hanging wall of the Himalayan Main Central thrust. Age gradients on this scale are inaccessible to ion microprobe spot analysis or conventional thermal ionization mass spectrometry. Interpretation of the near-surface {sup 208}Pb distributions with available monazite Pb diffusion data illustrates the potential of the approach for recovering continuous, high-temperature thermal history information not previously available.

  4. Characteristics of lead geochemistry and the mobility of Pb isotopes in the system of pedogenic rock-pedosphere-irrigated riverwater-cereal-atmosphere from the Yangtze River delta region, China.

    PubMed

    Wang, Cheng; Wang, Jianhua; Yang, Zhongfang; Mao, Changping; Ji, Junfeng

    2013-11-01

    Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock-pedosphere-irrigated riverwater-cereal-atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of (208)Pb/(206)Pb=-1.157×(206)Pb/(207)Pb+3.46 (r(2)=0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb ((208)Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7-52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb.

  5. Estimating total fusion cross sections by using a coupled-channel method

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seok; Cheoun, Myung-Ki; Kim, K. S.; Kim, T. H.; So, W. Y.

    2017-01-01

    We calculate the total fusion cross sections for the 6He + 209Bi, 6Li + 209Bi,9Be + 208Pb, 10Be + 209Bi, and 11Li + 208Pb systems by using a coupled-channel (CC) method and compare the results with the experimental data. In the CC approach for the total fusion cross sections, we exploit a globally determined Wood-Saxon potential with Akyüz-Winther parameters and couplings of the ground state to the low-lying excited states in the projectile and the target nuclei. The total fusion cross sections obtained with the CC are compared with those obtained without the CC couplings. The latter approach is tantamount to a one-dimensional barrier penetration model. Finally, our approach is applied to understand new data for the 11Li+208Pb system. Possible ambiguities inherent in those approaches are discussed in detail for further applications to the fusion system of halo and/or neutron-rich nuclei.

  6. Nuclear-reaction studies via the observation of unbound outgoing systems

    SciTech Connect

    Bice, A.N.

    1982-01-01

    The mechanisms involved in the production of fast ..cap alpha..-particles in /sup 12/C induced reactions have been investigated for the /sup 12/C + /sup 208/Pb system at bombarding energies of E(/sup 12/C) = 132, 187 and 230 MeV. Absolute cross sections have been determined for the reactions /sup 208/Pb (/sup 12/C, /sup 8/Be (g.s.)), /sup 208/Pb(/sup 12/C, /sup 8/Be (2.94 MeV)) and /sup 208/Pb (/sup 12/C, /sup 12/C* ..-->.. ..cap alpha.. + /sup 8/Be) by double and triple coincidence measurements of the sequential decay ..cap alpha..-particles. Inclusive ..cap alpha..-particle production cross sections were also measured at E (/sup 12/C) = 187 MeV for comparison. It is found that the simple inelastic scattering process (/sup 12/C, /sup 12/C* ..-->.. ..cap alpha.. + /sup 8/Be) does not contribute significantly to the production of fast ..cap alpha..-particles but that the production of /sup 8/Be nuclei by projectile fragmentation is an important source of ..cap alpha..-particles. At the highest bombarding energy investigated (19 MeV/A) it appears that the /sup 12/C ..-->.. 3..cap alpha.. fragmentation reaction becomes more prominent at the expense of the /sup 12/C ..-->.. ..cap alpha.. + /sup 8/Be fragmentation channel. It is concluded that projectile spectroscopic properties and/or final state interactions are important in fragmentation reactions for these bombarding energies. In a kinematically complete experiment the direct and the sequential breakup channels of 10 MeV/A /sup 7/Li projectiles have been investigated with /sup 12/C and /sup 208/Pb targets. By appropriate arrangement of detector telescopes it was possible to define a kinematical window which allowed for the unambigious observation of both the direct (to the ..cap alpha..-t continuum) and the sequential components of a heavy-ion projectile breakup reaction. A semiclassical Monte Carlo type projectile breakup calculation was constructed which qualitatively reproduced the measured ..cap alpha

  7. Large Pb Isotopic Variations in Pre-shield Stage Kilauea Magmas

    NASA Astrophysics Data System (ADS)

    Shimizu, N.; Sisson, T. W.; Layne, G. D.

    2001-12-01

    Volcaniclastic sediments found from a scarp below the mid-slope bench at water depths between 3,000 and 5,000m offshore south of Kilauea, Hawaii, contain abundant glass shards that represent submarine eruptions from an ancestral Kilauea volcano (Lipman et al., 2000; Sisson et al., 2001). Their major element compositions range from tholeiites/transitional basalts to alkali basalts to basanites and nephelinites. Pb isotopic compositions of the glasses were determined using a Cameca IMS 1270 ion microprobe at Woods Hole Oceanographic Institution. Replicate analyses of basalt glass stnadards show that 208Pb/206Pb and 207Pb/206Pb ratios could be determined in basalt glasses with external precisions better than 0.15% (1σ ) in a spot of 30 μ m across. Results show that: (1) a range of Pb isotopic compositions observed in the glasses are much greater than the entire spectrum of the Hawaiian volcanics. 208Pb/206Pb ratios vary from 2.099 to 2.004 and 207Pb/206Pb from 0.864 to 0.805. (2) There appear to be three distinct compositions, with each being represented by diverse magmatic compositions. There appears to be no significant mixing between them, and they form a linear array in a 208/206 vs 207/206 space, encompassing the entire Hawaiian Pb isotopic composition array. The least radiogenic composition (208Pb/206Pb=2.099, 207Pb/206Pb=0.864) in on an extension of the Honolulu Volcanics array, whereas the most radiogenic composition (208Pb/206Pb=2.004, 207Pb/206Pb=0.805) is far more radiogenic than any known Hawaiian magmas. The intermediate composition (208Pb/206Pb=2.041, 207Pb/206Pb=0.827) is close to the "Kea" endmember composition proposed by Eiler et al. (1998). The ancestral Kilauea nephelinites are derived from two distinct sources with radiogenic compositions and are quite distinct from all other Hawaiian post-erosional nephelinites. It is evident that diverse sources were tapped during the pre-shield stage Kilauea magmatism, and that melts erupted without mixing

  8. Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth.

    PubMed

    Shepherd, Thomas J; Dirks, Wendy; Roberts, Nick M W; Patel, Jaiminkumar G; Hodgson, Susan; Pless-Mulloli, Tanja; Walton, Pamela; Parrish, Randall R

    2016-04-01

    We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that

  9. Electromagnetic Properties of Materials and Metamaterials

    DTIC Science & Technology

    2010-09-20

    39 3.2.2 Pri sm Coup ler...18 Figure 21 :NRI and Tefl on wedge-pri sms fabricated by Boeing for the DARPA...plasmon di spersion for a metal-air interface(dm) and, in the limit where the goes to zero, a metal-pri sm interface(pm) ........ ... ........ 40 Figure

  10. Synthesis of the heaviest nuclei in cold fusion reactions

    NASA Astrophysics Data System (ADS)

    Münzenberg, G.; Morita, K.

    2015-12-01

    Cold fusion of heavy ions paved the way to superheavy elements. It was proposed by Yu.Ts. Oganessian more than forty years ago in 1974 [1,2]. First experiments were carried out at JINR Dubna, starting with the reaction 40Ar + 208Pb → 248Fm* where several hundreds to thousand atoms were produced on one day. The large production rate indicating an enhancement of the fusion cross section, especially for the evaporation of two or three neutrons, proved the concept of cold-fusion with the use of the doubly magic nucleus 208Pb as a target. The Dubna experiments were extended to the transactinide region beyond rutherfordium. The breakthrough came with the separation in-flight. Two different approaches were used: kinematic separation with the velocity filter SHIP [3] at GSI Darmstadt, and with the gasfilled separator GARIS [4,5] at RIKEN. With SHIP the concept of cold fusion of massive nuclear systems was convincingly confirmed by the observation of the one-neutron evaporation channel in the production of 247Rf in an irradiation of 208Pb with 50Ti [6] in 1981 which opened the way to the transactinide region. At SHIP the elements bohrium (107) to copernicium (112) were discovered [7]. A new closed shell region around hassium was found. The RIKEN experiments started in 2002. They confirmed the GSI results and in addition improved the data on structure and production of elements hassium to copernicium significantly. The heaviest element ever created in a cold fusion reaction, Z = 113, was observed at GARIS [8,9].

  11. Optimization of an acidic digestion method for the determination of total Pb concentration and its isotope ratios in human blood using ICP-QMS.

    PubMed

    Pérez-Rodríguez, Rebeca Y; Castro-Larragoitia, Javier; Alfaro-De La Torre, María C; Díaz-Barriga, Fernando

    2017-03-21

    Adverse effects of lead (Pb) on human health are observed even at levels below 5 μg/dL, affecting principally the children population and suggesting that there is not a safe exposure level. The determination of Pb isotopic ratios (LIRs) in biological and environmental samples, is an appropriate tool to track and control the exposure sources, because LIRs constitutes the pollutant's isotopic signature and hence can be used to identify sources of Pb emission. This study proposes the optimization of a method in order to significantly reduce the biological samples' matrix interferences, and improves precision and accuracy in the measurements of LIRs. Four total blood digestion methods were evaluated and the results were subjected to statistical methods (ANOVA) determining the combination of HNO3:H2O2 (2:1 v v(-1))/g from a sample on a hot plate as the best of them. For the method's validation, detection and quantification limits, linearity range, intermediate precision and recovery were evaluated. The total Pb (PbT) and LIRs were performed by ICP-QMS, defining the optimal value of detector dead time (DT), and correcting mass bias and instrumental drift for this matrix. LIRs based on (206)Pb, (207)Pb and (208)Pb were determined at high precision (%RSD 0.03-0.49%), than those involving (204)Pb (%RSD > 0.8). The optimized methodology can be used to identify pollution sources in blood and environmental samples using LIRs ((206)Pb/(207)Pb, (207)Pb/(208)Pb, (208)Pb/(206)Pb, etc.) in a trustworthy and simple way, with accurate results.

  12. U-Th-Pb ion microprobe analysis of monazite from the Paleoproterozoic Karrat rare earth element (REE) deposit, western Greenland

    NASA Astrophysics Data System (ADS)

    Mott, A.; Grove, M.; Bird, D. K.

    2012-12-01

    The Karrat rare earth element (REE) deposit is located at 72°N on the Niaqornakavsak peninsula of Qeqertarssuq Island on the western coast of Greenland. Metasomatic alteration of an amphibolite host rock by carbonatite derived fluids resulted in REE mineralization in the Karrat Isfjord area. REE in the mineralization are primarily found in bastnasite, allanite, and monazite. In-situ analysis of monazite was conducted on samples obtained from three sites of mineralization: (1) the primary deposit at Niaqornakavsak consisting of a single distinct ~30m thick unit; (2) at Umiamako Nuna 7 km to the east of Niaqornakavsak where the majority of REE mineralization occurs within the first 20m of the surface; and (3) a 6m thick REE-rich vein 100m below the surface at Umiamako Nuna. Formation ages for monazite at Niaqornakavsak, Umiamako Nuna (surface), and Umiamako Nuna (vein) have been calculated using 207Pb/206Pb, 206Pb/238U, and 208Pb/232Th isotope ratios. Multiple isotope ratios were examined to determine the ideal method of monazite analysis based on the inherent issues of low U content of monazite, difficulties measuring 204Pb, common Pb corrections, and peak interferences resulting from high concentrations of REE. 208Pb/232Th analysis resulted in the best precision and smallest spread of values. Energy filtering was applied to 208Pb/232Th analyses in an effort to reduce interferences at several peaks. Although all three isotope ratio analyses result in a Paleoproterozoic age similar to the timing of convergence of the North Atlantic craton, Rae craton, and Aasiat domain as well as the emplacement of the Prøven Igneous Complex in Greenland (1.95-1.80Ga), the values range between 1.7-1.9Ga depending on the isotope ratio.

  13. Investigation of off-site airborne transport of lead from a superfund removal action site using lead isotope ratios and concentrations

    USGS Publications Warehouse

    Pribil, Michael J.; Maddaloni, Mark A.; Staiger, Kimberly; Wilson, Eric; Magriples, Nick; Ali, Mustafa; Santella, Dennis

    2014-01-01

    Lead (Pb) concentration and Pb isotopic composition of surface and subsurface soil samples were used to investigate the potential for off-site air transport of Pb from a former white Pb processing facility to neighboring residential homes in a six block area on Staten Island, NY. Surface and subsurface soil samples collected on the Jewett White Pb site were found to range from 1.122 to 1.138 for 206Pb/207Pb and 2.393 to 2.411 for 208Pb/207Pb. The off-site surface soil samples collected from residential backyards, train trestle, near site grass patches and background areas varied from 1.144 to 1.196 for 206Pb/207Pb and 2.427 to 2.464 for 208Pb/207Pb. Two soil samples collected along Richmond Terrace, where Jewett site soils accumulated after major rain events, varied from 1.136 to 1.147 for 206Pb/207Pb and 2.407 to 2.419 for 208Pb/207Pb. Lead concentration for on-site surface soil samples ranged from 450 to 8000 ug/g, on-site subsurface soil samples ranged from 90,000 to 240,000 ug/g and off-site samples varied from 380 to 3500 ug/g. Lead concentration and isotopic composition for the Staten Island off-site samples were similar to previously published data for other northeastern US cities and reflect re-suspension and re-mobilization of local accumulated Pb. The considerable differences in both the Pb isotopic composition and Pb concentration of on-site and off-site samples resulted in the ability to geochemically trace the transport of particulate Pb. Data in this study indicate minimal off-site surface transport of Pb from the Jewett site into the neighboring residential area.

  14. Modeling metal bioaccumulation in the invasive mussels Dreissena polymorpha and Dreissena rostriformis bugensis in the rivers Rhine and Meuse.

    PubMed

    Le, T T Yen; Leuven, Rob S E W; Hendriks, A Jan

    2011-12-01

    The metal-specific covalent index and the species-specific size-based filtration rate were integrated into a biokinetic model estimating metal bioaccumulation in mussels from the dissolved phase and phytoplankton. The model was validated for zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis bugensis) mussels in the rivers Rhine and Meuse, the Netherlands. The model performed well in predicting tissue concentrations in different-sized zebra mussels from various sampling sites for (55) Mn, (56) Fe, (59) Co, (60) Ni, (82) Se, (111) Cd, (118) Sn, and (208) Pb (r(2) =0.71-0.99). Performance for (52) Cr, (63) Cu, (66) Zn, (68) Zn, and (112) Cd was moderate (r(2) <0.20). In quagga mussels, approximately 73 to 94% of the variability in concentrations of (82) Se, (111) Cd, (112) Cd, and (208) Pb was explained by the model (r(2) =0.73-0.94), followed by (52) Cr, (55) Mn, (56) Fe, (60) Ni, and (63) Cu (r(2) =0.48-0.61). Additionally, in both zebra and quagga mussels, average modeled concentrations were within approximately one order of magnitude of the measured values. In particular, in zebra mussels, estimations of (60) Ni and (82) Se concentrations were equal to 51 and 76% of the measurements, respectively. Higher deviations were observed for (52) Cr, (59) Co, (55) Mn, (56) Fe, (111) Cd, (63) Cu, and (112) Cd (underestimation), and (66) Zn, (68) Zn, (208) Pb, and (118) Sn (overestimation). For quagga mussels, modeled concentrations of (66) Zn and (68) Zn differed approximately 14% from the measured levels. Differences between predictions and measurements were higher for other metals.

  15. An odyssey of environmental pollution: the rise, fall and remobilization of industrial lead in Australia

    NASA Astrophysics Data System (ADS)

    Taylor, M. P.; Kristensen, L.; Liqin, W.; Harvey, P. J.; Dong, C.; Rouillon, M.

    2015-12-01

    The use of lead in automobile gasoline resulted in more than 240,000 tonnes of lead being emitted to the Australian environment over its 70-year period of use starting in 1932. The consequences of the emissions and subsequent depositions have resulted in marked contamination of urban and peri-urban aerosols, soils, plants and humans. This paper charts these effects and examines the extent of recovery from one of the most pervasive and persistent environmental pollutants. Lead isotopic composition of Adelaide and Sydney aerosol filters show that air lead composition shifts from values that approximate Broken Hill type ores, the predominant lead source used in gasoline (1.04 206Pb/207Pb and 2.31 208Pb/207Pb), towards ratios that more closely match local uncontaminated soil and bedrock values (Adelaide ~1.19 206Pb/207Pb and ~2.50 208Pb/207Pb; Sydney ~1.15 206Pb/207Pb and 2.48 208Pb/207Pb). Proxy atmospheric measurements from historic wine, lichen and fungi samples extending over 120 years show how both concentration and composition values shifted in the middle to late 20th century to reflect petrol emissions and then recovered rapidly at the end of the century as leaded gasoline consumption declined. For example, lead in wine from South Australia fell from >100 μg/L in the 1960s and 1970s to < 5 μg/L in the 2010s due to the removal of the primary source of atmospheric lead - gasoline. However, measurement of contemporary surface soils, ash produced from wildfires and air filters demonstrate that the effect of depositions persists and industrial lead and other toxic metals (including arsenic, cadmium and nickel) are subject to frequent remobilization. Predicted increases in wildfires and the generation of lead, arsenic and cadmium toxic particulates warrants greater consideration of the risk for vulnerable populations and firefighters who are most exposed.

  16. Interpretation of U-Th-Pb in-situ ages of hydrothermal monazite-(Ce) and xenotime-(Y): evidence from a large-scale regional study in clefts from the western alps

    NASA Astrophysics Data System (ADS)

    Grand'Homme, A.; Janots, E.; Bosse, V.; Seydoux-Guillaume, A. M.; De Ascenção Guedes, R.

    2016-12-01

    In eleven Alpine clefts of the western Alps, in-situ dating of monazite-(Ce) and xenotime-(Y) has been attempted to gain insights on possible disturbances of the geochronological U-Th-Pb systems and age interpretations in hydrothermal conditions. In most clefts, monazite-(Ce) in-situ 208Pb/232Th dating using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) yields well-resolved ages (with errors typically <0.3 Ma, quoted at the 2σ level), indicative of a short duration monazite-(Ce) growth. However, monazite-(Ce) dating demonstrates two successive episodes of growth separated by several million years within two single clefts. Only in one cleft, complex age mixture in a porous and complex zoned monazite-(Ce) suggests disturbance of the 208Pb/232Th ages due to replacement by dissolution-precipitation processes. While some U-Pb ages are coherent with the 208Pb/232Th ages, U-Pb ages are generally disturbed by significant 206Pb excess in monazite-(Ce) with high Th/U ratio (>100). Xenotime-(Y) has remarkably high Th/U ratios and U-Pb dating is also disturbed by 206Pb excess, whereas 208Pb/232Th dating gave well-resolved ages (34.9 ± 0.5 Ma), close to but higher than the monazite-(Ce) age obtained in the same cleft (32.3 ± 0.3 Ma). Correlation of the monazite-(Ce) U-Th-Pb age dataset with other geochronological data suggests for monazite-(Ce) precipitation at periods of high tectonic activity. In the external massifs, monazite-(Ce) dating confirms a polyphased transpressive regime with activity periods around 13-11 Ma and 8-6 Ma. Older monazite-(Ce) ages in the Argentera massif (20.6 ± 0.3 Ma) are consistent with the regional diachronism in the western external Alps. In the 2 clefts of the internal massifs, monazite-(Ce) dating provides first ages of hydrothermal activity: the monazite-(Ce) age at 32.3 ± 0.3 Ma coincides with the exhumation along the Penninic front, but the monazite-(Ce) age at 23.3 ± 0.2 Ma is complex to attribute to a

  17. Investigation of the energy-averaged double transition density of isoscalar monopole excitations in medium-heavy mass spherical nuclei

    NASA Astrophysics Data System (ADS)

    Gorelik, M. L.; Shlomo, S.; Tulupov, B. A.; Urin, M. H.

    2016-11-01

    The particle-hole dispersive optical model, developed recently, is applied to study properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. The energy-averaged strength functions of the isoscalar giant monopole resonance and its overtone in 208Pb are analyzed. In particular, we analyze the energy-averaged isoscalar monopole double transition density, the key quantity in the description of the hadron-nucleus inelastic scattering, and studied the validity of the factorization approximation using semi classical and microscopic one body transition densities, respectively, in calculating the cross sections for the excitation of isoscalar giant resonances by inelastic alpha scattering.

  18. Evidence for the onset of reflection asymmetry in sup 216 Fr

    SciTech Connect

    Debray, M.E.; Davidson, J.; Davidson, M.; Kreiner, A.J.; Hojman, D.; Santos, D. ); Ahn, K.; Fossan, D.B.; Liang, Y.; Ma, R.; Paul, E.S.; Piel, W.F. Jr.; Xu, N. )

    1990-05-01

    States in doubly odd {sup 216}Fr have been studied using in-beam {alpha}, {gamma}, and {ital e}{sup {minus}} spectroscopy techniques through the {sup 208}Pb({sup 11}B3{ital n}) fusion-evaporation reaction. {sup 216}Fr shows a band structure with interleaved states of alternating parities connected by enhanced {ital B}({ital E}1) transitions. It represents the lowest-mass corner of the region ({ital Z}{ge}87,{ital N}{ge}129) in which this phenomenon is observed.

  19. Analysis of nucleon-induced fission cross sections of lead and bismuth at energies from 45 to 500 MeV

    SciTech Connect

    Prokofyev, A.V.; Mashnik, S.G.; Sierk, A.J.

    1998-08-01

    In order to investigate the applicability of the Cascade-Exciton model (CEM) of nuclear reactions to fission cross sections and hoping to learn more about intermediate-energy fission, the authors use an extended version of the CEM, as realized in the code CEM95 to perform a detailed analysis of proton- and neutron-induced fission cross sections of {sup 209}Bi and {sup 208}Pb nuclei and of the linear momentum transfer to the fissioning nuclei in the 45--500 meV energy range.

  20. Coupled-cluster theory computation of the nuclear electric dipole polarizability

    NASA Astrophysics Data System (ADS)

    Bacca, Sonia; Miorelli, Mirko; Barnea, Nir; Hagen, Gaute; Orlandini, Giuseppina; Papenbrock, Thomas

    2016-03-01

    The electric dipole polarizability αD is strongly correlated with the size of atomic nuclei. It informs us about the neutron equation of state and links atomic nuclei to neutron stars. In recent years, scattering experiments have been used to determine the dipole polarizability in 208Pb, 120Sn and 68Ni. Combining the Lorentz integral transform with the coupled-cluster method allows us to perform ab initio computations of αD for medium mass nuclei. In Ref. we predicted the polarizability for 48Ca and presently we are investigating heavier systems such as 68Ni and 90Zn.

  1. Isomer ratio measurements as a probe of the dynamics of breakup and incomplete fusion

    SciTech Connect

    Gasques, L. R.; Dasgupta, M.; Hinde, D. J.; Peatey, T.; Diaz-Torres, A.; Newton, J. O.

    2006-12-15

    The incomplete fusion mechanism following breakup of {sup 6,7}Li and {sup 9}Be projectiles incident on targets of {sup 209}Bi and {sup 208}Pb is investigated through isomer ratio measurements for the {sup 212}At and {sup 211}Po products. The phenomenological analysis presented in this paper indicates that incomplete fusion brings relatively more angular momentum into the system than equivalent reactions with a direct beam of the fused fragment. This is attributed to the trajectories of breakup fragments. Calculations with a 3D classical trajectory model support this. Isomer ratio measurements for incomplete fusion reactions can provide a test of new theoretical models of breakup and fusion.

  2. Remark on: the neutron spherical optical-model absorption.

    SciTech Connect

    Smith, A. B.; Nuclear Engineering Division

    2007-06-30

    The energy-dependent behavior of the absorption term of the spherical neutron optical potential for doubly magic {sup 208}Pb and the neighboring {sup 209}Bi is examined. These considerations suggest a phenomenological model that results in an intuitively attractive energy dependence of the imaginary potential that provides a good description of the observed neutron cross sections and that is qualitatively consistent with theoretical concepts. At the same time it provides an alternative to some of the arbitrary assumptions involved in many conventional optical-model interpretations reported in the literature and reduces the number of the parameters of the model.

  3. Core excitation effects in halo nuclei using a transformed oscillator basis

    SciTech Connect

    Lay, J. A.; Arias, J. M.; Moro, A. M.; Gomez-Camacho, J.

    2013-06-10

    A recent generalization of the Transformed Harmonic Oscillator basis, intended to consider core excitations in the structure of one nucleon halo nuclei, is applied to the break up of {sup 11}Be. The reaction studied is {sup 11}Be+{sup 208}Pb at 69 MeV/nucleon. The experimental set up is designed to ensure pure dipole Coulomb excitations. Making use of the Equivalent Photon Method and the electromagnetic transition probabilities obtained with the transformed oscillator basis, a relevant contribution of the quadrupole excitations of the core is found. The inclusion of core excitations is, therefore, necessary for the correct extraction of the dipole electromagnetic transition probability of halo nuclei.

  4. Isoscalar [ital M]1 strength in lead

    SciTech Connect

    Alarcon, R.; Choi, S. ); Laszewski, R.M.; Dale, D.S. )

    1993-09-01

    Highly polarized tagged photons were used to measure the distribution of [ital M]1 transition strength in [sup 206]Pb at excitations between 5.5 and 6.9 MeV. The total [ital M]1 strength found in this energy range is consistent with that reported in [sup 208]Pb. For the isoscalar state at 5.8 MeV in [sup 206]Pb, [ital B]([ital M]1[up arrow])=(0.72[plus minus]0.15)[mu][sub [ital N

  5. Nuclear structure studies in the seaborgium region at SHIP

    SciTech Connect

    Antalic, S. Andel, B.; Heßberger, F. P.; Khuyagbaatar, J.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kindler, B.; Laatiaoui, M.; Lommel, B.; Kalaninová, Z.; Piot, J.; Vostinar, M.

    2015-10-15

    New decay data for the isotopes {sup 259}Sg and {sup 255}Rf were obtained at the velocity filter SHIP using an α-decay spectroscopy measurement. Both isotopes were produced and studied via a one neutron evaporation channel in the compound fusion reaction {sup 54}Cr+{sup 208}Pb. New isomeric states were observed and the single-particle level systematics for isotones with 151 and 153 neutrons were extended. A change of the ground-state configuration for the heaviest N = 151 isotones was observed. Detailed Monte-Carlo simulation for the α decay of {sup 259}Sg applying the GEANT4 toolkit was performed and compared with experimental data.

  6. Nuclear structure studies in the seaborgium region at SHIP

    NASA Astrophysics Data System (ADS)

    Antalic, S.; Heßberger, F. P.; Andel, B.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kalaninová, Z.; Kindler, B.; Khuyagbaatar, J.; Laatiaoui, M.; Lommel, B.; Piot, J.; Vostinar, M.

    2015-10-01

    New decay data for the isotopes 259Sg and 255Rf were obtained at the velocity filter SHIP using an α-decay spectroscopy measurement. Both isotopes were produced and studied via a one neutron evaporation channel in the compound fusion reaction 54Cr+208Pb. New isomeric states were observed and the single-particle level systematics for isotones with 151 and 153 neutrons were extended. A change of the ground-state configuration for the heaviest N = 151 isotones was observed. Detailed Monte-Carlo simulation for the α decay of 259Sg applying the Geant4 toolkit was performed and compared with experimental data.

  7. Neutron Scattering Cross Section and Analyzing Power Measurements for LEAD-208 from 6 TO 10 Mev and Optical Model Analyses.

    NASA Astrophysics Data System (ADS)

    Roberts, Mark L.

    Differential cross sections and analyzing powers have been obtained for the scattering of neutrons from the ground and first excited states of ^ {208}Pb. These new measurements include differential cross sections for elastic and inelastic neutron scattering at 8.0 MeV, and analyzing powers for elastic and inelastic neutron scattering at 6.0, 7.0, 8.0, 9.0, and 10.0 MeV. These data complement earlier work performed at Triangle Universities Nuclear Laboratory (TUNL) for elastic scattering of neutrons from ^{208 }Pb at 10.0, 14.0, and 17.0 MeV. All data were obtained using the TUNL pulsed beam facility and time -of-flight spectrometer. The data have been corrected for the effects of finite geometry, flux attenuation, and multiple scattering. The present elastic scattering data have been combined with the previously measured TUNL data and data measured elsewhere in order to obtain a detailed and high accuracy data set for neutron elastic scattering from ^{208}Pb over the 4.0 to 40.0 MeV energy range. This comprehensive data set has been described using the spherical optical model in which constant geometry fits, energy-dependent geometry fits, and fits incorporating the dispersion relation were performed. Although the overall description of the elastic n+^ {208}Pb scattering data was reasonably good using the various optical potentials, small systematic discrepancies remained at the backward angles of both the cross section and analyzing power data, and no optical model solution based on conventional Woods-Saxon form factors was found which could describe all of the details seen in the scattering data. To relax the constraint of having a Woods-Saxon form factor, the real central part of the optical model potential was modified using a Fourier-Bessel expansion of the real central potential. Individual fits at 6.0, 7.0, 8.0, 9.0, and 10.0 MeV, and fits to the combined 6.0 to 10.0 MeV data set were obtained using a Fourier -Bessel expansion of the real central potential

  8. Volatilized lead from Apollo 12 and 14 soils.

    NASA Technical Reports Server (NTRS)

    Doe, B. R.; Tatsumoto, M.

    1972-01-01

    Lead in some Apollo-12 and -14 soils and breccias was volatilized under vacuum at temperature intervals of 0 to 600 C, 600 to 800 C, 800 to 1000 C, and 1000 to 1350 C. It is found that the Pb(206)/Pb(204) ratio increases and the Pb(207)/Pb(206) ratio decreases in the temperature range between 600 and 1000 C. The Pb(208)/Pb(206) ratios decrease from a value of 2 at 600 C to a value of 0.7 at 1350 C. These and other data suggest a secondary isochron age of about 4200 million years.

  9. Search for the giant pairing vibration through (p,t) reactions around 50 and 60 MeV

    SciTech Connect

    Mouginot, B.; Khan, E.; Azaiez, F.; Franchoo, S.; Ramus, A.; Scarpaci, J. A.; Stefan, I.; Neveling, R.; Buthelezi, E. Z.; Foertsch, S. V.; Smit, F. D.; Fujita, H.; Usman, I.; Mabiala, J.; Mira, J. P.; Swartz, J. A.; Papka, P.

    2011-03-15

    The existence of the giant pairing vibration (GPV) in {sup 120}Sn and {sup 208}Pb was investigated using the (p,t) reaction at incident proton energies of 50 MeV and 60 MeV for the scattering angles 0 deg. and 7 deg. No clear signature for the GPV was found, providing an upper limit for the cross section of {sigma}{sub max} = 0.2 mb. Theoretical interpretations for the low cross section of the GPV are discussed.

  10. Shell model approach for nuclei with mass around 220

    NASA Astrophysics Data System (ADS)

    Kaiura, Yukiko; Yoshinaga, Naotaka; Higashiyama, Koji

    2014-09-01

    Ra and Th isotopes with mass around 220 belonging to a transitional region between spherical and deformed regions have fascinated our interest from the past. In particular, since a large number of negative parity states are observed in low-lying states, collective octupole correlations are supposed to be important. In this talk we report the nuclear structure of Po, Rn, Ra and Th isotopes in terms of the pair truncated shell model, the basic ingredients of which consist of nuclear collective models. The 208Pb is considered as the doubly-magic core. The conventional pairing plus quadrupole interaction is employed. Energy levels and electric transitions are compared between theory and experiment.

  11. Spin-Isospin Resonances: A Self-Consistent Covariant Description

    SciTech Connect

    Liang Haozhao; Nguyen Van Giai; Meng Jie

    2008-09-19

    For the first time a fully self-consistent charge-exchange relativistic RPA based on the relativistic Hartree-Fock (RHF) approach is established. The self-consistency is verified by the so-called isobaric analog state (IAS) check. The excitation properties and the nonenergy weighted sum rules of two important charge-exchange excitation modes, the Gamow-Teller resonance (GTR) and the spin-dipole resonance (SDR), are well reproduced in the doubly magic nuclei {sup 48}Ca, {sup 90}Zr and {sup 208}Pb without readjustment of the particle-hole residual interaction. The dominant contribution of the exchange diagrams is demonstrated.

  12. On the determination of the pion effective mass in nuclei from pionic atoms

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Gal, A.

    1998-07-01

    The binding energies of the deeply bound 1s and 2p states in pionic atoms of 207Pb, recently established experimentally in the 208Pb(d,3He) reaction, have been used by several groups to derive the pion effective mass in nuclear matter. We show that these binding energies are fully consistent with `normal' pionic atoms and that the real part of the pion-nucleus potential at the center of 207Pb is 28+/-3 MeV and not 20 MeV as suggested previously.

  13. New Insight into the Pygmy Dipole Resonance in Stable Nuclei

    SciTech Connect

    Neumann-Cosel, P. von

    2008-11-11

    Two examples of recent work on the structure of low-energy electric dipole modes are presented. The first part discusses the systematics of the pygmy dipole resonance (PDR) in stable tin isotopes deduced from high-resolution ({gamma},{gamma}') experiments. These help to distinguish between microscopic QRPA calculations based on either a relativistic or a nonrelativistic mean-field description, predicting significantly different properties of the PDR. The second part presents attempts to unravel the structure of dipoles modes at energies below the giant dipole resonance (GDR) in {sup 208}Pb with a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg.

  14. Decay spectroscopy of neutron-rich rare-earth isotopes and collectivity around double midshell

    SciTech Connect

    Watanabe, Hiroshi

    2015-10-15

    Neutron-rich rare-earth isotopes with A ≈ 170, which locate near the middle of the major shells for both proton and neutron between the doubly magic nuclei {sup 132}Sn and {sup 208}Pb, have been investigated by means of decay spectroscopy techniques at the RIBF facility at RIKEN. The nuclei of interest were produced by in-flight fission of a high-intensity {sup 238}U beam at 345 MeV/u. In this contribution, scientific motivations, the details of experimental procedures, and some prospects of the data analysis are reported.

  15. Mean-Field and RPA Approaches to Stable and Unstable Nuclei with Semi-Realistic NN Interaction

    SciTech Connect

    Nakada, H.

    2011-05-06

    A M3Y-type semi-realistic NN interaction has been applied to the mean-field and the RPA calculations. Explicitly including the tensor force and the central part of the one-pion exchange potential, the semi-realistic interaction is useful in studying the Z or N dependence of the nuclear shell structure. The magicity of N = 32, 40 and 58 in the neutron-rich Ca and Ni nuclei has been investigated, and the Z = 28 magicity in {sup 78}Ni has been argued. Significance of the tensor force in magnetic transitions is demonstrated by the M1 excitation of {sup 208}Pb.

  16. Comparison of Complementary Reactions in the Production of Mt

    SciTech Connect

    Nelson, Sarah; Gregorich, Kenneth; Dragojevic, Irena; Ellison, Paul; Garcia, Mitch Andre; Gates, Jacklyn; Stavsetra, Liv; Ali, Mazhar; Nitsche, Heino

    2009-01-21

    The new reaction 208Pb(59Co,n)266Mt was studied using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. A cross section of 7.7+5.2-3.3 pb was measured at a compound nucleus excitation energy of 14.9 MeV. The measured decay properties of 266Mt and its daughters correspond well with existing data. We compare this experimental result to transactinide compound nucleus formation model predictions, and the previously studied 209Bi(58Fe,n)266Mt reaction.

  17. Investigation of the Photoneutron Cross Section in LEAD-206 and LEAD-208 from 9 TO 16 Mev

    NASA Astrophysics Data System (ADS)

    Morford, Larry Joe

    The time of flight of photoneutrons from ('206)Pb and ('208)Pb was observed at scattering angles of 55(DEGREES), 90(DEGREES), and 125(DEGREES). Photons with energies between 9 and 16 MeV were used to excite the target nuclei. The incident photon beam was provided by the University of Illinois Tagged Photon Facility and had an effective energy resolution of around 400 keV. Neutron energies were determined by time of flight through a 1.5 meter path. The effective energy resolution of the neutrons was between 7.6% at 1 MeV and 12.5% at 5 MeV. Neutron detector efficiency was determined by measuring the photo-disintegration of deuterium. The resulting efficiency was found to be constant across the neutron energy range of interest. The fraction of neutrons with energy insufficient to pass the detector threshold was estimated to be 10.7%. The total cross section for both ('206)Pb and ('208)Pb are well described by Lorentzian curves with widths of 4.12 (+OR-) 0.24 MeV for ('206)Pb and 4.09 (+OR-) 0.38 MeV for ('208)Pb. The peak positions of the curves were determined to be 13.70 (+OR-) 0.06 MeV for ('206)Pb and 13.53 (+OR-) 0.05 MeV in ('208)Pb. No angular asymmetry about 90(DEGREES) in the differential cross sections was detected in either element above 11 MeV. Below 11 MeV the asymmetry varied with energy between alternate positive and negative values for each element. The time-of-flight spectra could be parameterized for low energy neutrons by a statistical decay with a nuclear temperature of 0.9 MeV. There was an excess of high energy neutrons above this distribution. A more detailed analysis of the spectra using the Hauser-Feshbach formalism suggests that this excess is also from the statistical decay of the nucleus.

  18. Study of heavy ion range in different solid state nuclear track detector materials

    NASA Astrophysics Data System (ADS)

    Diwan, P. K.; Singh, Lakhwant; Singh, Gurinder; Kumar, Shyam

    2000-03-01

    The range of several heavy ions as 238U, 208Pb, 197Au, 139La, 58Ni and 56Fe in sodalime glass; 197Au and 58Ni in muscovite mica and Lexan polycarbonate; 209Bi and 197Au in CR-39 have been determined experimentally. The calculations of range for these projectile-target combinations have been made using the Benton and Henke [10], Mukherjee and Nayak [11], Ziegler et al. [12] and Hubert et al. [14] semiempirical formulations. Finally a comparison has been made with the experimental results.

  19. 7Be- and 8B-reaction dynamics at Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Keeley, N.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lay, J. A.; Lin, C. J.; Marquinez-Duran, G.; Martel, I.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Pakou, A.; Rusek, K.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Stefanini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Teranishi, T.; Toniolo, N.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.

    2016-05-01

    We investigated the reaction dynamics induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being 7Be (Sα = 1.586 MeV) the loosely bound core of the even more exotic 8B (Sp = 0.1375 MeV) nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.

  20. Reaction dynamics induced by the radioactive ion beam 7Be on medium-mass and heavy targets

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Stefanini, C.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Keeley, N.; Lay, J. A.; Marquinez-Duran, G.; Martel, I.; Mazzocchi, C.; Molini, P.; Nicoletto, M.; Pakou, A.; Parkar, V. V.; Rusek, K.; Sánchez-Benítez, A. M.; Sandoli, M.; Sava, T.; Sgouros, O.; Signorini, C.; Silvestri, R.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Toniolo, N.; Zerva, K.

    2015-10-01

    We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam 7Be (Sα = 1.586 MeV) on medium-mass (58Ni) and heavy (208Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×105 pps 7Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.

  1. E2 transitions between excited single-phonon states: Role of ground-state correlations

    NASA Astrophysics Data System (ADS)

    Kamerdzhiev, S. P.; Voitenkov, D. A.

    2016-11-01

    The probabilities for E2 transitions between low-lying excited 3- and 5- single-phonon states in the 208Pb and 132Sn magic nuclei are estimated on the basis of the theory of finite Fermi systems. The approach used involves a new type of ground-state correlations, that which originates from integration of three (rather than two, as in the random-phase approximation) single-particle Green's functions. These correlations are shown to make a significant contribution to the probabilities for the aforementioned transitions.

  2. γ-ray spectroscopy of 209Tl

    DOE PAGES

    Amro, B. M. S.; Lister, C. J.; McCutchan, E. A.; ...

    2017-01-30

    Here, states in 209TI were populated using a multi-nucleon transfer reaction with a 136Xe beam impinging on a thick 208Pb target at E = 785 MeV. The beam was pulsed at 825 ns intervals in order to perform isomer decay spectroscopy. The known Jπ = 17/2+ isomer in 209TI was located at 1228(4) keV and measured to have a half-life of T1/2 = 146(10) ns. A second isomer with Jπ = 13/2+ were found to have T1/2 = 14(5) ns.

  3. Basalt Petrogenesis Beneath Slow - and Ultraslow-Spreading Arctic Mid-Ocean Ridges

    DTIC Science & Technology

    2009-02-01

    0.70274-0.70301), εHf (16.59-19.56), and Pb isotopes (e.g. 208Pb/206Pb = 2.043-2.095). This suggests a homogeneous mantle source and a long peridotite ...number of upper mantle rocks can contain Gt, the stability of Gt in peridotite depends on pressure. Thus if the host of Gt is peridotite , the dominant... peridotite , I have measured U and Th partition coefficients in silica-poor garnet pyroxenite, a minor mantle lithology for which such measurements

  4. Recent Results in Parity-Violating Electron Scattering at Jefferson Lab: PREX and HAPPEX-III

    NASA Astrophysics Data System (ADS)

    Jen, Chun-Min; PREx Collaboration

    2011-10-01

    The parity-violating asymmetry APV in electron scattering from the 208Pb nucleus is cleanly sensitive to the neutron radius Rn. A precision measurement of Rn would have important implications for the understanding of nuclear structure, and be a powerful constraint on the symmetry energy Sν(n) of neutron-rich nuclear matter, including neutron stars. The PREX collaboration has completed a first run, measuring Rn to a precision of ~2.5% and providing the first electroweak evidence for the neutron skin of a heavy nucleus. Results from this measurement, and prospects for more precise future measurements, will be discussed.

  5. Population and decay of a Kπ=8– two-quasineutron isomer in Pu244

    DOE PAGES

    Hota, S. S.; Tandel, S. K.; Chowdhury, P.; ...

    2016-08-22

    Here, the decay of a Kπ = 8– isomer in 244Pu and the collective band structures populating the isomer were studied using deep inelastic excitations with 47Ti and 208Pb beams, respectively. Precise measurements of M1/E2 branching ratios in the band confirm a 9/2–[734]νⓍ7/2+[624]ν configuration assignment for the isomer, validating the systematics of Kπ = 8–, two-quasineutron isomers observed in even-Z, N = 150 isotones. These isomers around the deformed shell gap at N = 152 provide critical benchmarks for theoretical predictions of single-particle energies in this gateway region to superheavy nuclei.

  6. A Primer on the Detection of Nuclear and Radiological Weapons

    DTIC Science & Technology

    2005-05-01

    signals or samples molecules from nuclear materials and turns them into information. This is indicated schematically in figure 12. The front end ...short-lived isotopes ending in stable 208Pb. The most prominent gamma rays are 239 keV from 212Pb, 511, 583 and 2614 keV from 208Tl, and 911 and...isotopes ending in 206Pb. The most prominent gamma rays are 609, 1120, and 1764 keV from 214Bi. • Potassium activity is due to decay of 40K, which

  7. Fractional processes and nuclear disassembly in very-heavy-ion collisions in the Fermi energy regime

    SciTech Connect

    Schroeder, W.U.

    1991-01-01

    Exclusive measurements of charged products and neutrons were performed for the reactions {sup 197}Au + (29 MeV/u) {sup 208}Pb and {sup 209}Bi + (28.2 MeV/u) {sup 136}Xe. The multiplicities of neutrons and charged particles are found to indicate collision impact parameters with different sensitivities. Characteristic correlations observed between massive products and light particles suggest the dominance of the damped-reaction mechanism in the Fermi energy domain. For central collisions, massive fragments are no longer observed, and a considerable fraction of the mass of the system is found disassembled into light particles and clusters. 75 refs., 19 figs.

  8. Coupled operation of the Oak Ridge isochronous cyclotron and the 25 MV tandem

    SciTech Connect

    Lord, R.S.; Ball, J.B.; Beckers, R.M.; Cleary, T.P.; Hudson, E.D.; Ludemann, C.A.; Martin, J.A.; Milner, W.T.; Mosko, S.W.; Ziegler, N.F.

    1981-01-01

    Coupled operation of the 25 MV tandem and the Oak Ridge Isochronous Cyclotron (ORIC) was achieved on January 27, 1981. A beam of 38 MeV /sup 16/O/sup 2 +/ was injected into ORIC, stripped to 8/sup +/ and accelerated to 324 MeV. Shortly afterwards, the energy was increased to the maximum design value of 25 MeV/amu (400 MeV). A spectrum taken of the scattering of this beam from a thin /sup 208/Pb target in the broad range spectrograh exhibited a resolution of 115 keV (FWHM). Performance of the system was in close agreement with that predicted from calculations.

  9. Population and decay of a Kπ=8- two-quasineutron isomer in 244Pu

    NASA Astrophysics Data System (ADS)

    Hota, S. S.; Tandel, S. K.; Chowdhury, P.; Ahmad, I.; Carpenter, M. P.; Chiara, C. J.; Greene, J. P.; Hoffman, C. R.; Jackson, E. G.; Janssens, R. V. F.; Kay, B. P.; Khoo, T. L.; Kondev, F. G.; Lakshmi, S.; Lalkovski, S.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Moran, K.; Peterson, D.; Shirwadkar, U.; Seweryniak, D.; Stefanescu, I.; Toh, Y.; Zhu, S.

    2016-08-01

    The decay of a Kπ=8- isomer in 244Pu and the collective band structures populating the isomer were studied using deep inelastic excitations with 47Ti and 208Pb beams, respectively. Precise measurements of M 1 /E 2 branching ratios in the band confirm a 9 /2-[734] ν⊗7 /2+[624] ν configuration assignment for the isomer, validating the systematics of Kπ=8- , two-quasineutron isomers observed in even-Z , N =150 isotones. These isomers around the deformed shell gap at N =152 provide critical benchmarks for theoretical predictions of single-particle energies in this gateway region to superheavy nuclei.

  10. Trace element and Pb isotope composition of plagioclase from dome samples from the 2004-2005 eruption of Mount St. Helens, Washington: Chapter 35 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Kent, Adam J.R.; Rowe, Michael C.; Thornber, Carl R.; Pallister, John S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Plagioclase crystals from gabbronorite inclusions in three dacite samples have markedly different trace-element and Pbisotope compositions from those of plagioclase phenocrysts, despite having a similar range of anorthite contents. Inclusions show some systematic differences from each other but typically have higher Ti, Ba, LREE, and Pb and lower Sr and have lower 208Pb/206Pb and 207Pb/206Pb ratios than coexisting plagioclase phenocrysts. The compositions of plagioclase from inclusions cannot be related to phenocryst compositions by any reasonable petrologic model. From this we suggest that they are unlikely to represent magmatic cumulates or restite inclusions but instead are samples of mafic Tertiary basement from beneath the volcano.

  11. Spatial coherence measurements of a 13.2 nm transient nickel-likecadmium soft x-ray laser pumped at grazing incidence

    SciTech Connect

    Lui, Y.; Wang, Y.; Larotonda, M.A.; Luther, B.M.; Rocca, J.J.; Attwood, D.T.

    2006-09-27

    We report the experimental confirmation of the production of element 110. In the bombardment of a {sup 208}Pb target with a 309 MeV {sup 64}Ni beam, we have observed two chains of time- and position-correlated events. Each chain consisted of the implantation of an evaporation residue followed by the emission of {alpha}-particles. We attribute these two chains to the decay of {sup 271}110 produced with a cross section of 8.3{sup +11}{sub -5.3} pb.

  12. Comparison of complementary reactions in the production of Mt

    SciTech Connect

    Nelson, S. L.; Dragojevic, I.; Ellison, P. A.; Garcia, M. A.; Gates, J. M.; Nitsche, H.; Gregorich, K. E.; Dvorak, J.; Stavsetra, L.; Ali, M. N.

    2009-02-15

    The new reaction {sup 208}Pb({sup 59}Co,n){sup 266}Mt was studied using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. A cross section of 7.7{sub -3.3}{sup +5.2} pb was measured at a compound nucleus excitation energy of 14.9 MeV. The measured decay properties of {sup 266}Mt and its daughters correspond well with existing data. We compare this experimental result to transactinide compound nucleus formation model predictions, and the previously studied {sup 209}Bi({sup 58}Fe,n){sup 266}Mt reaction.

  13. Experimental Sign of a Weakening of the N=50 Spherical Shell Gap

    SciTech Connect

    Prevost, A.; Astier, A.; Deloncle, I.; Porquet, M.-G.; Lucas, R.

    2006-04-26

    High-spin states of 84Se, produced as a fission fragment in the fusion-fission reaction 18O+208Pb, have been identified for the first time thanks to the EUROBALL IV array. The excitation energies of three of these states, interpreted as being due to the ({nu}g{sub 9/2}{sup -1} {nu}d{sub 5/2}{sup +1}) neutron-core excitation, give new insights about the evolution of the N=50 shell gap at the vicinity of 78Ni.

  14. In-Beam {gamma}-Ray Spectroscopy of the N=50 Isotones on the Neutron-Rich Side

    SciTech Connect

    Prevost, A.; Astier, A.; Deloncle, I.; Porquet, M.-G.; Lucas, R.

    2005-11-21

    High-spin states of 84Se, produced as a fission fragment in the fusion-fission reaction 18O+208Pb and studied with the EUROBALL IV array, have been identified for the first time. Their interpretation gives new insights about the evolution of the N=50 shell gap at the vicinity of 78Ni. To characterize this evolution, it would be worth using a new device devoted to the high-spin studies of neutron-rich nuclei produced by asymmetric fission modes. Such dedicated studies are reported in a second part.

  15. α-nucleus potential for α-decay and sub-barrier fusion

    NASA Astrophysics Data System (ADS)

    Denisov, V. Yu.; Ikezoe, H.

    2005-12-01

    The set of parameters for α-nucleus potential is derived by using the data for both the α-decay half-lives and the fusion cross sections around the barrier for reactions α+40Ca, α+59Co, and α+208Pb. The α-decay half-lives are obtained in the framework of a cluster model using the WKB approximation. The evaluated α-decay half-lives and the fusion cross sections agreed well with the data. Fusion reactions between α particles and heavy nuclei can be used for both the formation of very heavy nuclei and spectroscopic studies of the formed compound nuclei.

  16. Relativistic analysis of proton elastic scattering

    NASA Astrophysics Data System (ADS)

    El Nohy, N. A.; El-Hammamy, M. N.; Yoseph, S. I.; Abdel-Moneim, A. M.

    2015-04-01

    The Dirac equation as the relevant wave equation, is used in modified DWUCK4 program to calculate the elastic scattering cross section throughout the energy range suitable for relativistic treatment of proton elastic scattering by nuclei 40Ca, 58Ni, 90Zr and 208Pb. A good fit to the experimental data is presented. The real and imaginary potentials are well determined and behave regularly with energy. The behaviour of the real central effective potential shows the development of a "wine-bottle" shape in the transition energy region and the persistence of a small attractive potential in the nuclear surface region, even at 800 MeV.

  17. Reaction-dependent spin population and evidence of breakup in {sup 18}O

    SciTech Connect

    Hojman, D.; Pacheco, A.J.; Testoni, J.E.; Davidson, J.; Davidson, M.; Cardona, M.A.; Fernandez-Niello, J.O.; Kreiner, A.J.; Arazi, A.; Capurro, O.A.; Marti, G.V.; Bazzacco, D.; Lenzi, S.M.; Lunardi, S.; Alvarez, C. Rossi; Ur, C.; Burlon, A.; Debray, M.E.; De Angelis, G.; De Poli, M.

    2006-04-15

    Angular distributions and angular correlations have been measured for the emission of one and two {alpha}-particles in the {sup 18}O+{sup 207,208}Pb,{sup 209}Bi reactions at several beam energies above the Coulomb barrier. The results rule out fusion evaporation as the main reaction mechanism for the channels involving {alpha}-particle emission and support the interpretation of the breakup of the {sup 18}O projectiles into at least {sup 14}C+{alpha} and {sup 10}Be+{sup 8}Be before fusion.

  18. Antiproliferative Activity and in Vivo Toxicity of Double-Point Modified Analogs of 1,25-Dihydroxyergocalciferol

    PubMed Central

    Trynda, Justyna; Turlej, Eliza; Milczarek, Magdalena; Pietraszek, Anita; Chodyński, Michał; Kutner, Andrzej; Wietrzyk, Joanna

    2015-01-01

    Analogs of 1,25-dihydroxyergocalciferol, modified in the side-chain and in the A-ring, were tested for their antiproliferative activity against a series of human cancer cell lines in vitro and in vivo toxicity. The proliferation inhibition caused by the analogs was higher than that of the parent compounds, while the toxicity, measured as the serum calcium level, was lower. All analogs were able to induce, in HL-60 and MV4-11 leukemic cells, G0/G1 cell cycle arrest and differentiation expressed as morphological signs typical for monocytes. The analogs also induced the expression of CD11b and/or CD14 cell-differentiation markers. The most potent analogs, PRI-5105, PRI-5106, PRI-5201 and PRI-5202, were also able to induce vitamin D receptor (VDR) protein expression, mainly in the cytoplasmic fraction of HL-60 or MV4-11 cells. The most active analogs were the 19-nor ones with an extended and rigidified side-chain (PRI-5201 and PRI-5202), as in the former analogs PRI-1906 and PRI-1907. Epimerization at C-24 (PRI-5101) or introduction of an additional hydroxyl at C-23 (PRI-5104) reduced the toxicity of the analog with retained antiproliferative activity. PMID:26492238

  19. Tests of Multi-Nucleon Transfer Models Using Gamma-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    McCaleb, Kyle; Yanez, Ricardo; Loveland, Walter; OSU-ANL-BNL-ANU-UMd Collaboration

    2016-09-01

    It has been suggested that multi-nucleon transfer (MNT) reactions can be effective tools in synthesizing N=126 and n-rich heavy nuclei. We are engaged in a program to measure the yields of projectile-like fragments (PLFs) and target-like fragments (TLFs) in the interaction of 450 MeV 136Xe with 208Pb, 860 MeV 136Xe with 198Pt, and 1360 and 1700 MeV 204Hg with 208Pb. The use of in-beam, out of beam and post irradiation γ-ray spectroscopy using Gammasphere and single Ge detectors. We compare our results to the predictions of Zagrebaev and Greiner and semi-classical models such as GRAZING-F. We find the predictions of the GRAZING-F model represent, at best, the yields of the ΔZ = +/- 0,1,2 products while the Z-G predictions do a much better job of representing the yields of the large transfers. This work was supported, in part, by the Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Grant DE-SC0014380 and the National Science Foundation.

  20. A study on the Fresnel diffraction of {sup 6}He by means of different microscopic density distributions

    SciTech Connect

    Aygun, M.; Boztosun, I.; Sahin, Y.

    2012-08-15

    The elastic scattering of the halo nucleus {sup 6}He from heavy targets such as {sup 197}Au and {sup 208}Pb has been investigated in order to explain the Coulomb rainbow peak due to the Fresnel-type diffraction observed in the experimental data. In order to examine the role of nuclear potential to describe {sup 6}He + {sup 197}Au and {sup 6}He + {sup 208}Pb systems, we have used the no-core shell model, few-body and Gaussian-shaped density distributions at various energies. The microscopic real parts of the complex nuclear potential have been obtained by using the double-folding model for each of the density distribution and the phenomenological imaginary potentials have been taken as the standard Woods-Saxon shape. We have observed that fewbody and Gaussian-shaped density distributions have given standard Fresnel-type diffraction results, a classical scattering pattern with Coulomb rainbow peak whereas the nuclear potential obtained by using the no-core shell-model density distribution has provided the reduction at Fresnel peak and has given more consistent results with the experimental data.

  1. Comparison of complementary reactions for the production of {sup 261,262}Bh

    SciTech Connect

    Nelson, S. L.; Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nitsche, H.; Gregorich, K. E.; Sudowe, R.; Duellmann, Ch. E.; Eichler, R.

    2008-08-15

    Two heavy-ion induced fusion reactions producing {sup 261,262}Bh were studied using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. An excitation function for the production of {sup 262}Bh via the reaction {sup 209}Bi({sup 54}Cr,n){sup 262}Bh was measured with a maximum cross section from a fit to the data of 430 {+-} 110 pb observed at a compound nucleus excitation energy of 15.7 MeV. New data have been measured for the 1n exit channel of the {sup 208}Pb({sup 55}Mn, n){sup 262}Bh reaction. We present an updated excitation function with an observed maximum cross section of 530{+-}100 pb at a compound nucleus excitation energy of 14.1 MeV. Events corresponding to the 2n exit channel for the {sup 209}Bi({sup 54}Cr,2n){sup 261}Bh and {sup 208}Pb({sup 55}Mn,2n){sup 261}Bh reactions were also observed and are presented as partial excitation functions. The measured decay properties correspond well with existing experimental data. We compare these experimental results to cross section predictions from a model by Swiatecki et al. and discuss entrance channel effects on the magnitude of 1n cross sections.

  2. Field isotopic study of lead fate and compartmentalization in earthworm-soil-metal particle systems for highly polluted soil near Pb recycling factory.

    PubMed

    Goix, Sylvaine; Mombo, Stéphane; Schreck, Eva; Pierart, Antoine; Lévêque, Thibaut; Deola, Frédéric; Dumat, Camille

    2015-11-01

    Earthworms are important organisms in soil macrofauna and play a key role in soil functionality, and consequently in terrestrial ecotoxicological risk assessments. Because they are frequently observed in soils strongly polluted by metals, the influence of earthworm bioturbation on Pb fate could therefore be studied through the use of Pb isotopes. Total Pb concentrations and isotopic composition ((206)Pb, (207)Pb and (208)Pb) were then measured in earthworms, casts and bulk soils sampled at different distance from a lead recycling factory. Results showed decreasing Pb concentrations with the distance from the factory whatever the considered matrix (bulk soils, earthworm bodies or cast samples) with higher concentrations in bulk soils than in cast samples. The bivariate plot (208)Pb/(206)Pb ratios versus (206)Pb/(207)Pb ratios showed that all samples can be considered as a linear mixing between metallic process particulate matter (PM) and geochemical Pb background. Calculated anthropogenic fraction of Pb varied between approximately 84% and 100%. Based on Pb isotopic signatures, the comparison between casts, earthworms and bulk soils allowed to conclude that earthworms preferentially ingest the anthropogenic lead fraction associated with coarse soil organic matter. Actually, soil organic matter was better correlated with Pb isotopic ratios than with Pb content in soils. The proposed hypothesis is therefore a decrease of soil organic matter turnover due to Pb pollution with consequences on Pb distribution in soils and earthworm exposure. Finally, Pb isotopes analysis constitutes an efficient tool to study the influence of earthworm bioturbation on Pb cycle in polluted soils.

  3. One century sedimentary record of lead and zinc pollution in Yangzong Lake, a highland lake in southwestern China.

    PubMed

    Zhang, Enlou; Liu, Enfeng; Shen, Ji; Cao, Yanmin; Li, Yanling

    2012-01-01

    Reconstruction of trace metal pollution histories and sources may help us to regulate current pollutant discharge. This is especially important for the highland lakes in southwestern China, which are facing trace metals pollution. We present sedimentary records of 11 metals accumulated in Yangzong Lake since the 1870's, a highland lake in southwestern China. Pollution of lead and zinc (Pb and Zn) was differentiated based on principal component analysis, geochemical normalization, and lead isotope ratios. Nearly all the metals as well as grain size composition show generally constant values before the mid-1980's, denoting stable detrital input in the catchment. Fluctuations in the concentrations of the metals as well as grain size composition since the mid-1980's indicate an increase in soil erosion with strengthened human disturbance in the catchment. After geochemical normalization, Pb and Zn showed constant values before 1990 AD and then a gradual increase in parallel with the variations in 208Pb/206Pb and 207Pb/206Pb ratios, indicating that Pb and Zn pollution occurred. Combining the data of 208pb/206Pb and 207Pb/6Pb ratios in the sediments of Yangzong Lake, leaded gasoline, Pb-Zn ore and coal, and consumption or production historical trends, we deduced that the enhanced Pb and Zn pollution in Yangzong Lake is caused primarily by ore mining and refining.

  4. Lead and strontium isotopic evidence for crustal interaction and compositional zonation in the source regions of Pleistocene basaltic and rhyolitic magmas of the Coso volcanic field, California

    USGS Publications Warehouse

    Bacon, C.R.; Kurasawa, H.; Delevaux, M.H.; Kistler, R.W.; Doe, B.R.

    1984-01-01

    The isotopic compositions of Pb and Sr in Pleistocene basalt, high-silica rhyolite, and andesitic inclusions in rhyolite of the Coso volcanic field indicate that these rocks were derived from different levels of compositionally zoned magmatic systems. The 2 earliest rhyolites probably were tapped from short-lived silicic reservoirs, in contrast to the other 36 rhyolite domes and lava flows which the isotopic data suggest may have been leaked from the top of a single, long-lived magmatic system. Most Coso basalts show isotopic, geochemical, and mineralogic evidence of interaction with crustal rocks, but one analyzed flow has isotopic ratios that may represent mantle values (87Sr/86Sr=0.7036,206Pb/204Pb=19.05,207Pb/204Pb=15.62,208Pb/204Pb= 38.63). The (initial) isotopic composition of typical rhyolite (87Sr/86Sr=0.7053,206Pb/204Pb=19.29,207Pb/204Pb= 15.68,208Pb/204Pb=39.00) is representative of the middle or upper crust. Andesitic inclusions in the rhyolites are evidently samples of hybrid magmas from the silicic/mafic interface in vertically zoned magma reservoirs. Silicic end-member compositions inferred for these mixed magmas, however, are not those of erupted rhyolite but reflect the zonation within the silicic part of the magma reservoir. The compositional contrast at the interface between mafic and silicic parts of these systems apparently was greater for the earlier, smaller reservoirs. ?? 1984 Springer-Verlag.

  5. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    NASA Astrophysics Data System (ADS)

    Ning-jing, Hu; Peng, Huang; Hui, Zhang; Ai-mei, Zhu; Ji-hua, Liu; Jun, Zhang; Lian-hua, He

    2015-10-01

    To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8±7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997±0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477±0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  6. Very low-energy neutrino interactions

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reaction cross sections are now evaluated rather accurately by shell-model (SM) or SM+RPA calculations based on recent advances in nuclear structure studies. Due to these achievements, reliable constraints on super-nova neutrino temperatures as well as neutrino oscillation parameters become possible. Supernova neutrino tempeatures are constrained from abundances of elements obtained by using new ν-nucleus reaction cross sections. A possibility of constructing supernova neutrino spectrum from beta-beam measurements is pointed out. Neutrino mass hierarchy and mixing angle θ{sub 13} can be determined from abundance ratio of {sup 7}Li/{sup 11}B, which is sensitive to the MSW matter oscillation effects in supernova explosions. Inverted mass hierarchy is shown to be statistically more favored based on a recent analysis of presolar grains. Effects of neutrino-neutrino interactions are also shown to play important roles in r-process nucleosynthesis. Importance and possibilities of direct measurements of ν-induced cross sections on {sup 40}Ar and {sup 208}Pb are discussed for future supernova neutrino detections. Recent calculations of the cross sections for ν-{sup 40}Ar are presented. The need for new theoretical evaluations of the cross sections for ν-{sup 208}Pb is pointed out. Challenges to experiments on coherent elastic scattering are presented.

  7. Neutron Emission in Fission And Quasi-Fission of Hs

    SciTech Connect

    Itkis, I. M.; Itkis, M. G.; Knyazheva, G. N.; Kozulin, E. M.; Krupa, L.; Hanappe, F.; Dorvaux, O.; Stuttge, L.

    2010-04-30

    Mass and energy distributions of fission-like fragments obtained in the reactions {sup 26}Mg+{sup 248}Cm, {sup 36}S+{sup 238}U and {sup 58}Fe+{sup 208}Pb leading to the formation of {sup 266,274}Hs are reported. From the analysis of TKE distributions for symmetric fragment it was found that at energies below the Coulomb barrier the bimodal fission of {sup 274}Hs, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed, while in the reaction {sup 36}S+{sup 238}U at these energies the main part of the symmetric fragments arises from the quasi-fission process. At energies above the Coulomb barrier the fusion-fission is a main process leading to the formation of symmetric fragment for the both reactions. In the case of {sup 58}Fe+{sup 208}Pb reaction the quasi-fission process is the main reaction mechanism at all measured energies. The pre- and post-scission neutron multiplicities as a function of the fragment mass have been obtained for all studied reactions.

  8. Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats

    PubMed Central

    Han, Pingping; Lu, Shifeier; Zhou, Yinghong; Moromizato, Karine; Du, Zhibin; Friis, Thor; Xiao, Yin

    2016-01-01

    Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of 25Mg, 28Si, 39K, 47Ti, 56Fe, 59Co, 77Se, 88Sr, 137Ba, and 208Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of 28Si, 77Se, 208Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla. PMID:27338361

  9. Flux rates of atmospheric lead pollution within soils of a small catchment in northern Sweden and their implications for future stream water quality.

    PubMed

    Klaminder, Jonatan; Bindler, Richard; Laudon, Hjalmar; Bishop, Kevin; Emteryd, Ove; Renberg, Ingemar

    2006-08-01

    It is not well-known how the accumulated pool of atmospheric lead pollution in the boreal forest soil will affect the groundwater and surface water chemistry in the future as this lead migrates through the soil profile. This study uses stable lead isotopes (206Pb/207Pb and 208Pb/ 207Pb ratios) to trace the transport of atmospheric lead pollution within the soil of a small catchment and predict future lead level changes in a stream draining the catchment. Low 206Pb/207Pb and 208Pb/207Pb ratios for the lead in the soil water (1.16 +/- 0.02; 2.43 +/- 0.03) and streamwater (1.18 +/- 0.03; 2.42 +/- 0.03) in comparison to that of the mineral soil (>1.4; >2.5) suggest that atmospheric pollution contributes by about 90% (65-100%) to the lead pool found in these matrixes. Calculated transport rates of atmospheric lead along a soil transect indicate that the mean residence time of lead in organic and mineral soil layers is at a centennial to millennial time scale. A maximum release of the present pool of lead pollution in the soil to the stream is predicted to occur within 200-800 years. Even though the uncertainty of the prediction is large, it emphasizes the magnitude of the time lag between the accumulation of atmospheric lead pollution in soils and the subsequent response in streamwater quality.

  10. Lead Isotope Characterization of Petroleum Fuels in Taipei, Taiwan

    PubMed Central

    Yao, Pei-Hsuan; Shyu, Guey-Shin; Chang, Ying-Fang; Chou, Yu-Chen; Shen, Chuan-Chou; Chou, Chi-Su; Chang, Tsun-Kuo

    2015-01-01

    Leaded gasoline in Taiwan was gradually phased out from 1983 to 2000. However, it is unclear whether unleaded gasoline still contributes to atmospheric lead (Pb) exposure in urban areas. In this study, Pb isotopic compositions of unleaded gasolines, with octane numbers of 92, 95, 98, and diesel from two local suppliers in Taipei were determined by multi-collector inductively coupled plasma mass spectrometry with a two-sigma uncertainty of ± 0.02 %. Lead isotopic ratios of vehicle exhaust (208Pb/207Pb: 2.427, 206Pb/207Pb: 1.148, as estimated from petroleum fuels) overlap with the reported aerosol data. This agreement indicates that local unleaded petroleum fuels, containing 10–45 ng·Pb·g−1, are merely one contributor among various sources to urban aerosol Pb. Additionally, the distinction between the products of the two companies is statistically significant in their individual 208Pb/206Pb ratios (p-value < 0.001, t test). Lead isotopic characterization appears to be applicable as a “fingerprinting” tool for tracing the sources of Pb pollution. PMID:25918913

  11. Chronicling a century of lead pollution in Mexico: stable lead isotopic composition analyses of dated sediment cores.

    PubMed

    Soto-Jimenez, Martin F; Hibdon, Sharon A; Rankin, Charley W; Aggarawl, Jugdeep; Ruiz-Fernandez, A Carolina; Paez-Osuna, Federico; Flegal, A Russell

    2006-02-01

    Analyses of lead isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of dated sediment cores from two coastal estuaries and two inland lakes chronicle the predominance of industrial lead emissions in Mexico over the past century. These isotopic ratios exhibit a shift in composition from the turn of the previous century (1900) that corresponds with measurable increases (from 2- to 10-fold) in lead concentrations in the cores above their baseline values (3-22 microg/g)--both changes are consistent with the development of Mexican lead production for export and the manufacture of tetraethyl lead additives for Mexican gasolines. While subsequent changes in lead concentrations in the cores correspond with calculated emissions from the combustion of leaded gasoline in Mexico, isotopic compositions of the cores remain relatively constant throughout most of the 1900s (e.g., 206Pb/207Pb = 1.200 +/- 0.003; 208Pb/207Pb = 2.463 +/- 0.004). That isotopic constancy is attributed to the widespread pollution from lead production in Mexico and the dispersion of some of that lead used as an additive in Mexican gasolines.

  12. Benchmarking nuclear models for Gamow-Teller response

    NASA Astrophysics Data System (ADS)

    Litvinova, E.; Brown, B. A.; Fang, D.-L.; Marketin, T.; Zegers, R. G. T.

    2014-03-01

    A comparative study of the nuclear Gamow-Teller response (GTR) within conceptually different state-of-the-art approaches is presented. Three nuclear microscopic models are considered: (i) the recently developed charge-exchange relativistic time blocking approximation (RTBA) based on the covariant density functional theory, (ii) the shell model (SM) with an extended “jj77” model space and (iii) the non-relativistic quasiparticle random-phase approximation (QRPA) with a Brueckner G-matrix effective interaction. We study the physics cases where two or all three of these models can be applied. The Gamow-Teller response functions are calculated for 208Pb, 132Sn and 78Ni within both RTBA and QRPA. The strengths obtained for 208Pb are compared to data that enable a firm model benchmarking. For the nucleus 132Sn, also SM calculations are performed within the model space truncated at the level of a particle-hole (ph) coupled to vibration configurations. This allows a consistent comparison to the RTBA where ph⊗phonon coupling is responsible for the spreading width and considerable quenching of the GTR. Differences between the models and perspectives of their future developments are discussed.

  13. Nuclear structure studies of 202Hg and 203Tl using deep-inelastic collisions

    NASA Astrophysics Data System (ADS)

    Gass, Emily; McCutchan, E. A.; Sonzogni, A. A.; Barrett, J. S.; Loveland, W.; Yanez, R.; Zhu, S.; Ayangeakaa, A. D.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Lauritsen, T.; Chiara, C. J.; Harker, J. L.; Walters, W. B.

    2016-09-01

    Nuclei with a few valence nucleons outside 208Pb are crucial for testing the nuclear shell model and guiding our understanding of single particle structure. Data in this region are also potentially relevant to nuclear astrophysics. This analysis focused on the high-spin structure of 202Hg and 203Tl. Excited states in these nuclei were populated through deep-inelastic reactions from a beam of 136Xe and that was incident on a thick target of 208Pb in the Gammasphere array at Argonne National Laboratory. The level schemes of 202Hg and 203Tl were extended by locating a new isomer in each nucleus and a number of new high-spin states built on top of the isomers. The newly-observed states will be discussed in the context of the shell model. Supported by US DOE under the SULI Program and Grant Nos. DE-FG06-97ER41026 and DE-FG02-94ER40834 and Contract Nos. DE-AC02-06CH11357 and DE-AC02-06CH10886.

  14. Nuclear target development

    SciTech Connect

    Greene, J.P.; Thomas, G.E.

    1995-08-01

    The Physics Division operates a target development laboratory that produces thin foil targets needed for experiments performed at the ATLAS and Dynamitron accelerators. Targets are not only produced for the Physics Division but also for other divisions and occasionally for other laboratories and universities. In the past year, numerous targets were fabricated by vacuum evaporation either as self-supporting foils or on various substrates. Targets produced included Ag, Au, {sup 10,11}B, {sup 138}Ba, Be, {sup 12}C, {sup 40}Ca, {sup 116}Cd, {sup 155,160}Gd, {sup 76}Ge, In, LID, {sup 6}LiH, Melamine, Mg, {sup 142,150}Nd, {sup 58}Ni, {sup 206,208}Pb, {sup 194}Pt, {sup 28}Si, {sup 144,148}Sm, {sup 120,122,124}Sn, Ta, {sup 130}Te, ThF{sub 4}, {sup 46,50}Ti, TiH, U, UF{sub 4}, {sup 182}W and {sup 170}Yb. Polypropylene and aluminized polypropylene, along with metallized Mylar were produced for experiments at ATLAS. A number of targets of {sup 11}B of various thickness were made for the DEP 2-MeV Van de Graff accelerator. An increased output of foils fabricated using our small rolling mill included targets of Au, C, {sup 50}Cr, Cu, {sup 155,160}Gd, Mg, {sup 58}Ni, {sup 208}Pb, {sup 105,110}Pd. Sc, Ti, and {sup 64,66}Zn.

  15. Measurements of neutron skin in calcium and lead

    NASA Astrophysics Data System (ADS)

    Michaels, Robert

    2017-01-01

    Measurement of the parity-violating electron scattering asymmetry from 208Pb has demonstrated a new opportunity at Jefferson Lab to measure the weak charge form factor and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on 208Pb and 48Ca respectively. PREX-I ran in 2010, and CREX and a second run of PREX are currently in preparation. These are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter 48Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces. The measuements are a fundamental test of nuclear structure with applications to heavy ion research and neutron stars. Jefferson Science Associates, LLC, which operates Jefferson Lab for the U.S. DOE under U.S. DOE contract DE-AC05-060R23177.

  16. A direct comparison of the ages of detrital monazite versus detrital zircon in Appalachian foreland basin sandstones: Searching for the record of Phanerozoic orogenic events

    NASA Astrophysics Data System (ADS)

    Hietpas, Jack; Samson, Scott; Moecher, David

    2011-10-01

    The provenance potential of detrital monazite was investigated by in situ measurement of 232Th- 208Pb dates of grains isolated from six Middle Carboniferous-Permian sandstones from the Appalachian foreland basin. Provenance assessment of these units was previously investigated by measuring U-Pb crystallization ages of detrital zircon (Thomas et al., 2004; Becker et al., 2005, 2006). Approximately 90% of the detrital zircon ages record Mesoproterozoic or older ages, with only 10% recording the three major pulses of tectonism (Taconian, Acadian and Alleghanian) that are the hallmark of the Appalachian Orogen. 232Th- 208Pb ages of detrital monazite, however, strongly record the complex phases of Paleozoic orogenesis. Nearly 65% of the ages record Paleozoic events, while 35% record Neoproterozoic or older ages. In several of the analyzed sandstones, detrital monazite ages record Paleozoic orogenic events that are completely missed by detrital zircon ages, demonstrating that monazite ages more accurately reflect the character of the sediment source rocks. The inferred maximum age of sediment deposition, as determined by the youngest monazite grains, is ~ 550 Ma younger for two of the analyzed sandstones compared to depositional constraints based on the youngest detrital zircon. The different physical properties and petrogenesis of zircon and monazite are interpreted to be factors for the dramatic differences in sediment provenance information provided by each mineral. The results from this study have important implications for determining sediment provenance, constraining maximum age of sediment deposition, and developing robust regional tectonic models.

  17. Nuclear shape isomers

    NASA Astrophysics Data System (ADS)

    Möller, P.; Sierk, A. J.; Bengtsson, R.; Sagawa, H.; Ichikawa, T.

    2012-03-01

    We calculate potential-energy surfaces as functions of spheroidal (ɛ2), hexadecapole (ɛ4), and axial-asymmetry (γ) shape coordinates for 7206 nuclei from A=31 to A=290. We tabulate the deformations and energies of all minima deeper than 0.2 MeV and of the saddles between all pairs of minima. The tabulation is terminated at N=160. Our study is based on the FRLDM macroscopic-microscopic model defined in ATOMIC DATA AND NUCLEAR DATA TABLES [P. Möller, J.R. Nix, W.D. Myers, W.J. Swiatecki, At. Data Nucl. Data Tables 59 (1995) 185]. We also present potential-energy contour plots versus ɛ2 and γ for 1224 even-even nuclei in the region studied. We can identify nuclei for which a necessary condition for shape isomers occurs, namely multiple minima in the calculated potential-energy surface. We find that the vast majority of nuclear shape isomers occur in the A=80 region, the A=100 region, and in a more extended region centered around 208Pb. A calculated region of shape isomers that has so far not been extensively explored is the region of neutron-deficient actinides "north-east" of 208Pb.

  18. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    PubMed

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data.

  19. Distinction between elastic scattering of weakly bound proton- and neutron-rich nuclei: The case of 8B and 11Be

    NASA Astrophysics Data System (ADS)

    Yang, Y. Y.; Liu, X.; Pang, D. Y.

    2016-09-01

    Experimental data show that the elastic scattering cross sections of the neutron-rich nucleus 11Be are greatly reduced by the coupling effects from the breakup channels, while those of the proton-rich nucleus 8B are not. Such difference is found to persist in results of systematic calculations of 8B elastic scattering from 208Pb at 60 and 170.3 MeV and from 64Zn at 32 and 86 MeV, and 11Be elastic scattering from 208Pb at 55 and 143 MeV and from 64Zn at 29 and 66 MeV with the continuum-discretized coupled channel (CDCC) method. The Coulomb and centrifugal barriers experienced by the valence proton in the ground state of 8B, which do not exist for the valence neutron in the ground state of 11Be, are found to be the reason for such differences in the angular distributions of elastic scattering cross sections of these two weakly bound nuclei.

  20. Historical record of metal accumulation and lead source in the southeastern coastal region of Korea.

    PubMed

    Lim, Dhong-il; Jung, Seung Woon; Choi, Man Sik; Kang, Sun Mee; Jung, Hoi Soo; Choi, Jin Yong

    2013-09-15

    Concentrations of heavy metals and Pb isotopes were measured in the 1-M HCl leaching fraction of core sediments spanning the last 400 years. This sedimentary record of pollution history in metal concentrations shows a good correlation with the increases in industrialization, urbanization, and energy consumption since 1901s. Notably, the Pb concentration and the (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios were constant before the 1910s (16.7 μg/g, 0.844, and 2.098, respectively), whereas they increased steadily up to 21.9 μg/g, 0.848, and 2.101 after the 1910s. The correlations between Pb isotope ratios ((206)Pb, (207)Pb, and (208)Pb) showed different linear regression trends for core sediments before and after the 1910s, indicating differences in Pb sources. Our interpretation suggests that the source of anthropogenic Pb in Korean coastal region and the Yellow Sea shelf was presumed to be Chinese coals or ores, which have also played a major role as sources of atmospheric particulate Pb.

  1. Failure of the Woods-Saxon nuclear potential to simultaneously reproduce precise fusion and elastic scattering measurements

    SciTech Connect

    Mukherjee, A.; Hinde, D. J.; Dasgupta, M.; Newton, J. O.; Butt, R. D.; Hagino, K.

    2007-04-15

    A precise fusion excitation function has been measured for the {sup 12}C+{sup 208}Pb reaction at energies around the barrier, allowing the fusion barrier distribution to be extracted. The fusion cross sections at high energies differ significantly from existing fusion data. Coupled reaction channels calculations have been carried out with the code FRESCO. A bare potential previously claimed to uniquely describe a wide range of {sup 12}C+{sup 208}Pb near-barrier reaction channels failed to reproduce the new fusion data. The nuclear potential diffuseness of 0.95 fm which fits the fusion excitation function over a broad energy range fails to reproduce the elastic scattering. A diffuseness of 0.55 fm reproduces the fusion barrier distribution and elastic scattering data, but significantly overpredicts the fusion cross sections at high energies. This may be due to physical processes not included in the calculations. To constrain calculations, it is desirable to have precisely measured fusion cross sections, especially at energies around the barrier.

  2. Determination of Optimum Conditions for Distinguishing the Pulse Height Distributions of Atomic and Polyatomic Ions

    SciTech Connect

    Kristo, M J

    2006-12-12

    This work explored the use of pulse height distributions (PHD) from multiplier-type detectors as a means of detecting and eliminating the effects of polyatomic interferences in secondary ion mass spectrometry (SIMS). We explored the behavior of PHD for {sup 235}U{sup +}, {sup 208}Pb{sup 27}Al{sup +} and {sup 207}Pb{sup 28}Si{sup +}, all with a nominal mass-to-charge ratio of 235. In every case, the distribution for the atomic ion ({sup 235}U{sup +}) was clearly shifted relative to the distributions for {sup 208}Pb{sup 27}Al{sup +} and {sup 207}Pb{sup 28}Si{sup +}. When the first surface of the detector is metallic in character, the polyatomic ions are shifted to larger pulse heights relative to the atomic ion. When the first surface of the detector is oxide in character, the atomic ion is shifted to larger pulse heights relative to the polyatomic ions. The relative positioning appear to be stable for a given detector over time at the same secondary ion impact energy. Consequently, it appears to be feasible to use PHD data to detect interfering polyatomic ions and eliminate their deleterious effects using peak deconvolution techniques. Consequently, the updated Ultrafast RAE detector will be designed to make the pulse height information available to the data acquisition system.

  3. Pion and kaon correlations in high energy heavy-ion collisions

    SciTech Connect

    Wolf, K.L.; Wolf, K.L.

    1996-12-31

    Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An upgraded multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization. 35 refs., 15 figs., 5 tabs.

  4. Pion correlations and calorimeter design for high energy heavy ion collisions. Progress report

    SciTech Connect

    Wolf, K.L.

    1997-04-01

    Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An updated multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au + Au reaction, taken with full event characterization.

  5. Pion and kaon correlations in high energy heavy-ion collisions. Annual report, April 1, 1995--March 31, 1996

    SciTech Connect

    Wolf, K.L.

    1996-12-31

    Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV {sup 208}Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered {sup 208}Pb + Pb collisions. An upgraded multiple-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-ion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization.

  6. Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions

    SciTech Connect

    Vale, D.; Rauscher, T.; Paar, N. E-mail: Thomas.Rauscher@unibas.ch

    2016-02-01

    We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for {sup 56}Fe and {sup 208}Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons p(ν-bar {sub e},e{sup +})n are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of ν{sub e}- and ν-bar {sub e}-induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei ({sup 208}Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.

  7. Comparison of the concentrations of metal elements and isotopes of lead found in rice and rice bran.

    PubMed

    Dai, Shouhui; Yang, Hui; Yang, Lan; Wang, Fuhua; Du, Ruiying; Wen, Dian

    2014-08-01

    Very few studies have investigated the difference in the distribution of metal elements between rice and rice bran samples. In this study, the concentrations of 27 metal elements (Li, Be, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, and U) in 56 polished rice and their corresponding bran samples were determined. A significant difference in concentrations of all elements except Ag and Cd was found between rice and bran (P < 0.05), with bran/rice ratios of 1.21 to 36.3. High concentrations of metal elements, especially that of the heavy metal Cr, in bran samples present a potential safety issue for bran products, such as food and feed containing bran. Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios also were determined. The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in bran were generally higher than those in rice (P < 0.0001), and rice and bran samples were distinctly different from each other, indicating that Pb isotope composition is an effective for discriminating between bran and rice samples.

  8. Radii of neutron drops probed via the neutron skin thickness of nuclei

    DOE PAGES

    Zhao, P. W.; Gandolfi, S.

    2016-10-10

    Multineutron systems are crucial to understanding the physics of neutron-rich nuclei and neutron stars. Neutron drops, neutrons confined in an external field, are investigated systematically in both nonrelativistic and relativistic density functional theories and with ab initio calculations. Here, we demonstrate a new strong linear correlation, which is universal in the realm of mean-field models, between the rms radii of neutron drops and the neutron skin thickness of 208 Pb and 48 Ca , i.e., the difference between the neutron and proton rms radii of a nucleus. This correlation can be used to deduce the radii of neutron drops frommore » the measured neutron skin thickness in a model-independent way, and the radii obtained for neutron drops can provide a useful constraint for realistic three-neutron forces, due to its high quality. Furthermore, we present a new correlation between the slope L of the symmetry energy and the radii of neutron drops, and provide the first validation of such a correlation by using density-functional models and ab initio calculations. These newly established correlations, together with more precise measurements of the neutron skin thicknesses of 208 Pb and 48 Ca and/or accurate determinations of L , will have an enduring impact on the understanding of multineutron interactions, neutron-rich nuclei, neutron stars, etc.« less

  9. Identification of trace metal pollution in urban dust from kindergartens using magnetic, geochemical and lead isotopic analyses

    NASA Astrophysics Data System (ADS)

    Zhu, Zongmin; Sun, Guangyi; Bi, Xiangyang; Li, Zhonggen; Yu, Genhua

    2013-10-01

    In the present study, magnetic measurements were combined with geochemical analysis and stable Pb isotopic ratios to reveal the distribution and origination of trace metal pollutants in kindergarten dusts from a typical urban environment of Wuhan, central China. The geoaccumulation index (Igeo) of magnetic properties was more prominent than those of individual metals. The magnetic susceptibility (MS) and trace metals (Zn, Pb, and Cu) in this study together with published results from other Chinese cities formed a liner relationship, suggesting that metal contaminants in Chinese urban areas had similar MS to metal ratios, which could be used as an indicator for identification of pollution sources between Chinese cities and the other Asian cities. Stable Pb isotopic ratios (1.1125-1.1734 for 206Pb/207Pb and 2.4457-2.4679 for 208Pb/207Pb) in the urban dusts from Wuhan were characterized by higher 208Pb component in comparison with those from other Chinese cities. This result combined with principal component analysis (PCA) indicated that metal pollutants in the dusts were derived from industrial activities and coal combustion, whereas the traffic emissions were no longer a predominant pollution source in urban environment. Our study demonstrated that environmental magnetic methods could not only reveal the overall situation of trace metal contamination, but also prove evidence in the identification of pollution sources.

  10. Stable lead isotope ratios in Alaskan arctic aerosols

    NASA Astrophysics Data System (ADS)

    Sturges, W. T.; Hopper, J. F.; Barrie, L. A.; Schnell, R. C.

    Aerosol samples collected at Barrow, Alaska, during February and March 1990 were found to have uniform stable lead isotope compositions. The mean 208Pb/ 207Pb ratio was 2.423±0.009 and the mean 206Pb/ 207Pb ratio was 1.161±0.014. The latter ratio is essentially the same as that obtained from an earlier study of aerosols at two Canadian stations in the High Arctic and is typical of, but not unique to, Eurasian sources of atmospheric lead. Further discriminating power was available in this study through the inclusion of 208Pb/ 207Pb ratios, which provided additional evidence that the former Soviet Union and eastern Europe are major contributors to atmospheric particulate lead in the Alaskan Arctic, accounting for around two-thirds of the particulate lead measured at Barrow. The remaining third of the lead is attributed to west European sources. There was no evidence for a substantial North American component, other than local contamination.

  11. Capture and Fusion-Fission Processes in Heavy Ion Induced Reactions

    NASA Astrophysics Data System (ADS)

    Itkis, M. G.; Beghini, S.; Behera, B. R.; Bogatchev, A. A.; Bouchat, V.; Corradi, L.; Dorvaux, O.; Fioretto, E.; Gadea, A.; Hanappe, F.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Latina, A.; Lyapin, V. G.; Materna, T.; Montagnoli, G.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rowley, N.; Rubchenya, V. A.; Rusanov, A. Ya.; Sagaidak, R. N.; Scarlassara, F.; Schmitt, C.; Stefanini, A. M.; Stuttge, L.; Szilner, S.; Trotta, M.; Trzaska, W. H.; Voskresenski, V. M.

    2005-11-01

    Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions 12C+204Pb, 48Ca+144,154Sm, 168Er, 208Pb, 238U, 244Pu, 248Cm; 58Fe+208Pb, 244Pu, 248Cm, and 64Ni+186W, 242Pu are presented. The choice of the above-mentioned reactions was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 at Dubna using the same reactions. The 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET and the neutron multi-detector DEMON. The role of shell effects and the influence of the entrance channel asymmetry and the deformations of colliding nucleus on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed.

  12. Shell effects in fission and quasi-fission of heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Itkis, M. G.; A¨ysto¨, J.; Beghini, S.; Bogachev, A. A.; Corradi, L.; Dorvaux, O.; Gadea, A.; Giardina, G.; Hanappe, F.; Itkis, I. M.; Jandel, M.; Kliman, J.; Khlebnikov, S. V.; Kniajeva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Latina, A.; Materna, T.; Montagnoli, G.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rowley, N.; Rubchenya, V. A.; Rusanov, A. Ya.; Sagaidak, R. N.; Scarlassara, F.; Stefanini, A. M.; Stuttge, L.; Szilner, S.; Trotta, M.; Trzaska, W. H.; Vakhtin, D. N.; Vinodkumar, A. M.; Voskressenski, V. M.; Zagrebaev, V. I.

    2004-04-01

    Results of the experiments aimed at the study of fission and quasi-fission processes in the reactions 12C+ 204Pb, 48Ca+ 144,154Sm, 168Er, 208Pb, 244Pu, 248Cm; 58Fe+ 208Pb, 244Pu, 248Cm, and 64Ni+ 186W, 242Pu are presented in the work. The choice of the above-mentioned reactions was inspired by recent experiments on the production of the isotopes 283112, 289114 and 283116 at Dubna [1],[2] using the same reactions. The 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) and the Accelerator of the Laboratory of University of Jyvaskyla (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[3] and the neutron multi-detector DEMON[4],[5]. The role of shell effects and the influence of the entrance channel on the mechanism of the compound nucleus fusion-fission and the competitive process of quasi-fission are discussed.

  13. Lead 207, 208 (n, xn gamma) reactions for neutron energies up to 200 MeV

    SciTech Connect

    Pavlik, A.; Vonach, H.; Chadwick, M.B.; Haight, R.C.; Nelson, R.O.; Wender, S.A.; Young, P.G.

    1994-07-01

    High-resolution {gamma}-ray spectra from the interaction of neutrons in the energy range from 3 to 200 MeV with {sup 207,208}Pb were measured with the white neutron source at the WNR facility at Los Alamos National Laboratory. From these data, excitation functions for prominent {gamma} transitions in {sup 200,202,204,206,207,208}Pb were derived from threshold to 200 MeV incident neutron energy. These {gamma}-production cross sections represent formation cross sections for excited states of the residual nuclei. The results are compared with the predictions of nuclear reaction calculations based on the exciton model for precompound emission, the Hauser-Feshbach theory for compound nuclear decay, and coupled channels calculations to account for direct excitation of collective levels. Good agreement was obtained over the entire energy range covered in the experiment with reasonable model parameters. The results demonstrate that multiple preequilibrium emission has to be taken into account above about 40 MeV, and that the level density model of Ignatyuk should be used instead of the Gilbert-Cameron and back-shifted Fermi-gas models if excitation energies exceed about 30 MeV.

  14. Mitigating Corruption in Government Security Forces: The Role of Institutions, Incentives, and Personnel Management in Mexico

    DTIC Science & Technology

    2011-01-01

    Preventive Police PJF Policía Judicial Federal, or Federal Judicial Police PRI Partido Revolucionario Institucional , or Institutional Revolutionary...Partido Revolucionario Institucional , or PRI) emerged as the dominating political force in Mexico in the 20th century. The PRI regime was... tradicional /default.aspx Jacob, Brian A., and Steven D. Levitt, “Rotten Apples: An Investigation of the Prevalence and Predictors of Teacher Cheating

  15. Primitive and contaminated basalts from the Southern Rocky Mountains, U.S.A

    USGS Publications Warehouse

    Doe, B.R.; Lipman, P.W.; Hedge, C.E.; Kurasawa, H.

    1969-01-01

    Basalts in the Southern Rocky Mountains province have been analyzed to determine if any of them are primitive. Alkali plagioclase xenocrysts armored with calcic plagioclase seem to be the best petrographic indicator of contamination. The next best indicator of contamination is quartz xenocrysts armored with clinopyroxene. On the rocks and the region studied, K2O apparently is the only major element with promise of separating primitive basalt from contaminated basalt inasmuch as it constitutes more than 1 % in all the obviously contaminated basalts. K2O: lead (> 4 ppm) and thorium (> 2 ppm) contents and Rb/Sr (> 0.035) are the most indicative of the trace elements studied. Using these criteria, three basalt samples are primitive (although one contains 1.7% K2O) and are similar in traceelement contents to Hawaiian and Eastern Honshu, Japan, primitive basalts. Contamination causes lead isotope ratios, 206Pb/204Pb and 208Pb/204Pb, to become less radiogenic, but it has little or no effect on 87Sr/86Sr. We interpret the effect on lead isotopes to be due to assimilation either of lower crustal granitic rocks, which contain 5-10 times as much lead as basalt and which have been low in U/Pb and Th/Pb since Precambrian times, or of upper crustal Precambrian or Paleozoic rocks, which have lost much of their radiogenic lead because of heating prior to assimilation. The lack of definite effects on strontium isotopes may be due to the lesser strontium contents of granitic crustal rocks relative to basaltic rocks coupled with lack of a large radiogenic enrichment in the crustal rocks. Lead isotope ratios were found to be less radiogenic in plagioclase separates from an obviously contaminated basalt than in the primitive basalts. The feldspar separate that is rich in sodic plagioclase xenocrysts was found to be similar to the whole-rock composition for 206Pb/204Pb and 208Pb/204Pb whereas a more dense fraction probably enriched in more calcic plagioclase phenocrysts is more similar

  16. Skip the alignment: degenerate, multiplex primer and probe design using K-mer matching instead of alignments.

    PubMed

    Hysom, David A; Naraghi-Arani, Pejman; Elsheikh, Maher; Carrillo, A Celena; Williams, Peter L; Gardner, Shea N

    2012-01-01

    PriMux is a new software package for selecting multiplex compatible, degenerate primers and probes to detect diverse targets such as viruses. It requires no multiple sequence alignment, instead applying k-mer algorithms, hence it scales well for large target sets and saves user effort from curating sequences into alignable groups. PriMux has the capability to predict degenerate primers as well as probes suitable for TaqMan or other primer/probe triplet assay formats, or simply probes for microarray or other single-oligo assay formats. PriMux employs suffix array methods for efficient calculations on oligos 10-~100 nt in length. TaqMan® primers and probes for each segment of Rift Valley fever virus were designed using PriMux, and lab testing comparing signatures designed using PriMux versus those designed using traditional methods demonstrated equivalent or better sensitivity for the PriMux-designed signatures compared to traditional signatures. In addition, we used PriMux to design TaqMan® primers and probes for unalignable or poorly alignable groups of targets: that is, all segments of Rift Valley fever virus analyzed as a single target set of 198 sequences, or all 2863 Dengue virus genomes for all four serotypes available at the time of our analysis. The PriMux software is available as open source from http://sourceforge.net/projects/PriMux.

  17. Skip the Alignment: Degenerate, Multiplex Primer and Probe Design Using K-mer Matching Instead of Alignments

    PubMed Central

    Hysom, David A.; Naraghi-Arani, Pejman; Elsheikh, Maher; Carrillo, A. Celena; Williams, Peter L.; Gardner, Shea N.

    2012-01-01

    PriMux is a new software package for selecting multiplex compatible, degenerate primers and probes to detect diverse targets such as viruses. It requires no multiple sequence alignment, instead applying k-mer algorithms, hence it scales well for large target sets and saves user effort from curating sequences into alignable groups. PriMux has the capability to predict degenerate primers as well as probes suitable for TaqMan or other primer/probe triplet assay formats, or simply probes for microarray or other single-oligo assay formats. PriMux employs suffix array methods for efficient calculations on oligos 10-∼100 nt in length. TaqMan® primers and probes for each segment of Rift Valley fever virus were designed using PriMux, and lab testing comparing signatures designed using PriMux versus those designed using traditional methods demonstrated equivalent or better sensitivity for the PriMux-designed signatures compared to traditional signatures. In addition, we used PriMux to design TaqMan® primers and probes for unalignable or poorly alignable groups of targets: that is, all segments of Rift Valley fever virus analyzed as a single target set of 198 sequences, or all 2863 Dengue virus genomes for all four serotypes available at the time of our analysis. The PriMux software is available as open source from http://sourceforge.net/projects/PriMux. PMID:22485178

  18. Transactions Among Partners.

    ERIC Educational Resources Information Center

    Luther, Joseph

    The past and historical future of the Partnership for Rural Improvement (PRI) and its model for rural planning and development are explored. Evolution of the rural-urban conceptual dichotomy is reviewed. Rural is perceived as a state of being rather than a place. Implications of the PRI experience for new knowledge and skills in rural community…

  19. Peeking inside the "Black Box" of the Flynn Effect: Evidence from Three Wechsler Instruments

    ERIC Educational Resources Information Center

    Zhou, Xiaobin; Zhu, Jianjun; Weiss, Lawrence G.

    2010-01-01

    This study investigated the Wechsler Performance IQ (PIQ) or Perceptual Reasoning Index (PRI)/ Perceptual Organization Index (POI) change over time and its relation to ability levels. PIQ or PRI/ POI was analyzed because of the known sensitivity of nonverbal scales to the Flynn effect. Scores were analyzed using two methods. First, analysis of…

  20. Poroelastic Relaxation Indentation of Thin Layers of Gels

    DTIC Science & Technology

    2011-10-24

    polymer rheology J. Chem. Phys. 133, 184904 (2010) Microviscoelasticity of adhesive hard sphere dispersions : Tracer particle microrheology of aqueous...PRI agree well with those obtained from a compression test.17 The PRI has been applied to alginate hydrogels,13,17 polydimethylsiloxane (PDMS) swollen

  1. The Evolution of the Mexican Military: From the Mexican Revolution In 1910 to 2014

    DTIC Science & Technology

    2015-03-01

    that still relllllins after the seventy-one year m le of the PRI. Additionally, it discusses some of the historical effects of civilian control within...that still remains after the seventy-one year rule of the PRI. Additionally, it discusses some of the historical effects of civilian control within...4 D. POTENTIAL EXPLANATIONS AND HYPOTHESES .............................5 E. HISTORICAL BACKGROUND

  2. A Hand-Off Mechanism for Primosome Assembly in Replication Restart

    SciTech Connect

    Lopper, Matthew; Boonsombat, Ruethairat; Sandler, Steven J.; Keck, James L.

    2008-11-12

    Collapsed DNA replication forks must be reactivated through origin-independent reloading of the replication machinery (replisome) to ensure complete duplication of cellular genomes. In E. coli, the PriA-dependent pathway is the major replication restart mechanism and requires primosome proteins PriA, PriB, and DnaT for replisome reloading. However, the molecular mechanisms that regulate origin-independent replisome loading are not fully understood. Here, we demonstrate that assembly of primosome protein complexes represents a key regulatory mechanism, as inherently weak PriA-PriB and PriB-DnaT interactions are strongly stimulated by single-stranded DNA. Furthermore, the binding site on PriB for single-stranded DNA partially overlaps the binding sites for PriA and DnaT, suggesting a dynamic primosome assembly process in which single-stranded DNA is handed off from one primosome protein to another as a repaired replication fork is reactivated. This model helps explain how origin-independent initiation of DNA replication is restricted to repaired replication forks, preventing overreplication of the genome.

  3. Deconvolution of pigment and physiologically related photochemical reflectance index variability at the canopy scale over an entire growing season.

    PubMed

    Hmimina, G; Merlier, E; Dufrêne, E; Soudani, K

    2015-08-01

    The sensitivity of the photochemical reflectance index (PRI) to leaf pigmentation and its impacts on its potential as a proxy for light-use efficiency (LUE) have recently been shown to be problematic at the leaf scale. Most leaf-to-leaf and seasonal variability can be explained by such a confounding effect. This study relies on the analysis of PRI light curves that were generated at the canopy scale under natural conditions to derive a precise deconvolution of pigment-related and physiologically related variability in the PRI. These sources of variability were explained by measured or estimated physiologically relevant variables, such as soil water content, that can be used as indicators of water availability and canopy chlorophyll content. The PRI mainly reflected the variability in the pigment content of the canopy. However, the corrected PRI, which was obtained by subtracting the pigment-related seasonal variability from the PRI measurement, was highly correlated with the upscaled LUE measurements. Moreover, the sensitivity of the PRI to the leaf pigment content may mask the PRI versus LUE relationship or result in an artificial relationship that reflects the relationship of chlorophyll versus LUE, depending on the species phenology.

  4. Containing arsenic-enriched groundwater tracing lead isotopic compositions of common arsenical pesticides in a coastal Maine watershed

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.; Robinson, Glipin R.; Colvin, A.S.; Lipfert, G.; Reeve, A.S.

    2006-01-01

    Arsenical pesticides and herbicides were extensively used on apple, blueberry, and potato crops in New England during the first half of the twentieth century. Lead arsenate was the most heavily used arsenical pesticide until it was officially banned. Lead arsenate, calcium arsenate, and sodium arsenate have similar Pb isotope compositions: 208Pb207Pb = 2.3839-2.4722, and 206Pb207Pb = 1.1035-1.2010. Other arsenical pesticides such as copper acetoarsenite (Paris green), methyl arsonic acid and methane arsonic acid, as well as arsanilic acid are widely variable in isotope composition. Although a complete understanding of the effects of historical use of arsenical pesticides is not available, initial studies indicate that arsenic and lead concentrations in stream sediments in New England are higher in agricultural areas that intensely used arsenical pesticides than in other areas. The Pb isotope compositions of pesticides partially overlap values of stream sediments from areas with the most extensive agricultural use. The lingering effects of arsenical pesticide use were tested in a detailed geochemical and isotopic study of soil profiles from a watershed containing arsenic-enriched ground water in coastal Maine. Acid-leach compositions of the soils represent lead adsorbed to mineral surfaces or held in soluble minerals (Fe- and Mn-hydroxides, carbonate, and some micaceous minerals), whereas residue compositions likely reflect bedrock compositions. The soil profiles contain labile Pb (acid-leach) showing a moderate range in 206Pb 207Pb (1.1870-1.2069), and 208Pb207Pb (2.4519-2.4876). Isotope values vary as a function of depth: the lowest Pb isotope ratios (e.g.,208Pb206Pb) representing labile lead are in the uppermost soil horizons. Lead contents decrease with depth in the soil profiles. Arsenic contents show no clear trend with depth. A multi-component mixing scheme that included lead from the local parent rock (Penobscot Formation), lead derived from combustion of

  5. Lead pollution in subtropical ecosystems on the SE Gulf of California Coast: a study of concentrations and isotopic composition.

    PubMed

    Soto-Jiménez, Martin F; Páez-Osuna, Federico; Scelfo, Genine; Hibdon, Sharon; Franks, Rob; Aggarawl, Jugdeep; Flegal, A Russell

    2008-10-01

    Lead pollution was investigated in environmental matrices and biological indicators collected from two typical subtropical coastal ecosystems in the southeast Gulf of California, Mexico. Lead concentrations and isotopic compositions ((206)Pb/(207)Pb and (208)Pb/(207)Pb) were measured using high resolution inductively-coupled plasma-mass spectrometry (HR-ICP-MS) and thermal ionization mass spectrometry (TIMS), respectively. Lead in surface estuary sediments (10.0-34.2microgg(-1)) and particulate Pb (25.0-128.7microgg(-1), >98% of total Pb) in the water column were significantly higher than levels in natural bedrock soils (15.1+/-8.3microgg(-1)) and river runoff (1.9+/-1.4microgg(-1)). Aquatic plants had Pb concentrations between 2.5 and 7.2microgg(-1), while those in macroalgae ranged from 3 to 5microgg(-1). The ranges of mean Pb concentrations in the aquatic animals studied (ranges in microgg(-1)) were as follows: zooplankton 32+/-3, mussels 2.3-3.9, oysters 1.9-7.9, snail 2.0-7.7, barnacles 0.1-18.5, fish 1.4-8.9, crab 6.3-40.2 and polychaetae 8.5-16.7. Pb values in 20-40% of oyster and fish samples and in all samples of crab exceeded acceptable levels for a food source for human consumption. Pb isotope ratios (206)Pb/(207)Pb, (208)Pb/(207)Pb in biota ranged from 1.188 to 1.206 and 2.448 to 2.470, respectively. A plot of (206)Pb/(207)Pb versus (208)Pb/(207)Pb for the environmental and biological samples collected from two study areas indicates that they contain lead from ores mined in Mexico and used in the past to produce leaded gasoline in use until 1997, natural Pb weathered from the Sierra Madre Occidental mother rock, and the later influence of inputs from a more radiogenic source related to industrial activity in the United States. Statistical software IsoSource results revealed that the Pb contained in environmental matrices and biomonitors is mostly derived from gasoline (20-90%) and US emissions (10-40%).

  6. Probing the Strangeness Content of the Proton and the Neutron Radius of Lead-208 using Parity-Violating Electron Scattering

    NASA Astrophysics Data System (ADS)

    Silwal, Rupesh

    Precision measurement of the parity-violating asymmetry in electron-hadron scattering has been an extremely useful tool to study the structure of the hadrons. This thesis reports work on two such measurements: the measurement of the strange form-factors (FFs), GsE and GsM , by the Hall A Proton Parity Experiment (HAPPEX)-III collaboration, and the first direct measurement of the nucleon skin thickness in a heavy nucleus by the Lead (208Pb) Radius Experiment (PREX) collaboration. In HAPPEX-III, the parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons was measured at an average four-momentum transfer squared, , of 0.624 GeV2. A parity-violating asymmetry, A PV, of -23.80 +/- 0.78(stat) +/- 0.36(syst) parts-per-million (ppm) was measured, which corresponds to a linear combination of the strange FFs, GsE+0.517GsM = 0.003 +/- 0.010(stat) +/- 0.004(syst) +/-0.009(ff). The errors stat and syst are experimental statistical and systematic errors respectively. The error ff arises due to limits on precision of the electromagnetic FFs and radiative corrections. This result is consistent with zero contribution from the strange quarks to the proton FFs. Combined with the existing data on strange FFs, this result constrains the contribution of the strange FFs to the nucleon FFs to a few percent of the nucleon FFs. In PREX, the parity-violating asymmetry in the elastic scattering of polarized electrons from unpolarized 208Pb was measured at an average of 0.0088 GeV2. A parity-violating asymmetry, APV, of 656 +/- 60(stat) +/- 14(syst) parts-per-billion (ppb) was measured, which corresponds to a difference between the neutron and proton distribution radii in the 208Pb nucleus of Rn - R p = 0.33+0.16-0.18 fm. This result is the first electroweak evidence supporting the existence of a neutron skin in a neutron-rich nucleus. One class of systematic uncertainty that both of these experiments were sensitive to is the

  7. Lead Isotopic Source Signatures for Rains and River Waters in Taiwan

    NASA Astrophysics Data System (ADS)

    You, C.; Cheng, M.; Lee, M.; Lin, F.

    2002-12-01

    Lead isotopic compositions and Pb contents in rains and river waters are sensitive proxies for air-pollutant sources and their transport processes. We have collected more than 100 wet precipitations between 1998 and 2001 at Peng-Chia Yu, an offshore island in northern Taiwan, and two other cities, Taichung and Tainan, located at central and southern Taiwan. Additional 14 river waters collected along the Er-Ren-Shi River, Tainan were investigated for systematic comparison. All collected samples were analyzed for major ions (i.e., Cl, Na, Mg, Ca, SO4, NO3 and NH4) by ion chromatography, trace elements and Pb isotopes by ICP-MS (Element II) installed at NCKU. The Peng-Chia Yu rains show large seasonal variation in major ions where Na and Cl are much higher in the winter season. Significant industrial contributions of SO4, NH4 and nsCa are detected at Taichung and Tainan. Trace element results display a more complicated picture, suggesting mixing among seasalt, Asia continental dust, and atmospheric pollutant. These chemical data can be understood in terms of seasonal wind direction changes due to the Asian monsoon system. In winter, the northerly cold wind blow materials with high concentration of anthropogenic input (i.e., Pb and SO4) and dust source (i.e., Al and Ca) from the Asia continent. In contrast, the intertropical convergence zone (ITCZ) migrates northward and caused southwest monsoon prevail in the summer. The 208Pb/207Pb ratio shows consistent seasonal trends as that of Pb contents, possibly a result of mixing between Asia atmospheric sources and seasalt. For the Er-ren Shi River waters, Pb and Pb isotopic compositions vary systematically downstream. Pb concentrations decrease rapidly from 5200 ppt at upstream stations to a value of less than 50 ppt near the estuary whereas 208Pb/207Pb varied between 2.087 and 2.124. The 208Pb/206Pb vs. 1/Pb plot demonstrates a mixing trend between anthropogenic sources and seawater. These results demonstrate that Pb and

  8. Dependence of the Fermi energy upon neutron excess

    NASA Astrophysics Data System (ADS)

    Jeukenne, J.-P.; Mahaux, C.; Sartor, R.

    1991-05-01

    The Fermi energy EF is defined as the negative of the average between the separation energies of a nucleon from the (A+1)- and A-nucleon systems. In the independent-particle limit, EF is the average between the energies of the last occupied and of the first unoccupied shell-model orbits. For mass numbers 40<~A<~208, the experimental neutron Fermi energies EFn increase approximately linearly with increasing asymmetry parameter η=(N-Z)/A. In contrast, the experimental proton Fermi energies EFp are, on the average, nearly independent of η when the average single-particle Coulomb energy EC is subtracted, the quantity EFp-EC decreases linearly with increasing η, with a slope whose modulus differs from that found for EFn. These features are analyzed in the framework of two mean-field models; they both include an isoscalar and an isovector central component, as well as a Coulomb correction in the case of protons. From the comparison between the n-208Pb and p-208Pb mean fields, it is derived that the depth of the symmetry potential is nearly independent of energy in the domain 15<~E<~50 MeV, in close agreement with a recent phenomenological study of the global optical-model potential for nuclei with mass numbers 40<=A<=208. In the vicinity of the Fermi energy, the isoscalar and isovector components are assumed to have Woods-Saxon radial shapes and linearly energy-dependent depths. In both models, the depth of the symmetry potential is taken equal to (23.2-0.46E) MeV. In the first model, all the parameters are extracted from a recent dispersion relation analysis of the mean fields felt by neutrons and protons in 208Pb; then, the calculated neutron Fermi energies are in good agreement with the experimental values but the calculated proton Fermi energies are larger than the experimental values, except for the lead isotopes. The second model incorporates, in addition, information derived from dispersion relation analyses of the n-40Ca and n-90Zr potentials; its main

  9. Cooperative processing of primary miRNAs by DUS16 and DCL3 in the unicellular green alga Chlamydomonas reinhardtii

    PubMed Central

    Cerutti, Heriberto

    2017-01-01

    ABSTRACT We have previously reported that the RNA-binding protein Dull slicer 16 (DUS16) plays a key role in the processing of primary miRNAs (pri-miRNAs) in the unicellular green alga Chlamydomonas reinhardtii. In the present report, we elaborate on the interaction of DUS16 with Dicer-like 3 (DCL3) during pri-miRNA processing. Comprehensive analyses of small RNA libraries derived from mutant and wild-type algal strains allowed the de novo prediction of 35 pri-miRNA genes, including 9 previously unknown ones. The pri-miRNAs dependent on DUS16 for processing largely overlapped with those dependent on DCL3. Our findings suggest that DUS16 and DCL3 work cooperatively, presumably as components of a microprocessor complex, in the processing of the majority of pri-miRNAs in C. reinhardtii. PMID:28289490

  10. Biological Evaluation of Double Point Modified Analogues of 1,25-Dihydroxyvitamin D₂ as Potential Anti-Leukemic Agents.

    PubMed

    Corcoran, Aoife; Nadkarni, Sharmin; Yasuda, Kaori; Sakaki, Toshiyuki; Brown, Geoffrey; Kutner, Andrzej; Marcinkowska, Ewa

    2016-02-01

    Structurally similar double-point modified analogues of 1,25-dihydroxyvitamin D₂ (1,25D₂) were screened in vitro for their pro-differentiating activity against the promyeloid cell line HL60. Their affinities towards human full length vitamin D receptor (VDR) and metabolic stability against human vitamin D 24-hydroxylase (CYP24A1) were also tested. The analogues (PRI-1730, PRI-1731, PRI-1732, PRI-1733 and PRI-1734) contained 5,6-trans modification of the A-ring and of the triene system, additional hydroxyl or unsaturation at C-22 in the side chain and reversed absolute configuration (24-epi) at C-24 of 1,25D₂. As presented in this paper, introduction of selected structural modifications simultaneously in two distinct parts of the vitamin D molecule resulted in a divergent group of analogues. Analogues showed lower VDR affinity in comparison to that of the parent hormones, 1,25D₂ and 1,25D₃, and they caused effective HL60 cell differentiation only at high concentrations of 100 nM and above. Unexpectedly, introducing of a 5,6-trans modification combined with C-22 hydroxyl and 24-epi configuration switched off entirely the cell differentiation activity of the analogue (PRI-1734). However, this analogue remained a moderate substrate for CYP24A1, as it was metabolized at 22%, compared to 35% for 1,25D₂. Other analogues from this series were either less (12% for PRI-1731 and PRI-1733) or more (52% for PRI-1732) resistant to the enzymatic deactivation. Although the inactive analogue PRI-1734 failed to show VDR antagonism, when tested in HL60 cells, its structure might be a good starting point for our design of a vitamin D antagonist.

  11. Biological Evaluation of Double Point Modified Analogues of 1,25-Dihydroxyvitamin D2 as Potential Anti-Leukemic Agents

    PubMed Central

    Corcoran, Aoife; Nadkarni, Sharmin; Yasuda, Kaori; Sakaki, Toshiyuki; Brown, Geoffrey; Kutner, Andrzej; Marcinkowska, Ewa

    2016-01-01

    Structurally similar double-point modified analogues of 1,25-dihydroxyvitamin D2 (1,25D2) were screened in vitro for their pro-differentiating activity against the promyeloid cell line HL60. Their affinities towards human full length vitamin D receptor (VDR) and metabolic stability against human vitamin D 24-hydroxylase (CYP24A1) were also tested. The analogues (PRI-1730, PRI-1731, PRI-1732, PRI-1733 and PRI-1734) contained 5,6-trans modification of the A-ring and of the triene system, additional hydroxyl or unsaturation at C-22 in the side chain and reversed absolute configuration (24-epi) at C-24 of 1,25D2. As presented in this paper, introduction of selected structural modifications simultaneously in two distinct parts of the vitamin D molecule resulted in a divergent group of analogues. Analogues showed lower VDR affinity in comparison to that of the parent hormones, 1,25D2 and 1,25D3, and they caused effective HL60 cell differentiation only at high concentrations of 100 nM and above. Unexpectedly, introducing of a 5,6-trans modification combined with C-22 hydroxyl and 24-epi configuration switched off entirely the cell differentiation activity of the analogue (PRI-1734). However, this analogue remained a moderate substrate for CYP24A1, as it was metabolized at 22%, compared to 35% for 1,25D2. Other analogues from this series were either less (12% for PRI-1731 and PRI-1733) or more (52% for PRI-1732) resistant to the enzymatic deactivation. Although the inactive analogue PRI-1734 failed to show VDR antagonism, when tested in HL60 cells, its structure might be a good starting point for our design of a vitamin D antagonist. PMID:26840307

  12. The Effect of Analogues of 1α,25-Dihydroxyvitamin D₂ on the Regrowth and Gene Expression of Human Colon Cancer Cells Refractory to 5-Fluorouracil.

    PubMed

    Neska, Jacek; Swoboda, Paweł; Przybyszewska, Małgorzata; Kotlarz, Agnieszka; Bolla, Narasimha Rao; Miłoszewska, Joanna; Grygorowicz, Monika Anna; Kutner, Andrzej; Markowicz, Sergiusz

    2016-06-14

    This study aimed to evaluate the capacity of hypocalcemic analogues of 1α,25-dihydroxyvitamin D₂ (1,25D2) and 1α,25-dihydroxyvitamin D₃ (1,25D3) to inhibit regrowth and regulate the stemness-related gene expression in colon cancer cells undergoing renewal after exposure to 5-fluorouracil (5-FU). All of the tested analogues of 1,25D2 equally potently decreased the clonogenicity and the proliferative activity of HT-29 cells which survived the exposure to 5-FU, but differently regulated gene expression of these cells during their renewal. 1,25D2 and analogues (PRI-1907 and PRI-1917), as well as 1,25D3 and analogue PRI-2191, decreased the relative expression level of several stemness-related genes, such as NANOG, OCT3/4, PROM1, SOX2, ALDHA1, CXCR4, in HT-29/5-FU cells during their renewal, in comparison to untreated HT-29/5-FU cells. The other 1,25D2 analogues (PRI-1906 and PRI-1916) were not capable of downregulating the expression of these stemness-related genes as the analogues PRI-1907 and PRI-1917 did. All of the tested vitamin D analogues upregulated CDH1, the gene encoding E-cadherin associated with epithelial phenotype. Out of the series of analogues studied, side-chain branched analogues of 1,25D2 (PRI-1907, PRI-1917) and the analogue of 1,25D3 (PRI-2191) might be used to target cancer cells with stem-like phenotypes that survive conventional chemotherapy.

  13. Dynamics of spectral bio-indicators and their correlations with light use efficiency using directional observations at a Douglas-fir forest

    NASA Astrophysics Data System (ADS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Hilker, Thomas; Coops, Nicholas C.; Black, T. Andrew; Krishnan, Praveena

    2009-09-01

    The carbon science community must rely on satellite remote sensing to obtain global estimates of photosynthetic activity, typically expressed as net primary production (NPP), gross primary production (GPP) or light use efficiency (LUE). The photochemical reflectance index (PRI), calculated as a normalized difference reflectance index using a physiologically active green band (~531 nm) and another physiologically insensitive green reference band (~570 nm), denoted as PRI(570), has been confirmed in many studies as being strongly related to LUE. Here, we examined the potential of utilizing PRI(570) observations under different illumination conditions for canopy LUE estimation of a forest. In order to evaluate this, directional hyperspectral reflectance measurements were collected continuously throughout the daytime periods using an automated spectroradiometer in conjunction with tower-based eddy covariance fluxes and environmental measurements at a coastal conifer forest in British Columbia, Canada throughout the 2006 growing season. A parameter calculated as the PRI(570) difference (dPRI(570)) between shaded versus sunlit canopy foliage sectors showed a strong correlation to tower-based LUE. The seasonal pattern for this correlation produced a dramatic change from high negative (r ~ -0.80) values in the springtime and early fall to high positive values (r ~ 0.80) during the summer months, which could represent the seasonality of physiological characteristics and environmental factors. Although the PRI(570) successfully tracked canopy LUE, one or both of its green bands (~531 and 570 nm) used to calculate the PRI are unavailable on most existing and planned near-term satellites. Therefore, we examined the potential to use 24 other spectral indexes for LUE monitoring that might be correlated to PRI, and thereby a substitute for it. We also continued our previous investigations into the influence of illumination conditions on the observed PRI(570) and other indexes

  14. Momentum sharing in imbalanced Fermi systems

    DOE PAGES

    Hen, O.; Sargsian, M.; Weinstein, L. B.; ...

    2014-10-16

    The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron starsmore » and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.« less

  15. Load following capability of CANDLE reactor by adjusting coolant operation condition

    NASA Astrophysics Data System (ADS)

    Sekimoto, Hiroshi; Nakayama, Sinsuke

    2012-06-01

    The load following capability of CANDLE reactor is investigated in the condition that the control rods are unavailable. Both sodium cooled metallic fuel fast reactor (SFR) and 208Pb cooled metallic fuel fast reactor (LFR) are investigated for their performance in power rate changing by changing its coolant operation condition; either coolant flow rate or coolant inlet temperature. The change by coolant flow rate is difficult especially for SFR because the maximum temperature criteria on cladding material may be violated. The power rate can be changed for its full range easily by changing the coolant temperature at the core inlet. LFR can reduce the same amount of power rate by smaller change of temperature than SFR. However, the coolant output temperature is generally decreased for this method and the thermal efficiency becomes worse.

  16. Louisville seamount subduction and its implication on mantle flow beneath the central Tonga-Kermadec arc

    NASA Astrophysics Data System (ADS)

    Timm, Christian; Bassett, Daniel; Graham, Ian J.; Leybourne, Matthew I.; de Ronde, Cornel E. J.; Woodhead, Jon; Layton-Matthews, Daniel; Watts, Anthony B.

    2013-04-01

    Subduction of intraplate seamounts beneath a geochemically depleted mantle wedge provides a seldom opportunity to trace element recycling and mantle flow in subduction zones. Here we present trace element and Sr, Nd and Pb isotopic compositions of lavas from the central Tonga-Kermadec arc, west of the contemporary Louisville-Tonga trench intersection, to provide new insights into the effects of Louisville seamount subduction. Elevated 206Pb/204Pb, 208Pb/204Pb, 86Sr/87Sr in lavas from the central Tonga-Kermadec arc front are consistent with localized input of subducted alkaline Louisville material (lavas and volcaniclastics) into sub-arc partial melts. Furthermore, absolute Pacific Plate motion models indicate an anticlockwise rotation in the subducted Louisville seamount chain that, combined with estimates of the timing of fluid release from the subducting slab, suggests primarily trench-normal mantle flow beneath the central Tonga-Kermadec arc system.

  17. Dirac Calculations for Proton Inelastic Scattering at Intermediate Energies

    NASA Astrophysics Data System (ADS)

    El-Nohy, N. A.; El-Hammamy, M. N.; Aly, N. E.; Abdel-Moneim, A. M.; Hamza, A. F.

    2016-12-01

    Relativistic proton inelastic scattering from different targets (16O, 24Mg, 28Si, 40Ca, 54Fe, 58Ni, 90Zr, 154Sm, 176Yb, and 208Pb) at intermediate energies is analyzed in the framework of phenomenological optical potentials based on the Dirac formalism. Parameters of the Dirac phenomenological potential with Woods Saxon (WS) shape are obtained. The first order vibrational collective model with one phonon is used to calculate the transition optical potentials to the first low-lying excited state (2+) of the investigated target nuclei. Also, the variation of deformation length ( δ) with energy and mass number is studied. It is noticed that the deformation length increases slightly with energy at intermediate range.

  18. High-spin octupole yrast levels in {sup 216}Rn{sub 86}

    SciTech Connect

    Debray, M.E.; Davidson, J.; Davidson, M.; Kreiner, A. J.; Cardona, M. A.; Hojman, D.; Napoli, D.R.; De Angelis, G.; De Poli, M.; Gadea, A.; Lenzi, S.; Bazzacco, D.; Lunardi, S.; Rossi-Alvarez, C.; Ur, C.A.; Medina, N.

    2006-02-15

    The yrast level structure of {sup 216}Rn has been studied using in-beam spectroscopy {alpha}-{gamma}-{gamma} coincidence techniques through the {sup 208}Pb({sup 18}O, 2{alpha}2n) reaction in the 91-93 MeV energy range, using the 8{pi} GASP-ISIS spectrometer at Legnaro. The level scheme of {sup 216}Rn resulting from this study shows alternating parity bands only above a certain excitation energy. From this result, the lightest nucleus showing evidence of octupole collectivity at low spins is still {sup 216}Fr, thereby defining the lowest-mass corner for this kind of phenomenon as N{>=}129 and Z{>=}87.

  19. Near yrast states in doubly odd [sup 214]Fr

    SciTech Connect

    Debray, M.E.; Kreiner, A.J.; Kesque, J.M.; Ozafran, M.; Romo, A.; Somacal, H.; Vazquez, M.E. ); Davidson, J.; Davidson, M. ); Ahn, K.; Fossan, D.B.; Liang, Y.; Ma, R.; Paul, E.S.; Piel, W.F. Jr.; Xu, N. )

    1993-11-01

    High spin states of doubly odd [sup 214]Fr[sub 127] have been investigated using in-beam [gamma]-ray and conversion electron spectroscopy techniques through the [sup 206]Pb([sup 11]B, 3[ital n]) and [sup 208]Pb([sup 11]B, 5[ital n]) fusion-evaporation reactions. Completely new spectrocopic information has been obtained. The yrast level structure is established up to spin (19[sup +]) and some information on [gamma] transitions from higher-lying levels is also obtained. Two new isomers [ital T][sub 1/2]=174(20) ns and [ital T][sub 1/2]=11(2) ns were found. Configuration assignments for the low-lying levels are discussed. Information on residual proton-neutron interactions is extracted.

  20. Level structure of /sup 215/Fr

    SciTech Connect

    Drigert, M.W.; Cizewski, J.A.; Rosenthal, M.S.

    1985-07-01

    The structure of /sup 215/Fr has been studied via the /sup 208/Pb (/sup 11/B, 4n..gamma..)/sup 215/Fr reaction at beam energies from 45 to 66 MeV. In-beam ..gamma..-ray spectroscopy techniques, including ..gamma..-ray excitation function, x-ray-..gamma.. coincidence, ..gamma..-..gamma.. coincidence, ..gamma..-ray angular distribution, and ..gamma..-ray linear polarization measurements were used to construct a level scheme up to a spin value J = (41/2) at an excitation energy of 3405 keV. Definite parity assignments were made up to the (39/2)/sup -/ state. The structure of this nucleus is compared with that observed in the other N = 128 isotopes and predictions of shell model calculations.

  1. Density slope of the symmetry energy L (ρ0) constrained by proton radioactivity

    NASA Astrophysics Data System (ADS)

    Wan, Niu; Xu, Chang; Ren, Zhongzhou

    2016-10-01

    Background: Recently, the cluster radioactivity of heavy nuclei decaying to 208Pb was successfully used to constrain the density slope of the symmetry energy L (ρ0) at saturation density ρ0. Purpose: By using well-measured experimental decay energy and half-life, proton radioactivity is proposed to further constrain L (ρ0) in this work. Method: From the Hugenholtz-Van Hove theorem, L (ρ0) is found to be directly related to the magnitude of the symmetry potential, which can be extracted from the proton radioactivity within the density-dependent cluster model. Results: By investigating the radioactivity of proton emitters with large isospin asymmetry, the value of the density slope is found to be L (ρ0)=51.8 ±7.2 MeV.

  2. Grafting of acrylic acid on etched latent tracks induced by swift heavy ions on polypropylene films

    NASA Astrophysics Data System (ADS)

    Mazzei, R.; Fernández, A.; García Bermúdez, G.; Torres, A.; Gutierrez, M. C.; Magni, M.; Celma, G.; Tadey, D.

    2008-06-01

    In order to continue with a systematic study that include different polymers and monomers, the residual active sites produced by heavy ion beams, that remain after the etching process, were used to start the grafting process. To produce tracks, foils of polypropylene (PP) were irradiated with 208Pb of 25.62 MeV/n. Then, these were etched and grafted with acrylic acid (AA) monomers. Experimental curves of grafting yield as a function of grafting time with the etching time as a parameter were measured. Also, the grating yield as a function of the fluence and etching time was obtained. In addition, the permeation of solutions, with different pH, through PP grafted foils was measured.

  3. Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

    USGS Publications Warehouse

    Stern, C.R.; Frey, F.A.; Futa, K.; Zartman, R.E.; Peng, Z.; Kurtis, Kyser T.

    1990-01-01

    The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc

  4. Baseline metals pollution profile of tropical estuaries and coastal waters of the Straits of Malacca.

    PubMed

    Looi, Ley Juen; Aris, Ahmad Zaharin; Wan Johari, Wan Lutfi; Md Yusoff, Fatimah; Hashim, Zailina

    2013-09-15

    The status report on metal pollution in tropical estuaries and coastal waters is important to understand potential environmental health hazards. Detailed baseline measurements were made on physicochemical parameters (pH, temperature, redox potential, electrical conductivity, salinity, dissolved oxygen, total dissolved solid), major ions (Na, Ca, Mg, K, HCO3, Cl, SO4 and NO3) and metals concentrations ((27)Al, (75)As, (138)Ba, (9)Be, (111)Cd, (59)Co, (63)Cu, (52)Cr, (57)Fe, (55)Mn, (60)Ni, (208)Pb, (80)Se, (66)Zn) at estuaries and coastal waters along the Straits of Malacca. Principal component analysis (PCA) was employed to reveal potential pollution sources. Seven principal components were extracted with relation to pollution contribution from minerals-related parameters, natural and anthropogenic sources. The output from this study will generate a profound understanding on the metal pollution status and pollution risk of the estuaries and coastal system.

  5. Levels and source apportionment of children's lead exposure: could urinary lead be used to identify the levels and sources of children's lead pollution?

    PubMed

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-04-01

    As a highly toxic heavy metal, the pollution and exposure risks of lead are of widespread concern for human health. However, the collection of blood samples for use as an indicator of lead pollution is not always feasible in most cohort or longitudinal studies, especially those involving children health. To evaluate the potential use of urinary lead as an indicator of exposure levels and source apportionment, accompanying with environmental media samples, lead concentrations and isotopic measurements (expressed as (207)Pb/(206)Pb, (208)Pb/(206)Pb and (204)Pb/(206)Pb) were investigated and compared between blood and urine from children living in the vicinities of a typical coking plant and lead-acid battery factory. The results showed urinary lead might not be a preferable proxy for estimating blood lead levels. Fortunately, urinary lead isotopic measurements could be used as an alternative for identifying the sources of children's lead exposure, which coincided well with the blood lead isotope ratio analysis.

  6. Isotopic composition of Pb in ore deposits of the Betic Cordillera, Spain; origin and relationship to other European deposits

    USGS Publications Warehouse

    Arribas , Antonio; Tosdal, Richard M.

    1994-01-01

    The Betic Cordillera in southern Spain is a complex Alpine fold belt that resulted from the Cretaceous through Cenozoic collision of Africa with Europe. The region is illustrative of one of the characteristics of the Alpine-Mediterranean orogen: the occurrence over a limited area of mineral deposits with a wide variety of host rocks, mineralization ages, and styles. The metamorphic basement in the Betic zone is characterized by a nappe structure of superimposed tectonostratigraphic units and consists of lower Paleozoic to Lower Triassic clastic metasedimentary rocks. This is overlain by Middle to Upper Triassic platform carbonate rocks with abundant strata-bound F-Pb-Zn-(Ba) deposits (e.g., Sierra de Gador, Sierra Alhamilla). Cretaceous to Paleogene subduction-related compression in southeastern Spain was followed by Miocene postcollisional extension and resulted in the formation of the Almeria-Cartagena volcanic belt and widespread hydrothermal activity and associated polymetallic mineralization. Typical Miocene hydrothermal deposits include volcanic-hosted Au (e.g., Rodalquilar) and Ag-rich base metal (e.g., Cabo de Gata, Mazarron) deposits as well as complex polymetallic veins, mantos, and irregular replacement bodies which are hosted by Paleozoic and Mesozoic metamorphic rocks and Neogene sedimentary and volcanic rocks (e.g., Cartagena, Sierra Almagrera, Sierra del Aguilon, Loma de Bas).Lead isotope compositions were measured on sulfide samples from nine ore districts and from representative fresh samples of volcanic and basement rock types of the region. The results have been used to evaluate ore-forming processes in southeastern Spain with emphasis on the sources of metals. During a Late Triassic mineralizing event, Pb was leached from Paleozoic clastic metasedimentary rocks and incorporated in galena in strata-bound F-Pb-Zn-(Ba) deposits ( 206 Pb/ 204 Pb = 18.332 + or - 12, 207Pb/ 204 Pb = 15.672 + or - 12, 208 Pb/ 204 Pb = 38.523 + or - 46). The second

  7. Deep Sub-Barrier Fusion Enhancement in the {sup 6}He+{sup 206}Pb Reaction

    SciTech Connect

    Penionzhkevich, Yu.E.; Zagrebaev, V.I.; Lukyanov, S.M.; Kalpakchieva, R.

    2006-04-28

    The fusion of {sup 6}He with {sup 206}Pb has been studied at energies close to and below the Coulomb barrier. The experiment was carried out at the Dubna Radioactive Ion Beams complex of FLNR, JINR. The {sup 6}He beam intensity was about 5x10{sup 6} pps, the maximum energy being 60.3{+-}0.4 MeV. The yield of the {sup 210}Po isotope, produced in the 2n-evaporation channel, demonstrates an extremely large enhancement of the sub-barrier fusion cross section as compared with the {sup 4}He+{sup 208}Pb reaction. This enhancement is most likely due to the mechanism of 'sequential fusion' with an intermediate neutron transfer from {sup 6}He to the Pb nucleus with positive Q values.

  8. High-spin states in the five-valence-particle nucleus {sup 213}Po

    SciTech Connect

    Astier, Alain; Porquet, Marie-Genevieve

    2011-03-15

    Excited states in {sup 213}Po have been populated using the {sup 18}O+ {sup 208}Pb reaction at 85 MeV beam energy and studied with the Euroball IV {gamma} multidetector array. The level scheme has been built up to {approx}2.0 MeV excitation energy and spin I{approx}25/2({h_bar}/2{pi}) from the triple {gamma} coincidence data. Spin and parity values of several yrast states have been assigned from the {gamma} angular properties. The configurations of the yrast states are discussed using results of empirical shell-model calculations and by analogy with the neighboring nuclei. The spin and parity values of several low-spin states of {sup 213}Po previously identified from the {beta} decay of {sup 213}Bi are revised.

  9. Leading twist nuclear shadowing, nuclear generalized parton distributions and nuclear DVCS at small x

    SciTech Connect

    Guzey, Vadim; Goeke, Klaus; Siddikov, Marat

    2009-01-01

    We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact parameter dependent nuclear parton distributions (PDFs). Nuclear shadowing induces non-trivial correlations between the impact parameter $b$ and the light-cone fraction $x$. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on $^{208}$Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issue of the extraction of the DVCS signal from the $e A \\to e \\gamma A$ cross section. We find that the $e A \\to e \\gamma A$ differential cross section is dominated by DVCS at the momentum transfer $t$ near the minima of the nuclear form factor. We also find that nuclear shadowing leads

  10. First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in the {sup 244}Pu({sup 48}Ca,3-4n) reaction

    SciTech Connect

    Gates, J. M.; Duellmann, Ch. E.; Schaedel, M.; Ackermann, D.; Block, M.; Bruechle, W.; Essel, H. G.; Hartmann, W.; Hessberger, F. P.; Huebner, A.; Jaeger, E.; Khuyagbaatar, J.; Kindler, B.; Krier, J.; Kurz, N.; Lommel, B.; Schaffner, H.; Schausten, B.; Schimpf, E.; Steiner, J.

    2011-05-15

    Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of {sup 48}Ca to irradiate targets of {sup 206-208}Pb, which led to the production of {sup 252-254}No isotopes. These studies allowed for evaluation of the performance of TASCA when coupled to a new detector and electronics system. By following these studies, the isotopes of element 114 ({sup 288-291}114) were produced in irradiations of {sup 244}Pu targets with {sup 48}Ca beams at compound nucleus excitation energies around 41.7 and 37.5 MeV, demonstrating TASCA's ability to perform experiments with picobarn-level cross sections. A total of 15 decay chains were observed and were assigned to the decay of {sup 288-291}114. A new {alpha}-decay branch in {sup 281}Ds was observed, leading to the new nucleus {sup 277}Hs.

  11. Systematics of binding energies and radii based on realistic two-nucleon plus phenomenological three-nucleon interactions

    SciTech Connect

    Guenther, A.; Roth, R.; Reinhardt, S.; Hergert, H.

    2010-08-15

    We investigate the influence of phenomenological three-nucleon interactions on the systematics of ground-state energies and charge radii throughout the whole nuclear mass range from {sup 4}He to {sup 208}Pb. The three-nucleon interactions supplement unitarily transformed two-body interactions constructed within the unitary correlation operator method or the similarity renormalization group approach. To be able to address heavy nuclei as well, we treat the many-body problem in Hartree-Fock plus many-body perturbation theory, which is sufficient to assess the systematics of energies and radii, and limit ourselves to regularized three-body contact interactions. We show that even with such a simplistic three-nucleon interaction a simultaneous reproduction of the experimental ground-state energies and charge radii can be achieved, which is not possible with unitarily transformed two-body interactions alone.

  12. Anthropogenic and natural lead isotopes in Fe-hydroxides and Fe-sulphates in a watershed associated with arsenic-enriched groundwater, Maine, USA

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.

    2008-01-01

    A survey of the natural and anthropogenic sources of lead contributing to secondary minerals in sulphidic schists associated with arsenic-enriched groundwater in Coastal Maine shows that the most likely source is natural Pb, particularly from coexisting sulphide minerals. The secondary minerals also reflect notable contributions from anthropogenic Pb. The Pb isotopes establish pathways by which Pb, and by inference As, could have been transported from As-bearing minerals (arsenian pyrite, arsenopyrite, lollingite, orpiment, arsenic oxide and others), via sulphide oxidation or carbonation reactions into multiple generations of secondary minerals (goethite, hematite, jarosite, natrojarosite and others). Lead isotopic compositions of the sulphides and secondary minerals determined by thermal ionization mass spectrometry (n=53) range widely. Lead and As contents of the sulphides and secondary minerals overlap, and are generally positively correlated. Pyrite, the dominant sulphide in sulphidic schists associated with As-enriched groundwater in Coastal Maine, has values of 206Pb/204Pb from 18.186 to 18.391, 207Pb/204Pb from 15.617 to 15.657, 208Pb/204Pb from 38.052 to 38.210, 206Pb/207Pb from c. 1.1625 to 1.1760 and 208Pb/207Pb from c. 2.4276 to 2.4394. Mixtures of Fe-hydroxide and oxide minerals (predominantly goethite and hematite) and secondary Fe-sulphate minerals (jarosite, natrojarosite, rozenite and melanterite) in the sulphidic schists have overlapping but generally higher values of 206Pb/204Pb from 18.495 to 19.747 (one sample at 21.495), 207Pb/204Pb from 15.595 to 15.722 (one sample at 15.839), 208Pb/204Pb from 38.186 to 39.162,206Pb/207Pb from c.1.1860 to 1.2575 (one sample at 1.3855) and 208Pb/207Pb from c. 2.4441 to 2.4865 than the sulphides. Sulphides from Zn-Pb metal mines are somewhat less radiogenic than sulphides from the schists. Other sulphides (mostly pyrite) associated with pegmatites and granitic rocks are heterogeneous and more

  13. Impact of submersible pumps on Pb constituents in residential wells.

    PubMed

    Sidle, W C; Li, P

    2008-02-01

    Dissolved Pb in 51 domestic wells screened from 18 to 48 m in glacial tills and outwash deposits were examined in conjunction with the characteristics of their corresponding submersible pump. Pb concentrations, ranging from 0.8 to 24.9 microg l(-1), entering residential water supplies were measured during 2001-2004 in the Royal watershed, Maine. Principal component analyses assisted the weighting of pump age, well screen depth, and draw time variables. Preliminary Pb sequestration significance in the boreholes was predicted from geochemical speciation and synchrotron XAS analyses. Nascent 207Pb/206Pb and 208Pb/206Pb isotope analyses assisted the discrimination of possibly leached Pb from submersible pump materials among geogenic sources.

  14. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    NASA Technical Reports Server (NTRS)

    Hegner, E.; Tatsumoto, M.

    1987-01-01

    Isotopic Pb, Sr, and Nd data were collected by the Alvin submersible from seven basalt glasses in the southern Juan de Fuca Ridge (JFR), giving similar ratios for Pb-206/Pb-204 of about 18.45, for Pb-207/Pb-204 of about 15.47, for Pb-208/Pb-204 of about 37.81, for Sr-87/Sr-86 of about 0.70249, and for Nd-143/Nd-144 of about 0.51315. Data suggest that the basalts are all cogenetic, and that four of the samples are also comagmatic. It is concluded that isotopic data for the JFR and seamount basalts provide additional support for the mantle blob cluster model (Allegre et al., 1984), suggesting the involvement of multiple components in the genesis of ridge basalts, and including an unusual end-member that has nonradiogenic Sr and variable Pb-206/Pb-204 isotopic compositions.

  15. Theory of photon and electron induced reactions. Final report, July 1, 1990--June 30, 1993

    SciTech Connect

    Onley, D.S.; Wright, L.E.

    1993-01-01

    Theoretical work is reported on the following topics: photo- and electroproduction of mesons by the ({gamma},{pi}{sup {minus}}p) reactions on {sup 12}C and {sup 16}O; Coulomb distortion effects on (e,e{prime}{gamma}) and on inclusive (e,e{prime}) and exclusive (e,e{prime}p) scattering in the quasi-elastic region for {sup 40}Ca, {sup 208}Pb, and {sup 238}U; relativistic structure calculations in which the basic lagrangian is an extension of the {sigma}{endash}{omega} model in which the nucleons are coupled to five fields ({sigma}, {omega}, {rho}, {pi}, the electromagnetic field) and tensor coupling to the vector mesons {rho} and {omega} is also considered; and an investigation of the interaction {gamma} + p {yields} K{sup +} + {Lambda}{sup 0} in a simple quark model that supplies the coupling constants and form factors associated with each vertex in the Feynman diagrams. 19 figs., 51 refs.

  16. Reaction dynamics induced by the radioactive ion beam {sup 7}Be on medium-mass and heavy targets

    SciTech Connect

    Mazzocco, M. Stefanini, C.; Strano, E.; Torresi, D.; Lay, J. A.; Molini, P.; Soramel, F.; Boiano, A.; Parascandolo, C.; Pierroutsakou, D.; Di Meo, P.; Boiano, C.; La Commara, M.; Sandoli, M.; Silvestri, R.; Manea, C.; Nicoletto, M.; Acosta, L.; Fernandez-Garcia, J. P.; Glodariu, T.; and others

    2015-10-15

    We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam {sup 7}Be (S{sub α} = 1.586 MeV) on medium-mass ({sup 58}Ni) and heavy ({sup 208}Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×10{sup 5} pps {sup 7}Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.

  17. Appraisal of the Kuo-Herling shell-model interaction and application to A =210--212 nuclei

    SciTech Connect

    Warburton, E.K. ); Brown, B.A. )

    1991-02-01

    Shell-model calculations are described for {ital A}=204--212 nuclei. These calculations use the Kuo-Herling realistic effective interactions for hole states and particle states relative to {sup 208}Pb. These interactions contain a bare part and a core-polarization contribution. The contribution of the core polarization was varied to find the best fit to the energy spectra of {ital A}=204--206 and 210--212 nuclei. This and other modifications to the Kuo-Herling interaction---designed to give better agreement with experimental energy spectra---are discussed. Aspects of the spectroscopy of {sup 211{minus}212}Pb, {sup 210}Po, {sup 212}Ra, {sup 210}Bi, and {sup 212}At are presented in order to illustrate the use of the Kuo-Herling particle interaction. Deficiencies in the Kuo-Herling interaction are described and the desirability and possibility of an improved calculation of the interaction is emphasized.

  18. Redox heterogeneity in mid-ocean ridge basalts as a function of mantle source.

    PubMed

    Cottrell, Elizabeth; Kelley, Katherine A

    2013-06-14

    The oxidation state of Earth's upper mantle both influences and records mantle evolution, but systematic fine-scale variations in upper mantle oxidation state have not previously been recognized in mantle-derived lavas from mid-ocean ridges. Through a global survey of mid-ocean ridge basalt glasses, we show that mantle oxidation state varies systematically as a function of mantle source composition. Negative correlations between Fe(3+)/ΣFe ratios and indices of mantle enrichment--such as (87)Sr/(86)Sr, (208)Pb/(204)Pb, Ba/La, and Nb/Zr ratios--reveal that enriched mantle is more reduced than depleted mantle. Because carbon may act to simultaneously reduce iron and generate melts that share geochemical traits with our reduced samples, we propose that carbon creates magmas at ridges that are reduced and enriched.

  19. Four-body continuum-discretized coupled-channels calculations using a transformed harmonic oscillator basis

    SciTech Connect

    Rodriguez-Gallardo, M.; Arias, J. M.; Gomez-Camacho, J.; Moro, A. M.; Johnson, R. C.; Tostevin, J. A.; Thompson, I. J.

    2008-06-15

    The scattering of a weakly bound three-body system by a target is discussed. A transformed harmonic oscillator basis is used to provide an appropriate discrete and finite basis for treating the continuum part of the spectrum of the projectile. The continuum-discretized coupled-channels framework is used for the scattering calculations. The formalism is applied to different reactions, {sup 6}He+{sup 12}C at 229.8 MeV, {sup 6}He+{sup 64}Zn at 10 and 13.6 MeV, and {sup 6}He+{sup 208}Pb at 22 MeV, induced by the Borromean nucleus {sup 6}He. Both the Coulomb and nuclear interactions with a target are taken into account.

  20. Analytical transformed harmonic oscillator basis for continuum discretized coupled channels calculations

    SciTech Connect

    Moro, A. M.; Arias, J. M.; Gomez-Camacho, J.; Perez-Bernal, F.

    2009-11-15

    A new method for continuum discretization in continuum-discretized coupled-channels calculations is proposed. The method is based on an analytic local-scale transformation of the harmonic-oscillator wave functions proposed for other purposes in a recent work [Karatagladis et al., Phys. Rev. C 71, 064601 (2005)]. The new approach is compared with the standard method of continuum discretization in terms of energy bins for the reactions d+{sup 58}Ni at 80 MeV, {sup 6}Li+{sup 40}Ca at 156 MeV, and {sup 6}He+{sup 208}Pb at 22 MeV and 240 MeV/nucleon. In all cases very good agreement between both approaches is found.

  1. Exploring continuum structures with a pseudo-state basis

    SciTech Connect

    Lay, J. A.; Moro, A. M.; Arias, J. M.; Gomez-Camacho, J.

    2010-08-15

    The ability of a recently developed square-integrable discrete basis to represent the properties of the continuum of a two-body system is investigated. The basis is obtained performing a simple analytic local scale transformation to the harmonic oscillator basis. Scattering phase-shifts and the electric transition probabilities B(E1) and B(E2) have been evaluated for several potentials using the proposed basis. Both quantities are found to be in excellent agreement with the exact values calculated from the true scattering states. The basis has been applied to describe the projectile continuum in the {sup 6}He scattering by {sup 12}C and {sup 208}Pb targets at 240 MeV/nucleon and the {sup 11}Be scattering by {sup 12}C at 67 MeV/nucleon. The calculated breakup differential cross sections are found to be in very good agreement with the available experimental data for these reactions.

  2. Four-body continuum-discretized coupled-channels calculations

    SciTech Connect

    Rodriguez-Gallardo, M.; Arias, J. M.; Moro, A. M.; Gomez-Camacho, J.; Thompson, I. J.; Tostevin, J. A.

    2009-11-15

    The development of a continuum-bin scheme of discretization for three-body projectiles is necessary for studies of reactions of Borromean nuclei such as {sup 6}He within the continuum-discretized coupled-channels approach. Such a procedure, for constructing bin states on selected continuum energy intervals, is formulated and applied for the first time to reactions of a three-body projectile. The continuum representation uses the eigenchannel expansion of the three-body S matrix. The method is applied to the challenging case of the {sup 6}He+{sup 208}Pb reaction at 22 MeV, where an accurate treatment of both the Coulomb and the nuclear interactions with the target is necessary.

  3. The {sup 6}He Optical Potential at energies around the Coulomb barrier

    SciTech Connect

    Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-26

    We present an Optical Model (OM) study of {sup 6}He on {sup 208}Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (E{sub lab} = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the alpha channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the alpha particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  4. Search for magnetic dipole strength and giant spin-flip resonances in heavy nuclei. [120 to 200 MeV

    SciTech Connect

    Horen, D J

    1980-01-01

    A description is given of the use of high-resolution (n,n) scattering and the (p,n) reaction as tools to investigate highly excited states, with emphasis on information pertaining to magnetic dipole strength and giant spin-flip resonances in heavy nuclei. It is shown how the ability to determine uniquely the spins and parities of resonances observed in neutron scattering has been instrumental to an understanding of the distribution of M1 strength in /sup 207/ /sup 208/Pb. Some recent results of (p,n) studies with intermediate energy protons are discussed. Energy systematics of the giant Gamow-Teller (GT) resonance as well as new ..delta..l = ..delta..S = 1 resonance with J/sup ..pi../ = (1,2)/sup -/ are presented. It is shown how the (p,n) reaction might be useful in locating M1 strength in heavy nuclei. 20 figures.

  5. Decay Study of {sup 257}Rf

    SciTech Connect

    Qian, J.; Heinz, A.; Winkler, R.; Janssens, R. V. F.; Khoo, T. L.; Seweryniak, D.; Peterson, D.; Back, B. B.; Carpenter, M. P.; Greene, J. P.; Jiang, C. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Pardo, R. C.; Robinson, A.; Scott, R.; Vondrasek, R.; Wang, X.; Zhu, S.

    2009-03-04

    The isotope {sup 257}Rf was produced in the fusion-evaporation reaction {sup 208}Pb({sup 50}Ti, n){sup 257}Rf. Reaction products were separated by the Argonne Fragment Mass Analyzer. Radioactive decay and spontaneous fission of {sup 257}Rf and its decay products were investigated. An isomeric state in {sup 257}Rf, with a half-life of 160{sub -31}{sup 42} {mu}S, was discovered by detecting internal conversion electrons followed by alpha decays. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal-conversion electrons which were succeeded by alpha decay, with a half-life of 4.1{sub -1.3}{sup +2.4} s, was observed. These events might originate from the decay of excited states in {sup 257}Lr, populated by electron-capture decay of {sup 257}Rf, or from another isomer in {sup 257}Rf.

  6. New description of the four-body breakup reaction

    SciTech Connect

    Matsumoto, Takuma; Kato, Kiyoshi; Yahiro, Masanobu

    2010-11-15

    We present a novel method of smoothing discrete breakup cross sections calculated by the method of continuum-discretized coupled channels. The smoothing method based on the complex scaling method is tested with success for a {sup 58}Ni(d,pn) reaction at 80 MeV as an example of three-body breakup reactions and applied to a {sup 12}C({sup 6}He,nn {sup 4}He) reaction at 229.8 MeV as an example of four-body breakup reactions. Fast convergence of the breakup cross section with respect to extending the model space is confirmed. The method is also applied to {sup 12}C({sup 6}He,nn {sup 4}He) and {sup 208}Pb({sup 6}He,nn {sup 4}He) reactions at 240 MeV/A and compared with the experimental data.

  7. Analysis of fission-fragment mass distribution within the quantum-mechanical fragmentation theory

    NASA Astrophysics Data System (ADS)

    Singh, Pardeep; Kaur, Harjeet

    2016-11-01

    The fission-fragment mass distribution is analysed for the 208Pb(18O, f) reaction within the quantum-mechanical fragmentation theory (QMFT). The reaction potential has been calculated by taking the binding energies, Coulomb potential and proximity potential of all possible decay channels and a stationary Schrödinger equation has been solved numerically to calculate the fission-fragment yield. The overall results for mass distribution are compared with those obtained in experiment. Fine structure dips in yield, corresponding to fragment shell closures at Z = 50 and N=82, which are observed by Bogachev et al., are reproduced successfully in the present calculations. These calculations will help to estimate the formation probabilities of fission fragments and to understand many related phenomena occurring in the fission process.

  8. Angular momentum effects in multimodal fission of 226Th

    NASA Astrophysics Data System (ADS)

    Chubarian, G. G.; Hurst, B. J.; O'Kelly, D.; Schmitt, R. P.; Itkis, M. G.; Kondratiev, N. A.; Kozulin, E. M.; Oganessian, Yu. Ts.; Pashkevich, V. V.; Pokrovsky, I. V.; Salamatin, V. S.; Rusanov, A. Ya.; Calabretta, L.; Maiolino, C.; Lukashin, K.; Agodi, C.; Bellia, G.; Hanappe, F.; Liatard, E.; Huck, A.; Stuttgé, L.

    1998-12-01

    The γ-rays from the multimodal fission of the 226Th formed in 18O+208Pb was investigated at the near- and sub-barrier energies. The corresponding excitation energies at the saddle point, Esp*, ranged from 23 to 26 MeV. The average γ-ray multiplicities and relative γ-ray energies as a function of the mass of the fission fragments exhibits a complex structure and strong variations. Such strong variations have never been previously observed in heavy ion-induced fusion-fission reactions. Obtained results may be explained with the influence of shell effects on the properties of the fission fragments. Present work is the one in series of investigation of the multimodal fission phenomena in At-Th region.

  9. New Isotope 263Hs

    SciTech Connect

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  10. Elastic Cross Sections for Positive and Negative Pions at 400 and 500 Mev, with CARBON-12, CALCIUM-40, Zirconium -90, or LEAD-208: Measurements and Interpretations.

    NASA Astrophysics Data System (ADS)

    Kahrimanis, George Peter

    1995-01-01

    Pion-nucleus scattering at energies above the Delta(1232) resonance has been studied intensively using both pi^+ and pi^- beams on ^{12}C, ^{40}Ca, ^{90}Zr, and ^{208}Pb. The present data provide an opportunity to study the interaction of pions with nuclei at energies above the Delta(1232), where conventional second-order corrections should be small. The results are compared with other data sets at similar energies, and with four theoretical calculations: one employing a momentum-space microscopic optical model, another in the eikonal approach, an application of the Kemmer-Duffin-Petiau wave equation with the Relativistic Impulse Approximation, and one based on the Non-Relativistic Impulse Approximation. The comparisons show certain persistent features, such as a smaller effective radius of strong absorption than in the region of the Delta(1232), as expected, but still larger than these calculations predict.

  11. Analyzing Powers and Cross Sections of Inclusive Polarized Proton Scattering on LEAD-208.

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-Yan

    Inclusive polarized proton-nucleus scattering at 290 and 500 MeV was performed using a ^ {208}Pb(51 mg/cm^2) target. A broad range (0-250 MeV) of excitation energy has been studied over the 4^circ -27^circ angular range. The measured analyzing power and cross section of the continuum are compared with the recent DWIA model calculations. The analyzing power and cross section of low-lying states are compared with the DWBA model calculation. The cross section in the continuum region is found to be dominated by single -step quasifree scattering. The analyzing power angular distributions of continuum peaks support RIA model predictions, and indicate the presence of relativistic medium effects.

  12. Analysis of fine structure in the nuclear continuum

    SciTech Connect

    Shevchenko, A.; Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Carter, J.; Usman, I.; Cooper, G. R. J.; Fearick, R. W.

    2008-02-15

    Fine structure has been shown to be a general phenomenon of nuclear giant resonances of different multipolarities over a wide mass range. In this article we assess various techniques that have been proposed to extract quantitative information from the fine structure in terms of characteristic scales. These include the so-called local scaling dimension, the entropy index method, Fourier analysis, and continuous and discrete wavelet transforms. As an example, results on the isoscalar giant quadrupole resonance in {sup 208}Pb from high-energy-resolution inelastic proton scattering and calculations with the quasiparticle-phonon model are analyzed. Wavelet analysis, both continuous and discrete, of the spectra is shown to be a powerful tool to extract the magnitude and localization of characteristic scales.

  13. Fusion at deep subbarrier energies: potential inversion revisited

    SciTech Connect

    Hagino, K.; Rowley, N.

    2009-03-04

    For a single potential barrier, the barrier penetrability can be inverted based on the WKB approximation to yield the barrier thickness. We apply this method to heavy-ion fusion reactions at energies well below the Coulomb barrier and directly determine the inter-nucleus potential between the colliding nuclei. To this end, we assume that fusion cross sections at deep subbarrier energies are governed by the lowest barrier in the barrier distribution. The inverted inter-nucleus potentials for the {sup 16}O+{sup 144}Sm and {sup 16}O+{sup 208}Pb reactions show that they are much thicker than phenomenological potentials. We discuss a consequence of such thick potential by fitting the inverted potentials with the Bass function.

  14. Investigation of {sup 246}Fm : in-beam spectroscopy at the limits

    SciTech Connect

    Piot, J.; Dorvaux, O.; Gall, B. J.-P.; Rubert, J.; Greenlees, P. T.; Grahn, T.; Herzan, A.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Saren, J.

    2011-10-28

    The structure of {sup 246}Fm has been investigated using in-beam {gamma}-ray spectroscopy. The experiment was performed at the University of Jyvaeskylae using JUROGAM 2 coupled to RITU and GREAT. The {sup 246}Fm nuclei were produced using a 186 MeV beam of {sup 40}Ar impinging on a target of {sup 208}Pb. JUROGAM 2 was fully instrumented with TNT2D digital acquisition cards. The use of digital acquisition cards and a rotating target allowed for unprecedented beam intensities up to 71 particle-nanoamperes for prompt {gamma}-ray spectroscopy. With all these major advances for spectroscopy a rotational band is observed for the first time in {sup 246}Fm and discussed here.

  15. Large-scale shell-model calculations of nuclei around mass 210

    NASA Astrophysics Data System (ADS)

    Teruya, E.; Higashiyama, K.; Yoshinaga, N.

    2016-06-01

    Large-scale shell-model calculations are performed for even-even, odd-mass, and doubly odd nuclei of Pb, Bi, Po, At, Rn, and Fr isotopes in the neutron deficit region (Z ≥82 ,N ≤126 ) assuming 208Pb as a doubly magic core. All the six single-particle orbitals between the magic numbers 82 and 126, namely, 0 h9 /2,1 f7 /2,0 i13 /2,2 p3 /2,1 f5 /2 , and 2 p1 /2 , are considered. For a phenomenological effective two-body interaction, one set of the monopole pairing and quadrupole-quadrupole interactions including the multipole-pairing interactions is adopted for all the nuclei considered. The calculated energies and electromagnetic properties are compared with the experimental data. Furthermore, many isomeric states are analyzed in terms of the shell-model configurations.

  16. Sulfate-water isotope geothermometry and lead isotope data for the regional geothermal system in the Twin Falls Area, South-Central Idaho

    SciTech Connect

    Mariner, R.H.; Bullen, T.D.; Janik, C.J.; Young, H.W.

    1997-12-31

    Sulfate-water isotope geothermometry for the geothermal system at Twin Falls, Idaho indicates aquifer-temperatures of 90{degrees} to 106{degrees}C; most sites are between 90{degrees} and 93{degrees}C. {sup 206}Pb/{sup 204}Pb and {sup 208}Pb/{sup 204}Pb of individual thermal waters are principally a function of how much lead has been dissolved from the carbonate and silicate fractions of the Paleozoic limestone collected west of Grand View Peak. Although most thermal waters are recovered from Tertiary rhyolite, very little of the dissolved lead is from the rhyolite. Recharge to this system occurs in northern Nevada and the fluid moves northward in the Paleozoic limestones. The occurrence of thermal fluid in the Idavada Volcanics near and south of Twin Falls, Idaho is the result of upward movement of this fluid from the Paleozoic limestone.

  17. Isotopic dependence of the cross section for the induced fission of heavy nuclei

    SciTech Connect

    Bolgova, O. N.; Adamian, G. G.; Antonenko, N. V.; Zubov, A. S.; Ivanova, S. P.; Scheid, W.

    2009-06-15

    The cross sections for the induced fission of {sup 211-223}Ra, {sup 203-211}Rn, and {sup 221-231}Th nuclei undergoing peripheral collisions with {sup 208}Pb nuclei are calculated on the basis of the statistical model. The role of the N = 126 neutron shell is studied. The level density in excited nuclei is determined within the Fermi gas model and a model that takes into account the collective enhancement of the level density. The inclusion of a particle-hole excitation in addition to a collective Coulomb excitation makes it possible to obtain a satisfactory description of experimental cross sections for the fission of radium isotopes. The calculated ratios of the cross sections for the induced fission of {sup 236}U ({sup 237}U) and {sup 238}U ({sup 239}U) nuclei agree with experimental data.

  18. Measurement of the cross section for electromagnetic dissociation with neutron emission in Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV.

    PubMed

    Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agocs, A G; Agostinelli, A; Aguilar Salazar, S; Ahammed, Z; Ahmad Masoodi, A; Ahmad, N; Ahn, S U; Akindinov, A; Aleksandrov, D; Alessandro, B; Alfaro Molina, R; Alici, A; Alkin, A; Almaráz Aviña, E; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Arend, A; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Awes, T C; Aystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldini Ferroli, R; Baldisseri, A; Baldit, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Baumann, C; Bearden, I G; Beck, H; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Bock, N; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bose, S; Bossú, F; Botje, M; Böttger, S; Boyer, B; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Bugaiev, K; Busch, O; Buthelezi, Z; Caballero Orduna, D; Caffarri, D; Cai, X; Caines, H; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, F; Carena, W; Carminati, F; Casanova Díaz, A; Castillo Castellanos, J; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chawla, I; Cherney, M; Cheshkov, C; Cheynis, B; Chiavassa, E; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Coccetti, F; Colamaria, F; Colella, D; Conesa Balbastre, G; Conesa Del Valle, Z; Constantin, P; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortés Maldonado, I; Cortese, P; Cosentino, M R; Costa, F; Cotallo, M E; Crochet, P; Cruz Alaniz, E; Cuautle, E; Cunqueiro, L; Erasmo, G D; Dainese, A; Dalsgaard, H H; Danu, A; Das, D; Das, I; Das, K; Dash, A; Dash, S; De, S; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; De Marco, N; De Pasquale, S; de Rooij, R; Del Castillo Sanchez, E; Delagrange, H; Deloff, A; Demanov, V; Dénes, E; Deppman, A; Di Bari, D; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Diaz Corchero, M A; Dietel, T; Divià, R; Djuvsland, O; Dobrin, A; Dobrowolski, T; Domínguez, I; Dönigus, B; Dordic, O; Driga, O; Dubey, A K; Ducroux, L; Dupieux, P; Dutta Majumdar, A K; Dutta Majumdar, M R; Elia, D; Emschermann, D; Engel, H; Erdal, H A; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fearick, R; Fedunov, A; Fehlker, D; Feldkamp, L; Felea, D; Fenton-Olsen, B; Feofilov, G; Fernández Téllez, A; Ferretti, A; Ferretti, R; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Fragkiadakis, M; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Garishvili, I; Gerhard, J; Germain, M; Geuna, C; Gheata, A; Gheata, M; Ghidini, B; Ghosh, P; Gianotti, P; Girard, M R; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Gomez, R; Ferreiro, E G; González-Trueba, L H; González-Zamora, P; Gorbunov, S; Goswami, A; Gotovac, S; Grabski, V; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, A; Grigoras, C; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerra Gutierrez, C; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Gutbrod, H; Haaland, O; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Hanratty, L D; Hansen, A; Harmanova, Z; Harris, J W; Hartig, M; Hasegan, D; Hatzifotiadou, D; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hille, P T; Hippolyte, B; Horaguchi, T; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, G M; Ippolitov, M; Irfan, M; Ivan, C; Ivanov, A; Ivanov, M; Ivanov, V; Ivanytskyi, O; Jachołkowski, A; Jacobs, P M; Jancurová, L; Jang, H J; Jangal, S; Janik, M A; Janik, R; Jayarathna, P H S Y; Jena, S; Jha, D M; Jimenez Bustamante, R T; Jirden, L; Jones, P G; Jung, H; Jusko, A; Kakoyan, V; Kalcher, S; Kaliňák, P; Kalisky, M; Kalliokoski, T; Kalweit, A; Kanaki, K; Kang, J H; Kaplin, V; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Khan, M M; Khan, S A; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, B; Kim, D J; Kim, D W; Kim, J H; Kim, J S; Kim, M; Kim, S; Kim, S H; Kim, T; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Klay, J L; Klein, J; Klein-Bösing, C; Kliemant, M; Kluge, A; Knichel, M L; Knospe, A G; Koch, K; Köhler, M K; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Korneev, A; Kour, R; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kraus, I; Krawutschke, T; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucheriaev, Y; Kuhn, C; Kuijer, P G; Kurashvili, P; Kurepin, A; Kurepin, A B; Kuryakin, A; Kushpil, S; Kushpil, V; Kweon, M J; Kwon, Y; La Pointe, S L; La Rocca, P; Ladrón de Guevara, P; Lakomov, I; Langoy, R; Lara, C; Lardeux, A; Lazzeroni, C; Le Bornec, Y; Lea, R; Lechman, M; Lee, K S; Lee, S C; Lefèvre, F; Lehnert, J; Leistam, L; Lemmon, R C; Lenhardt, M; Lenti, V; León Monzón, I; León Vargas, H; Leoncino, M; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loenne, P I; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, R; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Mal'kevich, D; Malaev, M; Maldonado Cervantes, I; Malinina, L; Malzacher, P; Mamonov, A; Manceau, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Marin Tobon, C A; Markert, C; Martashvili, I; Martinengo, P; Martínez, M I; Martínez Davalos, A; Martínez García, G; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Mastromarco, M; Mastroserio, A; Matthews, Z L; Matyja, A; Mayani, D; Mayer, C; Mazer, J; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, A K; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Musa, L; Musso, A; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Naumov, N P; Navin, S; Nayak, T K; Nazarenko, S; Nazarov, G; Nedosekin, A; Nicassio, M; Nielsen, B S; Niida, T; Nikolaev, S; Nikolic, V; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Novitzky, N; Nyanin, A; Nyatha, A; Nygaard, C; Nystrand, J; Oeschler, H; Oh, S; Oh, S K; Oleniacz, J; Oppedisano, C; Ortiz Velasquez, A; Ortona, G; Oskarsson, A; Otwinowski, J; Oyama, K; Pachmayer, Y; Pachr, M; Padilla, F; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Patalakha, D I; Paticchio, V; Pavlinov, A; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perez Lezama, E; Perini, D; Perrino, D; Peryt, W; Pesci, A; Peskov, V; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Piccotti, A; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piuz, F; Piyarathna, D B; Płoskoń, M; Pluta, J; Pocheptsov, T; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puchagin, S; Puddu, G; Pujol Teixido, J; Pulvirenti, A; Punin, V; Putiš, M; Putschke, J; Quercigh, E; Qvigstad, H; Rachevski, A; Rademakers, A; Radomski, S; Räihä, T S; Rak, J; Rakotozafindrabe, A; Ramello, L; Ramírez Reyes, A; Raniwala, R; Raniwala, S; Räsänen, S S; Rascanu, B T; Rathee, D; Read, K F; Real, J S; Redlich, K; Reichelt, P; Reicher, M; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rodrigues Fernandes Rabacal, B; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roukoutakis, F; Roy, C; Roy, P; Rubio Montero, A J; Rui, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Safařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Sándor, L; Sandoval, A; Sano, M; Sano, S; Santo, R; Santoro, R; Sarkamo, J; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schreiner, S; Schuchmann, S; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, P A; Scott, R; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Sgura, I; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, N; Sharma, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, J; Song, M; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stefanek, G; Stefanini, G; Steinbeck, T; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Sumbera, M; Susa, T; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szostak, A; Tagridis, C; Takahashi, J; Tapia Takaki, J D; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Tlusty, D; Toia, A; Torii, H; Tosello, F; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urbán, J; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vallero, S; van der Kolk, N; van Leeuwen, M; Vande Vyvre, P; Vannucci, L; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Vikhlyantsev, O; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Viyogi, Y P; Vodopyanov, A; Voloshin, K; Voloshin, S; Volpe, G; von Haller, B; Vranic, D; Ovrebekk, G; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, V; Wan, R; Wang, D; Wang, M; Wang, Y; Wang, Y; Watanabe, K; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, A; Wilk, G; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yaldo, C G; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, H; Zhang, X; Zhou, D; Zhou, F; Zhou, Y; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M

    2012-12-21

    The first measurement of neutron emission in electromagnetic dissociation of ^{208}Pb nuclei at the LHC is presented. The measurement is performed using the neutron zero degree calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at sqrt[s(NN)]=2.76 TeV with neutron emission are σ(singleEMD)=187.4 ± 0.2(stat)(-11.2)(+13.2) (syst) b and σ(mutualEMD) = 5.7 ± 0.1(stat) ± 0.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model.

  19. {gamma}-ray spectroscopy of {sub 17}{sup 38}Cl using grazing reactions

    SciTech Connect

    O'Donnell, D.; Chapman, R.; Liang, X.; Burns, M.; Hodsdon, A.; Keyes, K.; Ollier, J.; Papenberg, A.; Smith, J. F.; Spohr, K. M.; Wang, Z. M.; Azaiez, F.; Ibrahim, F.; Stanoiu, M.; Verney, D.; Haas, F.; Caurier, E.; Curien, D.; Nowacki, F.; Salsac, M.-D.

    2010-02-15

    Excited states of {sub 17}{sup 38}Cl{sub 21} were populated in binary grazing reactions during the interaction of a beam of {sub 16}{sup 36}S{sub 20} ions of energy 215 MeV with a {sub 82}{sup 208}Pb{sub 126} target. The combination of the PRISMA magnetic spectrometer and the CLARA {gamma}-ray detector array was used to identify the reaction fragments and to detect their decay via {gamma}-ray emission. A level scheme for {sup 38}Cl is presented and discussed within the context of the systematics of neighboring nuclei and is compared with the results of state-of-the-art shell-model calculations.

  20. Conservation of Isospin in Neutron-rich Fission Fragments

    SciTech Connect

    Jain, A.K.; Choudhury, D.; Maheshwari, B.

    2014-06-15

    On the occasion of the 75{sup th} anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions {sup 238}U({sup 18}O,f) and {sup 208}Pb({sup 18}O,f) as well as a thermal neutron fission reaction {sup 245}Cm(n{sup th},f). We find that the conservation of the total isospin explains the overall trend in the observed relative yields of fragment masses in each fission pair partition. The isospin values involved are very large making the effect dramatic. The findings open the way for more precise calculations of fission fragment distributions in heavy nuclei and may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation of decay heat in the fission phenomenon.

  1. Isotopic composition of lead and strontium from Ascension and Gough Islands

    USGS Publications Warehouse

    Gast, P.W.; Tilton, G.R.; Hedge, C.

    1964-01-01

    Isotopic composition of lead and strontium has been determined in a series of rock samples from two islands on the Mid-Atlantic Ridge. Both inter-and intra-island variations exist in the abundance of radiogenic isotopes of both elements. Lead from basalt of Ascension Island has a Pb206-Pb 204 ratio of 19.5, while the corresponding ratio at Gough Island is only 18.4. The Pb208-Pb204 ratios from the two islands do not differ. Conversely, strontium from basalt of Ascension Island is less radiogenic than that from Gough Island basalts. The trachytes of both islands have lead and strontium that is more radiogenic than that found in the basalts. The inter-island differences indicate the existence of regional variations in the uranium-lead and rubidium-strontium ratios of the upper mantle source of these rocks and show that isotope compositions are a means for investigating chemical heterogeneities in the mantle.

  2. Realistic shell-model calculations and exotic nuclei around {sup 132}Sn

    SciTech Connect

    Covello, A.; Itaco, N.; Coraggio, L.; Gargano, A.

    2008-11-11

    We report on a study of exotic nuclei around doubly magic {sup 132}Sn in terms of the shell model employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. The short-range repulsion of the latter is renormalized by constructing a smooth low-momentum potential, V{sub low-k}, that is used directly as input for the calculation of the effective interaction. In this paper, we focus attention on proton-neutron multiplets in the odd-odd nuclei {sup 134}Sb, {sup 136}Sb. We show that the behavior of these multiplets is quite similar to that of the analogous multiplets in the counterpart nuclei in the {sup 208}Pb region, {sup 210}Bi and {sup 212}Bi.

  3. Dynamical eikonal approximation in breakup reactions of {sup 11}Be

    SciTech Connect

    Goldstein, G.; Baye, D.

    2006-02-15

    The dynamical eikonal approximation is a quantal method unifying the semiclassical time-dependent and eikonal methods by taking into account interference effects. The principle of the calculation is described and expressions for different types of cross sections are established for two variants of the method, differing by a phase choice. The 'coherent' variant respects rotational symmetry around the beam axis and is therefore prefered. A good agreement is obtained with experimental differential and integrated cross sections for the elastic breakup of the {sup 11}Be halo nucleus on {sup 12}C and {sup 208}Pb near 70 MeV/nucleon, without any parameter adjustment. The dynamical approximation is compared with the traditional eikonal method. Differences are analyzed and the respective merits of both methods are discussed.

  4. Probing the weakly-bound neutron orbit of {sup 31}Ne with total reaction and one-neutron removal cross sections

    SciTech Connect

    Horiuchi, W.; Suzuki, Y.; Capel, P.; Baye, D.

    2010-02-15

    A candidate of a neutron-halo nucleus, {sup 31}Ne, contains a single neutron in the pf shell. Within the Glauber and eikonal models, we analyze reactions used to study {sup 31}Ne. We show in a {sup 30}Ne+n model that the magnitudes of the total reaction and above all of the one-neutron removal cross sections of {sup 31}Ne on {sup 12}C and {sup 208}Pb targets strongly depend on the orbital angular momentum of the neutron, thereby providing us with efficient ways to determine both the spin-parity and structure of the ground state of {sup 31}Ne. Besides these inclusive observables, we also calculate energy and parallel-momentum distributions for the breakup of {sup 31}Ne and show their strong dependence on the orbital of the valence neutron in the bound state of {sup 31}Ne.

  5. Phenomenological barrier parameters for total reaction cross section

    NASA Astrophysics Data System (ADS)

    Phookan, C. K.; Kalita, K.

    2016-01-01

    A phenomenological formula for total reaction cross section is introduced for reactions induced by three types of projectiles. The formula is based on Wong's formula in which, the barrier parameters are calculated from the Bass, Aage Winther and the Akyuz Winther potentials. For the reactions studied, we find that a uniform correction of the barrier parameters can account for the total reaction cross section satisfactorily. An unusually large deviation of the barrier parameters is noticed for the reaction {}8{B} + {}^{58}{Ni}. Arguments are given that most likely the radius of the proton halo nucleus {}8{B} is not well accounted by the above potentials and hence, an increase in the effective radius of {}^8{B} is proposed. Analysis is also presented for the reaction {}^{11}{Li} + {}^{208}{Pb} by making the assumption that its reduced total reaction cross section lies on the same trajectory as that for other halo reactions.

  6. Dynamical nucleus-nucleus potential at short distances

    SciTech Connect

    Jiang Yongying; Wang Ning; Li Zhuxia; Scheid, Werner

    2010-04-15

    The dynamical nucleus-nucleus potentials for fusion reactions {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 208}Pb, and {sup 126}Sn+{sup 130}Te are studied with the improved quantum molecular dynamics model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for {sup 40}Ca+{sup 40}Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depths of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of the fusion barrier is also investigated. The fusion pocket becomes shallow for a heavy fusion system and almost disappears for heavy nearly symmetric systems, and the obtained potential at short distances is higher than the adiabatic potential.

  7. Constraining the nuclear equation of state at subsaturation densities.

    PubMed

    Khan, E; Margueron, J; Vidaña, I

    2012-08-31

    Only one-third of the nucleons in 208Pb occupy the saturation density area. Consequently, nuclear observables related to the average properties of nuclei, such as masses or radii, constrain the equation of state not at the saturation density but rather around the so-called crossing density, localized close to the mean value of the density of nuclei: ρ is approximately equal to 0.11 fm(-3). This provides an explanation for the empirical fact that several equation of state quantities calculated with various functionals cross at a density significantly lower than the saturation one. The third derivative M of the energy per unit of volume at the crossing density is constrained by the giant monopole resonance measurements in an isotopic chain rather than the incompressibility at saturation density. The giant monopole resonance measurements provide M=1100±70 MeV (6% uncertainty), whose extrapolation gives K(∞)=230±40 MeV (17% uncertainty).

  8. Intercomparison of experimental and theoretical ranges of heavy ions in plastic track detectors

    NASA Astrophysics Data System (ADS)

    Virk, H. S.; Randhawa, G. S.; Sharma, S. K.

    1996-01-01

    In the present study, CR-39 and Lexan polycarbonate plastic track detectors have been exposed to various heavy ion beams, i.e. ,238U, b,208Pb, u,197Au, a,139La, e132Xe and b93Nb (energy range from 5.6 to 18.0 MeV/u), from the UNILAC accelerator at GSI, Darmstadt. After exposure, the irradiated samples were etched under optimum etching conditions. The total etchable ranges of these heavy ions have been determined experimentally using a Carl Zeiss binocular microscope. In order to check the validity of the various stopping power and range formulations in this energy range, the experimentally determined range values have been compared with the theoretically computed values from the Benton and Henke, Mukherjee and Nayak, Ziegler et al. and Hubert et al. formulations.

  9. Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances

    NASA Astrophysics Data System (ADS)

    Thompson, I. J.; Escher, J. E.; Arbanas, G.

    2014-04-01

    Semidirect capture, a two-step process that excites a giant-dipole resonance followed by its radiative de-excitation, is a dominant process near giant-dipole resonances, that is, for incoming neutron energies within 5-20 MeV. At lower energies such processes may affect neutron capture rates that are relevant to astrophysical nucleosynthesis models. We implement a semidirect capture model in the coupled-channel reaction code Fresco and validate it by comparing the cross section for direct-semidirect capture 208Pb(n,γ)209Pb to experimental data. We also investigate the effect of low-energy electric dipole strength in the pygmy resonance. We use a conventional single-particle direct-semidirect capture code Cupido for comparison. Furthermore, we present and discuss our results for direct-semidirect capture reaction 130Sn(n,γ)131Sn, the cross section of which is known to have a significant effect on nucleosynthesis models.

  10. Extracting (n,gamma) direct capture cross sections from Coulomb dissociation: application to 14C(n,gamma)15C

    SciTech Connect

    Summers, N C; Nunes, F M

    2008-01-22

    A methodology for extracting neutron direct capture rates from Coulomb Dissociation data is developed and applied to the Coulomb dissociation of {sup 15}C on {sup 208}Pb at 68 MeV/nucleon. Full Continuum Discretized Coupled Channel calculations are performed and an asymptotic normalization coefficient is determined from a fit to the breakup data. Direct neutron capture calculations using the extracted asymptotic normalization coefficient provide (n, {gamma}) cross sections consistent with direct measurements. Our results show that the Coulomb Dissociation data can be reliably used for extracting the cross section for {sup 14}C(n,{gamma}){sup 15}C if the appropriate reaction theory is used. The resulting error bars are of comparable magnitude to those from the direct measurement.

  11. Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances

    SciTech Connect

    Thompson, I J; Escher, Jutta E; Arbanas, Goran

    2013-01-01

    Semidirect capture, a two-step process that excites a giant-dipole resonance followed by its radiative de-excitation, is a dominant process near giant-dipole resonances, that is, for incoming neutron energies within 5 20 MeV. At lower energies such processes may affect neutron capture rates that are relevant to astrophysical nucleosynthesis models. We implement a semidirect capture model in the coupled-channel reaction code Fresco and validate it by comparing the cross section for direct-semidirect capture 208Pb(n,g)209Pb to experimental data. We also investigate the effect of low-energy electric dipole strength in the pygmy resonance. We use a conventional single-particle direct-semidirect capture code Cupido for comparison. Furthermore, we present and discuss our results for direct-semidirect capture reaction 130Sn(n,g)131Sn, the cross section of which is known to have a significant effect on nucleosynthesis models.

  12. Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions

    SciTech Connect

    Szilner, S.; Jelavic-Malenica, D.; Soic, N.; Corradi, L.; Fioretto, E.; Sahin, E.; Silvestri, R.; Stefanini, A. M.; Valiente-Dobon, J. J.; Haas, F.; Lebhertz, D.; Bouhelal, M.; Caurier, E.; Courtin, S.; Goasduff, A.; Nowacki, F.; Ur, C. A.; Beghini, S.; Farnea, E.

    2011-07-15

    New {gamma} transitions have been identified in argon isotopes in {sup 40}Ar + {sup 208}Pb multiple transfer reactions by exploiting, in a fragment-{gamma} measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large {gamma} arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states.

  13. Metallic elements and isotope of Pb in wet precipitation in urban area, South America

    NASA Astrophysics Data System (ADS)

    Migliavacca, Daniela Montanari; Teixeira, Elba Calesso; Gervasoni, Fernanda; Conceição, Rommulo Vieira; Raya Rodriguez, Maria Teresa

    2012-04-01

    The atmosphere of urban areas has been the subject of many studies to show the atmospheric pollution in large urban centers. By quantifying wet precipitation through the analysis of metallic elements (ICP/AES) and Pb isotopes, the wet precipitation of the Metropolitan Area of the Porto Alegre (MAPA), Brazil, was characterized. The samples were collected between July 2005 and December 2007. Zn, Fe and Mn showed the highest concentration in studied sites. Sapucaia do Sul showed the highest average for Zn, due to influence by the steel plant located near the sampling site. The contribution of anthropogenic emissions from vehicular activity and steel plants in wet precipitation and suspended particulate matter in the MAPA was identified by the isotopic signatures of 208Pb/207Pb and 206Pb/207Pb. Moreover the analyses of the metallic elements allowed also to identify the contribution of other anthropic sources, such as steel plants and oil refinery.

  14. Neutron measurements in the stray field produced by 158 GeV c(-1) per nucleon lead ion beams.

    PubMed

    Agosteo, S; Birattari, C; Foglio Para, A; Nava, E; Silari, M; Ulrici, L

    1998-12-01

    This paper discusses measurements carried out at CERN in the stray radiation field produced by 158 GeV c(-1) per nucleon 208Pb82+ ions. The purpose was to test and intercompare the response of several detectors, mainly neutron measuring devices, and to determine the neutron spectral fluence as well as the microdosimetric (absorbed dose and dose equivalent) distributions in different locations around the shielding. Both active instruments and passive dosimeters were employed, including different types of Andersson-Braun rem counters, a tissue equivalent proportional counter, a set of superheated drop detectors, a Bonner sphere system, and different types of ion chambers. Activation measurements with 12C plastic scintillators and with 32S pellets were also performed to assess the neutron yield of high energy lead ions interacting with a thin gold target. The results are compared with previous measurements and with measurements made during proton runs.

  15. Nuclear physics. Momentum sharing in imbalanced Fermi systems.

    PubMed

    Hen, O; Sargsian, M; Weinstein, L B; Piasetzky, E; Hakobyan, H; Higinbotham, D W; Braverman, M; Brooks, W K; Gilad, S; Adhikari, K P; Arrington, J; Asryan, G; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Beck, A; May-Tal Beck, S; Bedlinskiy, I; Bertozzi, W; Biselli, A; Burkert, V D; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Colaneri, L; Cole, P L; Crede, V; D'Angelo, A; De Vita, R; Deur, A; Djalali, C; Doughty, D; Dugger, M; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Fedotov, G; Fegan, S; Forest, T; Garillon, B; Garcon, M; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hanretty, C; Hattawy, M; Hicks, K; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkanov, B I; Isupov, E L; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, F J; Koirala, S; Korover, I; Kuhn, S E; Kubarovsky, V; Lenisa, P; Levine, W I; Livingston, K; Lowry, M; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mokeev, V; Movsisyan, A; Munoz Camacho, C; Mustapha, B; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Ritchie, B G; Rizzo, A; Rosner, G; Roy, P; Rossi, P; Sabatié, F; Schott, D; Schumacher, R A; Sharabian, Y G; Smith, G D; Shneor, R; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tkachenko, S; Ungaro, M; Vlassov, A V; Voutier, E; Walford, N K; Wei, X; Wood, M H; Wood, S A; Zachariou, N; Zana, L; Zhao, Z W; Zheng, X; Zonta, I

    2014-10-31

    The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems.

  16. Gamow-Teller response and its spreading mechanism in doubly magic nuclei

    NASA Astrophysics Data System (ADS)

    Niu, Y. F.; Colò, G.; Vigezzi, E.

    2014-11-01

    The scope of the paper is to apply a state-of-the-art beyond mean-field model to the description of the Gamow-Teller response in atomic nuclei. This topic recently attracted considerable renewed interest, due, in particular, to the possibility of performing experiments in unstable nuclei. We study the cases of 48Ca,78Ni,132Sn, and 208Pb. Our model is based on a fully self-consistent Skyrme Hartree-Fock plus random phase approximation. The same Skyrme interaction is used to calculate the coupling between particles and vibrations, which leads to the mixing of the Gamow-Teller resonance with a set of doorway states and to its fragmentation. We compare our results with available experimental data. The microscopic coupling mechanism is also discussed in some detail.

  17. Spectroscopy of the Heaviest Elements

    NASA Astrophysics Data System (ADS)

    Clark, Roderick

    2009-10-01

    The specific ``magic'' proton and neutron numbers, representing major spherical shell gaps, beyond 208Pb are a matter of considerable debate. It is well established that nuclei near Z=100, N=152 (252Fm) have well-deformed prolate shapes. By performing prompt and delayed gamma-ray spectroscopy on deformed transfermium nuclei we can learn about the single-particle structure, shell gaps, pairing correlations, and excitation modes in the heaviest nuclei. After a brief overview of state-of-the-art measurements, I will describe recent results from experiments at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory which use the Berkeley Gas-filled Separator (BGS). I will then discuss the prospects of a new generation of spectroscopy measurements on the heaviest elements when the BGS is used in conjunction with the GRETINA gamma--ray tracking array.

  18. (Theoretical nuclear physics)

    SciTech Connect

    Not Available

    1991-01-01

    This report discussed the following topics: Consistent RHA-RPA for finite nuclei; vacuum polarization in a finite system; isovector correlations in QHD description of nuclear matter; nuclear response functions in quasielastic electron scattering; charge density differences for nuclei near {sup 208}Pb in quantum hadro-dynamics; excitation of the 10.957 MeV 0{sup {minus}}; T=0 state in {sup 16}O by 400 MeV protons; deformed chiral nucleons; new basis for exact vacuum calculations in 3-spatial dimensions; second order processes in the (e,e{prime}d) reaction; scalar and vector contributions to {bar p}p {yields} {bar {Lambda}}{Lambda} and {bar p}p {yields} {bar {Lambda}}{Sigma}{sup 0} + c.c; and radiative capture of protons by light nuclei at low energies.

  19. Theoretical nuclear physics

    SciTech Connect

    Kunz, P.D.

    1990-10-01

    This report contains small papers on the following topics: ground state correlations of nuclei in relativistic random phase approximation; instability of infinite nuclear matter in the relativistic hartree approximation; charge density differences for nuclei near {sup 208}Pb in relativistic models; meson exchange current corrections to magnetic moments in quantum hadro-dynamics; analysis of the O{sup +} {yields} O{sup {minus}} reaction at intermediate energies; contributions of reaction channels to the {sup 6}Li(p,{gamma}){sup 7}Be Reaction; deformed chiral nucleons; vacuum polarization in a finite system; second order processes in the (e,e{prime}d) reaction; sea contributions in Dirac RPA for finite nuclei; and momentum cutoffs in the sea.

  20. Entrance channel effects in superheavy element production

    NASA Astrophysics Data System (ADS)

    Nasirov, Avazbek; Giardina, Giorgio; Mandaglio, Giuseppe; Muminov, Akhtam

    2016-12-01

    The difference between evaporation residue cross sections measured in the cold (X+208Pb, 209Bi) and hot (48Ca+actinides) fusion reactions can be related to the stage of compound nucleus (CN) formation and/or to the stage of its survival against fission. The cold fusion reactions are favorable in synthesis of the superheavy elements (SHE) with charge numbers Z < 112 in comparison with the hot fusion reactions due to small excitation energy and large fission barrier of the CN formed in these reactions. The strong decrease of the cross sections of the synthesis of the SHE Z = 113 in the cold fusion reactions in comparison with the ones in the hot fusion reactions is the result of the increase of hindrance to the CN formation in the cold fusion reactions. The origin of the intrinsic fusion barrier, B, causing the strong decrease of the probability PCN in the cold fusion is discussed.

  1. Plume-Lithosphere Interaction beneath the Snake River Plain, Idaho: Constraints from Pb, Sr, Nd, and Hf Isotopes

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Hanan, B. B.; Shervais, J. W.

    2011-12-01

    The Yellowstone-Snake River Plain (YSRP) volcanic province links 17 million years of volcanic activity that extends from the Owyhee Plateau in western Idaho/eastern Oregon to its current terminus underlying the Yellowstone Plateau. This investigation presents new Strontium, Neodymium, Lead, and Hafnium isotopic compositions of 25 basalts that represent four distinct areas of the YSRP (i.e., eastern province, central province, western province, Owyhee Plateau), which transect the ancient cratonic boundary of North America. The purpose of this study is to test and refine models for plume-lithosphere interaction and determines the mantle origin for YSRP basalts. New results shows: (1) low-K tholeiites from the eastern, central, and western SRP have ɛNd (-2 to -5.5), 87Sr/86Sr (0.7060-0.7071) and similar Pb-isotopes [206Pb/204Pb (17.8-18.6), 207Pb/204Pb (15.5-15.66), 208Pb/204Pb (38.4-39.1)]; (2) central SRP tholeiites are enriched in 208Pb/204Pb (~38.5-38.9), relative to eastern SRP basalts and define a 208Pb/204Pb trend, intermediate between the eastern SRP and Craters of the Moon lavas; (3) western SRP high-K basalts are depleted in ɛNd (> -1) and 87Sr/86Sr (0.7050-0.7057), relative to low-K tholeiites, and plot closer to "bulk silicate earth," but are enriched in 206Pb/204Pb (18.66-18.71), and have 207Pb/204Pb (15.62-15.65) and 208Pb/204Pb (39.1-39.2) isotope ratios similar to high-K basalts of Smith Prairie (Boise River Group 2); (4) Silver City basalt (>16.6 Ma) overlaps in Pb-isotope space with Imnaha basalt compositions (Columbia River Basalt Group); (5) new 177Hf/176Hf isotopic data lie above and parallel to the Mantle array in Nd and Hf isotope space and define a linear trend between Leucite Hills lavas and OIB basalts (i.e., Steens and Hawaii); (6) these basalts follow a systematic geographic pattern: eastern and central plain low-K tholeiites have low ɛNd (-3 to -5) and intermediate 206Pb/204Pb (~17.7-18.5), while western plain low-K tholeiites are

  2. River Valley pluton, Ontario - A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

    NASA Technical Reports Server (NTRS)

    Ashwal, Lewis D.; Wooden, Joseph L.

    1989-01-01

    This paper presents Nd, Sr, and Pb isotopic data indicating a late-Archean/early-Proterozoic age for the River Valley anorthositic pluton of the southwestern Grenville Province of Sudbury, Ontario. Pb-Pb isotopic data on 10 whole-rock samples ranging in composition from anorthosite to gabbro yield an age of 2560 + or - 155 Ma. The River Valley pluton is thus the oldest anorthositic intrusive yet recognized within the Grenville Province. The Sm-Nd isotopic system records an age of 2377 + or - 68 Ma. High Pb-208/Pb-204 of deformed samples relative to igneous-textured rocks implies Th introduction and/or U loss during metamorphism in the River Valley area. Rb-Sr data from igneous-textured and deformed samples and from mineral separates give an age of 2185 + or - 105 Ma, indicating substantial disturbance of the Rb-Sr isotopic system.

  3. Universal damping mechanism of quantum vibrations in deep sub-barrier fusion reactions

    NASA Astrophysics Data System (ADS)

    Ichikawa, Takatoshi; Matsuyanagi, Kenichi

    2015-08-01

    We demonstrate the damping of quantum octupole vibrations near the touching point when two colliding nuclei approach each other in the mass-asymmetric 16 O + 208 Pb system, for which the strong fusion hindrance was clearly observed. We, for the first time, apply the random-phase approximation method to the heavy-mass asymmetric dinuclear system to calculate the transition strength B (E 3 ) as a function of the center-of-mass distance. The obtained B (E 3 ) strengths are substantially damped near the touching point, because the single-particle wave functions of the two nuclei strongly mix with each other and a neck is formed. The energy-weighted sums of B (E 3 ) are also strongly correlated with the damping factor, which is phenomenologically introduced in the standard coupled-channel calculations to reproduce the fusion hindrance. This strongly indicates that the damping of the quantum vibrations universally occurs in the deep sub-barrier fusion reactions.

  4. Structure of 10N via 9C+p Resonance Scattering

    NASA Astrophysics Data System (ADS)

    Hooker, Joshua; Rogachev, Grigory; Koshchiy, Yevgen; Uberseder, Ethan; Jayatissa, Heshani; Hunt, Curtis; Roeder, Brian

    2015-10-01

    The study of 10 N through the reaction 9 C(p , p) 9 C using a new time projection chamber (TexAT-P1) at the Cyclotron Institute at Texas A&M University. Only one experiment before this study on 10 N has claimed to have observed the ground state. We build on this result by providing a spin-parity assignment of the ground state and low-lying excited states in 10 N . The mirror nucleus, 10 Li , is not well known and also has uncertainty its spin-parity assignments and excitation energies in low-lying states. This nucleus is important to study as it can help explain the two neutron halo nucleus 11 Li as its nuclear matter radius is as large as that of 208 Pb .

  5. Spectroscopy of 215Rn86

    SciTech Connect

    Debray, M. E.; Davidson, M.; Davidson, J.; Hojman, D.; Kreiner, A. J.; Cardona, M. A.; Lenzi, S.; Napoli, D.

    2007-02-12

    The yrast level structure of 215,216Rn has been studied using in beam spectroscopy {alpha} - {gamma} - {gamma} coincidence techniques mainly through the 207Pb(18O, 2{alpha}2n) and 208Pb(18O, 2{alpha}2n) reactions in the 91-93 MeV energy range, using the 8{pi} GASP-ISIS spectrometer at Legnaro. The obtained low lying level scheme of 215Rn does not exhibit the alternating parity structure observed in their heavier known isotones 216Fr, 217Ra and 218Ac. The level scheme of 216Rn resulting from this study shows >From this result, the lightest nucleus showing evidence for reflection asymmetry is 216Fr defining one lowest-mass corner for this kind of phenomenon as N{>=}129 and Z{>=}87.

  6. Fully self-consistent study of charge-exchange resonances and the impact on the symmetry energy parameters

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Cao, Li-Gang; Colò, G.; Sagawa, H.

    2016-10-01

    We have examined within a fully self-consistent theoretical framework the energy difference between the anti-analog giant dipole resonance (AGDR) and the isobaric analog state (IAS), EAGDR-EIAS , as an indicator of the neutron skin and of the density behavior of the symmetry energy. We have improved two specific points in our HF+RPA calculations: (1) the exchange term of the two-body Coulomb interaction is treated exactly without Slater approximation; and (2) the two-parameters spin-orbit interaction is treated in a consistent way within the energy density functional theory. The estimated values for the neutron skin in 208Pb and the slope parameter of symmetry energy are compared with previous analysis available in the literature.

  7. Age of the moon: An isotopic study of uranium-thorium-lead systematics of lunar samples

    USGS Publications Warehouse

    Tatsumoto, M.; Rosholt, J.N.

    1970-01-01

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of 207Pb/206Pb, 206Pb/238U, 207Pb/235U, and 208Pb/232Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The 238U/235U ratio is the same as that in earth rocks, and 234U is in radioactive equilibrium with parent 238U.

  8. Age of the moon: an isotopic study of uranium-thorium-lead systematics of lunar samples.

    PubMed

    Tatsumoto, M; Rosholt, J N

    1970-01-30

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of (207)Pb/(206)Pb, (206)Pb/(238)U, (207)Pb/(235U), and(208)Pb/(232)Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The (238)U/(235)U ratio is the same as that in earth rocks, and (234)U is in radioactive equilibrium with parent (238)U.

  9. Constraining the symmetry energy content of nuclear matter from nuclear masses: A covariance analysis

    NASA Astrophysics Data System (ADS)

    Mondal, C.; Agrawal, B. K.; De, J. N.

    2015-08-01

    Elements of nuclear symmetry energy evaluated from different energy density functionals parametrized by fitting selective bulk properties of few representative nuclei are seen to vary widely. Those obtained from experimental data on nuclear masses across the periodic table, however, show that they are better constrained. A possible direction in reconciling this paradox may be gleaned from comparison of results obtained from use of the binding energies in the fitting protocol within a microscopic model with two sets of nuclei, one a representative standard set and another where very highly asymmetric nuclei are additionally included. A covariance analysis reveals that the additional fitting protocol reduces the uncertainties in the nuclear symmetry energy coefficient, its slope parameter, as well as the neutron-skin thickness in 208Pb nucleus by ˜50 % . The central values of these entities are also seen to be slightly reduced.

  10. Electroweak Measurements of Neutron Densities in CREX and PREX at JLab, USA

    SciTech Connect

    Horowitz, Charles J.; Kumar, Krishna S.; Michaels, Robert W.

    2014-02-01

    Measurement of the parity-violating electron scattering asymmetry is an established technique at Jefferson Lab and provides a new opportunity to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively; these are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter ${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces.

  11. Angular momentum effects in multimodal fission of {sup 226}Th

    SciTech Connect

    Chubarian, G.G.; Hurst, B.J.; OKelly, D.; Schmitt, R.P.; Itkis, M.G.; Kondratiev, N.A.; Kozulin, E.M.; Oganessian, Y.T.; Pashkevich, V.V.; Pokrovsky, I.V.; Salamatin, V.S.; Rusanov, A.Y.; Calabretta, L.; Maiolino, C.; Lukashin, K.; Agodi, C.; Bellia, G.; Hanappe, F.; Liatard, E.; Huck, A.; Stuttge, L.

    1998-12-01

    The {gamma}-rays from the multimodal fission of the {sup 226}Th formed in {sup 18}O+{sup 208}Pb was investigated at the near- and sub-barrier energies. The corresponding excitation energies at the saddle point, E{sub sp}{sup {asterisk}}, ranged from 23 to 26 MeV. The average {gamma}-ray multiplicities and relative {gamma}-ray energies as a function of the mass of the fission fragments exhibits a complex structure and strong variations. Such strong variations have never been previously observed in heavy ion-induced fusion-fission reactions. Obtained results may be explained with the influence of shell effects on the properties of the fission fragments. Present work is the one in series of investigation of the multimodal fission phenomena in At-Th region. {copyright} {ital 1998 American Institute of Physics.}

  12. Pb isotope composition in lichens and aerosols from eastern Sicily: Insights into the regional impact of volcanoes on the environment

    SciTech Connect

    Monna, F. ); Aiuppa, A.; Varrica, D. ); Dongarra, G. CNR, Palermo . Istituto Geochimica dei Fluidi)

    1999-08-01

    A total of 25 lichen thalli of Parmelia conspersa (Ehrh), collected at Vulcano island and at Mt. Etna, during a one-year biogeochemical survey, were analyzed for Pb, br, Al, Sc,[sup 206]Pb/[sup 207]Pb, and [sup 208]Pb/[sup 206]Pb ratios. Lead isotope ratios were also measured on aerosol samples from urban areas and industrial sites of Sicily. The observed [sup 206]Pb/[sup 207]Pb range for urban and industrial aerosols matches the anthropogenic signature. Lichens instead, are closer to the compositional field of [sup 206]Pb rich geogenic sources. This natural input is more evident at Vulcano island than at Mt. Etna, where the anthropogenic activities are considerably more effective. On the basis of lead isotope data, Pb/Br ratios and calculated lead enrichment factors, a natural lead pollution from volcanoes is suggested. Volcanic lead contribution ranges from 10 to 30% at Mt. Etna to 10--80% at Vulcano island.

  13. Low-power lead-cooled fast reactor loaded with MOX-fuel

    NASA Astrophysics Data System (ADS)

    Sitdikov, E. R.; Terekhova, A. M.

    2017-01-01

    Fast reactor for the purpose of implementation of research, education of undergraduate and doctoral students in handling innovative fast reactors and training specialists for atomic research centers and nuclear power plants (BRUTs) was considered. Hard neutron spectrum achieved in the fast reactor with compact core and lead coolant. Possibility of prompt neutron runaway of the reactor is excluded due to the low reactivity margin which is less than the effective fraction of delayed neutrons. The possibility of using MOX fuel in the BRUTs reactor was examined. The effect of Keff growth connected with replacement of natural lead coolant to 208Pb coolant was evaluated. The calculations and reactor core model were performed using the Serpent Monte Carlo code.

  14. Laboratory measurement of radioactivity purification for 212Pb in liquid scintillator

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Fang, Jian; Yu, Bo-Xiang; Zhang, Xuan; Zhou, Li; Cai, Xiao; Sun, Li-Jun; Liu, Wan-Jin; Wang, Lan; Lü, Jun-Guang

    2016-09-01

    Liquid scintillator (LS) has been widely used in past and running neutrino experiments, and is expected also to be used in future experiments. Requirements on LS radio-purity have become higher and higher. Water extraction is a powerful method to remove soluble radioactive nuclei, and a mini-extraction station has been constructed. To evaluate the extraction efficiency and optimize the operation parameters, a setup to load radioactivity to LS and a laboratory scale setup to measure radioactivity using the 212Bi-212Po-208Pb cascade decay have been developed. Experience from this laboratory study will be useful for the design of large scale water extraction plants and the optimization of working conditions in the future. Supported by The Strategic Priority Research Program of the Chinese Academy of Sciences (XDA10010500), Natural Science Foundation of China (11390384)

  15. High-Spin States of {sup 84,85}Br: Mapping the Proton Sub-Shells towards {sup 78}Ni

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Deloncle, I.; Venkova, Ts.; Azaiez, F.; Buta, A.; Curien, D.; Dorvaux, O.; Duchene, G.; Gall, B. J. P.; Khalfallah, F.; Piqueras, I.; Rousseau, M.; Meyer, M.; Redon, N.; Stezowski, O.; Lucas, R.

    2008-05-12

    The {sup 84,85}Br nuclei have been produced as fission fragments in the fusion reaction {sup 18}O+{sup 208}Pb at 85 MeV bombarding energy and studied with the Euroball IV array. The high-spin states of the odd-odd {sup 84}Br nucleus have been identified for the first time. From angular correlation analysis, spin values have been assigned to most of the {sup 85}Br excited states up to 4 MeV. All observed states in {sup 84,85}Br can be described by various proton excitations involving at least the two sub-shells ({pi}f{sub 5/2} and {pi}p{sub 3/2}) located just above the Z = 28 shell closure.

  16. Neutron-Rich Nuclei and Neutron Stars: A New Accurately Calibrated Interaction for the Study of Neutron-Rich Matter

    SciTech Connect

    Todd-Rutel, B.G.; Piekarewicz, J.

    2005-09-16

    An accurately calibrated relativistic parametrization is introduced to compute the ground state properties of finite nuclei, their linear response, and the structure of neutron stars. While similar in spirit to the successful NL3 parameter set, it produces an equation of state that is considerably softer--both for symmetric nuclear matter and for the symmetry energy. This softening appears to be required for an accurate description of several collective modes having different neutron-to-proton ratios. Among the predictions of this model are a symmetric nuclear-matter incompressibility of K=230 MeV and a neutron skin thickness in {sup 208}Pb of R{sub n}-R{sub p}=0.21 fm. The impact of such a softening on various neutron-star properties is also examined.

  17. Onset of nuclear structure effects in near-barrier elastic scattering of weakly bound nuclei: {sup 6}He and {sup 6}Li compared

    SciTech Connect

    Kucuk, Y.; Boztosun, I.; Keeley, N.

    2009-06-15

    The elastic scattering of the halo nucleus {sup 6}He from heavy targets at incident energies near the Coulomb barrier displays a marked deviation from the standard Fresnel-type diffraction behavior. This deviation is due to the strong Coulomb dipole breakup coupling produced by the Coulomb field of the heavy target, a specific feature of the nuclear structure of {sup 6}He. We have performed Continuum Discretized Coupled Channels calculations for the elastic scattering of {sup 6}He and {sup 6}Li from {sup 58}Ni, {sup 120}Sn, {sup 144}Sm, {sup 181}Ta and {sup 208}Pb targets in order to determine the range of Z{sub T} where this nuclear-structure specific coupling effect becomes manifest. We find that the strong Coulomb dipole breakup coupling effect is only clearly experimentally distinguishable for targets of Z{sub T}{approx_equal}80.

  18. Louisville seamount subduction and its implication on mantle flow beneath the central Tonga-Kermadec arc.

    PubMed

    Timm, Christian; Bassett, Daniel; Graham, Ian J; Leybourne, Matthew I; de Ronde, Cornel E J; Woodhead, Jon; Layton-Matthews, Daniel; Watts, Anthony B

    2013-01-01

    Subduction of intraplate seamounts beneath a geochemically depleted mantle wedge provides a seldom opportunity to trace element recycling and mantle flow in subduction zones. Here we present trace element and Sr, Nd and Pb isotopic compositions of lavas from the central Tonga-Kermadec arc, west of the contemporary Louisville-Tonga trench intersection, to provide new insights into the effects of Louisville seamount subduction. Elevated (206)Pb/(204)Pb, (208)Pb/(204)Pb, (86)Sr/(87)Sr in lavas from the central Tonga-Kermadec arc front are consistent with localized input of subducted alkaline Louisville material (lavas and volcaniclastics) into sub-arc partial melts. Furthermore, absolute Pacific Plate motion models indicate an anticlockwise rotation in the subducted Louisville seamount chain that, combined with estimates of the timing of fluid release from the subducting slab, suggests primarily trench-normal mantle flow beneath the central Tonga-Kermadec arc system.

  19. Coherent neutrino-nucleus scattering detection with a CsI[Na] scintillator at the SNS spallation source

    NASA Astrophysics Data System (ADS)

    Collar, J. I.; Fields, N. E.; Hai, M.; Hossbach, T. W.; Orrell, J. L.; Overman, C. T.; Perumpilly, G.; Scholz, B.

    2015-02-01

    We study the possibility of using CsI[Na] scintillators as an advantageous target for the detection of coherent elastic neutrino-nucleus scattering (CENNS), using the neutrino emissions from the SNS spallation source at Oak Ridge National Laboratory. The response of this material to low-energy nuclear recoils like those expected from this process is characterized. Backgrounds are studied using a 2 kg low-background prototype crystal in a dedicated radiation shield. The conclusion is that a planned 14 kg detector should measure approximately 550 CENNS events per year above a demonstrated ~ 7 keVnr low-energy threshold, with a signal-to-background ratio sufficient for a first measurement of the CENNS cross-section. The cross-section for the 208Pb(νe ,e-)208Bi reaction, of interest for future supernova neutrino detection, can be simultaneously obtained.

  20. Excitations of one-valence-proton, one-valence-neutron nucleus {sup 210}Bi from cold-neutron capture

    SciTech Connect

    Cieplicka-Oryńczak, N.; Fornal, B.; Szpak, B.; Leoni, S.; Bottoni, S.; Bazzacco, D.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Bocchi, G.; France, G. de; Simpson, G.; Urban, W.

    2015-10-15

    The low-spin structure of one-proton, one-neutron {sup 210}Bi nucleus was investigated in cold-neutron capture reaction on {sup 209}Bi. The γ-coincidence measurements were performed with use of EXILL array consisted of 16 HPGe detectors. The experimental results were compared to shell-model calculations involving valence particles excitations. The {sup 210}Bi nucleus offers the potential to test the effective proton-neutron interactions because most of the states should arise from the proton-neutron excitations. Additionally, it was discovered that a few states should come from the couplings of valence particles to the 3{sup −} octupole vibration in {sup 208}Pb which provides also the possibility of testing the calculations involving the core excitations.

  1. nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties in the CTEQ framework

    DOE PAGES

    Kovarik, K.; Kusina, A.; Jezo, T.; ...

    2016-04-28

    We present the new nCTEQ15 set of nuclear parton distribution functions with uncertainties. This fit extends the CTEQ proton PDFs to include the nuclear dependence using data on nuclei all the way up to 208Pb. The uncertainties are determined using the Hessian method with an optimal rescaling of the eigenvectors to accurately represent the uncertainties for the chosen tolerance criteria. In addition to the Deep Inelastic Scattering (DIS) and Drell-Yan (DY) processes, we also include inclusive pion production data from RHIC to help constrain the nuclear gluon PDF. Here, we investigate the correlation of the data sets with specific nPDFmore » flavor components, and asses the impact of individual experiments. We also provide comparisons of the nCTEQ15 set with recent fits from other groups.« less

  2. Structure of the real part of the nucleon optical potential

    SciTech Connect

    Kadmensky, S.G.; Lyuboshitz, V.V.; Shaikina, A.A.

    1995-09-01

    The components of the nucleon optical potential V(l, E) in the {sup 208}Pb and {sup 40}Ca nuclei are calculated on the basis of the generalized Hartree-Fock potential and using typical sets of vacuum NN forces. The parameters of the isoscalar component of V(1, E) are found to agree well with those of phenomenological optical potentials and of the optical potentials in the Skyrme model. The isovector component of V(1, E) strongly depends on energy, and its value at E = 0 is considerably less than the corresponding values of the phenomenological and Skyrme optical potentials. This points to the necessity of additional tests of the underlying pair NN potentials. The radial distribution of V(1, E) is more complicated than the radial dependence of phenomenological optical potentials. 6 refs., 5 figs.

  3. Spin Observables in the Quasifree

    NASA Astrophysics Data System (ADS)

    Luther, Bryan Alan

    Theoretical calculations of the spin-isospin response in quasifree nucleon-nucleus scattering predicted a large enhancement in the ratio of the longitudinal to transverse response functions. Measurements using the (vec {p},vec{n}) reaction at an energy of 495 MeV and a momentum transfer of 1.7 fm ^{-1} did not show the expected enhancement. This work presents new 495 MeV measurements taken to investigate this surprising result. The cross section, induced polarization, analyzing power and D _{NN} were measured for ^{208}Pb at a momentum transfer of 1.7 fm^{-1}. In addition, the cross section and a complete set of spin observables were measured for ^2H and ^{12}C at 1.2 fm^ {-1}. The response ratio R_ {L}/R_{T} was extracted for ^2H and ^{12 }C. The ^{208}Pb data are remarkably similar to the ^{12 }C data taken at 1.7 fm^{ -1} as is the parity ratio. This strengthens the argument that the quasifree (vec{p },vec{n}) reaction is probing fundamental properties of the nuclear medium. The normalized response functions for ^{12}C at 1.2 fm^ {-1} show some deviation from unity but comparison with DWIA calculations by Ichimura and Kawahigashi shows that the data are consistent with a suppression of the signal of collective effects in the nuclear medium. This implies some mechanism is modifying the NN interaction in the nuclear medium. Theoretical calculations based on two different possible mechanisms are compared with the data. An RPWIA calculation by Horowitz and Piekarewicz shows a suppression of the collective response ratio through introduction of effective nucleon masses. Another method uses a density dependent rho mass as suggested by Brown and Wambach. A DWIA calculation by Ichimura and Kawahigashi using this mechanism fits the data well but requires an exceptionally small value for the effective rho mass.

  4. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    NASA Astrophysics Data System (ADS)

    Hu, Ningjing; Huang, Peng

    2016-04-01

    Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments Hu Ning-jinga, Huang Pengb,, Liu Ji-huaa, a First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China b Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8 ± 7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997 ± 0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477 ± 0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  5. Elemental fractionation in 785 nm picosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-05-01

    Elemental fractionation and ICP-MS signal response were investigated for two different pulse width laser beams originating from the same laser system. Femtosecond and picosecond laser beams at pulse widths of 130 fs and 110 ps, respectively, and wavelength of 785 nm were used to ablate NIST 610 synthetic glass and SRM 1107 Naval Brass B at the same spot for 800 to 1000 laser pulses at different repetition rates (5 to 50 Hz). Elemental fractionation was found to depend on repetition rate and showed a trend with femtosecond laser ablation that is opposite to that observed in picosecond laser ablation for most measured isotopes. ICP-MS signal intensity was higher in femtosecond than picosecond LA-ICP-MS in both NIST 610 and naval brass when ablation was conducted under the same fluence and repetition rate. The differences in signal intensity were partly related to differences in particle size distribution between particles generated by femtosecond and picosecond laser pulses and the consequent differences in transport and ionization efficiencies. The main reason for the higher signal intensity resulting from femtosecond laser pulses was related to the larger crater sizes compared to those created during picosecond laser ablation. Elemental ratios measured using 66Zn/63Cu, 208Pb/238U, 232Th/238U, 66Zn/232Th and 66Zn/208Pb were found to change with the number of laser pulses with data points being more scattered in picosecond than femtosecond laser pulses. Reproducibility of replicate measurements of signal intensities, fractionation and elemental ratios was better for fs-LA-ICP-MS (RSD ~ 3 to 6%) than ps-LA-ICP-MS (RSD ~ 7 to 11%).

  6. Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007-09).

    PubMed

    Farmer, John G; Graham, Margaret C; Eades, Lorna J; Lilly, Allan; Bacon, Jeffrey R

    2016-02-15

    Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon (206)Pb/(207)Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon (206)Pb/(207)Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of (208)Pb/(207)Pb vs. (208)Pb/(206)Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The (206)Pb/(207)Pb ratio of the organic top horizon in (ii) was unrelated to the (206)Pb/(207)Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the (206)Pb/(207)Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m(-2) were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean (206)Pb/(207)Pb ratio~1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column.

  7. Unified description of scattering and fusion phenomena in heavy-ion collisions

    SciTech Connect

    Sahu, Basudeb; Sahu, B. B.; Mallick, G. S.; Agarwalla, S. K.; Shastry, C. S.

    2008-02-15

    An analytical recursive formula of the partial-wave scattering matrix for the total effective complex potential of nucleus-nucleus collisions is derived to conveniently analyze the data of angular variations of elastic scattering cross sections. Further, another expression of cross sections for the absorption from arbitrarily small intervals is derived. This leads to the explanation of the fusion cross section ({sigma}{sub fus}) data at various incident center-of-mass energies E{sub c.m.} by collecting the absorption contributions in the interior region of the effective potential. This concept is akin to that used by Udagawa et al. in the calculation of fusion cross sections in elastic channels. The interaction potential considered in the analysis is energy independent and by virtue of its weakly absorbing character it supports resonance states in different partial-wave trajectories. Consequently, occurrence of these resonances is shown to be the physical origin of the observed oscillatory structure in the variation respect to energy of the quantity D(E{sub c.m.})=d{sup 2}(E{sub c.m.}{sigma}{sub fus})/dE{sub c.m.}{sup 2}, the second derivative of the product E{sub c.m.}{sigma}{sub fus} with respect to E{sub c.m.}. In this article, we investigate two well-known cases of heavy-ion collisions, namely {sup 12}C+{sup 208}Pb and {sup 16}O+{sup 208}Pb, and obtain simultaneous and very successful explanations of cross sections for elastic scattering and fusion and the results of D(E{sub c.m.}). These results obtained by using a somewhat novel and convenient method demonstrate the unified description of scattering and fusion for interacting heavy-ion systems.

  8. Regional lead isotope study of a polluted river catchment: River Wear, Northern England, UK.

    PubMed

    Shepherd, Thomas J; Chenery, Simon R N; Pashley, Vanessa; Lord, Richard A; Ander, Louise E; Breward, Neil; Hobbs, Susan F; Horstwood, Matthew; Klinck, Benjamin A; Worrall, Fred

    2009-08-15

    High precision, lead isotope analyses of archived stream sediments from the River Wear catchment, northeast England (1986-88), provide evidence for three main sources of anthropogenic lead pollution; lead mining, industrial lead emissions and leaded petrol. In the upper catchment, pollution is totally controlled and dominated by large lead discharges from historic mining centres in the North Pennine Orefield ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0744-2.0954 and 0.8413-0.8554 respectively). In the lower catchment, co-extensive with the Durham Coalfield and areas of high population density, pollution levels are lower and regionally more uniform. Isotope ratios are systematically higher than in the upper catchment ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0856-2.1397 and 0.8554-0.8896 respectively) and far exceed values determined for the geogenic regional background. Here, the pollution is characterised by the atmospheric deposition of industrial lead and petrol lead. Lead derived from the combustion of coal, although present, is masked by the other two sources. Recent sediments from the main channel of the River Wear are isotopically indistinguishable from older, low order stream sediments of the North Pennine Orefield, indicating that contamination of the river by lead mining waste (up to several 1000 mg/kg Pb at some locations) continues to pose an environmental problem; a pattern that can be traced all the way to the tidal reach. Using within-catchment isotope variation and sediment lead concentrations, estimates can be made of the discharges from discrete mines or groups of mines to the overall level of lead pollution in the River Wear. As well as providing information pertinent to source apportionment and on-going catchment remediation measures, the database is a valuable resource for epidemiologists concerned with the health risks posed by environmental lead.

  9. Lead isotopes and trace metal ratios of aerosols as tracers of Pb pollution sources in Kanpur, India

    NASA Astrophysics Data System (ADS)

    Sen, Indra; Bizimis, Michael; Tripathi, Sachchida; Paul, Debajyoti; Tyagi, Swati; Sengupta, Deep

    2015-04-01

    The anthropogenic flux of Pb in the Earth's surface is almost an order of magnitude higher than its corresponding natural flux [1]. Identifying the sources and pathways of anthropogenic Pb in environment is important because Pb toxicity is known to have adverse effects on human health. Pb pollution sources for America, Europe, and China are well documented. However, sources of atmospheric Pb are unknown in India, particularly after leaded gasoline was phased out in 2000. India has a developing economy with a rapidly emerging automobile and high temperature industry, and anthropogenic Pb emission is expected to rise in the next decade. In this study, we report on the Pb- isotope compositions and trace metal ratios of airborne particulates collected in Kanpur, an industrial city in northern India. The Pb concentration in the airborne particulate matter varies between 14-216 ng/m3, while the other heavy metals vary by factor of 10 or less, e.g. Cd=0.3-3 ng/m3, As=0.4-3.5 ng/m3, Zn=36-161 ng/m3, and Cu=3-22 ng/m3. The 206Pb/207Pb, 208Pb/206Pb, and 208Pb/207Pb vary between 1.112 - 1.129, 2.123-2.141, and 2.409-2.424 respectively, and are highly correlated with each other (R2>0.9). Pb isotopes and trace metal data reveals that coal combustion is the major source of anthropogenic Pb in the atmosphere, with limited contribution from mining and smelting processes. We further conclude that combination of Pb isotope ratios and V/Pb ratios are powerful tracers for Pb source apportionment studies, which is otherwise difficult to differentiate based only on Pb systematics [1] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol.(46), 8601-8609

  10. Petrogenesis of pegmatites and granites in southwestern Maine

    SciTech Connect

    Tomascak, P.B.; Walker, R.J.; Krogstad, E.J. . Dept. of Geology)

    1993-03-01

    Granitic pegmatites occurring near the town of Topsham in southwestern Maine are mineralogically diverse, featuring abundant dikes and contain rare earth element minerals as well as one pegmatite that contains Li minerals. The pegmatite series crops out near the Brunswick granite, a texturally diverse granitic pluton, and lies 13 km southeast of the Mississippian age Sebago batholith. Areas intruded by pegmatites that possess such different mineral assemblages are globally rare. The origins of these mixed'' pegmatite series have not been comprehensively investigated. There is no known pattern of regional zonation (mineral/chemical) among Topsham series pegmatites, hence simple fractionation processes are probably not responsible for the compositional variations. The authors are attempting to clarify pegmatite petrogenesis using common Pb isotopic ratios of feldspars and Sm-Nd isotopic data from whole rocks and minerals. Pb isotopic ratios from leached feldspars reflect the Pb ratios of the source from which they were derived. The range of Pb isotopic compositions of alkali feldspars from 7 granitic pegmatites is as follows: [sup 206]Pb/[sup 204]Pb = 18.5-19.1; [sup 207]Pb/[sup 204]Pb = 15.53-15.69; [sup 208]Pb/[sup 204]Pb = 38.3-38.6. The Brunswick granite has K-feldspars with [sup 206]Pb/[sup 204]Pb = 18.40-18.47, [sup 207]/[sup 204]Pb = 15.64-15.66 and [sup 208]Pb/[sup 204]Pb = 38.29-38.39. The Pb isotopic compositions of both pegmatites and granites are significantly more radiogenic than existing data for the Sebago granite and argue against the consanguinity of Topsham pegmatites and the Sebago batholith. These data instead support a genetic link between the pegmatites and the Brunswick granite, which ranges from a fine-grained two-mica granite to a garnet-bearing pegmatitic leucogranite.

  11. Global investigation of the fine structure of the isoscalar giant quadrupole resonance

    SciTech Connect

    Shevchenko, A.; Burda, O.; Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Carter, J.; Sideras-Haddad, E.; Cooper, G. R. J.; Fearick, R. W.; Foertsch, S. V.; Lawrie, J. J.; Neveling, R.; Smit, F. D.; Fujita, H.; Fujita, Y.; Lacroix, D.

    2009-04-15

    Fine structure in the region of the isoscalar giant quadrupole resonance (ISGQR) in {sup 58}Ni, {sup 89}Y, {sup 90}Zr, {sup 120}Sn, {sup 166}Er, and {sup 208}Pb has been observed in high-energy-resolution ({delta}E{sub 1/2}{approx_equal}35-50 keV) inelastic proton scattering measurements at E{sub 0}=200 MeV at iThemba LABS. Calculations of the corresponding quadrupole excitation strength functions performed within models based on the random-phase approximation (RPA) reveal similar fine structure when the mixing of one-particle one-hole states with two-particle two-hole states is taken into account. A detailed comparison of the experimental data is made with results from the quasiparticle-phonon model (QPM) and the extended time-dependent Hartree-Fock (ETDHF) method. For {sup 208}Pb, additional theoretical results from second RPA and the extended theory of finite Fermi systems (ETFFS) are discussed. A continuous wavelet analysis of the experimental and the calculated spectra is used to extract dominant scales characterizing the fine structure. Although the calculations agree with qualitative features of these scales, considerable differences are found between the model and experimental results and amongst different models. Within the framework of the QPM and ETDHF calculations it is possible to decompose the model spaces into subspaces approximately corresponding to different damping mechanisms. It is demonstrated that characteristic scales mainly arise from the collective coupling of the ISGQR to low-energy surface vibrations.

  12. Disturbance versus preservation of U-Th-Pb ages in monazite during fluid-rock interaction: textural, chemical and isotopic in situ study in microgranites (Velay Dome, France)

    NASA Astrophysics Data System (ADS)

    Didier, A.; Bosse, V.; Boulvais, P.; Bouloton, J.; Paquette, J.-L.; Montel, J.-M.; Devidal, J.-L.

    2013-06-01

    Monazite is extensively used to date crustal processes and is usually considered to be resistant to diffusive Pb loss. Nevertheless, fluid-assisted recrystallisation is known to be capable of resetting the monazite chronometer. This study focuses on chemical and isotopic disturbances in monazite grains from two microgranite intrusions in the French Central Massif (Charron and Montasset). Petrologic data and oxygen isotopes suggest that both intrusions have interacted with alkali-bearing hydrothermal-magmatic fluids. In the Charron intrusion, regardless of their textural location, monazite grains are sub-euhedral and cover a large domain of compositions. U-Pb chronometers yield a lower intercept age of 297 ± 4 Ma. An inherited component at 320 Ma is responsible for the scattering of the U-Th-Pb ages. The Montasset intrusion was later affected by an additional F-rich crustal fluid with crystallisation of Ca-REE-fluorocarbonates, fluorite, calcite and chloritisation. Pristine monazite is chemically homogeneous and displays 208Pb/232Th and 206Pb/238U concordant ages at 307 ± 2 Ma. By contrast, groundmass monazite shows dissolution-recrystallisation features associated with apatite and thorite precipitation (Th-silicate) and strong chemical reequilibration. 208Pb/232Th ages are disturbed and range between 270 and 690 Ma showing that the Th/Pb ratio is highly fractionated during the interaction with fluids. Apparent U-Pb ages are older due to common Pb incorporation yielding a lower intercept age at 312 ± 10 Ma, the age of the pristine monazite. These results show that F-rich fluids are responsible for Th mobility and incorporation of excess Pb, which thus strongly disturbed the U-Th-Pb chronometers in the monazite.

  13. Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Uranium-thorium-lead systematics of an Archean granite from the Owl Creek Mountains, Wyoming

    SciTech Connect

    Stuckless, J.S.; Nkomo, I.T.; Butt, K.A.

    1986-01-01

    Isotopic analyses of apparently unaltered whole-rock samples of a granite from the Owl Creek Mountains, Wyo., yield a lead-lead isochron age of 2730 {plus minus} 35 Ma, which is somewhat older than the age obtained by the rubidium-strontium whole-rock method. Thorium-lead data for the same samples deviate markedly from an isochronal relation; however, calculated initial {sup 208}Pb/{sup 204}Pb ratios correlate with whole-rock {delta}{sup 18}O values and lead to the conclusion that the {sup 232}Th-{sup 208}Pb data are not colinear because of an originally heterogeneous granitic magma. Relationships in the {sup 207}Pb/{sup 235}U-{sup 206}Pb/{sup 238}U system show that uranium was mobilized during early Laramide time or shortly before, such that most surface and shallow drill-core samples lost 60-80 percent of their uranium, and some fractured, deeper drill-core samples gained from 50 to 10,000 percent uranium. Fission-track maps show that much uranium is located along edges and cleavages of biotite and magnetic where it is readily accessible to oxidizing ground water. Furthermore, qualitative comparisons of uranium distribution in samples with excess radiogenic lead and in samples with approximately equilibrium amounts of uranium and lead suggest that the latter contain more uranium in these readily accessible sites. Unlike other granites that have uranium distributions and isotopic systematics similar to those observed in this study, the granite of the Owl Creek Mountains is not associated with economic uranium deposits.

  14. Historical reconstruction of atmospheric lead pollution in central Yunnan province, southwest China: an analysis based on lacustrine sedimentary records.

    PubMed

    Liu, Enfeng; Zhang, Enlou; Li, Kai; Nath, Bibhash; Li, Yanling; Shen, Ji

    2013-12-01

    Atmospheric lead (Pb) pollution during the last century in central Yunnan province, one of the largest non-ferrous metal production centers in China, was reconstructed using sediment cores collected from Fuxian and Qingshui Lakes. Lead concentrations and isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) were measured in sediment cores from both lakes. The operationally defined chemical fractions of Pb in sediment core from Fuxian Lake were determined by the optimized BCR procedure. The chronology of the cores was reconstructed using (210)Pb and (137)Cs dating methods. Similar three-phase variations in isotopic ratios and enrichment factors of Pb were observed in the sediment cores from both lakes. Before the 1950s, the sediment data showed low (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios and enrichment factors (EFs=~1), indicating that the sedimentary Pb was predominantly of lithogenic origin. However, these indices were increased gradually between the 1950s and the mid-1980s, implying an atmospheric Pb deposition. The EFs and isotopic ratios of Pb reached their peak during recent years, indicating aggravating atmospheric Pb pollution. The average anthropogenic Pb fluxes since the mid-1980s were estimated to be 0.032 and 0.053 g m(-2) year(-1) recorded in Fuxian and Qingshui cores, respectively. The anthropogenic Pb was primarily concentrated in the reducible fraction. Combining the results of Pb isotopic compositions and chemical speciations in the sediment cores and in potential sources, we deduced that recent aggravating atmospheric Pb pollution in central Yunnan province should primarily be attributed to regional emissions from non-ferrous metal production industries.

  15. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead

    NASA Astrophysics Data System (ADS)

    Yang, Sha; Liu, Yun

    2015-07-01

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs.

  16. The link between Hawaiian mantle plume composition, magmatic flux, and deep mantle geodynamics

    NASA Astrophysics Data System (ADS)

    Harrison, Lauren N.; Weis, Dominique; Garcia, Michael O.

    2017-04-01

    Oceanic island basalts sample mantle reservoirs that are isotopically and compositionally heterogeneous. The Hawaiian-Emperor chain represents ∼85 Myr of volcanism supplied by a deep mantle plume. Two geographically and geochemically delineated trends, Kea and Loa, are well documented within the Hawaiian Islands. Enriched Loa compositions originate from subduction recycled or primordial material stored in deep mantle reservoirs such as the large low shear velocity province (LLSVP) below Hawai'i. Loa compositions have not been observed along the Emperor Seamounts (>50 Ma), whereas lavas on the Hawaiian Islands (<6.5 Ma) sample both Kea and Loa sources. Lead isotopes in shield lavas along the Northwest Hawaiian Ridge (NWHR) spanning ∼42 Myr between the bend in the chain and the Hawaiian Islands record the geochemical evolution of the Hawaiian mantle plume over a time period when many geophysical parameters (volcanic propagation rate, magmatic flux, mantle potential temperature) increased significantly. Along the NWHR, the Loa geochemical component appears ephemerally, which we link to the sampling of different lower mantle compositional domains by the Hawaiian mantle plume. The plume initially sampled only the deep Pacific mantle (Kea component) from outside the LLSVP during the formation of the Emperor Seamounts. Southward migration and anchoring of the plume on the LLSVP led to entrainment of increasing amounts of LLSVP material (Loa component) along the NWHR as documented by an increase in 208Pb*/206Pb* with decreasing age. The correlation between 208Pb*/206Pb* and magmatic flux suggests source composition affects the magmatic flux, and explains why the Hawaiian mantle plume has dramatically strengthened through time.

  17. Separable representation of energy-dependent optical potentials

    NASA Astrophysics Data System (ADS)

    Hlophe, L.; Elster, Ch.

    2016-03-01

    Background: One important ingredient for many applications of nuclear physics to astrophysics, nuclear energy, and stockpile stewardship are cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not feasible, indirect methods, e.g., (d ,p ) reactions, should be used. Those (d ,p ) reactions may be viewed as three-body reactions and described with Faddeev techniques. Purpose: Faddeev equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. Optical potentials representing the effective interactions in the neutron (proton) nucleus subsystem are usually non-Hermitian as well as energy dependent. Potential matrix elements as well as transition matrix elements calculated with them must fulfill the reciprocity theorem. The purpose of this paper is to introduce a separable, energy-dependent representation of complex, energy-dependent optical potentials that fulfill reciprocity exactly. Methods: Momentum space Lippmann-Schwinger integral equations are solved with standard techniques to obtain the form factors for the separable representation. Results: Starting from a separable, energy-independent representation of global optical potentials based on a generalization of the Ernst-Shakin-Thaler (EST) scheme, a further generalization is needed to take into account the energy dependence. Applications to n +48Ca ,n +208Pb , and p +208Pb are investigated for energies from 0 to 50 MeV with special emphasis on fulfilling reciprocity. Conclusions: We find that the energy-dependent separable representation of complex, energy-dependent phenomenological optical potentials fulfills reciprocity exactly. In addition, taking into account the explicit energy dependence slightly improves the description of the S matrix elements.

  18. Transition from quasi-elastic to deep-inelastic reactions

    SciTech Connect

    Rehm, K.E.

    1986-01-01

    Heavy ion induced transfer reactions are usually considered to fall into two categories. Quasi-elastic processes, on one hand, are characterized by small energy transfers, with one-nucleon transfer reactions being a typical example. These processes are dominant for grazing collisions, and are generally described within simple one-step DWBA calculations. Deep inelastic reactions, on the other hand, occur for more central collisions where the interaction time is longer and subsequently more energy and particles can be exchanged. Quasi-elastic collisions dominate transfer reactions induced by light heavy ions (e.g., /sup 16/O) at energies not too high above the barrier, while deep inelastic collisions are observed mainly in reactions induced by heavier projectiles (Kr, Xe). In this contribution, we discuss the transition between these two processes for the system /sup 48/Ti + /sup 208/Pb. /sup 48/Ti is located between light (/sup 16/O) and heavy (Kr) projectiles and should be well suited for a study of the interrelation between quasi- and deep-inelastic reactions. The experiments were performed with a 300 MeV /sup 48/Ti beam obtained from the Argonne National Laboratory superconducting linac. The outgoing particles were momentum analyzed in a split pole magnetic spectrograph and detected in the focal plane by a position sensitive ionization chamber. The specific energy loss, the magnetic rigidity and the total energy of the outgoing particles were measured enabling mass and Z-identification. The energy resolution was about 3 MeV, determined by the thickness of the /sup 208/Pb target, and thus excluded study of transfer reactions to discrete final states. Angular distributions were measured in the range theta/sub lab/ = 20/sup 0/ to 80/sup 0/ in steps of 5/sup 0/. 8 refs.

  19. Nuclear Structure Measurements of Fermium-254 and Advances in Target Production Methodologies

    NASA Astrophysics Data System (ADS)

    Gothe, Oliver Ralf

    The Berkeley Gas-filled Separator (BGS) has been upgraded with a new gas control system. It allows for accurate control of hydrogen and helium gas mixtures. This greatly increases the capabilities of the separator by reducing background signals in the focal plane detector for asymmetric nuclear reactions. It has also been shown that gas mixtures can be used to focus the desired reaction products into a smaller area, thereby increasing the experimental efficiency. A new electrodeposition cell has been developed to produce metal oxide targets for experiments at the BGS. The new cell has been characterized and was used to produce americium targets for the production of element 115 in the reaction 243Am(48Ca.3n) 288115. Additionally, a new method of producing targets for nuclear reactions was explored. A procedure for producing targets via Polymer Assisted Deposition (PAD) was developed and targets produced via this method were tested using the nuclear reaction 208Pb(40Ar.4 n)244Fm to determine their in-beam performance. It was determined that the silicon nitride backings used in this procedure are not feasible due to their crystal structures, and alternative backing materials have been tested and proposed. A previously unknown level in 254Fm has been identified at 985.7 keV utilizing a newly developed low background coincident apparatus. 254m was produced in the reaction 208Pb(48Ca. n)254No. Reaction products were guided to the two-clover low background detector setup via a recoil transfer chamber. The new level has been assigned a spin of 2- and has tentatively been identified as the octupole vibration in 254Fm. Transporting evaporation residues to a two-clover, low background detector setup can effectively be used to perform gamma-spectroscopy measurements of nuclei that are not accessible by current common methodologies. This technique provides an excellent addition to previously available tools such as in-beam spectroscopy and gamma-ray tracking arrays.

  20. Isotopic identification of natural vs. anthropogenic lead sources in marine sediments from the inner Ría de Vigo (NW Spain).

    PubMed

    Álvarez-Iglesias, P; Rubio, B; Millos, J

    2012-10-15

    San Simón Bay, the inner part of the Ría de Vigo (NW Spain), an area previously identified as highly polluted by Pb, was selected for the application of Pb stable isotope ratios as a fingerprinting tool in subtidal and intertidal sediment cores. Lead isotopic ratios were determined by inductively coupled plasma mass spectrometry on extracts from bulk samples after total acid digestion. Depth-wise profiles of (206)Pb/(207)Pb, (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb and (208)Pb/(207)Pb ratios showed, in general, an upward decrease for both intertidal and subtidal sediments as a consequence of the anthropogenic activities over the last century, or centuries. Waste channel samples from a nearby ceramic factory showed characteristic Pb stable isotope ratios different from those typical of coal and petrol. Natural isotope ratios from non-polluted samples were established for the study area, differentiating sediments from granitic or schist-gneiss sources. A binary mixing model employed on the polluted samples allowed estimating the anthropogenic inputs to the bay. These inputs represented between 25 and 98% of Pb inputs in intertidal samples, and 9-84% in subtidal samples, their contributions varying with time. Anthropogenic sources were apportioned according to a three-source model. Coal combustion-related emissions were the main anthropogenic source Pb to the bay (60-70%) before the establishment of the ceramic factory in the area (in the 1970s) which has since constituted the main source (95-100%), followed by petrol-related emissions. The Pb inputs history for the intertidal area was determined for the 20th century, and, for the subtidal area, the 19th and 20th centuries.

  1. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead.

    PubMed

    Yang, Sha; Liu, Yun

    2015-07-30

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wave function. Equilibrium (202)Hg/(198)Hg, (205)Tl/(203)Tl, (207)Pb/(206)Pb and (208)Pb/(206)Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of [formula in text] for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb(4+)-bearing species are found can enrich heavier Pb isotopes than Pb(2+)-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of (208)Pb/(206)Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb(2+)-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., [formula in text]) and odd-mass MIFs (i.e., [formula in text) are almost the same but with opposite signs.

  2. Isotopic source signatures for atmospheric lead: the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Bollhöfer, A.; Rosman, K. J. R.

    2000-10-01

    Aerosols collected between 1994 and 1999 at more than 70 different sites affecting the Southern Hemisphere have been measured for their 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios and Pb concentrations. Lower ratios are found at the southern tips of Africa, Australia and South America probably due to the supply of alkyllead from a common supplier such as Associated Octel. The ratios increase in a northerly direction probably due to a changing market share in alkyllead or an increasing industrial Pb contribution. The geographical variations in isotopic signatures made it possible to broadly characterize the different regions that influence the Southern Hemisphere. Brazil and Argentina exhibited 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios in aerosols of 1.141-1.184, 2.416-2.442 and 17.77-18.57, respectively. Mexican aerosols had values of 1.188-1.197, 2.452-2.463 and 18.46-18.73. Aerosols sampled in Chile had low ratios in the South of 1.063-1.094, 2.337-2.373 and 16.46-17.13 which increased in a northerly direction. Emissions from South Africa were characterized by ratios 1.067-1.090, 2.340-2.358 and 16.53-16.99. In 1994-1995 Australia and New Zealand had ratios of 1.060-1.193, 2.324-2.445 and 16.08-18.54. In 1997 however, the range was narrower: 1.072-1.112, 2.342-2.398 and 16.55-17.36, respectively. These isotopic signatures are potentially useful for tracing sources of pollution and the movement of air-masses on a global scale.

  3. A comparison of the isotopic composition of lead in rainwater, surface vegetation and tree bark at the long-term monitoring site, Glensaugh, Scotland, in 2007.

    PubMed

    Farmer, John G; Eades, Lorna J; Graham, Margaret C; Cloy, Joanna M; Bacon, Jeffrey R

    2010-08-01

    The lead concentrations and isotopic ratios (206Pb/207Pb, 208Pb/206Pb, 208Pb/207Pb) of 31 rainwater (September 2006-December 2007) and 11 surface vegetation (moss, lichen, heather) samples (October 2007) from the rural upland catchment of Glensaugh in northeast Scotland and of nine bark samples (October 2007) from trees, predominantly Scots pine, in or near Glensaugh were determined. The mean 206Pb/207Pb ratios for rainwater in 2006 and 2007 were similar to those previously determined for 2000 to 2003 at Glensaugh, yielding an average mean annual value of 1.151+/-0.005 (+/-1 SD) for the period from 2000, when an outright ban on leaded petrol came into force in the UK, to 2007. The mean 206Pb/207Pb ratio (1.146+/-0.004; n=7) for surface vegetation near the top (430-450 m) of the catchment was not significantly different (Student's t test) from that of rainwater (1.148+/-0.017; n=24) collected over the 12-month period prior to vegetation sampling, but both were significantly different, at the 0.1% (i.e. p<0.001) and 1% (p<0.01) level, respectively, from the corresponding mean value (1.134+/-0.006; n=9) for the outermost layer of tree bark. When considered in conjunction with similar direct evidence for 2002 and indirect evidence (e.g. grass, atmospheric particulates, dated peat) for recent decades in the Glensaugh area, these findings confirm that the lead isotopic composition of surface vegetation, including that of suitably located moss, reflects that of the atmosphere while that of the outermost layer of Scots pine bark is affected by non-contemporaneous lead. The nature and relative extent of the different contributory sources of lead to the current UK atmosphere in the era of unleaded petrol, however, are presently not well characterised on the basis of lead isotopic measurements.

  4. Investigation of Lead Target Nuclei Used on Accelerator-Driven Systems for Tritium Production

    NASA Astrophysics Data System (ADS)

    Tel, E.; Aydin, A.

    2012-02-01

    High-current proton accelerators are being researched at Los Alamos National Laboratory and other laboratories for accelerator production of tritium, transmuting long-lived radioactive waste into shorter-lived products, converting excess plutonium, and producing energy. These technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. Through ( p,xn) and ( n,xn) nuclear reactions, neutrons are produced and are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial fusion power plant. Rubbia succeeded in a proposal of a full scale demonstration plant of the Energy Amplifier. This plant is to be known the accelerator-driven system (ADS). The ADS can be used for production of neutrons in spallation neutron source and they can act as an intense neutron source in accelerator-driven subcritical reactors, capable of incinerating nuclear waste and of producing energy. Thorium and Uranium are nuclear fuels and Lead, Bismuth, Tungsten are the target nuclei in these reactor systems. The spallation targets can be Pb, Bi, W, etc. isotopes and these target material can be liquid or solid. Naturally Lead includes the 204Pb (%1.42), 206Pb (%24.1), 207Pb (%22.1) and 208Pb (%52.3) isotopes. The design of ADS systems and also a fusion-fission hybrid reactor systems require the knowledge of a wide range of better data. In this study, by using Hartree-Fock method with an effective nucleon-nucleon Skyrme interactions rms nuclear charge radii, rms nuclear mass radii, rms nuclear proton, neutron radii and neutron skin thickness were calculated for the 204, 206, 208Pb isotopes . The calculated results have been compared with those of the compiled experimental and theoretical values of other studies.

  5. Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination.

    PubMed

    Rankin, Charley W; Nriagu, Jerome O; Aggarwal, Jugdeep K; Arowolo, Toyin A; Adebayo, Kola; Flegal, A Russell

    2005-10-01

    In this article we present lead concentrations and isotopic compositions from analyses of cocoa beans, their shells, and soils from six Nigerian cocoa farms, and analyses of manufactured cocoa and chocolate products. The average lead concentration of cocoa beans was 208Pb/207Pb = 2.4344-2.4394) with those of finished cocoa products (206Pb/207Pb = 1.1475-1.1977; 208Pb/207Pb = 2.4234-2.4673). However, the much higher lead concentrations and larger variability in lead isotopic composition of finished cocoa products, which falls within the global range of industrial lead aerosols, indicate that most contamination occurs during shipping and/or processing of the cocoa beans and the manufacture of cocoa and chocolate products.

  6. Lead shot contribution to blood lead of First Nations people: the use of lead isotopes to identify the source of exposure.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-11-01

    Although lead isotope ratios have been used to identify lead ammunition (lead shotshell pellets and bullets) as a source of exposure for First Nations people of Canada, the actual source of lead exposure needs to be further clarified. Whole blood samples for First Nations people of Ontario, Canada, were collected from participants prior to the traditional spring harvest of water birds, as well as post-harvest. Blood-lead levels and stable lead isotope ratios prior to, and after the harvest were determined by ICP-MS. Data were analyzed by paired t-tests and Wilcoxon Signed-Ranks tests. All participants consumed water birds harvested with lead shotshell during the period of study. For the group excluding six males who were potentially exposed to other sources of lead (as revealed through a questionnaire), paired t-tests and Wilcoxon Signed-Ranks tests showed consistent results: significant (p<0.05) increases in blood-lead concentrations and blood levels of (206)Pb/(204)Pb and (206)Pb/(207)Pb towards the mean values we previously reported for lead shotshell pellets; and a significant decrease in (208)Pb/(206)Pb values towards the mean for lead shotshell pellets. However, when we categorized the group further into a group that did not use firearms and did not eat any other traditional foods harvested with lead ammunition other than waterfowl, our predictions for (206)Pb/(204)Pb, (206)Pb/(207)Pb and (208)Pb/(206)Pb hold true, but there was not a significant increase in blood-lead level after the hunt. It appears that the activity of hunting (i.e., use of a shotgun) was also an important route of lead exposure. The banning of lead shotshell for all game hunting would eliminate a source of environmental lead for all people who use firearms and/or eat wild game.

  7. Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil.

    PubMed

    Yu, Yang; Li, Yingxia; Li, Ben; Shen, Zhenyao; Stenstrom, Michael K

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources.

  8. Formation of superheavy elements in cold fusion reactions

    NASA Astrophysics Data System (ADS)

    Smolańczuk, Robert

    2001-04-01

    We calculate the formation cross sections of transactinides (superheavy elements), as well as heavy actinides (No and Lr), which have been or might be obtained in fusion reactions with the evaporation of only one neutron. We use both more realistic fusion barrier and survival probability of the compound nucleus in comparison with the original phenomenological model [Phys. Rev. C 59, 2634 (1999)] that prompted the Berkeley experiment on the synthesis of a new superheavy element 118 [Phys. Rev. Lett. 83, 1104 (1999)]. Calculations are performed for asymmetric and symmetric target-projectile combinations and for reactions with stable and radioactive-ion beams. The formation cross sections measured at GSI-Darmstadt for transactinides and heavy actinides, as well as that for superheavy element 118 reported by the LBNL-Berkeley group, are reproduced within a factor of 2.4, on average. Based on the obtained relatively large cross sections, we predict that optimal reactions with stable beams for the synthesis of so far unobserved superheavy elements 119, 120, and 121 are 209Bi(86Kr, 1n)294119, 208Pb(88Sr, 1n)295120, and 209Bi(88Sr, 1n)296121, respectively. This is because of the magic of both the target and the projectile that leads to larger Q value and, consequently, lower effective fusion barrier with larger transmission probability. The same effect is responsible for relatively large cross sections predicted for the symmetric reactions 136Xe(124Sn, 1n)259Rf, 136Xe(136Xe, 1n)271Hs,138Ba(136Xe, 1n)273110, and 140Ce(136Xe, 1n)275112. Although shell effects in the magic nuclei 124Sn, 136Xe, 138Ba, and 140Ce are not as strong as in 208Pb and 209Bi, they act on both the target and the projectile and lead to the prediction of measurable cross sections.

  9. Microprocessor dynamics and interactions at endogenous imprinted C19MC microRNA genes.

    PubMed

    Bellemer, Clément; Bortolin-Cavaillé, Marie-Line; Schmidt, Ute; Jensen, Stig Mølgaard Rask; Kjems, Jørgen; Bertrand, Edouard; Cavaillé, Jérôme

    2012-06-01

    Nuclear primary microRNA (pri-miRNA) processing catalyzed by the DGCR8-Drosha (Microprocessor) complex is highly regulated. Little is known, however, about how microRNA biogenesis is spatially organized within the mammalian nucleus. Here, we image for the first time, in living cells and at the level of a single microRNA cluster, the intranuclear distribution of untagged, endogenously-expressed pri-miRNAs generated at the human imprinted chromosome 19 microRNA cluster (C19MC), from the environment of transcription sites to single molecules of fully released DGCR8-bound pri-miRNAs dispersed throughout the nucleoplasm. We report that a large fraction of Microprocessor concentrates onto unspliced C19MC pri-miRNA deposited in close proximity to their genes. Our live-cell imaging studies provide direct visual evidence that DGCR8 and Drosha are targeted post-transcriptionally to C19MC pri-miRNAs as a preformed complex but dissociate separately. These dynamics support the view that, upon pri-miRNA loading and most probably concomitantly with Drosha-mediated cleavages, Microprocessor undergoes conformational changes that trigger the release of Drosha while DGCR8 remains stably bound to pri-miRNA.

  10. SUMOylation at K707 of DGCR8 controls direct function of primary microRNA

    PubMed Central

    Zhu, Changhong; Chen, Cheng; Huang, Jian; Zhang, Hailong; Zhao, Xian; Deng, Rong; Dou, Jinzhuo; Jin, Hui; Chen, Ran; Xu, Ming; Chen, Qin; Wang, Yanli; Yu, Jianxiu

    2015-01-01

    DGCR8 (DiGeorge syndrome critical region gene 8) is essential for primary microRNA (pri-miRNA) processing in the cell nucleus. It specifically combines with Drosha, a nuclear RNase III enzyme, to form the Microprocessor complex (MC) that cleaves pri-miRNA to precursor miRNA (pre-miRNA), which is further processed to mature miRNA by Dicer, a cytoplasmic RNase III enzyme. Increasing evidences suggest that pri-/pre-miRNAs have direct functions in regulation of gene expression, however the underlying mechanism how it is fine-tuned remains unclear. Here we find that DGCR8 is modified by SUMO1 at the major site K707, which can be promoted by its ERK-activated phosphorylation. SUMOylation of DGCR8 enhances the protein stability by preventing the degradation via the ubiquitin proteasome pathway. More importantly, SUMOylation of DGCR8 does not alter its association with Drosha, the MC activity and miRNA biogenesis, but rather influences its affinity with pri-miRNAs. This altered affinity of DGCR8 with pri-miRNAs seems to control the direct functions of pri-miRNAs in recognition and repression of the target mRNAs, which is evidently linked to the DGCR8 function in regulation of tumorigenesis and cell migration. Collectively, our data suggest a novel mechanism that SUMOylation of DGCR8 controls direct functions of pri-miRNAs in gene silencing. PMID:26202964

  11. Selective inhibitor of Wnt/β-catenin/CBP signaling ameliorates hepatitis C virus-induced liver fibrosis in mouse model.

    PubMed

    Tokunaga, Yuko; Osawa, Yosuke; Ohtsuki, Takahiro; Hayashi, Yukiko; Yamaji, Kenzaburo; Yamane, Daisuke; Hara, Mitsuko; Munekata, Keisuke; Tsukiyama-Kohara, Kyoko; Hishima, Tsunekazu; Kojima, Soichi; Kimura, Kiminori; Kohara, Michinori

    2017-03-23

    Chronic hepatitis C virus (HCV) infection is one of the major causes of serious liver diseases, including liver cirrhosis. There are no anti-fibrotic drugs with efficacy against liver cirrhosis. Wnt/β-catenin signaling has been implicated in the pathogenesis of a variety of tissue fibrosis. In the present study, we investigated the effects of a β-catenin/CBP (cyclic AMP response element binding protein) inhibitor on liver fibrosis. The anti-fibrotic activity of PRI-724, a selective inhibitor of β-catenin/CBP, was assessed in HCV GT1b transgenic mice at 18 months after HCV genome expression. PRI-724 was injected intraperitoneally or subcutaneously in these mice for 6 weeks. PRI-724 reduced liver fibrosis, which was indicated by silver stain, Sirius Red staining, and hepatic hydroxyproline levels, in HCV mice while attenuating αSMA induction. PRI-724 led to increased levels of matrix metalloproteinase (MMP)-8 mRNA in the liver, along with elevated levels of intrahepatic neutrophils and macrophages/monocytes. The induced intrahepatic neutrophils and macrophages/monocytes were identified as the source of MMP-8. In conclusion, PRI-724 ameliorated HCV-induced liver fibrosis in mice. We hypothesize that inhibition of hepatic stellate cells activation and induction of fibrolytic cells expressing MMP-8 contribute to the anti-fibrotic effects of PRI-724. PRI-724 is a drug candidate which possesses anti-fibrotic effect.

  12. Integrating Chlorophyll fapar and Nadir Photochemical Reflectance Index from EO-1/Hyperion to Predict Cornfield Daily Gross Primary Production

    NASA Technical Reports Server (NTRS)

    Zhang, Qingyuan; Middleton, Elizabeth M.; Cheng, Yen-Ben; Huemmrich, K. Fred; Cook, Bruce D.; Corp, Lawrence A.; Kustas, William P.; Russ, Andrew L.; Prueger, John H.; Yao, Tian

    2016-01-01

    The concept of light use efficiency (Epsilon) and the concept of fraction of photosynthetically active ration (PAR) absorbed for vegetation photosynthesis (PSN), i.e., fAPAR (sub PSN), have been widely utilized to estimate vegetation gross primary productivity (GPP). It has been demonstrated that the photochemical reflectance index (PRI) is empirically related to e. An experimental US Department of Agriculture (USDA) cornfield in Maryland was selected as our study field. We explored the potential of integrating fAPAR(sub chl) (defined as the fraction of PAR absorbed by chlorophyll) and nadir PRI (PRI(sub nadir)) to predict cornfield daily GPP. We acquired nadir or near-nadir EO-1/Hyperion satellite images that covered the cornfield and took nadir in-situ field spectral measurements. Those data were used to derive the PRI(sub nadir) and fAPAR (sub chl). The fAPAR (sub chl) is retrieved with the advanced radiative transfer model PROSAIL2 and the Metropolis approach, a type of Markov Chain Monte Carlo (MCMC) estimation procedure. We define chlorophyll light use efficiency Epsilon (sub chl) as the ratio of vegetation GPP as measured by eddy covariance techniques to PAR absorbed by chlorophyll (Epsilon(sub chl) = GPP/APAR (sub chl). Daily Epsilon (sub chl) retrieved with the EO-1 Hyperion images was regressed with a linear equation of PRI (sub nadir) Epsilon (sub chl) = Alpha × PRI (sub nadir) + Beta). The satellite Epsilon(sub chl- PRI (sub nadir) linear relationship for the cornfield was implemented to develop an integrated daily GPP model [GPP = (Alpha × PRI(sub nadir) + Beta) × fAPAR (sub chl) × PAR], which was evaluated with fAPAR (sub chl) and PRI (sub nadir) retrieved from field measurements. Daily GPP estimated with this fAPAR (sub chl-) PRI (nadir) integration model was strongly correlated with the observed tower in-situ daily GPP (R(sup 2) = 0.93); with a root mean square error (RMSE) of 1.71 g C mol-(sup -1) PPFD and coefficient of variation (CV) of 16

  13. TUNS user guide supplement: Data dictionary

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Provided is a data dictionary for the Technology Utilization Network System (TUNS) providing for each element name the long name, data type, data size, descriptive name and description, data of PRI clause, legal values, and location used.

  14. Developing a Roadmap for Integrating Computational and In Vitro Approaches in Risk-Based Chemical Safety Decisions (SSCT-SweTox)

    EPA Science Inventory

    Multiple drivers shape the types of chemical assessments performed within many regulatory agencies including economic considerations, data availability, and the ultimate application of the assessment. The result is that chemical assessments are “fit-for-purpose” ranging from pri...

  15. Two-coordinate terminal zinc hydride complexes: synthesis, structure and preliminary reactivity studies.

    PubMed

    Dawkins, Michael J C; Middleton, Ewart; Kefalidis, Christos E; Dange, Deepak; Juckel, Martin M; Maron, Laurent; Jones, Cameron

    2016-08-18

    The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = -N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R'-2,6,4; R = Me, R' = Pr(i) (L'); R = Pr(i), R' = Me (L*); R = Pr(i), R' = Pr(i) (L(†))) have been prepared and shown by crystallographic studies to have near linear N-Zn-H fragments. The results of computational studies imply that any PhZn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds.

  16. Quasi-Square Hole with Optimum Shape in an Infinite Plate Subjected to In-Plane Loading. Optimization of Inner and Outer Boundaries of Beams and Plates with Holes,

    DTIC Science & Technology

    1982-04-01

    Professr Isaac Pried Library Se-vices Department P. 0. Box 158 Boeton University 9700 South Case Avenue Madison, Pennsylvania 15663 Department of Mathanatics Argonne, Illinois 60440 Boton, Massachusetts 02215 -3- .JAL

  17. Solution Method of Multi-Product Two-Stage Logistics Problem with Constraints of Delivery Course

    NASA Astrophysics Data System (ADS)

    Ataka, Shinichiro; Gen, Mitsuo

    The logistics network design is one of the important phase of Supply Chain Management (SCM) and it is the problem that should be optimized for long-term promotion of efficiency of the whole supply chain. Usually a plant produces different type of products. Even if it is a factory of the same company, delivery is different by a kind of a produced product. The restrictions which this model has are deeply concerned with TP in the real world. In this paper, we consider the logistics network design problems with multi-products and constraints for delivery course. To solve the problem, we used a hybrid priority-based Genetic Algorithm (h-priGA), and we tried the comparison experiment with priority-based Genetic Algorithm (priGA)and h-priGA, we show it about the effectiveness of h-priGA.

  18. Vasodilator-stimulated phosphoprotein-phosphorylation assay in patients on clopidogrel: does standardisation matter?

    PubMed

    Freynhofer, Matthias K; Bruno, Veronika; Willheim, Martin; Hübl, Wolfgang; Wojta, Johann; Huber, Kurt

    2012-03-01

    The vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) flow-cytometric assay is mainly used in clinical trials to measure thienopyridine effects. However, there are remarkable differences in the reported optimal cut-offs, ranging from 48-61% platelet reactivity index (PRI). We therefore investigated whether a lack of standardisation might explain the differences in the cut-offs. We measured VASP-P in 62 individuals. PRI was calculated using the mean, geometric mean and median fluorescence intensities (FI). Stability of the blood-samples (time-to-assay, 0-2 days) and stability of the processed samples (0-120 minutes) within the recommended time-span were tested. Time-to-assay significantly influenced the PRI (p<0.001): the PRI from mean FI after two days was lower compared to values on day 1 (52 ± 22.9 vs. 57.7 ± 24.1, p<0.001). The PRI from the geometric mean FI after two days was lower compared to day 0 as well as day 1 (51.3 ± 23 vs. 58.2 ± 24.2 and vs. 59.1 ± 23.7, both p<0.001). The PRI from median FI was stable over time (day 0: 59.1 ± 25%, day 1: 59.7 ± 24.1% and day 2: 56.4 ± 23.9%, all p=ns). Furthermore, the lag time of the processed samples significantly altered the PRI (all p<0.001) with a maximum difference for PRI based on geometric mean FI after 90 minutes compared to baseline (Δ=3.92%PRI, p<0.001). The differences in the reported cut-offs might be explained by a lack of standardisation. More precise standardisation is inevitable, as the PRI significantly depends on the method of calculation, the time-to-assay as well as on the lag time after processing. Tolerably stable results were obtained for the PRI from the median FI.

  19. Availability Estimate of a Conceptual ESM System.

    DTIC Science & Technology

    1979-06-01

    effect transistors (GaAs FET) 23% Microwave diodes 21% Coax connectors 12% Ferrite isolators 12% Bandpass filters 8% Integrated circuits, linear 10...determination, pulse repetition interval (PRI) determination, and bearing determination to within a quadrant or better. Signal levels across the antenna ...intercept. It involves frequency and PRI determination and computer sorting for threats. Signal levels across the antenna may be down as much as 17 dB

  20. Reasons Military Patients with Primary Care Access Leave an Emergency Department Waiting Room Before Seeing a Provider

    DTIC Science & Technology

    2012-10-01

    department, leave without being seen, pri mary care access, wait times Emergency department (ED) waiting rooms can be anxietyprovoking, uncomfortable, and...Our patients, despite being in a closed healthcare system with ready access to care, identified long wait times as the pri- mary reason they left... Somerville , Everett. http://www.boston.com/yourtown/news/ cambridge/2011/02/check cambridge hospital emerg.html. Accessed February 21, 2012. 19. In an

  1. Photoperiod and temperature constraints on the relationship between the photochemical reflectance index and the light use efficiency of photosynthesis in Pinus strobus.

    PubMed

    Fréchette, Emmanuelle; Chang, Christine Yao-Yun; Ensminger, Ingo

    2016-03-01

    The photochemical reflectance index (PRI) is a proxy for the activity of the photoprotective xanthophyll cycle and photosynthetic light use efficiency (LUE) in plants. Evergreen conifers downregulate photosynthesis in autumn in response to low temperature and shorter photoperiod, and the dynamic xanthophyll cycle-mediated non-photochemical quenching (NPQ) is replaced by sustained NPQ. We hypothesized that this shift in xanthophyll cycle-dependent energy partitioning during the autumn is the cause for variations in the PRI-LUE relationship. In order to test our hypothesis, we characterized energy partitioning and pigment composition during a simulated summer-autumn transition in a conifer and assessed the effects of temperature and photoperiod on the PRI-LUE relationship. We measured gas exchange, chlorophyll fluorescence and leaf reflectance during the photosynthetic downregulation in Pinus strobus L. seedlings exposed to low temperature/short photoperiod or elevated temperature/short photoperiod conditions. Shifts in energy partitioning during simulated autumn were observed when the pools of chlorophylls decreased and pools of photoprotective carotenoids increased. On a seasonal timescale, PRI was controlled by carotenoid pool sizes rather than xanthophyll cycle dynamics. Photochemical reflectance index variation under cold autumn conditions mainly reflected long-term pigment pool adjustments associated with sustained NPQ, which impaired the PRI-LUE relationship. Exposure to warm autumn conditions prevented the induction of sustained NPQ but still impaired the PRI-LUE relationship. We therefore conclude that alternative zeaxanthin-independent NPQ mechanisms, which remain undetected by the PRI, are present under both cold and warm autumn conditions, contributing to the discrepancy in the PRI-LUE relationship during autumn.

  2. Integrating Solar Induced Fluorescence and the Photochemical Reflectance Index for Estimating Gross Primary Production in a Cornfield

    NASA Technical Reports Server (NTRS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Zhang, Qingyuan; Huemmrich, Karl F.; Campbell, Petya K. E.; Corp, Lawrence A.; Cook, Bruce D.; Kustas, William P.; Daughtry, Criag S.

    2013-01-01

    The utilization of remotely sensed observations for light use efficiency (LUE) and tower-based gross primary production (GPP) estimates was studied in a USDA cornfield. Nadir hyperspectral reflectance measurements were acquired at canopy level during a collaborative field campaign conducted in four growing seasons. The Photochemical Reflectance Index (PRI) and solar induced chlorophyll fluorescence (SIF), were derived. SIF retrievals were accomplished in the two telluric atmospheric oxygen absorption features centered at 688 nm (O2-B) and 760 nm (O2-A). The PRI and SIF were examined in conjunction with GPP and LUE determined by flux tower-based measurements. All of these fluxes, environmental variables, and the PRI and SIF exhibited diurnal as well as day-to-day dynamics across the four growing seasons. Consistent with previous studies, the PRI was shown to be related to LUE (r2 = 0.54 with a logarithm fit), but the relationship varied each year. By combining the PRI and SIF in a linear regression model, stronger performances for GPP estimation were obtained. The strongest relationship (r2 = 0.80, RMSE = 0.186 mg CO2/m2/s) was achieved when using the PRI and SIF retrievals at 688 nm. Cross-validation approaches were utilized to demonstrate the robustness and consistency of the performance. This study highlights a GPP retrieval method based entirely on hyperspectral remote sensing observations.

  3. Processing of microRNA primary transcripts requires heme in mammalian cells.

    PubMed

    Weitz, Sara H; Gong, Ming; Barr, Ian; Weiss, Shimon; Guo, Feng

    2014-02-04

    DiGeorge syndrome critical region gene 8 (DGCR8) is the RNA-binding partner protein of the nuclease Drosha. DGCR8 and Drosha recognize and cleave primary transcripts of microRNAs (pri-miRNAs) in the maturation of canonical microRNAs (miRNAs) in animals. We previously reported that human, frog, and starfish DGCR8 bind heme when expressed in Escherichia coli and that Fe(III) heme activates apoDGCR8 in reconstituted pri-miRNA processing assays. However, the physiological relevance of heme in miRNA maturation has not been clear. Here, we present a live-cell pri-miRNA processing assay that produces robust signals and faithfully indicates DGCR8 and Drosha activities. We demonstrate that all known heme-binding-deficient DGCR8 mutants are defective in pri-miRNA processing in HeLa cells. DGCR8 contains a previously uncharacterized heme-binding motif, "IPCL," that is also required for its activity. Heme availability and biosynthesis in HeLa cells positively affect pri-miRNA processing and production of mature miRNA. These results establish an essential function for heme in pri-miRNA processing in mammalian cells. Our study suggests that abnormal heme biosynthesis and degradation may contribute to diseases via miRNA-mediated gene regulation networks.

  4. Global Prioritization of Disease Candidate Metabolites Based on a Multi-omics Composite Network

    PubMed Central

    Yao, Qianlan; Xu, Yanjun; Yang, Haixiu; Shang, Desi; Zhang, Chunlong; Zhang, Yunpeng; Sun, Zeguo; Shi, Xinrui; Feng, Li; Han, Junwei; Su, Fei; Li, Chunquan; Li, Xia

    2015-01-01

    The identification of disease-related metabolites is important for a better understanding of metabolite pathological processes in order to improve human medicine. Metabolites, which are the terminal products of cellular regulatory process, can be affected by multi-omic processes. In this work, we propose a powerful method, MetPriCNet, to predict and prioritize disease candidate metabolites based on integrated multi-omics information. MetPriCNet prioritized candidate metabolites based on their global distance similarity with seed nodes in a composite network, which integrated multi-omics information from the genome, phenome, metabolome and interactome. After performing cross-validation on 87 phenotypes with a total of 602 metabolites, MetPriCNet achieved a high AUC value of up to 0.918. We also assessed the performance of MetPriCNet on 18 disease classes and found that 4 disease classes achieved an AUC value over 0.95. Notably, MetPriCNet can also predict disease metabolites without known disease metabolite knowledge. Some new high-risk metabolites of breast cancer were predicted, although there is a lack of known disease metabolite information. A predicted disease metabolic landscape was constructed and analyzed based on the results of MetPriCNet for 87 phenotypes to help us understand the genetic and metabolic mechanism of disease from a global view. PMID:26598063

  5. Monitoring water stress and fruit quality in an orange orchard under regulated deficit irrigation using narrow-band structural and physiological remote sensing indices

    NASA Astrophysics Data System (ADS)

    Stagakis, S.; González-Dugo, V.; Cid, P.; Guillén-Climent, M. L.; Zarco-Tejada, P. J.

    2012-07-01

    This paper deals with the monitoring of water status and the assessment of the effect of stress on citrus fruit quality using structural and physiological remote sensing indices. Four flights were conducted over a citrus orchard in 2009 using an unmanned aerial vehicle (UAV) carrying a multispectral camera with six narrow spectral bands in the visible and near infrared. Physiological indices such as the Photochemical Reflectance Index (PRI570), a new structurally robust PRI formulation that uses the 515 nm as the reference band (PRI515), and a chlorophyll ratio (R700/R670) were compared against the Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI) and Modified Triangular Vegetation Index (MTVI) canopy structural indices for their performance in tracking water status and the effects of sustained water stress on fruit quality at harvest. The irrigation setup in the commercial orchard was compared against a treatment scheduled to satisfy full requirements (based on estimated crop evapotranspiration) using two regulated deficit irrigation (RDI) strategies. The water status of the trees throughout the experiment was monitored with frequent field measurements of stem water potential (Ψx), while titratable acidity (TA) and total soluble solids (TSS) were measured at harvest on selected trees from each irrigation treatment. The high spatial resolution of the multispectral imagery (30 cm pixel size) enabled identification of pure tree crown components, extracting the tree reflectance from shaded, sunlit and aggregated pixels. The physiological and structural indices were then calculated from each tree at the following levels: (i) pure sunlit tree crown, (ii) entire crown, aggregating the within-crown shadows, and (iii) simulating a lower resolution pixel, including tree crown, sunlit and shaded soil pixels. The resulting analysis demonstrated that both PRI formulations were able to track water status, except when water stress

  6. The Condor seamount at Mid-Atlantic Ridge as a supplementary source of trace and rare earth elements to the sediments

    NASA Astrophysics Data System (ADS)

    Caetano, Miguel; Vale, Carlos; Anes, Bárbara; Raimundo, Joana; Drago, Teresa; Schimdt, Sabine; Nogueira, Marta; Oliveira, Anabela; Prego, Ricardo

    2013-12-01

    The Condor Seamount rises from seabed to 180m water depth, being located 10 nautical miles southwest of the island of Faial, Azores Archipelago at the Mid-Atlantic Ridge (MAR). The vertical distribution of major, minor, trace and rare earth elements (REE) and Pb isotopes was studied in four sediment cores: one from the top of the Condor Seamount (200m, MC9), two from the seamount base (1400m, MC2 and MC4), and one from a deep area (1900m, MC8). Sediments from the top of the Condor were composed by coarser particles being the fine fraction lower than 1%. Conversely the other sediments were constituted by 51-92% of fine particles (<63μm). Individual fragments of volcanic material (>2mm) were found at several depths of the cores sampled at the base of the seamount. The core collected in the top of the Condor showed higher carbonate content (76-86%) compared with the other cores (41-64%). The chemical compositions of MC2 and MC4 point to an enhancement of V, Cr, Co, Ni and Fe concentrations. Lower concentrations in MC8 hypothesis that Condor seamount constitutes a supplementary source of trace elements. The most plausible explanation for the enhancement found in sediments of the seamount base is the weathering of slopes with volcanic activities, which supply particles with higher element concentrations than pelagic sediments. This hypothesis is corroborated by REE data, showing increased chondrite normalized ratios in MC2 and MC4. Moreover, the REE pattern found in those cores was comparable to that existing in volcanic material with Light REE enrichment in comparison to Heavy REE. These results indicate a substantial contribution of particles derived from volcanic activities to sediments settled in the vicinity of the Condor Seamount. It is argued the potential use of REE in sediments from this region as tracers of volcanic activities. Depth profiles of 206Pb/207Pb and 206Pb/208Pb showed lower ratios in the first 8cm sediment layers, reflecting atmospheric input of

  7. The Solar System primordial lead

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, Janne; Zanda, Brigitte; Ebel, Denton S.; Albarède, Francis

    2010-11-01

    Knowledge of the primordial isotope composition of Pb in the Solar System is critical to the understanding of the early evolution of Earth and other planetary bodies. Here we present new Pb isotopic data on troilite (FeS) nodules from a number of different iron meteorites: Canyon Diablo, Mundrabilla, Nantan, Seeläsgen, Toluca (IAB-IIICD), Cape York (IIIA), Mt Edith (IIIB), and Seymchan (pallasite). Lead abundances and isotopic compositions typically vary from one troilite inclusion to another, even within the same meteorite. The most primitive Pb was found in three leach fractions of two exceptionally Pb-rich Nantan troilite nodules. Its 204Pb/ 206Pb is identical to that of Canyon Diablo troilite as measured by Tatsumoto et al. [M. Tatsumoto, R.J. Knight, C.J. Allègre, Time differences in the formation of meteorites as determined from the ratio of lead-207 to lead-206, Science 180(1973) 1279-1283]. However, our measurements of 207Pb/ 206Pb and 208Pb/ 206Pb are significantly higher than theirs, as well as other older literature data obtained by TIMS, while consistent with the recent data of Connelly et al. [J.N. Connelly, M. Bizzarro, K. Thrane, J.A. Baker, The Pb-Pb age of Angrite SAH99555 revisited, Geochim. Cosmochim. Acta 72(2008) 4813-4824], a result we ascribe to instrumental mass fractionation having biased the older data. Our current best estimate of the Solar System primordial Pb is that of Nantan troilite, which has the following isotopic composition: 204Pb/ 206Pb = 0.107459(16), 207Pb/ 206Pb = 1.10759(10), and 208Pb/ 206Pb = 3.17347(28). This is slightly less radiogenic than the intercept of the bundle of isotopic arrays formed in 207Pb/ 206Pb- 204Pb/ 206Pb space by our measurements of Canyon Diablo, Nantan, Seeläsgen, Cape York, and Mundrabilla, as well as literature data, which, in spite of rather large uncertainties, suggests a common primordial Pb component for all of these meteorites. The radiogenic Pb present in most of these irons is dominantly

  8. Isotopic Studies of the Guerrero Composite Terrane, West-Central Mexico: Implications for Provenance of Crustal Rocks and Ore Metals

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.; Salters, V. J.; Sachi-Kocher, A.

    2010-12-01

    New Pb, Sr, and Nd isotope analyses of various crustal units and ores from the Guerrero terrane are presented in order to gain insight into their provenance. Mesozoic basement rocks from the Arteaga Complex and Tejupilco metamorphic suite contain radiogenic Pb relative to bulk earth models (206Pb/204Pb between 18.701 and 19.256, 207Pb/204Pb between 15.623 and 15.693, and 208Pb/204Pb between 38.694 and 39.216), plotting to the right of the average Pb crust evolution curve of Stacey and Kramers (1975). The isotopic compositions of Pb in these rocks are substantially more radiogenic than published data on high-grade metamorphic rocks from the Grenvillian-age Oaxaca terrane, but are similar to Paleozoic basement rocks of the Mixteca terrane. Sr and Nd isotope data suggest that the basement rocks of the Guerrero terrane partly originated from ocean-floor rocks which were overlain by sediments derived from a cratonic terrane, possibly represented by the metamorphic complexes of the Oaxaca or Mixteca terranes. Lead isotope ratios of Cretaceous sedimentary rocks of the Zihuatanejo and Huetamo Sequences define two different clusters, with the Zihuatanejo Sequence units shifted to more radiogenic values (206Pb/204 between 18.763 and 19.437, 207Pb/204Pb between 15.580 and 15.643, and 208Pb/204Pb between 38.510 and 38.892). Samples from the Huetamo Sequence are less radiogenic than the metamorphic basement, with Pb isotope ratios between 18.630 and 18.998 for 206Pb/204, 15.563 and 15.641 for 207Pb/204Pb, and 38.369 and 38.610 for 208Pb/204Pb. They plot close to the radiogenic end of the MORB field, suggesting a possible mixing line between the basement rocks and the MORB component. Lead isotope ratios of Tertiary intrusive rocks from La Verde, El Malacate, and La Esmeralda resemble the orogene reservoir in the plumbotectonics model of Zartman and Doe (1981). Plutonic rocks from La Verde show the most radiogenic Pb compositions, suggesting a significant influence of old

  9. Estimating Light Use Efficiency Of A Pine And Beech Forest From Leaf To Ecosystem Scale Using The Photochemical Reflectance Index

    NASA Astrophysics Data System (ADS)

    Vanikiotis, Theofilos; Markos, Nikos; Stagakis, Stavros; Tzotsos, Angelos; Sykioti, Olga; Kyparissis, Aris

    2013-12-01

    The prospect of accurately tracking photosynthetic processes using satellite observations is very important for understanding and monitoring global carbon cycle and climate change. The present study investigates the efficiency of the Photochemical Reflectance Index (PRI) in detecting light use efficiency (ɛ) in different spatial scales. The study sites concern two dense and homogenous forests in the region of Epirus (Greece), one evergreen coniferous forest dominated by Pinus nigra species and one deciduous forest dominated by Fagus sylvatica. Field and laboratory measurements of canopy structure (Leaf Area Index - LAI, needle and shoot structure characteristics), leaf pigment concentrations, leaf photosynthesis and water potential were performed throughout the growth period. These measurements were used for an accurate description of the ecophysiological characteristics of the two species and thus the parameterization of a Canopy Photosynthesis Model in order to estimate canopy photosynthesis. During the same period, leaf and canopy reflectance measurements were performed in the field to test and evaluate PRI regarding it's efficiency to track ɛ in leaf and canopy scale. In order to investigate the potential application of PRI for estimating ɛ in a broader spatial scale, satellite hyperspectral or superspectral sensors can be used. Compact High Resolution Imaging Spectrometer (CHRIS) and Moderate Resolution Imaging Spectroradiometer (MODIS) are currently available for this purpose and their performances were tested within the present study. An agreement between the fluctuations of CHRIS PRI and the field measured canopy PRI has been found, with both of them appearing to track the ɛ fluctuation efficiently. However, MODIS PRI shows no intense fluctuation and no relationship with ɛ and field measured PRI, probably due to lack of atmospheric correction and the effects of viewing and illumination geometry.

  10. The core microprocessor component DiGeorge syndrome critical region 8 (DGCR8) is a nonspecific RNA-binding protein.

    PubMed

    Roth, Braden M; Ishimaru, Daniella; Hennig, Mirko

    2013-09-13

    MicroRNA (miRNA) biogenesis follows a conserved succession of processing steps, beginning with the recognition and liberation of an miRNA-containing precursor miRNA hairpin from a large primary miRNA transcript (pri-miRNA) by the Microprocessor, which consists of the nuclear RNase III Drosha and the double-stranded RNA-binding domain protein DGCR8 (DiGeorge syndrome critical region protein 8). Current models suggest that specific recognition is driven by DGCR8 detection of single-stranded elements of the pri-miRNA stem-loop followed by Drosha recruitment and pri-miRNA cleavage. Because countless RNA transcripts feature single-stranded-dsRNA junctions and DGCR8 can bind hundreds of mRNAs, we explored correlations between RNA binding properties of DGCR8 and specific pri-miRNA substrate processing. We found that DGCR8 bound single-stranded, double-stranded, and random hairpin transcripts with similar affinity. Further investigation of DGCR8/pri-mir-16 interactions by NMR detected intermediate exchange regimes over a wide range of stoichiometric ratios. Diffusion analysis of DGCR8/pri-mir-16 interactions by pulsed field gradient NMR lent further support to dynamic complex formation involving free components in exchange with complexes of varying stoichiometry, although in vitro processing assays showed exclusive cleavage of pri-mir-16 variants bearing single-stranded flanking regions. Our results indicate that DGCR8 binds RNA nonspecifically. Therefore, a sequential model of DGCR8 recognition followed by Drosha recruitment is unlikely. Known RNA substrate requirements are broad and include 70-nucleotide hairpins with unpaired flanking regions. Thus, specific RNA processing is likely facilitated by preformed DGCR8-Drosha heterodimers that can discriminate between authentic substrates and other hairpins.

  11. Successful disabling of the 5' UTR of HCV using adeno-associated viral vectors to deliver modular multimeric primary microRNA mimics.

    PubMed

    Bourhill, Tarryn; Arbuthnot, Patrick; Ely, Abdullah

    2016-09-01

    Chronic hepatitis C virus (HCV) infection is a major health concern and is strongly associated with cirrhosis, hepatocellular carcinoma and liver-related mortality. The HCV genome is the template for both protein translation and viral replication and, being RNA, is amenable to direct genetic silencing by RNA interference (RNAi). HCV is a highly mutable virus and is capable of escaping RNAi-mediated silencing. This has highlighted the importance of developing RNAi-based therapy that simultaneously targets multiple regions of the HCV genome. To develop a multi-targeting RNAi activator, a novel approach for the generation of anti-HCV gene therapy was investigated. Five artificial primary miRNA (pri-miR) were each designed to mimic the naturally occurring monomeric pri-miR-31. Potent knockdown of an HCV reporter was seen with four of the five constructs and were processed according to the intended design. The design of the individual pri-miR mimics enabled the modular assembly into multimeric mimics of any possible conformation. Consequently the four potent pri-miR mimics were used to generate polycistronic cassettes, which showed impressive silencing of an HCV target. To further their application as a gene therapy, recombinant adeno-associated viral (rAAV) vectors that express the polycistronic pri-miR mimics were generated. All AAV-delivered anti-HCV pri-miR mimics significantly knocked down the expression of an HCV target and showed inhibition of HCV replicon replication. Here we describe a protocol for the generation of therapeutic rAAVs that express modular polycistronic pri-miR cassettes allowing for rapid alteration and generation of tailored therapeutic constructs against HCV.

  12. Bioavailability and Sources of Lead in the Terrestrial Environment of Egypt

    NASA Astrophysics Data System (ADS)

    Marzouk, Ezzat; Shetaya, Waleed; Elkassas, Mohamed; Mohamed, Elham; Bailey, Elizabeth; Young, Scott

    2016-04-01

    Lead (Pb) is considered a major contemporary eco-toxicological threat with smelting operations and fossil fuel combustion regarded as the major sources in the environment. The majority of studies characterising Pb in soil have sought to determine: (i) its source, from 206,207,208Pb isotope ratios, (ii) its distribution among operationally defined soil fractions and (iii) its lability as defined by chemical extraction or isotopic exchangeability. The objectives of the current work were: (i) to source-apportion the soil Pb burden in Egypt between petrol, geological and other origins over a wide range of soil characteristics and diverse locations; (ii) to quantify the isotopically exchangeable fraction of Pb (PbE) as a measure of Pb reactivity; and (iii) to develop multivariate relationships to predict soil Pb lability. Combined determinations of SEP fractionation, isotopic lability and natural isotopic abundances were used as a means of characterizing Pb in ˜ 150 Egyptian soils (selected to cover a wide range of soil properties, locations and Pb exposure). Results showed a wide range of % PbEvalues (˜ 5 - 40 % of the total soil Pb concentration, Pbtotal). However, PbE showed no consistent correspondence to any single fraction of the SEP. Non-labile Pb (Pbtotal - PbE) showed reasonable agreement with the SEP 'residual' fraction in relatively uncontaminated soils from both inland and shoreline soils. However, in other soils, notably those from contaminated peri-urban and urban locations, the non-residual fractions (bound to oxides and humus) included non-labile forms of Pb. Up to 90% of the observed variability in the %PbE in soils from the inland and shoreline areas (uncontaminated) could be explained by soil factors, including variation in soil pH, soil organic matter content, total Pb and P concentrations. However, in the case of the contaminated peri-urban and urban soils the figure was only 33% implying a significant contaminant 'source' effect on Pb lability

  13. The transfer of bomb radiocarbon and anthropogenic lead to the deep North Atlantic Ocean observed from a deep sea coral

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Mi; Eltgroth, Selene F.; Boyle, Edward A.; Adkins, Jess F.

    2017-01-01

    Deep-ocean, Δ14C, Pb concentrations, and Pb isotopes were reconstructed from a deep-sea coral Enallopsammia rostrata from 1410 m depth off of Bermuda. Our high-resolution time series is created from closely spaced radial cross sections, with samples taken from the center of concentric coral growth bands that we show to be the oldest portion of the section. Prebomb radiocarbon ages from the coral demonstrate that the vertical growth rate of the coral is linear, and the age of the coral is estimated to be 560-630 yr old based on the growth rate. Using this age model to reconstruct Δ14C in deep seawater, we first detect bomb radiocarbon at the coral growth site around 1980, and show that Δ14C increased from - 80 ± 1 ‰ (average 1930-1979) to a plateau at - 39 ± 3 ‰ (1999-2001). Pb/Ca of the coral ranges between 1.1-4.5 nmol/mol during the 16th and 17th centuries, and Pb isotope ratios (206Pb/207Pb = 1.21, 208Pb/207Pb = 2.495) in this period agree with pre-anthropogenic values found in the pelagic sediments of the North Atlantic Ocean basin. Coral Pb/Ca is slightly elevated to 6.2 ± 0.9 nmol /mol between the 1740s and the 1850s and then increases to 25.1 ± 0.2 nmol /mol in the 1990s. The increase in coral Pb/Ca is accompanied by a decrease in coral 206Pb/207Pb and 208Pb/207Pb, indicating that the increase was caused by the infiltration of anthropogenic Pb to the coral growth site. Comparing our data to the surface coral Δ14C and Pb records from Bermuda reveals a time scale of tracer transport from the surface ocean to the coral growth site. Some characteristic features, e.g., the bomb-derived Δ14C increase, appear in the deep ocean approximately 25 yr later than the surface, but the overall increase of Δ14C and Pb in the deep ocean is smaller and slower than the surface, showing the importance of mixing during the transport of these tracers.

  14. Time constraints on faults activity in the Eastern California Shear Zone from U-Pb (SHRIMP-RG) dating of syntectonic opal

    NASA Astrophysics Data System (ADS)

    Nuriel, P.; Maher, K.; Miller, D. M.

    2013-12-01

    Absolute time constraints for fault activity are of fundamental importance in active fault systems. Such constraints are necessary for estimation of long-term slip-rates and earthquake recurrence intervals required for seismic-hazard assessments. Notwithstanding, paleoseismological records are often limited to the past 1 Ma, and important information such as fault initiation and early stage displacement are seldom determined. Here we present a novel methodological approach for direct dating of brittle deformation events over a geological time scale. We use in situ U-Pb SHRIMP-RG (Sensitive High Resolution Ion Microprobe - Reverse Geometry) analyses of opal precipitates in order to constrain the relative and absolute timing of brittle deformation events. The Mojave Desert fault segments within the Eastern California Shear Zone (ECSZ) are ideal faults to investigate the long-term history because of the need for improved constraints on the timing of fault initiation and the observed discrepancy between long-term and short-term estimates for strain accumulation rates in this area. We analyzed fault-related opal samples from ten different fault exposures within the Camp Rock, Cave Mountain, and the Cady fault systems. Millimeter size fragments of fault-related opal, occurring as fault coating, filling or fault-breccia cement, were imaged using cathodoluminescence and backscattering electron microscopy in order to identify distinct phases of opal associated with specific syntectonic microstructures. Sub-samples within each phase are then targeted with multiple SHRIMP-RG analyses (<50 μm in diameter) to allow the construction of 238U/208Pb-206Pb/208Pb and/or Tera-Wasserburg U-Pb isochrons. Of the 50 distinct phases that were identified, 20 were successfully dated and U-Pb age results range from 8.4 to 0.58 Ma. The timing of fault initiation along the Cave Mountain Fault system was previously estimated to be between 15 Ma and 5 Ma. Our results suggest that initial

  15. Nuclear Structure Studies with the SCANDIUM-45, SAMARIUM-144, and LEAD-208

    NASA Astrophysics Data System (ADS)

    Mostajabodda'Vati, Mojtaba

    Experiments were performed to measure neutron time-of-flight spectra from the (p,n) reaction on ^{45}Sc, ^{144 }Sm, and ^{208}Pb targets at about 136 MeV. In the ^{45}Sc(p,n) ^{45}Ti reaction we observe a 19/2^-, 17/2^- doublet at 4.3 MeV. These states are part of the two-particle, one-hole (pif _sp{7/2}{2}, nuf_sp{7/2}{ -1}) band of states. Distorted Wave Impulse Approximation (DWIA) calculations for these transitions were performed using wave functions obtained from a shell -model calculation which considers five particles in the 1f-2p shell with no restriction. These calculations describe the experimental results well without renormalization. The Gamow-Teller (GT) strength in ^{45 }Sc(p,n)^{45}Ti was considered also; the strength observed in peaks is about 40% of the minimum value expected from the simple GT sum rule. In the ^{144}Sm(p,n) ^{144}Eu reaction we observe a (pih_{11/2 }, nuh_sp {11/2}{-1}) 11^+ , 0 hbaromega stretched state at 2.2 MeV of excitation. A DWIA calculation for this transition with only the simple shell-model wave function needs to be normalized by 0.55 to agree with the experiment. More realistic wave functions were obtained from a 3p-3h shell -model calculation. The DWIA normalization factor required using these wave functions is essentially unity (0.95). The total observed GT strength in peaks is 40% of the GT sum rule value. A single peak is observed to be strongly excited in the ^{208}Pb(p,n) ^{208}Bi reaction at large angles. This peak was interpreted earlier as the (pii _{13/2}, nu i_sp{13/2}{-1} ) 13^+, 0 hbar omega state. The present experiment reveals that the observed peak is too broad to be a single state and that the angular distribution cannot be described well by a DWIA calculation assuming only a single transition. We believe that this peak is a doublet including an ( pii_{13/2}, nui_sp{13/2} {-1}) 11^+ state. This conclusion is supported by a higher resolution measurement performed at a single angle at 99 MeV. Assuming

  16. Spatial Distribution of Lead Isotope Ratios and Inorganic Element Concentrations in Epiphytic Lichens from the Athabasca Oil Sands Region

    NASA Astrophysics Data System (ADS)

    Graney, J. R.; Landis, M. S.; Puckett, K.; Edgerton, E.; Krupa, S.; Percy, K.

    2013-12-01

    Coupled studies of inorganic element concentrations and lead (Pb) isotope ratios have been conducted on Hypogymnia physodes samples collected in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada in 2002, 2008, and 2011. To investigate the spatial extent of air emissions, the lichens were collected from sites as far as 160 km from the mining and processing operations. 30 milligram sub-samples of the lichens were microwave digested, and the extracts were analyzed using DRC-ICPMS to determine elemental concentrations, and sector field ICPMS to measure Pb isotope ratios. Concentrations of elements in the lichens were found to reflect proximity to mining and oil processing sites as well as topography, ecosystem differences, and the metabolic biogeochemistry of the lichens. An exponential decrease in concentration of metals associated with fugitive dust (aluminum and others) versus distance from the mining sites, suggests elevated coarse particle emissions associated with mining operations. Near source concentrations of metals with an oil signature (vanadium and others) are less enhanced and more homogeneous than the metals in the fugitive dust, reflecting emission and deposition of smaller diameter particles at greater distances from oil processing sources. The mining and oil processing signatures are superimposed over elemental concentrations that reflect the nutrient needs of the lichens. These findings are being confirmed through ongoing studies using dichot samplers to collect coarse and fine particulate aerosol samples. The lichen samples collected beyond 50 km from the mining and processing sites cluster into a Pb isotope grouping with a 207Pb / 206Pb ratio of 0.8650 and a 208Pb / 206Pb ratio near 2.095. This grouping likely reflects the regional background Pb isotope ratio signature. 207Pb / 206Pb and 208Pb / 206Pb ratios decrease as one nears the mining and processing operations. This indicates that other Pb source(s), (e.g. Pb in the bitumen from the oil

  17. Pb and O isotopic constraints on the source of granitic rocks from Cape Breton Island, Nova Scotia, Canada

    USGS Publications Warehouse

    Ayuso, R.A.; Barr, S.M.; Longstaffe, F.J.

    1996-01-01

    Pb isotopic compositions of leached feldspars from twenty-three plutons in Cape Breton Island can be divided into two groups: anorthosite, syenite, and granite in the Blair River Complex, which have the least radiogenic compositions on the Island, and granitic rocks from terranes (Aspy, Bras d'Or, and Mira) to the south. Pb isotopic data for the Blair River Complex (206Pb/204Pb = 17.399-18.107; 207Pb/204Pb = 15.505-15.560; 208Pb/204Pb = 36.689-37.733) are consistent with an old source region ultimately derived from the mantle and contaminated by sialic crust. Oxygen isotopic compositions of syenite in the Blair River Complex (??18O = +8.0 to +8.5 permil) are slightly higher than anorthosite (+7.0 to +8.3 permil); a Silurian granite in the Blair River Complex has ??18O = +7.5 permil. Cambrian to Devonian plutons in the Aspy, Bras d'Or, and Mira terranes are more radiogenic (206Pb/204Pb = 18.192-18.981; 207Pb/204Pb = 15.574-15.712; 208Pb/ 204Pb =37.815-38.936) than the Blair River Complex and were generated from source regions having a predominant crustal Pb signature (high ??). The ??18O values of granites and granodiorites in the Aspy terrane (+7.5 to +9.2 permil; avg = +8.6 permil) and Bras d'Or (+3.7 to +11.3 permil; avg = +9.4 permil) are also consistent with involvement of sialic crust. Many Late Proterozoic granites from the Mira terrane have anomalously low ??18O values (+0.2 to +5.9 permil), perhaps produced from protoliths that had undergone hydrothermal alteration prior to melting. Paleozoic granitic rocks from the Aspy, Bras d'Or, and Mira terranes cannot be uniquely distinguished on the basis of their Pb and O isotopic compositions. The granitic rocks could have been generated during terrane amalgamation from combinations of unradiogenic (Grenville-like) and more radiogenic (Avalon-like) sources.

  18. Dust Deposition and Migration of the ITCZ through the Last Glacial Cycle in the Central Equatorial Pacific (Line Islands).

    NASA Astrophysics Data System (ADS)

    Reimi Sipala, M. A.; Marcantonio, F.

    2014-12-01

    Atmospheric dust can be used to record climate change in addition to itself playing a role in several key climate processes, such as affecting Earth's albedo, fomenting rain coalescence, encouraging biological productivity, and enhancing carbon export though particle sinks. Using deep sea sediments, it is possible to quantify and locate the sources and sinks of atmospheric dust. A key area of research is the shift in the inter-tropical converge zone (ITCZ), a thermally influenced area that shifts according to the northern and southern hemisphere temperature gradient. This ongoing project focuses on the changes of the ITCZ over the Central Equatorial Pacific (CEP) over the past ~25000 years. The research focuses on two cores taken from the Line Islands Ridge at 0° 29' N (ML1208-18GC), and 4° 41' N (ML1208-31BB). The main aim is to quantify the magnitude and provenance of windblown dust deposited in the CEP, and to address questions regarding the nature of the variations of dust through ice-age climate transitions. Radiogenic isotopes (Sr, Nd, Pb) have been successfully used to distinguish between different potential dust sources in the aluminosilicates fractions of Pacific Sediments. Our preliminary Pb isotope ratios suggest that, for modern deposition, the northern core's (31BB) detrital sediment fraction is likely sourced from Asian Loess (average ratios are 206Pb/204Pb = 18.88, 207Pb/204Pb = 15.69, 208Pb/204Pb = 39.06). The equatorial core's (18GC) detrital fraction has a less radiogenic Pb signature, which is consistent with South American dust sourcing (206Pb/204Pb = 18.62, 207Pb/204Pb = 15.63, 208Pb/204Pb = 38.62). This is indicative of a strong modern ITCZ that acts as an effective barrier for inter-hemispheric dust transport. Prior to Holocene time, the changes in Pb isotope ratios in both cores appear to be in anti-phase; the northern core becomes less radiogenic up to the LGM, while the southern core becomes more radiogenic. This is potentially due to a

  19. Geochemistry, Sr-Nd-Pb isotopes and geochronology of amphibole- and mica-bearing lamprophyres in northwestern Iran: Implications for mantle wedge heterogeneity in a palaeo-subduction zone

    NASA Astrophysics Data System (ADS)

    Aghazadeh, Mehraj; Prelević, Dejan; Badrzadeh, Zahra; Braschi, Eleonora; van den Bogaard, Paul; Conticelli, Sandro

    2015-02-01

    Lamprophyres of different age showing distinctive mineralogy, geochemistry and isotopic ratios are exposed in northwestern Iran. They can be divided into Late Cretaceous sannaite, Late Oligocene-Early Miocene camptonite (amphibole-bearing) and Late Miocene minette (mica-bearing) and spessartite (amphibole-bearing) lamprophyres. Sannaites have high-Ti amphibole along with high-Ti and Al clinopyroxene, and they are characterised by homogeneous enrichment in incompatible trace elements with troughs at Pb. Spessartites have hornblende and low-Al and Ti clinopyroxene, and they are characterised by enriched incompatible trace element pattern with depletions of Nb, Ta, Pb, and Ti with respect to large ion lithophile elements. Minettes have high-Ti and Al brown mica and low-Al and Ti clinopyroxene, and similar to spessartite, are characterised by fractionation of high field strength elements with respect to large ion lithophile elements, with troughs at Nb, Ta, and Ti and a peak at Pb. Minettes show high initial 87Sr/86Sr values up to 0.70760 and low initial 143Nd/144Nd down to 0.512463 with a negative correlation, consistent with the trace element distribution related with an enriched mantle source modified after sediment recycling during subduction and continental collision. Cretaceous sannaites and Early Miocene spessartites show low initial 87Sr/86Sr approaching 0.70447 and high 143Nd/144Nd values up to 0.512667, which are consistent with a depleted within-plate mantle source. Minette and spessartite lamprophyres show high initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values, whereas sannaites have lower, but variable, initial 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values with respect to those of calc-alkaline lamprophyres. Minettes originated by partial melting of a metasomatised lithospheric mantle following siliciclastic sediment recycling by subduction. In contrast, sannaites were generated from the partial melting of a similar lithospheric mantle that was

  20. Isotope hydrology dynamics of riverine wetlands in the Kankakee Watershed, Indiana

    USGS Publications Warehouse

    Sidle, W.C.; Arihood, L.; Bayless, R.

    2000-01-01

    Wetland restoration activities may disturb shallow ground-water flow dynamics. There may be unintentional sources of water flowing into a constructed wetland that could compromise the long-term viability of a wetland function. Measurement of naturally-occurring isotopes in the hydrosphere can provide an indication of provenance, flow paths or components, and residence times or ages of wetland ground-water flow systems. Hydraulic head measurements may not provide sufficient detail of shallow flow disturbances and can be complemented by analyzing isotopes in waters flowing through the wetland. Two north-central Indiana wetlands in the Kankakee watershed are being studied to determine the adequacy of wetland restoration activities. The native LaSalle wetland and the restored Hog Marsh wetland have contrasting ground-water flow regimes. The conservative water isotopes 18O, 2H, and 3H, and selected solute isotopes 13C, 14C, 15N, 34S, 87Sr, and 206-208Pb, demonstrate the complexity of ground-water flow in Hog Marsh compared to the established flow regime at the LaSalle wetland.Wetland restoration activities may disturb shallow ground-water flow dynamics. There may be unintentional sources of water flowing into a constructed wetland that could compromise the long-term viability of a wetland function. Measurement of naturally-occurring isotopes in the hydrosphere can provide an indication of provenance, flow paths or components, and residence times or ages of wetland ground-water flow systems. Hydraulic head measurements may not provide sufficient detail of shallow flow disturbances and can be complemented by analyzing isotopes in waters flowing through the wetland. Two north-central Indiana wetlands in the Kankakee watershed are being studied to determine the adequacy of wetland restoration activities. The native LaSalle wetland and the restored Hog Marsh wetland have contrasting ground-water flow regimes. The conservative water isotopes 18O, 2H, and 3H, and selected