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Sample records for source ho ni

  1. Magnetic ordering of YPd2Si-type HoNi2Si and ErNi2Si compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Isnard, O.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-12-01

    Magnetic properties of YPd2Si-type HoNi2Si and ErNi2Si were investigated via neutron diffraction and magnetisation measurements. HoNi2Si and ErNi2Si show ferromagnetic-like ordering at TC of 9 K and 7 K, respectively. The paramagnetic Weiss temperatures are 9 K and 11 K and the effective magnetic moments are 10.76 μB/fu and 9.79 μB/fu for HoNi2Si and ErNi2Si compounds, respectively. The HoNi2Si and ErNi2Si are soft ferromagnets with saturation magnetization of 8.1 μB/fu and 7.5 μB/fu, respectively at 2 K and in field of 140 kOe. The isothermal magnetic entropy change, ΔSm, has a maximum value of -15.6 J/kg·K at 10 K for HoNi2Si and -13.9 J/kg·K at 6 K for ErNi2Si for a field change of 50 kOe. Neutron diffraction study in zero applied field shows mixed ferromagnetic-antiferromagnetic ordering of HoNi2Si at 9 K and its magnetic structure is a sum of a-axis ferromagnetic Fa, b-axis antiferromagnetic AFb and c-axis antiferrromagnetic AFc components of Pn‧a21‧={1, mx‧/[1/2, 1/2, 1/2], 2y‧/[0, 1/2, 0], mz/[1/2, 0, 1/2]} magnetic space group and propagation vector K0=[0, 0, 0]. The holmium magnetic moment reaches a value of 9.23(9) μB at 1.5 K and the unit cell of HoNi2Si undergoes isotropic contraction around the temperature of magnetic transition.

  2. Magnetic properties of a new intermetallic compound Ho2Ni2Pb

    NASA Astrophysics Data System (ADS)

    Muñoz-Sandoval, E.; Chinchure, A. D.; Hendrikx, R. W. A.; Mydosh, J. A.

    2001-10-01

    Single-phase, textured samples of a new orthorhombic intermetallic compound Ho2Ni2Pb have been fabricated (space group Cmmm). Here the bulk magnetic properties are presented as determined via magnetization, susceptibility, heat capacity and resistivity measurements. The results exhibit two distinct magnetic transitions and large metamagnetic effects. Such behaviour is related to the unusual rare-earth symmetry of the highly anisotropic crystal structure.

  3. Large reversible magnetocaloric effect induced by metamagnetic transition in antiferromagnetic HoNiGa compound

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Xu; Zhang, Hu; Wu, Mei-Ling; Tao, Kun; Li, Ya-Wei; Yan, Tim; Long, Ke-Wen; Long, Teng; Pang, Zheng; Long, Yi

    2016-12-01

    The magnetic properties and magnetocaloric effects (MCE) of HoNiGa compound are investigated systematically. The HoNiGa exhibits a weak antiferromagnetic (AFM) ground state below the Ńeel temperature TN of 10 K, and the AFM ordering could be converted into ferromagnetic (FM) ordering by external magnetic field. Moreover, the field-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature, which then result in a large MCE. A large -ΔSM of 22.0 J/kg K and a high RC value of 279 J/kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ0H2/3 dependence of well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM-PM magnetic transition under high magnetic fields. The large reversible MCE induced by metamagnetic transition suggests that HoNiGa compound could be a promising material for magnetic refrigeration in low temperature range. Project supported by the National Natural Science Foundation of China (Grant Nos. 51671022 and 51427806), the Beijing Natural Science Foundation, China (Grant No. 2162022), and the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-15-002A3).

  4. Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

    PubMed

    Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

    2014-04-07

    Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

  5. Enhanced ferromagnetic properties in Ho and Ni co-doped BiFeO{sub 3} ceramics

    SciTech Connect

    Park, J. S.; Yoo, Y. J.; Hwang, J. S.; Lee, Y. P.; Kang, J.-H.; Lee, B. W.

    2014-01-07

    The magnetic properties of polycrystalline Bi{sub 1-x}Ho{sub x}Fe{sub 1-y}Ni{sub y}O{sub 3} (x = 0, 0.1; y = 0, 0.03), which were prepared by the solid-state method, have been investigated. The powder X-ray diffraction reveals that all the samples are polycrystalline and show rhombohedral perovskite structure. The micro-Raman scattering studies confirm that Bi{sub 0.9}Ho{sub 0.1}Fe{sub 0.97}Ni{sub 0.03}O{sub 3} has a compressive lattice distortion induced by the simultaneous substitution of Ho and Ni ions at A and B-sites, respectively. From the magnetization dependences at room temperature, Bi{sub 0.9}Ho{sub 0.1}Fe{sub 0.97}Ni{sub 0.03}O{sub 3} has enhanced magnetization (0.2280 emu/g) and low coercive field (280 Oe). It was revealed that the Ni dopant plays an important role for the improved ferromagnetic properties and the Ho dopant favors the magnetic exchange interactions in the co-doped ceramic.

  6. Disordered ferromagnetism in Ho2NiMnO6 double perovskite.

    PubMed

    Chakraborty, Tirthankar; Nair, Harikrishnan S; Nhalil, Hariharan; Ramesh Kumar, K; Strydom, André M; Elizabeth, Suja

    2017-01-18

    Magnetic and dielectric properties of the double perovskite Ho2NiMnO6 are reported. The compound is synthesized by nitrate route and is found to crystallize in monoclinic P21/n space group. Lattice parameters obtained by refining powder x-ray diffraction data are; a  =  5.218(2) Å, b  =  5.543(2) Å, c  =  7.480(3) Å and the monoclinic angle is [Formula: see text](4). A phase transition is observed at [Formula: see text] K in the temperature-dependent magnetization curve, M(T). The inverse magnetic susceptibility, (1/[Formula: see text]) fits reasonably well with modified Curie-Weiss law by incorporating the paramagnetic response of Ho(3+). 1/[Formula: see text] manifests as an upward deviation from ideal Curie-Weiss behaviour well above the ferromagnetic transition. Signs of inherent Griffiths phase pertaining to the Ni/Mn subsystem are visible when one subtracts the Ho(3+) paramagnetic contribution from total susceptibility and does the power-law analysis. The magnetic hysteresis at 2 K gives the maximum value of magnetization [Formula: see text] [Formula: see text]/f.u. at 50 kOe. Field-derivative of magnetization at 2 K shows discontinuities which indicates the existence of metamagnetic transitions in this compound. This needs to be probed further. Out of the two dielectric relaxations observed, the one at low temperature may be attributed to phononic frequencies and that at higher temperature may be due to Maxwell-Wagner relaxation. A correlation between magnetic and lattice degrees of freedom is plausible since the anomaly in dielectric constant coincides with T C.

  7. Disordered ferromagnetism in Ho2NiMnO6 double perovskite

    NASA Astrophysics Data System (ADS)

    Chakraborty, Tirthankar; Nair, Harikrishnan S.; Nhalil, Hariharan; Kumar, K. Ramesh; Strydom, André M.; Elizabeth, Suja

    2017-01-01

    Magnetic and dielectric properties of the double perovskite Ho2NiMnO6 are reported. The compound is synthesized by nitrate route and is found to crystallize in monoclinic P21/n space group. Lattice parameters obtained by refining powder x-ray diffraction data are; a  =  5.218(2) Å, b  =  5.543(2) Å, c  =  7.480(3) Å and the monoclinic angle is β ={{90.18}\\circ} (4). A phase transition is observed at {{T}\\text{C}}=86 K in the temperature-dependent magnetization curve, M(T). The inverse magnetic susceptibility, (1/χ (T) ) fits reasonably well with modified Curie-Weiss law by incorporating the paramagnetic response of Ho3+. 1/χ (T) manifests as an upward deviation from ideal Curie-Weiss behaviour well above the ferromagnetic transition. Signs of inherent Griffiths phase pertaining to the Ni/Mn subsystem are visible when one subtracts the Ho3+ paramagnetic contribution from total susceptibility and does the power-law analysis. The magnetic hysteresis at 2 K gives the maximum value of magnetization {{M}\\text{max}}≈ 15 {μ\\text{B}} /f.u. at 50 kOe. Field-derivative of magnetization at 2 K shows discontinuities which indicates the existence of metamagnetic transitions in this compound. This needs to be probed further. Out of the two dielectric relaxations observed, the one at low temperature may be attributed to phononic frequencies and that at higher temperature may be due to Maxwell-Wagner relaxation. A correlation between magnetic and lattice degrees of freedom is plausible since the anomaly in dielectric constant coincides with T C.

  8. Magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.; Mozharivskyj, Y.; Isnard, O.

    2017-02-01

    The magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}3Co2Ge3 and Ho3Ni2Ge3 exhibit field sensitive complex antiferromagnetic orderings with TN=51 K, Tm=10 K for Sm3Co2Ge3, TN=34 K, Tm=13 K for Tb3Co2Ge3, TN=7 K for Er3Co2Ge3 and TN=11 K for Ho3Ni2Ge3. At 2 K and above the critical field of 5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3, respectively, saturation magnetizations per rare-earth atom are 6.5 μB for Tb3Co2Ge3, 7.0 μB for Er3Co2Ge3 and 8.0 μB for Ho3Ni2Ge3 in the field of 140 kOe, whereas magnetization of Sm3Co2Ge3 has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔSm, indicates a field-induced ferromagnetic ordering in Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3 with a maximal ΔSm value of -10.9 J/kg K for Ho3Ni2Ge3 at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below TN=33 K and down to TmND=15 K Tb3Ni2Ge3 shows an ac-antiferromagnetic ordering with the C2‧/c magnetic space group, a K0=[0, 0, 0] propagation vector and a aTb3Ni2Ge3×bTb3Ni2Ge3×cTb3Ni2Ge3 magnetic unit cell. Below TmND=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2‧/c magnetic space group of the K0 vector and a sine-modulated a-antiferromagnetic component of the K1=[0, 0, ±1/3] propagation vector (the magnetic unit cell is aTb3Ni2Ge3×bTb3Ni2Ge3×3cTb3Ni2Ge3). The magnetic structure is made from the 'Tb2 - 2Tb1‧ clusters of the Tb1 8f and Tb2 4c sublattices with a dominant role of the Tb2 sublattices in the magnetic ordering of Tb3Ni2Ge3.

  9. Study of morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled compound

    SciTech Connect

    Bajorek, Anna; Skornia, Paweł; Prusik, Krystian; Wojtyniak, Marcin; Chełkowska, Grażyna

    2015-03-15

    The morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled intermetallic compounds are presented. The polycrystalline HoNi{sub 3} bulk compound crystallizes in the rhombohedral PuNi{sub 3} — type of crystal structure and indicates ferrimagnetic arrangement with the Curie temperature of T{sub C} = 57 ± 2 K, the helimagnetic temperature T{sub h} = 23 ± 2 K with the total saturation magnetic moment of 6.84 μ{sub B}/f.u. at 2 K. The use of the ball-milling method leads to the formation of HoNi{sub 3} nanoflakes with typical thickness of less than 100 nm prone to agglomeration upon milling. The increase of grinding duration leads to the reduction in crystallite size, which was confirmed by various complementary microscopical and diffraction studies. Moreover, the increase in milling duration results in the emergence of the relatively small coercivity (H{sub C}), remanence (M{sub r}) and a variation of the saturation magnetization (M{sub S}). - Graphical abstract: Display Omitted - Highlights: • The ball-milling method exhibits significant potential for producing RT{sub 3} nanopowders. • The AFM method was used for the first time in analysis of R–T nanoflakes morphology. • HoNi{sub 3} compound forms polycrystalline and textured nanoflakes evolving upon milling. • The decrease in crystallite size via grinding is confirmed by XRD, TEM and AFM. • The magnetic parameters were sensitive to the extension of pulverization b.

  10. Low-temperature heat-capacity studies of R2Ni3Si5 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Mazumdar, Chandan; Ghosh, K.; Nagarajan, R.; Ramakrishnan, S.; Padalia, B. D.; Gupta, L. C.

    1999-02-01

    We report here our low temperature (2-30 K) heat capacity, Cp measurements of R2Ni3Si5 (R=Pr, Nd, Sm, Gd-Ho). Large peaks in heat capacity data at magnetic transition temperatures (TN) confirm the bulk nature of magnetic order in these compounds. In Nd2Ni3Si5, Gd2Ni3Si5, and Dy2Ni3Si5, magnetization studies indicated only one magnetic transition, whereas, heat-capacity data show two transitions. TN of the heavier rare-earth member, Tb2Ni3Si5, showing significant deviation from de Gennes scaling is notable. Magnetic entropy, ΔS, estimated from heat-capacity data suggest that the magnetic ground state is a doublet in R2Ni3Si5 (R=Pr, Nd, Sm, Dy, Ho) and a quartet in Tb2Ni3Si5. In all the cases, ΔS, at TN is slightly less than that expected due to the suggested states, which we attribute to the occurrence of precursor effects of magnetic order above TN. Except for Gd2Ni3Si5, ΔS of the compounds does not reach the saturation limit of R ln(2J+1) even at 30 K, indicating the presence of crystalline electric field (CEF) effects. A hump in Cp is observed below TN in Gd2Ni3Si5 which is interpreted in terms of a possible amplitude-modulated magnetic spin structure.

  11. Magnetocaloric properties of R2NiMnO6 (R=Pr, Nd, Tb, Ho and Y) double perovskite family

    NASA Astrophysics Data System (ADS)

    Chakraborty, Tirthankar; Nhalil, Hariharan; Yadav, Ruchika; Wagh, Aditya A.; Elizabeth, Suja

    2017-04-01

    Double perovskite R2NiMnO6 (R=Pr, Nd, Tb, Ho and Y) composites are prepared via solid state synthesis or nitrate route. Isothermal magnetic entropy change (ΔSM (T , H)) and relative cooling power (RCP) for all systems are calculated and compared. All of them possess relatively high values of ΔSM (T , H) and RCP as compared to many perovskite and double perovskite systems reported previously. Ho2NiMnO6 has the highest value for | ΔSM (T , H) | and RCP as 8.4 JKg-1K-1 at 70 kOe and 59.18 J Kg-1 at 20 kOe respectively. This study highlights the potential of magnetocaloric refrigerant materials at low temperature.

  12. Magnetic structures of R5Ni2In4 and R11Ni4In9 ( R = Tb and Ho): Strong hierarchy in the temperature dependence of the magnetic ordering in the multiple rare-earth sublattices

    DOE PAGES

    Ritter, C.; Provino, A.; Manfrinetti, P.; ...

    2015-11-09

    In this study, the magnetic properties and magnetic structures of the R5Ni2In4 and the microfibrous R 11Ni4In9 compounds with R = Tb and Ho have been examined using magnetization, heat capacity, and neutron diffraction data. Rare earth atoms occupy three and five symmetrically inequivalent rare earth sites in R5Ni2In4 and R 11Ni4In9 compounds, respectively. As a result of the intra- and inter-magnetic sublattice interactions, the magnetic exchange interactions are different for various rare earth sites; this leads to a cascade of magnetic transitions with a strong hierarchy in the temperature dependence of the magnetic orderings.

  13. Metamagnetism and giant magnetoresistance of the rare-earth intermetallic compounds R2Ni2Pb (R=Er,Ho,Dy)

    NASA Astrophysics Data System (ADS)

    Chinchure, Aravind D.; Muñoz Sandoval, E.; Mydosh, J. A.

    2002-07-01

    We have measured the magnetization and magnetoresistance for a series of rare-earth (R=Er,Ho,Dy) plumbide intermetallic compounds, R2Ni2Pb. These materials form in an unusual orthorhombic structure with space group Cmmm. After multiple magnetic transitions, the ground state exhibits a steplike series of large-moment metamagnetic transitions in low fields (1-2 T) concomitant with switchinglike properties of the magnetoresistance where sharp changes of up to 30% are found. We relate these properties to the layered magnetic structure of the compound.

  14. Observed OH and HO2 in the upper troposphere suggest a major source from convective injection of peroxides

    NASA Astrophysics Data System (ADS)

    Jaeglé, L.; Jacob, D. J.; Wennberg, P. O.; Spivakovsky, C. M.; Hanisco, T. F.; Lanzendorf, E. J.; Hintsa, E. J.; Fahey, D. W.; Keim, E. R.; Proffitt, M. H.; Atlas, E. L.; Flocke, F.; Schauffler, S.; McElroy, C. T.; Midwinter, C.; Pfister, L.; Wilson, J. C.

    ER-2 aircraft observations of OH and HO2 concentrations in the upper troposphere during the NASA/STRAT campaign are interpreted using a photochemical model constrained by local observations of O3, H2O, NO, CO, hydrocarbons, albedo and overhead ozone column. We find that the reaction Q(¹D) + H2O is minor compared to acetone photolysis as a primary source of HOx (= OH + peroxy radicals) in the upper troposphere. Calculations using a diel steady state model agree with observed HOx concentrations in the lower stratosphere and, for some flights, in the upper troposphere. However, for other flights in the upper troposphere, the steady state model underestimates observations by a factor of 2 or more. These model underestimates are found to be related to a recent (< 1 week) convective origin of the air. By conducting time-dependent model calculations along air trajectories determined for the STRAT flights, we show that convective injection of CH3OOH and H2O2 from the boundary layer to the upper troposphere could resolve the discrepancy. These injections of HOx reservoirs cause large HOx increases in the tropical upper troposphere for over a week downwind of the convective activity. We propose that this mechanism provides a major source of HOx in the upper troposphere. Simultaneous measurements of peroxides, formaldehyde and acetone along with OH and HO2 are needed to test our hypothesis.

  15. Adapting TESLA technology for future cw light sources using HoBiCaT

    NASA Astrophysics Data System (ADS)

    Kugeler, O.; Neumann, A.; Anders, W.; Knobloch, J.

    2010-07-01

    The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.

  16. Spherical neutron polarimetry of the magnetic structure in HoNi{sub 2}B{sub 2}C: Interplay between magnetic phases and superconductivity

    SciTech Connect

    Schneider, M.; Zaharko, O.; Gasser, U.; Kreyssig, A.; Brown, P. J.; Canfield, P. C.

    2006-09-01

    Spherical neutron polarimetry has been used to answer open questions about different magnetic phases in HoNi{sub 2}B{sub 2}C, which are important in their interplay with superconductivity. We established that the incommensurate a{sup *} structure of k{sub 3}=(0.585 0 0) at 5.4 K in a zero magnetic field is a transverse-amplitude modulated wave with the magnetic moment along the b direction of the tetragonal structure. The depolarization of a neutron beam scattered from the k{sub 2}=(0 0 0.915) reflections reveals a multidomain state but does not allow an unambiguous determination of the spin configuration. Based on present knowledge of borocarbides and other rare-earth systems we give preference to a long-range incommensurate helical structure as the origin of the k{sub 2}=(0 0 0.915) reflections.

  17. Magnetic and Electronic Properties of R3Ni7B2 Compounds where R = Dy, Ho, Er

    NASA Astrophysics Data System (ADS)

    Bucur, N.; Vlaic, P.; Burzo, E.

    2007-04-01

    Band structure calculations show the presence of small magnetic moments at Ni sites. Magnetic measurements at 4.2 K evidenced a relative high anisotropy. Magnetic behavior of nickel is analyzed in spin fluctuation model.

  18. Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds: Crystal structure and magnetic properties

    SciTech Connect

    Morozkin, A.V.; Isnard, O.; Nirmala, R.; Malik, S.K.

    2015-05-15

    The crystal structure of new Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} (Immm, No. 71, oI10) and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} undergoes a ferromagnetic transition at ~66 K, whereas isostructural Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} shows an antiferromagnetic transition at ~52 K and a field-induced metamagnetic transition at low temperatures. Neutron diffraction study shows that, in zero applied field, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} exhibits c-axis antiferromagnetic order with propagation vector K=[1/2, 0, 1/2] below its magnetic ordering temperature and Tb magnetic moment reaches a value of 8.32(5) μ{sub B} at 2 K. The La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibits ferromagnetic like transition at ~42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below ~17 K. The magnetocaloric effect of Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of −14.3 J/kg K, −5.3 J/kg K and −10.3 J/kg K for a field change of 50 kOe near 66 K, 52 K and 42 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +12.8 J/kg K and ~+9.9 J/kg K, respectively at 7 K for a field change of 50 kOe. - Graphical abstract: The (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} supplement the series of Mo{sub 2}NiB{sub 2}-type rare earth compounds, whereas the (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} supplement the series of La{sub 2}Ni{sub 3}-type rare

  19. Missing OH source in a suburban environment near Beijing: observed and modelled OH and HO2 concentrations in summer 2006

    NASA Astrophysics Data System (ADS)

    Lu, K. D.; Hofzumahaus, A.; Holland, F.; Bohn, B.; Brauers, T.; Fuchs, H.; Hu, M.; Häseler, R.; Kita, K.; Kondo, Y.; Li, X.; Lou, S. R.; Oebel, A.; Shao, M.; Zeng, L. M.; Wahner, A.; Zhu, T.; Zhang, Y. H.; Rohrer, F.

    2012-04-01

    Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region 2006) at the suburban site Yufa in the south of Beijing in summer 2006. On most days, local air chemistry was influenced by aged air pollution that was advected by a slow, almost stagnant wind from southern regions. Observed daily maxima of OH and HO2* were in the range of (4-17) × 106 cm-3 and (2-24) × 108 cm-3, respectively. During daytime, OH reactivities were generally high (10-30 s-1) and mainly contributed by VOCs and their oxidation products. The comparison of modelled and measured HOx concentrations reveals a systematic underprediction of OH as a function of NO. A large discrepancy of a factor 2.6 is found at the lowest NO concentration encountered (0.1 ppb), whereas the discrepancy becomes insignificant above 1 ppb NO. This study extends similar observations from the Pearl-River Delta (PRD) in South China to a more urban environment. The OH discrepancy at Yufa can be resolved, if NO-independent additional OH recycling is assumed in the model. The postulated Leuven Isoprene Mechanism (LIM) has the potential to explain the gap between modelled and measured OH at Beijing taking into account conservative error estimates, but still lacks experimental confirmation. This and the hereby unresolved discrepancy at PRD suggest that other VOCs besides isoprene might be involved in the required, additional OH recycling. Fast primary production of ROx radicals up to 7 ppb h-1 was determined at Beijing which was dominated by the photolysis of O3, HONO, HCHO, and dicarbonyls. For a special case, 20 August, when the plume of Beijing city was encountered, a missing primary HOx source (≈ 3 ppb h-1) was determined under high NOx conditions similar to other urban areas like Mexico city. CAREBeijing2006 emphasizes the important role of OVOCs as a radical source and sink, and the need for

  20. Missing OH source in a suburban environment near Beijing: observed and modelled OH and HO2 concentrations in summer 2006

    NASA Astrophysics Data System (ADS)

    Lu, K. D.; Hofzumahaus, A.; Holland, F.; Bohn, B.; Brauers, T.; Fuchs, H.; Hu, M.; Häseler, R.; Kita, K.; Kondo, Y.; Li, X.; Lou, S. R.; Oebel, A.; Shao, M.; Zeng, L. M.; Wahner, A.; Zhu, T.; Zhang, Y. H.; Rohrer, F.

    2013-01-01

    Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region 2006) at the suburban site Yufa in the south of Beijing in summer 2006. On most days, local air chemistry was influenced by aged air pollution that was advected by a slow, almost stagnant wind from southern regions. Observed daily concentration maxima were in the range of (4-17) × 106 cm-3 for OH and (2-24) × 108 cm-3 for HO2 (including an estimated interference of 25% from RO2). During daytime, OH reactivities were generally high (10-30 s-1) and mainly contributed by observed VOCs and their calculated oxidation products. The comparison of modelled and measured HOx concentrations reveals a systematic underprediction of OH as a function of NO. A large discrepancy of a factor 2.6 is found at the lowest NO concentration encountered (0.1 ppb), whereas the discrepancy becomes insignificant above 1 ppb NO. This study extends similar observations from the Pearl-River Delta (PRD) in South China to a more urban environment. The OH discrepancy at Yufa can be resolved, if NO-independent additional OH recycling is assumed in the model. The postulated Leuven Isoprene Mechanism (LIM) has the potential to explain the gap between modelled and measured OH at Beijing taking into account conservative error estimates, but lacks experimental confirmation. This and the hereby unresolved discrepancy at PRD suggest that other VOCs besides isoprene might be involved in the required, additional OH recycling. Fast primary production of ROx radicals up to 7 ppb h-1 was determined at Beijing which was dominated by the photolysis of O3, HONO, HCHO, and dicarbonyls. For a special case, 20 August, when the plume of Beijing city was encountered, a missing primary HOx source (about 3 ppb h-1) was determined under high NOx conditions similar to other urban areas like Mexico City. CAREBeijing2006 emphasizes the

  1. Broadband Ho{sup 3+}-doped fibre radiation source emitting at 2 {mu}m

    SciTech Connect

    Kurkov, A S; Sholokhov, E M; Paramonov, V M; Kosolapov, A F

    2008-10-31

    A 2-{mu}m broadband radiation source based on a fibre doped with holmium ions, which is pumped by a 1.12-{mu}m ytterbium fibre laser, is developed. The maximum output power of 8 mW is achieved for the emission spectrum width of 45 nm. (active optical fibres)

  2. OH Oxidation of α-Pinene in the Atmosphere Simulation Chamber SAPHIR: Investigation of the Role of Pinonaldehyde Photolysis as an HO2 Source

    NASA Astrophysics Data System (ADS)

    Kaminski, M.; Acir, I. H.; Bohn, B.; Dorn, H. P.; Fuchs, H.; Häseler, R.; Hofzumahaus, A.; Li, X.; Rohrer, F.; Tillmann, R.; Wegener, R.; Kiendler-Scharr, A.; Wahner, A.

    2015-12-01

    About one third of the land surface is covered by forests, emitting approximately 75% of the total biogenic volatile organic compounds (BVOCs). The main atmospheric sink of these BVOCs during daytime is the oxidation by the hydroxyl radical (OH). Over the last decades field campaigns investigating the radical chemistry in forested regions showed that atmospheric chemistry models are often not able to describe the measured OH concentration well. At low NO concentrations and an OH reactivity dominated by BVOCs the OH was underestimated. This discrepancy could only partly be explained by the discovery of new OH regeneration pathways in the isoprene oxidation mechanism. Field campaigns in the U.S.A and Finland (Kim 2013 ACP, Hens 2014 ACP) demonstrated that in monoterpene (e.g. α-pinene) dominated environments model calculations also underpredict the observed HO2 and OH concentrations significantly even if the OH budget was closed by the measured OH production and destruction terms. These observations suggest the existence of an unaccounted source of HO2. One potential HO2 source in forests is the photolysis of monoterpene degradation products such as aldehydes. In the present study the photochemical degradation mechanism of α-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR. The focus of this study was in particular on the investigation of the role of pinonaldehyde, a main first generation product of α-pinene, as a possible HO2 source. For that purpose the pinonaldehyde yields of the reaction α-pinene + OH were determined at ambient monoterpene concentrations (<5 ppb) under low NOx as well as high NOx conditions. The pinonaldehyde yield under high NOx conditions (30.5 %) is in agreement with literature values of Wisthaler (2001 AE) and Aschmann (2002 JGR), under low NOx conditions the yield (10.8 %) is approximately a factor of three lower than the value published by Eddingsaas (2012 ACP). In a second set of experiments the photolysis

  3. Magnetic structures of R5Ni2In4 and R11Ni4In9 ( R = Tb and Ho): Strong hierarchy in the temperature dependence of the magnetic ordering in the multiple rare-earth sublattices

    SciTech Connect

    Ritter, C.; Provino, A.; Manfrinetti, P.; Pecharsky, V. K.; Gschneidner, Jr., K. A.; Dhar, S. K.

    2015-11-09

    In this study, the magnetic properties and magnetic structures of the R5Ni2In4 and the microfibrous R 11Ni4In9 compounds with R = Tb and Ho have been examined using magnetization, heat capacity, and neutron diffraction data. Rare earth atoms occupy three and five symmetrically inequivalent rare earth sites in R5Ni2In4 and R 11Ni4In9 compounds, respectively. As a result of the intra- and inter-magnetic sublattice interactions, the magnetic exchange interactions are different for various rare earth sites; this leads to a cascade of magnetic transitions with a strong hierarchy in the temperature dependence of the magnetic orderings.

  4. Antimonide-Based Heterostructure p-Channel MOSFETs With Ni-Alloy Source/Drain

    DTIC Science & Technology

    2013-11-01

    IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 11, NOVEMBER 2013 1367 Antimonide-Based Heterostructure p-Channel MOSFETs With Ni-Alloy Source/Drain Ze...density of 2×1012cm−2. Index Terms— Antimonide semiconductors, metal source/drain (S/D), Ni-GaSb, p-channel MOSFET . I. INTRODUCTION ANTIMONIDE-based...channel MOSFETs [3], [4], performance of III–V p- MOSFETs traditionally lagged behind. Recently, high-performance antimonide p- MOSFETs have been

  5. A 15 W 1152 nm Raman fiber laser with 6 nm spectral width for Ho3+-doped crystal's pumping source

    NASA Astrophysics Data System (ADS)

    Chen, Xiuyan; Jiang, Huawei

    2016-12-01

    A 11.5 W 1152 nm Raman fiber laser with 6 nm spectral width was demonstrated based on the resonator constructed with one fiber loop mirror and one fiber Bragg grating. By mans of experimental measurement and theoretical calculation, the reflectivity of the fiber loop mirror was confirmed as 0.93. The Yb3+-doped 1090 nm fiber length was about 5 m. When the maximum pumping power of 976 nm laser was 54.8 W, 32.2 W 1090 nm laser was obtained and the optical to optical conversion efficiency from 1090 nm to 1152 nm light was 48%. Finally, the 1152 nm Raman fiber laser was used for pumping Ho3+:LLF crystal, and the 1194 nm fluorescence emission peak was detected for the first time.

  6. A Source Manual for Information on NITINOL and NiTi

    DTIC Science & Technology

    1978-02-13

    NSWC/WOL TR 78-26/ A SOURCE MANUAL FOR INFORMATION ON <z NITINOL AND NiTi BY DAVID GOLDSTEIN RESEARCH AND TECHNOLOGY DEPARTMENT 13 FEBRUARY 1978 C...Conthinua owevess, side it necessary and identity by bWeck ammmber) NITINOL Nickel-Titanium Alloys NiTi Shape Memory Effect Heat Engines W0. A WRACT...Conshnue an reverse Wde Ifftoeseat and Identify by Weoek nmmer) This manual is a current listing of most of the published literature on NITINOL and NiTi

  7. Source of Scatter in the Creep Lives of NiAl(Hf) Single Crystals Revealed

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In recent years, there has been an increased emphasis in developing NiAl-based alloys for high- temperature applications in aircraft engines. In comparison to commercial superalloys, binary NiAl has a higher melting temperature, lower density, larger thermal conductivity, and better oxidation resistance. These properties make it a desirable material to replace superalloys as blades and vanes in aircraft engines. Despite this attractive combination of properties, binary NiAl cannot be used as a reliable structural material because of its low-temperature brittleness and poor high-temperature creep strength. GE Aircraft Engines in Cincinnati, Ohio, has recently developed NiAl(Hf) alloys that have creep strengths comparable to commercial superalloys while maintaining the other desirable properties of binary NiAl. The microstructures of these alloys consist of finely distributed G-phase (Ni_(16)Hf_(6)Si_(7)) precipitates, which strengthen the NiAl matrix. However, while the creep properties of these alloys were being evaluated, considerable scatter was observed in the creep lives of specimens tested under identical stress and temperature conditions. Although these alloys had nominally the same composition, the test specimens were obtained from four different ingots (A, B, C, and D) that had been heat treated under similar conditions. The NASA Lewis Research Center began the present study at the request of GE Aircraft Engines under a Space Act Agreement to identify the source of this scatter.

  8. Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere

    NASA Astrophysics Data System (ADS)

    Lu, K. D.; Rohrer, F.; Holland, F.; Fuchs, H.; Bohn, B.; Brauers, T.; Chang, C. C.; Häseler, R.; Hu, M.; Kita, K.; Kondo, Y.; Li, X.; Lou, S. R.; Nehr, S.; Shao, M.; Zeng, L. M.; Wahner, A.; Zhang, Y. H.; Hofzumahaus, A.

    2011-04-01

    Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15-26) × 106 cm-3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1-0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the

  9. Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere

    NASA Astrophysics Data System (ADS)

    Lu, K. D.; Rohrer, F.; Holland, F.; Fuchs, H.; Bohn, B.; Brauers, T.; Chang, C. C.; Häseler, R.; Hu, M.; Kita, K.; Kondo, Y.; Li, X.; Lou, S. R.; Nehr, S.; Shao, M.; Zeng, L. M.; Wahner, A.; Zhang, Y. H.; Hofzumahaus, A.

    2012-02-01

    Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15-26) × 106 cm-3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1-0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the

  10. Theoretical Studies of the HO/HO2 Catalytic Cycle for Ozone Destruction

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Langhoff, Steve R. (Technical Monitor)

    1996-01-01

    Recently it has been determined that the HO/HO2 catalytic cycle accounts for nearly one-half of the total ozone depletion in the lower stratosphere. The catalytic cycle is: (1) HO + O3 yields HO2 + O2; (2) HO2 + O3 yields HO + O2 + O2. The net reaction is 2O3 yields 3O2. The rate limiting step in this process is the reaction of HO2 with ozone. There is a problem extending the experimental measurement of the rate of this reaction over the range 233-400 K down to stratospheric temperatures of 210-220 K. Therefore we have undertaken a project to determine the temperature dependence of the rate constant for this reaction in the low temperature region. The first step in this project, which is described in this poster, is the determination of the relevant potential energy surfaces. The calculations use CASSCF/derivative methods to define the pathways followed by CASSCF/ACPF to determine the energetics. The HO + O3 reaction is found to proceed through an HO4 complex, which is unstable with respect to HO2 + O2. The HO2 +O3 reaction is more complex. One pathway, which has been characterized, is the formation of an HO5 complex which decomposes to HO3 + O2 and subsequently to HO + O2 + O2. Another pathway, which is believed to also play a role, is hydrogen abstraction to give O2 + HO3 and subsequent decomposition of HO3 to HO + O2. Isotopic labeling experiments indicate that the later pathway is dominant. However, so far attempts to locate the saddle point for this pathway have not been successful. We have also characterized the potential energy surfaces for a number of species involved in these reactions, including HO3 and triplet O4. The triplet O4 species is probably involved in the reaction of vibrationally excited O2 with ground state O2 leading to O3 + O. The latter reaction is believed to be important as an additional source of stratospheric ozone.

  11. Characterization of a Ho:Tm:Cr:YAG laser with a Cr:GSAG laser as pumping source

    NASA Technical Reports Server (NTRS)

    Henderson, George W.

    1989-01-01

    Rare earth lasers were in existance since the first laser was developed. The primary lasing elements for the class of lasers in the infrared was neodymium and chromium. However, the need for eye safe lasers in the mid-infrared range has prompted an enormous amount of research to the use of other elements. Holmium was investigated extensively as the source of infrared radiation for atmospheric research as well as medical research. The results and procedure are briefly discussed.

  12. Chemistry of HO x radicals in the upper troposphere

    NASA Astrophysics Data System (ADS)

    Jaeglé, Lyatt; Jacob, Daniel J.; Brune, William H.; Wennberg, Paul O.

    Aircraft observations from three recent missions (STRAT, SUCCESS, SONEX) are synthesized into a theoretical analysis of the factors controlling the concentrations of HO x radicals (HO x=OH+peroxy) and the larger reservoir family HO y (HO y=HO x+2H 2O 2+2CH 3OOH+HNO 2+HNO 4) in the upper troposphere. Photochemical model calculations capture 66% of the variance of observed HO x concentrations. Two master variables are found to determine the variance of the 24 h average HO x concentrations: the primary HO x production rate, P(HO x), and the concentration of nitrogen oxide radicals (NO x=NO+NO 2). We use these two variables as a coordinate system to diagnose the photochemistry of the upper troposphere and map the different chemical regimes. Primary HO x production is dominated by the O( 1D)+H 2O reaction when [H 2O]>100 ppmv, and by photolysis of acetone (and possibly other convected HO x precursors) under drier conditions. For the principally northern midlatitude conditions sampled by the aircraft missions, the HO x yield from acetone photolysis ranges from 2 to 3. Methane oxidation amplifies the primary HO x source by a factor of 1.1-1.9. Chemical cycling within the HO x family has a chain length of 2.5-7, while cycling between the HO x family and its HO y reservoirs has a chain length of 1.6-2.2. The number of ozone molecules produced per HO y molecule consumed ranges from 4 to 12, such that ozone production rates vary between 0.3 and 5 ppbv d -1 in the upper troposphere. Three chemical regimes (NO x-limited, transition, NO x-saturated) are identified to describe the dependence of HO x concentrations and ozone production rates on the two master variables P(HO x) and [NO x]. Simplified analytical expressions are derived to express these dependences as power laws for each regime. By applying an eigenlifetime analysis to the HO x-NO x-O 3 chemical system, we find that the decay of a perturbation to HO y in the upper troposphere (as from deep convection) is represented

  13. Sources of global warming in upper ocean temperature during El Niño

    USGS Publications Warehouse

    White, Warren B.; Cayan, Daniel R.; Dettinger, Mike; Auad, Guillermo

    2001-01-01

    Global average sea surface temperature (SST) from 40°S to 60°N fluctuates ±0.3°C on interannual period scales, with global warming (cooling) during El Niño (La Niña). About 90% of the global warming during El Niño occurs in the tropical global ocean from 20°S to 20°N, half because of large SST anomalies in the tropical Pacific associated with El Niño and the other half because of warm SST anomalies occurring over ∼80% of the tropical global ocean. From examination of National Centers for Environmental Prediction [Kalnay et al., 1996] and Comprehensive Ocean-Atmosphere Data Set [Woodruff et al., 1993] reanalyses, tropical global warming during El Niño is associated with higher troposphere moisture content and cloud cover, with reduced trade wind intensity occurring during the onset phase of El Niño. During this onset phase the tropical global average diabatic heat storage tendency in the layer above the main pycnocline is 1–3 W m−2above normal. Its principal source is a reduction in the poleward Ekman heat flux out of the tropical ocean of 2–5 W m−2. Subsequently, peak tropical global warming during El Niño is dissipated by an increase in the flux of latent heat to the troposphere of 2–5 W m−2, with reduced shortwave and longwave radiative fluxes in response to increased cloud cover tending to cancel each other. In the extratropical global ocean the reduction in poleward Ekman heat flux out of the tropics during the onset of El Niño tends to be balanced by reduction in the flux of latent heat to the troposphere. Thus global warming and cooling during Earth's internal mode of interannual climate variability arise from fluctuations in the global hydrological balance, not the global radiation balance. Since it occurs in the absence of extraterrestrial and anthropogenic forcing, global warming on decadal, interdecadal, and centennial period scales may also occur in association with Earth's internal modes of climate variability on those scales.

  14. Hetero-metallic {3d-4f-5d} complexes: preparation and magnetic behavior of trinuclear [(L(Me2)Ni-Ln){W(CN)(8)}] compounds (Ln = Gd, Tb, Dy, Ho, Er, Y; L(Me2) = Schiff base) and variable SMM characteristics for the Tb derivative.

    PubMed

    Sutter, Jean-Pascal; Dhers, Sébastien; Rajamani, Raghunathan; Ramasesha, S; Costes, Jean-Pierre; Duhayon, Carine; Vendier, Laure

    2009-07-06

    Assembling bimetallic {Ni-Ln}(3+) units and {W(CN)(8)}(3-) is shown to be an efficient route toward heteronuclear {3d-4f-5d} compounds. The reaction of either the binuclear [{L(Me2)Ni(H(2)O)(2)}{Ln(NO(3))(3)}] complexes or their mononuclear components [L(Me2)Ni] and Ln(NO(3))(3) with (HNBu(3))(3){W(CN)(8)} in dmf followed by diffusion of tetrahydrofuran yielded the trinuclear [{L(Me2)NiLn}{W(CN)(8)}] compounds 1 (Ln = Y), 2a,b (Gd), 3a,b (Tb), 4 (Dy), 5 (Ho), and 6 (Er) as crystalline materials. All of the derivatives possess the trinuclear core resulting from the linkage of the {W(CN)(8)} to the Ni center of the {Ni-Ln} unit. Differences are found in the solvent molecules acting as ligands and/or in the lattice depending on the crystallization conditions. For all the compounds ferromagnetic {Ni-W} and {Ni-Ln} (Ln = Gd, Tb, Dy, and Er} interactions are operative resulting in high spin ground states. Parameterization of the magnetic behaviors for the Y and Gd derivatives confirmed the strong cyano-mediated {Ni-W} interaction (J(NiW) = 27.1 and 28.5 cm(-1)) compared to the {Ni-Gd} interaction (J(NiGd) = 2.17 cm(-1)). The characteristic features for slow relaxation of the magnetization are observed for two Tb derivatives, but these are modulated by the crystal phase. Analysis of the frequency dependence of the alternating current susceptibility data yielded U(eff)/k(B) = 15.3 K and tau(0) = 4.5 x 10(-7) s for one derivative whereas no maxima of chi(M)'' appear above 2 K for the second one.

  15. Long-term monitoring of airborne nickel (Ni) pollution in association with some potential source processes in the urban environment.

    PubMed

    Kim, Ki-Hyun; Shon, Zang-Ho; Mauulida, Puteri T; Song, Sang-Keun

    2014-09-01

    The environmental behavior and pollution status of nickel (Ni) were investigated in seven major cities in Korea over a 13-year time span (1998-2010). The mean concentrations of Ni measured during the whole study period fell within the range of 3.71 (Gwangju: GJ) to 12.6ngm(-3) (Incheon: IC). Although Ni values showed a good comparability in a relatively large spatial scale, its values in most cities (6 out of 7) were subject to moderate reductions over the study period. To assess the effect of major sources on the long-term distribution of Ni, the relationship between their concentrations and the potent source processes like non-road transportation sources (e.g., ship and aircraft emissions) were examined from some cities with port and airport facilities. The potential impact of long-range transport of Asian dust particles in controlling Ni levels was also evaluated. The overall results suggest that the Ni levels were subject to gradual reductions over the study period irrespective of changes in such localized non-road source activities. The pollution of Ni at all the study sites was maintained well below the international threshold (Directive 2004/107/EC) value of 20ngm(-3).

  16. Room-temperature metal-hydride discharge source, with observations on NiH and FeH.

    PubMed

    Vallon, Raphaël; Ashworth, Stephen H; Crozet, Patrick; Field, Robert W; Forthomme, Damien; Harker, Heather; Richard, Cyril; Ross, Amanda J

    2009-11-26

    A metal sputtering source suitable for laboratory production of metal hydrides is described. Sputtering from pure nickel or iron in an Ar/H(2) discharge is analyzed at low resolution. High resolution laser excitation and dispersed fluorescence spectra of NiH have also been recorded. The source has been designed to operate with a ferromagnetic circuit for Zeeman spectroscopy. Signals from the source are strong enough to record dispersed fluorescence from NiH by Fourier transform interferometry in magnetic fields up to 1 T. We establish that FeH can also be formed in this source.

  17. Ternary rare-earth aluminium intermetallics RE10TAl3 (RE = Y, Ho, Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt) with an ordered anti-Co2Al5 structure.

    PubMed

    Benndorf, Christopher; Eckert, Hellmut; Janka, Oliver

    2017-01-24

    Twenty new rare-earth metal rich intermetallic aluminium compounds, RE10TAl3 (RE = Y, Ho, Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), were synthesized by arc melting the elements. The compounds crystallize, in analogy to e.g. the respective Cd representatives, with a ternary ordered structure as anti-type to the hexagonal Co2Al5 type, with the space group P63/mmc. The three crystallographically independent rare-earth metal sites occupy the aluminium positions of the aristotype, while the transition metal and aluminium atoms are ordered on the two cobalt sites. Like other rare-earth rich compounds the RE10TX3 members also exhibit transition-metal-centred T@RE6 trigonal prisms as striking structural building units. The prepared compounds have been investigated by susceptibility measurements and (27)Al solid-state MAS-NMR measurements conducted on the Pauli-paramagnetic Y and Lu compounds. Some compounds show a certain amount of disorder as seen from the single crystal structure analysis and from signal broadening in the NMR investigations. By separating Knight shifts from second-order quadrupolar shifts via field dependent measurements, monotonic trends can be discerned regarding the effect of the T atom valence electron concentration and period number, as well as the effect of the closed 4f shell contributed in the Lu compounds. The results confirm that a comparison of Knight shifts within a series of isotypic compounds can reveal important electronic structure information in intermetallic systems.

  18. Derivation of hydroperoxyl radical (HO2) levels at an urban site via measurement of pernitric acid (HO2NO2) by iodide chemical ionization mass spectrometry (I(-)-CIMS).

    PubMed

    Chen, Dexian; Huey, L Gregory; Tanner, David J; Li, Jianfeng; Ng, Nga Lee; Wang, Yuhang

    2017-02-17

    Hydroperoxyl radical (HO2) is a key species to atmospheric chemistry. At warm temperatures, the hydroperoxyl radical (HO2) and NO2 come to a rapid steady state with pernitric acid (HO2NO2). This paper presents the derivation of HO2 from observations of HO2NO2 and NO2 in metropolitan Atlanta, US in winter 2014 and summer 2015. HO2 was observed to have a diurnal cycle with morning concentrations suppressed by high NO from the traffic. At night, derived HO2 levels were nonzero and exhibited correlations with O3 and NO3, consistent with previous studies that ozonolysis and oxidation by NO3 are sources of nighttime HO2. Measured and model calculated HO2 were in reasonable agreement: Without the constraint of measured HO2NO2 , the model reproduced HO2 with a model-to-observed ratio (M/O) 1.27 (r = 0.54) for winter, 2014, and 0.70 (r = 0.80) for summer, 2015. Adding measured HO2NO2 as a constraint, the model predicted HO2 with M/O = 1.13 ((r = 0.77) for winter 2014, and 0.90 ((r = 0.97) for summer 2015. These results demonstrate the feasibility of deriving HO2 from HO2NO2 measurements in warm regions where HO2NO2 has a short lifetime.

  19. Infrared Identification of HO2 and HO3 Radicals in Irradiated Ices

    NASA Astrophysics Data System (ADS)

    Cooper, P. D.; Moore, M. H.; Hudson, R. L.

    2006-05-01

    Absorption bands at 1259 and 1142 cm-1 in H2O-O2 ice mixtures irradiated with 0.8 MeV protons at 9 K, have been assigned to the HO3 and HO2 radicals respectively. The assignment of these bands is based upon isotopic shift measurements when 18O2 is used. These bands are also observed in irradiated H2O-O3 and pure H2O2 ices. In each case, they are formed by the following reactions: H + O3 → HO3 H + O2 → HO2 While neither radical has been observed in ice using infrared spectroscopy before, the HO2 radical is known to form in irradiated water ice, but remarkably, the lesser known HO3 is the more prominent spectral feature. These species are probably formed in the surfaces of icy outer solar system bodies where O2 and O3 have already been observed. Their ability to remain trapped in ice is unknown and their reactivity at typical surface temperatures may prevent signficant concentrations being produced. However, even as intermediate species, due to their reactivity they may constitute an important component of the oxidant population in such ices. If they can remain trapped, they may provide a potential energy source for organic reactions or even microbial life in places such as Europa's sub-surface ocean.

  20. Minfong Ho: Politics in Prose

    ERIC Educational Resources Information Center

    Wiggins, Joy L.

    2006-01-01

    In this article, the author interviews Minfong Ho, an award-winning Thai writer of children's and young adult novels. Ho was born in Burma to Chinese parents in 1951, raised in Singapore and Thailand, educated in Bangkok, Taiwan, and at Cornell University in New York. Ho's first novel, "Sing to the Dawn," won first prize from the Council of…

  1. Behavior of OH and HO 2 in the winter atmosphere in New York City

    NASA Astrophysics Data System (ADS)

    Ren, Xinrong; Brune, William H.; Mao, Jingqiu; Mitchell, Michael J.; Lesher, Robert L.; Simpas, James B.; Metcalf, Andrew R.; Schwab, James J.; Cai, Chenxia; Li, Yongquan; Demerjian, Kenneth L.; Felton, Henry D.; Boynton, Garry; Adams, Allen; Perry, Jacqueline; He, Yi; Zhou, Xianliang; Hou, Jian

    Hydroxyl (OH) and hydroperxy (HO 2) radicals, collectively known as HO x, were measured during an intensive field study in January and February 2004 in New York City. Much less OH and HO 2 levels were observed than in the summer of 2001 at the same site. On average, the maximum daytime mixing ratios were 0.05 pptv (1.4×10 6 cm -3) for OH and 0.7 pptv for HO 2, which were about one fifth of the levels in the summer of 2001. A zero-dimensional chemical model, based on the regional atmospheric chemical mechanism (RACM) and constrained by the measured concentrations of O 3, NO, NO 2, CO, SO 2, speciated volatile organic compounds (VOCs) and meteorological parameters, was used to study the HO x chemistry in this environment. The model generally reproduced the daytime OH well, with a median measured-to-model ratio of 0.98. However, HO 2 was significantly under-predicted both at day and at night, with a median measured-to-model ratio of 6.0 during daytime. The discrepancy is pronounced when NO concentrations were high, a result that is consistent with some previous studies in urban environments. Photolysis of HONO was the dominant calculated HO x source during daytime; O 3 reactions with alkenes became the main calculated HO x source at night. The main calculated HO x sink was the OH reaction with NO 2. The discrepancy between measured and modeled HO 2 may be caused by significant HO x production that is missing in the model. An additional HO 2 production of up to 3×10 7 cm -3 s -1 (1.1 pptv s -1), which is three times the calculated HO x production, is needed. This HO 2 production can come either from unknown new HO x production or from unknown HO 2 recycling that does not go through OH.

  2. Tropospheric HO determination by FAGE

    NASA Technical Reports Server (NTRS)

    Hard, T. M.; Obrien, R. J.; Chan, C. Y.; Mehrabzadeh, A. A.

    1986-01-01

    In the detection of tropospheric HO by laser excited fluorescence, and alternative air-sampling method, named FAGE (Fluorescence Assay with Gas Expansion) was introduced. Here the air is expanded through a nozzle prior to excitation, in order to improve the ratio of the HO signal to the scattered, fluorescent, and photolytic backgrounds. The improvement comes from the differing pressure dependence of the intensities of these four terms, as well as the distinguishability of their temporal waveforms at low pressures when excited by a pulsed laser. HO has been excited by a YAG/dye laser. Other lasers and pumping paths may perform as well or better in this method. With FAGE, chemical modulation of the HO signal was achieved by hydrocarbon addition to the nozzle flow, converting photolytic HO from an interference to a background. Chemical calibration of the instrumental response to external HO was also achieved, by hydrocarbon decay, at HO concentrations within the ambient range.

  3. HO(x) Measurements in PEM Tropics B with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

    NASA Technical Reports Server (NTRS)

    Brune, William H.

    2001-01-01

    The primary objective of PEM Tropics B was to study the processes responsible for the production and loss of tropospheric ozone over the tropical Pacific. This region of the globe contains very clean air as well as aged, polluted air that was advected from both the Asian and American continents. Understanding ozone requires understanding of HO(x) (HO(x) = OH + HO2) chemistry, since the reaction between H02 and NO leads to ozone production and the production of OH often requires ozone loss. In addition, OH is the atmosphere's primary oxidant. Since most atmospheric oxidation is thought to occur in the tropical lower troposphere, measurements during PEM Tropics B should provide an important test of the OH abundances and distributions. Thus, understanding and thoroughly testing HO(x) processes was an important objective of PEM Tropics B. Several issues need to be tested, One is HO, production rates and sources, since HO,, production directly affects ozone production and loss. Another is HO(x) behavior in and around clouds, since HO(x) is lost to cloud particles, but convection may bring HO(x) precursors from near the surface to the upper troposphere. A third is the rise and fall of HO(x) at sunrise and sunset, since these variations give strong indications of the important sources and sinks of HO(x). Making and interpreting high-quality OH and H02 measurements from the NASA DC-8 during PEM Tropics B is the objective of this research effort.

  4. Flashlamp-pumped Ho:Tm:Cr:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Murray, Keith E. (Inventor); Kokta, Milan R. (Inventor)

    1997-01-01

    A room temperature solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG host material doped with a concentration of about 0.35% Ho ions, about 5.57% Tm ions and at least about 1.01% Cr ions. A broadband energizing source such as a flashlamp is disposed transversely to the laser crystal to energize the Ho ions, Tm ions and Cr ions.

  5. Heterogeneous Uptake of HO2 Radicals onto Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    George, I. J.; Matthews, P. S.; Brooks, B.; Goddard, A.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2011-12-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, together known as HOx, play a vital role in atmospheric chemistry by controlling the oxidative capacity of the troposphere. The atmospheric lifetime and concentrations of many trace reactive species, such as volatile organic compounds (VOCs), are determined by HOx radical levels. Therefore, the ability to accurately predict atmospheric HOx concentrations from a detailed knowledge of their sources and sinks is a very useful diagnostic tool to assess our current understanding of atmospheric chemistry. Several recent field studies have observed significantly lower concentrations of HO2 radicals than predicted using box models, where HO2 loss onto aerosols was suggested as a possible missing sink [1, 2]. However, the mechanism on HO2 uptake onto aerosols and its impact on ambient HOx levels are currently not well understood. To improve our understanding of this process, we have conducted laboratory experiments to measure HO2 uptake coefficients onto submicron aerosol particles. The FAGE (Fluorescence Assay by Gas Expansion) technique, a highly sensitive laser induced fluorescence based detection method, was used to monitor HO2 uptake kinetics onto aerosol particles in an aerosol flow tube. The application of the FAGE technique allowed for kinetic experiments to be performed under low HO2 concentrations, i.e. [HO2] < 109 molecules cm-3. HO2 radicals were produced by the photolysis of water vapour in the presence of O2 and aerosol particles were produced either by atomizing dilute salt solutions or by homogeneous nucleation. HO2 uptake coefficients (γ) have been measured for single-component solid and aqueous inorganic salt and organic aerosol particles with a wide range of hygroscopicities. HO2 uptake coefficients on solid particles were below the detection limit (γ < 0.001), whereas on aqueous aerosols uptake coefficients were somewhat larger (γ = 0.001 - 0.008). HO2 uptake coefficients were highest on aerosols

  6. Orbital degeneracy as a source of frustration in LiNiO2

    NASA Astrophysics Data System (ADS)

    Vernay, F.; Penc, K.; Fazekas, P.; Mila, F.

    2004-07-01

    Motivated by the absence of cooperative Jahn-Teller effect and of magnetic ordering in LiNiO2 , a layered oxide with triangular planes, we study a general spin-orbital model on the triangular lattice. A mean-field approach reveals the presence of several singlet phases between the SU(4) symmetric point and a ferromagnetic phase, a conclusion supported by exact diagonalizations of finite clusters. We argue that one of the phases, characterized by a large number of low-lying singlets associated to dimer coverings of the triangular lattice, could explain the properties of LiNiO2 , while a ferro-orbital phase that lies nearby in parameter space leads to a new prediction for the magnetic properties of NaNiO2 .

  7. Ni distribution in MORB-source-mantle pyroxenites: Traces of melt-rock reaction on a cm-scale

    NASA Astrophysics Data System (ADS)

    Sergeev, D.; Dijkstra, A.; Pettke, T.

    2010-12-01

    Introduction The origin of pyroxenites in mantle peridotites is widely discussed as they represent the most important observed lithological inhomogeneity in the upper mantle. We have studied a case of such mantle heterogeneity, consisting of 1-10 cm thick concordant layers of websteritic pyroxenites within residual MORB-source mantle peridotites, in the Jurassic Pindos Ophiolite (N. Greece). Here we report Ni concentrations in minerals in pyroxenites and we compare them with those in the enclosing peridotites We use this data to test whether these pyroxenite layers are cumulate veins, or the product of melt-rock reactions. Results Ni concentrations analysed by Laser ablation ICP-MS on single olivine grains in thick sections show values for the wall-rock peridotites 2580-3480 μg/g, while 2825-3815 μg/g are measured in pyroxenites layers. We consistently observe higher Ni concentrations (10-20%) in pyroxenites compared to peridotites and we observe the same trend in thick sections containing peridotite and pyroxenite parts. The highest Ni concentrations, up to 4145 μg/g, are found in olivine inclusions - older grains surrounded by newly formed orthopyroxene in pyroxenites. Similar elevated Ni concentrations are also characteristic for single orthopyroxene and clinopyroxene grains in pyroxenites compared to peridotites. Intermediate values are typical for transition zones, as there is no strict contact line on the thick section scale between peridotite and pyroxenite. Discussion The data is consistent with a melt-rock reaction origin for the pyroxenites. Melt-rock reaction in the upper mantle between peridotites and SiO2-rich melts would not significantly lower the whole-rock Ni concentration in the newly-formed hybrid rock (pyroxenites). The transformation of olivine to orthopyroxene would strongly concentrate Ni in the remaining olivine and would also enrich other minerals (Sobolev et al. 2007). This interpretation is fully supported by petrographical

  8. Modifications in surface, structural and mechanical properties of brass using laser induced Ni plasma as an ion source

    NASA Astrophysics Data System (ADS)

    Ahmad, Shahbaz; Bashir, Shazia; Rafique, M. Shahid; Yousaf, Daniel

    2016-03-01

    Laser induced Ni plasma has been employed as source of ion implantation for surface, structural and mechanical properties of brass. Excimer laser (248 nm, 20 ns, 120mJ and 30 Hz) was used for the generation of Ni plasma. Thomson parabola technique was employed to estimate the energy of generated ions using CR39 as a detector. In response to stepwise increase in number of laser pulses from 3000 to 12000, the ion dose varies from 60 × 1013 to 84 × 1016 ions/cm2 with constant energy of 138 KeV. SEM analysis reveals the growth of nano/micro sized cavities, pores, pits, voids and cracks for the ion dose ranging from 60 × 1013 to 70 × 1015 ions/cm2. However, at maximum ion dose of 84 × 1016 ions/cm2 the granular morphology is observed. XRD analysis reveals that new phase of CuZnNi (200) is formed in the brass substrate after ion implantation. However, an anomalous trend in peak intensity, crystallite size, dislocation line density and induced stresses is observed in response to the implantation with various doses. The increase in ion dose causes to decrease the Yield Stress (YS), Ultimate Tensile Strength (UTS) and hardness. However, for the maximum ion dose the highest values of these mechanical properties are achieved. The variations in the mechanical properties are correlated with surface and crystallographical changes of ion implanted brass.

  9. HO:LULF and HO:LULF Laser Materials

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Morrison, Clyde A. (Inventor); Filer, Elizabeth D. (Inventor); Jani, Mahendra G. (Inventor); Murray, Keith E. (Inventor); Lockard, George E. (Inventor)

    1998-01-01

    A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

  10. On the stability of (3)H and (63)Ni Ultima Gold liquid scintillation sources.

    PubMed

    Nedjadi, Youcef; Duc, Pierre-François; Bochud, François; Bailat, Claude

    2016-12-01

    The stability of (3)H and (63)Ni samples, made with Ultima Gold and Ultima Gold AB using eight aqueous fractions ranging between 0.1% and 10%, was monitored over a period of 32 weeks. Counting rate losses were measured in all cases, but were found to be particularly severe for samples with low aqueous fractions. Hydrodynamic diameter measurements of the reverse micelles of (3)H and (63)Ni in Ultima Gold and Ultima Gold AB samples were performed with dynamic light scattering. For Ultima Gold, the micelle diameters were measured to be about 2nm and slightly dependent of the aqueous fraction, while for Ultima Gold AB they were found to vary strongly with the aqueous fraction and range between 1 and 4nm. The hypothesis that the counting rate instabilities derive from changes in the sizes of micelles was tested by measuring them four times over the monitoring period. The measurement results do not support this claim.

  11. Cobalt internal standard for Ni to assist the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis.

    PubMed

    de Babos, Diego Victor; Bechlin, Marcos André; Barros, Ariane Isis; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta; de Oliveira, Silvana Ruella

    2016-05-15

    A new method is proposed for the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS), employing direct solid sample analysis (DSS) and internal standardization (IS). Cobalt was used as internal standard to minimize matrix effects during Ni determinations, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9937. The performance of the method was checked by analysis of six plant certified reference materials, and the results for Mo and Ni were in agreement with the certified values (95% confidence level, t-test). Analysis was made of different types of plant materials used as renewable sources of energy, including sugarcane leaves, banana tree fiber, soybean straw, coffee pods, orange bagasse, peanut hulls, and sugarcane bagasse. The concentrations found for Mo and Ni ranged from 0.08 to 0.63 ng mg(-1) and from 0.41 to 6.92 ng mg(-1), respectively. Precision (RSD) varied from 2.1% to 11% for Mo and from 3.7% to 10% for Ni. Limits of quantification of 0.055 and 0.074 ng were obtained for Mo and Ni, respectively.

  12. {sup 163}Ho based experiments

    SciTech Connect

    Gastaldo, Loredana

    2015-07-15

    The analysis of the endpoint region of the calorimetrically measured {sup 163}Ho electron capture spectrum is a very promising way to determine the mass of the electron neutrino. The achievable sensitivity of {sup 163}Ho-based experiments and the experimental challenges will be presented. Three large collaborations aim at developing large scale experiments able to reach sub-eV sensitivity. Presently pilot experiments are performed to demonstrate the possibility to calorimetrically measure high precision and high statistics {sup 163}Ho spectra. The different approaches as well as the state of the art of the experimental efforts for the three collaborations will be discussed.

  13. Compact Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1988-01-01

    Longitudinal pumping by laser diodes increases efficiency. Improved holmium:yttrium lithium fluoride laser radiates as much as 56 mW of power at wavelength of 2.1 micrometer. New Ho:YLF laser more compact and efficient than older, more powerful devices of this type. Compact, efficient Ho:YLF laser based on recent successes in use of diode lasers to pump other types of solid-state lasers.

  14. Evaluation of solid sampling for determination of Mo, Ni, Co, and V in soil by high-resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Babos, Diego Victor; Barros, Ariane Isis; Ferreira, Edilene Cristina; Neto, José Anchieta Gomes

    2017-04-01

    New methods are proposed for the determination of Mo, Ni, Co, and V in soils using high-resolution continuum source graphite furnace atomic absorption spectrometry with direct solid sampling. Cobalt and V were simultaneously determined, and different analytical lines of Ni and V were monitored to adjust sensitivity for each sample. Accuracy was checked by means of soil certified reference materials, and also by flame atomic absorption spectrometry as comparative technique. The results for Mo, Ni, Co, and V found by proposed methods were in agreement with certified values and with those obtained by the comparative technique at 95% confidence level. The concentrations found in different soil samples were in the ranges 0.19-1.84 mg kg- 1 (Mo), 9.2-22.7 mg kg- 1 (Ni), 1.1-10.7 mg kg- 1 (Co), and 35.6-426.1 mg kg- 1 (V). The relative standard deviations were in the ranges 3.2-10% (Mo), 2.8-9.8% (Ni), 4.0-9.2% (Co), and 1.2-8.0% (V). The limits of quantification for Mo, Ni, Co, and V were 0.027, 0.071, 0.15, and 1.43 ng, respectively.

  15. Topics in Ho Morphophonology and Morphosyntax

    ERIC Educational Resources Information Center

    Pucilowski, Anna

    2013-01-01

    Ho, an under-documented North Munda language of India, is known for its complex verb forms. This dissertation focuses on analysis of several features of those complex verbs, using data from original fieldwork undertaken by the author. By way of background, an analysis of the phonetics, phonology and morphophonology of Ho is first presented. Ho has…

  16. Heterogeneous Uptake of HO2 Radicals onto Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    George, I. J.; Brooks, B.; Goddard, A.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2010-12-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, known collectively as HOx radicals, are the key reactants that control the oxidative capacity of the troposphere and the atmospheric lifetimes and concentrations of most trace reactive species, i.e. NOx, O3 and volatile organic compounds. Therefore, in order to gain an overall understanding of atmospheric chemistry and to predict the fate of atmospheric pollutants, a detailed knowledge of the sources and sinks of HOx species and their steady-state atmospheric concentrations is crucial. To this end, field measurements of atmospheric HOx concentrations have been recently compared to model predictions to gauge our level of understanding of atmospheric chemistry of trace reactive species. Box models incorporating known gas-phase chemistry have significantly overpredicted steady-state HO2 levels in comparison to field observations, suggesting heterogeneous uptake onto aerosols as a possible missing atmospheric sink for HO2 radicals [1-2]. However, relatively few laboratory studies have been performed to determine the kinetic parameters for HO2 loss onto aerosols, and thus the ability to assess the impact of this mechanism on HOx levels is limited. The goal of this laboratory study is to improve our understanding of the tropospheric HOx budget by measuring HO2 uptake kinetics onto aerosol particles. In this work, HO2 radicals were produced by the photolysis of water vapour and the FAGE (Fluorescence Assay by Gas Expansion) technique was used to monitor HO2 loss kinetics onto aerosol particles in an aerosol flow tube setup. FAGE is a highly sensitive laser-induced fluorescence based detection method for HOx radicals that has allowed for kinetic measurements to be performed under low HO2 concentrations minimizing gas-phase HO2 self reaction, i.e. for [HO2] < 109 molecules cm-3. The mass accommodation coefficient was determined by measuring HO2 uptake onto Cu(II)-doped ammonium sulfate aerosols. Reactive uptake coefficients

  17. NdHO, a novel oxyhydride

    SciTech Connect

    Wideroe, Marius; Fjellvag, Helmer; Norby, Truls; Willy Poulsen, Finn; Willestofte Berg, Rolf

    2011-07-15

    A new metal oxyhydride; neodymium oxyhydride, NdHO, has been synthesized from a reactant mixture of metal hydride (CaH{sub 2} or NdH{sub 3}) and neodymium oxide (Nd{sub 2}O{sub 3}). The unit cell dimensions decrease smoothly in the series from LaHO, CeHO, PrHO to NdHO, in line with the lanthanide contraction. The crystal structure of NdHO is described on the basis of Rietveld refinement on neutron powder diffraction data: Space group: P4/nmm (no. 129, D{sub 4h}{sup 7}). Axis lengths: a=7.8480(5) A, c=5.5601(8) A. Volume: V=342.46(6) A{sup 3}. The tetragonal structure is derived from the fluorite structure, showing complete ordering of hydride and oxide ions over the anion sublatttice. The formation of NdHO was further substantiated by Raman spectroscopy. - Graphical Abstract: View of the NdHO structure. Highlights: > CaH{sub 2} or NdH{sub 3} react with Nd{sub 2}O{sub 3} in reducing atmospheres forming a new oxyhydride, NdHO. > NdHO crystalises in tetragonal space group P4/nmm with axes a=b=7.8480(5) A and c=5.5601(8) A. > The structure is similar to the fluorite structure with complete ordering of hydride and oxide ions. > Unit cell dimensions decrease smoothly in the series from LaHO, CeHO, PrHO to NdHO. > The formation of NdHO is substantiated by Raman spectroscopy.

  18. Layer-structured LiNi0.8Co0.2O2: A new triple (H+/O2-/e-) conducting cathode for low temperature proton conducting solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Fan, Liangdong; Su, Pei-Chen

    2016-02-01

    Solid oxide fuel cells with proton conducting electrolytes (H-SOFCs) show great potential for more efficient energy conversion over their oxygen ionic conducting counterparts at temperatures below 650 °C, providing a comparably high performance cathode material can be available. A brief review of current development of cathode materials shows that materials with triple (oxygen ionic, protonic, and electronic) conducting properties are most promising for H-SOFCs. In this work, a triple-conducting LiNi0.8Co0.2O2 (LNCO) with layered structure, allowing simultaneous conduction of intrinsic oxygen ion and electron as well as the extrinsic proton, is proposed as a cathode material for H-SOFC. The electrochemical impedance spectroscopy analysis of LNCO shows the good oxygen reduction reaction (ORR) activity with a considerably low activation energy of 0.88 eV, and an evident water uptake capability those facilitate the cathode reaction process. Fuel cells using LNCO cathode on a BaZr0.1Ce0.7Y0.2O3 proton-conducting electrolyte render a peak power density of 410 mW cm-2 at 650 °C under H2/air condition, which is higher than most of the typical cathode materials reported with similar cell configurations. This work also demonstrated a new series of simple and low cost cathode materials simultaneously possessing interesting triple-conduction and good ORR activities for low temperature H-SOFCs.

  19. Shape coexistence in 153Ho

    NASA Astrophysics Data System (ADS)

    Pramanik, Dibyadyuti; Sarkar, S.; Saha Sarkar, M.; Bisoi, Abhijit; Ray, Sudatta; Dasgupta, Shinjinee; Chakraborty, A.; Krishichayan, Kshetri, Ritesh; Ray, Indrani; Ganguly, S.; Pradhan, M. K.; Ray Basu, M.; Raut, R.; Ganguly, G.; Ghugre, S. S.; Sinha, A. K.; Basu, S. K.; Bhattacharya, S.; Mukherjee, A.; Banerjee, P.; Goswami, A.

    2016-08-01

    The high-spin states in 153Ho have been studied by the La57(20Ne139,6 n ) reaction at a projectile energy of 139 MeV at the Variable Energy Cyclotron Centre (VECC), Kolkata, India, utilizing an earlier campaign of the Indian National Gamma Array (INGA) setup. Data from γ -γ coincidence, directional correlation, and polarization measurements have been analyzed to assign and confirm the spins and parities of the levels. We have suggested a few additions and revisions of the reported level scheme of 153Ho. The RF-γ time difference spectra have been useful to confirm the half-life of an isomer in this nucleus. From the comparison of experimental and theoretical results, it is found that there are definite indications of shape coexistence in this nucleus. The experimental and calculated lifetimes of several isomers have been compared to follow the coexistence and evolution of shape with increasing spin.

  20. Measurements of HO2 chemical kinetics with a new detection method

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Manzanares, E. R.

    1985-01-01

    In this research program, HO2 was detected by the OH(A-X) photofragment from dissociative excitation of HO2 at 147 nm. This detection method was applied to measure the reaction rate constant of HO2 + O3. This reaction rate constant is needed for the understanding of stratospheric chemistry. Since C12 was used in the flow system, photoexcitation of C12 may produce fluorescence to interfere with the measurements. Thus, the photoexcitation process of C12 in the vacuum ultraviolet region was also examined in this research period using synchrotron radiation as a light source. The research results are summarized.

  1. Development of a Chemiluminescence Method for Gas-Phase HO2 Detection

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Lloyd, J.; Springston, S.

    2003-12-01

    Hydroperoxyl Radical (HO2) is a highly reactive intermediate species that participates in photochemical processes in the troposphere. Accurate measurement of HO2 will facilitate the verification of the ozone production mechanism used by the atmospheric chemistry community. HO2 is also the major source of H2O2, which is responsible for the oxidation of SO2 in droplets. Here, we describe a new HO2 detection method based on flow injection analysis (FIA) with a chemiluminescence detector. Gas-phase HO2 is first scrubbed into a pH 9 borax buffer solution, then injected into a chemiluminescence detector, where HO2 and its conjugate base O2- react with MCLA, a synthetic analog of the luciferin from the crustacean Cypridina, to emit light at 465 nm. This technique shows high sensitivity (DL = 0.1 nM in liquid phase or 1 pptv in gas phase) and selectivity for the HO2 / O2- system. A unique feature of our technique is the calibration with a radiolytic method that uses a 60Co gamma ray source to quantitatively produce stable aqueous HO2 / O2- standards. This calibration method is highly reproducible, producing an instrument response that varies less than 5% from day to day. We tested our instrument in the meteorology field at Brookhaven National Laboratory (BNL), which is considered a clean remote rural site with background ozone levels about 30 ppbv. On July 17, 2003, a clear sunny day, with a steady NW wind, HO2 started to build up after sunrise and reached a maximum of 9 pptv at about 3 pm local time, approximately two hours after the maximum solar intensity. Our technique has the advantages of simplicity, low cost and ease of operation. It is especially suitable for field measurements, where space and energy resources are usually limited.

  2. A Reevaluation of Airborne HO(x) Observations from NASA Field Campaigns

    NASA Technical Reports Server (NTRS)

    Olson, Jennifer; Crawford, James H.; Chen, Gao; Brune, William H.; Faloona, Ian C.; Tan, David; Harder, Hartwig; Martinez, Monica

    2006-01-01

    In-situ observations of tropospheric HO(x) (OH and HO2) obtained during four NASA airborne campaigns (SUCCESS, SONEX, PEM-Tropics B and TRACE-P) are reevaluated using the NASA Langley time-dependent photochemical box model. Special attention is given to previously diagnosed discrepancies between observed and predicted HO2 which increase with higher NO(x) levels and at high solar zenith angles. This analysis shows that much of the model discrepancy at high NO(x) during SUCCESS can be attributed to modeling observations at time-scales too long to capture the nonlinearity of HO(x) chemistry under highly variable conditions for NO(x). Discrepancies at high NO(x) during SONEX can be moderated to a large extent by complete use of all available precursor observations. Differences in kinetic rate coefficients and photolysis frequencies available for previous studies versus current recommendations also explain some of the disparity. Each of these causes is shown to exert greater influence with increasing NO(x) due to both the chemical nonlinearity between HO(x) and NO(x) and the increased sensitivity of HO(x) to changes in sources at high NO(x). In contrast, discrepancies at high solar zenith angles will persist until an adequate nighttime source of HO(x) can be identified. It is important to note that this analysis falls short of fully eliminating the issue of discrepancies between observed and predicted HO(x) for high NO(x) environments. These discrepancies are not resolved with the above causes in other data sets from ground-based field studies. Nevertheless, these results highlight important considerations in the application of box models to observationally based predictions of HO(x) radicals.

  3. Crystalline Ni3C as both carbon source and catalyst for graphene nucleation: a QM/MD study

    PubMed Central

    Jiao, Menggai; Li, Kai; Guan, Wei; Wang, Ying; Wu, Zhijian; Page, Alister; Morokuma, Keiji

    2015-01-01

    Graphene nucleation from crystalline Ni3C has been investigated using quantum chemical molecular dynamics (QM/MD) simulations based on the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. It was observed that the lattice of Ni3C was quickly relaxed upon thermal annealing at high temperature, resulting in an amorphous Ni3C catalyst structure. With the aid of the mobile nickel atoms, inner layer carbon atoms precipitated rapidly out of the surface and then formed polyyne chains and Y-junctions. The frequent sinusoidal-like vibration of the branched carbon configurations led to the formation of nascent graphene precursors. In light of the rapid decomposition of the crystalline Ni3C, it is proposed that the crystalline Ni3C is unlikely to be a reaction intermediate in the CVD-growth of graphene at high temperatures. However, results present here indicate that Ni3C films can be employed as precursors in the synthesis of graphene with exciting possibility. PMID:26169042

  4. Tm:YLF Pumped Ho:YAG and Ho:LuAG Lasers

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Reichle, Donald J.; Walsh, Brian M.; Axenson, Theresa J.

    2004-01-01

    Room temperature Ho:YAG and Ho:LuAG lasers pumped by a Tm:YLF laser demonstrated a 3.4 mJ threshold and 0.41 slope efficiency, incident optical to laser output energy. Results for numerous rod lengths, Ho concentrations, and output mirror reflectivities are presented.

  5. Enhancement of programming speed on gate-all-around poly-silicon nanowire nonvolatile memory using self-aligned NiSi Schottky barrier source/drain

    NASA Astrophysics Data System (ADS)

    Ho, Ching-Yuan; Chang, Yaw-Jen; Chiou, Y. L.

    2013-08-01

    The programming characteristics of gate-all-around silicon-oxide-nitride-oxide silicon (SONOS) nonvolatile memories are presented using NiSi/poly-Si nanowires (SiNW) Schottky barrier (SB) heterojunctions. The non-uniform thermal stress distribution on SiNW channels due to joule heating affected the carrier transport behavior. Under a high drain voltage, impact ionization was found as a large lateral field enhances carrier velocity. As gate voltage (Vg) increased, the difference in the drain current within a range of various temperature conditions can be mitigated because a high gate field lowers the SB height of a NiSi source/SiNW/NiSi drain junction to ensure efficient hot-carrier generation. By applying the Fowler-Nordheim programming voltage to the SONOS nanowire memory, the SB height (Φn = 0.34 eV) could be reduced by image force; thus, hot electrons could be injected from SB source/drain electrodes into the SiN storage node. To compare both SiNW and Si nanocrystal SONOS devices, the SB SiNW SONOS device was characterized experimentally to propose a wider threshold-voltage window, exhibiting efficient programming characteristics.

  6. Cobalt-related features of spectral and magnetic properties of RNi4Co (R=Ho, Er)

    NASA Astrophysics Data System (ADS)

    Lukoyanov, A. V.; Knyazev, Yu. V.; Kuz`min, Yu. I.; Kuchin, A. G.

    2014-11-01

    In this paper we investigate spectral and magnetic properties of RNi4Co (R=Ho, Er) intermetallics to reveal the features associated with the presence of Co substituting ion in comparison with the parent HoNi5 and ErNi5 compounds. Our ab initio LSDA+U calculations show that in the electronic structure Co states are strongly manifested near the Fermi energy for the case of Co in 2c position, while Co in 3g position results only in weak changes of the total DOS curve. Theoretical optical conductivity calculated assuming Co equally redistributed among 2c or 3g positions agrees well with the experimental optical conductivity. Cobalt ion in RNi4Co (R=Ho, Er) is characterized by magnetic moment of 1 μB that increases exchange interaction in the 3d sublattice by several times that contributes to the growth of Curie temperature in comparison with the parent compounds.

  7. Ferroelectricity and competing interactions in Ho-deficient non-stoichiometric orthorhombic HoMnO3

    NASA Astrophysics Data System (ADS)

    Wang, J. X.; Yan, Z. B.; Xie, Y. L.; Zhou, X. H.; Liu, J.-M.

    2015-05-01

    We investigate the consequences of the Ho-deficient non-stoichiometry in orthorhombic HoMnO3 in terms of microscopic mechanisms for ferroelectricity modulation. It is suggested that the Ho-deficiency (then Mn excess) results in Ho-vacancies and then Mn occupation of the Ho-site with increasing non-stoichiometry. The Ho-deficiency enhances the Mn-Mn symmetric exchange striction by suppressing the independent Ho-Ho interaction, and thus benefits to the induced Ho spin ordering against the independent Ho spin ordering. The symmetric Ho-Mn exchange striction is thus enhanced by this induced Ho spin ordering, leading to remarkably enhanced ferroelectric polarization as observed. This work presents an alternative scheme to modulate the multiferroicity in rare-earth manganites of strong 4f-3d coupling.

  8. Ferroelectricity and competing interactions in Ho-deficient non-stoichiometric orthorhombic HoMnO{sub 3}

    SciTech Connect

    Wang, J. X.; Yan, Z. B.; Xie, Y. L.; Zhou, X. H.; Liu, J.-M.

    2015-05-07

    We investigate the consequences of the Ho-deficient non-stoichiometry in orthorhombic HoMnO{sub 3} in terms of microscopic mechanisms for ferroelectricity modulation. It is suggested that the Ho-deficiency (then Mn excess) results in Ho-vacancies and then Mn occupation of the Ho-site with increasing non-stoichiometry. The Ho-deficiency enhances the Mn-Mn symmetric exchange striction by suppressing the independent Ho-Ho interaction, and thus benefits to the induced Ho spin ordering against the independent Ho spin ordering. The symmetric Ho-Mn exchange striction is thus enhanced by this induced Ho spin ordering, leading to remarkably enhanced ferroelectric polarization as observed. This work presents an alternative scheme to modulate the multiferroicity in rare-earth manganites of strong 4f-3d coupling.

  9. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

  10. Increasing Accuracy and Increasing Tension in Ho

    NASA Astrophysics Data System (ADS)

    Freedman, Wendy L.

    2017-01-01

    The Hubble Constant, Ho, provides a measure of the current expansion rate of the universe. In recent decades, there has been a huge increase in the accuracy with which extragalactic distances, and hence Ho, can be measured. While the historical factor-of-two uncertainty in Ho has been resolved, a new discrepancy has arisen between the values of Ho measured in the local universe, and that estimated from cosmic microwave background measurements, assuming a Lambda cold dark matter model. I will review the advances that have led to the increase in accuracy in measurements of Ho, as well as describe exciting future prospects with the James Webb Space Telescope (JWST) and Gaia, which will make it feasible to measure extragalactic distances at percent-level accuracy in the next decade.

  11. Thermochemistry of HO2 + HO2 → H2O4: Does HO2 Dimerization Affect Laboratory Studies?

    PubMed

    Sprague, Matthew K; Irikura, Karl K

    2015-07-09

    Self-reaction is an important sink for the hydroperoxy radical (HO2) in the atmosphere. It has been suggested (Denis, P. A.; Ornellas, F. R. J. Phys. Chem. A, 2009, 113 (2), 499-506) that the minor product hydrogen tetroxide (HO4H) may act as a reservoir of HO2. Here, we compute the thermochemistry of HO2 self-reactions to determine if either HO4H or the cyclic hydrogen-bound dimer (HO2)2 can act as reservoirs. We computed electronic energies using coupled-cluster calculations in the complete basis set limit, CCSD(T)/CBS[45]//CCSD(T)/cc-pVTZ. Our model chemistry includes corrections for vibrational anharmonicity in the zero-point energy and vibrational partition functions, core-valence correlation, scalar relativistic effects, diagonal Born-Oppenheimer, spin-orbit splitting, and higher-order corrections. We compute the Gibbs energy of dimerization to be (-20.1 ± 1.6) kJ/mol at 298.15 K (2σ uncertainty), and (-32.3 ± 1.5) kJ/mol at 220 K. For atmospherically relevant [HO2] = 10(8) molecules per cm(3), our thermochemistry indicates that dimerization will be negligible, and thus H2O4 species are atmospherically unimportant. Under conditions used in laboratory experiments ([HO2] > 10(12) molecules per cm(3), 220 K), H2O4 formation may be significant. We compute two absorption spectra that could be used for laboratory detection of HO4H: the OH stretch overtone (near-IR) and electronic (UV) spectra.

  12. Ho:YLF pumped HBr laser.

    PubMed

    Botha, L R; Bollig, C; Esser, M J D; Campbell, R N; Jacobs, C; Preussler, D R

    2009-10-26

    A Ho:YLF laser pumped HBr molecular laser was developed that produced up to 2.5 mJ of energy in the 4 micron wavelength region. The Ho:YLF laser was fiber pumped using a commercial Tm:fibre laser. The Ho:YLF laser was operated in a single longitudinal mode via injection seeding with a narrow band diode laser which in turn was locked to one of the HBr transitions. The behavior of the HBr laser was described using a rate equation mathematical model and this was solved numerically. Good agreement both qualitatively and quantitatively between the model and experimental results was obtained.

  13. Registration of "HoCP 00-950" Sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 00-950 sugarcane was selected from progeny of the cross HoCP 93-750 x HoCP 92-676 made at Canal Point, Florida. HoCP 00-950 was developed through cooperative research by the Agricultural Research Service of the United States Department of Agriculture, the Louisiana Agricultural Experiment Stati...

  14. AN ELISA ASSAY FOR HEME OXYGENASE (HO-1)

    EPA Science Inventory

    An ELISA assay for heme oxygenase (HO-l )

    Abstract

    A double antibody capture ELISA for the HO-l protein has been developed to separately quantitate HO-I protein. The use of 2.5% NP40 detergent greatly assists in freeing HO-l protein from membranes and/or other cel...

  15. Local Measurement of Tropospheric HO(x)

    NASA Technical Reports Server (NTRS)

    Crosley, David R.

    1994-01-01

    In March of 1992 a workshop sponsored by NASA and NSF was held at SRI International to assess the current ability to measure atmospheric OH and HO2. The measurement techniques reviewed during the workshop for detection of OH included five laser-induced fluorescence schemes, five laser-based adsorption techniques, and four non-laser methods. Six instruments or instrument concepts for HO2 detection, including chemical amplification, conversion to OH with subsequent OH detection, or direct spectroscopic detection of the HO2 were also discussed. The conclusions from the workshop identify several measurement techniques for OH and HO2 that are ready for field tests. These have the ability to measure the radicals with sufficient sensitivity and accuracy to form meaningful comparison with atmospheric model predictions. The workshop conclusions also include recommendations for informal and formal intercomparison protocols.

  16. LiHo(PO3)4

    PubMed Central

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

    2009-01-01

    Lithium holmium(III) polyphosphate(V), LiHo(PO3)4, belongs to the type I of polyphosphates with general formula ALn(PO3)4, where A is a monovalent cation and Ln is a trivalent rare earth cation. In the crystal structure, the polyphosphate chains spread along the b-axis direction, with a repeat period of four tetra­hedra and 21 inter­nal symmetry. The Li and Ho atoms are both located on twofold rotation axes and are surrounded by four and eight O atoms, leading to a distorted tetra­hedral and dodeca­hedral coordination, respectively. The HoO8 polyhedra are isolated from each other, the closest Ho⋯Ho distance being 5.570 (1) Å. PMID:21581738

  17. Ni-Co laterite deposits

    USGS Publications Warehouse

    Marsh, Erin E.; Anderson, Eric D.

    2011-01-01

    Nickel-cobalt (Ni-Co) laterite deposits are an important source of nickel (Ni). Currently, there is a decline in magmatic Ni-bearing sulfide lode deposit resources. New efforts to develop an alternative source of Ni, particularly with improved metallurgy processes, make the Ni-Co laterites an important exploration target in anticipation of the future demand for Ni. This deposit model provides a general description of the geology and mineralogy of Ni-Co laterite deposits, and contains discussion of the influences of climate, geomorphology (relief), drainage, tectonism, structure, and protolith on the development of favorable weathering profiles. This model of Ni-Co laterite deposits represents part of the U.S. Geological Survey Mineral Resources Program's effort to update the existing models to be used for an upcoming national mineral resource assessment.

  18. The Unimolecular Decomposition and H Abstraction Reactions by HO and HO2 from n-Butanol

    NASA Astrophysics Data System (ADS)

    Moc, Jerzy; Black, Gráinne; Simmie, John M.; Curran, Henry J.

    2009-08-01

    By using correlated ab initio (MP2, CCSD(T)) and multi-level (G3, CBS-QB3) methods we have studied unimolecular and bimolecular reactions of n-butanol in the gas phase. The specific processes investigated include H2O elimination and hydrogen abstraction by the hydroxy (HO) and hydroperoxy (HO2) radicals from this alcohol.

  19. HO(x) Measurements in SONEX with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

    NASA Technical Reports Server (NTRS)

    Brune, William M.

    1997-01-01

    SONEX, which was delayed by aircraft inspection problems, began the second week of October and concluded in mid-November with 16 flights. These flights covered the Pacific Ocean off the western United States, transits across the United States, the western coast of Europe, and the North and Central Atlantic Ocean. Particular attention was paid to the North Atlantic Flight Corridor. ATHOS collected high-quality HO(x) data on 15 flights. Observations taken at 5 Hz were typically averaged into 20-second measurements. Each 20-second measurement has precision 1(sigma) of less than 0.01 pptv. OH measurements were generally made from the surface to flight altitudes. HO2 measurements, which require reagent NO flow, were made from flight altitudes to near the top of the planetary boundary layer. Measured OH and HO2 during SONEX was generally lower than the measured OH and HO2 during SUCCESS (April-May, 1996, central United States). Whereas during SUCCESS midday OH was 0.1-0.5 pptv and HO2 was 3-15 pptv, during SONEX midday OH was 0.02-0.2 pptv and HO2 was 0.5-8 pptv. Part of this difference results from the midday solar zenith angles, which were larger during SONEX than during SUCCESS due to both the season and the generally higher latitudes sampled during SONEX. However, some of the difference may be due to differences in HOx sources, since less air influenced by convection was sampled during SONEX. These possibilities await post-flight calibrations of ATHOS and analysis of observations of HO(x) and simultaneously measured meteorology and trace species.

  20. The interplay between magnetism and superconductivity in RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd)

    NASA Astrophysics Data System (ADS)

    El Massalami, M.; Bud'ko, S. L.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    1995-02-01

    The superconducting and magnetic phase diagram (characteristic temperatures versus effective ionic radii) of the RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd) compounds are considered. Although the gradual degradation of superconductivity can be scaled to the de Gennes factor, ( g-1) 2J( J + 1), the unique reentrant behavior of the HoNi 2B 2C compound and the abrupt quenching of superconductivity for R lighter than Ho are most probably unaccountable within this scheme. Rather, it is argued that their low- T magnetic and transport properties as well as the main features of the interplay between magnetism and superconductivity can be accounted for if the low- T magnetism of HoNi 2B 2C, as reported by Grigereit et al., is generalized to the other isomorphous R members. Thus the onset of the 4f moments antiferromagnetic state at T1 is accompanied by an oscillatory component, which transforms to a commensurate antiferromagnetic state at T2. For HoNi 2B 2C, the pressure and magnetic-field influence on Tc, T1 and T2 will be discussed.

  1. High Energy Double-Pulsed Ho:Tm:YLF Laser Amplifier

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Braud, Alain; Petros, Mulugeta; Singh, Upendra N.

    2002-01-01

    A high energy double-pulsed Ho:Tm:YLF 2-micrometer laser amplifier has been demonstrated. 600 mJ per pulse pair under Q-switch operation is achieved with the gain of 4.4. This solid-state laser source can be used as lidar transmitter for multiple lidar applications such as coherent wind and carbon dioxide measurements.

  2. Tracing sources of crustal contamination using multiple S and Fe isotopes in the Hart komatiite-associated Ni-Cu-PGE sulfide deposit, Abitibi greenstone belt, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Hiebert, R. S.; Bekker, A.; Houlé, M. G.; Wing, B. A.; Rouxel, O. J.

    2016-10-01

    Assimilation by mafic to ultramafic magmas of sulfur-bearing country rocks is considered an important contributing factor to reach sulfide saturation and form magmatic Ni-Cu-platinum group element (PGE) sulfide deposits. Sulfur-bearing sedimentary rocks in the Archean are generally characterized by mass-independent fractionation of sulfur isotopes that is a result of atmospheric photochemical reactions, which produces isotopically distinct pools of sulfur. Likewise, low-temperature processing of iron, through biological and abiotic redox cycling, produces a range of Fe isotope values in Archean sedimentary rocks that is distinct from the range of the mantle and magmatic Fe isotope values. Both of these signals can be used to identify potential country rock assimilants and their contribution to magmatic sulfide deposits. We use multiple S and Fe isotopes to characterize the composition of the potential iron and sulfur sources for the sulfide liquids that formed the Hart deposit in the Shaw Dome area within the Abitibi greenstone belt in Ontario (Canada). The Hart deposit is composed of two zones with komatiite-associated Ni-Cu-PGE mineralization; the main zone consists of a massive sulfide deposit at the base of the basal flow in the komatiite sequence, whereas the eastern extension consists of a semi-massive sulfide zone located 12 to 25 m above the base of the second flow in the komatiite sequence. Low δ56Fe values and non-zero δ34S and Δ33S values of the komatiitic rocks and associated mineralization at the Hart deposit is best explained by mixing and isotope exchange with crustal materials, such as exhalite and graphitic argillite, rather than intrinsic fractionation within the komatiite. This approach allows tracing the extent of crustal contamination away from the deposit and the degree of mixing between the sulfide and komatiite melts. The exhalite and graphitic argillite were the dominant contaminants for the main zone of mineralization and the eastern

  3. Investigation of loss processes of Tm and Tm,Ho in YAG

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Bair, C. H.; Inge, A. T.; Hess, R. V.

    1991-01-01

    The loss of excitation from various manifolds of Tm and Tm,Ho in YAG as a function of temperature and concentration is studied. Two probable loss mechanisms - a Tm up-conversion and a Ho up-conversion - are identified. A 785-nm CW diode laser with 400-nW peak power was focused to a small spot on the sample. The emission from the sample observed at 90 deg was monitored through a monochromator with slits open to 3 mm. Intensity of emission was measured by varying the power of the excitation source using a set of neutral density filters. Power is reported as the percentage of the peak power, and the intensity curves were normalized below 20 percent of transmission. The fact that there is emission above the pump energy indicates an up-conversion from excited manifolds. Nonlinear changes in the intensity of the emission from the Tm 3F4 manifold with the pump power reveals a loss of excitation from this manifold. The linear dependence of the 5I7 manifold emission with pump power at low Tm and high Ho concentrations and the gain of energy in the 5I6 manifold of Ho indicate that the 5I7 manifold loss is due to the coupling of Tm and Ho ions.

  4. 75 FR 52534 - Su Van Ho: Debarment Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... Salmonella bacteria, with verification of such exportation or destruction by FDA. Mr. Ho concealed and... with Salmonella bacteria. As a result of his conviction, on June 10, 2010, FDA sent Mr. Ho a notice...

  5. Ho:YAG Single Crystal Fiber: Fabrication and Optical Characterization

    DTIC Science & Technology

    2014-06-16

    optical characterization 0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was fabricated using Laser Heated Pedestal Growth (LHPG) method and...ABSTRACT Ho:YAG single crystal fiber: fabrication and optical characterization Report Title 0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was...0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was fabricated using Laser Heated Pedestal Growth (LHPG) method and characterized for its

  6. Kinetics of the reaction HO2 + NO2 + M yields HO2NO2 + M

    NASA Technical Reports Server (NTRS)

    Sander, S. P.; Peterson, M. E.

    1984-01-01

    The flash photolysis/ultraviolet absorption technique was used to measure the rate constants for the reaction HO2 + NO2 + M yields HO2NO2 + M over the pressure range 50-700 torr and temperature range 229-362 K using He, O2, and N2 as diluent gases. The data were fit to the expression derived by Troe (1979) and co-workers for describing the pressure and temperature dependence of reactions in the falloff region. By combining these data with recent measurements of the rate constant for HO2NO2 thermal decomposition values of 73.8 + or - 2 eu for the standard entropy and -12.6 + or - kcal/mol for the standard enthalpy of formation of HO2NO2 were obtained. A significant enhancement in the rate constant was observed when water vapor was added to the system.

  7. Black strings in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Aliev, Alikram N.; Şentürk, Çetin

    2011-08-01

    We examine a class of cylindrically symmetric solutions in Hořava-Lifshitz gravity. For the relativistic value of the coupling constant, λ=1, we find the hedgehog-type static black string solution with the nonvanishing radial shift in the Arnowitt-Deser-Misner-type decomposition of the spacetime metric. With zero radial shift, this solution corresponds to the usual Banados-Teitelboim-Zanelli (BTZ) black string in general relativity. However, unlike the general relativity case, the BTZ-type black strings do naturally exist in Hořava-Lifshitz gravity, without the need for any specific source term. We also find a rotating BTZ-type black string solution which requires the nonvanishing radial shift for its very existence. We calculate the mass and the angular momentum of this solution, using the canonical Hamiltonian approach. Next, we discuss the Lemos-type black string, which is inherent in general relativity with a negative cosmological constant, and present the static metric for any value of λ>1/3. Finally, we show that while, for λ=1, the entropy of the Lemos-type black string is given by one quarter of the horizon area, the entropy of the static BTZ-type black string is one half of its horizon area.

  8. Correlation of acoustic emission generated during uniform biaxial loading to microstructural sources in 7075-T651 aluminum and 21Cr-6Ni-9Mn stainless steel. Final report

    SciTech Connect

    Leon, E.; Mukherjee, A.K.

    1981-12-01

    This paper reports on the effect on acoustic emission (AE) of uniform biaxial loading of a thin-walled tube designed by Hamstad, Patterson and Mukherjee. The AE generated during biaxial loading of 7075-T651 aluminum and 21Cr-6Ni-9Mn stainless steel had several anomalous features relative to tensile generated AE. The biaxial AE data was of a much higher level and peaked at a lower strain than the uniaxial AE response. A particle cracking model was proposed in which inclusions with the largest projected surface area perpendicular to the principal axis of applied loading will crack before smaller inclusions, and the resulting energy released per AE will be proportional to the crack surface area. The inclusion contents were studied with respect to size, shape, density, hardness, and fracture/decohesion behavior. The inclusions in both 7075-T651 and 21-6-9 display the preferred cracking orientation predicted in the Hamstad, et al. model and are shown to be associated with the generated AE. However, other factors appear to contribute to the total AE responses. There is evidence that for 7075-T651 subjected to biaxial loading, a grain boundary-related mechanism becomes a significant source of AE in the latter stages of strain hardening. Also, for both materials, the complex applied load during biaxial loading appears to amplify the level of AE.

  9. OH and HO2 chemistry in clean marine air during SOAPEX-2

    NASA Astrophysics Data System (ADS)

    Sommariva, R.; Haggerstone, A.-L.; Carpenter, L. J.; Carslaw, N.; Creasey, D. J.; Heard, D. E.; Lee, J. D.; Lewis, A. C.; Pilling, M. J.; Zádor, J.

    2004-01-01

    Model-measurement comparisons of HOx in extremely clean air ([NO]<3 ppt) are reported. Measurements were made during the second Southern Ocean Photochemistry Experiment (SOAPEX-2), held in austral summer 1999 at the Cape Grim Baseline Air Pollution Station in north-western Tasmania, Australia. The free-radical chemistry was studied using a zero-dimensional box-model based upon the Master Chemical Mechanism (MCM). Two versions of the model were used, with different levels of chemical complexity, to explore the role of hydrocarbons upon free-radical budgets under very clean conditions. The "detailed" model was constrained to measurements of CO, CH4 and 15 NMHCs, while the "simple" model contained only the CO and CH4 oxidation mechanisms, together with inorganic chemistry. The OH and HO2 (HOx) concentrations predicted by the two models agreed to within 5-10%. The model results were compared with the HOx concentrations measured by the FAGE (Fluorescence Assay by Gas Expansion) technique during four days of clean Southern Ocean marine boundary layer (MBL) air. The models overestimated OH concentrations by about 10% on two days and about 20% on the other two days. HO2 concentrations were measured during two of these days and the models overestimated the measured concentrations by about 40%. Better agreement with measured HO2 was observed by using data from several MBL aerosol measurements to estimate the aerosol surface area and by increasing the HO2 uptake coefficient to unity. This reduced the modelled HO2 overestimate by ~40%, with little effect on OH, because of the poor HO2 to OH conversion at the low ambient NOx concentrations. Local sensitivity analysis and Morris One-At-A-Time analysis were performed on the "simple" model, and showed the importance of reliable measurements of j(O1D) and [HCHO] and of the kinetic parameters that determine the efficiency of O(1D) to OH and HCHO to HO2 conversion. A 2σ standard deviation of 30-40% for OH and 25-30% for HO2 was

  10. The Secret Lives of Cepheids: The prototype Classical Cepheid δ Cephei is a Pulsed Variable X-ray and FUV Source - Implications for achieving a high precision Hubble Constant (Ho)

    NASA Astrophysics Data System (ADS)

    Guinan, Edward F.; Engle, Scott G.; Neilson, Hilding; Harper, Graham M.; Remage Evans, Nancy

    2016-06-01

    As part of our “Secret Lives of Cepheids” program, we report that the prototype Classical Cepheid - δ Cep is an X-ray source with pulsation-modulated X-ray & FUV emissions. Recent Chandra X-ray observations, when combined with our previous Chandra & XMM-Newton data, confirm a periodic sharp ~ 5 fold increase in X-ray flux at ~ 0.5φ. The X-ray emission phases with the star's pulsation P = 5.366-d, confirms that the X-ray emissions arise from the Cepheid itself and not from a companion. The X-ray variation is “spike-like” with an Lx (max) ~ 2.1 x1029 erg/s, with plasma temperatures of ~ 2 - 6 MK. The HST-COS FUV fluxes increase ~10-20 times and reach maximum strengths during ~0.88-0.97φ - prior to maximum brightness. The FUV emissions arise from ionized plasmas with T ~10 - 300 x103 K. The FUV emission lines show turbulent broadening near the maximum fluxes. The FUV emissions are best explained by pulsation-induced collisional shocks originating from the star’s pulsating atmosphere. However, the X-ray emissions occur 0.5 - 0.6 φ (~3 days) later than the FUV emission line maxima. Thus, it appears that the X-ray emissions arise further out from the star. We suggests that to produce the observed high temperature X-ray emitting plasmas, that the X-rays most likely arise from pulsation-shock induced turbulent-magnetic heated plasmas. If this behavior is extended to other Cepheids, the presence of pulsation induced X-ray and FUV emissions could play major roles in the dynamics and heating of Cepheid atmospheres and could have consequences affecting the Cepheid Period-Luminosity (P-L) law. For example, the additional energy and shock-heating could produce enhanced mass loss leading to the formation of circumstellar shells. For example, the presence of circumstellar matter could bias the P-L relation if not accounted for. Similar X-ray - UV behavior is indicated by at least one other Cepheid, β Doradus.This research is supported from grants from NASA for

  11. Yields of O2(b 1 Sigma g +) from reactions of HO2. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.; Choo, K. Y.; Leu, M. T.

    1985-01-01

    The production of O2(b 1 Sigma g +) has been monitored for several reactions of the HO2 radical at 300 K using a discharge-flow apparatus with resonance fluorescence and chemiluminescence detection. In all cases, the resulting quantum efficiencies were found to be less than 0.03. O2(b) was observed when F atoms were added to H2O2 in the gas phase. The signal strengths of O2(b) were proportional to initial concentrations of HO2 formed by the F + H2O2 reaction. Observed /O2(b)/, /HO2/, and /OH/ vs /F/0 were analyzed using a simple three-step mechanism and a more complete computer simulation with 22 reaction steps. The results indicate that the F + HO2 reaction yields O2(b) with an efficiency of (3.6 + or - 1.4) x 10 to the -3rd. Yields from the O + OH2 reaction were less than 0.02, indicating that this reaction cannot be a major source of the O2(b) emission observed in the earth's nightglow.

  12. Low noise, tunable Ho:fiber soliton oscillator for Ho:YLF amplifier seeding

    NASA Astrophysics Data System (ADS)

    Li, Peng; Ruehl, Axel; Bransley, Colleen; Hartl, Ingmar

    2016-06-01

    We present a passively mode-locked, tunable soliton Ho:fiber ring oscillator, optimized for seeding of holmium-doped yttrium lithium flouride (Ho:YLF) amplifiers. The oscillator is independently tunable in central wavelength and spectral width from 2040 to 2070 nm and from 5 to 10 nm, respectively. At all settings the pulse energy within the soliton is around 800 pJ. The soliton oscillator was optimized to fully meet the spectral requirements for seeding Ho:YLF amplifiers. Its Kelly sidebands are located outside the amplifier gain spectrum, resulting in a train of about 1 ps long pedestal-free pulses with relative intensity noise of only 0.13% RMS when integrated from 1 Hz to Nyquist frequency.

  13. Hydration and mobility of HO-(aq)

    PubMed Central

    Asthagiri, D.; Pratt, Lawrence R.; Kress, J. D.; Gomez, Maria A.

    2004-01-01

    The hydroxide anion plays an essential role in many chemical and biochemical reactions. But a molecular-scale description of its hydration state, and hence also its transport, in water is currently controversial. The statistical mechanical quasichemical theory of solutions suggests that \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{HO}}{\\cdot}[{\\mathrm{H}}_{2}{\\mathrm{O}}]_{3}^{-}\\end{equation*}\\end{document} is the predominant species in the aqueous phase under standard conditions. This result agrees with recent spectroscopic studies on hydroxide water clusters and with the available thermodynamic hydration free energies. In contrast, a recent ab initio molecular dynamics simulation has suggested that \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{HO}}{\\cdot}[{\\mathrm{H}}_{2}{\\mathrm{O}}]_{4}^{-}\\end{equation*}\\end{document} is the only dominant aqueous solution species. We apply adiabatic ab initio molecular dynamics simulations and find good agreement with both the quasichemical theoretical predictions and experimental results. The present results suggest a picture that is simpler, more traditional, but with additional subtlety. These coordination structures are labile but the tricoordinate species is the prominent case. This conclusion is unaltered with changes in the electronic density functional. No evidence is found for rate-determining activated interconversion of a \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength

  14. AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE HO-1 ISOFORM OF HEME OXYGENASE

    EPA Science Inventory

    AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE HO-1 ISOFORM OF HEME OXYGENASE

    Heme oxygenase (HO) occurs in biological tissues as two major isoforms HO-1 and HO-2. HO-1 is inducible by many treatments, particularly oxidative stress-related conditions such as depletion of gl...

  15. High Energy Directly Pumped Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Petros, Mulugeta; Yu, Ji-Rong; Singh, Upendra N.; Barnes, Norman P.

    2000-01-01

    The most commonly used crystal architecture to produce 2 micrometer laser is co-doping Ho and Tm into a single host crystal. In this method, the stored energy transfer from the Tm (3)F4 to the Ho (5)I7 manifold is not fast enough to warrant high efficiency for short pulse applications. By separating the Ho and the Tm ions and doping the Tm in YALO3 and the Ho in YLF, we were able to directly pump the Ho (5)I7 manifold with 1.94 micrometers. The Ho:YLF laser has produced 33 mJ at 2.062 micrometers with a quantum efficiency of 0.88. The performance of each laser will be presented.

  16. Spectroscopic and lasing properties of Ho:Tm:LuAG

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Filer, Elizabeth D.; Naranjo, Felipe L.; Rodriguez, Waldo J.; Kokta, Milan R.

    1993-01-01

    Ho:Tm:LuAG has been grown, examined spectroscopically, and lased at 2.1 microns. Ho:Tm:LuAG was selected for this experimental investigation when quantum-mechanical modeling predicted that it would be a good laser material for Ho laser operation on one of the 5I7 to 5I8 transitions. Lasing was achieved at 2.100 microns, one of the three wavelengths predicted to be most probable for laser action.

  17. Room temperature 2 μm Tm,Ho : YLF laser

    NASA Astrophysics Data System (ADS)

    Baronti, B.; Cornacchia, F.; Di Lieto, A.; Maroni, P.; Toncelli, A.; Tonelli, M.

    2003-03-01

    We present the results obtained with a Tm,Ho : YLF crystal, grown in the new crystals growth facility realized in the Dipartimento di Fisica of the Università di Pisa. The 2 μm laser performance has been studied for three different pump sources, a Ti : Sapphire, a diode—tuned at 792.7 nm—and a Co : MgF 2 laser, tuned at 1.682 μm.

  18. Heterogeneous photochemistry of imidazole-2-carboxaldehyde: HO2 radical formation and aerosol growth

    NASA Astrophysics Data System (ADS)

    González Palacios, Laura; Corral Arroyo, Pablo; Aregahegn, Kifle Z.; Steimer, Sarah S.; Bartels-Rausch, Thorsten; Nozière, Barbara; George, Christian; Ammann, Markus; Volkamer, Rainer

    2016-09-01

    The multiphase chemistry of glyoxal is a source of secondary organic aerosol (SOA), including its light-absorbing product imidazole-2-carboxaldehyde (IC). IC is a photosensitizer that can contribute to additional aerosol ageing and growth when its excited triplet state oxidizes hydrocarbons (reactive uptake) via H-transfer chemistry. We have conducted a series of photochemical coated-wall flow tube (CWFT) experiments using films of IC and citric acid (CA), an organic proxy and H donor in the condensed phase. The formation rate of gas-phase HO2 radicals (PHO2) was measured indirectly by converting gas-phase NO into NO2. We report on experiments that relied on measurements of NO2 formation, NO loss and HONO formation. PHO2 was found to be a linear function of (1) the [IC] × [CA] concentration product and (2) the photon actinic flux. Additionally, (3) a more complex function of relative humidity (25 % < RH < 63 %) and of (4) the O2 / N2 ratio (15 % < O2 / N2 < 56 %) was observed, most likely indicating competing effects of dilution, HO2 mobility and losses in the film. The maximum PHO2 was observed at 25-55 % RH and at ambient O2 / N2. The HO2 radicals form in the condensed phase when excited IC triplet states are reduced by H transfer from a donor, CA in our system, and subsequently react with O2 to regenerate IC, leading to a catalytic cycle. OH does not appear to be formed as a primary product but is produced from the reaction of NO with HO2 in the gas phase. Further, seed aerosols containing IC and ammonium sulfate were exposed to gas-phase limonene and NOx in aerosol flow tube experiments, confirming significant PHO2 from aerosol surfaces. Our results indicate a potentially relevant contribution of triplet state photochemistry for gas-phase HO2 production, aerosol growth and ageing in the atmosphere.

  19. EGR-1 regulates Ho-1 expression induced by cigarette smoke

    SciTech Connect

    Chen, Huaqun; Wang, Lijuan; Gong, Tao; Yu, Yang; Zhu, Chunhua; Li, Fen; Wang, Li; Li, Chaojun

    2010-05-28

    As an anti-oxidant molecule, heme oxygenase-1 (HO-1) has been implicated in the protection of lung injury by cigarette smoke (CS). The mechanisms regulating its expression have not been defined. In this report, the role of early growth response 1 (EGR-1) in the regulation of Ho-1 expression was investigated. In C57BL/6 mice with CS exposure, HO-1 was greatly increased in bronchial epithelial cells and alveolar inflammatory cells. In primary cultured mouse lung fibroblasts and RAW264.7 cells exposed to cigarette smoke water extract (CSE), an increase in HO-1 protein level was detected. In addition, CSE induced HO-1 expression was decreased in Egr-1 deficient mouse embryo fibroblasts (Egr-1{sup -/-} MEFs). Nuclear localization of EGR-1 was examined in mouse lung fibroblasts after exposure to CSE. Luciferase reporter activity assays showed that the enhancer region of the Ho-1 gene containing a proposed EGR-1 binding site was responsible for the induction of HO-1. A higher increase of alveolar mean linear intercept (Lm) was observed in lung tissues, and a larger increase in the number of total cells and monocytes/macrophages from bronchial alveolar lavage fluid was found in CS-exposed mice by loss of function of EGR-1 treatment. In summary, the present data demonstrate that EGR-1 plays a critical role in HO-1 production induced by CS.

  20. Monitoring DNA recombination initiated by HO endonuclease.

    PubMed

    Sugawara, Neal; Haber, James E

    2012-01-01

    DNA double-strand breaks (DSBs) have proven to be very potent initiators of recombination in yeast and other organisms. A single, site-specific DSB initiates homologous DNA repair events such as gene conversion, break-induced replication, and single-strand annealing, as well as nonhomologous end joining, microhomology-mediated end joining, and new telomere addition. When repair is either delayed or prevented, a single DSB can trigger checkpoint-mediated cell cycle arrest. In budding yeast, expressing the HO endonuclease under the control of a galactose-inducible promoter has been instrumental in the study of these processes by providing us a way to synchronously induce a DSB at a unique site in vivo. We describe how the HO endonuclease has been used to study the recombination events in mating-type (MAT) switching. Southern blots provide an overview of the process by allowing one to examine the formation of the DSB, DNA degradation at the break, and formation of the product. Denaturing gels and slot blots as well as PCR have provided important tools to follow the progression of resection in wild-type and mutant cells. PCR has also been important in allowing us to follow the kinetics of certain recombination intermediates such as the initiation of repair DNA synthesis or the removal of nonhomologous Y sequences during MAT switching. Finally chromatin immunoprecipitation has been used to follow the recruitment of key proteins to the DSB and in subsequent steps in DSB repair.

  1. Towards Performance Portability with GungHo

    NASA Astrophysics Data System (ADS)

    Ford, Rupert; Glover, Matthew; Ham, David; Hobson, Mike; Maynard, Chris; Mitchell, Lawrence; Mullerworth, Steve; Pickles, Stephen; Rezny, Mike; Riley, Graham; Wood, Nigel; Ashworth, Mike

    2014-05-01

    The Met Office's numerical weather prediction and climate model code, the Unified Model (UM), is almost 25 years old. Up to the present day the UM has been able to be run efficiently on many of the worlds most powerful computers, helping to keep the Met Office at the forefront of climate prediction and weather forecasting. However, with performance increases from each new generation of computers now being primarily provided by an increase in the amount of parallelism rather than an increase in the clock-speed of the processors themselves, running higher resolutions of the UM now faces the double challenge of code scalability and numerical accuracy. The UM's atmospheric dynamical core makes use of a finite-difference scheme on a regular latitude-longitude grid. The regular latitude-longitude mesh results in an increasingly disparate grid resolution as the mesh resolution increases due to lines of longitude converging at the poles. For example, a 10km resolution at mid-latitudes would result in a 12m resolution at the poles. The difference in resolution leads to increased communication at the poles and load balance issues which are known to impair scalability; it also leads to issues with numerical accuracy and smaller time-steps due to the difference in scale. To address this problem the Met Office, NERC and STFC initiated the GungHo project. The primary aim of this project is to deliver a scalable, numerically accurate dynamical core. This dynamical core is scheduled to become operational around the year 2022. The project is currently investigating the use of quasi-uniform meshes, such as triangular, icosahedral and cubed-sphere meshes, using finite element methods. The associated GungHo software infrastructure is being developed to support multiple meshes and element types thus allowing for future model development. GungHo is also proposing a novel separation of concerns for the software implementation of the dynamical core. This approach distinguishes between

  2. Heterogeneous Reaction of HO2 Radical with Dicarboxylic Acid Particles

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.

    2010-12-01

    HOx(OH+ HO2) radical plays a central role in the tropospheric chemistry. Recently, the heterogeneous loss of HO2 by aerosol particles is a potentially important HOx sink in the troposphere suggested from observation study. However, there have been few studies for loss of HO2 by aerosols. In this study, we measured the HO2 uptake coefficients for four dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and pimelic acid) aerosol particles under ambient conditions (760Torr and 296K) using an aerosol flow tube(AFT) coupled with a chemical conversion /laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(-10^8 molecules/cm^3). In this system, the effect of the self-reaction of HO2 in the gas phase can be neglected. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at 30% and 70% of relative humilities (RH). Determined HO2 uptake coefficients by succinic acid, glutaric acid, adipic acid, and pimelic acid aerosol particles at 30% RH were 0.05 +/- 0.02, 0.07 +/- 0.03, 0.02 +/- 0.01, and 0.06 +/- 0.03, respectively, while the uptake coefficients by those particles at 70% RH were 0.13 +/- 0.05, 0.13 +/- 0.03, 0.06 +/- 0.01, and 0.11 +/- 0.03, respectively. These results suggest that compositions and relative humidity are significant to the HO2 uptake. We will discuss the potential HO2 loss processes.

  3. Effect of thermomechanical pre-treatment on short- and long-term Ni release from biomedical NiTi.

    PubMed

    Freiberg, Katharina E; Bremer-Streck, Sibylle; Kiehntopf, Michael; Rettenmayr, Markus; Undisz, Andreas

    2014-05-01

    The effect of annealing and deformation on short-term (21days) and long-term (8months) Ni release from biomedical NiTi wires is studied. The deformation of annealed NiTi wires causes cracking and flaking of the surface oxide layer. Flaking of oxide particles does not uncover the Ni-rich layer underneath the surface oxide layer, since at sites where flaking occurs, a thin (∼25nm) layer of oxide remains on top of this Ni-rich layer. The number of cracks in the oxide and Ni-rich layer, respectively, increases with deformation, and intercrystalline crack propagation into the Ni-rich layer and the NiTi bulk is observed. In plastically deformed wires, the cracks may remain opened, providing access of immersion liquid to these zones. Characteristics and quantity of short-term Ni release are significantly affected by the pre-deformation, resulting in an up to 2 times higher total Ni release within the first 21days of deformed compared to annealed wires. Pre-deformation does not significantly influence long-term Ni release; all annealed and deformed samples exhibit similar long-term Ni release rates. The source of Ni during short-term release is the Ni contained in the surface zone of the oxide layer. For high pre-deformation, the Ni-rich layer is a second source for Ni. This second source is also the cause for Ni release in long-term immersion experiments.

  4. Does acetone react with HO2 in the upper-troposphere?

    NASA Astrophysics Data System (ADS)

    Dillon, T. J.; Pozzer, A.; Vereecken, L.; Crowley, J. N.; Lelieveld, J.

    2012-02-01

    Recent theoretical calculations showed that reaction with HO2 could be an important sink for acetone (CH3C(O)CH3) and source of acetic acid (CH3C(O)OH) in cold parts of the atmosphere (e.g. the tropopause region). This work details studies of HO2 + CH3C(O)CH3 (CH3)2C(OH)OO (R1) in laboratory-based and theoretical chemistry experiments; the atmospheric significance of Reaction (R1) was assessed in a global 3-D chemical model. Pulsed laser-kinetic experiments were conducted, for the first time, at the low-temperatures representative of the tropopause. Reaction with NO converted HO2 to OH for detection by laser induced fluorescence. Reduced yields of OH at T < 220 K provided indirect evidence for the sequestration of HO2 by CH3C(O)CH3 with a forward rate coefficient greater than 2 × 10-12 cm3 molecule-1 s-1. No evidence for Reaction (R1) was observed at T > 230 K, probably due to rapid thermal dissociation back to HO2 + CH3C(O)CH3. Numerical simulations of the data indicate that these experiments were sensitive to only (R1a) HO2-CH3C(O)CH3 complex formation, the first step in (R1). Rearrangement (R1b) of the complex to form peroxy radicals, and hence the atmospheric significance of (R1) has yet to be rigorously verified by experiment. Results from new quantum chemical calculations indicate that K1 is characterised by large uncertainties of at least an order of magnitude at T < 220 K. The large predicted values from Hermans et al. lie at the top end of the range of values obtained from calculations at different (higher) levels of theory. Atmospheric modelling studies demonstrated that whilst (R1) chemistry may be a significant loss process for CH3C(O)CH3 near the tropopause, it cannot explain observations of CH3C(O)OH throughout the troposphere.

  5. Optical Characterization of the Ho^3+ Complex in HEMA

    NASA Astrophysics Data System (ADS)

    Rodriguez, Manuel, III; Sardar, Dhiraj; Nash, Kelly; Yow, Raylon; Gruber, John

    2007-10-01

    The spectroscopic properties of the Ho^3+ complex embedded in 2-hydroxyethyl methacrylate (HEMA) are investigated. The intensities of the room temperature absorption spectra of the Ho^3+(4f^10) transitions in Ho(NO3)3.5H2O:HEMA have been analyzed using the Judd-Ofelt (J-O) model to obtain the phenomenological intensity parameters, φ2, φ4, and φ6. These parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Ho^3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds of ^2S+1LJ Ho^3+(4f^10), which include ^5G4+^3K7^(2), ^5G5, ^5G6+^5F1, ^5F2+^3K8^(2), ^5F3, ^5F4+^5S2, and ^5F5. The predicted room temperature fluorescence lifetime of ^5I7 to ^5I8 is about 0.5 ms, suggesting a reasonably strong interaction between the complex and the polymer. A comparative study of Ho^3+(4f^10) ions in different host materials suggests that Ho(NO3)3.5H2O:HEMA could be an excellent candidate for certain applications such as narrow band pass filters, especially in the visible-to-near infrared region of the spectrum.

  6. Laser flash photolysis studies of radical-radical reaction kinetics: The HO{sub 2} + IO reaction

    SciTech Connect

    Cronkhite, J.M.; Stickel, R.E.; Nicovich, J.M.; Wine, P.H.

    1999-04-29

    Reactive iodine as a potential tropospheric O{sub 3} sink has received considerable attention recently. Laser flash photolysis of Cl{sub 2}/CH{sub 3}OH/O{sub 2}/I{sub 2}/NO{sub 2}/SF{sub 6}N{sub 2} mixtures at 308 nm has been coupled with simultaneous time-resolved detection of HO{sub 2} (by infrared tunable diode laser absorption spectroscopy) and IO (by visible absorption spectroscopy) to investigate the kinetics of the atmospherically important reaction HO{sub 2} + IO {r_arrow} products over the temperature range 274--373 K in N{sub 2} buffer gas at pressures of 12 and 25 Torr. All experiments were performed under near pseudo-first-order conditions with HO{sub 2} in excess over IO. At 298 K, the rate coefficient was determined to be (9.7 {+-} 2.9) {times} 10{sup {minus}11} cm{sup 3} molecule{sup {minus}1}s{sup {minus}1}, with the primary source of uncertainty being knowledge of the infrared line strength(s) required to convert measured HO{sub 2} absorbances to absolute concentrations. The temperature dependence of the HO{sub 2} + IO rate coefficient was found to be adequately described by the Arrhenius expression k = 9.3 {times} 10{sup {minus}12} exp(680/T) cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. The results reported in this study are compared with other recent studies of HO{sub 2} + IO kinetics, and the potential roles of this reaction in atmospheric chemistry are discussed.

  7. Adaptation of an In Situ Ground-Based Tropospheric OH/HO2 Instrument for Aircraft Use

    NASA Technical Reports Server (NTRS)

    Brune, William H.

    1997-01-01

    In-situ HO(x) (OH and HO2) measurements are an essential part of understanding the photochemistry of aircraft exhaust in the atmosphere. HO(x) affects the partitioning of nitrogen species in the NO(y) family. Its reactions are important sources and sinks for tropospheric ozone, thus providing a link between the NO(x) in aircraft exhaust and tropospheric ozone. OH mixing ratios are enhanced in aircraft wakes due to the photolysis of the HONO that is made close to the engine. Measurements of HO(x) in aircraft wakes, along with NO(x) measurements, thus provides a constraint on chemical models of the engine combustion and exhaust. The development of the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) is reported. We designed, developed, and successfully flew this instrument. It was part of the instrument complement on board the NASA DC-8 during SUCCESS, which took place in Kansas in April and May, 1996. ATHOS has a limit-of-detection for OH (S/N = 2) of 10(exp 5) OH molecules cm(exp -3) in less than 150 seconds. While this sensitivity is about 2-3 times less than the initial projections in the proposal, it is more than adequate for good measurements of OH and HO2 from the planetary boundary layer to the stratosphere. Our participation in SUCCESS was to be engineering test flights for ATHOS; however, the high-quality measurements we obtained are being used to study HO(x) photochemistry in contrails, clouds, and the clear air.

  8. HoBi-like viruses: an emerging group of pestiviruses.

    PubMed

    Bauermann, Fernando V; Ridpath, Julia F; Weiblen, Rudi; Flores, Eduardo F

    2013-01-01

    The genus Pestivirus is composed of 4 important pathogens of livestock: Bovine viral diarrhea virus 1 and 2 (BVDV-1 and BVDV-2), Classical swine fever virus (CSFV), and Border disease virus of sheep (BDV). BVDV are major pathogens of cattle, and infection results in significant economic loss worldwide. A new putative pestivirus species, tentatively called "HoBi-like," "BVDV-3," or "atypical pestiviruses," was first identified in Europe in fetal bovine serum (FBS) imported from Brazil. HoBi-like viruses are related to BVDV at the genetic and antigenic levels. Further, the disease caused by these new viruses resembles clinical presentations historically associated with BVDV infection, including growth retardation, reduced milk production, respiratory disease, reduced reproductive performance, and increased mortality among young stock. Current BVDV diagnostic tests may fail to detect HoBi-like viruses or to differentiate between BVDV and HoBi-like viruses. Further, commercial tests for BVDV exposure, based on serological response, do not reliably detect HoBi-like virus exposure, and cross protection against HoBi-like viruses conferred by current BVDV vaccines is likely limited. As many HoBi-like viruses, characterized to date, were isolated from FBS originating from Brazil, it is assumed that the agent is probably widespread in Brazilian herds. Nevertheless, reports of natural infection in Southeast Asia and Europe demonstrate that these viruses are not restricted to South America. Increased demand for FBS has led to widespread distribution of FBS originating in HoBi-like virus endemic regions. The contamination of such FBS with HoBi-like viruses may lead to spread of this virus to other regions.

  9. White up-conversion emission in Ho3+/Tm3+/Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Li, Chenxia; Xu, Shiqing; Ye, Rengguang; Deng, Degang; Hua, Youjie; Zhao, Shilong; Zhuang, Songlin

    2011-04-01

    Ho3+/Tm3+/Yb3+ tri-doped glass ceramics with white light emitting have been developed and demonstrated. Pumped by 980 nm laser diode (LD), intensive red, green and blue up-conversions (UC) were obtained. The green emission is assigned to Ho3+ ion and the blue emission is assigned to Tm3+ ion, whereas the red emission is the combination contribution of the Ho3+ and Tm3+ ions. The RGB intensities could be adjusted by tuning the rare-earth ion concentration and pump power intensity. Thus, multicolor of the luminescence, including perfect white light with CIE-X=0.329 and CIE-Y=0.342 in the 1931 CIE chromaticity diagram can be obtained in 0.15 Ho3+/0.2Tm3+/3Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals pumped by a single infrared laser diode source of 980 nm at 500 mW. The up-conversion luminescence mechanism of Yb3+ sensitize Ho3+ and Tm3+ ions and the energy transfer from Ho3+ to Tm3+ in oxy-fluoride silicate glass ceramics were analyzed.

  10. Review of Tm and Ho Materials; Spectroscopy and Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2008-01-01

    A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2- m lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.

  11. Magnetic properties of epitaxial hexagonal HoFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Xiao, Zhuyun; Xu, Xiaoshan; Wang, Wenbin; Keavney, David; Liu, Yaohua; Cheng, X. M.

    2014-03-01

    Multiferroic materials exhibit multiple ferroic orders simultaneously and thus have great potential applications in information technology, sensing and actuation. Epitaxial hexagonal HoFeO3 (h-HFO) films are very promising candidates as multiferroic materials with room temperature ferromagnetism, because magnetic Ho3+ ions are expected to have stronger exchange interactions with Fe3+ ions than the well-studied h-LuFeO3 films. We report study of magnetic properties of epitaxial h-HFO thin films deposited using laser molecular beam epitaxy on Yttria-stabilized zirconia (YSZ) substrates. X-ray diffraction measurements confirmed the epitaxial registry and six-fold symmetry of the film. Temperature dependence of magnetization of the film measured by a Quantum Design SQUID magnetometer shows dominating paramagnetic characteristic. Element specific x-ray magnetic circular dichroism measurements performed at beamline 4-ID-C of the Advanced Photon Source show a ferromagnetic ordering of Fe and an exchange coupling between Ho3+ and Fe3+ ions. Work at BMC is supported by NSF Career award (DMR 1053854). Work at ANL is supported by US-DOE, Office of Science, BES (No. DE-AC02-06CH11357).

  12. Measurements of OH and HO2 yields from the gas phase ozonolysis of isoprene

    NASA Astrophysics Data System (ADS)

    Malkin, T. L.; Goddard, A.; Heard, D. E.; Seakins, P. W.

    2010-02-01

    The reactions of ozone with alkenes are an important source of hydroxyl (OH) radicals; however, quantification of their importance is hindered by uncertainties in the absolute OH yield. Hydroxyl radical yields for the gas-phase ozonolysis of isoprene are determined in this paper by four different methods: (1) The use of cyclohexane as an OH scavenger, and the production of cyclohexanone, (2) The use of 1,3,5-trimethylbenzene as an OH tracer, and the diminution in its concentration, (3) A kinetic method in which the OH yield was obtained by performing a series of pseudo-first-order experiments in the presence or absence of an OH scavenger (cyclohexane), (4) The OH and HO2 yields were determined by fitting the temporal OH and HO2 profiles following direct detection of absolute OH and HO2 concentrations by laser induced fluorescence at low pressure (Fluorescence Assay by Gas Expansion- FAGE). The following OH yields for the ozonolysis of isoprene were obtained, relative to alkene consumed, for each method: (1) Scavenger (0.25±0.04), (2) Tracer (0.25±0.03), (3) Kinetic study (0.27±0.02), and (4) Direct observation (0.26±0.02), the error being one standard deviation. An averaged OH yield of 0.26±0.02 is recommended at room temperature and atmospheric pressure and this result is compared with recent literature determinations. The HO2 yield was directly determined for the first time using FAGE to be 0.26±0.03.

  13. Road to Victory: Building the Ho Chi Minh Trail.

    ERIC Educational Resources Information Center

    Kenney, Marianne

    1993-01-01

    Presents a secondary school lesson on the building of the Ho Chi Minh Trail during the Vietnam War. Helps students link history and geographical skills through cooperative group learning. Includes maps, diagrams, and three student readings. (CFR)

  14. Kinetics and mechanism of HO2 and DO2 disproportionations

    NASA Technical Reports Server (NTRS)

    Kircher, C. C.; Sander, S. P.

    1984-01-01

    A flash photolysis/UV abosrption technique was used to study the HO2 + HO2 and DO2 + DO2 reactions in the gas phase. Rate constants were measured at pressures between 100 and 700 torr of Ar and N2, and at temperatures between 230 and 420 K with up to 10 torr of added water vapor. The overall disproportionation rate constants for the reaction is given as the sum of pressure-independent and pressure-dependent terms. A kinetic analysis shows that both reactions have a zero-pressure bimolecular component and a termolecular component which is linearly dependent on pressure up to 700 torr. A priori estimates of the vibrational frequencies of the product of the HO2 + HO2 reaction suggest binding energies of 12-20 kcal per mol (for the initial association).

  15. High-spin yrast structure of {sup 159}Ho

    SciTech Connect

    Ollier, J.; Simpson, J.; Riley, M. A.; Wang, X.; Aguilar, A.; Teal, C.; Paul, E. S.; Nolan, P. J.; Petri, M.; Rigby, S. V.; Thomson, J.; Unsworth, C.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Zhu, S.; Darby, I. G.; Hartley, D. J.; Kondev, F. G.

    2011-08-15

    An investigation of the yrast structure of the odd-Z {sup 159}Ho nucleus to high spin has been performed. The {sup 159}Ho nucleus was populated by the reaction {sup 116}Cd({sup 48}Ca,p4n{gamma}) at a beam energy of 215 MeV, and resulting {gamma} decays were detected by the Gammasphere spectrometer. The h{sub 11/2} yrast band has been significantly extended up to I{sup {pi}=}75/2{sup -} (tentatively 79/2{sup -}). A lower frequency limit for the second (h{sub 11/2}){sup 2} proton alignment was extracted consistent with the systematics of this alignment frequency, indicating an increased deformation with neutron number in the Ho isotopes. The energy-level splitting between the signature partners in the h{sub 11/2} structures of the Ho isotopes and the neighboring N=92 isotones is discussed.

  16. HoCaMA: Home Care Hybrid Multiagent Architecture

    NASA Astrophysics Data System (ADS)

    Fraile, Juan A.; Bajo, Javier; Abraham, Ajith; Corchado, Juan M.

    Home Care is one of the main objectives of Ambient Intelligence. Nowadays, the disabled and elderly population, which represents a significant part of our society, requires novel solutions for providing home care in an effective way. In this chapter, we present HoCaMA, a hybrid multiagent architecture that facilitates remote monitoring and care services for disabled patients at their homes. HoCaMA combines multiagent systems and Web services to facilitate the communication and integration with multiple health care systems. In addition, HoCaMA focuses on the design of reactive agents capable of interacting with different sensors present in the environment, and incorporates a system of alerts through SMS and MMS mobile technologies. Finally, it uses Radio Frequency IDentification and JavaCard technologies to provide advanced location and identification systems, as well as automatic access control facilities. HoCaMA has been implemented in a real environment and the results obtained are presented within this chapter.

  17. Uptake of HO2 Radicals Onto Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, P. S.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2013-12-01

    OH and HO2 radicals play an important role in the troposphere by controlling its oxidative capacity and therefore the concentration of many trace species. Several field studies have observed significantly lower concentrations of HO2 radicals than predicted using box models (1,2). HO2 loss onto aerosols has been suggested as a possible sink. Mineral dust has an estimated annual flux of 2000 Tg year-1 (3). However, there has only been one study of HO2 uptake onto Arizona Test Dust (ATD) surfaces (4) and there are currently no published studies for dust aerosols. Therefore, the aim of this study was to measure the HO2 uptake coefficient onto ATD aerosols over a range of humidities and for different HO2 concentrations, as well as investigating the uptake as a function of the exposure time to the aerosol, for which a dependence had been observed for aqueous salt aerosols (5). Uptake coefficients were measured for ATD aerosols at atmospheric pressure and at 291 K using a Fluorescence Assay by Gas Expansion (FAGE) detector combined with a flow tube. HO2 was formed from the photolysis of water vapour and was injected into the flow tube using a moveable injector, which was placed in six different positions along the flow tube. The non stable aerosol output was produced by stirring ATD in a bottle producing a dust cloud which was entrained into a flow. The aerosol number concentration was measured using a Condensation Particle Counter (CPC) and was converted into a surface area using the average radius of one aerosol. The uptake coefficient was then able to be calculated by assuming first order kinetics. The HO2 uptake coefficient was measured at a relative humidity of between 6 and 75% and at initial HO2 concentrations of ~ 0.3 - 1 × 10^9 molecule cm-3. Average uptake coefficients of 0.018 × 0.006 and 0.031 × 0.008 were measured for the higher and lower HO2 concentrations respectively, and the impact investigated using a constrained box model. A time dependence was also

  18. Registration of 'HoCP 91-552' sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 91-552’ sugarcane was selected from progeny of the cross ‘LCP 81-10’ x ‘CP 72-356’ made at Canal Point, Florida. HoCP 91-552 was developed through cooperative research by the Agricultural Research Service of the United States Department of Agriculture’s Sugarcane Research Unit, the Louisiana A...

  19. Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. II. Spectra of Ho II and Ho III

    NASA Astrophysics Data System (ADS)

    Başar, Gö.; Al-Labady, N.; Özdalgiç, B.; Güzelçimen, F.; Er, A.; Öztürk, I. K.; Ak, T.; Bİlİr, S.; Tamanis, M.; Ferber, R.; Kröger, S.

    2017-02-01

    Fourier Transform spectra of holmium (Ho) in the UV spectral range from 31,530 to 25,000 cm‑1 (317 to 400 nm) have been investigated, particularly focusing on the ionic lines. The distinction between the different degrees of ionization (I, II, and III) is based on differences in signal-to-noise ratios from two Ho spectra, which have been measured with different buffer gases, i.e., neon and argon. Based on 106 known Ho ii and 126 known Ho iii energy levels, 97 lines could be classified as transitions of singly ionized Ho and 9 lines could be classified as transitions of doubly ionized Ho. Of the 97 Ho ii lines, 6 have not been listed in the extant literature. Another 215 lines have been assigned to Ho ii, though they could not be classified on the basis of the known energy levels.

  20. The role of neutrophils in corneal wound healing in HO-2 null mice.

    PubMed

    Marrazzo, Giuseppina; Bellner, Lars; Halilovic, Adna; Li Volti, Giovanni; Drago, Filippo; Dunn, Michael W; Schwartzman, Michal Laniado

    2011-01-01

    Our studies demonstrated that Heme oxygenase (HO), in particular, the constitutive HO-2, is critical for a self-resolving inflammatory and repair response in the cornea. Epithelial injury in HO-2 null mice leads to impaired wound closure and chronic inflammation in the cornea. This study was undertaken to examine the possible relationship between HO-2 and the recruitment of neutrophils following a corneal surface injury in wild type (WT) and HO-2 knockout (HO-2(-/-)) mice treated with Gr-1 monoclonal antibody to deplete peripheral neutrophils. Epithelial injury was performed by removing the entire corneal epithelium. Infiltration of inflammatory cell into the cornea in response to injury was higher in HO-2(-/-) than in WT. However, the rate of corneal wound closure following neutrophil depletion was markedly inhibited in both WT and HO-2(-/-) mice by 60% and 85%, respectively. Neutropenia induced HO-1 expression in WT but not in HO-2(-/-) mice. Moreover, endothelial cells lacking HO-2 expressed higher levels of the Midkine and VE-cadherin and displayed strong adhesion to neutrophils suggesting that perturbation in endothelial cell function caused by HO-2 depletion underlies the increased infiltration of neutrophils into the HO-2(-/-) cornea. Moreover, the fact that neutropenia worsened epithelial healing of the injured cornea in both WT and HO-2(-/-) mice suggest that cells other than neutrophils contribute to the exaggerated inflammation and impaired wound healing seen in the HO-2 null cornea.

  1. Kinetics and product yields of the acetyl peroxy + HO2 radical reaction studied by photoionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dodson, L. G.; Shen, L.; Savee, J. D.; Eddingsaas, N. C.; Welz, O.; Taatjes, C. A.; Osborn, D. L.; Sander, S. P.; Okumura, M.

    2013-12-01

    The acetyl peroxy radical (CH3C(O)O2) is a key intermediate in the oxidation of carbonyl-containing hydrocarbons in the troposphere. Reaction of acetyl peroxy radicals with HO2 has been suggested as a source of OH radicals in low-NOx environments. Previous work on this reaction observed only two product channels forming (1) peracetic acid and (2) acetic acid. Recent experiments have shown that there is a third channel that generates the radicals OH and acetoxy: CH3C(O)O2 + HO2 → (1) CH3C(O)OOH + O2 (2) CH3C(O)OH + O3 (3) CH3C(O)O + O2 + OH This last pathway to OH formation would then contribute to the apparent isoprene OH recycling suggested by discrepancies between atmospheric models and field observations of OH. There have, however, been significant disagreements among experiments on the yield of OH from reaction of acetyl peroxy radicals with HO2. We report our preliminary studies of acetyl peroxy self-reaction and its reaction with HO2 at 298 K and 8 Torr. Experiments were conducted at the Advanced Light Source synchrotron at the Lawerence Berkeley National Laboratory using tunable VUV ionizing radiation coupled to the Sandia National Laboratory pulsed-laser-photolysis multiplexed photoionization mass spectrometer to detect the time- and isomer-resolved formation of radical intermediates and products. From these results, we report new branching fractions of the three product channels in the acetyl peroxy + HO2 radical reaction.

  2. Ternary system Er-Ni-In at T=870 K

    SciTech Connect

    Dzevenko, M.; Tyvanchuk, Yu.; Bratash, L.; Zaremba, V.; Havela, L.; Kalychak, Ya.

    2011-10-15

    Isothermal section of the Er-Ni-In system at T=870 K was constructed by means of X-ray powder diffraction and EDX-analyses. Nine ternary compounds, namely ErNi{sub 9}In{sub 2} (YNi{sub 9}In{sub 2}-type), Er{sub 1-1.22}Ni{sub 4}In{sub 1-0.78} (MgCu{sub 4}Sn-type), Er{sub 10}Ni{sub 9.07}In{sub 20} (Ho{sub 10}Ni{sub 9}In{sub 20}-type), ErNi{sub 1-0.60}In{sub 1-1.40} (ZrNiAl-type), Er{sub 2}Ni{sub 2}In (Mn{sub 2}AlB{sub 2}-type), Er{sub 2}Ni{sub 1.78}In (Mo{sub 2}FeB{sub 2}-type), Er{sub 5}Ni{sub 2}In{sub 4} (Lu{sub 5}Ni{sub 2}In{sub 4}-type), Er{sub 5}Ni{sub 2}In (Mo{sub 5}SiB{sub 2}-type), and Er{sub 13.53}Ni{sub 3.14}In{sub 3.33} (Lu{sub 14}Co{sub 2}In{sub 3}-type), exist in the Er-Ni-In system at this temperature. The substitution of Ni for In was observed for ErNi{sub 1-0.60}In{sub 1-1.40} and In for Er in the case of related compounds ErNi{sub 2} and ErNi{sub 4}In. Er can enter NiIn (CoSn-type) leading to including-substitution type of compound Er{sub 0-0.12}NiIn{sub 1-0.89}. Basic magnetic properties of the Er{sub 0.04}NiIn{sub 0.97}, ErNi{sub 2}, Er{sub 0.9}Ni{sub 2}In{sub 0.1}, and ErNi{sub 4}In phases were inspected. Electrical-resistivity studies were performed on the ErNiIn, ErNi{sub 0.9}In{sub 1.1}, and ErNi{sub 4}In phases. - Graphical Abstract: Phase relations in the ternary system Er-Ni-In have been established for the isothermal section at T=870 K based on X-ray phase and EDX-analyses. Nine ternary compounds were observed. Highlights: > Isothermal section of Er-Ni-In system at T=870 K was constructed. > Nine ternary compounds were detected. > Basic magnetic properties of Er{sub 0.04}NiIn{sub 0.97} and ErNi{sub 4}In phases were inspected.

  3. Reaction of HO2 with O3 and the effect of water vapor on HO2 kinetics

    NASA Technical Reports Server (NTRS)

    Demore, W. B.

    1979-01-01

    The effects of temperature and water vapor concentration on the ratio of the rate constant of the reaction HO2 + O3 yields OH + 2(O2) to the square root of the rate constant for the reaction HO2 + HO2 yields H2O2 + O2 are determined. Photolysis of H2-O2-O3 mixtures at 253.7 nm was carried out with H2O pressures in the range 0 to 15 torr at a temperature range of -42.5 to 61 C along with 184.9 nm photolysis of H2O-O2-O3 mixtures. It is shown that the rate of O3 photolysis is suppressed by the addition of water vapor and it is suggested that this effect is realized in the HO2 + HO2 yields H2O2 + O2 reaction. The calculated expression for the temperature dependence of the rate constant ratio is found to be in good agreement with that calculated from separate rate constants. Rate constants determined for the reaction OH + HO2 yields H2O + O2 are found to be higher than those previously determined, presumably due to increased pressure, indicating that atmospheric models should take into account the possible pressure dependences of the reactions considered.

  4. Is the 'Bromine Explosion' generated from the reaction BrO HO2 alone?

    NASA Astrophysics Data System (ADS)

    Behnke, Wolfgang; Zetzsch, Cornelius

    2010-05-01

    We observed bromine explosions (a fast production of atomic Br and Cl under tropospheric conditions) in various smog chamber experiments in Teflon bags at room temperature at a relative humidity of about 80% in the presence of NaCl/NaBr-aerosol, simulated sunlight and ozone (200 - 400 ppb). Time profiles of ozone and hydrocarbons (HCs: n-butane, 2,2-dimethylbutane, tetramethylbutane and toluene, initially about 2 ppb each) were monitored to determine concentrations and source strengths of OH radicals, atomic Cl and Br and the corresponding time profiles of BrCl and Br2 as their photolytic precursors. The number and size of aerosols are measured as well as their chemical composition (Br-, Cl- and oxalic acid). Full records of raw data from the smog chamber runs are available at www.eurochamp.org for potential users. Chemical box model calculations deliver concentrations of various intermediates, such as aldehydes, HO2 and RO2 radicals and the inorganic halogen compounds ClO, BrO, HOCl and HOBr, where HOBr from O3 + Br- => BrO- + O2 in the aqueous/adsorbed phase induces the following gas-phase/ heterogeneous chain reaction Br + O3 => BrO + O2(1) BrO + HO2 => HOBr + O2(2a) HOBr + (Aerosol) => HOBrad(3) Surface-adsorbed HOBr reacts with Br- or Cl- to produce Br2 or BrCl, both of which are released and photolysed. Formation of Br2 should prevail up to Cl-/Br- -ratios of about 104 (Fickert, S., J.W. Adams, J.N. Crowley, J. Geophys. Res., D104, 23719-23727, 1999). A maximum of this ratio is reached about 30 minutes after the beginning and decreases during the next hours - probably by reaction of Br2 with oxalate and absorption of HBr, formed from the reaction of Br with aldehydes. Parallel to chain reaction (1)-(3) a chain reaction replacing Br by Cl seems possible but can not be realized, since the main sink of atomic Cl is its reaction with hydrocarbons - leading to chain termination - in contrast to atomic Br (ratio of rates: kCl[O3]/kCl[HC] ~ 0.1; kBr[O3]/k

  5. Heterogeneous Uptake of HO2 Radicals onto Submicron Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, P. S.; George, I. J.; Brooks, B.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2012-12-01

    OH and HO2 (HOx) radicals are closely coupled and OH is responsible for the majority of the oxidation in the troposphere and controls the concentrations of many trace species. Therefore, it is important to be able to accurately predict HOx concentrations. However, some field measurement studies have reported significantly lower HO2 radical concentrations than calculated by constrained box models using detailed chemical mechanisms. Although the inclusion of halogen chemistry into the mechanisms can explain much of the differences in the marine boundary layer (MBL) (1,2), HO2 uptake by aerosols has been suggested as a possible sink in the MBL (2), the Arctic troposphere (3) and the upper troposphere (4). There have been very few laboratory studies (5,6) on HO2 uptake by aerosols and the rates and mechanism is still uncertain. The HO2 uptake coefficients were measured for a variety of atmospherically relevant inorganic and organic aerosols. The measurements were performed using an aerosol flow tube combined with a Fluorescence Assay by Gas Expansion (FAGE) detector. The sensitive FAGE cell allowed low HO2 concentrations (108-109 molecule cm-3) to be injected into the flow tube using a moveable injector. By moving the injector along the flow tube, position dependent HO2 decays were able to be recorded which when plotted against the total aerosol surface area allowed an uptake coefficient to be obtained. The aerosols were generated using an atomiser or by homogeneous nucleation and the total aerosol surface area was measured using a Scanning Mobility Particle Sizer. The HO2 uptake coefficient (γ) was measured at room temperature for dry inorganic salts and dry organics (γ< 0.004), wet inorganic salts and wet organics (γ= 0.002-0.005), wet copper doped ammonium sulfate aerosols (γ= 0.28± 0.05) and ammonium sulfate aerosols doped with different molar amounts of iron (γ= 0.003-0.06). The pH dependence of the HO2 uptake coefficient was investigated, however no

  6. Comparisons of observed and modeled OH and HO2 concentrations during the ambient measurement period of the HOxComp field campaign

    NASA Astrophysics Data System (ADS)

    Kanaya, Y.; Hofzumahaus, A.; Dorn, H.-P.; Brauers, T.; Fuchs, H.; Holland, F.; Rohrer, F.; Bohn, B.; Tillmann, R.; Wegener, R.; Wahner, A.; Kajii, Y.; Miyamoto, K.; Nishida, S.; Watanabe, K.; Yoshino, A.; Kubistin, D.; Martinez, M.; Rudolf, M.; Harder, H.; Berresheim, H.; Elste, T.; Plass-Dülmer, C.; Stange, G.; Kleffmann, J.; Elshorbany, Y.; Schurath, U.

    2012-03-01

    A photochemical box model constrained by ancillary observations was used to simulate OH and HO2 concentrations for three days of ambient observations during the HOxComp field campaign held in Jülich, Germany in July 2005. Daytime OH levels observed by four instruments were fairly well reproduced to within 33% by a base model run (Regional Atmospheric Chemistry Mechanism with updated isoprene chemistry adapted from Master Chemical Mechanism ver. 3.1) with high R2 values (0.72-0.97) over a range of isoprene (0.3-2 ppb) and NO (0.1-10 ppb) mixing ratios. Daytime HO2(*) levels, reconstructed from the base model results taking into account the sensitivity toward speciated RO2 (organic peroxy) radicals, as recently reported from one of the participating instruments in the HO2 measurement mode, were 93% higher than the observations made by the single instrument. This also indicates an overprediction of the HO2 to OH recycling. Together with the good model-measurement agreement for OH, it implies a missing OH source in the model. Modeled OH and HO2(*) could only be matched to the observations by addition of a strong unknown loss process for HO2(*) that recycles OH at a high yield. Adding to the base model, instead, the recently proposed isomerization mechanism of isoprene peroxy radicals (Peeters and Müller, 2010) increased OH and HO2(*) by 28% and 13% on average. Although these were still only 4% higher than the OH observations made by one of the instruments, larger overestimations (42-70%) occurred with respect to the OH observations made by the other three instruments. The overestimation in OH could be diminished only when reactive alkanes (HC8) were solely introduced to the model to explain the missing fraction of observed OH reactivity. Moreover, the overprediction of HO2(*) became even larger than in the base case. These analyses imply that the rates of the isomerization are not readily supported by the ensemble of radical observations. One of the measurement days

  7. Theoretical characterization of the potential energy surface for H + O2 yields HO2(asterisk) yields HO + O. II - The potential for H atom exchange in HO2

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Rohlfing, Celeste Mcmichael

    1989-01-01

    The results of CASSCF multireference contracted CI calculations with large ANO basis sets are presented for the exchange region of the HO2 potential-energy surface. The saddle point for H atom exchange is about 13 kcal/mol below the energy of H + O2; therefore, this region of the surface should be accessible during H + O2 recombination and methathesis reactions.

  8. Does acetone react with HO2 in the upper-troposphere?

    NASA Astrophysics Data System (ADS)

    Dillon, T. J.; Pozzer, A.; Crowley, J. N.; Lelieveld, J.

    2010-07-01

    Recent theoretical calculations showed that reaction of HO2 with acetone (CH3C(O)CH3) could be a potentially important sink for acetone and source for acetic acid in cold parts of the atmosphere (e.g. the tropopause region). The reaction HO2+CH3C(O)CH3⇌(CH3)2C(OH)OO (R1, R-1) was therefore studied experimentally at low-temperatures for the first time. HO2 was generated by pulsed laser photolysis, and converted by reaction with NO to OH for detection by laser induced fluorescence. Reduced yields of OH at T<220 K provided evidence for stabilisation of (CH3)2C(OH)OO at such temperatures. In contrast, no evidence for (R1) was observed at T>230 K, probably due to rapid thermal dissociation of the peroxy radical product back to reactants (R-1). The experimental data indicate that the rate coefficient for the forward reaction, k1(207 K), is larger than 1.6×10-12 cm3 molecule-1 s-1, in line with recent quantum mechanical calculations. In contrast, an upper limit for the equilibrium constant K1(T)=k1(T)/k-1(T) of 7.8×1028exp(50.6 kJ mol-1/RT) was obtained, considerably smaller than calculated from theory. Incorporation of these results into a global 3-D chemical model demonstrated that (R1) is neither a significant loss process for CH3C(O)CH3 nor a significant source of acetic acid in the atmosphere.

  9. Quantum yields of OH, HO2 and NO3 in the UV photolysis of HO2NO2.

    PubMed

    Jiménez, Elena; Gierczak, Tomasz; Stark, Harald; Burkholder, James B; Ravishankara, A R

    2005-01-21

    Quantum yields, phi, of OH and HO2 in the ultraviolet photolysis of HO2NO2 (peroxynitric acid, PNA) at 193 and 248 nm and that of NO3 at 193, 248 and 308 nm are reported. Quantum yields were measured using pulsed excimer laser photolysis combined with pulsed laser induced fluorescence (PLIF) detection of OH radicals and cavity ring-down (CRD) detection of NO3 radicals. HO2 radicals were quantified by converting them to OH via the HO2 + NO --> OH + NO2 reaction and detecting OH. The quantum yields obtained at 296 K are: phi193 nm(OH) = 0.21 +/- 0.12, phi248 nm(OH) = 0.085 +/- 0.08, phi193 nm(HO2) = 0.56 +/- 0.09, phi248 nm(HO2) = 0.89 +/- 0.26, phi193 nm(NO3) = 0.35 +/- 0.09, phi248 nm(NO3) = 0.08 +/- 0.04 and phi308 nm(NO3) = 0.05 +/- 0.02. The quoted uncertainties are 2sigma (95% confidence level) and include estimated systematic errors. Our results are compared with the previous quantum yield measurements of OH (MacLeod et al., J. Geophys. Res., 1988, 93, 3813) and NO2 (Roehl et al., 2001, J. Phys. Chem., 105, 1592) at 248 nm and the discrepancies are discussed. The rate coefficients at 298 K for reactions of OH with HO2NO2, H2O2, HNO3 and NO are also reported.

  10. Buffer-gas loaded MOTs for Ho, Yb,Tm, and Er

    NASA Astrophysics Data System (ADS)

    Chae, Eunmi; Drayna, Garrett; Hemmerling, Boerge; Hutzler, Nick; Ravi, Aakash; Collopy, Alejandra; Hummon, Matthew; Stuhl, Benjamin; Yeo, Mark; Ye, Jun; Doyle, John

    2014-05-01

    We report on direct loading of lanthanide atoms into MOTs from a two-stage slow buffer-gas beam source, which has a peak forward velocity of ~ 30 - 60 m/s, considerably lower than other beam implementations. The low velocity combined with species generality makes this source useful for loading magneto-optical traps (MOTs), especially for species that are not well suited to the traditional approach of oven plus Zeeman slower. We report loading MOTs with Yb, Tm, Er, and Ho, without any additional slowing stages. Application of a single frequency slowing laser to the buffer-gas beam of Yb results in an unprecedentedly high loading rate of 2 . 0 (1 . 0) ×1010 Yb atoms/s and 1 . 3 (0 . 7) ×108 Yb atoms in the MOT. We plan to use this versatile source to load a MOT with CaF, following the same general approach to that used with YO and SrF.

  11. 1.88 Micrometers InGaAsP Pumped, Room Temperature Ho: LuAG Laser

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Amzajerdian, Farzin; Reichle, Donald J.; Busch, George; Leisher, Paul

    2009-01-01

    A room temperature, directly diode pumped Ho:LuAG laser oscillated for the first time. Direct pumping of the Ho upper laser manifold maximizes efficiency, minimizes heating, and eliminates Ho:Tm energy sharing. Design and performance are presented.

  12. Role of Yb3+ ions on enhanced ~2.9 μm emission from Ho3+ ions in low phonon oxide glass system

    PubMed Central

    Balaji, Sathravada; Gupta, Gaurav; Biswas, Kaushik; Ghosh, Debarati; Annapurna, Kalyandurg

    2016-01-01

    The foremost limitation of an oxide based crystal or glass host to demonstrate mid- infrared emissions is its high phonon energy. It is very difficult to obtain radiative mid-infrared emissions from these hosts which normally relax non-radiatively between closely spaced energy levels of dopant rare earth ions. In this study, an intense mid-infrared emission around 2.9 μm has been perceived from Ho3+ ions in Yb3+/Ho3+ co-doped oxide based tellurite glass system. This emission intensity has increased many folds upon Yb3+: 985 nm excitation compared to direct Ho3+ excitations due to efficient excited state resonant energy transfer through Yb3+: 2F5/2 → Ho3+: 5I5 levels. The effective bandwidth (FWHM) and cross-section (σem) of measured emission at 2.9 μm are assessed to be 180 nm and 9.1 × 10−21 cm2 respectively which are comparable to other crystal/glass hosts and even better than ZBLAN fluoride glass host. Hence, this Ho3+/Yb3+ co-doped oxide glass system has immense potential for the development of solid state mid-infrared laser sources operating at 2.9 μm region. PMID:27374129

  13. New orthorhombic derivative of CaCu{sub 5}-type structure: RNi{sub 4}Si compounds (R=Y, La, Ce, Sm, Gd–Ho), crystal structure and some magnetic properties

    SciTech Connect

    Morozkin, A.V.; Knotko, A.V.; Yapaskurt, V.O.; Yuan, Fang; Mozharivskyj, Y.; Nirmala, R.

    2013-12-15

    The crystal structure of new YNi{sub 4}Si-type RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds has been established using powder X-ray diffraction. The YNi{sub 4}Si structure is a new structure type, which is orthorhombic derivative of CaCu{sub 5}-type structure (space group Cmmm N 65, oC12). GdNi{sub 4}Si and DyNi{sub 4}Si compounds order ferromagnetically at 25 and 19 K, respectively whereas YNi{sub 4}Si shows antiferromagnetic nature. At 15 K, DyNi{sub 4}Si shows second antiferromagnetic-like transition. The magnetic moment of GdNi{sub 4}Si at 5 K in 50 kOe field is ∼7.2 μ{sub B}/f.u. suggesting a completely ordered ferromagnetic state. The magnetocaloric effect of GdNi{sub 4}Si is calculated in terms of isothermal magnetic entropy change and it reaches the maximum value of −12.8 J/kg K for a field change of 50 kOe near T{sub C} ∼25 K. - Graphical abstract: The RNi{sub 4}Si (R=Y, La, Ce, Sm, Gd–Ho) compounds crystallize in new YNi{sub 4}Si-type structure which is orthorhombic derivative of the basic CaCu{sub 5}-type structure. GdNi{sub 4}Si and DyNi{sub 4}Si compounds show the ferromagnetic-like ordering, whereas.YNi{sub 4}Si has the antiferromagnetic nature. The GdNi{sub 4}Si demonstrates the big magnetocaloric effect near temperature of ferromagnetic ordering. The relationship between initial CaCu{sub 5}-type DyNi{sub 5} and YNi{sub 4}Si-type DyNi{sub 4}Si lattices.

  14. Measurements of the HO2 uptake coefficients onto single component organic aerosols.

    PubMed

    Lakey, P S J; George, I J; Whalley, L K; Baeza-Romero, M T; Heard, D E

    2015-04-21

    Measurements of HO2 uptake coefficients (γ) were made onto a variety of organic aerosols derived from glutaric acid, glyoxal, malonic acid, stearic acid, oleic acid, squalene, monoethanol amine sulfate, monomethyl amine sulfate, and two sources of humic acid, for an initial HO2 concentration of 1 × 10(9) molecules cm(-3), room temperature and at atmospheric pressure. Values in the range of γ < 0.004 to γ = 0.008 ± 0.004 were measured for all of the aerosols apart from the aerosols from the two sources of humic acid. For humic acid aerosols, uptake coefficients in the range of γ = 0.007 ± 0.002 to γ = 0.09 ± 0.03 were measured. Elevated concentrations of copper (16 ± 1 and 380 ± 20 ppb) and iron (600 ± 30 and 51 000 ± 3000 ppb) ions were measured in the humic acid atomizer solutions compared to the other organics that can explain the higher uptake values measured. A strong dependence upon relative humidity was also observed for uptake onto humic acid, with larger uptake coefficients seen at higher humidities. Possible hypotheses for the humidity dependence include the changing liquid water content of the aerosol, a change in the mass accommodation coefficient or in the Henry's law constant.

  15. Magnetic properties of HoMn2O5

    NASA Astrophysics Data System (ADS)

    Radulov, I.; Lovchinov, V.; Dimitrov, D.; Apostolov, A.; Nizhankovskii, V.; Daszkiewicz, M.

    2007-04-01

    We have investigated the detailed field and temperature dependence of the dielectric constant, dielectric losses, electric polarization, magnetization and magnetostriction (MS) in orthorhombic HoMn2O5 single crystals. HoMn2O5 displays incommensurate antiferromagnetic ordering below 39 K, becoming commensurate on further cooling. The commensurate-incommensurate transition takes place at low temperatures. The inherent magnetic frustration in this material is lifted by a small lattice distortion, primarily involving shifts of the Mn3+ cations and giving rise to a canted antiferroelectric phase. Colossal magnetostriction (CMS) effect was observed and a novel phase transition diagram was build.

  16. Asymptotic Freedom in Hořava-Lifshitz Gravity

    NASA Astrophysics Data System (ADS)

    D'Odorico, Giulio; Saueressig, Frank; Schutten, Marrit

    2014-10-01

    We use the Wetterich equation for foliated spacetimes to study the renormalization group flow of projectable Hořava-Lifshitz gravity coupled to n Lifshitz scalars. Using novel results for anisotropic heat kernels, the matter-induced beta functions for the gravitational couplings are computed explicitly. The renormalization group flow exhibits an UV attractive anisotropic Gaussian fixed point where Newton's constant vanishes and the extra scalar mode decouples. This fixed point ensures that the theory is asymptotically free in the large-n expansion, indicating that projectable Hořava-Lifshitz gravity is perturbatively renormalizable. Notably, the fundamental fixed point action does not obey detailed balance.

  17. Theoretical characterization of the minimum energy path for the reaction H + O2 to HO2(asterisk) to HO + O

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Rohlfing, Celeste Mcmichael; Melius, Carl F.; Bauschlicher, Charles W., Jr.

    1988-01-01

    The potential energy surface for the H + O2 to HO2(asterisk) to HO + O reaction has been investigated in the region of the minimum energy path using CASSCF/contracted CI (CCI) calculations with a large basis set. The results show no barrier for the addition of an H atom to O2, in agreement with previous studies. A crossing between the surface for electrostatic (OH dipole-O quadrupole) interaction and that for the formation of an O-O chemical bond, at r(infinity) of about 5.5 a(0), results in a small (about 0.5 kcal/mol) barrier.

  18. Microscopic insight into the study of band spectra of 158Ho and 159,161,163Ho isotopes

    NASA Astrophysics Data System (ADS)

    Slathia, Barun; Devi, Rani; Khosa, S. K.

    2016-11-01

    The nuclear structure properties of the low-lying and excited states of Holmium isotopes have been studied within the framework of Projected Shell Model. The theoretical results are found to be in the reasonable agreement with the observed ones. The theoretical B (M 1) / B (E 2) estimates of 158Ho are seen to reproduce the same systematics as shown by the observed ones. However, for 159,161,163Ho, the B (E 2) transition probabilities for the ground state band have been predicted for transitions for which the experimental values are not available.

  19. Living with ghosts in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Ramazanov, S.; Arroja, F.; Celoria, M.; Matarrese, S.; Pilo, L.

    2016-06-01

    We consider the branch of the projectable Hořava-Lifshitz model which exhibits ghost instabilities in the low energy limit. It turns out that, due to the Lorentz violating structure of the model and to the presence of a finite strong coupling scale, the vacuum decay rate into photons is tiny in a wide range of phenomenologically acceptable parameters. The strong coupling scale, understood as a cutoff on ghosts' spatial momenta, can be raised up to Λ ˜ 10 TeV. At lower momenta, the projectable Hořava-Lifshitz gravity is equivalent to General Relativity supplemented by a fluid with a small positive sound speed squared (10-42 ≲) c s 2 ≲ 10-20, that could be a promising candidate for the Dark Matter. Despite these advantages, the unavoidable presence of the strong coupling obscures the implementation of the original Hořava's proposal on quantum gravity. Apart from the Hořava-Lifshitz model, conclusions of the present work hold also for the mimetic matter scenario, where the analogue of the projectability condition is achieved by a non-invertible conformal transformation of the metric.

  20. Conductively Cooled Ho:Tm:LuLiF Laser Amplifier

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Trieu, Bo; Petros, M.; Petzar, Paul; Lee, Hyung; Singh, U.

    2008-01-01

    A conductively-cooled Ho:Tm:LuLiF laser head can amplify 80mJ/340ns probe pulses into 400mJ when the pump pulse energy is close to amplified spontaneous emission (ASE) threshold, 5.6J. For a small signal, the double-pass amplification exceeds 25.

  1. Registration of ‘Ho 00-961’ sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ho 00-961’ (Reg. No., PI) sugarcane (a complex hybrid of Saccharum officinarum L., S. spontaneum L., S. barberi Jeswiet, and S. sinense Roxb. amend. Jeswiet) was selected by the USDA-ARS Sugarcane Research Unit, and evaluated cooperatively with the Louisiana State University Agricultural Center, an...

  2. Programme Note: Realities and Opportunities in Ho Chi Minh City.

    ERIC Educational Resources Information Center

    Franchet, Chi Nguyen

    1996-01-01

    The current status of street children in Ho Chi Minh City, Vietnam, is characterized by marginalization from society through street vending, begging, theft, and prostitution. Evaluation of a drop-in center serving children without family linkages indicates need for needs assessments, follow-up activities, measurement of individual child progress,…

  3. Performance of Ho:YAG as a function of temperature

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Gettemy, Donald J.

    1990-01-01

    The performance of two multiply doped Ho:YAG lasers has been characterized as a function of the laser rod temperature. From the experimental results, the dependence of the slope efficiency and threshold on temperature has been extracted. Threshold can be correlated with the occupation of the lower laser level. Implications on the optimum operating temperature are discussed.

  4. Atomic transition rates for neutral holmium (Ho I)

    NASA Astrophysics Data System (ADS)

    Nave, Gillian

    2003-10-01

    Transition rates for 321 lines between 345 and 1080 nm from 73 levels of Ho I are presented. They have been measured by combining branching fractions obtained by Fourier transform spectrometry with lifetimes of Den Hartog et al. [J. Opt. Soc. Am. B 6, 2278 (1999)]. The uncertainty of the transition rates is 5%-10%.

  5. 2012 Louisiana "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three years after selection in the seedling stage of the USDA variety program, superior experimental varieties are assigned permanent “HoCP” or “Ho” numbers. These varieties are then planted in replicated yield trials at SRU’s Ardoyne Farm in Schriever and at the LSU AgCenter’s Iberia Research Stati...

  6. Temperature Dependence of the O + HO2 Rate Coefficient

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1997-01-01

    A pulsed laser photolysis technique has been employed to investigate the kinetics of the radical-radical reaction O((sup 3)P) + HO2 OH + O2 over the temperature range 266-391 K in 80 Torr of N2 diluent gas. O((sup 3)P) was produced by 248.5-nm KrF laser photolysis of O3 followed by rapid quenching of O(1D) to O((sup 3)P) while HO2 was produced by simultaneous photolysis of H2O2 to create OH radicals which, in turn, reacted with H2O2 to yield HO2. The O((sup 3)P) temporal profile was monitored by using time-resolved resonance fluorescence spectroscopy. The HO2 concentration was calculated based on experimentally measured parameters. The following Arrhenius expression describes our experimental results: k(sub 1)(T) equals (2.91 +/- 0.70) x 10(exp -11) exp[(228 +/- 75)/T] where the errors are 2 sigma and represent precision only. The absolute uncertainty in k, at any temperature within the range 266-391 K is estimated to be +/- 22 percent. Our results are in excellent agreement with a discharge flow study of the temperature dependence of k(sub 1) in 1 Torr of He diluent reported by Keyser, and significantly reduce the uncertainty in the rate of this important stratospheric reaction at subambient temperatures.

  7. Single-frequency lasing of monolithic Ho,Tm:YLF

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Deyst, John P.; Storm, Mark E.

    1993-01-01

    Single-frequency lasing in monolithic crystals of holmium-thulium-doped YLF (Ho,Tm:YLF) is reported. A maximum single-frequency output power of 6 mW at a wavelength of 2.05 microns is demonstrated. Frequency tuning is also described.

  8. Low temperature magnetic transitions of single crystal HoBi

    SciTech Connect

    Fente, A.; Suderow, H.; Vieira, S.; Nemes, N. M.; García-Hernández, M.; Bud'ko, S. L.; Canfield, P. C.

    2013-10-01

    We present resistivity, specific heat and magnetization measurements in high quality single crystals of HoBi, with a residual resistivity ratio of 126. We find, from the temperature and field dependence of the magnetization, an antiferromagnetic transition at 5.7 K, which evolves, under magnetic fields, into a series of up to five metamagnetic phases.

  9. 2014 Louisiana "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the USDA sugarcane variety program, superior experimental varieties are assigned permanent “HoCP” or “Ho” numbers three years after selection in the seedling stage. These varieties are then planted in replicated yield trials at the Sugarcane Research Unit's (SRU) Ardoyne Farm in Schriever and at ...

  10. Flash-lamp-pumped Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF lasers: experimental results of a single, long pulse length comparison.

    PubMed

    Jani, M G; Barnes, N P; Murray, K E

    1997-05-20

    Flash-lamp-pumped, room-temperature Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF are compared for single but long pulse operation, with pulse lengths of approximately 1.0 mus. Under similar operating conditions in normal-mode operation, a slope efficiency of 0.0331 was observed for Ho:Tm:Er:YLF compared with 0.0047 for Ho:Tm:Cr:YAG. For Q-switched operation, Ho:Tm:Er:YLF yielded a slope efficiency of 0.0075. In comparison, a slope efficiency of 0.0012 was obtained for Ho:Tm:Cr:YAG. Two methods of producing long pulse lengths are compared: pulse selection of normal-mode relaxation oscillations and Q-switching in a long resonator. Theoretical models developed in a companion paper for normal-mode relaxation oscillations and Q-switching in quasi-four-level solid-state lasers are in agreement with the experimental results.

  11. Critical budget of metal sources and pathways in the Seine River basin (1994-2003) for Cd, Cr, Cu, Hg, Ni, Pb and Zn.

    PubMed

    Thévenot, Daniel R; Moilleron, Régis; Lestel, Laurence; Gromaire, Marie-Christine; Rocher, Vincent; Cambier, Philippe; Bonté, Philippe; Colin, Jean-Louis; de Pontevès, Claire; Meybeck, Michel

    2007-04-01

    River basin metal pollution originates from heavy industries (plating, automobile) and from urban sources (Paris conurbation: 2740 km(2), 9.47 million inhabitants). The natural sources of metal have been found to be limited due to sedimentary nature of this catchment and to the very low river sediment transport (10 t km(-2) y(-1)). Several types of data have been collected to build the metal budget within the whole Seine River basin: field surveys, economical statistics and environmental models. Environmental contamination and related fluxes have been measured on atmospheric fallout, rural streams particles, and Seine River particles upstream and downstream of Paris and at river mouth. Metal pathways and budgets have been set up for (i) a typical cultivated area, (ii) a Paris combined sewer system, (iii) Paris conurbation and (iv) the whole catchment metal retention effect in floodplain and dredged material. Metal fluxes to the estuary have been decomposed into natural, urban domestic and other sources. The latter are within 1-2 orders of magnitude larger than waste water fluxes directly released into rivers according to an industrial census. These fluxes have been further compared to the annual use (1994-2003) of these metals. Metal excess fluxes exported by the river are now a marginal leak of metal inputs to the catchment (i.e. "raw" metals, metals in goods, atmospheric fallout), generally from 0.2 to 5 per thousand. However, due to the very limited dilution power in this basin, the contamination of particles is still relatively high. The Seine River basin is gradually storing metals, mostly in manufactured products used in construction, but also in various waste dumps, industrial soils, agricultural and flood plain soils.

  12. Electron microscopy study of Ni induced crystallization in amorphous Si thin films

    SciTech Connect

    Radnóczi, G. Z.; Battistig, G.; Pécz, B.; Dodony, E.; Vouroutzis, N.; Stoemenos, J.; Frangis, N.; Kovács, A.

    2015-02-17

    The crystallization of amorphous silicon is studied by transmission electron microscopy. The effect of Ni on the crystallization is studied in a wide temperature range heating thinned samples in-situ inside the microscope. Two cases of limited Ni source and unlimited Ni source are studied and compared. NiSi{sub 2} phase started to form at a temperature as low as 250°C in the limited Ni source case. In-situ observation gives a clear view on the crystallization of silicon through small NiSi{sub 2} grain formation. The same phase is observed at the crystallization front in the unlimited Ni source case, where a second region is also observed with large grains of Ni{sub 3}Si{sub 2}. Low temperature experiments show, that long annealing of amorphous silicon at 410 °C already results in large crystallized Si regions due to the Ni induced crystallization.

  13. Luminescence properties of long-lasting phosphor SrMg2(PO4)2:Eu2+, Ho3+, Zr4+

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Wang, Mingwen; Lin, Wei; Ye, Yaping; Wu, Xue

    2016-12-01

    Novel long lasting phosphors SrMg2(PO4)2:Eu2+, SrMg2(PO4)2:Eu2+, Zr4+, SrMg2(PO4)2:Eu2+, Ho3+ and SrMg2(PO4)2:Eu2+, Ho3+, Zr4+ were synthesized by conventional solid-state reaction method. The luminescent properties were systematically characterized by X-ray diffraction, photoluminescent excitation and emission spectra, as well as thermoluminescence spectrum and decay curves. The XRD patterns indicated that the samples belonged to monoclinic phase and co-doping Eu2+, Ho3+ and Zr4+ ions had no effect on the basic crystal structure. These phosphors emitting purplish blue light is related to the characteristic emission of Eu2+. The afterglow time of Eu2+ activated SrMg2(PO4)2 can be greatly enhanced by the co-doping of Ho3+, Zr4+. After the 365 nm UV light excitation source switching off, the Sr0.92Mg1.95(PO4)2:Eu2+0.01, Zr4+0.05, Ho3+0.07 phosphorescence can be observed for more than 1013 s in the limit of light perception of dark-adapted human eyes (0.32 mcd/m2). Different kinds of TL peaks at 423, 448 and 473 K have appeared, and traps densities have increased compared with the Eu2+ single doped SrMg2(PO4)2 phosphor. By analyzing the TL curve the depths of traps were calculated to be 0.846, 0.896 and 0.946 eV, respectively, which suggested that the co-doping of Ho3+, Zr4+ improved the electron storage ability of material. Besides, the mechanism was discussed in this report.

  14. Materials Data on HoNi2 (SG:227) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-05

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  15. Materials Data on Ni(HO)2 (SG:5) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. Materials Data on Ni(HO)2 (SG:156) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  17. Materials Data on HoNi (SG:62) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-05-16

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Materials Data on Ho3Ni19B10 (SG:12) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Materials Data on HoNiO3 (SG:62) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-04-22

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on HoNi4B (SG:191) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on Ho2NiIr (SG:225) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-08-28

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Relationships between NOS2 and HO-1 in liver of rats with chronic bile duct ligation.

    PubMed

    Flores, Olga; Criado, Manuela; Sánchez-Rodríguez, Angel; Hidalgo, Froilán; Collía, Francisco; López-Novoa, José Miguel; Esteller, Alejandro

    2005-05-01

    An increased expression and activity of the heme oxygenase-1 (HO-1) in the liver has been observed in models of hepatic damage. Nitric oxide (NO) seems to be involved in HO-1 regulation. The aim of this work is to assess HO-1 induction and heme oxygenase (HO) activity in rats with bile duct ligation (BDL). We have assessed the effect of chronic inhibition of the NO synthesis by N(G)-nitro-l-arginine methyl ester (l-NAME) on HO-1 induction and HO activity. In the BDL animals, compared with sham-operated ones, we found an increased plasma nitrite and bilirubin concentration, and a marked liver expression of inducible nitric oxide synthase and HO-1, assessed by both Western blot and immunohistochemistry. Chronic l-NAME treatment prevented plasma nitrite increase in animals subjected to BDL. BDL animals treated with l-NAME, compared with untreated BDL rats, showed an important decrease in HO-1 expression and in HO activity (assessed as a decreased plasma bilirubin and bilirubin excretion). In conclusion, our experiments show parallel changes in expression and activity of HO-1 and NOS2 activity in the BDL model of liver damage and suggest that increased NO production is involved in HO-1 overexpression.

  3. Nuclear spectroscopy above isomers in {sub 67}{sup 148}Ho{sub 81} and {sub 67}{sup 149}Ho{sub 82} nuclei: Search for core-excited states in {sup 149}Ho

    SciTech Connect

    Kownacki, J.; Napiorkowski, P. J.; Zielinska, M.; Kordyasz, A.; Srebrny, J.; Droste, Ch.; Morek, T.; Grodner, E.; Ruchowska, E.; Korman, A.; Czarnacki, W.; Kisielinski, M.; Kowalczyk, M.; Wrzosek-Lipska, K.; Hadynska-KlePk, K.; Mierzejewski, J.; Lieder, R. M.; Perkowski, J.; Andrzejewski, J.; Krol, A.

    2010-04-15

    The excited states of {sup 148}Ho and {sup 149}Ho isotopes are studied using gamma-ray and electron spectroscopy in off-beam and in-beam modes following {sup 112,114}Sn({sup 40}Ar,xnyp) reactions. Experiments include measurements of single gamma-rays and conversion electron spectra as well as gamma-gamma, electron-gamma, gamma-t, and gamma-gamma-t coincidences with the use of the OSIRIS-II 12-HPGe array and conversion electron spectrometer. Based on the present results, the level schemes of {sup 148}Ho and {sup 149}Ho are revised and significantly extended, up to about 4 and 5 MeV of excitation energy, respectively. Spin and parity of 5{sup -} are assigned to the 9.59-s isomer in {sup 148}Ho based on conversion electron results. Previously unobserved gamma rays feeding the 10{sup +} isomer in {sup 148}Ho and the 27/2{sup -} isomer in {sup 149}Ho nuclei are proposed. Shell-model calculations are performed. Possible core-excited states in {sup 149}Ho are discussed.

  4. South Pole Antarctica observations and modeling results: New insights on HO x radical and sulfur chemistry

    NASA Astrophysics Data System (ADS)

    Mauldin, Roy; Kosciuch, Edward; Eisele, Fred; Huey, Greg; Tanner, David; Sjostedt, Steve; Blake, Don; Chen, Gao; Crawford, Jim; Davis, Douglas

    2010-02-01

    Measurements of OH, H 2SO 4, and MSA at South Pole (SP) Antarctica were recorded as a part of the 2003 Antarctic Chemistry Investigation (ANTCI 2003). The time period 22 November, 2003-2 January, 2004 provided a unique opportunity to observe atmospheric chemistry at SP under both natural conditions as well as those uniquely defined by a solar eclipse event. Results under natural solar conditions generally confirmed those reported previously in the year 2000. In both years the major chemical driver leading to large scale fluctuations in OH was shifts in the concentration levels of NO. Like in 2000, however, the 2003 observational data were systematically lower than model predictions. This can be interpreted as indicating that the model mechanism is still missing a significant HO x sink reaction(s); or, alternatively, that the OH calibration source may have problems. Still a final possibility could involve the integrity of the OH sampling scheme which involved a fixed building site. As expected, during the peak in the solar eclipse both NO and OH showed large decreases in their respective concentrations. Interestingly, the observational OH profile could only be approximated by the model mechanism upon adding an additional HO x radical source in the form of snow emissions of CH 2O and/or H 2O 2. This would lead one to think that either CH 2O and/or H 2O 2 snow emissions represent a significant HO x radical source under summertime conditions at SP. Observations of H 2SO 4 and MSA revealed both species to be present at very low concentrations (e.g., 5 × 10 5 and 1 × 10 5 molec cm -3, respectively), but similar to those reported in 2000. The first measurements of SO 2 at SP demonstrated a close coupling with the oxidation product H 2SO 4. The observed low concentrations of MSA appear to be counter to the most recent thinking by glacio-chemists who have suggested that the plateau's lower atmosphere should have elevated levels of MSA. We speculate here that the absence

  5. Cluster-size dependent internal dynamics and magnetic anisotropy of Ho ions in HoM2N@C80 and Ho2MN@C80 families (M = Sc, Lu, Y)

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Krylov, D.; Schiemenz, S.; Rosenkranz, M.; Westerström, R.; Dreiser, J.; Greber, T.; Büchner, B.; Popov, A. A.

    2014-09-01

    The paramagnetic NMR study of HoM2N@C80-Ih and Ho2MN@C80-Ih nitride cluster fullerenes (M = Sc, Lu, Y) reveals strong dependence of Ho-induced paramagnetic shifts (δpara) in 13C NMR spectra on the size of the diamagnetic metal in the cluster. In particular, the δpara value in HoY2N@C80 is almost doubled in comparison to that in HoSc2N@C80. X-ray magnetic circular dichroism studies show that all Ho-nitride cluster fullerenes have the same magnetic ground state of Ho3+. Point-charge ligand-field splitting calculations show that the increase of the M3+ radius in going from Sc to Y results in a considerable increase of the energy splitting between different Jz states. This leads to a 19% higher magnetic anisotropy of Ho3+ in HoY2N@C80 than in HoSc2N@C80 at 300 K. Variations of the molecular geometry and cluster dynamics with the size of the cluster are found to have even greater influence on δpara values. This work shows that the magnetic properties of the species confined inside the fullerene cages can be tuned using the geometrical factors such as the cluster and the cage size.The paramagnetic NMR study of HoM2N@C80-Ih and Ho2MN@C80-Ih nitride cluster fullerenes (M = Sc, Lu, Y) reveals strong dependence of Ho-induced paramagnetic shifts (δpara) in 13C NMR spectra on the size of the diamagnetic metal in the cluster. In particular, the δpara value in HoY2N@C80 is almost doubled in comparison to that in HoSc2N@C80. X-ray magnetic circular dichroism studies show that all Ho-nitride cluster fullerenes have the same magnetic ground state of Ho3+. Point-charge ligand-field splitting calculations show that the increase of the M3+ radius in going from Sc to Y results in a considerable increase of the energy splitting between different Jz states. This leads to a 19% higher magnetic anisotropy of Ho3+ in HoY2N@C80 than in HoSc2N@C80 at 300 K. Variations of the molecular geometry and cluster dynamics with the size of the cluster are found to have even greater influence on

  6. Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho

    NASA Astrophysics Data System (ADS)

    Rettig, L.; Dornes, C.; Thielemann-Kühn, N.; Pontius, N.; Zabel, H.; Schlagel, D. L.; Lograsso, T. A.; Chollet, M.; Robert, A.; Sikorski, M.; Song, S.; Glownia, J. M.; Schüßler-Langeheine, C.; Johnson, S. L.; Staub, U.

    2016-06-01

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E 1 , 2 p →5 d ) or quadrupole (E 2 , 2 p →4 f ) transition allows us to selectively and independently study the spin dynamics of the itinerant 5 d and localized 4 f electronic subsystems via the suppression of the magnetic (2 1 3 -τ ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4 f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4 f -5 d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  7. Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho.

    PubMed

    Rettig, L; Dornes, C; Thielemann-Kühn, N; Pontius, N; Zabel, H; Schlagel, D L; Lograsso, T A; Chollet, M; Robert, A; Sikorski, M; Song, S; Glownia, J M; Schüßler-Langeheine, C; Johnson, S L; Staub, U

    2016-06-24

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L_{3} absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E1, 2p→5d) or quadrupole (E2, 2p→4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3-τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f-5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  8. The uptake of HO2 radicals to organic aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, Pascale; Krapf, Manuel; Dommen, Josef; George, Ingrid; Whalley, Lisa; Ingham, Trevor; Baeza-Romero, Maria Teresa; Ammann, Markus; Heard, Dwayne

    2014-05-01

    HOx (OH + HO2) radicals are responsible for the majority of the oxidation in the troposphere and control the concentrations of many trace species in the atmosphere. There have been many field studies where the measured HO2 concentrations have been smaller than the concentration predicted by model calculations [1,2]. The difference has often been attributed to HO2 uptake by aerosols. Organics are a major component of aerosols accounting for 10 - 70 % of their mass [3]. However, there have been very few laboratory studies measuring HO2 uptake onto organic aerosols [4]. Uptake coefficients (γ) were measured for a range of aerosols using a Fluorescence Assay By Gas Expansion (FAGE) detector combined with an aerosol flow tube. HO2 was injected into the flow tube using a moveable injector which allowed first order HO2 decays to be measured along the flow tube both with and without aerosols. Laboratory generated aerosols were made using an atomiser or by homogeneous nucleation. Secondary organic aerosols (SOA) were made using the Paul Scherrer Institute smog chamber and also by means of a Potential Aerosol Mass (PAM) chamber. The total aerosol surface area was then measured using a Scanning Mobility Particle Sizer (SMPS). Experiments were carried out on aerosols containing glutaric acid, glyoxal, malonic acid, stearic acid, oleic acid and squalene. The HO2 uptake coefficients for these species were measured in the range of γ < 0.004 to γ = 0.008 ± 0.004. Humic acid was also studied, however, much larger uptake coefficients (γ = 0.007 - 0.09) were measured, probably due to the fact that these aerosols contained elevated levels of transition metal ions. For humic acid the uptake coefficient was highly dependent on humidity and this may be explained by the liquid water content of the aerosols. Measurements were also performed on copper doped aerosols containing different organics. An uptake coefficient of 0.23 ± 0.07 was measured for copper doped ammonium sulphate

  9. Novel imidazole derivatives as heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2) inhibitors and their cytotoxic activity in human-derived cancer cell lines.

    PubMed

    Salerno, Loredana; Pittalà, Valeria; Romeo, Giuseppe; Modica, Maria N; Marrazzo, Agostino; Siracusa, Maria A; Sorrenti, Valeria; Di Giacomo, Claudia; Vanella, Luca; Parayath, Neha N; Greish, Khaled

    2015-01-01

    Heme oxygenase (HO) is a cytoprotective enzyme that can be overexpressed in some pathological conditions, including certain cancers. In this work, novel imidazole derivatives were designed and synthesized as inhibitors of heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). In these compounds the imidazole ring, crucial for the activity, is connected to a hydrophobic group, represented by aryloxy, benzothiazole, or benzoxazole moieties, by means of alkyl or thioalkyl chains of different length. Many of the tested compounds were potent and/or selective against one of the two isoforms of HO. Furthermore, most of the pentyl derivatives showed to be better inhibitors of HO-2 with respect to HO-1, revealing a critical role of the alkyl chain in discriminating between the two isoenzymes. Compounds which showed the better profile of HO inhibition were selected and tested to evaluate their cytotoxic properties in prostate and breast cancer cell lines (DU-145, PC3, LnCap, MDA-MB-231, and MCF-7). In these assays, aryloxyalkyl derivatives resulted more cytotoxic than benzothiazolethioalkyl ones; in particular compound 31 was active against all the cell lines tested, confirming the anti-proliferative properties of HO inhibitors and their potential use in the treatment of specific cancers.

  10. Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

    DOE PAGES

    Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.; ...

    2015-04-29

    The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm–3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MSmore » to determine the 163Ho/165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.« less

  11. Sex-Dependent Effects of HO-1 Deletion from Adipocytes in Mice

    PubMed Central

    Hosick, Peter A.; Weeks, Mary Frances; Hankins, Michael W.; Moore, Kyle H.; Stec, David E.

    2017-01-01

    Induction of heme oxygenase-1 (HO-1) has been demonstrated to decrease body weight and improve insulin sensitivity in several models of obesity in rodents. To further study the role of HO-1 in adipose tissue, we created an adipose-specific HO-1 knockout mouse model. Male and female mice were fed either a control or a high-fat diet for 30 weeks. Body weights were measured weekly and body composition, fasting blood glucose and insulin levels were determined every six weeks. Adipocyte-specific knockout of HO-1 had no significant effect on body weight in mice fed a high-fat diet but increased body weight in female mice fed a normal-fat diet. Although body weights were not different in females fed a high fat diet, loss of HO-1 in adipocytes resulted in significant alterations in body composition. Adipose-specific HO-1 knockout resulted in increased fasting hyperglycemia and insulinemia in female but not male mice on both diets. Adipose-specific knockout of HO-1 resulted in a significant loss of HO activity and a decrease in the protein levels of adiponectin in adipose tissue. These results demonstrate that loss of HO-1 in adipocytes has greater effects on body fat and fasting hyperglycemia in a sex-dependent fashion and that expression of HO-1 in adipose tissue may have a greater protective role in females as compared to males. PMID:28287466

  12. Identical gamma-vibrational bands in {sup 165}Ho

    SciTech Connect

    Radford, D.C.; Galindo-Uribarri, A.; Janzen, V.P.

    1996-12-31

    The structure of {sup 165}Ho at moderate spins has been investigated by means of Coulomb excitation. Two {gamma}-vibrational bands (K{sup {pi}} = 11/2{sup {minus}} and K{sup {pi}} = 3/2{sup {minus}}) are observed, with very nearly identical in-band {gamma}-ray energies. Gamma-ray branching ratios are analyzed to extract information on Coriolis mixing, and the role of the K quantum number in identical bands is discussed.

  13. Smart Ho:YAG laser lithotriptor using optical correlation

    NASA Astrophysics Data System (ADS)

    Kokaj, Jahja O.; Marafi, Mustafa A.; Makdisi, Yacob; Bhatia, Kuldip S.; Mathew, K. J.; Caka, Nebi; Hasani, Rexhep

    1998-03-01

    Ultra fast imaging and destruction of the gall bladder stone is performed using Ho:YAG laser. A laser guided approach for lithotropsy is proposed. The correlation output peak is introduced as a feedback signal for firing the laser pulse for stone destruction and 'discrimination' of the tissue image so that the risk of damaging and perforation of the tissue is reduced. A system constituted by correlation of ballistic images and fluorescent signals is proposed.

  14. The uptake of HO2 on meteoric smoke analogues

    NASA Astrophysics Data System (ADS)

    James, Alexander D.; Moon, Daniel R.; Feng, Wuhu; Lakey, Pascale S. J.; Frankland, Victoria L.; Heard, Dwayne E.; Plane, John M. C.

    2017-01-01

    The kinetics of heterogeneous HO2 uptake onto meteoric smoke particles (MSPs) has been studied in the laboratory using analogues of MSP aerosol entrained into a flow tube. The uptake coefficient, γ, was determined on synthetic amorphous olivine (MgFeSiO4) to be (6.9 ± 1.2) × 10-2 at a relative humidity (RH) of 10%. On forsterite (Mg2SiO4), γ = (4.3 ± 0.4) × 10-3 at RH = 11.6% and (7.3 ± 0.4) × 10-2 at RH = 9.9% on fayalite (Fe2SiO4). These results indicate that Fe plays a more important mechanistic role than Mg in the removal of HO2 from the gas phase. Electronic structure calculations show that Fe atoms exposed at the particle surface provide a catalytic site where HO2 is converted to H2O2 via an Eley-Rideal mechanism, but this does not occur on exposed surface Mg atoms. The impact of this heterogeneous process in the middle atmosphere was then investigated using a whole atmosphere chemistry-climate model which incorporates a microphysical treatment of MSPs. Using a global MSP production rate from meteoric ablation of 44 t/day, heterogeneous uptake (with γ = 0.2) on MSPs significantly alters the HOx budget in the nighttime polar vortex. This impact is highly latitude dependent and thus could not be confirmed using currently available satellite measurements of HO2, which are largely unavailable at latitudes greater than 70°.

  15. A stable gain-switched Ho:CYA laser resonantly pumped at 1922 nm

    NASA Astrophysics Data System (ADS)

    Zhang, J. N.; Chen, B. H.; Shen, D. Y.; Xu, X. D.

    2017-04-01

    We report on a gain-switched Ho:CaYAlO4 laser resonantly pumped by a home-constructed high power Tm:fiber laser at ~1922 nm. Stable nanosecond single-pulse operation could be maintained when the continuous-wave pump signal was modulated at repetition rates of 60–100 kHz with an acousto-optic modulator. A pulse duration of 311 ns has been obtained at a 60 kHz repetition rate under a pump power level of 11 W. The temporal stability and simplicity of operation make this laser suitable for a variety of applications, such as spectroscopy, gas sensing, and as the seed source of a master oscillation power amplifier system.

  16. In-band pumped Ho3+:KY3F10 2 μm laser.

    PubMed

    Schellhorn, Martin; Parisi, Daniela; Veronesi, Stefano; Bolognesi, Giacomo; Eichhorn, Marc; Tonelli, Mauro

    2013-02-15

    We report the first observation to our knowledge of room-temperature continuous-wave laser operation on the (5)I(7)→(5)I(8) transition of Ho(3+) ions in a KY(3)F(10) single crystal. Using a Tm-doped silica fiber laser operating at 1938 nm as a pump source, a maximum laser power of 1.8 W was obtained at a wavelength of ~2040 nm for 27 W of absorbed pump power with a slope efficiency of 19.1% with respect to absorbed power. At low cavity output coupling, the lasing wavelength shifted to 2060.5 nm. The beam propagation factor (M(2)) was measured to be <1.06 at the maximum output power, confirming fundamental transverse-mode (TEM(00)) operation. Performing a Caird analysis, we determined resonator round-trip losses and intrinsic slope efficiency of 30% and 43.8%, respectively.

  17. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    2012-05-01

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  18. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  19. Degradation of poly(3-hydroxyoctanoic acid) [P(3HO)] by bacteria: Purification and properties of a P(3HO) depolymerase from Pseudomonas fluorescens GK13

    SciTech Connect

    Schirmer, A.; Jendrossek, D.; Schlegel, H.G. )

    1993-04-01

    Poly(3-hydroxyoctanoic acid)[P(3HO)] and other poly(hydroxyalkanoic acids) PHA are widespread bacterial storage compounds of carbon and reducing power. They are biodegradable to carbon dioxide and water, and both aerobic and anaerobic P(3HB)-degradable bacteria are widely distributed in various ecosytems: soil, activated sludge, lake water and air, sea water, estuarine sediment, and anaerobic sewage sludge. This study describes the isolation and characterization of P(3HO) degrading bacteria: Alcaligenes eutrophus, Comamonas violaceum, Pseudomonas citronellolis, and P. fluorescenes (2 strains). The authors also describe purified P(3HO) depolymerase and compared it to PHB and PHA deploymerases. P(3HO) depolymerase activity was found not only in the sulture supernatant but also in the soluble fraction and membrane fractions of P(3HO) grown cells.39 refs.,5 figs.,3 tabs.

  20. Kinetics of HO2 + HO2 -> H2O2 + O2: Implications for Stratospheric H2O2

    NASA Astrophysics Data System (ADS)

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Salawitch, R. J.; Toon, G. C.; Sen, B.; Blavier, J.-F.; Jucks, K. W.

    2002-05-01

    The reaction HO2 + HO2 -> H2O2 + O2(1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl2/CH3OH/O2/N2 and F2/H2/O2/N2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k1 = (8.8 +/- 0.9) 10-13 × exp[(210 +/- 26)/T] cm3 molecule-1 s-1 (2σ uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k1, which includes the dependence on bath gas density, is k1 = (1.5 +/- 0.2) × 10-12 × exp[(19 +/- 31)/T] + 1.7 × 10-33 × [M] × exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere.

  1. Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines.

    PubMed

    Llovet, Xavier; Pinard, Philippe T; Heikinheimo, Erkki; Louhenkilpi, Seppo; Richter, Silvia

    2016-12-01

    We report electron probe microanalysis measurements on nickel silicides, Ni5Si2, Ni2Si, Ni3Si2, and NiSi, which were done in order to investigate anomalies that affect the analysis of such materials by using the Ni L3-M4,5 line (Lα). Possible sources of systematic discrepancies between experimental data and theoretical predictions of Ni L3-M4,5 k-ratios are examined, and special attention is paid to dependence of the Ni L3-M4,5 k-ratios on mass-attenuation coefficients and partial fluorescence yields. Self-absorption X-ray spectra and empirical mass-attenuation coefficients were obtained for the considered materials from X-ray emission spectra and relative X-ray intensity measurements, respectively. It is shown that calculated k-ratios with empirical mass attenuation coefficients and modified partial fluorescence yields give better agreement with experimental data, except at very low accelerating voltages. Alternatively, satisfactory agreement is also achieved by using the Ni L3-M1 line (Lℓ) instead of the Ni L3-M4,5 line.

  2. High-power and highly efficient diode-cladding-pumped Ho3+-doped silica fiber lasers.

    PubMed

    Jackson, Stuart D; Bugge, Frank; Erbert, Götz

    2007-11-15

    We demonstrate high-power operation from a singly Ho3+-doped silica fiber laser that is cladding pumped directly with diode lasers operating at 1150 nm. Internal slope efficiencies approaching the Stokes limit were produced, and the maximum output power was 2.2W. This result was achieved using a low Ho3+-ion concentration and La3+-ion codoping, which together limit the transfer of energy between excited Ho3+ ions.

  3. Purification and activity standardisation of a (166m)Ho solution.

    PubMed

    Nedjadi, Youcef; Spring, Philippe; Bailat, Claude; Froidevaux, P; Wastiel, C; Bochud, François

    2008-01-01

    As part of a project to use the long-lived (T(1/2)=1200a) (166m)Ho as reference source in its reference ionisation chamber, IRA standardised a commercially acquired solution of this nuclide using the 4pibeta-gamma coincidence and 4pigamma (NaI) methods. The (166m)Ho solution supplied by Isotope Product Laboratories was measured to have about 5% Europium impurities (3% (154)Eu, 0.94% (152)Eu and 0.9% (155)Eu). Holmium had therefore to be separated from europium, and this was carried out by means of ion-exchange chromatography. The holmium fractions were collected without europium contamination: 162h long HPGe gamma measurements indicated no europium impurity (detection limits of 0.01% for (152)Eu and (154)Eu, and 0.03% for (155)Eu). The primary measurement of the purified (166m)Ho solution with the 4pi (PC) beta-gamma coincidence technique was carried out at three gamma energy settings: a window around the 184.4keV peak and gamma thresholds at 121.8 and 637.3keV. The results show very good self-consistency, and the activity concentration of the solution was evaluated to be 45.640+/-0.098kBq/g (0.21% with k=1). The activity concentration of this solution was also measured by integral counting with a well-type 5''x5'' NaI(Tl) detector and efficiencies computed by Monte Carlo simulations using the GEANT code. These measurements were mutually consistent, while the resulting weighted average of the 4pi NaI(Tl) method was found to agree within 0.15% with the result of the 4pibeta-gamma coincidence technique. An ampoule of this solution and the measured value of the concentration were submitted to the BIPM as a contribution to the Système International de Référence.

  4. Corrigendum to "Hierarchical Ni0.54Co0.46O2 nanowire and nanosheet arrays grown on carbon fiber cloth for high-performance supercapacitors" [J. Power Source 329 (2016) 473-483

    NASA Astrophysics Data System (ADS)

    Jiang, Yuanzhi; Zhang, Lijuan; Zhang, Hang; Zhang, Cui; Liu, Shuangxi

    2016-11-01

    The authors regret that the chemical formula of "Ni0.54Co0.46O2" is incorrect throughout the article and should be changed to "Ni0.54Co0.46O" in all cases. Moreover, there was a clerical mistake in Equation (2) which should be corrected as "E = ∫ I × V(t) dt / 3.6 ". These clerical mistakes do NOT have any effect on the discussion or conclusion of the article.

  5. Low Temperature Chlorine-Initiated Oxidation of Small-Chain Methyl Esters: Quantification of Chain-Terminating HO2-Elimination Channels.

    PubMed

    Muller, Giel; Scheer, Adam; Osborn, David L; Taatjes, Craig A; Meloni, Giovanni

    2016-03-17

    Cl-initiated oxidation reactions of three small-chain methyl esters, methyl propanoate (CH3CH2COOCH3; MP), methyl butanoate (CH3CH2CH2COOCH3; MB), and methyl valerate (CH3CH2CH2CH2COOCH3; MV), are studied at 1 or 8 Torr and 550 and 650 K. Products are monitored as a function of mass, time, and photoionization energy using multiplexed photoionization mass spectrometry coupled to tunable synchrotron photoionization radiation. Pulsed photolysis of molecular chlorine is the source of Cl radicals, which remove an H atom from the ester, forming a free radical. In each case, after addition of O2 to the initial radicals, chain-terminating HO2-elimination reactions are observed to be important. Branching ratios among competing HO2-elimination channels are determined via absolute photoionization spectra of the unsaturated methyl ester coproducts. At 550 K, HO2-elimination is observed to be selective, resulting in nearly exclusive production of the conjugated methyl ester coproducts, methyl propenoate, methyl-2-butenoate, and methyl-2-pentenoate, respectively. However, in MV, upon raising the temperature to 650 K, other HO2-elimination pathways are observed that yield methyl-3-pentenoate and methyl-4-pentenoate. In each methyl ester oxidation reaction, a peak is observed at a mass consistent with cyclic ether formation, indicating chain-propagating OH loss/ring formation pathways via QOOH intermediates. Evidence is observed for the participation of resonance-stabilized QOOH in the most prominent cyclic ether pathways. Stationary point energies for HO2-elimination pathways and select cyclic ether formation channels are calculated at the CBS-QB3 level of theory and assist in the assignment of reaction pathways and final products.

  6. Magnetic properties and structures of fibrous R11Ni4In9 intermetallics (R = heavy rare earths)

    NASA Astrophysics Data System (ADS)

    Provino, Alessia; Ritter, Clemens; Gschneidner, Karl A.; Manfrinetti, Pietro; Dhar, Sudesh K.; Pecharsky, Vitalij K.

    2015-03-01

    The existence and the unusual self-assembled nano/microfibrous morphology of the R11T4In9 (R = rare earth, T = Ni, Pd, Pt) phases has been recently studied [1,2,3]. All the rare earths (but Sc, Eu, Yb) form this ternary compound (orthorhombic Nd11Pd4In9-type, oC48, Cmmm). The bundles of fibers grow parallel to the temperature gradient and along the short c-axis. In this presentation we describe the results of a detailed investigation of the physical properties (electrical resistivity, heat capacity, magnetization measurements) of Tb11Ni4In9, Dy11Ni4In9andHo11Ni4In9 by orienting the fibers parallel and orthogonal, respectively, to the electric current and magnetic field. The unusual fibrous microstructure of these compounds leads to a strong anisotropy in their physical properties, with the c-axis of the orthorhombic cell being the easy magnetization and high electrical-conductivity direction. The magnetic structures of Tb11Ni4In9andHo11Ni4In9, which have multiple magnetic orderings, have been investigated by neutron diffraction. The complex magnetic behavior found in these phases is a result of the competing ferrimagnetic (along the c-axis) and antiferromagnetic (on the a - b plane) orderings of the five R sublattices.

  7. Superdeformation studies in {sup 150}Tb and {sup 153}Ho

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Crowell, B.

    1995-08-01

    There are now over 40 superdeformed (SD) bands known in the A {approximately} 150 region and in most cases the properties of these bands are understood in terms of single-particle excitations in the absence of pairing. By continuing the search for new SD bands we hope to gain insight into (1) the ordering of the proton and neutron orbitals near the Fermi surface in the SD well, (2) the effects that the alignment of those orbitals has on the moments of inertia, and (3) the collective excitations in the SD well. For {sup 150}Tb, which is one proton and one neutron away from the SD doubly-magic nucleus {sup 152}Dy, it should be possible to study SD bands based on both proton and neutron hole excitations. By adding one proton to the {sup 152}Dy nucleus (i.e. {sup 153}Ho) proton excitations above the Z = 66 shell gap can be studied. These excitations are important as calculations suggested that the proton intruder orbital N = 7 might become occupied. Interactions between this orbital and a N = 5 level may result in softness towards octupole vibrations. High spin states in {sup 150}Th and {sup 153}Ho were populated using the {sup 124}Sn({sup 31}P,5n) and {sup 120}Sn({sup 37}Cl,4n) reactions, respectively. In both cases the early implementation phase of Gammasphere was used to detect the decay gamma rays and over 1 x 10{sup 9} triple and higher fold coincidence events were recorded. In {sup 150}Tb, the data analysis is complete and two new SD bands were identified. The fact that Im{sup (2)} moments of inertia are sensitive to the specific high-N intruder content of the SD bands was used to suggest configurations for the two new bands. A paper reporting these results is being prepared. For {sup 153}Ho, data analysis is still in its early stages.

  8. Brillouin Light Scattering study of the rotatable magnetic anisotropy in exchange biased bilayers of Ni81 Fe19 Ir20 Mn80

    NASA Astrophysics Data System (ADS)

    Rodríguez, Roberto; Oliveira, Alexandre; Estrada, Francisco; Santos, Obed; Azevedo, Antonio; Rezende, Sergio

    It is known that when a ferromagnet (FM) is in atomic contact with an antiferromagnet (AF) the exchange coupling between the FM and AF spins at the interface induces a unidirectional anisotropy in the ferromagnetic film. This effect is known as exchange bias (EB). Despite the large amount of research on this topic there are still several aspects of the EB mechanism that are not well understood. One of this aspects is the origin of the rotatable anisotropy in polycrystalline AFs. By means of Brillouin Light Scattering (BLS) measurements, we investigated the dependence of the rotatable anisotropy field HRA and exchange field HE with the magnitude of the external magnetic field (Ho) in FM/AM bilayers of Ni81Fe19(10nm)/Ir20Mn80(tAF) . We developed an algorithm to numerically fit the in-plane angular dependence of the magnon frequency, at a fixed value of Ho measured by BLS. From the fit parameters we were able to investigate HRA and HE dependency on Ho. The results reveal that HRA value depends on Ho, so we argue that AF grain distribution at the interface is partially modified by the applied field strength. Contrary to this, the relation between HE and Ho is not straightforward, remaining constant at high values of Ho.

  9. Auxin 2012: a rich mea ho'oulu.

    PubMed

    Strader, Lucia C; Nemhauser, Jennifer L

    2013-03-01

    In December 2012, scientists from around the world gathered in Waikoloa, Hawaii for 'Auxin 2012', a meeting organized by Paula McSteen (University of Missouri, USA), Ben Scheres (Utrecht University, The Netherlands) and Yunde Zhao (University of California, San Diego, USA). At the meeting, participants discussed the latest advances in auxin biosynthesis, transport and signaling research, in addition to providing context for how these pathways intersect with other aspects of plant physiology and development. Fittingly, the meeting began with a traditional Hawaiian ceremony that recognized the centrality of the harvest of plant life ('mea ho'oulu' in Hawaiian) for continued human survival.

  10. Chaplygin gas Hořava-Lifshitz quantum cosmology

    NASA Astrophysics Data System (ADS)

    Ardehali, Hossein; Pedram, Pouria

    2016-02-01

    In this paper, we study the Chaplygin gas Hořava-Lifshitz quantum cosmology. Using Schutz formalism and Arnowitt-Deser-Misner decomposition, we obtain the corresponding Schrödinger-Wheeler-DeWitt equation. We obtain exact classical and quantum mechanical solutions and construct wave packets to study the time evolution of the expectation value of the scale factor for two cases. We show that unlike classical solutions and upon choosing appropriate initial conditions, the expectation value of the scale factor never tends to the singular point which exhibits the singularity-free behavior of the solutions in the quantum domain.

  11. Ho:YLF Laser Pumped by TM:Fiber Laser

    NASA Astrophysics Data System (ADS)

    Mizutani, Kohei; Ishii, Shoken; Itabe, Toshikazu; Asai, Kazuhiro; Sato, Atsushi

    2016-06-01

    A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser is described. A ring resonator of 3m length is adopted for the oscillator. The laser is a master oscillator and an amplifier system. It is operated at high repetition rate of 200-5000 Hz in room temperature. The laser outputs were about 9W in CW and more than 6W in Q-switched operation. This laser was developed to be used for wind and CO2 measurements.

  12. An Efficient Single Frequency Ho:YLF Laser for IPDA Lidar Applications

    NASA Technical Reports Server (NTRS)

    Yu, J.; Bai, Y.; Wong, T.; Reithmeier, K.; Petros, M.

    2016-01-01

    A highly efficient, versatile, single frequency 2-micron pulsed laser can be used in a pulsed Differential Absorption Lidar (DIAL) / Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution measurements to investigate sources and sinks of CO2. For a direct detection IPDA lidar, the desired 2 ?m Ho:YLF laser should generate 30-40 mJ pulses at the repetition rate of 100 to 200 Hz, with short pulse length (<100 ns) and better than 2% wall plug efficiency. A Tm fiber laser in-band pumped Ho:YLF laser has been developed to meet this technical challenge. This Ho:YLF laser is designed in a four mirror ring resonator with bow tie configuration, which helps to obtain high beam quality. It is end-pumped by a 40 W linearly polarized Tm fiber laser at 1.94µm. The resonator length is 1.10 meters with output coupler reflectivity at 45%. The laser crystal size is 3 x 3 x 60 mm (w, h, l) with a doping concentration of 0.5% Holmium. The laser beam and pump beam are mode-matched in the active medium. Thus, the pump and laser beams have the same confocal parameters. Mode-matching is also helpful for operating the laser in a single transverse mode. The laser beam waist is slightly less than 0.5 mm at the center of the laser crystal. Based on quasi-four level modeling, pump absorption and saturation depend on laser intensity. Laser amplification and saturation also depend on the pump intensity in the crystal. The laser is injection seeded to obtain the single frequency required by an IPDA lidar measurement. The seed beam is entered into the resonator through an output coupler. The laser is mounted on a water cooled optical bench for stable and reliable operation. The size of the optical bench is 22.16 x 9.20 x 1.25 inches. It is stiffened so that the laser can be operated in any orientation of the optical bench. This packaged Ho:YLF laser is designed for either mobile trailer or airborne platform operation. The engineering prototype Ho:YLF laser has

  13. OH, HO2, partially speciated RO2 and OH reactivity measurements over a range of NOx during day and night (Invited)

    NASA Astrophysics Data System (ADS)

    Heard, D. E.; Whalley, L. K.; Gallaway, S.; Stone, D. J.; Ingham, T.; Walker, H.; Evans, M. J.

    2013-12-01

    Measurements will be reported for OH, HO2, partially speciated RO2 (distinguishing smaller alkane related RO2 from larger alkane/alkene/aromatic related RO2) and OH reactivity measurements taken during the ClearfLo campaigns in central London in the winter and summer of 2012. Comparison with calculations from a detailed box model utilising the Master Chemical Mechanism v3.2 tested our ability to reproduce radical levels, and enabled detailed radical budgets to be determined, highlighting for example the important role of the photolysis of nitrous acid and carbonyl species as radical sources. Speciation of RO2 enabled the break-down of ozone production from different classes of VOCs to be calculated directly, and clear differences in the contribution from different types of RO2 were seen during warmer and cooler periods. Comparison of the total calculated chemical O3 production with observations showed that most of the ozone production observed was generated locally. The missing OH reactivity was greatest during morning and evening rush hours, with good agreement at other times. Long-term seasonal measurements of OH and HO2 radicals in the tropical marine boundary layer at the Cape Verde Atmospheric Observatory were reported in a recent publication [1] and here comparisons will be reported with both box model calculations utilising the Master Chemical Mechanism and the three-dimensional global chemical transport model GEOS-Chem. Both approaches result in over-predictions of OH and HO2 suggesting an incomplete description of sinks. In the box model bromine/iodine chemistry increases OH by ~10%, whereas the global model incorporating bromine chemistry decreases OH by ~ 5%. In the global model the impact of O3 destruction from bromine chemistry (and hence reduction of OH) is greater than the increase in OH from changes in HOx partitioning, whereas in the box model O3 is constrained to measurements, and hence the impact of halogens on OH can only derive from HOx

  14. Diurnal HO2 cycles at clean air and urban sites in the troposphere

    NASA Technical Reports Server (NTRS)

    Hard, T. M.; Chan, C. Y.; Mehrabzadeh, A. A.; O'Brien, R. J.

    1992-01-01

    HO2 concentrations at two Oregon sites were determined for continuous periods of 36 to 48 hours, using fluorescence assay with gas expansion. At the sea level coastal site, NNW winds prevailed during daytime, and a point measurement of very low total nonmethane hydrocarbon concentration indicated the presence of remote tropospheric air of oceanic origin. At the urban site, HO2 was determined during moderately low ozone pollution levels. At both sites, maximum daily (HO2) was in the range of 1-2 x 10 exp 8/cu cm under clear-sky conditions, with an estimated overall uncertainty of 40 percent. HO2 was detected by continuous low-pressure sampling with flowing chemical conversion to HO, which was detected by laser-excited fluorescence. The instrumental response to HO2 was calibrated by the self-decay of HO2 at atmospheric pressure. Interference in the measured daytime HO2 concentrations by RO2 was estimated at less than 20 percent.

  15. HoCP 04-838 – A new sugarcane variety for Louisiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 04-838 was released to the Louisiana sugar industry on May 3, 2011 by the Agricultural Research Service of the United States Department of Agriculture in cooperation with the Louisiana State University Agricultural Center, and the American Sugar Cane League of the U.S.A., Inc. HoCP 04-838 re...

  16. Intense red upconversion emission of Yb/Tm/Ho triply-doped tellurite glasses.

    PubMed

    Zhan, Huan; Zhou, Zhiguang; He, Jianli; Lin, Aoxiang

    2012-05-20

    By conventional melting and quenching methods, 3Yb2O3-0.2Tm2O3-xHo2O3 (wt%, x=0.2~1.2) was doped into an easily fiberized tellurite glass with composition of 78TeO2-10ZnO-12Na2O (mol%) to form YTH-TZN78 glasses. Under 976 nm excitation, the direct sensitizing effect of Yb ions (Yb→Ho) and indirect sensitizing and self-depopulating effects of Tm ions (Yb→Tm→Ho) were found to present intense red upconversion emission at 657 nm (Red, Ho:5F5→5I8) and were responsible for the absence of the usually observed 484 nm emission (Blue, Tm:1G4→3H36). Regardless of the dopant concentration of Ho ions, the intensity of the red emission at 657 nm (Red, Ho:5F5→5I8) is about three times stronger than that of the green one at 543 nm (Green, Ho:5S2→5I8). For this certain red emission at 657 nm, 0.4 wt% Ho2O3-doped YTH-TZN78 glass was found to present the highest emission intensity and is therefore determined as a promising active tellurite glass for red fiber laser development.

  17. Ho 07-613 – A potential new sugarcane variety for Louisiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The clone Ho 07-613 will be up for release to Louisiana sugarcane farmers in May of 2014. This potential new variety is a joint release of the United States Department of Agriculture, the Louisiana State University Agricultural Center, and the American Sugar Cane League of the U.S.A., Inc. Ho 07-613...

  18. Gravitational collapse in Hořava-Lifshitz theory

    NASA Astrophysics Data System (ADS)

    Greenwald, Jared; Lenells, Jonatan; Satheeshkumar, V. H.; Wang, Anzhong

    2013-07-01

    We study gravitational collapse of a spherical fluid in nonrelativistic general covariant theory of the Hořava-Lifshitz gravity with the projectability condition and an arbitrary coupling constant λ, where |λ-1| characterizes the deviation of the theory from general relativity in the infrared limit. The junction conditions across the surface of a collapsing star are derived under the (minimal) assumption that the junctions be mathematically meaningful in terms of distribution theory. When the collapsing star is made of a homogeneous and isotropic perfect fluid, and the external region is described by a stationary spacetime, the problem reduces to the matching of six independent conditions. If the perfect fluid is pressureless (a dust fluid), it is found that the matching is also possible. In particular, in the case λ=1, the external spacetime is described by the Sch-(anti-)de Sitter solution written in Painlevé-Gullstrand coordinates. In the case λ≠1, the external spacetime is static but not asymptotically flat. Our treatment can be easily generalized to other versions of Hořava-Lifshitz gravity or, more generally, to any theory of higher-order derivative gravity.

  19. Containment-enhanced Ho:YAG photofragmentation of soft tissues

    NASA Astrophysics Data System (ADS)

    Christens-Barry, William A.; Guarnieri, Michael; Carson, Benjamin S.

    1998-01-01

    Laser surgery of soft tissue can exploit the power of brief, intense pulses of light to cause localized disruption of tissue with minimal effect upon surrounding tissue. In particular, studies of Ho:YAG laser surgery have shown that the effects of cavitation upon tissues and bone depend upon the physical composition of structures in the vicinity of the surgical site. For photofragmentation of occluding structures within catheters and other implant devices, it is possible to exploit the particular geometry of the catheter to amplify the effects of photofragmentation beyond those seen in bulk tissue. A Ho:YAG laser was used to photofragment occlusive material (tissue and tissue analogs) contained in glass capillary tubing and catheter tubing of the kind used in ventricular shunt implants for the management of hydrocephalus. Occluded catheters obtained from patient explants were also employed. Selection of operational parameters used in photoablation and photofragmentation of soft tissue must consider the physical composition and geometry of the treatment site. In the present case, containment of the soft tissue within relatively inelastic catheters dramatically alters the extent of photofragmentation relative to bulk (unconstrained) material. Our results indicate that the disruptive effect of cavitation bubbles is increased in catheters, due to the rapid displacement of material by cavitation bubbles comparable in size to the inner diameter of the catheter. The cylindrical geometry of the catheter lumen may additionally influence the propagation of acoustic shock waves that result from the collapse of the condensing cavitation bubbles.

  20. Itinerant and localized magnetization dynamics in antiferromagnetic Ho

    SciTech Connect

    Rettig, L.; Dornes, C.; Thielemann-Kuhn, N.; Pontius, N.; Zabel, H.; Schlagel, D. L.; Lograsso, T. A.; Chollet, M.; Robert, A.; Sikorski, M.; Song, S.; Glownia, J. M.; SchuBler-Langeheine, C.; Johnson, S. L.; Staub, U.

    2016-06-21

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Here, tuning the x-ray energy to the electric dipole (E1, 2p → 5d) or quadrupole (E2, 2p → 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3–τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f–5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  1. Itinerant and localized magnetization dynamics in antiferromagnetic Ho

    DOE PAGES

    Rettig, L.; Dornes, C.; Thielemann-Kuhn, N.; ...

    2016-06-21

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Here, tuning the x-ray energy to the electric dipole (E1, 2p → 5d) or quadrupole (E2, 2p → 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3–τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flipmore » process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f–5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.« less

  2. Theoretical study of reactions of HO{sub 2} in low-temperature oxidation of benzene

    SciTech Connect

    Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z.; Kennedy, Eric M.; Mackie, John C.

    2010-07-15

    We have generated a set of thermodynamic and kinetic parameters for the reactions involving HO{sub 2} in the very early stages of benzene oxidation at low temperatures using density functional theory (DFT). In particular, we report the rate constants for the reactions of HO{sub 2} with benzene and phenyl. The calculated reaction rate constant for the abstraction of H-C{sub 6}H{sub 5} by HO{sub 2} is found to be in good agreement with the limited experimental values. HO{sub 2} addition to benzene is found to be more important than direct abstraction. We show that the reactions of HO{sub 2} with the phenyl radical generate the propagating radical OH in a highly exoergic reaction. The results presented herein should be useful in modeling the oxidation of aromatic compounds at low temperatures. (author)

  3. Kinetic and Thermochemical Studies of Weakly-Bound HO2 Complexes with Carboxylic acids

    NASA Astrophysics Data System (ADS)

    Zhao, Z.; Nicovich, J. M.; McKee, M. L.; Wine, P. H.

    2008-12-01

    Numerous theoretical and experimental studies have suggested that HO2 radicals are able to form strong hydrogen bonds with some closed-shell species, which can potentially influence our understanding of HO2 chemistry in the upper troposphere and lower stratosphere. In this study, a laser flash photolysis-tunable diode laser absorption spectroscopy technique has been employed to study the formation of HO2 complexes with formic and acetic acids. At low temperatures, equilibration kinetics have been observed, allowing adduct formation and dissociation rate coefficients to be obtained and adduct binding enthalpies to be determined. This is the first experimental study of the HO2-carboxylic acid complexes and the binding energies are in good agreement with the most recent theoretical estimates. The potential role of HO2-RC(O)OH adducts in atmospheric chemistry will be discussed.

  4. Magnetic properties of Ho1- x Lu x B12 solid solutions

    NASA Astrophysics Data System (ADS)

    Gabáni, S.; Gaz̆o, E.; Pristás̆, G.; Takác̆ová, I.; Flachbart, K.; Shitsevalova, N.; Siemensmeyer, K.; Sluchanko, N.

    2013-05-01

    Magnetic properties of the geometrically frustrated antiferromagnet HoB12 (with T N = 7.4 K) modified by substitution of magnetic Ho atoms through non-magnetic Lu ones are presented and discussed. In this case, in Ho1- x Lu x B12 solid solutions, both chemical pressure resulting from different Lu3+ and Ho3+ radii and magnetic dilution take place with increasing Lu content ( x) that change properties of the system. The received results show strong indication for the existence of a quantum critical point near x = 0.9, which separates the region of magnetic order (starting with HoB12 for x = 0) and the nonmagnetic region (ending with superconducting LuB12 for x = 1).

  5. Radical scavenging activity of antioxidants evaluated by means of electrogenerated HO radical.

    PubMed

    Oliveira, Raquel; Geraldo, Dulce; Bento, Fátima

    2014-11-01

    A method is proposed and tested concerning the characterization of antioxidants by means of their reaction with electrogenerated HO radicals in galvanostatic assays with simultaneous O2 evolution, using a Pt anode fairly oxidized. The consumption of a set of species with antioxidant activity, ascorbic acid (AA), caffeic acid (CA), gallic acid (GA) and trolox (T), is described by a first order kinetics. The rate of the processes is limited by the kinetics of reaction with HO radicals and by the kinetics of charge transfer. Information regarding the scavenger activity of antioxidants is obtained by the relative value of the rate constant of the reaction between antioxidants and HO radicals, k(AO,HO)/k(O2). The number of HO radicals scavenged per molecule of antioxidant is also estimated and ranged from 260 (ascorbic acid) to 500 (gallic acid). The method is applied successfully in the characterization of the scavenger activity of ascorbic acid in a green-tea based beverage.

  6. A Total Organic Aqueous Redox Flow Battery Employing Low Cost and Sustainable Methyl Viologen Anolyte and 4-HO-TEMPO Catholyte

    SciTech Connect

    Liu, Tianbiao L.; Wei, Xiaoliang; Nie, Zimin; Sprenkle, Vincent L.; Wang, Wei

    2016-02-04

    The worldwide increasing energy demands and rising CO2 emissions motivate a search of new technologies to take advantage of renewable energy such as solar and wind. Rechargeable redox flow batteries (RFBs) with their high power density, high energy efficiency, scalability (up to MW and MWh), and safety features are one suitable option for integrating such energy sources and overcoming their intermittency. Source limitation and forbidden high system costs of current RFBs technologies impede wide implementation. Here we report a total organic aqueous redox flow battery (OARFB), using low cost and sustainable MV (anolyte) and 4-HO-TEMPO (catholyte), and benign NaCl supporting electrolyte. The electrochemical properties of the organic redox active materials were studied using cyclic voltammetry and rotating disk electrode voltammetry. The MV/4-HO-TEMPO ARFB has an exceptionally high cell voltage, 1.25 V. Prototypes of the organic ARFB can be operated at high current densities ranging from 20 to 100 mA/cm2, and deliver stable capacity for 100 cycles with nearly 100% coulombic efficiency. The overall technical characters of the MV/4-HO-TEMPO ARFB are very attractive for continuous technic development.

  7. Controllable synthesis and up-conversion properties of tetragonal BaYF5:Yb/Ln (Ln=Er, Tm, and Ho) nanocrystals.

    PubMed

    Niu, Na; Yang, Piaoping; Liu, Yanchao; Li, Chunxia; Wang, Dong; Gai, Shili; He, Fei

    2011-10-15

    The nanocrystals (NCs) of tetragonal barium yttrium fluoride (BaYF(5)) doped 1 mol% Ln(3+) (Ln=Er, Tm, Ho) and 20 mol% Yb(3+) with different morphologies and sizes have been successfully synthesized through a facile hydrothermal method. The influences of pH values of the initial solution and fluorine sources on the final structure and morphology of the products have been well investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the size, structure and morphology of these samples prepared at different conditions. And it is found that BaYF(5):Yb/Ln NCs prepared at pH value of 10 using NaBF(4) as F(-) source have a uniform spherical morphology with average diameter of 25 nm. Additionally, the up-conversion (UC) properties of Yb/Er, Yb/Tm, and Yb/Ho doped BaYF(5) nanoparticles were also discussed. Under 980 nm laser excitation, the BaYF(5):Yb/Er, BaYF(5):Yb/Tm, and BaYF(5):Yb/Ho NCs exhibit green, whitish blue, and yellow green UC luminescence, respectively. The luminescence mechanisms for the doped lanthanide ions were thoroughly analyzed.

  8. Energy transfer and lasing in LiYbF4:Ho, LiYbF4:Ho,Tm, and KYb(WO4)3 crystals

    NASA Astrophysics Data System (ADS)

    Sandulenko, Alexander V.; Sandulenko, V. A.; Tkachuk, Alexandra M.; Titov, Alexandre N.; Reiterov, V. M.; Ivanov, V. N.

    1998-12-01

    We have studied both theoretically and experimentally the energy transfer processes in YbLiF4:Ho3+ (0.4%) and YbLiF4:Ho3+ (0.4%),Tm3+ (10%) crystals and in the series of crystals KYb(WO4)2:Tm3+,Ho3+ (0.4%) with the thulium concentration 5; 10; and 20%. The population kinetics of the 5I7 holmium level was studied under the 1.047 micrometers Q-switched YLF:Nd3+ laser pumping. The efficiency of energy transfer processes in Ho3+ doped crystals, codoped with Yb3+ and Tm3+, was demonstrated. With an YbLiF4:Ho3+ (0.4%) laser rod we have obtained lasing at 2.06 micrometers with the total efficiency of 4.8% and the slope efficiency of 11%. In the KYb(WO4)2:Tm3+ (10%),Ho3+ (0.4%) crystal, lasing was obtained for the first time at 2 micrometers . The pumping threshold being approximately 150 mJ, total efficiency 6% and slope efficiency 9.7% was achieved.

  9. White upconversion luminescence in Tm3+/Ho3+/Yb3+ triply doped K+-Na+ ion-exchanged aluminum germanate glass channel waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

    2013-01-01

    Rare-earth ions doped K+-Na+ ion-exchanged aluminum germanate (NMAG) glass channel waveguides have been designed and fabricated. Under 980 nm laser pumping, an intense upconversion white light transmission trace was observed in Tm3+/Ho3+/Yb3+ triply doped NMAG glass channel waveguide and a high-brightness light spot was achieved from the output end of the fiber connected to the waveguide channel. The fluorescent colors were diverse and located within or near the white region in CIE chromaticity diagram under various pumping powers. These admirable results indicate that Tm3+/Ho3+/Yb3+ triply doped NMAG channel waveguide is a promising light source for medical and high-precision processing illumination.

  10. Nanoscale η-NiSi formation via ion irradiation of Si/Ni/Si

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Satpati, Biswarup; Bhukta, Anjan; Dev, B. N.

    2017-01-01

    Nickel monosilicide (NiSi) has emerged as an excellent material of choice for source-drain contact applications below 45 nm node complementary metal-oxide-semiconductor technology. We have investigated the formation of nanoscale NiSi by ion irradiation of Si (˜5 nm)/Ni(˜15 nm)/Si, grown in an ultrahigh vacuum environment. Irradiation was carried out at room temperature with 1 MeV Si+ ions. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed for analysis. With increasing ion fluence, ion beam mixing occurs and more and more Si is incorporated into the Ni layer, and this layer gets amorphized. At an even higher fluence, a recrystallized uniform nickel monosilicide (η-NiSi) layer is formed. Several planar spacings of different Miller indices of η-NiSi have been observed in XRD and TEM. Additionally, an interesting amorphization and recrystallization behavior has been observed in the substrate Si with increasing ion fluence. To our knowledge, this has never been observed in ion irradiation of bare Si in decades of work in this area. This kind of amorphization/recrystallization in Si is apparently Ni-induced. Irradiation displaces Ni and produces a distribution of Ni in amorphized Si. Irradiation at a higher fluence produces two recrystallized Si bands in amorphous Si with concomitant accumulation of Ni at the amorphous/crystalline interfaces. On a further increase in irradiation fluence, the recrystallized Si bands again pass through amorphization and recrystallization. The total thickness of recrystallized, as well as amorphous Si, shows an oscillatory behavior as a function of ion fluence.

  11. 2-.mu.m fiber amplified spontaneous emission (ASE) source

    NASA Technical Reports Server (NTRS)

    Jiang, Shibin (Inventor); Wu, Jianfeng (Inventor); Geng, Jihong (Inventor)

    2007-01-01

    A 2-.mu.m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm.sub.2O.sub.3) or 0.1-5 wt% holmium oxides (Ho.sub.2O.sub.3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.

  12. Cosmological perturbations in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Gao, Xian; Wang, Yi; Brandenberger, R.; Riotto, A.

    2010-04-01

    We study cosmological perturbations in Hořava-Lifshitz Gravity, a recently proposed potentially ultraviolet-complete quantum theory of gravity. We consider scalar metric fluctuations about a homogeneous and isotropic space-time. Starting from the most general metric, we work out the complete second order action for the perturbations. We then make use of the residual gauge invariance and of the constraint equations to reduce the number of dynamical degrees of freedom. At first glance, it appears that there is an extra scalar metric degree of freedom. However, introducing the Sasaki-Mukhanov variable, the combination of spatial metric fluctuation and matter inhomogeneity for which the action in general relativity has canonical form, we find that this variable has the standard time derivative term in the second order action, and that the extra degree of freedom is nondynamical. The limit λ→1 is well behaved, unlike what is obtained when expanding about Minkowski space-time. Thus, there is no strong coupling problem for Hořava-Lifshitz gravity when considering cosmological solutions. We also compute the spectrum of cosmological perturbations. If the potential in the action is taken to be of “detailed balance” form, we find a cancellation of the highest derivative terms in the action for the curvature fluctuations. As a consequence, the initial spectrum of perturbations will not be scale-invariant in a general space-time background, in contrast to what happens when considering Hořava-Lifshitz matter leaving the gravitational sector unperturbed. However, if we break the detailed balance condition, then the initial spectrum of curvature fluctuations is indeed scale-invariant on ultraviolet scales. As an application, we consider fluctuations in an inflationary background and draw connections with the “trans-Planckian problem” for cosmological perturbations. In the special case in which the potential term in the action is of detailed balance form and in which

  13. Sticking of HO2 on fatty acids aggregates

    NASA Astrophysics Data System (ADS)

    Vardanega, Delphine; Briquez, Stéphane; Duflot, Denis; Monnerville, Maurice; Toubin, Céline

    2015-04-01

    Models of atmospheric chemistry are widely used to perform projections of future changes in the chemical composition of the global troposphere, including changes in climate related greenhouse gases and aerosol particles. However, large uncertainties are still associated with the chemistry implemented in these models, which in turn can lead to inaccurate long-term predictions. The proposed work seeks to improve our understanding of the oxidative capacity of the atmosphere, which drives the lifetime of trace gases, and therefore atmospheric composition. Recent measurements [1] of free radicals made in forested environments characterized by low levels of nitrogen oxides (NOx = NO and NO2) indicate that current models of atmospheric chemistry tend to overestimate the concentration of peroxy radicals (HO2 and RO2). An overestimation of peroxy radicals is an important issue since these radicals are the main precursors of the hydroxyl radical (OH), the most important atmospheric oxidant during daytime. This issue could lead to a significant overestimation of the oxidative capacity of the global atmosphere since more than 86% of the Earth surface is covered by forests, oceans, and polar regions. An analysis of this dataset indicates that the missing sink could be due to an underestimation of the rates of RO2+HO2 reactions, and/or the uptake of peroxy radicals onto aerosol particles. A thorough evaluation of scientific studies published in the literature shows that there is a lack of kinetic and mechanistic data to correctly assess the contribution of these two loss pathways of peroxy radicals in low NOx environments. Classical molecular dynamics simulations, using the Gromacs package [2], are performed to study the interaction of HO2 with organic (carboxylic acid) aerosols. The effect of the presence of water molecules on the surface are also be investigated. These calculations provide theoretical values for observable quantities such as uptake and mass accommodation

  14. Resonantly pumped high efficiency Ho:YAG laser.

    PubMed

    Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

    2012-11-20

    High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

  15. BRIEF REVIEW Hořava-Lifshitz cosmology: a review

    NASA Astrophysics Data System (ADS)

    Mukohyama, Shinji

    2010-11-01

    Here we review the basic construction and cosmological implications of a power-counting renormalizable theory of gravitation, recently proposed by Hořava. We explain that (i) at low energy this theory does not exactly recover general relativity but instead mimics general relativity plus dark matter; (ii) higher spatial curvature terms allow bouncing and cyclic universes as regular solutions; (iii) the anisotropic scaling with the dynamical critical exponent z = 3 solves the horizon problem and leads to scale-invariant cosmological perturbations even without inflation. We also comment on issues related to an extra scalar degree of freedom called scalar graviton. In particular, for spherically-symmetric, static, vacuum configurations we prove non-perturbative continuity of the λ → 1 + 0 limit, where λ is a parameter in the kinetic action and general relativity has the value λ = 1. We also derive the condition under which linear instability of the scalar graviton does not show up.

  16. Migration and employment in Ho Chi Minh City.

    PubMed

    Truong Si Anh; Gubry, P; Vu Thi Hong; Huguet, J W

    1996-06-01

    This article presents findings from a survey of migrants conducted during September 1994 in Ho Chi Minh City, Vietnam. The sample includes 19,019 households in 34 residence blocks selected from the 17 districts that comprise the most populated areas of the city. 704 migrants and 296 nonmigrant households completed the basic demographic and socioeconomic questionnaire. One migrant and one nonmigrant completed a detailed questionnaire. Migrants are identified as those who migrated to the city after April 1984. Migrants are divided into those moving during 1984-89 and during 1990-94. The average annual rate of growth in population during the census years 1979-89 was 1.87% and during 1989-94 was 3.5%. Growth during 1989-94 was 1.6% due to natural increase and 1.9% due to net migration. 43% of population growth was due to natural increase and 57% was from net migration. Migration to large cities, such as Ho Chi Minh City, was stimulated by employment opportunities in the private sector. There were more female migrants in both study periods, and the proportion of females increased in the more recent past. About 15% of female migrants aged over 13 years were students and 58% were in the labor force. Most migrants were aged 15-29 years (41% during 1984-89 and 53% during 1990-94). Only 31% of nonmigrants were aged 15-29 years. About 33% of migrants originated from the Mekong River Delta in the south; 20% originated from the Red River Delta and Hanoi region; and 20% came from the Central Coast. Over time, the proportion of migrants from the coast increased and that from the Red River Delta decreased. Migrants and nonmigrants shared similar unemployment and economic activity rates. However, twice the proportion of migrants aged over 13 years were attending school. The author presents the evidence for the influence of urban economic policies on migration, specifically female migration.

  17. HO endonuclease-induced recombination in yeast meiosis resembles Spo11-induced events.

    PubMed

    Malkova, A; Klein, F; Leung, W Y; Haber, J E

    2000-12-19

    In meiosis, gene conversions are accompanied by higher levels of crossing over than in mitotic cells. To determine whether the special properties of meiotic recombination can be attributed to the way in which Spo11p creates double-strand breaks (DSBs) at special hot spots in Saccharomyces cerevisiae, we expressed the site-specific HO endonuclease in meiotic cells. We could therefore compare HO-induced recombination in a well-defined region both in mitosis and meiosis, as well as compare Spo11p- and HO-induced meiotic events. HO-induced gene conversions in meiosis were accompanied by crossovers at the same high level (52%) as Spo11p-induced events. Moreover, HO-induced crossovers were reduced 3-fold by a msh4Delta mutation that similarly affects Spo11p-promoted events. In a spo11Delta diploid, where the only DSB is made by HO, crossing over was significantly higher (27%) than in mitotic cells (HO-induced gene conversion tract lengths are shorter in meiotic than in mitotic cells. We conclude that a hallmark of meiotic recombination, the production of crossovers, is independent of the nature of Spo11p-generated DSBs at special hotspots, but some functions of Spo11p are required in trans to achieve maximum crossing over.

  18. High-power graphene mode-locked Tm/Ho co-doped fiber laser with evanescent field interaction.

    PubMed

    Li, Xiaohui; Yu, Xuechao; Sun, Zhipei; Yan, Zhiyu; Sun, Biao; Cheng, Yuanbing; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2015-11-16

    Mid-infrared ultrafast fiber lasers are valuable for various applications, including chemical and biomedical sensing, material processing and military applications. Here, we report all-fiber high-power graphene mode-locked Tm/Ho co-doped fiber laser at long wavelength with evanescent field interaction. Ultrafast pulses up to 7.8 MHz are generated at a center wavelength of 1879.4 nm, with a pulse width of 4.7 ps. A graphene absorber integrated with a side-polished fiber can increase the damage threshold significantly. Harmonics mode-locking can be obtained till to the 21(th) harmonics at a pump power of above 500 mW. By using one stage amplifier in the anomalous dispersion regime, the laser can be amplified up to 450 mW and the narrowest pulse duration of 1.4 ps can be obtained simultaneously. Our work paves the way to graphene Tm/Ho co-doped mode-locked all-fiber master oscillator power amplifiers as potentially efficient and economic laser sources for high-power laser applications, such as special material processing and nonlinear optical studies.

  19. Solvothermal synthesis and upconversion properties of YF3:Ln (Ln = Yb/Er,Yb/Tm,Yb/Ho) nanoparticles.

    PubMed

    He, Fei; Wang, Lin; Niu, Na; Gai, Shili; Wang, Yan; Yang, Piaoping

    2014-05-01

    YF3 nanoparticles with different morphology, dimension, and dispersity have been synthesized through a simple solvothermal method by using n-octanol and n-octylamine as a mixed solvent and lanthanide acetylacetonate as the RE3+ source. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrum (EDS) and up-conversion (UC) photoluminescence spectra were used to characterize the samples. The results reveal that the morphology and dimension of the as-prepared nanoparticles can be regulated by adjusting n-octanol/ n-octylamine volume ratio in the initial system. Besides, by doping with different rare-earth elements (Yb/Er, Yb/Tm, Yb/Ho), the as-prepared YF3 samples can emit characteristic green, blue, and yellow light under 980 nm laser excitation. Additionally, when being co-doped with the activator ion-pairs Tm/Er and Tm/Ho, the color of the emission light can be further modified by adjusting the Yb3+ ion content.

  20. High-power graphene mode-locked Tm/Ho co-doped fiber laser with evanescent field interaction

    PubMed Central

    Li, Xiaohui; Yu, Xuechao; Sun, Zhipei; Yan, Zhiyu; Sun, Biao; Cheng, Yuanbing; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2015-01-01

    Mid-infrared ultrafast fiber lasers are valuable for various applications, including chemical and biomedical sensing, material processing and military applications. Here, we report all-fiber high-power graphene mode-locked Tm/Ho co-doped fiber laser at long wavelength with evanescent field interaction. Ultrafast pulses up to 7.8 MHz are generated at a center wavelength of 1879.4 nm, with a pulse width of 4.7 ps. A graphene absorber integrated with a side-polished fiber can increase the damage threshold significantly. Harmonics mode-locking can be obtained till to the 21th harmonics at a pump power of above 500 mW. By using one stage amplifier in the anomalous dispersion regime, the laser can be amplified up to 450 mW and the narrowest pulse duration of 1.4 ps can be obtained simultaneously. Our work paves the way to graphene Tm/Ho co-doped mode-locked all-fiber master oscillator power amplifiers as potentially efficient and economic laser sources for high-power laser applications, such as special material processing and nonlinear optical studies. PMID:26567536

  1. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair.

    PubMed

    Cremers, Niels A J; Suttorp, Maarten; Gerritsen, Marlous M; Wong, Ronald J; van Run-van Breda, Coby; van Dam, Gooitzen M; Brouwer, Katrien M; Kuijpers-Jagtman, Anne Marie; Carels, Carine E L; Lundvig, Ditte M S; Wagener, Frank A D T G

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  2. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair

    PubMed Central

    Cremers, Niels A. J.; Suttorp, Maarten; Gerritsen, Marlous M.; Wong, Ronald J.; van Run-van Breda, Coby; van Dam, Gooitzen M.; Brouwer, Katrien M.; Kuijpers-Jagtman, Anne Marie; Carels, Carine E. L.; Lundvig, Ditte M. S.; Wagener, Frank A. D. T. G.

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  3. Mechanical properties, in vitro corrosion and biocompatibility of newly developed biodegradable Mg-Zr-Sr-Ho alloys for biomedical applications

    PubMed Central

    Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

    2016-01-01

    Our previous studies have demonstrated that Mg-Zr-Sr alloys can be anticipated as excellent biodegradable implant materials for load-bearing applications. In general, rare earth elements (REEs) are widely used in magnesium (Mg) alloys with the aim of enhancing the mechanical properties of Mg-based alloys. In this study, the REE holmium (Ho) was added to an Mg-1Zr-2Sr alloy at different concentrations of Mg1Zr2SrxHo alloys (x = 0, 1, 3, 5 wt. %) and the microstructure, mechanical properties, degradation behaviour and biocompatibility of the alloys were systematically investigated. The results indicate that the addition of Ho to Mg1Zr2Sr led to the formation of the intermetallic phases MgHo3, Mg2Ho and Mg17Sr2 which resulted in enhanced mechanical strength and decreased degradation rates of the Mg-Zr-Sr-Ho alloys. Furthermore, Ho addition (≤5 wt. %) to Mg-Zr-Sr alloys led to enhancement of cell adhesion and proliferation of osteoblast cells on the Mg-Zr-Sr-Ho alloys. The in vitro biodegradation and the biocompatibility of the Mg-Zr-Sr-Ho alloys were both influenced by the Ho concentration in the Mg alloys; Mg1Zr2Sr3Ho exhibited lower degradation rates than Mg1Zr2Sr and displayed the best biocompatibility compared with the other alloys. PMID:27553403

  4. Preparation, characterization and photocatalytic properties of Ho doped ZnO nanostructures synthesized by sonochemical method

    NASA Astrophysics Data System (ADS)

    Phuruangrat, Anukorn; Yayapao, Oranuch; Thongtem, Titipun; Thongtem, Somchai

    2014-03-01

    The three-dimensional flowerlike undoped and Ho doped ZnO microstructure was successfully synthesized by a sonochemical method. The morphologies and structures of the phase were characterized by the analyses of XRD, SEM and TEM. The flower-like structure composed of numerous one-dimensional hexagonal nanoprisms ZnO and Ho doped ZnO were revealed as hexagonal crystal structure with exposure (0 0 1) facet. The Ho doped ZnO exhibited a relatively higher photocatalytic activity than the pure ZnO in the degradation of methylene blue under UV light.

  5. Path-integral molecular dynamics simulations for water anion clusters (HO)5- and (DO)5-

    NASA Astrophysics Data System (ADS)

    Takayanagi, Toshiyuki; Yoshikawa, Takehiro; Motegi, Haruki; Shiga, Motoyuki

    2009-11-01

    Quantum path-integral molecular dynamics simulations have been performed for the (HO)5- and (DO)5- anion clusters on the basis of a semiempirical one-electron pseudopotential-polarization model. Due to larger zero-point vibrational amplitudes for H atoms than that of D atoms, hydrogen-bond lengths in the (HO)5- cluster are slightly larger than those in (DO)5-. The distribution of the vertical detachment energies for (HO)5- also show a broader feature than that for (DO)5-. The present PIMD simulations thus demonstrate the importance of nuclear quantum effects in water anion clusters.

  6. Are models of catalytic removal of O3 by HO(x) accurate? Constraints from in situ measurements of the OH to HO2 ratio

    NASA Astrophysics Data System (ADS)

    Cohen, R. C.; Wennberg, P. O.; Stimpfle, R. M.; Koplow, J.; Anderson, J. G.; Fahey, D. W.; Woodbridge, E. L.; Keim, E. R.; Gao, R.; Proffitt, M. H.

    1994-11-01

    Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60 deg N. A method is presented for interpreting the rates of chemical transformations that (1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2; and (2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of 'missing chemistry' are strickly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd notrogen in the lower statosphere.

  7. Are models of catalytic removal of O3 by HO(x) accurate? Constraints from in situ measurements of the OH to HO2 ratio

    NASA Technical Reports Server (NTRS)

    Cohen, R. C.; Wennberg, P. O.; Stimpfle, R. M.; Koplow, J.; Anderson, J. G.; Fahey, D. W.; Woodbridge, E. L.; Keim, E. R.; Gao, R.; Proffitt, M. H.

    1994-01-01

    Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60 deg N. A method is presented for interpreting the rates of chemical transformations that (1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2; and (2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of 'missing chemistry' are strickly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd notrogen in the lower statosphere.

  8. Organ doses from hepatic radioembolization with 90Y, 153Sm, 166Ho and 177Lu: A Monte Carlo simulation study using Geant4

    NASA Astrophysics Data System (ADS)

    Hashikin, N. A. A.; Yeong, C. H.; Guatelli, S.; Abdullah, B. J. J.; Ng, K. H.; Malaroda, A.; Rosenfeld, A. B.; Perkins, A. C.

    2016-03-01

    90Y-radioembolization is a palliative treatment for liver cancer. 90Y decays via beta emission, making imaging difficult due to absence of gamma radiation. Since post-procedure imaging is crucial, several theranostic radionuclides have been explored as alternatives. However, exposures to gamma radiation throughout the treatment caused concern for the organs near the liver. Geant4 Monte Carlo simulation using MIRD Pamphlet 5 reference phantom was carried out. A spherical tumour with 4.3cm radius was modelled within the liver. 1.82GBq of 90Y sources were isotropically distributed within the tumour, with no extrahepatic shunting. The simulation was repeated with 153Sm, 166Ho and 177Lu. The estimated tumour doses for all radionuclides were 262.9Gy. Tumour dose equivalent to 1.82GBq 90Y can be achieved with 8.32, 5.83, and 4.44GBq for 153Sm, 166Ho and 177Lu, respectively. Normal liver doses by the other radionuclides were lower than 90Y, hence beneficial for normal tissue sparing. The organ doses from 153Sm and 177Lu were relatively higher due to higher gamma energy, but were still well below 1Gy. 166Ho, 177Lu and 153Sm offer useful gamma emission for post-procedure imaging. They show potential as 90Y substitutes, delivering comparable tumour doses, lower normal liver doses and other organs doses far below the tolerance limit.

  9. Measurement of {sup 63}Ni and {sup 59}Ni by accelerator mass spectrometry using characteristic projectile x-rays

    SciTech Connect

    McAninch, J.E.; Hainsworth, L.J.; Marchetti, A.A.

    1996-05-01

    The long-lived isotopes of nickel ({sup 59}Ni, {sup 63}Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction {sup 63}Cu(n,p){sup 63}Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of {sup 63}Ni(t{sub 1/2} = 100 y) requires the chemical removal of {sup 63}Cu, which is a stable isobar of {sup 63}Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 x 10{sup -8} (Cu/Ni) using the reaction of Ni with carbon monoxide to form the gas Ni(CO){sub 4}. The Ni(CO){sub 4} is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile x-rays, allowing further rejection of remaining {sup 63}Cu. In a demonstration experiment, {sup 63}Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a {sup 252}Cf source. We successfully measured {sup 63}Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 10{sup 12} with quantitative retention of {sup 63}Ni. Detection sensitivity (3{sigma}) was {approximately}20 fg {sup 63}Ni in 1 mg Ni carrier ({sup 63}Ni/Ni {approx} 2 x 10{sup -11}). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for {sup 59}Ni (t{sub 1/2} = 10{sup 5} y).

  10. Wormholes and naked singularities in the complete Hořava theory

    NASA Astrophysics Data System (ADS)

    Bellorín, Jorge; Restuccia, Alvaro; Sotomayor, Adrián

    2014-08-01

    We find the static spherically symmetric solutions (with vanishing shift function) of the complete nonprojectable Hořava theory explicitly, writing the space-time metrics as explicit tensors in local coordinate systems. This completes previous work of other authors who have studied the same configurations. The solutions depend on the coupling constant α of the (∂ilnN)2 term. The λ=1/3 case of the theory does not possess any extra mode; hence, the range of α is in principle not limited by the linear stability of any extra mode. We study the full range of α, both in the positive and negative sectors. We find the same wormhole solutions and naked singularities that were found for the Einstein-aether theory in a sector of the space of α. There also arise wormholes in other sectors of α. Our coordinate systems are valid at the throats of the wormholes. We also find the perturbative solutions for small α. We give this version of the solutions directly on the original radial coordinate r, which is particularly suitable for representing the exterior region of solutions with localized sources.

  11. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganga, B. G.; Santhosh, P. N.; Thomas, P. John

    2012-06-01

    Ni and Cu-Ni nanoparticles were prepared by solution phase method and crystal phase was identified by XRD. SEM and EDX were used to analyze morphology and elemental composition of nanoparticles. Magnetic measurements indicate that Ni nanoparticles are superparamagnetic at room temperature and blocking temperature is around 103 K. Ferromagnetism is observed in the case of Cu-Ni nanoparticles with decrease in magnetization compared to Ni nanoparticles.

  12. Kinetics of the reactions of HBr with O3 and HO2: The yield of HBr from HO2 + BrO

    NASA Technical Reports Server (NTRS)

    Mellouki, Abdelwahid; Talukdar, Ranajit K.; Howard, Carleton J.

    1994-01-01

    An upper limit on the yield of HBr from reaction (R1) (HO2 + BrO yields products) has been determined by measuring an upper limit for the rate coefficient of the reverse reaction (R1') (HBr + O3 yields HO2 + BrO). The limits measured at 300 and 441 K were extrapolated to low temperatures to determine that the yield of HBr from reaction (R1) is negligible throughout the stratosphere (less than 0.01% of k(sub 1)). An upper limit for the rate coefficient of the reaction of HO2 with HBr was also determined to be very low less than or equal to 3 x 10(exp -17) cu cm/molecule/sec at 300 K and less than or equal to 3 x 10(exp -16) cu cm/molecule/sec at 400 K. The implications of these results to stratospheric chemistry are discussed.

  13. Potential Energy Surfaces for the Reactions of HO2 Radical with CH2O and HO2 in CO2 Environment.

    PubMed

    Masunov, Artëm E; Atlanov, Arseniy A; Vasu, Subith S

    2016-10-06

    We report on potential energies for the transition state, reactant, and product complexes along the reaction pathways for hydrogen transfer reactions to hydroperoxyl radical from formaldehyde H2CO + HO2 → HCO + H2O2 and another hydroperoxyl radical 2HO2 → H2O2 + O2 in the presence of one carbon dioxide molecule. Both covalently bonded intermediates and weak intermolecular complexes are identified and characterized. We found that reactions that involve covalent intermediates have substantially higher activation barriers and are not likely to play a role in hydrogen transfer kinetics. The van der Waals complexation with carbon dioxide does not affect hydrogen transfer from formaldehyde, but it lowers the barrier for hydroperoxyl self-reaction by nearly 3 kcal/mol. This indicates that CO2 environment is likely to have catalytic effect on HO2 self-reaction, which needs to be included in kinetic combustion mechanisms in supercritical CO2.

  14. Vapor complexation in the CsI-HoI 3 system up to 1300 K and the f ← f hypersensitive transition intensities of Ho(III) in different coordination geometries

    NASA Astrophysics Data System (ADS)

    Papatheodorou, G. N.; Chrissanthopoulos, A.

    2007-04-01

    Electronic absorption spectroscopy is used in the temperature range 850-1300 K, to study the vapor species over molten HoI 3-CsI (1:1), molten CsI and solid HoI 3. Quantitative absorbance measurements are used to calculate the following enthalpies of transition: Δ Hsubl(HoI 3) = 271 ± 3 kJ mol -1, Δ Hvap. (CsHoI 4) = 155 ± 2 kJ mol -1 and Δ Hvap. (CsI) = 151 ± 2 kJ mol -1. The ligand field components of the 5G 6 ← 5I 8 hypersensitive transition of Ho(III) for the three different, all iodide, coordination geometries of HoI 3(g), CsHoI 4(g) and HoI 63- (in molten CsI) have been examined in detail. The molar absorptivities ( ɛ) and oscillator strengths ( f) increase as the coordination decreases from the "octahedral" HoI 63- ( ɛ = 65 L mol -1 cm -1; f = 99 × 10 -6) to the distorted tetrahedral HoI 4- ( ɛ = 235 L mol -1 cm -1; f = 290 × 10 -6) to the trigonal HoI 3 ( ɛ = 390 L mol -1 cm -1; f = 500 × 10 -6). The main factors affecting the hypersensitive transition intensities are the coordination number and symmetry and the ligand polarizability as well as the Boltzmann population effects on the ground state levels which are responsible for the appearance of "hot" bands in the spectra. A C2v symmetry is anticipated for the CsHoI 4(g) with the HoI 4- "tetrahedra" distorted towards a square planar symmetry leading to a structure with a pseudo-like inversion center.

  15. Low energy spin dynamics in the spin ice, Ho2Sn2O7

    SciTech Connect

    Ehlers, Georg; Huq, Ashfia; Diallo, Souleymane Omar; Adriano, Cris; Rule, K; Cornelius, A. L.; Fouquet, Peter; Pagliuso, P G; Gardner, Jason

    2012-01-01

    The magnetic properties of Ho{sub 2}Sn{sub 2}O{sub 7} have been investigated and compared to other spin ice compounds. Although the lattice has expanded by 3% relative to the better studied Ho{sub 2}Ti{sub 2}O{sub 7} spin ice, no significant changes were observed in the high temperature properties, T {approx}> 20 K. As the temperature is lowered and correlations develop, Ho{sub 2}Sn{sub 2}O{sub 7} enters its quantum phase at a slightly higher temperature than Ho{sub 2}Ti{sub 2}O{sub 7} and is more antiferromagnetic in character. Below 80 K a weak inelastic mode associated with the holmium nuclear spin system has been measured. The hyperfine field at the holmium nucleus was found to be {approx}700 T.

  16. An Efficient End-Pumped Ho:Tm:YLF Disk Amplifier

    NASA Technical Reports Server (NTRS)

    Yu, Ji-Rong; Petros, Mulugeta; Singh, Upendra N.; Barnes, Norman P.

    2000-01-01

    An efficient diode-pumped, room temperature Ho:Tm:YLF disk amplifier was realized by end-pump configuration. Compared to side pump configuration, about a factor three improvement in system efficiency has been demonstrated.

  17. In vivo analysis of the Saccharomyces cerevisiae HO nuclease recognition site by site-directed mutagenesis.

    PubMed Central

    Nickoloff, J A; Singer, J D; Heffron, F

    1990-01-01

    HO nuclease introduces a specific double-strand break in the mating-type locus (MAT) of Saccharomyces cerevisiae, initiating mating-type interconversion. To define the sequence recognized by HO nuclease, random mutations were produced in a 30-base-pair region homologous to either MAT alpha or MATa by a chemical synthesis procedure. The mutant sites were introduced into S. cerevisiae on a shuttle vector and tested for the ability to stimulate recombination in an assay that mimics mating-type interconversion. The results suggest that a core of 8 noncontiguous bases near the Y-Z junction of MAT is essential for HO nuclease to bind and cleave its recognition site. Other contacts must be required because substrates that contain several mutations outside an intact core reduce or eliminate cleavage in vivo. The results show that HO site recognition is a complex phenomenon, similar to promoter-polymerase interactions. Images PMID:2406563

  18. Spectral and lasing characteristics of 1% Ho:YAG ceramics under intracavity pumping

    SciTech Connect

    Bagayev, S N; Vatnik, S M; Vedin, I A; Kurbatov, P F; Osipov, V V; Shitov, V A; Maksimov, R N; Luk'yashin, K E; Pavlyuk, A A

    2015-01-31

    High-transparency 1% Ho:YAG ceramics with the transmission coefficient of 82% in the IR range at the sample thickness of 1 mm are synthesised from a mixture of the Ho:Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} nanopowders obtained by the laser method. Results of investigations of spectral and lasing characteristics of 1 % Ho:YAG ceramics under intracavity pumping by radiation of a 5% Tm:KLuW disk element are presented. Based on spectral intensity analysis of generation in the 1.8 – 2.1 mm range and on cavity parameters, the estimated lasing slope efficiency for 1% Ho:YAG ceramics is about 40%. (lasers)

  19. Review of magnetic features observed in (A,A')Ni 2B 2C solid solutions

    NASA Astrophysics Data System (ADS)

    Kuznietz, Moshe; Gonçalves, António P.; Almeida, Manuel

    2002-08-01

    The nickel-borocarbides ANi 2B 2C [A=Y, Ln (lanthanide), An(actinide)], crystallizing in the body-centred tetragonal LuNi 2B 2C-type structure, are classified according to the existence or coexistence of superconducting and antiferromagnetic states (AF). The magnetic features observed in polycrystalline (A,A')Ni 2B 2C solid solutions, adopting the same crystal structure, are reviewed and discussed. Published data on the magnetism in (A,Ln)Ni 2B 2C systems (ANi 2B 2C nonmagnetic, A=Y,La,Lu) indicate a gradual rise in the threshold content, x( m), in (Y 1- xLn x)Ni 2B 2C (Ln=Gd,Tb,Dy,Ho,Er) for the establishment of AF states. (A,A')Ni 2B 2C systems with magnetic end compounds show gradual variation in magnetic features when A and A' are both heavy Ln. The behaviour of (A,A')Ni 2B 2C systems of light A (Pr or U) and heavy A' (Dy or Tm) depends on the magnetic structures of the end compounds. In intermediate compositions, incomplete moment compensation in (Pr,Dy)Ni 2B 2C decreases TN, while different moment directions in the end compounds in (U,Dy)Ni 2B 2C lead to a directional frustration of ordered moments. Such a frustration in (U,Tm)Ni 2B 2C is related to different magnetic structures of the end compounds.

  20. Measurement of HOx• production rate due to radon decay in air

    SciTech Connect

    Ding, Huiling

    1993-08-01

    Radon in indoor air may cause the exposure of the public to excessive radioactivity. Radiolysis of water vapor in indoor air due to radon decay could produce (•OH and HO2 •) that may convert atmospheric constituents to compounds of lower vapor pressure. These lower vapor pressure compounds might then nucleate to form new particles in the indoor atmosphere. Chemical amplification was used to determine HOx• production rate in indoor air caused by radon decay. Average HOx• production rate was found to be (4.31±0.07) x 105 HOx• per Rn decay per second (Bq) 3.4 to 55.0% at 22C. This work provided G(HOx•)-value, 7.86±0.13 No./100 eV in air by directly measuring [HOx•] formed from the radiolysis procedure. This G value implies that HOx• produced by radon decay in air might be formed by multiple processes and may be result of positive ion-molecule reactions, primary radiolysis, and radical reactions. There is no obvious relation between HOx• production rate and relative humidity. A laser-induced fluorescence (LIF) system has been used for •OH production rate measurement; it consists of an excimer laser, a dye laser, a frequency doubler, a gaseous fluorescence chamber, and other optical and electronic parts. This system needs to be improved to eliminate the interferences of light scattering and artificial •OH produced from the photolysis of O3/H2O.

  1. Raman and infrared study of 4f electron-phonon coupling in HoVO3

    NASA Astrophysics Data System (ADS)

    Roberge, B.; Balli, M.; Jandl, S.; Fournier, P.; Palstra, T. T. M.; Nugroho, A. A.

    2016-11-01

    First-order Raman scattering and multiphonons are studied in RVO3 (R  =  Ho and Y) as a function of temperature in the orthorhombic and monoclinic phases. Raman spectra of HoVO3 and YVO3 unveil similar features since both compounds have nearly identical R-radii. However, the most important difference lies in the transition temperature involving the V3+ orbitals, the V3+ magnetic moments as well as the crystallographic structure. Particularly, the magnetic and orbital reorientations occur at T N2  =  40 K for HoVO3 instead T N2  =77 K in the case of YVO3. For both systems, anomalous phonon shifts which are related to spin-phonon coupling are observed below the V3+ magnetic ordering temperature (T N1  ≈  110 K) while additional phonon anomalies are exclusively observed in HoVO3 around T *  ≈  15 K. On the other hand, infrared (IR) transmittance measurements as a function of temperature reveal Ho3+5I8  →  5I7 excitations and additional excitations assigned as vibronics. These latter combined with drastic changes in Ho3+5I8  →  5I7 excitations at T N2, are indicative of a strong coupling between the Ho3+ ions and the ligand field. This could explain the large magnetocaloric capacity shown by HoVO3.

  2. The growth of Ho:YAG single crystals by Czochralski method and investigating the formed cores

    SciTech Connect

    Hasani Barbaran, J. Ghani Aragi, M. R.; Javaheri, I.; Baharvand, B.; Tabasi, M.; Layegh Ahan, R.; Jangjo, E.

    2015-12-15

    Ho:YAG single crystals were grown by Czochralski technique, and investigated by the X-ray diffraction (XRD) and optical methods. The crystals were cut and polished in order to observe and analyze their cores. It was found that the deviation of the cores formed in the Czochralski grown Ho:YAG single crystals are resulted from non-symmetrical status of thermal insulation around the Iridium crucible.

  3. 36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

    NASA Astrophysics Data System (ADS)

    Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.

    2017-01-01

    A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

  4. Magnetic properties of R2Co15Al2 compounds with R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm

    NASA Astrophysics Data System (ADS)

    Shen, Bao-gen; Cheng, Zhao-hua; Zhang, Shao-ying; Wang, Jing-yun; Liang, Bing; Zhang, Hong-wei; Zhan, Wen-shan

    1999-03-01

    An investigation of the structure and the magnetic anisotropy of R2Co15Al2 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds has been performed by means of x-ray diffraction and magnetization measurements. X-ray diffraction shows the prepared compounds to be single phase, having the hexagonal Th2Ni17-type structure for R=Y, Ho, Er, and Tm and the rhombohedral Th2Zn17-type structure for R=Ce, Pr, Nd, Gd, Tb, and Dy. Except for the Ce compound, the unit-cell volumes of R2Co15Al2 compounds decrease in accordance with the lanthanide contraction. Substitution of Al for Co in R2Co17 leads to a decrease of the saturation magnetization at 1.5 K and Curie temperature. The exchange-coupling constants JCo-Co and JR-Co have been calculated by using the method based on magnetic ordering temperature. It is found that the JR-Co has a small dependence on the R elements and is almost not affected by the Al substitution. The Ce compound is found to exhibit an anomalous lattice parameter and magnetic characteristic, which are relative to the mixed-valence behavior of the Ce ion. X-ray diffraction measurements on magnetically aligned R2Co15Al2 powders show that the compounds with R=Pr, Nd, Gd, Tb, Dy, and Ho have an easy-plane type of magnetic anisotropy, whereas the compounds with R=Y, Ce, Sm, Er, and Tm exhibit an easy-axis type of magnetic anisotropy at room temperature. The compounds R2Co15Al2 with R=Pr and Ho exhibit a spin-reorientation transition and the spin-reorientation temperature is found to be 531 and 431 K, respectively. A strong uniaxial anisotropy is observed in Sm2Co15Al2 compound with a magnetocrystalline anisotropy field of 84 kOe at room temperature.

  5. Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

    SciTech Connect

    Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.; Engle, Jonathan  W.; Barnhart, Todd  E.; Nickles, Robert  J.; Pollington, Anthony  D.; Kunde, Gerd  J.; Rabin, Michael  W.; Birnbaum, Eva  R.

    2015-04-29

    The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm–3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the 163Ho/165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.

  6. Correlation between magnon and magnetic symmetries of hexagonal RMnO3 (R = Er, Ho, Lu)

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi Minh Hien; Nguyen, Thi Huyen; Chen, Xiang-Bai; Park, Yeonju; Jung, Young Mee; Lee, D.; Noh, T. W.; Cheong, Sang-Wook; Yang, In-Sang

    2016-11-01

    The correlation between the magnon scattering and the magnetic symmetries of hexagonal RMnO3 (R = Er, Ho) thin films and LuMnO3 single crystal was studied through the 2D Correlation Spectroscopy (2D COS) and Perturbation-Correlation Moving Window 2D (PCMW2D) Correlation Spectroscopy which were performed on the temperature-dependent Raman spectra of RMnO3 (R = Er, Ho, Lu). From the Raman spectra, we observed much stronger intensity and more asymmetrical magnon peak in LuMnO3 single crystal than in ErMnO3 and HoMnO3 thin films. While the ratio between magnon and phonon's linewidth of LuMnO3 and HoMnO3 display an anomalous behavior, that ratio of ErMnO3 is almost stable. The result from PCMW2D also supports these results. In addition, our 2D COS analysis showed that there are more overlap peaks in broad four-spin flipping magnon peak in LuMnO3 than that in ErMnO3 and HoMnO3. The differences of hexagonal RMnO3 (R = Er, Ho, Lu) in magnon scattering are very similar to the actual differences of the magnetic symmetries of these compounds. Therefore, we suggest that the magnon scattering of hexagonal RMnO3 is strongly correlated with the magnetic symmetries of these materials.

  7. Measurements of OH and HO2 Radicals and OH Reactivity at Tropical Locations Using Laser-Induced Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Furneaux, K. L.; Whalley, L. K.; Edwards, P.; Goddard, A.; Ingham, T.; Evans, M. J.; Heard, D. E.

    2009-04-01

    included, indicating a missing HOx source. Both OH and HO2 were observed at night. Measurements of HOx at the Cape Verde Atmospheric Observatory (16.9N, 24.9W) were made from May - June 2007 as part of the RHaMBLe (Reactive Halogens in the Marine Boundary Layer) programme. The site is located adjacent to the ocean with an absence of macro algae, providing conditions analogous to open ocean, clean marine air. However, background tropical conditions were not dictated by simple chemistry. Peak OH and HO2 concentrations were 9 × 106 molecule cm-3 and 6 ×108 molecule cm-3, respectively. HO2 was observed at night between 5 - 20 × 106 molecule cm-3. Modelling studies determined oxygenated-VOCs and halogen chemistry to play an important role in HOx chemistry. A comparison of HOx measurements at tropical open ocean and tropical rainforest locations shows that HOx chemistry varies greatly throughout the tropics. Higher HOx sinks in tropical rainforest environments result in a decrease of HOx compared to the tropical open ocean. 1. Lelieveld, J., T. M. Butler, et al. (2008). Atmospheric oxidation capacity sustained by a tropical forest, Nature, 452(7188): 737-740. 2. Martinez, M., Harder, H., et al. (2008). Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements, ACPD, 8, 15491-15536.

  8. Sources of hydroxyl radical in headwater streams from nitrogen-saturated forest.

    PubMed

    Chiwa, Masaaki; Higashi, Naoko; Otsuki, Kyoichi; Kodama, Hiroki; Miyajima, Tohru; Takeda, Kazuhiko; Sakugawa, Hiroshi

    2015-01-01

    Hydroxyl radical (HO) photoformation rate (RHO) was determined in headwater stream samples from nitrogen (N)-saturated forests, (1) to quantify the sources of HO in headwater streams and (2) to evaluate the nitrate NO3(-)-induced enhancement of HO formation in stream water caused by N saturation in forested watersheds. Stream water fulvic acid extracted from the forested watersheds was used to quantify the contribution of dissolved organic matter (DOM) to RHO. The results showed that almost all (97%; 81-109%) RHO sources in our headwater stream samples were quantitatively elucidated; the photolysis of NO3(-) (55%; 34-75%), nitrite [N(III)] (2%; 0.5-5.2%), and DOM-derived HO formation, from which photo-Fenton reactions (18%; 12-26%) and the direct photolysis of fluorescent dissolved organic matter (FDOM) (22%; 10-40%), was successfully separated. FDOM, which accounted for 53% (24-96%) of DOM in total organic carbon bases, was responsible for HO formation in our headwater streams. High NO3(-) leaching caused by N saturation in forested watersheds increased RHO in the headwaters, indicating that N-saturated forest could significantly change photoinduced and biogeochemical processes via enhanced HO formation in downstream water.

  9. Ho-doped Soft Glass Optical Fibers for Coherent Wavelength Sources Above 2 Micron

    DTIC Science & Technology

    2010-12-01

    Politecnico di Torino – Dipartimento di Scienza dei Materiali e Ingegneria Chimica Corso Duca degli Abruzzi, 24 – 10129 Torino Italia tel: +39...Abruzzi, 24 – 10129 Torino Italia tel: +39 011 564 4707 fax: +39 011 564 4699 e-mail: daniel.milanese@polito.it url: www.composites.polito.it...Materiali e Ingegneria Chimica Corso Duca degli Abruzzi, 24 – 10129 Torino Italia tel: +39 011 564 4707 fax: +39 011 564 4699 e-mail

  10. The challenges of water governance in Ho Chi Minh City.

    PubMed

    van Leeuwen, Cornelis J; Dan, Nguyen P; Dieperink, Carel

    2016-04-01

    Population growth, urbanization, pollution, and climate change pose urgent water challenges in cities. In this study, the sustainability of integrated water resources management in Ho Chi Minh City (HCMC) was evaluated using the City Blueprint approach. The City Blueprint is a set of 24 dedicated indicators divided over 8 categories (i.e., water security, water quality, drinking water, sanitation, infrastructure, climate robustness, biodiversity and attractiveness, and governance including public participation). The analysis showed that the rapid increase of water use for urban, industrial, and agricultural activities in HCMC has resulted in depletion of groundwater and severe pollution of both groundwater and surface water. Surface water quality, groundwater quality, biodiversity, and the sanitation of domestic and industrial wastewater are matters that need serious improvement. Current and future water supply in HCMC is at risk. HCMC can cope with it, but the 7 governance gaps as described by the Organisation for Economic Co-operation and Development (OECD) are major obstacles for HCMC. Rainwater harvesting, pollution reduction, as well as wastewater reuse are among the practical options. Wastewater reuse could lower the water stress index to 10%. The window to do this is narrow and rapidly closing as a result of the unprecedented urbanization and economic growth of this region.

  11. Groundwater screening for 940 organic micro-pollutants in Hanoi and Ho Chi Minh City, Vietnam.

    PubMed

    Duong, Hanh Thi; Kadokami, Kiwao; Chau, Hong Thi Cam; Nguyen, Trung Quang; Nguyen, Thao Thanh; Kong, Lingxiao

    2015-12-01

    Groundwater is the main source of drinking water for more than half of the residents of Hanoi (HN). It also provides about one third of the total water demand for residents of Ho Chi Minh City (HCM). However, due to rapid urbanization and frequent discharges of untreated urban wastewater to surface water, freshwater is widely contaminated by man-made chemicals, which may result in groundwater pollution. As part of an ongoing campaign to collect baseline information on the occurrence of organic micro-pollutants (OMPs) in the aquatic environment in Vietnam, 43 water samples were collected from 26 groundwater wells in HN (22) and HCM (4) in September 2013 and August 2014. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) and the resulting chromatograms were screened for 940 OMPs by an automated identification and quantification system (AIQS) within a GC-MS database. A total of 74 compounds were detected, with between 4 and 43 (median 18) compounds found at each site. Overall, contamination levels were low, with over 89 % of the detected concentrations that were less than 0.5 μg L(-1). Results suggest that most of the sampled aquifers have been impacted by non-point source pollution. Most of the contaminants detected are either currently not regulated in drinking water or are present at low levels. A health risk assessment for detected contaminants implied that there were no risks to humans. Since this study was based on a limited number of samples, especially in HCM, further, more detailed studies on the occurrence of OMPs in groundwater in HCM and a full risk assessment of detected contaminants should be prioritized.

  12. Ho:YAG laser irradiation in blood vessel as a vasodilator: ex vivo study

    NASA Astrophysics Data System (ADS)

    Nakatani, E.; Iwasaki, T.; Kaneko, K.; Shimazaki, N.; Arai, T.

    2007-02-01

    We studied Ho:YAG laser irradiation in blood vessel as a vasodilator ex vivo. We thought that the Ho:YAG laser-induced bubble expansion might be able to dilate the vessel because we found the vessel wall expansion after the Ho:YAG laser irradiation, that is steady deformation, in the vessel ex vivo. There have been many reports regarding to the Ho:YAG laser irradiation in the vessel. Most of studies concentrated on the interaction between Ho:YAG laser irradiation and vessel wall to investigate side effect on Ho:YAG laser angioplasty. We proposed to use the Ho:YAG laser-induced bubble expansion as a vasodilator. We studied vasodilation effect of the Ho:YAG laser-induced bubble ex vivo. The flash lamp excited Ho:YAG laser surgical unit (IH102, NIIC, Japan) (λ=2.1μm) was used. The laser energy was delivered by a silica glass fiber (outer diameter: 1000μm, core diameter: 600μm). The laser-induced bubble was generated in the extracted fresh porcine carotid artery with the warmed saline perfusion. The laser energy at the fiber tip was ranging from 170-1300mJ per pulse. Number of the laser irradiation was ranged from 20pulses to 100pulses. The outer diameter of the vessel was observed. To examine the change in mechanical properties of the vessel wall, the stress-strain curve of the laser-irradiated vessel was measured. Birefringence observation and microscopic observation of staining specimen were performed. When the laser energy was set to 1300mJ per pulse, the outer diameter of the vessel after the laser irradiation was expanded by 1.4 times comparing with that of before the laser irradiation and the dilatation effect was kept even at 10minutes after the irradiation. The elasticity modulus of the artery by collagen was changed by the laser irradiation. In the polarized microscopic observation, the brightness of the intimal side of the vessel is increased comparing with that of the normal. We think this brightness increasing may be attributed to birefringence change

  13. Facile Routes to NiF(6)(2)(-), AgF(4)(-), AuF(6)(-), and PtF(6)(-) Salts Using O(2)(+) as a Source of O(2)F in Anhydrous HF.

    PubMed

    Lucier, G. M.; Shen, C.; Elder, S. H.; Bartlett, N.

    1998-07-27

    O(2)(+) salts dissolved in liquid anhydrous hydrogen fluoride (aHF) at 20 degrees C or below oxidize aHF solutions of PtF(6)(2)(-) to PtF(6)(-). The parent base of O(2)(+) salts in aHF (O(2)F((solv))) generated with alkali fluoride is long-lived below -50 degrees C. An aHF solution of O(2)F((solv)) oxidizes Au(III) to Au(V) below -50 degrees C (2O(2)F((solv)) + AuF(4)(-)((solv)) --> AuF(6)(-)((solv)) +2O(2(g))). In situ generation of O(2)F((solv)) (O(2)(+)((solv)) + F(-)((solv)) --> O(2)F((solv))) with AgF(2) or NiF(2) in suspension in the aHF made basic with alkali fluoride gives AgF(4)(-) and NiF(6)(2)(-)salts. Low solubility of AAsF(6)(A = Cs, K) in aHF provides for the metathetical preparation of (O(2))(2)PdF(6) solutions in aHF. Removal of aHF, even at -60 degrees C, results in some O(2) and F(2) loss, to a composition approaching (O(2))PdF(5).

  14. Dual protective role of HO-1 in transplanted liver grafts: A review of experimental and clinical studies

    PubMed Central

    Wang, Chun-Feng; Wang, Zhen-Yu; Li, Ji-Yu

    2011-01-01

    Liver transplantation is considered as the most effective treatment for end-stage liver disease. However, serious complications still exist, particularly in two aspects: ischemia and subsequent reperfusion of the liver, causing postoperative hepatic dysfunction and even failure; and acute and chronic graft rejections, affecting the allograft survival. Heme oxygenase (HO), a stress-response protein, is believed to exert a protective function on both the development of ischemia-reperfusion injury (IRI) and graft rejection. In this review of current researches on allograft protection, we focused on the HO-1. We conjecture that HO-1 may link these two main factors affecting the prognosis of liver transplantations. In this review, the following aspects were emphasized: the basic biological functions of HO-1, its roles in IRI and allograft rejection, as well as methods to induce HO-1 and the prospects of a therapeutic application of HO-1 in liver transplantation. PMID:21912452

  15. TRACE-P OH and HO2 Measurements with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) on the DC-8

    NASA Technical Reports Server (NTRS)

    Brune, William H.; Martinez-Harder, Monica; Harder, Hartwig

    2004-01-01

    The Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) measures OH and HO2 from the NASA DC-8. This instrument detects OH by laser induced fluorescence (LIF) in detection chambers at low pressure and detects HO2 by chemical conversion with NO followed by LIF detection. The demonstrated detection limit (S/N=2, 5 min.) for OH is about 0.005 pptv (1x10(exp 6)/cu cm at 2 km altitude) and for HO2 is 0.05 pptv (1x10(exp 6)/cu cm at 2 km altitude). We will use ATHOS to measure OH, HO2, and HO2/OH during TRACE- P, analyze these results by comparing them against fundamental relationships and computer models, and publish the analyses. TRACE-P HO(x), measurements will help develop a clearer picture of the atmospheric oxidation and 0 3 production that occur as Asian pollution spreads across the Pacific Ocean.

  16. Modeling and predicting pKa values of mono-hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) by local molecular descriptors.

    PubMed

    Yu, Haiying; Wondrousch, Dominik; Yuan, Quan; Lin, Hongjun; Chen, Jianrong; Hong, Huachang; Schüürmann, Gerrit

    2015-11-01

    Hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) are attracting considerable concerns because of their multiple endocrine-disrupting effects and wide existence in environment and organisms. The hydroxyl groups enable these chemicals to be ionizable, and dissociation constant, pKa, becomes an important parameter for investigating their environmental behavior and biological activities. In this study, a new pKa prediction model was developed using local molecular descriptors. The dataset contains 21 experimental pKa values of HO-PCBs and HO-PBDEs. The optimized geometries by ab initio HF/6-31G(∗∗) algorithm were used to calculate the site-specific molecular readiness to accept or donate electron charges. The developed model obtained good statistical performance, which significantly outperformed commercial software ACD and SPARC. Mechanism analysis indicates that pKa values increase with the charge-limited donor energy EQocc on hydroxyl oxygen atom and decrease with the energy-limited acceptor charge QEvac on hydroxyl hydrogen atom. The regression model was also applied to calculate pKa values for all 837 mono-hydroxylated PCBs and PBDEs in each class, aiming to provide basic data for the ecological risk assessment of these chemicals.

  17. Radical chemistry at a rural site (Wangdu) in the North China Plain: observation and model calculations of OH, HO2 and RO2 radicals

    NASA Astrophysics Data System (ADS)

    Tan, Zhaofeng; Fuchs, Hendrik; Lu, Keding; Hofzumahaus, Andreas; Bohn, Birger; Broch, Sebastian; Dong, Huabin; Gomm, Sebastian; Häseler, Rolf; He, Lingyan; Holland, Frank; Li, Xin; Liu, Ying; Lu, Sihua; Rohrer, Franz; Shao, Min; Wang, Baolin; Wang, Ming; Wu, Yusheng; Zeng, Limin; Zhang, Yinsong; Wahner, Andreas; Zhang, Yuanhang

    2017-01-01

    A comprehensive field campaign was carried out in summer 2014 in Wangdu, located in the North China Plain. A month of continuous OH, HO2 and RO2 measurements was achieved. Observations of radicals by the laser-induced fluorescence (LIF) technique revealed daily maximum concentrations between (5-15) × 106 cm-3, (3-14) × 108 cm-3 and (3-15) × 108 cm-3 for OH, HO2 and RO2, respectively. Measured OH reactivities (inverse OH lifetime) were 10 to 20 s-1 during daytime. The chemical box model RACM 2, including the Leuven isoprene mechanism (LIM), was used to interpret the observed radical concentrations. As in previous field campaigns in China, modeled and measured OH concentrations agree for NO mixing ratios higher than 1 ppbv, but systematic discrepancies are observed in the afternoon for NO mixing ratios of less than 300 pptv (the model-measurement ratio is between 1.4 and 2 in this case). If additional OH recycling equivalent to 100 pptv NO is assumed, the model is capable of reproducing the observed OH, HO2 and RO2 concentrations for conditions of high volatile organic compound (VOC) and low NOx concentrations. For HO2, good agreement is found between modeled and observed concentrations during day and night. In the case of RO2, the agreement between model calculations and measurements is good in the late afternoon when NO concentrations are below 0.3 ppbv. A significant model underprediction of RO2 by a factor of 3 to 5 is found in the morning at NO concentrations higher than 1 ppbv, which can be explained by a missing RO2 source of 2 ppbv h-1. As a consequence, the model underpredicts the photochemical net ozone production by 20 ppbv per day, which is a significant portion of the daily integrated ozone production (110 ppbv) derived from the measured HO2 and RO2. The additional RO2 production from the photolysis of ClNO2 and missing reactivity can explain about 10 % and 20 % of the discrepancy, respectively. The underprediction of the photochemical ozone

  18. A new measurement of the half-life of (166m)Ho.

    PubMed

    Nedjadi, Y; Bailat, C; Caffari, Y; Froidevaux, P; Wastiel, C; Kivel, N; Guenther-Leopold, I; Triscone, G; Jaquenod, F; Bochud, F

    2012-09-01

    The work presented here is a new and precise measurement of the half-life of (166m)Ho by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of (166m)Ho atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope (166)Er interferes with the mass spectrometric measurement, Er has to be eliminated from the (166m)Ho radioactive solution. The elimination was achieved using ion-exchange chromatography with the cation exchange resin Dowex AG 50W-X8 and 2-Hydroxybutanoic acid as the mobile phase. After a first transit through the chromatographic column, the purified (166m)Ho eluate was spiked with natural Er to get a resulting Er isotopic composition close to that of natural Er at better than 99.5%, and then it underwent two further separations to eliminate the Er. The activity concentration of this Er-free radioactive (166m)Ho solution was measured in our reference ionisation chamber calibrated for this nuclide by means of the 4πβ(PC)-γ and 4πβ(PS)-4πγ coincidence techniques and integral counting with a well-type NaI(Tl) detector and Monte Carlo efficiencies. An aliquot of this standardized solution was sent to the Paul Scherrer Institute (PSI) for mass concentration determination using an isotope dilution MC-ICP-MS approach. The mass concentration of (166m)Ho in this solution was determined with 0.25% relative standard uncertainty. This value was corroborated by two other independent measurements. The new half-life of (166m)Ho, 1132.6(39) years (k=1), is compatible with the value determined in 1965, but is 5.6% shorter and about 43 times more precise.

  19. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  20. Urological applications of Ho/Nd:Yag laser

    NASA Astrophysics Data System (ADS)

    Grifoni, Riccardo; Pierangeli, Tiziana; Gioacchini, Andrea; Muraro, Giovanni B.

    2001-10-01

    The introduction of Ho:Yag laser has brought many advantages in urology. By this work we want show you our experience with this technology. Between April 1998 and May 2000 we treated 137 patients. Of these 28 had urinary lithiasis (18 bladder and 10 ureteral stones 3 in the upper, 2 in the middle and 5 in the distal tract), 40 were affected by enlargement of prostatic gland: 32 had B.P.H., 8 P.C.; 36 had T.C.C. and 33 strictures of urethra (27) or bladder neck (6). For ureteral lithiasis we used 200 micrometer fiber, energy of 0.5 - 1.4 J with 10 Hz of frequency. In case of bladder stones a 550 or 1000 micrometer using a power of 80 W. The prostatic gland were resected by a 550 micrometer fiber, 2.2 - 2.8 J, 25 - 30 Hz and 70 -80 W. The superficial bladder tumors were removed by 1.4 J with 10 - 15 Hz and 10 - 14 W. In the large tumors we completed the procedure by Nd:YAG at the base of the tumor. Urethra and bladder neck strictures were treated by 1.2 - 1.8 J and 10 - 30 Hz. We successful treated 26 patients with urinary lithiasis obtained the complete vaporization of the stones, 2 had endoscopic ancillary procedures. Out of 32 patients with B.P.H. 41% had the complete resection of the gland the others the resection of the 3d lobe. We removed 114 superficial bladder tumors and only 4 patients had a local recurrence. Of the patients with the strictures 4 had more than one treatment and about 87% had good result. From our experience the use of Holmium:Yag laser has been very efficacy to treat different urological diseases, also in patients with important comorbid disorders and its use reduce the stay in hospital and so the costs.

  1. Effects of Ni content on nanocrystalline Fe-Co-Ni ternary alloys synthesized by a chemical reduction method

    NASA Astrophysics Data System (ADS)

    Chokprasombat, Komkrich; Pinitsoontorn, Supree; Maensiri, Santi

    2016-05-01

    Magnetic properties of Fe-Co-Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe50Co50-xNix nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe50Ni50 nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300 Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe-Co-Ni alloys could be adjusted by varying the Ni content.

  2. Determination of equilibrium constants for the reaction between acetone and HO2 using infrared kinetic spectroscopy.

    PubMed

    Grieman, Fred J; Noell, Aaron C; Davis-Van Atta, Casey; Okumura, Mitchio; Sander, Stanley P

    2011-09-29

    The reaction between the hydroperoxy radical, HO(2), and acetone may play an important role in acetone removal and the budget of HO(x) radicals in the upper troposphere. We measured the equilibrium constants of this reaction over the temperature range of 215-272 K at an overall pressure of 100 Torr using a flow tube apparatus and laser flash photolysis to produce HO(2). The HO(2) concentration was monitored as a function of time by near-IR diode laser wavelength modulation spectroscopy. The resulting [HO(2)] decay curves in the presence of acetone are characterized by an immediate decrease in initial [HO(2)] followed by subsequent decay. These curves are interpreted as a rapid (<100 μs) equilibrium reaction between acetone and the HO(2) radical that occurs on time scales faster than the time resolution of the apparatus, followed by subsequent reactions. This separation of time scales between the initial equilibrium and ensuing reactions enabled the determination of the equilibrium constant with values ranging from 4.0 × 10(-16) to 7.7 × 10(-18) cm(3) molecule(-1) for T = 215-272 K. Thermodynamic parameters for the reaction determined from a second-law fit of our van't Hoff plot were Δ(r)H°(245) = -35.4 ± 2.0 kJ mol(-1) and Δ(r)S°(245) = -88.2 ± 8.5 J mol(-1) K(-1). Recent ab initio calculations predict that the reaction proceeds through a prereactive hydrogen-bonded molecular complex (HO(2)-acetone) with subsequent isomerization to a hydroxy-peroxy radical, 2-hydroxyisopropylperoxy (2-HIPP). The calculations differ greatly in the energetics of the complex and the peroxy radical, as well as the transition state for isomerization, leading to significant differences in their predictions of the extent of this reaction at tropospheric temperatures. The current results are consistent with equilibrium formation of the hydrogen-bonded molecular complex on a short time scale (100 μs). Formation of the hydrogen-bonded complex will have a negligible impact on the

  3. Identification of Natural Infections in Sheep/Goats with HoBi-like Pestiviruses in China.

    PubMed

    Shi, H; Kan, Y; Yao, L; Leng, C; Tang, Q; Ji, J; Sun, S

    2016-10-01

    The natural infections of HoBi-like pestiviruses in cattle have been reported in South America, Europe and Asia. In China, although the detections of HoBi-like pestivirus have been reported, the epidemiological investigation was limited. From January 2014 to October 2015, several flocks of sheep/goats in Henan province in central China suffered respiratory diseases which were recovered slowly after antibiotics treatment. To test whether it is the HoBi-like pestivirus caused this symptom, 49 serum samples and 22 nasal swabs were then collected for analysis by serology and RT-PCR. Serological result revealed that prevalence of pestivirus in small ruminants was 12.2% (6/49) in central China. Sequence analysis of partial 5'-UTR nucleotides of pestivirus-positive samples suggested that HoBi-like pestivirus might have circulated in sheep/goats of China for a period and have evolved into new genotype clusters. It is apparent that the study provides the molecular evidence of natural infections in goat/sheep species with HoBi-like pestiviruses in China.

  4. Luminescent properties of Tm3+/ Ho3+ co-doped LiYF4 crystals

    NASA Astrophysics Data System (ADS)

    Li, Shan-shan; Xia, Hai-ping; Dong, Yan-ming; Fu, Li; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-11-01

    Ho3+ with various concentrations and Tm3+ with molar concentration of 1.28% are co-doped in LiYF4 (YLF) single crystals. The luminescent properties of the crystals are investigated through emission spectra, emission cross section and decay curves under the excitation of 808 nm. The energy transfer from Tm3+ to Ho3+ and the optimum fluorescence emission of Ho3+ around 2.05 μm are investigated. The emission intensity at 2.05 μm keeps increasing with the molar concentration of Ho3+ improved from 0.50% to 1.51% when the molar concentration of Tm3+ is kept at 1.28%. Moreover, for the co-doped crystals in which the molar concentrations of Tm3+ and Ho3+ are 1.28% and 1.51%, respectively, the maximum emission cross section reaches 0.760×10-20 cm2 and the maximum fluorescence lifetime is 21.98 ms. All the parameters suggest that these materials have more advantages in the future 2.0 μm laser applications.

  5. Hepatitis B Stigma and Knowledge among Vietnamese in Ho Chi Minh City and Chicago

    PubMed Central

    Dam, Lan; Cheng, Anita; Tran, Phuong; Wong, Shirley S.; Hershow, Ronald; Cotler, Sheldon

    2016-01-01

    Stigma regarding viral hepatitis and liver disease has psychological and social consequences including causing negative self-image, disrupting relationships, and providing a barrier to prevention, testing, and treatment. The aim of this study was to characterize and compare HBV knowledge and stigma in Vietnamese in Ho Chi Minh City and Chicago and to begin to evaluate the cultural context of HBV stigma. Methods. A written survey including knowledge questions and a validated HBV stigma questionnaire was distributed to Vietnamese in Ho Chi Minh City and Chicago. 842 surveys from Ho Chi Minh City and 170 from Chicago were analyzed. Results. Vietnamese living in Chicago had better understanding of HBV transmission and that HBV can cause chronic infection and liver cancer. Vietnamese in Chicago had higher stigma scores on a broad range of items including guilt and shame about HBV and were more likely to feel that persons with HBV can bring harm to others and should be isolated. Conclusions. Vietnamese in Ho Chi Minh City and Chicago have knowledge deficits about HBV, particularly regarding modes of transmission. Persons in Ho Chi Minh City expressed lower levels of HBV stigma than Vietnamese living in Chicago, likely reflecting changing cultural attitudes in Vietnam. Culturally appropriate educational initiatives are needed to address the problem of HBV stigma. PMID:28101498

  6. Comparison of spectroscopic properties of Tm and Ho in YAG and YLF crystals

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Inge, A. T.; Di Bartolo, B.

    1991-01-01

    The paper compares the cross-relaxation, energy transfer and loss processes in Tm- and Ho-doped YAG and YLF as a function of temperature, Tm concentration, and excitation power. Significant differences in the behavior of Tm and Tm,Ho in YAG and YLF crystals were found. The cross-relaxation rates of Tm(6 pct) are faster in YLF (about 5 microsec) than YAG (about 10 microsec). The energy transfer rates between Tm and Ho are faster in YLF than YAG. The time it takes for the maximum intensity of 1.7-micron emission to drop 10 percent is 25 microsec for YLF:Tm(6 pct),Ho(0.6 pct) and 65 microsec YAG:Tm(6 pct),Ho(0.5 pct). The losses occurring with increasing pump power for 2.1-micron emission of the above samples are 30 percent less in YLF than YAG. These qualitative differences point to YLF as a valuable 2-micron laser host material.

  7. Ghrelin attenuates the growth of HO-8910 ovarian cancer cells through the ERK pathway

    PubMed Central

    Bai, R.X.; Wang, W.P.; Zhao, P.W.; Li, C.B.

    2016-01-01

    Ovarian cancer is one of the most common causes of death from gynecologic tumors and is an important public health issue. Ghrelin is a recently discovered bioactive peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR). Several studies have identified the protective effects of ghrelin on the mammalian reproductive system. However, little research has been done on the effects of ghrelin on ovarian cancer cells, and the underlying mechanisms of these effects. We sought to understand the potential involvement of mitogen-activated protein kinases (MAPKs) in ghrelin-mediated inhibition of growth of the ovarian line HO-8910. We applied different concentrations of ghrelin and an inhibitor of the ghrelin receptor (D-Lys3-GHRP-6) to HO-8910 cells and observed the growth rate of cells and changes in phosphorylation of the MAPKs ERK1/2, JNK and p38. We discovered that ghrelin-induced apoptosis of HO-8910 cells was though phosphorylated ERK1/2, and that this phosphorylation (as well as p90rsk phosphorylation) was mediated by the GHSR. The ERK1/2 pathway is known to play an essential part in the ghrelin-mediated apoptosis of HO-8910 cells. Hence, our study suggests that ghrelin inhibits the growth of HO-8910 cells primarily through the GHSR/ERK pathway. PMID:26840702

  8. Near-IR diode laser absorption for measurement of tropospheric HO2

    NASA Technical Reports Server (NTRS)

    Stanton, Alan C.

    1994-01-01

    The possibility of using tunable lead salt diode lasers in the infrared for measurement of tropospheric HO2 has been frequently considered. Although the sensitivity of diode laser absorption has been improved through the use of high frequency detection techniques, nature has been unkind in that the HO2 absorption cross sections are weak. Even using the most optimistic assumptions about attainable path length and detectable absorbance, measurement of tropospheric HO2 by diode laser absorption in the mid-IR appears marginal. A possible alternative method for measuring HO2 is by absorption at near-infrared wavelengths. Several absorption bands of HO2 occur in the wavelength region between 1.2 and 1.6 micron due to electronic transitions and overtones of the fundamental vibrational modes. InGaAsP diode lasers operate in this wavelength region and can be used for high resolution spectroscopy in a manner analogous to the lead salt lasers. A diode laser system in the near-IR offers some advantages.

  9. Clinical Presentation Resembling Mucosal Disease Associated with 'HoBi'-like Pestivirus in a Field Outbreak.

    PubMed

    Weber, M N; Mósena, A C S; Simões, S V D; Almeida, L L; Pessoa, C R M; Budaszewski, R F; Silva, T R; Ridpath, J F; Riet-Correa, F; Driemeier, D; Canal, C W

    2016-02-01

    The genus Pestivirus of the family Flaviviridae consists of four recognized species: Bovine viral diarrhoea virus 1 (BVDV-1), Bovine viral diarrhoea virus 2 (BVDV-2), Classical swine fever virus (CSFV) and Border disease virus (BDV). Recently, atypical pestiviruses ('HoBi'-like pestiviruses) were identified in batches of contaminated foetal calf serum and in naturally infected cattle with and without clinical symptoms. Here, we describe the first report of a mucosal disease-like clinical presentation (MD) associated with a 'HoBi'-like pestivirus occurring in a cattle herd. The outbreak was investigated using immunohistochemistry, antibody detection, viral isolation and RT-PCR. The sequence and phylogenetic analysis of 5'NCR, N(pro) and E2 regions of the RT-PCR positive samples showed that four different 'HoBi'-like strains were circulating in the herd. The main clinical signs and lesions were observed in the respiratory and digestive systems, but skin lesions and corneal opacity were also observed. MD characteristic lesions and a pestivirus with cytopathic biotype were detected in one calf. The present study is the first report of a MD like presentation associated with natural infection with 'HoBi'-like pestivirus. This report describes the clinical signs and provides a pathologic framework of an outbreak associated with at least two different 'HoBi'-like strains. Based on these observations, it appears that these atypical pestiviruses are most likely underdiagnosed in Brazilian cattle.

  10. Growth and magneto-optical characteristic of Ho2Ti2O7 crystal

    NASA Astrophysics Data System (ADS)

    Kang, Junbiao; Xu, Wenming; Zhang, Wenhui; Chen, Xiang; Liu, Wei; Guo, Feiyun; Wu, Shuting; Chen, Jianzhong

    2014-06-01

    A pyrochlore crystal with magneto-optical effect-Ho2Ti2O7 crystal has been grown by Czochralski method. X-ray powder diffraction, magnetic susceptibility, transmission spectrum and Faraday rotation of single crystal Ho2Ti2O7 were measured. The results of Rietveld refinement revealed that the crystal belongs to cubic system and the lattice parameters calculated by Jade 7.0 (Materials Data, Inc.) were a=1.00915(7) nm and V=1.0277 nm3. The effective magnetic moment and Curie-Weiss temperature of Ho2Ti2O7 crystal are 10.4 μB and 1.86 K, respectively. The transmittance of Ho2Ti2O7 crystals grown in Ar can be more than 72% in 700-1080 nm and 1260-1500 nm. The Verdet constant of Ho2Ti2O7 crystal at 1064 nm comes up to -54.1 rad/(mT), which is 1.35 times as large as that of Tb3Ga5O12 reported.

  11. Hepatitis B Stigma and Knowledge among Vietnamese in Ho Chi Minh City and Chicago.

    PubMed

    Dam, Lan; Cheng, Anita; Tran, Phuong; Wong, Shirley S; Hershow, Ronald; Cotler, Sheldon; Cotler, Scott J

    2016-01-01

    Stigma regarding viral hepatitis and liver disease has psychological and social consequences including causing negative self-image, disrupting relationships, and providing a barrier to prevention, testing, and treatment. The aim of this study was to characterize and compare HBV knowledge and stigma in Vietnamese in Ho Chi Minh City and Chicago and to begin to evaluate the cultural context of HBV stigma. Methods. A written survey including knowledge questions and a validated HBV stigma questionnaire was distributed to Vietnamese in Ho Chi Minh City and Chicago. 842 surveys from Ho Chi Minh City and 170 from Chicago were analyzed. Results. Vietnamese living in Chicago had better understanding of HBV transmission and that HBV can cause chronic infection and liver cancer. Vietnamese in Chicago had higher stigma scores on a broad range of items including guilt and shame about HBV and were more likely to feel that persons with HBV can bring harm to others and should be isolated. Conclusions. Vietnamese in Ho Chi Minh City and Chicago have knowledge deficits about HBV, particularly regarding modes of transmission. Persons in Ho Chi Minh City expressed lower levels of HBV stigma than Vietnamese living in Chicago, likely reflecting changing cultural attitudes in Vietnam. Culturally appropriate educational initiatives are needed to address the problem of HBV stigma.

  12. Novel tracer method to measure isotopic labeled gas-phase nitrous acid (HO15NO) in biogeochemical studies.

    PubMed

    Wu, Dianming; Kampf, Christopher J; Pöschl, Ulrich; Oswald, Robert; Cui, Junfang; Ermel, Michael; Hu, Chunsheng; Trebs, Ivonne; Sörgel, Matthias

    2014-07-15

    Gaseous nitrous acid (HONO), the protonated form of nitrite, contributes up to ∼60% to the primary formation of hydroxyl radical (OH), which is a key oxidant in the degradation of most air pollutants. Field measurements and modeling studies indicate a large unknown source of HONO during daytime. Here, we developed a new tracer method based on gas-phase stripping-derivatization coupled to liquid chromatography-mass spectrometry (LC-MS) to measure the 15N relative exceedance, ψ(15N), of HONO in the gas-phase. Gaseous HONO is quantitatively collected and transferred to an azo dye, purified by solid phase extraction (SPE), and analyzed using high performance liquid chromatography coupled to mass spectrometry (HPLC-MS). In the optimal working range of ψ(15N)=0.2-0.5, the relative standard deviation of ψ(15N) is <4%. The optimum pH and solvents for extraction by SPE and potential interferences are discussed. The method was applied to measure HO15NO emissions from soil in a dynamic chamber with and without spiking 15) labeled urea. The identification of HO15NO from soil with 15N urea addition confirmed biogenic emissions of HONO from soil. The method enables a new approach of studying the formation pathways of HONO and its role for atmospheric chemistry (e.g., ozone formation) and environmental tracer studies on the formation and conversion of gaseous HONO or aqueous NO2- as part of the biogeochemical nitrogen cycle, e.g., in the investigation of fertilization effects on soil HONO emissions and microbiological conversion of NO2- in the hydrosphere.

  13. Effect of poverty on the relationship between personal exposures and ambient concentrations of air pollutants in Ho Chi Minh City

    NASA Astrophysics Data System (ADS)

    Mehta, Sumi; Sbihi, Hind; Dinh, Tuan Nguyen; Xuan, Dan Vu; Le Thi Thanh, Loan; Thanh, Canh Truong; Le Truong, Giang; Cohen, Aaron; Brauer, Michael

    2014-10-01

    Socioeconomic factors often affect the distribution of exposure to air pollution. The relationships between health, air pollution, and poverty potentially have important public health and policy implications, especially in areas of Asia where air pollution levels are high and income disparity is large. The objective of the study was to characterize the levels, determinants of exposure, and relationships between children personal exposures and ambient concentrations of multiple air pollutants amongst different socioeconomic segments of the population of Ho Chi Minh City, Vietnam. Using repeated (N = 9) measures personal exposure monitoring and determinants of exposure modeling, we compared daily average PM2.5, PM10, PM2.5 absorbance and NO2 concentrations measured at ambient monitoring sites to measures of personal exposures for (N = 64) caregivers of young children from high and low socioeconomic groups in two districts (urban and peri-urban), across two seasons. Personal exposures for both PM sizes were significantly higher among the poor compared to non-poor participants in each district. Absolute levels of personal exposures were under-represented by ambient monitors with median individual longitudinal correlations between personal exposures and ambient concentrations of 0.4 for NO2, 0.6 for PM2.5 and PM10 and 0.7 for absorbance. Exposures of the non-poor were more highly correlated with ambient concentrations for both PM size fractions and absorbance while those for NO2 were not significantly affected by socioeconomic position. Determinants of exposure modeling indicated the importance of ventilation quality, time spent in the kitchen, air conditioner use and season as important determinant of exposure that are not fully captured by the differences in socioeconomic position. Our results underscore the need to evaluate how socioeconomic position affects exposure to air pollution. Here, differential exposure to major sources of pollution, further influenced by

  14. Study of cavitation bubble dynamics during Ho:YAG laser lithotripsy by high-speed camera

    NASA Astrophysics Data System (ADS)

    Zhang, Jian J.; Xuan, Jason R.; Yu, Honggang; Devincentis, Dennis

    2016-02-01

    Although laser lithotripsy is now the preferred treatment option for urolithiasis, the mechanism of laser pulse induced calculus damage is still not fully understood. This is because the process of laser pulse induced calculus damage involves quite a few physical and chemical processes and their time-scales are very short (down to sub micro second level). For laser lithotripsy, the laser pulse induced impact by energy flow can be summarized as: Photon energy in the laser pulse --> photon absorption generated heat in the water liquid and vapor (super heat water or plasma effect) --> shock wave (Bow shock, acoustic wave) --> cavitation bubble dynamics (oscillation, and center of bubble movement , super heat water at collapse, sonoluminscence) --> calculus damage and motion (calculus heat up, spallation/melt of stone, breaking of mechanical/chemical bond, debris ejection, and retropulsion of remaining calculus body). Cavitation bubble dynamics is the center piece of the physical processes that links the whole energy flow chain from laser pulse to calculus damage. In this study, cavitation bubble dynamics was investigated by a high-speed camera and a needle hydrophone. A commercialized, pulsed Ho:YAG laser at 2.1 mu;m, StoneLightTM 30, with pulse energy from 0.5J up to 3.0 J, and pulse width from 150 mu;s up to 800 μs, was used as laser pulse source. The fiber used in the investigation is SureFlexTM fiber, Model S-LLF365, a 365 um core diameter fiber. A high-speed camera with frame rate up to 1 million fps was used in this study. The results revealed the cavitation bubble dynamics (oscillation and center of bubble movement) by laser pulse at different energy level and pulse width. More detailed investigation on bubble dynamics by different type of laser, the relationship between cavitation bubble dynamics and calculus damage (fragmentation/dusting) will be conducted as a future study.

  15. Investigation of antibiotics in health care wastewater in Ho Chi Minh City, Vietnam.

    PubMed

    Vo, Thi-Dieu-Hien; Bui, Xuan-Thanh; Cao, Ngoc-Dan-Thanh; Luu, Vinh-Phuc; Nguyen, Thanh-Tin; Dang, Bao-Trong; Thai, Minh-Quan; Nguyen, Dinh-Duc; Nguyen, Thanh-Son; Dinh, Quoc-Tuc; Dao, Thanh-Son

    2016-12-01

    Hospital wastewater contains huge amounts of hazardous pollutants which are being discharged daily to environment with or without treatment. Antibiotics were among the important group of pharmaceuticals considered as a potential source of health risk for human and other living creatures. Although the investigations about the existence of antibiotics in hospital wastewater have gained concern for researchers in many countries, there is only one research conducted in Hanoi-Vietnam. Hence, in this study, investigations have been done to fulfill the requirement of real situation in Vietnam by accomplishing survey for 39 health care facilities in Ho Chi Minh City. As results, seven popular antibiotics were detected to exist in all samples such as sulfamethoxazole (2.5 ± 1.9 μg/L), norfloxacin (9.6 ± 9.8 μg/L), ciprofloxacin (5.3 ± 4.8 μg/L), ofloxacin (10.9 ± 8.1 μg/L), erythromycin (1.2 ± 1.2 μg/L), tetracycline (0.1 ± 0.0 μg/L), and trimethoprim (1.0 ± 0.9 μg/L). On the other hand, survey also showed that only 64% of health care facilities using conventional activate sludge (AS) processes in wastewater treatment plants (WWTPs). As a consequence, basic environmental factors (BOD5, COD, TSS, NH4(+)-N, or total coliforms) were not effectively removed from the hospital wastewater due to problems relating to initial design or operational conditions. Therefore, 18% effluent samples of the surveyed WWTPs have exceeded the national standard limits (QCVN 28:2010, level B).

  16. Density-functional study of the structures and properties of holmium-doped silicon clusters HoSi n (n = 3-9) and their anions.

    PubMed

    Hou, Liyuan; Yang, Jucai; Liu, Yuming

    2017-04-01

    The structures and properties of Ho-doped Si clusters, including their adiabatic electron affinities (AEAs), simulated photoelectron spectra (PESs), stabilities, magnetic moments, and charge-transfer characteristics, were systematically investigated using four density-functional methods. The results show that the double-hybrid functional (which includes an MP2 correlation component) can accurately predict the ground-state structure and properties of Ho-doped Si clusters. The ground-state structures of HoSi n (n = 3-9) are sextuplet electronic states. The structures of these Ho-doped Si clusters (aside from HoSi7) are substitutional. The ground-state structures of HoSi n(-) are quintuplet electronic states. Their predicted AEAs are in excellent agreement with the experimental ones. The mean absolute error in the theoretical AEAs of HoSi n (n = 4-9) is only 0.04 eV. The simulated PESs for HoSi n(-) (n = 5-9) are in good agreement with the experimental PESs. Based on its simulated PES and theoretical AEA, we reassigned the experimental PES of HoSi4(-) and obtained an experimental AEA of 2.2 ± 0.1 eV. The dissociation energies of Ho from HoSi n and HoSi n(-) (n = 3-9) were evaluated to test the relative stabilities of the clusters. HOMO-LUMO gap analysis indicated that doping the Si clusters with the rare-earth metal atom significantly increases their photochemical reactivity. Natural population analysis showed that the magnetic moments of HoSi n (n = 3-9) and their anions derive mainly from the Ho atom. It was also found that the magnetic moments of Ho in the HoSi n clusters are larger than the magnetic moment of an isolated Ho atom.

  17. Exogenous induction of HO-1 alleviates vincristine-induced neuropathic pain by reducing spinal glial activation in mice.

    PubMed

    Shen, Yan; Zhang, Zhi-Jun; Zhu, Ming-Di; Jiang, Bao-Chun; Yang, Tian; Gao, Yong-Jing

    2015-07-01

    Chemotherapy drugs such as vincristine can produce painful peripheral neuropathy for which is still lack of effective treatment. Recent studies have demonstrated that neuroinflammation plays an important role in the pathogenesis of neuropathic pain. Heme oxygenase 1 (HO-1) was shown to mediate the resolution of inflammation. In this study, we investigated the contribution of HO-1 in the modulation of vincristine-induced pain and the mechanisms implicated. Injection of vincristine induced persistent mechanical allodynia and thermal hyperalgesia in mice. The expression of HO-1 mRNA and protein was increased in 2 weeks in the spinal cord. Immunostaining showed that HO-1 was mainly expressed in neurons of spinal cord dorsal horn in naïve animals, but induced in astrocytes and microglia after vincristine injection. Intraperitoneal injection of HO-1 inducer increased HO-1 expression in the spinal cord and attenuated vincristine-induced pain. Persistent induction of HO-1 by intraspinal injection of HO-1-expressing lentivirus alleviated vincristine-induced pain for more than 2 weeks. Furthermore, vincristine induced activation of glial cells (astrocytes and microglia), phosphorylation of MAPKs (JNK, ERK, and p38), and production of TNF-α and monocyte chemoattractant protein-1 in the spinal cord, which were all reduced by intrathecal injection of HO-1 inducer. Taken together, our data provide the first evidence that induction of HO-1 attenuates vincristine-induced neuropathic pain via inhibition of glia-mediated neuroinflammation in the spinal cord. This suggests that exogenously induced HO-1 may have potential as therapy in chemotherapy-induced neuropathic pain.

  18. Consistency of the Health of the Nation Outcome Scales (HoNOS) at inpatient-to-community transition

    PubMed Central

    Harvey, Richard; Phung, Dinh; Venkatesh, Svetha; Connor, Jason P

    2016-01-01

    Objectives The Health of the Nation Outcome Scales (HoNOS) are mandated outcome-measures in many mental-health jurisdictions. When HoNOS are used in different care settings, it is important to assess if setting specific bias exists. This article examines the consistency of HoNOS in a sample of psychiatric patients transitioned from acute inpatient care and community centres. Setting A regional mental health service with both acute and community facilities. Participants 111 psychiatric patients were transferred from inpatient care to community care from 2012 to 2014. Their HoNOS scores were extracted from a clinical database; Each inpatient-discharge assessment was followed by a community-intake assessment, with the median period between assessments being 4 days (range 0–14). Assessor experience and professional background were recorded. Primary and secondary outcome measures The difference of HoNOS at inpatient-discharge and community-intake were assessed with Pearson correlation, Cohen's κ and effect size. Results Inpatient-discharge HoNOS was on average lower than community-intake HoNOS. The average HoNOS was 8.05 at discharge (median 7, range 1–22), and 12.16 at intake (median 12, range 1–25), an average increase of 4.11 (SD 6.97). Pearson correlation between two total scores was 0.073 (95% CI −0.095 to 0.238) and Cohen's κ was 0.02 (95% CI −0.02 to 0.06). Differences did not appear to depend on assessor experience or professional background. Conclusions Systematic change in the HoNOS occurs at inpatient-to-community transition. Some caution should be exercised in making direct comparisons between inpatient HoNOS and community HoNOS scores. PMID:27121703

  19. Molecular cloning and expression of a cucumber (Cucumis sativus L.) heme oxygenase-1 gene, CsHO1, which is involved in adventitious root formation.

    PubMed

    Li, Mei-Yue; Cao, Ze-Yu; Shen, Wen-Biao; Cui, Jin

    2011-10-15

    Our previous work showed that in cucumber (Cucumis sativus), auxin rapidly induces heme oxygenase (HO) activity and the product of HO action, carbon monoxide (CO), then triggers the signal transduction events leading to adventitious root formation. In this study, the cucumber HO-1 gene (named as CsHO1) was isolated and sequenced. It contains four exons and three introns and encodes a polypeptide of 291 amino acids. Further results show that CsHO1 shares a high homology with plant HO-1 proteins and codes a 33.3 kDa protein with a 65-amino transit peptide, predicting a mature protein of 26.1 kDa. The mature CsHO1 was expressed in Escherichia coli to produce a fusion protein, which exhibits HO activity. The CsHO1:GFP fusion protein was localized in the chloroplast. Related biochemical analyses of mature CsHO1, including Vmax, Km, Topt and pHopt, were also investigated. CsHO1 mRNA was found in germinating seeds, roots, stem, and especially in leaf tissues. Several well-known adventitious root inducers, including auxin, ABA, hemin, nitric oxide donor sodium nitroprusside (SNP), CaCl(2), and sodium hydrosulfide (NaHS), differentially up-regulate CsHO1 transcripts and corresponding protein levels. These results suggest that CsHO1 may be involved in cucumber adventitious rooting.

  20. Ni, Co, and Mo-metal-catalyzed alkynes hydrostannations using Bu(3)SnCl/PMHS/KF/18-crown-6 as an in situ Bu(3)SnH source.

    PubMed

    Ghosh, Banibrata; Maleczka, Robert E

    2011-10-12

    A number of terminal alkynes were subjected to nickel, cobalt, and molybdenum catalyzed hydrostannations in presence of tributyltin chloride, polymethylhydrosiloxane, potassium fluoride and 18-crown-6 as an situ organotin hydride source to produce vinylstannanes.

  1. The effect of moderate-intensity exercise on the expression of HO-1 mRNA and activity of HO in cardiac and vascular smooth muscle of spontaneously hypertensive rats.

    PubMed

    Ren, Cailing; Qi, Jie; Li, Wanwei; Zhang, Jun

    2016-04-01

    The objective of this study was to observe the effects of moderate-intensity training on the activity of heme oxygenase (HO) and expression of HO-1 mRNA in the aorta and the cardiac muscle of spontaneously hypertensive rats (SHRs). After 9 weeks of swimming exercise, the activity of HO and expression of HO-1 mRNA in the SHRs were measured. The resting blood pressure in the exercise group was increased by 1.7% (P > 0.05), whereas it was significantly elevated by 10.3% (P < 0.01) in the SHR rats. Compared with animals in the control and sedentary groups, the expression level of HO-1 mRNA of aorta and cardiac muscle in the exercise group was significantly enhanced (P < 0.01). The HO activity and the content of plasma carbon monoxide (CO) in the sedentary group were dramatically decreased (P < 0.05 and P < 0.01, respectively) compared with the control group. HO activity and content of plasma CO in the exercise group were significantly higher compared with those in the sedentary group (P < 0.05 and P < 0.01, respectively). The HO/CO metabolic pathway might be involved in the regulation of blood pressure of the SHR models.

  2. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Smialek, James L.; Barrett, Charles A.

    1988-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al2O3 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  3. Kinetics of the reaction OH + HO2 yields H2O + O2 at 296 K

    NASA Technical Reports Server (NTRS)

    Sridharan, U. C.; Kaufman, F.; Qiu, L. X.

    1981-01-01

    The rate constant of the title reaction was measured in a discharge-flow reactor by addition of excess HO2 from a movable double injector to a gas stream containing small concentrations of OH. The concentration of OH was measured by laser-induced fluorescence, HO2 by conversion to OH, and H and O by vacuum-UV resonance fluorescence. Five sets of experiments, each with different excess concentration of HO2, gave an average rate constant of (7.5 + or - 1.2) x 10 to the -11th cu cm/s where the error limits (single sigma) include uncertainties of all experimental parameters. This result is compared with other findings and is discussed in terms of its importance in stratospheric chemistry and in rate theory.

  4. In vitro investigation on Ho:YAG laser-assisted bone ablation underwater.

    PubMed

    Zhang, Xianzeng; Chen, Chuanguo; Chen, Faner; Zhan, Zhenlin; Xie, Shusen; Ye, Qing

    2016-07-01

    Liquid-assisted hard tissue ablation by infrared lasers has extensive clinical application. However, detailed studies are still needed to explore the underlying mechanism. In the present study, the dynamic process of bubble evolution induced by Ho:YAG laser under water without and with bone tissue at different thickness layer were studied, as well as its effects on hard tissue ablation. The results showed that the Ho:YAG laser was capable of ablating hard bone tissue effectively in underwater conditions. The penetration of Ho:YAG laser can be significantly increased up to about 4 mm with the assistance of bubble. The hydrokinetic forces associated with the bubble not only contributed to reducing the thermal injury to peripheral tissue, but also enhanced the ablation efficiency and improve the ablation crater morphology. The data also presented some clues to optimal selection of irradiation parameters and provided additional knowledge of the bubble-assisted hard tissue ablation mechanism.

  5. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.

  6. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    PubMed

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

  7. Adsorption of HO(x) on aerosol surfaces - Implications for the atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Leu, M.-T.; Nair, H. A.; Yung, Y. L.

    1993-01-01

    The potential impact of heterogeneous chemistry on the abundance and distribution of HO(x) in the Martian atmosphere is investigated using observational data on dust and ice aerosol distributions combined with an updated photochemical model. Critical parameters include the altitude distributions of aerosols and the surface loss coefficients of HO2 on dust and ice in the lower atmosphere and of H on ice above 40 km. Results of calculations indicate that adsorption of HO2 on dust, or ice near 30 km, can deplete OH abundances in the lower atmosphere by 10 percent or more and that the adsorption of H on ice at 50 km can result in even larger OH depletions (this effect is localized to altitudes greater than 40 km, where CO oxidation is relatively unimportant).

  8. Anomalous charge transport in RB12 (R = Ho, Er, Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Sluchanko, N.; Bogomolov, L.; Glushkov, V.; Demishev, S.; Ignatov, M.; Khayrullin, Eu.; Samarin, N.; Sluchanko, D.; Levchenko, A.; Shitsevalova, N.; Flachbart, K.

    High precision measurements of Hall RH(T) and Seebeck S(T) coefficients have been carried out for the first time on single crystals of rare earth dodecaborides RB12 (R D Ho, Er, Tm, Lu) at temperatures 1.8-300 K. Low temperature anomalies detected on the temperature dependencies of RH(T) and S(T) are associated with antiferromagnetic phase transitions in HoB12, ErB12 and TmB12 compounds. The observed discrepancy between the change of charge carriers' mobility and de-Gennes factor (g - 1)2 J(J + 1) (J - angular momentum of the 4f shell) in the set of HoB12-TmB12 allows us to conclude about the appreciable influence of spin fluctuations on the charge transport in these compounds with B12 atomic clusters.

  9. ADP-2Ho as a Phasing Tool for Nucleotide-Containing Proteins

    SciTech Connect

    Ku,S.; Smith, G.; Howell, P.

    2007-01-01

    Trivalent holmium ions were shown to isomorphously replace magnesium ions to form an ADP-2Ho complex in the nucleotide-binding domain of Bacillus subtilis 5-methylthioribose (MTR) kinase. This nucleotide-holmium complex provided sufficient phasing power to allow SAD and SIRAS phasing of this previously unknown structure using the L{sub III} absorption edge of holmium. The structure of ADP-2Ho reveals that the two Ho ions are approximately 4 {angstrom} apart and are likely to share their ligands: the phosphoryl O atoms of ADP and a water molecule. The structure determination of MTR kinase using data collected using Cu K X-radiation was also attempted. Although the heavy-atom substructure determination was successful, interpretation of the map was more challenging. The isomorphous substitution of holmium for magnesium in the MTR kinase-nucleotide complex suggests that this could be a useful phasing tool for other metal-dependent nucleotide-containing proteins.

  10. High-resolution spectra of LiYF4:Ho3+ in a magnetic field

    NASA Astrophysics Data System (ADS)

    Popova, M. N.; Boldyrev, K. N.

    2017-01-01

    We report on the first high-resolution optical spectroscopy study of LiYF4:Ho in an external magnetic field. Peculiarities in the hyperfine structure of holmium spectral lines are discussed for the cases H||c and H⊥c (H = 0.53 and 0.87 T). The spectra reveal a strong interaction between crystal-field levels, mediated by Zeeman and hyperfine terms in the Hamiltonian. A study of the magnetic-field-dependent isotope shifts in 7Li0.16Li0.9YF4:Ho (0.1 at.%) single crystals delivers an estimate of the difference in magnetic g factors for holmium centers with all 6Li isotopes in the nearest surrounding of Ho3+ (g(0)) and the centers having one 7Li isotope there (g(1)):g(1) - g(0) = 0.01 ± 0.005.

  11. Ground state of Ho atoms on Pt(111) metal surfaces: Implications for magnetism

    NASA Astrophysics Data System (ADS)

    Karbowiak, M.; Rudowicz, C.

    2016-05-01

    We investigated the ground state of Ho atoms adsorbed on the Pt(111) surface, for which conflicting results exist. The density functional theory (DFT) calculations yielded the Ho ground state as | Jz=±8 > . Interpretation of x-ray absorption spectroscopy and x-ray magnetic circular dichroism spectra and the magnetization curves indicated the ground state as | Jz=±6 > . Superposition model is employed to predict the crystal-field (CF) parameters based on the structural data for the system Ho/Pt(111) obtained from the DFT modeling. Simultaneous diagonalization of the free-ion (HFI) and the trigonal CF Hamiltonian (HCF) within the whole configuration 4 f10 of H o3 + ion was performed. The role of the trigonal CF terms, neglected in the pure uniaxial CF model used previously for interpretation of experimental spectra, is found significant, whereas the sixth-rank CF terms may be neglected in agreement with the DFT predictions. The results provide substantial support for the experimental designation of the | Jz=±6 > ground state, albeit with subtle difference due to admixture of other | Jz> states, but run against the DFT-based designation of the | Jz=±8 > ground state. A subtle splitting of the ground energy level with the state (predominantly), | Jz=±6 > is predicted. This paper provides better insight into the single-ion magnetic behavior of the Ho/Pt(111) system by helping to resolve the controversy concerning the Ho ground state. Experimental techniques with greater resolution powers are suggested for direct confirmation of this splitting and C3 v symmetry experienced by the Ho atom.

  12. Infrared radiation properties of Ho³⁺ in multicomponent germanium tellurite glasses.

    PubMed

    Sui, Z Q; Chen, B J; Pun, E Y B; Lin, H

    2015-07-01

    Ho(3+)-doped and Ho(3+)/Yb(3+)-codoped multicomponent germanium tellurite (MGT) glasses with multifarious emission channels in the near-infrared wavelength region have been fabricated and characterized. Judd-Ofelt intensity parameters of Ho(3+)-doped MGT glasses are solved to be Ω2=5.32×10(-20)  cm(2), Ω(4)=2.73×10(-20)  cm(2), and Ω(6)=1.12×10(-20)  cm(2), indicating a higher asymmetric and stronger covalent environment around Ho(3+) ions in MGT glasses. Efficient infrared fluorescences have been observed in MGT glasses, and spontaneous emission probabilities are derived to be 230.4, 79.9, and 138.3  s(-1) for the (5)I(6)→(5)I(8), ((5)F(4),(5)S(2))→(5)I(5), and (5)I(7)→(5)I(8) radiative transitions, respectively. In Ho(3+)/Yb(3+)-codoped MGT glasses, the maximum stimulated emission cross-section of 2.0 μm emission is calculated to be 4.93×10(-21)  cm(2), and the corresponding gain cross-section is derived to be 3.62×10(-21)  cm(2) when the excited state population fraction P reaches 0.8. Multifarious infrared emissions show that Ho(3+) in MGT glasses is a good candidate for optical amplifiers and optoelectronic devices.

  13. NO counterbalances HO-1 overexpression-induced acceleration of hepatocyte proliferation in mice.

    PubMed

    Schuett, Harald; Eipel, Christian; Maletzki, Claudia; Menger, Michael D; Vollmar, Brigitte

    2007-06-01

    The trigger for liver regeneration, including shear stress, has been the subject of ongoing debate. Blood vessel-derived gaseous molecules carbon monoxide (CO) and nitric oxide (NO) regulate vascular tone and play an important role in liver regeneration. In heme oxygenase-1 (HO-1) transgenic mice, it has been shown that CO-mediated impairment of vasorelaxation is an NO-dependent event. We therefore studied liver regeneration in HO-1 overexpressing animals in dependency of NO availability. Mice were subjected to (2/3) hepatectomy and were treated with either cobalt protoporphyrin-IX for induction of CO-liberating HO-1, N(omega)-nitro-L-arginine methyl ester (L-NAME) for blockade of NO synthase (NOS) or both. Application of molsidomine in L-NAME treated animals served for resubstitution of NO. Vehicle-treated animals served as respective control animals. We examined 5-bromo-2'-deoxyuridine incorporation and proliferating cell nuclear antigen expression as well as HO-1 and NOS-2 protein levels. Intrahepatic red blood cell velocity and volumetric blood flow were evaluated by in vivo fluorescence microscopy as indicators for microvascular shear stress. Hepatic regeneration remained unaffected by L-NAME application for NOS blockade. However, NOS blockade in HO-1 induced animals caused increased 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen measures of liver regeneration. In parallel, these animals revealed increased velocities and volumetric blood flow in the terminal afferent vessels and postsinusoidal venules. These local hemodynamic changes including enhanced hepatocyte proliferation could be reversed by NO liberation via molsidomine. The present findings stress the role of NO to counterbalance vascular tone in HO-1 overexpressing animals for maintenance of adequate perfusion and salutary shear force within the hepatic microvasculature upon liver resection.

  14. Bulk Migration of Ni/NiO in Ni-YSZ during Reducing Conditions

    SciTech Connect

    Saraf, Laxmikant V.; Baer, Donald R.; Lea, Alan S.; Zhu, Zihua; Strohm, James J.; Sitzman, S. D.; King, David L.

    2010-02-09

    Understanding the migration of Ni/NiO in Ni-YSZ can potentially help to design a better solid oxide fuel cell (SOFC) anode. We have observed that extensive hydrogen reduction and methane steam reforming of Ni-YSZ caused bulk migration of Ni/NiO to at least ~ 5 µm deeper from the Ni-YSZ surface. No significant bulk migration effects were detected after simple thermal treatments in non-reducing/non-reforming environment. Surface analysis of a single zirconia grain in the first 10-20 nm region from annealed, hydrogen reduced and methane steam reformed Ni-YSZ shows Ni-enriched surface supporting earlier claims of Ni exsolution. 3D-EBSD analysis of thermally treated sample before exposing it to reducing and reforming environment indicated mixed NiO/YSZ phase with some porosity and random grain orientation. The surface analysis and mapping were carried out using ToF-SIMS and AES whereas EDS maps on FIB sliced areas on Ni-YSZ were utilized for the bulk analysis. The results provide additional information related to complex reactions occurring in SOFC during internal reforming conditions.

  15. FABRICATION OF NEUTRON SOURCES

    DOEpatents

    Birden, J.H.

    1959-01-20

    A method is presented for preparing a more efficient neutron source comprising inserting in a container a quantity of Po-210, inserting B powder coated with either Ag, Pt, or Ni. The container is sealed and then slowly heated to about 450 C to volatilize the Po and effect combination of the coated powder with the Po. The neutron flux emitted by the unit is moritored and the heating step is terminated when the flux reaches a maximum or selected level.

  16. Intense 2.8 μm emission of Ho³⁺ doped PbF₂ single crystal.

    PubMed

    Zhang, Peixiong; Yin, Jigang; Zhang, Baitao; Zhang, Lianhan; Hong, Jiaqi; He, Jingliang; Hang, Yin

    2014-07-01

    A Ho³⁺-doped PbF₂ mid-IR laser crystal was successfully grown using the vertical Bridgman method. An intense 2.8 μm emission in Ho:PbF₂ crystal was observed for the first time. By analyzing the absorption and emission measurements of the Ho:PbF₂ crystal with the Judd-Ofelt theory, the intensity parameters Ω(2,4,6), exited state lifetimes, branching ratios, and emission cross-sections were calculated. It is found that the Ho:PbF₂ crystal has high fluorescence branching ratio (20.99%), large emission cross section (1.44×10⁻²⁰ cm²), long fluorescence lifetime (5.4 ms), and high quantum efficiency (88.4%) corresponding to the stimulated emission of Ho³⁺: ⁵I₆→⁵I₇ transition. The structure of Ho:PbF₂ crystal was also analyzed by the Raman spectrum, and it was found that the Ho:PbF₂ crystal possesses low phonon energy of 257 cm⁻¹. We propose that the Ho:PbF₂ crystal may be a promising material for 2.8 μm laser applications.

  17. Impacts and Preferences Study for e-HO as a Holistic Learning Environment Complementary to E-Learning

    ERIC Educational Resources Information Center

    Lee, Ching-Yieh; Der Pan, Peter Jen; Liao, Ching-Jung

    2011-01-01

    We present in this study the significance and impacts of an innovative e-HO as a holistic and horizontal platform complementary to e-Learning to help realize transdisciplinary learning and foster integration of knowledge in higher education. A comprehensive investigation of a survey conducted among 647 university students for e-HO is presented…

  18. Antigenic differences between bovine viral diarrhea viruses and HoBi virus: Possible impacts on diagnosis and control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Compare antigenic differences between HoBi virus and BVDV strains that might impact on diagnostics and control. Eighteen non-cytopathic isolates of pestiviruses including the 5 genotypic groups (BVDV1a-c, BVDV2, BDV) and HoBi virus, were tested using antigen capture enzyme-linked immunosorbent assay...

  19. Photoluminescence Quenching and Enhanced Optical Conductivity of P3HT-Derived Ho(3+)-Doped ZnO Nanostructures.

    PubMed

    Kabongo, Guy L; Mbule, Pontsho S; Mhlongo, Gugu H; Mothudi, Bakang M; Hillie, Kenneth T; Dhlamini, Mokhotjwa S

    2016-12-01

    In this article, we demonstrate the surface effect and optoelectronic properties of holmium (Ho(3+))-doped ZnO in P3HT polymer nanocomposite. We incorporated ZnO:Ho(3+) (0.5 mol% Ho) nanostructures in the pristine P3HT-conjugated polymer and systematically studied the effect of the nanostructures on the optical characteristics. Detailed UV-Vis spectroscopy analysis revealed enhanced absorption coefficient and optical conductivity in the P3HT-ZnO:Ho(3+) film as compared to the pristine P3HT. Moreover, the obtained photoluminescence (PL) results established the improvement of exciton dissociation as a result of ZnO:Ho(3+) nanostructures inclusion. The occurrence of PL quenching is the result of enhanced charge transfer due to ZnO:Ho(3+) nanostructures in the polymer, whereas energy transfer from ZnO:Ho(3+) to P3HT was verified. Overall, the current investigation revealed a systematic tailoring of the optoelectronic properties of pristine P3HT after inclusion of ZnO:Ho(3+) nanostructures, thus opening brilliant perspectives for applications in various optoelectronic devices.

  20. Sensitizing effect of Ho3+ on the Er3+: 2.7 μm-emission in fluoride glass

    NASA Astrophysics Data System (ADS)

    Huang, Feifei; Li, Xia; Liu, Xueqiang; Zhang, Junjie; Hu, Lili; Chen, Danping

    2014-03-01

    The fluorescence properties of 2.7 μm emission and energy transfer mechanism of Ho3+/Er3+ co-doped fluoride glass (ZBYA) have been investigated in the present paper. Ho3+ strengthens the Er3+: 2.7 μm emission in the ZBYA glasses due to the energy transfer from Er3+ to Ho3+, while the 1.5 μm emission decreases dramatically. The optimized concentration ratio of Er3+ to Ho3+ is found to be 1:1 in our glass system. The absorption and emission spectra are tested and the sample possesses large emission cross section (16.5 × 10-21 cm2) around 2.7 μm along with larger radiative transition probability (25.11 S-1) on the basis of Judd-Ofelt and Fuchtbauer-Ladenburg theories. Additionally, the energy transfer microparameters are calculated using Förster-Dexter theory and the result shows the energy transfer coefficient of Er3+:4I13/2 → Ho3+:5I7 is 24 times larger than that of Er3+:4I11/2 → Ho3+:5I6. Our results show that Er3+: 2.7 μm emission can be sensitized by Ho3+ efficiently, and this Er3+/Ho3+-codoped fluoride glasses might have potential application in mid-infrared lasers.

  1. English Language Training in Vietnam in the Era of Doi Moi. Ho Chi Minh City: A Descriptive Case Study.

    ERIC Educational Resources Information Center

    Shapiro, Lawrence Avrom

    The status of English language education in Ho Chi Minh City (Vietnam) in the era of Doi Moi, or economic structuring that began in 1986, is analyzed. Background information is given on the history of English language training in Vietnam since 1975, the municipality of Ho Chi Minh City, the emergence of Doi Moi policy, policy concerning licensing…

  2. A measurement of the vibrational band strength for the upsilon sub 3 band of the HO2 radical

    NASA Technical Reports Server (NTRS)

    Zahniser, M. S.; Stanton, A. C.

    1985-01-01

    The HO2 radicals generated in a discharge-flow system were observed with tunable diode laser absorption in the P-branch of the nu(3) vibrationall band at 1080/cm. The observed line positions agree with those calculated from the molecular constants for the nu(3) bland obtained from a previous study using laser magnetic resonance spectroscopy. The band strength was determined by observing line center absoptions when HO2 is produced in the reaction F + H2O2 yields HO2 + HF (k1) with a measured concentration of atomic fluorine and excess hydrogen peroxide. F-atom concentrations are measured by diode laser absorption of the spin-orbit transition at 404/cm. The analysis accounts for HO2 losses due to the reactions of HO2 + HO2 yields H2O2 + O2 (k3) and F + HO2 yields HF + O2 (k4). The line strength for the 6(15) 7(16) F(1) transition is 2.9 x 10 to the 21st power sq cm/molecule/cm which corresponds to a nu(3) band strength of 34 +/- 9 sq/cm(STP atm). This value is a factor of 6 lower than previous ab initio calculations. These results will be useful in assessing the feasibility of atmospheric measurements of HO2 using infrared absorption techniques.

  3. Decay of the neutron-rich isotope 171Ho and the identification of 169Dy

    NASA Astrophysics Data System (ADS)

    Chasteler, R. M.; Nitschke, J. M.; Firestone, R. B.; Vierinen, K. S.; Wilmarth, P. A.

    1990-10-01

    Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between 170Er ions and natW targets. On-line mass separation was used together with β- and γ-ray spectroscopy in these studies. At mass A=169, the heaviest known dysprosium isotope, 39(8) s,169Dy, was identified. It was observed to β- decay to the ground state of 169Ho or through a level at 1578 keV. In the A=171 mass chain, a partial decay scheme for 55(3)-s 171Ho was determined.

  4. Spectroscopic characterization of dynamical processes for Tm,Ho:YAG lasers

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Edwards, W. C.; Inge, A. T.; Dibartolo, B.

    1991-01-01

    The energy transfer processes in Tm,Ho:YAG lasers were investigated in spectral studies and measurements of the temporal response to pulsed excitation. These processes include the population of the 3H4 pump band of Tm, cross-relaxation in Tm, the transfer of energy from Tm to Ho, and various loss mechanisms. It was found that the Tm cross-relaxation is due to a dipole-dipole interaction between Tm ions and that the rate of this process is a function of temperature and ion concentration.

  5. Diode-Pumped Thulium (Tm)/Holmium (Ho) Composite Fiber 2.1-Micrometers Laser

    DTIC Science & Technology

    2015-09-01

    fibers of undoped clad (~ ∅ 200 μm), Tm-doped clad (~ ∅ 75 μm), and Ho-doped core (~ ∅ 23 μm). Through the 2-for-1 process, a single 808-nm diode light ...ARL-TR-7452 ● SEP 2015 US Army Research Laboratory Diode -Pumped Thulium (Tm)/Holmium (Ho) Composite Fiber 2.1-μm Laser by G...is no longer needed. Do not return it to the originator. ARL-TR-7452 ● SEP 2015 US Army Research Laboratory Diode -Pumped Thulium

  6. First Spectroscopic Solutions of Two Southern Eclipsing Binaries: HO Tel and QY Tel

    NASA Astrophysics Data System (ADS)

    Sürgit, D.; Erdem, A.; Engelbrecht, C. A.; van Heerden, P.; Manick, R.

    2015-07-01

    We present preliminary results from the analysis of spectroscopic observations of two southern eclipsing binary stars, HO Tel and QY Tel. The grating spectra of these two systems were obtained at the Sutherland Station of the South African Astronomical Observatory in 2013. Radial velocities of the components were determined by the Fourier disentangling technique. Keplerian radial velocity models of HO Tel and QY Tel give their mass ratio as 0.921±0.005 and 1.089±0.007, respectively.

  7. Multicolor upconversion emission from Tm3++Ho3++Yb3+ codoped tellurite glass on NIR excitations

    NASA Astrophysics Data System (ADS)

    Giri, N. K.; Rai, D. K.; Rai, S. B.

    2008-06-01

    Multicolor emission has been produced using 798 nm and 980 nm laser excitation in a Tm3++Ho3++Yb3+ codoped tellurite based glass. This glass generates simultaneously red, green and blue (RGB) emission on 798 nm excitation. Multicolor emission thus obtained was tuned to white luminescence by adjusting the Ho3+ ion concentration. There is a close match between the calculated color coordinate for the white luminescence obtained here and the point of equal energy which represents white in the 1931 CIE chromaticity diagram. The 980 nm excitation of the same sample on the other hand gives intense green and red emission and the glass appears greenish.

  8. Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

    NASA Technical Reports Server (NTRS)

    May, R. D.; Molina, L. T.; Webster, C. R.

    1988-01-01

    A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

  9. High efficient actively Q-switched Ho:LuAG laser.

    PubMed

    Duan, Xiaoming; Yao, Baoquan; Li, Gang; Ju, Youlun; Wang, Yuezhu; Zhao, Guangjun

    2009-11-23

    We present the room temperature Q-switched performances of a Ho:LuAG laser operated at 2.1 microm. At the repetition rate of 10 kHz, the maximum average output power of 9.9 W with a slope efficiency of 69.9% relative to absorbed pump power was obtained in Ho:LuAG laser. Also, the minimum pulse width of 33.0 ns was obtained, corresponding to the peak power was 30.0 kW.

  10. Role of Entropy-Corrected New Agegraphic Dark Energy in Hořava-Lifshitz Gravity

    NASA Astrophysics Data System (ADS)

    Bagchi Khatua, Piyali; Chakraborty, Shuvendu; Debnath, Ujjal

    2013-02-01

    In this work, we have considered the entropy-corrected new agegraphic dark energy (ECNADE) model in Hořava-Lifshitz gravity in FRW universe. We have discussed the correspondence between ECNADE and other dark energy models such as DBI-essence, Yang-Mills dark energy, Chameleon field, Non-linear electrodynamics field and hessence dark energy in the context of Hořava-Lifshitz gravity and reconstructed the potentials and the dynamics of the scalar field theory which describe the ECNADE.

  11. The Effect of Temperature on the Radiative Performance of Ho-Yag Thin Film Selective Emitters

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Good, Brian S.

    1995-01-01

    We present the emitter efficiency results for the thin film 25 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) selective emitter from 1000 to 1700 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns) and used to calculate the radiative efficiency. The radiative efficiency and power density of rare earth doped selective emitters are strongly dependent on temperature and experimental results indicate an optimum temperature (1650 K for Ho YAG) for thermophotovoltaic (TPV) applications.

  12. Preparation of electrodeposited Zn-Ni-B alloy coatings

    NASA Astrophysics Data System (ADS)

    Sakai, Taro; Kamimoto, Yuki; Ichino, Ryoichi

    2016-01-01

    We prepared Zn-Ni-B alloys with high Zn content and high corrosion resistance. The composition of the alloys was controlled by potentiostatic electrolysis. In the electroplating bath, dimethylamineborane was used as the B source. The characterization of the alloys and corrosion resistance evaluation were carried out by X-ray diffraction (XRD) analysis, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Tafel plots, and cyclic corrosion tests. All films were categorized into three groups on the basis of the results of XRD analysis, and it was found by TEM analysis that the Ni-B-type showed an amorphous structure. The Ni-B-type could contain up to 50.6 mol % Zn and showed similar or better anticorrosion properties than the amorphous Ni-B films. In the Ni-B-type, the higher the Zn content, the higher the corrosion resistance. The Zn-Ni-B alloys had almost the same electrochemical corrosion resistance and Zn content as the Zn-Ni-P alloys.

  13. The HoMBReS and HoMBReS Por un Cambio Interventions to Reduce HIV Disparities Among Immigrant Hispanic/Latino Men.

    PubMed

    Rhodes, Scott D; Leichliter, Jami S; Sun, Christina J; Bloom, Fred R

    2016-02-12

    Hispanics/Latinos in the United States are affected disproportionately by human immunodeficiency virus (HIV) infection, acquired immunodeficiency syndrome (AIDS), and other sexually transmitted diseases (STDs); however, few effective evidence-based prevention interventions for this population exist. This report describes the Hombres Manteniendo Bienestar y Relaciones Saludables (Men Maintaining Wellbeing and Healthy Relationships) (HoMBReS) intervention, which was developed by a community-based, participatory research partnership in North Carolina and initially implemented during 2005-2009. HoMBReS is an example of an effective intervention that uses lay health advisors (known as Navegantes [navigators]) in the context of existing social networks (i.e., recreational soccer teams) to promote consistent condom use and HIV and STD testing among Hispanic/Latino men. In 2012, HoMBReS was classified as a best-evidence community-level HIV prevention intervention (CDC. Compendium of evidence-based behavioral interventions and best practices for HIV prevention. Atlanta, GA: US Department of Health and Human Services, CDC; 2015). The intervention has been implemented elsewhere, enhanced, and further evaluated in longitudinal intervention and implementation studies. HoMBReS has been adapted for other populations, including men who have sex with men and transgender persons. Additional evaluation has found that Navegantes continue in their roles as health advisors, opinion leaders, and community advocates after study support ends. Hispanic/Latino men's social networks can be leveraged to promote sexual health within the community by decreasing HIV risk behaviors among Hispanics/Latinos in the United States.

  14. The HoMBReS and HoMBReS Por un Cambio Interventions to Reduce HIV Disparities Among Immigrant Hispanic/Latino Men

    PubMed Central

    Rhodes, Scott D.; Leichliter, Jami S.; Sun, Christina J.; Bloom, Fred R.

    2016-01-01

    Summary Hispanics/Latinos in the United States are affected disproportionately by human immunodeficiency virus (HIV) infection, acquired immunodeficiency syndrome (AIDS), and other sexually transmitted diseases (STDs); however, few effective evidence-based prevention interventions for this population exist. This report describes the Hombres Manteniendo Bienestar y Relaciones Saludables (Men Maintaining Wellbeing and Healthy Relationships) (HoMBReS) intervention, which was developed by a community-based, participatory research partnership in North Carolina and initially implemented during 2005–2009. HoMBReS is an example of an effective intervention that uses lay health advisors (known as Navegantes [navigators]) in the context of existing social networks (i.e., recreational soccer teams) to promote consistent condom use and HIV and STD testing among Hispanic/Latino men. In 2012, HoMBReS was classified as a best-evidence community-level HIV prevention intervention (CDC. Compendium of evidence-based behavioral interventions and best practices for HIV prevention. Atlanta, GA: US Department of Health and Human Services, CDC; 2015). The intervention has been implemented elsewhere, enhanced, and further evaluated in longitudinal intervention and implementation studies. HoMBReS has been adapted for other populations, including men who have sex with men and transgender persons. Additional evaluation has found that Navegantes continue in their roles as health advisors, opinion leaders, and community advocates after study support ends. Hispanic/Latino men’s social networks can be leveraged to promote sexual health within the community by decreasing HIV risk behaviors among Hispanics/Latinos in the United States. PMID:26916740

  15. Effects of holmium substitution on multiferroic properties in Tb0.67Ho0.33MnO3

    NASA Astrophysics Data System (ADS)

    Staruch, M.; Lawes, G.; Kumarasiri, A.; Cotica, L. F.; Jain, M.

    2013-02-01

    In this work, the structural, electrical, and magnetic properties of orthorhombic TbMnO3 and Tb0.67Ho0.33MnO3 ceramics are presented. The lattice parameters and the Mn-O-Mn bond angle were found to decrease with Ho-substitution as evidenced by Rietveld refinement of the X-ray diffraction data and Raman spectroscopy measurements. A weak ferromagnetic moment was observed in both dc and ac magnetic measurements of the Ho-substituted sample possibly due to spin canting in the antiferromagnetic phase. Tb0.67Ho0.33MnO3 was confirmed to be multiferroic with appearance of spontaneous polarization below 25 K and an additional increase in polarization ˜15.5 K associated with the ordering of the Ho3+ moments.

  16. White Lighting Upconversion in Tm3+/Ho3+/Yb3+ Co-Doped CaWO4

    NASA Astrophysics Data System (ADS)

    Chung, Jun Ho; Yeop Lee, Sang; Shim, Kwang Bo; Ryu, Jeong Ho

    2012-05-01

    Controllable white upconversion (UC) luminescence was obtained from Tm3+/Ho3+/Yb3+-codoped CaWO4. Under the excitation of a 980 nm single wavelength laser diode, the Tm3+/Ho3+/Yb3+-codoped CaWO4 exhibited bright white UC luminescence composed of blue emission from Tm3+ and green and red emissions from Ho3+ visible to the naked eye. The intensity ratios of green, red, and blue UC emissions varied with Tm3+/Ho3+ concentrations, which can control white UC emission ranging from the cool to the warm region. Various white UC colors can be easily changed by adjusting the Tm3+/Ho3+ concentrations in the CaWO4 matrix.

  17. Magnetic properties of Ho{sub 1-x}Er{sub x}Al{sub 2} alloys

    SciTech Connect

    Khan, Mahmud; Paudyal, D.; Gschneidner, K. A. Jr.; Pecharsky, V. K.

    2013-05-07

    HoAl{sub 2} exhibits a first order spin reorientation transition at 20 K. Heat capacity measurements showed that when Ho is partially replaced by Er in Ho{sub 1-x}Er{sub x}Al{sub 2}, the spin reorientation transition is gradually suppressed, while slowly shifting to higher temperatures with increasing Er concentration. In this paper, we investigate the magnetic properties of pseudo binary Ho{sub 1-x}Er{sub x}Al{sub 2} alloys by ac and dc magnetization measurements. The magnetization data show that the magnetic interactions below T{sub C} are dramatically modified when Er is added in Ho{sub 1-x}Er{sub x}Al{sub 2}. For a better explanation of the experimental data, results of first principles calculations have been presented as well.

  18. Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. Part I. Spectrum of Ho I

    NASA Astrophysics Data System (ADS)

    Al-Labady, N.; Özdalgiç, B.; Er, A.; Güzelçimen, F.; Öztürk, I. K.; Kröger, S.; Kruzins, A.; Tamanis, M.; Ferber, R.; Başar, Gö.

    2017-02-01

    The Fourier Transform spectra of a Holmium hollow cathode discharge lamp have been investigated in the UV spectral range from 25,000 up to 31,530 cm‑1 (317 to 400 nm). Two Ho spectra have been measured with neon and argon as buffer gases. Based on the intensity ratios from these two spectra, a distinction was made between atomic and ionic lines (ionic lines are discussed in an accompanying paper). Using the known Ho i energy levels, 71 lines could be classified as transitions of atomic Ho, 34 of which have not been published previously. Another 32 lines, which could not be classified, are listed in the literature and assigned as atomic Ho. An additional 370 spectral lines have been assigned to atomic Ho based on the signal-to-noise ratio in the two spectra measured under different discharge conditions, namely with buffer gases argon and neon, respectively. These 370 lines have not been previously listed in the literature.

  19. Pinocembrin Suppresses H2O2-Induced Mitochondrial Dysfunction by a Mechanism Dependent on the Nrf2/HO-1 Axis in SH-SY5Y Cells.

    PubMed

    de Oliveira, Marcos Roberto; da Costa Ferreira, Gustavo; Brasil, Flávia Bittencourt; Peres, Alessandra

    2017-01-13

    Mitochondria are susceptible to redox impairment, which has been associated with neurodegeneration. These organelles are both a source and target of reactive species. In that context, there is increasing interest in finding natural compounds that modulate mitochondrial function and mitochondria-related signaling in order to prevent or to treat diseases involving mitochondrial impairment. Herein, we investigated whether and how pinocembrin (PB) would prevent mitochondrial dysfunction elicited by the exposure of human neuroblastoma SH-SY5Y cells to hydrogen peroxide (H2O2). PB (25 μM) was administrated for 4 h before H2O2 treatment (300 μM for 24 h). PB prevented H2O2-induced loss of cell viability mitochondrial depolarization in SH-SY5Y cells. PB also attenuated redox impairment in mitochondrial membranes. The production of superoxide anion radical (O2(-•)) and nitric oxide (NO(•)) was alleviated by PB in cells exposed to H2O2. PB suppressed the H2O2-induced inhibition of the tricarboxylic acid (TCA) cycle enzymes aconitase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Furthermore, PB induced anti-inflammatory effects by abolishing the H2O2-dependent activation of the nuclear factor-κB (NF-κB) and upregulation of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The PB-induced antioxidant and anti-inflammatory effects are dependent on the heme oxygenate-1 (HO-1) enzyme and on the activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), since HO-1 inhibition (with 0.5 μM ZnPP IX) or Nrf2 silencing (with small interfering RNA (siRNA)) abolished the effects of PB. Overall, PB afforded cytoprotection by the Nrf2/HO-1 axis in H2O2-treated SH-SY5Y cells.

  20. Kinetics of the reactions of HBr with O{sub 3} and HO{sub 2}: The yield of HBr from HO{sub 2} + BrO

    SciTech Connect

    Mellouki, A.; Talukdar, R.K.; Howard, C.J.

    1994-11-20

    An upper limit on the yield of HBr from reaction (R1) (HO{sub 2} + BrO {yields} products) has been determined by measuring an upper limit for the rate coefficient of the reverse reaction (R1{prime}) (HBr + O{sub 3} {yields} HO{sub 2} + BrO). The limits measured at 300 and 441 K were extrapolated to low temperatures to determine that the yield of HBr from reaction (R1) is negligible throughout the stratosphere (<0.01% of k{sub 1}). An upper limit for the rate coefficient of the reaction of HO{sub 2} with HBr was also determined to be very low {le} 3 x 10{sup {minus}17}cm{sup 3}molecule{sup {minus}1}s{sup {minus}1} at 300 K and {le} 3 x 10{sup {minus}16}cm{sup 3}molecule{sup {minus}1}s{sup {minus}1} at 400 K. The implications of these results to stratospheric chemistry are discussed. 18 refs., 1 fig., 6 tabs.

  1. The dynamics of diluted Ho spin ice Ho2-xYxTi2O7 studied byneutron spin echo spectroscopy

    SciTech Connect

    Ehlers, G.; Gardner, J.S.; Booth, C.H.; Daniel, M.; Kam, K.C.; Cheetham, A.K.; Antonio, D.; Brooks, H.E.; Cornelius, A.L.; Bramwell,S.T.; Lago, J.; Haussler, W.; Rosov, N.

    2006-02-27

    We have studied the spin relaxation in diluted spin ice Ho{sub 2-x} Y{sub x} Ti{sub 2}O{sub 7} by means of neutron spin echo spectroscopy. Remarkably, the geometrical frustration is not relieved by doping with non-magnetic Y, and the dynamics of the freezing is unaltered in the spin echo time window up to x {approx_equal} 1.6. At higher doping with non-magnetic Y (x {ge} 1.6) a new relaxation process at relatively high temperature (up to at least T {approx_equal} 55 K) appears which is more than 10 times faster than the thermally activated main relaxation process. We find evidence that over the whole range of composition all Ho spins participate in the dynamics. These results are compared to a.c. susceptibility measurements of the diluted Ho and Dy spin ice systems. X-ray absorption fine structure (EXAFS) spectra and x-ray diffraction show that the samples are structurally well ordered.

  2. Rainfall and Wind Patterns Along the Equator During El Niño and La Niña Events in 2000-2014

    NASA Astrophysics Data System (ADS)

    Halpern, David

    2015-04-01

    Four El Niño events and six La Niña events occurred from March 2000 - February 2014 in the Oceanic Niño Index for the Niño 3.4 region. In the west Pacific from 150°E-150°W the surface westward wind speed in El Niño was considerably smaller than in La Niña. At the upper troposphere (13-15 km), the eastward wind speed was larger in El Niño than in La Niña. Both wind patterns were consistent with conventional wisdom of an eastward or westward longitudinal shift of the surface zonal winds of the Walker Circulation during El Niño or La Niña. However, in the east Pacific from 150°W-90°W the surface westward wind speed in El Niño was larger than in La Niña, which was not consistent with a local wind-generated thermocline depth deeper in El Niño than in La Niña. The influence of central Pacific El Niños in 2000-2014, when the sea surface temperature anomaly (SSTA) was strongest in the central Pacific, compared to 1980-1999, when the El Niño SSTA was largest in the eastern Pacific, will be discussed. This paper will review the zonal wind observations, including those at 10-m and 14-km heights in the Atlantic Ocean, where increased vertical shear during El Niño would suppress the formation of hurricanes. This paper will also examine the movements of the longitudinal position in El Niño and La Niña of the sharp zonal gradient of rainfall, which normally occurs near 170°W. In March 2000 - February 2014 the average annual amounts of rainfall in the west and east Pacific were 1.7 and 0.4 mm/hr, respectively; each value was fairly uniform over a large longitudinal region. Data sources were 10-m height wind vectors recorded by ASCAT-on-MetOp-A and SeaWinds-on-QuikSCAT, wind vectors at many troposphere heights by MISR-on-Terra, and rainfall by TMI-on-TRMM.

  3. Natural nanomorphous Ni/NiO magnetic multilayers: structure and magnetism of the high-Ar pressure series.

    PubMed

    Pappas, S D; Delimitis, A; Kapaklis, V; Papaioannou, E Th; Poulopoulos, P; Trachylis, D; Velgakis, M J; Politis, C

    2014-08-01

    Natural nanomorphous Ni/NiO multilayers have exhibited interesting magnetic properties, such as an unusual positive surface anisotropy and perpendicular magnetic anisotropy. Most attention has been paid to multilayers prepared by radio frequency magnetron sputtering under relatively low (3 x 10(-3) mbar) Ar pressure. Here we report on the correlation between structural and magnetic properties for a new series of multilayers, prepared under relatively high (3 x 10(-2) mbar) Ar pressure. The crystalline Ni individual layer thickness ranges between 5-8 nm. The amorphous NiO layer thickness is constant, about 1.1 nm thick. X-ray reflectivity showed that in some of the multilayers the high-order Bragg peaks become broader and diminish quickly. Cross-section transmission electron microscopy reveals that this occurs because the first bilayers are formed in accordance to the growth conditions, while the ones near the top are vanished. Despite the deterioration of the interface quality, all samples show tendency for perpendicular magnetic anisotropy even for large bilayer thickness of about 9 nm. Similar tendency is observed even by a 330 nm thick non-multilayered Ni film grown under the same conditions. This observation reveals the important role of strain and magnetoelastic anisotropy as a source of perpendicular magnetic anisotropy in the Ni/NiO multilayers.

  4. El Niño's impact on California precipitation: seasonality, regionality, and El Niño intensity

    NASA Astrophysics Data System (ADS)

    Jong, Bor-Ting; Ting, Mingfang; Seager, Richard

    2016-05-01

    California has experienced severe drought in recent years posing great challenges to agricultural production, water resources, and land management. El Niño, as the prime source of seasonal to interannual climate predictability, offers the potential of amelioration of drought in California. Here El Niño’s impacts on California winter precipitation are examined, focusing on variations by season, region, and the strength of El Niño using observational data for the period 1901-2010. The El Niño influence on California precipitation strengthens from early to late winter and is stronger in the south than the north. Eight of ten moderate-to-strong El Niños in the late winter put southern California in the wettest tercile and none of these ten events put northern California in the driest tercile. The early to late winter strengthening of the El Niño impact on precipitation occurs even as El Niño weakens and is associated with a strengthening and eastward extending tropical deep convection anomaly allowed by the late winter warming of the climatological mean sea surface temperature over the tropical eastern Pacific.

  5. Heme Oxygenase-1 (HO-1) Expression in Prostate Cancer Cells Modulates the Oxidative Response in Bone Cells

    PubMed Central

    Ferrando, Mercedes; Wan, Xinhai; Meiss, Roberto; Yang, Jun; De Siervi, Adriana; Navone, Nora; Vazquez, Elba

    2013-01-01

    Prostate cancer (PCa) is a leading cause of death among males. It is currently estimated that inflammatory responses are linked to 15-20% of all deaths from cancer worldwide. PCa is dominated by complications arising from metastasis to the bone where the tumor cells interact with the bone microenvironment impairing the balance between bone formation and degradation. However, the molecular nature of this interaction is not completely understood. Heme oxygenase-1 (HO-1) counteracts oxidative damage and inflammation. Previous studies from our laboratory showed that HO-1 is implicated in PCa, demonstrating that endogenous HO-1 inhibits bone derived-prostate cancer cells proliferation, invasion and migration and decreases tumor growth and angiogenesis in vivo. The aim of this work was to analyze the impact of HO-1 modulated PCa cells on osteoblasts proliferation in vitro and on bone remodeling in vivo. Using a co-culture system of PC3 cells with primary mice osteoblasts (PMOs), we demonstrated that HO-1 pharmacological induction (hemin treatment) abrogated the diminution of PMOs proliferation induced by PCa cells and decreased the expression of osteoclast-modulating factors in osteoblasts. No changes were detected in the expression of genes involved in osteoblasts differentiation. However, co-culture of hemin pre-treated PC3 cells (PC3 Hem) with PMOs provoked an oxidative status and activated FoxO signaling in osteoblasts. The percentage of active osteoblasts positive for HO-1 increased in calvarias explants co-cultured with PC3 Hem cells. Nuclear HO-1 expression was detected in tumors generated by in vivo bone injection of HO-1 stable transfected PC3 (PC3HO-1) cells in the femur of SCID mice. These results suggest that HO-1 has the potential to modify the bone microenvironment impacting on PCa bone metastasis. PMID:24224047

  6. High Pressure synchrotron XRD and Raman studies of Ho0.5Y1.5Ti2O7

    NASA Astrophysics Data System (ADS)

    White, Melanie; Kumar, Ravhi; Baker, Jason; Light, Brian

    Pyrochlore oxides are of interest for their spin-frustrated systems and their proposed use in high-level nuclear waste management. We sought to examine the structural stability of these materials under extreme conditions in order to help determine their viability for applications. A compression and decompression study of Ho0.5Y1.5Ti2O7 was done in approximately 5 GPa intervals to above 55 GPa with both synchrotron powder x-ray diffraction at the Argonne National Laboratory Advanced Photon Source, and Raman spectroscopy at the University of Nevada - Las Vegas High Pressure Science and Engineering Center (HiPSEC). In both studies, pressurization of sample was achieved using a symmetric-style diamond anvil cell (DAC). The results are compared with the high pressure behavior of other rare earth titanates. A reversible phase transition is observed between 45 and 49 GPa in both studies. The x-ray diffraction patterns are analyzed in order to identify the crystal structure of the new phase. Vibrational modes are assigned to the Raman spectra and tracked as a function of pressure. Our poster will discuss the results in detail. This research was sponsored by the NNSA under the SSAA program through the DOE Cooperative Agreement #DE-NA0001982. Portions of this study were performed at HPCAT (Sector 16) Advanced Photon Source (APS), Argonne National Laboratory.

  7. Modulating the reactivity of Ni-containing Pt(111)-skin catalysts by density functional theory calculations.

    PubMed

    Su, Hai-Yan; Bao, Xin-He; Li, Wei-Xue

    2008-05-21

    We present here a first principles density functional theory investigation of the reactivity of Pt(111)-skin catalysts, which are varied from surface alloys with Ni to bulk PtxNi 1-x (x=0.25,0.50,0.75) alloys. Molecule (CO, O, and H) adsorption and oxidation of CO+O and H+O reactions were studied and analyzed in detail. Independent of the adsorbates, the interaction between adsorbates and substrates becomes weakened with increase in Ni, due to the downshift of d-band center of surface Pt atoms. Moreover, activation barriers of CO and H oxidation toward atomic oxygen gradually decrease. In term of CO preferential oxidation (PROX) in excess of hydrogen, it turns out that the overall reactivity and selectivity rely on the optimum of various elementary steps involved such as competitive molecular (dissociative) adsorption and oxidation reaction. The present calculations show that Pt3Ni(111) with Pt overlayer is an optimum catalyst for CO PROX in excess of hydrogen.

  8. Anti-Inflammatory Effect of Angelica gigas via Heme Oxygenase (HO)-1 Expression.

    PubMed

    Cho, Joon Hyeong; Kwon, Jung Eun; Cho, Youngmi; Kim, Inhye; Kang, Se Chan

    2015-06-15

    Angelica gigas (AG) is effective against various medical conditions such as bacterial infection, inflammation, and cancer. It contains a number of coumarin compounds and the group of interest is the pyranocoumarin, which comprises decursin and decursinol angelate. This group has an effect on controlling inflammation, which is caused by excessive nitric oxide (NO) production. Heme oxygenases (HOs), particularly HO-1, play a role in regulating the production of NO. Thus, this study aimed to investigate the anti-inflammatory effects of AG by measuring HO-1 expression. Treatments with CH2Cl2 layer and Angelica gigas extract (AGE) showed the highest NO inhibition effects. Decursin, decursinol angelate, and nodakenin were isolated from the CH2Cl2 layer of AGE. Decursin also demonstrated the highest anti-oxidative effect among the coumarins. Although decursin had the best NO inhibition and anti-oxidative effects, the effects of AGE treatment far surpassed that of decursin. This is owing to the combination effect of the coumarins present within AGE, which is a solvent extract of AG. The expression of HO-1 is an effective indicator of the anti-inflammatory effects of AG. Based on the results of the coumarin compounds, HO-1 expression was found to be dose dependent and specific to decursin.

  9. No-go theorem for slowly rotating black holes in Hořava-Lifshitz gravity.

    PubMed

    Barausse, Enrico; Sotiriou, Thomas P

    2012-11-02

    We consider slowly rotating, stationary, axisymmetric black holes in the infrared limit of Hořava-Lifshitz gravity. We show that such solutions do not exist, provided that they are regular everywhere apart from the central singularity. This has profound implications for the viability of the theory, considering the astrophysical evidence for the existence of black holes with nonzero spin.

  10. Magnetism and superconductivity in Eu(Ho)Mo/sub 6/S/sub 8/

    SciTech Connect

    Capone, D.W. II; Lai Fook, M.S.; Guertin, R.P.; Hinks, D.G.; Dunlap, B.D.; Foner, S.; Abou-Aly, A.I.; Brooks, J.S.

    1984-10-01

    A variety of ambient and high pressure experimental results reveal the interplay between magnetism and superconductivity in Ho doped samples of the pressure induced superconductor, EuMo/sub 6/S/sub 8/. Ho concentrations up to 50 atomic percent of the rare earth ions were used. High resolution magnetic measurements are consistent with the crystalline electric field ground state for the Ho/sup 3 +/ ions being a magnetic doublet consisting largely of J/sub z/ = 18. The results of high pressure magnetization experiments reveal negligible effects of reduced lattice constant on the rare earth-rare earth interactions. Resistivity in a 10 atomic percent sample for P = 10 kbar shows the suppression of a P = 0 structural transition, metallic conductivity down to low temperatures, and finally superconductivity at 8 K. The upper critical field, H/sub c2/(T), for this sample was measured for P = 7, 10 and 12 kbar and showed strong reentrant behavior (dH/sub c2/(T)/dT > 0 as T ..-->.. 0 K). A minimum with field in the resistivity above H/sub c2/ was also observed at lowest temperatures. The H/sub c2/(T) data are compared with those of EuMo/sub 6/S/sub 8/ at high pressure, which shows positive curvature, and HoMo/sub 6/S/sub 8/, in which superconductivity is quenched by ferromagnetism at low temperatures. 14 references, 4 figures.

  11. Efficient Operation of Conductively Cooled Ho:Tm:LuLiF Laser Oscillator/Amplifier

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Bai, Yingxin; Trieu, Bo; Petros, M.; Petzar, Paul; Lee, Hyung; Singh, U.

    2008-01-01

    A conductively-cooled Ho:Tm:LuLiF laser oscillator generates 1.6J normal mode pulses at 10Hz with optical to optical efficiency of 20%. When the laser head module is used as the amplifier, the double-pass small-signal amplification excesses 25.

  12. Frustrated spin correlations in diluted spin ice Ho2-xLaxTi2O7

    SciTech Connect

    Ehlers, Georg; Ehlers, G.; Mamontov, E.; Zamponi, M.; Faraone, A.; Qiu, Y.; Cornelius, A.L.; Booth, C.H.; Kam, K.C.; Le Toquin, R.; Cheetham, A.K.; Gardner, J.S.

    2008-04-30

    We have studied the evolution of the structural properties as well as the static and dynamic spin correlations of spin ice Ho2Ti2O7, where Ho was partially replaced by non-magnetic La. The crystal structure of diluted samples Ho2-xLaxTi2O7 was characterized by x-ray and neutron diffraction and by Ho L-III-edge and Ti K-edge extended x-ray absorption fine structure (EXAFS) measurements. It is found that the pyrochlore structure remains intact until about x = 0.3, but a systematic increase in local disorder with increasing La concentration is observed in the EXAFS data, especially from the Ti K edge.Quasi-elastic neutron scattering and ac susceptibility measurements show that, in x<= 0.4 samples at temperatures above macroscopic freezing, the spin -spin correlations are short ranged and dynamic in nature. The main difference with pure spin ice in the dynamics is the appearance of a second, faster, relaxation process.

  13. Reaction Kinetics of HBr with HO2: A New Channel for Isotope Scrambling Reactions.

    PubMed

    Church, Jonathan R; Skodje, Rex T

    2016-11-03

    The gas phase reaction kinetics of HBr with the HO2 radical are investigated over the temperature range of T = 200-1500 K using a theoretical approach based on transition state theory. The parameters for the potential energy surface are computed using density functional theory with the M11 exchange functional. The rate coefficient for the HBr + HO2 → Br + H2O2 abstraction channel is found to be somewhat larger than previous estimates at low temperatures due to quantum tunneling. The present study reveals the existence of a novel exchange pathway, HBr + H'O2 → H'Br + HO2, which exhibits a much lower reaction barrier than does the abstraction route. The transition state for this process is a symmetrical planar five-membered-ring-shaped structure. At low temperatures, this concerted double hydrogen transfer reaction is several orders of magnitude faster than the abstraction channel. The exchange process may be observed using isotope scrambling reactions; such reactions may contribute to observed isotope abundances in the atmosphere. The rate coefficients for the isotopically labeled reactions are computed.

  14. Etiology and outcome of chronic renal failure in hospitalized children in Ho Chi Minh City, Vietnam.

    PubMed

    Mong Hiep, Tran Thi; Janssen, Françoise; Ismaili, Khalid; Khai Minh, Dang; Vuong Kiet, Doan; Robert, Annie

    2008-06-01

    The aim of this study was to investigate the etiology and treatment modalities and to determine mortality risks in hospitalized children with chronic renal failure (CRF) in Ho Chi Minh City, Vietnam. We reviewed the records of 310 children with CRF hospitalized in Ho Chi Minh City from January 2001 to December 2005. The average annual number cases was 4.8 per million child population native to Ho Chi Minh City. Median age was 14 years; 85% of patients were in end-stage renal failure. Associated illnesses were anemia (96%), hypertension (74%), and cardiopulmonary diseases (39%). Causes of included glomerulonephritis (30%) and congenital/hereditary anomalies (20%), but in 50% of children, the etiology was unavailable. Seventy-three percent of cases with end-stage renal failure did not benefit from renal replacement therapy. During hospitalization, 47 patients (15%) died. Mortality risks were higher in young children (1-4 years), in boys, and in patients with acquired pathologies. Severe metabolic acidosis was the main predictive factor of mortality by multivariate regression analysis. Our data shows a poor outcome due to late referral and limited facilities for renal replacement therapy in children with CRF hospitalized in Ho Chi Minh City.

  15. Conventional and anisotropic magnetic entropy change in HoAl2 ferromagnetic compound

    NASA Astrophysics Data System (ADS)

    Gil, L. A.; Campoy, J. C. P.; Plaza, E. J. R.; de Souza, M. V.

    2016-07-01

    In this paper, we present theoretical investigations on the conventional and anisotropic magnetocaloric effects in the cubic HoAl2 ferromagnetic compound. They are investigated in terms of a Hamiltonian that takes into account the Zeeman and exchange magnetic interactions, and crystalline electric field. In this study we have explored recent experimental results in HoAl2 single crystals and polycrystalline samples. HoAl2 presents a spin reorientation transition at 20 K and different signatures of this phenomenon are reproduced in our calculations. In addition, we have calculated the anisotropic variation of magnetic entropy that corresponds to a rotation of a HoAl2 single crystal from its [110] towards its [100] direction in the presence of a constant applied magnetic field. The intensity of the anisotropic effect is twice that one of the conventional effect at spin reorientation region. A subtle signature of the spin reorientation is also observed in the [111] direction. We conclude that the crystal electric field term plays the principal role to describe the main magnetic characteristics of the system, not being necessary to include in the Hamiltonian others effects such as elastic or high order magnetic interactions.

  16. Enhanced spin - Reorientation temperature and origin of magnetocapacitance in HoFeO3

    NASA Astrophysics Data System (ADS)

    Kotnana, Ganesh; Jammalamadaka, S. Narayana

    2016-11-01

    We report on the increase in the spin reorientation temperature in HoFe0.5Cr0.5O3 compound by isovalent substitution (Cr3+) at the Fe-site and the magnetocapacitance in the HoFeO3 compound. Spin reorientation transition is evident around 50 K and 150 K for the x=0 and x=0.5 compounds respectively. The increase in the spin reorientation transition temperature in case of x=0.5 compound can be attributed to the domination of the Ho3+-Fe3+ interaction over the Fe3+-Fe3+ interaction. Decrease in Néel temperature from 643 K (x=0) to 273 K (x=0.5) can be ascribed to the decrease in the interaction between antiferromagnetically aligned Fe3+ moments as a result of the dilution of the Fe3+ moments with the Cr3+ addition. From the magnetization M vs. magnetic field H variation it is evident that the coercivity, HC decreases for x=0.5 compound, hinting the magnetic softening of the HoFeO3 compound. Observed magnetocapacitance could be due to lossy dielectric mechanism in the present compound. Indeed, present results would be helpful in understanding the physics behind rare-earth orthoferrites.

  17. Anti-Inflammatory Effect of Angelica gigas via Heme Oxygenase (HO)-1 Expression

    PubMed Central

    Cho, Joon Hyeong; Kwon, Jung Eun; Cho, Youngmi; Kim, Inhye; Kang, Se Chan

    2015-01-01

    Angelica gigas (AG) is effective against various medical conditions such as bacterial infection, inflammation, and cancer. It contains a number of coumarin compounds and the group of interest is the pyranocoumarin, which comprises decursin and decursinol angelate. This group has an effect on controlling inflammation, which is caused by excessive nitric oxide (NO) production. Heme oxygenases (HOs), particularly HO-1, play a role in regulating the production of NO. Thus, this study aimed to investigate the anti-inflammatory effects of AG by measuring HO-1 expression. Treatments with CH2Cl2 layer and Angelica gigas extract (AGE) showed the highest NO inhibition effects. Decursin, decursinol angelate, and nodakenin were isolated from the CH2Cl2 layer of AGE. Decursin also demonstrated the highest anti-oxidative effect among the coumarins. Although decursin had the best NO inhibition and anti-oxidative effects, the effects of AGE treatment far surpassed that of decursin. This is owing to the combination effect of the coumarins present within AGE, which is a solvent extract of AG. The expression of HO-1 is an effective indicator of the anti-inflammatory effects of AG. Based on the results of the coumarin compounds, HO-1 expression was found to be dose dependent and specific to decursin. PMID:26083119

  18. Transport properties of Ho1- x Lu x B12 solid solutions

    NASA Astrophysics Data System (ADS)

    Gabáni, S.; Bat'ko, I.; Bat'ková, M.; Flachbart, K.; Gaz̆o, E.; Pristás̆, G.; Takác̆ová, I.; Bogach, A. V.; Sluchanko, N. E.; Shitsevalova, N. Yu.

    2013-05-01

    Our studies of Ho1- x Lu x B12 solid solutions have shown that the temperature of antiferromagnetic (AF) order in geometrically frustrated system of HoB12 ( T N = 7.4 K) is linearly suppressed to zero temperature, i.e. T N → 0, as lutetium concentration increases to x→ x c ≈ 0.9. In this contribution, we present original results of electrical resistivity measurements on Ho1- x Lu x B12 single crystalline samples with x = 0, 0.2, 0.5, 0.7, 0.9, 1 in the temperature range 0.06-300 K and in magnetic fields ( B) up to 8 T. Complex B vs T N phase diagrams were received from precise temperature ρ( T) and field ρ( B) dependences of resistivity with several AF phases for x ≤ 0.5 pointing to a possibility of quantum critical point at x c ≈ 0.9. The scattering of conduction electrons in the AF phase and in the paramagnetic phase as well as Hall effect results are analyzed and discussed for various concentrations x, when magnetic dilution increases with the increasing content of nonmagnetic Lu ions in the Ho1- x Lu x B12 system.

  19. HoBi-like viruses – the typical 'atypical bovine pestivirus'

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoBi-like viruses, also referred to as bovine viral diarrhea virus 3 (BVDV-3) and atypical pestivirus, have been proposed as a new putative bovine pestivirus species. These viruses were first identified in the last decade and are currently distributed in at least three continents. Published findings...

  20. Clinical presentation resembling mucosal disease associated with 'HoBi'-like pestivirus in a field outbreak

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Pestivirus of the family Flaviviridae consists of four recognized species: Bovine viral diarrhea virus 1 (BVDV-1), Bovine viral diarrhea virus 2 (BVDV-2), Classical swine fever virus (CSFV) And Border disease virus (BDV). Recently, atypical pestiviruses (‘HoBi’-like pestiviruses) were iden...

  1. Diabetes Control among Vietnamese Patients in Ho Chi Minh City: An Observational Cross-Sectional Study

    ERIC Educational Resources Information Center

    Yokokawa, Hirohide; Khue, Nguyen Thy; Goto, Aya; Nam, Tran Quang; Trung, Tran The; Khoa, Vo Tuan; Ngoc, Nguyen Thi Boi; Minh, Pham Nghiem; Vinh, Nguyen Quang; Okayama, Akira; Yasumura, Seiji

    2010-01-01

    The objective of this study was to assess the extent of diabetic control and its associated factors among Vietnamese patients with diabetes mellitus (DM). The study was conducted among 652 outpatients who were recruited at a public general hospital (People Hospital 115) and a private clinic (Medic Center) in Ho Chi Minh City, Vietnam. Median age…

  2. Theoretical Study on Mechanism of Reaction of OH with HO2NO2

    NASA Astrophysics Data System (ADS)

    Tian, Yan; He, Tian-jing; He, Li; Liu, Fan-chen; Chen, Dong-ming

    2008-02-01

    The reaction of HO2NO2 (peroxynitric acid, PNA) with OH was studied by the hybrid density functional B3LYP and CBS-QB3 methods. Based on the calculated potential energy surface, five reaction channels, H2O+NO2+O2, HOOH+NO3, NO2+HO3H, HO2+HONO2 and HO2+HOONO, were examined in detail. The major reaction channel is PNA+OH→M1→TS1→H2O+NO2+O2. Taking a pre-equilibrium approximation and using the CBS-QB3 energies, the theoretical rate constant of this channel was calculated as 1.13 × 10-12 cm3/(molecule s) at 300 K, in agreement with the experimental result. Comparison between reactions of HOONO2+OH and HONO2+OH was carried out. For HOR+OH reactions, the total rate constants increase from R=NO2 to R=ONO2, which is consistent with experimental measurements.

  3. High Repetition Rate and Frequency Stabilized Ho:YLF Laser for CO2 Differential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petros, M.; Petzar, Pau; Trieu, Bo; Lee, Hyung; Singh, U.

    2009-01-01

    High repetition rate operation of an injection seeded Ho:YLF laser has been demonstrated. For 1 kHz operation, the output pulse energy reaches 5.8mJ and the optical-to-optical efficiency is 39% when the pump power is 14.5W.

  4. Aprotinin Inhibits Vascular Smooth Muscle Cell Inflammation and Proliferation via Induction of HO-1

    PubMed Central

    Lee, Dong Hyup; Choi, Hyoung Chul; Lee, Kwang Youn

    2009-01-01

    Aprotinin is used clinically in cardiopulmonary bypass surgery to reduce transfusion requirements and the inflammatory response. The mechanism of action for the anti-inflammatory effects of aprotinin is still unclear. We examined our hypothesis whether inhibitory effects of aprotinin on cytokine-induced inducible nitric oxide synthase (iNOS) expression (IL-1β plus TNF-α), reactive oxygen species (ROS) generation, and vascular smooth muscle cell (VSMC) proliferation were due to HO-1 induction in rat VSMCs. Aprotinin induced HO-1 protein expression in a dose-dependent manner, which was potentiated during inflammatory condition. Aprotinin reduced cytokine mixture (CM)-induced iNOS expression in a dose dependent manner. Furthermore, aprotinin reduced CM-induced ROS generation, cell proliferation, and phosphorylation of JNK but not of P38 and ERK1/2 kinases. Aprotinin effects were reversed by pre-treatment with the HO-1 inhibitor, tin protoporphyrin IX (SnPPIX). HO-1 is therefore closely involved in inflammatory-stimulated VSMC proliferation through the regulation of ROS generation and JNK phosphorylation. Our results suggest a new molecular basis for aprotinin anti-inflammatory properties. PMID:19885007

  5. ETV Report:Siemens Model H-4XE-HO Open Channel UV System

    EPA Science Inventory

    Verification testing of the Siemens Barrier Sunligt H-4XE-HO UV System was completed at the UV Validation and Research Center of New York (UV Center), located in Johnstown, NY. The H-4XE System utilizes 16 high-output, low-pressure lamps oriented horizontally and parallel to the...

  6. String theory embeddings of nonrelativistic field theories and their holographic Hořava gravity duals.

    PubMed

    Janiszewski, Stefan; Karch, Andreas

    2013-02-22

    We argue that generic nonrelativistic quantum field theories with a holographic description are dual to Hořava gravity. We construct explicit examples of this duality embedded in string theory by starting with relativistic dual pairs and taking a nonrelativistic scaling limit.

  7. Highly Efficient Operation of Tm:fiber Laser Pumped Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Petros, M.; Yu, Jirong; Petzar, Paul; Trieu, Bo; Chen, Sam; Lee, Hyung; Singh, U.

    2006-01-01

    A 19 W, TEM(sub 00) mode, Ho:YLF laser pumped by continuous wave Tm:fiber laser has been demonstrated at the room temperature. The slope efficiency and optical-to-optical efficiency are 65% and 55%, respectively.

  8. Effect of Ho substitution on structure and magnetic properties of BiFeO{sub 3}

    SciTech Connect

    Suresh, Pittala; Srinath, S.; Babu, P. D.

    2014-05-07

    Structure and magnetic properties of trivalent Ho substituted BiFeO{sub 3} (Ho{sub x}Bi{sub 1−x}FeO{sub 3}) have been studied for the compositional range x = 0 to 0.2. The structure remains in rhombohedral R3c for x < 0.15, and further increase in x results a structural transition to orthorhombic Pnma. The decrease in Raman modes and the appearance of new mode at 475 cm{sup −1} confirms the structural changes. Ho doping at Bi site breaks the spin cycloid of BiFO{sub 3} and leads to the observation of ferromagnetic order at low temperatures. With increase in temperature, the M-H curves exhibit a pinching leading to double hysteresis loops. A minimum is observed in M-T curves for low fields at compensation temperature (Θ{sub C}) and H{sub C} attains a maximum close to Θ{sub C}. Variation of H{sub C} with temperature is discussed in terms of a model consisting of two sublattices. The improved magnetic properties achieved by Ho doping enhance the potential of BiFeO{sub 3} for multiferroic applications.

  9. Magnetic ordering in Ho{sub 2}Fe{sub 2}Si{sub 2}C

    SciTech Connect

    Susilo, R. A. Cadogan, J. M.; Cobas, R.; Hutchison, W. D.; Campbell, S. J.; Avdeev, M.

    2015-05-07

    We have used neutron diffraction and {sup 57}Fe Mössbauer spectroscopy, complemented by magnetisation and specific heat measurements, to examine the magnetic ordering of Ho{sub 2}Fe{sub 2}Si{sub 2}C. We have established that Ho{sub 2}Fe{sub 2}Si{sub 2}C orders antiferromagnetically below T{sub N} = 16(1) K with a magnetic structure involving ordering of the Ho sublattice along the b-axis with a propagation vector k=[0 0 1/2 ]. {sup 57}Fe Mössbauer spectra collected below T{sub N} show no evidence of a magnetic splitting, demonstrating the absence of long range magnetic ordering of the Fe sublattice. A small line broadening is observed in the {sup 57}Fe spectra below T{sub N}, which is due to a transferred hyperfine field—estimated to be around 0.3 T at 10 K—from the Ho sublattice.

  10. Decay studies of {sup 145,147}Er, {sup 146}Ho and {sup 129}Nd

    SciTech Connect

    Ma, F.; Xu, S. W.; Zhou, X. H.; Xie, Y. X.; Zheng, Y.

    2011-11-30

    Based on a He-jet apparatus coupled with a tape transport system, Very neutron-deficient isotopes {sup 145,147}Er, {sup 146}Ho, and {sup 129}Nd were identified by p-{gamma}(X) or {gamma}-{gamma}(X) coincidence measurements, and their radioactive decay properties were studied.

  11. Ac susceptibility of Ho (Fe,CO)11Ti compounds and their hydrides

    NASA Astrophysics Data System (ADS)

    Tabatabai Yazdi, Sh.; Motevalizadeh, L.

    2015-04-01

    The structural characterization and ac susceptibility behavior of polycrystalline samples of HoFe11-xCoxTiHy (x=1, 2, 4, 6, 7, 9, 11 and y=0, 1) intermetallics are investigated. All compounds crystallize in tetragonal ThMn12-type structure. The replacement of Fe by Co causes the lattice constants to decrease, while hydrogen insertion leads to cell volume expansion. A spin-reorientation (SR) transition from a uniaxial to cone/planar structure is observed for the HoFe11-xCoxTi compounds of higher Co content (x>7). By hydrogenation, SR transition appears in all samples due to relative reinforcement of Ho contribution to anisotropy. TSR values increase by Co-content because of the preferential substitution of Fe by Co atoms and consequently, concentration-dependence of contribution of transition metal sublattice to anisotropy, as well as that of Ho. The concentration-dependence of magnetization direction and hydrogen-induced SR in the studied samples are discussed in the framework of two-magnetic sublattice model by bearing in mind the temperature-dependent competition of their anisotropies and dependence of magnetic anisotropy on crystal field interactions.

  12. Using transurethral Ho:YAG-laser resection to treat urethral stricture and bladder neck contracture

    NASA Astrophysics Data System (ADS)

    Bo, Juanjie; Dai, Shengguo; Huang, Xuyuan; Zhu, Jing; Zhang, Huiguo; Shi, Hongmin

    2005-07-01

    Objective: Ho:YAG laser had been used to treat the common diseases of urinary system such as bladder cancer and benign prostatic hyperplasia in our hospital. This study is to assess the efficacy and safety of transurethral Ho:YAG-laser resection to treat the urethral stricture and bladder neck contracture. Methods: From May 1997 to August 2004, 26 cases of urethral stricture and 33 cases of bladder neck contracture were treated by transurethral Ho:YAG-laser resection. These patients were followed up at regular intervals after operation. The uroflow rate of these patients was detected before and one-month after operation. The blood loss and the energy consumption of holmium-laser during the operation as well as the complications and curative effect after operation were observed. Results: The therapeutic effects were considered successful, with less bleeding and no severe complications. The Qmax of one month postoperation increased obviously than that of preoperation. Of the 59 cases, restenosis appeared in 11 cases (19%) with the symptoms of dysuria and weak urinary stream in 3-24 months respectively. Conclusions: The Ho:YAG-laser demonstrated good effect to treat the obstructive diseases of lower urinary tract such as urethral stricture and bladder neck contracture. It was safe, minimal invasive and easy to operate.

  13. Catalase prevents maternal diabetes-induced perinatal programming via the Nrf2-HO-1 defense system.

    PubMed

    Chang, Shiao-Ying; Chen, Yun-Wen; Zhao, Xin-Ping; Chenier, Isabelle; Tran, Stella; Sauvé, Alexandre; Ingelfinger, Julie R; Zhang, Shao-Ling

    2012-10-01

    We investigated whether overexpression of catalase (CAT) in renal proximal tubular cells (RPTCs) could prevent the programming of hypertension and kidney disease in the offspring of dams with maternal diabetes. Male offspring of nondiabetic and diabetic dams from two transgenic (Tg) lines (Hoxb7-green fluorescent protein [GFP]-Tg [controls] and Hoxb7/CAT-GFP-Tg, which overexpress CAT in RPTCs) were studied from the prenatal period into adulthood. Nephrogenesis, systolic blood pressure, renal hyperfiltration, kidney injury, and reactive oxygen species (ROS) generation were assessed. Gene expression of transforming growth factor-β1 (TGF-β1), nuclear factor erythroid 2p45-related factor-2 (Nrf2), and heme oxygenase-1 (HO-1) was tested in both in vitro and in vivo studies. Renal dysmorphogenesis was observed in offspring of Hoxb7-GFP-Tg dams with severe maternal diabetes; the affected male offspring displayed higher renal ROS generation and developed hypertension and renal hyperfiltration as well as renal injury with heightened TGF-β1 expression in adulthood. These changes were ameliorated in male offspring of diabetic Hoxb7/CAT-GFP-Tg dams via the Nrf2-HO-1 defense system. CAT promoted Nrf2 nuclear translocation and HO-1 gene expression, seen in both in vitro and in vivo studies. In conclusion, CAT overexpression in the RPTCs ameliorated maternal diabetes-induced perinatal programming, mediated, at least in part, by triggering the Nrf2-HO-1 defense system.

  14. AQUEOUS REDUCTION OF HG2+ TO HG0 BY HO2 IN THE CMAQ-MODEL

    EPA Science Inventory

    Numerical models of atmospheric mercury are formulated based on the current understanding of mercury chemistry in air and in atmospheric water. Recent evidence that significant reduction of Hg2+ by reaction with HO2 may not actually occur in natural atmospheric water has obviou...

  15. Solid state phase equilibria and intermetallic compounds of the Al-Cr-Ho system

    SciTech Connect

    Pang, Mingjun; Zhan, Yongzhong; Du, Yong

    2013-02-15

    The solid state phase equilibria of the Al-Cr-Ho ternary system at 500 Degree-Sign C were experimentally investigated. The phase relations at 500 Degree-Sign C are governed by 14 three-phase regions, 29 two-phase regions and 15 single-phase regions. The existences of 10 binary compounds and 2 ternary phases have been confirmed. Al{sub 11}Cr{sub 2}, Al{sub 11}Cr{sub 4} and Al{sub 17}Ho{sub 2} were not found at 500 Degree-Sign C. Crystal structures of Al{sub 9}Cr{sub 4} and Al{sub 8}Cr{sub 4}Ho were determined by the Rietveld X-ray powder data refinement. Al{sub 9}Cr{sub 4} was found to exhibit cubic structure with space group I4-bar 3m (no. 217) and lattice parameters a=0.9107(5) nm. Al{sub 8}Cr{sub 4}Ho crystallizes in ThMn{sub 12} structure type with space group I4/mmm (no. 139) and lattice parameters a=0.8909(4) nm, c=0.5120(5) nm. It is concluded that the obtained Al{sub 4}Cr phase in this work should be {mu}-Al{sub 4}Cr by comparing with XRD pattern of the hexagonal {mu}-Al{sub 4}Mn compound. - Graphical abstract: The solid state phase equilibria of the Al-Cr-Ho ternary system at 500 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Al-Cr-Ho system has been investigated. Black-Right-Pointing-Pointer Al{sub 9}Cr{sub 4} has cubic structure with space group I4-bar 3m. Black-Right-Pointing-Pointer Al{sub 8}Cr{sub 4}Ho crystallizes in ThMn{sub 12} type with space group I4/mmm. Black-Right-Pointing-Pointer Al{sub 4}Cr phase is {mu}-type at 500 Degree-Sign C.

  16. [NiIII(OMe)]-mediated reductive activation of CO2 affording a Ni(κ1-OCO) complex

    DOE PAGES

    Chiou, Tzung -Wen; Tseng, Yen -Ming; Lu, Tsai -Te; ...

    2016-02-24

    Here, carbon dioxide is expected to be employed as an inexpensive and potential feedstock of C1 sources for the mass production of valuable chemicals and fuel. Versatile chemical transformations of CO2, i.e. insertion of CO2 producing bicarbonate/acetate/formate, cleavage of CO2 yielding μ-CO/μ-oxo transition-metal complexes, and electrocatalytic reduction of CO2 affording CO/HCOOH/CH3OH/CH4/C2H4/oxalate were well documented. Herein, we report a novel pathway for the reductive activation of CO2 by the [NiIII(OMe)(P(C6H3-3-SiMe3-2-S)3)]– complex, yielding the [NiIII(κ1-OCO˙–)(P(C6H3-3-SiMe3-2-S)3)]– complex. The formation of this unusual NiIII(κ1-OCO˙–) complex was characterized by single-crystal X-ray diffraction, EPR, IR, SQUID, Ni/S K-edge X-ray absorption spectroscopy, and Ni valence-to-core X-ray emissionmore » spectroscopy. The inertness of the analogous complexes [NiIII(SPh)], [NiII(CO)], and [NiII(N2H4)] toward CO2, in contrast, demonstrates that the ionic [NiIII(OMe)] core attracts the binding of weak σ-donor CO2 and triggers the subsequent reduction of CO2 by the nucleophilic [OMe]– in the immediate vicinity. This metal–ligand cooperative activation of CO2 may open a novel pathway promoting the subsequent incorporation of CO2 in the buildup of functionalized products.« less

  17. Inside HOLMES experiment: 163Ho metallic target production for the micro-calorimeter absorber

    NASA Astrophysics Data System (ADS)

    Pizzigoni, G.; Alpert, B.; Balata, M.; Bennett, D.; Biasotti, M.; Boragno, C.; Brofferio, C.; De Gerone, M.; Dressler, R.; Faverazani, M.; Ferri, E.; Folwer, J.; Gatti, F.; Giachero, A.; Heinitz, S.; Hilton, G.; Köster, U.; Lusignoli, M.; Maino, M.; Mates, J.; Nisi, S.; Nizzolo, R.; Nucciotti, A.; Pessina, G.; Puiu, A.; Ragazzi, S.; Reintsema, C.; Ribeiro Gomes, M.; Shmidt, D.; Schumann, D.; Sisti, M.; Swetz, D.; Terranova, F.; Ullom, J.; Day, P. K.

    2016-07-01

    The main goal in the HOLMES experiment is the neutrino mass measurement using an array of 1000 micro-calorimeters with standard metallic absorber. A good isotope for such measurement is the 163Ho, those isotopes embedded in the metallic absorber will be 1011-1013. Since 163Ho is not available in nature, a dedicated process must be set up to produce the amount needed for this neutrino mass experiment. The process with the highest born-up cross-section is the neutron irradiation of Er2O3 enriched in 162Er: 162Er(n,γ)163Er →163Ho+νe, where the decay is an EC with half-life of about 75 min and the (n,γ) is about 20 barns for thermal neutron. After the neutron irradiation in the oxide powder there are several radioactive isotopes which are potentially disturbing because of the background that they cause below 5 keV. The chemical separation of holmium from the irradiation enriched Er2O3 powder is therefore mandatory and will be performed by means of ion exchange chromatography. On the end of those processes the oxide powder enriched in 162Er will have the 163Ho isotope number required. The holmium chemical state influences the end point of the EC spectrum, in order to avoid such effect it is necessary to embed in the absorber only the metallic isotope. Reduction and distillation technique allowed us to obtain a pure metallic holmium, starting from natural oxide holmium. This technique will be applied on the irradiated oxide powder to obtain the metallic 163Ho, ready to be embedded in the micro-calorimeter absorber.

  18. Iron Supplementation Alters Heme and Heme Oxygenase 1 (HO-1) Levels In Pregnant Women in Ghana

    PubMed Central

    Salifu, Hassana; Wilson, Nana O.; Liu, Mingli; Dickinson-Copeland, Carmen; Yatich, Nelly; Keenan, John; Turpin, Cornelius; Jolly, Pauline; Gyasi, Richard; Adjei, Andrew A.; Stiles, Jonathan K.

    2016-01-01

    Background Iron supplementation is recommended for pregnant women to meet their iron requirement for a healthy pregnancy. The benefits and risks of universal iron supplementation during pregnancy in malaria endemic countries are currently being debated. As part of a broader study that focused on the effect of heme/HO-1 on pregnancy outcomes in malaria in pregnancy, we determined the association between iron supplementation and free heme levels in blood of pregnant women with and without malaria in Ghana. We hypothesized that pregnant women with malaria who took iron supplements will have higher levels of Heme/HO-1 than those who did not take iron supplements. Methods A total of 337 women were recruited for this study. Blood samples were collected for malaria diagnosis and heme/HO-1 measurement. Quantification of heme was done using a heme colorimetric assay kit and HO-1 levels were performed using Enzyme-Linked Immunosorbent Assay (ELISA) on plasma samples. Results Malaria positive iron supplemented women, in their third trimester, had significantly higher median levels of heme 59.3(43.1 – 60.4) than non-malaria iron supplemented women 35.7(33.0 – 62.2), p = 0.026. Also, malaria positive iron supplemented women had significant higher median levels of HO-16.2(IQR 4.9 – 8.1) than pregnant women who did not take iron supplements 2.9 (IQR 2.1 – 3.8), p = <0.001 Conclusion Although iron supplementation may be highly beneficial and improve pregnancy outcomes for iron deficient or anemic mothers, it is also likely that iron supplementation for pregnant women who are not iron deficient may put this group of women at risk for adverse pregnancy outcomes. Findings from this study sheds light on the effect of iron supplementation on malaria derived heme in pregnancy, which may inform how iron supplementation is recommended for pregnant women who are not iron deficient. PMID:28124024

  19. Faraday Rotation Spectroscopy of HO_{2} from AN Atmospheric Flow Reactor

    NASA Astrophysics Data System (ADS)

    Brumfield, Brian; Wysocki, Gerard; Sun, Wenting; Ju, Yiguang

    2013-06-01

    The hydroperoxyl radical (HO_{2}) is a key reactive intermediate in the low-temperature (<1000 K) and high pressure (≥1 atm) oxidation chemistry of hydrocarbons and oxygenated fuels. Chemical kinetic models have been developed for a number of fuels in the low-temperature and high-pressure regime, but validation of these models relies on quantitative measurements of radical intermediates such as HO_{2}. In situ optical measurements of HO_{2} at high-pressure (≥1 atm) by absorption spectroscopy are complicated by spectral overlap from non-radical species. Faraday rotation spectroscopy (FRS) is a sensitive magneto-optical dispersion-based technique that can be used to selectively observe signals from radicals while strongly suppressing signals from non-radicals, effectively eliminating the problem of spectral overlap at high-pressures. Recently FRS has been used in the first direct measurements of HO_{2} at the exit of an atmospheric flow reactor during the oxidation of dimethyl ether (DME). An external-cavity quantum cascade laser was used to record FRS spectra of Q-branch transitions in the ν_{2} vibrational band at 7.14 μm. To describe the experimental signals a numerical spectral model was developed using line positions and intensities provided by the HITRAN 2008 spectral database. HO_{2} concentrations were determined through non-linear fitting of the spectral model to the experimental spectra. In this talk the non-linear fitting of the FRS spectra to the numerical model will be presented, and the measured temperature dependence on the concentration will be compared to results from chemical kinetic modeling of DME oxidation. Litfin et al., J. Chem. Phys.72, 6602 (1980).

  20. Covariant Hořava-like and mimetic Horndeski gravity: cosmological solutions and perturbations

    NASA Astrophysics Data System (ADS)

    Cognola, Guido; Myrzakulov, Ratbay; Sebastiani, Lorenzo; Vagnozzi, Sunny; Zerbini, Sergio

    2016-11-01

    We consider a variant of the Nojiri-Odintsov covariant Hořava-like gravitational model, where diffeomorphism invariance is broken dynamically via a non-standard coupling to a perfect fluid. The theory allows one to address some of the potential instability problems present in Hořava-Lifshitz gravity due to explicit diffeomorphism invariance breaking. The fluid is instead constructed from a scalar field constrained by a Lagrange multiplier. In fact, the Lagrange multiplier construction allows for an extension of the Hořava-like model to include the scalar field of mimetic gravity, an extension which we thoroughly explore. By adding a potential for the scalar field, we show how one can reproduce a number of interesting cosmological scenarios. We then turn to the study of perturbations around a flat FLRW background, showing that the fluid in question behaves as an irrotational fluid, with zero sound speed. To address this problem, we consider a modified version of the theory, adding higher derivative terms in a way which brings us beyond the Horndeski framework. We compute the sound speed in this modified higher order mimetic Hořava-like model and show that it is non-zero, which means that perturbations therein can be sensibly defined. Caveats to our analysis, as well as comparisons to projectable Hořava-Lifshitz gravity, are also discussed. In conclusion, we present a theory of gravity which preserves diffeomorphism invariance at the level of the action but breaks it dynamically in the UV, reduces to General Relativity (GR) in the IR, allows the realization of a number of interesting cosmological scenarios, is well defined when considering perturbations around a flat FLRW background, and features cosmological dark matter emerging as an integration constant.

  1. Rate Constants for the Reactions of OH with CO, NO and NO2, and of HO2 with NO2 in the Presence of Water Vapour at Lower-Tropospheric Conditions

    NASA Astrophysics Data System (ADS)

    Rolletter, Michael; Fuchs, Hendrik; Novelli, Anna; Ehlers, Christian; Hofzumahaus, Andreas

    2016-04-01

    Recent studies have shown that the chemistry of gaseous nitrous acid (HONO) in the lower troposphere is not fully understood. Aside from heterogenous reactions, the daytime HONO formation in the gas-phase is not well understood (Li et al., Science, 2014). For a better understanding of HONO in the gas-phase, we have reinvestigated the reaction rate constants of important tropospheric reactions of the HOx radical family (OH and HO2) with nitrogen oxides at realistic conditions of the lower troposphere (at ambient temperature/pressure and in humid air). In this study we apply a direct pump and probe technique with high accuracy, using small radical concentrations to avoid secondary chemistry. Pulsed laser photolysis/laser-induced fluorescence (LP/LIF) was used to investigate the reaction rate constants of OH with CO, NO, NO2, and HO2 with NO2 in synthetic air at different water vapor concentrations (up to 5 x 1017 molecules cm-3). Photolysis of ozone in the presence of gaseous water was the source of OH. The reactions took place in a flow-tube at room temperature and atmospheric pressure. The chemical decay of the radicals was monitored by laser-induced fluorescence detection in a low-pressure cell, which sampled air continuously from the end of the flow-tube. Knowing the reactant concentrations subsequently allowed to calculate the bimolecular reaction rate constants at 1 atm from the pseudo-first-order decays. In order to observe HO2 reactions, OH was converted into HO2 with an excess of CO in the flow-tube. The newly measured rate constants for OH with CO, NO and NO2 agree very well with current recommendations by NASA/JPL and IUPAC and have an improved accuracy (uncertainty < 5%). These rate coefficients are independent of the presence of water vapour. The measured rate constant of HO2 with NO2 was found to depend significantly on the water-vapour concentration (probably due to formation of HO2*H2O complexes) and to exceed current recommendations by NASA/JPL and

  2. 2-3 μm emission and fluorescent decaying behavior in Ho3+-doped tellurium germanate glass

    NASA Astrophysics Data System (ADS)

    Gao, Song; Liu, Xueqiang; Kang, Shuai; Liao, Meisong; Hu, Lili

    2016-03-01

    In this work, we report the 2.05 μm emission and ∼3 μm broadband spectra of Ho2O3-doped 33GeO2-30TeO2-27PbO-10CaO (in mol%) glass under 640 nm laser excitation. Clear emission spectra due to the 5I7-5I8 transition and the 5I6-5I7 transition in Ho3+ are observed. The 2.05 μm emission intensity and the full width at half maximum (FWHM) of the ∼3 μm broadband depend on the Ho concentration. The peak stimulated emission cross-section of Ho3+ is 6.57 × 10-21 cm2 at 2.05 μm, as calculated by the McCumber theory. The emission spectra are recorded and the maximum emission intensity at 2.05 μm is obtained at a doping level of 0.5 mol% Ho2O3 in the glass. A broad and flat emission band from 2700 nm to 3050 nm is observed in 2 mol% Ho2O3-doped tellurium germanate glass. The lifetime of the 5I7 state decreases with the increase in Ho3+ concentration due to non-radiative relaxation processes. An energy transfer coefficient of 271.88 mol-1 s-1 is obtained.

  3. In 2013, holmium laser enucleation of the prostate (HoLEP) may be the new 'gold standard'.

    PubMed

    van Rij, Simon; Gilling, Peter J

    2012-12-01

    In this review article, we assess why holmium laser enucleation of the prostate (HoLEP) has become an important treatment modality for benign prostatic hypertrophy (BPH). Meta-analysis comparing HoLEP with both open prostatectomy (OP) and transurethral resection of prostate (TURP) shows TURP to be as effective with less morbidity. More recently, HoLEP has long-term durability data confirming a very low reoperation rate. This article investigates how previous hurdles to the widespread uptake of HoLEP have been overcome. Recent literature shows that the learning curve is actually similar to many other current urological procedures, and that the efficiency of HoLEP is equal to that of other surgical procedures. HoLEP is also beneficial in the growing population of men on anticoagulation who require treatment for BPH. Finally, HoLEP is the only laser treatment for BPH with level 1 evidence and endorsement in both the American Urological Association (AUA) and European Association of Urology (EAU) guidelines.

  4. HOLMES: The electron capture decay of [Formula: see text]Ho to measure the electron neutrino mass with sub-eV sensitivity.

    PubMed

    Alpert, B; Balata, M; Bennett, D; Biasotti, M; Boragno, C; Brofferio, C; Ceriale, V; Corsini, D; Day, P K; De Gerone, M; Dressler, R; Faverzani, M; Ferri, E; Fowler, J; Gatti, F; Giachero, A; Hays-Wehle, J; Heinitz, S; Hilton, G; Köster, U; Lusignoli, M; Maino, M; Mates, J; Nisi, S; Nizzolo, R; Nucciotti, A; Pessina, G; Pizzigoni, G; Puiu, A; Ragazzi, S; Reintsema, C; Gomes, M Ribeiro; Schmidt, D; Schumann, D; Sisti, M; Swetz, D; Terranova, F; Ullom, J

    The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the decay of [Formula: see text]Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted [Formula: see text]Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.

  5. Magnetic properties of pure and Fe doped HoCrO3 thin films fabricated via a solution route

    NASA Astrophysics Data System (ADS)

    Yin, Shiqi; Sauyet, Theodore; Guild, Curt; Suib, S. L.; Jain, Menka

    2017-04-01

    Multiferroic properties of orthorhombically distorted perovskite rare-earth chromites, such as HoCrO3, are being investigated extensively in recent years. In the present work, we report on the effect of Fe substitution on the magnetic properties of HoCrO3 thin films. Thin films of HoCrO3 and HoCr0.7Fe0.3O3 were fabricated via a solution route on platinized silicon substrates. Structural properties of the films were evaluated by X-ray diffraction and Raman spectroscopy techniques. The surface morphology and cross-sections of the films were examined using scanning electron microscopy. Optical band gaps of pure and Fe doped HoCrO3 films are found to be 3.45 eV and 3.39 eV, respectively. The magnetization measurements show that the Néel temperatures (where Cr3+ orders) for the HoCrO3 and HoCr0.7Fe0.3O3 films are 134 and 148 K, respectively. In a magnetic field of 2 T, the maximum entropy change and relative cooling power, two parameters to evaluate the magnetocaloric properties of a material, were 0.813 J/kg K at 11 K and 21.1 J/kg for HoCrO3 film, in comparison with 0.748 J/kg K at 15 K and 26.8 J/kg for HoCr0.7Fe0.3O3 film. To our knowledge, this is the first work exploring the band gap and magnetocaloric properties of rare-earth chromite thin films. These findings should inspire the development of rare-earth chromite thin films for temperature control of nanoscale electronic devices and sensors in the low temperature region (< 30 K).

  6. Unveiling the Association of STAT3 and HO-1 in Prostate Cancer: Role beyond Heme Degradation1

    PubMed Central

    Elguero, Belen; Gueron, Geraldine; Giudice, Jimena; Toscani, Martin A; De Luca, Paola; Zalazar, Florencia; Coluccio-Leskow, Federico; Meiss, Roberto; Navone, Nora; De Siervi, Adriana; Vazquez, Elba

    2012-01-01

    Activation of the androgen receptor (AR) is a key step in the development of prostate cancer (PCa). Several mechanisms have been identified in AR activation, among them signal transducer and activator of transcription 3 (STAT3) signaling. Disruption of STAT3 activity has been associated to cancer progression. Recent studies suggest that heme oxygenase 1 (HO-1) may play a key role in PCa that may be independent of its catalytic function. We sought to explore whether HO-1 operates on AR transcriptional activity through the STAT3 axis. Our results display that HO-1 induction in PCa cells represses AR activation by decreasing the prostate-specific antigen (PSA) promoter activity and mRNA levels. Strikingly, this is the first report to show by chromatin immunoprecipitation analysis that HO-1 associates to gene promoters, revealing a novel function for HO-1 in the nucleus. Furthermore, HO-1 and STAT3 directly interact as determined by co-immunoprecipitation studies. Forced expression of HO-1 increases STAT3 cytoplasmic retention. When PCa cells were transfected with a constitutively active STAT3 mutant, PSA and STAT3 downstream target genes were abrogated under hemin treatment. Additionally, a significant decrease in pSTAT3 protein levels was detected in the nuclear fraction of these cells. Confocal microscopy images exhibit a decreased rate of AR/STAT3 nuclear co-localization under hemin treatment. In vivo studies confirmed that STAT3 nuclear delimitation was significantly decreased in PC3 tumors overexpressing HO-1 grown as xenografts in nude mice. These results provide a novel function for HO-1 down-modulating AR transcriptional activity in PCa, interfering with STAT3 signaling, evidencing its role beyond heme degradation. PMID:23226098

  7. Molecular cloning, characterization, and expression of an alfalfa (Medicago sativa L.) heme oxygenase-1 gene, MsHO1, which is pro-oxidants-regulated.

    PubMed

    Fu, Guang-Qing; Xu, Sheng; Xie, Yan-Jie; Han, Bin; Nie, Li; Shen, Wen-Biao; Wang, Ren

    2011-07-01

    It has been documented that plant heme oxygenase-1 (HO-1; EC 1.14.99.3) is both development- and stress-regulated, thus it plays a vital role in light signalling and stress responses. In this study, an alfalfa (Medica sativa L.) HO-1 gene MsHO1 was isolated and sequenced. It contains four exons and three introns within genomic DNA sequence and encodes a polypeptide with 283 amino acids. MsHO1 had a conserved HO signature sequence and showed high similarity to other HOs in plants, especially HO-1 isoform. The MsHO1:GFP fusion protein was localized in the chloroplast. Further biochemical activity analysis of mature MsHO1, which was expressed in Escherichia coli, showed that the Vmax was 48.78 nmol biliverdin-IXα (BV) h⁻¹ nmol⁻¹ protein with an apparent Km value for hemin of 2.33 μM, and the optimum Tm and pH were 37 °C and 7.2, respectively. Results of semi-quantitative RT-PCR and western blot showed that the expressions of MsHO1 were higher in alfalfa stems and leaves than those in germinating seeds and roots. Importantly, MsHO1 gene expression and protein level were induced significantly by some pro-oxidant compounds, including hemin and nitric oxide (NO) donor sodium nitroprusside (SNP). In conclusion, MsHO1 may play an important role in oxidative responses.

  8. Imaging Chemical Aggregation of Ni/NiO Particles from Reduced NiO-YSZ

    SciTech Connect

    Saraf, Laxmikant V.

    2011-07-20

    Energy dispersive X-ray spectroscopy (EDS) mapping of nickel oxide yttria-stabilized zirconia (NiO-YSZ) was carried out after various hydrogen reducing and methane steam reforming conditions. Nickel aggregation was visualized after methane steam reforming by correlating Ni K{sub {alpha}} map with scanning transmission electron microscopy (STEM) images. From the reduced O K{sub {alpha}} intensities in the Ni K{sub {alpha}} dominated regions after methane steam reforming, NiO reduction in to Ni can be interpreted. From correlation between Zr K{sub {alpha}} and O K{sub {alpha}} maps, high stability of YSZ was also realized. Examples of NiO-YSZ overlapped particles are considered to discuss chemical imaging of a single particle.

  9. Reliability analysis of single crystal NiAl turbine blades

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan; Noebe, Ronald; Wheeler, Donald R.; Holland, Fred; Palko, Joseph; Duffy, Stephen; Wright, P. Kennard

    1995-01-01

    As part of a co-operative agreement with General Electric Aircraft Engines (GEAE), NASA LeRC is modifying and validating the Ceramic Analysis and Reliability Evaluation of Structures algorithm for use in design of components made of high strength NiAl based intermetallic materials. NiAl single crystal alloys are being actively investigated by GEAE as a replacement for Ni-based single crystal superalloys for use in high pressure turbine blades and vanes. The driving force for this research lies in the numerous property advantages offered by NiAl alloys over their superalloy counterparts. These include a reduction of density by as much as a third without significantly sacrificing strength, higher melting point, greater thermal conductivity, better oxidation resistance, and a better response to thermal barrier coatings. The current drawback to high strength NiAl single crystals is their limited ductility. Consequently, significant efforts including the work agreement with GEAE are underway to develop testing and design methodologies for these materials. The approach to validation and component analysis involves the following steps: determination of the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; measurement of the failure strength envelope of the material; coding of statistically based reliability models; verification of the code and model; and modeling of turbine blades and vanes for rig testing.

  10. Ni/Al Multilayers Produced by Accumulative Roll Bonding and Sputtering

    NASA Astrophysics Data System (ADS)

    Simões, S.; Ramos, A. S.; Viana, F.; Emadinia, O.; Vieira, M. T.; Vieira, M. F.

    2016-10-01

    Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high heat release rate and can be triggered by an external impulse, are reasons why it has already attracted much research attention. There is a huge potential in the use of Ni/Al multilayers as a controllable and localized heat source for joining temperature-sensitive materials such as microelectronic components. The heat released and the phases resulting from the reaction of Ni and Al multilayers depend on the production methods, their composition, as well as the bilayer thickness and annealing conditions. The present research aims to explore the influence of these variables on the reaction of different multilayers, namely those produced by accumulative roll bonding (ARB) and sputtering. Structural evolution of Ni/Al multilayers with temperature was studied by differential scanning calorimetry, x-ray diffraction and scanning electron microscopy. Phase evolution, heat release rate and NiAl final grain size are controlled by the ignition method used to trigger the reaction of Ni and Al. The potential use of these multilayers in the diffusion bonding of TiAl was analyzed. The ARB multilayers allow the production of joints with higher strength than the joints produced with commercial multilayers (NanoFoil®) produced by sputtering. However, the formation of brittle intermetallic phases (Ni3Al, Ni2Al3 and NiAl3) compromises the mechanical properties of the joint.

  11. Optical spectroscopy and diode-pumped laser characteristics of codoped Tm-Ho:YLF and Tm-Ho:BaYF: a comparative analysis

    NASA Astrophysics Data System (ADS)

    Cornacchia, F.; Sani, E.; Toncelli, A.; Tonelli, M.; Marano, M.; Taccheo, S.; Galzerano, G.; Laporta, P.

    Single crystals of monoclinic BaY2F8 and tetragonal LiYF4 codoped with the same Tm3+ and Ho3+ concentrations were successfully grown by the Czochralski method. Here we present a comparative analysis of the two hosts including spectroscopic characterization and cw diode-pumped laser experiments in the 2-μm wavelength region at room temperature. The main differences between the two hosts are a lower slope efficiency associated with a much wider tuning range (2005-2094 nm) of BaY2F8 with respect to LiYF4.

  12. Magnetic properties and electronic structures of R Ni B compounds where R is a heavy rare earth

    NASA Astrophysics Data System (ADS)

    Burzo, E.; Bucur, N.; Chioncel, L.; Rednic, V.

    2008-07-01

    Magnetic measurements were performed in the temperature range 4.2-300 K and fields up to 70 kOe on R3Ni7B2 compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie-Weiss type behaviour. Effective nickel moments of 1.33 ± 0.25 µB were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.

  13. Atomic diffusion in liquid Ni, NiP, PdNiP, and PdNiCuP alloys

    SciTech Connect

    Chathoth, S. Mavila; Meyer, A.; Koza, M.M.; Juranyi, F.

    2004-11-22

    We investigated the self-diffusion of Ni in liquid Ni, Ni{sub 80}P{sub 20}, Pd{sub 40}Ni{sub 40}P{sub 20}, and Pd{sub 43}Ni{sub 10}Cu{sub 27}P{sub 20} at temperatures up to 1795 K with incoherent, quasielastic neutron scattering. Values of measured self-diffusion coefficients vary over the accessible temperature ranges as a function of composition only within 10%. Although mixing has a drastic effect on the liquidus temperature and the undercooling capabilities, a relation between these properties and the atomic diffusion in the liquid is not observed. Apparently, diffusive motion is governed by the packing fraction of the atoms, that is very similar in these dense liquids.

  14. Chemical Ionization Mass Spectrometry-Based Measurements of HO2 and RO2 During TRACE-P

    NASA Technical Reports Server (NTRS)

    Cantrell, Christopher A.; Eisele, Fred L.

    2004-01-01

    The Transport and Chemical Evolution over the Pacific (TRACE-P) mission extends NASA's Global Tropospheric Experiment (GTE) series of campaigns. TRACE-P was an aircraft-based campaign that was part of a larger ground-based and aircraft-based program (APARE) under the auspices of the International Global Atmospheric Chemistry (IGAC) program. TRACE-P was designed to (1) determine the chemical composition of Asian outflow over the western Pacific, and to (2) determine the chemical evolution of the Asian outflow. These objectives were addressed through a variety of observations and numerical modeling exercises. In particular, the goals included sampling strategies that would improve understanding of the budgets of odd hydrogen species (OH and HO2), budgets of NOx (NO, NO2, and their reservoirs), and impacts of oxidants produced in the outflow on air quality in the United States. The NASA DC-8 and P-3B aircraft were deployed in the March and April, 2001 out of primary bases of operation in Hong Kong and Yokota Air Base in Japan. These two aircraft have complementary capabilities which allow high altitude and long range impacts, as well as low altitude, local impacts to be assessed. In order to quantify the composition and evolution of Asian outflow, it is important to quantify as many species as possible including photochemically active species (e.g. NO2, CH2O, O3, acetone, etc.), sources species (VOCs, CO, NOx, SO2, aerosols), reactive intermediates including free radicals (OH, HO2, RO2, and their reservoirs), and end products (nitric acid, sulfuric acid, secondary aerosols, etc.). The more complete the measurement suite, the more tightly constrained the numerical modeling can be (within the uncertainties of the measurements). The numerical models range in sophistication from simple steady state box models (as employed in this study) to multi-dimensional chemical transport models. Data were collected on approximately 20 flights of the DC-8 and 21 flights of the P-3B

  15. Increased frequency of extreme La Niña events under greenhouse warming

    NASA Astrophysics Data System (ADS)

    Cai, Wenju; Wang, Guojian; Santoso, Agus; McPhaden, Michael J.; Wu, Lixin; Jin, Fei-Fei; Timmermann, Axel; Collins, Mat; Vecchi, Gabriel; Lengaigne, Matthieu; England, Matthew H.; Dommenget, Dietmar; Takahashi, Ken; Guilyardi, Eric

    2015-02-01

    The El Niño/Southern Oscillation is Earth’s most prominent source of interannual climate variability, alternating irregularly between El Niño and La Niña, and resulting in global disruption of weather patterns, ecosystems, fisheries and agriculture. The 1998-1999 extreme La Niña event that followed the 1997-1998 extreme El Niño event switched extreme El Niño-induced severe droughts to devastating floods in western Pacific countries, and vice versa in the southwestern United States. During extreme La Niña events, cold sea surface conditions develop in the central Pacific, creating an enhanced temperature gradient from the Maritime continent to the central Pacific. Recent studies have revealed robust changes in El Niño characteristics in response to simulated future greenhouse warming, but how La Niña will change remains unclear. Here we present climate modelling evidence, from simulations conducted for the Coupled Model Intercomparison Project phase 5 (ref. ), for a near doubling in the frequency of future extreme La Niña events, from one in every 23 years to one in every 13 years. This occurs because projected faster mean warming of the Maritime continent than the central Pacific, enhanced upper ocean vertical temperature gradients, and increased frequency of extreme El Niño events are conducive to development of the extreme La Niña events. Approximately 75% of the increase occurs in years following extreme El Niño events, thus projecting more frequent swings between opposite extremes from one year to the next.

  16. Dislocation sources in ordered intermetallics

    SciTech Connect

    Yoo, M.H.; Appel, F.; Wagner, R.; Mecking, H.

    1996-09-01

    An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.

  17. Energy transfer processes between Tm(3+) and Ho(3+) in LiYF4. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Oezen, Goenuel

    1991-01-01

    The spectroscopic properties of the crystal LiYF4 doped with Thulium (Tm) and Holmium (Ho) ions are studied. The basic processes are discussed that regulate the transfer of energy between these two ions in this crystal. In this system Tm is considered the donor ion and the Ho the acceptor ion. Spectral data were obtained on three samples available: LiYF4:Tm(3+) (0.5 percent), LiYF4:Ho(3+) (1 percent), and LiYF4:Tm(3+) (5 percent), Ho(3+) (0.2 percent). Spectral data, which include absorption, luminescence, excitation, and the response to pulsed excitation in a wide range of temperatures, allowed to look at the energy transfer processes by considering the kinetic evolution of the emission of the two ions (donor and acceptor) involved in the process and the basic spectroscopic properties related to them. This inclusive approach has led to the validation of the physical model.

  18. Study of Ho-doped Bi{sub 2}Te{sub 3} topological insulator thin films

    SciTech Connect

    Harrison, S. E.; Collins-McIntyre, L. J.; Zhang, S. L.; Chen, Y. L.; Hesjedal, T.; Baker, A. A.; Figueroa, A. I.; Laan, G. van der; Kellock, A. J.; Pushp, A.; Parkin, S. S. P.; Harris, J. S.

    2015-11-02

    Breaking time-reversal symmetry through magnetic doping of topological insulators has been identified as a key strategy for unlocking exotic physical states. Here, we report the growth of Bi{sub 2}Te{sub 3} thin films doped with the highest magnetic moment element Ho. Diffraction studies demonstrate high quality films for up to 21% Ho incorporation. Superconducting quantum interference device magnetometry reveals paramagnetism down to 2 K with an effective magnetic moment of ∼5 μ{sub B}/Ho. Angle-resolved photoemission spectroscopy shows that the topological surface state remains intact with Ho doping, consistent with the material's paramagnetic state. The large saturation moment achieved makes these films useful for incorporation into heterostructures, whereby magnetic order can be introduced via interfacial coupling.

  19. A novel ratiometric fluorescent probe based on 1, 8-naphthalimide for the detection of Ho3 + and its bioimaging

    NASA Astrophysics Data System (ADS)

    Zhang, Huifang; Liu, Tao; Yin, Caixia; Wen, Yin; Chao, Jianbin; Zhang, Yongbin; Huo, Fangjun

    2017-03-01

    A ratiometric fluorescent probe for the detection of Ho3 + in DMSO-aqueous medium was designed and synthesized based on 1, 8-naphthalimide. The probe displayed response to Ho3 + with a fluorescence decrease at 512 nm and enhancement at 480 nm, accompanying with a distinct fluorescence change from bright yellow-green to cyan. Besides, the probe exhibited a lower detection limit (6 × 10- 8 M) and could be used in intracellular fluorescence imaging. To the best of the knowledge, it was the first ratiometric fluorescent probe for Ho3 + detection. This probe was expected to be a useful tool for further elucidating the roles of Ho3 + in materials, biology and environment.

  20. Ab initio investigations of A-site doping on the structure and electric polarization of HoMnO3

    NASA Astrophysics Data System (ADS)

    S, Sathya Sheela; C, Kanagaraj; Natesan, Baskaran

    2015-06-01

    We have investigated the effect of A-site doping on the structure and electric polarization of orthorhombic HoMnO3 using ab initio density functional theory calculations. We find that the substitution of rare earth ions, such as Lu, Y and La in place of Ho in orthorhombic HoMnO3 modifies the local structure around Mn ions drastically, and leads to the formation of two distinct Mn sites Mn(0) and Mn(1). As a result, large variance between Mn(0)O6 and Mn(1)O6 octahedral distortions arises. This variance in the octahedral distortions drives the disparate hopping of electrons between the eg orbitals enhancing the electronic polarization with increasing rare earth ion radius. The largest polarization of 7 µC/cm2 is obtained for La doped HoMnO3. This increase in polarization has been explained on the basis of radius mismatch induced local structural effects.

  1. Comparison of benzene adsorption on Ni(111) and Ni(100)

    SciTech Connect

    Myers, A.K.; Schoofs, G.R.; Benziger, J.B.

    1987-04-23

    The adsorption of benzene on the Ni(100) and the Ni(111) crystal faces was compared in order to investigate the effect of crystallographic orientation on the interaction of benzene with nickel. Temperature programmed reaction (TPR) was used to characterize adsorption bond strengths and determine product distributions. Benzene was found to adsorb 44 kJ/mol less strongly on the Ni(111) plane than on the Ni(100) surface. Di-hydrogen evolution formed after decomposition of benzene was similar for both surfaces. Benzene chemisorption was modeled by using extended Hueckel theory (EHT), a semiempirical molecular orbital method. The calculations predict bonding of benzene over a threefold hollow site on Ni(111). Multicenter bonding of the benzene carbon atoms with the nickel atoms is indicated by the calculations. The binding strength of benzene is controlled by the degree of overlap of the carbon ..pi.. orbitals with the nickel atom orbitals. Benzene binds more strongly to the Ni(100) surface because the carbon ..pi.. orbitals can overlap with four nickel atoms on the fourfold hollow site, whereas on Ni(111) the carbon atoms are closely associated with only three nickel atoms on the threefold hollow site.

  2. Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

    NASA Technical Reports Server (NTRS)

    Choi, Young S.; Kim, Kyong H.; Whitney, Donald A.; Hess, Robert V.; Barnes, Norman P.; Bair, Clayton H.; Brockman, Philip

    1989-01-01

    A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid

  3. HO-1, RET and PML as possible markers for risk stratification of acute myelocytic leukemia and prognostic evaluation.

    PubMed

    Yu, Meisheng; Wang, Jishi; Ma, Dan; Chen, Shuya; Lin, Xiaojing; Fang, Qin; Zhe, Nana

    2015-11-01

    Heme oxygenase-1 (HO-1) is an inducible isoform of HO that is activated in response to oxidative stress and has anti-apoptotic and pro-proliferative effects on leukemia cells. RET, a tyrosine kinase receptor; its expression levels are associated with the differentiation degree of acute myelocytic leukemia (AML) cells. The promyelocytic leukemia (PML) gene inhibits cell proliferation and tumor growth, participates in the differentiation of hematopoietic progenitor cells and induces cell apoptosis. However, the association between the expression levels of HO-1, RET and PML genes and the risk stratification of AML and prognosis have not previously been reported. In the present study, HO-1 was expressed in the human AML Kasumi-1, HL-60 and THP-1 cell lines, and HO-1 expression was regulated by Hemin (20 µmol/l) and ZnPPIX (10 µmol/l). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis demonstrated that expression of RET and PML were positively and negatively correlated with HO-1 expression, respectively. Bone marrow samples (18 favorable, 55 intermediate, 15 adverse and 2 unknown karyotype AML cases and 20 healthy donors) were collected from 90 randomly selected AML patients upon their first visit. The mRNA and protein expression of HO-1, RET and PML in samples was detected by RT-qPCR and western blot analysis. At the mRNA level, the adverse group expressed significantly higher levels of HO-1 and RET compared with the levels in the favorable and normal groups. The PML mRNA expression levels in adverse patient samples was lower compared with those of the intermediate group and favorable group. Western blot analysis demonstrated that the expression levels of HO-1, RET and PML proteins in all risk groups exhibited the same pattern of expression as was observed for the mRNA levels. The overall survival and relapse-free survival rates were shortest in AML patients with high HO-1 expression (Kaplan-Meier; log-rank, P<0.01). The results of the

  4. Determination of the Temperature Dependence of the Rate Constants for HO2/Acetonylperoxy Reaction and Acetonylperoxy Self-Reaction

    NASA Astrophysics Data System (ADS)

    Darby, E. C.; Grieman, F. J.; Hui, A. O.; Okumura, M.; Sander, S. P.

    2014-12-01

    Reactions of hydroperoxy radical, HO2, with carbonyl containing RO2 can play an important role in the oxidation chemistry of the troposphere. Discovered radical product channels in addition to radical termination channels have resulted in increased study of these important reactions. In our continued study of HO2 reactions with acetonylperoxy and acetylperoxy radicals, we report here our first results on the kinetics of the acetonylperoxy system. Previous studies have resulted in conflicting results and no temperature dependence of the rate constants. Using the Infrared Kinetic Spectroscopy (IRKS) method in which a temperature-controlled slow-flow tube apparatus and laser flash photolysis of Cl2 are used to produce HO2 and CH3C(O)CH2O2 from methanol and acetone, respectively, we studied the chemical kinetics involved over the temperature range of 295 to 240 K. Rates of chemical reaction were determined by monitoring the HO2 concentration as a function of time by sensitive near-IR diode laser wavelength modulation spectroscopy while simultaneously measuring the disappearance of [CH3C(O)CH2O2] in the ultraviolet at 300 nm. The simultaneous fits resulted in the determination of the temperature dependence of the rate constants for the HO2/acetonylperoxy reaction and the acetonylperoxy self-reaction. At the lower temperatures, the reactions of HO2 and CH3C(O)CH2O2 with the adducts HO2•CH3OH and HO2•CH3C(O)CH3 formed in significant concentrations needed to be included in the fitting models.

  5. Comparison of 2 micron Ho and 10 micron CO2 lidar for atmospheric backscatter and Doppler windshear detection

    NASA Technical Reports Server (NTRS)

    Killinger, Dennis

    1991-01-01

    The development of eye-safe, solid-state Lidar systems is discussed, with an emphasis on Coherent Doppler Lidar for Atmospheric Wind Measurements. The following subject areas are covered: tunable Ho DIAL (Differential Absorption Lidar)/lidar atmospheric measurements; atmospheric turbulence measurements and detector arrays; diurnal measurements of C(sub n)(sup 2) for KSC lidar measurements; and development of single-frequency Ho laser/lidar.

  6. Are HO radicals produced in the reaction of O(3P) with 1-C4H8 ?

    NASA Technical Reports Server (NTRS)

    Luria, M.; Simonaitis, R.; Heicklen, J.

    1972-01-01

    The reaction of O(3P) with 1-C4H8 was examined in the presence of CO which scavenges HO radicals to produce CO2. From the CO2 quantum yield, an upper limit to the efficiency of HO production in the reaction of O(3P) with 1-C4H8 was found to be 0.020 at both 298 and 473 K.

  7. Heat capacity and thermodynamic properties of HoMnO3 in the range of 364-1046 K

    NASA Astrophysics Data System (ADS)

    Denisova, L. T.; Chumilina, L. G.; Shaikhutdinov, K. A.; Patrin, G. S.; Denisov, V. M.

    2016-03-01

    The temperature dependence of the molar heat capacity of HoMnO3 has been measured by differential scanning calorimetry. The experimental data have been used to calculate the thermodynamic properties of the oxide compound (changes in the enthalpy H°( T)- H°(364 K), entropy S°( T)- S°(364 K), and reduced Gibbs energy Φ°( T)). The data on the heat capacity of HoMnO3 have been generalized in the range of 40-1000 K.

  8. 2 μm emission properties and nonresonant energy transfer of Er3+ and Ho3+ codoped silicate glasses

    PubMed Central

    Cao, Ruijie; Lu, Yu; Tian, Ying; Huang, Feifei; Guo, Yanyan; Xu, Shiqing; Zhang, Junjie

    2016-01-01

    2.0 μm emission properties of Er3+/Ho3+ codoped silicate glasses were investigated pumped by 980 nm LD. Absorption spectra were determined. Intense mid-infrared emissions near 2 μm are observed. The spectral components of the 2 μm fluorescence band were analyzed and an equivalent model of four-level system was proposed to describe broadband 2 μm emission. Low OH− absorption coefficient (0.23 cm−1), high fluorescence lifetime (2.95 ms) and large emission cross section (5.61 × 10−21 cm2) corresponding to Ho3+: 5I7→5I8 transition were obtained from the prepared glass. Additionally, energy transfer efficiency from the Er3+: 4I13/2 to the Ho3+: 5I7 level can reach as high as 85.9% at 0.75 mol% Ho2O3 doping concentration. Energy transfer microscopic parameters (CDA) via the host-assisted spectral overlap function were also calculated to elucidate the observed 2 μm emissions in detail. Moreover, the rate equation model between Er3+ and Ho3+ ions was developed to elucidate 2 μm fluorescence behaviors with the change of Ho3+ concentration. All results reveal that Er3+/Ho3+ codoped silicate glass is a promising material for improving the Ho3+ 2.0 μm fiber laser performance. PMID:27901047

  9. Investigation of the amplification properties of Ho:YAG single crystal fiber

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Zhang, Zeyu; Buckley, Ian; Miller, Jerome K.; Johnson, Eric G.; Nie, Craig D.; Harrington, James A.; Shori, Ramesh K.

    2015-02-01

    0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was fabricated using the laser heated pedestal growth (LHPG) method and amplification properties of the fabricated Ho:YAG SCF were studied. The relatively large lengthto- diameter ratio provides guiding for both the pump and signal beams propagating in the SCF. The propagation and gain of signals with different modes were studied. A numerical method based on finite difference (FD) beam propagation method (BPM) combined with the rate equations was developed for theoretical simulation. The results are encouraging to demonstrate the advantages of SCF for its fiber-like beam guiding property and solid state material gain property. The simulation tool provides details about how the fiber shape and launched mode affect the gain and output beam shape as well as predicts the amplification behavior of such unique specialty fibers.

  10. Experimental study into single-longitudinal-mode Tm,Ho:YVO4 lasers

    NASA Astrophysics Data System (ADS)

    Dai, Tong-Yu; Han, Liu; Yao, Bao-Quan; Ju, You-Lun; Yu, Kuai-Kuai; Wang, Yue-Zhu

    2015-11-01

    The single-longitudinal-mode (SLM) Tm,Ho:YVO4 lasers were achieved by microchip configuration and double Fabry-Perot structure at room temperature. In the case of the microchip configuration laser, the maximum SLM power up to 17 mW was obtained on 2052.4 nm at 15 °C. In order to improve the output power of the SLM laser, it was implemented that the configuration of double Fabry-Perot etalons was used into the study of Tm,Ho:YVO4 lasers. Utilizing such configuration, the laser generated up to 95 mW output power in SLM at the wavelength of 2051.3 nm. With the angle of the Fabry-Perot etalons varied, the wavelength of the SLM laser could be turned from 2050.4 nm to 2051.3 nm, corresponding to a turning frequency of -64 GHz.

  11. Metamagnetism-enhanced magnetocaloric effect in the rare earth intermetallic compound Ho5Ge4

    NASA Astrophysics Data System (ADS)

    Nirmala, R.; Morozkin, A. V.; Rajivgandhi, R.; Nigam, A. K.; Quezado, S.; Malik, S. K.

    2016-11-01

    Magnetic and magnetocaloric properties of polycrystalline Ho5Ge4 (orthorhombic, Sm5Ge4-type, Space group Pnma, No. 62, oP36) compound have been studied. This compound orders antiferromagnetically at ~24 K (TN). From the magnetization vs field isotherms obtained close to the magnetic transition temperature, magnetocaloric effect (MCE) has been estimated. The isothermal magnetic entropy change (ΔSM) reaches a maximum value of ~-27 J/kg-K at ~30 K for a field change of 140 kOe. A metamagnetic transition is observed in the field dependent magnetization data at temperatures below 20 K, for critical fields above 20 kOe, giving rise to a ferromagnetic order and hence a large MCE. The magnetic moment value at 2.5 K is ~8μB/Ho3+ in 90 kOe field.

  12. New relaxation processes in diluted Ho2Ti2O7

    SciTech Connect

    Gardner, Jason; Ehlers, Georg

    2009-01-01

    We have studied the spin relaxation in diluted spin ice Ho{sub 2-x}R{sub x}Ti{sub 2}O{sub 7} (R = La or Y) by means of neutron scattering. Remarkably, doping with nonmagnetic ions does not relieve the geometrical frustration and the dynamics of the freezing is unaltered whilst the cubic unit cell is maintained. When the nonmagnetic substitution starts to distort the lattice, a new relaxation process is revealed. We present new data from several diluted spin ice samples where Arrhenius behavior observed in the parent compound, Ho{sub 2}Ti{sub 2}O{sub 7} is superseded by other processes including a quantum tunnelling process.

  13. Hořava–Lifshitz gravity inspired Bianchi-II cosmology and the mixmaster universe

    NASA Astrophysics Data System (ADS)

    Giani, Leonardo; Kamenshchik, Alexander Y.

    2017-04-01

    We study different aspects of the Hořava-Lifshitz inspired Bianchi-II cosmology and its relations with the mixmaster universe model. First, we present exact solutions for a toy model, where only the cubic in spatial curvature terms are present in the action; then we briefly discuss some exotic singularities, which can appear in this toy model. We study also the toy model where only the quadratic in spatial curvature terms are present in the action. We establish relations between our results and those obtained by using the Hamiltonian formalism. Finally, we apply the results obtained by studying Bianchi-II cosmology to describe the evolution of the mixmaster universe in terms of the Belinsky–Khalatnikov–Lifshitz formalism. Generally, our analysis gives some arguments in favour of the existence of the oscillatory approach to the singularity in a universe governed by the Hořava–Lifshitz type gravity.

  14. Deuteron induced reactions on Ho and La: Experimental excitation functions and comparison with code results

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam-Rebeles, R.; Tarkanyi, F.; Takacs, S.; Csikai, J.; Takacs, M. P.; Ignatyuk, A.

    2013-09-01

    Activation products of rare earth elements are gaining importance in medical and technical applications. In stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross-sections for production of 161,165Er, 166gHo on 165Ho and 135,137m,137g,139Ce, 140La, 133m,133g,cumBa and 136Cs on natLa targets were measured up to 50 MeV. Reduced uncertainty is obtained by simultaneous remeasurement of the 27Al(d,x)24,22Na monitor reactions over the whole energy range. A comparison with experimental literature values and results from updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2012 online library) is discussed.

  15. Structure of three-quasiparticle isomers in {sup 169}Ho and {sup 171}Tm.

    SciTech Connect

    Dracoulis, G. D.; Lane, G. J.; Hughes, R. O.; Kondev, F. G.; Watanabe, H.; Seweryniak, D.; Zhu, S.; Carpenter, M. P.; Chiara, C. J.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Stefanescu, I.; Chowdhury, P.

    2010-09-17

    A three-quasiparticle isomer with {tau}=170(8) {micro}s and K{sup {pi}} = (19/2{sup +}) has been identified in the neutron-rich isotope {sup 169}Ho. The isomer decays with K-forbidden transitions to members of a band associated with the 7/2-[523] proton configuration, whose structure is characterized through analysis of the in-band {gamma}-ray branching ratios. In the isotone {sup 171}Tm, the rotational band based on the known 19/2{sup +}, three-quasiparticle isomer has also been observed. Alternative one-proton two-neutron configurations for the isomer in {sup 169}Ho are discussed in terms of multiquasiparticle calculations and through a comparison with the structures observed in {sup 171}Tm.

  16. A Kinetic and Product Study of the Cl + HO2 Reaction

    NASA Technical Reports Server (NTRS)

    Hickson, Kevin M.; Keyser, Leon F.

    2005-01-01

    Absolute rate data and product branching ratios for the reactions Cl + HO2 to HCl + O2 (k1a) and Cl + HO2 to OH + ClO (k1b) have been measured from 226 to 336 K at a total pressure of 1 Torr of helium using the discharge flow resonance fluorescence technique coupled with infrared diode laser spectroscopy. For kinetic measurements, pseudo-first-order conditions were used with both reagents in excess in separate experiments. HO2 was produced by two methods: through the termolecular reaction of H atoms with O2 and also by the reaction of F atoms with H2O2. Cl atoms were produced by a microwave discharge of Cl2 in He. HO2 radicals were converted to OH radicals prior to detection by resonance fluorescence at 308 nm. Cl atoms were detected directly at 138 nm also by resonance fluorescence. Measurement of the consumption of HO2 in excess Cl yielded k1a and measurement of the consumption of Cl in excess HO2 yielded the total rate coefficient, k1. Values of k1a and k1 derived from kinetic experiments expressed in Arrhenius form are (1.6 +/- 0.2) x 10-11 exp[(249 +/- 34)/T] and (2.8 +/- 0.1) x 10-11 exp[(123 +/- 15)/T] cm3 molecule-1 s-1, respectively. As the expression for k1 is only weakly temperature dependent, we report a temperature-independent value of k1 = (4.5 +/- 0.4) x 10-11 cm3 molecule-1 s-1. Additionally, an Arrhenius expression for k1b can also be derived: k1b = (7.7 +/- 0.8) x 10-11 exp[-(708 +/- 29)/T] cm3 molecule-1 s-1. These expressions for k1a and k1b are valid for 226 K T 336 and 256 K T 296 K, respectively. The cited errors are at the level of a single standard deviation. For the product measurements, an excess of Cl was added to known concentrations of HO2 and the reaction was allowed to reach completion. HCl product concentrations were determined by IR absorption yielding the ratio k1a/k1 over the temperature range 236 K T 296 K. OH product concentrations were determined by resonance fluorescence giving rise to the ratio k1b/k1 over the temperature

  17. High-efficiency resonantly pumped room temperature Ho:YVO4 laser.

    PubMed

    Li, Gang; Yao, Bao-Quan; Meng, Pei-Bei; Ju, You-Lun; Wang, Yue-Zhu

    2011-08-01

    An efficient 2 μm room temperature Ho:YVO(4) laser resonantly pumped by a 1.94 μm Tm:YAP laser is demonstrated, for the first time to our knowledge, in this Letter. Up to 8.58 W of laser output at 2053 nm is obtained with the optical-to-optical conversion efficiency as much as 41.2%. The output beam had quality of M2 factor with Mx(2) of 3.58 and My(2) of 1.76 at 8 W output level. In addition, we also obtained 4.18 W laser output at 2066 nm and 7.04 W at 2040 nm from the Ho:YVO(4) laser with conversion efficiency of 27.8% and 33.8%, respectively.

  18. Structure of three-quasiparticle isomers in {sup 169}Ho and {sup 171}Tm

    SciTech Connect

    Dracoulis, G. D.; Lane, G. J.; Hughes, R. O.; Kondev, F. G.; Chiara, C. J.; Watanabe, H.; Seweryniak, D.; Zhu, S.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Stefanescu, I.; Chowdhury, P.

    2010-09-15

    A three-quasiparticle isomer with {tau}=170(8) {mu}s and K{sup {pi}=} (19/2{sup +}) has been identified in the neutron-rich isotope {sup 169}Ho. The isomer decays with K-forbidden transitions to members of a band associated with the 7/2{sup -}[523] proton configuration, whose structure is characterized through analysis of the in-band {gamma}-ray branching ratios. In the isotone {sup 171}Tm, the rotational band based on the known 19/2{sup +}, three-quasiparticle isomer has also been observed. Alternative one-proton two-neutron configurations for the isomer in {sup 169}Ho are discussed in terms of multiquasiparticle calculations and through a comparison with the structures observed in {sup 171}Tm.

  19. [A Case of Holmium: YAG Laser Resection of Superficial Bladder Tumor (HoLRBT)].

    PubMed

    Sugita, Yoshiko; Shitara, Toshiya; Hirayama, Takahiro; Fujita, Tetsuo; Yoshida, Kazunari; Kubo, Seiichi; Iwamura, Masatsugu

    2015-10-01

    We present a case of holmium : YAG laser resection of superficial bladder tumor (HoLRBT). A 73-year-old male was referred to our hospital with elevated prostatic specific antigen. Due to difficulty of urination, holmium : YAG laser enucleation of the prostate was performed under the diagnosis of benign prostatic hyperplasia. During the surgery, superficial bladder tumor was incidentally identified, and HoLRBT was performed. After the operation, histopathological examination revealed urothelial carcinoma, G2 > G1, pTa. The patient has been subsequently followed up for 9 months, and there areno evidence of recurrence. Changing the holmium : YAG laser energy setting can potentially be effective and safe to approach a superficial bladder tumor.

  20. The normal and inverse magnetocaloric effect in RCu2 (R=Tb, Dy, Ho, Er) compounds

    NASA Astrophysics Data System (ADS)

    Zheng, X. Q.; Xu, Z. Y.; Zhang, B.; Hu, F. X.; Shen, B. G.

    2017-01-01

    Orthorhombic polycrystalline RCu2 (R=Tb, Dy, Ho and Er) compounds were synthesized and the magnetic properties and magnetocaloric effect (MCE) were investigated in detail. All of the RCu2 compounds are antiferromagnetic (AFM) ordered. As temperature increases, RCu2 compounds undergo an AFM to AFM transition at Tt and an AFM to paramagnetic (PM) transition at TN. Besides of the normal MCE around TN, large inverse MCE around Tt was found in TbCu2 compound. Under a field change of 0-7 T, the maximal value of inverse MCE is even larger than the value of normal MCE around TN for TbCu2 compound. Considering of the normal and inverse MCE, TbCu2 shows the largest refrigerant capacity among the RCu2 (R=Tb, Dy, Ho and Er) compounds indicating its potential applications in low temperature multistage refrigeration.

  1. Molecular dynamics simulation of graphene growth at initial stage on Ni(100) facet for low flux C energy by CVD

    NASA Astrophysics Data System (ADS)

    Syuhada, Ibnu; Rosikhin, Ahmad; Fikri, Aulia; Noor, Fatimah A.; Winata, Toto

    2016-02-01

    In this study, atomic simulation for graphene growth on Ni (100) at initial stage via chemical vapor deposition method has been developed. The C-C atoms interaction was performed by Terasoff potential mean while Ni-Ni interaction was specified by EAM (Embedded Atom Modified). On the other hand, we used very simple interatomic potential to describe Ni-C interaction during deposition process. From this simulation, it shows that the formation of graphene is not occurs through a combined deposition mechanism on Ni substrate but via C segregation. It means, Ni-C amorphous is source for graphene growth when cooling down of Ni substrate. This result is appropriate with experiments, tight binding and quantum mechanics simulation.

  2. Molecular dynamics simulation of graphene growth at initial stage on Ni(100) facet for low flux C energy by CVD

    SciTech Connect

    Syuhada, Ibnu Rosikhin, Ahmad Fikri, Aulia Noor, Fatimah A. Winata, Toto

    2016-02-08

    In this study, atomic simulation for graphene growth on Ni (100) at initial stage via chemical vapor deposition method has been developed. The C-C atoms interaction was performed by Terasoff potential mean while Ni-Ni interaction was specified by EAM (Embedded Atom Modified). On the other hand, we used very simple interatomic potential to describe Ni-C interaction during deposition process. From this simulation, it shows that the formation of graphene is not occurs through a combined deposition mechanism on Ni substrate but via C segregation. It means, Ni-C amorphous is source for graphene growth when cooling down of Ni substrate. This result is appropriate with experiments, tight binding and quantum mechanics simulation.

  3. Release of Ni from birnessite during transformation of birnessite to todorokite: Implications for Ni cycling in marine sediments

    NASA Astrophysics Data System (ADS)

    Atkins, Amy L.; Shaw, Samuel; Peacock, Caroline L.

    2016-09-01

    crystallinity of the neo-formed todorokite phase, but does not alter the mechanism and pathway of todorokite formation, compared to a Ni-free system. Furthermore, in systems tending towards todorokite as the final diagenetic product, we see that up to 50% of the Ni originally sequestered by birnessite is released to solution during the transformation. Our work indicates that the transformation of birnessite to todorokite in oxic marine sediments likely provides a significant source of Ni to marine sedimentary porewaters and potentially a hitherto unrecognized benthic flux of Ni to seawater.

  4. Anomalous Symmetries Of The Rovibrational Levels of HO2: Consequences Of A Conical Intersection

    NASA Technical Reports Server (NTRS)

    Barclay, V. J.; Dateo, C. E.; Hamilton, I. P.; Kendrick, B.; Pack, R. T.; Schwenke, D. W.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    We show that the geometric phase arising from a conical intersection of the lowest potential energy surfaces of HO2 causes its bending vibrational wavefunctions to be double valued, which allows them to be locally symmetric on one side of the intersection and locally antisymmetric on the other. The material of the proposed publication was reviewed and the technical content will not reveal any information not already in the public domain and will not give any foreign industry or government a competitive advantage.

  5. Activation of the complement cascade enhances motility of leukemic cells by downregulating expression of HO-1

    PubMed Central

    Abdelbaset-Ismail, A; Borkowska-Rzeszotek, S; Kubis, E; Bujko, K; Brzeźniakiewicz-Janus, K; Bolkun, L; Kloczko, J; Moniuszko, M; Basak, G W; Wiktor-Jedrzejczak, W; Ratajczak, M Z

    2017-01-01

    As a crucial arm of innate immunity, the complement cascade (ComC) is involved both in mobilization of normal hematopoietic stem/progenitor cells (HSPCs) from bone marrow (BM) into peripheral blood and in their homing to BM. Despite the fact that ComC cleavage fragments alone do not chemoattract normal HSPCs, we found that leukemia cell lines as well as clonogenic blasts from chronic myeloid leukemia and acute myeloid leukemia patients respond robustly to C3 and C5 cleavage fragments by chemotaxis and increased adhesion. This finding was supported by the detection of C3a and C5a receptors in cells from human malignant hematopoietic cell lines and patient blasts at the mRNA (reverse transcriptase-polymerase chain reaction) and protein level (fluorescence-activated cell sorting), and by the demonstration that these receptors respond to stimulation by C3a and C5a by phosphorylation of p42/44 and p38 mitogen-activated protein kinases (MAPK), and protein kinase B (PKB/AKT). We also found that inducible heme oxygenase 1 (HO-1) is a negative regulator of ComC-mediated trafficking of leukemic cells, and that stimulation of leukemic cells by C3 or C5 cleavage fragments activates p38 MAPK, which downregulates HO-1 expression, rendering cells more mobile. We conclude that activation of the ComC in leukemia/lymphoma patients (for example, as a result of accompanying infections) enhances the motility of malignant cells and contributes to their spread in a p38 MAPK–HO-1-dependent manner. Therefore, inhibition of p38 MAPK or upregulation of HO-1 by small-molecule modulators would have a beneficial effect on ameliorating cell migration-mediated expansion of leukemia/lymphoma cells when the ComC becomes activated. PMID:27451975

  6. Surface-water-resources information for the Ho-Chunk Nation lands and vicinity, Wisconsin

    USGS Publications Warehouse

    Diebel, Matthew W.; Sullivan, Daniel J.

    2003-01-01

    Qualitative assessments indicate that agricultural activities are the main contributing factor to water quality and fish habitat problems in the studied areas. Index of Biotic Integrity ratings, based on fish data, were available for 5 sites on 3 streams. Hilsenhoff Biotic Index ratings, based on macroinvertebrate data, were available for 21 sites on 4 streams. This information will serve as baseline data and as a guide to ongoing study and management of these waters by the Ho-Chunk Nation.

  7. Heterogeneous Chemistry of HO2NO2 on Liquid Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    1995-01-01

    The interaction of HO2NO2 (peroxynitric acid, PNA) vapor with liquid sulfuric acid surfaces was investigated for the acid contents ranging from 50 to 70 wt % and over a temperature range from 205 to 230 K, using a fast flow-reactor coupled to a chemical ionization mass spectrometer. PNA was observed to be physically taken up by liquid sulfuric acid, without undergoing irreversible aqueous phase reactions.

  8. Kinetics of the reaction between OH and HO sub 2 on the singlet potential energy surface

    SciTech Connect

    Gonzalez, C.; Theisen, J.; Zhu, Ling; Schlegel, H.B.; Hase, W.L. ); Kaiser, E.W. )

    1991-09-05

    Electronic structure calculations at the HF, MP2, and MP4 levels of theory, with the 6-31G** basis set, are reported for stationary points on the OH + HO{sub 2} singlet potential energy surface. Two particularly important stationary points are the trioxide (H{sub 2}O{sub 3}) global minimum and the reaction transition state for O{sub 2}({sup 1}{Delta}) + H{sub 2}O formation. For the latter, the MP4 0 K barrier height is 15.2 kcal/mol. Thus, the formation of O{sub 2}({sup 1}{Delta}) and H{sub 2}O is predicted to be unimportant, except at highly elevated temperatures. MP2 vibrational frequencies calculated for H{sub 2}O{sub 3} are in good agreement with the experiment. Reaction rate theory calculations are performed to assess the effect collisional stabilization of the vibrationally/rotationally excited intermediate H{sub 2}O{sub 3}* has on the apparent loss of the OH and HO{sub 2} reactants. In the high-pressure limit each of the H{sub 2}O{sub 3}* intermediates is collisionally stabilized. However, at intermediate pressures the importance of collisional stabilization depends on the OH + HO{sub 2} {yields} H{sub 2}O{sub 3} reaction exothermicity. The MP4 calculations reported here and a previous configuration interaction (CI) calculation place this exothermicity at {minus}22 to {minus}29 kcal/mol at 0 K. With use of these energies, the collisional stabilization of H{sub 2}O{sub 3}* at room temperature is predicted to become important only at pressures of an inefficient bath gas like He, the loss of the OH and HO{sub 2} reactants is predicted to occur only on the triplet potential energy surface.

  9. Excited state absorption and energy transfer in Ho3+-doped indium fluoride glass

    NASA Astrophysics Data System (ADS)

    Gomes, Laercio; Fortin, Vincent; Bernier, Martin; Maes, Frédéric; Vallée, Réal; Poulain, Samuel; Poulain, Marcel; Jackson, Stuart D.

    2017-04-01

    This investigation examines in detail the rates of energy transfer relevant to the 5I5 → 5I6 transition (at 3930 nm) in Ho3+-doped InF3 glass as a function of the Ho3+ concentration. The decay times, branching ratios and rate parameters for energy transfer were measured in this investigation for Ho3+ (x)-doped InF3 glass with x = 2, 4 and 10 mol.% and they were used as the input parameters for a rate equation analysis. Excited state absorption (ESA) initiating from the lower laser level is included in the study. Numerical simulation of CW laser emission at 3.9 μm was performed using two pump wavelengths, one for upper laser level excitation (i.e., 5I8 → 5I5 = λP1) and the other for lower laser level de-excitation (i.e., 5I6 → 5S2 = λP2). The pump wavelength λP2 = 962 nm was chosen based on the measurements of ESA and the application of the McCumber method. Critically, the estimated ESA cross section at λP2 = 962 nm (σESA = 7.1 × 10-21 cm2) is approximately sixteen times larger than ground state (5I8) absorption cross section (σGSA = 4.3 × 10-22 cm2) and ESA does not overlap with any ground state absorption process. Our calculations suggest that even for high Ho3+ concentration in which cross relaxation has been shown in a previous study to quench the 5I5 level, ESA is nevertheless strong enough to allow a sufficient population inversion required for practical CW emission.

  10. Stopping relativistic Xe, Ho, Au and U nuclei in nuclear emulsions

    NASA Technical Reports Server (NTRS)

    Waddington, C. J.; Fixsen, D. J.; Freier, P. S.

    1985-01-01

    Nuclei of Xe-54, Ho-67, Au-79 and U-92 accelerated at the Bevalac to energies between 1200 and 900 MeV/n were stopped in nuclear emulsions. The observed residual ranges were compared with those calculated from various models of energy loss and shown to be most consistent with a calculation that includes those higher order correction terms proposed previously to describe the energy loss of highly charged particles, for which the first Born approximation is not valid.

  11. Visualiser of two-micron laser radiation based on Ho:CaF{sub 2} crystals

    SciTech Connect

    Lyapin, A A; Ryabochkina, P A; Ushakov, S N; Fedorov, P P

    2014-06-30

    The anti-Stokes luminescence spectra of Ho:CaF{sub 2} crystals corresponding to the {sup 5}G{sub 4} → {sup 5}I{sub 8}, {sup 5}G{sub 5} → {sup 5}I{sub 8}, {sup 5}F{sub 3} → {sup 5}I{sub 8}, {sup 5}F{sub 4}({sup 5}S{sub 2}) → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 8}, {sup 5}S{sub 2} → {sup 5}I{sub 7}, {sup 5}I{sub 4} → {sup 5}I{sub 8}, {sup 5}I{sub 5} → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 7}, {sup 5}F{sub 3} → {sup 5}I{sub 6}, {sup 5}I{sub 6} → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 6}, and {sup 5}I{sub 5} → {sup 5}I{sub 7} transitions upon excitation of the {sup 5}I{sub 7} level of Ho{sup 3+} ions are studied. A method for visualisation of IR radiation in the two-micron range using Ho:CaF{sub 2} crystals is proposed. The energy efficiency of conversion of two-micron laser radiation to radiation in the red spectral range 620 – 690 nm by a 1 mol % HoF{sub 3}:CaF{sub 2} crystal is estimated to be no higher than 0.02%. (nonlinear optical phenomena)

  12. Analysis of emission spectra of Ho{sup 3+}:LFBCd glasses

    SciTech Connect

    Naresh, V. Buddhudu, S.

    2014-04-24

    In the present paper, we report on the absorption and emission properties of (0.1-1.5 mol %) Ho{sup 3+} doped LFBCd (Li{sub 2}O{sub −}LiF{sub −}B{sub 2}O{sub 3−}CdO) glasses prepared via melt quenching method. On exciting these glasses at (λ{sub exci}) = 452 nm, two emissions at 556 nm ({sup 5}S{sub 2}→{sup 5}I{sub 8}; Green), 655 nm ({sup 5}F{sub 5}→{sup 5}I{sub 8}; Red) have been obtained. Upon exciting these glasses with a 980 nm diode laser, NIR emissions at 1195 nm ({sup 5}I{sub 6}→{sup 5}I{sub 8}), 1951 nm ({sup 5}I{sub 7}→{sup 5}I{sub 8}) have been measured for 1 mol % Ho{sup 3+}:LFBCd glass. For higher concentration beyond 1.0 mol %, emission quenching of Ho{sup 3+} glass has been noticed and which has successfully been explained in terms of an energy level diagram. From absorption cross-section data, stimulated emission cross-section has been evaluated by applying McCumber's theory and further cross-sectional gain has also been computed for the emissions at 1195 nm (∼1.20 μm) and 1951 nm (∼2.0 μm) of 1 mol % Ho{sup 3+}:LFBCd glass.

  13. HO-1 inhibits preadipocyte proliferation and differentiation at the onset of obesity via ROS dependent activation of Akt2

    PubMed Central

    Wagner, Gabriel; Lindroos-Christensen, Josefine; Einwallner, Elisa; Husa, Julia; Zapf, Thea-Christin; Lipp, Katharina; Rauscher, Sabine; Gröger, Marion; Spittler, Andreas; Loewe, Robert; Gruber, Florian; Duvigneau, J. Catharina; Mohr, Thomas; Sutterlüty-Fall, Hedwig; Klinglmüller, Florian; Prager, Gerhard; Huppertz, Berthold; Yun, Jeanho; Wagner, Oswald; Esterbauer, Harald; Bilban, Martin

    2017-01-01

    Excessive accumulation of white adipose tissue (WAT) is a hallmark of obesity. The expansion of WAT in obesity involves proliferation and differentiation of adipose precursors, however, the underlying molecular mechanisms remain unclear. Here, we used an unbiased transcriptomics approach to identify the earliest molecular underpinnings occuring in adipose precursors following a brief HFD in mice. Our analysis identifies Heme Oxygenase-1 (HO-1) as strongly and selectively being upregulated in the adipose precursor fraction of WAT, upon high-fat diet (HFD) feeding. Specific deletion of HO-1 in adipose precursors of Hmox1fl/flPdgfraCre mice enhanced HFD-dependent visceral adipose precursor proliferation and differentiation. Mechanistically, HO-1 reduces HFD-induced AKT2 phosphorylation via ROS thresholding in mitochondria to reduce visceral adipose precursor proliferation. HO-1 influences adipogenesis in a cell-autonomous way by regulating events early in adipogenesis, during the process of mitotic clonal expansion, upstream of Cebpα and PPARγ. Similar effects on human preadipocyte proliferation and differentiation in vitro were observed upon modulation of HO-1 expression. This collectively renders HO-1 as an essential factor linking extrinsic factors (HFD) with inhibition of specific downstream molecular mediators (ROS & AKT2), resulting in diminished adipogenesis that may contribute to hyperplastic adipose tissue expansion. PMID:28102348

  14. Genetic detection and characterization of emerging HoBi-like viruses in archival foetal bovine serum batches.

    PubMed

    Giammarioli, M; Ridpath, J F; Rossi, E; Bazzucchi, M; Casciari, C; De Mia, G M

    2015-07-01

    Bovine viral diarrhea viruses (BVDV) are members of the Pestivirus genus within the family Flaviviridae. Based on antigenic and nucleotide differences, BVDV are classified into two recognized species, BVDV-1 and BVDV-2. More recently, a new putative pestivirus species, tentatively called "HoBi-like", has been associated with bovine viral diarrhea. HoBi-like viruses were first identified in fetal bovine serum (FBS) imported from Brazil. Subsequently, a number of HoBi-like viruses have been detected as contaminants in FBS or cell culture and in live ruminants. To further investigate the possible pestivirus contamination in commercially available FBS batches, 26 batches of FBS with various countries of origin, were tested in this study for the presence of bovine pestiviruses. All the 26 batches were positive by RT-PCR for at least one species of bovine pestiviruses. HoBi-like viruses were detected in 15 batches. Analysis of the 5'UTR and N(pro) sequences of 15 newly identified HoBi-like viruses combined with analysis of additional sequences from GenBank, identified 4 genetic groups tentatively named 3a-3d. The current study confirmed the presence of the emerging HoBi-like viruses in FBS products labeled with different geographic origins. This finding has obvious implications for the safety of biological products, such cell lines and vaccines.

  15. Multi-parametric thermal sensing based on NIR emission of Ho(III) doped CaWO4 phosphors

    NASA Astrophysics Data System (ADS)

    Zhou, Xianju; Wang, Rongxue; Xiang, Guotao; Jiang, Sha; Li, Li; Luo, Xiaobing; Pang, Yu; Tian, Yili

    2017-04-01

    Optical thermometry based on trivalent rare earth doped materials has attracted much attention recently. This article reported the temperature dependent near infrared luminescence of Ho3+ doped in CaWO4 phosphors. A series of CaWO4:Ho3+ powders have been synthesized by high temperature solid state reaction. The XRD patterns showed that the Ho3+ ions have occupied the lattice sites of Ca2+ ions in the phosphors. The thermometry effect was demonstrated by different spectroscopic parameters through the emission intensity of Ho3+: 5I6 → 5I8 transition at ∼1190 nm, the spectral shift of the charge transfer band of W-O and the lifetime of Ho3+: 5F4, 5S2 excited state. These three optical parameters present a simple linear relation with the temperature in the range of 30-300 °C. This allows for accurate thermal sensing based on simultaneous measurement of these parameters. Results show that CaWO4:Ho3+ phosphors might be served as a potential candidate for thermometry.

  16. Thermal decomposition of HO2NO2 (peroxynitric acid, PNA): rate coefficient and determination of the enthalpy of formation.

    PubMed

    Gierczak, Tomasz; Jiménez, Elena; Riffault, Veronique; Burkholder, James B; Ravishankara, A R

    2005-02-03

    Rate coefficients for the gas-phase thermal decomposition of HO(2)NO(2) (peroxynitric acid, PNA) are reported at temperatures between 331 and 350 K at total pressures of 25 and 50 Torr of N(2). Rate coefficients were determined by measuring the steady-state OH concentration in a mixture of known concentrations of HO(2)NO(2) and NO. The measured thermal decomposition rate coefficients k(-)(1)(T,P) are used in combination with previously published rate coefficient data for the HO(2)NO(2) formation reaction to yield a standard enthalpy for reaction 1 of Delta(r)H degrees (298K) = -24.0 +/- 0.5 kcal mol(-1) (uncertainties are 2sigma values and include estimated systematic errors). A HO(2)NO(2) standard heat of formation, Delta(f)H degrees (298K)(HO(2)NO(2)), of -12.6 +/- 1.0 kcal mol(-1) was calculated from this value. Some of the previously reported data on the thermal decomposition of HO(2)NO(2) have been reanalyzed and shown to be in good agreement with our reported value.

  17. Inhibitory effect of leptin on rosiglitazone-induced differentiation of primary adipocytes prepared from TallyHO/Jng mice

    SciTech Connect

    Kim, Ki Young; Kim, Joo Young; Sung, Yoon-Young; Jung, Won Hoon; Kim, Hee-Youn; Park, Ji Seon; Cheon, Hyae Gyeong; Rhee, Sang Dal

    2011-03-25

    Research highlights: {yields} In this study, we investigated the effects of leptin on adipocyte differentiation prepared from subcutaneous fat of TallyHo mice. {yields} Leptin inhibited the adipocytes differentiation at physiological concentration via inhibition of PPAR{gamma} expression. {yields} Inhibitors of ERK and STAT1 restored the leptin's inhibitory activity both in vitro and in vivo. -- Abstract: The effects of leptin on rosiglitazone-induced adipocyte differentiation were investigated in the primary adipocytes prepared from subcutaneous fat of TallyHO/Jng (TallyHO) mouse, a recently developed model animal for type 2 diabetes mellitus (T2DM). The treatment of leptin inhibited the rosiglitazone-induced adipocyte differentiation with a decreased expression of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) a key adipogenic transcription factor, both in mRNA and protein levels. Leptin (10 nM) was sufficient to inhibit the adipocyte differentiation, which seemed to come from increased expression of leptin receptor genes in the fat of TallyHO mice. The inhibition of adipogenesis by leptin was restored by the treatment of inhibitors for extracellular-signal-regulated kinase (ERK) (PD98059) and signal transducer and activator of transcription-1 (STAT1) (fludarabine). Furthermore, in vivo intraperitoneal administration of PD98059 and fludarabine increased the PPAR{gamma} expression in the subcutaneous fat of TallyHO mice. These data suggest that leptin could inhibit the PPAR{gamma} expression and adipocyte differentiation in its physiological concentration in TallyHO mice.

  18. Syntonized white up-converted emission by Tm3+-Yb3+-Er3+-Ho3+ doped ZrO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Solís, D.; López-Luke, T.; De La Rosa, E.; Meza, O.; Anderson, S.

    2010-02-01

    Although the general properties of the rare earths' electronic states and transitions are well understood, much less is known regarding the relationships between them and the electronic band states of a crystal lattice. These interactions can enhance or inhibit performance and provide mechanisms for manipulating the material's optical properties. Up-conversion ZrO2:Tm3+, Yb3+, Er3+, Ho3+ nano-crystalline samples were synthesized by sol-gel method and emission properties were analyzed as function of different concentrations of rare earth ions. The samples were pumped at 970 nm with a semiconductor laser source. The introduction of different ion concentrations affects the shape and peak intensities of the measured blue, green and red bands. Results showed in this work tend to demonstrate a feasible control of the chromaticity coordinates of emission and present an approximation to the equipotential white chromaticity coordinates.

  19. Long-term effect of heme oxygenase (HO)-1 induction in glomerular immune injury.

    PubMed

    Datta, Prasun K; Duann, Pu; Lianos, Elias A

    2006-03-01

    In a rat model of macrophage-dependent glomerular immune injury induced by administration of antibody against the glomerular basement membrane (anti-GBM), the authors assessed the anti-proteinuric effect of Heme Oxygenase-1 (HO-1) induction. Rats received anti-GBM antibody alone, anti-GBM antibody and treatment with the HO-1 inducer, hemin, or non-immune serum (controls). Urine protein, creatinine, and nitrite/nitrate excretion were measured on days 5, 7, and 14 after administration of the anti-GBM antibody. In hemin-treated animals with anti-GBM antibody-induced immune injury, HO-1 immunolocalized in macrophages infiltrating glomeruli and in tubular epithelial cells. In these animals, proteinuria was decreased. There was also a decrease in blood urea nitrogen (BUN) levels without a change in serum creatinine or systemic blood pressure. The observations establish the anti-proteinuric effect of hemin induction. This effect could be mechanistically linked to blunting of the ability of infiltrating macrophages to cause injury or to changes in tubular handling of filtered protein.

  20. Ho3+-doped strontium-aluminium-bismuth-borate glasses for green light emission.

    PubMed

    Rajesh, D; Dhamodhara Naidu, M; Ratnakaram, Y C; Balakrishna, A

    2014-11-01

    Strontium-aluminium-bismuth-borate glasses (SAlBiB) doped with different concentrations of Ho(3+) were prepared using conventional melt quenching technique and their structural and optical properties investigated. X-ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd-Ofelt (J-O) theory was applied to evaluate J-O intensity parameters, Ω(λ) (λ = 2, 4 and 6). Using J-O intensity parameters, radiative properties such as spontaneous transition probabilities (A(R)), branching ratios (β(R)) and radiative lifetimes (τ(R)) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, (5)S2 ((5)F4)→(5)I(8) was observed. Emission peak positions (λ(P)), effective bandwidths (Δλ(eff)) and stimulated emission cross-sections (σ(p)) were calculated for the observed emission transitions, (5)F3 →(5)I(8), (5)S2((5)F4)→(5)I(8) and (5)F5 →(5)I(8) of Ho(3+) in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho(3+) has better emission properties.

  1. Nadroparin sodium activates Nrf2/HO-1 pathway in acetic acid-induced colitis in rats.

    PubMed

    Yalniz, Mehmet; Demirel, Ulvi; Orhan, Cemal; Bahcecioglu, Ibrahim Halil; Ozercan, Ibrahim Hanefi; Aygun, Cem; Tuzcu, Mehmet; Sahin, Kazim

    2012-06-01

    Effects of nadroparin sodium, a low molecular weight heparin, in colitis was investigated by analyzing proteins implicated in nuclear factor E2-related factor-2/heme oxygenase-1 (Nrf2/HO-1) and nuclear factor kappa B (NF-κB) pathways. Twenty-eight rats were used. Colitis was induced by acetic acid (AA). Nadroparin sodium was given to prevention and treatment groups in addition to AA. Colitis was assessed histologically and levels of proteins were analyzed with Western blot. Nadroparin not only prevented and ameliorated the AA-induced colitis histopathologically but also decreased expression of colon NF-κB, activator protein-1, cyclooxygenase-2, tumor necrosis factor-alpha, and IL-6, which were significantly increased in group AA compared to control. The accumulation of Nrf2 in nuclear fraction and HO-1 found low in group AA was increased with nadroparin (p < 0.05). The mean malondialdehyde level increased with AA and was decreased significantly with nadroparin prevention and treatment (p < 0.001). Nadroparin sodium has both protective and therapeutic effects against colonic inflammation via exerting anti-oxidative and anti-inflammatory effects by modulating Nrf2/HO-1 and NF-κB pathways.

  2. Mitochondrial quality-control dysregulation in conditional HO-1–/– mice

    PubMed Central

    Suliman, Hagir B.; Keenan, Jeffrey E.; Piantadosi, Claude A.

    2017-01-01

    The heme oxygenase-1 (Hmox1; HO-1) pathway was tested for defense of mitochondrial quality control in cardiomyocyte-specific Hmox1 KO mice (HO-1[CM]–/–) exposed to oxidative stress (100% O2). After 48 hours of exposure, these mice showed persistent cardiac inflammation and oxidative tissue damage that caused sarcomeric disruption, cardiomyocyte death, left ventricular dysfunction, and cardiomyopathy, while control hearts showed minimal damage. After hyperoxia, HO-1(CM)–/– hearts showed suppression of the Pgc-1α/nuclear respiratory factor-1 (NRF-1) axis, swelling, low electron density mitochondria by electron microscopy (EM), increased cell death, and extensive collagen deposition. The damage mechanism involves structurally deficient autophagy/mitophagy, impaired LC3II processing, and failure to upregulate Pink1- and Park2-mediated mitophagy. The mitophagy pathway was suppressed through loss of NRF-1 binding to proximal promoter sites on both genes. These results indicate that cardiac Hmox1 induction not only prevents heme toxicity, but also regulates the timing and registration of genetic programs for mitochondrial quality control that limit cell death, pathological remodeling, and cardiac fibrosis. PMID:28194437

  3. Treatment of hyperplastic inferior nasal turbinates by means of a Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Sroka, Ronald; Leunig, Andreas; Janda, P.; Rosler, P.; Grevers, G.; Baumgartner, Reinhold

    1999-06-01

    Although the successful use of the Ho:YAG laser in nasal turbinate surgery had been reported no clinical study had been performed to assess the clinical outcome in longterm. By means of a pulsed Ho:YAG laser emitting at λ=2080nm (1J/pulse, 3-8 Hz) 57 patients suffering from nasal obstruction due to allergic rhinitis and vasomotoric rhinitis were treated under local anesthesia. The study was conducted by standardized questionnaire, photo documentation, allergy test, mucocilliar test, rhinomanometry, radiology and histology. Within 2 weeks after laser treatment a significant improvement of nasal airflow correlating to the extent of the ablated turbinate tissue could be determined. This effect lasted up until 1 year post treatment resulting in an improved quality of life in more than 80 percent of the patients. Side effects like nasal dryness and pain were rare (<4%), no immediate complications were observed. The total treatment time takes 3-8 min and nasal packing was not necessary after the laser procedure. In conclusion Ho:YAG laser treatment can be performed as an outpatient procedure under local anesthesia with excellent ablation of soft tissue in a short treatment time with promising results.

  4. The Status of the MARE Experiment with 187Re and 163Ho Isotopes

    NASA Astrophysics Data System (ADS)

    Ferri, E.; Bagliani, D.; Biasotti, M.; Ceruti, G.; Corsini, D.; Faverzani, M.; Gatti, F.; Giachero, A.; Gotti, C.; Kilbourne, C.; Kling, A.; Maino, M.; Manfrinetti, P.; Nucciotti, A.; Pessina, G.; Pizzigoni, G.; Gomes, M. Ribeiro; Sisti, M.

    Neutrino oscillation experiments have proved that neutrinos are massive particles but the assessment of their absolute mass scale is still an outstanding challenge in today particle physics and cosmology. The laboratory experiments dedicated to effective electron-neutrino mass determination are the ones based on the study of single beta decay or electron capture (EC) decay. Exploiting only on energy-momentum conservation, this kinematic measurement is the only one which permits to estimate neutrino masses without theoretical assumptions on neutrino nature and it is truly model-independent. To date the most competitive isotopes for a calorimetric measurement of the neutrino mass are 187Re and 163Ho. While the first decays beta, the latter decays via electron capture, and both have a Q-value around 2.5 keV. The measurement of 163Ho EC is an appealing alternative to the 187Re beta decay measurement because few nuclei are needed and it is a self-calibrating measurement. In this context the MARE project, based on rhenium thermal detectors has been born. We report here the status of MARE in Milan with Rhenium and the activity concerning the production of radioactive 163Ho isotope in the framework of MARE.

  5. Coherent polarization locking of Q-switched Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Chua, C. F.; Tan, L. H.; Phua, P. B.

    2013-03-01

    We had demonstrated the use of Coherent Polarization Locking (CPL) to mitigate the intra-cavity optical damage in a Q-switched Ho:YAG laser. By splitting the available pump power into two individual Ho:YAG laser rods, we had passively coherent combined two orthogonal polarized lasers with output pulse energy of 9.13mJ, pulse width of 14ns, operating at 800Hz pulse repetition rate. In contrast, when all the pump power was pumped on a single Ho:YAG laser rod built with the same cavity configuration, severe optical damage was observed. It was occurred at the surface coating of the laser rod when operating at < 2kHz pulse repetition rate, thus limiting the output pulse energy to < 5mJ. We also demonstrated, first to our knowledge, that by performing Q-switching only in one of the laser arms, it resulted in pulse operation for the entire CPL laser cavity.

  6. Passively Q-switched Ho:YLF laser pumped by Tm3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Ju, Youlun; Yao, Baoquan; Dai, Tongyu; Duan, Xiaoming; Li, Jiang; Ding, Yu; Liu, Wei; Pan, Yubai; Li, Chaoyu

    2016-03-01

    We demonstrate a compact and efficient passively Q-switched (PQS) Ho:YLF laser pumped by a self-made all-fiber laser. Firstly, we design and make an all-fiber laser operating at 1940 nm with a slope efficiency of 40.6%. Then, the all-fiber laser was used to pump Ho:YLF laser directly. In the CW (continues-wave) operation Ho:YLF laser, the maximum output power was 7.79 W, corresponding to the slope efficiency of 55.2%. Using Cr2+:ZnS as the saturable absorber, the average power of 6.03 W was achieved with the slope efficiency of 45.9%. The shortest pulse duration was 15.6 ns and the pulse repetition frequency was 2.3 kHz at the pump power of 20.4 W. The pulse energy was a constant as 2.7 mJ when the pump power exceeded 15 W. The beam quality factor of M2 was 1.05, indicating nearly diffraction limited beam propagation.

  7. High Resolution Neutron Scattering Study of Ho2Ti2O7

    NASA Astrophysics Data System (ADS)

    Gardner, Jason

    2010-03-01

    I will review recent neutron scattering work on the pyrochlore oxides Ho2Ti2O7, looking at the slow spin dynamics in the system. For many years now, the nuclear spin system was held responsible for the persistent (electronic) spin dynamics in Ho2Ti2O7 at mK temperatures. We can now measure both spin systems directly with the improved signal to noise ratio seen at modern back scattering instrumentation. I hope to show this is not the case. To complicate the story further propagating magnetic ``monopoles'' have now been observed in this and other spin ice materials. I will comment on these exotic excitations and what our data can say about them. This work was performed in collaboration with Georg Ehlers and other at the SNS, in Oak Ridge. [4pt] [1] ``Direct observation of a nuclear spin excitation in Ho2Ti2O7'' G Ehlers, E Mamontov, M Zamponi, K C Kam and J S Gardner, Phys. Rev. Lett. 102, 016405 (2009). [0pt] [2] ``Observation of Magnetic Monopoles in Spin Ice'' Kadowaki et al., J. Phys. Soc Japan 78 103706 (2009) and Signature of magnetic monopole and Dirac string dynamics in spin ice'' Jaubert and Holdsworth, Nature Phys. 5, 258 (2009).

  8. Nutritional control of IL-23/Th17-mediated autoimmune disease through HO-1/STAT3 activation

    PubMed Central

    Brück, Jürgen; Holstein, Julia; Glocova, Ivana; Seidel, Ursula; Geisel, Julia; Kanno, Toshio; Kumagai, Jin; Mato, Naoko; Sudowe, Stephan; Widmaier, Katja; Sinnberg, Tobias; Yazdi, Amir S.; Eberle, Franziska C.; Hirahara, Kiyoshi; Nakayama, Toshinori; Röcken, Martin; Ghoreschi, Kamran

    2017-01-01

    The nutritional curcumin (CUR) is beneficial in cell-mediated autoimmune diseases. The molecular mechanisms underlying this food-mediated silencing of inflammatory immune responses are poorly understood. By investigating antigen-specific immune responses we found that dietary CUR impairs the differentiation of Th1/Th17 cells in vivo during encephalomyelitis and instead promoted Th2 cells. In contrast, feeding CUR had no inhibitory effect on ovalbumin-induced airway inflammation. Mechanistically, we found that CUR induces an anti-inflammatory phenotype in dendritic cells (DC) with enhanced STAT3 phosphorylation and suppressed expression of Il12b and Il23a. On the molecular level CUR readily induced NRF2-sensitive heme oxygenase 1 (HO-1) mRNA and protein in LPS-activated DC. HO-1 enhanced STAT3 phosphorylation, which enriched to Il12b and Il23a loci and negatively regulated their transcription. These findings demonstrate the underlying mechanism through which a nutritional can interfere with the immune response. CUR silences IL-23/Th17-mediated pathology by enhancing HO-1/STAT3 interaction in DC. PMID:28290522

  9. Magnetic and superconducting phase diagram of the half-Heusler topological semimetal HoPdBi.

    PubMed

    Nikitin, A M; Pan, Y; Mao, X; Jehee, R; Araizi, G K; Huang, Y K; Paulsen, C; Wu, S C; Yan, B H; de Visser, A

    2015-07-15

    We report a study of the magnetic and electronic properties of the non-centrosymmetric half-Heusler antiferromagnet HoPdBi (TN = 2.0 K). Magnetotransport measurements show HoPdBi has a semimetallic behavior with a carrier concentration n = 3.7 × 10(18) cm(-3) extracted from the Shubnikov-de Haas effect. The magnetic phase diagram in the field-temperature plane has been determined by transport, magnetization, and thermal expansion measurements: magnetic order is suppressed at BM ~ 3.6 T for T --> 0. Superconductivity with Tc ~ 1.9 K is found in the antiferromagnetic phase. Ac-susceptibility measurements provide solid evidence for bulk superconductivity below Tc = 0.75 K with a screening signal close to a volume fraction of 100%. The upper critical field shows an unusual linear temperature variation with Bc2(T --> 0) = 1.1 T. We also report electronic structure calculations that classify HoPdBi as a new topological semimetal, with a non-trivial band inversion of 0.25 eV.

  10. Pulsed laser photolysis study of the reaction between O(3P) and HO2

    NASA Technical Reports Server (NTRS)

    Ravishankara, A. R.; Wine, P. H.; Nicovich, J. M.

    1983-01-01

    It is pointed out that bimolecular reactions involving two free radicals are of great interest because both reactants have unpaired electrons and hence could interact at distances longer than those typical of radical-molecule encounters. A method based on laser photolysis is being developed to produce selectively free radicals in the homogeneous gas phase. This is to be done in such a way as to isolate the reaction of interest and subsequently follow the course of the reaction using spectroscopic techniques. The present investigation is concerned with a study in which the rate coefficient for the reaction of O(3P) with HO2, has been measured at N2 pressures ranging from 10 to 500 torr, taking into account the reaction O(3P)+HO2 yields OH-O2. In the described study, O(3P) and HO2 were produced by cophotolysis of O3 and H2O2 in N2 at 248.5 nm using a KrF excimer laser.

  11. Identification and epidemiology of a rare HoBi-like pestivirus strain in Bangladesh.

    PubMed

    Haider, N; Rahman, M S; Khan, S U; Mikolon, A; Gurley, E S; Osmani, M G; Shanta, I S; Paul, S K; Macfarlane-Berry, L; Islam, A; Desmond, J; Epstein, J H; Daszak, P; Azim, T; Luby, S P; Zeidner, N; Rahman, M Z

    2014-06-01

    The genus pestivirus of the family flaviviridae consists of four recognized species: bovine viral diarrhoea virus 1 (BVDV-1), bovine viral diarrhoea virus 2 (BVDV-2), classical swine fever virus and border disease virus. A new putative pestivirus species tentatively named as either 'HoBi-like pestivirus' or BVDV-3 has recently been identified in Brazil, Italy and Thailand. Despite reports of serological evidence of BVDV in Bangladesh, the types of the virus circulating in cattle have not been identified. We conducted surveillance in cattle from May 2009 to August 2010 in three government veterinary hospitals to characterize BVDV in cattle of Bangladesh. We tested serum for BVDV using an antigen-capture ELISA. Of 638 cattle samples, 3% (16/638) tested positive for BVDV antigen. The ELISA-positive samples were selected for further molecular detection and characterization of BVDV. Molecular analysis of the partial 5' untranslated region (UTR) nucleotide sequences of BVDV-positive samples identified the rare HoBi-like pestivirus or BVDV-3 virus circulating in cattle of Bangladesh. The identification of this rare HoBi-like pestivirus or BVDV-3 strain in Bangladesh warrants further surveillance to evaluate its impact on livestock production.

  12. t-BHQ Provides Protection against Lead Neurotoxicity via Nrf2/HO-1 Pathway

    PubMed Central

    Ye, Fang; Li, Xiaoyi; Li, Lili; Yuan, Jing; Chen, Jun

    2016-01-01

    The neurotoxicity of lead has been well established, and oxidative stress is strongly associated with lead-induced neurotoxicity. Nrf2 is important for protection against oxidative stress in many disease models. We applied t-BHQ, which is an Nrf2 activator, to investigate the possible role of Nrf2 in the protection against lead neurotoxicity. t-BHQ significantly attenuated the oxidative stress in developmental rats by decreasing MDA level, as well as by increasing SOD activity and GSH content, in the hippocampus and frontal cortex. Furthermore, neuronal apoptosis was detected by Nissl staining, and Bax expression was inhibited in the t-BHQ-treated group. Results showed that t-BHQ suppressed ROS production and caspase 3/7 activity but increased intracellular GSH content, in SH-SY5Y cells under lead exposure. Moreover, in vivo and in vitro, t-BHQ enhanced the nuclear translocation of Nrf2 and binding to ARE areas but did not induce Nrf2 transcription. These phenomena were confirmed using RT-PCR, EMSA, Western blot, and immunofluorescence analyses. Subsequent upregulation of the expression of HO-1, NQO1, and GCLC was observed. However, knockdown of Nrf2 or HO-1 adversely affected the protective effects of t-BHQ against lead toxicity in SH-SY5Y cells. Thus, t-BHQ can protect against lead neurotoxicity, depending on the Nrf2/HO-1 pathway. PMID:26798413

  13. Phonon Drag and Magnetic Anomalies, of Thermopower, in RB12 (R = Ho, Er, Tm, Lu)

    NASA Astrophysics Data System (ADS)

    Glushkov, V.; Demishev, S.; Ignatov, M.; Khayrullin, E.; Sluchanko, N.; Shitsevalov, N.; Levchenko, A.; Filipov, V.; Flachbart, K.; Siemensmeyer, K.

    2008-01-01

    High precision measurements of the Seebeck coefficient S(T) were carried out on the single crystals of RB12 (R = Ho, Er, Tm, Lu) at temperatures 2-300 K. It was shown that the effects of phonon drag result from vibrations of rare earth ions (ℏ ωE≈10-33 meV) in the rigid framework structure of the B12 clusters and determine the main contribution to thermopower at intermediate temperatures (30-300 K). The correlated behavior of transport parameters favors the appreciable enhancement of spin fluctuations in the sequence of magnetic compounds (HoB12-TmB12) when approaching to the valence instability state in YbB12. The giant increase in S(T) detected in the vicinity of the Néel temperature TN for HoB12, ErB12, and TmB12 seems to result from the density of states renormalization caused by antiferromagnetic ordering.

  14. White light emitting Ho{sup 3+}-doped CdS nanocrystal ingrained glass nanocomposites

    SciTech Connect

    Dey, Chirantan; Karmakar, Basudeb; Goswami, Madhumita

    2015-02-23

    We report the generation of white light from Ho{sup 3+} ion doped CdS nanocrystal ingrained borosilicate glass nanocomposites prepared by the conventional melt-quench method. Near visible 405 nm diode laser excited white light emission is produced by tuning the blue emission from the Ho{sup 3+} ions, green band edge, and orange-red surface-state emissions of the nanocrystalline CdS, which are further controlled by the size of the nanocrystals. The absorption and emission spectra evidenced the excitation of Ho{sup 3+} ions by absorption of photons emitted by the CdS nanocrystals. The high color rendering index (CRI = 84–89) and befitting chromaticity coordinates (x = 0.308–0.309, y = 0.326–0.338) of white light emission, near visible harmless excitation wavelength (405 nm), and high absorbance values at excitation wavelength point out that these glass nanocomposites may serve as a prominent candidate for resin free high power white light emitting diodes.

  15. Isotope correlations as a probe for freeze-out characterization: central 124Sn+ 64Ni, 112Sn+ 58Ni collisions

    NASA Astrophysics Data System (ADS)

    Geraci, E.; Alderighi, M.; Anzalone, A.; Auditore, L.; Baran, V.; Bartolucci, M.; Berceanu, I.; Blicharska, J.; Bonasera, A.; Borderie, B.; Bougault, R.; Bruno, M.; Brzychczyk, J.; Cardella, G.; Cavallaro, S.; Chbihi, A.; Cibor, J.; Colonna, M.; D'Agostino, M.; De Filippo, E.; Di Toro, M.; Giustolisi, F.; Grzeszczuk, A.; Guazzoni, P.; Guinet, D.; Iacono-Manno, M.; Kowalski, S.; La Guidara, E.; Lanzalone, G.; L´, G.; Le Neindre, N.; Li, S.; Lo Nigro, S.; Maiolino, C.; Majka, Z.; Manfredi, G.; Paduszynski, T.; Pagano, A.; Papa, M.; Petrovici, M.; Piasecki, E.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Rivet, M. F.; Rosato, E.; Russo, S.; Russotto, P.; Sechi, G.; Simion, V.; Sperduto, M. L.; Steckmeyer, J. C.; Trifiro`, A.; Trimarchi, M.; Vannini, G.; Vigilante, M.; Wieleczko, J. P.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W.

    2004-04-01

    124Sn+ 64Ni and 112Sn+ 58Ni reactions at 35 AMeV incident energy were studied with the forward part of CHIMERA multi-detector. The most central collisions were selected by means of a multidimensional analysis. The characteristics of the source formed in the central collisions, as size, temperature and volume, were inspected. The measured isotopes of light fragments (3 ⩽ Z ⩽ 8) were used to examine isotope yield ratios that provide information on the free neutron to proton densities.

  16. Comparison of acute oxidative stress on rat lung induced by nano and fine-scale, soluble and insoluble metal oxide particles: NiO and TiO2.

    PubMed

    Horie, Masanori; Fukui, Hiroko; Endoh, Shigehisa; Maru, Junko; Miyauchi, Arisa; Shichiri, Mototada; Fujita, Katsuhide; Niki, Etsuo; Hagihara, Yoshihisa; Yoshida, Yasukazu; Morimoto, Yasuo; Iwahashi, Hitoshi

    2012-06-01

    The aim of the present study is to understand the association between metal ion release from nickel oxide (NiO) nanoparticles and induction of oxidative stress in the lung. NiO nanoparticles have cytotoxic activity through nickel ion release and subsequent oxidative stress. However, the interaction of oxidative stress and nickel ion release in vivo is still unclear. In the present study, we examined the effect of metal ion release on oxidative stress induced by NiO nanoparticles. Additionally, nano and fine TiO(2) particles as insoluble particles were also examined. Rat lung was exposed to NiO and TiO(2) nanoparticles by intratracheal instillation. The NiO nanoparticles released Ni(2+) in dispersion. Bronchoalveolar lavage fluid (BALF) was collected at 1, 24, 72 h and 1 week after instillation. The lactate dehydrogenase (LDH) and HO-1 levels were elevated at 24 and 72 h after instillation in the animals exposed to the NiO nanoparticles. On the other hand, total hydroxyoctadecadienoic acid (tHODE), which is an oxidative product of linoleic acid, as well as SP-D and α-tochopherol levels were increased at 72 h and 1 week after instillation. Fine NiO particles, and nano and fine TiO(2) particles did not show lung injury or oxidative stress from 1 h to 1 week after instillation. These results suggest that Ni(2+) release is involved in the induction of oxidative stress by NiO nanoparticles in the lung. Ni(2+) release from NiO nanoparticles is an important factor inoxidative stress-related toxicity, not only in vitro but also in vivo.

  17. Theoretical study of the unimolecular dissociation HO2 --> H+O2. I. Calculation of the bound states of HO2 up to the dissociation threshold and their statistical analysis

    NASA Astrophysics Data System (ADS)

    Dobbyn, Abigail J.; Stumpf, Michael; Keller, Hans-Martin; Schinke, Reinhard

    1995-12-01

    This is the first of a series of papers in which we investigate the unimolecular dissociation of hydroperoxyl. Using the DMBE IV potential energy surface [Pastrana et al., J. Phys. Chem. 94, 8073 (1990)], in the present study 726 bound states of HO2(X˜) up to the H+O2 dissociation threshold are calculated in an attempt to access the extent of the coupling between the modes of the system. The first approach involves an analysis of the nodal structure of the wave functions. While the wave functions for the lowest states are regular and assignable, the degree of mixing and complexity rapidly increases with energy. The wave functions close to the dissociation threshold are mostly irregular without any clear cut nodal structure and fill the entire coordinate space available. Nevertheless, a small number of regular states, that are associated with large excitation in the O2 stretching coordinate and no or only little excitation in the other modes, are found even at high energies. The second approach used to study the degree of intramolecular coupling is an analysis of the energy spectrum. The nearest neighbor level spacing distribution, which probes the short-range correlation, as well as the Σ2 and Δ3 statistics, which are sensitive to the long-range correlations in the spectrum, are investigated and compared to the distributions predicted for regular and irregular spectra. Both of these approaches indicate that the system is almost totally irregular with a Brody parameter of about 92%. In addition, the sum of states at a particular energy, which is extremely important in all statistical models for unimolecular dissociation, is approximately calculated from the volume of classical phase space and found to be in excellent agreement with the exact quantum mechanical result.

  18. Investigation of Ni@CoO core-shell nanoparticle films synthesized by sequential layer deposition

    NASA Astrophysics Data System (ADS)

    Spadaro, M. C.; Luches, P.; Benedetti, F.; Valeri, S.; Turchini, S.; Bertoni, G.; Ferretti, A. M.; Capetti, E.; Ponti, A.; D'Addato, S.

    2017-02-01

    Films of Ni@CoO core-shell nanoparticles (NP Ni core size d ≈ 11 nm) have been grown on Si/SiOx and lacey carbon supports, by a sequential layer deposition method: a first layer of CoO was evaporated on the substrate, followed by the deposition of a layer of pre-formed, mass-selected Ni NPs, and finally an overlayer of CoO was added. The Ni NPs were formed by a magnetron gas aggregation source, and mass selected with a quadrupole mass filter. The morphology of the films was investigated with Scanning Electron Microscopy and Scanning Transmission Electron Microscopy. The Ni NP cores have a shape compatible with McKay icosahedron, caused by multitwinning occurring during their growth in the source, and the Ni NP layer shows the typical random paving growth mode. After the deposition of the CoO overlayer, CoO islands are observed, gradually extending and tending to merge with each other, with the formation of shells that enclose the Ni NP cores. In situ X-ray Photoelectron Spectroscopy showed that a few Ni atomic layers localized at the core-shell interface are oxidized, hinting at the possibility of creating an intermediate NiO shell between Ni and CoO, depending on the deposition conditions. Finally, X-ray Magnetic Circular Dichroism at the Ni L2,3 absorption edge showed the presence of magnetization at room temperature even at remanence, revealing the possibility of magnetic stabilization of the NP film.

  19. Contrasting Effects of Ca{sup 2+} and Ho{sup 3+} Substitutions on Superconductivity and Excess conductivity of (Ho{sub 1-x}Ca{sub x})(Ba{sub 2-y}Ho{sub y})Cu{sub 3}O{sub 7-{delta}}

    SciTech Connect

    Maulud, M. F.; Hamidi, Z. S.; Yusof, A. A.; Yusof, M. I. M.; Yahya, A. K.

    2010-07-07

    Effects of Ho{sup 3+} and Ca{sup 2+} substitutions in (Ho{sub 1-x}Ca{sub x})(Ba{sub 2-y}Ho{sub y})Cu{sub 3}O{sub 7-{delta}}ceramics on normal and superconducting state behaviour were investigated. Electrical resistivity measurements showed increasing Ho{sup 3+} substitution at Ba{sup 2+} site (x = 0, 0.4, y = 0-0.4) caused normal state resistivity to change from metal-like to semimetal/semiconductor-like behaviour and suppressed T{sub c} from 89 K (y = 0) to 72 K (y = 0.4) while substitution of Ca{sup 2+} for Ho{sup 3+}((x = 0.2) 0.4, (y 0.4)) revives metallic behaviour of the normal state with increasing x. Excess conductivity analysis based on Asmalazov-Larkin theory showed 2D to 3D transition for all superconducting samples but with contrasting effects of the substitutions on AL{sub 2D} and AL{sub 3D} constants. The resistivity and excess conductivity results indicate effective hole filling Ho{sup 3+} and hole doping by by Ca{sup 2+} substitutions.

  20. Self-Assembly of Hierarchical Ni-Mo-Polydopamine Microflowers and their Conversion to a Ni-Mo2 C/C Composite for Water Splitting.

    PubMed

    Sun, Lianshan; Wang, Chunli; Sun, Qujiang; Cheng, Yong; Wang, Limin

    2017-02-13

    With the aim of finding efficient non-noble metal catalysts for water splitting, hierarchical Ni-Mo-polydopamine microflowers (Ni-Mo2 C/C MF) were synthesized through a facile aqueous-phase reaction at room temperature. NiMoO4 nanowires were utilized as both Ni and Mo source; they can complex with dopamine to form a hierarchical structure and affect the scale of the final product. The energy dispersive spectroscopy (EDS) measurement of Ni-Mo2 C/C microflowers (MF) shows a high content of Mo2 C and Ni (>90 wt %). For the hydrogen evolution reaction (HER), the Ni-Mo2 C/C MF displays a low overpotential of 99 mV at a current density of -10 mA cm(-2) and a small Tafel slope of 73 mV dec(-1) in 1.0 m KOH. By comparison with Mo2 C/C microspheres (MS), the nanosized Ni-doped particles offer more active sites and enhance the kinetic performance. This facile synthesis strategy is also suitable for preparing other metal-Mo2 C/C composites that can be used in the fields of catalysis and energy conversion.

  1. Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

    SciTech Connect

    Gupta, Vinay Kawaguchi, Toshikazu; Miura, Norio

    2009-01-08

    Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co{sub 3}O{sub 4}, NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm{sup 2} current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides.

  2. Domain Structures and Anisotropy in Exchange-coupled [Co/Pd]-NiFe and [Co/Ni]-NiFe Multilayers

    NASA Astrophysics Data System (ADS)

    Tryputen, Larysa; Chung, Sunjae; Mohseni, Majid; Nguyen, T. N. Anh; Åkerman, Johan; Guo, Feng; McMichael, Robert D.; Ross, Caroline A.

    2014-03-01

    Exchange-coupled multilayers [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe with strong perpendicular magnetic anisotropy have been proposed to use in spin-torque switching and oscillators devices with tilted fixed and free layer to improve their functional performance. We present an experimental study of the magnetization behavior of [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe multilayers measured using magnetometry, magnetic force microscopy (MFM) and ferromagnetic resonance (FMR) as a function of the thickness of the top NiFe layer. We varied the thickness of the NiFe layer in [Co/Pd]5-NiFe (t), t = 0 - 80 nm and [Co/Ni]4-NiFe (t), t = 0.5 - 2.5 nm in order to study the interplay between perpendicular magnetization of the Co/Pd or Co/Ni multilayers and in-plane magnetization of the NiFe. Our magnetometry and FMR data suggest that the [Co/Ni]4/NiFe multilayer behaves like a homogeneous ferromagnetic film with anisotropy that reorients towards in-plane as the NiFe thickness increases, whereas the [Co/Pd]5/NiFe multilayer reveals more complex behavior in which the [Co/Pd] layer retains out-of-plane anisotropy while the magnetization of NiFe layer tilts in-plane with increasing thickness. MFM showed that domains with ~0.1 +/-m size were visible in [Co/Pd]-/NiFe with NiFe thickness of 20-80 nm. Multilayers were patterned into sub-100 nm dots using ion beam etching and their magnetization behavior are compared with unpatterned films.

  3. NRF2 activation is involved in ozonated human serum upregulation of HO-1 in endothelial cells

    SciTech Connect

    Pecorelli, Alessandra; Bocci, Velio; Acquaviva, Alessandra; Belmonte, Giuseppe; Gardi, Concetta; Virgili, Fabio; Ciccoli, Lucia; Valacchi, Giuseppe

    2013-02-15

    During the last decade, it has been shown that the activation of NRF2 and the binding to electrophile-responsive element (EpREs), stimulates the expression of a great number of genes responsible for the synthesis of phase I and phase II proteins, including antioxidants enzymes and heme oxygenase-1 (HO-1). This critical cell response occurs in cardiovascular, degenerative and chronic infective diseases aggravated by a chronic oxidative stress. In our previous reports we have shown that ozonated plasma is able to up-regulate HO-1 expression in endothelial cells. In the present work we investigated a candidate mechanism involved in this process. After treatment with increasing doses of ozonated serum (20, 40 and 80 μg/mL O{sub 3} per mL of serum), a clear dose dependent activation of NRF2 and the subsequent induction of HO-1 and NAD(P)H quinone oxidoreductase 1(NQO1) was observed. This effect was also present when cells were treated with serum and hydrogen peroxide (H{sub 2}O{sub 2}) or serum and 4-hydroxynonenal (4HNE). Moreover, the treatment with ozonated serum was associated with a dose-dependent activation of extracellular-signal-regulated kinases (ERK1/2) and p38 MAP kinases (p38), not directly involved in NRF2 activation. These data, provide a new insight on the mechanism responsible for the induction of HO-1 expression by ozonated serum in the endothelium, and have a practical importance as an expedient approach to the treatment of patients with both effective orthodox drugs and ozonated autohemotherapy, targeted to the restoration of redox homeostasis. - Highlights: ► Endothelial HO1 is upregulated by ozonated plasma ► This activation is induced by NRF2 and it is ERK independent. ► 4HNE and H{sub 2}O{sub 2} are the main molecules involved in this process. ► Ozonated plasma induced a hormetic effect ► Combination of orthodox medicine and ozonated plasma can be a useful treatment.

  4. One-Pot Solvothermal in Situ Growth of 1D Single-Crystalline NiSe on Ni Foil as Efficient and Stable Transparent Conductive Oxide Free Counter Electrodes for Dye-Sensitized Solar Cells.

    PubMed

    Bao, Chao; Li, Faxin; Wang, Jiali; Sun, Panpan; Huang, Niu; Sun, Yihua; Fang, Liang; Wang, Lei; Sun, Xiaohua

    2016-12-07

    One-dimensional single-crystal nanostructural nickel selenides were successfully in situ grown on metal nickel foils by two simple one-step solvothermal methods, which formed NiSe/Ni counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The nickel foil acted as the nickel source in the reaction process, a supporting substrate, and an electron transport "speedway". Electrochemical testing indicated that the top 1D single-crystal NiSe exhibited prominent electrocatalytic activity for I3(-) reduction. Due to the metallic conductivity of Ni substrate and the outstanding electrocatalytic activity of single-crystal NiSe, the DSSC based on a NiSe/Ni CE exhibited higher fill factor (FF) and larger short-circuit current density (Jsc) than the DSSC based on Pt/FTO CE. The corresponding power conversion efficiency (6.75%) outperformed that of the latter (6.18%). Moreover, the NiSe/Ni CEs also showed excellent electrochemical stability in the I(-)/I3(-) redox electrolyte. These findings indicated that single-crystal NiSe in situ grown on Ni substrate was a potential candidate to replace Pt/TCO as a cheap and highly efficient counter electrode of DSSC.

  5. Solvotermal synthesis of NiO, Ni and NiS nanoparticles.

    PubMed

    Gutierrez, Angel; Perpiñán, M Felisa; Sánchez, Ana E; Torralba, M Carmen

    2013-01-01

    Nanoparticles of NiO, Ni or NiS have been obtained by solvothermal decomposition of different molecular precursors. The influence of several parameters, such as temperature, reaction time, solvent or capping agent used, in the nature and size of the obtained nanoparticle has been studied. The characterization by XRD and TEM techniques indicates that the nanoparticles of NiO exhibit average sizes of 3-8 nm, while those of Ni are in the 30-40 nm range. This difference in size has been attributed to the presence of molecules of the capping agent (n-octylamine or oleic acid) that surround the NiO nanoparticles but were not present in the nickel ones. The capping agent is, thus, preventing the aggregation of the smallest nanoparticles. The use of either a S-donor capping agent (4-mercaptopyridine) or a precursor having S-donor ligands (diethyldithiocarbamate) have led to the formation of NiS with average sizes around 35 nm. The magnetic properties of the nanoparticles have been studied, showing superparamagnetism and magnetic hysteresis below the blocking temperature, which, in time, is dependent of the particle size.

  6. Synthesis and formation mechanism of Ag-Ni alloy nanoparticles at room temperature

    NASA Astrophysics Data System (ADS)

    Yan, Shi; Sun, Dongbai; Tan, Yuanyuan; Xing, Xueqing; Yu, Hongying; Wu, Zhonghua

    2016-11-01

    Ag-Ni nanoparticles were prepared with a chemical reduction method in the presence of polyvinylpyrrolidone (PVP) used as a stabilizing agent. During the synthesis of Ag-Ni nanoparticles, silver nitrate was used as the Ag+ source while nickel sulfate hexahydrate was used as Ni2+ source. Mixed solutions of Ag+ source and Ni2+ source were used as the precursors and sodium borohydride was used as the reducing agent. Five ratios of Ag+/Ni2+ (9:1, 3:1, 1:1, 1:3, and 1:9) suspensions were prepared in the corresponding precursors. Ag-Ni alloy nanoparticles were obtained with this method at room temperature. Scanning electronic microscope (SEM), energy dispersive spectrum (EDS), high resolution transmission electron microscope (HRTEM) were used to characterize the morphology, composition and crystal structure of the nanoparticles. The crystal structure was also investigated with X-ray diffraction (XRD). In all five Ag/Ni ratios, two kinds of particle structures were observed that are single crystal structure and five-fold twinned structure respectively. Free energy of nanoparticles with different crystal structures were calculated at each Ag/Ni ratio. Calculated results revealed that, with identical volume, free energy of single crystal particle is lower than multi-twinned particle and the difference becomes smaller with the increase of particle size; increase of Ni content will lead the increase of free energy for both structures. Formation of different crystal structures are decided by the structure of the original nuclei at the very early stage of the reduction process.

  7. Energy Levels and Intensity Parameters of Ho3(+) Ions in Y3Al5O12 and Lu3Al5O12

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Grew, Gary W.; Barnes, Norman P.

    2006-01-01

    The energy levels of the trivalent lanthanide Ho(sup 3+) in Y3Al5O12 (YAG) and Lu3Al5O12 (LuAG) have been measured. The Stark split levels for the first nine Ho manifolds in these materials have been measured, and the results have been fit to a free ion plus crystal field Hamiltonian to generate a theoretical set of energy levels. Crystal field parameters were varied to determine the best fit between experimental and theoretical energy levels. The energy levels of Ho:LuAG are seen to be very similar to those in Ho:YAG. However, subtle changes resulting from replacing Y(sup 3+) with Lu(sup 3+) in the garnet crystal Y3Al5O12 result in different transition wavelengths in LuAG. This has implications for Ho (sup 5)I7yields (sup 5)I8 lasers operating at approximately 2.1 micrometers. Although the energy levels have been measured previously in Ho:YAG, they have not been measured in Ho:LuAG. A comparison of the energy levels in Ho:YAG measured here show some discrepancies with previous measurements. The consistency of the energy level placement between Ho:LuAG and Ho:YAG indicate that the earlier studies may have some errors in the assignments. Finally, a Judd-Ofelt analysis is performed on Ho:YAG and Ho:LuAG to determine the intensity parameters, and thus, the transition probabilities and branching ratios of the first eight excited manifolds.

  8. s-process nucleosynthesis in massive stars: new results on {sup 60}Fe, {sup 62}Ni and {sup 64}Ni

    SciTech Connect

    Domingo-Pardo, C.; Dillmann, I.; Faestermann, T.; Korschinek, G.; Lachner, J.; Maiti, M.; Poutivtsev, M.; Rugel, R.; Giesen, U.; Nolte, R.; Goerres, J.; Uberseder, E.; Wiescher, M.; Heil, M.; Reifarth, R.; Horn, S.; Koechli, S.; Neuhausen, J.; Schumann, D.; Kaeppeler, F.

    2009-01-28

    The s process synthesizes the elements between Fe and Sr in massive stars during two major evolutionary stages, convective core He burning and C shell burning. This scenario implies fascinating consequences for the chemical evolution of the star. For instance, the neutron capture rate at each isotope can have a big influence on the production of many of the subsequent higher mass isotopes. Correspondingly, one needs to know the (n,{gamma}) cross sections of the involved isotopes with high accuracy in order to determine the abundance pattern reliably and to obtain a consistent picture of this stage. This contribution gives an overview on recent and future experiments for the Fe/Ni nucleosynthesis in massive stars. New results on {sup 60}Fe, {sup 62}Ni and {sup 64}Ni are reported. {sup 60}Fe is mostly produced during the short convective C shell burning phase, where peak densities of {approx}10{sup 11} cm{sup -3} are reached, prior to the SN explosion. The stellar (n,{gamma}) cross section of {sup 60}Fe could be measured with a 1 {mu}g sample obtained at PSI (Switzerland), which was sufficient for an activation measurement using the intense, quasi-stellar neutron field for a thermal energy of 25 keV at the Karlsruhe Van de Graaff accelerator. The FZK accelerator was also used for an activation of {sup 62}Ni, whereas in this case, the number of {sup 63}Ni nuclei produced were determined via accelerator mass spectroscopy at the Maier-Leibnitz-Laboratorium in Garching/Munich. The (n,{gamma}) cross section of {sup 64}Ni at a stellar temperature equivalent to 50 keV has been measured in a collaboration between FZK Karlsruhe and PTB Braunschweig. Finally, complementary time of flight measurements on the Fe and Ni isotopes over a broad energy range are planned at the white neutron source n lowbar TOF of CERN for the future campaign in 2009.

  9. Substance P Induces HO-1 Expression in RAW 264.7 Cells Promoting Switch towards M2-Like Macrophages

    PubMed Central

    Montana, Giovanna

    2016-01-01

    Substance P (SP) is a neuropeptide that mediates many physiological as well as inflammatory responses. Recently, SP has been implicated in the resolution of inflammation through induction of M2 macrophages phenotype. The shift between M1-like and M2-like, allowing the resolution of inflammatory processes, also takes place by means of hemeoxygenase-1 (HO-1). HO-1 is induced in response to oxidative stress and inflammatory stimuli and modulates the immune response through macrophages polarisation. SP induces HO-1 expression in human periodontal ligament (PDL), the latter potentially plays a role in cytoprotection. We demonstrated that SP promotes M2-like phenotype from resting as well as from M1 macrophages. Indeed, SP triggers the production of interleukine-10 (IL-10), interleukine-4 (IL-4) and arginase-1 (Arg1) without nitric oxide (NO) generation. In addition, SP increases HO-1 expression in a dose- and time-dependent manner. Here we report that SP, without affecting cell viability, significantly reduces the production of pro-inflammatory cytokines and enzymes, such as tumor necrosis factor-alpha (TNF-α), interleukine-6 (IL-6), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and ameliorates migration and phagocytic properties in LPS-stimulated RAW 264.7 cells. M2-like conversion required retention of NF-κB p65 into the cytoplasm and HO-1 induced expression. Silencing of the HO-1 mRNA expression reversed the induction of pro-inflammatory cytokines in RAW 264.7 stimulated by LPS and down-regulated anti-inflammatory hallmarks of M2 phenotype. In conclusion, our data show that SP treatment might be associated with anti-inflammatory effects in LPS-stimulated RAW 264.7 cells by suppressing NF-κB activation and inducing HO-1 expression. PMID:27907187

  10. Phase evolution and magnetic properties of HoIn{sub 3−x}Co{sub x}

    SciTech Connect

    Chen, Songlin; Guo, Yongquan He, Qiang

    2015-03-28

    The phase evolution of HoIn{sub 3−x}Co{sub x} exhibits the phase transformations from the original HoIn{sub 3} with cubic structure to the intermediated HoCo{sub 2}In with orthorhombic structure and to the final HoCo{sub 3} with rhombohedral structure. The corresponding magnetic states are found to closely associate with the structural phase transformation of HoIn{sub 3−x}Co{sub x}.With increasing Co contents, HoIn{sub 3−x}Co{sub x} are paramagnetic in region of x < 0.6, mixture of paramagnetic and ferromagnetic in range of 0.6 < x < 1.8, and ferromagnetic in range of 3 > x > 2.4 at room temperature, respectively. The field dependence of magnetization curves follows an equation of M=M{sub s}(1−a/H )+χH, where M{sub s} and χ are corresponding to the saturation moment and susceptibility; a is a parameter related to the external field. The fitting results show that the susceptibility increases with increasing Co contents and M{sub s} depends upon the Co content as well. It implies that the evolution of magnetic phases in HoIn{sub 3−x}Co{sub x} might originate from the change of exchange interaction from the one between the isolated Co spins and the surrounding conduction electrons in Co-poor regime to the one between Co-Co pairs mediated by the conduction electrons in Co-rich regime.

  11. Impact of Ho3+-doping on 13C dynamic nuclear polarization using trityl OX063 free radical

    PubMed Central

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kaur, Pavanjeet; Martins, André; Fidelino, Leila; Khemtong, Chalermchai; Song, Likai; Sherry, A. Dean

    2016-01-01

    We have investigated the effects of Ho-DOTA doping on the dynamic nuclear polarization (DNP) of [1-13C] sodium acetate using trityl OX063 free radical at 3.35 T and 1.2 K. Our results indicate that addition of 2 mM Ho-DOTA on 3 M [1-13C] sodium acetate sample in 1:1 v/v glycerol:water with 15 mM trityl OX063 improves the DNP-enhanced 13C solid-state nuclear polarization by a factor of around 2.7-fold. Similar to the Gd3+ doping effect on 13C DNP, the locations of the positive and negative 13C maximum polarization peaks in the 13C microwave DNP sweep are shifted towards each other with the addition of Ho-DOTA on the DNP sample. W-band electron spin resonance (ESR) studies have revealed that while the shape and linewidth of the trityl OX063 ESR spectrum was not affected by Ho3+-doping, the electron spin-lattice relaxation time T1 of trityl OX063 was prominently reduced at cryogenic temperatures. The reduction of trityl OX063 electron T1 by Ho-doping is linked to the 13C DNP improvement in light of the thermodynamic picture of DNP. Moreover, the presence of Ho-DOTA in the dissolution liquid at room temperature has negligible reduction effect on liquid-state 13C T1, in contrast to Gd3+-doping which drastically reduces the 13C T1. The results here suggest that Ho3+-doping is advantageous over Gd3+ in terms of preservation of hyperpolarized state—an important aspect to consider for in vitro and in vivo NMR or imaging (MRI) experiments where a considerable preparation time is needed to administer the hyperpolarized 13C liquid. PMID:27424954

  12. Abnormal Intermetallic Compound Evolution in Ni/Sn/Ni and Ni/Sn-9Zn/Ni Micro Solder Joints Under Thermomigration

    NASA Astrophysics Data System (ADS)

    Zhao, N.; Deng, J. F.; Zhong, Y.; Huang, M. L.; Ma, H. T.

    2017-04-01

    Interfacial reactions in Ni/Sn/Ni and Ni/Sn-9Zn/Ni micro solder joints during thermomigration (TM) have been studied by reflowing solder joints on a hot plate. Asymmetrical growth and transformation of interfacial intermetallic compounds (IMCs) were clearly observed. The growth of the Ni3Sn4 IMC in the Ni/Sn/Ni solder joints was always fast at the cold end and relatively slow at the hot end. Only asymmetrical growth of the Ni5Zn21 IMC in the Ni/Sn-9Zn/Ni solder joints occurred at the beginning because Zn was the dominant TM species; however, asymmetrical transformation of the Ni5Zn21 IMC also occurred under the combined effect of Zn depletion and Ni dissolution and migration, resulting in formation of a thin τ-phase layer at the hot end and a thick τ-phase/Ni5Zn21/τ-phase sandwich structure at the cold end. TM of Ni and Zn atoms was identified towards the cold end, being responsible for the abnormal IMC evolution. Addition of Zn was found to slow the TM-induced IMC growth and Ni dissolution.

  13. Knockout of ho-1 protects the striatum from ferrous iron-induced injury in a male-specific manner in mice

    PubMed Central

    Wang, Li-Fang; Yokoyama, Kazunari K.; Lin, Chih-Lung; Chen, Tzu-Yin; Hsiao, Hsiu-Wen; Chiang, Pei-Chi; Hsu, Chin

    2016-01-01

    Men have worse survival than premenopausal women after intracerebral hemorrhage (ICH). After ICH, overproduction of iron associated with induction of heme oxygenase-1 (HO-1) in brain was observed. Rodent ICH model using ferrous citrate (FC)-infusion into the striatum to simulate iron overload, showed a higher degree of injury severity in males than in females. However, the participation of HO-1 in sex-differences of iron-induced brain injury remains unknown. The present results showed a higher level of HO-1 expression associated with more severe injury in males compared with females after FC-infusion. Estradiol (E2) contributed to lower levels of FC-induced HO-1 expression in females compared with males. Heterozygote ho-1 KO decreased the levels of FC-induced injury severity, histological lesions, behavioral deficits, autophagy and autophagic cell death in the striatum of males but not in females. Moreover, ho-1 deficiency enhanced the neuroprotection by E2 only in males. These results suggested that over induction of HO-1 plays a harmful role in FC-induced brain injury in a male-specific manner. Suppression of HO-1 combined with E2 exhibits a synergistic effect on neuroprotection against FC-induced striatal injury in males. These findings open up the prospect for male-specific neuroprotection targeting HO-1 suppression for patients suffering from striatal iron overload. PMID:27198537

  14. Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho2Cu2O5 nanoplates prepared with a coordination-complex method

    NASA Astrophysics Data System (ADS)

    Guo, Rui; You, Junhua; Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng; Liu, Xuanwen

    2017-02-01

    Ho2Cu2O5 nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc)2(OAc)(H2O)3]·8H2O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N2 environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho2Cu2O5 formed through the diffusion of CuO into Ho2O3 particles. Cu2+ diffused faster than Ho3+ during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N2 atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho2Cu2O5 particles. The final Ho2Cu2O5 particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N2 played important roles in determining the morphology of the resulting Ho2Cu2O5. The catalytic oxidation activity of Ho2Cu2O5 samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.

  15. Nuclear Heme Oxygenase-1 (HO-1) Modulates Subcellular Distribution and Activation of Nrf2, Impacting Metabolic and Anti-oxidant Defenses*

    PubMed Central

    Biswas, Chhanda; Shah, Nidhi; Muthu, Manasa; La, Ping; Fernando, Amal P.; Sengupta, Shaon; Yang, Guang; Dennery, Phyllis A.

    2014-01-01

    With oxidative injury as well as in some solid tumors and myeloid leukemia cells, heme oxygenase-1 (HO-1), the anti-oxidant, anti-inflammatory, and anti-apoptotic microsomal stress protein, migrates to the nucleus in a truncated and enzymatically inactive form. However, the function of HO-1 in the nucleus is not completely clear. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor and master regulator of numerous antioxidants and anti-apoptotic proteins, including HO-1, also accumulates in the nucleus with oxidative injury and in various types of cancer. Here we demonstrate that in oxidative stress, nuclear HO-1 interacts with Nrf2 and stabilizes it from glycogen synthase kinase 3β (GSK3β)-mediated phosphorylation coupled with ubiquitin-proteasomal degradation, thereby prolonging its accumulation in the nucleus. This regulation of Nrf2 post-induction by nuclear HO-1 is important for the preferential transcription of phase II detoxification enzymes such as NQO1 as well as glucose-6-phosphate dehydrogenase (G6PDH), a regulator of the pentose phosphate pathway. Using Nrf2 knock-out cells, we further demonstrate that nuclear HO-1-associated cytoprotection against oxidative stress depends on an HO-1/Nrf2 interaction. Although it is well known that Nrf2 induces HO-1 leading to mitigation of oxidant stress, we propose a novel mechanism by which HO-1, by modulating the activation of Nrf2, sets an adaptive reprogramming that enhances antioxidant defenses. PMID:25107906

  16. Understanding and engineering of NiGe/Ge junction formed by phosphorus ion implantation after germanidation

    SciTech Connect

    Oka, Hiroshi Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2014-08-11

    Modulation of the effective electron Schottky barrier height (eSBH) of NiGe/Ge contacts induced by phosphorus ion implantation after germanide formation was investigated by considering local inhomogeneity in the eSBH. Systematic studies of NiGe/Ge contact devices having various germanide thicknesses and ion implantation areas indicated the threshold dopant concentration at the NiGe/Ge interface required for eSBH modulation and negligible dopant diffusion even at NiGe/Ge interface during drive-in annealing, leading to variation in the eSBH between the bottom and sidewall portions of the NiGe regions. Consequently, this method makes it possible to design source/drain contacts with low-resistivity Ohmic and ideal rectifying characteristics for future Ge-based transistors.

  17. Thermal plasma synthesis of Fe{sub 1−x}Ni{sub x} alloy nanoparticles

    SciTech Connect

    Raut, Suyog A.; Kanhe, Nilesh S.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2014-04-24

    Fe-Ni alloy nanoparticles are of great interest because of diverse practical applications in the fields such as magnetic fluids, high density recording media, catalysis and medicine. We report the synthesis of Fe-Ni nanoparticles via thermal plasma route. Thermal plasma assisted synthesis is a high temperature process and gives high yields of production. Here, we have used direct arc thermal plasma plume of 6kw as a source of energy at operating pressure 500 Torr. The mixture of Fe-Ni powder in required proportion (Fe{sub 1−x}Ni{sub x}; x=0.30, 0.32, 0.34, 0.36, 0.38 and 0.40) was made to evaporate simultaneously from the graphite anode in thermal plasma reactor to form Fe-Ni bimetallic nanoparticles. The as synthesized particles were characterized by X-Ray Diffraction (XRD), Thermo-Gravimetric Analysis/Differential Scanning Calorimtry (TGA/DSC)

  18. Measurement of 59Ni and 63Ni by accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; He, Ming; Ruan, Xiangdong; Xu, Yongning; Shen, Hongtao; Du, Liang; Xiao, Caijin; Dong, Kejun; Jiang, Shan; Yang, Xuran; Lan, Xiaoxi; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10-13 and 63Ni/Ni = 2 × 10-12, respectively.

  19. Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

    NASA Astrophysics Data System (ADS)

    Zhou, Dechun; Bai, Xuemei; Zhou, Hang

    2017-03-01

    Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10‑21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm‑1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

  20. Preparation of Ho(3+)/Tm(3+) Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm.

    PubMed

    Zhou, Dechun; Bai, Xuemei; Zhou, Hang

    2017-03-17

    Ho(3+)/Tm(3+) co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm(3+) doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho(3+) is greatly influenced by the doping concentration ratio of Ho(3+) to Tm(3+) and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10(-21) cm(2) when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm(-1), which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

  1. Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

    PubMed Central

    Zhou, Dechun; Bai, Xuemei; Zhou, Hang

    2017-01-01

    Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10−21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm−1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser. PMID:28303946

  2. Accessing Ni(III)-thiolate versus Ni(II)-thiyl bonding in a family of Ni-N2S2 synthetic models of NiSOD.

    PubMed

    Broering, Ellen P; Dillon, Stephanie; Gale, Eric M; Steiner, Ramsey A; Telser, Joshua; Brunold, Thomas C; Harrop, Todd C

    2015-04-20

    Superoxide dismutase (SOD) catalyzes the disproportionation of superoxide (O2(• -)) into H2O2 and O2(g) by toggling through different oxidation states of a first-row transition metal ion at its active site. Ni-containing SODs (NiSODs) are a distinct class of this family of metalloenzymes due to the unusual coordination sphere that is comprised of mixed N/S-ligands from peptide-N and cysteine-S donor atoms. A central goal of our research is to understand the factors that govern reactive oxygen species (ROS) stability of the Ni-S(Cys) bond in NiSOD utilizing a synthetic model approach. In light of the reactivity of metal-coordinated thiolates to ROS, several hypotheses have been proffered and include the coordination of His1-Nδ to the Ni(II) and Ni(III) forms of NiSOD, as well as hydrogen bonding or full protonation of a coordinated S(Cys). In this work, we present NiSOD analogues of the general formula [Ni(N2S)(SR')](-), providing a variable location (SR' = aryl thiolate) in the N2S2 basal plane coordination sphere where we have introduced o-amino and/or electron-withdrawing groups to intercept an oxidized Ni species. The synthesis, structure, and properties of the NiSOD model complexes (Et4N)[Ni(nmp)(SPh-o-NH2)] (2), (Et4N)[Ni(nmp)(SPh-o-NH2-p-CF3)] (3), (Et4N)[Ni(nmp)(SPh-p-NH2)] (4), and (Et4N)[Ni(nmp)(SPh-p-CF3)] (5) (nmp(2-) = dianion of N-(2-mercaptoethyl)picolinamide) are reported. NiSOD model complexes with amino groups positioned ortho to the aryl-S in SR' (2 and 3) afford oxidized species (2(ox) and 3(ox)) that are best described as a resonance hybrid between Ni(III)-SR and Ni(II)-(•)SR based on ultraviolet-visible (UV-vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectroscopies, as well as density functional theory (DFT) calculations. The results presented here, demonstrating the high percentage of S(3p) character in the highest occupied molecular orbital (HOMO) of the four-coordinate reduced form of NiSOD (Ni

  3. Activated AMPK boosts the Nrf2/HO-1 signaling axis—A role for the unfolded protein response

    PubMed Central

    Zimmermann, Kristin; Baldinger, Johannes; Mayerhofer, Barbara; Atanasov, Atanas G.; Dirsch, Verena M.; Heiss, Elke H.

    2015-01-01

    In light of the emerging interplay between redox and metabolic signaling pathways we investigated the potential cross talk between nuclear factor E2-related factor 2 (Nrf2) and AMP-activated kinase (AMPK), central regulators of the cellular redox and energy balance, respectively. Making use of xanthohumol (XN) as an activator of both the AMPK and the Nrf2 signaling pathway we show that AMPK exerts a positive influence on Nrf2/heme oxygenase (HO)-1 signaling in mouse embryonic fibroblasts. Genetic ablation and pharmacological inhibition of AMPK blunts Nrf2-dependent HO-1 expression by XN already at the mRNA level. XN leads to AMPK activation via interference with mitochondrial function and activation of liver kinase B1 as upstream AMPK kinase. The subsequent AMPK-mediated enhancement of the Nrf2/HO-1 response does not depend on inhibition of the mammalian target of rapamycin, inhibition of glycogen synthase kinase 3β, or altered abundance of Nrf2 (total and nuclear). However, reduced endoplasmic reticulum stress was identified and elaborated as a step in the AMPK-augmented Nrf2/HO-1 response. Overall, we shed more light on the hitherto incompletely understood cross talk between the LKB1/AMPK and the Nrf2/HO-1 axis revealing for the first time involvement of the unfolded protein response as an additional player and suggesting tight cooperation between signaling pathways controlling cellular redox, energy, or protein homeostasis. PMID:25843659

  4. Magnetic properties of aluminum-substituted R-T deuterides Ho6(Fe,Al)23Dz

    NASA Astrophysics Data System (ADS)

    Ostoréro, J.; Guillot, M.

    2007-05-01

    The influence of deuteration on the magnetic properties of aluminum-substituted R6Fe23-xAlxDz compounds (R =Ho,Y; x =0,5; z =10,16) has been investigated by magnetization measurements in the temperature range of 5-350K under a magnetic field of up to 90kOe. In comparison to the parent alloys, a large increase of the Fe magnetic moment μFe, much larger in yttrium than in holmium compounds, is observed upon deuteration. The magnetic exchange coupling NHo -Fe between the R and Fe sublattices was estimated from the slope of the field-induced transitions of the magnetization M isotherms in the vicinity of the compensation temperature Tcomp. The values of NHo -Fe and Tcomp decrease with insertion of deuterium, indicating a weakening in R -T coupling. The different results are analyzed within the frame of the Néel ferrimagnetic model taking into account the noncolinearity of the Ho and Fe sublattices magnetizations. The Ho-Ho and Fe-Fe magnetic interactions and the canting angle θ(θ ≪10°) are then determined. In Al-substituted deuterides, the presence of the rare-earth Ho "stabilizes" the ferrimagnetism.

  5. Re-entrant magneto-elastic transition in HoFe 4Ge 2: an XRPD study

    NASA Astrophysics Data System (ADS)

    Schobinger-Papamantellos, P.; Rodríguez-Carvajal, J.; Buschow, K. H. J.; Dooryhee, E.; Fitch, A. N.

    2002-09-01

    High-quality powder XRD data collected on the ESRF beam line BM16, are presented for the entire magnetically ordered regime ( T N=50 K) of the compound HoFe 4Ge 2. The data analysis reveals the occurrence of a re-entrant structural transition. The first symmetry breaking transition is of second order and occurs at the magnetic transition while the second transition occurs at lower temperatures at 15 K and is of first order: P4 2/ mnm (T c,T N=50 K)→ Cmmm (T IC=15 K)→ P4 2/ mnm. The phase diagram comprises three temperature regions: (a) the high temperature range with T> TN for the tetragonal P4 2/mnm phase; (b) the intermediate temperature range, 15 K< T< TN, with exclusively the orthorhombic phase Cmmm (c) the low temperature range, 4.2-15 K, where the Cmmm and P4 2/mnm phases coexist in strongly variable proportions. The P4 2/mnm phase reaches 73.6% at 4.2 K. This phenomenon is most likely due to competing magneto-elastic mechanisms involving the Ho crystal field anisotropy, the Ho-Ho, Ho-Fe and the Fe-Fe exchange interactions and their coupling with the lattice strains. The anisotropic peak broadening associated with the presence of microstructure effects has been refined by using the instrumental resolution and modeling the anisotropic strain.

  6. Antiferromagnetic order and the structural order-disorder transition in the Cd6Ho quasicrystal approximant

    SciTech Connect

    Kreyssig, Andreas; Beutier, Guillaume; Hiroto, Takanobu; Kim, Min Gyu; Tucker, Gregory S.; de Boissieu, Marc; Tamura, Ryuji; Goldman, Alan I.

    2014-09-22

    It has generally been accepted that the orientational ordering of the Cd4 tetrahedron within the Cd6 R quasicrystal approximants is kinetically inhibited for R = Ho, Er, Tm and Lu by steric constraints. Our high-resolution X-ray scattering measurements of the Cd6Ho quasicrystal approximant, however, reveal an abrupt (first-order) transition to a monoclinic structure below T S = 178 K for samples that have ‘aged’ at room temperature for approximately one year, reopening this question. Using X-ray resonant magnetic scattering at the Ho L 3-edge we have elucidated the nature of the antiferromagnetic ordering below T N = 8.5 K in Cd6Ho. The magnetic Bragg peaks are found at the charge forbidden H + K + L = 2n + 1 positions, referenced to the high-temperature body-centred cubic structure. In general terms, this corresponds to antiferromagnetic arrangements of the Ho moments on adjacent clusters in the unit cell as previously found for Cd6Tb.

  7. The large late-glacial Ho eruption of the Hudson volcano, southern Chile

    NASA Astrophysics Data System (ADS)

    Weller, D.; Miranda, C. G.; Moreno, P. I.; Villa-Martínez, R.; Stern, C. R.

    2014-06-01

    Lakes formed in the Aysén region of southern Chile after the retreat of mountain glaciers, established by ~17,900 calendar years before present (cal years BP) or earlier, contain numerous late-glacial and Holocene tephra layers derived from >70 eruptions of the volcanoes in the region, including Hudson, the southernmost in the Andean Southern Volcanic Zone (SVZ). Sediment cores from seven of these lakes contain an unusually thick late-glacial age tephra layer, which based on its distribution and bulk trace-element composition was derived from a large explosive eruption of Hudson volcano between 17,300 and 17,440 cal years BP and is termed Ho. In 13 cores from six of these lakes, each located ~100 km generally northeast of Hudson, the Ho tephra layer ranges between 50 and 88 cm in thickness, and contains pumice grains up to 2 cm in maximum diameter. Comparison with three previously documented large explosive Holocene Hudson eruptions (H1 at 7,750 cal years BP, H2 at 3,920 cal years BP, and H3 in 1991 AD) suggests that Ho was larger, with an estimated tephra volume of >20 km3, the largest post-glacial eruption documented for any volcano in the southern Andes and most likely responsible for the formation of the Hudson caldera. In total, Hudson has erupted ≥45 km3 of pyroclastic material in the last ~17,500 years, making it the most productive volcano in the southern Andes in terms of the total volume erupted since the beginning of deglaciation in the region. Chemical stratification is not seen in the waterlain Ho tephra, but these deposits are bi-modal, consisting of a much greater proportion of dark glassy basaltic-trachyandesite dense fragments and pumice, with glasses which range between 55 and 59 wt.% SiO2, along with volumetrically less-significant lighter-colored trachydacite pumice, with glass of 66 wt.% SiO2. In contrast, H1 products are trachyandesitic in composition, H2 ones are more felsic than H1, being composed essentially of trachydacite, and although

  8. Missing peroxy radical sources within a summertime ponderosa pine forest

    NASA Astrophysics Data System (ADS)

    Wolfe, G. M.; Cantrell, C.; Kim, S.; Mauldin, R. L., III; Karl, T.; Harley, P.; Turnipseed, A.; Zheng, W.; Flocke, F.; Apel, E. C.; Hornbrook, R. S.; Hall, S. R.; Ullmann, K.; Henry, S. B.; DiGangi, J. P.; Boyle, E. S.; Kaser, L.; Schnitzhofer, R.; Hansel, A.; Graus, M.; Nakashima, Y.; Kajii, Y.; Guenther, A.; Keutsch, F. N.

    2014-05-01

    Organic peroxy (RO2) and hydroperoxy (HO2) radicals are key intermediates in the photochemical processes that generate ozone, secondary organic aerosol and reactive nitrogen reservoirs throughout the troposphere. In regions with ample biogenic hydrocarbons, the richness and complexity of peroxy radical chemistry presents a significant challenge to current-generation models, especially given the scarcity of measurements in such environments. We present peroxy radical observations acquired within a ponderosa pine forest during the summer 2010 Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Organic Carbon Study (BEACHON-ROCS). Total peroxy radical mixing ratios reach as high as 180 pptv (parts per trillion by volume) and are among the highest yet recorded. Using the comprehensive measurement suite to constrain a near-explicit 0-D box model, we investigate the sources, sinks and distribution of peroxy radicals below the forest canopy. The base chemical mechanism underestimates total peroxy radicals by as much as a factor of 3. Since primary reaction partners for peroxy radicals are either measured (NO) or underpredicted (HO2 and RO2, i.e., self-reaction), missing sources are the most likely explanation for this result. A close comparison of model output with observations reveals at least two distinct source signatures. The first missing source, characterized by a sharp midday maximum and a strong dependence on solar radiation, is consistent with photolytic production of HO2. The diel profile of the second missing source peaks in the afternoon and suggests a process that generates RO2 independently of sun-driven photochemistry, such as ozonolysis of reactive hydrocarbons. The maximum magnitudes of these missing sources (~120 and 50 pptv min-1, respectively) are consistent with previous observations alluding to unexpectedly intense oxidation within forests. We conclude that a similar mechanism may underlie many

  9. Missing peroxy radical sources within a rural forest canopy

    NASA Astrophysics Data System (ADS)

    Wolfe, G. M.; Cantrell, C.; Kim, S.; Mauldin, R. L., III; Karl, T.; Harley, P.; Turnipseed, A.; Zheng, W.; Flocke, F.; Apel, E. C.; Hornbrook, R. S.; Hall, S. R.; Ullmann, K.; Henry, S. B.; DiGangi, J. P.; Boyle, E. S.; Kaser, L.; Schnitzhofer, R.; Hansel, A.; Graus, M.; Nakashima, Y.; Kajii, Y.; Guenther, A.; Keutsch, F. N.

    2013-12-01

    Organic peroxy (RO2) and hydroperoxy (HO2) radicals are key intermediates in the photochemical processes that generate ozone, secondary organic aerosol and reactive nitrogen reservoirs throughout the troposphere. In regions with ample biogenic hydrocarbons, the richness and complexity of peroxy radical chemistry presents a significant challenge to current-generation models, especially given the scarcity of measurements in such environments. We present peroxy radical observations acquired within a Ponderosa pine forest during the summer 2010 Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Organic Carbon Study (BEACHON-ROCS). Total peroxy radical mixing ratios reach as high as 180 pptv and are among the highest yet recorded. Using the comprehensive measurement suite to constrain a near-explicit 0-D box model, we investigate the sources, sinks and distribution of peroxy radicals below the forest canopy. The base chemical mechanism underestimates total peroxy radicals by as much as a factor of 3. Since primary reaction partners for peroxy radicals are either measured (NO) or under-predicted (HO2 and RO2, i.e. self-reaction), missing sources are the most likely explanation for this result. A close comparison of model output with observations reveals at least two distinct source signatures. The first missing source, characterized by a sharp midday maximum and a strong dependence on solar radiation, is consistent with photolytic production of HO2. The diel profile of the second missing source peaks in the afternoon and suggests a process that generates RO2 independently of sun-driven photochemistry, such as ozonolysis of reactive hydrocarbons. The maximum magnitudes of these missing sources (~ 120 and 50 pptv min-1, respectively) are consistent with previous observations alluding to unexpectedly intense oxidation within forests. We conclude that a similar mechanism may underlie many such observations.

  10. Missing Peroxy Radical Sources Within a Rural Forest Canopy

    NASA Technical Reports Server (NTRS)

    Wolfe, G. M.; Cantrell, C.; Kim, S.; Mauldin, R. L., III; Karl, T.; Harley, P.; Turnipseed, A.; Zheng, W.; Flocke, F.; Apel, E. C.; Hornbrook, R. S.; Hall, S. R.; Ullmann, K.; Henry, S. B.; DiGangi, J. P.; Boyle, E. S.; Kaser, L.; Schnitzhofer, R.; Hansel, A.; Graus, M.; Nakashima, Y.; Kajii, Y.; Guenther, A.; Keutsch, F. N.

    2013-01-01

    Organic peroxy (RO2) and hydroperoxy (HO2) radicals are key intermediates in the photochemical processes that generate ozone, secondary organic aerosol and reactive nitrogen reservoirs throughout the troposphere. In regions with ample biogenic hydrocarbons, the richness and complexity of peroxy radical chemistry presents a significant challenge to current-generation models, especially given the scarcity of measurements in such environments. We present peroxy radical observations acquired within a Ponderosa pine forest during the summer 2010 Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Organic Carbon Study (BEACHON-ROCS). Total peroxy radical mixing ratios reach as high as 180 pptv and are among the highest yet recorded. Using the comprehensive measurement suite to constrain a near-explicit 0-D box model, we investigate the sources, sinks and distribution of peroxy radicals below the forest canopy. The base chemical mechanism underestimates total peroxy radicals by as much as a factor of 3. Since primary reaction partners for peroxy radicals are either measured (NO) or under-predicted (HO2 and RO2, i.e. self-reaction), missing sources are the most likely explanation for this result. A close comparison of model output with observations reveals at least two distinct source signatures. The first missing source, characterized by a sharp midday maximum and a strong dependence on solar radiation, is consistent with photolytic production of HO2. The diel profile of the second missing source peaks in the afternoon and suggests a process that generates RO2 independently of sun-driven photochemistry, such as ozonolysis of reactive hydrocarbons. The maximum magnitudes of these missing sources (approximately 120 and 50 pptv min-1, respectively) are consistent with previous observations alluding to unexpectedly intense oxidation within forests. We conclude that a similar mechanism may underlie many such observations.

  11. The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle.

    PubMed

    Pecorella, Shelly R H; Potter, Jennifer V F; Cherry, Anne D; Peacher, Dionne F; Welty-Wolf, Karen E; Moon, Richard E; Piantadosi, Claude A; Suliman, Hagir B

    2015-10-15

    The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity.

  12. The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle

    PubMed Central

    Pecorella, Shelly R. H.; Potter, Jennifer V. F.; Cherry, Anne D.; Peacher, Dionne F.; Welty-Wolf, Karen E.; Moon, Richard E.; Suliman, Hagir B.

    2015-01-01

    The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity. PMID:26186946

  13. Ionized state of hydroperoxy radical-water hydrogen-bonded complex: (HO2-H2O)+.

    PubMed

    Joshi, Ravi; Ghanty, Tapan K; Naumov, Sergej; Mukherjee, Tulsi

    2007-12-27

    Ab initio molecular orbital calculations have been employed to characterize the structure and bonding of the (HO2-H2O)+ radical cation system. Geometry optimization of this system was carried out using unrestricted density functional theory in conjunction with the BHHLYP functional and 6-311++G(2df,2p) as well as 6-311++G(3df,3p) basis sets, the second-order Møller-Plesset perturbation (MP2) method with the 6-311++G(3df,3p) basis set, and the couple cluster (CCSD) method with the aug-cc-pVTZ basis set. The effect of spin multiplicity on the stability of the (HO2-H2O)+ system has been studied and also compared with that of oxygen. The calculated results suggest a proton-transferred hydrogen bond between HO2 and H2O in H3O3+ wherein a proton is partially transferred to H2O producing the O2...H3O+ structure. The basis set superposition error and zero-point energy corrected results indicate that the H3O3+ system is energetically more stable in the triplet state; however, the singlet state of H3O3+ is more stable with respect to its dissociation into H3O+ and singlet O2. Since the resulting proton-transferred hydrogen-bonded complex (O2...H3O+) consists of weakly bound molecular oxygen, it might have important implications in various chemical processes and aquatic life systems.

  14. Hořava Gravity in the Effective Field Theory formalism: From cosmology to observational constraints

    NASA Astrophysics Data System (ADS)

    Frusciante, Noemi; Raveri, Marco; Vernieri, Daniele; Hu, Bin; Silvestri, Alessandra

    2016-09-01

    We consider Hořava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Hořava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low- ℓ polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Hořava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

  15. The photochemistry of acetone in the upper troposphere: A source of odd-hydrogen radicals

    NASA Astrophysics Data System (ADS)

    McKeen, S. A.; Gierczak, T.; Burkholder, J. B.; Wennberg, P. O.; Hanisco, T. F.; Keim, E. R.; Gao, R.-S.; Liu, S. C.; Ravishankara, A. R.; Fahey, D. W.

    This paper summarizes measured photodissociation quantum yields for acetone in the 290-320 nm wavelength region for pressures and temperatures characteristic of the upper troposphere. Calculations combine this laboratory data with trace gas concentrations obtained during the NASA and NOAA sponsored Stratospheric Tracers of Atmospheric Transport (STRAT) field campaign, in which measurements of OH, HO2, odd-nitrogen, and other compounds were collected over Hawaii, and west of California during fall and winter of 1995/1996. OH and HO2 concentrations within 2 to 5 km layers just below the tropopause are ∼50% larger than expected from O3, CH4, and H2O chemistry alone. Although not measured during STRAT, acetone is inferred from CO measurements and acetone-CO correlations from a previous field study. These inferred acetone levels are a significant source of odd-hydrogen radicals that can explain a large part of the discrepancy in the upper troposphere. For lower altitudes, the inferred acetone makes a negligible contribution to HOx (HO+HO2), but influences NOy partitioning. A major fraction of HOx production by acetone is through CH2O formation, and the HOx discrepancy can also be explained by CH2O levels in the 20 to 50 pptv range, regardless of the source.

  16. Single-frequency, Q-switched Ho:YAG laser at room temperature injection-seeded by two F-P etalons-restricted Tm, Ho:YAG laser.

    PubMed

    Dai, T Y; Ju, Y L; Yao, B Q; Shen, Y J; Wang, W; Wang, Y Z

    2012-06-01

    We demonstrated a 1.91 μm pumped, injection-seeded Q-switched Ho:YAG laser operating at room temperature. By inserting two Fabry-Perot etalons into the laser cavity, single-frequency Tm, Ho:YAG seed lasing was achieved at a wavelength of 2090.9 nm, with a typical output power of 60 mW. Single-frequency, nearly transform-limited Q-switched operation of the Ho:YAG laser was achieved by injection seeding. The output energy of the single-frequency Q-switched pulse is 7.6 mJ, with a pulse width of 132 ns and a repetition rate of 100 Hz. We measured the pulse spectrum, half-width of which was 3.5 MHz, by a heterodyne technique.

  17. Three Gorges Dam alters the Changjiang (Yangtze) river water cycle in the dry seasons: Evidence from H-O isotopes.

    PubMed

    Deng, Kai; Yang, Shouye; Lian, Ergang; Li, Chao; Yang, Chengfan; Wei, Hailun

    2016-08-15

    As the largest hydropower project in the world, the Three Gorges Dam (TGD) has attracted great concerns in terms of its impact on the Changjiang (Yangtze) River and coastal marine environments. In this study, we measured or collected the H-O isotopic data of river water, groundwater and precipitation in the mid-lower Changjiang catchment during the dry seasons of recent years. The aim was to investigate the changes of river water cycle in response to the impoundment of the TGD. Isotopic evidences suggested that the mid-lower Changjiang river water was ultimately derived from precipitation, but dominated by the mixing of different water masses with variable sources and isotopic signals as well. The isotopic parameter "deuterium excess" (d-excess) yielded large fluctuations along the mid-lower mainstream during the initial stage of the TGD impoundment, which was inherited from the upstream water with inhomogeneous isotopic signals. However, as the reservoir water level rising to the present stage, small variability of d-excess was observed along the mid-lower mainstream. This discrepancy could be explained that the TGD impoundment had significantly altered the water cycle downstream the dam, with the rising water level increasing the residence time and enhancing the mixing of reservoir water derived from upstream. This eventually resulted in the homogenization of reservoir water, and thus small fluctuations of d-excess downstream the dam after the quasi-normal stage (2008 to present). We infer that the retention effect of large reservoirs has greatly buffered the d-excess natural variability of water cycle in large river systems. Nevertheless, more research attention has to be paid to the damming effect on the water cycle in the river, estuarine and coastal areas, especially during the dry seasons.

  18. Development of Multiply Sensitized Ho:YLF as a Laser Material

    DTIC Science & Technology

    1974-10-01

    SENSITIZED H0: YLF AS A LASER MATERIAL 7. AUTHORf«) E. P. Chicklis, R. C. Folweiler, C. 3. Naiman. D R. Gabbe, A. Linz, H. P. Jenssen 9...Phase Diagram of LiF-YF- View Through 7.5 cm of YLF Excitation Spectrum of aß- YLF Emission Spectra of Xe Flashlamps Levels of Er, Tm, Ho Tm...Page 86 88 89 92 93 95 104 108 109 111 112 115 116 LIST OF TABLES Table 3-1 3-2 3-3 4-1 Material and Optical Properties YLF vs

  19. AmeriFlux US-Ho2 Howland Forest (west tower)

    DOE Data Explorer

    Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Ho2 Howland Forest (west tower). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical Cycles 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.

  20. AmeriFlux US-Ho3 Howland Forest (harvest site)

    DOE Data Explorer

    Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Ho3 Howland Forest (harvest site). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical Cycles 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.

  1. AmeriFlux US-Ho1 Howland Forest (main tower)

    DOE Data Explorer

    Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Ho1 Howland Forest (main tower). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical Cycles 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.

  2. First-Principles Chemical Kinetic Modeling of Methyl trans-3-Hexenoate Epoxidation by HO2.

    PubMed

    Cagnina, S; Nicolle, A; de Bruin, T; Georgievskii, Y; Klippenstein, S J

    2017-03-09

    The design of innovative combustion processes relies on a comprehensive understanding of biodiesel oxidation kinetics. The present study aims at unraveling the reaction mechanism involved in the epoxidation of a realistic biodiesel surrogate, methyl trans-3-hexenoate, by hydroperoxy radicals using a bottom-up theoretical kinetics methodology. The obtained rate constants are in good agreement with experimental data for alkene epoxidation by HO2. The impact of temperature and pressure on epoxidation pathways involving H-bonded and non-H-bonded conformers was assessed. The obtained rate constant was finally implemented into a state-of-the-art detailed combustion mechanism, resulting in fairly good agreement with engine experiments.

  3. A dual-end-pumped Ho:YAG laser with a high energy output

    SciTech Connect

    Duan, X M; Cui, Zh; Dai, T Y; Yu, K K; Yao, B Q; Li, L J

    2015-08-31

    We report a high energy output from a Ho:YAG oscillator resonantly double-end pumped by Tm:YLF lasers at room temperature. The maximum pulse energy of 52.5 mJ was achieved at a pulse repetition rate of 100Hz and a pulse duration of 35.2 ns, corresponding to a peak power of approximately 1.5 MW. The output wavelength was 2090.7 nm with beam quality factor M{sup 2} ∼ 1.2. (lasers)

  4. Temperature dependence of the reactions of OH and HO2 with O3

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Tschuikow-Roux, E.

    1974-01-01

    Recent steady-state experiments involving the photolysis of O2-H2O mixtures at 1849 A conducted by DeMore (1973) have provided direct evidence for the catalytic cycle involving a reaction of ozone with OH in the first step and a reaction of ozone with HO2, which is produced in the first reaction, in the second step. The measurements of the rate constants for these reactions which had first been conducted at room temperature are now extended to the temperature range from 0 to 69 C.

  5. Complex magnetism of Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Lužnik, J.; Koželj, P.; Vrtnik, S.; Jelen, A.; Jagličić, Z.; Meden, A.; Feuerbacher, M.; Dolinšek, J.

    2015-12-01

    Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results show that the Ho-Dy-Y-Gd-Tb hexagonal HEA exhibits a rich and complex magnetic field-temperature (H ,T ) phase diagram, as a result of competition among the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the disorder-induced local random potential that favors spin glass-type spin freezing in random directions, the Zeeman interaction with the external field that favors spin alignment along the field direction, and the thermal agitation that opposes any spin ordering. Three characteristic temperature regions were identified in the (H ,T ) phase diagram between room temperature and 2 K. Within the upper temperature region I (roughly between 300 and 75 K), thermal fluctuations average out the effect of local random pinning potential and the spin system behaves as a pure system of compositionally averaged spins, undergoing a thermodynamic phase transition to a long-range ordered helical antiferromagnetic state at the Néel temperature TN=180 K that is a compositional average of the Néel temperatures of pure Tb, Dy, and Ho metals. Region II (between 75 and 20 K) is an intermediate region where the long-range periodic spin order "melts" and the random ordering of spins in the local random potential starts to prevail. Within the low-temperature region III (below 20 K), the spins gradually freeze in a spin glass configuration. The spin glass phase appears to be specific to the rare earths containing hexagonal HEAs, sharing

  6. New asymptotically Lifshitz black holes in Hořava gravity

    NASA Astrophysics Data System (ADS)

    Eling, Christopher

    2016-12-01

    We study asymptotically Lifshitz solutions with critical exponent z ≠1 in Hořava gravity in three and four spacetime dimensions. For z =2 and z =3 /2 , we find a novel class of numerical solutions with regular universal horizon but that are characterized by nonanalytic behavior near infinity. In the interior, inside the universal horizon, the unit timelike vector field associated with the preferred time foliation exhibits oscillatory behavior, qualitatively similar to that found earlier in asymptotically flat solutions. For z >2 , no solutions of this type appear to exist. We comment on potential applications to holographic Lifshitz dualities.

  7. Observation of large magnetocaloric effect in HoRu{sub 2}Si{sub 2}

    SciTech Connect

    Paramanik, Tapas Das, Kalipada; Das, I.

    2014-02-28

    Detailed magnetic, magnetotransport, and magnetocaloric measurements on HoRu{sub 2}Si{sub 2} have been performed. In this Letter, we report presence of spin reorientation transition below paramagnetic to antiferromagnetic transition temperature (T{sub N} = 19 K). Large magnetic entropy change 9.1 J/kg K and large negative magnetoresistance ∼21% in a magnetic field of 5 T has been observed around T{sub N}, which is associated with field induced spin-flip metamagnetic transition.

  8. The Resonantly Diode Pumped, Cryogenic Ho3+:YVO4 2.05-Micrometers Laser

    DTIC Science & Technology

    2011-10-01

    code) (301) 394-2007 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 iii Contents List of Figures iv 1. The Diode-pumped Holmium ...The Diode-pumped Holmium -doped Solid-state Laser Holmium (Ho) as a rare earth laser ion continues to gain the interest of the laser community as it...emits at eye-safe wavelengths around 2 µm and is useful for atmospheric sensing and medical applications. Diode-pumped holmium co-doped thulium (Tm

  9. Low temperature growth of graphene on Cu-Ni alloy nanofibers for stable, flexible electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Dong; Yin, Zong-You; Du, Ze-Hui; Yang, Yang; Zhu, Min-Min; Xie, Ling-Hai; Huang, Wei

    2014-04-01

    Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m-2.Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under

  10. Establishing the Dependence of [HO2]/[OH] on Temperature, Halogen Loading, O3, and NO(x) Based on in Situ Measurements from the NASA ER-2

    NASA Technical Reports Server (NTRS)

    Lanzendorf, E. J.; Hanisco, T. F.; Wennberg, P. O.; Cohen, R. C.; Stimpfle, R. M.; Anderson, J. G.; Gao, R. S.; Margitan, J. J.; Bui, T. P.

    2001-01-01

    In situ observations of OH and HO2 from the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA), Stratospheric TRacers of Atmospheric Transport (STRAT), and Polar Ozone Loss in the Arctic Region in Summer (POLARIS) NASA ER-2 field campaigns are used to examine the partitioning of HO(x) in the lower stratosphere (tropopause to approx.21 km) and upper troposphere (approx.10 km to tropopause). These measurements span a latitude range from 70degS to 90degN and a variety of atmospheric conditions as a result of seasonal changes and altitude. The response of the observed [HO2]/[OH] to changes in temperature, [03], [CO], [NO], [CIO], and [BrO] is investigated. The measured ratio is accurately described (approx.+/-10%) by a steady-state model constrained by the measured mixing ratios of O3, CO, NO, CIO, and BrO, where the model is valid for conditions of HO(x) cycling much faster than HO(x) production and loss. The concentration of HO2 depends on [OH], which, to first order, has been observed to be a simple function of the solar zenith angle in the lower stratosphere. The partitioning between OH and HO2 is controlled by the local chemistry between the HO, radicals and O3, CO, NO, CIO, and BrO. The response of [HO(x)] to changes in [NO(x)] and [O3] is demonstrated. Further observations are necessary to illustrate the response of HO(x) to changes in halogen concentrations. A quantitative understanding of [HO2]/[OH] is important, since many of the reactions that control this ratio are directly involved in catalytic removal of O3 in the lower stratosphere and production of O3 in the upper troposphere.

  11. Room-Temperature Synthesis of Thiostannates from {[Ni(tren)]2[Sn2S6]}n.

    PubMed

    Hilbert, Jessica; Näther, Christian; Weihrich, Richard; Bensch, Wolfgang

    2016-08-15

    The compound {[Ni(tren)]2[Sn2S6]}n (1) (tren = tris(2-aminoethyl)amine, C6H18N4) was successfully applied as source for the room-temperature synthesis of the new thiostannates [Ni(tren)(ma)(H2O)]2[Sn2S6]·4H2O (2) (ma = methylamine, CH5N) and [Ni(tren)(1,2-dap)]2[Sn2S6]·2H2O (3) (1,2-dap = 1,2-diaminopropane, C3H10N2). The Ni-S bonds in the Ni2S2N8 bioctahedron in the structure of 1 are analyzed with density functional theory calculations demonstrating significantly differing Ni-S bond strengths. Because of this asymmetry they are easily broken in the presence of an excess of ma or 1,2-dap immediately followed by Ni-N bond formation to N donor atoms of the amine ligands thus generating [Ni(tren)(amine)](2+) complexes. The chemical reactions are fast, and compounds 2 and 3 are formed within 1 h. The synthesis concept presented here opens hitherto unknown possibilities for preparation of new thiostannates.

  12. Single-crystalline δ-Ni2Si nanowires with excellent physical properties

    NASA Astrophysics Data System (ADS)

    Chiu, Wen-Li; Chiu, Chung-Hua; Chen, Jui-Yuan; Huang, Chun-Wei; Huang, Yu-Ting; Lu, Kuo-Chang; Hsin, Cheng-Lun; Yeh, Ping-Hung; Wu, Wen-Wei

    2013-06-01

    In this article, we report the synthesis of single-crystalline nickel silicide nanowires (NWs) via chemical vapor deposition method using NiCl2·6H2O as a single-source precursor. Various morphologies of δ-Ni2Si NWs were successfully acquired by controlling the growth conditions. The growth mechanism of the δ-Ni2Si NWs was thoroughly discussed and identified with microscopy studies. Field emission measurements show a low turn-on field (4.12 V/μm), and magnetic property measurements show a classic ferromagnetic characteristic, which demonstrates promising potential applications for field emitters, magnetic storage, and biological cell separation.

  13. Update of the BIPM comparison BIPM.RI(II)-K1.Ho-166m activity measurements of the radionuclide 166mHo for the PTB (Germany), with linked results for the EURAMET.RI(II)-K2.Ho-166m comparison

    NASA Astrophysics Data System (ADS)

    Ratel, G.; Michotte, C.; Courte, S.; Kossert, K.

    2015-01-01

    The PTB submitted directly to the SIR one ampoule of 166mHo prepared from a dilution of the solution distributed to four laboratories participating in the EURAMET.RI(II)-K2.Ho-166m comparison in 2013. No attempt to evaluate a new KCRV has been made and the usual procedure was applied to link the results of the comparison to the usual SIR entries through the PTB. One NMI used this K2 comparison to update its previous degree of equivalence which is older than 20 years. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the four remaining laboratories in the BIPM.RI(II)-K1.Ho166m comparison, the six laboratories in the regional comparison APMP.RI(II)-K2.Ho166m and the four laboratories in the regional EURAMET.RI(II)-K2.Ho-166m comparison. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  14. Carbon supported Pd-Ni-P nanoalloy as an efficient catalyst for ethanol electro-oxidation in alkaline media

    NASA Astrophysics Data System (ADS)

    Wang, Ye; Shi, Fei-Fei; Yang, Yao-Yue; Cai, Wen-Bin

    2013-12-01

    Carbon-supported well-dispersed Pd-Ni-P ternary catalyst targeted for ethanol oxidation reaction (EOR) in alkaline media is synthesized in a simple aqueous bath containing Pd(II) and Ni(II) salts with sodium hypophosphite as the reducing agent and the source for P and sodium citrate as the complexing agent. XRD analysis on the as-prepared Pd-Ni-P/C reveals that Ni shrinks while P expands the Pd lattice structure, and XPS measurement suggests different electronic effects of the two alloying elements on Pd. Cyclic voltammetry and chronoamperometry indicate that the Pd-Ni-P/C presents a remarkably higher electrocatalytic activity than the state-of-the-art Pd/C, Pd-P/C and Pd-Ni/C catalysts. This may be ascribed to the unique electronic, geometric and bifunctional effects involved in this ternary nanoalloy.

  15. Synthesis and Characterization of Pure Ni and Ni-Sn Intermetallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yakymovych, A.; Ipser, H.

    2017-02-01

    The present research focused on the synthesis of Ni and Ni-Sn nanoparticles via a chemical reduction method using hydrazine hydrate. The syntheses were performed applying highly purified water or diethylene glycol as solvent. The produced nanoparticles were characterized by scanning electron microscopy and powder X-ray diffraction. The as-synthesized Ni-Sn nanoparticles with nominal starting ratios Ni:Sn = 3:1, 3:2, and 3:4 consisted of different amounts of pure Ni and a low-temperature Ni3Sn2 phase. It was found that all synthesized nanopowders had a spherical shape with the largest average size for pure Ni and decreasing size for particles containing Sn. X-ray diffraction showed that all synthesized nanoparticles contained Ni and a low-temperature Ni3Sn2 phase independent of the initial molar ratio; while Ni3Sn and Ni3Sn4 could not be detected.

  16. Evaluation of HOx sources and cycling using measurement-constrained model calculations in a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated ecosystem

    NASA Astrophysics Data System (ADS)

    Kim, S.; Wolfe, G. M.; Mauldin, L.; Cantrell, C.; Guenther, A.; Karl, T.; Turnipseed, A.; Greenberg, J.; Hall, S. R.; Ullmann, K.; Apel, E.; Hornbrook, R.; Kajii, Y.; Nakashima, Y.; Keutsch, F. N.; DiGangi, J. P.; Henry, S. B.; Kaser, L.; Schnitzhofer, R.; Graus, M.; Hansel, A.

    2012-06-01

    We present a detailed analysis of OH and HO2 observations from the BEACHON (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen)-ROCS (Rocky Mountain Organic Carbon Study) 2010 field campaign at the Manitou Forest Observatory (MFO), which is a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated forest environment. A comprehensive suite of measurements was used to constrain primary production of OH via ozone photolysis, OH recycling from HO2, and OH chemical loss rates, in order to estimate the steady-state concentration of OH. In addition, the University of Washington Chemical Model (UWCM) was used to evaluate the performance of a near-explicit chemical mechanism. The diurnal cycle in OH from the steady-state calculations is in good agreement with measurement. A comparison between the photolytic production rates and the recycling rates from the HO2 + NO reaction shows that recycling rates are ~20 times faster than the photolytic OH production rates from ozone. Thus, we find that direct measurement of the recycling rates and the OH loss rates can provide accurate predictions of OH concentrations. More importantly, we also conclude that a conventional OH recycling pathway (HO2 + NO) can explain the observed OH levels in this non-isoprene environment. This is in contrast to observations in isoprene-dominated regions, where investigators have observed significant underestimation of OH and have speculated that unknown sources of OH are responsible. The highly-constrained UWCM calculation under-predicts observed HO2 by as much as a factor of 8. As HO2 maintains oxidation capacity by recycling to OH, UWCM underestimates observed OH by as much as a factor of 5. When the UWCM calculation is constrained by measured HO2, model calculated OH is in reasonable agreement with the observed OH levels. Conversely, constraining the model to observed OH only slightly reduces the model-measurement HO2 discrepancy, implying unknown HO2

  17. Preparation and property of duplex Ni-B-TiO2/Ni nano-composite coatings

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Jen; Wang, Yuxin; Shu, Xin; Tay, Seeleng; Gao, Wei; Shakoor, R. A.; Kahraman, Ramazan

    2015-03-01

    The duplex Nickel-Boron-Titania/Nickel (Ni-B-TiO2/Ni) coatings were deposited on mild steel by using two baths with Ni as the inner layer. TiO2 nanoparticles were incorporated into the Ni-B coatings as the outer layer by using solid particle mixing method. The microstructure, morphology and corrosion resistance of the duplex Ni-B-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the duplex interface was uniform and the adhesion between two layers was very good. The microhardness of duplex Ni-B-TiO2/Ni coating was much higher than the Ni coating due to the outer layer of Ni-B-TiO2 coating. The corrosion resistance of the duplex Ni-B-TiO2/Ni coating was also significantly improved comparing with single Ni-B coating. The Ni-B-10 g/L TiO2/Ni coating was found to have the best corrosion resistance among these duplex coatings. This type of duplex Ni-B-TiO2/Ni coating, with high hardness and good corrosion resistance properties, should be able to find broad applications under adverse environmental conditions.

  18. Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

    NASA Astrophysics Data System (ADS)

    Abdel-wahab, M. Sh.; Jilani, Asim; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-06-01

    Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV-Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and chemical state analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.

  19. The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria. Reply to a commentary.

    PubMed

    Lehninger, A L; Reynafarje, B; Hendler, R W; Shrager, R I

    1985-11-18

    Costa, L.E., Reynafarje, B. and Lehninger, A.L. [(1984) J. Biol. Chem. 259, 4802-4811] have reported 'second-generation' measurements of the H+/O ratio approaching 8.0 for vectorial H+ translocation coupled to succinate oxidation by rat liver mitochondria. In a Commentary in this Journal [Krab, K., Soos, J. and Wikström, M. (1984) FEBS Lett. 178, 187-192] it was concluded that the measurements of Costa et al. significantly overestimated the true H+/O stoichiometry. It is shown here that the mathematical simulation on which Krab et al. based this claim is faulty and that data reported by Costa et al. had already excluded the criticism advanced by Krab et al. Also reported are new data, obtained under conditions in which the arguments of Krab et al. are irrelevant, which confirm that the H+/O ratio for succinate oxidation extrapolated to level flow is close to 8.

  20. A 41-W ZnGeP₂ optical parametric oscillator pumped by a Q-switched Ho:YAG laser.

    PubMed

    Yao, Bao-Quan; Shen, Ying-Jie; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

    2014-12-01

    We reported a high-power ZnGeP₂ (ZGP) optical parametric oscillator (OPO) pumped by a Q-switched Ho:YAG laser. The maximum output power of the ZGP OPO was 41.2 W at 107.0 W incident Ho pump power, corresponding to a slope efficiency of 44.6%. The ZGP OPO produced 16-ns mid-IR pulse laser in the 3.74-3.98 μm and 4.38-4.76 μm spectral regions simultaneously. The beam quality was measured to be M²<4.37. The continuous wave maximum average output power of the Ho:YAG laser was 128 W, corresponding to a slope efficiency of 65.8%.